Cytogenetic status and oxidative DNA-damage induced by atorvastatin in human peripheral blood lymphocytes: Standard and Fpg-modified comet assay

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gajski, Goran; Garaj-Vrhovac, Vera; Orescanin, Visnja

2008-08-15

To investigate the genotoxic potential of atorvastatin on human lymphocytes in vitro standard comet assay was used in the evaluation of basal DNA damage and to investigate possible oxidative DNA damage produced by reactive oxygen species (ROS) Fpg-modified version of comet assay was also conducted. In addition to these techniques the new criteria for scoring micronucleus test were applied for more complete detection of baseline damage in binuclear lymphocytes exposed to atorvastatin 80 mg/day in different time periods by virtue of measuring the frequency of micronuclei, nucleoplasmic bridges and nuclear buds. All parameters obtained with the standard comet assay andmore » Fpg-modified comet assay were significantly higher in the treated than in control lymphocytes. The Fpg-modified comet assay showed a significantly greater tail length, tail intensity, and tail moment in all treated lymphocytes than did the standard comet assay, which suggests that oxidative stress is likely to be responsible for DNA damage. DNA damage detected by the standard comet assay indicates that some other mechanism is also involved. In addition to the comet assay, a total number of micronuclei, nucleoplasmic bridges and nuclear buds were significantly higher in the exposed than in controlled lymphocytes. Regression analyses showed a positive correlation between the results obtained by the comet (Fpg-modified and standard) and micronucleus assay. Overall, the study demonstrated that atorvastatin in its highest dose is capable of producing damage on the level of DNA molecule and cell.« less

Genotoxicity of 2-[2-(acetylamino)-4-[bis(2-hydroxyethyl)amino]-5-methoxyphenyl]-5-amino-7-bromo-4-chloro-2H-benzotriazole (PBTA-6) and 4-amino-3,3'-dichloro-5,4'-dinitro-biphenyl (ADDB) in goldfish (Carassius auratus) using the micronucleus test and the comet assay.

PubMed

Masuda, Shuichi; Deguchi, Yuya; Masuda, Yumi; Watanabe, Tetsushi; Nukaya, Haruo; Terao, Yoshiyasu; Takamura, Takeji; Wakabayashi, Keiji; Kinae, Naohide

2004-05-09

2-[2-(Acetylamino)-4-[bis(2-hydroxyethyl)amino]-5-methoxyphenyl]-5-amino-7-bromo-4-chloro-2H-benzotriazole (PBTA-6) and 4-amino-3,3'-dichloro-5,4'-dinitrobiphenyl (ADDB) are two compounds, which show strong mutagenicity toward bacteria, that have been identified as major mutagens in river water in Japan. In the present study, we examined the genotoxicity of PBTA-6 and ADDB in goldfish (Carassius auratus) by the micronucleus test and single-cell gel electrophoresis (comet assay). The frequencies of micronuclei in gill cells gradually increased until 96h after i.p. injection of PBTA-6 and ADDB at doses of 50mg/kg body weight, and then decreased 144h after injection. PBTA-6 induced micronuclei in gill cells dose-dependently at a dose range of 1-100mg/kg body weight, giving significantly high frequencies at doses of 50 and 100mg/kg body weight. On the other hand, no significant increase was observed in the peripheral erythrocytes of goldfish exposed to PBTA-6 or ADDB. In the comet assay, values of DNA tail moment and tail length in peripheral erythrocytes increased significantly until 6h after the i.p. injection of PBTA-6 (50mg/kg body weight), only to decrease by 9h after injection. Both the DNA tail moment and tail length were dose-dependently increased by injections of PBTA-6 at doses ranging from 1 to 50mg/kg. Significantly high values for tail moment and tail length were found in peripheral erythrocytes 3h after an i.p. injection of ADDB and persisted for up to 6h. These results show that both PBTA-6 and ADDB have genotoxic effects in goldfish.

Ulysses feels the brush of a comet's tail

NASA Astrophysics Data System (ADS)

2000-04-01

"Ulysses's prime task is to map the solar wind above the Sun's poles: it had not been looking for Hyakutake, which happened to be at its closest approach to the Sun on 1 May 1996, or any other comet", says Richard Marsden, ESA's Ulysses Project Scientist. "Ulysses was just in the right place at the right time." The two teams stumbled across the telltale signature of a comet quite independently when poring over old Ulysses data. Jones and colleagues found their evidence in magnetic field data: "the magnetic field lines were draped in a way that you'd expect in a comet's tail," says Jones. The other instrument team, lead by George Gloeckler from the University of Maryland, found their evidence when looking at the composition of the solar wind. Cometary tails are rich in oxygen and carbon compared with the solar wind, but depleted in nitrogen and neon. The Imperial College team identified Hyakutake as the source of the anomalous readings. On 1 May 1996, Ulysses was aligned with the Sun and the position Hyakutake had occupied eight days earlier, which Jones calculated was the time needed for material leaving the comet's nucleus to travel the distance to Ulysses. One of the most surprising aspects of the discovery is the length of Hyakutake's tail. Cometary experts had thought that comet tails eventually spread out and lose their integrity. "We found that the whole thing is preserved as an entity and doesn't spread out very much," says Gloeckler. "If it can persist as far as Ulysses, there's no reason to presume that it wouldn't continue to the edge of the heliosphere (the boundary about 100AU from the Sun between the solar wind and the interstellar medium)," says Jones. "This discovery makes us wonder whether Ulysses or other spacecraft have crossed a comet tail before. So we're going back to look again for other signatures. But it's probably a rare event," says Jones. The comet nucleus has to be in exactly the right position with respect to the Sun and the spacecraft for the tail to pass over the spacecraft at the right time - and the chances of that happening very often are probably small.

Comparative evaluation of genotoxicity by micronucleus assay in the buccal mucosa over comet assay in peripheral blood in oral precancer and cancer patients.

PubMed

Katarkar, Atul; Mukherjee, Sanjit; Khan, Masood H; Ray, Jay G; Chaudhuri, Keya

2014-09-01

Early detection and quantification of DNA damage in oral premalignancy or malignancy may help in management of the disease and improve survival rates. The comet assay has been successfully utilised to detect DNA damage in oral premalignant or malignancy. However, due to the invasive nature of collecting blood, it may be painful for many unwilling patients. This study compares the micronucleus (MN) assay in oral buccal mucosa cells with the comet assay in peripheral blood cells in a subset of oral habit-induced precancer and cancer patients. For this, MN assay of exfoliated epithelial cells was compared with comet assay of peripheral blood leucocytes among 260 participants, including those with oral lichen planus (OLP; n = 52), leukoplakia (LPK; n = 51), oral submucous fibrosis (OSF; n = 51), oral squamous cell carcinoma (OSCC; n = 54) and normal volunteers (n = 52). Among the precancer groups, LPK patients showed significantly higher levels of DNA damage as reflected by both comet tail length (P < 0.0001) and micronuclei (MNi) frequency (P = 0.0009). The DNA damage pattern in precancer and cancer patients was OLP < OSF < LPK < OSCC, and with respective oral habits, it was multiple habits > cigarette + khaini > cigarette smokers > areca + khaini > areca. There was no significant difference in the comet length and MNi frequency between males and females who had oral chewing habits. An overall significant correlation was observed between MNi frequency and comet tail length with r = 0.844 and P < 0.0001. Thus, the extent of DNA damage evaluation by the comet assay in peripheral blood cells is perfectly reflected by the MN assay on oral exfoliated epithelial cells, and MNi frequency can be used with the same effectiveness and greater efficiency in early detection of oral premalignant conditions. © The Author 2014. Published by Oxford University Press on behalf of the UK Environmental Mutagen Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Endogenous DNA damage and testicular germ cell tumors

PubMed Central

Cook, Michael B.; Sigurdson, Alice J.; Jones, Irene M.; Thomas, Cynthia B.; Graubard, Barry I.; Korde, Larissa; Greene, Mark H.; McGlynn, Katherine A.

2008-01-01

Testicular germ cell tumors (TGCT) are comprised of two histologic groups, seminomas and nonseminomas. We postulated that the possible divergent pathogeneses of these histologies may be partially explained by variable levels of net endogenous DNA damage. To test our hypothesis, we conducted a case-case analysis of 51 seminoma and 61 nonseminoma patients using data and specimens from the Familial Testicular Cancer study and the U.S. Radiologic Technologists cohort. A lymphoblastoid cell line was cultured for each patient and the alkaline comet assay was used to determine four parameters: tail DNA, tail length, comet distributed moment (CDM) and Olive tail moment (OTM). Odds ratios (OR) and 95% confidence intervals (95%CI) were estimated using logistic regression. Values for tail length, tail DNA, CDM and OTM were modeled as categorical variables using the 50th and 75th percentiles of the seminoma group. Tail DNA was significantly associated with nonseminoma compared to seminoma (OR50th percentile=3.31, 95%CI: 1.00, 10.98; OR75th percentile=3.71, 95%CI: 1.04, 13.20; p for trend=0.039). OTM exhibited similar, albeit statistically non-significant, risk estimates (OR50th percentile=2.27, 95%CI: 0.75, 6.87; OR75th percentile=2.40, 95%CI: 0.75, 7.71; p for trend=0.12) whereas tail length and CDM showed no association. In conclusion, the results for tail DNA and OTM indicate that net endogenous levels are higher in patients who develop nonseminoma compared with seminoma. This may partly explain the more aggressive biology and younger age-of-onset of this histologic subgroup compared with the relatively less aggressive, later-onset seminoma. PMID:18657195

Evaluation of the cytogenetic status of human lymphocytes after exposure to a high concentration of bee venom in vitro.

PubMed

Garaj-Vrhovac, Verica; Gajski, Goran

2009-03-01

Several studies have reported radioprotective, antimutagenic, anti-inflammatory, antinociceptive, and anticancer effects of bee venom both in the cell and the whole organism. The aim of this study was to assess the effects of a single high dose of 100 microg mL(-1) of whole bee venom in human lymphocytes in vitro over a variety of time spans (from 10 min to 24 h). After the treatment, we used the comet assay and micronucleus test to see the effect of bee venom on the cell. The comet assay confirmed that the venom damaged the DNA molecule. Tail length, tail intensity, tail moment showed a significant increase (P < 0.05). The percentage of long-tailed nuclei (LTN) with the tail length exceeding the 95th percentile also increased in a time-dependent manner. The micronucleus parameters (number of micronuclei, nucleoplasmic bridges, and nuclear buds) also showed a significant time-dependent increase (P < 0.05). This research indicates that high concentrations of bee venom can lead to cellular instability. Further research is needed to understand the mechanism of action of bee venom and its components in human cells and to see if this natural product may find application in medicine.

Mosaic CCD method: A new technique for observing dynamics of cometary magnetospheres

NASA Technical Reports Server (NTRS)

Saito, T.; Takeuchi, H.; Kozuba, Y.; Okamura, S.; Konno, I.; Hamabe, M.; Aoki, T.; Minami, S.; Isobe, S.

1992-01-01

On April 29, 1990, the plasma tail of Comet Austin was observed with a CCD camera on the 105-cm Schmidt telescope at the Kiso Observatory of the University of Tokyo. The area of the CCD used in this observation is only about 1 sq cm. When this CCD is used on the 105-cm Schmidt telescope at the Kiso Observatory, the area corresponds to a narrow square view of 12 ft x 12 ft. By comparison with the photograph of Comet Austin taken by Numazawa (personal communication) on the same night, we see that only a small part of the plasma tail can be photographed at one time with the CCD. However, by shifting the view on the CCD after each exposure, we succeeded in imaging the entire length of the cometary magnetosphere of 1.6 x 10(exp 6) km. This new technique is called 'the mosaic CCD method'. In order to study the dynamics of cometary plasma tails, seven frames of the comet from the head to the tail region were twice imaged with the mosaic CCD method and two sets of images were obtained. Six microstructures, including arcade structures, were identified in both the images. Sketches of the plasma tail including microstructures are included.

Double-stranded DNA breaks hidden in the neutral Comet assay suggest a role of the sperm nuclear matrix in DNA integrity maintenance

PubMed Central

Ribas-Maynou, J.; Gawecka, J.E.; Benet, J.; Ward, W.S.

2014-01-01

We used a mouse model in which sperm DNA damage was induced to understand the relationship of double-stranded DNA (dsDNA) breaks to sperm chromatin structure and to the Comet assay. Sperm chromatin fragmentation (SCF) produces dsDNA breaks located on the matrix attachment regions, between protamine toroids. In this model, epididymal sperm induced to undergo SCF can religate dsDNA breaks while vas deferens sperm cannot. Here, we demonstrated that the conventional neutral Comet assay underestimates the epididymal SCF breaks because the broken DNA ends remain attached to the nuclear matrix, causing the DNA to remain associated with the dispersion halo, and the Comet tails to be weak. Therefore, we term these hidden dsDNA breaks. When the Comet assay was modified to include an additional incubation with sodium dodecyl sulfate (SDS) and dithiothreitol (DTT) after the conventional lysis, thereby solubilizing the nuclear matrix, the broken DNA was released from the matrix, which resulted in a reduction of the sperm head halo and an increase in the Comet tail length, exposing the hidden dsDNA breaks. Conversely, SCF-induced vas deferens sperm had small halos and long tails with the conventional neutral Comet assay, suggesting that the broken DNA ends were not tethered to the nuclear matrix. These results suggest that the attachment to the nuclear matrix is crucial for the religation of SCF-induced DNA breaks in sperm. Our data suggest that the neutral Comet assay identifies only dsDNA breaks that are released from the nuclear matrix and that the addition of an SDS treatment can reveal these hidden dsDNA breaks. PMID:24282283

Double-stranded DNA breaks hidden in the neutral Comet assay suggest a role of the sperm nuclear matrix in DNA integrity maintenance.

PubMed

Ribas-Maynou, J; Gawecka, J E; Benet, J; Ward, W S

2014-04-01

We used a mouse model in which sperm DNA damage was induced to understand the relationship of double-stranded DNA (dsDNA) breaks to sperm chromatin structure and to the Comet assay. Sperm chromatin fragmentation (SCF) produces dsDNA breaks located on the matrix attachment regions, between protamine toroids. In this model, epididymal sperm induced to undergo SCF can religate dsDNA breaks while vas deferens sperm cannot. Here, we demonstrated that the conventional neutral Comet assay underestimates the epididymal SCF breaks because the broken DNA ends remain attached to the nuclear matrix, causing the DNA to remain associated with the dispersion halo, and the Comet tails to be weak. Therefore, we term these hidden dsDNA breaks. When the Comet assay was modified to include an additional incubation with sodium dodecyl sulfate (SDS) and dithiothreitol (DTT) after the conventional lysis, thereby solubilizing the nuclear matrix, the broken DNA was released from the matrix, which resulted in a reduction of the sperm head halo and an increase in the Comet tail length, exposing the hidden dsDNA breaks. Conversely, SCF-induced vas deferens sperm had small halos and long tails with the conventional neutral Comet assay, suggesting that the broken DNA ends were not tethered to the nuclear matrix. These results suggest that the attachment to the nuclear matrix is crucial for the religation of SCF-induced DNA breaks in sperm. Our data suggest that the neutral Comet assay identifies only dsDNA breaks that are released from the nuclear matrix and that the addition of an SDS treatment can reveal these hidden dsDNA breaks.

Application of the micronucleus test and comet assay in Trachemys callirostris erythrocytes as a model for in situ genotoxic monitoring.

PubMed

Zapata, Lina M; Bock, Brian C; Orozco, Luz Yaneth; Palacio, Jaime A

2016-05-01

Trachemys callirostris is a turtle species endemic to northern South America. In northern Colombia it occurs in the middle and lower Magdalena River drainage and its principal tributaries (lower Cauca and San Jorge rivers) and in other minor drainages such as the lower Sinú River. In recent years, industrial, agricultural, and mining activities have altered natural habitats in Colombia where this species occurs, and many of the pollutants released there are known to induce genetic alterations in wildlife species. The micronucleus test and comet assay are two of the most widely used methods to characterize DNA damage induced by physical and chemical agents in wildlife species, but have not been employed previously for genotoxic evaluations in T. callirostris. The goal of this study was to optimize these genotoxic biomarkers for T. callirostris erythrocytes in order to establish levels of DNA damage in this species and thereby evaluate its potential as a sentinel species for monitoring genotoxic effects in freshwater environments in northern Colombia. Both genotoxic techniques were applied on peripheral blood erythrocytes from 20 captive-reared T. callirostris individuals as a negative control, as well as from samples obtained from 49 individuals collected in Magangué (Magdalena River drainage) and 24 individuals collected in Lorica (Sinú River drainage) in northern Colombia. Negative control individuals exhibited a baseline frequency of micronuclei of 0.78±0.58 and baseline values for comet tail length and tail moment of 3.34±0.24µm and 10.70±5.5, respectively. In contrast, samples from both field sites exhibited significantly greater evidence of genotoxic effects for both tests. The mean MN frequencies in the samples from Magangué and Lorica were 8.04±7.08 and 12.19±12.94, respectively. The mean tail length for samples from Magangué and Lorica were 5.78±3.18 and 15.46±7.39, respectively. Finally, the mean tail moment for samples from Magangué and Lorica were 23.59±18.22 and 297.94±242.18, respectively. The frequency of micronuclei in the samples was positively related to comet tail length and tail moment. Thus, this study showed that both genotoxicity biomarkers may be applied to T. callirostris erythrocytes as a sentinel organism for assessing the effects of environmental pollutants in freshwater ecosystems in northern South America. Copyright © 2016 Elsevier Inc. All rights reserved.

In vitro assessment of genotoxic effects of electric arc furnace dust on human lymphocytes using the alkaline comet assay.

PubMed

Garaj-Vrhovac, Vera; Orescanin, Visnja; Ruk, Damir; Gajski, Goran

2009-02-15

In vitro genotoxic effects of leachates of electric arc furnace dust (EAFD) on human peripheral lymphocytes, assessed prior and following the treatment with a strong alkaline solution were investigated using the alkaline comet assay. Prior and following the treatment, lymphocytes were incubated with leachate of EAFD for 6 and 24 hours at 37 degrees C. Negative controls were also included. Mean values of the tail lengths established in the samples treated with the leachate stemming from the original dust for 6 and 24 hours, were 15.70 microm and 16.78 microm, respectively, as compared to 12.33 microm found in the control sample. Slight, but significant increase in the tail length was also found with the dust treated with a strong alkaline solution (13.37 microm and 13.60 microm). In case of high heavy metal concentrations (the extract of the original furnace dust), the incubation period was revealed to be of significance as well. The obtained results lead to the conclusion that alkaline comet assay could be used as a rapid, sensitive and low-cost tool when assessing genotoxicity of various waste materials, such as leachates of the electric arc furnace dust.

Genotoxicity of cadmium chloride in the marine gastropod Nerita chamaeleon using comet assay and alkaline unwinding assay.

PubMed

Sarkar, Anupam; Bhagat, Jacky; Ingole, Baban S; Rao, Durga P; Markad, Vijaykumar L

2015-02-01

This paper presents an evaluation of the genotoxic effects of cadmium chloride (CdCl2 ) on marine gastropod, Nerita chamaeleon following the technique of comet assay and the DNA alkaline unwinding assay (DAUA). In this study, the extent of DNA damage in gill cells of N. chamaeleon was measured after in vivo exposure to four different concentrations (10, 25, 50, and 75 µg/L) of CdCl2 . In vitro exposure of hydrogen peroxide (H2 O2 ; 1, 10, 25, and 50 µM) of the gill cells showed a significant increase in the percentage tail DNA, Olive tail moment, and tail length (TL). Significant changes in percentage tail DNA by CdCl2 exposure were observed in all exposed groups of snails with respect to those in control. Exposure to 75 µg/L of CdCl2 produced significant decrease in DNA integrity as measured by DAUA at all duration with respect to control. In vivo exposure to different concentrations of CdCl2 (10, 25, 50, and 75 µg/L) to N. chamaeleon showed considerable increase in DNA damage as observed by both alkaline comet assay and the DAUA. The extent of DNA damage in marine gastropods determined by the application of alkaline comet assay and DAUA clearly indicated the genotoxic responses of marine gastropod, N. chamaeleon to a wide range of cadmium concentration in the marine environment. © 2013 Wiley Periodicals, Inc.

The study of comets, part 1. [conference on photometry and spectrum analysis of Kohoutek comet and comet tails

NASA Technical Reports Server (NTRS)

Donn, B. (Editor); Mumma, M. J. (Editor); Jackson, W. M. (Editor); Ahearn, M. (Editor); Harrington, R. (Editor)

1976-01-01

Papers are presented dealing with observations of comets. Topic discussed include: photometry, polarimetry, and astrometry of comets; detection of water and molecular transitions in comets; ion motions in comet tails; determination of comet brightness and luminosity; and evolution of cometary orbits. Emphasis is placed on analysis of observations of comet Kohoutek.

Sperm DNA quality evaluated by comet assay and sperm chromatin structure assay in stallions after unilateral orchiectomy.

PubMed

Serafini, R; Varner, D D; Bissett, W; Blanchard, T L; Teague, S R; Love, C C

2015-09-15

Unilateral orchiectomy (UO) may interfere with thermoregulation of the remaining testis caused by inflammation surrounding the incision site, thus altering normal spermatogenesis and consequently sperm quality. Two measures of sperm DNA quality (neutral comet assay and the sperm chromatin structure assay [SCSA]) were compared before UO (0 days) and at 14, 30, and 60 days after UO to determine whether sperm DNA changed after a mild testis stress (i.e., UO). The percent DNA in the comet tail was higher at 14 and 60 days compared to 0 days (P < 0.05) after UO. All other comet tail measures (i.e., length, moment, migration) were higher at all time periods after UO compared to 0 days (P < 0.05). Two SCSA measures (mean-αt, mode-αt) increased at 14 days after UO (P < 0.05), whereas two measures (SD-αt and COMP-αt) did not change. This study identified a decrease in sperm DNA quality using both the neutral comet assay and the SCSA, which was not identified using traditional measures of sperm quality. Copyright © 2015 Elsevier Inc. All rights reserved.

Application of cytogenetic endpoints and comet assay on human lymphocytes treated with atorvastatin in vitro.

PubMed

Gajski, Goran; Garaj-Vrhovac, Vera

2008-01-01

This study investigated the genotoxic potential of atorvastatin on human lymphocytes using comet assay, structural chromosome aberrations (CA) and sister-chromatid exchange (SCE) analysis. Lymphocyte cultures were treated with a single drug at a concentration of 30.21 ng/mL. For comet assay, cells exposed to atorvastatin for 24 h, 48 h and 72 h were embedded in agarose slides, lysed with alkaline lysis solution and exposed to an electric field. DNA migrated within the agarose and formed comets whose length depends on the amount of DNA damage. For analysis of structural CA, cells were grown on medium for 48 h and for SCE analysis for 72 h. Structural CA did not induce significant damage to the genome, although a higher CA frequency was observed in cells treated with atorvastatin for 3 h, 20 h and 48 h than in control samples. Results of the SCE analysis did show statistically significant differences in the mean SCE number between atorvastatin-exposed and control human lymphocytes and between different exposure times. Comet assay also showed increased DNA damage caused in atorvastatin-exposed human lymphocytes than in corresponding control cells for exposure times of 24 h, 48 h and 72 h for the tail length and for 72 h for the tail moment. Results obtained in this study point to the significance of biological indicators providing information on the primary genome damage after long-term exposure, which can help to establish drug therapeutic concentrations that do not put patients with high blood cholesterol to a greater treatment-related risk.

Laboratory Study on Disconnection Events in Comets

NASA Astrophysics Data System (ADS)

Li, Yan-Fei; Li, Yu-Tong; Wang, Wei-Min; Yuan, Da-Wei; et al.

2018-01-01

When comets interacting with solar wind, straight and narrow plasma tails will be often formed. The most remarkable phenomenon of the plasma tails is the disconnection event, in which a plasma tail is uprooted from the comet's head and moves away from the comet. In this paper, the interaction process between a comet and solar wind is simulated by using a laser-driven plasma cloud to hit a cylinder obstacle. A disconnected plasma tail is observed behind the obstacle by optical shadowgraphy and interferometry. Our particle-in-cell simulations show that the diference in thermal velocity between ions and electrons induces an electrostatic field behind the obstacle. This field can lead to the convergence of ions to the central region, resulting in a disconnected plasma tail. This electrostatic field-induced model may be a possible explanation for the disconnection events of cometary tails.

Assessment of genotoxic effects of flumorph by the comet assay in mice organs.

PubMed

Zhang, T; Zhao, Q; Zhang, Y; Ning, J

2014-03-01

The present study investigated the genotoxic effects of flumorph in various organs (brain, liver, spleen, kidney and sperm) of mice. The DNA damage, measured as comet tail length (µm), was determined using the alkaline comet assay. The comet assay is a sensitive assay for the detection of genotoxicity caused by flumorph using mice as a model. Statistically significant increases in comet assay for both dose-dependent and duration-dependent DNA damage were observed in all the organs assessed. The organs exhibited the maximum DNA damage in 96 h at 54 mg/kg body weight. Brain showed maximum DNA damage followed by spleen > kidney > liver > sperm. Our data demonstrated that flumorph had induced systemic genotoxicity in mammals as it caused DNA damage in all tested vital organs, especially in brain and spleen.

Comet Halley: The Curtis Schmidts-Isla de Pascua observations

NASA Technical Reports Server (NTRS)

Miller, Freeman D.; Liller, William

1986-01-01

Halley's comet plasma tail disturbances and attendant tail phenomena were observed. Nearly simultaneous exposures with two telescopes serve to correlate information obtained with the two instruments. Photographs of 14 pre-Halley comets taken on 54 nights were examined with a view to cross-interpretation of phenomena seen in Halley with the earlier comets, as recorded on a homogenous collection of plates taken with the same instrument. The tail of Halley was highly active. This contrasts sharply with pre-Halley comets where undisturbed tails are the rule. During March and April, disturbances appeared in the tail of Halley at an average of 1 new distrubance every 3.7 days. It is considered that 10 of the 11 observed disturbances had common characteristics which allow them to be characterized as disconnections.

A tail like no other. The RPC-MAG view of Rosetta's tail excursion at comet 67P/Churyumov-Gerasimenko

NASA Astrophysics Data System (ADS)

Volwerk, Martin; Goetz, Charlotte; Richter, Ingo; Delva, Magda; Ostaszewski, Katharina; Schwingenschuh, Konrad; Glassmeier, Karl-Heinz

2018-06-01

Context. The Rosetta Plasma Consortium (RPC) magnetometer (MAG) data during the tail excursion in March-April 2016 are used to investigate the magnetic structure of and activity in the tail region of the weakly outgassing comet 67P/Churyumov-Gerasimenko (67P). Aims: The goal of this study is to compare the large scale (near) tail structure with that of earlier missions to strong outgassing comets, and the small scale turbulent energy cascade (un)related to the singing comet phenomenon. Methods: The usual methods of space plasma physics are used to analyse the magnetometer data, such as minimum variance analysis, spectral analysis, and power law fitting. Also the cone angle and clock angle of the magnetic field are calculated to interpret the data. Results: It is found that comet 67P does not have a classical draped magnetic field and no bi-lobal tail structure at this late stage of the mission when the comet is already at 2.7 AU distance from the Sun. The main magnetic field direction seems to be more across the tail direction, which may implicate an asymmetric pick-up cloud. During periods of singing comet activity the propagation direction of the waves is at large angles with respect to the magnetic field and to the radial direction towards the comet. Turbulent cascade of magnetic energy from large to small scales is different in the presence of singing as without it.

The path and surviving tail of a comet that fell into the sun

NASA Technical Reports Server (NTRS)

Sekanina, Z.

1982-01-01

A satisfactory orbital solution for Comet Howard-Koomen-Michels 1979 XI is found on the assumption that the comet's line of apsides coincided with that of the Kreutz sungrazing comet group. The derived perihelion distance then shows that this is the first known case of a comet falling into the sun. A dust tail that survived the comet is studied as a particle flow phenomenon controlled by no force other than solar gravity and solar radiation pressure. The tail's outline is interpreted in terms of an onset of dust production, a peak repulsive force on the particles, and a circumsolar dustfree zone due to particle sublimation. It is shown that the surviving debris consisted mostly of absorbing, submicron size particles in hyperbolic trajectories convex to the sun and curving toward the earth. The tail width may be a product of the interaction of charged dust in the tail with a complicated structure of the coronal magnetic field.

Extremely low-frequency electromagnetic fields cause DNA strand breaks in normal cells

PubMed Central

2014-01-01

Background Extremely low frequency electromagnetic fields aren’t considered as a real carcinogenic agent despite the fact that some studies have showed impairment of the DNA integrity in different cells lines. The aim of this study was evaluation of the late effects of a 100 Hz and 5.6 mT electromagnetic field, applied continuously or discontinuously, on the DNA integrity of Vero cells assessed by alkaline Comet assay and by cell cycle analysis. Normal Vero cells were exposed to extremely low frequency electromagnetic fields (100 Hz, 5.6 mT) for 45 minutes. The Comet assay and cell cycle analysis were performed 48 hours after the treatment. Results Exposed samples presented an increase of the number of cells with high damaged DNA as compared with non-exposed cells. Quantitative evaluation of the comet assay showed a significantly (<0.001) increase of the tail lengths, of the quantity of DNA in tail and of Olive tail moments, respectively. Cell cycle analysis showed an increase of the frequency of the cells in S phase, proving the occurrence of single strand breaks. The most probable mechanism of induction of the registered effects is the production of different types of reactive oxygen species. Conclusions The analysis of the registered comet indices and of cell cycle showed that extremely low frequency electromagnetic field of 100 Hz and 5.6 mT had a genotoxic impact on Vero cells. PMID:24401758

On the folding phenomenon of comet tail rays

NASA Astrophysics Data System (ADS)

Ershkovich, A. I.

1982-01-01

It is shown that the folding phenomenon of the comet tail rays is compatible with the Ferraro isorotation law if the comet tail magnetic field has no azimuthal component, that is, Bphi (the polar angle) equals zero. Considering electric drift due to convectional electric fields, a formula is obtained for the angular rate of a ray closure which reduces to that of Ness and Donn (1966) if the velocity profile across the tail is linear. The magnetic field B of approximately 20-40 gammas in the coma and less than about 10 gammas in the distant tail is estimated under typical solar wind conditions at 1 AU.

Exposure to pesticide mixtures and DNA damage among rice field workers.

PubMed

Varona-Uribe, Marcela Eugenia; Torres-Rey, Carlos H; Díaz-Criollo, Sonia; Palma-Parra, Ruth Marien; Narváez, Diana María; Carmona, Sandra Patricia; Briceño, Leonardo; Idrovo, Alvaro J

2016-01-01

This study describes the use of pesticides mixtures and their potential association with comet assay results in 223 rice field workers in Colombia. Thirty-one pesticides were quantified in blood, serum, and urine (15 organochlorines, 10 organophosphorus, 5 carbamates, and ethylenethiourea), and the comet assay was performed. Twenty-four (77.42%) pesticides were present in the workers. The use of the maximum-likelihood factor analysis identified 8 different mixtures. Afterwards, robust regressions were used to explore associations between the factors identified and the comet assay. Two groups of mixtures--α-benzene hexachloride (α-BHC), hexachlorobenzene (HCB), and β-BHC (β: 1.21, 95% confidence interval [CI]: 0.33-2.10) and pirimiphos-methyl, malathion, bromophos-methyl, and bromophos-ethyl (β: 11.97, 95% CI: 2.34-21.60)--were associated with a higher percentage of DNA damage and comet tail length, respectively. The findings suggest that exposure to pesticides varies greatly among rice field workers.

Use of statistical analysis to validate ecogenotoxicology findings arising from various comet assay components.

PubMed

Hussain, Bilal; Sultana, Tayyaba; Sultana, Salma; Al-Ghanim, Khalid Abdullah; Masoud, Muhammad Shahreef; Mahboob, Shahid

2018-04-01

Cirrhinus mrigala, Labeo rohita, and Catla catla are economically important fish for human consumption in Pakistan, but industrial and sewage pollution has drastically reduced their population in the River Chenab. Statistics are an important tool to analyze and interpret comet assay results. The specific aims of the study were to determine the DNA damage in Cirrhinus mrigala, Labeo rohita, and Catla catla due to chemical pollution and to assess the validity of statistical analyses to determine the viability of the comet assay for a possible use with these freshwater fish species as a good indicator of pollution load and habitat degradation. Comet assay results indicated a significant (P < 0.05) degree of DNA fragmentation in Cirrhinus mrigala followed by Labeo rohita and Catla catla in respect to comet head diameter, comet tail length, and % DNA damage. Regression analysis and correlation matrices conducted among the parameters of the comet assay affirmed the precision and the legitimacy of the results. The present study, therefore, strongly recommends that genotoxicological studies conduct appropriate analysis of the various components of comet assays to offer better interpretation of the assay data.

Indirect Solar Wind Measurements Using Archival Cometary Tail Observations

NASA Astrophysics Data System (ADS)

Zolotova, Nadezhda; Sizonenko, Yuriy; Vokhmyanin, Mikhail; Veselovsky, Igor

2018-05-01

This paper addresses the problem of the solar wind behaviour during the Maunder minimum. Records on plasma tails of comets can shed light on the physical parameters of the solar wind in the past. We analyse descriptions and drawings of comets between the eleventh and eighteenth century. To distinguish between dust and plasma tails, we address their colour, shape, and orientation. Based on the calculations made by F.A. Bredikhin, we found that cometary tails deviate from the antisolar direction on average by more than 10°, which is typical for dust tails. We also examined the catalogues of Hevelius and Lubieniecki. The first indication of a plasma tail was revealed only for the great comet C/1769 P1.

A worldwide photographic network for wide-field observations of Halley's Comet in 1985-1986

NASA Technical Reports Server (NTRS)

Niedner, M. B., Jr.; Brandt, J. C.; Rahe, J.

1982-01-01

A global network of ground-based observatories for the study of Halley's Comet in 1985/1986 is discussed. Recommendations are made with respect to improving coordination between reporting observatories, in order to ensure detailed imaging of such fast-generating cometary phenomena as plasma-tail knots, helices, disconnected tails, rays and condensations. A method for calibrating telescopes is considered by which well-studied objects will be photographed to provide references for images of Halley's Comet. This procedure is expected to reduce errors to approximately 0.05 mag. A coordinated study of Halley's Comet will provide important data on the physical properties of the Comet. Examples of the topics of study related to the plasma physics of the Comet's tail include: magnetic reconnection, rippling and tearing modes, kink instability, Kelvin-Helmholtz instability, and the flute instability.

Detection of ozone-induced DNA single strand breaks in murine bronchoalveolar lavage cells acutely exposed in vivo.

PubMed

Haney, J T; Connor, T H; Li, L

1999-04-01

Single-strand breaks (SSBs) in DNA have been used a biomarker of oxidative damage. The comet assay, also known as single-cell gel electrophoresis, was used to investigate the ability of ozone (O(3)) to induce DNA SSBs in murine bronchoalveolar lavage (BAL) cells. The comet assay is more sensitive than other techniques currently utilized for detecting SSBs and requires fewer cells. In the present study, 3 mice were exposed for 3 h to 0.25 ppm of O(3), and 3 to 0.5 ppm of O(3) for 3 h. Two air-exposed mice served as negative controls. All mice were euthanized 3 h after exposure, at which time BAL cells were recovered from the lungs and stained with ethidium bromide. BAL cells recovered from an air-exposed mouse were exposed to various concentrations of H(2)O(2) in vitro for 1 h at 4 degrees C. Excluding cells from the H(2)O(2) group (n = 25), 50 randomly selected BAL cells were graded by comet tail length into 1 of 4 categories: no damage (0 mm), low damage (1-10 mm), medium damage (11-30 mm), and high damage (31 + mm). The nonparametric Wilcoxon rank-sum test was used for statistical analysis, and p values lower than .05 were considered significant. The H(2)O(2) and the 0.25 and 0.5 ppm O3 groups showed statistically significant increases in DNA SSBs as compared to air-exposed controls. The results of this study indicate that (1) O(3) induces DNA strand breaks in murine BAL cells at 0.25 and 0.5 ppm, as evidenced by statistically significant increases in the length of comet tails for O(3)-exposed groups, and (2) the comet assay can be used to assess O(3)-induced SSBs for in vivo exposures. Therefore, it has the potential as a biomarker for in vivo oxidant exposures.

Evaluation of 8-hydroxy-2'-deoxyguanosine (8-OHdG) adduct levels and DNA strand breaks in human peripheral blood lymphocytes exposed in vitro to polycyclic aromatic hydrocarbons with or without animal metabolic activation.

PubMed

Isabel, Rodríguez-Romero María; Sandra, Gómez-Arroyo; Rafael, Villalobos-Pietrini; Carmen, Martínez-Valenzuela; Josefina, Cortés-Eslava; del Carmen, Calderón-Ezquerro María; Rocío, García-Martínez; Francisco, Arenas-Huertero; Elena, Calderón-Segura María

2012-04-01

The polycyclic aromatic hydrocarbons (PAHs) dibenzo(a,h)anthracene, benzo(ghi)perylene, benzo(b)fluoranthene and benzo(a)pyrene have been identified in urban air from Mexico City and some of them are classified as human carcinogens. In the present study, human peripheral blood lymphocytes were exposed in vitro to different concentrations of PAHs with (+S9) or without (-S9) metabolic activation. The genotoxic and cytotoxic effects of each PAH were examined with an alkaline comet assay and trypan blue dye exclusion, and oxidative DNA damage was determined via the detection of 8-hydroxy-2'-deoxyguanosine (8-OhdG) adduct levels by enzyme-linked immunosorbent assay (ELISA). The DNA damage was evaluated with two genotoxicity parameters: the frequency of comets and the comet tail length. Concentrations of 20, 40, 80, 160 and 320 µM DB(a,h)A-S9; 20, 40, 80, 160 and 240 µM B(ghi)P-S9; 20, 30, 40, 60 and 80 µM B(b)F-S9; and 80 µM B(a)P-S9 for 24 h induced a small but significant increase in the means of comet frequency, in the tail length and in the 8-oHDg levels in relation to the control (0.5% DMSO-S9). However, all PAHs+S9 produced a more significant increase in DNA strand breaks and the level of 8-OHdG compared with the control (0.5% DMSO+S9), with a concentration-effect relationship. The viability of lymphocytes exposed to all PAHs-S9 and PAHs+S9 was not modified compared with the control. The results of this study demonstrate that the comet and ELISA are rapid, suitable and sensitive methods to detect in vitro PAH-induced DNA damage in human peripheral lymphocytes.

High-sodium comet

NASA Astrophysics Data System (ADS)

Friebele, Elaine

In mid-April, astronomers in the Canary Islands discovered that Comet Hale-Bopp has a tail composed of sodium atoms, in addition to the commonly known ion and dust tails. Although sodium atoms have been seen at the centers of other comets, this is the first observation of a comet tail consisting of sodium.The discovery by Gabriele Cremonese of the Padova Astronomical Observatory in Italy and Don Pollaco of the Isaac Newton Group of telescopes at the Canary Islands, came from images of Hale-Bopp taken with a special wide-field camera fitted with a filter that isolates emission from sodium atoms. The sodium atoms are distributed over an enormous region in and around Hale-Bopp. It is not clear exactly how the sodium tail, which is 600,000 km wide and 50 million km long, was formed.

Using the EUV to Weigh a Sun-Grazing Comet as it Disappears in the Solar Corona

NASA Technical Reports Server (NTRS)

Pesnell, William Dean; Schrijiver, Carolus J.; Brown, John C.; Battams, Karl; Saint-Hilaire, Pascal; Hudson Hugh S.; Lui, Wei

2012-01-01

On July 6,2011, the Atmospheric Imaging Assembly (AlA) on the Solar Dynamics Observatory (SDO) observed a comet in most of its EUY passbands. The comet disappeared while moving through the solar corona. The comet penetrated to 0.146 solar radii ($\\simapprox.100,000 km) above the photosphere before its EUY faded. Before then, the comet's coma and a tail were observed in absorption and emission, respectively. The material in the variable tail quickly fell behind the nucleus. An estimate of the comet's mass based on this effect, one derived from insolation, and one using the tail's EUY brightness, all yield $\\sim 50$ giga-grams some 10 minutes prior to the end of its visibility. These unique first observations herald a new era in the study of Sun-grazing comets close to their perihelia and of the conditions in the solar corona and solar wind. We will discuss the observations and interpretation of the comet by SDO as well as the coronagraph observations from SOHO and STEREO. A search of the SOHO comet archive for other comets that could be observed in the SDO; AlA EUY channels will be described

What's New With Hale Bopp?

NASA Astrophysics Data System (ADS)

Shylaja, B. S.

1997-06-01

The comet Hale-Bopp has provided a great opportunity to astrophysicists. It is bright and it has been available for observations for a long period of time. A good number of large telescopes all over the northern hemisphere have been deployed for observations of this comet. Within a month of its discovery came the first result that the comet was quite active even when it was beyond Jupiter. Jets of gas and dust continued to stream out one after the other. This created the suspicion that the magnitude estimates may turn out to be only the limits rather than the actual values. The anxiety, so created disappeared only when the comet reached the visibility limits in late 1996. By the time it reached the perihelion on April 1, it was not fooling around anymore and kept up the promise of a 'civilized comet', the one that could be located without a finding chart. As is well known, the magnitude after the perihelion passage, would be slightly higher than the estimated value. The two-tail structure was first noticed a few months prior to the perihelion. The gradation in colour from blue of the ion tail to yellow of the dust tail was quite conspicuous. A simple binocular could easily resolve the two. Interestingly, just after the perihelion, there was a flare and the associated storm on the sun due to which a temporary increase in the solar wind particle density can occur. It would be extremely interesting to find the related effects on the tail, especially on the ion component. The solar and cometary physicists are (as on April 26th) eagerly looking forward to monitoring the changes. The ion tail has grown to about 15 degrees in the sky and is expected to get disrupted after the solar storm. On the other hand, the dust tail which grew to a full length of 45 degrees offered a glorious sight in the evening sky. The new moon at the time of perihelion enhanced the spectacle. In the middle of April quite suddenly, a third tail, a sharp yellow one, showed up. This was attributed to the presence of the neutral sodium component. Comets Halley and Hyakutake both had shown this type of tail structure. Last year comet Hyakutake made news for it was emitting soft X-rays, not a known cometary trait until then. Hale Bopp has followed suit. The LECS instrument onboard BeppoSAX spacecraft provided the news for the Netherlands Team. A thermal bremstrahlung model for 0.36 keV X-rays compares well with that of Hyakutake. This implies that the luminosity of the lines of carbon or oxygen in X-rays is less than 10 per cent of the continuum. Results on the coma structure and rotation of the nucleus of the Hale Bopp have started appearing already. A change in the direction of rotation during February 1997 has been observed. The list of molecules detected from spectroscopic investigations is ever increasing - H2O, HDO, OH H2O(+), CO, CO2, CO(+), HCO(+), H2S, SO, SO2, H2CS, OCS, CS, CH3OH (Plenty of alcohol!) H2CO, HCOOH, CH3CN, HNC, HC3N, HNCO, CN, NH3, NH2, NH2CHO, NHCH4, C2H2, C2H6, C3, C2, Na and many isotopes! The detection of deuterated water (HDO, heavy water) has provided a first measure of D/H ratio. Meir (University of Hawaii) and his team calculated HDO production rate of 4 x 1026 molecules/sec. The production rate of water is 2 x 1030 making the HDO/H2O ratio as 2 x 104. This makes Hale Bopp a "normal comet", akin to Halley and Hyakutake. With more than 3000 images on the web sites, the comet Hale Bopp is providing a wealth of information on the various aspects of the cometary science. With almost 300 tons of cometary material falling onto the earth every year and with the detection of frozen water on moon and mercury (obviously the sources have to be comets) the comets are believed to be promoters of life on earth.

Solar-wind velocity measurements from near-Sun comets C/2011 W3 (Lovejoy), C/2011 L4 (Pan-STARRS), and C/2012 S1 (ISON)

NASA Astrophysics Data System (ADS)

Ramanjooloo, Y.; Jones, G. H.; Coates, A.; Owens, M. J.; Battams, K.

2014-07-01

Since the mid-20th century, comets' plasma (type I) tails have been studied as natural probes of the solar wind [1]. Comets have induced magnetotails, formed through the draping of the heliospheric magnetic field by the velocity shear in the mass-loaded solar wind. These can be easily observed remotely as the comets' plasma tails, which generally point away from the Sun. Local solar-wind conditions directly influence the morphology and dynamics of a comet's plasma tail. During ideal observing geometries, the orientation and structure of the plasma tail can reveal large-scale and small-scale variations in the local solar-wind structure. These variations can be manifested as tail condensations, kinks, and disconnection events. Over 50 % of observed catalogued comets are sungrazing comets [2], fragments of three different parent comets. Since 2011, two bright new comets, C/2011 W3 [3] (from hereon comet Lovejoy) and C/2012 S1 [4] (hereon comet ISON) have experienced extreme solar-wind conditions and insolation of their nucleus during their perihelion passages, approaching to within 8.3×10^5 km (1.19 solar radii) and 1.9×10^6 km (2.79 solar radii) of the solar centre. They each displayed a prominent plasma tail, proving to be exceptions amongst the observed group of sungrazing comets. These bright sungrazers provide unprecedented access to study the solar wind in the heretofore unprobed innermost region of the solar corona. The closest spacecraft in-situ sampling of the solar wind by the Helios probes reached 0.29 au. For this study, we define a sungrazing comet as one with its perihelion within the solar Roche limit (3.70 solar radii). We also extend this study to include C/2011 L4 [5] (comet Pan-STARRS), a comet with a much further perihelion distance of 0.302 au. The technique employed in this study was first established by analysing geocentric amateur observations of comets C/2001 Q4 (NEAT) and C/2004 Q2 (Machholz) [7]. These amateur images, obtained with modern equipment and sensors, rival and sometimes arguably exceed the quality of professional images obtained only 2--3 decades ago. Multiple solar-wind velocity estimates were derived from each image and the results compared to observed and modelled near-Earth solar-wind data. Our unique analysis technique [Ramanjooloo et al., in preparation] allows us to determine the latitudinal variations of the solar wind, heliospheric current-sheet sector boundaries and the boundaries of transient features as a comet with an observable plasma tail probes the inner heliosphere. We present solar-wind velocity measurements derived from multiple observing locations of comets Lovejoy from the 14th -- 19th December 2011, comet Pan-STARRS during 11th -- 16th March 2013 and comet ISON from 12th -- 29th November 2013. Observations were gathered from multiple resources, from the SECCHI heliospheric imagers aboard STEREO A and B [8], the LASCO coronagraphs aboard SOHO [9], as well as ground-based amateur and professional observations coordinated by the CIOC. Overlapping observation sessions from the three spacecraft and ground-based efforts provided the perfect opportunity to use these comets as a diagnostic tool to understand solar-wind variability close to the Sun. We plan to compare our observations to results of suitable simulations [10] of plasma conditions in the corona and inner heliosphere during each of the comets' perihelion passage. The correlation of the solar-wind velocity distribution from different observing locations can provide clues towards the morphology and orientation of the plasma tail. We also attempt to determine the difficult-to-determine non-radial components of the measured solar-wind velocities.

Genotoxicity evaluation of HMG CoA reductase inhibitor rosuvastatin.

PubMed

Berber, Ahmet Ali; Celik, Mustafa; Aksoy, Hüseyin

2014-07-01

The genotoxic potential of rosuvastatin as one of the statin drugs was assessed by chromosomal aberrations (CAs), micronucleus (MN) and DNA damage by comet assay in the human peripheral blood lymphocytes. Rosuvastatin was used at concentrations of 0.0625, 0.125, 0.25, 0.5 and 1 µg/mL for these in vitro assays. In all assays, a negative and positive control were also included. CA frequencies were significantly increased in all concentrations at 24 hours and significantly increased in all concentrations except 0.0625 µg/mL at 48 hours, compared to the negative control. Rosuvastatin has a decreased mitotic index (MI) at 0.5- and 1-µg/mL concentrations at 24 hours and at 0.25, 0.5 and 1 µg/mL at 48 hours. A significant increase was observed for induction of MN in all treatments, compared to the negative control. Cytokinesis-block proliferation indices were not affected by treatments with rosuvastatin. In the comet assay, significant increases in comet tail length and tail moment were observed at 0.0625-, 0.5- and 1-µg/mL concentrations. Comet intensity was significantly increased in all concentrations except 0.0625 µg/mL. According to these results, rosuvastatin is cytotoxic and clastogenic/aneugenic in human peripheral lymphocytes. Further studies should be conducted in other test systems to evaluate the full genotoxic potential of rosuvastatin.

Disintegration of comet nuclei

NASA Astrophysics Data System (ADS)

Ksanfomality, Leonid V.

2012-02-01

The breaking up of comets into separate pieces, each with its own tail, was seen many times by astronomers of the past. The phenomenon was in sharp contrast to the idea of the eternal and unchangeable celestial firmament and was commonly believed to be an omen of impending disaster, especially for comets with tails stretching across half the sky. It is only now that we have efficient enough space exploration tools to see comet nuclei and even - in the particular case of small comet Hartley-2 in 2010 - to watch their disintegration stage. There are also other suspected candidates for disintegration in the vast family of comet nuclei and other Solar System bodies.

Genotoxicity of waterpipe smoke in buccal cells and peripheral blood leukocytes as determined by comet assay.

PubMed

Al-Amrah, Hadba Jar-Allah; Aboznada, Osama Abdullah; Alam, Mohammad Zubair; ElAssouli, M-Zaki Mustafa; Mujallid, Mohammad Ibrahim; ElAssouli, Sufian Mohamad

2014-12-01

Waterpipe smoke causes DNA damage in peripheral blood leukocytes and in buccal cells of smokers. To determine the exposure effect of waterpipe smoke on buccal cells and peripheral blood leukocytes in regard to DNA damage using comet assay. The waterpipe smoke condensates were analyzed by gas chromatography-mass spectrometry (GC-MS). The study was performed on 20 waterpipe smokers. To perform comet assay on bucaal cells of smokers, 10 µl of cell suspension was mixed with 85 µl of pre-warmed 1% low melting agarose, applied to comet slide and electrophoresed. To analyze the effect of smoke condensate in vitro, 1 ml of peripheral blood was mixed with 10 µl of smoke condensate and subjected for comet assay. The GC-MS analysis revealed the presence of 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4on, nicotine, hydroxymethyl furancarboxaldehyde and 3-ethoxy-4-hydroxybenzaldehyde in the smoke condensates. Waterpipe smoking caused DNA damage in vivo in buccal cells of smokers. The tail moment and tail length in buccal cells of smokers were 186 ± 26 and 456 ± 71, respectively, which are higher than control. The jurak and moassel smoke condensates were found to cause DNA damage in peripheral blood leukocytes. The moassel smoke condensate was more damaging. There is wide misconception that waterpipe smoking is not as harmful as cigarette smoking. This study demonstrated that waterpipe smoke induced DNA damage in exposed cells. Waterpipe smokes cause DNA damage in buccal cells. The smoke condensate of both jurak and moassel caused comet formation suggesting DNA damage in peripheral blood leukocytes.

Observations of Halley's Comet by the Solar Maximum Mission (SMM)

NASA Technical Reports Server (NTRS)

Niedner, M. B.

1986-01-01

Solar Maximum Mission coronagraph/polarimeter observations of large scale phenomena in Halley's Comet are discussed. Observations of the hydrogen coma with the UV spectrometer are considered. It is concluded that coronograph/polarimeter observations of the disconnection event, in which the entire plasma tail uproots itself from the head of the comet, is convected away in the solar wind at speeds in the 50 to 100 km/sec range (relative to the head), and is replaced by a plasma tail constructed from folding ion-tail rays, are the most interesting.

Jatropha curcas leaf and bark fractions protect against ultraviolet radiation-B induced DNA damage in human peripheral blood lymphocytes.

PubMed

Sundari, J; Selvaraj, R; Rajendra Prasad, N; Elumalai, R

2013-11-01

The present study is conducted to investigate the antioxidant potential of Jatropha curcas root bark extract (RB4 fraction) and leaf extract (L1 fraction), and to study their effects on UVB-radiation-induced DNA damage in cultured human blood lymphocytes. In this study, J. curcas showed strong antioxidant property in different free radical scavenging systems. Both the fractions effectively scavenged hydroxyl (OH), superoxide anion (O₂(·-)), 1,1-diphenyl-2-picrylhydrazyl (DPPH·) and 2,2-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid radical cation (ABTS(·+)) in a concentration-dependent manner. The IC₅₀ (Inhibitory Concentration 50) values of J. curcas fractions were compared to standard ascorbic acid used in this study. The antioxidant potential of a compound was directly proportional to the photoprotective effect. In this study, human peripheral blood lymphocytes (HPBL) were exposed to UVB-radiation and there was an increase in comet attributes (% tail DNA, tail length, tail movement and Olive tail moment). Jatropha curcas RB4 fraction and L1 fraction treatment before UVB-irradiation significantly decreased the % tail DNA, tail length, tail moment and Olive tail moment in irradiated HPBL. These results suggested that J. curcas exhibited strong antioxidant property and RB4 and L1 fractions protected UVB-radiation-induced DNA damage in HPBL. Copyright © 2013 Elsevier B.V. All rights reserved.

Evaluation of DNA Damage in Common Carp (Cyprinus carpio L.) by Comet Assay for Determination of Possible Pollution in Lake Mogan (Ankara)

PubMed Central

Çok, İsmet; Ulutaş, Onur Kenan; Okuşluk, Öncü; Durmaz, Emre; Demir, Nilsun

2011-01-01

Contamination of the aquatic environment with various concentrations of pollutants results in unexpected threats to humans and wildlife. The consequences of exposure and metabolism of pollutants/xenobiotics, especially carcinogens and mutagens, can be suitably assessed by investigating severe events, such as DNA damage; for example, DNA adducts and DNA strand breaks. One of the commonly used techniques to detect DNA damage in aquatic organisms is single-cell gel electrophoresis (comet assay). This study was carried out using Cyprinus carpio in order to identify the possible pollution in Lake Mogan, near Ankara, Turkey, where the city's sewer system and pesticides used in agriculture are believed to be the common causes of pollution. From the comet assay, the tail length (μm), tail intensity (%), and tail moment values of fish caught from Lake Mogan were found to be 31.10 ± 10.39, 7.77 ± 4.51, 1.50 ± 1.48, respectively, whereas for clean reference sites they were found to be 22.80 ± 1.08, 3.47 ± 1.59, 0.40 ± 0.51, respectively. The values are statistically different from each other (p < 0.0001, p < 0.0001, and p < 0.0013, respectively). These results indicate that Lake Mogan may be polluted with substances that have genotoxic effects and constitute an early warning for the lake system. Further detailed research is needed to establish the source of the pollution and the chemicals responsible. PMID:21805014

The International Cometary Explorer (ICE) mission to Comets Giacobini-Zinner and Halley

NASA Technical Reports Server (NTRS)

Brandt, J. C.

1986-01-01

Use of the ISEE-3 satellite (renamed ICE) to study the interaction between the solar wind and a cometary atmosphere by passing through the plasma tail by intercepting Comet Giacobini-Zinner on 11 September 1985 is described. Details of the targeting strategy are discussed. Additional scientific objectives following the tail intercept of Comet Giacobini-Zinner include the support of Comet Halley studies through the measurement of solar-wind conditions upstream of P/Halley in October 1985 and March 1986.

On the nature of the anti-tail of Comet Kohoutek /1973f/. I - A working model

NASA Technical Reports Server (NTRS)

Sekanina, Z.

1974-01-01

The model derived for the anti-tail of Comet Kohoutek describes it as a flat formation, confined essentially to the comet's orbit plane and composed of relatively heavy particles (mostly in the size range 0.1-1 mm) whose motions are controlled by solar gravity and solar radiation pressure. Almost all the material was produced by the comet before perihelion at a rate about an order of magnitude higher than for Comets Arend-Roland and Bennett. The latent heat of vaporization of the particle material is estimated at 40-45 kcal/mole or higher.

Comparison of the plasma tails of four comets: P/Halley, Okazaki-Levy-Rudenko, Austin, and Levy

NASA Technical Reports Server (NTRS)

Farnham, Tony L.; Meech, Karen J.

1994-01-01

Photographic and charge coupled device (CCD) plasma tail observations are compared for four comets: P/Halley (22 nights in 1985/1986), Okazaki-Levy-Rudenko 1989 XIX (1989 December 2), Austin 1990 V (nine nights in 1990), and Levy 1990 XX (two nights in 1991). We present a discussion of several image-processing techniques used to enhance the visibility of the plasma tail features in order to measure velocities, accelerations, and position angles. The data are used to assess the validity of various physical mechanisms proposed to explain plasma tail phenomena. Seven disconnection events were observed in the comet P/Halley data, two in the Austin data, and none for the other comets. Analysis of these data suggests that while the crossing of the solar neutral sheet (the sector boundary) is a prominent factor in the production of a disconnection event, it is likely that several mechanisms are at work. A sector boundary crossing has been ruled out as the cause of either the 1986 April 26 P/Halley disconnection or the 1990 May 5/6 Austin disconnection. The motions of the disconnection events, knots, and condensations in the tails were seen to increase from 30-60 km/s near the nucleus (within 10(exp 6) km) to 80-100 km/s at 10(exp 7) km, consistent with either bulk motion or Alfven waves. Distinguishing between the two cases is not possible with these data. It was found that although the tail ray rotation rate slows as the ray approaches the tail axis, it is not a good indicator of the solar wind speed. Historical plasma tail data are also used to look for clues as to why some comets form well-developed plasma tails and others do not.

Genotoxic effects of glyphosate or paraquat on earthworm coelomocytes.

PubMed

Muangphra, Ptumporn; Kwankua, Wimon; Gooneratne, Ravi

2014-06-01

The potential genotoxicity (nuclear anomalies, damage to single-strand DNA) and pinocytic adherence activity of two (glyphosate-based and paraquat-based) commercial herbicides to earthworm coelomocytes (immune cells in the coelomic cavity) were assessed. Coelomocytes were extracted from earthworms (Pheretima peguana) exposed to concentrations

Current ideas on the nature of comets

NASA Technical Reports Server (NTRS)

Rahe, J.

1984-01-01

The chemical composition, emission and line spectra, and structure of comet nuclei, cometary atmospheres, and comet tails are discussed. The role of ultraviolet and infrared astronomy in defining comets is examined.

Interaction of the plasma tail of comet Bradfield 1979L on 1980 February 6 with a possibly flare-generated solar-wind disturbance

NASA Technical Reports Server (NTRS)

Niedner, M. B., Jr.; Brandt, J. C.; Zwickl, R. D.; Bame, S. J.

1983-01-01

Solar-wind plasma data from the ISEE-3 and Helios 2 spacecraft were examined in order to explain a uniquely rapid 10 deg turning of the plasma tail of comet Bradfield 1979l on 1980 February 6. An earlier study conducted before the availability of in situ solar-wind data (Brandt et al., 1980) suggested that the tail position angle change occurred in response to a solar-wind velocity shear across the polar component changed by approximately 50 km/s. The present contribution confirms this result and further suggests that the comet-tail activity was caused by non-corotating, disturbed plasma flows probably associated with an Importance 1B solar flare.

Electron Tomography and Simulation of Baculovirus Actin Comet Tails Support a Tethered Filament Model of Pathogen Propulsion

PubMed Central

Mueller, Jan; Pfanzelter, Julia; Winkler, Christoph; Narita, Akihiro; Le Clainche, Christophe; Nemethova, Maria; Carlier, Marie-France; Maeda, Yuichiro; Welch, Matthew D.; Ohkawa, Taro; Schmeiser, Christian; Resch, Guenter P.; Small, J. Victor

2014-01-01

Several pathogens induce propulsive actin comet tails in cells they invade to disseminate their infection. They achieve this by recruiting factors for actin nucleation, the Arp2/3 complex, and polymerization regulators from the host cytoplasm. Owing to limited information on the structural organization of actin comets and in particular the spatial arrangement of filaments engaged in propulsion, the underlying mechanism of pathogen movement is currently speculative and controversial. Using electron tomography we have resolved the three-dimensional architecture of actin comet tails propelling baculovirus, the smallest pathogen yet known to hijack the actin motile machinery. Comet tail geometry was also mimicked in mixtures of virus capsids with purified actin and a minimal inventory of actin regulators. We demonstrate that propulsion is based on the assembly of a fishbone-like array of actin filaments organized in subsets linked by branch junctions, with an average of four filaments pushing the virus at any one time. Using an energy-minimizing function we have simulated the structure of actin comet tails as well as the tracks adopted by baculovirus in infected cells in vivo. The results from the simulations rule out gel squeezing models of propulsion and support those in which actin filaments are continuously tethered during branch nucleation and polymerization. Since Listeria monocytogenes, Shigella flexneri, and Vaccinia virus among other pathogens use the same common toolbox of components as baculovirus to move, we suggest they share the same principles of actin organization and mode of propulsion. PMID:24453943

Electron tomography and simulation of baculovirus actin comet tails support a tethered filament model of pathogen propulsion.

PubMed

Mueller, Jan; Pfanzelter, Julia; Winkler, Christoph; Narita, Akihiro; Le Clainche, Christophe; Nemethova, Maria; Carlier, Marie-France; Maeda, Yuichiro; Welch, Matthew D; Ohkawa, Taro; Schmeiser, Christian; Resch, Guenter P; Small, J Victor

2014-01-01

Several pathogens induce propulsive actin comet tails in cells they invade to disseminate their infection. They achieve this by recruiting factors for actin nucleation, the Arp2/3 complex, and polymerization regulators from the host cytoplasm. Owing to limited information on the structural organization of actin comets and in particular the spatial arrangement of filaments engaged in propulsion, the underlying mechanism of pathogen movement is currently speculative and controversial. Using electron tomography we have resolved the three-dimensional architecture of actin comet tails propelling baculovirus, the smallest pathogen yet known to hijack the actin motile machinery. Comet tail geometry was also mimicked in mixtures of virus capsids with purified actin and a minimal inventory of actin regulators. We demonstrate that propulsion is based on the assembly of a fishbone-like array of actin filaments organized in subsets linked by branch junctions, with an average of four filaments pushing the virus at any one time. Using an energy-minimizing function we have simulated the structure of actin comet tails as well as the tracks adopted by baculovirus in infected cells in vivo. The results from the simulations rule out gel squeezing models of propulsion and support those in which actin filaments are continuously tethered during branch nucleation and polymerization. Since Listeria monocytogenes, Shigella flexneri, and Vaccinia virus among other pathogens use the same common toolbox of components as baculovirus to move, we suggest they share the same principles of actin organization and mode of propulsion.

[Study on three kinds of gasoline oxygenates-induced DNA damage in mice fibroblasts].

PubMed

Song, Chonglin; Zhang, Zhifu; Chen, Xue; Zhang, Yanfeng; Wang, Chunhua; Liu, Keming

2002-10-01

To study DNA damage of three kinds of gasoline oxygenates. Single cell gel electrophoresis assay(Comet assay) was used to detect the damage effects of three gasoline oxygenates[methyl tertiary butyl ether(MTBE), ethanol anhydrous(EA) and dimethyl carbonate(DMC)] on DNA in L-929 mice fibroblasts. In certain concentation(37.500-150.000 mg/ml), MTBE could directly cause DNA damage of L-929 mice fibroblasts. There was obvious dose-effect relationship, i.e. when the concentration of MTBE was increased from 9.375 to 150.000 mg/ml, the comet rate also increased from 4% to 85%, and the length of comet tail changed correspondingly. The results of EA and DMC were negative. Under the condition of this experiment(150.000 mg/ml), MTBE could directly cause DNA damage while the effect of EA and DMC on DNA damage was not found.

Characteristics of the tail of Comet Giacobini-Zinner

NASA Technical Reports Server (NTRS)

Scarf, F. L.

1986-01-01

The physical structure and characteristics of the Comet Giacobini-Zinner tail are described. Variations in the vector B-field configuration, the electron distribution function, the energetic ion population, and the electromagnetic and electrostatic plasma wave spectra are analyzed. The ICE detected a two-lobe magnetic field configuration and a narrow central plasma sheet. Additional analyses proposed for the Giacobini-Zinner tail data are discussed.

[Endonuclease modified comet assay for oxidative DNA damage induced by detection of genetic toxicants].

PubMed

Zhao, Jian; Li, Hongli; Zhai, Qingfeng; Qiu, Yugang; Niu, Yong; Dai, Yufei; Zheng, Yuxin; Duan, Huawei

2014-03-01

The aim of this study was to investigate the use of the lesion-specific endonucleases-modified comet assay for analysis of DNA oxidation in cell lines. DNA breaks and oxidative damage were evaluated by normal alkaline and formamidopyrimidine-DNA-glycosylase (FPG) modified comet assays. Cytotoxicity were assessed by MTT method. The human bronchial epithelial cell (16HBE) were treated with benzo (a) pyrene (B(a)P), methyl methanesulfonate (MMS), colchicine (COL) and vincristine (VCR) respectively, and the dose is 20 µmol/L, 25 mg/ml, 5 mg/L and 0.5 mg/L for 24 h, respectively. Oxidative damage was also detected by levels of reactive oxygen species in treated cells. Four genotoxicants give higher cytotoxicity and no significant changes on parameters of comet assay treated by enzyme buffer. Cell survival rate were (59.69 ± 2.60) %, (54.33 ± 2.81) %, (53.11 ± 4.00) %, (51.43 ± 3.92) % in four groups, respectively. There was the direct DNA damage induced by test genotoxicants presented by tail length, Olive tail moment (TM) and tail DNA (%) in the comet assay. The presence of FPG in the assays increased DNA migration in treated groups when compared to those without it, and the difference was statistically significant which indicated that the clastogen and aneugen could induce oxidative damage in DNA strand. In the three parameters, the Olive TM was changed most obviously after genotoxicants treatment. In the contrast group, the Olive TM of B(a) P,MMS, COL,VCR in the contrast groups were 22.99 ± 17.33, 31.65 ± 18.86, 19.86 ± 9.56 and 17.02 ± 9.39, respectively, after dealing with the FPG, the Olive TM were 34.50 ± 17.29, 43.80 ± 10.06, 33.10 ± 12.38, 28.60 ± 10.53, increased by 58.94%, 38.48%, 66.86% and 68.21%, respectively (t value was 3.91, 3.89, 6.66 and 3.87, respectively, and all P < 0.05), and the correlation between Olive TM and reactive oxygen species was better than other parameters (r = 0.77, P < 0.05). This study indicates that FPG-comet assay appears more specific for detecting oxidative DNA damage induced by genotoxicants exposure, and the application of comet assay will be expanded. The endonuclease modified comet assay will be used widely in the toxicology and molecular epidemiology study.

Review: Observations of recent comets, ion tails

NASA Technical Reports Server (NTRS)

Brandt, J. C.

1976-01-01

Photographic plates of the moving structures in the cometary tail are examined. Several divergent explanations for the case of comet Kohoutek are presented. It is suggested that these hypotheses be tested by observing the motion of the material spectroscopically by means of the Doppler effect.

Multi-fluid model of a sun-grazing comet in the rapidly ionizing, magnetized low corona

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jia, Y.-D.; Russell, C. T.; Liu, W.

2014-11-20

Two Sun-grazing comets were recently imaged in the low solar corona by space telescopes in unprecedented detail, revealing a wide range of new phenomena. This sparked growing interest in the interaction of comets with the coronal plasma and magnetic field and their diagnostic potential as solar probes. However, interpretation of such rich observational data requires profound understanding of relevant physical processes in an unexplored regime. Here advanced numerical modeling can provide critical clues. To this end, we present a prototype, multi-fluid, magnetohydrodynamic model of a steady-state comet in the low solar corona. These simulation results are compared with previously modeledmore » comets in the solar wind environment. By inspecting their projection and column densities, we find a dominance of O{sup 6+} ions in the cometary tail, which can explain the observed extreme ultraviolet emission. The tail is found to be comparable to recent EUV images of these comets. In addition, the comet tail appears wider when the observer's line of sight is perpendicular rather than parallel to the local magnetic field. This is opposite to the trend in the interplanetary space permeated in the solar wind, because the ratio between dynamic pressure and magnetic pressure is an order of magnitude smaller than at 1 AU. On the other hand, we find that iron ions in the comet head build up to a density comparable to that of oxygen ions, but are unlikely to form a visible tail because of the shorter mean free paths of the neutrals.« less

High resolution integral-field spectroscopy of gas and ion distributions in the coma of Comet C/2012 S1 ISON

NASA Astrophysics Data System (ADS)

Schmidt, Carl

2016-02-01

Neutral and ion species in cometary comae exhibit significant differences in their spatial distributions. These distributions reflect the combined effects of sublimation, ion pickup, collisions, solar radiation pressure, photolysis scale lengths of any parent molecules, and photolysis of the species of interest. An image-slicer spectrograph (R ∼ 20,000) is used here to measure C2, NH2, Na, and H2O+ emission lines in Comet C/2012 S1 ISON's coma within a narrow spectral window spanning 5868-5926 Å. These species are mapped over a 1.6 × 2.7 arcmin field made up of 240 individual spectra. While prior cometary observations have found that peak column densities of these species appear either sunward or anti-sunward, ISON's coma was elongated several thousand kilometers along an axis perpendicular to its motion and the sunward vector. The peak brightness of each species was located within 5000 km of the dusty continuum concentration. ISON's water ion tail appeared distinctly broader than the neutral Na tail and no evidence is seen for an extended source of Na by dissociative recombination of a molecular ion. The Na D2/D1 ratio in the head is 1.49 ± 0.06 despite being optically thin, increasing to 1.93 ± 0.07 in the tail. The dust distribution falls off less steeply than the canonical inverse with distance from the nucleus and C2 and NH2 scale lengths indicate an extended source, possibly due to nucleus fragmentation.

The study of the physics of cometary nuclei

NASA Technical Reports Server (NTRS)

Whipple, F. L.; Marsden, B. G.; Sekanina, Z.

1975-01-01

Research in the area of split and hyperbolic comets, orbital calculations, and interstellar comets is discussed. Other topics discussed include the role of comets in galactic chemistry, gamma ray bursts, and predicted favorable visibility conditions for anomalous tails of comets.

Analysis of the Tail Structures of Comet 1P/Halley 1910 II

NASA Astrophysics Data System (ADS)

Voelzke, Marcos Rincon

2013-11-01

For the purpose of identifying, measuring, and correlating the morphological structures along the plasma tail of 1P/Halley, 886 images from September 1909 to May 1911 are analysed. These images are from the Atlas of Comet Halley 1910 II (DONN; RAHE; BRANDT, 1986).

Structures far from the head of comet Kohoutek. II - A discussion of the Swan Cloud of January 11 and of the general morphology of cometary plasma tails

NASA Technical Reports Server (NTRS)

Niedner, M. B., Jr.; Brandt, J. C.

1980-01-01

Photographs show that the 'Swan Cloud' observed in comet Kohoutek on January 11, 1974 was an advanced stage of a plasma tail disconnection event, of which the rejected tail appeared to decelerate as it receded from the head. The event commenced with the development of strong tail ray activity followed by the actual tail disconnection, the merging of the disconnected tail with the new tail to form the Swan and the formation of arcade loops in the space between closing tail rays. The observed morphological sequence is easily understood in the sector boundary model (Niedner et al., 1978), and the arcade loops are proposed to be reconnected flux tubes between oppositely polarized tail rays in the incipient new tail which followed the disconnection

Physical processes in comets

NASA Technical Reports Server (NTRS)

Whipple, F. L.; Huebner, W. F.

1976-01-01

The paper discusses physical processes in comets which involve solar and nuclear radial forces that affect the motions of gases and icy grains, gas-phase chemistry very close to the nuclei of large comets near the sun, sublimation of icy grains, dissociation of parent molecules into radicals and of radicals into atoms, and ionization by sunlight and collisions. The composition and dimensions of nuclei are examined along with variations in intrinsic brightness, the nature of volatiles, gas production rates in the coma, characteristics of icy grains in the coma, and the structure of streamers, ion tails, and dust tails. The structure of the coma is described in detail on the basis of spectroscopic observations of several comets. The origin of comets is briefly reviewed together with the relation of comets to earth, the interplanetary complex, and the interstellar medium. Desirable future observations are noted, especially by space missions to comets.

Comets: Gases, ices, grains and plasma

NASA Technical Reports Server (NTRS)

Wilkening, L. L.

1981-01-01

The program and abstracts of the 97 papers delivered at the colloquium are presented. Cometary nuclei, comet dust, the coma, ion tails, several comet missions, and cometary origin and evolution were discussed.

Monitoring of DNA breakage in embryonic stages of the African catfish Clarias gariepinus (Burchell, 1822) after exposure to lead nitrate using alkaline comet assay.

PubMed

Osman, Alaa G M; Mekkawy, Imam A; Verreth, Johan; Wuertz, Sven; Kloas, Werner; Kirschbaum, Frank

2008-12-01

Increasing lead contamination in Egyptian ecosystems and high lead concentrations in food items have raised concern for human health and stimulated studies on monitoring ecotoxicological impact of lead-caused genotoxicity. In this work, the alkaline comet assay was modified for monitoring DNA strand breakage in sensitive early life stages of the African catfish Clarias gariepinus. Following exposure to 100, 300, and 500 microg/L lead nitrate, DNA strand breakage was quantified in embryos at 30, 48, 96, 144, and 168 h post-fertilization (PFS). For quantitative analysis, four commonly used parameters (tail % DNA, %TDNA; head % DNA, %HDNA; tail length, TL; tail moment, TM) were analyzed in 96 nuclei (in triplicates) at each sampling point. The parameter %TDNA revealed highest resolution and lowest variation. A strong correlation between lead concentration, time of exposure, and DNA strand breakage was observed. Here, genotoxicity detected by comet assay preceded the manifested malformations assessed with conventional histology. Qualitative evaluation was carried out using five categories are as follows: undamaged (%TDNA < or = 10%), low damaged (10% < %TDNA < or = 25%), median damaged (25 < %TDNA < or = 50%), highly damaged (50 < %TDNA < or = 75%), and extremely damaged (%TDNA > 75%) nuclei confirming a dose and time-dependent shift towards increased frequencies of highly and extremely damaged nuclei. A protective capacity provided by a hardened chorion is a an interesting finding in this study as DNA damage in the prehatching stages 30 h-PFS and 48 h-PFS was low in all treatments (qualitative and quantitative analyses). These results clearly show that the comet assay is a sensitive tool for the detection of genotoxicity in vulnerable early life stages of the African catfish and is a method more sensitive than histological parameters for monitoring genotoxic effects. 2008 Wiley Periodicals, Inc.

Ancient Chinese Observations and Modern Cometary Models

NASA Astrophysics Data System (ADS)

Yeomans, D. K.

1995-12-01

Ancient astronomical observations by Chinese, Japanese, and Korean observers represent the only data source for discerning the long-term behavior of comets. The primary source material is derived from Chinese astrologers who kept a vigilant celestial watch in an effort to issue up-to-date astrological forecasts for the reigning emperors. Surprisingly accurate records were kept on cometary apparitions with careful notes being made of an object's position, motion, size, color, and tail length. For comets Halley, Swift-Tuttle, and Tempel-Tuttle, Chinese observations have been used to model their motions over two millennia and to infer their photometric histories. One general result is that active comets must achieve an apparent magnitude of 3.5 or brighter before they become obvious naked-eye objects. For both comets Halley and Swift-Tuttle, their absolute magnitudes and hence their outgassing rates, have remained relatively constant for two millennia. Comet Halley's rocket-like outgassing has consistently delayed the comet's return to perihelion by 4 days so that the comet's spin axis must have remained stable for at least two millennia. Although its outgassing is at nearly the same rate as Halley's, comet Swift-Tuttle's motion has been unaffected by outgassing forces; this comet is likely to be ten times more massive than Halley and hence far more difficult for rocket-like forces to push it around. Although the earliest definite observations of comet Tempel-Tuttle were in 1366, the associated Leonid meteor showers have been identified as early as A.D. 902. The circumstance for each historical meteor shower and storm have been used to guide predictions for the upcoming 1998-1999 Leonid meteor displays.

Two-Tailed Comet Assay (2T-Comet): Simultaneous Detection of DNA Single and Double Strand Breaks.

PubMed

Cortés-Gutiérrez, Elva I; Fernández, José Luis; Dávila-Rodríguez, Martha I; López-Fernández, Carmen; Gosálvez, Jaime

2017-01-01

A modification of the original comet assay was developed for the simultaneous evaluation of DNA single strand breaks (SSBs) and double strand breaks (DSBs) in human spermatozoa. The two-dimensional perpendicular tail comet assay (2T-comet) combines non-denaturing and denaturant conditions to the same sperm nucleoid. In this case, the species-specific deproteinized sperm is first subjected to an electrophoretic field under non-denaturing conditions to mobilize isolated free discrete DNA fragments produced from DSBs; this is then followed by a second electrophoresis running perpendicular to the first one but under alkaline conditions to produce DNA denaturation, exposing SSBs on the same linear DNA chain or DNA fragments flanked by DSBs. This procedure results in a two dimensional comet tail emerging from the core where two types of original DNA affected molecule can be simultaneously discriminated. The 2T-comet is a fast, sensitive, and reliable procedure to distinguish between single and double strand DNA damage within the same cell. It is an innovative method for assessing sperm DNA integrity, which has important implications for human fertility and andrological pathology. This technique may be adapted to assess different DNA break types in other species and other cell types.

Disintegration phenomena in Comet West

NASA Technical Reports Server (NTRS)

Sekanina, Z.

1976-01-01

Two peculiarities of Comet West, the multiple splitting of the nucleus as seen in telescope observations and the complex structure of the dust tail, are discussed. A method of analysis based on the premise that the observed rate of separation of a fragment from the principal nucleus is determined by the difference in effective solar attraction acting on the bodies is applied to investigate the motion of the four fragments that separated from the nucleus of Comet West. The predicted motion of the fragments is in good agreement with available observations. It is suggested that the 'synchronic' bands of the dust tail consist of tiny fragments from relatively large particles that burst after release from the comet. The unusual orientation of these bands and their high surface brightness relative to the diffuse tail are explained by a sudden increase in the particle acceleration and in the total scattering surface as the result of the disintegration of the larger particles.

Creating cometary models using ancient Chinese data

NASA Astrophysics Data System (ADS)

Yeomans, D. K.

For more than two millennia, Chinese court astronomers maintained a rather comprehensive record of cometary sightings. Owing to the significance of comets as portents for the reigning emperor, early sky watchers from China (as well as their counterparts from Korea and Japan) carefully noted each cometary apparition for the purpose of astrological predictions. The dates and corresponding celestial locations and motions were usually recorded and in some cases, the colors, coma sizes, and tail lengths were also noted. These ancient observations represent the only source of information available for modeling the long-term behavior of periodic comets. For comets Halley and Swift-Tuttle, Chinese records have been identified as far back as 240 B.C. and 69 B.C. respectively and these data have been used to define their long-term motions. As a result, heliocentric and geocentric distances for each Chinese sighting of these two comets can be computed and estimates can be made for each comet's intrinsic brightness at various observed returns. Although the earliest identified apparition of comet Tempel-Tuttle is A.D. 1366, the associated Leonid meteor showers were noted back to at least A.D. 902. The Leonid meteor stream is young in the sense that outstanding meteor displays occur only near the time of the parent comet's perihelion passages. The ancient Chinese records of the Leonid meteor showers and storms have been used to map the particle distribution around the parent comet and this information was used to guide predictions for the 1998-1999 Leonid meteor showers.

Study of sungrazing comets with space-based coronagraphs: new possibilities offered by METIS on boar Solar Orbiter

NASA Astrophysics Data System (ADS)

Bemporad, Alessandro

Thanks to the launch of SOHO in the end of 1995 and to the continuous monitoring of the white light (WL) corona offered by the LASCO coronagraphs, it was discovered that sungrazing comets are much more common than previously thought. More than 2500 comets have been discovered over about 17 years, hence slightly less than a comet every 2 days is observed by coronagraphs. The white light emission seen by SOHO/LASCO and more recently also by the STEREO/SECCHI instruments provides information not only on the comet orbits (hence on its origin), but also on the dust-tail formation, dust-tail disconnection, occurrence of nucleus fragmentation and nucleus disintegration processes. Very interestingly, a few sungrazing comets have been also observed in the UV spectra by the SOHO UV Coronagraph Spectrometer (UVCS) and the strong emission observed in the H I Lyman-alpha lambda 1216 Å line provided direct information also on the water outgassing rate, tail chemical composition, nucleus size and occurrence of nucleus fragmentations. Moreover, the UV cometary emission provides a new method to estimate physical parameters of the coronal plasma met by the comet (like electron density, proton temperature and solar wind velocity), in a way that these comets can be considered as “local probes” for the solar corona. Unique observations of comets will be provided in the next future by the METIS coronagraph on board the Solar Orbiter mission: METIS will contemporary observe the corona in WL and in UV (HI Lyman-alpha), hence will be a unique instrument to study at the same time the transiting comets and the solar corona being crossed by the comets. Previous results and new possibilities offered by METIS on these topics are summarized and discussed here.

Genotoxic effects of environmental endocrine disruptors on the aquatic insect Chironomus riparius evaluated using the comet assay.

PubMed

Martínez-Paz, Pedro; Morales, Mónica; Martínez-Guitarte, José Luis; Morcillo, Gloria

2013-12-12

Genotoxicity is one of the most important toxic endpoints in chemical toxicity testing and environmental risk assessment. The aim of this study was to evaluate the genotoxic potential of various environmental pollutants frequently found in aquatic environments and characterized by their endocrine disrupting activity. Monitoring of DNA damage was undertaken after in vivo exposures of the aquatic larvae of the midge Chironomus riparius, a model organism that represents an abundant and ecologically relevant macroinvertebrate, widely used in freshwater toxicology. DNA-induced damage, resulting in DNA fragmentation, was quantified by the comet assay after short (24 h) and long (96 h) exposures to different concentrations of the selected toxicants: bisphenol A (BPA), nonylphenol (NP), pentachlorophenol (PCP), tributyltin (TBT) and triclosan (TCS). All five compounds were found to have genotoxic activity as demonstrated by significant increases in all the comet parameters (%DNA in tail, tail length, tail moment and Olive tail moment) at all tested concentrations. Persistent exposure did not increase the extent of DNA damage, except for TCS at the highest concentration, but generally there was a reduction in DNA damage thought to be associated with the induction of the detoxification processes and repairing mechanisms. Comparative analysis showed differences in the genotoxic potential between the chemicals, as well as significant time and concentration-dependent variations, which most likely reflect differences in the ability to repair DNA damage under the different treatments. The present report demonstrates the sensitivity of the benthic larvae of C. riparius to these environmental genotoxins suggesting its potential as biomonitor organism in freshwater ecosystems. The results obtained about the DNA-damaging potential of these environmental pollutants reinforce the need for additional studies on the genotoxicity of endocrine active substances that, by linking genotoxic activity to other biological responses, could provide further understanding of adverse effects in aquatic environments. Copyright © 2013 Elsevier B.V. All rights reserved.

ACTIVITY OF 50 LONG-PERIOD COMETS BEYOND 5.2 au

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sárneczky, K.; Szabó, Gy. M.; Csák, B.

2016-12-01

Remote investigations of ancient matter in the solar system have traditionally been carried out through observations of long-period (LP) comets, which are less affected by solar irradiation than their short-period counterparts orbiting much closer to the Sun. Here we summarize the results of our decade-long survey of the distant activity of LP comets. We found that the most important separation in the data set is based on the dynamical nature of the objects. Dynamically new comets are characterized by a higher level of activity on average: the most active new comets in our sample can be characterized by Afρ valuesmore » >3–4, higher than those for our most active returning comets. New comets develop more symmetric comae, suggesting a generally isotropic outflow. In contrast to this, the comae of recurrent comets can be less symmetrical, ocassionally exhibiting negative slope parameters, which suggest sudden variations in matter production. The morphological appearance of the observed comets is rather diverse. A surprisingly large fraction of the comets have long, tenuous tails, but the presence of impressive tails does not show a clear correlation with the brightness of the comets.« less

On the mechanism of ray closure in comet tails

NASA Astrophysics Data System (ADS)

Ershkovich, A. I.

The folding phenomenon of comet tail rays is explained by means of an electric drift due to convectional electric fields. This mechanism results in an angular rate of closure which reduces to that obtained by Ness and Donn (1966) if the velocity profile across the tail is linear and the plasma conductivity is ideal. Observations of both the ray closure and the disconnection events point to the phenomenon of anomalous resistivity. Magnetic fields of about 30-40 gammas in the coma and of 10 gammas in the distant tail (at 1 AU) are estimated from the MHD momentum equation.

DNA damage in haemocytes and midgut gland cells of Steatoda grossa (Theridiidae) spiders exposed to food contaminated with cadmium.

PubMed

Stalmach, Monika; Wilczek, Grażyna; Wilczek, Piotr; Skowronek, Magdalena; Mędrzak, Monika

2015-03-01

The aim of this study was to assess the genotoxic effects of Cd on haemocytes and midgut gland cells of web-building spiders, Steatoda grossa (Theridiidae), exposed to the metal under laboratory conditions. Analyzes were conducted on adult females and males, fed for four weeks with cadmium-contaminated Drosophila hydei flies, grown on a medium suplemented with 0.25 mM CdCl2. The comet assay, providing a quantitative measure of DNA strand breaks, was used to evaluate the DNA damage caused by the metal. Cadmium content was measured in whole spider bodies by the AAS method. Metal body burden was significantly lower in females (0.25 µgg(-1) dry weight) than in males (3.03 µgg(-1) dry weight), suggesting that females may have more effective mechanisms controlling the uptake of metal, via the digestive tract, or its elimination from the body. Irrespectively of sex, spiders fed prey contaminated with cadmium showed significantly higher values of comet parameters: tail DNA (TDNA), tail length (TL) and olive tail moment (OTM), in comparison with the control. In midgut gland cells, the level of DNA damage was higher for males than females, while in haemocytes the genotoxic effect of cadmium was greater in females. The obtained results indicate that in spiders cadmium displays strong genotoxic effects and may cause DNA damage even at low concentrations, however the severity of damage seems to be sex- and internal organ-dependent. The comet assay can be considered a sensitive tool for measuring the deleterious effect of cadmium on DNA integrity in spiders. Copyright © 2014 Elsevier Inc. All rights reserved.

TURBULENCE IN THE SOLAR WIND MEASURED WITH COMET TAIL TEST PARTICLES

DOE Office of Scientific and Technical Information (OSTI.GOV)

DeForest, C. E.; Howard, T. A.; Matthaeus, W. H.

2015-10-20

By analyzing the motions of test particles observed remotely in the tail of Comet Encke, we demonstrate that the solar wind undergoes turbulent processing enroute from the Sun to the Earth and that the kinetic energy entrained in the large-scale turbulence is sufficient to explain the well-known anomalous heating of the solar wind. Using the heliospheric imaging (HI-1) camera on board NASA's STEREO-A spacecraft, we have observed an ensemble of compact features in the comet tail as they became entrained in the solar wind near 0.4 AU. We find that the features are useful as test particles, via mean-motion analysismore » and a forward model of pickup dynamics. Using population analysis of the ensemble's relative motion, we find a regime of random-walk diffusion in the solar wind, followed, on larger scales, by a surprising regime of semiconfinement that we attribute to turbulent eddies in the solar wind. The entrained kinetic energy of the turbulent motions represents a sufficient energy reservoir to heat the solar wind to observed temperatures at 1 AU. We determine the Lagrangian-frame diffusion coefficient in the diffusive regime, derive upper limits for the small scale coherence length of solar wind turbulence, compare our results to existing Eulerian-frame measurements, and compare the turbulent velocity with the size of the observed eddies extrapolated to 1 AU. We conclude that the slow solar wind is fully mixed by turbulence on scales corresponding to a 1–2 hr crossing time at Earth; and that solar wind variability on timescales shorter than 1–2 hr is therefore dominated by turbulent processing rather than by direct solar effects.« less

Icy Visitor from Beyond

NASA Image and Video Library

2010-10-05

This visitor from deep space, seen here by NASA Wide-field Infrared Survey Explorer, is comet Hartley 2, the destination for NASA EPOXI mission. The comet tail is seen here as a fuzzy streak to the right of the comet.

ScienceCast 96: Sunset Comet

NASA Image and Video Library

2013-03-14

Comet Pan-STARRS has survived its encounter with the sun and is now emerging from twilight in the sunset skies of the northern hemisphere. A NASA spacecraft monitoring the comet has beamed back pictures of a wild and ragged tail.

Light-curve analysis of KOI 2700b: the second extrasolar planet with a comet-like tail

NASA Astrophysics Data System (ADS)

Garai, Z.

2018-03-01

Context. The Kepler object KOI 2700b (KIC 8639908b) was discovered recently as the second exoplanet with a comet-like tail. It exhibits a distinctly asymmetric transit profile, likely indicative of the emission of dusty effluents and reminiscent of KIC 12557548b, the first exoplanet with a comet-like tail. Aim. The scientific goal of this work is to verify the disintegrating-planet scenario of KOI 2700b by modeling its light curve and to put constraints on various tail and planet properties, as was done in the case of KIC 12557548b. Methods: We obtained the phase-folded and binned transit light curve of KOI 2700b, which we subsequently iteratively modeled using the radiative-transfer code SHELLSPEC. We modeled the comet-like tail as part of a ring around the parent star and we also included the solid body of the planet in the model. During the modeling we applied selected species and dust particle sizes. Results: We confirmed the disintegrating-planet scenario of KOI 2700b. Furthermore, via modeling, we derived some interesting features of KOI 2700b and its comet-like tail. It turns out that the orbital plane of the planet and its tail are not edge-on, but the orbital inclination angle is from the interval [85.1, 88.6] deg. In comparison with KIC 12557548b, KOI 2700b exhibits a relatively low dust density decreasing in its tail. We also derived the dust density at the beginning of the ring and the highest optical depth through the tail in front of the star, based on a tail-model with a cross-section of 0.05 × 0.05 R⊙ at the beginning and 0.09 × 0.09 R⊙ at its end. Our results show that the dimension of the planet is Rp/Rs ≤ 0.014 (Rp ≤ 0.871 R⊕, or ≤5551 km). We also estimated the mass-loss rate from KOI 2700b, and we obtained Ṁ values from the interval [5.05 × 107, 4.41 × 1015] g s-1. On the other hand, we could not draw any satisfactory conclusions about the typical grain size in the dust tail.

Modified in vivo comet assay detects the genotoxic potential of 14-hydroxycodeinone, an α,β-unsaturated ketone in oxycodone.

PubMed

Pant, Kamala; Roden, Nicholas; Zhang, Charles; Bruce, Shannon; Wood, Craig; Pendino, Kimberly

2015-12-01

14-Hydroxycodeinone (14-HC) is an α,β-unsaturated ketone impurity found in oxycodone drug substance and has a structural alert for genotoxicity. 14-HC was tested in a combined Modified and Standard Comet Assay to determine if the slight decrease in % Tail DNA noted in a previously conducted Standard Comet Assay with 14-HC could be magnified to clarify if the response was due to cross-linking activity. One limitation of the Standard Comet Assay is that DNA cross-links cannot be reliably detected. However, under certain modified testing conditions, DNA cross-links and chemical moieties that elicit such cross-links can be elucidated. One such modification involves the induction of additional breakages of DNA strands by gamma or X-ray irradiation. To determine if 14-HC is a DNA crosslinker in vivo, a Modified Comet Assay was conducted using X-ray irradiation as the modification to visualize crosslinking activity. In this assay, 14-HC was administered orally to mice up to 320 mg/kg/day. Results showed a statistically significant reduction in percent tail DNA in duodenal cells at 320 mg/kg/day, with a nonstatistically significant but dose-related reduction in percent tail DNA also observed at the mid dose of 160 mg/kg/day. Similar decreases were not observed in cells from the liver or stomach, and no increases in percent tail DNA were noted for any tissue in the concomitantly conducted Standard Comet Assay. Taken together, 14-HC was identified as a cross-linking agent in the duodenum in the Modified Comet Assay. © 2015 Wiley Periodicals, Inc.

Plasma Waves Associated with Mass-Loaded Comets

NASA Technical Reports Server (NTRS)

Tsurutani, Bruce; Glassmeier, Karl-Heinz

2015-01-01

Plasma waves and instabilities are integrally involved with the plasma "pickup" process and the mass loading of the solar wind (thus the formation of ion tails and the magnetic tails). Anisotropic plasmas generated by solar wind-comet interactions (the bow shock, magnetic field pileup) cause the generation of plasma waves which in turn "smooth out" these discontinuities. The plasma waves evolve and form plasma turbulence. Comets are perhaps the best "laboratories" to study waves and turbulence because over time (and distance) one can identify the waves and their evolution. We will argue that comets in some ways are better laboratories than magnetospheres, interplanetary space and fusion devices to study nonlinear waves and their evolution.

DNA damage in human germ cell exposed to the some food additives in vitro.

PubMed

Pandir, Dilek

2016-08-01

The use of food additives has increased enormously in modern food technology but they have adverse effects in human healthy. The aim of this study was to investigate the DNA damage of some food additives such as citric acid (CA), benzoic acid (BA), brilliant blue (BB) and sunset yellow (SY) which were investigated in human male germ cells using comet assay. The sperm cells were incubated with different concentrations of these food additives (50, 100, 200 and 500 μg/mL) for 1 h at 32 °C. The results showed for CA, BA, BB and SY a dose dependent increase in tail DNA%, tail length and tail moment in human sperm when compared to control group. When control values were compared in the studied parameters in the treatment concentrations, SY was found to exhibit the highest level of DNA damage followed by BB > BA > CA. However, none of the food additives affected the tail DNA%, tail length and tail moment at 50 and 100 μg/mL. At 200 μg/mL of SY, the tail DNA% and tail length of sperm were 95.80 ± 0.28 and 42.56 ± 4.66, for BB the values were 95.06 ± 2.30 and 39.56 ± 3.78, whereas for BA the values were 89.05 ± 2.78 and 31.50 ± 0.71, for CA the values were 88.59 ± 6.45 and 13.59 ± 2.74, respectively. However, only the highest concentration of the used food additives significantly affected the studied parameters of sperm DNA. The present results indicate that SY and BB are more harmful than BA and CA to human sperm in vitro.

Comets as natural laboratories: Interpretations of the structure of the inner heliosphere

NASA Astrophysics Data System (ADS)

Ramanjooloo, Yudish; Jones, Geraint H.; Coates, Andrew J.; Owens, Mathew J.

2015-11-01

Much has been learnt about the heliosphere’s structure from in situ solar wind spacecraft observations. Their coverage is however limited in time and space. Comets can be considered to be natural laboratories of the inner heliosphere, as their ion tails trace the solar wind flow. Solar wind conditions influence comets’ induced magnetotails, formed through the draping of the heliospheric magnetic field by the velocity shear in the mass-loaded solar wind.I present a novel imaging technique and software to exploit the vast catalogues of amateur and professional images of comet ion tails. My projection technique uses the comet’s orbital plane to sample its ion tail as a proxy for determining multi-latitudinal radial solar wind velocities in each comet’s vicinity. Making full use of many observing stations from astrophotography hobbyists to professional observatories and spacecraft, this approach is applied to several comets observed in recent years. This work thus assesses the validity of analysing comets’ ion tails as complementary sources of information on dynamical heliospheric phenomena and the underlying continuous solar wind.Complementary velocities, measured from folding ion rays and a velocity profile map built from consecutive images, are derived as an alternative means of quantifying the solar wind-cometary ionosphere interaction, including turbulent transient phenomena such as coronal mass ejections. I review the validity of these techniques by comparing near-Earth comets to solar wind MHD models (ENLIL) in the inner heliosphere and extrapolated measurements by ACE to the orbit of comet C/2004 Q2 (Machholz), a near-Earth comet. My radial velocities are mapped back to the solar wind source surface to identify sources of the quiescent solar wind and heliospheric current sheet crossings. Comets were found to be good indicators of solar wind structure, but the quality of results is strongly dependent on the observing geometry.

Physical characteristics of cometary dust from dynamical studies - A review

NASA Technical Reports Server (NTRS)

Sekanina, Z.

1980-01-01

Progress made in the determination of the physical characteristics of cometary dust particles from studies of dust tail dynamics is reviewed. Applications of the combined dynamical photometric approach of Finson and Probstein (1968) to studies of cometary tails exhibiting continuous light intensity variations are discussed, with attention given to determinations of the particle-size-related distribution function of the solar radiation pressure exerted on the particles, the contribution of comets to the interplanetary dust, calculations of dust ejection rates and a Monte Carlo approach to the analysis of dust tails. Investigations of dust streamers and striae, which are believed to be related to comet outbursts entailing brief but sharp enhancements of dust production, are then reviewed, with particular attention given to observations of Comet West 1976 VI. Finally, the question of cometary particle type is addressed, and it is pointed out that the presence of submicron absorbing particles in the striae of Comet West is not incompatible with the presence of micron-size dielectric particles in the inner coma.

Genome-Wide siRNA Screen Identifies Complementary Signaling Pathways Involved in Listeria Infection and Reveals Different Actin Nucleation Mechanisms during Listeria Cell Invasion and Actin Comet Tail Formation

PubMed Central

Kühbacher, Andreas; Emmenlauer, Mario; Rämo, Pauli; Kafai, Natasha; Dehio, Christoph

2015-01-01

ABSTRACT Listeria monocytogenes enters nonphagocytic cells by a receptor-mediated mechanism that is dependent on a clathrin-based molecular machinery and actin rearrangements. Bacterial intra- and intercellular movements are also actin dependent and rely on the actin nucleating Arp2/3 complex, which is activated by host-derived nucleation-promoting factors downstream of the cell receptor Met during entry and by the bacterial nucleation-promoting factor ActA during comet tail formation. By genome-wide small interfering RNA (siRNA) screening for host factors involved in bacterial infection, we identified diverse cellular signaling networks and protein complexes that support or limit these processes. In addition, we could precise previously described molecular pathways involved in Listeria invasion. In particular our results show that the requirements for actin nucleators during Listeria entry and actin comet tail formation are different. Knockdown of several actin nucleators, including SPIRE2, reduced bacterial invasion while not affecting the generation of comet tails. Most interestingly, we observed that in contrast to our expectations, not all of the seven subunits of the Arp2/3 complex are required for Listeria entry into cells or actin tail formation and that the subunit requirements for each of these processes differ, highlighting a previously unsuspected versatility in Arp2/3 complex composition and function. PMID:25991686

Effect of Bearing Defects

DTIC Science & Technology

1974-12-01

defect types were tested at various levels: Comet- Tail, Dig-Nick, Dirt Brinell, Grind-Skip Lines, Impingement, Orange Peel , Pit, Scratch and "Liney...Shallow irregular indentation of surface. <.0015 max. dim. -(<.0008)*’ Otange Peel Pebbly appearance of raceway surface. Small ** Comet Tail Pit...scratch; dig-nick; impingement; grind-skip lines; and orange peel . The data obtained indicated that these defects in most cases, affected bearing

C/2013 A1 (Siding Spring vs. Mars)

NASA Technical Reports Server (NTRS)

Moorhead, Althea; Cooke, William

2013-01-01

Comet C/2013 A1 (Siding Spring): recently discovered long period comet. Will have close encounter with Mars on October 19, 2014. Collision is extremely unlikely. Passing through the coma and/or tail is likely. Increases risk to Martian spacecraft. Meteoroids (100 microns or larger): approx. or <20% chance of impact per square meter due to coma and tail. Gas may also a ect Martian atmosphere.

The Perihelion Emission of Comet C/2010 L5 (WISE)

NASA Astrophysics Data System (ADS)

Kramer, E. A.; Bauer, J. M.; Fernandez, Y. R.; Stevenson, R.; Mainzer, A. K.; Grav, T.; Masiero, J.; Nugent, C.; Sonnett, S.

2017-03-01

The only Halley-type comet discovered by the Wide-Field Infrared Survey Explorer (WISE), C/2010 L5 (WISE), was imaged three times by WISE, and it showed a significant dust tail during the second and third visits (2010 June and July, respectively). We present here an analysis of the data collected by WISE, putting estimates on the comet’s size, dust production rate, gas production (CO+CO2) rate, and active fraction. We also present a detailed description of a novel tail-fitting technique that allows the commonly used syndyne-synchrone models to be used analytically, thereby giving more robust results. We find that C/2010 L5's dust tail was likely formed by strong emission, likely in the form of an outburst, occurring when the comet was within a few days of perihelion. Analyses of the June and July data independently agree on this result. The two separate epochs of dust tail analysis independently suggest a strong emission event close to perihelion. The average size of the dust particles in the dust tail increased between the epochs, suggesting that the dust was primarily released in a short period of time, and the smaller dust particles were quickly swept away by solar radiation pressure, leaving the larger particles behind. The difference in CO2 and dust production rates measured in 2010 June and July is not consistent with “normal” steady-state gas production from a comet at these heliocentric distances, suggesting that much of the detected CO2 and dust was produced in an episodic event. Together, these conclusions suggest that C/2010 L5 experienced a significant outburst event when the comet was close to perihelion.

The Perihelion Emission of Comet C/2010 L5 ( WISE )

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kramer, E. A.; Bauer, J. M.; Stevenson, R.

The only Halley-type comet discovered by the Wide-Field Infrared Survey Explorer ( WISE ), C/2010 L5 ( WISE ), was imaged three times by WISE , and it showed a significant dust tail during the second and third visits (2010 June and July, respectively). We present here an analysis of the data collected by WISE , putting estimates on the comet’s size, dust production rate, gas production (CO+CO{sub 2}) rate, and active fraction. We also present a detailed description of a novel tail-fitting technique that allows the commonly used syndyne–synchrone models to be used analytically, thereby giving more robust results.more » We find that C/2010 L5's dust tail was likely formed by strong emission, likely in the form of an outburst, occurring when the comet was within a few days of perihelion. Analyses of the June and July data independently agree on this result. The two separate epochs of dust tail analysis independently suggest a strong emission event close to perihelion. The average size of the dust particles in the dust tail increased between the epochs, suggesting that the dust was primarily released in a short period of time, and the smaller dust particles were quickly swept away by solar radiation pressure, leaving the larger particles behind. The difference in CO{sub 2} and dust production rates measured in 2010 June and July is not consistent with “normal” steady-state gas production from a comet at these heliocentric distances, suggesting that much of the detected CO{sub 2} and dust was produced in an episodic event. Together, these conclusions suggest that C/2010 L5 experienced a significant outburst event when the comet was close to perihelion.« less

Observations at venus encounter by the plasma science experiment on mariner 10.

PubMed

Bridge, H S; Lazarus, A J; Scudder, J D; Ogilvie, K W; Hartle, R E; Asbridge, J R; Bame, S J; Feldman, W C; Siscoe, G L

1974-03-29

Preliminary results from the rearward-looking electrostatic analyzer of the plasma science experiment during the Mariner 10 encounter with Venus are described. They show that the solar-wind interaction with the planet probably involves a bow shock rather than an extended exosphere, but that this is not a thin boundary at the point where it was crossed by Mariner 10. An observed reduction in the flux of electrons with energies greater than 100 electron volts is interpreted as evidence for somne direct interaction with the exosphere. Unusual intermittent features observed downstream of the planet indicate the presence of a comet-like tail hundreds of scale lengths in length.

Observations at Venus encounter by the plasma science experiment on Mariner 10

NASA Technical Reports Server (NTRS)

Bridge, H. S.; Lazarus, A. J.; Scudder, J. D.; Ogilvie, K. W.; Hartle, R. E.; Asbridge, J. R.; Bame, S. J.; Feldman, W. C.; Siscoe, G. L.

1974-01-01

Preliminary results from the rearward-looking electrostatic analyzer of the plasma science experiment during the Mariner 10 encounter with Venus are described. They show that the solar-wind interaction with the planet probably involves a bow shock rather than an extended exosphere, but that this is not a thin boundary at the point where it was crossed by Mariner 10. An observed reduction in the flux of electrons with energies greater than 100 electron volts is interpreted as evidence for some direct interaction with the exosphere. Unusual intermittent features observed downstream of the planet indicate the presence of a comet-like tail hundreds of scale lengths in length.

Asteroids, Comets, Meteors 1991

NASA Technical Reports Server (NTRS)

Harris, Alan W. (Editor); Bowell, Edward (Editor)

1992-01-01

Papers from the conference are presented and cover the following topics with respect to asteroids, comets, and/or meteors: interplanetary dust, cometary atmospheres, atmospheric composition, comet tails, astronomical photometry, chemical composition, meteoroid showers, cometary nuclei, orbital resonance, orbital mechanics, emission spectra, radio astronomy, astronomical spectroscopy, photodissociation, micrometeoroids, cosmochemistry, and interstellar chemistry.

Validation of freezing tissues and cells for analysis of DNA strand break levels by comet assay

PubMed Central

Jackson, Petra

2013-01-01

The comet analysis of DNA strand break levels in tissues and cells has become a common method of screening for genotoxicity. The large majority of published studies have used fresh tissues and cells processed immediately after collection. However, we have used frozen tissues and cells for more than 10 years, and we believe that freezing samples improve efficiency of the method. We compared DNA strand break levels measured in fresh and frozen bronchoalveolar cells, and lung and liver tissues from mice exposed to the known mutagen methyl methanesulphonate (0, 25, 75, 112.5mg/kg). We used a high-throughput comet protocol with fully automated scoring of DNA strand break levels. The overall results from fresh and frozen samples were in agreement [R 2 = 0.93 for %DNA in tail (%TDNA) and R 2 = 0.78 for tail length (TL)]. A slightly increased %TDNA was observed in lung and liver tissue from vehicle controls; and TL was slightly reduced in bronchoalveolar lavage cells from the high-dose group. In our comet protocol, a small block of tissue designated for comet analysis is frozen immediately at tissue collection and kept deep frozen until rapidly homogenised and embedded in agarose. To demonstrate the feasibility of long-term freezing of samples, we analysed the day-to-day variation of our internal historical negative and positive comet assay controls collected over a 10-year period (1128 observations, 11 batches of frozen untreated and H2O2-treated A549 lung epithelial cells). The H2O2 treatment explained most of the variation 57–77% and the day-to-day variation was only 2–12%. The presented protocol allows analysis of samples collected over longer time span, at different locations, with reduced variation by reducing number of electrophoreses and is suitable for both toxicological and epidemiological studies. The use of frozen tissues; however, requires great care during preparation before analysis, with handling as a major risk factor. PMID:24136994

Assessment of occupational genotoxic risk among Brazilian hairdressers.

PubMed

Galiotte, Maíra Precivalle; Kohler, Priscila; Mussi, Gisele; Gattás, Gilka J F

2008-10-01

To evaluate the genotoxic risk to hairdressers exposed daily to chemical substances such as hair dyes, waving and straightening preparations and manicurists' products by the Comet assay test (single-cell gel electrophoresis). The Comet assay was performed on blood samples from 69 female hairdressers (36.4 +/- 10.7 years old) currently employed in 21 different beauty institutes in São Paulo, Brazil, and on 55 female control blood donors (32.6 +/- 10.0 years old) from the São Paulo University Clinical Hospital blood bank. All the control subjects had occupations other than hairdresser. Comet assays were performed by evaluating 100 blood lymphocytes per individual and graded by visual score according to comet tail length. The hairdressers showed a higher frequency of DNA damage revealed by Comet Score (159.8 +/- 71) when compared to the control group (125.4 +/- 64.1), and the difference was statistically significant by the Student's t-test (P = 0.005). Multiple regression analysis showed that in addition to the hairdressers' profession, tobacco use contributed to the higher frequency of cells with comets (P < 0.05). The observed DNA damage could be associated with the hairdressers' occupational environment, where different chemicals are chronically manipulated and inhaled. Considering that this profession in many countries, including Brazil, is not officially regulated, more attention should focus on these professionals not only by legislative bodies but also by multidisciplinary teams able to develop and implement risk prevention and control strategies for chemical, physical and biological agents to which hairdressers are exposed.

Centered reduced moments and associate density functions applied to alkaline comet assay.

PubMed

Castaneda, Roman; Pelaez, Alejandro; Marquez, Maria-Elena; Abad, Pablo

2005-01-01

The single cell gel electrophoresis assay is a sensitive, rapid, and visual technique for deoxyribonucleic acid (DNA) strand-break detection in individual mammalian cells, whose application has significantly increased in the past few years. The cells are embedded in agarose on glass slides followed by lyses of the cell membrane. Thereafter, damaged DNA strands are electrophoresed away from the nucleus towards the anode giving the appearance of a comet tail. Nowadays, charge coupled device cameras are attached at optical microscopes for recording the images of the cells, and digital image processing is applied for obtaining quantitative descriptors. However, the conventional software is usually expensive, inflexible and, in many cases, can only provide low-order descriptors based in image segmentation, determination of centers of mass, and Euclidean distances. Associated density functions and centered reduced moments offer an effective and flexible alternative for quantitative analysis of the comet cells. We will show how the position of the center of mass, the lengths and orientation of the main semiaxes, and the eccentricity of such images can be accurately determined by this method.

David Levy's Guide to Observing and Discovering Comets

NASA Astrophysics Data System (ADS)

Levy, David H.

2003-05-01

Preface; Part I. Why Observe Comets?: 1. Of history, superstition, magic, and science; 2. Comet science progresses; Part II. Discovering Comets: 3. Comet searching begins; 4. Tails and trails; 5. Comet searching in the twentieth century; 6. How I search for comets; 7. Searching for comets photographically; 8. Searching for comets with CCDs; 9. Comet hunting by reading; 10. Hunting for sungrazers over the Internet; 11. What to do when you think you've found a comet; Part III. A New Way of Looking at Comets: 12. When comets hit planets; 13. The future of visual comet hunting; Part IV. How to Observe Comets: 14. An introduction to comet hunting; 15. Visual observing of comets; 16. Estimating the magnitude of a comet; 17. Taking a picture of a comet; 18. Measuring where a comet is in the sky; Part V. Closing Notes: 19. My passion for comets.

Mutagenicity and genotoxicity of coal fly ash water leachate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chakraborty, R.; Mukherjee, A.

2009-03-15

Fly ash is a by-product of coal-fired electricity generation plants. The prevalent practice of disposal is as slurry of ash and water to storage or ash ponds located near power stations. This has lain to waste thousands of hectares of land all over the world. Since leaching is often the cause of off-site contamination and pathway of introduction into the human environment, a study on the genotoxic effects of fly ash leachate is essential. Leachate prepared from the fly ash sample was analyzed for metal content, and tested for mutagenicity and genotoxicity. Analyses of metals show predominance of the metalsmore » - sodium, silicon, potassium, calcium, magnesium, iron, manganese, zinc, and sulphate. The Ames Salmonella mutagenicity assay, a short-term bacterial reverse mutation assay, was conducted on two-tester strains of Salmonella typhimurium strains TA97a and TA102. For genotoxicity, the alkaline version of comet assay on fly ash leachate was carried in vitro on human blood cells and in vivo on Nicotiana plants. The leachate was directly mutagenic and induced significantconcentration-dependent increases in DNA damage in whole blood cells, lymphocytes, and in Nicotiana plants. The comet parameters show increases in tail DNA percentage (%), tail length (mu m), and olive tail moment (arbitrary units). Our results indicate that leachate from fly ash dumpsites has the genotoxic potential and may lead to adverse effects on vegetation and on the health of exposed human populations.« less

Establishing a model for assessing DNA damage in murine brain cells as a molecular marker of chemotherapy-associated cognitive impairment.

PubMed

Krynetskiy, Evgeny; Krynetskaia, Natalia; Rihawi, Diana; Wieczerzak, Katarzyna; Ciummo, Victoria; Walker, Ellen

2013-10-17

Chemotherapy-associated cognitive impairment often follows cancer chemotherapy. We explored chemotherapy-induced DNA damage in the brain cells of mice treated with 5-fluorouracil (5FU), an antineoplastic agent, to correlate the extent of DNA damage to behavioral functioning in an autoshaping-operant mouse model of chemotherapy-induced learning and memory deficits (Foley et al., 2008). Male, Swiss-Webster mice were injected once with saline or 75 mg/kg 5FU at 0, 12, and 24h and weighed every 24h. Twenty-four h after the last injection, the mice were tested in a two-day acquisition and the retention of a novel response task for food reinforcement. Murine brain cells were analyzed for the presence of single- and double-strand DNA breaks by the single cell gel electrophoresis assay (the Comet assay). We detected significant differences (p<0.0001) for all DNA damage characteristics (DNA "comet" tail shape, migration pattern, tail moment and olive moments) between control mice cohort and 5FU-treated mice cohort: tail length - 119 vs. 153; tail moment - 101 vs. 136; olive moment - 60 vs. 82, correspondingly. We found a positive correlation between increased response rates (r=0.52, p<0.05) and increased rate of errors (r=0.51, p<0.05), and DNA damage on day 1. For all 15 mice (saline-treated and 5FU-treated mice), we found negative correlations between DNA damage and weight (r=-0.75, p<0.02). Our results indicate that chemotherapy-induced DNA damage changes the physiological status of the brain cells and may provide insights to the mechanisms for cognitive impairment after cancer chemotherapy. Copyright © 2013 Elsevier Inc. All rights reserved.

Asteroids and Comets Outreach Compilation

NASA Technical Reports Server (NTRS)

1999-01-01

Contents include various different animations in the area of Asteroids and Comets. Titles of the short animated clips are: STARDUST Mission; Asteroid Castallia Impact Simulation; Castallia, Toutatis and the Earth; Simulation Asteroid Encounter with Earth; Nanorover Technology Task; Near Earth Asteroid Tracking; Champollian Anchor Tests; Early Views of Comets; Exploration of Small Bodies; Ulysses Resource Material from ESA; Ulysses Cometary Plasma Tail Animation; and various discussions on the Hale-Bopp Comet. Animation of the following are seen: the Stardust aerogel collector grid collecting cometary dust particles, comet and interstellar dust analyzer, Wiper-shield and dust flux monitor, a navigation camera, and the return of the sample to Earth; a comparison of the rotation of the Earth to the Castallia and Tautatis Asteroids; an animated land on Tautatis and the view of the motion of the sky from its surface; an Asteroid collision with the Earth; the USAF Station in Hawaii; close-up views of asteroids; automatic drilling of the Moon; exploding Cosmic Particles; and the dropping off of the plasma tail of a comet as it travels near the sun.

Modern Observational Techniques for Comets

NASA Technical Reports Server (NTRS)

Brandt, J. C. (Editor); Greenberg, J. M. (Editor); Donn, B. (Editor); Rahe, J. (Editor)

1981-01-01

Techniques are discussed in the following areas: astrometry, photometry, infrared observations, radio observations, spectroscopy, imaging of coma and tail, image processing of observation. The determination of the chemical composition and physical structure of comets is highlighted.

Lymphocyte DNA damage in Turkish asphalt workers detected by the comet assay.

PubMed

Bacaksiz, Aysegul; Kayaalti, Zeliha; Soylemez, Esma; Tutkun, Engin; Soylemezoglu, Tulin

2014-01-01

Asphalt has a highly complex structure and it contains several organic compounds including polycyclic aromatic hydrocarbons and heterocyclic compounds. In this study, comet assay was used to detect the DNA damage in blood lymphocytes of 30 workers exposed to asphalt fumes and 30 nonexposed controls. This is the first report on Turkish asphalt workers' investigated DNA damage using the alkaline single cell gel electrophoresis (SCGE). The DNA damage was evaluated by the percentage of DNA in the comet tail (% tail DNA) for each cell. According to our results, workers exposed to asphalt fumes had higher DNA damage than the control group (p < 0.01). The present study showed that asphalt fumes caused a significant increase in DNA damage and the comet assay is a suitable method for determining DNA damage in asphalt workers.

Organic extracts of coke oven emissions can induce genetic damage in metabolically competent HepG2 cells.

PubMed

Xin, Lili; Wang, Jianshu; Guo, Sifan; Wu, Yanhu; Li, Xiaohai; Deng, Huaxin; Kuang, Dan; Xiao, Wei; Wu, Tangchun; Guo, Huan

2014-05-01

Coke oven emissions (COEs) containing various carcinogenic polycyclic aromatic hydrocarbons (PAHs) represent the coal-burning pollution in the air. Organic pollutants in the aerosol and particulate matter of COEs were collected from the bottom, side, and top of a coke oven. The Comet assay and cytokinesis-block micronucleus cytome assay were conducted to analyze the genetic damage of extractable organic matter (EOM) of COEs on HepG2 cells. All the three EOMs could induce significant dose-dependent increases in Olive tail moment, tail DNA, and tail length, micronuclei, nucleoplasmic bridges, and nuclear buds frequencies, which were mostly positively correlated with the total PAHs concentration in each EOM. In conclusion, EOMs of COEs in the three typical working places of coke oven can induce DNA strand breaks and genomic instability in the metabolically competent HepG2 cells. The PAHs in EOMs may be important causative agents for the genotoxic effects of COEs. Copyright © 2014 Elsevier B.V. All rights reserved.

NASA Hubble Sees Comet ISON Intact

NASA Image and Video Library

2013-10-09

This image from NASA Hubble Space Telescope of the sunward plunging comet ISON suggests that the comet is intact despite some predictions that the fragile icy nucleus might disintegrate as the sun warms it. In this NASA Hubble Space Telescope image taken on October 9, 2013 the comet's solid nucleus is unresolved because it is so small. If the nucleus broke apart then Hubble would have likely seen evidence for multiple fragments. Moreover, the coma or head surrounding the comet's nucleus is symmetric and smooth. This would probably not be the case if clusters of smaller fragments were flying along. What's more, a polar jet of dust first seen in Hubble images taken in April is no longer visible and may have turned off. This color composite image was assembled using two filters. The comet's coma appears cyan, a greenish-blue color due to gas, while the tail is reddish due to dust streaming off the nucleus. The tail forms as dust particles are pushed away from the nucleus by the pressure of sunlight. The comet was inside Mars' orbit and 177 million miles from Earth when photographed. Comet ISON is predicted to make its closest approach to Earth on 26 December, at a distance of 39.9 million miles. http://photojournal.jpl.nasa.gov/catalog/PIA18153

Singing comet changes its song

NASA Astrophysics Data System (ADS)

Volwerk, M.; Goetz, C.; Delva, M.; Richter, I.; Tsurutani, B. T.; Eriksson, A.; Odelstad, E.; Meier, P.; Nilsson, H.; Glassmeier, K.-H.

2017-09-01

The singing comet was discovered at the beginning of the Rosetta mission around comet 67P/Churyumov-Gerasimenko. Large amplitude compressional waves with frequencies between 10 and 100 mHz were observed. When the comet became more active this signal was no longer measured. During the so-called tail excursion, late in the mission after perihelion, with again a less active comet, the singing was observed again and interestingly, going from 26 March to 27 March 2016 the character of the singing changed.

Midcourse Space Experiment Observations of Small Solar System Bodies

NASA Astrophysics Data System (ADS)

Kraemer, Kathleen E.; Lisse, C. M.; Price, Stephan D.; Mizuno, D.; Walker, R. G.; Farnham, T. L.; Mäkinen, T.

2005-11-01

Eight comets, two transition objects (extinct comet candidates), and two near-Earth asteroids were imaged in four infrared bands with the SPIRIT III instrument on the Midcourse Space Experiment, namely, C/1996 B2 (Hyakutake), C/1995 O1 (Hale-Bopp), C/1996 Q1 (Tabur), 126P/IRAS, 22P/Kopff, 46P/Wirtanen, (3200) Phaethon, (4015) 107P/Wilson-Harrington, (4179) Toutatis, (4197) 1982 TA, 125P/Spacewatch, and 55P/Tempel-Tuttle. We present maps of each object detected and a description of their characteristics. Five of the comets had extended dust tails, all of which show evidence for silicate emission in the 8.3 μm band. The comet C/Hyakutake had a strong secondary dust tail along the direction of the comet's motion, which the dynamical models showed was consistent with emission from large particles. The dust trail from P/Kopff was detected more than 2° from the coma in three of the four bands and is probably composed of large particles emitted during the 1996 apparition.

Strong CO+ and {{\\rm{N}}}_{2}^{+} Emission in Comet C/2016 R2 (Pan-STARRS)

NASA Astrophysics Data System (ADS)

Cochran, Anita L.; McKay, Adam J.

2018-02-01

We report on imaging and spectroscopic observations of comet C/2016 R2 (Pan-STARRS) obtained with the 0.8 m and 2.7 m telescopes of McDonald Observatory in 2017 November and December, respectively. The comet was at a heliocentric distance greater than 3 au during both sets of observations. The images showed a well-developed tail with properties that suggested it was an ion tail. The spectra confirmed that we were observing well-developed bands of CO+ and {{{N}}}2+. The {{{N}}}2+ detection was unequivocally cometary and was one of the strongest bands of {{{N}}}2+ detected in a comet spectrum. We derived the ratio of these two ions and from that we were able to derive that N2/CO = 0.15. This is the highest such ratio reported for a comet. This Letter includes data taken at The McDonald Observatory of The University of Texas at Austin.

Genetic damage induced by organic extract of coke oven emissions on human bronchial epithelial cells.

PubMed

Zhai, Qingfeng; Duan, Huawei; Wang, Yadong; Huang, Chuanfeng; Niu, Yong; Dai, Yufei; Bin, Ping; Liu, Qingjun; Chen, Wen; Ma, Junxiang; Zheng, Yuxin

2012-08-01

Coke oven emissions are known as human carcinogen, which is a complex mixture of polycyclic aromatic hydrocarbon. In this study, we aimed to clarify the mechanism of action of coke oven emissions induced carcinogenesis and to identify biomarkers of early biological effects in a human bronchial epithelial cell line with CYP1A1 activity (HBE-CYP1A1). Particulate matter was collected in the oven area on glass filter, extracted and analyzed by GC/MS. DNA breaks and oxidative damage were evaluated by alkaline and endonucleases (FPG, hOGG1 and ENDO III)-modified comet assays. Cytotoxicity and chromosomal damage were assessed by the cytokinesis-block micronucleus cytome (CBMN-Cyt) assay. The cells were treated with organic extract of coke oven emissions (OE-COE) representing 5, 10, 20, 40μg/mL extract for 24h. We found that there was a dose-effect relationship between the OE-COE and the direct DNA damage presented by tail length, tail intensity and Olive tail moment in the comet assay. The presence of lesion-specific endonucleases in the assays increased DNA migration after OE-COE treatment when compared to those without enzymes, which indicated that OE-COE produced oxidative damage at the level of pyrimidine and purine bases. The dose-dependent increase of micronuclei, nucleoplasmic bridges and nuclear buds in exposed cells was significant, indicating chromosomal and genomic damage induced by OE-COE. Based on the cytotoxic biomarkers in CBMN-Cyt assay, OE-COE may inhibit nuclear division, interfere with apoptosis, or induce cell necrosis. This study indicates that OE-COE exposure can induce DNA breaks/oxidative damage and genomic instability in HBE-CYP1A1 cells. The FPG-comet assay appears more specific for detecting oxidative DNA damage induced by complex mixtures of genotoxic substances. Copyright © 2012 Elsevier Ltd. All rights reserved.

DNA damage in outdoor workers occupationally exposed to environmental air pollutants

PubMed Central

Tovalin, H; Valverde, M; Morandi, M T; Blanco, S; Whitehead, L; Rojas, E

2006-01-01

Background Health concerns about the exposure to genotoxic and carcinogenic agents in the air are particularly significant for outdoor workers in less developed countries. Aims To investigate the association between personal exposure to a group of air pollutants and severity of DNA damage in outdoor workers from two Mexican cities. Methods DNA damage (Comet assay) and personal exposure to volatile organic compounds, PM2.5, and ozone were investigated in 55 outdoor and indoor workers from México City and Puebla. Results In México City, outdoor workers had greater DNA damage, reflected by a longer tail length, than indoor workers (median 46.8 v 30.1 μm), and a greater percentage of highly damaged cells (cells with tail length ⩾41 μm); in Puebla, outdoor and indoor workers had similar DNA damage. There were more alkali labile sites in outdoor than indoor workers. The DNA damage magnitude was positively correlated with PM2.5 and ozone exposure. Outdoor and indoor workers with ⩾60% of highly damaged cells (highly damaged workers) had significantly higher exposures to PM2.5, ozone, and some volatile organic compounds. The main factors associated with the highly damaged workers were ozone, PM2.5, and 1‐ethyl‐2‐methyl benzene exposure. Conclusions With this approach, the effects of some air pollutants could be correlated with biological endpoints from the Comet assay. It is suggested that the use of personal exposure assessment and biological endpoints evaluation could be an important tool to generate a more precise assessment of the associated potential health risks. PMID:16556741

Genoprotective effect of hyaluronic acid against benzalkonium chloride-induced DNA damage in human corneal epithelial cells

PubMed Central

Wu, Han; Zhang, Huina; Wang, Changjun; Wu, Yihua; Xie, Jiajun; Jin, Xiuming; Yang, Jun

2011-01-01

Purpose The aim of this study was to investigate hyaluronic acid (HA) protection on cultured human corneal epithelial cells (HCEs) against benzalkonium chloride (BAC)-induced DNA damage and intracellular reactive oxygen species (ROS) increase. Methods Cells were incubated with different concentrations of BAC with or without the presence of 0.2% HA for 30 min. DNA damage to HCEs was examined by alkaline comet assay and by immunofluorescence microscopic detection of the phosphorylated form of histone variant H2AX (γH2AX) foci. ROS production was assessed by the fluorescent probe, 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA). Cell apoptosis was determined with annexin V staining by flow cytometry. Results HA significantly reduced BAC-induced DNA damage as indicated by the tail length (TL) and tail moment (TM) of alkaline comet assay and by γH2AX foci formation, respectively. Moreover, HA significantly decreased BAC-induced ROS increase and cell apoptosis. However, exposure to HA alone did not produce any significant change in DNA damage, ROS generation, or cell apoptosis. Conclusions BAC could induce DNA damage and cell apoptosis in HCEs, probably through increasing oxidative stress. Furthermore, HA was an effective protective agent that had antioxidant properties and could decrease DNA damage and cell apoptosis induced by BAC. PMID:22219631

Progress in a Study of Striations in the Dust Tail of Comet Hale-Bopp (C/1995 O1)

NASA Astrophysics Data System (ADS)

Sekanina, Z.; Ryan, O.; Boehnhardt, H.; Birkle, K.; Engels, D.; Jaeger, M.; Keller, P.; Raab, H.

1999-01-01

We report preliminary results of a massive investigation of the striation patterns observed in the dust tail of comet Hale-Bopp in March and April 1997. Our findings are based on 16 wide-field photographs taken with Schmidt cameras on March 2-20, with six more, from March 31-April 8, still waiting for analysis. Altogether approximately 700 individual striae were examined on the 16 images, which were scanned and computer processed to enhance the morphology. About 5300 stria points, or some 7-8 points per stria per image on the average, were measured and their astrometric positions determined and subsequently converted to a Cartesian coordinate system, aligned with the comet's projected radius vector and centered on the nucleus. The evolution of the striated tail has been studied using the Sekanina-Farrell fragmentation hypothesis (AJ 85, 1538, 1980), previously applied to other comets. This two-step model is characterized by the time of release from the nucleus of a parent object (or objects) whose motion is assumed to have been subjected to a constant repulsive acceleration betap (presumably due to solar radiation pressure) until the time of fragmentation.

Comet 67P Seen by Kepler

NASA Image and Video Library

2016-10-07

The European Space Agency's Rosetta mission concluded its study of comet 67P/Churyumov-Gerasimenko on Sept. 30, 2016. NASA's planet-hunting Kepler spacecraft observed the comet during the final month of the Rosetta mission, while the comet was not visible from Earth. This animation is composed of images from Kepler of the comet. From Sept. 7 through Sept. 20, the Kepler spacecraft, operating in its K2 mission, fixed its gaze on comet 67P. From the distant vantage point of Kepler, the comet's nucleus and tail could be observed. The long-range view from Kepler complements the closeup view of the Rosetta spacecraft, providing context for the high-resolution investigation Rosetta performed as it descended closer and closer to the comet. During the two-week period of study, Kepler took a picture of the comet every 30 minutes. The animation shows a period of 29.5 hours of observation from Sept. 17 thru Sept. 18. The comet is seen passing through Kepler's field of view from top right to bottom left, as outlined by the diagonal strip. The white dots represent stars and other regions in space studied during K2's tenth observing campaign. As a comet travels through space it sheds a tail of gas and dust. The more material that is shed, the more surface area there is to reflect sunlight. A comet's activity level can be obtained by measuring the reflected sunlight. Analyzing the Kepler data, scientists will be able to determine the amount of mass lost each day as comet 67P travels through the solar system. An animation is available at http://photojournal.jpl.nasa.gov/catalog/PIA21072

Tests for genotoxicity and mutagenicity of furan and its metabolite cis-2-butene-1,4-dial in L5178Y tk+/- mouse lymphoma cells.

PubMed

Kellert, Marco; Brink, Andreas; Richter, Ingrid; Schlatter, Josef; Lutz, Werner K

2008-12-08

Furan is found in various food items and is cytotoxic and carcinogenic in the liver of rats and mice. Metabolism of furan includes the formation of an unsaturated dialdehyde, cis-2-butene-1,4-dial (BDA). In view of the multifunctional electrophilic reactivity of BDA, adduct formation with protein and DNA may explain some of the toxic effects. Short-term tests for genotoxicity of furan in mammalian cells are inconclusive, little is known for BDA. We investigated BDA generated by hydrolysis of 2,5-diacetoxy-2,5-dihydrofuran for genotoxicity in L5178Y tk+/- mouse lymphoma cells using standard procedures for the comet assay, the micronucleus test, and the mouse lymphoma thymidine kinase gene mutation assay, using 4-h incubation periods. Cytotoxicity was remarkable: cell viability at concentrations>or=50 microM was reduced to <50%. In the dose range up to 25 microM, viability was >90%. Measures of comet-tail length and thymidine-kinase mutant frequency were increased 1.6- and 2.4-fold above control, respectively. Analysis of three fully independent replicates with a linear mixed-effects model showed a highly significant increase with concentration for both endpoints. Compared to methyl methanesulfonate used as a positive control, BDA was of similar potency with respect to genotoxicity, but it was much more cytotoxic. Furan added to cell cultures at doses that resulted in time-averaged effective concentrations of up to 3100 microM was neither cytotoxic nor genotoxic. A potential cross-linking activity of BDA was investigated by checking whether gamma radiation-induced DNA migration in the comet assay could be reduced by pre-treatment with BDA. In contrast to the effect of the positive control glutaraldehyde, BDA treatment did not reduce the comet tail length. On the contrary, an increase was observed at >or=100 microM BDA, which was attributable to early apoptotic cells. Although BDA was found to be a relatively potent genotoxic agent in terms of the concentration necessary to double the background measures, cytotoxicity strongly limited the concentration range that produced interpretable results. This may explain some of the inconclusive results and indicates that non-genotoxic effects must be taken into account in the discussion of the modes of toxic and carcinogenic action of furan.

Investigation of the phenomenon of the big comet of 1858

NASA Technical Reports Server (NTRS)

Pape, C. F.

1977-01-01

Various aspects of the large comet of 1858 including the luminosity of the core and the shape, intensity and position of the tail with respect to the sun and stars are described and then compared with the large comet of 1744 described by Heinsius and Halley's comet of 1835. The purpose of these observations is to try to gain a clearer understanding of the nature of the polar force from the sun acting on the comet. This force is said to differ from the usual force of gravity.

Interaction of Comets and the Solar Wind

NASA Technical Reports Server (NTRS)

Wagner, William (Technical Monitor); Raymond, John C.

2003-01-01

We had originally planned to analyze UVCS observations of Comet Machholz, but we obtained higher quality observations of Comet Kudo-Fujikawa in January 2003 at its 0.19 AU perihelion. Besides a large and rapidly increasing water outgassing rate, we detected a bright tail in doubly ionized carbon. The amount of carbon was greater than could be accounted for by GO photodissociation, and we attribute the carbon to evaporation of organics from dust. A spectacular disconnection event was apparent in the C III tail, and it coincides within the uncertainties with the position of the heliospheric current sheet. A paper is in press in Science, and it will be the subject of a press release. We are also analyzing two sungrazing comets. Comet C/2001 C2 shows evidence for sub-fragments and for a very long lasting source of neutrals, which we tentatively identify as evaporation of pyroxene dust grains. Comet C/2002 S2 shows a sudden 2 magnitude drop in optical brightness and an equally sudden recovery. UVCS observations during that time show a steadily increasing outgassing rate. We have derived solar wind densities for both comets, but we are still sorting out the ambiguities involving the fragmentation and optical behavior. We are collaborating with Philippe Lamy on the LASCO measurements.

Mechanics of biomimetic systems propelled by actin comet tails

NASA Astrophysics Data System (ADS)

Kang, Hyeran; Tambe, Dhananjay; Shenoy, Vivek; Tang, Jay

2009-03-01

The motility of intracellular bacterial pathogens such as Listeria monocytogenes is driven by filamentous actin comet tails in a variety of trajectories. Here, we present the in vitro study on the actin-based movements using spherical beads of different sizes coated with VCA protein, a partial domain of N-Wasp, in platelet extracts. Long term two-dimensional trajectories of the spherical beads motility show characteristic difference than those observed for bacteria, which have both elongated shape and asymmetric expression of the polymerization inducing enzyme. The trajectories also vary sensitively with the bead size and shape. These results provide a useful test to our new analytical model including the rotation of the bead relative to the tail.

International Halley Watch: Discipline specialists for large scale phenomena

NASA Technical Reports Server (NTRS)

Brandt, J. C.; Niedner, M. B., Jr.

1986-01-01

The largest scale structures of comets, their tails, are extremely interesting from a physical point of view, and some of their properties are among the most spectacular displayed by comets. Because the tail(s) is an important component part of a comet, the Large-Scale Phenomena (L-SP) Discipline was created as one of eight different observational methods in which Halley data would be encouraged and collected from all around the world under the aspices of the International Halley Watch (IHW). The L-SP Discipline Specialist (DS) Team resides at NASA/Goddard Space Flight Center under the leadership of John C. Brandt, Malcolm B. Niedner, and their team of image-processing and computer specialists; Jurgan Rahe at NASA Headquarters completes the formal DS science staff. The team has adopted the study of disconnection events (DE) as its principal science target, and it is because of the rapid changes which occur in connection with DE's that such extensive global coverage was deemed necessary to assemble a complete record.

The worldwide impact of Donati's comet on art and society in the mid-19th century

NASA Astrophysics Data System (ADS)

Gasperini, Antonella; Galli, Daniele; Nenzi, Laura

2011-06-01

Donati's comet was one of the most spectacular astronomical events of the nineteenth century. Its extended sword-like tail was a spectacular sight that inspired several literary and artistic representations. Traces of Donati's comet are found in popular magazines, children's books, collection cards, and household objects through the beginning of the twentieth century.

On the trail of Comet G-Z

NASA Technical Reports Server (NTRS)

Maran, S. P.

1985-01-01

The International Cometary Explorer (ICE) is to investigate the magnetic and electric fields, plasmas, and particles in the Comet Giacobini-Zinner (G-Z) and to study its interaction with solar wind. The ICE can pass through the comet only once and it will take 90 minutes to cross from one side of the tail to the other. Since the Comet G-Z often changes its orbit due to nongravitational forces changing its direction and velocity, ICE's position needs to be adjusted. The probe is aimed 10,000 km from the nucleus in order to be provided the best passage through the Comet G-Z. The 64-meter dishes of JPL's Deep-Space Network (DSN) will receive data transmitted on two adjacent S-band frequencies at the rate of 1024 bits per second. Also NASA has arranged for the radio telescope at Arecibo to record the transmission. The Japanese 64-meter tracking antenna at Usada, equipped with an ultrasensitive receiver for one ICE frequency, will provide pre-encounter and post-encounter tracking. The ICE data may provide information about the dust tail in the Comet G-Z which could be compared to previous research.

Interaction of Comets and the Solar Wind

NASA Technical Reports Server (NTRS)

Wagner, William (Technical Monitor); Raymond, John C.

2004-01-01

The analysis of Comet Kudo-Fujikawa at perihelion was published and picked up by Der Spiegel. Besides a large and rapidly increasing water outgassing rate, we detected a bright tail in doubly ionized carbon. The amount of carbon was greater than could be accounted for by CO photodissociation, and we attribute it to evaporation of organics from dust. A spectacular disconnection event was apparent in the C III tail, and it coincides within the uncertainties to the position of the heliospheric current sheet. The analysis of the sungrazing comet C2001 C2 is in press. It showed evidence for subfragments and for a very long lasting source of neutrals, which we identify as evaporation of pyroxene dust grains. Results were also presented at COSPAR. We are working on observations of another sungrazer, comet C2002 S2, which shows a sudden 2 magnitude drop in optical brightness and an equally sudden recovery. UVCS observations during that time show a steadily increasing outgassing rate. We have derived solar wind densities for both comets, but we are still sorting out the ambiguities involving the fragmentation and optical behavior.

Report of the Comet Science Working Group

NASA Technical Reports Server (NTRS)

1979-01-01

General scientific questions and measurement objectives that can be addressed on a first comet mission relate to: (1) the chemical nature and the physical structure of comet nuclei as well as the changes that occur as functions of time and orbital position; (2) the chemical and physical nature of the atmospheres and ionospheres of comets, the processes which occur in them, and the development of these atmospheres and ionospheres as functions of time and orbital position; and (3) the nature of comet tails, the processes by which they are formed, and the interaction of comets with the solar wind. Capabilities of the various instruments required are discussed.

Helium discovered in the tail of an exoplanet

NASA Astrophysics Data System (ADS)

Deming, Drake

2018-05-01

As the exoplanet WASP-107b orbits its host star, its atmosphere escapes to form a comet-like tail. Helium atoms detected in the escaping gases give astronomers a powerful tool for investigating exoplanetary atmospheres.

Polyvinylidene Fluoride as a Suture Material: Evaluation of Comet Tail-Like Infiltrate and Foreign Body Granuloma.

PubMed

Lambertz, Andreas; Schröder, Kai Michael; Schöb, Dominik Stefan; Binnebösel, Marcel; Anurov, Michael; Klinge, Uwe; Neumann, Ulf Peter; Klink, Christian Daniel

2015-01-01

Biocompatibility and tissue integration of a surgical suture are decisive factors for wound healing and therefore for the success of sutures. The optimal suture material is still under discussion. Polyvinylidene fluoride (PVDF) is described to have superior properties of biocompatibility and is therefore frequently used as a mesh component. Only little information is available about its use as a suture material. The aim of this study was to evaluate the biocompatibility of PVDF as a suture material in comparison to 5 different established sutures in a rat model. In 30 male rats, a monofilamental PVDF suture (Resopren®) and 5 established control suture materials [polyester (Miralene®), polytetrafluoroethylene (Gore®), poliglecaprone (Monocryl®), polydioxanone (Monoplus®), polyglactin 910 (Vicryl®), USP size 3-0] were placed in the subcutaneous layer of the abdominal wall without knot or tension. After 3, 7 or 21 days, the abdominal walls were explanted for histopathological and immunohistochemical investigation with special regard to the size and quality of foreign body granuloma and the length of the comet tail-like infiltrate (CTI). The PVDF sutures showed the smallest size of foreign body granuloma (60 ± 14 µm) and the smallest CTI length (343 ± 60 µm) of all polymers after 21 days. Only PVDF (Resopren) and polydioxanone (Monoplus) showed a significant collagen I/III ratio increase between days 3 and 21 (p = 0.009 and p = 0.016). The quality of foreign body reaction regarding inflammation, proliferation and fibrotic remodeling was similar between all suture materials. Our data indicate that monofilamental PVDF sutures show a favorable foreign body reaction with small granuloma sizes and CTI length in comparison to established sutures. Its use as a suture material in general surgery could therefore be extended in the future. To reinforce these findings, further clinical studies need to be conducted. 2015 S. Karger AG, Basel.

THE PLASMA ENVIRONMENT IN COMETS OVER A WIDE RANGE OF HELIOCENTRIC DISTANCES: APPLICATION TO COMET C/2006 P1 (MCNAUGHT)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shou, Y.; Combi, M.; Gombosi, T.

2015-08-20

On 2007 January 12, comet C/2006 P1 (McNaught) passed its perihelion at 0.17 AU. Abundant remote observations offer plenty of information on the neutral composition and neutral velocities within 1 million kilometers of the comet nucleus. In early February, the Ulysses spacecraft made an in situ measurement of the ion composition, plasma velocity, and magnetic field when passing through the distant ion tail and the ambient solar wind. The measurement by Ulysses was made when the comet was at around 0.8 AU. With the constraints provided by remote and in situ observations, we simulated the plasma environment of Comet C/2006more » P1 (McNaught) using a multi-species comet MHD model over a wide range of heliocentric distances from 0.17 to 1.75 AU. The solar wind interaction of the comet at various locations is characterized and typical subsolar standoff distances of the bow shock and contact surface are presented and compared to analytic solutions. We find the variation in the bow shock standoff distances at different heliocentric distances is smaller than the contact surface. In addition, we modified the multi-species model for the case when the comet was at 0.7 AU and achieved comparable water group ion abundances, proton densities, plasma velocities, and plasma temperatures to the Ulysses/SWICS and SWOOPS observations. We discuss the dominating chemical reactions throughout the comet-solar wind interaction region and demonstrate the link between the ion composition near the comet and in the distant tail as measured by Ulysses.« less

First images of a possible CO(+)-tail of comet P/Schwassmann-Wachmann 1 observed against the dust coma background

NASA Technical Reports Server (NTRS)

Jockers, Klaus; Bonev, T.; Ivanova, Violeta; Rauer, H.

1992-01-01

Comet P/Schwassmann-Wachmann 1 was observed with the 2m-Ritchey-Cretien Telescope of the Bulgarian National Observatory, Rozhen, Bulgaria, using the CCD-camera and focal reducer of the Max-Planck-Institute for Aeronomy. Images were taken in a red continuum window and in the 2-0 A(exp 2)Pi - X(exp 2)Sigma(+) band of CO(+) located in the blue part of the spectrum. The red images reveal an extended dust coma. From a comparison of the red and blue images a dust reddening of 13.2 percent per 1000 A is derived. At 642 nm the magnitude of the comet with a square diaphragm of 4.5 arcsec is 16.6. The blue images, taken in the CO(+) band, show a significantly different brightness distribution which is interpreted as presence of a CO(+) coma and tail superimposed on the continuum. A column density of several 10(exp 10) CO(+) molecules cm(exp -2) is derived. The tail thickness of 10(exp 5) km is unexpectedly small. We estimate the CO(+) production rate to about 6 x 10(exp 26) CO(+) particles s(exp -1). This value does not support the idea that the outbursts of this comet are caused by crystallization of amorphous water ice.

Likely transiting exocomets detected by Kepler

NASA Astrophysics Data System (ADS)

Rappaport, S.; Vanderburg, A.; Jacobs, T.; LaCourse, D.; Jenkins, J.; Kraus, A.; Rizzuto, A.; Latham, D. W.; Bieryla, A.; Lazarevic, M.; Schmitt, A.

2018-02-01

We present the first good evidence for exocomet transits of a host star in continuum light in data from the Kepler mission. The Kepler star in question, KIC 3542116, is of spectral type F2V and is quite bright at Kp = 10. The transits have a distinct asymmetric shape with a steeper ingress and slower egress that can be ascribed to objects with a trailing dust tail passing over the stellar disc. There are three deeper transits with depths of ≃ 0.1 per cent that last for about a day, and three that are several times more shallow and of shorter duration. The transits were found via an exhaustive visual search of the entire Kepler photometric data set, which we describe in some detail. We review the methods we use to validate the Kepler data showing the comet transits, and rule out instrumental artefacts as sources of the signals. We fit the transits with a simple dust-tail model, and find that a transverse comet speed of ˜35-50 km s-1 and a minimum amount of dust present in the tail of ˜1016 g are required to explain the larger transits. For a dust replenishment time of ˜10 d, and a comet lifetime of only ˜300 d, this implies a total cometary mass of ≳3 × 1017 g, or about the mass of Halley's comet. We also discuss the number of comets and orbital geometry that would be necessary to explain the six transits detected over the 4 yr of Kepler prime-field observations. Finally, we also report the discovery of a single comet-shaped transit in KIC 11084727 with very similar transit and host-star properties.

Trajectories of charged dust grains in the cometary environment

NASA Astrophysics Data System (ADS)

Horanyi, M.; Mendis, D. A.

1985-07-01

Using a simple model of the particles and fields environment of a comet, the trajectories of the smallest (micron- and submicron-sized) dust grains that are expected to be released from a cometary nucleus are calculated. It is shown that electromagnetic forces play a crucial role in the dynamics of these particles. The present calculations indicate not only the asymmetry of the sunward dust envelopes that have been suggested earlier by other authors, but they also indicate the possible existence of wavy dust features far down the tail, reminiscent of the peculiar wavy dust feature observed in the dust tail of Comet Ikeya-Seki 1965f. The importance of these findings in studying the lower end of the cometary dust mass spectrum during the forthcoming fly-by missions to Comet Halley is underscored.

Dust evolution from comets

NASA Technical Reports Server (NTRS)

Sekanina, Z.

1976-01-01

The studies of the evolution of cometary debris are reviewed. The subject is divided into three major sections: (1) the developments in the immediate vicinity of the cometary nucleus, which is the source of the dust; (2) the formation of the dust tail; and (3) the blending of the debris with the dust component of interplanetary matter. The importance of the physical theory of comets is emphasized for the understanding of the early phase of evolution. A physico-dynamical model designed to analyze the particle-emission mechanism from the distribution of light in the dust tail is described and the results are presented. Increased attention is paid to large particles because of their importance for the evolution of the zodiacal cloud. Finally, implications are discussed for the future in situ investigations of comets.

Dust evolution from comets

NASA Technical Reports Server (NTRS)

Sekanina, Z.

1977-01-01

The studies of the evolution of cometary debris are reviewed. The subject is divided into three major sections: (1) the developments in the immediate vicinity of the cometary nucleus, which is the source of the dust; (2) the formation of the dust tail; and (3) the blending of the debris with the dust component of interplanetary matter. The importance of the physical theory of comets is emphasized for the understanding of the early phase of the evolution of cometary dust. A physico-dynamical model designed to analyze the particle-emission mechanism from the distribution of light in the dust tails is described and the results are presented. Increased attention is paid to large particles because of their importance for the evolution of the zodiacal cloud. Finally, implications are discussed for the future in situ investigations of comets.

Insecticide exposure affects DNA and antioxidant enzymes activity in honey bee species Apis florea and A. dorsata: Evidence from Punjab, Pakistan.

PubMed

Hayat, Khizar; Afzal, Muhammad; Aqueel, Muhammad Anjum; Ali, Sajjad; Saeed, Muhammad Farhan; Khan, Qaiser M; Ashfaq, Muhammad; Damalas, Christos A

2018-09-01

Insecticide exposure can affect honey bees in agro-ecosystems, posing behavioral stresses that can lead to population decline. In this study, insecticide incidence, DNA damage, and antioxidant enzyme activity were studied in Apis florea and A. dorsata honey bee samples collected from insecticide-treated and insecticide-free areas of Punjab, Pakistan. Seven insecticides: chlorpyrifos, dimethoate, imidacloprid, phorate, emamectin, chlorfenapyr, and acetamiprid were detected in seven samples of A. florea and five samples of A. dorsata. In total, 12 samples (22.2%) of honey bees were found positive to insecticide presence out of 54 samples. The most frequently detected insecticide was chlorpyrifos, which was found in four samples (7.4%), with a concentration ranging from 0.01 to 0.05 μg/g and an average concentration 0.03 μg/g. The comet assay or single cell gel electrophoresis assay, a simple way to measure DNA strand breaks in eukaryotic cells, was used to microscopically find damage of DNA at the level of a single cell. Comet tail lengths of DNA in A. florea and A. dorsata samples from insecticide-treated areas were significantly higher (P < 0.05) than samples from insecticide-free areas. The highest comet tail length (19.28 ± 2.67 μm) was observed in DNA of A. dorsata from insecticide-treated areas, while the minimum one (3.18 ± 1.46 μm) was noted in A. dorsata from insecticide-free areas. Catalase (CAT) activity did not vary significantly between honey bee samples from insecticide-treated and insecticide-free areas, while glutathione S-transferase (GST) activity showed a significant reduction in response to insecticide exposure. Significant positive correlations were detected between enzyme activity and insecticide concentration in honey bee species from insecticide-treated areas compared with control groups. Toxicity from pesticide exposure at sub-lethal levels after application or from exposure to pesticide residues should not be underestimated in honey bees, as it may induce physiological impairment that can decline honey bees' health. Copyright © 2018 Elsevier B.V. All rights reserved.

THE EXTRAORDINARY MULTI-TAILED MAIN-BELT COMET P/2013 P5

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jewitt, David; Agarwal, Jessica; Weaver, Harold

2013-11-20

Hubble Space Telescope observations of main-belt comet P/2013 P5 reveal an extraordinary system of six dust tails that distinguish this object from any other. Observations two weeks apart show dramatic morphological change in the tails while providing no evidence for secular fading of the object as a whole. Each tail is associated with a unique ejection date, revealing continued, episodic mass loss from the 0.24 ± 0.04 km radius nucleus over the last five months. As an inner-belt asteroid and probable Flora family member, the object is likely to be highly metamorphosed and unlikely to contain ice. The protracted periodmore » of dust release appears inconsistent with an impact origin, but may be compatible with a body that is losing mass through a rotational instability. We suggest that P/2013 P5 has been accelerated to breakup speed by radiation torques.« less

Observations of a comet on collision course with the sun.

PubMed

Michels, D J; Sheeley, N R; Howard, R A; Koomen, M J

1982-02-26

A brilliant new comet (1979 XI: Howard-Koomen-Michels) was discovered in data from the Naval Research Laboratory's orbiting SOLWIND coronagraph. An extensive sequence of pictures, telemetered from the P78-1 satellite, shows the coma, accompanied by a bright and well-developed tail, passing through the coronagraph's field of view at afew million kilometers from the sun. Preliminary orbital calculations based on the observed motion of the comet's head and morphology of the tail indicate that this previously unreported object is a sungrazing comet and may be one of the group of Kreutz sungrazers. It appears from the data that the perihelion distance was less than 1 solar radius, so that the cometary nucleus encountered dense regions of the sun's atmosphere, was completely vaporized, and did not reappear after the time of closest approach to the sun. After this time, however, cometary debris, scattered into the ambient solar wind, caused a brightening of the corona over one solar hemisphere and to heliocentric distances of 5 to 10 solar radii.

Neutral Na in comets tails: a chemical story

NASA Astrophysics Data System (ADS)

Ellinger, Y.; Pauzat, F.; Mousis, O.; Guilbert-Lepoutre, A.; Leblanc, F.; Ali-Dib, M.; Doronin, M.; Zicler, E.; Doressoundiram, A.

2015-10-01

The origin of the neutral sodium comet tail discovered in comet Hale-Bopp in 1997 is still a matter of discussion. Here we propose a scenario which is based on chemical grounds. The starting point is the chemical trapping of the Na+ ion in the refractory material during the condensation phase of the protosolar nebula, followed by its incorporation in the building blocks of the comets parent bodies. In the next step, the Na+ ions are washed out of the refractory material by the water formed by the melting of the ice due to the heat released in the radioactive decay of short period elements. When the water freezes again, the Na+ ion looses its positive charge to evolve progressively toward a neutral atom when approaching the surface of the ice. As shown by high-level numerical simulations based on first principle periodic density functional theory (DFT) to describe the solid structure of the ice, it is a neutral Na that is ejected with the sublimation of the ice top layer.

Effects of lead nitrate and sodium selenite on DNA damage and oxidative stress in diabetic and non-diabetic rat erythrocytes and leucocytes.

PubMed

Baş, Hatice; Kalender, Yusuf; Pandir, Dilek; Kalender, Suna

2015-05-01

The adverse effects of lead nitrate (LN) and the preventive role of sodium selenite were investigated in diabetic and non-diabetic rat blood by measuring trolox equivalent antioxidant capacity (TEAC), ferric reducing antioxidant power (FRAP), malondialdehyde (MDA) levels and activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione-S-transferase (GST) also by evaluating DNA damage with comet assay. LN increased the levels of MDA, tail DNA%, mean tail length and tail moment, decreased the enzymes activities, FRAP and TEAC values. In sodium selenite+LN group, we observed the protective effect of sodium selenite on examining parameters. Diabetes caused alterations on these parameters, too. We found that sodium selenite did not protect against diabetes caused damages. As a result, LN caused toxic effects on blood cells and sodium selenite alleviated this toxicity but it did not show preventive effect against diabetes. Also, LN caused more harmfull effects in diabetic groups than non-diabetic groups. Copyright © 2015 Elsevier B.V. All rights reserved.

Analysis of the tail structures of comet P/Halley 1910 II

NASA Astrophysics Data System (ADS)

Voelzke, M. R.; Izaguirre, L. S.

Eight hundred and eighty six images from September 1909 to May 1911 are analysed for the purpose of identifying, measuring and correlating the morphological structures along the plasma tail of P/Halley. These images are from the Atlas of Comet Halley 1910 II (Donn et al. 1986). A systematic visual analysis revealed 304 wavy structures along the main tail and 164 along the secondary tails, 41 solitary waves (solitons), 13 Swan-like tails, 26 disconnection events (DEs), 166 knots and six shells. While the wavy structures denote undulations or a train of waves, the solitons refer to the formations usually denominated kinks. In general, it is possible to associate the occurrence of a DE and/or a Swan-Tail with the occurrence of a knot, but the last one may occur independently. It is also possible to say that the solitons occur in association with the wavy structures, but the reverse is not true. The 26 DEs documented in 26 different images allowed the derivation of two onsets of DEs, i.e., the time when the comet supposedly crossed a frontier between magnetic sectors of the solar wind. Both onsets of DEs were determined after the perihelion passage with an average of the corrected velocities Vc equal to (57 ± 15) km s-1. The mean value of the corrected wavelength λ c measured in 70 different wavy structures is equal to (1.7 ± 0.1) × 106 km and the mean amplitude A of the wave (measured in the same 70 wavy structures cited above) is equal to (1.4 ± 0.1) × 105 km. The mean value of the corrected cometocentric phase velocity Vpc measured in 20 different wavy structures is equal to (168 ± 28) km s-1. The average value of the corrected velocities Vkc of the knots measured in 36 different images is equal to (128 ± 12) km s-1. There is a tendency for A and λ c to increase with increasing cometocentric distance. The preliminary results of this work agree with the earlier research from Voelzke and Matsuura (1998), which analysed comet P/Halley's tail structures in its last apparition in 1986. Donn, B., Rahe, J. and Brandt, J.C. (1986) Atlas of Comet Halley 1910 II. NASA SP-488, NASA Scientific and Technical Information Branch, 1-600. Voelzke, M.R. and Matsuura, O.T. (1998) Planet. Space Sci. 46 (8), 835-841.

The natural history of Halley's comet

NASA Astrophysics Data System (ADS)

McLaughlin, W. I.

1981-07-01

The 1986 apparition of Halley's comet will be the subject of numerous space probes, planned to determine the chemical nature and physical structure of comet nuclei, atmospheres, and ionospheres, as well as comet tails. The problems of cometary origin remain inconclusive, with theories ranging from a purely interstellar origin to their being ejecta from the Galilean satellites of Jupiter. Comets can be grouped into one of two classes, depending on their periodicity, and statistical mechanics of the entire Jovian family of comets can be examined under the equilibrium hypothesis. Comet anatomy estimations have been determined, and there is speculation that comet chemistry may have been a factor in the origin of life on earth. Halley's comet was first noted using Newton's dynamical methods, and Brady (1972) attempted to use the comet as a gravitational probe in search of a trans-Plutonian planet. Halley's orbit is calculated by combination of ancient observations and modern scientific methods.

PROBING THE SOLAR WIND ACCELERATION REGION WITH THE SUN-GRAZING COMET C/2002 S2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Giordano, S.; Raymond, J. C.; Lamy, P.

Comet C/2002 S2, a member of the Kreutz family of sungrazing comets, was discovered in white-light images of the Large Angle and Spectromeric Coronagraph Experiment coronagraph on the Solar and Heliospheric Observatory (SOHO) on 2002 September 18 and observed in H I Lyα emission by the SOHO Ultraviolet Coronagraph Spectrometer (UVCS) instrument at four different heights as it approached the Sun. The H I Lyα line profiles detected by UVCS are analyzed to determine the spectral parameters: line intensity, width, and Doppler shift with respect to the coronal background. Two-dimensional comet images of these parameters are reconstructed at the differentmore » heights. A novel aspect of the observations of this sungrazing comet data is that, whereas the emission from most of the tail is blueshifted, that along one edge of the tail is redshifted. We attribute these shifts to a combination of solar wind speed and interaction with the magnetic field. In order to use the comet to probe the density, temperature, and speed of the corona and solar wind through which it passes, as well as to determine the outgassing rate of the comet, we develop a Monte Carlo simulation of the H I Lyα emission of a comet moving through a coronal plasma. From the outgassing rate, we estimate a nucleus diameter of about 9 m. This rate steadily increases as the comet approaches the Sun, while the optical brightness decreases by more than a factor of 10 and suddenly recovers. This indicates that the optical brightness is determined by the lifetimes of the grains, sodium atoms, and molecules produced by the comet.« less

Comet ISON Approaching the Sun [still

NASA Image and Video Library

2013-11-27

This movie from NASA’s STEREO spacecraft's Heliospheric Imager shows Comet ISON, Mercury, Comet Encke and Earth over a five-day period from Nov. 20 to Nov. 25, 2013. The sun sits right of the field of view of this camera. Comet ISON, which will round the sun on Nov. 28, is what's known as a sungrazing comet, due to its close approach. Foreshortening or the angle at which these images were obtained make Earth appear as if it is closer to the sun than Mercury. If you look closely you will also see a dimmer and smaller comet Encke near comet ISON. A comet’s journey through the solar system is perilous and violent. A giant ejection of solar material from the sun could rip its tail off. Before it reaches Mars -- at some 230 million miles away from the sun -- the radiation of the sun begins to boil its water, the first step toward breaking apart. And, if it survives all this, the intense radiation and pressure as it flies near the surface of the sun could destroy it altogether. Even if the comet does not survive, tracking its journey will help scientists understand what the comet is made of, how it reacts to its environment, and what this explains about the origins of the solar system. Closer to the sun, watching how the comet and its tail interact with the vast solar atmosphere can teach scientists more about the sun itself. Image Credit: NASA/STEREO NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Hubble's Last Look at Comet ISON Before Perihelion

NASA Image and Video Library

2013-11-22

As of mid-November, ISON is officially upon us. Using Hubble, we've taken our closest look yet at the innermost region of the comet, where geysers of sublimating ice are fueling a spectacular tail. Made from observations on November 2nd, the image combines pictures of ISON taken through blue and red filters. As we expect, the round coma around ISON's nucleus is blue and the tail has a redder hue. Ice and gas in the coma reflect blue light from the Sun, while dust grains in the tail reflect more red light than blue light. This is the most color separation we've seen so far in ISON -- that's because the comet, nearer than ever to the Sun, is brighter and more structured than ever before. We've certainly come a long way since Hubble started observing Comet ISON, way back in April. Of course, our eight-month retrospective pales in comparison with ISON's own journey, which started some 10,000 years ago in the Oort cloud. ISON will come closest to the Sun on November 28, a point in its orbit known as perihelion. What's remarkable here is that the entire ISON, this awesome, shimmery space tadpole, is being produced from a dusty ball of ice estimated to be a few kilometers in diameter. Compared to ISON's full extent, Hubble's latest image is tiny. It only shows the very base of the tail. Yet even in this closest closeup we've ever had, a single pixel spans 24 km across the comet. Now that Comet ISON is close, amateur astromers rule the day. But Hubble observations, including this latest image, are still providing key insights into the science and spectacle of a comet we hope will continue to impress. Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA) -------- More details on Comet ISON: Comet ISON began its trip from the Oort cloud region of our solar system and is now travelling toward the sun. The comet will reach its closest approach to the sun on Thanksgiving Day -- 28 Nov 2013 -- skimming just 730,000 miles above the sun's surface. If it comes around the sun without breaking up, the comet will be visible in the Northern Hemisphere with the naked eye, and from what we see now, ISON is predicted to be a particularly bright and beautiful comet. Catalogued as C/2012 S1, Comet ISON was first spotted 585 million miles away in September 2012. This is ISON's very first trip around the sun, which means it is still made of pristine matter from the earliest days of the solar system’s formation, its top layers never having been lost by a trip near the sun. Comet ISON is, like all comets, a dirty snowball made up of dust and frozen gases like water, ammonia, methane and carbon dioxide -- some of the fundamental building blocks that scientists believe led to the formation of the planets 4.5 billion years ago. NASA has been using a vast fleet of spacecraft, instruments, and space- and Earth-based telescope, in order to learn more about this time capsule from when the solar system first formed. The journey along the way for such a sun-grazing comet can be dangerous. A giant ejection of solar material from the sun could rip its tail off. Before it reaches Mars -- at some 230 million miles away from the sun -- the radiation of the sun begins to boil its water, the first step toward breaking apart. And, if it survives all this, the intense radiation and pressure as it flies near the surface of the sun could destroy it altogether. This collection of images show ISON throughout that journey, as scientists watched to see whether the comet would break up or remain intact. The comet reaches its closest approach to the sun on Thanksgiving Day -- Nov. 28, 2013 -- skimming just 730,000 miles above the sun’s surface. If it comes around the sun without breaking up, the comet will be visible in the Northern Hemisphere with the naked eye, and from what we see now, ISON is predicted to be a particularly bright and beautiful comet. ISON stands for International Scientific Optical Network, a group of observatories in ten countries who have organized to detect, monitor, and track objects in space. ISON is

Cytostatic and genotoxic effect of temephos in human lymphocytes and HepG2 cells.

PubMed

Benitez-Trinidad, A B; Herrera-Moreno, J F; Vázquez-Estrada, G; Verdín-Betancourt, F A; Sordo, M; Ostrosky-Wegman, P; Bernal-Hernández, Y Y; Medina-Díaz, I M; Barrón-Vivanco, B S; Robledo-Marenco, M L; Salazar, A M; Rojas-García, A E

2015-06-01

Temephos is an organophosphorus pesticide that is used in control campaigns against Aedes aegypti mosquitoes, which transmit dengue. In spite of the widespread use of temephos, few studies have examined its genotoxic potential. The aim of this study was to evaluate the cytotoxic, cytostatic and genotoxic effects of temephos in human lymphocytes and hepatoma cells (HepG2). The cytotoxicity was evaluated with simultaneous staining (FDA/EtBr). The cytostatic and genotoxic effects were evaluated using comet assays and the micronucleus technique. We found that temephos was not cytotoxic in either lymphocytes or HepG2 cells. Regarding the cytostatic effect in human lymphocytes, temephos (10 μM) caused a significant decrease in the percentage of binucleated cells and in the nuclear division index as well as an increase in the apoptotic cell frequency, which was not the case for HepG2 cells. The comet assay showed that temephos increased the DNA damage levels in human lymphocytes, but it did not increase the MN frequency. In contrast, in HepG2 cells, temephos increased the tail length, tail moment and MN frequency in HepG2 cells compared to control cells. In conclusion, temephos causes stable DNA damage in HepG2 cells but not in human lymphocytes. These findings suggest the importance of temephos biotransformation in its genotoxic effect. Copyright © 2015. Published by Elsevier Ltd.

RELATIVE ACTIN NUCLEATION PROMOTION EFFICIENCY BY WASP AND WAVE PROTEINS IN ENDOTHELIAL CELLS

PubMed Central

Kang, Hyeran; Wang, Jingjing; Longley, Sarah J.; Tang, Jay X.; Shaw, Sunil K.

2010-01-01

The mammalian genome encodes multiple WASP1 (Wiskott-Aldrich Syndrome Protein)/WAVE (WASP-family Verprolin homologous) proteins. Members of this family interact with the Arp (actin related protein) 2/3 complex to promote growth of a branched actin network near the plasma membrane or the surface of moving cargos. Arp2/3 mediated branching can further lead to formation of comet tails (actin rockets). Despite their similar domain structure, different WASP/WAVE family members fulfill unique functions that depend on their subcellular location and activity levels. We measured the relative efficiency of actin nucleation promotion of full length WASP/WAVE proteins in a cytoplasmic extract from primary human umbilical vein endothelial cells (HUVEC). In this assay WAVE2 and WAVE3 complexes showed higher nucleation efficiency than WAVE1 and N-WASP, indicating distinct cellular controls for different family members. Previously, WASP and N-WASP were the only members that were known to stimulate comet formation. We observed that in addition to N-WASP, WAVE3 also induced short actin tails, and the other WAVEs induced formation of asymmetric actin shells. Differences in shape and structure of actin-based growth may reflect varying ability of WASP/WAVE proteins to break symmetry of the actin shell, possibly by differential recruitment of actin bundling or severing (pruning or debranching) factors. PMID:20816932

Histopathological and genotoxic effects of chlorpyrifos in rats.

PubMed

Ezzi, Lobna; Belhadj Salah, Imen; Haouas, Zohra; Sakly, Amina; Grissa, Intissar; Chakroun, Sana; Kerkeni, Emna; Hassine, Mohsen; Mehdi, Meriem; Ben Cheikh, Hassen

2016-03-01

This study aims to investigate the effects of chlorpyrifos's sub-acute exposure on male rats. Two groups with six animals each were orally treated, respectively, with 3.1 mg/kg b w and 6.2 mg/kg b w of chlorpyrifos during 4 weeks. The genotoxic effect of chlopyrifos was investigated using the comet assay and the micronucleus test. Some hematological and liver's histopathological changes were also evaluated. Results revealed that chlorpyrifos induced histopathological alterations in liver parenchyma. The lymphoid infiltration observed in liver sections and the increase in white blood cells parameter are signs of inflammation. A significant increase in the platelet' count and in polychromatic erythrocytes/normochromatic erythrocytes (PCE/NCE) ratio was observed in chlorpyrifos-treated groups which could be due to the stimulatory effect of chlorpyrifos on cell formation in the bone marrow at lower doses. In addition, the increase of bone marrow micronucleus percentage and the comet tail length revealed a genotoxic potential of chlorpyrifos in vivo.

Pulsewidth-dependent nature of laser-induced DNA damage in RPE cells

NASA Astrophysics Data System (ADS)

Hall, Rebecca M.; Glickman, Randolph D.; Rockwell, Benjamin A.; Kumar, Neeru; Noojin, Gary D.

2001-07-01

Ultrashort pulse laser radiation may produce cellular damage through unique mechanisms. Primary cultures of bovine retinal pigment epithelial (RPE) cells were exposed to the out put of a Ti:Sapphire laser producing 30 fs (mode-locked) pulses, 44 amplified fs pulses, or continuous wave exposures at 800 nm. Laser exposures at and below the damage threshold were studied. DNA damage was detected using single cell gel electrophoresis (comet assay). Unexposed (control) cells produced short tails with low tail moments. In contrast, all laser-exposed cells showed some degree of DNA fragmentation, but the size and shape of the resulting comets differed among the various modalities. CW-exposed cells produced generally light and relatively compact tails, suggesting fewer and larger DNA fragments, while mode-locked laser exposures (30 fs pulses) resulted in large and diffuse comets, indicating the DNA was fragmented into many very small pieces. Work is continuing to define the relationship of laser pulsewidth and intensity with the degree of DNA fragmentation. These results suggest that DNA damage may result from multiple mechanisms of laser-cell interaction, including multiphoton absorption.

Infrared observations of Comet Austin (1990 V) by the COBE/Diffuse Infrared Background Experiment

NASA Technical Reports Server (NTRS)

Lisse, C. M.; Freudenreich, H. T.; Hauser, M. G.; Kelsall, T.; Moseley, S. H.; Reach, W. T.; Silverberg, R. F.

1994-01-01

Comet Austin was observed by the Cosmic Background Explorer (COBE)/Diffuse Infrared Background Experiment (DIRBE) with broadband photometry at 1-240 micrometers during the comet's close passage by Earth in 1990 May. A 6 deg long (6 x 10(exp 6) km) dust tail was found at 12 and 25 micrometers, with detailed structure due to variations in particle properties and mass-loss rate. The spectrum of the central 42 x 42 sq arcmin pixel was found to agree with that of a graybody of temperature 309 +/- 5 K and optical depth 7.3 +/- 10(exp -8). Comparison with IUE and ground-based obervations indicates that particles of radius greater than 20 micrometers predominate by surface area. A mass-loss rate of 510 (+510/-205) kg/s and a total tail mass of 7 +/- 2 x 10(exp 10) kg was found for a model dust tail composed of Mie spheres with a differential particle mass distribution dn/d log m approx. m(exp -0.63) and 2:1 silicate:amorphous carbon composition by mass.

Asteroid (457175) 2008 GO98: a quasi-Hilda comet. (Italian Title: Asteroide (457175) 2008 GO98:una cometa "quasi-Hilda")

NASA Astrophysics Data System (ADS)

Bacci, P.

2017-12-01

Cometary activity in the asteroid (457175) 2008 GO98 was observed at San Marcello Observatory, highlighting an extended coma and a tail of 36 arcseconds. The asteroid should be classified as a quasi-Hilda comet.

The effect of gamma radiation on the Common carp (Cyprinus carpio): In vivo genotoxicity assessment with the micronucleus and comet assays.

PubMed

M K, Praveen Kumar; Soorambail K, Shyama; Bhagatsingh Harisingh, Sonaye; D'costa, Avelyno; Ramesh Chandra, Chaubey

2015-10-01

Radioactive wastes may be leached into freshwater, either accidentally or in industrial effluents. We have studied gamma radiation-induced DNA damage in the freshwater fish Cyprinus carpio. Fish were irradiated with 2-10Gy gamma radiation and genotoxic effects in blood cells were studied with the micronucleus (MN) and comet assays. Micronuclei and a dose-dependent increase in comet-tail DNA were seen in dose- and time-dependent studies. The highest % tail DNA was observed at 24h, declining until 72h, which may indicate the repair of radiation-induced DNA single-strand breaks after gamma radiation. However, double-stranded DNA damage may not have been repaired, as indicated by increased micronuclei at later periods. A positive correlation was observed between the comet and micronucleus assay results. This study confirms the mutagenic/genotoxic potential of gamma radiation in the Common carp, as well as the possible combined use of the micronucleus and comet assays for in vivo laboratory studies with fresh-water fish for screening the genotoxic potential of radioactive pollution. Copyright © 2015 Elsevier B.V. All rights reserved.

Genotoxicity testing: Comparison of the γH2AX focus assay with the alkaline and neutral comet assays.

PubMed

Nikolova, Teodora; Marini, Federico; Kaina, Bernd

2017-10-01

Genotoxicity testing relies on the quantitative measurement of adverse effects, such as chromosome aberrations, micronuclei, and mutations, resulting from primary DNA damage. Ideally, assays will detect DNA damage and cellular responses with high sensitivity, reliability, and throughput. Several novel genotoxicity assays may fulfill these requirements, including the comet assay and the more recently developed γH2AX assay. Although they are thought to be specific for genotoxicants, a systematic comparison of the assays has not yet been undertaken. In the present study, we compare the γH2AX focus assay with the alkaline and neutral versions of the comet assay, as to their sensitivities and limitations for detection of genetic damage. We investigated the dose-response relationships of γH2AX foci and comet tail intensities at various times following treatment with four prototypical genotoxicants, methyl methanesulfonate (MMS), N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), mitomycin C, and hydrogen peroxide (H 2 O 2 ) and we tested whether there is a correlation between the endpoints, i.e., alkali-labile sites and DNA strand breaks on the one hand and the cell's response to DNA double-strand breaks and blocked replication forks on the other. Induction of γH2AX foci gave a linear dose response and all agents tested were positive in the assay. The increase in comet tail intensity was also a function of dose; however, mitomycin C was almost completely ineffective in the comet assay, and the doses needed to achieve a significant effect were somewhat higher for some treatments in the comet assay than in the γH2AX foci assay, which was confirmed by threshold analysis. There was high correlation between tail intensity and γH2AX foci for MMS and H 2 O 2 , less for MNNG, and none for mitomycin C. From this we infer that the γH2AX foci assay is more reliable, sensitive, and robust than the comet assay for detecting genotoxicant-induced DNA damage. Copyright © 2017 Elsevier B.V. All rights reserved.

Comet Kohoutek

NASA Technical Reports Server (NTRS)

Gary, Gilmer A. (Editor)

1975-01-01

A compilation of scientific observations (workshop) is presented. Topics discussed are: (1) tail form, structure, and evolution; (2) hydroxyl related observations; (3) molecules and atoms in the coma and tail; (4) photometry and radiometry; and (5) spacecraft and ground based observation data. Color photographs are shown.

Interpreting sperm DNA damage in a diverse range of mammalian sperm by means of the two-tailed comet assay

PubMed Central

Cortés-Gutiérrez, Elva I.; López-Fernández, Carmen; Fernández, José Luis; Dávila-Rodríguez, Martha I.; Johnston, Stephen D.; Gosálvez, Jaime

2014-01-01

Key Concepts The two-dimensional Two-Tailed Comet assay (TT-comet) protocol is a valuable technique to differentiate between single-stranded (SSBs) and double-stranded DNA breaks (DSBs) on the same sperm cell.Protein lysis inherent with the TT-comet protocol accounts for differences in sperm protamine composition at a species-specific level to produce reliable visualization of sperm DNA damage.Alkaline treatment may break the sugar–phosphate backbone in abasic sites or at sites with deoxyribose damage, transforming these lesions into DNA breaks that are also converted into ssDNA. These lesions are known as Alkali Labile Sites “ALSs.”DBD–FISH permits the in situ visualization of DNA breaks, abasic sites or alkaline-sensitive DNA regions.The alkaline comet single assay reveals that all mammalian species display constitutive ALS related with the requirement of the sperm to undergo transient changes in DNA structure linked with chromatin packing.Sperm DNA damage is associated with fertilization failure, impaired pre-and post- embryo implantation and poor pregnancy outcome.The TT is a valuable tool for identifying SSBs or DSBs in sperm cells with DNA fragmentation and can be therefore used for the purposes of fertility assessment. Sperm DNA damage is associated with fertilization failure, impaired pre-and post- embryo implantation and poor pregnancy outcome. A series of methodologies to assess DNA damage in spermatozoa have been developed but most are unable to differentiate between single-stranded DNA breaks (SSBs) and double-stranded DNA breaks (DSBs) on the same sperm cell. The two-dimensional Two-Tailed Comet assay (TT-comet) protocol highlighted in this review overcomes this limitation and emphasizes the importance in accounting for the difference in sperm protamine composition at a species-specific level for the appropriate preparation of the assay. The TT-comet is a modification of the original comet assay that uses a two dimensional electrophoresis to allow for the simultaneous evaluation of DSBs and SSBs in mammalian spermatozoa. Here we have compiled a retrospective overview of how the TT-comet assay has been used to investigate the structure and function of sperm DNA across a diverse range of mammalian species (eutheria, metatheria, and prototheria). When conducted as part of the TT-comet assay, we illustrate (a) how the alkaline comet single assay has been used to help understand the constitutive and transient changes in DNA structure associated with chromatin packing, (b) the capacity of the TT-comet to differentiate between the presence of SSBs and DSBs (c) and the possible implications of SSBs or DSBs for the assessment of infertility. PMID:25505901

An Integrated Modeling Study for Coordinated Observations of H, O, OH, and H2O(+) Emissions in the Coma and Ion Tail of the Comet Hale-Bopp

NASA Technical Reports Server (NTRS)

Smyth, William H.

2001-01-01

This project has two overall objectives. One objective is to advance our general understanding of both the comet neutral atmosphere and the cometary plasma in the atmosphere and ion tall. The other objective is to obtain specific key information about comet Hale-Bopp that is generally important for Hale-Bopp studies. The primary emphasis in this project is to analyze, in a self-consistent manner, excellent quality high resolution image and line profile observations obtained by the University of Wisconsin for H, O, OH, and H2O+ emissions from the inner coma, outer coma, and ion tail of Hale-Bopp. The information on the spatial and velocity distributions of H2O neutral and ionized photo-products in the inner coma, outer coma, and in the H2O+ ion tail is of substantial and direct importance in the development of an integrated understanding of the complex structure and dynamics of the neutral and plasma species in the atmosphere of Hale-Bopp in particular and comets in general. The H2O production rate of Hale-Bopp is determined and, together with the other information related to the structure and dynamics of the neutral and plasma atmospheres obtained in this study, provide critical information important for a wide variety of research conducted by other groups.

Anticipated results from dust experiments on cometary missions

NASA Technical Reports Server (NTRS)

Kissel, J.; Fechtig, H.; Grun, E.

1981-01-01

The major scientific objectives of a mission are: to determine the chemical nature and physical structure of comet nuclei, and to characterize the changes that occur as a function of time orbital position; to characterize the chemical and physical nature of the atmospheres and ionospheres of comets as well as the processes that occur in them, and to characterize the development of the atmospheres and ionospheres as functions of time and orbital position; and to determine the nature of comet tails and processes by which they are formed, and to characterize the interaction of comets with the solar wind. Since dust is a major constituent of a comet, the achievement of these goals requires the intensive study of the paticulate emission from a comet.

Plasma diagnosis from thermal noise and limits on dust flux or mass in comet Giacobini-Zinner

NASA Technical Reports Server (NTRS)

Meyer-Vernet, N.; Couturier, P.; Hoang, S.; Perche, C.; Steinberg, J. L.; Fainberg, J.

1986-01-01

Thermal noise spectroscopy was used to measure the density and temperature of the main (cold) electron plasma population during two hours around the point of closest approach of the International Cometary Explorer (ICE) to comet Giacobini-Zinner. The time resolution was 18 seconds in the plasma tail and 54 seconds elsewhere. Near the tail axis, the maximum plasma density was 670/cu cm and the temperature slightly above one volt. Away from the axis, the plasma density dropped to 100/cu cm over 2000 km, then decreased to 10/cu cm over 15,000 km; at the plasma tail, the density fluctuated between 10 and 30/cu cm, and the temperature, between 100,000 and 400,000 K. No evidence was found of grain impact on the spacecraft or antennas in the plasma tail. This yields an upper limit for the dust flux or particle mass, indicating either fluxes or masses in the tail smaller than those implied by models or an anomalous grain structure. Outside the tail, and particularly near 100,000 km from its axis, impulsive noises indicating plasma turbulence were observed.

WHAMM Directs the Arp2/3 Complex to the ER for Autophagosome Biogenesis through an Actin Comet Tail Mechanism.

PubMed

Kast, David J; Zajac, Allison L; Holzbaur, Erika L F; Ostap, E Michael; Dominguez, Roberto

2015-06-29

Nucleation-promoting factors (NPFs) control the spatio-temporal activity of Arp2/3 complex in cells]. Thus, WASP and the WAVE complex direct the formation of branched actin networks at the leading edge during cell motility and endo/exocytosis, whereas the WASH complex is involved in endosomal transport. Less understood are WHAMM and JMY, two NPFs with similar domain architecture. JMY is found in the nucleus and the cytosol and is involved in transcriptional regulation, cell motility, and trans-Golgi transport. WHAMM was reported to bind microtubules and to be involved in ER to cis-Golgi transport. Here, we show that WHAMM directs the activity of Arp2/3 complex for autophagosome biogenesis through an actin-comet tail motility mechanism. Macroautophagy--the process by which cytosolic material is engulfed into autophagosomes for degradation and/or recycling--was recently shown to involve actin, but the mechanism is unknown. We found that WHAMM forms puncta that colocalize and comigrate with the autophagy markers LC3, DFCP1, and p62 through a WHAMM-dependent actin-comet tail mechanism. Under starvation, WHAMM and actin are observed at the interface between neighboring autophagosomes, whose number and size increase with WHAMM expression. Interfering with actin polymerization, inhibiting Arp2/3 complex, knocking down WHAMM, or blocking its interaction with Arp2/3 complex through mutagenesis all inhibit comet tail formation and reduce the size and number of autophagosomes. Finally, JMY shows similar localization to WHAMM and could be involved in similar processes. These results reveal a link between Arp2/3-complex-dependent actin assembly and autophagy. Copyright © 2015 Elsevier Ltd. All rights reserved.

May 8 Hubble View of ISON

NASA Image and Video Library

2013-11-22

Superficially resembling a skyrocket, Comet ISON is hurtling toward the Sun at a whopping 48,000 miles per hour. Its swift motion is captured in this image taken May 8, 2013, by NASA's Hubble Space Telescope. At the time the image was taken, the comet was 403 million miles from Earth, between the orbits of Mars and Jupiter. Unlike a firework, the comet is not combusting, but in fact is pretty cold. Its skyrocket-looking tail is really a streamer of gas and dust bleeding off the icy nucleus, which is surrounded by a bright, star-like-looking coma. The pressure of the solar wind sweeps the material into a tail, like a breeze blowing a windsock. As the comet warms as it moves closer to the Sun, its rate of sublimation will increase. The comet will get brighter and the tail grows longer. The comet is predicted to reach naked-eye visibility in November. The comet is named after the organization that discovered it, the Russia-based International Scientific Optical Network. This false-color, visible-light image was taken with Hubble's Wide Field Camera 3. Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA) -------- More details on Comet ISON: Comet ISON began its trip from the Oort cloud region of our solar system and is now travelling toward the sun. The comet will reach its closest approach to the sun on Thanksgiving Day -- 28 Nov 2013 -- skimming just 730,000 miles above the sun's surface. If it comes around the sun without breaking up, the comet will be visible in the Northern Hemisphere with the naked eye, and from what we see now, ISON is predicted to be a particularly bright and beautiful comet. Catalogued as C/2012 S1, Comet ISON was first spotted 585 million miles away in September 2012. This is ISON's very first trip around the sun, which means it is still made of pristine matter from the earliest days of the solar system’s formation, its top layers never having been lost by a trip near the sun. Comet ISON is, like all comets, a dirty snowball made up of dust and frozen gases like water, ammonia, methane and carbon dioxide -- some of the fundamental building blocks that scientists believe led to the formation of the planets 4.5 billion years ago. NASA has been using a vast fleet of spacecraft, instruments, and space- and Earth-based telescope, in order to learn more about this time capsule from when the solar system first formed. The journey along the way for such a sun-grazing comet can be dangerous. A giant ejection of solar material from the sun could rip its tail off. Before it reaches Mars -- at some 230 million miles away from the sun -- the radiation of the sun begins to boil its water, the first step toward breaking apart. And, if it survives all this, the intense radiation and pressure as it flies near the surface of the sun could destroy it altogether. This collection of images show ISON throughout that journey, as scientists watched to see whether the comet would break up or remain intact. The comet reaches its closest approach to the sun on Thanksgiving Day -- Nov. 28, 2013 -- skimming just 730,000 miles above the sun’s surface. If it comes around the sun without breaking up, the comet will be visible in the Northern Hemisphere with the naked eye, and from what we see now, ISON is predicted to be a particularly bright and beautiful comet. ISON stands for International Scientific Optical Network, a group of observatories in ten countries who have organized to detect, monitor, and track objects in space. ISON is managed by the Keldysh Institute of Applied Mathematics, part of the Russian Academy of Sciences. NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scienti

The genotoxic effect of oxcarbazepine on mice blood lymphocytes.

PubMed

Akbar, Huma; Khan, Ajmal; Mohammadzai, Imdadullah; Khisroon, Muhammad; Begum, Ilham

2018-04-01

This study was conducted to assess the amount of DNA damage caused by Oxcarbazepine (OXC) through single cell gel electrophoresis (SCGE) technique/comet assay. OXC derived from dibenzazepine series is an effective second generation antiepileptic drug (AED) for both children and adults. Side effects like genotoxic effects of AEDs are of prime importance resulting from toxic metabolites, free radicals and reactive oxygen species (ROS). Forty Eight adult male Bagg's albino mice (BALB/c) were randomly classified into eight groups, each comprising of six animals. Two of these groups were control and six were tested groups. Control groups were injected with 1% tween 80 while tested groups were injected with 10, 20, and 40 mg/kg-day OXC for seven days (acute therapy) and 28 days (subchronic therapy) in peritoneal cavity. Blood samples were collected by cardiac puncture and subjected to comet assay for the analysis of DNA damage. Per sample 100 cells were scored and classified according to comet tail length. The results showed that OXC in acute and long term therapies had significantly higher (p < 0.05) genotoxicity in treated groups as compared to control groups. Our study suggests that OXC may cause significant DNA damage in both acute as well as in subchronic therapies.

Analysis of the tail structures of comet P/Halley 1910 II

NASA Astrophysics Data System (ADS)

Voelzke, Marcos Rincon; Izaguirre, Liberdade

2012-07-01

Eight hundred and eighty six images from September 1909 to May 1911 are analysed for the purpose of identifying, measuring and correlating the morphological structures along the plasma tail of P/Halley. These images are from the Atlas of Comet Halley 1910 II (Donn et al., 1986). A systematic visual analysis revealed 304 wavy structures along the main tail and 164 along the secondary tails, 41 solitary waves (solitons), 13 Swan-like tails, 26 disconnection events (DEs), 166 knots (regions of higher density of matter) and six shells. While the wavy structures denote undulations or a train of waves, the solitons refer to the formations usually denominated kinks. In general, it is possible to associate the occurrence of a DE and/or a Swan-Tail with the occurrence of a knot, but the last one may occur independently. It is also possible to say that the solitons occur in association with the wavy structures, but the reverse is not true. The 26 DEs documented in 26 different images allowed the derivation of two onsets of DEs (Table 1), i.e., the time when the comet supposedly crossed a frontier between magnetic sectors of the solar wind (Brandt and Snow, 2000). Both onsets of DEs were determined after the perihelion passage with an average of the corrected velocities Vc equal to (57 ± 15) km/s. The mean value of the corrected wavelength c measured in 70 different wavy structures is equal to (1.7 ± 0.1) x 10^6 km and the mean amplitude A of the wave (measured in the same 70 wavy structures cited above) is equal to (1.4 ± 0.1) x 10^5 km. The mean value of the corrected cometocentric phase velocity Vpc measured in 20 different wavy structures is equal to (168 ± 28) km/s. The average value of the corrected velocities Vkc of the knots measured in 36 different images is equal to (128 ± 12) km/s. There is a tendancy for A and c to increase with increasing cometocentric distance. The results of this work agree with the earlier research from Voelzke and Matsuura (1998), which analysed comet P/Halley's tail structures in its last apparition in 1986.

Morphological analysis of the tail structures of comet P/Halley 1910 II

NASA Astrophysics Data System (ADS)

Voelzke, M. R.; Izaguirre, L. S.

2012-05-01

For the purpose of identifying, measuring and correlating the morphological structures along the plasma tail of P/Halley 886 images from September 1909 to May 1911 are analysed. These images are from the Atlas of Comet Halley 1910 II (Donn et al., 1986). A systematic visual analysis revealed 304 wavy structures along the main tail and 164 along the secondary tails, 41 solitary waves (solitons), 13 Swan-like tails, 26 disconnection events (DEs), 166 knots (regions of higher density of matter) and six shells. While the wavy structures denote undulations or a train of waves, the solitons refer to the formations usually denominated as kinks. In general, it is possible to associate the occurrence of a DE and/or a Swan-Tail with the occurrence of a knot, but the last one may occur independently. It is also possible to say that the solitons occur in association with the wavy structures, but the reverse is not true. The 26 DEs documented in 26 different images allowed the derivation of two onsets of DEs (Table 1), i.e., the time when the comet supposedly crossed a frontier between magnetic sectors of the solar wind (Brandt and Snow, 2000). Both onsets of DEs were determined after the perihelion passage with an average of the corrected velocities Vc equal to (57±15) km s-1. The mean value of the corrected wavelength λc measured in 70 different wavy structures is equal to (1.7±0.1)×106 km and the mean amplitude A of the wave (measured in the same 70 wavy structures cited above) is equal to (1.4±0.1)×105 km. The mean value of the corrected cometocentric phase velocity Vpc measured in 20 different wavy structures is equal to (168±28) km s-1. The average value of the corrected velocities Vkc of the knots measured in 36 different images is equal to (128±12) km s-1. There is a tendency for A and λc to increase with increasing cometocentric distance. The results of this work agree with the earlier research from Voelzke and Matsuura (1998), which analysed comet P/Halley's tail structures in its last apparition in 1986.

Temporal Evolution of the Morphological Tail Structures of Comet P/Halley 1910 II

NASA Astrophysics Data System (ADS)

Izaguirre, L. S.; Voelzke, M. R.

2004-08-01

Eight hundred and eighty six images from September 1909 to May 1911 are analysed for the purpose of identifying, measuring and correlating the morphological structures along the plasma tail of P/Halley. These images are from the Atlas of Comet Halley 1910 II (Donn et al., 1986). A systematic visual analysis revealed 304 wavy structures (Yi et al., 1998) along the main tail and 164 along the secondary tails, 41 solitary waves (solitons) (Roberts, 1985), 13 Swan-like tails (Jockers, 1985), 26 disconnection events (DEs) (Voelzke, 2002a), 166 knots (Voelzke et al., 1997) and six shells (Schulz and Schlosser, 1989). While the wavy structures denote undulations or a train of waves, the solitons refer to the formations usually denominated kinks (Tomita et al., 1987). In general, it is possible to associate the occurrence of a DE and/or a Swan-Tail with the occurrence of a knot, but the last one may occur independently. It is also possible to say that the solitons occur in association with the wavy structures, but the reverse is not true. The 26 DEs documented in 26 different images allowed the derivation of two onsets of DEs, i.e., the time when the comet supposedly crossed a frontier between magnetic sectors of the solar wind (Brandt and Snow, 2000). Both onsets of DEs were determined after the perihelion passage with an average of the corrected velocities Vc equal to (57 ± 15) km s-1. The mean value of the corrected wavelength lc measured in 70 different wavy structures is equal to (1.7 ± 0.1) x 10^6 km and the mean amplitude A of the wave (measured in the same 70 wavy structures cited above) is equal to (1.4 ± 0.1) x 10^5 km. The mean value of the corrected cometocentric phase velocity Vpc measured in 20 different wavy structures is equal to (168 ± 28) km s-1. The average value of the corrected velocities Vkc of the knots measured in 36 different images is equal to (128 ± 12) km s-1. There is a tendency for A and lc to increase with increasing cometocentric distance. The preliminary results of this work agree with the earlier research from Voelzke and Matsuura (1998), which analysed comet P/Halley's tail structures in its last apparition in 1986.

Gas Distributions in Comet ISON’s Coma: Concurrent Integral-Field Spectroscopy and Narrow-band Imaging.

NASA Astrophysics Data System (ADS)

Schmidt, Carl; Johnson, Robert E.; Baumgardner, Jeffrey; Mendillo, Michael

2014-11-01

At a solar distance of 0.44 AU, Oort cloud comet C/2012 S1 (ISON) exhibited an outburst phase that was observed by small telescopes at the McDonald Observatory. In conjunction with narrow-band (14Å) imaging over a wide-field, an image-slicer spectrograph ( 20,000) simultaneously measured the spatial distribution of ISON’s coma over a 1.6 x 2.7 arcminute field made up of 246 individual spectra. More than fifty emission lines from C2, NH2, CO, H2O+ and Na were observed within a single Echelle order spanning 5868Å to 5930Å. Spatial reconstructions of these species reveal that ISON’s coma was quite elongated several thousand km along the axis perpendicular to its motion. The ion tail appeared distinctly broader than the neutral Na tail, providing strong evidence that Na in the coma did not originate by dissociative recombination of a sodium bearing molecular ion. Production rates increased from 1.6 ± 0.3 x 1023 to 5.8 ± 1 x 1023 Na atoms/s within 24 hours, outgassing much less than comparable comets relative to ISON’s water production. The anti-sunward Na tail was imaged >106 km from the nucleus. Its distribution indicates origins both near the nucleus and in the dust tail, with the ratio of these Na sources varying on hourly timescales due to outburst activity.

Comets and the origin of life; Proceedings of the Fifth College Park Colloquium on Chemical Evolution, University of Maryland, College Park, MD, October 29-31, 1980

NASA Technical Reports Server (NTRS)

Ponnamperuma, C.

1981-01-01

Papers are presented concerning the characteristics of comets and their possible role in the origin of life. Specific topics include the characteristics, origin and structure of the cometary nucleus, cometary chemical abundances, the nature of interplanetary dust and its entry into terrestrial planet atmospheres, and the mechanism of ray closure in comet tails. Attention is also given to chemically evolved interstellar dust as a source of prebiotic material, the relation of comets to paleoatmospheric photochemistry, comets as a vehicle for panspermia, limits to life posed by extreme environments, and the status of cometary space missions as of 1980.

The International Cometary Explorer (ICE) mission to comet Giacobini-Zinner (G/Z)

NASA Technical Reports Server (NTRS)

Brandt, J. C.; Farquhar, R. W.; Maran, S. P.; Niedner, M. B.; Von Rosenvinge, T.

1985-01-01

The primary objectives of the International Cometary Explorer (ICE) mission is to provide in situ data on the interaction between solar wind and the atmosphere of the P/Giacobini-Zinner comet (G/Z), making measurements of particles, fields, and waves while passing through the cometary tail of G/Z on September 11, 1985. Following the G/Z tail intercept, the ICE measurements will complement the later upstream measurements obtained by the Comet Halley probe. The major ICE payload includes a vector helium magnetometer, the plasma-wave experiment, the radio-wave experiment, the plasma-electron experiment, and the plasma ion experiment. Other experiments are intended to measure energetic protons, X-rays, low energy to high energy cosmic rays, cosmic ray electrons, and gamma-ray bursts. The ICE measurements of G/Z will be supplemented with ground-based measurements. Schematic diagrams are included.

Analysis of the ICE combiner for multiple antenna arraying

NASA Technical Reports Server (NTRS)

Foster, C.; Marina, M.

1987-01-01

The passage of the International Cometary Explorer (ICE) through the tail of comet Giacobini-Zinner took place on September 11, 1985, at approximately 11:04 GMT. The signal-to-noise ratio of the data received from the ICE spacecraft during the comet encounter was improved by arraying the 64-m antenna channels A and B (RCP and LCP) with the two 34-m antennas. Specially designed combiners were built to combine the signals received by the three antennas at the different DSN sites to ensure that the spacecraft's weak signal was received. Although the ICE spacecraft was built with a 5-W transmitter and with a small antenna designed to provide data from no farther than 1 million miles, these combiners provided enough signal margin during the encounter to receive the ICE transmitted data from within the tail of comet Giacobini-Zinner, 44 million miles from earth.

The Rotational Properties of Multi-tailed Asteroid P/2013 P5

NASA Astrophysics Data System (ADS)

Gustafsson, Annika; Moskovitz, Nicholas; Levine, Stephen

2014-11-01

To date, there are twelve known celestial bodies in the Solar System, labeled Main Belt Comets (e.g. Hsieh & Jewitt, 2006) or Active Asteroids (Jewitt, 2012) that exhibit both asteroid and comet-like properties. Among them is P/2013 P5, a comet-asteroid transition object discovered by PAN-STARRS in August 2013. Observations made with the Hubble Space Telescope in September 2013 revealed that P/2013 P5 appears to have six comet-like dust tails. Jewitt et al. (2013) concluded that this extraordinary structure and activity cannot be explained by traditional near-surface ice sublimation or collision events ejecting particles from the asteroid’s surface. Instead, the most likely explanation is that this unusual object has been spun-up by YORP torques to a critical limit that has resulted in the rotational disruption of the asteroid causing the unique six-tail structure. This interpretation predicts that the nucleus of this comet-like asteroid should be in rapid rotation. In November 2013, broadband photometry of P/2013 P5 was obtained with Lowell Observatory’s 4-meter Discovery Channel Telescope using the Large Monolithic Imager to investigate the possibility of rapid rotation. On chip optimal aperture photometry was performed on P/2013 P5. At an apparent magnitude V=22.5 magnitude, we found no significant variability in the light curve at the level of 0.15 magnitudes. General morphology changes in the nucleus-coma system of the asteroid were also investigated. We will present our analysis of this search for variability in both time and spatially across the coma relative to the object’s center of brightness. Hsieh, H. H., & Jewitt, D. 2006, Science, 312, 561Jewitt, D. 2012, AJ, 143, 66Jewitt, D.C., Agarwal, J., Weaver, H., Mutchler, M., & Larson, S. 2013, ApL, 778

Comet giacobini-zinner: plasma description.

PubMed

Bame, S J; Anderson, R C; Asbridge, J R; Baker, D N; Feldman, W C; Fuselier, S A; Gosling, J T; McComas, D J; Thomsen, M F; Young, D T; Zwickl, R D

1986-04-18

A strong interaction between the solar wind and comet Giacobini-Zinner was observed oh 11 September 1985 with the Los Alamos plasma electron experiment on the International Cometary Explorer (ICE) spacecraft. As ICE approached an intercept point 7800 kilometers behind the nucleus from the south and receded to the north, upstream phenomena due to the comet were observed. Periods of enhanced electron heat flux from the comet as well as almost continuous electron density fluctuations were measured. These effects are related to the strong electron heating observed in the cometary interaction region and to cometary ion pickup by the solar wind, respectively. No evidence for a conventional bow shock was found as ICE entered and exited the regions of strongest interaction of the solar wind with the cometary environment. The outer extent of this strong interaction zone was a transition region in which the solar wind plasma was heated, compressed, and slowed. Inside the inner boundary of the transition region was a sheath that enclosed a cold intermediate coma. In the transition region and sheath, small-scale enhancements in density were observed. These density spikes may be due to an instability associated with cometary ion pickup or to the passage of ICE through cometary ray structures. In the center of the cold intermediate coma a narrow, high-density core of plasma, presumably the developing plasma tail was found. In some ways this tail can be compared to the plasma sheet in Earth's magnetotail and to the current sheet in the tail at Venus. This type of configuration is expected in the double-lobe magnetic topology detected at the comet, possibly caused by the theoretically expected draping of the interplanetary magnetic field around its ionosphere.

Optimal dose selection of N-methyl-N-nitrosourea for the rat comet assay to evaluate DNA damage in organs with different susceptibility to cytotoxicity.

PubMed

Kitamoto, Sachiko; Matsuyama, Ryoko; Uematsu, Yasuaki; Ogata, Keiko; Ota, Mika; Yamada, Toru; Miyata, Kaori; Funabashi, Hitoshi; Saito, Koichi

2015-07-01

The in vivo rodent alkaline comet assay (comet assay) is a promising technique to evaluate DNA damage in vivo. However, there is no agreement on a method to evaluate DNA damage in organs where cytotoxicity is observed. As a part of the Japanese Center for the Validation of Alternative Methods (JaCVAM)-initiative international validation study of the comet assay, we examined DNA damage in the liver, stomach, and bone marrow of rats given three oral doses of N-methyl-N-nitrosourea (MNU) up to the maximum tolerated dose based on systemic toxicity. MNU significantly increased the % tail DNA in all the organs. Histopathological analysis showed no cytotoxic effect on the liver, indicating clearly that MNU has a genotoxic potential in the liver. In the stomach, however, the cytotoxic effects were very severe at systemically non-toxic doses. Low-dose MNU significantly increased the % tail DNA even at a non-cytotoxic dose, indicating that MNU has a genotoxic potential also in the stomach. Part of the DNA damage at cytotoxic doses was considered to be a secondary effect of severe cell damage. In the bone marrow, both the % tail DNA and incidence of micronucleated polychromatic erythrocytes significantly increased at non-hematotoxic doses, which were different from the non-cytotoxic doses for liver and stomach. These findings indicate that an optimal dose for detecting DNA damage may vary among organs and that careful attention is required to select an optimum dose for the comet assay based on systemic toxicity such as mortality and clinical observations. The present study shows that when serious cytotoxicity is suggested by increased % hedgehogs in the comet assay, histopathological examination should be included for the evaluation of a positive response. Copyright © 2015 Elsevier B.V. All rights reserved.

Dust environment and dynamical history of a sample of short-period comets

NASA Astrophysics Data System (ADS)

Pozuelos, F. J.; Moreno, F.; Aceituno, F.; Casanova, V.; Sota, A.; López-Moreno, J. J.; Castellano, J.; Reina, E.; Diepvens, A.; Betoret, A.; Häusler, B.; Gonález, C.; Rodríguez, D.; Bryssinck, E.; Cortés, E.; García, F.; García, F.; Limón, F.; Grau, F.; Fratev, F.; Baldrís, F.; Rodriguez, F. A.; Montalbán, F.; Soldán, F.; Muler, G.; Almendros, I.; Temprano, J.; Bel, J.; Sánchez, J.; Lopesino, J.; Báez, J.; Hernández, J. F.; Martín, J. L.; Ruiz, J. M.; Vidal, J. R.; Gaitán, J.; Salto, J. L.; Aymamí, J. M.; Bosch, J. M.; Henríquez, J. A.; Martín, J. J.; Lacruz, J.; Tremosa, L.; Lahuerta, L.; Reszelsky, M.; Rodríguez, M.; Camarasa, M.; Campas, M.; Canales, O.; Dekelver, P. J.; Moreno, Q.; Benavides, R.; Naves, R.; Dymoc, R.; García, R.; Lahuerta, S.; Climent, T.

2014-08-01

Aims: In this work, we present an extended study of the dust environment of a sample of short-period comets and their dynamical history. With this aim, we characterize the dust tails when the comets are active, and we make a statistical study to determine their dynamical evolution. The targets selected were 22P/Kopff, 30P/Reinmuth 1, 78P/Gehrels 2, 115P/Maury, 118P/Shoemaker-Levy 4, 123P/West-Hartley, 157P/Tritton, 185/Petriew, and P/2011 W2 (Rinner). Methods: We use two different observational data sets: a set of images taken at the Observatorio de Sierra Nevada and, the Afρ curves provided by the amateur astronomical association Cometas-Obs. To model these observations, we use our Monte Carlo dust tail code. From this analysis, we derive the dust parameters, which best describe the dust environment: dust loss rates, ejection velocities, and size distribution of particles. On the other hand, we use a numerical integrator to study the dynamical history of the comets, which allows us to determine with a 90% confidence level the time spent by these objects in the region of Jupiter family comets. Results: From the Monte Carlo dust tail code, we derived three categories according to the amount of dust emitted: weakly active (115P, 157P, and Rinner), moderately active (30P, 123P, and 185P), and highly active (22P, 78P, and 118P). The dynamical studies showed that the comets of this sample are young in the Jupiter family region, where the youngest ones are 22P (~100 yr), 78P (~500 yr), and 118P (~600 yr). The study points to a certain correlation between comet activity and time spent in the Jupiter family region, although this trend is not always fulfilled. The largest particle sizes are not tightly constrained, so that the total dust mass derived should be regarded as a lower limit. Appendices are available in electronic form at http://www.aanda.org

Is the tail of 73P-B/Schwassman-Wachman 1 chasing its Remnant Nucleus?

NASA Technical Reports Server (NTRS)

Wooden, D. H.; Harker, D. E.; Woodward, C. E.; Ehrenfreund, P.; Geers, V. C.; Waters, L. B. F. M.; Cox, N.

2006-01-01

We report on imaging observations of comets 73P-B/Schwassmann-Wachmann 1 and 73P-C/Schwassmann-Wachmann 1 at the IRTF with SpeX (J, K) and MRSI (10 micron narrow band filter set) on 2006 Apr 17-19 UT and 2006 Jun 18-19, and at the VLT with VISIR (1 0 micron narrow band filters, 20 micron) on 2006 Apr 17 UT. Compared to when the comet was in the midst of breaking up in mid-April, in June the tail of 73P-B is much fainter and there is a compact coma detected well separated and ahead of its tail, and fainter than the tail. The width of the tail in J, K, and 10 micron images indicates that the pieces that were shed in April must still be outgassing and releasing small particles into the tail-shaped coma; small grains have relatively short lifetimes in the coma due to radiation pressure. The trailing tail is now well separated from the faint "leader of the pack" compact coma that we suppose is a remaining piece of the nucleus. It will be interesting to see post-perihelion if this "leading compact coma" object continues to gain distance on the debris and continues to weakly outgas and shed small grains. One wonders if it expended its volatiles (available to the surface) in breaking up; a short-lived release of volatiles occurred in the Deep Impact event with comet 9P/Tempel 1. 73P-C is extended with a more elongated coma structure closer to perihelion compared to 2006 Apr 18- 19 UT. The SEDs from 2006 Apr and Jun from SpeX-MIRSI (IRTF) are compared with VISIR (VLT) SEDs from 2006 Apr. Information on the heliocentric dependence of the activity and dust release yields insights into the origin of activity and the relationship between activity and grain size distribution/mineralogy.

Comet ISON Approaching the Sun [hd video

NASA Image and Video Library

2013-11-27

This movie from NASA’s STEREO spacecraft's Heliospheric Imager shows Comet ISON, Mercury, Comet Encke and Earth over a five-day period from Nov. 20 to Nov. 25, 2013. The sun sits right of the field of view of this camera. Comet ISON, which will round the sun on Nov. 28, is what's known as a sungrazing comet, due to its close approach. Foreshortening or the angle at which these images were obtained make Earth appear as if it is closer to the sun than Mercury. If you look closely you will also see a dimmer and smaller comet Encke near comet ISON. A comet’s journey through the solar system is perilous and violent. A giant ejection of solar material from the sun could rip its tail off. Before it reaches Mars -- at some 230 million miles away from the sun -- the radiation of the sun begins to boil its water, the first step toward breaking apart. And, if it survives all this, the intense radiation and pressure as it flies near the surface of the sun could destroy it altogether. Even if the comet does not survive, tracking its journey will help scientists understand what the comet is made of, how it reacts to its environment, and what this explains about the origins of the solar system. Closer to the sun, watching how the comet and its tail interact with the vast solar atmosphere can teach scientists more about the sun itself. Image Credit: NASA/STEREO NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Evaluation of genotoxic activity of maleic hydrazide, ethyl methane sulfonate, and N-nitroso diethylamine in Tradescantia.

PubMed

Alvarez-Moya, C; Santerre-Lucas, A; Zúñiga-González, G; Torres-Bugarín, O; Padilla-Camberos, E; Feria-Velasco, A

2001-01-01

To assess the genotoxic activity of N-nitroso diethylamine (NDEA), maleic hydrazide (MH), and ethyl methane sulfonate (EMS) using two systems: the comet assay on nuclei from Tradescantia, and the pink mutation test on Tradescantia staminal hairs (clone 4430). Tradescantia cups was obtained from Laboratorio de Citogenética y Mutagénesis del Centro de Ciencias de la Atmósfera de la Universidad Nacional Autónoma de México and treated with: N-nitroso diethylamine (NDEA) at 1, 5, 10 mM, maleic hydrazide (MH) at 1, 5, 10 mM and ethyl methane sulfonate (EMS) at 15, 30 and 45 mM; and used in both pink mutation assay and comet assay using cellular nuclei from Tradescantia staminal hairs. The observation of staminal hair was realized along eight days (6-14) after treatment), flowers produced day 14 after treatment were utilized done according to Underbrink. In previous reports on plants, were comet assay was used, breaking cellular wall and separating by centrifugation gradient are necessary. Here, nuclei from staminal hairs were obtained by squashing the cells (is not necessary to utilize to break special procedure cellular wall), collected using a nylon mesh of 80 Mm and next the comet assay was applied. Student's T test was the statistical test used for analyzing the comet assay data. Both assays showed a great sensitivity to the studied mutagens. A relationship between the dose-pink event and the dose-tail length was evident. Even though the Tradescantia mutation assay is a sensitive test with MH and EMS, low doses of NDEA were not able to induce a significant increase in the pink event frequencies; however, the comet assay was able to detect the mutagenic effect of NDEA at the same dose. Thus, it is clear that the comet assay is highly sensitive to the lowest dose of chemical mutagens. The comet assay on nuclei from Tradescantia staminal hairs is a useful tool to monitor genotoxic agents; it is simple, highly sensitive, and faster than the pink mutation test.

H2O(+) structures in the inner plasma tail of comet Austin

NASA Technical Reports Server (NTRS)

Jockers, Klaus; Bonev, T.; Geyer, E. H.

1992-01-01

We present images of comet Austin 1989c1 in the light of H2O(+) from which the contribution of the dust continuum and the gas coma was completely removed. We describe the behavior of the H2O(+) plasma in the inner coma where it is reliably observed for the first time.

Search for Dormant Comets in Near-Earth Space

NASA Astrophysics Data System (ADS)

Kim, Yoonyoung

2013-06-01

It is considered that comets have been injected into near-Earth space from outer region (e.g. Kuiper-belt region), providing rich volatile and organic compounds to the earth. Some comets are still active while most of them are dormant with no detectable tails and comae. Here we propose to make a multi-band photometric observation of near-Earth objects (NEOs) with comet-like orbits. We select our targets out of infrared asteroidal catalogs based on AKARI and WISE observations. With a combination of taxonomic types by Subaru observation and albedos by AKARI or WISE, we aim to dig out dormant comet candidates among NEOs. Our results will provide valuable information to figure out the dynamical evolution and fate of comets. We would like to emphasize that this is the first taxonomic survey of dormant comets to utilize the infrared data archive with AKARI and WISE.

Kohoutek - A great comet coming.

NASA Technical Reports Server (NTRS)

Maran, S. P.; Hobbs, R. W.

1973-01-01

Passing inside the earth's orbit in late November, the comet Kohoutek will travel through the inner solar system during a unique period in the history of the space program, when Skylab and Mariner Venus-Mercury are in operation and the new C-141 Airborne Infrared Observatory is ready for flight. It is planned to investigate comprehensively the nature and evolution of the coma and tails of the comet. The detailed goals of the investigation include the identification of the parent molecules of the gases observed in comets, the determination of the processes that break down the parent molecules, the study of the physical nature of transient events in the comet, and the measurement of the solar-wind velocity in the inner solar system.

Tidal disruption and the appearance of periodic comet Shoemaker-Levy 9

NASA Technical Reports Server (NTRS)

Sekanina, Z.; Chodas, P. W.; Yeomans, D. K.

1994-01-01

A unified model is formulated to interpret quantitatively the observed characteristics of the nuclear train, the two dust trails, and the tail region of P/Shoemaker-Levy 9 in terms of a collisionally modified rotation velocity distribution of the comet's debris. Since there is no evidence for the comet's out-gassing, the model does not assume activity. The discruption of the parent comet was due primarily to tidal stesses during its extremely close approach to Juptier in July 1992. The original nucleus is found to have been most probably approximately 5 km in radius or, equivalently, approximately 10(exp 17) g in mass. The dynamical separation of the debris occurred apparently approximately 2.2 hr after the perijove passage, even though the actual fragmentation of the original mass is likely to have begun before closest approach. Physical breakp was accompanied by ubiquitous low-velocity collisions among the particulates, resulting in a rearrangement of the initial rotaional velocities into a rapidly 'thermalized' distribution, characterized by a long tail of relatively high velocities for the debris that populates the dust trails far from the nuclear train. Compelling evidence is presented for secondary fragmentation events, indicative of the comet's continuing disintegration. Secondary fragmentation may be caused by rotational bursting of the massive fragments that had been cracked but unbroken during the tidal disruption. Impact conditions and possible interactions of the comet's debris with the jovian system during the encounter in July 1994 are described.

Comet Halley in 1910, as viewed from a Maltese perspective

NASA Astrophysics Data System (ADS)

Galea, Adrian

2009-07-01

Comet Halley's return in 1910 was keenly anticipated globally by scientists and the lay public alike. Although cometary science had progressed rapidly during the last quarter of the nineteenth century, superstition remained significant in different parts of the world and there were fears that people would die if the prediction that the Earth would pass through the comet's tail were correct. Malta was a small British island colony in the Mediterranean, and the inhabitants there were no exception. Local newspapers reported concerns from their readers and from foreign sources, but they also included reassuring scientific information about comets. Under the patronage of the colonial government a local amateur astronomer named Francis Reynolds reassured the public through lectures that he delivered. Overall the local population appeared to have been calm about the impending return. The first recorded sighting from Malta was on 24 April 1910 and the first naked eye sighting occurred the following day. Accounts were published in the local newspapers and in private correspondence, suggesting a high level of public interest in this object. No photographs of the comet from Malta have been traced, but the aforementioned Mr Reynolds and a well-known Maltese artist, G. Cali, did make a number of paintings. On the night when the Earth was due to pass through the comet's tail many local people congregated around the bastions of the city under an overcast sky in the early hours of the morning, but no untoward events were experienced.

Detection of radiation treatment of beans using DNA comet assay

NASA Astrophysics Data System (ADS)

Khan, Ashfaq A.; Khan, Hasan M.; Delincée, Henry

2002-03-01

A simple technique of microgel electrophoresis of single cells (DNA Comet Assay) enabled a quick detection of radiation treatment of several kinds of leguminous beans (azuki, black, black eye, mung, pinto, red kidney and white beans). Each variety was exposed to radiation doses of 0.5, 1 and 5kGy covering the permissible limits for insect disinfestation. The cells or nuclei from beans were extracted in cold PBS, embedded in agarose on microscope slides, lysed between 15 and 60min in 2.5% SDS and electrophoresis was carried out at a voltage of 2V/cm for 2-2.5min. After silver staining, the slides were evaluated through an ordinary transmission microscope. In irradiated samples, fragmented DNA stretched towards the anode and the damaged cells appeared as a comet. The density of DNA in the tails increased with increasing radiation dose. However, in non-irradiated samples, the large molecules of DNA remained relatively intact and there was only minor or no migration of DNA; the cells were round or had very short tails only. Hence, the DNA comet assay provides an inexpensive, rapid and relatively simple screening method for the detection of irradiated beans.

Biochemical and molecular alterations in freshwater mollusks as biomarkers for petroleum product, domestic heating oil.

PubMed

Al-Fanharawi, Ali Abdulhamza; Rabee, Adel M; Al-Mamoori, Ayad M J

2018-04-13

To investigate the effect one of the oil products, domestic heating oil (DHO), on freshwater mollusks, Unio tigridis and Viviparous bengalensis were exposed to three DHO concentrations for each species (5.8, 8.7, and 17.4 ml L -1 for mussels; 6.5, 9.7, and 19.5 mlL -1 for snails, respectively). Antioxidant enzymes (superoxide dismutase, catalase), malondialdehyde, acetylcholinesterase and DNA damage in both species tissues were monitored over 21 days. The results showed that both antioxidant enzymes concentration (SOD and CAT) increased in the lowest DHO concentrations (5.8, and 8.7 ml L -1 ), and then decreased in the highest concentration (17.4 ml L -1 ) as the same pattern for Unio tigridis, but this not occurred for Viviparous bengalensis. MDA values recorded significantly increased compared to control. No reduction was observed in AChE concentrations in soft tissues of both mollusks may due to that DHO was a non-neurotoxicant to Unio tigridis and Viviparous bengalensis. The results of DNA damage parameters were showed significant differences (p≤ 0.05) between control and DHO concentrations except lowest concentration for each parameter measured in digestive gland of Unio tigridis. As well as, these significant differences were recorded between control and three concentrations of DHO exposure for comet length, and tail length parameters, and between control and highest oil concentration for tail moment in Viviparous bengalensis. DHO has the ability to prevent the reproduction of Viviparous bengalensis snail relation to control, that is what we considered strong evidence of the toxicity properties of DHO on the reproductive status of this species of snails. SOD, CAT, and MDA were useful biomarkers for evaluating the toxicity of DHO in mussel and snails, and comet assay was a good tool to assess the potential genotoxicity of DHO. Copyright © 2018 Elsevier Inc. All rights reserved.

Forecast for the Remainder of the Leonid Storm Season

NASA Technical Reports Server (NTRS)

Jenniskens, Peter; DeVincenzi, Donald L. (Technical Monitor)

2001-01-01

The dust trails of comet 55P/Tempel-Tuttle lead to Leonid storms on Earth, threatening satellites in orbit. We present a new model that accounts in detail for the observed properties of dust tails evolved by the comet at previous oppositions. The prediction model shows the 1767-dust trail closer to Earth's orbit in 2001 than originally thought; increasing expected peak rates for North America observers. Predictions for the 2002 storms are less affected. We demonstrate that the observed shower profiles can be understood as a projection of the comet lightcurve.

The International Cometary Explorer (ICE)wallsheet teacher's guide

NASA Technical Reports Server (NTRS)

Maran, S. P. (Editor)

1985-01-01

On September 11, 1985, the veteran NASA spacecraft ISEE-3 which has been renamed the International Cometary Explorer (ICE) will make the first visit of a spacecraft to a comet. A teachers' guide to the NASA wallsheet on the ICE and its mission is presented. This circumstance of course results from the current interest in the return of Halley's Comet. This teacher's guide will be helpful in understanding scientists strong interest in sending the ICE spacecraft to investigate the tail of a much less famous object Comet Giacobin-Zinner.

An early look of comet C/2013 A1 (Siding Spring): Breathtaker or nightmare?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ye, Quan-Zhi; Hui, Man-To, E-mail: qye22@uwo.ca

The dynamically new comet, C/2013 A1 (Siding Spring), is to make a close approach to Mars on 2014 October 19 at 18:30 UT at a distance of 40 ± 1 Martian radii. Such an extremely rare event offers a precious opportunity for the spacecrafts on Mars to closely study a dynamically new comet itself as well as the planet-comet interaction. Meanwhile, the high-speed meteoroids released from C/Siding Spring also pose a threat to physically damage the spacecrafts. Here we present our observations and modeling results of C/Siding Spring to characterize the comet and assess the risk posed to the spacecraftsmore » on Mars. We find that the optical tail of C/Siding Spring is dominated by larger particles at the time of the observation. Synchrone simulation suggests that the comet was already active in late 2012 when it was more than 7 AU from the Sun. By parameterizing the dust activity with a semi-analytic model, we find that the ejection speed of C/Siding Spring is comparable to comets such as the target of the Rosetta mission, 67P/Churyumov-Gerasimenko. Under a nominal situation, the simulated dust cone will miss the planet by about 20 Martian radii. At the extreme ends of uncertainties, the simulated dust cone will engulf Mars, but the meteoric influx at Mars is still comparable to the nominal sporadic influx, seemly indicating that an intense and enduring meteoroid bombardment due to C/Siding Spring is unlikely. Further simulation also suggests that gravitational disruption of the dust tail may be significant enough to be observable at Earth.« less

The solar wind structure that caused a large-scale disturbance of the plasma tail of comet Austin

NASA Technical Reports Server (NTRS)

Kozuka, Yukio; Konno, Ichishiro; Saito, Takao; Numazawa, Shigemi

1992-01-01

The plasma tail of Comet Austin (1989c1) showed remarkable disturbances because of the solar maximum periods and its orbit. Figure 1 shows photographs of Comet Austin taken in Shibata, Japan, on 29 Apr. 1990 UT, during about 20 minutes with the exposure times of 90 to 120 s. There are two main features in the disturbance; one is many bowed structures, which seem to move tailwards; and the other is a large-scale wavy structure. The bowed structures can be interpreted as arcade structures brushing the surface of both sides of the cometary plasma surrounding the nucleus. We identified thirteen structures of the arcades from each of the five photographs and calculated the relation between the distance of each structure from the cometary nucleus, chi, and the velocity, upsilon. The result is shown. This indicates that the velocity of the structures increases with distance. This is consistent with the result obtained from the observation at the Kiso Observatory.

The earliest drawings of datable auroras and a two-tail comet from the Syriac Chronicle of Zūqnīn

NASA Astrophysics Data System (ADS)

Hayakawa, Hisashi; Mitsuma, Yasuyuki; Fujiwara, Yasunori; Kawamura, Akito Davis; Kataoka, Ryuho; Ebihara, Yusuke; Kosaka, Shunsuke; Iwahashi, Kiyomi; Tamazawa, Harufumi; Isobe, Hiroaki

2017-04-01

People have probably been watching the sky since the beginning of human history. Observers in pre-telescopic ages recorded anomalous events, which now provide uniquely valuable information for modern scientists. Records that include drawings are particularly useful, since the verbal expressions recorded by pre-telescopic observers, who did not know the physical nature of the phenomena, are often ambiguous. However, drawings concerning specific datable events in the historical documents are far fewer than the verbal records. Therefore, in this paper we show the possible earliest drawings of datable auroras and a two-tail comet included in a manuscript of the Chronicle of Zūqnīn, a Syriac chronicle up to 775/776 CE, to interpret their nature. Careful perusing the original Syriac autograph manuscript, MS Vat.Sir.162, provide not only historical facts in the realm around Amida, but also information concerning low-latitude aurora observations due to extreme space weather events and the existence of sun-grazing comets.

Plasma-tail activity and the interplanetary medium at Halley's Comet during Armada Week: 6-14 March 1986

NASA Technical Reports Server (NTRS)

Niedner, Malcolm B., Jr.; Schwingenschuh, Konrad; Hoeksema, J. Todd; Dryer, Murray; Mcintosh, Patrick S.

1987-01-01

The encounters of five spacecraft with Halley's Comet during 6-14 March 1986 offered a unique opportunity to calibrate the solar-wind interaction with cometary plasmas as recorded by remote wide-field and narrow-field/narrowband imaging. Perhaps not generally recognized in the comet community is the additional opportunity offered by the Halley Armada to study the structure of the solar-wind and interplanetary magnetic field (IMF) in three dimensions using five sets of data obtained over similar time intervals and heliocentric distances, but at somewhat different heliolatitudes. In fact, the two problems, i.e., comet physics and the structure of the interplanetary medium, are coupled if one wants to understand what conditions pertained at the comet between the encounters. This relationship is discussed.

Use of sensitive methods for detection of DNA damage on human lymphocytes exposed to p,p'-DDT: Comet assay and new criteria for scoring micronucleus test.

PubMed

Gajski, Goran; Ravlic, Sanda; Capuder, Zeljka; Garaj-Vrhovac, Vera

2007-08-01

Wide distribution, stability and long persistence in the environment of dichlorodiphenyltrichloroethane (DDT), probably the best-known and most useful insecticide in the world, imposes the need for further examination of the effect of this chemical on human health and especially on the human genome. In this study, peripheral blood human lymphocytes from a healthy donor were exposed to 0.025 mg/L concentration of p,p'-DDT at different time periods (1, 2, 24 and 48 h). For the assessment of genotoxic effect, the new criteria for scoring micronucleus test and alkaline comet assay were used. Both methods showed that p,p'-DDT induces DNA damage in low concentration used in this research. Results of micronucleus test showed a statistically significant (p < 0.05) genotoxic effect of p,p'-DDT on human lymphocytes compared with corresponding control and a different exposure time. A comet assay also showed increased DNA damage caused in p,p'-DDT-exposed human lymphocytes than in corresponding control cells for the tail length. Results obtained by measuring the level of DNA migration and incidence of micronuclei (MN), nucleoplasmic bridges (NPBs) and nuclear buds (NBUDs) indicate the sensitivity of these tests and their application in detection of primary genome damage after long-term exposure to establish the effect of p,p'-DDT on human genome.

Evaluation of impairment of DNA in marine gastropod, Morula granulata as a biomarker of marine pollution.

PubMed

Sarkar, A; Bhagat, Jacky; Sarker, Subhodeep

2014-08-01

The impairment of DNA in marine gastropod Morula granulata was evaluated in terms of the loss of DNA integrity in the species as a measure of the impact of genotoxic contaminants prevalent in the marine environment along the coast of Goa, India. The extent of DNA damage occurred in the marine gastropods collected from different sampling sites such as Arambol, Anjuna, Sinquerim, Dona Paula, Bogmalo, Hollant, Velsao, Betul and Palolem along the coast of Goa was measured following the technique of partial alkaline unwinding as well as comet assays. The highest DNA integrity was observed at Arambol (F, 0.75), identified as the reference site, whereas the lowest DNA integrity at Hollant (F, 0.33) situated between the two most contaminated sites at Bogmalo and Velsao. The impact of genotoxic contaminants on marine gastropods was pronounced by their low DNA integrity at Sinquerim (F, 0.40) followed by Betul (F, 0.47), Velsao (F, 0.51), Anjuna (F, 0.54), Bogmalo (F, 0.55), Dona Paula (F, 0.67) and Palolem (F, 0.70). The extent of DNA damage occurred in M. granulata due to ecotoxicological impact of the prevailing marine pollutants along the coast of Goa was further substantiated by comet assay and expressed in terms of %head-DNA, %tail DNA, tail length and Olive tail moment. The single cell gel electrophoresis of M. granulata clearly showed relatively higher olive tail moment in the marine gastropod from the contaminated sites, Anjuna, Hollant, Velsao and Betul. The variation in the mean %head DNA at different sampling sites clearly indicated that the extent of DNA damage in marine gastropod increases with the increase in the levels of contamination at different sampling sites along the coast. The stepwise multiple regression analysis of the water quality parameters showed significant correlation between the variation in DNA integrity and PAH in combination with NO3, salinity and PO4 (R¯(2), 0.90). The measurement of DNA integrity in M. granulata thus provides an early warning signal of contamination of the coastal ecosystem of Goa by genotoxic contaminants. Copyright © 2014 Elsevier Inc. All rights reserved.

Effects of curcumin on antioxidative activities and cytokine production in Jian carp (Cyprinus carpio var. Jian) with CCl4-induced liver damage.

PubMed

Cao, Liping; Ding, Weidong; Du, Jingliang; Jia, Rui; Liu, Yingjuan; Zhao, Caiyuan; Shen, Yujin; Yin, Guojun

2015-03-01

We investigated the protective effects of curcumin on liver-damaged Cyprinus carpio var. Jian (Jian carp). The carp were fed 0.1%, 0.5%, or 1.0% curcumin for 60 days, then injected intraperitoneally with 30% carbon tetrachloride solution. Liver and blood samples were collected to measure the liver index, serum- and liver-associated enzymes, liver histology, nuclear factor-κB (NF-κB)/c-Rel, interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and IL-12 mRNA expression, and the level of NF-κB/c-Rel protein in the liver, and for a comet assay. We found that 0.5% and 1.0% curcumin significantly reduced the CCl(4)-induced increase in the liver index. The comet assay showed that the tail moment, olive tail moment, tail length, and tail DNA% improved in fish pretreated with 0.5 or 1.0% curcumin. CCl(4)-induced histological changes, including extensive hepatocyte degeneration, indistinct cell borders, nuclear condensation, and karyolysis were clearly reduced after treatment with 0.5% and 1.0% curcumin. Moreover, 0.5% and 1.0% curcumin significantly inhibited the CCl(4)-induced increase in serum glutamic oxaloacetic transaminase and promoted the restoration of superoxide dismutase in the liver; 1.0% curcumin significantly reduced serum glutamic pyruvic transaminase and lactate dehydrogenase and hepatic malondialdehyde, but significantly increased the total antioxidant capacity and glutathione levels in the liver. The CCl(4)-induced upregulation of NF-κB/c-Rel, IL-1β, and TNF-α mRNAs and NF-κB/c-Rel protein levels was inhibited by 0.5% and 1.0% curcumin, and IL-12 mRNA was reduced by all three doses of curcumin. The effects of curcumin on the liver index, enzymes, histological changes, and cytokines were dose-dependent. Our results indicate that curcumin reduces CCl(4)-induced liver damage in Jian carp by upregulating antioxidative activities and inhibiting NF-κB, IL-1β, TNF-α, and IL-12 expression. Copyright © 2014 Elsevier Ltd. All rights reserved.

Comet-toolbox: Numerical simulations of cometary dust tails in your browser

NASA Astrophysics Data System (ADS)

Vincent, J.

2014-07-01

The last few years have seen a rise in the popularity of comets, on both professional and amateur levels. Many cometary events, sometimes visible without a telescope, have triggered worldwide campaigns of ground- and space-based observations: for instance, the explosion of comet 17P/Holmes, the sungrazers C/2006 P1 (McNaught) and C/2012 S1 (ISON), or the forthcoming close encounter of C/2013 A1 (Siding Springs) and Mars. With the overwhelming amount of data available, it becomes more and more important to release the models we use to analyze these events. This ensures not only that more people get the opportunity to investigate the data, but is also beneficial for the science itself as everybody is able to see, use, and improve the models. As a professional planetary scientist, I have written many tools to process the data I use, especially in the field of cometary and asteroid science [1-6]. With the progress of modern computers, it is now possible to translate these tools to simple HTML/Javascript interfaces and run the models in an Internet browser. I have decided to make my tools available in this way, to be used by anybody interested in modeling cometary processes. The first tool being released at ACM 2014 is the Finson-Probstein diagram. The motion of dust particles in a cometary environment is a complex process. A precise description of the grain trajectories requires advanced hydrodynamic models. In the tail, dust and gas are decoupled and the only significant forces affecting the grain trajectories are the solar gravity and radiation pressure. Both forces depend on the square of the heliocentric distance but work in opposite directions. Their sum can be seen as a reduced solar gravity, and the equation of motion is simply m × a = (1-β) × Sun_{gravity}, where β is the ratio P_{radiation}/Sun_{gravity}, and is inversely proportional to the size of the grains for particles larger than 1 micron. From this relation, Finson & Probstein (1968, [7]) proposed a model which describes the full tail geometry with a grid of synchrones and syndynes, i.e., lines representing, respectively, the locations of particles released at the same time or with the same β. This model is simple because it considers only particles released in the orbital plane of the comet, and with zero initial velocity, but it provides a very good approximation of the shape of the tail, and has been used successfully to study many comets. One of the many strengths of this approach is the possibility to date events in the tail. For instance, one can understand if regions of higher density are related to outbursts of the nucleus, or are a result of fragmentation of large chunks of material within the trail. It can also be used to disentangle between continuous activity, short outbursts, or impacts, when all these events produce a feature which at first look like a normal cometary tail. The model can be found at http://www.comet-toolbox.com.

Oct. 9 Hubble View of ISON

NASA Image and Video Library

2013-11-22

On Oct. 9, 2013, Hubble observed comet ISON once again, when it was inside the orbit of Mars, about 177 million miles from Earth. This image shows that the comet was still intact despite some predictions that the fragile icy nucleus might disintegrate closer to the sun. The comet will pass closest to the sun on Nov. 28, 2013. If the nucleus had broke apart then Hubble would have likely seen evidence of multiple fragments. Moreover, the coma, or head, surrounding the comet's nucleus is symmetric and smooth. This would probably not be the case if clusters of smaller fragments were flying along. This color composite image was assembled using two filters. The comet's coma appears cyan, a greenish-blue color due to gas, while the tail is reddish due to dust streaming off the nucleus. The tail forms as dust particles are pushed away from the nucleus by the pressure of sunlight. Credit: NASA -------- More details on Comet ISON: Comet ISON began its trip from the Oort cloud region of our solar system and is now travelling toward the sun. The comet will reach its closest approach to the sun on Thanksgiving Day -- 28 Nov 2013 -- skimming just 730,000 miles above the sun's surface. If it comes around the sun without breaking up, the comet will be visible in the Northern Hemisphere with the naked eye, and from what we see now, ISON is predicted to be a particularly bright and beautiful comet. Catalogued as C/2012 S1, Comet ISON was first spotted 585 million miles away in September 2012. This is ISON's very first trip around the sun, which means it is still made of pristine matter from the earliest days of the solar system’s formation, its top layers never having been lost by a trip near the sun. Comet ISON is, like all comets, a dirty snowball made up of dust and frozen gases like water, ammonia, methane and carbon dioxide -- some of the fundamental building blocks that scientists believe led to the formation of the planets 4.5 billion years ago. NASA has been using a vast fleet of spacecraft, instruments, and space- and Earth-based telescope, in order to learn more about this time capsule from when the solar system first formed. The journey along the way for such a sun-grazing comet can be dangerous. A giant ejection of solar material from the sun could rip its tail off. Before it reaches Mars -- at some 230 million miles away from the sun -- the radiation of the sun begins to boil its water, the first step toward breaking apart. And, if it survives all this, the intense radiation and pressure as it flies near the surface of the sun could destroy it altogether. This collection of images show ISON throughout that journey, as scientists watched to see whether the comet would break up or remain intact. The comet reaches its closest approach to the sun on Thanksgiving Day -- Nov. 28, 2013 -- skimming just 730,000 miles above the sun’s surface. If it comes around the sun without breaking up, the comet will be visible in the Northern Hemisphere with the naked eye, and from what we see now, ISON is predicted to be a particularly bright and beautiful comet. ISON stands for International Scientific Optical Network, a group of observatories in ten countries who have organized to detect, monitor, and track objects in space. ISON is managed by the Keldysh Institute of Applied Mathematics, part of the Russian Academy of Sciences. NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Protective effects of folic acid on DNA damage and DNA methylation levels induced by N-methyl- N'-nitro- N-nitrosoguanidine in Kazakh esophageal epithelial cells.

PubMed

Chen, Y; Feng, H; Chen, D; Abuduwaili, K; Li, X; Zhang, H

2018-01-01

The protective effects of folic acid on DNA damage and DNA methylation induced by N-methyl- N'-nitro- N-nitrosoguanidine (MNNG) in Kazakh esophageal epithelial cells were investigated using a 3 × 3 factorial design trial. The cells were cultured in vitro and exposed to media containing different concentrations of folic acid and MNNG, after which growth indices were detected. DNA damage levels were measured using comet assays, and genome-wide DNA methylation levels (MLs) were measured using high-performance liquid chromatography. The DNA methylation of methylenetetrahydrofolate reductase (MTHFR) and folate receptor- α (FR α) genes was detected by bisulfite sequencing polymerase chain reaction (PCR). The results showed significant increases in tail DNA concentration, tail length, and Olive tail moment ( p < 0.01); a significant reduction of genome-wide DNA MLs ( p < 0.01); and an increase in the methylation frequencies of MTHFR and FR α genes. In particular, significant differences were observed in the promoter regions of both genes ( p < 0.01). Our study indicated that a reduction in folic acid concentration promotes DNA damage and DNA methylation in Kazakh esophageal epithelial cells upon MNNG exposure. Thus, sufficient folic acid levels could play a protective role against the damage induced by this compound.

Study of a comet rendezvous mission, volume 1

NASA Technical Reports Server (NTRS)

1972-01-01

The feasibility, scientific objectives, modes of exploration and implementation alternatives of a rendezvous mission to Encke's comet in 1984 are considered. Principal emphasis is placed on developing the scientific rationale for such a mission, based on available knowledge and best estimates of this comet's physical characteristics, including current theories of its origin, evolution and composition. Studied are mission profile alternatives, performance tradeoffs, preferred exploration strategy, and a spacecraft design concept capable of performing this mission. The study showed that the major scientific objectives can be met by a Titan IIID/Centaur-launched 17.5 kw solar electric propulsion spacecraft which carries 60 kg of scientific instruments and is capable of extensive maneuvering within the comet envelope to explore the coma, tail and nucleus.

Induction and repair of DNA cross-links induced by sulfur mustard in the A-549 cell line followed by a comet assay.

PubMed

Jost, Petr; Svobodova, Hana; Stetina, Rudolf

2015-07-25

Sulfur mustard is a highly toxic chemical warfare agent with devastating impact on intoxicated tissues. DNA cross-links are probably the most toxic DNA lesions induced in the cell by sulfur mustard. The comet assay is a very sensitive method for measuring DNA damage. In the present study using the A-549 lung cell line, the comet assay protocol was optimized for indirect detection of DNA cross-links induced by sulfur mustard. The method is based on the additional treatment of the assayed cells containing cross-links with the chemical mutagen, styrene oxide. Alkali-labile adducts of styrene oxide cause DNA breaks leading to the formation of comets. A significant dose-dependent reduction of DNA migration of the comet's tail was found after exposing cells to sulfur mustard, indicative of the amount of sulfur mustard induced cross-links. The remarkable decrease of % tail DNA could be observed as early as 5min following exposure to sulfur mustard and the maximal effect was found after 30min, when DNA migration was reduced to the minimum. Sulfur mustard preincubated in culture medium without cells lost its ability to induce cross-links and had a half-life of about 15min. Pre-incubation longer than 30min does not lead to a significant increase in cross-links when applied to cells. However, the amount of cross-links is decreased during further incubation due to repair. The current modification of the comet assay provides a useful tool for detecting DNA cross-links induced by sulfur mustard and could be used for detection of other DNA cross-linking agents such as chemotherapeutic drugs. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Plasma-tail activity at the time of the Vega encounters

NASA Technical Reports Server (NTRS)

Niedner, Malcolm B., Jr.; Schwingensuch, Konrad

1986-01-01

Physical associations are sought between Halley's plasma tail activity seen in ground-based imagery and near-comet, solar wind/IMF measurements obtained by the Vega spacecraft. Disconnection Events (DE's) and the sector boundary/frontside magnetic reconnection model (Niedner and Brandt, 1978) of their origin are discussed. Strong support for the model comes from 2 DE's: a major event whose onset, on March 7 to 8, is strongly correlated with a reversal of the comet's magnetic barrier observed by Vega-1 and Vega-2 and with an IMF sector boundary observed by Vega-1; and a minor event on March 7 which may be associated with the two-polarity (possibly reconnecting) magnetic barrier seen by Vega-1 on March 6, when the solar-wind density was low.

An Early Investigation Of The Striated Tail Of Comet Hale-Bopp (C/1995 O1)

NASA Astrophysics Data System (ADS)

Pittichová, J.; Sekanina, Z.; Birkle, K.; Boehnhardt, H.; Engels, D.; Keller, P.

1997-07-01

The Sekanina-Farrell particle fragmentation model for the striated tails of dust comets is successfully applied to two images of comet Hale-Bopp to study the motions of 12 striae in a time span of March 12 15, 1997. There is evidence for recurring outbursts with a periodicity of 11h21m, consistent with results based on analysis of dust jets. The ejecta in all the striae appear to have been released from one source on the nucleus between the end of January and the second half of February 1997, some 60 to 40 days before perihelion. The parent particles were subjected to a radiation pressure acceleration of βp ≃ 0.55 and their fragmentation lifetimes in 11 of the 12 striae were practically constant and equal to 13 15 days, when normalized to 1 AU from the Sun. Brief analysis of Watanabe et al.'s measurements of striae on their images from March 5 9, 1997 shows even shorter fragmentation lifetimes for the parent particles, mostly about 7 11 days at1 AU.

Edaravone protects human peripheral blood lymphocytes from γ-irradiation-induced apoptosis and DNA damage.

PubMed

Chen, Liming; Liu, Yinghui; Dong, Liangliang; Chu, Xiaoxia

2015-03-01

Radiation-induced cellular injury is attributed primarily to the harmful effects of free radicals, which play a key role in irradiation-induced apoptosis. In this study, we investigated the radioprotective efficacy of edaravone, a licensed clinical drug and a powerful free radical scavenger that has been tested against γ-irradiation-induced cellular damage in cultured human peripheral blood lymphocytes in studies of various diseases. Edaravone was pre-incubated with lymphocytes for 2 h prior to γ-irradiation. It was found that pretreatment with edaravone increased cell viability and inhibited generation of γ-radiation-induced reactive oxygen species (ROS) in lymphocytes exposed to 3 Gy γ-radiation. In addition, γ-radiation decreased antioxidant enzymatic activity, such as superoxide dismutase and glutathione peroxidase, as well as the level of reduced glutathione. Conversely, treatment with 100 μM edaravone prior to irradiation improved antioxidant enzyme activity and increased reduced glutathione levels in irradiated lymphocytes. Importantly, we also report that edaravone reduced γ-irradiation-induced apoptosis through downregulation of Bax, upregulation of Bcl-2, and consequent reduction of the Bax:Bcl-2 ratio. The current study shows edaravone to be an effective radioprotector against γ-irradiation-induced cellular damage in lymphocytes in vitro. Finally, edaravone pretreatment significantly reduced DNA damage in γ-irradiated lymphocytes, as measured by comet assay (% tail DNA, tail length, tail moment, and olive tail moment) (p < 0.05). Thus, the current study indicates that edaravone offers protection from radiation-induced cytogenetic alterations.

Protection of cadmium chloride induced DNA damage by Lamiaceae plants

PubMed Central

Thirugnanasampandan, Ramaraj; Jayakumar, Rajarajeswaran

2011-01-01

Objective To analyze the total phenolic content, DNA protecting and radical scavenging activity of ethanolic leaf extracts of three Lamiaceae plants, i.e. Anisomelos malabarica (A. malabarica), Leucas aspera (L. aspera) and Ocimum basilicum (O. basilicum). Methods The total polyphenols and flavonoids were analyzed in the ethanolic leaf extracts of the lamiaceae plants. To determine the DNA protecting activity, various concentrations of the plant extracts were prepared and treated on cultured HepG2 human lung cancer cells. The pretreated cells were exposed to H2O2 to induce DNA damage through oxidative stress. Comet assay was done and the tail length of individual comets was measured. Nitric oxide and superoxide anion scavenging activities of lamiaceae plants were analyzed. Results Among the three plant extracts, the highest amount of total phenolic content was found in O. basilicum (189.33 mg/g), whereas A. malabarica showed high levels of flavonoids (10.66 mg/g). O. basilicum also showed high levels of DNA protecting (85%) and radical scavenging activity. Conclusions The results of this study shows that bioactive phenols present in lamiaceae plants may prevent carcinogenesis through scavenging free radicals and inhibiting DNA damage. PMID:23569799

Electronic cigarettes induce DNA strand breaks and cell death independently of nicotine in cell lines.

PubMed

Yu, Vicky; Rahimy, Mehran; Korrapati, Avinaash; Xuan, Yinan; Zou, Angela E; Krishnan, Aswini R; Tsui, Tzuhan; Aguilera, Joseph A; Advani, Sunil; Crotty Alexander, Laura E; Brumund, Kevin T; Wang-Rodriguez, Jessica; Ongkeko, Weg M

2016-01-01

Evaluate the cytotoxicity and genotoxicity of short- and long-term e-cigarette vapor exposure on a panel of normal epithelial and head and neck squamous cell carcinoma (HNSCC) cell lines. HaCaT, UMSCC10B, and HN30 were treated with nicotine-containing and nicotine-free vapor extract from two popular e-cigarette brands for periods ranging from 48 h to 8 weeks. Cytotoxicity was assessed using Annexin V flow cytometric analysis, trypan blue exclusion, and clonogenic assays. Genotoxicity in the form of DNA strand breaks was quantified using the neutral comet assay and γ-H2AX immunostaining. E-cigarette-exposed cells showed significantly reduced cell viability and clonogenic survival, along with increased rates of apoptosis and necrosis, regardless of e-cigarette vapor nicotine content. They also exhibited significantly increased comet tail length and accumulation of γ-H2AX foci, demonstrating increased DNA strand breaks. E-cigarette vapor, both with and without nicotine, is cytotoxic to epithelial cell lines and is a DNA strand break-inducing agent. Further assessment of the potential carcinogenic effects of e-cigarette vapor is urgently needed. Copyright © 2015 Elsevier Ltd. All rights reserved.

Electronic cigarettes induce DNA strand breaks and cell death independently of nicotine in cell lines

PubMed Central

Yu, Vicky; Rahimy, Mehran; Korrapati, Avinaash; Xuan, Yinan; Zou, Angela E.; Krishnan, Aswini R.; Tsui, Tzuhan; Aguilera, Joseph A.; Advani, Sunil; Crotty Alexander, Laura E.; Brumund, Kevin T.; Wang-Rodriguez, Jessica

2016-01-01

Objectives Evaluate the cytotoxicity and genotoxicity of short- and long-term e-cigarette vapor exposure on a panel of normal epithelial and head and neck squamous cell carcinoma (HNSCC) cell lines. Materials and Methods HaCaT, UMSCC10B, and HN30 were treated with nicotine-containing and nicotine-free vapor extract from two popular e-cigarette brands for periods ranging from 48 hours to 8 weeks. Cytotoxicity was assessed using Annexin V flow cytometric analysis, trypan blue exclusion, and clonogenic assays. Genotoxicity in the form of DNA strand breaks was quantified using the neutral comet assay and γ-H2AX immunostaining. Results E-cigarette-exposed cells showed significantly reduced cell viability and clonogenic survival, along with increased rates of apoptosis and necrosis, regardless of e-cigarette vapor nicotine content. They also exhibited significantly increased comet tail length and accumulation of γ-H2AX foci, demonstrating increased DNA strand breaks. Conclusion E-cigarette vapor, both with and without nicotine, is cytotoxic to epithelial cell lines and is a DNA strand break-inducing agent. Further assessment of the potential carcinogenic effects of e-cigarette vapor is urgently needed. PMID:26547127

Rosetta - ESA's new comet chaser

NASA Astrophysics Data System (ADS)

1999-06-01

The Rosetta orbiter will literally chase comet Wirtanen for two years, sending back valuable data and ensuring Europe retains its lead in comet science. A lander will attach itself to this lump of frozen ice and dust, which is travelling through space at over 130,000 kilometres per hour, and analyse samples. Just as the re-discovery of the Rosetta Stone, 200 years ago, enabled the mysteries of ancient Egyptian hieroglyphics to be unrravelled, so the Rosetta mission will help scientists learn even more about comets, the most primitive objects in the solar system. In 1986, ESA's Giotto spacecraft flew into the tail of Halley's Comet. That was ESA's first interplanetary mission and it was hailed as an outstanding success. The pictures and scientific data that Giotto sent back placed Europe at the forefront of comet science. Notes for Editors : On the day of the press event, the now deactivated Giotto spacecraft will do an Earth flyby 13 years after its encounter with Halley's Comet. The British Museum is celebrating 200-years anniversary of the Rosetta Stone, with an exhibition that includes a model of its modern equivalent, the Rosetta spacecraft.

Alkaline comet assay in liver and stomach, and micronucleus assay in bone marrow, from rats treated with 2-acetylaminofluorene, azidothymidine, cisplatin, or isobutyraldehyde.

PubMed

Kraynak, A R; Barnum, J E; Cunningham, C L; Ng, A; Ykoruk, B A; Bennet, B; Stoffregen, D; Merschman, M; Freeland, E; Galloway, S M

2015-07-01

As part of the Japanese Center for the Validation of Alternative Methods (JaCVAM) initiative international validation study of the in vivo rat alkaline comet assay (comet assay), we examined the ability of the assay to determine the genotoxicity of 2-acetylaminofluorene (AAF), azidothymidine (AZT), cisplatin (CPN), and isobutyraldehyde (IBA) in liver and glandular stomach of male Sprague-Dawley rats. Rats were given oral doses of test compound or control once daily for three days. High dose levels were approximately maximum tolerated doses and were based on preliminary range-finding studies. Tissues were harvested 3h after the final dose (48h after the initial dose). A bone marrow micronucleus assay (MN) was also conducted on the rats treated with AZT, CPN, and IBA. Acute toxic effects of treatment were determined primarily through histomorphologic analysis of liver and stomach but also by body weight and serum liver enzyme changes. The comet assay was conducted on fresh tissue preparations but frozen samples from two studies were also assayed. Statistically significant dose-related differences in comet % DNA in tail were found in liver and stomach for the genotoxin AZT and in liver for the genotoxin CPN, but not in liver or stomach for the non-genotoxin IBA. Statistically significant differences in % DNA in tail were measured in liver for the low and mid dose of the genotoxin AAF, but not the high dose. The comet assays of frozen liver suspensions from CPN- and AAF-treated rats yielded comparable results to the assays of fresh preparations. There were no indications of significant toxicity induced by any treatment. The micronucleus assay was positive for CPN and AZT and negative for IBA. In conclusion, the in vivo comet assay is capable of detecting genotoxic effects of a variety of chemicals and may fill an important role in the genotoxicity test battery. Copyright © 2015 Elsevier B.V. All rights reserved.

Poly A tail length analysis of in vitro transcribed mRNA by LC-MS.

PubMed

Beverly, Michael; Hagen, Caitlin; Slack, Olga

2018-02-01

The 3'-polyadenosine (poly A) tail of in vitro transcribed (IVT) mRNA was studied using liquid chromatography coupled to mass spectrometry (LC-MS). Poly A tails were cleaved from the mRNA using ribonuclease T1 followed by isolation with dT magnetic beads. Extracted tails were then analyzed by LC-MS which provided tail length information at single-nucleotide resolution. A 2100-nt mRNA with plasmid-encoded poly A tail lengths of either 27, 64, 100, or 117 nucleotides was used for these studies as enzymatically added poly A tails showed significant length heterogeneity. The number of As observed in the tails closely matched Sanger sequencing results of the DNA template, and even minor plasmid populations with sequence variations were detected. When the plasmid sequence contained a discreet number of poly As in the tail, analysis revealed a distribution that included tails longer than the encoded tail lengths. These observations were consistent with transcriptional slippage of T7 RNAP taking place within a poly A sequence. The type of RNAP did not alter the observed tail distribution, and comparison of T3, T7, and SP6 showed all three RNAPs produced equivalent tail length distributions. The addition of a sequence at the 3' end of the poly A tail did, however, produce narrower tail length distributions which supports a previously described model of slippage where the 3' end can be locked in place by having a G or C after the poly nucleotide region. Graphical abstract Determination of mRNA poly A tail length using magnetic beads and LC-MS.

Vehicle and positive control values from the in vivo rodent comet assay and biomonitoring studies using human lymphocytes: historical database and influence of technical aspects.

PubMed

Pant, Kamala; Springer, S; Bruce, S; Lawlor, T; Hewitt, N; Aardema, M J

2014-10-01

There is increased interest in the in vivo comet assay in rodents as a follow-up approach for determining the biological relevance of chemicals that are genotoxic in in vitro assays. This is partly because, unlike other assays, DNA damage can be assessed in this assay in virtually any tissue. Since background levels of DNA damage can vary with the species, tissue, and cell processing method, a robust historical control database covering multiple tissues is essential. We describe extensive vehicle and positive control data for multiple tissues from rats and mice. In addition, we report historical data from control and genotoxin-treated human blood. Technical issues impacting comet results are described, including the method of cell preparation and freezing. Cell preparation by scraping (stomach and other GI tract organs) resulted in higher % tail DNA than mincing (liver, spleen, kidney etc) or direct collection (blood or bone marrow). Treatment with the positive control genotoxicant, ethyl methanesulfonate (EMS) in rats and methyl methanesulfonate in mice, resulted in statistically significant increases in % tail DNA. Background DNA damage was not markedly increased when cell suspensions were stored frozen prior to preparing slides, and the outcome of the assay was unchanged (EMS was always positive). In conclusion, historical data from our laboratory for the in vivo comet assay for multiple tissues from rats and mice, as well as human blood show very good reproducibility. These data and recommendations provided are aimed at contributing to the design and proper interpretation of results from comet assays. © 2014 Wiley Periodicals, Inc.

In vitro antioxidation activity and genoprotective effect of selected Chinese medicinal herbs.

PubMed

Szeto, Yim Tong; Wong, Shirley Ching Yee; Wong, Julia Wai Ming; Kalle, Wouter; Pak, Sok Cheon

2011-01-01

Some traditional Chinese medicinal seeds and fruits are well known for their antioxidant properties. This research aims to investigate whether Fructus Lycii, Fructus Schisandrae Chinensis, Fructus Ligustri Lucidi and Semen Cuscutae protect DNA from oxidant challenge by hydrogen peroxide (H(2)O(2)). The standard comet assay was used to assess the genoprotective effect of these medicinal herbs. Blood was taken from three healthy adults, aged from 36 to 42. Lymphocytes were isolated and treated with different concentrations of aqueous herbal extracts, while controls were treated with phosphate buffered saline. The lymphocytes were stressed with 50 μM H(2)O(2). Treated cells were embedded in agarose and layered on slides. These sandwiched lymphocytes were lysed and afterwards subjected to an electric field in an alkaline environment. Damaged DNA was pulled out from the nucleus towards the positive electrode as a comet tail; its density was related to the degree of DNA damage. Finally, the slides were stained with fluorescence dye and tails were visually scored for 100 cells. The experiment was repeated three times and DNA damage in treated cells was compared to the controls. There was no statistical difference in DNA damage among the herb treated cells and untreated cells in the comet assay. Our data demonstrated that the selected medicinal herbs did not show in vitro DNA protection in the comet assay against oxidant challenge.

A Million Comet Pieces

NASA Technical Reports Server (NTRS)

2006-01-01

[figure removed for brevity, see original site] A Million Comet Pieces (poster version)

This infrared image from NASA's Spitzer Space Telescope shows the broken Comet 73P/Schwassman-Wachmann 3 skimming along a trail of debris left during its multiple trips around the sun. The flame-like objects are the comet's fragments and their tails, while the dusty comet trail is the line bridging the fragments.

Comet 73P /Schwassman-Wachmann 3 began to splinter apart in 1995 during one of its voyages around the sweltering sun. Since then, the comet has continued to disintegrate into dozens of fragments, at least 36 of which can be seen here. Astronomers believe the icy comet cracked due the thermal stress from the sun.

The Spitzer image provides the best look yet at the trail of debris left in the comet's wake after its 1995 breakup. The observatory's infrared eyes were able to see the dusty comet bits and pieces, which are warmed by sunlight and glow at infrared wavelengths. This comet debris ranges in size from pebbles to large boulders. When Earth passes near this rocky trail every year, the comet rubble burns up in our atmosphere, lighting up the sky in meteor showers. In 2022, Earth is expected to cross close to the comet's trail, producing a noticeable meteor shower.

Astronomers are studying the Spitzer image for clues to the comet's composition and how it fell apart. Like NASA's Deep Impact experiment, in which a probe smashed into comet Tempel 1, the cracked Comet 73P/Schwassman-Wachmann 3 provides a perfect laboratory for studying the pristine interior of a comet.

This image was taken from May 4 to May 6 by Spitzer's multi-band imaging photometer, using its 24-micron wavelength channel.

Effect of different procedures of ejaculate collection, extenders and packages on DNA integrity of boar spermatozoa following freezing-thawing.

PubMed

Fraser, L; Strzezek, J

2007-06-01

Whole ejaculate or sperm-rich fraction, collected from four sexually mature boars, was frozen in an extender containing lactose-hen egg yolk with glycerol (lactose-HEY-G) or extender containing lactose, lyophilized lipoprotein fractions isolated from ostrich egg yolk and glycerol (lactose-LPFo-G), and Orvus Es Paste, respectively. The sperm samples were also frozen in a standard boar semen extender (Kortowo-3), without the addition of cryoprotective substances. Sperm DNA integrity was assessed using a modified neutral comet assay. Sperm characteristics such as motility, plasma membrane integrity (SYBR-14/PI), mitochondrial function (rhodamine 123) and acrosome integrity were monitored. Freezing-thawing caused a significant increase (P<0.05) in sperm DNA fragmentation, irrespective of the procedures of ejaculate collection and extender type. Sperm DNA fragmentation was significantly lower (P<0.05) in the whole ejaculate compared with the sperm-rich fraction, indicating that spermatozoa maintained in the whole seminal plasma prior to its removal for freezing-thawing procedure were less vulnerable to cryo-induced DNA fragmentation. Furthermore, spermatozoa frozen in lactose-HEY-G or lactose-LPFo-G extender exhibited lower (P<0.05) DNA fragmentation than those frozen in the absence of cryoprotective substances. The levels of sperm DNA damage, as expressed by comet tail length and tail moment values, were significantly higher (P<0.05) in sperm samples frozen in the absence of cryoprotective substances. The deterioration in post-thaw sperm DNA integrity was concurrent with reduced sperm characteristics. It can be suggested that evaluation of DNA integrity, coupled with different sperm characteristics such as motility, plasma membrane integrity and mitochondrial function, may aid in determining the quality of frozen-thawed boar semen.

DNA damage and oxidative stress induced by imidacloprid exposure in the earthworm Eisenia fetida.

PubMed

Wang, Juan; Wang, Jinhua; Wang, Guangchi; Zhu, Lusheng; Wang, Jun

2016-02-01

To investigate the soil ecological effect of imidacloprid, earthworm Eisenia fetida was exposed to various concentrations of imidacloprid (0.10, 0.50, and 1.00 mg kg(-1) soil) respectively after 7, 14, 21, and 28 d. The effect of imidacloprid on reactive oxygen species (ROS) generation, antioxidant enzymes activity [superoxide dismutase (SOD) and catalase (CAT), glutathione S-transferase enzyme (GST)], malondialdehyde (MDA) content and DNA damage of the E. fetida was investigated. Significant increase of the ROS level was observed. The SOD and GST activity were significantly induced at most exposure intervals. CAT activity was inhibited and reflected a dose-dependent relationship on days 7, 14 and 21. High MDA levels were observed and the olive tail moment (OTM) as well as the percentage of DNA in the comet tail (tail DNA%) in comet assay declined with increasing concentrations and exposure time after 7 d. Our results suggested that the sub-chronic exposure of imidacloprid caused DNA damage and lipid peroxidation (LPO) leading to antioxidant responses in earthworm E. fetida. Copyright © 2015 Elsevier Ltd. All rights reserved.

Magnetotails at unmagnetized bodies - Comparison of Comet Giacobini-Zinner and Venus

NASA Technical Reports Server (NTRS)

Mccomas, D. J.; Gosling, J. T.; Russell, C. T.; Slavin, J. A.

1987-01-01

It is found that the near ionopause environs play a crucial role in the tail formation process at both Venus and G-Z and that draping at the two very different sized bodies occurs on ionopause scale sizes. On the other hand, ion densities, downtail mass fluxes, tailward J x B forces, and lobe betas are factors of about 10,000, 50, 100, and 20 times greater in the G-Z tail than in Venus', while bulk flow speeds and ion temperatures are factors of about 15 and 240 times lower. These large quantitative differences in the properties within the two magnetotails are attributable to the significantly greater upstream mass loading of the solar wind by the extended neutral atmosphere at G-Z (comets in general) compared to the gravitationally bound atmosphere of Venus.

Up Close and Personal with Hartley 2

NASA Image and Video Library

2010-11-04

This image, one of the closest taken of comet Hartley 2 by NASA EPOXI mission, shows many features across the comet surface. The length of the comet is equal to the distance between the Capitol building and the Washington Monument in Washington.

Optical spectrophotometry of Comet P/Giacobini-Zinner and emission profiles of H2O+

NASA Technical Reports Server (NTRS)

Strauss, M. A.; Mccarthy, P. J.; Spinrad, H.

1986-01-01

Two-dimensional CCD spectrograms were obtained of Comet P/Giacobini-Zinner (1984e) on five occasions between July and October 1985. Spatial emission profiles of H2O+ were extracted at 6198 angstroms (the strongest ionic line in the visible spectrum). This emission line traces the extent of the ion, or plasma, tail. The spectrographic slit was placed approximately along the trajectory of the ICE spacecraft on September 11, 1985; the resulting H2O+ profile has a full-width-half-maximum of about 5700 km, about three times that of the plasma density profile measured by ICE, and has a full-width-zero-intensity of about 30,000 km, very similar to the ICE values. H2O production rates for the comet are derived and compared with those of Comet P/Halley (1982i).

Possible Disintegrating Planet Artist Concept

NASA Image and Video Library

2012-05-21

This artist concept depicts a comet-like tail of a possible disintegrating super Mercury-size planet candidate as it transits, or crosses, its parent star, named KIC 12557548. The results are based on data from NASA Kepler mission.

Study of Comets Composition and Structure

NASA Astrophysics Data System (ADS)

Khalaf, S. Z.; Selman, A. A.; Ali, H. S.

2008-12-01

The present paper focuses on the nature of the different interactions between cometary nucleus and tail with solar wind. The dynamics of the comet will impose many features that provide unique behavior of the comet when entering the solar system. These features are reviewed in this paper and few investigations are made. The calculations made in this work represent the analysis and interpretation of the different features of the comet, such as perihelion and eccentricity dependence on the gas production rate, and the dependence of the latter on the composition of the comet nucleus. The dependences of the heliocentric, bow shock, contact surface, and stand-off distances with gas production rate for many types of comets that cover linear and non-linear types are studied in this work. Important results are obtained which indicated the different physical interactions between cometary ions and solar wind. Furthermore, the important relation between mean molecular weight and gas production rate are analyzed and studied in this work and a conclusion is made that, as the gas production rate increases, the mean molecular weight will decrease exponentially. A detailed discussion for this unique relation is given.

The application of the comet assay to assess the genotoxicity of environmental pollutants in the nematode Caenorhabditis elegans.

PubMed

Imanikia, Soudabeh; Galea, Francesca; Nagy, Eszter; Phillips, David H; Stürzenbaum, Stephen R; Arlt, Volker M

2016-07-01

This study aimed to establish a protocol for cell dissociation from the nematode Caenorhabditis elegans (C. elegans) to assess the genotoxicity of the environmental pollutant benzo[a]pyrene (BaP) using the alkaline version of the single cell electrophoresis assay (comet assay). BaP genotoxicity was assessed in C. elegans (wild-type [WT]; N2, Bristol) after 48h exposure (0-40μM). Induction of comets by BaP was concentration-dependent up to 20μM; comet% tail DNA was ∼30% at 20μM BaP and ∼10% in controls. Similarly, BaP-induced DNA damage was evaluated in C. elegans mutant strains deficient in DNA repair. In xpa-1 and apn-1 mutants BaP-induced comet formation was diminished to WT background levels suggesting that the damage formed by BaP that is detected in the comet assay is not recognised in cells deficient in nucleotide and base excision repair, respectively. In summary, our study provides a protocol to evaluate DNA damage of environmental pollutants in whole nematodes using the comet assay. Copyright © 2016 The Author(s). Published by Elsevier B.V. All rights reserved.

Does a continuous solid nucleus exist in comets.

NASA Technical Reports Server (NTRS)

Lyttleton, R. A.

1972-01-01

The implication of actual cometary observations for the physical nature of comets is briefly reviewed, bringing out the complete conflict with observation of the ice-dust solid nucleus model put forward in recent years as representing the fundamental structure of comets. That under increasing solar heat the nucleus develops an expanding atmosphere is inconsistent with the well-established phenomenon that the coma contracts with decreasing distance from the sun. Several comets remaining always beyond Mars have nevertheless been strongly active and produced fine tails. That some comets show at times a star-like point of light is readily explicable on the dust-cloud structure and by no means establishes that a solid nucleus exists. With the nucleus-area corresponding not to a small solid mass but to an optical phenomenon, there would be no reason to expect that it would describe a precise dynamical orbit. On the hypothesis of a nucleus, it is necessary to postulate further some internal jet-propulsion mechanism to account for the orbital deviations.

Simulating the Solar Wind Interaction with Comet 67P/Churyumov-Gerasimenko: Latest Results

NASA Astrophysics Data System (ADS)

Deca, J.; Divin, A. V.; Henri, P.; Eriksson, A. I.; Markidis, S.; Olshevsky, V.; Goldstein, R.; Myllys, M. E.; Horanyi, M.

2017-12-01

First observed in 1969, comet 67P/Churyumov-Gerasimenko was escorted for almost two years along its 6.45-yr elliptical orbit by ESA's Rosetta orbiter spacecraft. When a comet is sufficiently close to the Sun, the sublimation of ice leads to an outgassing atmosphere and the formation of a coma, and a dust and plasma tail. Comets are critical to decipher the physics of gas release processes in space. The latter result in mass-loaded plasmas, which more than three decades after the Active Magnetospheric Particle Tracer Explorers (AMPTE) space release experiments are still not fully understood. Using a 3D fully kinetic approach, we study the solar wind interaction with comet 67P/Churyumov-Gerasimenko, focusing in particular on the ion-electron dynamics for various outgassing rates. A detailed kinetic treatment of the electron dynamics is critical to fully capture the complex physics of mass-loading plasmas and to describe the strongly inhomogeneous plasma dynamics observed by Rosetta, down to electron kinetic scales.

[Use of comet assay for the risk assessment of oil- and chemical-industry workers].

PubMed

Megyesi, János; Biró, Anna; Wigmond, László; Major, Jenő; Tompa, Anna

2014-11-23

The comet assay is a fluorescent microscopic method that is able to detect DNA strand-breaks even in non-proliferative cells in samples with low cell counts. The aim of the authors was to measure genotoxic DNA damage and assess oxidative DNA damage caused by occupational exposure in groups exposed to benzene, polycyclic aromatic carbohydrates and styrene at the workplace in order to clarify whether the comet assay can be used as an effect marker tool in genotoxicology monitoring. In addition to the basic steps of the comet assay, one sample was treated with formamido-pirimidine-DNA-glycolase restriction-enzyme that measures oxidative DNA damage. An increase was observed in tail moments in each group of untreated and Fpg-treated samples compared to the control. It can be concluded that occupational exposure can be detected with the method. The comet assay may prove to be an excellent effect marker and a supplementary technique for monitoring the presence or absence of genotoxic effects.

First application of comet assay in blood cells of Mediterranean loggerhead sea turtle (Caretta caretta).

PubMed

Caliani, Ilaria; Campani, Tommaso; Giannetti, Matteo; Marsili, Letizia; Casini, Silvia; Fossi, Maria Cristina

2014-05-01

The aim of this study was to validate the comet assay in erythrocytes of Caretta caretta, a species never investigated for genotoxicity. We studied 31 loggerhead sea turtles from three Italian marine rescue centres. Peripheral blood samples were collected from all the animals and the comet assay applied. All comet cells were analysed using two methods: visual scoring and computer image analysis. The % DNA in tail mean value ± SD and Damage Index were 21.56 ± 15.41 and 134.83 ± 94.12, respectively. A strong and statistically significant statistically correlation between the two analytical methods was observed (r = 0.95; p < 0.05). These results demonstrate that the comet assay is a useful method to detect the possible effects of genotoxic agents in loggerhead sea turtle and to increase the knowledge about the ecotoxicological health status of this threatened species. Copyright © 2013 Elsevier Ltd. All rights reserved.

A Starry Diamond in a Veil of Light: Artistic and Literary Suggestions of a Comet

NASA Astrophysics Data System (ADS)

Gasperini, A.; Galli, D.

2016-01-01

Donati's Comet, discovered in Florence on June 2, 1858, was one of the most spectacular astronomical events of the nineteenth century. It could be seen with the naked eye during September and October 1858, when it reached its highest splendour. The sight of the comet, with its bright nucleus and its long, curved tail, inspired paintings, watercolors, engravings, and sketches by artists such as William Dyce, Samuel Palmer, and William Turner of Oxford. Donati's Comet is mentioned in the works of several contemporary writers and poets (Hawthorne, Dickens, Hardy, and Verne), and in the diaries of explorers and travelers all around the world. Long-lasting traces of the impression left by Donati's Comet are found in many forms of popular art and literature (ladies' magazines, children's books, collection cards, and advertisements) until the beginning of the twentieth century. This paper focuses on a few examples of this fascination, emphasizing the connections among the astronomical event and the artistic sensibility of the period.

Comets in Indian Scriptures

NASA Astrophysics Data System (ADS)

Das Gupta, P.

2016-01-01

The Indo-Aryans of ancient India observed stars and constellations for ascertaining auspicious times in order to conduct sacrificial rites ordained by the Vedas. Naturally, they would have sighted comets and referred to them in the Vedic texts. In Rigveda (circa 1700-1500 BC) and Atharvaveda (circa 1150 BC), there are references to dhumaketus and ketus, which stand for comets in Sanskrit. Rigveda speaks of a fig tree whose aerial roots spread out in the sky (Parpola 2010). Had this imagery been inspired by the resemblance of a comet's tail with long and linear roots of a banyan tree (ficus benghalensis)? Varahamihira (AD 550) and Ballal Sena (circa AD 1100-1200) described a large number of comets recorded by ancient seers, such as Parashara, Vriddha Garga, Narada, and Garga, to name a few. In this article, we propose that an episode in Mahabharata in which a radiant king, Nahusha, who rules the heavens and later turns into a serpent after he kicked the seer Agastya (also the star Canopus), is a mythological retelling of a cometary event.

The generation of magnetic fields and electric currents in cometary plasma tails

NASA Technical Reports Server (NTRS)

Ip, W.-H.; Mendis, D. A.

1976-01-01

Due to the folding of the interplanetary magnetic field into the tail as a comet sweeps through the interplanetary medium, the magnetic field in the tail can be built up to the order of 100 gammas at a heliocentric distance of about 1 AU. This folding of magnetic flux tubes also results in a cross-tail electric current passing through a neutral sheet. When streams of enhanced plasma density merge with the main tail, cross-tail currents as large as 1 billion A may result. A condition could arise which causes a significant fraction of this current to be discharged through the inner coma, resulting in rapid ionization. The typical time scale for such outbursts of ionization is estimated to be of the order of 10,000 sec, which is in reasonable agreement with observation.

Curved tails in polymerization-based bacterial motility

NASA Astrophysics Data System (ADS)

Rutenberg, Andrew D.; Grant, Martin

2001-08-01

The curved actin ``comet-tail'' of the bacterium Listeria monocytogenes is a visually striking signature of actin polymerization-based motility. Similar actin tails are associated with Shigella flexneri, spotted-fever Rickettsiae, the Vaccinia virus, and vesicles and microspheres in related in vitro systems. We show that the torque required to produce the curvature in the tail can arise from randomly placed actin filaments pushing the bacterium or particle. We find that the curvature magnitude determines the number of actively pushing filaments, independent of viscosity and of the molecular details of force generation. The variation of the curvature with time can be used to infer the dynamics of actin filaments at the bacterial surface.

Velocity of Ejection of Meteor Particle from the Nucleus of Comets

NASA Astrophysics Data System (ADS)

Safarov, Abduljalol; Ibadinov, Khursand

2016-07-01

The time and velocity of dust particles of anomalous tail of comets was determine. Velocity ejection of dust particles from the nuclei of comets C/1851 U1, C/1877 G1, C/1921 E1, C/1925 V1, C/1962 C1, C/1969 T1, C/1975 V2, 2P/1924 and 26P/1927 F1 reaching up to 0.4 km/s can be attributed to the removal of large dust particles from the surface of the icy nucleus of comet sublimating molecules. In comets C/1823 Y1, C/1844 Y1, C/1882 R1, C/1883 D1, C/1888 R1, C/1892 E1, D/1894 F1, C/1910 A1, C/1921 E1, C/1922 U1, C/1930 D1, C/1930 O1, C/1931 P1, C/1932 M1, C/1935 A1, C/1954 O1, C/1961 O1, C/1963 A1, C/1968 H1, C/1973 E1, C/1980 P1, C/1984 N2, C/1987 P1, C/1995 O1, C/1999 H1, C/1999 T2, C/1999 S4, C/2002 T7, C/2004 F4, C/2004 Q2, 6P/1950, 7P/1869 G1, 7P/1933, 10P/1930, 19P/1918, 34P/1938 J1, 35P/1939, 67P/1982, 73P/1930 J1, 96P/1986 J1 and 109P/1862 O1 ejection velocity (up to a few km/s) of the particles of anomalous tail from the nuclei significantly exceed the thermal velocity of the molecules sublimating ice nuclei. Such velocity may be explained by the removal of particles from the surface of the nucleus after the collision of the comet nucleus with meteoroids

Outbursting comet P/2010 V1 (Ikeya-Murakami): A miniature comet Holmes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ishiguro, Masateru; Jewitt, David; Hanayama, Hidekazu

2014-05-20

The short-period comet P/2010 V1 (Ikeya-Murakami, hereafter {sup V}1{sup )} was discovered visually by two amateur astronomers. The appearance of the comet was peculiar, consisting of an envelope, a spherical coma near the nucleus and a tail extending in the anti-solar direction. We investigated the brightness and the morphological development of the comet by taking optical images with ground-based telescopes. Our observations show that V1 experienced a large-scale explosion between UT 2010 October 31 and November 3. The color of the comet was consistent with the Sun (g' – R {sub C} = 0.61 ± 0.20, R {sub C} –more » I {sub C} = 0.20 ± 0.20, and B – R {sub C} = 0.93 ± 0.25), suggesting that dust particles were responsible for the brightening. We used a dynamical model to understand the peculiar morphology, and found that the envelope consisted of small grains (0.3-1 μm) expanding at a maximum speed of 500 ± 40 m s{sup –1}, while the tail and coma were composed of a wider range of dust particle sizes (0.4-570 μm) and expansion speeds 7-390 m s{sup –1}. The total mass of ejecta is ∼5 × 10{sup 8} kg and kinetic energy ∼5 × 10{sup 12} J. These values are much smaller than in the historic outburst of 17P/Holmes in 2007, but the energy per unit mass (1 × 10{sup 4} J kg{sup –1}) is comparable. The energy per unit mass is about 10% of the energy released during the crystallization of amorphous water ice suggesting that crystallization of buried amorphous ice can supply the mass and energy of the outburst ejecta.« less

A common carcinogen benzo[a]pyrene causes p53 overexpression in mouse cervix via DNA damage.

PubMed

Gao, Meili; Li, Yongfei; Sun, Ying; Long, Jiangang; Kong, Yu; Yang, Shuiyun; Wang, Yili

2011-09-18

Benzo[a]pyrene (BaP) is cytotoxic and/or genotoxic to lung, stomach and skin tissue in the body. However, the effect of BaP on cervical tissue remains unclear. The present study detected DNA damage and the expression of the p53 gene in BaP-induced cervical tissue in female mice. Animals were intraperitoneally injected and orally gavaged with BaP at the doses of 2.5, 5, and 10mg/kg twice a week for 14 weeks. The single-cell gel electrophoresis (SCGE) assay was used to detect the DNA damage. Immunohistochemistry (IHC) and in situ hybridization (ISH) were used to detect the expression of p53 protein and p53 mRNA, respectively. The results showed that BaP induced a significant and dose-dependent increase of the number of cells with DNA damaged and the tail length as well as Comet tail moment in cervical tissue. The expression level of p53 protein and mRNA was increased. The results demonstrate that BaP may show toxic effect on the cervix by increasing DNA damage and the expression of the p53 gene. Copyright © 2011 Elsevier B.V. All rights reserved.

Impact of acid mine drainage on haematological, histopathological and genotoxic effects in golden mahaseer, Tor putitora.

PubMed

Shahi, Neetu; Sarma, Debaji; Pandey, Jyoti; Das, Partha; Sarma, Dandadhar; Mallik, Sumanta Kumar

2016-07-01

The present study was carried out to evaluate sub-lethal mechanism of acid mine drainage toxicity in fingerlings (9.5 ± 2.4 cm) of golden mahseer, Tor putitora. Exposed fingerlings showed significant reduction (P < 0.01) in blood erythrocytes, neutrophils, thrombocytes, lymphocytes and leukocytes in contrast to increase in number of immature circulating cells. Hyperplasia, degeneration of glomeruli, presence of inflammatory cells and increased number of melanomacrophage aggregates, vacuolization of cell cytoplasm, hepatocyte swelling were marked in kidney and liver of fish. Ladder in, an increment of 180-200 bp of hepatic and kidney DNA, by electrophoresis were consistent with DNA damage. 10 day exposure to acid mine drainage resulted in reduction of double stranded DNA to 46.0 and 48.0 in hepatocytes and kidney cells respectively. Significant increase (P < 0.01) in tail length and percent tail DNA was evident by comet assay. The results suggest that exposure to acid mine drainage might cause irreversible damage to immune cells, tissue and DNA of fish, and this model of DNA damage may contribute in identifying novel molecular mechanism of interest for bioremediation application.

Pharmaceutical wastewater being composite mixture of environmental pollutants may be associated with mutagenicity and genotoxicity.

PubMed

Sharif, Ali; Ashraf, Muhammad; Anjum, Aftab Ahmed; Javeed, Aqeel; Altaf, Imran; Akhtar, Muhammad Furqan; Abbas, Mateen; Akhtar, Bushra; Saleem, Ammara

2016-02-01

Pharmaceutical industries are amongst the foremost contributor to industrial waste. Ecological well-being is endangered owing to its facile discharge. In the present study, heavy metals and organic contaminants in waste water were characterized using atomic absorption spectrophotometer and GC-MS, respectively. Mutagenicity and genotoxic potential of pharmaceutical waste water were investigated through bacterial reverse mutation assay and in vitro comet assay, respectively. Ames test and comet assay of first sample were carried out at concentrations of 100, 50, 25, 12.5, 6.25 % v/v effluent with distilled water. Chromium (Cr), lead (Pb), arsenic (As), and cadmium (Cd) were found in high concentrations as compared to WHO- and EPA-recommended maximum limits. Arsenic was found to be the most abundant metal and its maximum concentration was 0.8 mg.L(-1). GC-MS revealed the presence of lignocaine, digitoxin, trimethoprim, caffeine, and vitamin E in waste water. Dose-dependent decrease in mutagenic index was observed in both strains. Substantial increase in mutagenicity was observed for TA-100, when assay was done by incorporating an enzyme activation system, whereas a slight increase was detected for TA-102. In vitro comet assay of waste water exhibited decrease in damage index and percentage fragmentation with the increase in dilution of waste water. Tail length also decreased with an increase in the dilution factor of waste water. These findings suggest that pharmaceutical waste water being a mix of different heavy metals and organic contaminants may have a potent mutagenic and genotoxic effect on exposed living organisms.

Application of DNA comet assay for detection of radiation treatment of grams and pulses.

PubMed

Khan, Hasan M; Khan, Ashfaq A; Khan, Sanaullah

2011-12-01

Several types of whole pulses (green lentils, red lentils, yellow lentils, chickpeas, green peas, cowpeas and yellow peas) and grams (black grams, red grams and white grams) have been investigated for the identification of radiation treatment using microgel electrophoresis of single cells (DNA comet assay). Pulses and grams were exposed to the radiation doses of 0.5, 1.0 and 5 kGy covering the legalized commercial dose range for protection from insect/pest infestations. All irradiated samples showed comet like stretching of fragmented DNA toward anode, which is expected for irradiated samples. Unirradiated samples showed many intact cells/nuclei in form of round stains or with short faint tails, which is typical for unirradiated food samples. The study shows that DNA comet assay can be used as a rapid, inexpensive and highly effective screening test for the detection of radiation treatment of foods, like pulses and grams.

A STUDY OF DUST AND GAS AT MARS FROM COMET C/2013 A1 (SIDING SPRING)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kelley, Michael S. P.; Farnham, Tony L.; Bodewits, Dennis

Although the nucleus of comet C/2013 A1 (Siding Spring) will safely pass Mars in 2014 October, the dust in the coma and tail will more closely approach the planet. Using a dynamical model of comet dust, we estimate the impact fluence. Based on our nominal model no impacts are expected at Mars. Relaxing our nominal model's parameters, the fluence is no greater than ∼10{sup –7} grains m{sup –2} for grain radii larger than 10 μm. Mars-orbiting spacecraft are unlikely to be impacted by large dust grains, but Mars may receive as many as ∼10{sup 7} grains, or ∼100 kg of total dust.more » We also estimate the flux of impacting gas molecules commonly observed in comet comae.« less

Anti-proliferative effect of biogenic gold nanoparticles against breast cancer cell lines (MDA-MB-231 & MCF-7)

NASA Astrophysics Data System (ADS)

K. S., Uma Suganya; Govindaraju, K.; Ganesh Kumar, V.; Prabhu, D.; Arulvasu, C.; Stalin Dhas, T.; Karthick, V.; Changmai, Niranjan

2016-05-01

Breast cancer is a major complication in women and numerous approaches are being developed to overcome this problem. In conventional treatments such as chemotherapy and radiotherapy the post side effects cause an unsuitable effect in treatment of cancer. Hence, it is essential to develop a novel strategy for the treatment of this disease. In the present investigation, a possible route for green synthesis of gold nanoparticles (AuNPs) using leaf extract of Mimosa pudica and its anticancer efficacy in the treatment of breast cancer cell lines is studied. The synthesized nanoparticles were found to be effective in killing cancer cells (MDA-MB-231 & MCF-7) which were studied using various anticancer assays (MTT assay, cell morphology determination, cell cycle analysis, comet assay, Annexin V-FITC/PI staining and DAPI staining). Cell morphological analysis showed the changes occurred in cancer cells during the treatment with AuNPs. Cell cycle analysis revealed apoptosis in G0/G1 to S phase. Similarly in Comet assay, there was an increase in tail length in treated cells in comparison with the control. Annexin V-FITC/PI staining assay showed prompt fluorescence in treated cells indicating the translocation of phosphatidylserine from the inner membrane. PI and DAPI staining showed the DNA damage in treated cells.

The Flaxseed-Derived Lignan Phenolic Secoisolariciresinol Diglucoside (SDG) Protects Non-Malignant Lung Cells from Radiation Damage

PubMed Central

Velalopoulou, Anastasia; Tyagi, Sonia; Pietrofesa, Ralph A.; Arguiri, Evguenia; Christofidou-Solomidou, Melpo

2015-01-01

Plant phenolic compounds are common dietary antioxidants that possess antioxidant and anti-inflammatory properties. Flaxseed (FS) has been reported to be radioprotective in murine models of oxidative lung damage. Flaxseed’s protective properties are attributed to its main biphenolic lignan, secoisolariciresinol diglucoside (SDG). SDG is a free radical scavenger, shown in cell free systems to protect DNA from radiation-induced damage. The objective of this study was to investigate the in vitro radioprotective efficacy of SDG in murine lung cells. Protection against irradiation (IR)-induced DNA double and single strand breaks was assessed by γ-H2AX labeling and alkaline comet assay, respectively. The role of SDG in modulating the levels of cytoprotective enzymes was evaluated by qPCR and confirmed by Western blotting. Additionally, effects of SDG on clonogenic survival of irradiated cells were evaluated. SDG protected cells from IR-induced death and ameliorated DNA damage by reducing mean comet tail length and percentage of γ-H2AX positive cells. Importantly, SDG significantly increased gene and protein levels of antioxidant HO-1, GSTM1 and NQO1. Our results identify the potent radioprotective properties of the synthetic biphenolic SDG, preventing DNA damage and enhancing the antioxidant capacity of normal lung cells; thus, rendering SDG a potential radioprotector against radiation exposure. PMID:26703588

The Flaxseed-Derived Lignan Phenolic Secoisolariciresinol Diglucoside (SDG) Protects Non-Malignant Lung Cells from Radiation Damage.

PubMed

Velalopoulou, Anastasia; Tyagi, Sonia; Pietrofesa, Ralph A; Arguiri, Evguenia; Christofidou-Solomidou, Melpo

2015-12-22

Plant phenolic compounds are common dietary antioxidants that possess antioxidant and anti-inflammatory properties. Flaxseed (FS) has been reported to be radioprotective in murine models of oxidative lung damage. Flaxseed's protective properties are attributed to its main biphenolic lignan, secoisolariciresinol diglucoside (SDG). SDG is a free radical scavenger, shown in cell free systems to protect DNA from radiation-induced damage. The objective of this study was to investigate the in vitro radioprotective efficacy of SDG in murine lung cells. Protection against irradiation (IR)-induced DNA double and single strand breaks was assessed by γ-H2AX labeling and alkaline comet assay, respectively. The role of SDG in modulating the levels of cytoprotective enzymes was evaluated by qPCR and confirmed by Western blotting. Additionally, effects of SDG on clonogenic survival of irradiated cells were evaluated. SDG protected cells from IR-induced death and ameliorated DNA damage by reducing mean comet tail length and percentage of γ-H2AX positive cells. Importantly, SDG significantly increased gene and protein levels of antioxidant HO-1, GSTM1 and NQO1. Our results identify the potent radioprotective properties of the synthetic biphenolic SDG, preventing DNA damage and enhancing the antioxidant capacity of normal lung cells; thus, rendering SDG a potential radioprotector against radiation exposure.

Localization of alkali-labile sites in donkey (Equus asinus) and stallion (Equus caballus) spermatozoa.

PubMed

Cortés-Gutiérrez, Elva I; Dávila-Rodríguez, Martha I; López-Fernández, Carmen; Fernández, José Luis; Crespo, Francisco; Gosálvez, Jaime

2014-01-15

The presence of constitutive alkali-labile sites (ALS) has been investigated using a protocol of DNA breakage detection-fluorescence in situ hybridization and comet assay in spermatozoa of donkey (Equus asinus) and stallion (Equus caballus). These results were compared with those obtained using a similar experimental approach using somatic cells. The relative abundance of ALS was of the order of four times more in spermatozoa than in somatic cells. Alkali-labile sites showed a tendency to cluster localized at the equatorial-distal regions of the sperm. The amount of hybridized signal in the ALS in the sperm of donkey (Equus asinus) was 1.3 times greater than in stallion (Equus caballus), and the length of the comet tail obtained in donkey sperm was 1.6 times longer than that observed in stallion (P < 0.05); however, these differences were not appreciated in somatic cells. In conclusion, ALS localization in sperm is not a randomized event and a different pattern of ALS distribution occurs for each species. These results suggest that ALS represents a species-specific issue related to chromatin organization in sperm and somatic cells in mammalian species, and they might diverge even with very short phylogenetic distances. Copyright © 2014 Elsevier Inc. All rights reserved.

Comet Hyakutake to Approach the Earth in Late March 1996

NASA Astrophysics Data System (ADS)

1996-03-01

Astronomers Prepare for a Rare Event In the early morning of January 31, 1996, Japanese amateur astronomer Yuji Hyakutake made his second comet discovery within five weeks. He found the new comet near the border between the southern constellations of Hydra (The Water-Snake) and Libra (The Scales), amazingly just three degrees from the position where he detected another comet on December 26, 1995. After two weeks of hectic activity among amateur and professional astronomers all over the world, much interesting information has now been gathered about the new comet which has been designated C/1996 B2 (Hyakutake) . In particular, it has been found to move in a near-parabolic orbit that will bring it unusually close to the Earth next month. It is then expected to become bright enough to be seen with the unaided eye and to remain so during several weeks thereafter. Preparations are now made to observe the celestial visitor with a large number of telescopes, on the ground and in space. This event offers a rare opportunity to study the immediate surroundings of a cometary nucleus in detail and the specialists intend to make the most of it. Discovery and orbit Yuji Hyakutake, of profession photoengraver and a well-known amateur astronomer, announced his new discovery without delay, and within 24 hours, it had been sighted by several other observers in Japan and Australia. Experienced comet-watchers described its appearance as `diffuse with central condensation and of magnitude 11-12', i.e. a little more than 100 times fainter than what can be seen with the unaided eye. This brightness is not unusual for a comet discovered by an amateur, although it would probably have been missed, had it been just a little fainter. In the present case, the decisive factors for Hyakutake's success were undoubtedly his very powerful equipment (25 x 150 binoculars) and the advantageous combination of the comet's southern position in the sky and his location in Kagoshima, the southernmost prefecture of Japan. Within three days only, nearly 120 positional measurements of the comet were obtained, mostly by amateur observers in Australia, PR China, the Czech Republic, France, Japan, Spain and the U.S.A. This allowed Brian Marsden of the Central Bureau for Astronomical Telegrams of the International Astronomical Union (Cambridge, Mass., U.S.A.) to compute a preliminary orbit. It showed that the comet moves along a parabola - or at least an extremely elongated ellipse - and that it must therefore have come from far away and may never have been near the Sun before. At the time of discovery, the comet was about 280 million km from the Earth and outside the orbit of Mars. Moreover, the motion of the comet is such that it will continue to approach the Earth with a speed of about 58 km/sec during the next weeks and will pass within 15 million kilometres of our planet in late March. This corresponds to one tenth of the distance between the Earth and the Sun (0.1 AU) and, in cosmical terms, the passage is therefore a very close one. Information about some earlier comet encounters may be found in the Appendix at the end of this Press Release. Continued observations have confirmed this and have also allowed to fix the moment of closest passage as Monday, March 25, at about 7h UT. At that time, the comet will be moving northwards through the northern constellation of Draco (The Dragon) at the exceptional rate of 0.77 deg/hour. The event will be best observable from the northern hemisphere. Two days later, the comet passes within a few degrees of the northern celestial pole. The perihelion (the orbital point closest to the Sun) is reached on May 1, 1996, at a distance of 35 million kilometres from the Sun, far inside the orbit of the innermost planet, Mercury. From then on, the comet will rapidly move south, crossing the celestial equator in mid-May and reaching 70 degrees south in late July. Recent observations Comet Hyakutake obviously comes from far away, maybe even from the very distant `Oort Cloud' of comets that surrounds the solar system. In this sense it is different from the periodical comets which move in closed orbits around the Sun with revolution periods between a few years and some decades. Its `dirty snowball' nucleus of ices and dust has therefore not been heated by the Sun for a very long time, perhaps never, if this is its first visit to the inner regions of the solar system. Hence it is particularly difficult to predict its future performance. Nevertheless, the available observations seem to indicate that it is a quite `active' comet and that it may therefore become comparatively bright when it approaches the Earth and later at perihelion. But how bright ? Imaging as well as spectroscopic observations have been performed in order to better characterize Comet Hyakutake. On CCD-frames obtained of the comet in early February with telescopes at the ESO La Silla Observatory and elsewhere, an elongation is clearly visible (cf. ESO Press Photo 11/96 ) in the anti-sunward direction of the coma (the cloud of gas and dust that surrounds the cometary nucleus). A real tail has not yet developed, but this is expected to happen soon. The size of the coma was measured as at least 7 arcmin, corresponding to a projected diameter of nearly 500,000 kilometres. It is also of interest that until recently the coma otherwise appeared absolutely symmetrical - there was no indication of `jets', i.e. no large vents on the surface of the nucleus had yet become active. However, on images obtained with the ESO 3.6-metre telescope in the morning of February 13, a `jet'-like feature is seen which emerges south-east of the nucleus (i.e. from the sunlit side) and curls counter-clockwise towards the opposite side (the `tail'-direction). This is probably the first evidence of localized dust production on the surface of the nucleus. CCD observations were made on February 9 at the Lowell Observatory (Flagstaff, U.S.A.) through special optical filters which isolate the light from different components of the coma, e.g. the light emitted by the OH-, C2- and CN-molecules in gaseous form and also the reflected sunlight from the dust grains. They show that the gas production rates are almost as high as those measured at famous Comet Halley when it was at about the same distance from the Sun during its approach in late 1985. The dust production of Comet Hyakutake also seems to be quite impressive. The first spectra of the new comet were obtained at La Silla with the Boller and Chivens spectrograph at the ESO 1.52-metre telescope on February 8; they show comparatively strong emission of CN, C2 and C3 molecules, cf. ESO Press Photo 12/96. This is not unusual for a comet at the corresponding heliocentric distance. In conclusion, the recent observations show Comet Hyakutake to be an `active' comet. The evaporation of the ices on the surface of its nucleus, due to the heating of the Sun, is well underway and much dust is being ejected during this process. It is quite likely that this comet will put on a fine display, starting in mid-March and lasting until soon after the perihelion passage in early May. Nevertheless, there have been some cases [1] in recent times when the activity level of new comets did not develop as expected, so some caution is necessary. The encounter on March 25 By a straightforward extrapolation of the current brightness, it would appear that Comet Hyakutake will reach magnitude 1 on March 25, 1996, at the time of the closest approach to the Earth. This is almost as bright as the brightest stars in the sky. However, it is important to consider that this is the `integrated' brightness of the entire comet head which may fill an area of several degrees in diameter in the sky. Thus the comet will appear as a moderately bright, very diffuse object that is best visible in binoculars. There will be a central point of enhanced brightness, corresponding to the innermost part of the coma around the nucleus. The motion is sufficiently fast to be easily perceptible on the stellar background. We do not know the size of the nucleus yet, but assuming - optimistically, from the measured gas and dust production - that the diameter is 10 kilometres, i.e. about as large as that of Comet Halley, then the magnitude of the nucleus alone should be about 11 at the time of the closest encounter. It may therefore be well visible in even small telescopes, as a bright point near the centre of the diffuse coma. However, it will most probably not be possible to obtain resolved images of the nucleus with ground-based telescopes; even if the size turns out to be this large, the nucleus will only subtend an angle of about 0.15 arcsec and thus appear point-like. The comet's extremely rapid motion across the sky at the encounter will constitute a major technical-observational problem for most telescopes. Moreover, it cannot be excluded that the coma is so dense that the nucleus will be completely hidden from view. The only telescope which could possibly image the nucleus as an extended object is the Hubble Space Telescope, for which observations are now being planned. Still, there is no doubt that the upcoming event offers very bright prospects for the investigation of the near-nucleus environment of a comet. Another technique which will most likely be attempted is that of radar soundings; the return time for a signal will only be 100 seconds. In the past, only a handful of comets have been investigated in this way and none in great detail. However, in view of the recent, great technological advances in this field, it should in principle be possible to `image' the nucleus of Comet Hyakutake with some of the largest radio telescopes. Predictions for the appearance of the tail(s) at the encounter are still very uncertain, since their development has not yet started. In the best case, the dust tail may become quite impressive and reach a length of many degrees, and the expected ion tail could also be quite long. The perihel passage The brightness at perihel on May 1 will probably exceed that at the Earth encounter and Comet Hyakutake could then become a very spectacular object. How bright it will actually be is much dependent on the amount of dust released from the nucleus as it approaches the Sun. Unfortunately, the viewing conditions will not be very good and the full moon on May 3 will also adversely influence the sight. Appendix: Comet encounters with the Earth There is no doubt that the close encounter with C/1996 B2 (Hyakutake) is a relatively rare event. According to Brian Marsden (Central Bureau for Astronomical Telegrams of the International Astronomical Union, Cambridge, Mass., U.S.A.): The approach of C/1996 B2 to the Earth on March 25 (0.10 AU) [2] is the closest for any comet since 1983 (when there were two comets coming to 0.06 AU and 0.03 AU within a month of each other), and it is the fifth closest approach of any comet during the past century. What is unique about this comet is that no other comet is known then to have gone on to pass anything like as close to the Sun as this one does (0.23 AU on May 1). One of the 1983 comets had about twice this comet's perihelion distance, but the approach to the Earth was well after perihelion. There was possibly a comet with a perihelion distance comparable to this one that came closer to the Earth after perihelion in the year 400, but that is very uncertain. The time interval between passage near the Earth and subsequent passage near the Sun is longer for C/1996 B2 (37 days) than for any closer Earth approach since that of the famous Lexell comet in 1770 (43 days), that comet holding the record confirmed approach to the Earth (0.015 AU or 2.2 million kilometres). C/1996 B2 is intrinsically the brightest Earth-approacher since the early eighteenth century, and the 55 days between discovery and Earth approach is a record for a pre-perihelic Earth approach. More information about other close encounters and collisions of comets with the Earth may be found in an article by Zdenek Sekanina and Don Yeomans (Jet Propulsion Laboratory, CALTECH, Pasadena, U.S.A.) which appeared in 1984 in the American journal The Astronomical Journal , Volume 89, page 154. Notes: [1] Prominent examples are Comet Kohoutek in 1973 and Comet Austin in 1990. [2] 1 Astronomical Unit (AU) = 149.6 million kilometres (the mean distance between the Earth and the Sun). Note also that ESO has set up a special Home Page for the Comet Hyakutake event ( http://www.eso.org/educnpubrelns/comet-hyakutake.html) where new information from ESO will be brought.

"Comet tail sign": A pitfall of post-gadolinium magnetic resonance imaging findings for metastatic brain tumors.

PubMed

Mitsuya, Koichi; Nakasu, Yoko; Narita, Yoshitaka; Nakasu, Satoshi; Ohno, Makoto; Miyakita, Yasuji; Abe, Masato; Ito, Ichiro; Hayashi, Nakamasa; Endo, Masahiro

2016-05-01

A highly enhanced cap attached to the surface of metastatic tumors in the brain parenchyma is occasionally encountered on magnetic resonance (MR) images. This atypical enhanced cap tends to occur in severe peritumoral edema and may produce the characteristic bulge of a metastatic mass lesion termed the "comet tail sign" (CTS). The purpose of this study was to demonstrate the features of the CTS using MR imaging and pathological findings, and to clarify its clinical relevance. We selected 21 consecutive cases of newly diagnosed metastases from MR imaging studies that demonstrated the CTS; all had diffuse peritumoral edema. The MR T2-weighted images showed similarly homogenous and high intensity signals in both the tail and peritumoral edema. Fourteen of the 21 patients underwent surgical resection of their tumors, and 12 tails were separately removed for pathological examination, no tumor cells which revealed. We speculate that the CTS does not contain neoplastic tissues but is observed as a result of the leakage of contrast medium from the tumor body into the interstitial space of the white matter. Although CTS is a peculiar and uncommon enhancement pattern, it has clinical significance in determining the extent of the margin for invasive local treatments, such as surgical resection or stereotactic radiotherapy; this is particularly true in and near the eloquent areas.

Detection of DNA damage in workers exposed to JP-8 jet fuel.

PubMed

Krieg, Edward F; Mathias, Patricia I; Toennis, Christine A; Clark, John C; Marlow, Kate L; B'hymer, Clayton; Singh, Narendra P; Gibson, Roger L; Butler, Mary Ann

2012-09-18

The genotoxicity of jet propulsion fuel 8 (JP-8) was assessed in the leukocytes of archived blood specimens from U.S. Air Force personnel using the comet assay. No differences in mean comet assay measurements were found between low, moderate, and high exposure groups before or after a 4h work shift. Before the work shift, mean tail DNA and mean tail (Olive) moment increased as the concentration of benzene measured in end-exhaled breath increased, indicating that prior environmental or work-related exposures to benzene produced DNA damage. The number of cells with highly damaged DNA decreased as the pre-shift benzene concentration in breath increased. It is not clear why the decrease is occurring. Mean tail DNA and mean tail (Olive) moment decreased as the concentrations of benzene and naphthalene measured in breath immediately after the work shift increased. These inverse relationships may reflect a slower rate of absorption or a faster rate of expiration of benzene in the lung. The number of cells with highly damaged DNA increased as the concentration of urinary (2-methoxyethoxy)acetic acid (MEAA) increased. This relationship was not seen in urinary MEAA adjusted for creatinine. MEAA is a metabolite of the deicing agent 2-(2-methoxyethoxy)ethanol contained in JP-8. MEAA or a component of JP-8 correlated with MEAA may have a toxic effect on DNA. Published by Elsevier B.V.

Assessment of the predictive capacity of the optimized in vitro comet assay using HepG2 cells.

PubMed

Hong, Yoon-Hee; Jeon, Hye Lyun; Ko, Kyung Yuk; Kim, Joohwan; Yi, Jung-Sun; Ahn, Ilyoung; Kim, Tae Sung; Lee, Jong Kwon

2018-03-01

Evaluation of DNA damage is critical during the development of new drugs because it is closely associated with genotoxicity and carcinogenicity. The in vivo comet assay to assess DNA damage is globally harmonized as OECD TG 489. However, a comet test guideline that evaluates DNA damage without sacrificing animals does not yet exist. The goal of this study was to select an appropriate cell line for optimization of the in vitro comet assay to assess DNA damage. We then evaluated the predictivity of the in vitro comet assay using the selected cell line. In addition, the effect of adding S9 was evaluated using 12 test chemicals. For cell line selection, HepG2, Chinese hamster lung (CHL/IU), and TK6 cell lines were evaluated. We employed a method for the in vitro comet assay based on that for the in vivo comet assay. The most appropriate cell line was determined by% tail DNA increase after performing in vitro comet assays with 6 test chemicals. The predictivity of the in vitro comet assay using the selected cell line was measured with 10 test chemicals (8 genotoxins and 2 non-genotoxic chemicals). The HepG2 cell line was found to be the most appropriate, and in vitro comet assays using HepG2 cells exhibited a high accuracy of 90% (9/10). This study suggests that HepG2 is an optimal cell line for the in vitro comet assay to assess DNA damage. Copyright © 2018 Elsevier B.V. All rights reserved.

April 30 Hubble View of ISON

NASA Image and Video Library

2013-11-22

On April 30, NASA's Hubble Space Telescope observed Comet ISON again. The comet is in the upper middle, showing the long tail. Various galaxies and stars appear behind it. In this image, Hubble trained its telescope on the stars instead of following the comet. The result is that the comet appears fuzzier, but the stars and galaxies are more detailed and precise. These dimmer features don't pop out if the camera is moving, following along with ISON. To see them, you really need to dwell in one place until they emerge from the noise. Credit: NASA/ESA/STScI/AURA -------- More details on Comet ISON: Comet ISON began its trip from the Oort cloud region of our solar system and is now travelling toward the sun. The comet will reach its closest approach to the sun on Thanksgiving Day -- 28 Nov 2013 -- skimming just 730,000 miles above the sun's surface. If it comes around the sun without breaking up, the comet will be visible in the Northern Hemisphere with the naked eye, and from what we see now, ISON is predicted to be a particularly bright and beautiful comet. Catalogued as C/2012 S1, Comet ISON was first spotted 585 million miles away in September 2012. This is ISON's very first trip around the sun, which means it is still made of pristine matter from the earliest days of the solar system’s formation, its top layers never having been lost by a trip near the sun. Comet ISON is, like all comets, a dirty snowball made up of dust and frozen gases like water, ammonia, methane and carbon dioxide -- some of the fundamental building blocks that scientists believe led to the formation of the planets 4.5 billion years ago. NASA has been using a vast fleet of spacecraft, instruments, and space- and Earth-based telescope, in order to learn more about this time capsule from when the solar system first formed. The journey along the way for such a sun-grazing comet can be dangerous. A giant ejection of solar material from the sun could rip its tail off. Before it reaches Mars -- at some 230 million miles away from the sun -- the radiation of the sun begins to boil its water, the first step toward breaking apart. And, if it survives all this, the intense radiation and pressure as it flies near the surface of the sun could destroy it altogether. This collection of images show ISON throughout that journey, as scientists watched to see whether the comet would break up or remain intact. The comet reaches its closest approach to the sun on Thanksgiving Day -- Nov. 28, 2013 -- skimming just 730,000 miles above the sun’s surface. If it comes around the sun without breaking up, the comet will be visible in the Northern Hemisphere with the naked eye, and from what we see now, ISON is predicted to be a particularly bright and beautiful comet. ISON stands for International Scientific Optical Network, a group of observatories in ten countries who have organized to detect, monitor, and track objects in space. ISON is managed by the Keldysh Institute of Applied Mathematics, part of the Russian Academy of Sciences. NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Comparative sacral morphology and the reconstructed tail lengths of five extinct primates: Proconsul heseloni, Epipliopithecus vindobonensis, Archaeolemur edwardsi, Megaladapis grandidieri, and Palaeopropithecus kelyus.

PubMed

Russo, Gabrielle A

2016-01-01

This study evaluated the relationship between the morphology of the sacrum-the sole bony link between the tail or coccyx and the rest of the body-and tail length (including presence/absence) and function using a comparative sample of extant mammals spanning six orders (Primates, Carnivora, Rodentia, Diprotodontia, Pilosa, Scandentia; N = 472). Phylogenetically-informed regression methods were used to assess how tail length varied with respect to 11 external and internal (i.e., trabecular) bony sacral variables with known or suspected biomechanical significance across all mammals, only primates, and only non-primates. Sacral variables were also evaluated for primates assigned to tail categories ('tailless,' 'nonprehensile short-tailed,' 'nonprehensile long-tailed,' and 'prehensile-tailed'). Compared to primates with reduced tail lengths, primates with longer tails generally exhibited sacra having larger caudal neural openings than cranial neural openings, and last sacral vertebrae with more mediolaterally-expanded caudal articular surfaces than cranial articular surfaces, more laterally-expanded transverse processes, more dorsally-projecting spinous processes, and larger caudal articular surface areas. Observations were corroborated by the comparative sample, which showed that shorter-tailed (e.g., Lynx rufus [bobcat]) and longer-tailed (e.g., Acinonyx jubatus [cheetah]) non-primate mammals morphologically converge with shorter-tailed (e.g., Macaca nemestrina) and longer-tailed (e.g., Macaca fascicularis) primates, respectively. 'Prehensile-tailed' primates exhibited last sacral vertebrae with more laterally-expanded transverse processes and greater caudal articular surface areas than 'nonprehensile long-tailed' primates. Internal sacral variables performed poorly compared to external sacral variables in analyses of extant primates, and were thus deemed less useful for making inferences concerning tail length and function in extinct primates. The tails lengths of five extinct primates were reconstructed from the external sacral variables: Archaeolemur edwardsi had a 'nonprehensile long tail,' Megaladapis grandidieri, Palaeopropithecus kelyus, and Epipliopithecus vindobonensis probably had 'nonprehensile short tails,' and Proconsul heseloni was 'tailless.' Copyright © 2015 Elsevier Ltd. All rights reserved.

Comet or Asteroid?

NASA Astrophysics Data System (ADS)

1997-11-01

When is a minor object in the solar system a comet? And when is it an asteroid? Until recently, there was little doubt. Any object that was found to display a tail or appeared diffuse was a comet of ice and dust grains, and any that didn't, was an asteroid of solid rock. Moreover, comets normally move in rather elongated orbits, while most asteroids follow near-circular orbits close to the main plane of the solar system in which the major planets move. However, astronomers have recently discovered some `intermediate' objects which seem to possess properties that are typical for both categories. For instance, a strange object (P/1996 N2 - Elst-Pizarro) was found last year at ESO ( ESO Press Photo 36/96 ) which showed a cometary tail, while moving in a typical asteroidal orbit. At about the same time, American scientists found another (1996 PW) that moved in a very elongated comet-type orbit but was completely devoid of a tail. Now, a group of European scientists, by means of observations carried out at the ESO La Silla observatory, have found yet another object that at first appeared to be one more comet/asteroid example. However, continued and more detailed observations aimed at revealing its true nature have shown that it is most probably a comet . Consequently, it has received the provisional cometary designation P/1997 T3 . The Uppsala-DLR Trojan Survey Some time ago, Claes-Ingvar Lagerkvist (Astronomical Observatory, Uppsala, Sweden), in collaboration with Gerhard Hahn, Stefano Mottola, Magnus Lundström and Uri Carsenty (DLR, Institute of Planetary Exploration, Berlin, Germany), started to study the distribution of asteroids near Jupiter. They were particularly interested in those that move in orbits similar to that of Jupiter and which are located `ahead' of Jupiter in the so-called `Jovian L4 Lagrangian point'. Together with those `behind' Jupiter, these asteroids have been given the names of Greek and Trojan Heroes who participated in the famous Trojan war. Thus such asteroids are known as the Trojans and the mentioned programme is referred to as the Uppsala-DLR Trojan Survey . In September and October/November 1996, the ESO Schmidt telescope was used to cover about 900 square degrees twice centered on the sky field in the direction of the Jovian L4 point. The observations were made by ESO night-assistants Guido and Oscar Pizarro . By inspection of those from September, Claes-Ingvar Lagerkvist found a total of about 400 Trojan asteroids, most of which were hitherto unknown. Their accurate positions were measured on a two-coordinate measuring machine at the ESO Headquarters in Garching (Germany). During the same period, the 0.6-m Bochum telescope at La Silla was used for additional observations of positions and magnitudes. An asteroid with a tail? ESO Press Photo 31a/97 ESO Press Photo 31a/97 [JPG, 120k] Caption: Discovery image of P/1997 T3 , obtained on October 1, 1997, with the 1-metre ESO Schmidt telescope at the La Silla observatory in the Chilean Atacama desert. The object is seen as a small straight and sharp `asteroidal' trail (in 4 o'clock orientation) on the lower right side of the strong white line in the middle of the field, directly opposite the white dot (these marks were placed in order to mark the position of the new object on the film). A new object was found by Claes-Ingvar Lagerkvist on a film obtained with the ESO 1-metre Schmidt telescope on October 1, 1997. The appearance was that of a point light source, i.e. it was presumably of asteroidal nature , cf. ESO Press Photo 31a/97. ESO Press Photo 31b/97 ESO Press Photo 31b/97 [JPG, 45k] Caption: P/1997 T3 on October 6, 1997 at 05:13:54 UT. This image of the new object (slightly above and to the left of the centre of the field) was obtained with the 0.6-m Bochum telescope at La Silla; the observer was Andreas Nathues . The tail is faintly visible to the lower left of the point-like object (in the 7 o'clock direction). However, when Andreas Nathues (DLR, Institute of Planetary Exploration) soon thereafter obtained seven unfiltered CCD images on three consecutive nights with the 60-cm `Bochum telescope' at La Silla, Uri Carsenty found a tail extending 15 arcseconds in the WSE direction from the point source, cf. ESO Press Photo 31b/97. The (red) magnitude was about 19, or 150,000 times fainter than what is visible to the naked eye. More observations were obtained at La Silla during the following nights, confirming the persistent presence of this tail. NTT observations confirm the cometary nature of P/1997 T3 ESO Press Photo 31c/97 ESO Press Photo 31c/97 [JPG, 52k] Caption: Deep NTT image of P/1997 T3. This image covers a field of 105 x 60 arcsec and is a composite of several CCD exposures. It was taken with the ESO New Technology Telescope (NTT) and the EMMI multi-mode instrument by ESO astronomers Hermann Boehnhardt and Olivier Hainaut on different days between 21 and 25 October 1997. By computer processing, the images of P/1997 T3 are aligned to the same pixel position and co-added in order to increase the visibility of the comet. Due to the motion of the comet, multiple images of several galaxies and stars appear in this photo. At the time of the observations, the comet was about 3.34 AU from Earth and about 4.30 AU from the Sun. A larger version [JPG, 384k] is also available. In late October 1997, further images of the new object and its tail were taken with the ESO 3.5-m New Technology Telescope (NTT) at La Silla, cf. ESO Press Photo 31c/97. On these, the narrow tail was seen to be at least 90 arcsec long and pointing roughly in the Sun direction . The steady appearance and the sunward orientation of the tail indicates that it consists of dust. Moreover, a preliminary image analysis shows the presence of a weak and very condensed coma of dust grains around the nucleus. Interestingly, a series of images through several broadband filters with a total of almost 30 min exposure time did not show any trace of a normal, anti-sunward tail seen in most comets. Still, these observations indicate that the object resembles a typical comet much more than originally thought. This is also supported by the fact that its orbit, calculated on the basis of positional observations during the past month, has been found to be moderately elongated (eccentricity 0.36). The mean distance to the Sun is 6.67 AU (1000 million kilometres), but it comes as close as 4.25 AU (635 million kilometres) at its perihelion. The orbital period is about 17 years. More observations needed! It will be interesting to follow this new object in coming years. Will it remain `cometary' or will the unusual tail disappear after a while? Could it be that some `asteroids' in `cometary' orbits, if observed in more detail with a larger telescope, as was done in this case with the NTT, will also turn out to have a faint coma and even a tail? It is at this moment still unknown which implications the discovery of apparently `intermediate' objects may have on our understanding of the origin and evolution of the solar system. In particular, it is not at all clear whether they represent a completely new class of objects with an internal structure (and composition?) that is significantly different from a `dirty-snowball' cometary nucleus or a rocky asteroid. It may also be that some asteroids have substantial deposits of icy material on or near the surface that may be set free under certain circumstances and mimic cometary activity. This might in theory happen by collisions with other, smaller objects or due to an internal heat source. Only further observations of such objects will allow to tell. Where to find more information Here are some WWW-addresses where more useful information may be obtained about the comet/asteroid phenomenon: * http://www.dlr.de/Berlin/ - Small Bodies Group at the DLR (Berlin, Germany) * http://www.astro.uu.se/planet/asteroid - Asteroids' page of the Uppsala planetary system group (Sweden) * http://www.skypub.com/comets/1996n2pw.html - Are They Comets or Asteroids? (adapted version of article by Stuart J. Goldman in Sky & Telescope, November 1996) * http://cfa-www.harvard.edu/~graff/pressreleases/1996PW.html - Two Unusual Objects: 1996 PW and C/1996 N2 (Press information from the Harvard-Smithsonian Center for Astrophysics (CfA), Cambridge, Massachusetts, U.S.A.) * Abstract of research article : Origin and Evolution of the Unusual Object 1996 PW: Asteroids from the Oort Cloud? by Paul R. Weissman and Harold F. Levison * Abstract of research article : The Main Asteroid Belt - Comet Graveyard or Nursery? by Mark Hammergren * Preprint of research article : The Lightcurve and Colours of Unusual Minor Planet 1996 PW by J.K. Davies et al. This Press Release is accompanied by ESO PR Photo 31a/97 [JPG, 120k] , ESO PR Photo 31b/97 [JPG, 45k] and ESO PR Photo 31c/97 [JPG, 52k]. A larger version of ESO PR Photo 31c/97 [JPG, 384k] is also available. They may be reproduced, if credit is given to the European Southern Observatory. How to obtain ESO Press Information ESO Press Information is made available on the World-Wide Web (URL: http://www.eso.org ).

NASA's Hubble Sees Asteroid Spout Six Comet-like Tails

NASA Image and Video Library

2013-11-13

This NASA Hubble Space Telescope set of images reveals a never-before-seen set of six comet-like tails radiating from a body in the asteroid belt, designated P/2013 P5. The asteroid was discovered as an unusually fuzzy-looking object with the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) survey telescope in Hawaii. The multiple tails were discovered in Hubble images taken on Sept. 10, 2013. When Hubble returned to the asteroid on Sept. 23, the asteroid's appearance had totally changed. It looked as if the entire structure had swung around. One interpretation is that the asteroid's rotation rate has been increased to the point where dust is falling off the surface and escaping into space where the pressure of sunlight sweeps out fingerlike tails. According to this theory, the asteroid's spin has been accelerated by the gentle push of sunlight. The object, estimated to be no more than 1,400 feet across, has ejected dust for at least five months, based on analysis of the tail structure. These visible-light, false-color images were taken with Hubble's Wide Field Camera 3. Object Name: P/2013 P5 Image Type: Astronomical/Annotated Credit: NASA, ESA, and D. Jewitt (UCLA) NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

NASA's Hubble Sees Asteroid Spout Six Comet-like Tails

NASA Image and Video Library

2013-11-13

P/2013 P5 on September 23, 2013. --- This NASA Hubble Space Telescope set of images reveals a never-before-seen set of six comet-like tails radiating from a body in the asteroid belt, designated P/2013 P5. The asteroid was discovered as an unusually fuzzy-looking object with the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) survey telescope in Hawaii. The multiple tails were discovered in Hubble images taken on Sept. 10, 2013. When Hubble returned to the asteroid on Sept. 23, the asteroid's appearance had totally changed. It looked as if the entire structure had swung around. One interpretation is that the asteroid's rotation rate has been increased to the point where dust is falling off the surface and escaping into space where the pressure of sunlight sweeps out fingerlike tails. According to this theory, the asteroid's spin has been accelerated by the gentle push of sunlight. The object, estimated to be no more than 1,400 feet across, has ejected dust for at least five months, based on analysis of the tail structure. These visible-light, false-color images were taken with Hubble's Wide Field Camera 3. Object Name: P/2013 P5 Image Type: Astronomical/Annotated Credit: NASA, ESA, and D. Jewitt (UCLA) NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

NASA's Hubble Sees Asteroid Spout Six Comet-like Tails

NASA Image and Video Library

2013-11-13

P/2013 P5 on September 10, 2013. --- This NASA Hubble Space Telescope set of images reveals a never-before-seen set of six comet-like tails radiating from a body in the asteroid belt, designated P/2013 P5. The asteroid was discovered as an unusually fuzzy-looking object with the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) survey telescope in Hawaii. The multiple tails were discovered in Hubble images taken on Sept. 10, 2013. When Hubble returned to the asteroid on Sept. 23, the asteroid's appearance had totally changed. It looked as if the entire structure had swung around. One interpretation is that the asteroid's rotation rate has been increased to the point where dust is falling off the surface and escaping into space where the pressure of sunlight sweeps out fingerlike tails. According to this theory, the asteroid's spin has been accelerated by the gentle push of sunlight. The object, estimated to be no more than 1,400 feet across, has ejected dust for at least five months, based on analysis of the tail structure. These visible-light, false-color images were taken with Hubble's Wide Field Camera 3. Object Name: P/2013 P5 Image Type: Astronomical/Annotated Credit: NASA, ESA, and D. Jewitt (UCLA) NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Comet ISON Enhanced

NASA Image and Video Library

2013-11-22

Taken on 19 Nov. 2013, this image shows a composite "stacked" image of comet ISON. These five stacked images of 10 seconds each were taken with the 20" Marshall Space Flight Center telescope in New Mexico. This technique allows the comet's sweeping tail to emerge with more detail. Credit: NASA/MSFC/MEO/Cameron McCarty -------- More details on Comet ISON: Comet ISON began its trip from the Oort cloud region of our solar system and is now travelling toward the sun. The comet will reach its closest approach to the sun on Thanksgiving Day -- 28 Nov 2013 -- skimming just 730,000 miles above the sun's surface. If it comes around the sun without breaking up, the comet will be visible in the Northern Hemisphere with the naked eye, and from what we see now, ISON is predicted to be a particularly bright and beautiful comet. Catalogued as C/2012 S1, Comet ISON was first spotted 585 million miles away in September 2012. This is ISON's very first trip around the sun, which means it is still made of pristine matter from the earliest days of the solar system’s formation, its top layers never having been lost by a trip near the sun. Comet ISON is, like all comets, a dirty snowball made up of dust and frozen gases like water, ammonia, methane and carbon dioxide -- some of the fundamental building blocks that scientists believe led to the formation of the planets 4.5 billion years ago. NASA has been using a vast fleet of spacecraft, instruments, and space- and Earth-based telescope, in order to learn more about this time capsule from when the solar system first formed. The journey along the way for such a sun-grazing comet can be dangerous. A giant ejection of solar material from the sun could rip its tail off. Before it reaches Mars -- at some 230 million miles away from the sun -- the radiation of the sun begins to boil its water, the first step toward breaking apart. And, if it survives all this, the intense radiation and pressure as it flies near the surface of the sun could destroy it altogether. This collection of images show ISON throughout that journey, as scientists watched to see whether the comet would break up or remain intact. The comet reaches its closest approach to the sun on Thanksgiving Day -- Nov. 28, 2013 -- skimming just 730,000 miles above the sun’s surface. If it comes around the sun without breaking up, the comet will be visible in the Northern Hemisphere with the naked eye, and from what we see now, ISON is predicted to be a particularly bright and beautiful comet. ISON stands for International Scientific Optical Network, a group of observatories in ten countries who have organized to detect, monitor, and track objects in space. ISON is managed by the Keldysh Institute of Applied Mathematics, part of the Russian Academy of Sciences. NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on The 67P/Churyumov-Gerasimenko observation campaign in support of the Rosetta mission.

PubMed

Snodgrass, C; A'Hearn, M F; Aceituno, F; Afanasiev, V; Bagnulo, S; Bauer, J; Bergond, G; Besse, S; Biver, N; Bodewits, D; Boehnhardt, H; Bonev, B P; Borisov, G; Carry, B; Casanova, V; Cochran, A; Conn, B C; Davidsson, B; Davies, J K; de León, J; de Mooij, E; de Val-Borro, M; Delacruz, M; DiSanti, M A; Drew, J E; Duffard, R; Edberg, N J T; Faggi, S; Feaga, L; Fitzsimmons, A; Fujiwara, H; Gibb, E L; Gillon, M; Green, S F; Guijarro, A; Guilbert-Lepoutre, A; Gutiérrez, P J; Hadamcik, E; Hainaut, O; Haque, S; Hedrosa, R; Hines, D; Hopp, U; Hoyo, F; Hutsemékers, D; Hyland, M; Ivanova, O; Jehin, E; Jones, G H; Keane, J V; Kelley, M S P; Kiselev, N; Kleyna, J; Kluge, M; Knight, M M; Kokotanekova, R; Koschny, D; Kramer, E A; López-Moreno, J J; Lacerda, P; Lara, L M; Lasue, J; Lehto, H J; Levasseur-Regourd, A C; Licandro, J; Lin, Z Y; Lister, T; Lowry, S C; Mainzer, A; Manfroid, J; Marchant, J; McKay, A J; McNeill, A; Meech, K J; Micheli, M; Mohammed, I; Monguió, M; Moreno, F; Muñoz, O; Mumma, M J; Nikolov, P; Opitom, C; Ortiz, J L; Paganini, L; Pajuelo, M; Pozuelos, F J; Protopapa, S; Pursimo, T; Rajkumar, B; Ramanjooloo, Y; Ramos, E; Ries, C; Riffeser, A; Rosenbush, V; Rousselot, P; Ryan, E L; Santos-Sanz, P; Schleicher, D G; Schmidt, M; Schulz, R; Sen, A K; Somero, A; Sota, A; Stinson, A; Sunshine, J M; Thompson, A; Tozzi, G P; Tubiana, C; Villanueva, G L; Wang, X; Wooden, D H; Yagi, M; Yang, B; Zaprudin, B; Zegmott, T J

2017-07-13

We present a summary of the campaign of remote observations that supported the European Space Agency's Rosetta mission. Telescopes across the globe (and in space) followed comet 67P/Churyumov-Gerasimenko from before Rosetta's arrival until nearly the end of the mission in September 2016. These provided essential data for mission planning, large-scale context information for the coma and tails beyond the spacecraft and a way to directly compare 67P with other comets. The observations revealed 67P to be a relatively 'well-behaved' comet, typical of Jupiter family comets and with activity patterns that repeat from orbit to orbit. Comparison between this large collection of telescopic observations and the in situ results from Rosetta will allow us to better understand comet coma chemistry and structure. This work is just beginning as the mission ends-in this paper, we present a summary of the ground-based observations and early results, and point to many questions that will be addressed in future studies.This article is part of the themed issue 'Cometary science after Rosetta'. © 2017 The Author(s).

The Giacobini-Zinner magnetotail - Tail configuration and current sheet

NASA Technical Reports Server (NTRS)

Mccomas, D. J.; Gosling, J. T.; Bame, S. J.; Slavin, J. A.; Smith, E. J.

1987-01-01

The configuration and properties of the draped Giacobini-Zinner magnetotail and its field-reversing current sheet are studied using the combined magnetic field and plasma electron data sets obtained from the International Cometary Explorer spacecraft when it traversed (in October 1985) the comet 7800 km downstream of the nucleus. The MHD equations are used to derive pressure balance and plasma acceleration conditions. The implications of the various properties derived are examined, particularly with regard to the upstream near-nucleus region where the tail formation process occurs.

Adaptation of the neutral bacterial comet assay to assess antimicrobial-mediated DNA double-strand breaks in Escherichia coli

PubMed Central

SOLANKY, DIPESH; HAYDEL, SHELLEY E.

2012-01-01

This study aimed to determine the mechanism of action of a natural antibacterial clay mineral mixture, designated CB, by investigating the induction of DNA double-strand breaks (DSBs) in Escherichia coli. To quantify DNA damage upon exposure to soluble antimicrobial compounds, we modified a bacterial neutral comet assay, which primarily associates the general length of an electrophoresed chromosome, or comet, with the degree of DSB-associated DNA damage. To appropriately account for antimicrobial-mediated strand fragmentation, suitable control reactions consisting of exposures to water, ethanol, kanamycin, and bleomycin were developed and optimized for the assay. Bacterial exposure to the CB clay resulted in significantly longer comet lengths, compared to water and kanamycin exposures, suggesting that the induction of DNA DSBs contributes to the killing activity of this antibacterial clay mineral mixture. The comet assay protocol described herein provides a general technique for evaluating soluble antimicrobial-derived DNA damage and for comparing DNA fragmentation between experimental and control assays. PMID:22940101

Establishing a model for assessing DNA damage in murine brain cells as a molecular marker of chemotherapy-associated cognitive impairment

PubMed Central

Krynetskiy, Evgeny; Krynetskaia, Natalia; Rihawi, Diana; Wieczerzak, Katarzyna; Ciummo, Victoria; Walker, Ellen

2013-01-01

Aims Chemotherapy-associated cognitive impairment often follows cancer chemotherapy. We explored chemotherapy-induced DNA damage in the brain cells of mice treated with 5-fluorouracil (5FU), an antineoplastic agent, to correlate the extent of DNA damage to behavioral functioning in an autoshaping-operant mouse model of chemotherapy-induced learning and memory deficits (Foley et al. 2008). Main methods Male, Swiss-Webster mice were injected once with saline or 75 mg/kg 5FU at 0, 12, and 24 h and weighed every 24 h. Twenty-four h after the last injection, the mice were tested in a two-day acquisition and retention of a novel response task for food reinforcement. Murine brain cells were analyzed for the presence of single- and double-strand DNA breaks by the single cell gel electrophoresis assay (the Comet assay). Key findings We detected significant differences (p<0.0001) for all DNA damage characteristics (DNA “comet” tail shape, migration pattern, tail moment and Olive moments) between control mice cohort and 5FU-treated mice cohort: tail length – 119 vs. 153; tail moment – 101 vs. 136; olive moment – 60 vs. 82, correspondingly. We found a positive correlation between increased response rates (r=0.52, p<0.05) and increased rate of errors (r=0.51, p<0.05), and DNA damage on day 1. For all 15 mice (saline-treated and 5FU-treated mice), we found negative correlations between DNA damage and weight (r=−0.75, p<0.02). Significance Our results indicate that chemotherapy-induced DNA damage changes the physiological status of the brain cells and may provide insights to the mechanisms for cognitive impairment after cancer chemotherapy. PMID:23567806

Biomonitoring of DNA damage in peripheral blood lymphocytes of subjects with dental restorative fillings.

PubMed

Di Pietro, Angela; Visalli, Giuseppa; La Maestra, Sebastiano; Micale, Rosanna; Baluce, Barbara; Matarese, Giovanni; Cingano, Luciano; Scoglio, Maria Elena

2008-02-29

Dental fillings provide a major iatrogenic exposure to xenobiotic compounds due to the high prevalence of surface restorations in developed countries. Experimental data suggest that both amalgams, which contain mercury, and resin-based dental materials cause an impairment of the cellular pro- and anti-oxidant redox balance. The aim of this study was to assess the potential genotoxicity of dental restorative compounds in peripheral blood lymphocytes of young exposed subjects compared with controls. The study examined, by use of the comet assay, 68 carefully selected subjects taking into account the major known confounding factors. In the 44 exposed subjects, the mean numbers of restored surfaces was 3.0 and 3.8 in males and females, respectively. Tail length, percentage of DNA in the tail, tail moment or Olive tail moment were twofold higher in the exposed group than in unexposed controls, with significant differences. No significant difference was observed between amalgam and composite fillings. Furthermore, as shown by multivariate analysis, the association between dental fillings and DNA damage was enhanced by the number of fillings and by the exposure time. Among the lifestyle variables, a moderate physical activity showed a protective effect, being inversely correlated to the DNA damage parameters evaluated. On the whole, the use of DNA-migration allowed us to detect for the first time the potential adverse impact on human health of both kinds of dental filling constituents, the amalgams and the methacrylates. The main mechanism underlying the genotoxicity of dental restorative materials of various nature may be ascribed to the ability of both amalgams and methacrylates to trigger the generation of cellular reactive oxygen species, able to cause oxidative DNA lesions.

Dust environment and dynamical history of a sample of short-period comets . II. 81P/Wild 2 and 103P/Hartley 2

NASA Astrophysics Data System (ADS)

Pozuelos, F. J.; Moreno, F.; Aceituno, F.; Casanova, V.; Sota, A.; López-Moreno, J. J.; Castellano, J.; Reina, E.; Climent, A.; Fernández, A.; San Segundo, A.; Häusler, B.; González, C.; Rodriguez, D.; Bryssinck, E.; Cortés, E.; Rodriguez, F. A.; Baldris, F.; García, F.; Gómez, F.; Limón, F.; Tifner, F.; Muler, G.; Almendros, I.; de los Reyes, J. A.; Henríquez, J. A.; Moreno, J. A.; Báez, J.; Bel, J.; Camarasa, J.; Curto, J.; Hernández, J. F.; González, J. J.; Martín, J. J.; Salto, J. L.; Lopesino, J.; Bosch, J. M.; Ruiz, J. M.; Vidal, J. R.; Ruiz, J.; Sánchez, J.; Temprano, J.; Aymamí, J. M.; Lahuerta, L.; Montoro, L.; Campas, M.; García, M. A.; Canales, O.; Benavides, R.; Dymock, R.; García, R.; Ligustri, R.; Naves, R.; Lahuerta, S.; Pastor, S.

2014-11-01

Aims: This paper is a continuation of the first paper in this series, where we presented an extended study of the dust environment of a sample of short-period comets and their dynamical history. On this occasion, we focus on comets 81P/Wild 2 and 103P/Hartley 2, which are of special interest as targets of the spacecraft missions Stardust and EPOXI. Methods: As in the previous study, we used two sets of observational data: a set of images, acquired at Sierra Nevada and Lulin observatories, and the Afρ data as a function of the heliocentric distance provided by the amateur astronomical association Cometas-Obs. The dust environment of comets (dust loss rate, ejection velocities, and size distribution of the particles) was derived from our Monte Carlo dust tail code. To determine their dynamical history we used the numerical integrator Mercury 6.2 to ascertain the time spent by these objects in the Jupiter family Comet region. Results: From the dust analysis, we conclude that both 81P/Wild 2 and 103P/Hartley 2 are dusty comets, with an annual dust production rate of 2.8 × 109 kg yr-1 and (0.4-1.5) × 109 kg yr-1, respectively. From the dynamical analysis, we determined their time spent in the Jupiter family Comet region as ~40 yr in the case of 81P/Wild 2 and ~1000 yr for comet 103P/Hartley 2. These results imply that 81P/Wild 2 is the youngest and the most active comet of the eleven short-period comets studied so far, which tends to favor the correlation between the time spent in JFCs region and the comet activity previously discussed.

International cometary explorer encounter with giacobini-zinner: magnetic field observations.

PubMed

Smith, E J; Tsurutani, B T; Slvain, J A; Jones, D E; Siscoe, G L; Mendis, D A

1986-04-18

The vector helium magnetometer on the International Cometary Explorer observed the magnetic fields induced by the interaction of comet Giacobini-Zinner with the solar wind. A magnetic tail was penetrated approximately 7800 kilometers downstream from the comet and was found to be 10(4) kilometers wide. It consisted of two lobes, containing oppositely directed fields with strengths up to 60 nanoteslas, separated by a plasma sheet approximately 10(3)kilometers thick containing a thin current sheet. The magnetotail was enclosed in an extended ionosheath characterized by intense hydromagnetic turbulene and interplanetary fields draped around the comet. A distant bow wave, which may or may not have been a bow shock, was observed at both edges of the ionosheath. Weak turbulence was observed well upstream of the bow wave.

Three component plasma electron distribution in the intermediate ionized coma of Comet Giacobini-Zinner

NASA Astrophysics Data System (ADS)

Zwickl, R. D.; Baker, D. N.; Bame, S. J.; Feldman, W. C.; Fuselier, S. A.; Huebner, W. F.; McComas, D. J.; Young, D. T.

1986-04-01

The observation of three distinct components of the electron distribution function measured in the intermediate ionized coma (IIC) and plasma tail of Comet Giacobini-Zinner is reported. It is believed that the cold component represents electrons produced close to the comet nucleus by ionization of cometary matter and subsequent cooling by Coulomb collisions. The second component also appears to be composed of electrons produced by photoionization of cometary neutrals, but sufficiently far from the nucleus that the distributions are largely unaffected by Coulomb interactions. The hot component is probably a population of electrons originating in the solar wind. Throughout the IIC, the electrostatic potential of the spacecraft was very low (less than 0.8 eV), implying that ICE generated very little impact-produced plasma during its passage.

Evolution of large-sclae plasma structures in comets: Kinematics and physics

NASA Technical Reports Server (NTRS)

Brandt, John C.

1988-01-01

Disconnection Events are the dramatic part of the periodic morphology involving the separation of the entire plasma tail from the head region of the comet and the growth of a new plasma. The coordinated observations of Comet Halley recorded approximately 30 DEs during the 7 months of plasma activity; 19 of these are obvious. The plasma physics of these events were approached via a detailed, kinematic investigation of specific DEs and the solar-wind environment associated with it. As the detailed investigations are completed, researchers should be able to answer the question of a single or multiple mechanism(s) for DEs and determine which mechanism(s) are important. At present, the mechanism of sunward magnetic reconnection caused by interplanetary sector boundary crossing in consistent with the data available.

[The maternal effect in infantile autism: elevated DNA damage degree in patients and their mothers].

PubMed

Porokhovnik, L N; Kostyuk, S V; Ershova, E S; Stukalov, S M; Veiko, N N; Korovina, N Yu; Gorbachevskaya, N L; Sorokin, A B; Lyapunova, N A

2016-05-01

Infantile autism is a common disorder of mental development, which is characterized by impairments in the communicative, cognitive and speech spheres and obsessional stereotyped behaviour. Although in most cases, pathogenic factors remain unclear, infantile autism has a significant hereditary component, however, its etiology is also under the influence of environmental factors, including the condition of the mother's body during pregnancy ("maternal effect"). Oxidative stress is assumed to play a key role in the pathogenesis of infantile autism. It is known that oxidative stress has a prominent genotoxic effect, which is realized through inducing single and double strand breaks of the nuclear DNA. We evaluated the degree of DNA damage in patients with infantile autism and their mothers using DNA comet assay. The comet tail moment and DNA per cent ratio in the tail were assessed for each individual. The two parameters appeared to be strongly correlated (r=0.90). Mean and median values of both parameters were considerably higher in the sample of autistic children, than in age-matching healthy controls. Interestingly, these parameters were also elevated in healthy mothers of autistic children, with no difference from the values in the group of autistic children. The control group of healthy women of reproductive age, who had no children with autism, differed by the DNA comet tail moment from the group of mothers of autistic children, but did not differ significantly from the control group of healthy children. The results suggest that there are genotoxic factors in mentally healthy mothers of autistic children, which can determine the pathological process in the foeti via environmental "maternal effect" during gestation.

Postsacral vertebral morphology in relation to tail length among primates and other mammals.

PubMed

Russo, Gabrielle A

2015-02-01

Tail reduction/loss independently evolved in a number of mammalian lineages, including hominoid primates. One prerequisite to appropriately contextualizing its occurrence and understanding its significance is the ability to track evolutionary changes in tail length throughout the fossil record. However, to date, the bony correlates of tail length variation among living taxa have not been comprehensively examined. This study quantifies postsacral vertebral morphology among living primates and other mammals known to differ in relative tail length (RTL). Linear and angular measurements with known biomechanical significance were collected on the first, mid-, and transition proximal postsacral vertebrae, and their relationship with RTL was assessed using phylogenetic generalized least-squares regression methods. Compared to shorter-tailed primates, longer-tailed primates possess a greater number of postsacral vertebral features associated with increased proximal tail flexibility (e.g., craniocaudally longer vertebral bodies), increased intervertebral body joint range of motion (e.g., more circularly shaped cranial articular surfaces), and increased leverage of tail musculature (e.g., longer spinous processes). These observations are corroborated by the comparative mammalian sample, which shows that distantly related short-tailed (e.g., Phascolarctos, Lynx) and long-tailed (e.g., Dendrolagus, Acinonyx) nonprimate mammals morphologically converge with short-tailed (e.g., Macaca tonkeana) and long-tailed (e.g., Macaca fascicularis) primates, respectively. Multivariate models demonstrate that the variables examined account for 70% (all mammals) to 94% (only primates) of the variance in RTL. Results of this study may be used to infer the tail lengths of extinct primates and other mammals, thereby improving our understanding about the evolution of tail reduction/loss. © 2014 Wiley Periodicals, Inc.

Polyadenylation state microarray (PASTA) analysis.

PubMed

Beilharz, Traude H; Preiss, Thomas

2011-01-01

Nearly all eukaryotic mRNAs terminate in a poly(A) tail that serves important roles in mRNA utilization. In the cytoplasm, the poly(A) tail promotes both mRNA stability and translation, and these functions are frequently regulated through changes in tail length. To identify the scope of poly(A) tail length control in a transcriptome, we developed the polyadenylation state microarray (PASTA) method. It involves the purification of mRNA based on poly(A) tail length using thermal elution from poly(U) sepharose, followed by microarray analysis of the resulting fractions. In this chapter we detail our PASTA approach and describe some methods for bulk and mRNA-specific poly(A) tail length measurements of use to monitor the procedure and independently verify the microarray data.

Initial speed of knots in the plasma tail of C/2013 R1(Lovejoy)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yagi, Masafumi; Furusho, Reiko; Terai, Tsuyoshi

We report short-time variations in the plasma tail of C/2013 R1(Lovejoy). A series of short (2–3 minutes) exposure images with the 8.2 m Subaru telescope shows faint details of filaments and their motions over a 24 minute observing duration. We identified rapid movements of two knots in the plasma tail near the nucleus (∼3×10{sup 5} km). Their speeds are 20 and 25 km s{sup −1} along the tail and 3.8 and 2.2 km s{sup −1} across it, respectively. These measurements set a constraint on an acceleration model of plasma tail and knots as they set the initial speed just aftermore » their formation. We also found a rapid narrowing of the tail. After correcting the motion along the tail, the narrowing speed is estimated to be ∼8 km s{sup −1}. These rapid motions suggest the need for high time-resolution studies of comet plasma tails with a large telescope.« less

Biomonitoring of Toxic Effects of Pesticides in Occupationally Exposed Individuals.

PubMed

Arshad, Muhammad; Siddiqa, Maryam; Rashid, Saddaf; Hashmi, Imran; Awan, Muhammad Ali; Ali, Muhammad Arif

2016-06-01

Workers in pesticide manufacturing industries are constantly exposed to pesticides. Genetic biomonitoring provides an early identification of potential cancer and genetic diseases in exposed populations. The objectives of this biomonitoring study were to assess DNA damage through comet assay in blood samples collected from industry workers and compare these results with those of classical analytical techniques used for complete blood count analysis. Samples from controls (n = 20) and exposed workers (n = 38) from an industrial area in Multan, Pakistan, were subjected to various tests. Malathion residues in blood samples were measured by gas chromatography. The exposed workers who were employed in the pesticide manufacturing industry for a longer period (i.e., 13-25 years) had significantly higher DNA tail length (7.04 μm) than the controls (0.94 μm). Workers in the exposed group also had higher white blood cell and red blood cell counts, and lower levels of mean corpuscular hemoglobin (MCH), MCH concentration, and mean corpuscular volume in comparison with normal levels for these parameters. Malathion was not detected in the control group. However, in the exposed group, 72% of whole blood samples had malathion with a mean value of 0.14 mg/L (range 0.01-0.31 mg/L). We found a strong correlation (R (2) = 0.91) between DNA damage in terms of tail length and malathion concentration in blood. Intensive efforts and trainings are thus required to build awareness about safety practices and to change industrial workers' attitude to prevent harmful environmental and anthropogenic effects.

The Comet Giacobini-Zinner magnetotail: Axial stresses and inferred near-nucleus properties

NASA Technical Reports Server (NTRS)

Mccomas, D. J.; Gosling, J. T.; Bame, S. J.; Slavin, J. A.; Smith, E. J.; Steinberg, J. L.

1986-01-01

Utilizing the electron and magnetic field data from the ICE tail traversal of comet Giacobini-Zinner along with the MHD equations, a steady state, stress balance model of the cometary magnetotail was developed, and used to infer important but unmeasured ion properties within the magnetotail at ICE and upstream at the average point along each streamline where cometary ions are picked-up. The derived tailward ion flow speed at ICE is quite constant at approx. -20 to -30 km/sec across the entire tail. The flow velocity, ion temperature, density, and ion source rates upstream from the lobes (current sheet) at the average pick-up locations are approx. -75 km/sec (approx. -12), approx. 4 million K (approx. 100,000), approx. 20 cc (approx. 400), and approx. 15 cu cm/sec. Gradients in the plasma properties between the two regions are quite strong. Implications of inferred plasma properties for the near-nucleus region and for cometary magnetotail formation are examined.

Ion abundances and implications for photochemistry in Comets Halley (1986 III) and Bradfield (1987 XXIX)

NASA Astrophysics Data System (ADS)

Lutz, B. L.; Womack, M.; Wagner, R. M.

1993-04-01

The Ohio State University Image Dissector Scanner on the Perkins 1.8-m telescope at the Lowell Observatory was used to record spectra of the plasma tails of Comets P/Halley (1986 III) and P/Bradfield (1987 XXIX, also 1987s). The ionic species CO(+), N2(+), CH(+), and H2O(+) were identified in these spectra, and column densities for them were calculated from measured fluxes. The observed N2(+)/H2O(+) ratios are at least an order of magnitude lower and the observed CH(+)/H2O(+) ratios are a factor of 100 higher than theoretical results. The abundance ratio N2/CO was derived in the plasma tail of Bradfield from N2(+) and CO(+) data, and found to be an order of magnitude higher than a value measured in Halley. The relative ion abundances of CH(+), N2(+), CO(+), and H2O(+) in Halley are consistent with in situ measurements obtained from the Giotto spacecraft.

Application of MCM image construction to IRAS comet observations

NASA Technical Reports Server (NTRS)

Schlapfer, Martin F.; Walker, Russell G.

1994-01-01

There is a wealth of IRAS comet data, obtained in both the survey and pointed observations modes. However, these measurements have remained largely untouched due to difficulties in removing instrumental effects from the data. We have developed a version of the Maximum Correlation Method for Image Construction algorithm (MCM) which operates in the moving coordinate system of the comet and properly treats both real cometary motion and apparent motion due to spacecraft parallax. This algorithm has been implemented on a 486/33 PC in FORTRAN and IDL codes. Preprocessing of the IRAS CRDD includes baseline removal, deglitching, and removal of long tails due to dielectric time constants of the detectors. The resulting images are virtually free from instrumental effects and have the highest possible spatial resolution consistent with the data sampling. We present examples of high resolution IRAS images constructed from survey observations of Comets P/Tempel 1 and P/Tempel 2, and pointed observations of IRAS-Araki-Alcock.

103P/Hartley 2: ground-based monitoring of the EPOXI flyby comet

NASA Astrophysics Data System (ADS)

Tubiana, C.; Snodgrass, C.; Vincent, J.-B.; Barrera, L.; Nowajewski, P.; Retamales, G.; Lister, T.; Boehnhardt, H.

2011-10-01

Comet 103P/Hartley 2 was the fly-by target of the NASA EPOXI mission. Observations of this comet during its previous perihelion passage [1] and in 2008 when it was in its aphelion arc [2, 3] revealed a small and very active nucleus. We observed 103P from March 2010 to January 2011 using the 4m SOAR telescope located at Cerro Pachon, Chile. We took images in UBVRI filters using the SOAR Optical Imager (SOI). In addition, we made use of the large collection of (mostly BVR) images taken of the comet by school pupils using the two robotic 2m Faulkes Telescopes, which cover the same period. At the time of the observations, the comet was moving from 2.8 AU pre-perihelion to 1.6 AU post-perihelion heliocentric distance, when the comet was expected to display the most activity. The main purpose of our observations was the characterization of the activity of comet 103P and its evolution along the perihelion arc. We searched for the presence of dust coma structures and their evolution with changing heliocentric distance and determined gas and dust production rates, the dust color and the variation in these quantities as the comet passed perihelion. While no coma structures were detected between March and July 2010, a clear anisotropy in the coma in the anti-tail direction was detected in images obtained in November 2011 (Fig. 1). At the same place, the Laplace filter detects what might be a jet.

Telling tails: selective pressures acting on investment in lizard tails.

PubMed

Fleming, Patricia A; Valentine, Leonie E; Bateman, Philip W

2013-01-01

Caudal autotomy is a common defense mechanism in lizards, where the animal may lose part or all of its tail to escape entrapment. Lizards show an immense variety in the degree of investment in a tail (i.e., length) across species, with tails of some species up to three or four times body length (snout-vent length [SVL]). Additionally, body size and form also vary dramatically, including variation in leg development and robustness and length of the body and tail. Autotomy is therefore likely to have fundamentally different effects on the overall body form and function in different species, which may be reflected directly in the incidence of lost/regenerating tails within populations or, over a longer period, in terms of relative tail length for different species. We recorded data (literature, museum specimens, field data) for relative tail length (n=350 species) and the incidence of lost/regenerating tails (n=246 species). We compared these (taking phylogeny into account) with intrinsic factors that have been proposed to influence selective pressures acting on caudal autotomy, including body form (robustness, body length, leg development, and tail specialization) and ecology (foraging behavior, physical and temporal niches), in an attempt to identify patterns that might reflect adaptive responses to these different factors. More gracile species have relatively longer tails (all 350 spp., P < 0.001; also significant for five of the six families tested separately), as do longer (all species, P < 0.001; Iguanidae, P < 0.05; Lacertidae, P < 0.001; Scindidae, P < 0.001), climbing (all species, P < 0.05), and diurnal (all species, P < 0.01; Pygopodidae, P < 0.01) species; geckos without specialized tails (P < 0.05); or active-foraging skinks (P < 0.05). We also found some relationships with the data for caudal autotomy, with more lost/regenerating tails for nocturnal lizards (all 246 spp., P < 0.01; Scindidae, P < 0.05), larger skinks (P < 0.05), climbing geckos (P < 0.05), or active-foraging iguanids (P < 0.05). The selective advantage of investing in a relatively longer tail may be due to locomotor mechanics, although the patterns observed are also largely consistent with predictions based on predation pressure.

A Tale of Two Comets: ISON

NASA Image and Video Library

2013-11-26

Release Date: November 25, 2013 MESSENGER image of comet C/2012 S1 (ISON) during its closest approach to Mercury. At that time, ISON was approximately 22.5 million miles (36.2 million kilometers) from MESSENGER and 42.1 million miles (67.8 million kilometers) from the Sun. The image is 7° by 4.7° in size and has been slightly magnified and smoothed to enhance the faint tail of the comet. The tail was oriented at an angle to MESSENGER at the time and is foreshortened in this image; however, some faint structure can still be seen. MESSENGER's cameras have been acquiring targeted observations (watch an animation here) of Encke since October 28 and ISON since October 26, although the first faint detections didn't come until early November. During the closest approach of each comet to Mercury, the Mercury Atmospheric and Surface Composition Spectrometer (MASCS) and X-Ray Spectrometer (XRS) instruments also targeted the comets. Observations of ISON conclude on November 26, when the comet passes too close to the Sun, but MESSENGER will continue to monitor Encke with both the imagers and spectrometers through early December. Read this mission news story for more details. The MESSENGER spacecraft is the first ever to orbit the planet Mercury, and the spacecraft's seven scientific instruments and radio science investigation are unraveling the history and evolution of the Solar System's innermost planet. During the first two years of orbital operations, MESSENGER acquired over 150,000 images and extensive other data sets. MESSENGER is capable of continuing orbital operations until early 2015. Date acquired: 01:54:30 UTC on November 20, 2013 Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS) Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington/Southwest Research Institute NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

In vivo Comet assay--statistical analysis and power calculations of mice testicular cells.

PubMed

Hansen, Merete Kjær; Sharma, Anoop Kumar; Dybdahl, Marianne; Boberg, Julie; Kulahci, Murat

2014-11-01

The in vivo Comet assay is a sensitive method for evaluating DNA damage. A recurrent concern is how to analyze the data appropriately and efficiently. A popular approach is to summarize the raw data into a summary statistic prior to the statistical analysis. However, consensus on which summary statistic to use has yet to be reached. Another important consideration concerns the assessment of proper sample sizes in the design of Comet assay studies. This study aims to identify a statistic suitably summarizing the % tail DNA of mice testicular samples in Comet assay studies. A second aim is to provide curves for this statistic outlining the number of animals and gels to use. The current study was based on 11 compounds administered via oral gavage in three doses to male mice: CAS no. 110-26-9, CAS no. 512-56-1, CAS no. 111873-33-7, CAS no. 79-94-7, CAS no. 115-96-8, CAS no. 598-55-0, CAS no. 636-97-5, CAS no. 85-28-9, CAS no. 13674-87-8, CAS no. 43100-38-5 and CAS no. 60965-26-6. Testicular cells were examined using the alkaline version of the Comet assay and the DNA damage was quantified as % tail DNA using a fully automatic scoring system. From the raw data 23 summary statistics were examined. A linear mixed-effects model was fitted to the summarized data and the estimated variance components were used to generate power curves as a function of sample size. The statistic that most appropriately summarized the within-sample distributions was the median of the log-transformed data, as it most consistently conformed to the assumptions of the statistical model. Power curves for 1.5-, 2-, and 2.5-fold changes of the highest dose group compared to the control group when 50 and 100 cells were scored per gel are provided to aid in the design of future Comet assay studies on testicular cells. Copyright © 2014 Elsevier B.V. All rights reserved.

Evaluation of genome damage in subjects occupationally exposed to possible carcinogens.

PubMed

Zeljezic, Davor; Mladinic, Marin; Kopjar, Nevenka; Radulovic, Azra Hursidic

2016-09-01

In occupational exposures, populations are simultaneously exposed to a mixture of chemicals. We aimed to evaluate DNA damage due to possible carcinogen exposure (phenylhydrazine, ethylene oxide, dichloromethane, and 1,2-dichloroethane) in lymphocytes of pharmaceutical industry workers from the same production line. Population comprised 16 subjects (9 females and 7 males) who were exposed to multiple chemicals for 8 months. Genome damage was assessed using alkaline comet assay, micronucleus assay, and comet assay coupled with fluorescent in situ hybridization (comet-FISH). After 8 months of exposure, the issue of irregular use of all available personal protective equipment (PPE) came into light. To decrease the risk of exposure, strict use of PPE was enforced. After 8 months of strict PPE use, micronuclei frequency and comet assay parameters in lymphocytes of pharmaceutical workers significantly decreased compared with prior period of irregular PPE use. Comet-FISH results indicated a significant shift in distribution of signals for the TP 53 gene toward a more frequent occurrence in the comet tail. Prolonged exposure to possible carcinogens may hinder DNA repair mechanisms and affect structural integrity of TP 53 Two indicators of loss of TP 53 gene integrity have risen, namely, TP 53 fragmentation rate in lymphocytes with persistently elevated primary damage and incidence of TP 53 deletions in undamaged lymphocytes. © The Author(s) 2015.

Toxicity assessment of sodium fluoride in Drosophila melanogaster after chronic sub-lethal exposure.

PubMed

Dutta, Moumita; Rajak, Prem; Khatun, Salma; Roy, Sumedha

2017-01-01

Sodium fluoride (NaF), one of the most frequently used fluoride compound is composed of Na + and F - . Apart from its use in water fluoridation, NaF also acts as a major component for different dental products like toothpastes, gels and mouth rinses etc. The present study was carried out to explore the toxic impact of chronic NaF exposure on a non-target organism, Drosophila melanogaster. The larvae exposed to different concentrations of NaF through food showed a significant increase in HSP70 expression both qualitatively and quantitatively. The altered tail length and tail intensity in Comet assay validate the increased DNA damage in treated larvae. The activity of AChE, oxidative stress marker enzymes, phase I and phase II detoxifying enzymes were found to be significantly inhibited in the treated larvae when compared to control though there was no evidence of dose dependent change in each case. The alterations in the mentioned parameters can be due to increased body Fluoride ion (F - ) concentration since the analysis with ion electrode analyzer revealed that F - concentration increased significantly with NaF treatment. Hence, the results suggest that D. melanogaster manifest prominent toxic response when subjected to chronic exposure to sub-lethal NaF concentrations. Copyright © 2016 Elsevier Ltd. All rights reserved.

Experimental Investigation of the Effect of Vertical-tail Size and Length and of Fuselage Shape and Length on the Static Lateral Stability Characteristics of a Model with 45 Degree Sweptback Wing and Tail Surfaces

NASA Technical Reports Server (NTRS)

Queijo, M J; Wolhart, Walter D

1951-01-01

An investigation was made to determine the effects of vertical-tail size and length and of fuselage shape and length on the static lateral stability characteristics of a model with wing and vertical tails having the quarter-chord lines swept back 45 degrees. The results indicate that the directional instability of the various isolated fuselages was about two-thirds as large as that predicted by classical theory.

Comet ISON Streaks Toward the Sun

NASA Image and Video Library

2013-11-22

Date: 19 Nov 2013 Comet ISON shows off its tail in this three-minute exposure taken on 19 Nov. 2013 at 6:10 a.m. EST, using a 14-inch telescope located at the Marshall Space Flight Center. The comet is just nine days away from its close encounter with the sun; hopefully it will survive to put on a nice show during the first week of December. The star images are trailed because the telescope is tracking on the comet, which is now exhibiting obvious motion with respect to the background stars over a period of minutes. At the time of this image, Comet ISON was some 44 million miles from the sun -- and 80 million miles from Earth -- moving at a speed of 136,700 miles per hour. Credit: NASA/MSFC/Aaron Kingery -------- More details on Comet ISON: Comet ISON began its trip from the Oort cloud region of our solar system and is now travelling toward the sun. The comet will reach its closest approach to the sun on Thanksgiving Day -- 28 Nov 2013 -- skimming just 730,000 miles above the sun's surface. If it comes around the sun without breaking up, the comet will be visible in the Northern Hemisphere with the naked eye, and from what we see now, ISON is predicted to be a particularly bright and beautiful comet. Catalogued as C/2012 S1, Comet ISON was first spotted 585 million miles away in September 2012. This is ISON's very first trip around the sun, which means it is still made of pristine matter from the earliest days of the solar system’s formation, its top layers never having been lost by a trip near the sun. Comet ISON is, like all comets, a dirty snowball made up of dust and frozen gases like water, ammonia, methane and carbon dioxide -- some of the fundamental building blocks that scientists believe led to the formation of the planets 4.5 billion years ago. NASA has been using a vast fleet of spacecraft, instruments, and space- and Earth-based telescope, in order to learn more about this time capsule from when the solar system first formed. The journey along the way for such a sun-grazing comet can be dangerous. A giant ejection of solar material from the sun could rip its tail off. Before it reaches Mars -- at some 230 million miles away from the sun -- the radiation of the sun begins to boil its water, the first step toward breaking apart. And, if it survives all this, the intense radiation and pressure as it flies near the surface of the sun could destroy it altogether. This collection of images show ISON throughout that journey, as scientists watched to see whether the comet would break up or remain intact. The comet reaches its closest approach to the sun on Thanksgiving Day -- Nov. 28, 2013 -- skimming just 730,000 miles above the sun’s surface. If it comes around the sun without breaking up, the comet will be visible in the Northern Hemisphere with the naked eye, and from what we see now, ISON is predicted to be a particularly bright and beautiful comet. ISON stands for International Scientific Optical Network, a group of observatories in ten countries who have organized to detect, monitor, and track objects in space. ISON is managed by the Keldysh Institute of Applied Mathematics, part of the Russian Academy of Sciences. NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Fluctuating asymmetry in great tit nestlings in relation to diet quality, calcium availability and pollution exposure.

PubMed

Sillanpää, Saila; Salminen, Juha-Pekka; Eeva, Tapio

2010-07-15

Stress during development may cause fluctuating asymmetry (FA), i.e. non-directional and random deviations from perfect symmetry in otherwise symmetrical morphological traits. These deviations affect the phenotypic quality of an individual. We manipulated the diet of nestling great tits, Parus major, to investigate how food quality and quantity affect FA in the length and mass of the outermost tail feathers of great tit nestlings in a polluted and an unpolluted area. High carotenoid diet groups and the control group had higher FA in tail feather length compared to a mealworm-supplemented (low carotenoid) group. This suggests that high carotenoid content in the diet may either directly or indirectly induce higher FA in tail feather length. Calcium is an essential element for birds and important component of feathers. The less calcium there was in the diet, the higher was the FA in tail feather length, which suggests that calcium availability may be an important determinant of the developmental stability of tail feather length. In the control group, in which nestlings were fully dependent upon natural food resources provided by their parents, FA in feather mass was higher in polluted than in unpolluted sites. Diet quality and quantity seemed to differentially affect FA in tail feather length and mass between the polluted and the unpolluted areas. FA in tail feather length in the control group was unaltered by pollution, while FA in tail feather mass was lower in the control group in the unpolluted than in the polluted area. Our study also demonstrates for the first time that the developmental stability of tail feather length and mass are affected by different factors. Copyright 2010 Elsevier B.V. All rights reserved.

Trajectory analysis for the nucleus and dust of comet C/2013 A1 (Siding Spring)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Farnocchia, Davide; Chesley, Steven R.; Chodas, Paul W.

Comet C/2013 A1 (Siding Spring) will experience a high velocity encounter with Mars on 2014 October 19 at a distance of 135,000 km ± 5000 km from the planet center. We present a comprehensive analysis of the trajectory of both the comet nucleus and the dust tail. The nucleus of C/2013 A1 cannot impact on Mars even in the case of unexpectedly large nongravitational perturbations. Furthermore, we compute the required ejection velocities for the dust grains of the tail to reach Mars as a function of particle radius and density and heliocentric distance of the ejection. A comparison between ourmore » results and the most current modeling of the ejection velocities suggests that impacts are possible only for millimeter to centimeter size particles released more than 13 AU from the Sun. However, this level of cometary activity that far from the Sun is considered extremely unlikely. The arrival time of these particles spans a 20-minute time interval centered at 2014 October 19 at 20:09 TDB, i.e., around the time that Mars crosses the orbital plane of C/2013 A1. Ejection velocities larger than currently estimated by a factor >2 would allow impacts for smaller particles ejected as close as 3 AU from the Sun. These particles would reach Mars from 19:13 TDB to 20:40 TDB.« less

Ion Acoustic Waves Observed at Comet 67P/Churyumov-Gerasimenko

NASA Astrophysics Data System (ADS)

Gunell, H.; Nilsson, H.; Hamrin, M.; Eriksson, A.; Maggiolo, R.; Pierre, H.; Altwegg, K.; Tzou, C. Y.; Rubin, M.; Glassmeier, K. H.; Stenberg Wieser, G.; Wedlund, C. S.; De Keyser, J.; Dhooghe, F.; Cessateur, G.; Gibbons, A.

2016-12-01

We present observations of ion acoustic waves at Comet 67P/Churyumov-Gerasimenko performed on 20 January 2015 when the Rosetta spacecraft was located near the terminator, 28 km from the nucleus of the comet. At the time of the observations the activity of the comet was still low. We use distribution functions obtained by the Ion Composition Analyser of the Rosetta Plasma Consortium (RPC-ICA) and electron temperature estimatesfrom the Langmuir Probes (RPC-LAP) to compute dispersion relations for waves on the ion timescale, and compare the results to spectra obtained by RPC-LAP. The peaks of the wave spectra appear at frequencies near 500 Hz. We perform cross-calibrations between RPC-ICA, RPC-LAP, and the Mutual Impedance Probe (RPC-MIP). Matching the dispersion relations to the wave observations helps us to form an estimate of the plasma density. At times when there is significant wave activity the water ion distribution is constituted by a cold (0.01 eV) population of locally produced ions and a thin tail of ions that have been accelerated by an electric field. The tail is approximately unidirectional, covering a wide velocity range, and centred at 20km/s in the spacecraft frame. At other times a warm (approximately 1 eV), mainly isotropic, ion population renders the ion acoustic mode heavily damped, and no waves are observed. Observations of the neutral density by the ROSINA COPS instrument indicate that frictional heating by the radial neutral flow contributes to this warm ion population. This work was supported by the Belgian Science Policy Office through the Solar-Terrestrial Centre of Excellence and by PRODEX/ROSETTA/ROSINA PEA 4000107705.

Spatial variations of brightness, colour and polarization of dust in comet 67P/Churyumov-Gerasimenko

NASA Astrophysics Data System (ADS)

Rosenbush, Vera K.; Ivanova, Oleksandra V.; Kiselev, Nikolai N.; Kolokolova, Ludmilla O.; Afanasiev, Viktor L.

2017-07-01

We present post-perihelion photometric and polarimetric observations of comet 67P/Churyumov-Gerasimenko performed at the 6-m telescope of the SAO RAS in the g-sdss (465/65 nm), r-sdss (620/60 nm) and R filters. Observations in November and December 2015 and April 2016 covered the range of heliocentric distance 1.62-2.72 au and phase angle 33.2°-10.4°. The comet was very active. Two persistent jets and long dust tail were observed during the whole observing period; one more jet was detected only in December. The radial profiles of surface brightness, colour and polarization significantly differed for the coma, jets and tail, and changed with increasing heliocentric distance. The dust production Afρ decreased from 162 cm at r = 1.62 au to 51 cm at r = 2.72 au. The dust colour (g-r) gradually changed from 0.8 mag in the innermost coma to about 0.4 mag in the outer coma. The spectral slope was 8.2 ± 1.7 per cent/100 nm in the 465 to 620 nm wavelength domain. In November and December, the polarization in the near-nucleus area was about 8 per cent, dropped sharply to 2 per cent at the distance above 5000 km and then gradually increased with distance from the nucleus, reaching ˜8 per cent at 40 000 km. In April, at a phase angle 10.4°, the polarization varied between -0.6 per cent in the near-nucleus area and -4 per cent in the outer coma. Circular polarization was not detected in the comet. The spatial variations of brightness, colour and polarization in different structural features suggest some evolution of particle properties, most likely decreasing the size of dust particles.

Interplanetary gas. XX - Does the radial solar wind speed increase with latitude

NASA Technical Reports Server (NTRS)

Brandt, J. C.; Harrington, R. S.; Roosen, R. G.

1975-01-01

The astrometric technique used to derive solar wind speeds from ionic comet-tail orientations has been used to test the suggestion that the radial solar wind speed is higher near the solar poles than near the equator. We find no evidence for the suggested latitude variation.

Spitzer June 13 View of ISON

NASA Image and Video Library

2013-11-22

These images from NASA's Spitzer Space Telescope of Comet ISON were taken on June 13, 2013, when ISON was about 310 million miles from the sun. The image on the left shows light in the near infrared wavelengths of 3.6 microns. It shows a tail of fine, rocky dust issuing from the comet and blown back by the pressure of sunlight as the comet speeds towards the sun. The image on the right side shows light with a wavelength of 4.5 microns. It reveals a very different round structure -- the first detection of a neutral gas atmosphere surrounding ISON. In this case, it is most likely created by carbon dioxide that is "fizzing" from the surface of the comet at a rate of about 2.2 million pounds a day. Credit: NASA/JPL-Caltech/JHUAPL/UCF -------- More details on Comet ISON: Comet ISON began its trip from the Oort cloud region of our solar system and is now travelling toward the sun. The comet will reach its closest approach to the sun on Thanksgiving Day -- 28 Nov 2013 -- skimming just 730,000 miles above the sun's surface. If it comes around the sun without breaking up, the comet will be visible in the Northern Hemisphere with the naked eye, and from what we see now, ISON is predicted to be a particularly bright and beautiful comet. Catalogued as C/2012 S1, Comet ISON was first spotted 585 million miles away in September 2012. This is ISON's very first trip around the sun, which means it is still made of pristine matter from the earliest days of the solar system’s formation, its top layers never having been lost by a trip near the sun. Comet ISON is, like all comets, a dirty snowball made up of dust and frozen gases like water, ammonia, methane and carbon dioxide -- some of the fundamental building blocks that scientists believe led to the formation of the planets 4.5 billion years ago. NASA has been using a vast fleet of spacecraft, instruments, and space- and Earth-based telescope, in order to learn more about this time capsule from when the solar system first formed. The journey along the way for such a sun-grazing comet can be dangerous. A giant ejection of solar material from the sun could rip its tail off. Before it reaches Mars -- at some 230 million miles away from the sun -- the radiation of the sun begins to boil its water, the first step toward breaking apart. And, if it survives all this, the intense radiation and pressure as it flies near the surface of the sun could destroy it altogether. This collection of images show ISON throughout that journey, as scientists watched to see whether the comet would break up or remain intact. The comet reaches its closest approach to the sun on Thanksgiving Day -- Nov. 28, 2013 -- skimming just 730,000 miles above the sun’s surface. If it comes around the sun without breaking up, the comet will be visible in the Northern Hemisphere with the naked eye, and from what we see now, ISON is predicted to be a particularly bright and beautiful comet. ISON stands for International Scientific Optical Network, a group of observatories in ten countries who have organized to detect, monitor, and track objects in space. ISON is managed by the Keldysh Institute of Applied Mathematics, part of the Russian Academy of Sciences. NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Human sperm sex chromosome disomy and sperm DNA damage assessed by the neutral comet assay.

PubMed

McAuliffe, M E; Williams, P L; Korrick, S A; Dadd, R; Marchetti, F; Martenies, S E; Perry, M J

2014-10-10

Is there an association between human sperm sex chromosome disomy and sperm DNA damage? An increase in human sperm XY disomy was associated with higher comet extent; however, there was no other consistent association of sex chromosome disomies with DNA damage. There is limited published research on the association between sex chromosome disomy and sperm DNA damage and the findings are not consistent across studies. We conducted a cross-sectional study of 190 men (25% ever smoker, 75% never smoker) from subfertile couples presenting at the Massachusetts General Hospital Fertility Clinic from January 2000 to May 2003. Multiprobe fluorescence in situ hybridization for chromosomes X, Y and 18 was used to determine XX, YY, XY and total sex chromosome disomy in sperm nuclei using an automated scoring method. The neutral comet assay was used to measure sperm DNA damage, as reflected by comet extent, percentage DNA in the comet tail, and tail distributed moment. Univariate and multiple linear regression models were constructed with sex chromosome disomy (separate models for each of the four disomic conditions) as the independent variable, and DNA damage parameters (separate models for each measure of DNA damage) as the dependent variable. Men with current or past smoking history had significantly greater comet extent (µm: regression coefficients with 95% CI) [XX18: 15.17 (1.98, 28.36); YY18: 14.68 (1.50, 27.86); XY18: 15.41 (2.37, 28.45); Total Sex Chromosome Disomy: 15.23 (2.09, 28.38)], and tail distributed moment [XX18: 3.01 (0.30, 5.72); YY18: 2.95 (0.24, 5.67); XY18: 3.04 (0.36, 5.72); Total Sex Chromosome Disomy: 3.10 (0.31, 5.71)] than men who had never smoked. In regression models adjusted for age and smoking, there was a positive association between XY disomy and comet extent. For an increase in XY disomy from 0.56 to 1.47% (representing the 25th to 75th percentile), there was a mean increase of 5.08 µm in comet extent. No other statistically significant findings were observed. A potential limitation of this study is that it is cross-sectional. Cross-sectional analyses by nature do not lend themselves to inference about directionality for any observed associations; therefore we cannot determine which variable is the cause and which one is the effect. A small sample size may be a further limitation. Comparison of these findings to other studies is limited due to methodological differences. Although consistent associations across sex chromosome disomies or DNA damage measures were not observed, this study highlights the need to explore etiologies of sperm DNA damage and sex chromosome disomy to better understand the potential mechanistic overlaps between the two. This work was supported by NIOSH Grant T42 OH008416, and NIH/NIEHS Grants ES 009718, ES 000002, and R01 ES017457. During the study M.E.M. was affiliated with the Department of Environmental Health at the Harvard School of Public Health. N/A. © The Author 2014. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Human sperm sex chromosome disomy and sperm DNA damage assessed by the neutral comet assay

PubMed Central

McAuliffe, M.E.; Williams, P.L.; Korrick, S.A.; Dadd, R.; Marchetti, F.; Martenies, S.E.; Perry, M.J.

2014-01-01

STUDY QUESTION Is there an association between human sperm sex chromosome disomy and sperm DNA damage? SUMMARY ANSWER An increase in human sperm XY disomy was associated with higher comet extent; however, there was no other consistent association of sex chromosome disomies with DNA damage. WHAT IS KNOWN ALREADY There is limited published research on the association between sex chromosome disomy and sperm DNA damage and the findings are not consistent across studies. STUDY DESIGN, SIZE, AND DURATION We conducted a cross-sectional study of 190 men (25% ever smoker, 75% never smoker) from subfertile couples presenting at the Massachusetts General Hospital Fertility Clinic from January 2000 to May 2003. PARTICIPANTS/MATERIALS, SETTING, METHODS Multiprobe fluorescence in situ hybridization for chromosomes X, Y and 18 was used to determine XX, YY, XY and total sex chromosome disomy in sperm nuclei using an automated scoring method. The neutral comet assay was used to measure sperm DNA damage, as reflected by comet extent, percentage DNA in the comet tail, and tail distributed moment. Univariate and multiple linear regression models were constructed with sex chromosome disomy (separate models for each of the four disomic conditions) as the independent variable, and DNA damage parameters (separate models for each measure of DNA damage) as the dependent variable. MAIN RESULTS AND THE ROLE OF CHANCE Men with current or past smoking history had significantly greater comet extent (µm: regression coefficients with 95% CI) [XX18: 15.17 (1.98, 28.36); YY18: 14.68 (1.50, 27.86); XY18: 15.41 (2.37, 28.45); Total Sex Chromosome Disomy: 15.23 (2.09, 28.38)], and tail distributed moment [XX18: 3.01 (0.30, 5.72); YY18: 2.95 (0.24, 5.67); XY18: 3.04 (0.36, 5.72); Total Sex Chromosome Disomy: 3.10 (0.31, 5.71)] than men who had never smoked. In regression models adjusted for age and smoking, there was a positive association between XY disomy and comet extent. For an increase in XY disomy from 0.56 to 1.47% (representing the 25th to 75th percentile), there was a mean increase of 5.08 µm in comet extent. No other statistically significant findings were observed. LIMITATIONS, REASONS FOR CAUTION A potential limitation of this study is that it is cross-sectional. Cross-sectional analyses by nature do not lend themselves to inference about directionality for any observed associations; therefore we cannot determine which variable is the cause and which one is the effect. A small sample size may be a further limitation. Comparison of these findings to other studies is limited due to methodological differences. WIDER IMPLICATIONS OF THE FINDINGS Although consistent associations across sex chromosome disomies or DNA damage measures were not observed, this study highlights the need to explore etiologies of sperm DNA damage and sex chromosome disomy to better understand the potential mechanistic overlaps between the two. STUDY FUNDING/COMPETING INTEREST(S) This work was supported by NIOSH Grant T42 OH008416, and NIH/NIEHS Grants ES 009718, ES 000002, and R01 ES017457. During the study M.E.M. was affiliated with the Department of Environmental Health at the Harvard School of Public Health. TRIAL REGISTRATION NUMBER N/A. PMID:25069502

Will comet 209P/LINEAR generate the next meteor storm?

NASA Astrophysics Data System (ADS)

Ye, Quanzhi; Wiegert, Paul A.

2014-02-01

Previous studies have suggested that comet 209P/LINEAR may produce strong meteor activity on Earth on 2014 May 24; however, exact timing and activity level is difficult to estimate due to the limited physical observations of the comet. Here, we reanalyse the optical observations of 209P/LINEAR obtained during its 2009 apparition. We find that the comet is relatively depleted in dust production, with Afρ at 1 cm level within eight months around its perihelion. This feature suggested that this comet may be currently transitioning from a typical comet to a dormant comet. Syndyne simulation shows that the optical cometary tail is dominated by larger particles with β ˜ 0.003. Numerical simulations of the cometary dust trails confirm the arrival of particles on 2014 May 24 from some of the 1798-1979 trails. The nominal radiant is at RA 122° ± 1°, Dec. 79° ± 1° (J2000) in the constellation of Camelopardalis. Given that the comet is found to be depleted in dust production, we concluded that a meteor storm (ZHR ≥ 1000) may be unlikely. However, our simulation also shows that the size distribution of the arrived particles is skewed strongly to larger particles. Coupling with the result of syndyne simulation, we think that the event, if detectable, may be dominated by bright meteors. We encourage observers to monitor the expected meteor event as it will provide us with rare direct information on the dynamical history of 209P/LINEAR which is otherwise irretrievably lost.

The end states of long-period comets and the origin of Halley-type comets

NASA Astrophysics Data System (ADS)

Fernández, Julio A.; Gallardo, Tabaré; Young, Juan D.

2016-09-01

We analyse a sample of 73 old long-period comets (LPCs) (orbital periods 200 < P < 1000 yr) with perihelion distances q < 2.5 au, discovered in the period 1850-2014. We cloned the observed comets and also added fictitious LPCs with perihelia in the Jupiter's zone. We consider both a purely dynamical evolution and a physico-dynamical one with different physical lifetimes. We can fit the computed energy distribution of comets with q < 1.3 au to the observed one only within the energy range 0.01 < x < 0.04 au-1 (or periods 125 < P < 1000 yr), where the `energy' is taken as the inverse of the semimajor axis a, namely x ≡ 1/a. The best results are obtained for physical lifetimes of about 200-300 revolutions (for a comet with a standard q = 1 au). We find that neither a purely dynamical evolution, nor a physico-dynamical one can reproduce the long tail of larger binding energies (x ≳ 0.04 au-1) that correspond to most Halley-type comets (HTCs) and Jupiter-family comets. We conclude that most HTCs are not the end states of the evolution of LPCs, but come from a different source, a flattened one that we identify with the Centaurs that are scattered to the inner planetary region from the trans-Neptunian belt. These results also show that the boundary between LPCs and HTCs should be located at an energy x ˜ 0.04 au-1 (P ˜ 125 yr), rather than the conventional classical boundary at P = 200 yr.

The Gas Production Rate and Coma Structure of Comet C/1995 O1 (Hale-Bopp)

NASA Astrophysics Data System (ADS)

Morgenthaler, Jeffrey P.; Harris, Walter M.; Roesler, Frederick L.; Scherb, Frank; Anderson, Christopher M.; Doane, Nathaniel E.; Oliversen, Ronald J.

2002-06-01

The University of Wisconsin-Madison and NASA-Goddard conducted acomprehensive multi-wavelength observing campaign of coma emissionsfrom comet Hale-Bopp, including OH 3080 Å, [O I] 6300 Å H2O+ 6158 Å, H Balmer-α 6563 Å, NH2 6330 Å, [C I] 9850 ÅCN 3879 Å, C2 5141 Å, C3 4062 Å,C I 1657 Å, and the UV and optical continua. In thiswork, we concentrate on the results of the H2O daughter studies.Our wide-field OH 3080 Å measured flux agrees with other, similarobservations and the expected value calculated from published waterproduction rates using standard H2O and OH photochemistry.However, the total [O I] 6300 Å flux determined spectroscopically overa similar field-of-view was a factor of 3-4 higher than expected.Narrow-band [O I] images show this excess came from beyond theH2O scale length, suggesting either a previously unknown source of[O I] or an error in the standard OH + ν→ O(1 D) + H branching ratio. The Hale-Bopp OH and[O I] distributions, both of which were imaged tocometocentric distances >1 × 106 km, were more spatiallyextended than those of comet Halley (after correcting for brightnessdifferences), suggesting a higher bulk outflow velocity. Evidence ofthe driving mechanism for this outflow is found in the Hα lineprofile, which was narrower than in comet Halley (though likelybecause of opacity effects, not as narrow as predicted by Monte-Carlomodels). This is consistent with greater collisional coupling betweenthe suprathermal H photodissociation products and Hale-Bopp's densecoma. Presumably because of mass loading of the solar wind by ionsand ions by the neutrals, the measured acceleration of H2O+ downthe ion tail was much smaller than in comet Halley. Tailwardextensions in the azimuthal distributions of OH 3080 Å,[O I], and [C I] , as well as a Doppler asymmetry in the[O I] line profile, suggest ion-neutral coupling. While thetailward extension in the OH can be explained by increased neutralacceleration, the [O I] 6300 Å and [C I] 9850 Å emissions show 13%and >200% excesses in this direction (respectively), suggesting anon-negligible contribution from dissociative recombination of CO+and/or electron collisional excitation. Thus, models including theeffects of photo- and collisional chemistry are necessary for the fullinterpretation of these data.

Sperm DNA damage output parameters measured by the alkaline Comet assay and their importance.

PubMed

Simon, L; Aston, K I; Emery, B R; Hotaling, J; Carrell, D T

2017-03-01

The alkaline Comet assay has shown high diagnostic value to determine male reproductive health and prognostic ability to predict ART success. Here, spermatozoon was analysed in 47 fertile donors and 238 patients, including 132 couples undergoing ART [semen was collected: Group I - within 3 months of their treatment (n = 79); and Group II - 3 months prior to their treatment (n = 53)]. We introduce four Comet distribution plots (A, B1, B2 and C) by plotting the level of DNA damage (x-axis) and percentage of comets (y-axis). Fertile donors had low mean DNA damage, olive tail moment and per cent of spermatozoa with damage and increased type A plots. Comet parameters were associated with clinical pregnancies in Group I. About 66% of couples with type A distribution plot were successful after ART, whereas couples with type B1, B2 and C distribution plots achieved 56%, 44% and 33% pregnancies respectively. The efficiency of the Comet assay was due to complete decondensation process, where the compact sperm nuclear DNA (28.2 ± 0.2 μm 3 ) is decondensed to ~63 μm 3 (before lysis) and ~1018 μm 3 (after lysis). A combinational analysis of all the Comet output parameters may provide a comprehensive evaluation of patient's reproductive health as these parameters measure different aspects of DNA damage within the spermatozoa. © 2016 Blackwell Verlag GmbH.

April 10 View of ISON

NASA Image and Video Library

2013-11-22

This NASA Hubble Space Telescope image of Comet (C/2012 S1) ISON was photographed on April 10, 2013, when the comet was slightly closer than Jupiter's orbit at a distance of 394 million miles from Earth. Even at that great distance the comet is already active as sunlight warms the surface and causes frozen volatiles to boil off. Astronomers used such early images to try to measure the size of the nucleus, in order to predict whether the comet would stay intact when it slingshots around the sun -- at 700,000 miles above the sun's surface -- on Nov. 28, 2013. The comet's dusty coma, or head of the comet, is approximately 3,100 miles across, or 1.2 times the width of Australia. A dust tail extends more than 57,000 miles, far beyond Hubble's field of view. This image was taken in visible light. The blue false color was added to bring out details in the comet structure. Credit: NASA/ ESA/STScI/AURA -------- More details on Comet ISON: Comet ISON began its trip from the Oort cloud region of our solar system and is now travelling toward the sun. The comet will reach its closest approach to the sun on Thanksgiving Day -- 28 Nov 2013 -- skimming just 730,000 miles above the sun's surface. If it comes around the sun without breaking up, the comet will be visible in the Northern Hemisphere with the naked eye, and from what we see now, ISON is predicted to be a particularly bright and beautiful comet. Catalogued as C/2012 S1, Comet ISON was first spotted 585 million miles away in September 2012. This is ISON's very first trip around the sun, which means it is still made of pristine matter from the earliest days of the solar system’s formation, its top layers never having been lost by a trip near the sun. Comet ISON is, like all comets, a dirty snowball made up of dust and frozen gases like water, ammonia, methane and carbon dioxide -- some of the fundamental building blocks that scientists believe led to the formation of the planets 4.5 billion years ago. NASA has been using a vast fleet of spacecraft, instruments, and space- and Earth-based telescope, in order to learn more about this time capsule from when the solar system first formed. The journey along the way for such a sun-grazing comet can be dangerous. A giant ejection of solar material from the sun could rip its tail off. Before it reaches Mars -- at some 230 million miles away from the sun -- the radiation of the sun begins to boil its water, the first step toward breaking apart. And, if it survives all this, the intense radiation and pressure as it flies near the surface of the sun could destroy it altogether. This collection of images show ISON throughout that journey, as scientists watched to see whether the comet would break up or remain intact. The comet reaches its closest approach to the sun on Thanksgiving Day -- Nov. 28, 2013 -- skimming just 730,000 miles above the sun’s surface. If it comes around the sun without breaking up, the comet will be visible in the Northern Hemisphere with the naked eye, and from what we see now, ISON is predicted to be a particularly bright and beautiful comet. ISON stands for International Scientific Optical Network, a group of observatories in ten countries who have organized to detect, monitor, and track objects in space. ISON is managed by the Keldysh Institute of Applied Mathematics, part of the Russian Academy of Sciences. NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on April 10 Hubble View of ISON

NASA Image and Video Library

2013-11-22

This NASA Hubble Space Telescope image of Comet (C/2012 S1) ISON was photographed on April 10, 2013, when the comet was slightly closer than Jupiter's orbit at a distance of 394 million miles from Earth. Even at that great distance the comet is already active as sunlight warms the surface and causes frozen volatiles to boil off. Astronomers used such early images to try to measure the size of the nucleus, in order to predict whether the comet would stay intact when it slingshots around the sun -- at 700,000 miles above the sun's surface -- on Nov. 28, 2013. The comet's dusty coma, or head of the comet, is approximately 3,100 miles across, or 1.2 times the width of Australia. A dust tail extends more than 57,000 miles, far beyond Hubble's field of view. This image was taken in visible light. The blue false color was added to bring out details in the comet structure. Credit: NASA/ ESA/STScI/AURA -------- More details on Comet ISON: Comet ISON began its trip from the Oort cloud region of our solar system and is now travelling toward the sun. The comet will reach its closest approach to the sun on Thanksgiving Day -- 28 Nov 2013 -- skimming just 730,000 miles above the sun's surface. If it comes around the sun without breaking up, the comet will be visible in the Northern Hemisphere with the naked eye, and from what we see now, ISON is predicted to be a particularly bright and beautiful comet. Catalogued as C/2012 S1, Comet ISON was first spotted 585 million miles away in September 2012. This is ISON's very first trip around the sun, which means it is still made of pristine matter from the earliest days of the solar system’s formation, its top layers never having been lost by a trip near the sun. Comet ISON is, like all comets, a dirty snowball made up of dust and frozen gases like water, ammonia, methane and carbon dioxide -- some of the fundamental building blocks that scientists believe led to the formation of the planets 4.5 billion years ago. NASA has been using a vast fleet of spacecraft, instruments, and space- and Earth-based telescope, in order to learn more about this time capsule from when the solar system first formed. The journey along the way for such a sun-grazing comet can be dangerous. A giant ejection of solar material from the sun could rip its tail off. Before it reaches Mars -- at some 230 million miles away from the sun -- the radiation of the sun begins to boil its water, the first step toward breaking apart. And, if it survives all this, the intense radiation and pressure as it flies near the surface of the sun could destroy it altogether. This collection of images show ISON throughout that journey, as scientists watched to see whether the comet would break up or remain intact. The comet reaches its closest approach to the sun on Thanksgiving Day -- Nov. 28, 2013 -- skimming just 730,000 miles above the sun’s surface. If it comes around the sun without breaking up, the comet will be visible in the Northern Hemisphere with the naked eye, and from what we see now, ISON is predicted to be a particularly bright and beautiful comet. ISON stands for International Scientific Optical Network, a group of observatories in ten countries who have organized to detect, monitor, and track objects in space. ISON is managed by the Keldysh Institute of Applied Mathematics, part of the Russian Academy of Sciences. NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Genotoxic effects of the water-soluble fraction of heavy oil in the brackish/freshwater amphipod Quadrivisio aff. lutzi (Gammaridea) as assessed using the comet assay.

PubMed

Weber, Laura; Carvalho, Ligia; Sá, Natália; Silva, Viviane; Beraldini, Nathalia; Souza, Valderes; Conceição, Moisés

2013-05-01

Amphipod crustaceans have been widely used as invertebrate models in ecotoxicology due to their importance in the food chain. However, few studies have evaluated the genotoxic effects of pollutants in this model using the comet assay. The main obstacle to using amphipods in the comet assay is the difficulty in obtaining enough blood cells from a single individual. In this study, we evaluated the genotoxic effects of the water-soluble fraction (WSF) of heavy oil on the brackish/freshwater amphipod Quadrivisio aff. lutzi, which is common in the coastal lagoons of southeastern Brazil, using hemocytes obtained from single amphipods (without pooling) after optimizing hemolymph extraction. The comet assay revealed significantly higher DNA damage levels (2- to 6-fold higher) in treated amphipods compared to untreated ones with a sublethal concentration of 17.6 % of the WSF within 72 h of treatment. Two independent experiments confirmed an "up and down" pattern of DNA damage, measured as the % of DNA contained in the tail of the comets. Elevations in DNA damage levels were observed at the 6 and 48 h time points, while very low levels of DNA damage were observed at the 24 and 72 h time points. Furthermore, the comet assay revealed gender variability in the levels of DNA damage after short-term exposure.

ACE-SWICS In Situ Plasma Composition of Fragmented Comet 73P/Schwassmann-Wachmann 3

NASA Astrophysics Data System (ADS)

Gilbert, J. A.; Lepri, S. T.; Rubin, M.; Zurbuchen, T.

2013-12-01

The interiors of comets contain some of the most pristine material in the solar system. Comet 73P/Schwassmann-Wachmann 3, discovered in 1930 with a double nucleus, is a Jupiter-family comet with a 5.34-year period. This comet split into 5 fragments in 1995 and disintegrated into nearly 70 pieces in 2006. In May and June of 2006, recently ionized cometary particles originating from some of these fragments were collected with the ACE-SWICS sensor. Due to a combination of the close proximity of the fragments passing between ACE-SWICS and the Sun, and the instrument characteristics, unique measurements regarding the charge state composition and the elemental abundances of both cometary and heliospheric plasma were made during this time. The cometary material released from some of these fragments can be identified by the concentrations of water-group pick-up ions having a mass-per-charge of 16-18 amu/e. With a focus on Helium, Carbon, and water-group ions, we present an analysis of the cometary plasma. Charge state ratios of C+/O+ fall below 0.1 during detection of comet fragment plasma, and there is a clear increase in He+ during fragment crossings. The C/O ratio and He charge states are used to provide constraints on the activity of the cometary fragments and also the spatial distribution of the extended and ionized cometary tail.

Comet Science Working Group report on the Halley Intercept Mission

NASA Technical Reports Server (NTRS)

1980-01-01

The Halley Intercept Mission is described and the scientific benefits expected from the program are defined. One characteristic of the mission is the optical navigation and resulting accurate delivery of the spacecraft to a desired point near the nucleus. This accuracy of delivery has two important implications: (1) high probability that the mass spectrometers and other in situ measurement devices will reach the cometary ionosphere and the zone of parent molecules next to the nucleus; (2) high probability that sunlit, high resolution images of Halley's nucleus will be obtained under proper lighting conditions. In addition an observatory phase is included during which high quality images of the tail and coma structure will be obtained at progressively higher spatial resolutions as the spacecraft approaches the comet. Complete measurements of the comet/solar wind interaction can be made around the time of encounter. Specific recommendations are made concerning project implementation and spacecraft requirements.

NASA's Solar Observing Fleet Watch Comet ISON's Journey Around the Sun

NASA Image and Video Library

2013-11-22

Comet ISON makes its appearance into the higher-resolution HI-1 camera on the STEREO-A spacecraft. The dark "clouds" coming from the right are density enhancements in the solar wind, causing all the ripples in comet Encke's tail. These kinds of solar wind interactions give us valuable information about solar wind conditions near the sun. Note: the STEREO-A spacecraft is currently located on the other side of the Sun, so it sees a totally different geometry to what we see from Earth. Credit: Karl Battams/NASA/STEREO/CIOC NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Comet Jacques Approaches the Sun

NASA Image and Video Library

2014-07-24

NASA's Solar TErrestrial Relations Observatory, STEREO has observed the recently discovered Comet Jacques as it passed by its nearest approach to the Sun (July 1-6, 2014). The wide field instrument on board STEREO (Ahead) showed the comet with its elongated tail being stretched and pummeled by the gusty solar wind streaming from the Sun. Also visible near the center of the image is the bright planet Venus. The Sun is just out of the field of view to the right. Comet Jacques is traveling through space at about 180,000 km per hour (110,000 mph). It may brighten enough to be seen with the naked eye. High res still here: www.flickr.com/photos/gsfc/14710024276/ Download original file: sohowww.nascom.nasa.gov/pickoftheweek/old/11jul2014/ Credit: NASA/Goddard/STEREO NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

The crash of P/Shoemaker-Levy 9 into Jupiter and its implications for comet bombardment on Earth

NASA Technical Reports Server (NTRS)

Shoemaker, E. M.; Shoemaker, C. S.

1994-01-01

Periodic Comet Shoemaker/Levy 9 will impact Jupiter in late July 1994. The comet, which broke into more than 20 telescopically detectable fragments when it passed with the Roche lobe of Jupiter on July 8, 1992, is captured in a highly eccentric orbit about Jupiter. The 21 recognized nuclei will be spread out in a train of the order 7 x 10(exp 6) km long at the time of impact, and the impacts will be spread in time over about 5 1/2 days centered on about July 21.2 UT. In addition to the train of recognized bright nuclei, the comet consists of 'wings' of unresolved bodies that are the source of a very broad composite dust tail. The linear extent of the wings is about an order of magnitude greater than that of the train of recognized discrete nuclei. Collision of the wings will be spread in time over several months. Thus the impact of P/S-L 9 with Jupiter will be an event of appreciable duration.

Comet Jacques Approaches the Sun [video

NASA Image and Video Library

2014-07-24

NASA's Solar TErrestrial RElations Observatory, STEREO has observed the recently discovered Comet Jacques as it passed by its nearest approach to the Sun (July 1-6, 2014). The wide field instrument on board STEREO (Ahead) showed the comet with its elongated tail being stretched and pummeled by the gusty solar wind streaming from the Sun. Also visible near the center of the image is the bright planet Venus. The Sun is just out of the field of view to the right. Comet Jacques is traveling through space at about 180,000 km per hour (110,000 mph). It may brighten enough to be seen with the naked eye. Video of this event here: www.flickr.com/photos/gsfc/14730658164/ Download original file: sohowww.nascom.nasa.gov/pickoftheweek/old/11jul2014/ Credit: NASA/Goddard/STEREO NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Three Dimensional Explicit Model for Cometary Tail Ions Interactions with Solar Wind

NASA Astrophysics Data System (ADS)

Al Bermani, M. J. F.; Alhamed, S. A.; Khalaf, S. Z.; Ali, H. Sh.; Selman, A. A.

2009-06-01

The different interactions between cometary tail and solar wind ions are studied in the present paper based on three-dimensional Lax explicit method. The model used in this research is based on the continuity equations describing the cometary tail-solar wind interactions. Three dimensional system was considered in this paper. Simulation of the physical system was achieved using computer code written using Matlab 7.0. The parameters studied here assumed Halley comet type and include the particle density rho, the particles velocity v, the magnetic field strength B, dynamic pressure p and internal energy E. The results of the present research showed that the interaction near the cometary nucleus is mainly affected by the new ions added to the plasma of the solar wind, which increases the average molecular weight and result in many unique characteristics of the cometary tail. These characteristics were explained in the presence of the IMF.

Comet Siding Spring Seen Next to Mars

NASA Image and Video Library

2017-12-08

This composite NASA Hubble Space Telescope Image captures the positions of comet Siding Spring and Mars in a never-before-seen close passage of a comet by the Red Planet, which happened at 2:28 p.m. EDT October 19, 2014. The comet passed by Mars at approximately 87,000 miles (about one-third of the distance between Earth and the Moon). At that time, the comet and Mars were approximately 149 million miles from Earth. The comet image shown here is a composite of Hubble exposures taken between Oct. 18, 8:06 a.m. EDT to Oct. 19, 11:17 p.m. EDT. Hubble took a separate photograph of Mars at 10:37 p.m. EDT on Oct. 18. The Mars and comet images have been added together to create a single picture to illustrate the angular separation, or distance, between the comet and Mars at closest approach. The separation is approximately 1.5 arc minutes, or one-twentieth of the angular diameter of the full Moon. The background starfield in this composite image is synthesized from ground-based telescope data provided by the Palomar Digital Sky Survey, which has been reprocessed to approximate Hubble’s resolution. The solid icy comet nucleus is too small to be resolved in the Hubble picture. The comet’s bright coma, a diffuse cloud of dust enshrouding the nucleus, and a dusty tail, are clearly visible. This is a composite image because a single exposure of the stellar background, comet Siding Spring, and Mars would be problematic. Mars is actually 10,000 times brighter than the comet, and so could not be properly exposed to show detail in the Red Planet. The comet and Mars were also moving with respect to each other and so could not be imaged simultaneously in one exposure without one of the objects being motion blurred. Hubble had to be programmed to track on the comet and Mars separately in two different observations. The images were taken with Hubble’s Wide Field Camera 3. Credit: NASA, ESA, PSI, JHU/APL, STScI/AURA Credit: NASA, ESA, PSI, JHU/APL, STScI/AURA

Delayed effects of low level acute irradiation and chronic environmental radioactive contamination on DNA lymphocytes of people living in Dolon, a settlement located in the vicinity of the Semipalatinsk nuclear test site (Kazakhstan).

PubMed

Chenal, C; Legue, F; Nourgalieva, K

2006-10-01

During 42 years several hundred nuclear tests were performed by the former USSR at the Semipalatinsk Test Site (STS, Kazakhstan), of which more than 100 were done in the atmosphere. We report here the late genetic damage of external exposure to radiation and environmental radioactive contamination in people living in Dolon, a small settlement situated in the vicinity of the STS. The comet assay was applied on DNA lymphocytes of 20 exposed women and 32 non-exposed women living at 500 km from the STS. We observed a statistically significant difference between the exposed and control groups for mean tail moment (MTM) and DNA% in the tail. The mean values of all comet assay parameters (MTM, DNA% in the tail and score) were higher in the group of women born before 1949 as compared to those born after 1950, which could reflect an effect of external irradiation in 1949 due to the most contaminating explosion. These results suggest that people exposed 50 years ago to relatively small doses of external irradiation and/or still living in an environment contaminated by small amounts of long life radionuclides, still present DNA damage which is in agreement with other cytogenetical studies performed at the same site, on the same population.

Genotoxic effects of boric acid and borax in zebrafish, Danio rerio using alkaline comet assay

PubMed Central

Gülsoy, Nagihan; Yavas, Cüneyd; Mutlu, Özal

2015-01-01

The present study is conducted to determine the potential mechanisms of Boron compounds, boric acid (BA) and borax (BX), on genotoxicity of zebrafish Danio rerio for 24, 48, 72 and 96-hours acute exposure (level:1, 4, 16, 64 mg/l BA and BX) in semi-static bioassay experiment. For that purpose, peripheral erythrocytes were drawn from caudal vein and Comet assay was applied to assess genotoxicity. Acute (96 hours) exposure and high concentrations of boric acid and borax increases % tail DNA and Olive tail moment. Genotoxicity was found for BA as concentration-dependent and BX as concentration and time dependent manner. In general, significant effects (P < 0,05) on both concentrations and exposure times were observed in experimental groups. DNA damage was highest at 96 h and 24 h for all BX and BA concentrations, respectively in peripheral blood of D. rerio. For the first time, our study demonstrates the effect of waterborne BA and BX exposure on genotoxicity at the molecular level, which may contribute to understanding the mechanism of boric acid and borax-induced genotoxicity in fish. PMID:26862320

Genotoxic effects of boric acid and borax in zebrafish, Danio rerio using alkaline comet assay.

PubMed

Gülsoy, Nagihan; Yavas, Cüneyd; Mutlu, Özal

2015-01-01

The present study is conducted to determine the potential mechanisms of Boron compounds, boric acid (BA) and borax (BX), on genotoxicity of zebrafish Danio rerio for 24, 48, 72 and 96-hours acute exposure (level:1, 4, 16, 64 mg/l BA and BX) in semi-static bioassay experiment. For that purpose, peripheral erythrocytes were drawn from caudal vein and Comet assay was applied to assess genotoxicity. Acute (96 hours) exposure and high concentrations of boric acid and borax increases % tail DNA and Olive tail moment. Genotoxicity was found for BA as concentration-dependent and BX as concentration and time dependent manner. In general, significant effects (P < 0,05) on both concentrations and exposure times were observed in experimental groups. DNA damage was highest at 96 h and 24 h for all BX and BA concentrations, respectively in peripheral blood of D. rerio. For the first time, our study demonstrates the effect of waterborne BA and BX exposure on genotoxicity at the molecular level, which may contribute to understanding the mechanism of boric acid and borax-induced genotoxicity in fish.

A radio source occultation experiment with comet Austin 1982g, with unusual results

NASA Technical Reports Server (NTRS)

De Pater, I.; Ip, W.-H.

1984-01-01

A radio source occultation by comet Austin 1982g was observed on September 15-16, 1982. A change in the apparent position of 1242 + 41 by 1.3 arcsec occurred when the source was 220,000 km away from the cometary ion tail. If this change was due to refraction by the cometary plasma, it indicates an electron density of the plasma of about 10,000/cu cm. When the radio source was on the other side of the plasma tail, at a distance of 230,000 km, the position angle of the electric vector of the radio source changed gradually over about 140 deg within two hours. This observation cannot be explained in terms of ionospheric Faraday rotation, and results from either an intrinsic change in the radio source or Faraday rotation in the cometary plasma due to a change in the direction and/or strength of the magnetic field. In the latter case, the cometary coma must have an electron density and a magnetic field strength orders of magnitude larger than current theories predict.

A Different Way to Visualize Solar Changes

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2016-07-01

This time series of SDO images of an active region shows coronal dimming as well as flares. These images can be combined into a minimum-value persistence map (bottom panel) that better reveals the entire dimming region. [Adapted from Thompson Young 2016]What if there were a better way to analyze a comets tail, the dimming of the Suns surface, or the path of material in a bright solar eruption? A recent study examines a new technique for looking at these evolving features.Mapping Evolving FeaturesSometimes interesting advances in astronomy come from simple, creative new approaches to analyzing old data. Such is the case in a new study by Barbara Thompson and Alex Young (NASA Goddard Space Flight Center), which introduces a technique called persistence mapping to better examine solar phenomena whose dynamic natures make them difficult to analyze.What is a persistence map? Suppose you have a set of N images of the same spatial region, with each image taken at a different time. To create a persistence map of these images, you would combine this set of images by retaining only the most extreme (for example, the maximum) value for each pixel, throwing away the remaining N-1 values for each pixel.Persistence mapping is especially useful for bringing out rare or intermittent phenomena features that would often be washed out if the images were combined in a sum or average instead. Thompson and Young describe three example cases where persistence mapping brings something new to the table.Top: Single SDO image of Comet Lovejoy. Center: 17 minutes of SDO images, combined in a persistence map. The structure of the tail is now clearly visible. Bottom: For comparison, the average pixel value for this sequence of images. Click for a closer look![Thompson Young 2016]A Comets TailAs Comet Lovejoy passed through the solar corona in 2011, solar physicists analyzed extreme ultraviolet images of its tail because the motion of the tail particles reveals information about the local coronal magnetic field.Past analyses have averaged or summed images of the comet in orbit to examine its tail. But a persistence map of the maximum pixel values far more clearly shows the striations within the tail that reveal the directions of the local magnetic field lines.Dimming of the SunDimming of the Suns corona near active regions tells us about the material thats evacuated during coronal mass ejections. This process can be complex: regions dim at different times, and flares sometimes hide the dimming, making it difficult to observe. But understanding the entire dimming region is necessary to infer the total mass loss and complete magnetic footprint of a gradual eruption from the Suns surface.SDO and STEREO-A images of a prominence eruption. Tracking the falling material is difficult due to the complex background. [Thompson Young 2016]Creating a persistence map of minimum pixel values achieves this and also neatly sidesteps the problem of flares hiding the dimming regions, since the bright pixels are discarded. In the authors example, a persistence map estimates 50% more mass loss for a coronal dimming event than the traditional image analysis method, and it reveals connections between dimming regions that were previously missed.An Erupting ProminenceThe authors final example is of falling prominence material after a solar eruption, seen in absorption against the bright corona. They show that you can construct a persistence map of minimum pixel values over the time the material falls (see the cover image), allowing the materials paths to be tracked despite the evolving background behind it. Tracing these trajectories provides information about the local magnetic field.Thompson and Youngs examples indicate that persistence mapping clearly provides new information in some cases of intermittent or slowly evolving solar phenomena. It will be interesting to see where else this technique can be applied!CitationB. J. Thompson and C. A. Young 2016 ApJ 825 27. doi:10.3847/0004-637X/825/1/27

Inhibitory effect of grapefruit juice on the genotoxicity induced by hydrogen peroxide in human lymphocytes.

PubMed

Razo-Aguilera, G; Baez-Reyes, R; Alvarez-González, I; Paniagua-Pérez, R; Madrigal-Bujaidar, E

2011-11-01

By means of the comet assay we demonstrated a strong effect by hydrogen peroxide (HP) and no damage by grapefruit juice (GJ) in human lymphocytes. Cells exposed to HP and treated with three concentrations of GJ (10-90 min) showed an increase of DNA damage by HP over the control level, and a decrease of such damage by GJ. With the comet assay plus formamidopyrimidine-DNA-glycosylase we found the strongest increase of DNA damage by HP over the control level, and the strongest reduction of such damage by GJ. By applying the comet/FISH method we determined 98% of the p53 gene signals in the comet head of control cells along the experiment (10-90 min), in contrast with about 90% signals in the comet tail of cells exposed to HP. Cells treated with both agents showed a significant, concentration/time dependent return of p53 signals to the head, suggesting enhancement of the gene repair. Finally, with the annexin V assay we found an increase in apoptosis and necrosis by HP, and no effect by GJ; when GJ was added to HP treated cells no modification was observed in regard to apoptosis, although a decrease of necrosis was observed. Copyright © 2011 Elsevier Ltd. All rights reserved.

Adsorption of finite semiflexible polymers and their loop and tail distributions

NASA Astrophysics Data System (ADS)

Kampmann, Tobias A.; Kierfeld, Jan

2017-07-01

We discuss the adsorption of semiflexible polymers to a planar attractive wall and focus on the questions of the adsorption threshold for polymers of finite length and their loop and tail distributions using both Monte Carlo simulations and analytical arguments. For the adsorption threshold, we find three regimes: (i) a flexible or Gaussian regime if the persistence length is smaller than the adsorption potential range, (ii) a semiflexible regime if the persistence length is larger than the potential range, and (iii) for finite polymers, a novel crossover to a rigid rod regime if the deflection length exceeds the contour length. In the flexible and semiflexible regimes, finite size corrections arise because the correlation length exceeds the contour length. In the rigid rod regime, however, it is essential how the global orientational or translational degrees of freedom are restricted by grafting or confinement. We discuss finite size corrections for polymers grafted to the adsorbing surface and for polymers confined by a second (parallel) hard wall. Based on these results, we obtain a method to analyze adsorption data for finite semiflexible polymers such as filamentous actin. For the loop and tail distributions, we find power laws with an exponential decay on length scales exceeding the correlation length. We derive and confirm the loop and tail power law exponents for flexible and semiflexible polymers. This allows us to explain that, close to the transition, semiflexible polymers have significantly smaller loops and both flexible and semiflexible polymers desorb by expanding their tail length. The tail distribution allows us to extract the free energy per length of adsorption for actin filaments from experimental data [D. Welch et al., Soft Matter 11, 7507 (2015)].

Ameliorative effects of curcumin on the spermatozoon tail length, count, motility and testosterone serum level in metronidazole-treated mice.

PubMed

Karbalay-Doust, S; Noorafshan, A

2011-01-01

Metronidazole (MTZ) is used as an antiparasitic drug. Curcumin is considered as anti-oxidant and anti-inflammatory agent. The ameliorative effects of curcumin on MTZ induced toxicity on mice spermatozoon tail length, count, motility and testosterone level were investigated. MTZ was administered in 500 and 165 (high and therapeutic doses) mg/kg/day, with and without curcumin (100 mg/kg/day). After 16 days the above parameters were assessed. Spermatozoon count and motility and serum testosterone level MTZ-treated (500 and 165) mice were reduced. In the mice treated with MTZ+curcumin these parameters decreased but in a lesser extent than the MTZ-treated animals. Mid-piece and total lengths of the spermatozoon tail in control animals were 31.6 ± 9.0 μm and 100.3 ± 15.0 μm and in the mice treated with high doses (500) of MTZ were reduced. The mid-piece and total spermatozoon tail length has been decreased in a lesser extent in the mice treated with high dose MTZ+curcumin than the mice treated with high dose MTZ (p<0.01). But the length was not changed in animals treated with therapeutic dose of MTZ. It means curcumin treated animals had ~52% and ~39% average increase in mid-piece and total lengths in comparison with the MTZ-treated (500) animals. Stereological estimation of the sperm tail length, including sampling of spermatozoa and also counting of the intersections of their tails with the stereological grids was a rapid technique and took only 5-10 minutes. It can be concluded that curcumin has an ameliorative effect on the spermatozoon, testosterone level and tail length in MTZ-treated mice.

Brownian dynamics simulation of amphiphilic block copolymers with different tail lengths, comparison with theory and comicelles.

PubMed

Hafezi, Mohammad-Javad; Sharif, Farhad

2015-11-01

Study on the effect of amphiphilic copolymers structure on their self assembly is an interesting subject, with important applications in the area of drug delivery and biological system treatments. Brownian dynamics simulations were performed to study self-assembly of the linear amphiphilic block copolymers with the same hydrophilic head, but hydrophobic tails of different lengths. Critical micelle concentration (CMC), gyration radius distribution, micelle size distribution, density profiles of micelles, shape anisotropy, and dynamics of micellization were investigated as a function of tail length. Simulation results were compared with predictions from theory and simulation for mixed systems of block copolymers with long and short hydrophobic tail, reported in our previous work. Interestingly, the equilibrium structural and dynamic parameters of pure and mixed block copolymers were similarly dependant on the intrinsic/apparent hydrophobic block length. Log (CMC) was, however; proportional to the tail length and had a different behavior compared to the mixed system. The power law scaling relation of equilibrium structural parameters for amphiphilic block copolymers predicts the same dependence for similar hydrophobic tail lengths, but the power law prediction of CMC is different, which is due to its simplifying assumptions as discussed here. Copyright © 2015 Elsevier Inc. All rights reserved.

Slight hypercalcemia is not associated with positive responses in the Comet Assay in male rat liver.

PubMed

Thiel, Anette; Hamel, Annie; Schaefer, Katrien; Cardoso, Renato; Beilstein, Paul

2017-08-01

Maintenance of physiological levels of intracellular and extracellular calcium is essential for life. Increased intracellular calcium levels are involved in cell death (apoptosis and necrosis) and are associated with positive responses in the Comet assay in vitro. In addition, high calcium and vitamin D intakes were reported to induce apoptosis in adipose tissue in obese mice and to increase DNA-migration in the Comet assay. To investigate increased serum concentration of calcium as a potential confounding factor in the regulatory Comet assay in vivo, we induced mild hypercalcemia in male Wistar rats by 3-day continuous intravenous infusion of calcium gluconate and performed the Comet assay in the liver in line with regulatory guidelines. The results of the study showed that mild increases in serum calcium concentration (up to 1.4 times above the concurrent control) and increased urinary calcium concentration (up to 27.8 times above the concurrent control) results in clinical signs like mild tremor, faster respiration rate and decreased activity in a few animals. However, under the conditions of the study, no increase in the %Tail DNA in the Comet assay and no indication of liver damage as determined by histopathological means were observed. Thus, mild increases in plasma calcium did not lead to positive results in a genotoxicity assessment by the Comet assay in the rat liver. This result is important as it confirms the reliability of this assay for regulatory evaluation of safety. Copyright © 2017 DSM Nutritional Products AG. Published by Elsevier B.V. All rights reserved.

Detection of hypoxic fractions in murine tumors by comet assay: Comparison with other techniques

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Q.; Kavanagh, M.C.; Newcombe, D.

1995-12-01

The alkaline comet assay was used to detect the hypoxic fractions of murine tumors. A total of four tumor types were tested using needle aspiration biopsies taken immediately after a radiation dose of 15 Gy. Initial studies confirmed that the normalized tail moment, a parameter reflecting single-strand DNA breaks induced by the radiation, was linearly related to radiation dose. Further, it was shown that for a mixed population (1:1) of cells irradiated under air-breathing or hypoxic conditions, the histogram of normal tail moment values obtained from analyzing 400 cells in the population had a double peak which, when fitted withmore » two Gaussian distributions, gave a good estimate of the proportion of the two subpopulations. For the four tumor types, the means of the calculated hypoxic fractions from four or five individual tumors were 0.15 {+-} 0.04 for B16F1, 0.08 {+-} 0.04 for KHT-LP1, 0.17 {+-} 0.04 for RIF-1 and 0.04 {+-} 0.01 for SCCVII. Analysis of variance showed that the hypoxic fraction in KHT-LP1 tumors is significantly lower than those of the other three tumors (P = 0.026) but that there is no significant difference in hypoxic fraction between B16F1, RIF-1 and SCCVII tumors (P = 0.574). Results from multiple samples taken from each of five RIF-1 tumors showed that the intertumor heterogeneity of hypoxic fractions was greater than that within the same tumor. The mean hypoxic fraction obtained using the comet assay for the four tumor types was compared with the hypoxic fraction determined by the clonogenic assay, or median pO{sub 2} values, or [{sup 3}H]misonidazole binding in the same tumor types. The values of hypoxic fraction obtained with the comet assay were two to four times lower than those measured by the paired survival method. Preliminary results obtained with a dose of 5 Gy were consistent with those obtained using 15 Gy. These results suggest the further development of the comet assay for clinical studies. 21 refs., 7 figs., 5 tabs.« less

PREVAILING DUST-TRANSPORT DIRECTIONS ON COMET 67P/CHURYUMOV–GERASIMENKO

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kramer, Tobias; Noack, Matthias

Dust transport and deposition behind larger boulders on the comet 67P/Churyumov–Gerasimenko (67P/C–G) have been observed by the Rosetta mission. We present a mechanism for dust-transport vectors based on a homogeneous surface activity model incorporating in detail the topography of 67P/C–G. The combination of gravitation, gas drag, and Coriolis force leads to specific dust transfer pathways, which for higher dust velocities fuel the near-nucleus coma. By distributing dust sources homogeneously across the whole cometary surface, we derive a global dust-transport map of 67P/C–G. The transport vectors are in agreement with the reported wind-tail directions in the Philae descent area.

KOI-2700b—A Planet Candidate with Dusty Effluents on a 22 hr Orbit

NASA Astrophysics Data System (ADS)

Rappaport, Saul; Barclay, Thomas; DeVore, John; Rowe, Jason; Sanchis-Ojeda, Roberto; Still, Martin

2014-03-01

Kepler planet candidate KOI-2700b (KIC 8639908b), with an orbital period of 21.84 hr, exhibits a distinctly asymmetric transit profile, likely indicative of the emission of dusty effluents, and reminiscent of KIC 1255b. The host star has T eff = 4435 K, M ~= 0.63 M ⊙, and R ~= 0.57 R ⊙, comparable to the parameters ascribed to KIC 12557548. The transit egress can be followed for ~25% of the orbital period and, if interpreted as extinction from a dusty comet-like tail, indicates a long lifetime for the dust grains of more than a day. We present a semiphysical model for the dust tail attenuation and fit for the physical parameters contained in that expression. The transit is not sufficiently deep to allow for a study of the transit-to-transit variations, as is the case for KIC 1255b however, it is clear that the transit depth is slowly monotonically decreasing by a factor of ~2 over the duration of the Kepler mission. We infer a mass-loss rate in dust from the planet of ~2 lunar masses per Gyr. The existence of a second star hosting a planet with a dusty comet-like tail would help to show that such objects may be more common and less exotic than originally thought. According to current models, only quite small planets with Mp <~ 0.03 M ⊕ are likely to release a detectable quantity of dust. Thus, any "normal-looking" transit that is inferred to arise from a rocky planet of radius greater than ~1/2 R ⊕ should not exhibit any hint of a dusty tail. Conversely, if one detects an asymmetric transit due to a dusty tail, then it will be very difficult to detect the hard body of the planet within the transit because, by necessity, the planet must be quite small (i.e., <~ 0.3 R ⊕).

Cadmium-induced cyto- and genotoxicity are organ-dependent in lettuce.

PubMed

Monteiro, Cristina; Santos, Conceição; Pinho, Sónia; Oliveira, Helena; Pedrosa, Tiago; Dias, Maria Celeste

2012-07-16

Cadmium is a priority pollutant. Its mechanisms and effects within different plant organs remain unclear. Here, cyto-genotoxicity biomarkers were evaluated in roots and leaves after Cd exposure (0, 1, 10, and 50 μM) of the model crop Lactuca sativa L. (cv. "Reine de Mai"). Overall, superoxide dismutase (SOD) and catalase (CAT) activities were stimulated in leaves, where Cd accumulation was lower in comparison to that in roots. In roots, SOD and peroxidase (POX, APX) activities were stimulated. Moreover, in both organs glutathione reductase (GR) was not affected by Cd. Overall, the H(2)O(2) content increased in both organs, while the total antioxidant capacity decreased in leaves and increased in roots with Cd concentrations. In both organs, lipid and protein oxidation rose with consequent increase of membrane permeability. Simultaneously, the comet assay showed that tail moment, tail length, and % tail DNA were maximum for 1 μM. For 10 μM, shorter tails were found suggesting induced Cd-DNA adducts that lead to DNA-DNA/DNA-protein cross-links, and/or formation of longer DNA fragments, and/or impairment of DNA repair mechanisms, while at 50 μM, nucleoids sensitivity to the technique was evident. This result was consistent with the maximum micronuclei frequency found for the 10 μM Cd dose in roots, suggesting that the surviving cells in this organ had an increase of mitotic catastrophe and that DNA repair systems for blocking cell cycle were dysfunctional. In lower Cd concentrations, root cells might have developed strategies to repair damaged DNA by blocking the cell cycle at specific checkpoints, thus avoiding mitotic catastrophe. Roots at 1 μM showed a cell cycle blockage trend at the G(2) checkpoint, while those at higher concentrations presented S phase delay. We finally discuss a general model of Cd-organ interaction covering these cyto- and genotoxic effects and the potential use of this cultivar in phytoremediation strategies.

Catching the Tail of the Comet: Technology in the Classroom

ERIC Educational Resources Information Center

Bullard, Bettie

2005-01-01

During the past 10 years, the level of technology in schools has increased with tremendous speed. Accessible through that medium is a body of information that will double in 6 years and quadruple in 12. Before teachers have mastered one type of technology, school administrators are stacking old computers in workrooms or behind stage curtains. Just…

Cigarette smoke-induced DNA damage and repair detected by the comet assay in HPV-transformed cervical cells.

PubMed

Moktar, Afsoon; Ravoori, Srivani; Vadhanam, Manicka V; Gairola, C Gary; Gupta, Ramesh C

2009-12-01

Human papillomavirus (HPV) is the causative factor in the development and progression of cervical cancers in >97% of the cases, although insufficient. Epidemiological studies suggest an elevated risk of cervical cancer for cigarette smokers; therefore, we examined cigarette smoke-induced DNA damage and repair in HPV16-transformed human ectocervical cells (ECT1/E6 E7). Cells were treated with cigarette smoke condensate (CSC) for 72 h to assess the formation of single- and double-strand DNA breaks, measured by alkaline and neutral single cell gel electrophoresis assays, respectively. The mean tail length of cells with single-strand breaks was increased by 1.8-, 2.7- and 3.7-fold (p<0.001) after treatment with 4, 8 and 12 microg/ml CSC, respectively. The tail length with double-strand breaks was also increased dose-dependently. These results were further supported by measurement of the mean tail moment: the increase in both single- and double-strand breaks were much more pronounced with increasing concentration of CSC, by up to 23.5-fold (p<0.0001 for both assays). To examine the DNA repair, cells were treated with CSC for 72 h, followed by CSC withdrawal and re-incubation of the cells with fresh medium for 24, 48, or 72 h. Both single- and double-strand DNA breaks were removed during the initial 24 h but no further removal of the damage was observed. Up to 80% of residual single- and double-strand DNA breaks (p<0.05) were found to persist at all CSC concentrations examined. Ellagic acid, a known antioxidant and free-radical scavenger, was found to significantly inhibit DNA breaks induced by CSC. Thus, free radicals may be a plausible source of CSC-induced DNA damage. These data show that CSC-mediated DNA strand breaks are highly persistent, and suggest that persistence of cigarette smoke-associated DNA damage in the presence of HPV infection may lead to increased mutations in cervical cells and ultimately higher cancer risk.

Results of the International Validation of the in vivo rodent alkaline comet assay for the detection of genotoxic carcinogens: Individual data for 1,2-dibromoethane, p-anisidine, and o-anthranilic acid in the 2nd step of the 4th phase Validation Study under the JaCVAM initiative.

PubMed

Takasawa, Hironao; Takashima, Rie; Narumi, Kazunori; Kawasako, Kazufumi; Hattori, Akiko; Kawabata, Masayoshi; Hamada, Shuichi

2015-07-01

As part of the Japanese Center for the Validation of Alternative Methods (JaCVAM)-initiative International Validation Study of an in vivo rat alkaline comet assay, we examined 1,2-dibromoethane (DBE), p-anisidine (ASD), and o-anthranilic acid (ANT) to investigate the effectiveness of the comet assay in detecting genotoxic carcinogens. Each of the three test chemicals was administered to 5 male Sprague-Dawley rats per group by oral gavage at 48, 24, and 3h before specimen preparation. Single cells were collected from the liver and glandular stomach at 3h after the final dosing, and the specimens prepared from these two organs were subjected to electrophoresis under alkaline conditions (pH>13). The percentage of DNA intensity in the comet tail was then assessed using an image analysis system. A micronucleus (MN) assay was also conducted using these three test chemicals with the bone marrow (BM) cells collected from the same animals simultaneously used in the comet assay, i.e., combination study of the comet assay and BM MN assay. A genotoxic (Ames positive) rodent carcinogen, DBE gave a positive result in the comet assay in the present study, while a genotoxic (Ames positive) non-carcinogen, ASD and a non-genotoxic (Ames negative) non-carcinogen, ANT showed negative results in the comet assay. All three chemicals produced negative results in the BM MN assay. While the comet assay findings in the present study were consistent with those obtained from the rodent carcinogenicity studies for the three test chemicals, we consider the positive result in the comet assay for DBE to be particularly meaningful, given that this chemical produced a negative result in the BM MN assay. Therefore, the combination study of the comet assay and BM MN assay is a useful method to detect genotoxic carcinogens that are undetectable with the BM MN assay alone. Copyright © 2015 Elsevier B.V. All rights reserved.

Aqueous Foam Stabilized by Tricationic Amphiphilic Surfactants

NASA Astrophysics Data System (ADS)

Heerschap, Seth; Marafino, John; McKenna, Kristin; Caran, Kevin; Feitosa, Klebert; Kevin Caran's Research Group Collaboration

2015-03-01

The unique surface properties of amphiphilic molecules have made them widely used in applications where foaming, emulsifying or coating processes are needed. The development of novel architectures with multi-cephalic/tailed molecules have enhanced their anti-bacterial activity in connection with tail length and the nature of the head group. Here we report on the foamability of two triple head double, tail cationic surfactants (M-1,14,14, M-P, 14,14) and a triple head single tail cationic surfactant (M-1,1,14) and compare them with commercially available single headed, single tailed anionic and cationic surfactants (SDS,CTAB and DTAB). The results show that bubble rupture rate decrease with the length of the carbon chain irrespective of head structure. The growth rate of bubbles with short tailed surfactants (SDS) and longer, single tailed tricationic surfactants (M-1,1,14) was shown to be twice as high as those with longer tailed surfactants (CTAB, M-P,14,14, M-1,14,14). This fact was related to the size variation of bubbles, where the foams made with short tail surfactants exhibited higher polydispersivity than those with short tails. This suggests that foams with tricationic amphiphilics are closed linked to their tail length and generally insensitive to their head structure.

The Carboxyl Tail of Connexin32 Regulates Gap Junction Assembly in Human Prostate and Pancreatic Cancer Cells*

PubMed Central

Katoch, Parul; Mitra, Shalini; Ray, Anuttoma; Kelsey, Linda; Roberts, Brett J.; Wahl, James K.; Johnson, Keith R.; Mehta, Parmender P.

2015-01-01

Connexins, the constituent proteins of gap junctions, are transmembrane proteins. A connexin (Cx) traverses the membrane four times and has one intracellular and two extracellular loops with the amino and carboxyl termini facing the cytoplasm. The transmembrane and the extracellular loop domains are highly conserved among different Cxs, whereas the carboxyl termini, often called the cytoplasmic tails, are highly divergent. We have explored the role of the cytoplasmic tail of Cx32, a Cx expressed in polarized and differentiated cells, in regulating gap junction assembly. Our results demonstrate that compared with the full-length Cx32, the cytoplasmic tail-deleted Cx32 is assembled into small gap junctions in human pancreatic and prostatic cancer cells. Our results further document that the expression of the full-length Cx32 in cells, which express the tail-deleted Cx32, increases the size of gap junctions, whereas the expression of the tail-deleted Cx32 in cells, which express the full-length Cx32, has the opposite effect. Moreover, we show that the tail is required for the clustering of cell-cell channels and that in cells expressing the tail-deleted Cx32, the expression of cell surface-targeted cytoplasmic tail alone is sufficient to enhance the size of gap junctions. Our live-cell imaging data further demonstrate that gap junctions formed of the tail-deleted Cx32 are highly mobile compared with those formed of full-length Cx32. Our results suggest that the cytoplasmic tail of Cx32 is not required to initiate the assembly of gap junctions but for their subsequent growth and stability. Our findings suggest that the cytoplasmic tail of Cx32 may be involved in regulating the permeability of gap junctions by regulating their size. PMID:25548281

The comet assay in human biomonitoring.

PubMed

Anderson, Diana; Dhawan, Alok; Laubenthal, Julian

2013-01-01

Human biomonitoring studies aim to identify potential exposures to environmental, occupational, or lifestyle toxicants in human populations and are commonly used by public health decision makers to predict disease risk. The Comet assay measures changes in genomic stability and is one of the most reliable biomarkers to indicate early biological effects, and therefore accepted by various governmental regulatory agencies. The appeal of the Comet assay lies in its relative simplicity, rapidity, sensitivity, and economic efficiency. Furthermore, the assay is known for its broad versatility, as it can be applied to virtually any human cell and easily adapted in order to detect particular biomarkers of interest, such as DNA repair capacity or single- and double-strand breaks. In a standard experiment, isolated single cells are first embedded in agarose, and then lysed in high-salt solutions in order to remove all cellular contents except the DNA attached to a nuclear scaffold. Subsequent electrophoresis results in accumulation of undamaged DNA sequences at the proximity of the nuclear scaffold, while damaged sequences migrate towards the anode. When visualized with fluorochromes, these migrated DNA fragments resemble a comet tail and can be quantified for their intensity and shape according to internationally drafted guidelines.

Optical observations of the AMPTE artificial comet and magnetotail barium releases

NASA Technical Reports Server (NTRS)

Hallinan, T. J.; Stenbaek-Nielsen, H.; Brown, N.

1985-01-01

The first AMPTE artificial comet was observed with a low light level television camera operated aboard the NASA CV990 flying out of Moffett Field, California. The comet head, neutral cloud, and comet tail were all observed for four minutes with an unifiltered camera. Brief observations at T + 4 minutes through a 4554A Ba(+) filter confirmed the identification of the structures. The ion cloud expanded along with the neutral cloud at a rate of 2.3 km/sec (diameter) until it reached a final diameter of approx. 170 km at approx. T + 90 s. It also drifted with the neutral cloud until approx. 165 s. By T + 190 s it had reached a steady state velocity of 5.4 km/sec southward. A barium release in the magnetotail was observed from the CV990 in California, Eagle, Alaska, and Fairbanks, Alaska. Over a twenty-five minute period, the center of the barium streak drifted southward (approx. 500 m/sec), upward (24 km/sec) and eastward (approx 1 km/sec) in a nonrotating reference frame. An all-sky TV at Eagle showed a single auroral arc in the far North during this period.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Opher, M.; Drake, J. F.; Zieger, B.

The classic accepted view of the heliosphere is a quiescent, comet-like shape aligned in the direction of the Sun’s travel through the interstellar medium (ISM) extending for thousands of astronomical units (AUs). Here, we show, based on magnetohydrodynamic (MHD) simulations, that the tension (hoop) force of the twisted magnetic field of the Sun confines the solar wind plasma beyond the termination shock and drives jets to the north and south very much like astrophysical jets. These jets are deflected into the tail region by the motion of the Sun through the ISM similar to bent galactic jets moving through themore » intergalactic medium. The interstellar wind blows the two jets into the tail but is not strong enough to force the lobes into a single comet-like tail, as happens to some astrophysical jets. Instead, the interstellar wind flows around the heliosphere and into the equatorial region between the two jets. As in some astrophysical jets that are kink unstable, we show here that the heliospheric jets are turbulent (due to large-scale MHD instabilities and reconnection) and strongly mix the solar wind with the ISM beyond 400 AU. The resulting turbulence has important implications for particle acceleration in the heliosphere. The two-lobe structure is consistent with the energetic neutral atom (ENA) images of the heliotail from IBEX where two lobes are visible in the north and south and the suggestion from the Cassini ENAs that the heliosphere is “tailless.”.« less

Cometary water-group ions in the region surrounding Comet Giacobini-Zinner - Distribution functions and bulk parameter estimates

NASA Astrophysics Data System (ADS)

Staines, K.; Balogh, A.; Cowley, S. W. H.; Hynds, R. J.; Yates, T. S.; Richardson, I. G.; Sanderson, T. R.; Wenzel, K. P.; McComas, D. J.; Tsurutani, B. T.

1991-03-01

The bulk parameters (number density and thermal energy density) of cometary water-group ions in the region surrounding Comet Giacobini-Zinner have been derived using data from the EPAS instrument on the ICE spacecraft. The derivation is based on the assumption that the pick-up ion distribution function is isotropic in the frame of the bulk flow, an approximation which has previously been shown to be reasonable within about 400,000 km of the comet nucleus along the spacecraft trajectory. The transition between the pick-up and mass-loaded regions occurs at the cometary shock, which was traversed at a cometocentric distance of about 100,000 km along the spacecraft track. Examination of the ion distribution functions in this region, transformed to the bulk flow frame, indicates the occurrence of a flattened distribution in the vicinity of the local pick-up speed, and a steeply falling tail at speeds above, which may be approximated as an exponential in ion speed.

Four-fluid MHD Simulations of the Plasma and Neutral Gas Environment of Comet 67P/Churyumov-Gerasimenko Near Perihelion

NASA Astrophysics Data System (ADS)

Huang, Zhenguang; Toth, Gabor; Gombosi, Tamas; Jia, Xianzhe; Rubin, Martin; Fougere, Nicolas; Tenishev, Valeriy; Combi, Michael; Bieler, Andre; Hansen, Kenneth; Shou, Yinsi; Altwegg, Kathrin

2016-04-01

The neutral and plasma environment is critical in understanding the interaction of the solar wind and comet 67P/Churyumov-Gerasimenko (CG), the target of the European Space Agency's Rosetta mission. In this study, we have developed a 3-D four-fluid model, which is based on BATS-R-US (Block-Adaptive Tree Solarwind Roe-type Upwind Scheme) within SWMF (Space Weather Modeling Framework) that solves the governing multi-fluid MHD equations and the Euler equations for the neutral gas fluid. These equations describe the behavior and interactions of the cometary heavy ions, the solar wind protons, the electrons, and the neutrals. We simulated the plasma and neutral gas environment of comet CG with SHAP5 model near perihelion and we showed that the plasma environment in the inner coma region have some new features: magnetic reconnection in the tail region, a magnetic pile-up region on the nightside, and nucleus directed plasma flow inside the nightside reconnection region.

Optical polarimetry of Comet NEAT C/2001 Q4

NASA Astrophysics Data System (ADS)

Ganesh, S.; Joshi, U. C.; Baliyan, K. S.

2009-06-01

Comet NEAT C/2001 Q4 was observed for linear polarization using the optical polarimeter mounted at the 1.2 m telescope at Mt. Abu Observatory, during the months of May and June 2004. Observations were conducted through the International Halley Watch narrow band (continuum) and BVR broad band filters. During the observing run the phase angle ranged from 85.6° in May to 55° in June. As expected, polarization increases with wavelength in this phase angle range. Polarization colour in the narrow bands changes at different epochs, perhaps related to cometary activity or molecular emission contamination. The polarization was also measured in the cometary coma at different locations along a line, in the direction of the tail. As expected, we notice minor decrease in the polarization as photocenter (nucleus) is traversed while brightness decreases sharply away from it. Based on these polarization observations we infer that the Comet NEAT C/2001 Q4 has high polarization and a typical grain composition—mixture of silicates and organics.

Vitamin C attenuates biochemical and genotoxic damage in common carp (Cyprinus carpio) upon joint exposure to combined toxic doses of fipronil and buprofezin insecticides.

PubMed

Ghazanfar, Madiha; Shahid, Sana; Qureshi, Irfan Zia

2018-03-01

In the present study, potential protective role of Vitamin C (l-ascorbic acid) was investigated in aquaria acclimated common carp (Cyprinus carpio) following exposure for 96 h to combined toxic doses of fipronil (FP) and buprofezin (BPFN) insecticides in combination (FP: 200 μg/L; 4.57 × 10 -7  mol/L and BPFN: 50 mg/L; 1.64 × 10 -4  mol/L). At end of 96 h exposure, fish were supplemented with low (25 mg/L) and high (50 mg/L) doses of Vitamin C, added once daily to aquaria water for continuous three weeks. Appropriate control groups were run in parallel. Fish behavior was monitored throughout for signs of toxicity. At completion of experiments, liver, kidney, brain and gills were excised for toxicity assessment and possible remediation by the Vitamin C through biochemical determination of reactive oxygen species (ROS), thiobarbituric acid reactive substances or TBARS, reduced glutathione (GSH) and total protein content, levels of catalase (CAT), superoxide dismutase (SOD) and peroxidase (POD), and the Comet assay. Hepatosomatic index (HSI), condition factor (CF), survival rate (SR), and combination index (CI) were also determined. Data were compared statistically at p < 0.05. Results showed significant behavioral and biochemical alterations, and DNA damage in the fish group exposed to FP and BPFN in combination. In fish groups supplemented with Vitamin C following FP and BPFN treatment, significant alleviation in tissue damage and toxic effects was represented by substantial decreases in ROS and TBARS production (p < 0.001), along with a concomitant significant increase in the survival rate, GSH and total protein content, HSI, CF, and activities of SOD, CAT and POD enzymes (p < 0.001). Mean tail length of comet and percent tail DNA decreased significantly (p < 0.001), which indicated amelioration of DNA damage. The study concludes that Vitamin C is an effective remedial treatment against FP and BPFN-induced damage in exposed fish. Copyright © 2018 Elsevier B.V. All rights reserved.

Influence of experimental conditions on data variability in the liver comet assay.

PubMed

Guérard, M; Marchand, C; Plappert-Helbig, U

2014-03-01

The in vivo comet assay has increasingly been used for regulatory genotoxicity testing in recent years. While it has been demonstrated that the experimental execution of the assay, for example, electrophoresis or scoring, can have a strong impact on the results; little is known on how initial steps, that is, from tissue sampling during necropsy up to slide preparation, can influence the comet assay results. Therefore, we investigated which of the multitude of steps in processing the liver for the comet assay are most critical. All together eight parameters were assessed by using liver samples of untreated animals. In addition, two of those parameters (temperature and storage time of liver before embedding into agarose) were further investigated in animals given a single oral dose of ethyl methanesulfonate at dose levels of 50, 100, and 200 mg/kg, 3 hr prior to necropsy. The results showed that sample cooling emerged as the predominant influence factor, whereas variations in other elements of the procedure (e.g., size of the liver piece sampled, time needed to process the liver tissue post-mortem, agarose temperature, or time of lysis) seem to be of little relevance. Storing of liver samples of up to 6 hr under cooled conditions did not cause an increase in tail intensity. In contrast, storing the tissue at room temperature, resulted in a considerable time-dependent increase in comet parameters. Copyright © 2013 Wiley Periodicals, Inc.

Comet C/2011 W3 (Lovejoy) between 2 and 10 Solar Radii: Physical Parameters of the Comet and the Corona

NASA Astrophysics Data System (ADS)

Raymond, J. C.; Downs, Cooper; Knight, Matthew M.; Battams, Karl; Giordano, Silvio; Rosati, Richard

2018-05-01

Comet C/2011 W3 (Lovejoy) is the first sungrazing comet in many years to survive perihelion passage. We report ultraviolet observations with the Ultraviolet Coronagraph Spectrometer (UVCS) spectrometer aboard the Solar and Heliospheric Observatory satellite at five heights as the comet approached the Sun. The brightest line, Lyα, shows dramatic variations in intensity, velocity centroid, and width during the observation at each height. We derive the outgassing rates and the abundances of N, O, and Si relative to H, and we estimate the effective diameter of the nucleus to be several hundred meters. We consider the effects of the large outgassing rate on the interaction between the cometary gas and the solar corona and find good qualitative agreement with the picture of a bow shock resulting from mass loading by cometary neutrals. We obtain estimates of the solar wind density, temperature, and speed, and compare them with predictions of a global magnetohydrodynamic simulation, finding qualitative agreement within our uncertainties. We also determine the sublimation rate of silicate dust in the comet’s tail by comparing the visible brightness from the Large Angle Spectroscopic Coronagraphs with the Si III intensity from UVCS. The sublimation rates lie between the predicted rates for olivines and pyroxenes, suggesting that the grains are composed of a mixture of those minerals.

The Gas Production Rate and Coma Structure of Comet C/1995 01 (Hale-Bopp)

NASA Technical Reports Server (NTRS)

Morgenthaler, Jeffrey P.; Harris, Walter M.; Roesler, Frederick L.; Scherb, Frank; Anderson, Christopher M.; Doane, Nathaniel E.; Oliversen, Ronald J.

2002-01-01

The University of Wisconsin-Madison and NASA-Goddard conducted a comprehensive multi-wavelength observing campaign of coma emissions from comet Hale-Bopp, including OH 3080 A, [O I] 6300 A, H2O(+) 6158 A, H Balmer-alpha 6563 A, NH2 6330 A, [C I] 9850 A CN 3879 A, C2 5141 A, C3 4062 A, C I 1657 A, and the UV and optical continua. In this work, we concentrate on the results of the H2O daughter studies. Our wide-field OH 3080 A measured flux agrees with other, similar observations and the expected value calculated from published water production rates using standard H2O and OH photochemistry. However, the total [O I] 6300 A flux determined spectroscopically over a similar field-of-view was a factor of 3 - 4 higher than expected. Narrow-band [O I] images show this excess came from beyond the H2O scale length, suggesting either a previously unknown source of [O I] or an error in the standard OH + upsilon to O((sup I)D) + H branching ratio. The Hale-Bopp OH and [O I] distributions, both of which were imaged to cometocentric distances greater than 1 x 10(exp 6) km, were more spatially extended than those of comet Halley (after correcting for brightness differences), suggesting a higher bulk outflow velocity. Evidence of the driving mechanism for this outflow is found in the H(alpha) line profile, which was narrower than in comet Halley (though likely because of opacity effects, not as narrow as predicted by Monte-Carlo models). This is consistent with greater collisional coupling between the suprathermal H photodissociation products and Hale-Bopp's dense coma. Presumably because of mass loading of the solar wind by ions and ions by the neutrals, the measured acceleration of H2O(+) down the ion tail was much smaller than in comet Halley. Tailward extensions in the azimuthal distributions of OH 3080 A, [O I], and [C I], as well as a Doppler asymmetry in the [O I] line profile, suggest ion-neutral coupling. While the tailward extension in the OH can be explained by increased neutral acceleration, the [O I] 6300 A and [C I] 9850 A emissions show 13% and less than 200% excesses in this direction (respectively), suggesting a non-negligible contribution from dissociative recombination of CO(+) and/or electron collisional excitation. Thus, models including the effects of photo-and collisional chemistry are necessary for the full interpretation of these data.

Navigating the International Cometary Explorer for encounter with Comet Giacobini-Zinner

NASA Astrophysics Data System (ADS)

Efron, L.; Muellerschoen, R. J.; Premkumar, R. I.

The navigation of the International Cometary Explorer for its encounter with Comet Giacobini-Zinner, provided by orbit determination using radio metric data from the 64-m Deep Space Network antennas in California and Spain, is discussed. Orbital solutions providing predictions of 50-km geocentric delivery accuracy in the target plane were achieved using 6-12 week data arcs between periodic attitude change maneuvers. The one-sigma two-way range and range rate were found to be 40 m and 0.2 mm/s or better, respectively. Post-flight analysis shows tail centerline passage to be achieved within 10 s of the predicted time, and a geocentric position uncertainty at the encounter of better than 40 km is found.

Morphological changes and allometric growth in hatchery-reared Chinese loach Paramisgurnus dabryanus (Dabry de Thiersant, 1872)

NASA Astrophysics Data System (ADS)

Zhang, Yunlong; Wu, Qiaowan; Hu, Weihua; Wang, Fan; Shao, Weihan; Zhang, Chengming; Zhao, Zhongbo; He, Hui; Fan, Qixue; Gu, Zemao

2016-07-01

The length-weight relationship and allometric growth patterns of hatchery-reared Chinese loach, Paramisgurnus dabryanus (Dabry de Thiersant, 1872), were determined from hatching to 60 days after hatching. A best power model was estimated for the length-weight relationship during the early life stages. Positive allometric growth for the head segment, trunk length, tail length and eye diameter was also found in the early life stages, while body depth, tail depth, tail fin length, pectoral fin length and barbel length displayed a negative coefficient. During the subsequent early developmental stage, the growth coefficients showed a clear and common tendency towards isometry for all measured body ratios. The allometric growth changes in Chinese loach during the early stage are possibly the result of selective organogenesis directed towards survival priorities.

Development and Testing of Harpoon-Based Approaches for Collecting Comet Samples

NASA Technical Reports Server (NTRS)

Purves, Lloyd (Compiler); Nuth, Joseph (Compiler); Amatucci, Edward (Compiler); Wegel, Donald; Smith, Walter; Church, Joseph; Leary, James; Kee, Lake; Hill, Stuart; Grebenstein, Markus;

Small is different: RPC observations of a small scale comet interacting with the solar wind

NASA Astrophysics Data System (ADS)

Nilsson, Hans; Burch, James L.; Carr, Christopher M.; Eriksson, Anders I.; Glassmeier, Karl-Heinz; Henri, Pierre; Rosetta Plasma Consortium Team

2016-10-01

Rosetta followed comet 67P from low activity at more than 3 AU heliocentric distance to peak activity at perihelion and then out again. We study the evolution of the dynamic plasma environment using data from the Rosetta Plasma Consortium (RPC). Observations of cometary plasma began in August 2014, at a distance of 100 km from the comet nucleus and at 3.6 AU from the Sun. As the comet approached the Sun, outgassing from the comet increased, as did the density of the cometary plasma. Measurements showed a highly heterogeneous cold ion environment, permeated by the solar wind. The solar wind was deflected due to the mass loading from newly added cometary plasma, with no discernible slowing down. The magnetic field magnitude increased significantly above the background level, and strong low frequency waves were observed in the magnetic field, a.k.a. the "singing comet". Electron temperatures were high, leading to a frequently strongly negative spacecraft potential. In mid to late April 2015 the solar wind started to disappear from the observation region. This was associated with a solar wind deflection reaching nearly 180°, indicating that mass loading became efficient enough to form a solar wind-free region. Accelerated water ions, moving mainly in the anti-sunward direction, kept being observed also after the solar wind disappearance. Plasma boundaries began to form and a collisionopause was tentatively identified in the ion and electron data. At the time around perihelion, a diamagnetic cavity was also observed, at a surprisingly large distance from the comet. In late 2016 the solar wind re-appeared at the location of Rosetta, allowing for studies of asymmetry of the comet ion environment with respect to perihelion. A nightside excursion allowed us to get a glimpse of the electrodynamics of the innermost part of the plasma tail. Most of these phenomena are dependent on the small-scale physics of comet 67P, since for most of the Rosetta mission the solar wind - comet atmosphere interaction region is smaller than the pickup ion gyroradius in the undisturbed solar wind.

Physical and dynamical properties of the anomalous comet 249P/LINEAR

NASA Astrophysics Data System (ADS)

Fernández, Julio A.; Licandro, Javier; Moreno, Fernando; Sosa, Andrea; Cabrera-Lavers, Antonio; de León, Julia; Birtwhistle, Peter

2017-10-01

Images and low-resolution spectra of the near-Earth Jupiter family comet (JFC) 249P/LINEAR in the visible range obtained with the instrument OSIRIS in the 10.4 m Gran Telescopio Canarias (GTC) (La Palma, Spain) on January 3, 4, 6 and February 6, 2016 are presented, together with a series of images obtained with the 0.4m telescope of the Great Shefford Observatory obtained on Oct. 22 and 27, and Nov. 1 and 24, 2006. The reflectance spectrum of 249P is similar to that of a B-type asteroid. The comet has an absolute (visual) nuclear magnitude HV = 17.0 ± 0.4 , which corresponds to a radius of about 1-1.3 km for a geometric albedo ∼ 0.04 - 0.07 . From the analysis of GTC images using a Monte Carlo dust tail code we find that the time of maximum dust ejection rate was around 1.6 days before perihelion. The analysis of the dust tails during the 2006 and 2016 perihelion approaches reveals that, during both epochs, the comet repeated the same dust ejection pattern, with a similar short-lived activity period of about 20 days (FWHM) around perihelion and a dust loss rate peaking at 145 ± 50 kg/s. The total dust mass ejected during its last perihelion passage was (2.5 ± 0.9) × 108 kg, almost all this mass being emitted before the first observation of January 3, 2016. The activity onset, duration, and total ejected mass were very similar during the 2006 perihelion passage. This amount of dust mass is very low as compared with that from other active JFCs. The past orbital evolution of 249P and 100 clones were also followed over a time scale of ∼ 5 × 104 yr. The object and more than 60% of the clones remained bound to the near-Earth region for the whole computed period, keeping its perihelion distance within the range q ≃ 0.4 - 1.1 au. The combination of photometric and spectroscopic observations and dynamical studies show that the near-Earth comet 249P/LINEAR has several peculiar features that clearly differentiate it from typical JFCs. We may be in front of a new class of near-Earth JFC whose source region is not the distant trans-neptunian population, but much closer in the asteroid belt. Therefore, 249P/LINEAR may be a near-Earth counterpart of the so-called main-belt comets or active asteroids.

The poly(A) tail length of casein mRNA in the lactating mammary gland changes depending upon the accumulation and removal of milk.

PubMed Central

Kuraishi, T; Sun, Y; Aoki, F; Imakawa, K; Sakai, S

2000-01-01

The length of casein mRNA from the lactating mouse mammary gland, as assessed on Northern blots, is shorter after weaning, but is elongated following the removal of milk. In order to investigate this phenomenon, the molecular structures of beta- and gamma-casein mRNAs were analysed. The coding and non-coding regions of the two forms were the same length, but the long form of casein mRNA had a longer poly(A) tail than the short form (P<0.05). In order to examine the stability of casein mRNA under identical conditions, casein mRNAs with the long and short poly(A) tails were incubated in the rabbit reticulocyte lysate (RRL) cell-free translation system. Casein mRNA with the long poly(A) tail had a longer half-life than that with the short tail (P<0.05). The beta- and gamma-casein mRNAs were first degraded into 0.92 and 0.81 kb fragments respectively. With undegraded mRNA, the poly(A) tail shortening by exoribonuclease was not observed until the end of the incubation. Northern blot analysis showed that casein mRNA with the long poly(A) tail was protected efficiently from endoribonucleases. We conclude that the length of the poly(A) tail of casein mRNA in the lactating mammary gland changes depending upon the accumulation and removal of the gland's milk, and we show that the longer poly(A) tail potentially protects the mRNA from degradation by endoribonucleases. PMID:10749689

The carboxyl tail of connexin32 regulates gap junction assembly in human prostate and pancreatic cancer cells.

PubMed

Katoch, Parul; Mitra, Shalini; Ray, Anuttoma; Kelsey, Linda; Roberts, Brett J; Wahl, James K; Johnson, Keith R; Mehta, Parmender P

2015-02-20

Connexins, the constituent proteins of gap junctions, are transmembrane proteins. A connexin (Cx) traverses the membrane four times and has one intracellular and two extracellular loops with the amino and carboxyl termini facing the cytoplasm. The transmembrane and the extracellular loop domains are highly conserved among different Cxs, whereas the carboxyl termini, often called the cytoplasmic tails, are highly divergent. We have explored the role of the cytoplasmic tail of Cx32, a Cx expressed in polarized and differentiated cells, in regulating gap junction assembly. Our results demonstrate that compared with the full-length Cx32, the cytoplasmic tail-deleted Cx32 is assembled into small gap junctions in human pancreatic and prostatic cancer cells. Our results further document that the expression of the full-length Cx32 in cells, which express the tail-deleted Cx32, increases the size of gap junctions, whereas the expression of the tail-deleted Cx32 in cells, which express the full-length Cx32, has the opposite effect. Moreover, we show that the tail is required for the clustering of cell-cell channels and that in cells expressing the tail-deleted Cx32, the expression of cell surface-targeted cytoplasmic tail alone is sufficient to enhance the size of gap junctions. Our live-cell imaging data further demonstrate that gap junctions formed of the tail-deleted Cx32 are highly mobile compared with those formed of full-length Cx32. Our results suggest that the cytoplasmic tail of Cx32 is not required to initiate the assembly of gap junctions but for their subsequent growth and stability. Our findings suggest that the cytoplasmic tail of Cx32 may be involved in regulating the permeability of gap junctions by regulating their size. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

The neutral coma of comets: A review

NASA Technical Reports Server (NTRS)

Delsemme, A. H.

1976-01-01

The hypothesis that water snow controls the vaporization of the nucleus of some comets seems verified from the general order of magnitude of the size of their nucleus and of their nuclear albedo; the largest observed production rates are H and OH which both seem to originate from the photodissociation of H2O, as also confirmed by the scale length of the invisible parent molecule producing OH. However, comet Encke is not uniformly covered by water snow, as it produces only one tenth of the expected vaporization. Early results on comet Kohoutek suggest that the conclusions could be slightly different for some of the new comets in Oort's sense. If the far ultraviolet observations confirm the early assessments of the production rates of C, O and H, then at least another major constituent competing with water has not yet been detected. Such a major constituent is suggested by the ratios C/O = 0.24 and H/O = 2.5.

Antiproliferative Activity and Apoptosis Inducing Mechanism of Anthocephalus cadamba on Dalton’s Lymphoma Ascites Cells

PubMed Central

Dolai, Narayan; Islam, Aminul; Haldar, Pallab Kanti

2016-01-01

The purpose of this investigation was to evaluate the antiproliferative and apoptogenic mechanistic studies of methanol extract of Anthocephalus cadamba (MEAC) on Dalton’s lymphoma ascites (DLA) cells treated mice. Determination of antiproliferative activity was performed by using different DLA cells (2×106 cells, i.p.) inoculated mice groups (n = 12). Groups were treated for 14 consecutive days with MEAC at the doses of 200 and 400 mg/Kg b.w. respectively. The mechanism of antiproliferation activity of MEAC was investigated through morphological studies by acridine orange (AO)/ethidium bromide (EB) double staining method. Comet assay was estimated to check the DNA damage induced apoptosis property. Furthermore, flow cytometry (FACS) was used to quantitatively detect the apoptotic rate by double labeling techniques using Annexin-V FITC/propidium iodide staining analysis and apoptotic proteins expression done by western blotting assay method. MEAC exhibited significant (p<0.01) decrease the tumor volume, viable cell count, tumor weight and elevated the life span of DLA tumor bearing mice. Analysis of AO/EB staining and flow cytometry showed that MEAC possessed apoptosis induced antitumor activity on DLA cells in a dose dependant manner. Dose dependent induction of DNA damage on DLA cells were observed after MEAC treatment, which was evident from the appearance of comet tail length. Pro-apoptotic gene, Bax was up-regulated and down-regulation of the Bcl-2/Bax ratio, suggesting that Bcl-2 family involved in the control of apoptosis. Experimental results revealed that MEAC possess potent antitumor activity via induction of cancer cell apoptosis mechanism. PMID:27980586

E-cigarette vapour is not inert and exposure can lead to cell damage.

PubMed

Holliday, Richard; Kist, Ralf; Bauld, Linda

2016-03-01

In vitro experiments were performed on normal epithelial cells as well as head and neck squamous cell carcinoma (HNSCC) cell lines. The widely available cell line HaCat, a spontaneously transformed immortal keratinocyte and the HNSCC cell lines HN30 and UMSCC10B were used. Cells were exposed to nicotine-containing and nicotine-free vapour extract from two popular e-cigarette brands for periods ranging from 48 hours to eight weeks. Cytotoxicity was assessed using Annexin V flow cytometric analysis, trypan blue exclusion and clonogenic assays. Genotoxicity in the form of DNA strand breaks was quantified using the neutral comet assay and γ-H2AX immunostaining. E-cigarette-exposed cells showed significantly reduced cell viability and clonogenic survival, along with increased rates of apoptosis and necrosis, regardless of e-cigarette vapour nicotine content. They also exhibited significantly increased comet tail length and accumulation of γ-H2AX foci, demonstrating increased DNA strand breaks. In conclusion, our study strongly suggests that electronic cigarettes are not as safe as their marketing makes them appear to the public. Our in vitro experiments employing two brands of e-cigs show that at biologically relevant doses, vapourised e-cig liquids induce increased DNA strand breaks and cell death, and decreased clono- genic survival in both normal epithelial and HNSCC cell lines independently of nicotine content. Further research is needed to definitively determine the long-term effects of e-cig usage, as well as whether the DNA damage shown in our study as a result of e-cig exposure will lead to mutations that ultimately result in cancer.

NASA Vision. Volume 1, No. 5

NASA Technical Reports Server (NTRS)

Fenton, Mary (Editor); Wood, Jennifer (Editor)

2003-01-01

Contents include the following: Administrator O'Keefe addresses NASA's return to flight. New independent engineering and safety center. Around the centers. NASA and your library: local libraries making room for space. Robonaut: the next generation. Inspiring the next generation ... of Hispanics. NASA and teachers focus on parks. GSFC director gives keynote address. Agency honor awards. Summer interns join the NASA team. Catching a comet's tail in Earth's atmosphere.

Pioneer Venus observations during Comet Halley's inferior conjunction

NASA Technical Reports Server (NTRS)

Russell, C. T.; Luhmann, J. G.; Scarf, F. L.

1985-01-01

On Feb. 4, 1986, Halley passed through inferior conjunction with Venus but was at high latitudes. Not all data for this time period have been received. However, the data that are available suggest that at most only weak effects associated with Halley were seen at Pioneer Venus. The data during this time, however, are useful for correlating with the behavior of the plasma tail.

Effect of nose shape and tail length on supersonic stability characteristics of a projectile

NASA Technical Reports Server (NTRS)

Sawyer, W. C.; Collins, I. K.

1973-01-01

The effect of nose shape and tail length on the static stability of a fin-stabilized projectile has been investigated in the Langley Unitary Plan with tunnel at angles of attack to about 12 deg for a Mach number range from 1.5 to 2.5. The tests were made at a constant Reynolds number of 6.56 x 1,000,000 per meter. The results of the investigation showed that nose shape had no effect on the static stability. Increasing the tail length resulted in a progressively stabilizing tendency. However, only the 1.5-caliber-tail-length configuration was stable over the test angle-of-attack range at Mach number 1.5. This configuration was marginally stable or unstable at the higher Mach numbers, and the shorter configurations were unstable at all Mach numbers for either part of or the entire test angle-of-attack range.

The association of occupational metals exposure and oxidative damage, telomere shortening in fitness equipments manufacturing workers

PubMed Central

KO, Jiunn-Liang; CHENG, Yu-Jung; LIU, Guan-Cen; HSIN, I-Lun; CHEN, Hsiu-Ling

2017-01-01

The welding is the major working process in fitness equipment manufacturing industry, and International Agency for Research on Cancer has classified welding fumes as possibly carcinogenic to humans (Group 2B). The present study aimed to evaluate associations between the occupational exposure of metals and oxidative damage and telomere length shortening in workers involved in the manufacture of fitness equipment. The blood metal concentrations were monitored and malondialdehyde (MDA), alkaline Comet assay was determined as oxidative damage in 117 workers from two representative fitness equipment manufacturing plants. MDA levels varied according to workers’ roles at the manufacturing plants, and showed a trend as cutting>painting>welding>administration workers. Welders had marginally shorter average telomere lengths than the administrative workers (p=0.058). Cr and Mn levels were significantly greater in welders than they were in administrative workers. There were significantly positive correlations between MDA and Cr and Mn levels, the major components of welding fume. However, the association would be eliminated if co-metals exposure were considered simultaneously. In future, telomere length and MDA might be potential biomarkers for predicting cardiovascular disease in co-metals exposed workers. PMID:28420806

What is a Sungrazing Comet? [hd video

NASA Image and Video Library

2013-11-27

Sungrazing comets are a special class of comets that come very close to the sun at their nearest approach, a point called perihelion. To be considered a sungrazer, a comet needs to get within about 850,000 miles from the sun at perihelion. Many come even closer, even to within a few thousand miles. Being so close to the sun is very hard on comets for many reasons. They are subjected to a lot of solar radiation which boils off their water or other volatiles. The physical push of the radiation and the solar wind also helps form the tails. And as they get closer to the sun, the comets experience extremely strong tidal forces, or gravitational stress. In this hostile environment, many sungrazers do not survive their trip around the sun. Although they don't actually crash into the solar surface, the sun is able to destroy them anyway. Many sungrazing comets follow a similar orbit, called the Kreutz Path, and collectively belong to a population called the Kreutz Group. In fact, close to 85% of the sungrazers seen by the SOHO satellite are on this orbital highway. Scientists think one extremely large sungrazing comet broke up hundreds, or even thousands, of years ago, and the current comets on the Kreutz Path are the leftover fragments of it. As clumps of remnants make their way back around the sun, we experience a sharp increase in sungrazing comets, which appears to be going on now. Comet Lovejoy, which reached perihelion on December 15, 2011 is the best known recent Kreutz-group sungrazer. And so far, it is the only one that NASA's solar-observing fleet has seen survive its trip around the sun. Comet ISON, an upcoming sungrazer with a perihelion of 730,000 miles on November 28, 2013, is not on the Kreutz Path. In fact, ISON's orbit suggests that it may gain enough momentum to escape the solar system entirely, and never return. Before it does so, it will pass within about 40 million miles from Earth on December 26th. More information on this topic available at: www.nasa.gov/content/goddard/timeline-of-comet-ison-s-dan... Credit: NASA's Goddard Space Flight Center NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Intermonolayer Friction and Surface Shear Viscosity of Lipid Bilayer Membranes

PubMed Central

den Otter, W. K.; Shkulipa, S. A.

2007-01-01

The flow behavior of lipid bilayer membranes is characterized by a surface viscosity for in-plane shear deformations, and an intermonolayer friction coefficient for slip between the two leaflets of the bilayer. Both properties have been studied for a variety of coarse-grained double-tailed model lipids, using equilibrium and nonequilibrium molecular dynamics simulations. For lipids with two identical tails, the surface shear viscosity rises rapidly with tail length, while the intermonolayer friction coefficient is less sensitive to the tail length. Interdigitation of lipid tails across the bilayer midsurface, as observed for lipids with two distinct tails, strongly enhances the intermonolayer friction coefficient, but hardly affects the surface shear viscosity. The simulation results are compared against the available experimental data. PMID:17468168

Exploring the volatile composition of comets C/2012 F6 (Lemmon) and C/2012 S1 (ISON) with ALMA

NASA Astrophysics Data System (ADS)

Bøgelund, Eva G.; Hogerheijde, Michiel R.

2017-08-01

Context. Comets formed in the outer and cold parts of the disk which eventually evolved into our solar system. Assuming that the comets have undergone no major processing, studying their composition provides insight in the pristine composition of the Solar Nebula. Aims: We derive production rates for a number of volatile coma species and explore how molecular line ratios can help constrain the uncertainties of these rates. Methods: We analyse observations obtained with the Atacama Large Millimeter/Submillimeter Array of the volatile composition of the comae of comets C/2012 F6 (Lemmon) and C/2012 S1 (ISON) at heliocentric distances of 1.45 AU and 0.56 AU, respectively. Assuming a Haser profile with constant outflow velocity, we model the line intensity of each transition using a 3D radiative transfer code and derive molecular production rates and parent scale lengths. Results: We report the first detection of CS in comet ISON obtained with the ALMA array and derive a parent scale length for CS of 200 km. Due to the high spatial resolution of ALMA, resulting in a synthesised beam with a size slightly smaller than the derived parent scale length (0.̋59 × 0.̋39 corresponding to (375 × 250) km at the distance of the comet at the time of observations), we are able to tentatively identify CS as a daughter species, I.e., a species produced in the coma and/or sublimated from icy grains, rather than a parent species. In addition we report the detection of several CH3OH transitions and confirm the previously reported detections of HCN, HNC and H2CO as well as dust in the coma of each comet, and report 3σ upper limits for HCO+. Conclusions: We derive molecular production rates relative to water of 0.2% for CS, 0.06-0.1% for HCN, 0.003-0.05% for HNC, 0.1-0.2% for H2CO and 0.5-1.0% for CH3OH, and show that the modelling uncertainties due to unknown collision rates and kinematic temperatures are modest and can be mitigated by available observations of different transitions of HCN.

Genotoxicity assessment of amaranth and allura red using Saccharomyces cerevisiae.

PubMed

Jabeen, Hafiza Sumara; ur Rahman, Sajjad; Mahmood, Shahid; Anwer, Sadaf

2013-01-01

Amaranth (E123) and Allura red (E129), very important food azo dyes used in food, drug, paper, cosmetic and textile industries, were assessed for their genotoxic potential through comet assay in yeast cells. Comet assay was standardized by with different concentration of H(2)O(2). Concentrations of Amaranth and Allura red were maintained in sorbitol buffer starting from 9.76 to 5,000 μg/mL and 1 × 10(4) cells were incubated at two different incubation temperatures 28 and 37°C. Amaranth (E123) and Allura red (E129) were found to exhibit their genotoxic effect directly in Saccharomyces cerevisiae. No significant genotoxic activity was observed for Amaranth and Allura red at 28°C but at 37°C direct relation of Amaranth concentration with comet tail was significant and no positive relation was seen with time exposure factor. At 37°C the minimum concentration of Amaranth and Allura red at which significant DNA damage observed through comet assay was 1,250 μg/mL in 2nd h post exposure time. The results indicated that food colors should be carefully used in baking products as heavy concentration of food colors could affect the fermentation process of baking.

Comet 209P/LINEAR and the associated Camelopardalids meteor shower

NASA Astrophysics Data System (ADS)

Ye, Q.; Hui, M.; Wiegert, P.; Campbell-Brown, M.; Brown, P.; Weryk, R.

2014-07-01

Previous studies have suggested that comet 209P/LINEAR may produce strong meteor activity on the Earth on 2014 May 24. Here we present our observations and simulations prior to the event. We reanalyze the optical observations of P/LINEAR obtained during its 2009 apparition to model the corresponding meteor stream. We find that the comet is relatively depleted in dust production, with Afρ at 1-cm level within eight months around its perihelion. A syndyne simulation shows that the optical cometary tail is dominated by larger particles with β˜0.003. Numerical simulation of the cometary dust trails confirms the arrival of particles on 2014 May 24 from some of the 1798--1979 trails, with nominal radiant in the constellation of Camelopardalis. Given that the comet is found to be depleted in dust production, we concluded that a meteor storm may be unlikely. However, our simulation also shows that the size distribution of the arrived particles is skewed strongly towards larger particles, which, coupling with the result of the syndyne simulation, suggested that the event (if detectable) may be dominated by bright meteors. Preliminary results from the observations of P/LINEAR during its 2014 apparition as well as the Camelopardalids meteor shower will also be presented.

Evaluation of genotoxicity of the acute gamma radiation on earthworm Eisenia fetida using single cell gel electrophoresis technique (Comet assay).

PubMed

Sowmithra, K; Shetty, N J; Jha, S K; Chaubey, R C

2015-12-01

Earthworms (Eisenia fetida) most suitable biological indicators of radioactive pollution. Radiation-induced lesions in DNA can be considered to be molecular markers for early effects of ionizing radiation. Gamma radiation produces a wide spectrum of DNA. Some of these lesions, i.e., DNA strand breaks and alkali labile sites can be detected by the single-cell gel electrophoresis (SCGE) or comet assay by measuring the migration of DNA from immobilized nuclear DNA. E. fetida were exposed to different doses of gamma radiation, i.e., 1, 5, 10, 20, 30, 40 and 50Gy, and comet assay was performed for all the doses along with control at 1, 3 and 5h post irradiation to evaluate the genotoxicity of gamma radiation in this organism. The DNA damage was measured as percentage of comet tail DNA. A significant increase in DNA damage was observed in samples exposed to 5Gy and above, and the increase in DNA damage was dose dependent i.e., DNA damage was increased with increased doses of radiation. The highest DNA damage was noticed at 1h post irradiation and gradually decreased with time, i.e., at 3 and 5h post irradiation. The present study reveals that gamma radiation induces DNA damage in E. fetida and the comet assay is a sensitive and rapid method for its detection to detect genotoxicity of gamma radiation. Copyright © 2015 Elsevier B.V. All rights reserved.

Exploring Mercury Tail

NASA Image and Video Library

2008-08-26

As the MESSENGER spacecraft approached Mercury, the UVVS field of view was scanned across the planet's exospheric "tail," which is produced by the solar wind pushing Mercury's exosphere (the planet's extremely thin atmosphere) outward. This figure, recently published in Science magazine, shows a map of the distribution of sodium atoms as they stream away from the planet (see PIA10396); red and yellow colors represent a higher abundance of sodium than darker shades of blue and purple, as shown in the colored scale bar, which gives the brightness intensity in units of kiloRayleighs. The escaping atoms eventually form a comet-like tail that extends in the direction opposite that of the Sun for many planetary radii. The small squares outlined in black correspond to individual measurements that were used to create the full map. These measurements are the highest-spatial-resolution observations ever made of Mercury's tail. In less than six weeks, on October 6, 2008, similar measurements will be made during MESSENGER's second flyby of Mercury. Comparing the measurements from the two flybys will provide an unprecedented look at how Mercury's dynamic exosphere and tail vary with time. Date Acquired: January 14, 2008. http://photojournal.jpl.nasa.gov/catalog/PIA11076

The Sodium Tail of the Moon

NASA Technical Reports Server (NTRS)

Matta, M.; Smith, S.; Baumgardner, J.; Wilson, J.; Martinis, C.; Mendillo, M.

2009-01-01

During the few days centered about new Moon, the lunar surface is optically hidden from Earth-based observers. However, the Moon still offers an observable: an extended sodium tail. The lunar sodium tail is the escaping "hot" component of a coma-like exosphere of sodium generated by photon-stimulated desorption, solar wind sputtering and meteoroid impact. Neutral sodium atoms escaping lunar gravity experience solar radiation pressure that drives them into the anti-solar direction forming a comet-like tail. During new Moon time, the geometry of the Sun, Moon and Earth is such that the anti-sunward sodium flux is perturbed by the terrestrial gravitational field resulting in its focusing into a dense core that extends beyond the Earth. An all-sky camera situated at the El Leoncito Observatory (CASLEO) in Argentina has been successfully imaging this tail through a sodium filter at each lunation since April 2006. This paper reports on the results of the brightness of the lunar sodium tail spanning 31 lunations between April 2006 and September 2008. Brightness variability trends are compared with both sporadic and shower meteor activity, solar wind proton energy flux and solar near ultra violet (NUV) patterns for possible correlations. Results suggest minimal variability in the brightness of the observed lunar sodium tail, generally uncorrelated with any single source, yet consistent with a multi-year period of minimal solar activity and non-intense meteoric fluxes.

Shape, Density, and Geology of the Nucleus of Comet 103P/Hartley 2

NASA Technical Reports Server (NTRS)

Thomas, P.C.; A'hearn, Michael F.; Veverka, Joseph; Belton, Michael J. S.; Kissel, Jochen; Belton, Michael J. S.; Klaasen, Kenneth P.; McFadden, Lucy A.; Melosh, H. Jay; Schultz, Peter H.;

Modeling the cometary environment using a fluid approach

NASA Astrophysics Data System (ADS)

Shou, Yinsi

Comets are believed to have preserved the building material of the early solar system and to hold clues to the origin of life on Earth. Abundant remote observations of comets by telescopes and the in-situ measurements by a handful of space missions reveal that the cometary environments are complicated by various physical and chemical processes among the neutral gases and dust grains released from comets, cometary ions, and the solar wind in the interplanetary space. Therefore, physics-based numerical models are in demand to interpret the observational data and to deepen our understanding of the cometary environment. In this thesis, three models using a fluid approach, which include important physical and chemical processes underlying the cometary environment, have been developed to study the plasma, neutral gas, and the dust grains, respectively. Although models based on the fluid approach have limitations in capturing all of the correct physics for certain applications, especially for very low gas density environment, they are computationally much more efficient than alternatives. In the simulations of comet 67P/Churyumov-Gerasimenko at various heliocentric distances with a wide range of production rates, our multi-fluid cometary neutral gas model and multi-fluid cometary dust model have achieved comparable results to the Direct Simulation Monte Carlo (DSMC) model, which is based on a kinetic approach that is valid in all collisional regimes. Therefore, our model is a powerful alternative to the particle-based model, especially for some computationally intensive simulations. Capable of accounting for the varying heating efficiency under various physical conditions in a self-consistent way, the multi-fluid cometary neutral gas model is a good tool to study the dynamics of the cometary coma with different production rates and heliocentric distances. The modeled H2O expansion speeds reproduce the general trend and the speed's nonlinear dependencies of production rate and heliocentric distance, which are found in remote observations. In the multi-fluid dust model, we use a newly developed numerical mesh to resolve the real shaped nucleus in the center and to facilitate prescription of the outer boundary conditions that accommodate the rotating frame. The model studies the effects of the rotating nucleus and the cometary activity in time-dependent simulations for the first time. The result also suggests that the rotation of the nucleus explains why there is no clear dust speed dependence on size in some of the dust observations. We developed a new multi-species comet MHD model to simulate the plasma environment of comet C/2006 P1 (McNaught) over a wide range of heliocentric distances from 0.17 AU to 1.75 AU, with the constraints provided by remote and in situ observations. Typical subsolar standoff distances of bow shock and contact surface are modeled and presented to characterize the solar wind interaction of the comet at various heliocentric distances. In addition, the model is also the first one to be used to study the composition and dynamics in the distant cometary tail. The results agree well with the measured water group ion abundances from the Ulysses/SWICS 1.7 AU down-tail from the comet and the velocity and temperature measured by Ulysses/SWOOPS.

Solar wind interaction with comet 67P: Impacts of corotating interaction regions

NASA Astrophysics Data System (ADS)

Edberg, N. J. T.; Eriksson, A. I.; Odelstad, E.; Vigren, E.; Andrews, D. J.; Johansson, F.; Burch, J. L.; Carr, C. M.; Cupido, E.; Glassmeier, K.-H.; Goldstein, R.; Halekas, J. S.; Henri, P.; Koenders, C.; Mandt, K.; Mokashi, P.; Nemeth, Z.; Nilsson, H.; Ramstad, R.; Richter, I.; Wieser, G. Stenberg

2016-02-01

We present observations from the Rosetta Plasma Consortium of the effects of stormy solar wind on comet 67P/Churyumov-Gerasimenko. Four corotating interaction regions (CIRs), where the first event has possibly merged with a coronal mass ejection, are traced from Earth via Mars (using Mars Express and Mars Atmosphere and Volatile EvolutioN mission) to comet 67P from October to December 2014. When the comet is 3.1-2.7 AU from the Sun and the neutral outgassing rate ˜1025-1026 s-1, the CIRs significantly influence the cometary plasma environment at altitudes down to 10-30 km. The ionospheric low-energy (˜5 eV) plasma density increases significantly in all events, by a factor of >2 in events 1 and 2 but less in events 3 and 4. The spacecraft potential drops below -20 V upon impact when the flux of electrons increases. The increased density is likely caused by compression of the plasma environment, increased particle impact ionization, and possibly charge exchange processes and acceleration of mass-loaded plasma back to the comet ionosphere. During all events, the fluxes of suprathermal (˜10-100 eV) electrons increase significantly, suggesting that the heating mechanism of these electrons is coupled to the solar wind energy input. At impact the magnetic field strength in the coma increases by a factor of 2-5 as more interplanetary magnetic field piles up around the comet. During two CIR impact events, we observe possible plasma boundaries forming, or moving past Rosetta, as the strong solar wind compresses the cometary plasma environment. We also discuss the possibility of seeing some signatures of the ionospheric response to tail disconnection events.

Analysis of the perihelic passages of the comet 1P/Halley in 1910 and in 1986

NASA Astrophysics Data System (ADS)

Voelzke, Marcos Rincon

2016-07-01

This work is based on a systematic analysis of images of 1P/Halley comet collected during its penultimate and ultimate approaches, i.e., in 1910 and in 1986. The present research basically characterised, identified, classified, measured and compared some of the tail structures of comet 1P/Halley like DEs, wavy structures and solitons. The images illustrated in the Atlas of Comet Halley 1910 II (Donn et al., 1986), which shows the comet in its 1910 passage, were compared with the images illustrated in The International Halley Watch Atlas of Large-Scale Phenomena (Brandt et al., 1992), which shows the comet in its 1986 passage. While two onsets of DEs were discovered after the perihelion passage in 1910, the average value of the corrected cometocentric velocity Vc was (57 ± 15) km/s; ten were discovered after the perihelion passage in 1986 with an average of corrected velocities equal to (130 ± 37) km/s. The mean value of the corrected wavelength of wavy structures, in 1910, is equal to (1.7 ± 0.1) x 10 ^{6} km and in 1986 is (2.2 ± 0.2) x 10 ^{6} km. The mean value of the amplitude A of the wave, in 1910, is equal to (1.4 ± 0.1) x 10 ^{5} km and in 1986 it is equal to (2.8 ± 0.5) x 10 ^{5} km. The goals of this research are to report the results obtained from the analysis of the P/Halleýs 1910 and 1986 images, to provide empirical data for comparison and to form the input for future physical/theoretical work.

Comparative analysis of images of comet 1P/Halley in their perihelion passages in 1910 and 1986

NASA Astrophysics Data System (ADS)

Voelzke, Marcos Rincon

This work is based on a systematic analysis of images of 1P/Halley comet collected during its penultimate and ultimate approaches, i.e., in 1910 and in 1986. The present research basically characterised, identified, classified, measured and compared some of the tail structures of comet 1P/Halley like DEs, wavy structures and solitons. The images illustrated in the Atlas of Comet Halley 1910 II (Donn et al., 1986), which shows the comet in its 1910 passage, were compared with the images illustrated in The International Halley Watch Atlas of Large-Scale Phenomena (Brandt et al., 1992), which shows the comet in its 1986 passage. While two onsets of DEs were discovered after the perihelion passage in 1910, the average value of the corrected cometocentric velocity Vc was (57 ± 15) km s (-1) ; ten were discovered after the perihelion passage in 1986 with an average of corrected velocities equal to (130 ± 37) km s (-1) .The mean value of the corrected wavelength of wavy structures, in 1910, is equal to (1.7 ± 0.1) x 10 (6) km and in 1986 is (2.2 ± 0.2) x 10 (6) km. The mean value of the amplitude A of the wave, in 1910, is equal to (1.4 ± 0.1) x 10 (5) km and in 1986 it is equal to (2.8 ± 0.5) x 10 (5) km. The goals of this research are to report the results obtained from the analysis of the P/Halleýs 1910 and 1986 images, to provide empirical data for comparison and to form the input for future physical/theoretical work.

Analysis of the morphological structures of comet 1P/Halley in their perihelion passages in 1910 and 1986

NASA Astrophysics Data System (ADS)

Voelzke, Marcos Rincon

2015-08-01

This work is based on a systematic analysis of images of 1P/Halley comet collected during its penultimate and ultimate approaches, i.e., in 1910 and in 1986. The present research basically characterised, identified, classified, measured and compared some of the tail structures of comet 1P/Halley like DEs, wavy structures and solitons. The images illustrated in the Atlas of Comet Halley 1910 II (Donn et al., 1986), which shows the comet in its 1910 passage, were compared with the images illustrated in The International Halley Watch Atlas of Large-Scale Phenomena (Brandt et al., 1992), which shows the comet in its 1986 passage. While two onsets of DEs were discovered after the perihelion passage in 1910, the average value of the corrected cometocentric velocity Vc was (57 ± 15) km/s ; ten were discovered after the perihelion passage in 1986 with an average of corrected velocities equal to (130 ± 37) km/s .The mean value of the corrected wavelength of wavy structures, in 1910, is equal to (1.7 ± 0.1) x 106 km and in 1986 is (2.2 ± 0.2) x 106 km. The mean value of the amplitude A of the wave, in 1910, is equal to (1.4 ± 0.1) x 105 km and in 1986 it is equal to (2.8 ± 0.5) x 105 km. The goals of this research are to report the results obtained from the analysis of the P/Halleýs 1910 and 1986 images, to provide empirical data for comparison and to form the input for future physical/theoretical work.

The near ultraviolet spectra of comets P/Brorsen-Metcalf and Austin

NASA Technical Reports Server (NTRS)

Cochran, William D.; Odell, C. R.; Miller, C. O.; Cochran, Anita L.; Opal, C. B.; Valk, D.; Barker, E. S.

1990-01-01

Results are reported on spectrophotometric observations of comets P/Brorsen-Metcalf and Austin from 3000 to 3600 A at a spectral resolution of about 1.8 A. The strongest features are the OH(A-X) 0-0 and 1-1 bands, and the NH(A-X) 0-0 bands. For the first time, the OH(A-X) 0-1 band was clearly found. The existence of the CN(B-X) 2-1 and 3-2 bands were verified and measured. A feature at 3258 A that was first seen in uncalibrated spectra was detected, and was identified as the NH singlet (c-a) 0-0 transition. The CO2(+) features at 3378, 3504, and 3512 A were also firmly identified. This ion was reported as being present in the tail of Comet Bester (1984 I) by Swings and Page (1950). The identification of a weak feature at 3547 A was proposed as the fundamental transition of H2CO, which would make this the first optical cometary detection of this molecule which is very abundant in giant molecular clouds.

Preliminary study on evaluation of the pancreatic tail observable limit of transabdominal ultrasonography using a position sensor and CT-fusion image.

PubMed

Sumi, Hajime; Itoh, Akihiro; Kawashima, Hiroki; Ohno, Eizaburo; Itoh, Yuya; Nakamura, Yosuke; Hiramatsu, Takeshi; Sugimoto, Hiroyuki; Hayashi, Daijuro; Kuwahara, Takamichi; Morishima, Tomomasa; Kawai, Manabu; Furukawa, Kazuhiro; Funasaka, Kohei; Nakamura, Masanao; Miyahara, Ryoji; Katano, Yoshiaki; Ishigami, Masatoshi; Ohmiya, Naoki; Goto, Hidemi; Hirooka, Yoshiki

2014-08-01

Transabdominal ultrasonography (US) is commonly used for the initial screening of bilio-pancreatic diseases in Asian countries due to its widespread availability, the non-invasiveness and the cost-effectiveness. However, it is considered that US has limits to observe the area, namely the blind area. The observation of the pancreatic tail is particularly difficult. The goal of this study was to examine the pancreatic tail region that cannot be visualized on transverse scanning of the upper abdomen using US with spatial positional information and factors related to visualization, and observation of the tail from the splenic hilum. Thirty-nine patients with pancreatic/biliary tract disease underwent CT and US with GPS-like technology and fusion imaging for measurement of the real pancreatic length and the predicted/real unobservable (PU and RU) length of the pancreatic tail. RU from US on transverse scanning and the real pancreatic length were used to determine the unobservable area (UA: RU/the real pancreatic length). Relationships of RU with physical and hematological variables that might influence visualization of the pancreatic tail were investigated. The real pancreatic length was 160.9 ± 16.4mm, RU was 41.0 ± 17.8mm, and UA was 25.3 ± 10.4%. RU was correlated with BMI (R=0.446, P=0.004) and waist circumferences (R=0.354, P=0.027), and strongly correlated with PU (R=0.788, P<0.001). The pancreatic tail was visible from the splenic hilum in 22 (56%) subjects and was completely identified in 13 (33%) subjects. Combined GPS-like technology with fusion imaging was useful for the objective estimation of the pancreatic blind area. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Catching Comet's Particles in the Earth's Atmosphere by Using Balloons

NASA Astrophysics Data System (ADS)

Potashko, Oleksandr; Viso, Michel

The project is intended to catch cometary particles in the atmosphere by using balloons. The investigation is based upon knowledge that the Earth crosses the comet’s tails during the year. One can catch these particles at different altitudes in the atmosphere. So, we will be able to gradually advance in the ability to launch balloons from low to high altitudes and try to catch particles from different comet tails. The maximum altitude that we have to reach is 40 km. Both methods - distance observation and cometary samples from mission Stardust testify to the presence of organic components in comet’s particles. It would be useful to know more details about this organic matter for astrobiology; besides, the factor poses danger to the Earth. Moreover, it is important to prove that it is possible to get fundamental scientific results at low cost. In the last 5 years launching balloons has become popular and this movement looks like hackers’ one - as most of them occur without launch permission to airspace. The popularity of ballooning is connected with low cost of balloon, GPS unit, video recording unit. If you use iPhone, you have a light solution with GPS, video, picture and control function in one unit. The price of balloon itself begins from $50; it depends on maximum altitude, payload weight and material. Many university teams realized balloon launching and reached even stratosphere at an altitude of 33 km. But most of them take only video and picture. Meanwhile, it is possible to carry out scientific experiments by ballooning, for example to collect comet particles. There is rich experience at the moment of the use of mineral, chemical and isotopic analysis techniques and data of the comet’s dust after successful landing of StarDust capsule with samples in 2006. Besides, we may use absolutely perfect material to catch particles in the atmosphere, which was used by cosmic missions such as Stardust and Japanese Hayabusa. As to balloon launches, we could use Indian Space Research Organization experience that launched a balloon to stratosphere in 2009 and successfully caught particles with organics at an altitude of 42 km. The main aim of the project is to catch cometary particles by using balloons and to make this method steady and reliable. Why are the comet particles interesting? The nature of a comet is full of puzzles; many researchers think that comets may give keys to the origin of the Solar System and origin of life on the Earth. 2014 and 2015 are special years for comet science: mission Rozetta will reach the vicinity of the comet 67P/Churyumov-Gerasimenko - 10 years after leaving the Earth. Using astronomic data, one may choose date for ballooning, specify the altitude of comet particles by photometry and laser measurement of particle outburst. After height measurement one may launch a balloon. For example, for Draconids particles (Parent comet: 21PGiacobini-Zinner) the expected time of outburst maximum - hence that for catching is 22:42 UT, October 6, 2014. The best conditions for catching will be in Greenland and extreme north-eastern part of North America. Draconids are very convenient for the initial stage of the project - the altitude of observed Draconids outburst is 10 km. One may catch them above 10 km, e.g. 10500 m. We consider ballooning is quite a good method to get experimental data as an additional technique in comparison with big space missions. Moreover, it might be a part of cosmic mission to other planets such as Mars and Venus. The approach of the project is to make targeting catch of comet particles. The method consists of choosing the right place and time for ballooning.

The Science of Sungrazers, Sunskirters, and Other Near-Sun Comets

NASA Astrophysics Data System (ADS)

Jones, Geraint H.; Knight, Matthew M.; Battams, Karl; Boice, Daniel C.; Brown, John; Giordano, Silvio; Raymond, John; Snodgrass, Colin; Steckloff, Jordan K.; Weissman, Paul; Fitzsimmons, Alan; Lisse, Carey; Opitom, Cyrielle; Birkett, Kimberley S.; Bzowski, Maciej; Decock, Alice; Mann, Ingrid; Ramanjooloo, Yudish; McCauley, Patrick

2018-02-01

This review addresses our current understanding of comets that venture close to the Sun, and are hence exposed to much more extreme conditions than comets that are typically studied from Earth. The extreme solar heating and plasma environments that these objects encounter change many aspects of their behaviour, thus yielding valuable information on both the comets themselves that complements other data we have on primitive solar system bodies, as well as on the near-solar environment which they traverse. We propose clear definitions for these comets: We use the term near-Sun comets to encompass all objects that pass sunward of the perihelion distance of planet Mercury (0.307 AU). Sunskirters are defined as objects that pass within 33 solar radii of the Sun's centre, equal to half of Mercury's perihelion distance, and the commonly-used phrase sungrazers to be objects that reach perihelion within 3.45 solar radii, i.e. the fluid Roche limit. Finally, comets with orbits that intersect the solar photosphere are termed sundivers. We summarize past studies of these objects, as well as the instruments and facilities used to study them, including space-based platforms that have led to a recent revolution in the quantity and quality of relevant observations. Relevant comet populations are described, including the Kreutz, Marsden, Kracht, and Meyer groups, near-Sun asteroids, and a brief discussion of their origins. The importance of light curves and the clues they provide on cometary composition are emphasized, together with what information has been gleaned about nucleus parameters, including the sizes and masses of objects and their families, and their tensile strengths. The physical processes occurring at these objects are considered in some detail, including the disruption of nuclei, sublimation, and ionisation, and we consider the mass, momentum, and energy loss of comets in the corona and those that venture to lower altitudes. The different components of comae and tails are described, including dust, neutral and ionised gases, their chemical reactions, and their contributions to the near-Sun environment. Comet-solar wind interactions are discussed, including the use of comets as probes of solar wind and coronal conditions in their vicinities. We address the relevance of work on comets near the Sun to similar objects orbiting other stars, and conclude with a discussion of future directions for the field and the planned ground- and space-based facilities that will allow us to address those science topics.

No correlation is found for vegetables between antioxidant capacity and potential benefits in improving antioxidant function in aged rats

PubMed Central

Ji, Linlin; Gao, Weina; Wei, Jingyu; Wu, Jianquan; Yang, Jijun; Meng, Bin; Guo, Changjiang

2014-01-01

Vegetables vary greatly in antioxidant capacity in vitro. This study was to investigate the actions of three vegetables different remarkably in antioxidant capacity in vitro on antioxidant function in aged rats. Sixty female aged Wistar rats were randomly assigned to the control, lotus root, rape and cucumber (high, moderate and low in antioxidant capacity, respectively) treated groups. After 6 weeks of feeding, there were no significant differences in plasma FRAP value and contents of vitamin C, vitamin E, uric acid and total phenolics among different groups, whereas the content of reduced glutathione was significantly higher in the rape and cucumber groups. Plasma superoxide dismutase activity also was significantly increased in the rape and cucumber groups. Plasma contents of malondialdehyde, carbonyls and hemolysis were decreased significantly in 3 vegetable-treated groups. Meanwhile, urinary 8-hydroxy-2'-deoxyguanosine excretion was lower significantly in the rape group and the ratio of comet tail length to total length of blood mononuclear cells was decreased significantly in 3 vegetables treated groups. These results suggest that 3 vegetables tested are effective in improving antioxidant function to some extent in aged rats and no correlation is found between antioxidant capacity in vitro and improvements of antioxidant function. The benefits observed in this study may come from additive or synergistic combinations of antioxidants contained in vegetables. PMID:24895483

Genotoxicity of air borne particulates assessed by comet and the Salmonella mutagenicity test in Jeddah, Saudi Arabia.

PubMed

Elassouli, Sufian M; Alqahtani, Mohamed H; Milaat, Waleed

2007-09-01

Fine airborne respirable particulates less than 10 micrometer (PM10) are considered one of the top environmental public health concerns, since they contain polycyclic aromatic hydrocarbons (PAHs) which are among the major carcinogenic compounds found in urban air. The objective of this study is to assess the genotoxicity of the ambient PM10 collected at 11 urban sites in Jeddah, Saudi Arabia. The PM10 extractable organic matter (EOM) was examined for its genotoxicity by the single cell gel electrophoresis (SCGE) comet assay and the Salmonella mutagenicity (Ames) test .Gas chromatography-mass spectrometry was used to quantify 16 PAH compounds in four sites. Samples from oil refinery and heavy diesel vehicles traffic sites showed significant DNA damage causing comet in 20-44% of the cells with tail moments ranging from 0.5-2.0 compared to samples from petrol driven cars and residential area, with comet in less than 2% of the cells and tail moments of < 0.02. In the Ames test, polluted sites showed indirect mutagenic response and caused 20-56 rev/ m3, mean while residential and reference sites caused 2-15 rev /m3. The genotoxicity of the EOM in both tests directly correlated with the amount of organic particulate and the PAHs concentrations in the air samples. The PAHs concentrations ranged between 0.83 ng/m3 in industrial and heavy diesel vehicles traffic sites to 0.18 ng /m3 in the residential area. Benzo(ghi)pyrene was the major PAH components and at one site it represented 65.4 % of the total PAHs. Samples of the oil refinery site were more genotoxic in the SCGE assay than samples from the heavy diesel vehicles traffic site, despite the fact that both sites contain almost similar amount of PAHs. The opposite was true for the mutagenicity in the Ames test. This could be due to the nature of the EOM in both sites. These findings confirm the genotoxic potency of the PM10 organic extracts to which urban populations are exposed.

Evaluation of the genetic alterations in direct and indirect exposures of hexavalent chromium [Cr(VI)] in leather tanning industry workers North Arcot District, South India.

PubMed

Balachandar, Vellingiri; Arun, Meyyazhagan; Mohana Devi, Subramaniam; Velmurugan, Palanivel; Manikantan, Pappusamy; Karthick Kumar, Alagamuthu; Sasikala, Keshavarao; Venkatesan, Chinnakulandai

2010-10-01

The focal aim of the present study was to identify the genetic alterations occurring in the tannery workers and surrounding inhabitants chronically exposed to hexavalent chromium [Cr(VI)]. A total of 108 samples which includes 72 exposed subjects [36 directly exposed (DE) subjects and 36 indirectly exposed (IE) subjects] and 36 controls were recruited for this study. The exposed subjects and controls were selected based on the Cr level present in air and their urine. Directly exposed subjects were categorized based on their work duration in the tannery industries, whereas the indirectly exposed subjects were categorized based on their year of residence in the place adjacent to tannery industries for more than 3 decades. Controls were normal and healthy. Age was matched for the exposed subjects and controls. The exposed subjects as well as the controls were categorized based on their age (group I, <40 years; group II, >41 years). Cell cultures were established from blood samples (5 ml from each subject) collected from the subjects (exposed subjects and controls) after obtaining informed consent. G-banding (Giemsa staining) of the cultures, micronucleus (MN) assay and comet assay were used to identify the genetic alterations of individuals exposed to Cr(VI) in comparison with the controls. A higher degree of total CA [12 ± 8.49 (21-25 years)] and MN [18.69 ± 7.39 (11-15 years)] was found in DE subjects compared to other groups. In IE subjects, elevated levels of CA [5.67 ± 1.15 (51-60 years)] and MN [25 ± 9.89 (71-80 years)] were observed. As expected, controls exhibited minimal number of alterations. The overall CA frequency due to Cr exposure was significantly different from that of the controls for both chromatid and chromosome type aberrations (P < 0.05 by ANOVA). The MN/1,000 binucleated cells were significantly increased (P < 0.05) in the peripheral lymphocytes of DE and IE subjects in comparison with controls. The mean tail length of comet assay for DE, IE and controls were analyzed. The mean tail length of DE subjects [4.21 (3.21-10.98)] was higher compared to that of IE subjects [3.98 (2.98-11.27)] and controls [3.01 (2.68-9.40)]. In conclusion, this work shows a clear genotoxic effect associated with chromium exposure, both directly and indirectly. Our result reinforces the higher sensitivity of cytogenetic assays for the biomonitoring of occupationally exposed populations. There is a strong need to educate those who work with potentially hazardous heavy about its adverse effects and highlight the importance of using protective measures.

Possible Dust Models for C/2012 S1

NASA Astrophysics Data System (ADS)

Yanamandra-Fisher, P. A.

2014-12-01

Comet C/2012 S1 (ISON) provided a great opportunity to study a dynamically new Oort-cloud comet on its initial and only passage through the inner solar system. Contrary to expectations, the comet's activity fluctuated from high through a quiescent phase, and a major outburst days before its perihelion passage, ending in a dramatic race to complete disintegration on perihelion day, 28 November 2013. Amateur observations to professional ground-based, sub-orbital telescopes indicate the various changes of visible factors such as Afrho, a proxy for dust activity, and the measured production rates for water, consistent with the disintegration of the nucleus. Hines et al. (2013; ApJ Lett. 780) detected positive polarization in the inner coma and negative polarization in the outer coma, indicative of a jet, independently confirmed by Li et al. (2013, ApJ Lett., 779). Thermal emission observations of the comet pre-perihelion from NAOJ/Subaru/COMICS, a mid-infrared spectrometer, indicated a body with an equivalent brightness temperature of 265K (Ootsubo et al., 2013, ACM, Helsinki,FI); thermal observations acquired at the NASA/Infrared Telescope Facility (IRTF) with The Aerospace Corporation spectrometer (BASS, PI. R. Russell), before and after the November 12, 2013 outburst observed by the CIOC_ISON amateur network, indicates a brightness temperature of 330K and the presence, albeit weak, of the 11.3-micron crystalline silicate feature (Sitko et al., 2014, LPI abstract 1537). A Monte Carlo comet dust tail model, applied to extract the dust environment parameters of comet C/2012 S1 (ISON) from both Earth-based and Solar and Heliospheric Observatory (SOHO) calibrated observations, performed from about 6 AU (inbound), to right after perihelion passage, when just a small portion of the original comet nucleus survived in the form of a cloud of tiny particles, indicates that particles underwent disintegration and fragmentation (Moreno et al., 2014, ApJ Lett., 791). Ongoing work on possible dust models that incorporate both the observed polarization and thermal emission will be discussed.

Temporal analysis of the morphological structures of comet 1P/Halley in the perihelion passages in 1910 and 1986

NASA Astrophysics Data System (ADS)

Voelzke, M. R.

2016-11-01

This work is based on a systematic analysis of images of 1P/Halley comet collected during its penultimate and ultimate approaches, i.e., in 1910 and in 1986. The present research basically characterised, identified, classified, measured and compared some of the tail structures of comet 1P/Halley like DEs, wavy structures and solitons. The images illustrated in the Atlas of Comet Halley 1910 II (Donn et al., 1986), which shows the comet in its 1910 passage, were compared with the images illustrated in The International Halley Watch Atlas of Large-Scale Phenomena (Brandt et al., 1992), which shows the comet in its 1986 passage. While two onsets of DEs were discovered after the perihelion passage in 1910, the average value of the corrected cometocentric velocity Vc was (57 ± 15) km/s; ten were discovered after the perihelion passage in 1986 with an average of corrected velocities equal to (130 ± 37) km/s. The mean value of the corrected wavelength of wavy structures, in 1910, is equal to (1.7 ± 0.1) x 10^6 km and in 1986 is (2.2 ± 0.2) x 10^6 km. The mean value of the amplitude A of the wave, in 1910, is equal to (1.4 ± 0.1) x 10^5 km and in 1986 it is equal to (2.8 ± 0.5) x 10^5 km. The goals of this research are to report the results obtained from the analysis of the P/Halleýs 1910 and 1986 images, to provide empirical data for comparison and to form the input for future physical/theoretical work. Referências [1] Brandt, J.C., Niedner Jr., M.B. & Rahe, J. 1992. International Halley Watch Atlas of Large-Scale Phenomena. University of Colorado-Boulder (printed by Johnson Printing Co., Boulder, CO) [2] Donn, B., Rahe, J. & Brandt, J.C. 1986. Atlas of Comet Halley 1910 II. NASA SP-488

Numerical calculation of boundary layers and wake characteristics of high-speed trains with different lengths

PubMed Central

Zhou, Dan; Niu, Jiqiang

2017-01-01

Trains with different numbers of cars running in the open air were simulated using the delayed detached-eddy simulation (DDES). The numbers of cars included in the simulation are 3, 4, 5 and 8. The aim of this study was to investigate how train length influences the boundary layer, the wake flow, the surface pressure, the aerodynamic drag and the friction drag. To certify the accuracy of the mesh and methods, the drag coefficients from numerical simulation of trains with 3 cars were compared with those from the wind tunnel test, and agreement was obtained. The results show that the boundary layer is thicker and the wake vortices are less symmetric as the train length increases. As a result, train length greatly affects pressure. The upper surface pressure of the tail car reduced by 2.9%, the side surface pressure of the tail car reduced by 8.3% and the underneath surface pressure of the tail car reduced by 19.7% in trains that included 3 cars to those including 8 cars. In addition, train length also has a significant effect on the friction drag coefficient and the drag coefficient. The friction drag coefficient of each car in a configuration decreases along the length of the train. In a comparison between trains consisting of 3 cars to those consisting of 8 cars, the friction drag coefficient of the tail car reduced by 8.6% and the drag coefficient of the tail car reduced by 3.7%. PMID:29261758

Genotoxicity following Organophosphate Pesticides Exposure among Orang Asli Children Living in an Agricultural Island in Kuala Langat, Selangor, Malaysia.

PubMed

Sutris, J M; How, V; Sumeri, S A; Muhammad, M; Sardi, D; Mohd Mokhtar, M T; Muhammad, H; Ghazi, H F; Isa, Z M

2016-01-01

Agriculture is an important sector for the Malaysian economy. The use of pesticides in agriculture is crucial due to its function in keeping the crops from harmful insects. Children living near agricultural fields are at risk of pesticide poisoning. To evaluate the genotoxic risk among children who exposed to pesticides and measure DNA damage due to pesticides exposure. In a cross-sectional study 180 Orang Asli Mah Meri children aged between 7 and 12 years were studied. They were all living in an agricultural island in Kuala Langat, Selangor, Malaysia. The data for this study were collected via modified validated questionnaire and food frequency questionnaire, which consisted of 131 food items. 6 urinary organophosphate metabolites were used as biomarkers for pesticides exposure. For genotoxic risk or genetic damage assessment, the level of DNA damage from exfoliated buccal mucosa cells was measured using the comet assay electrophoresis method. Out of 180 respondents, 84 (46.7%) showed positive traces of organophosphate metabolites in their urine. Children with detectable urinary pesticide had a longer tail length (median 43.5; IQR 30.9 to 68.1 μm) than those with undetectable urinary pesticides (median 24.7; IQR 9.5 to 48.1 μm). There was a significant association between the extent of DNA damage and the children's age, length of residence in the area, pesticides detection, and frequency of apple consumption. The organophosphate genotoxicity among children is associated with the amount of exposure (detectability of urinary pesticide) and length of residence in (exposure) the study area.

Is lack of sleep capable of inducing DNA damage in aged skin?

PubMed

Kahan, V; Ribeiro, D A; Egydio, F; Barros, L A; Tomimori, J; Tufik, S; Andersen, M L

2014-01-01

Skin naturally changes with age, becoming more fragile. Various stimuli can alter skin integrity. The aim of this study was to evaluate whether sleep deprivation affects the integrity of DNA in skin and exacerbates the effects of aging. Fifteen-month old female Hairless mice underwent 72 h of paradoxical sleep deprivation or 15 days of chronic sleep restriction. Punch biopsies of the skin were taken to evaluate DNA damage by single cell gel (comet) assay. Neither paradoxical sleep deprivation nor sleep restriction increased genetic damage, measured by tail movement and tail intensity values. Taken together, the findings are consistent with the notion that aging overrides the effect of sleep loss on the genetic damage in elderly mice. © 2014 S. Karger AG, Basel.

Theories of comets to the age of Laplace

NASA Astrophysics Data System (ADS)

Heidarzadeh, Tofigh

Although the development of ideas about cometary motion has been investigated in several projects, a comprehensive and detailed survey of physical theories of comets has not been conducted. The available works either illustrate relatively short periods in the history of physical cometology or portray a landscape view without adequate details. The present study is an attempt to depict the details of the major physical theories of comets from Aristotle to the age of Laplace. The basic question from which this project originated was simple: how did natural philosophers and astronomers define the nature and place of a new category of celestial objects--the comets--after Brahe's estimation of cometary distances? However, a study starting merely from Brahe without covering classical and medieval thought about comets would be incomplete. Thus, based on the fundamental physical characteristics attributed to comets, the history of cometology may be divided into three periods: from Aristotle to Brahe, in which comets were assumed to be meteorological phenomena; from Brahe to Newton, when comets were admitted as celestial bodies but with unknown trajectories; and from Newton to Laplace, in which they were treated as members of the solar system having more or less the same properties of the planets. By estimating the mass of comets in the 1800s, Laplace diverted cometology into a different direction wherein they were considered among the smallest bodies in the solar system and deprived of the most important properties that had been used to explain their physical constitution during the previous two millennia. Ideas about the astrological aspects of comets are not considered in this study. Also, topics concerning the motion of comets are explained to the extent that is helpful in illustrating their physical properties. The main objective is to demonstrate the foundations of physical theories of comets, and the interaction between observational and mathematical astronomy, and the physical sciences in defining the properties of comets. The number of publications containing ideas about the physical properties of comets shows a radical increase in the third period of our account of cometology. From numerous general astronomy texts or treatises devoted to comets in this period, those were discussed here that either proposed a different theory of comets or criticized the physical aspects of contemporary theories. The survey includes only works published in England and France, and a few in German-speaking countries. Although Laplace's achievement in estimation of cometary masses became the basis of modern cometology, our current ideas about the actual size, mass and composition of comets, and the processes by which the coma and tail are formed have been developed only since the mid twentieth century. Post-Laplacian developments in the study of comets are highlighted in an appendix, which briefly reviews the major achievements in the observational and theoretical study of comets in the nineteenth and the twentieth centuries. Although the present study is mainly focused on the physical theories of comets, its results will be relevant to studies in the history of geology, planetary science, and astrology. On the other hand, those results may initiate new studies about educational practices for physics and astronomy in post- Newtonian Europe, the ways that different parts of Newton's physical, astronomical and cosmological ideas evolved after him, and the influence of cometary studies on the foundation of astrophysics.

Large momentum part of a strongly correlated Fermi gas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tan, Shina

2008-12-15

It is well known that the momentum distribution of the two-component Fermi gas with large scattering length has a tail proportional to 1/k{sup 4} at large k. We show that the magnitude of this tail is equal to the adiabatic derivative of the energy with respect to the reciprocal of the scattering length, multiplied by a simple constant. This result holds at any temperature (as long as the effective interaction radius is negligible) and any large scattering length; it also applies to few-body cases. We then show some more connections between the 1/k{sup 4} tail and various physical quantities, includingmore » the pressure at thermal equilibrium and the rate of change of energy in a dynamic sweep of the inverse scattering length.« less

The Meteoroid Fluence at Mars Due to Comet C/2013 A1 (Siding Spring)

NASA Technical Reports Server (NTRS)

Moorhead, A.; Wiegert, P.; Blaauw, R.; McCarty, C.; Kingery, A.; Cooke, W.

2014-01-01

Long-period comet C/2013 A1 (Siding Spring) will experience a close encounter with Mars on 2014 Oct 19. A collision between the comet and the planet has been ruled out, but the comet's coma may envelop Mars and its man-made satellites. By the time of the close encounter, five operational spacecraft will be present near Mars. Characterizing the coma is crucial for assessing the risk posed to these satellites by meteoroid impacts. We present an analytic model of cometary comae that describes the spatial and size distributions of cometary dust and meteoroids. This model correctly reproduces, to within an order of magnitude, the number of impacts recorded by Giotto near 1P/Halley [1] and by Stardust near comet 81P/Wild 2 [2]. Applied to Siding Spring, our model predicts a total particle fluence near Mars of 0.02 particles per square meter. In order to determine the degree to which Siding Spring's coma deviates from a sphere, we perform numerical simulations which take into account both gravitational effects and radiative forces. We take the entire dust component of the coma and tail continuum into account by simulating the ejection and evolution of dust particles from comet Siding Spring. The total number of particles simulated is essentially a free parameter and does not provide a check on the total fluence. Instead, these simulations illustrate the degree to which the coma of Siding Spring deviates from the perfect sphere described by our analytic model (see Figure). We conclude that our analytic model sacrifices less than an order of magnitude in accuracy by neglecting particle dynamics and radiation pressure and is thus adequate for order-of-magnitude fluence estimates. Comet properties may change unpredictably and therefore an analytic coma model that enables quick recalculation of the meteoroid fluence is highly desirable. NASA's Meteoroid Environment Office is monitoring comet Siding Spring and taking measurements of cometary brightness and dust production. We will discuss our coma model and nominal fluence taking the latest observations into account.

Reduced Activity and Large Particles from the Disintegrating Planet Candidate KIC 12557548b

NASA Astrophysics Data System (ADS)

Schlawin, E.; Herter, T.; Zhao, M.; Teske, J. K.; Chen, H.

2016-08-01

The intriguing exoplanet candidate KIC 12557548b is believed to have a comet-like tail of dusty debris trailing a small rocky planet. The tail of debris scatters up to 1.3% of the stellar light in the Kepler observatory’s bandpass (0.42-0.9 μm). Observing the tail’s transit depth at multiple wavelengths can reveal the composition and particle size of the debris, constraining the makeup and lifetime of the sub-Mercury planet. Early dust particle size predictions from the scattering of the comet-like tail pointed toward a dust size of ˜0.1 μm for silicate compositions. These small particles would produce a much deeper optical transit depth than near-infrared transit depth. We measure a transmission spectrum for KIC 12557548b using the SpeX spectrograph (covering 0.8-2.4 μm) simultaneously with the MORIS imager taking r‧ (0.63 μm) photometry on the Infrared Telescope Facility for eight nights and one night in H band (1.63 μm) using the Wide-field IR Camera at the Palomar 200 inch telescope. The infrared spectra are plagued by systematic errors, but we argue that sufficient precision is obtained when using differential spectroscopic calibration when combining multiple nights. The average differential transmission spectrum is flat, supporting findings that KIC 12557548b’s debris is likely composed of larger particles ≳0.5 μm for pyroxene and olivine and ≳0.2 μm for iron and corundum. The r‧ photometric transit depths are all below the average Kepler value, suggesting that the observations occurred during a weak period or that the mechanisms producing optical broadband transit depths are suppressed.

Theory of long-range diffusion of proteins on a spherical biological membrane: application to protein cluster formation and actin-comet tail growth.

PubMed

Amatore, Christian; Oleinick, Alexander I; Klymenko, Oleksiy V; Svir, Irina

2009-07-13

Breaking of symmetry is often required in biology in order to produce a specific function. In this work we address the problem of protein diffusion over a spherical vesicle surface towards one pole of the vesicle in order to produce ultimately an active protein cluster performing a specific biological function. Such a process is, for example, prerequisite for the assembling of proteins which then cooperatively catalyze the polymerization of actin monomers to sustain the growth of actin tails as occurs in natural vesicles such as those contained in Xenopus eggs. By this process such vesicles may propel themselves within the cell by the principle of action-reaction. In this work the physicochemical treatment of diffusion of large biomolecules within a cellular membrane is extended to encompass the case when proteins may be transiently poised by corral-like structures partitioning the membrane as has been recently documented in the literature. In such case the exchange of proteins between adjacent corrals occurs by energy-gated transitions instead of classical Brownian motion, yet the present analysis shows that long-range movements of the biomolecules may still be described by a classical diffusion law though the diffusion coefficient has then a different physical meaning. Such a model explains why otherwise classical diffusion of proteins may give rise to too small diffusion coefficients compared to predictions based on the protein dimension. This model is implemented to examine the rate of proteins clustering at one pole of a spherical vesicle and its outcome is discussed in relevance to the mechanism of actin comet tails growth.

Arecibo Observatory support of the US international cometary Explorer mission encounter at comet Giacobini-Zinner

NASA Technical Reports Server (NTRS)

Gordon, D. D.; Ward, M. T.

1986-01-01

The Arecibo Observatory in Puerto Rico participated in the support of the U.S. International Cometary Explorer (ICE) mission when the ICE spacecraft passed through the tail of comet Giacobini-Zinner on September 11, 1985. The Arecibo Observatory is a research facility of the National Astronomy and Ionosphere Center (NAIC) operated by Cornell University under contract to the National Science Foundation (NSF). Coverage of the encounter involved the use of the observatory's 305-m (1000-ft) radio reflector antenna and RF and data system equipment fabricated or modified specifically for support of the ICE mission. The successful implementation, testing, and operation of this temporary receive, record, and data relay capability resulted from a cooperative effort by personnel at the Arecibo Observatory, the Goddard Space Flight Center, and the Jet Propulsion Laboratory.

ICE navigation support

NASA Astrophysics Data System (ADS)

Efron, L.; Muellerschoen, R. J.; Premkumar, R. I.

1986-08-01

The International Cometary Explorer (ICE) encounter with Comet Giacobini-Zinner took place 7 years after the spacecraft's original launch on 12 August 1978 as the International Sun Earth Explorer 3 (ISEE-3), part of a three-spacecraft project to study the interaction between the solar wind and the Earth's magnetosphere. Transfer to an interplanetary trajectory was performed via a 119-km-altitute, gravity-assist, lunar swingby on December 1983. Navigation support during interplanetary cruise and comet encounter was provided by orbit determination utilizing radio metric data from the DSN 64-meter antennas in Goldstone, California and Madrid, Spain. Orbit solutions yielding predictions of 50-km geocentric delivery accuracy in the target aim plane were achieved during interplanetary cruise and at comet encounter using 6-to-12-week data arcs between periodic attitude-change maneuvers. One-sigma two-way range and range rate residuals were consistently 40 meters and 0.2 mm/s or better, respectively. Non-gravitational forces affected the comet's motion during late August and early September 1985 and caused a 2300-km shift in the orbit of the comet relative to the spacecraft. This necessitated a final ICE orbit trim maneuver 3 days prior to encounter. Near-real-time assessment of two-way 2-GHz (S-band) Doppler pseudo-residuals during the June and July 1985 trajectory change maneuvers aided in calibration of the spacecraft's thrusters in preparation for this final critical maneuver. Post-flight analysis indicates tail centerline passage was achieved within 10 seconds of the predicted time and geocentric position uncertainty at encounter was less than 40 km.

Infrared observations of an outburst of small dust grains from the nucleus of Comet P/Halley 1986 III at perihelion

NASA Technical Reports Server (NTRS)

Gehrz, R. D.; Johnson, C. H.; Magnuson, S. D.; Ney, E. P.; Hayward, T. L.

1995-01-01

A close examination of the 0.7- to 23-micron infrared data base acquired by Gehrz and Ney (1992), suggests that the nucleus of Comet P/Halley 1986 III emitted a burst of small dust grains during a 3-day period commencing within hours of perihelion passage on 1986 February 9.46 UT. The outburst was characterized by significant increases in the coma's grain color temperature T(sub obs), temperature excess (superheat: S = T(sub obs)/T(sub BB)), infrared luminosity, albedo, and 10-micron silicate emission feature strength. These changes are all consistent with the sudden ejection from the nucleus of a cloud of grains with radii of approximately 0.5 micron. This outburst may have produced the dust that was responsible for some of the tail streamers photographed on 1986 February 22 UT. The peak of the dust outburst occurred about 3 days before a pronounced increase in the water production rate measured by the Pioneer Venus Orbiter Ultraviolet Spectrometer. We suggest that jets that release large quantities of small particles may be largely responsible for some of the variable infrared behavior that has been reported for P/Halley and other comets during the past two decades. Such jets may also account for some of the differences IR Type I and IR Type II comets.

Neurotoxicity of low bisphenol A (BPA) exposure for young male mice: Implications for children exposed to environmental levels of BPA.

PubMed

Zhou, Yuanxiu; Wang, Zhouyu; Xia, Minghan; Zhuang, Siyi; Gong, Xiaobing; Pan, Jianwen; Li, Chuhua; Fan, Ruifang; Pang, Qihua; Lu, Shaoyou

2017-10-01

To investigate the neuron toxicities of low-dose exposure to bisphenol A (BPA) in children, mice were used as an animal model. We examined brain cell damage and the effects of learning and memory ability after BPA exposure in male mice (4 weeks of age) that were divided into four groups and chronically received different BPA treatments for 8 weeks. The comet assay and hippocampal neuron counting were used to detect the brain cell damage. The Y-maze test was applied to test alterations in learning and memory ability. Long term potentiation induction by BPA exposure was performed to study the potential mechanism of performance. The percentages of tail DNA, tail length and tail moment in brain cells increased with increasing BPA exposure concentrations. Significant differences in DNA damage were observed among the groups, including between the low-dose and control groups. In the Y-maze test, the other three groups qualified for the learned standard one day earlier than the high-exposed group. Furthermore, the ratio of qualified mice in the high-exposed group was always the lowest among the groups, indicating that high BPA treatment significantly altered the spatial memory performance of mice. Different BPA treatments exerted different effects on the neuron numbers of different regions in the hippocampus. In the CA1 region, the high-exposed group had a significant decrease in neuron numbers. A non-monotonic relationship was observed between the exposure concentrations and neuron quantity in the CA3 region. The hippocampal slices in the control and medium-exposed groups generated long-term potentiation after induction by theta burst stimulation, but the low-exposed group did not. A significant difference was observed between the control and low-exposed groups. In conclusion, chronic exposure to a low level of BPA had adverse effects on brain cells and altered the learning and memory ability of adolescent mice. Copyright © 2017 Elsevier Ltd. All rights reserved.

Selected biomarkers as predictive tools in testing efficacy of melatonin and coenzyme Q on propionic acid - induced neurotoxicity in rodent model of autism.

PubMed

Al-Ghamdi, Mashael; Al-Ayadhi, Laila; El-Ansary, Afaf

2014-02-25

Exposures to environmental toxins are now thought to contribute to the development of autism spectrum disorder. Propionic acid (PA) found as a metabolic product of gut bacteria has been reported to mimic/mediate the neurotoxic effects of autism. Results from animal studies may guide investigations on human populations toward identifying environmental contaminants that produce or drugs that protect from neurotoxicity. Forty-eight young male Western Albino rats were used in the present study. They were grouped into six equal groups 8 rats each. The first group received a neurotoxic dose of buffered PA (250 mg/Kg body weight/day for 3 consecutive days). The second group received only phosphate buffered saline (control group). The third and fourth groups were intoxicated with PA as described above followed by treatment with either coenzyme Q (4.5 mg/kg body weight) or melatonin (10 mg/kg body weight) for one week (therapeutically treated groups). The fifth and sixth groups were administered both compounds for one week prior to PA (protected groups). Heat shock protein70 (Hsp70), Gamma amino-butyric acid (GABA), serotonin, dopamine, oxytocin and interferon γ-inducible protein 16 together with Comet DNA assay were measured in brain tissues of the six studied groups. The obtained data showed that PA caused multiple signs of brain toxicity revealed in depletion of GABA, serotonin, and dopamine, are which important neurotransmitters that reflect brain function, interferon γ-inducible protein 16 and oxytocin. A high significant increase in tail length, tail DNA% damage and tail moment was reported indicating the genotoxic effect of PA. Administration of melatonin or coenzyme Q showed both protective and therapeutic effects on PA-treated rats demonstrated in a remarkable amelioration of most of the measured parameters. In conclusion, melatonin and coenzyme Q have potential protective and restorative effects against PA-induced brain injury, confirmed by improvement in biochemical markers and DNA double strand breaks.

Selected biomarkers as predictive tools in testing efficacy of melatonin and coenzyme Q on propionic acid - induced neurotoxicity in rodent model of autism

PubMed Central

2014-01-01

Background Exposures to environmental toxins are now thought to contribute to the development of autism spectrum disorder. Propionic acid (PA) found as a metabolic product of gut bacteria has been reported to mimic/mediate the neurotoxic effects of autism. Results from animal studies may guide investigations on human populations toward identifying environmental contaminants that produce or drugs that protect from neurotoxicity. Forty-eight young male Western Albino rats were used in the present study. They were grouped into six equal groups 8 rats each. The first group received a neurotoxic dose of buffered PA (250 mg/Kg body weight/day for 3 consecutive days). The second group received only phosphate buffered saline (control group). The third and fourth groups were intoxicated with PA as described above followed by treatment with either coenzyme Q (4.5 mg/kg body weight) or melatonin (10 mg/kg body weight) for one week (therapeutically treated groups). The fifth and sixth groups were administered both compounds for one week prior to PA (protected groups). Heat shock protein70 (Hsp70), Gamma amino-butyric acid (GABA), serotonin, dopamine, oxytocin and interferon γ-inducible protein 16 together with Comet DNA assay were measured in brain tissues of the six studied groups. Results The obtained data showed that PA caused multiple signs of brain toxicity revealed in depletion of GABA, serotonin, and dopamine, are which important neurotransmitters that reflect brain function, interferon γ-inducible protein 16 and oxytocin. A high significant increase in tail length, tail DNA% damage and tail moment was reported indicating the genotoxic effect of PA. Administration of melatonin or coenzyme Q showed both protective and therapeutic effects on PA–treated rats demonstrated in a remarkable amelioration of most of the measured parameters. Conclusion In conclusion, melatonin and coenzyme Q have potential protective and restorative effects against PA-induced brain injury, confirmed by improvement in biochemical markers and DNA double strand breaks. PMID:24568717

Evaluation of Genotoxic and Cytotoxic Effects in Human Peripheral Blood Lymphocytes Exposed In Vitro to Neonicotinoid Insecticides News

PubMed Central

Calderón-Segura, María Elena; Gómez-Arroyo, Sandra; Villalobos-Pietrini, Rafael; Martínez-Valenzuela, Carmen; Carbajal-López, Yolanda; Calderón-Ezquerro, María del Carmen; Cortés-Eslava, Josefina; García-Martínez, Rocío; Flores-Ramírez, Diana; Rodríguez-Romero, María Isabel; Méndez-Pérez, Patricia; Bañuelos-Ruíz, Enrique

2012-01-01

Calypso (thiacloprid), Poncho (clothianidin), Gaucho (imidacloprid), and Jade (imidacloprid) are commercial neonicotinoid insecticides, a new class of agrochemicals in México. However, genotoxic and cytotoxic studies have not been performed. In the present study, human peripheral blood lymphocytes (PBL) were exposed in vitro to different concentrations of the four insecticides. The genotoxic and cytotoxic effects were evaluated using the alkaline comet and trypan blue dye exclusion assays. DNA damage was evaluated using two genotoxicity parameters: tail length and comet frequency. Exposure to 9.5 × 10−6 to 5.7 × 10−5 M Jade; 2.8 × 10−4 to 1.7 × 10−3 M Gaucho; 0.6 × 10−1 to 1.4 × 10−1 M Calypso; 1.2 × 10−1 to 9.5 × 10−1 M Poncho for 2 h induced a significant increase DNA damage with a concentration-dependent relationship. Jade was the most genotoxic of the four insecticides studied. Cytotoxicity was observed in cells exposed to 18 × 10−3 M Jade, 2.0 × 10−3 M Gaucho, 2.0 × 10−1 M Calypso, 1.07 M Poncho, and cell death occurred at 30 × 10−3 M Jade, 3.3 × 10−3 M Gaucho, 2.8 × 10−1 M Calypso, and 1.42 M Poncho. This study provides the first report of genotoxic and cytotoxic effects in PBL following in vitro exposure to commercial neonicotinoid insecticides. PMID:22545045

Semen molecular and cellular features: these parameters can reliably predict subsequent ART outcome in a goat model

PubMed Central

Berlinguer, Fiammetta; Madeddu, Manuela; Pasciu, Valeria; Succu, Sara; Spezzigu, Antonio; Satta, Valentina; Mereu, Paolo; Leoni, Giovanni G; Naitana, Salvatore

2009-01-01

Currently, the assessment of sperm function in a raw or processed semen sample is not able to reliably predict sperm ability to withstand freezing and thawing procedures and in vivo fertility and/or assisted reproductive biotechnologies (ART) outcome. The aim of the present study was to investigate which parameters among a battery of analyses could predict subsequent spermatozoa in vitro fertilization ability and hence blastocyst output in a goat model. Ejaculates were obtained by artificial vagina from 3 adult goats (Capra hircus) aged 2 years (A, B and C). In order to assess the predictive value of viability, computer assisted sperm analyzer (CASA) motility parameters and ATP intracellular concentration before and after thawing and of DNA integrity after thawing on subsequent embryo output after an in vitro fertility test, a logistic regression analysis was used. Individual differences in semen parameters were evident for semen viability after thawing and DNA integrity. Results of IVF test showed that spermatozoa collected from A and B lead to higher cleavage rates (0 < 0.01) and blastocysts output (p < 0.05) compared with C. Logistic regression analysis model explained a deviance of 72% (p < 0.0001), directly related with the mean percentage of rapid spermatozoa in fresh semen (p < 0.01), semen viability after thawing (p < 0.01), and with two of the three comet parameters considered, i.e tail DNA percentage and comet length (p < 0.0001). DNA integrity alone had a high predictive value on IVF outcome with frozen/thawed semen (deviance explained: 57%). The model proposed here represents one of the many possible ways to explain differences found in embryo output following IVF with different semen donors and may represent a useful tool to select the most suitable donors for semen cryopreservation. PMID:19900288

Assessing the genotoxic potential of chlorothalonil drift from potato fields in Prince Edward Island, Canada.

PubMed

Garron, Christine; Knopper, Loren D; Ernst, William R; Mineau, Pierre

2012-02-01

Chlorothalonil, a broad-spectrum nonsystemic foliar fungicide, is one of the most extensively used pesticide active ingredients on Prince Edward Island, Canada, for blight control on potatoes. In ambient air-sampling programs conducted in 1998 and 1999 and from 2002 to 2004, chlorothalonil was measured in 97% of air samples collected. It is known to produce severe eye and skin irritation, is cytogenic and is considered a possible human carcinogen by the United States Environmental Protection Agency and the International Agency for Research on Cancer. Inhalation studies that quantify chlorothalonil subchronic effects (e.g., genotoxicity) are lacking. The purpose of this study was to assess the possible genotoxic potential of chlorothalonil under field conditions by using the alkaline comet assay to assess DNA damage in CD-1 mice. Mice were selected as a surrogate species for wild small mammals (e.g., meadow voles, deer mice) known to inhabit areas adjacent to potato fields. Mice were placed at three locations downwind of a chlorothalonil application (0, 30, and 100 m) and at one up-wind control location at least 30 m from the field. Downwind mice were exposed to drift throughout the spray period (approximately 30 min) and for an additional hour after spraying. Air samples were collected during the spray trials (before, during, and after spraying) using high-volume polyurethane foam and PM(2.5) air samplers. Pesticide deposits were measured using 20 × 25 cm glass-fibre filters. After exposure, blood was collected from each mouse, and DNA strand breaks in white blood cells measured using comet assay. Results suggest that metrics of DNA damage [tail length (TL), percent DNA in tail] were not significantly related to total air chlorothalonil concentration from the three spray trials (r (2) = 0.000, P = 0.907 for TL; r (2) = 0.001, P = 0.874 for percent DNA). In addition, no significant difference in DNA damage was observed between exposed (at 0 m) and control animals (P = 0.357 for TL; P = 0.958 for percent DNA). Based on these results it can be concluded that wild small mammals living beside fields sprayed with chlorothalonil are at no greater risk of exposure-related DNA damage than conspecifics from unexposed areas.

VizieR Online Data Catalog: WINERED CN-red band emission in comet C/2013 R1 (Shinnaka+, 2017)

NASA Astrophysics Data System (ADS)

Shinnaka, Y.; Kawakita, H.; Kondo, S.; Ikeda, Y.; Kobayashi, N.; Hamano, S.; Sameshima, H.; Fukue, K.; Matsunaga, N.; Yasui, C.; Izumi, N.; Mizumoto, M.; Otsubo, S.; Takenaka, K.; Watase, A.; Kawanishi, T.; Nakanishi, K.; Nakaoka, T.

2018-05-01

High-resolution spectroscopic observations of comet C/2013 R1 (Lovejoy; hereafter, comet Lovejoy) in the near-infrared wavelength region were performed using the WINERED spectrograph (Ikeda et al. 2016SPIE.9908E..5ZI) mounted on the Nasmyth focus of the 1.3 m Araki telescope (F/10) at Koyama Astronomical Observatory, Japan (Yoshikawa et al. 2012SPIE.8444E..6GY). We used a slit of length 47" and width 1.5". This slit width corresponds to a spectral resolving power of R=28000 (two pixels). The observations of comet Lovejoy were performed on 2013 November 30, from 19:08 UT to 21:04 UT; the total integration time was 6000 s on source. The heliocentric and geocentric distances were 0.91 au and 0.49 au, respectively, and the relative velocities of the comet to the Sun and observer were -14.5 km/s and 25.8 km/s, respectively, at the observations. We put the comet at the center of the slit during the exposures. Other calibration data (darks, flats, and comparison-lamp frames) were also acquired. (1 data file).

Mid-infrared spectra of comet nuclei

NASA Astrophysics Data System (ADS)

Kelley, Michael S. P.; Woodward, Charles E.; Gehrz, Robert D.; Reach, William T.; Harker, David E.

2017-03-01

Comet nuclei and D-type asteroids have several similarities at optical and near-IR wavelengths, including near-featureless red reflectance spectra, and low albedos. Mineral identifications based on these characteristics are fraught with degeneracies, although some general trends can be identified. In contrast, spectral emissivity features in the mid-infrared provide important compositional information that might not otherwise be achievable. Jovian Trojan D-type asteroids have emissivity features strikingly similar to comet comae, suggesting that they have the same compositions and that the surfaces of the Trojans are highly porous. However, a direct comparison between a comet and asteroid surface has not been possible due to the paucity of spectra of comet nuclei at mid-infrared wavelengths. We present 5-35 μm thermal emission spectra of comets 10P/Tempel 2, and 49P/Arend-Rigaux observed with the Infrared Spectrograph on the Spitzer Space Telescope. Our analysis reveals no evidence for a coma or tail at the time of observation, suggesting the spectra are dominated by the comet nucleus. We fit each spectrum with the near-Earth asteroid thermal model (NEATM) and find sizes in agreement with previous values. However, the NEATM beaming parameters of the nuclei, 0.74-0.83, are systematically lower than the Jupiter-family comet population mean of 1.03 ± 0.11, derived from 16- and 22-μm photometry. We suggest this may be either an artifact of the spectral reduction, or the consequence of an emissivity low near 16 μm. When the spectra are normalized by the NEATM model, a weak 10-μm silicate plateau is evident, with a shape similar to those seen in mid-infrared spectra of D-type asteroids. A silicate plateau is also evident in previously published Spitzer spectra of the nucleus of comet 9P/Tempel 1. We compare, in detail, these comet nucleus emission features to those seen in spectra of the Jovian Trojan D-types (624) Hektor, (911) Agamemnon, and (1172) Aneas, as well as those seen in the spectra of seven comet comae. The comet comae present silicate features with two distinct shapes, either trapezoidal, or more rounded, the latter apparently due to enhanced emission near 8 to 8.5 μm. The surfaces of Tempel 2, Arend-Rigaux, and Hektor best agree with the comae that present trapezoidal features, furthering the hypothesis that the surfaces of these targets must have high porosities in order to exhibit a spectrum similar to a comet coma. An emissivity minimum at 15 μm, present in the spectra of Tempel 2, Arend-Rigaux, Hektor, and Agamemnon, is also described, the origin of which remains unidentified. The compositional similarity between D-type asteroids and comets is discussed, and our data supports the hypothesis that they have similar origins in the early Solar System.

To catch a comet: Technical overview of CAN DO G-324

NASA Technical Reports Server (NTRS)

Obrien, T. J. (Editor)

1986-01-01

The primary objective of the C. E. Williams Middle School Get Away Special CAN DO is the photographing of Comet Halley. The project will involve middle school students, grades 6 through 8, in the study and interpretation of astronomical photographs and techniques. G-324 is contained in a 5 cubic foot GAS Canister with an opening door and pyrex window for photography. It will be pressurized with one atmosphere of dry nitrogen. Three 35mm still cameras with 250 exposure film backs and different focal length lenses will be fired by a combination of automatic timer and an active comet detector. A lightweight 35mm movie camera will shoot single exposures at about 1/2 minute intervals to give an overlapping skymap of the mission. The fifth camera is a solid state television camera specially constructed for detection of the comet by microprocessor.

HT-COMET: a novel automated approach for high throughput assessment of human sperm chromatin quality.

PubMed

Albert, Océane; Reintsch, Wolfgang E; Chan, Peter; Robaire, Bernard

2016-05-01

Can we make the comet assay (single-cell gel electrophoresis) for human sperm a more accurate and informative high throughput assay? We developed a standardized automated high throughput comet (HT-COMET) assay for human sperm that improves its accuracy and efficiency, and could be of prognostic value to patients in the fertility clinic. The comet assay involves the collection of data on sperm DNA damage at the level of the single cell, allowing the use of samples from severe oligozoospermic patients. However, this makes comet scoring a low throughput procedure that renders large cohort analyses tedious. Furthermore, the comet assay comes with an inherent vulnerability to variability. Our objective is to develop an automated high throughput comet assay for human sperm that will increase both its accuracy and efficiency. The study comprised two distinct components: a HT-COMET technical optimization section based on control versus DNAse treatment analyses ( ITALIC! n = 3-5), and a cross-sectional study on 123 men presenting to a reproductive center with sperm concentrations categorized as severe oligozoospermia, oligozoospermia or normozoospermia. Sperm chromatin quality was measured using the comet assay: on classic 2-well slides for software comparison; on 96-well slides for HT-COMET optimization; after exposure to various concentrations of a damage-inducing agent, DNAse, using HT-COMET; on 123 subjects with different sperm concentrations using HT-COMET. Data from the 123 subjects were correlated to classic semen quality parameters and plotted as single-cell data in individual DNA damage profiles. We have developed a standard automated HT-COMET procedure for human sperm. It includes automated scoring of comets by a fully integrated high content screening setup that compares well with the most commonly used semi-manual analysis software. Using this method, a cross-sectional study on 123 men showed no significant correlation between sperm concentration and sperm DNA damage, confirming the existence of hidden chromatin damage in men with apparently normal semen characteristics, and a significant correlation between percentage DNA in the tail and percentage of progressively motile spermatozoa. Finally, the use of DNA damage profiles helped to distinguish subjects between and within sperm concentration categories, and allowed a determination of the proportion of highly damaged cells. The main limitations of the HT-COMET are the high, yet indispensable, investment in an automated liquid handling system and heating block to ensure accuracy, and the availability of an automated plate reading microscope and analysis software. This standardized HT-COMET assay offers many advantages, including higher accuracy and evenness due to automation of sensitive steps, a 14.4-fold increase in sample analysis capacity, and an imaging and scoring time of 1 min/well. Overall, HT-COMET offers a decrease in total experimental time of more than 90%. Hence, this assay constitutes a more efficient option to assess sperm chromatin quality, paves the way to using this assay to screen large cohorts, and holds prognostic value for infertile patients. Funded by the CIHR Institute of Human Development, Child and Youth Health (IHDCYH; RHF 100625). O.A. is a fellow supported by the Fonds de la Recherche du Québec - Santé (FRQS) and the CIHR Training Program in Reproduction, Early Development, and the Impact on Health (REDIH). B.R. is a James McGill Professor. The authors declare no conflicts of interest. © The Author 2016. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Rosetta - a comet ride to solve planetary mysteries

NASA Astrophysics Data System (ADS)

2003-01-01

Comets are very interesting objects for scientists, since their composition reflects how the Solar System was when it was very young and still 'unfinished', more than 4600 million years ago. Comets have not changed much since then. By orbiting Comet Wirtanen and landing on it, Rosetta will collect essential information to understand the origin and evolution of our Solar System. It will also help discover whether comets contributed to the beginnings of life on Earth. In fact comets are carriers of complex organic molecules, that - delivered to Earth through impacts - perhaps played a role in the origin of living forms. Furthermore, “volatile” light elements carried by comets may have also played an important role in forming the Earth’s oceans and atmopshere. “Rosetta is one of the most challenging missions ever undertaken so far”, says Prof. David Southwood, ESA Director of Science, “No one before attempted a similar mission, unique for its scientific implications as well as for its complex and spectacular interplanetary space manoeuvres”. Before reaching its target in 2011, Rosetta will circle the Sun almost four times on wide loops in the inner Solar System. During its long trek, the spacecraft will have to endure some extreme thermal conditions. Once it is close to Comet Wirtanen, scientists will take it through a delicate braking manoeuvre; then the spacecraft will closely orbit the comet, and gently drop a lander on it. It will be like landing on a small, fast-moving cosmic bullet that still has - at present - an almost unknown 'geography'. An amazing 8-year interplanetary trek Rosetta is a 3-tonne box-type spacecraft about 3 metres high, with two 14-metre long solar panels. It consists of an orbiter and a lander. The lander is approximately 1 metre across and 80 centimetres high. It will be attached to the side of the Rosetta orbiter during the journey to Comet Wirtanen. Rosetta carries 21 experiments in total, 10 of them on the lander. They will be kept in hibernation during most of its 8-year trek towards Wirtanen. What makes Rosetta's cruise so long? To reach Comet Wirtanen, the spacecraft needs to go out in deep space as far from the Sun as Jupiter is. No launcher could possibly get Rosetta there directly. ESA's spacecraft will gather speed from gravitational ‘kicks’ provided by three planetary fly-bys: one of Mars in 2005 and two of Earth in 2005 and 2007. During the trip, Rosetta will also visit two asteroids, Otawara (in 2006) and Siwa (in 2008). During these encounters, scientists will switch on Rosetta's instruments for calibration and scientific studies. Long trips in deep space include many hazards, such as extreme changes in temperature. Rosetta will leave the benign environment of near-Earth space to the dark, frigid regions beyond the asteroid belt. To manage these thermal loads, experts have done very tough pre-launch tests to study Rosetta's endurance. For example, they have heated its external surfaces to more than 150°C, then quickly cooled it to -180°C in the next test. The spacecraft will be fully reactivated prior to the comet rendezvous manoeuvre in 2011. Then, Rosetta will orbit the comet - an object only 1.2 km wide - while it cruises through the inner Solar System at 135 000 kilometres per hour. At that time of the rendezvous - around 675 million km from the Sun - Wirtanen will hardly show any surface activity. It means that the carachteristic coma (the comet’s ‘atmosphere’) and the tail will not be formed yet, because of the large distance from the Sun. The comet's tail is in fact made of dust grains and frozen gases from the comet's surface that vapourise because of the Sun's heat. During 6-month, Rosetta will extensively map the comet surface, prior to selecting a landing site. In July 2012, the lander will self-eject from the spacecraft from a height of just one kilometre. Touchdown will take place at walking speed - less than 1 metre per second. Immediately after touchdown, the lander will fire a harpoon into the ground to avoid bouncing off the surface back into space, since the extremely weak comet’s gravity alone would not hold onto the lander. Operations and scientific observations on the comet surface will last 65 hours as a minimum, but may continue for many months. During and after the lander operations, Rosetta will continue orbiting and studying the comet: Rosetta will be the first spacecraft to witness at close quarters the changes taking place in a comet when the comet approaches the Sun and grows its coma and tail. The trip will end in July 2013, after 10.5 years of adventure, when the comet is closest to the Sun. Studying a comet on the spot Rosetta's goal is to examine the comet in great detail. The instruments on Rosetta orbiter include several cameras, spectrometers, and experiments that work at different wavelengths --infrared, ultraviolet, microwave, radio and a number of sensors. They will provide, among other things, very high-resolution images and information about the shape, density, temperature, and chemical composition of the comet. Rosetta’s instruments will analyse the gases and dust grains in the so-called “coma” that forms when the comet becomes active, as well as the interaction with the solar wind. The 10 instruments on board the lander will do an on-the-spot analysis of the composition and structure of the comet’s surface and subsurface material. A drilling system will take samples down to 30 centimetres below the surface and will feed these to the ‘composition analysers’. Other instruments will measure properties such as near-surface strength, density, texture, porosity, ice phases, and thermal properties. Microscopic studies of individual grains will tell us about the texture. In addition, instruments on the lander will study how the comet changes during the day-night cycle, and while it approaches the Sun. Ground operations Data from the lander are relayed to the orbiter, which stores them for downlink to Earth at the next ground station contact. ESA has installed a new deep-space antenna at New Norcia, near Perth in Western Australia, as the main communications link between the spacecraft and the ESOC Mission Control in Darmstadt, Germany. This 35-metre diameter parabolic antenna allows the radio signal to reach distances of more than 1 million kilometres from Earth. The radio signals, travelling at the speed of light, will take up to 50 minutes to cover the distance between the spacecraft and Earth. Rosetta's Science Operations Centre, which is responsible for collecting and distributing the scientific data, will share a location at ESOC and ESTEC in Noordwijk, The Netherlands. The Lander Control Centre is located in DLR in Cologne, Germany, and the Lander Science Centre in CNES in Toulouse, France. Building Rosetta Rosetta was selected as a mission in 1993. The spacecraft has been built by Astrium Germany as prime contractor. Major subcontractors are Astrium UK (spacecraft platform), Astrium France (spacecraft avionics), and Alenia Spazio (assembly, integration, and verification). Rosetta’s industrial team involves more than 50 contractors from 14 European countries, Canada and the United States. Scientific consortia from institutes across Europe and the United States have provided the instruments on the orbiter. A European consortium under the leadership of the German Aerospace Research Institute (DLR) has provided the lander. Rosetta has cost ESA Euro 701 million at 2000 economic conditions. This amount includes the launch and the entire period of development and mission operations from 1996 to 2013. The lander and the experiments, the so-called 'payload', are not included since they are funded by the member states through the scientific institutes. Note to editors Europe is certainly a pioneer in comet exploration. In 1986, ESA’s spacecraft Giotto performed the closest comet fly-by ever achieved by any spacecraft (at a distance of 600 kilometres of Halley). It sent back wonderful pictures and data that showed that comets contain complex organic molecules. These kinds of compounds are rich in carbon, hydrogen, oxygen, and nitrogen. Intriguingly, these are the elements which make up nucleic acids and amino acids, which are essential ingredients for life as we know it. Giotto continued its successful journey and flew by Comet Grigg-Skjellerup in 1992 within about 200 km distance. Now scientists will be eagerly waiting to be able to answer some of the new intriguing questions that arose from analysing the exciting results from Giotto. Other past missions that have flown by a comet were: NASA’s ICE mission in 1985, the two Russian VEGA spacecraft and the two Japanese spacecraft Suisei and Sakigake that were part of the armada that visited comet Halley in 1986; NASA’s Deep Space 1 flew-by comet Borelly in 2001 and NASA’s Stardust will fly-by comet Wild 2 in early 2004 and will return samples of the comet’s coma in 2006. Unfortunately NASA’s Contour launched in Summer 2002 failed when it was inserted onto its interplanetary trajectory. In 2004 we will see the launch of Deep Impact, a spacecraft that will shoot a massive block of copper into a comet nucleus.

Colloidal and antibacterial properties of novel triple-headed, double-tailed amphiphiles: exploring structure-activity relationships and synergistic mixtures.

PubMed

Marafino, John N; Gallagher, Tara M; Barragan, Jhosdyn; Volkers, Brandi L; LaDow, Jade E; Bonifer, Kyle; Fitzgerald, Gabriel; Floyd, Jason L; McKenna, Kristin; Minahan, Nicholas T; Walsh, Brenna; Seifert, Kyle; Caran, Kevin L

2015-07-01

Two novel series of tris-cationic, tripled-headed, double-tailed amphiphiles were synthesized and the effects of tail length and head group composition on the critical aggregation concentration (CAC), thermodynamic parameters, and minimum inhibitory concentration (MIC) against six bacterial strains were investigated. Synergistic antibacterial combinations of these amphiphiles were also identified. Amphiphiles in this study are composed of a benzene core with three benzylic ammonium bromide groups, two of which have alkyl chains, each 8-16 carbons in length. The third head group is a trimethylammonium or pyridinium. Log of critical aggregation concentration (log[CAC]) and heat of aggregation (ΔHagg) were both inversely proportional to the length of the linear hydrocarbon chains. Antibacterial activity increases with tail length until an optimal tail length of 12 carbons per chain, above which, activity decreased. The derivatives with two 12 carbon chains had the best antibacterial activity, killing all tested strains at concentrations of 1-2μM for Gram-positive and 4-16μM for Gram-negative bacteria. The identity of the third head group (trimethylammonium or pyridinium) had minimal effect on colloidal and antibacterial activity. The antibacterial activity of several binary combinations of amphiphiles from this study was higher than activity of individual amphiphiles, indicating that these combinations are synergistic. These amphiphiles show promise as novel antibacterial agents that could be used in a variety of applications. Copyright © 2015 Elsevier Ltd. All rights reserved.

Trajectories for the Sakigake extended-mission phase

NASA Technical Reports Server (NTRS)

Farquhar, R.; Dunham, D.; Hsu, S.; Uesugi, K.; Kawaguchi, J.

1988-01-01

The trajectory profile that will be used by Japan's Sakigake spacecraft to accomplish its extended-mission objectives is described. Currently, Sakigake is following a heliocentric trajectory that will return to the earth's vicinity in January 1992. Four earth gravity-assist maneuvers are planned to redirect Sakigake to an encounter with Comet Honda-Mrkos-Pajdusakova (HMP) in February 1996. While carrying out the earth-swingby maneuvers, the spacecraft will make several passes through previously unexplored regions of the distant geomagnetic tail.

Plasma wave observations at comet giacobini-zinner.

PubMed

Scarf, F L; Coroniti, F V; Kennel, C F; Gurnett, D A; Ip, W H; Smith, E J

1986-04-18

The plasma wave instrument on the International Cometary Explorer (ICE) detected bursts of strong ion acoustic waves almost continuously when the spacecraft was within 2 million kilometers of the nucleus of comet Giacobini-Zinner. Electromagnetic whistlers and low-level electron plasma oscillations were also observed in this vast region that appears to be associated with heavy ion pickup. As ICE came closer to the anticipated location of the bow shock, the electromagnetic and electrostatic wave levels increased significantly, but even in the midst of this turbulence the wave instrument detected structures with familiar bow shock characteristics that were well correlated with observations of localized electron heating phenomena. Just beyond the visible coma, broadband waves with amplitudes as high as any ever detected by the ICE plasma wave instrument were recorded. These waves may account for the significant electron heating observed in this region by the ICE plasma probe, and these observations of strong wave-particle interactions may provide answers to longstanding questions concerning ionization processes in the vicinity of the coma. Near closest approach, the plasma wave instrument detected broadband electrostatic noise and a changing pattern of weak electron plasma oscillations that yielded a density profile for the outer layers of the cold plasma tail. Near the tail axis the plasma wave instrument also detected a nonuniform flux of dust impacts, and a preliminary profile of the Giacobini-Zinner dust distribution for micrometer-sized particles is presented.

Novel automatic detection of pleura and B-lines (comet-tail artifacts) on in vivo lung ultrasound scans

NASA Astrophysics Data System (ADS)

Moshavegh, Ramin; Hansen, Kristoffer Lindskov; Møller Sørensen, Hasse; Hemmsen, Martin Christian; Ewertsen, Caroline; Nielsen, Michael Bachmann; Jensen, Jørgen Arendt

2016-04-01

This paper presents a novel automatic method for detection of B-lines (comet-tail artifacts) in lung ultrasound scans. B-lines are the most commonly used artifacts for analyzing the pulmonary edema. They appear as laser-like vertical beams, which arise from the pleural line and spread down without fading to the edge of the screen. An increase in their number is associated with presence of edema. All the scans used in this study were acquired using a BK3000 ultrasound scanner (BK Ultrasound, Denmark) driving a 192-element 5:5 MHz wide linear transducer (10L2W, BK Ultrasound). The dynamic received focus technique was employed to generate the sequences. Six subjects, among those three patients after major surgery and three normal subjects, were scanned once and Six ultrasound sequences each containing 50 frames were acquired. The proposed algorithm was applied to all 300 in-vivo lung ultrasound images. The pleural line is first segmented on each image and then the B-line artifacts spreading down from the pleural line are detected and overlayed on the image. The resulting 300 images showed that the mean lateral distance between B-lines detected on images acquired from patients decreased by 20% in compare with that of normal subjects. Therefore, the method can be used as the basis of a method of automatically and qualitatively characterizing the distribution of B-lines.

Quercetin protects human peripheral blood mononuclear cells from OTA-induced oxidative stress, genotoxicity, and inflammation.

PubMed

Periasamy, Ramyaa; Kalal, Iravathy Goud; Krishnaswamy, Rajashree; Viswanadha, VijayaPadma

2016-07-01

Ochratoxin A (OTA) is one of the most abundant food-contaminating mycotoxins world wide, and is detrimental to human and animal health. This study evaluated the protective effect of quercetin against OTA-induced cytotoxicity, genotoxicity, and inflammatory response in lymphocytes. Cytotoxicity determined by MTT assay revealed IC20 value of OTA to be 20 µM, which was restored to near control values by pretreatment with quercetin. Oxidative stress parameters such as antioxidant enzymes, LPO and PCC levels indicated that quercetin exerted a protective effect on OTA-induced oxidative stress. Quercetin exerted an antigenotoxic effect on OTA-induced genotoxicity, by significantly reducing the number of structural aberrations in chromosomes and comet parameters like, % olive tail moment from 2.76 ± 0.02 to 0.56 ± 0.02 and % tail DNA from 56.23 ± 2.56 to 12.36 ± 0.56 as determined by comet assay. OTA-induced NO, TNF-α, IL-6, and IL-8 were significantly reduced in the quercetin pretreated samples indicating its anti-inflammatory role. Our results demonstrate for the first time that quercetin exerts a cytoprotective effect against OTA-induced oxidative stress, genotoxicity, and inflammation in lymphocytes. © 2014 Wiley Periodicals, Inc. Environ Toxicol 31: 855-865, 2016. © 2014 Wiley Periodicals, Inc.

A comparison between VEGA 1, 2 and Giotto flybys of comet 1P/Halley: implications for Rosetta

NASA Astrophysics Data System (ADS)

Volwerk, M.; Glassmeier, K.-H.; Delva, M.; Schmid, D.; Koenders, C.; Richter, I.; Szegö, K.

2014-11-01

Three flybys of comet 1P/Halley, by VEGA 1, 2 and Giotto, are investigated with respect to the occurrence of mirror mode waves in the cometosheath and field line draping in the magnetic pile-up region around the nucleus. The time interval covered by these flybys is approximately 8 days, which is also the approximate length of an orbit or flyby of Rosetta around comet 67P/Churyumov-Gerasimenko. Thus any significant changes observed around Halley are changes that might occur for Rosetta during one pass of 67P/CG. It is found that the occurrence of mirror mode waves in the cometosheath is strongly influenced by the dynamical pressure of the solar wind and the outgassing rate of the comet. Field line draping happens in the magnetic pile-up region. Changes in nested draping regions (i.e. regions with different Bx directions) can occur within a few days, possibly influenced by changes in the outgassing rate of the comet and thereby the conductivity of the cometary ionosphere.

A comparison between VEGA 1, 2 and Giotto flybys of comet 1P/Halley: Implications for Rosetta

NASA Astrophysics Data System (ADS)

Volwerk, Martin; Glassmeier, Karl-Heinz; Delva, Magda; Schmid, Daniel; Koenders, Christoph; Richter, Ingo; Szegö, Karoly

2015-04-01

Three flybys of comet 1P/Halley, by VEGA 1, 2 and Giotto, are investigated with respect to the occurrence of mirror mode waves in the cometosheath and field line draping in the magnetic pile-up region around the nucleus. The time interval covered by these flybys is approximately 8 days, which is also the approximate length of an orbit or flyby of Rosetta around comet 67P/Churyumov-Gerasimenko. Thus any significant changes observed around Halley are changes that might occur for Rosetta during one pass of 67P/CG. It is found that the occurrence of mirror mode waves in the cometosheath is strongly influenced by the dynamical pressure of the solar wind and the outgassing rate of the comet. Field line draping happens in the magnetic pile-up region. Changes in nested draping regions (i.e. regions with different Bx-directions) can occur within a few days, possibly in fluenced by changes in the outgassing rate of the comet and thereby the conductivity of the cometary ionosphere.

Comet 67P Through the Lens of Art

NASA Astrophysics Data System (ADS)

Smirnova, Ekaterina

2017-04-01

My proposal is to share my artistic exploration of a comet through the bodily senses, while finding inspiration in scientific data. I will present my artwork as a slideshow, showcasing: large scale paintings, ceramic sculptures, music and interactive augmented reality. The Rosetta mission of the European Space Agency (ESA) to comet 67P/ Churyumov-Gerasimenko is remarkable. The scientific investigation of the comet's composition, atmosphere, dust, vapor, surface and internal structure are crucial to help researchers understand the origin of the solar system and our own planet. Sight: Paintings Rosetta mission discovered that the water on the comet is different from the water on Earth; as measured with the ROSINA-DFMS instrument on Rosetta, water on 67P contains approximately 3 times more hydrogen­deuterium oxide - HDO, than found in Earth's oceans. In the art studio I re-create water that is close in composition to the water on the comet, by concentrating the level of HDO. With this water I paint large scale watermedia paintings, based on the photographs by Rosetta (OSIRIS, Nav. Cam.). Touch: Sculptures While exploring the comet's three-dimensional form, I focus more deeply on the composition of the comet. Stoneware clay and my choice of a glaze both include iron oxide, a common constituent of meteorites and comets. Hearing: Music An audio piece "A Singing Comet", by Manuel Senfft, based on the Rosetta Plasma Consortium data, inspired me to make a musical piece. In collaboration with clarinetist Lee Mottram (Wales) and composer Takuto Fukuda (Japan) we created an electro­acoustic composition in which we tell the story of comets visiting our Solar System, repeating their cycle, curving around the sun and releasing water, carrying away dust to form their tails. Smell In collaboration with The Open University, UK, postcards with a smell of the comet were created, introducing the chemical components of the comet. The smell was recreated by combining several molecules that were found in the comet's coma with the ROSINA instrument: in particular, hydrogen cyanide, ammonia and hydrogen sulphide. Interactive: Augmented Reality (AR) Inspired by spectroscopic data from OSIRIS, I introduce AR to reveal a "hidden" layer. I am highlighting that some scientific information can only be viewed by using special instruments, in this case - instruments on board the Rosetta spacecraft. Viewers can see a virtual layer on top of my paintings using a readily available instrument - ones cellphone. RGB colors, of a particular wavelength, will be introduced to the generally monochromatic paintings. Through my art I study the relationship between humans and the Universe, understanding the connection, the influence and the effect they have on each other. ESA's example of human scientists ambitiously exploring a distant cosmic object empowers me to create and share my personal exploration. This is the way I would like to share comet 67P with the world. I invite you to look through an artist's eyes and see science with renewed beauty and wonder. To view the artwork: http://www.ekaterina-smirnova.com/67p/ http://www.ekaterina-smirnova.com/67p-sculptures/

Bright Comet ISON

NASA Image and Video Library

2013-11-22

Comet ISON shines brightly in this image taken on the morning of 19 Nov. 2013. This is a 10-second exposure taken with the Marshall Space Flight Center 20" telescope in New Mexico. The camera there is black and white, but the smaller field of view allows for a better "zoom in" on the comet's coma, which is essentially the head of the comet. Credit: NASA/MSFC/MEO/Cameron McCarty -------- More details on Comet ISON: Comet ISON began its trip from the Oort cloud region of our solar system and is now travelling toward the sun. The comet will reach its closest approach to the sun on Thanksgiving Day -- 28 Nov 2013 -- skimming just 730,000 miles above the sun's surface. If it comes around the sun without breaking up, the comet will be visible in the Northern Hemisphere with the naked eye, and from what we see now, ISON is predicted to be a particularly bright and beautiful comet. Catalogued as C/2012 S1, Comet ISON was first spotted 585 million miles away in September 2012. This is ISON's very first trip around the sun, which means it is still made of pristine matter from the earliest days of the solar system’s formation, its top layers never having been lost by a trip near the sun. Comet ISON is, like all comets, a dirty snowball made up of dust and frozen gases like water, ammonia, methane and carbon dioxide -- some of the fundamental building blocks that scientists believe led to the formation of the planets 4.5 billion years ago. NASA has been using a vast fleet of spacecraft, instruments, and space- and Earth-based telescope, in order to learn more about this time capsule from when the solar system first formed. The journey along the way for such a sun-grazing comet can be dangerous. A giant ejection of solar material from the sun could rip its tail off. Before it reaches Mars -- at some 230 million miles away from the sun -- the radiation of the sun begins to boil its water, the first step toward breaking apart. And, if it survives all this, the intense radiation and pressure as it flies near the surface of the sun could destroy it altogether. This collection of images show ISON throughout that journey, as scientists watched to see whether the comet would break up or remain intact. The comet reaches its closest approach to the sun on Thanksgiving Day -- Nov. 28, 2013 -- skimming just 730,000 miles above the sun’s surface. If it comes around the sun without breaking up, the comet will be visible in the Northern Hemisphere with the naked eye, and from what we see now, ISON is predicted to be a particularly bright and beautiful comet. ISON stands for International Scientific Optical Network, a group of observatories in ten countries who have organized to detect, monitor, and track objects in space. ISON is managed by the Keldysh Institute of Applied Mathematics, part of the Russian Academy of Sciences. NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Variation of sperm head shape and tail length in a species of Australian hydromyine rodent: the spinifex hopping mouse, Notomys alexis.

PubMed

Bauer, M; Breed, W G

2006-01-01

In Australia, there are around 60 species of murid rodents that occur in the subfamily Hydromyinae, most of which produce highly complex, monomorphic, spermatozoa in which the head has an apical hook together with two ventral processes containing filamentous actin and a long tail of species-specific length. One of the few exceptions to this is the spinifex hopping mouse, Notomys alexis, whose spermatozoa have previously been shown to have pleiomorphic heads. In this study, the structural organisation of the sperm head has been investigated in more detail and the variability in length of the midpiece and total length of the sperm tail has been determined for this species. The findings confirm that pleiomorphic sperm heads are invariably present in these animals and that this variability is associated with that of the nucleus, although nuclear vacuoles were not evident. The total length of the sperm tail, as well as that of the midpiece, was also highly variable both within, as well as between, individual animals. The reason(s) for this high degree of variability in sperm morphology is not known but it may relate to a relaxation of the genetic control of sperm form owing to depressed levels of inter-male sperm competition.

An Evolutionarily Conserved Family of Virion Tail Needles Related to Bacteriophage P22 gp26: Correlation between Structural Stability and Length of the -Helical Trimeric Coiled Coil

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhardwaj, A.; Walker-Kopp, N; Casjens, S

2009-01-01

Bacteriophages of the Podoviridae family use short noncontractile tails to inject their genetic material into Gram-negative bacteria. In phage P22, the tail contains a thin needle, encoded by the phage gene 26, which is essential both for stabilization and for ejection of the packaged viral genome. Bioinformatic analysis of the N-terminal domain of gp26 (residues 1-60) led us to identify a family of genes encoding putative homologues of the tail needle gp26. To validate this idea experimentally and to explore their diversity, we cloned the gp26-like gene from phages HK620, Sf6 and HS1, and characterized these gene products in solution.more » All gp26-like factors contain an elongated {alpha}-helical coiled-coil core consisting of repeating, adjacent trimerization heptads and form trimeric fibers with length ranging between about 240 to 300 {angstrom}. gp26 tail needles display a high level of structural stability in solution, with Tm (temperature of melting) between 85 and 95 C. To determine how the structural stability of these phage fibers correlates with the length of the {alpha}-helical core, we investigated the effect of insertions and deletions in the helical core. In the P22 tail needle, we identified an 85-residue-long helical domain, termed MiCRU (minimal coiled-coil repeat unit), that can be inserted in-frame inside the gp26 helical core, preserving the straight morphology of the fiber. Likewise, we were able to remove three quarters of the helical core of the HS1 tail needle, minimally decreasing the stability of the fiber. We conclude that in the gp26 family of tail needles, structural stability increases nonlinearly with the length of the {alpha}-helical core. Thus, the overall stability of these bacteriophage fibers is not solely dependent on the number of trimerization repeats in the {alpha}-helical core.« less

Systematic random sampling of the comet assay.

PubMed

McArt, Darragh G; Wasson, Gillian R; McKerr, George; Saetzler, Kurt; Reed, Matt; Howard, C Vyvyan

2009-07-01

The comet assay is a technique used to quantify DNA damage and repair at a cellular level. In the assay, cells are embedded in agarose and the cellular content is stripped away leaving only the DNA trapped in an agarose cavity which can then be electrophoresed. The damaged DNA can enter the agarose and migrate while the undamaged DNA cannot and is retained. DNA damage is measured as the proportion of the migratory 'tail' DNA compared to the total DNA in the cell. The fundamental basis of these arbitrary values is obtained in the comet acquisition phase using fluorescence microscopy with a stoichiometric stain in tandem with image analysis software. Current methods deployed in such an acquisition are expected to be both objectively and randomly obtained. In this paper we examine the 'randomness' of the acquisition phase and suggest an alternative method that offers both objective and unbiased comet selection. In order to achieve this, we have adopted a survey sampling approach widely used in stereology, which offers a method of systematic random sampling (SRS). This is desirable as it offers an impartial and reproducible method of comet analysis that can be used both manually or automated. By making use of an unbiased sampling frame and using microscope verniers, we are able to increase the precision of estimates of DNA damage. Results obtained from a multiple-user pooled variation experiment showed that the SRS technique attained a lower variability than that of the traditional approach. The analysis of a single user with repetition experiment showed greater individual variances while not being detrimental to overall averages. This would suggest that the SRS method offers a better reflection of DNA damage for a given slide and also offers better user reproducibility.

Optical and Near-infrared Polarimetry of Non-periodic Comet C/2013 US10 (Catalina)

NASA Astrophysics Data System (ADS)

Kwon, Yuna Grace; Ishiguro, Masateru; Kuroda, Daisuke; Hanayama, Hidekazu; Kawabata, Koji S.; Akitaya, Hiroshi; Nakaoka, Tatsuya; Itoh, Ryosuke; Toda, Hiroyuki; Yanagisawa, Kenshi; Lee, Myung Gyoon; Ohta, Kouji; Yoshida, Michitoshi; Kawai, Nobuyuki; Watanabe, Jun-Ichi

2017-10-01

We present an optical and near-infrared (hereafter NIR) polarimetric study of a comet C/2013 US10 (Catalina) observed on UT 2015 December 17-18 at phase angles of α = 52.°1-53.°1. Additionally, we obtained an optical spectrum and multi-band images to examine the influence of gas emission. We find that the observed optical signals are significantly influenced by gas emission; that is, the gas-to-total intensity ratio varies from 5 to 30% in the R C and 3%-18% in the I C bands, depending on the position in the coma. We derive the “gas-free dust polarization degrees” of 13.8% ± 1.0% in the R C and 12.5% ± 1.1% in the I C bands and a gray polarimetric color, I.e., -8.7% ± 9.9% μm-1 in optical and 1.6% ± 0.9% μm-1 in NIR. The increments of polarization obtained from the gas correction show that the polarimetric properties of the dust in this low-polarization comet are not different from those in high-polarization comets. In this process, the cometocentric distance dependence of polarization has disappeared. We also find that the R C-band polarization degree of the southeast dust tail, which consists of large dust particles (100 μm-1 mm), is similar to that in the outer coma where small and large ones are mixed. Our study confirms that the dichotomy of cometary polarization does not result from the difference of dust properties, but from depolarizing gas contamination. This conclusion can provide a strong support for similarity in origin of comets.

CCD imaging and photometry of 46P/Wirtanen during October 1996

NASA Astrophysics Data System (ADS)

Fink, Uwe; Fevig, Ron A.; Tegler, Stephen C.; Romanishin, William

1997-11-01

During the period of 96 Oct. 7.16 to Oct. 12.14 comet P/Wirtanen was observed with our CCD system at the 154 cm Catalina Observatory telescope at a heliocentric distance near 2.1 AU. The comet exhibited a coma of about 7 in in diameter with a tail of about 14 in. The observed B, V and R magnitudes within a 9.3 in diameter aperture were 19.94, 19.11 and 18.73, respectively. The large majority of our observations were carried out with a filter combining the V and R passbands (V+R). The average V+R magnitudes for Oct. 7.16, 8.14, 9.12 and 10.15, respectively, were 18.91, 18.87, 18,87 and 18.86. The data did not allow the extraction of a lightcurve but hopefully can be used in conjunction with other observations to constrain the comet's rotation period. An attempt to separate the nucleus contribution from the coma resulted in an upper limit to the nuclear magnitude of ≈20.6 in V+R at a phase of 26° or ≈19.6 at 0° phase angle. This results in an upper limit of 1.2 km for the comet's radius assuming a geometric albedo of 0.04. Calculating the Afϱ yielded a value of 7 cm which is a factor of 170 smaller than P/Halley at a comparable heliocentric distance and phase angle. Making the simple assumption that the comet's activity is proportional to its surface area makes the surface area of Wirtanen about 2.4 km 2, equivalent to an effective radius of ≈0.44 km.

Investigating the Spatial Structure of HCN Emission in Comet C/2012 F6 (Lemmon)

NASA Astrophysics Data System (ADS)

Booth, Shawn; Burkhardt, Andrew; Corby, Joanna; Dollhopf, Niklaus; Rawlings, Mark; Remijan, Anthony

2015-11-01

Comets are of particular interest in the field of Astrochemistry as they can be used as a direct probe of formation chemistry of the Solar System. Originating in the Oort Cloud reservoir, these long period objects experience relatively limited solar influence. The majority of cometary material (water, methane and ammonia ices) has remained in the same state as when it formed. These ices are precursors to more complex molecules which have been shown to form amino acids that are crucial for the development of life. HCN, or hydrogen cyanide, is of particular interest because it can form the nucleobase adenine (C5H5N5). The goals of this project are to map the HCN distribution of Comet C/2012 F6 (Lemmon) and to show the simultaneous observation capabilities of the Atacama Large Millimeter/Submillimeter Array (ALMA), which allows the extraction of 7-m array, 12-m array and single dish observation data. On UT 2013 May 11, Comet Lemmon was observed using ALMA. The Cycle 1 configuration was used with the Band 6 receivers, with a 1.5 GHz range centered on the HCN transition at 265.86 GHz, which gave a spectral resolution of 0.07 km/s. We show that Comet Lemmon has both a compact HCN region (found with the 12-m array) and also an extended component, forming a tail-like structure in the anti-motion direction (found with the 7-m array). We were also able to extract the autocorrelation data (single dish) and show that it is viable. This project was supported and funded by NRAO in conjunction with the National Science Foundation (NSF), with special thanks to the Astronomy Department at University of Virginia.

Use of a standardized JaCVAM in vivo rat comet assay protocol to assess the genotoxicity of three coded test compounds; ampicillin trihydrate, 1,2-dimethylhydrazine dihydrochloride, and N-nitrosodimethylamine.

PubMed

McNamee, J P; Bellier, P V

2015-07-01

As part of the Japanese Center for the Validation of Alternative Methods (JaCVAM)-initiative international validation study of the in vivo rat alkaline comet assay (comet assay), our laboratory examined ampicillin trihydrate (AMP), 1,2-dimethylhydrazine dihydrochloride (DMH), and N-nitrosodimethylamine (NDA) using a standard comet assay validation protocol (v14.2) developed by the JaCVAM validation management team (VMT). Coded samples were received by our laboratory along with basic MSDS information. Solubility analysis and range-finding experiments of the coded test compounds were conducted for dose selection. Animal dosing schedules, the comet assay processing and analysis, and statistical analysis were conducted in accordance with the standard protocol. Based upon our blinded evaluation, AMP was not found to exhibit evidence of genotoxicity in either the rat liver or stomach. However, both NDA and DMH were observed to cause a significant increase in % tail DNA in the rat liver at all dose levels tested. While acute hepatoxicity was observed for these compounds in the high dose group, in the investigators opinion there were a sufficient number of consistently damaged/measurable cells at the medium and low dose groups to judge these compounds as genotoxic. There was no evidence of genotoxicity from either NDA or DMH in the rat stomach. In conclusion, our laboratory observed increased DNA damage from two blinded test compounds in rat liver (later identified as genotoxic carcinogens), while no evidence of genotoxicity was observed for the third blinded test compound (later identified as a non-genotoxic, non-carcinogen). This data supports the use of a standardized protocol of the in vivo comet assay as a cost-effective alternative genotoxicity assay for regulatory testing purposes. Crown Copyright © 2015. Published by Elsevier B.V. All rights reserved.

CONSTRAINING THE DUST COMA PROPERTIES OF COMET C/SIDING SPRING (2013 A1) AT LARGE HELIOCENTRIC DISTANCES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Jian-Yang; Samarasinha, Nalin H.; Kelley, Michael S. P.

2014-12-10

The close encounter of comet C/2013 A1 (Siding Spring) with Mars on 2014 October 19 presented an extremely rare opportunity to obtain the first flyby quality data of the nucleus and inner coma of a dynamically new comet. However, the comet's dust tail potentially posed an impact hazard to those spacecraft orbiting Mars. To characterize the comet at large heliocentric distances, study its long-term evolution, and provide critical inputs to hazard modeling, we imaged C/Siding Spring with the Hubble Space Telescope when the comet was at 4.58, 3.77, and 3.28 AU from the Sun. The dust production rate, parameterized bymore » the quantity Afρ, was 2500, 2100, and 1700 cm (5000 km radius aperture) for the three epochs, respectively. The color of the dust coma is (5.0 ± 0.3)%/100 nm for the first two epochs, and (9.0 ± 0.3)%/100 nm for the last epoch, and reddens with increasing cometocentric distance out to ∼3000 km from the nucleus. The spatial distribution and the temporal evolution of the dust color are most consistent with the existence of icy grains in the coma. Two jet-like dust features appear in the northwest and south-southeast directions projected in the sky plane. Within each epoch of 1-2 hr, no temporal variations were observed for either feature, but the position angle of the south-southeastern feature varied between the three epochs by ∼30°. The dust feature morphology suggests two possible orientations for the rotational pole of the nucleus, (R.A., decl.) = (295° ± 5°, +43° ± 2°) and (190° ± 10°, +50° ± 5°), or their diametrically opposite orientations.« less

Preliminary report of results from the plasma science experiment on Mariner 10

NASA Technical Reports Server (NTRS)

Bridge, H. S.; Lazarus, A. J.; Ogilvie, K. W.; Scudder, J. D.; Hartle, R. E.; Asbridge, J. R.; Bame, S. J.; Feldman, W. C.; Siscoe, G. L.; Yeates, C. M.

1974-01-01

Preliminary measurements of electron number density and temperature near Venus and Mercury and some results on flow speeds are presented. It is concluded that the interaction of the solar wind with Venus probably results in a bow shock characterized by H/r = 0.01 (ratio of the ionospheric scale height to the planetocentric distance of the nose of the ionopause); an extended exosphere appears unlikely. This direct interaction is indicated by the behavior of electrons with energies of 100-500 eV. Some unusual downstream effects suggest a comet-like tail several hundred scale lengths long. Near Mercury, a fully developed bow shock and magnetosheath were observed. Inside the magnetosheath there is a region analogous to the magnetosphere of the earth and populated by electrons of lower density and temperature than those found in the solar wind. The solar wind ram pressure corresponds to a stagnation pressure equivalent to a 170 gamma magnetic field. The strong solar wind interaction with Mercury is definitely magnetic, but not ionospheric or atmospheric. Spectra and particle flux varied widely while the spaceship was within the magnetosphere itself; temporal events like substorms may be responsible.

Hubble Witnesses an Asteroid Mysteriously Disintegrating

NASA Image and Video Library

2014-03-06

This series of images shows the asteroid P/2013 R3 breaking apart, as viewed by the NASA/ESA Hubble Space Telescope in 2013. This is the first time that such a body has been seen to undergo this kind of break-up. The Hubble observations showed that there are ten distinct objects, each with comet-like dust tails, embedded within the asteroid's dusty envelope. The four largest rocky fragments are up to 200 metres in radius, about twice the length of a football pitch. The date increases from left to right, with frames from 29 October 2013, 15 November 2013, 13 December 2013, and 14 January 2014 respectively, showing how the clumps of debris material move around. The 14 January 2014 frame was not included in the science paper and is additional data. Credit: NASA, ESA, D. Jewitt (UCLA) Read more: 1.usa.gov/1ig2E0x NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Use of Arctium lappa Extract Against Acetaminophen-Induced Hepatotoxicity in Rats.

PubMed

El-Kott, Attalla Farag; Bin-Meferij, Mashael Mohammed

2015-12-01

Severe destructive hepatic injuries can be induced by acetaminophen overdose and may lead to acute hepatic failure. To investigate the ameliorative effects of Arctium lappa root extract on acetaminophen-induced hepatotoxicity. Rats were divided into 4 groups: normal control group, Arctium lappa extract group, acetaminophen-injected group, and acetaminophen treated with Arctium lappa extract group. The treatment with Arctium lappa extract reduced serum alanine transaminase, aspartate aminotransferase, and alkaline phosphatase in the acetaminophen group when compared with the control group. DNA fragments in the acetaminophen-injected group were also significantly increased (P < 0.05). The comet assay revealed increased detaching tail length and DNA concentration during the hepatic toxicity in the acetaminophen group. The malondialdehyde content was inhibited by Arctium lappa treatment (12.97±0.89 nmol/mg) when compared with the acetaminophen-treated-only group (12.97±0.89 nmol/mg). Histopathologic examination revealed that acetaminophen administration produced hepatic cell necrosis, infiltrate of lymphocytes, and vacuolation that were associated with the acetaminophen-treated animal group, but the degree of acetaminophen-induced hepatotoxicity was mediated by treatment with Arctium lappa extract. Arctium lappa can prevent most of the hepatic tissue damage caused by acetaminophen overdose in rats.

Tail position affects the body temperature of rats during cold exposure in a low-energy state.

PubMed

Uchida, Yuki; Tokizawa, Ken; Nakamura, Mayumi; Lin, Cheng-Hsien; Nagashima, Kei

2012-02-01

Rats place their tails underneath their body trunks when cold (tail-hiding behavior). The aim of the present study was to determine whether this behavior is necessary to maintain body temperature. Male Wistar rats were divided into 'fed' and '42-h fasting' groups. A one-piece tail holder (8.4 cm in length) that prevented the tail-hiding behavior or a three-piece tail holder (2.8 cm in length) that allowed for the tail-hiding behavior was attached to the tails of the rats. The rats were exposed to 27°C for 180 min or to 20°C for 90 min followed by 15°C for 90 min with continuous body temperature and oxygen consumption measurements. Body temperature decreased by -1.0 ± 0.1°C at 15°C only in the rats that prevented tail-hiding behavior of the 42-h fasting group, and oxygen consumption increased at 15°C in all animals. Oxygen consumption was not different between the rats that prevented tail-hiding behavior and the rats that allowed the behavior in the fed and 42-h fasting groups under ambient conditions. These results show that the tail-hiding behavior is involved in thermoregulation in the cold in fasting rats.

67P, Singing Comet

NASA Astrophysics Data System (ADS)

Smirnova, Ekaterina

2017-04-01

I would like to propose to present a short science-art-music collaboration film called "67P, Singing Comet" (5:27 min). If time of the session will allow, prior to the film I would like to make a slide show introduction to this project, highlighting the inspiration - the mission Rosetta by the European Space Agency (ESA) - and the artistic collaboration that took place in creating this piece. Inspired by the ESA Rosetta mission to the comet 67P, Ekaterina Smirnova (artist and project director, New York), Lee Mottram (clarinetist, Wales), Takuto Fukuda (composer, Japan) and Brian Hekker (video editor, New York) collaborated to create a unique atmospheric piece. Water and the origins of life throughout the Universe (specifically the Earth) is an element of the mission and the focus of Ekaterina's artistic vision. Ekaterina literally and figuratively paints a sensory assemblage using a combination of synthetic and natural elements to shape this artistic creation. To paint her watercolor works she is using a replica of the water found on the comet and implementing her own heartbeat into the music to create a recognizable inward sound of life. The Electro-Acoustic composition by Takuto Fukuda features an electronically manipulated performance by clarinetist Lee Mottram. The piece ceremoniously begins with reverberant bursts of low-register atonal bells transporting the listener to their ethereal inner origins of body and mind. The imagination takes the experience to an unknown destination as it gains speed gliding through the visual and audible textures of space and time. The comet's water similarly reacts with an ebb and flow thawing ice to potentially give life a chance as it is thrust along an orbit around the Sun. Near then far from the heat the comet forms frozen particles from vapors as it reaches it's furthest stretches creating an aerodynamic tail of icicles that slowly dissipate in a cycle that repeats itself until the comet's ultimate collision with an obstacle violating it's path. A type of galactic intersection that may be have been the origin of life here on Earth. To view the video, please visit: http://www.ekaterina-smirnova.com/67p-music/

The use of comet assay to assess DNA integrity of boar spermatozoa following liquid preservation at 5 degrees C and 16 degrees C.

PubMed

Fraser, L; Strzezek, J

2004-01-01

The comet assay, under neutral conditions, allows the assessment of DNA integrity influenced by sperm ageing, which is manifested in DNA double-strand breaks. Here, we attempted to use a modified neutral comet assay test (single-cell gel electrophoresis), to our knowledge for the first time, to assess DNA integrity of boar spermatozoa during liquid storage for 96 h at 5 degrees C and 16 degrees C. In this comet assay protocol we used 2% beta-mercaptoethanol prior to the lysis procedure, to aid in removing nuclear proteins. Ejaculates from 3 boars (designated A, C and G) were diluted with a standard semen extender, Kortowo-3 (K-3), which was supplemented with lipoprotein fractions extracted from hen egg yolk (LPFh) or ostrich egg yolk (LPFo). Irrespective of the extender type, the percentage of comet-detected spermatozoa with damaged DNA increased gradually during prolonged storage at 5 degrees C and 16 degrees C. Spermatozoa stored in K-3 extender exhibited elevated levels of DNA damage at both storage temperatures. Significant differences in DNA damage among the boars were more pronounced during storage in LPF-based extenders at 5 degrees C: spermatozoa of boars A and G were less susceptible to DNA damage. The percent of tail DNA in comets was lower in LPF-based extenders, and there were individual variations among the boars. We observed that changes in DNA integrity were dependent on the extender type and storage temperature. A higher level of DNA instability was observed in K-3 extended semen compared with K-3/LPFh or K-3/LPFo extended semen during storage at 5 degrees C. No significant difference in the level of DNA damage between K-3/LPFh and K-3/LPFo was observed. It seems that a long-term storage can affect genomic integrity of boar spermatozoa. The modified neutral comet assay can be used to detect low levels of DNA damage in boar spermatozoa during liquid preservation. Therefore, screening for sperm DNA damage may be used as an additional test of sperm function that can have diagnostic value in practice.

Development of a Test Method for the Evaluation of DNA Damage in Mouse Spermatogonial Stem Cells

PubMed Central

Jeon, Hye Lyun; Yi, Jung-Sun; Kim, Tae Sung; Oh, Youkyung; Lee, Hye Jeong; Lee, Minseong; Bang, Jin Seok; Ko, Kinarm; Ahn, Il Young; Ko, Kyungyuk; Kim, Joohwan; Park, Hye-Kyung; Lee, Jong Kwon; Sohn, Soo Jung

2017-01-01

Although alternative test methods based on the 3Rs (Replacement, Reduction, Refinement) are being developed to replace animal testing in reproductive and developmental toxicology, they are still in an early stage. Consequently, we aimed to develop alternative test methods in male animals using mouse spermatogonial stem cells (mSSCs). Here, we modified the OECD TG 489 and optimized the in vitro comet assay in our previous study. This study aimed to verify the validity of in vitro tests involving mSSCs by comparing their results with those of in vivo tests using C57BL/6 mice by gavage. We selected hydroxyurea (HU), which is known to chemically induce male reproductive toxicity. The 50% inhibitory concentration (IC50) value of HU was 0.9 mM, as determined by the MTT assay. In the in vitro comet assay, % tail DNA and Olive tail moment (OTM) after HU administration increased significantly, compared to the control. Annexin V, PI staining and TUNEL assays showed that HU caused apoptosis in mSSCs. In order to compare in vitro tests with in vivo tests, the same substances were administered to male C57BL/6 mice. Reproductive toxicity was observed at 25, 50, 100, and 200 mg/kg/day as measured by clinical measures of reduction in sperm motility and testicular weight. The comet assay, DCFH-DA assay, H&E staining, and TUNEL assay were also performed. The results of the test with C57BL/6 mice were similar to those with mSSCs for HU treatment. Finally, linear regression analysis showed a strong positive correlation between results of in vitro tests and those of in vivo. In conclusion, the present study is the first to demonstrate the effect of HU-induced DNA damage, ROS formation, and apoptosis in mSSCs. Further, the results of the current study suggest that mSSCs could be a useful model to predict male reproductive toxicity. PMID:28443181

Correlation between length and tilt of lipid tails

NASA Astrophysics Data System (ADS)

Kopelevich, Dmitry I.; Nagle, John F.

2015-10-01

It is becoming recognized from simulations, and to a lesser extent from experiment, that the classical Helfrich-Canham membrane continuum mechanics model can be fruitfully enriched by the inclusion of molecular tilt, even in the fluid, chain disordered, biologically relevant phase of lipid bilayers. Enriched continuum theories then add a tilt modulus κθ to accompany the well recognized bending modulus κ. Different enrichment theories largely agree for many properties, but it has been noticed that there is considerable disagreement in one prediction; one theory postulates that the average length of the hydrocarbon chain tails increases strongly with increasing tilt and another predicts no increase. Our analysis of an all-atom simulation favors the latter theory, but it also shows that the overall tail length decreases slightly with increasing tilt. We show that this deviation from continuum theory can be reconciled by consideration of the average shape of the tails, which is a descriptor not obviously includable in continuum theory.

Comet ISON Passes Through Virgo

NASA Image and Video Library

2013-11-22

Date: 8 Nov 2013 - Comet ISON shines in this five-minute exposure taken at NASA's Marshall Space Flight Center on Nov. 8, 2013.. The image was captured using a color CCD camera attached to a 14" telescope located at Marshall. At the time of this picture, comet ISON was 97 million miles from Earth, moving ever closer toward the sun. Credit: NASA/MSFC/Aaron Kingery -------- More details on Comet ISON: Comet ISON began its trip from the Oort cloud region of our solar system and is now travelling toward the sun. The comet will reach its closest approach to the sun on Thanksgiving Day -- 28 Nov 2013 -- skimming just 730,000 miles above the sun's surface. If it comes around the sun without breaking up, the comet will be visible in the Northern Hemisphere with the naked eye, and from what we see now, ISON is predicted to be a particularly bright and beautiful comet. Catalogued as C/2012 S1, Comet ISON was first spotted 585 million miles away in September 2012. This is ISON's very first trip around the sun, which means it is still made of pristine matter from the earliest days of the solar system’s formation, its top layers never having been lost by a trip near the sun. Comet ISON is, like all comets, a dirty snowball made up of dust and frozen gases like water, ammonia, methane and carbon dioxide -- some of the fundamental building blocks that scientists believe led to the formation of the planets 4.5 billion years ago. NASA has been using a vast fleet of spacecraft, instruments, and space- and Earth-based telescope, in order to learn more about this time capsule from when the solar system first formed. The journey along the way for such a sun-grazing comet can be dangerous. A giant ejection of solar material from the sun could rip its tail off. Before it reaches Mars -- at some 230 million miles away from the sun -- the radiation of the sun begins to boil its water, the first step toward breaking apart. And, if it survives all this, the intense radiation and pressure as it flies near the surface of the sun could destroy it altogether. This collection of images show ISON throughout that journey, as scientists watched to see whether the comet would break up or remain intact. The comet reaches its closest approach to the sun on Thanksgiving Day -- Nov. 28, 2013 -- skimming just 730,000 miles above the sun’s surface. If it comes around the sun without breaking up, the comet will be visible in the Northern Hemisphere with the naked eye, and from what we see now, ISON is predicted to be a particularly bright and beautiful comet. ISON stands for International Scientific Optical Network, a group of observatories in ten countries who have organized to detect, monitor, and track objects in space. ISON is managed by the Keldysh Institute of Applied Mathematics, part of the Russian Academy of Sciences. NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

The dust environment of comet 67P/Churyumov-Gerasimenko: results from Monte Carlo dust tail modelling applied to a large ground-based observation data set

NASA Astrophysics Data System (ADS)

Moreno, Fernando; Muñoz, Olga; Gutiérrez, Pedro J.; Lara, Luisa M.; Snodgrass, Colin; Lin, Zhong Y.; Della Corte, Vincenzo; Rotundi, Alessandra; Yagi, Masafumi

2017-07-01

We present an extensive data set of ground-based observations and models of the dust environment of comet 67P/Churyumov-Gerasimenko covering a large portion of the orbital arc from about 4.5 au pre-perihelion through 3.0 au post-perihelion, acquired during the current orbit. In addition, we have also applied the model to a dust trail image acquired during this orbit, as well as to dust trail observations obtained during previous orbits, in both the visible and the infrared. The results of the Monte Carlo modelling of the dust tail and trail data are generally consistent with the in situ results reported so far by the Rosetta instruments Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) and Grain Impact Analyser and Dust Accumulator (GIADA). We found the comet nucleus already active at 4.5 au pre-perihelion, with a dust production rate increasing up to ˜3000 kg s-1 some 20 d after perihelion passage. The dust size distribution at sizes smaller than r = 1 mm is linked to the nucleus seasons, being described by a power law of index -3.0 during the comet nucleus southern hemisphere winter but becoming considerably steeper, with values between -3.6 and -4.3, during the nucleus southern hemisphere summer, which includes perihelion passage (from about 1.7 au inbound to 2.4 au outbound). This agrees with the increase of the steepness of the dust size distribution found from GIADA measurements at perihelion showing a power index of -3.7. The size distribution at sizes larger than 1 mm for the current orbit is set to a power law of index -3.6, which is near the average value of insitu measurements by OSIRIS on large particles. However, in order to fit the trail data acquired during past orbits previous to the 2009 perihelion passage, a steeper power-law index of -4.1 has been set at those dates, in agreement with previous trail modelling. The particle sizes are set at a minimum of r = 10 μm, and a maximum size, which increases with decreasing heliocentric distance, in the 1-40 cm radius domain. The particle terminal velocities are found to be consistent with the in situ measurements as derived from the instrument GIADA on board Rosetta.

The cometary magnetic field and its associated electric currents

NASA Technical Reports Server (NTRS)

Ip, W.-H.; Mendis, D. A.

1975-01-01

Two different observations of Comet Kohoutek (1973f) seem to suggest the existence of substantial magnetic fields (not less than 100 gammas) in its coma and tail. The effects of the currents and hydromagnetic waves associated with these magnetic fields are considered. It is shown that while the currents closing through the inner coma may represent an important source of ionization in that region, the dissipation of hydromagnetic waves may also be a significant, if not dominant, source of heating there.

Developmental origin of limb size variation in lizards.

PubMed

Andrews, Robin M; Skewes, Sable A

2017-05-01

In many respects, reptile hatchlings are fully functional, albeit miniature, adults. This means that the adult morphology must emerge during embryonic development. This insight emphasizes the connection between the mechanisms that generate phenotypic variation during embryonic development and the action of selection on post-hatching individuals. To determine when species-specific differences in limb and tail lengths emerge during embryonic development, we compared allometric patterns of early limb growth of four distantly related species of lizards. The major questions addressed were whether early embryonic limb and tail growth is characterized by the gradual (continuous allometry) or by the abrupt emergence (transpositional allometry) of size differences among species. Our observations supported transpositional allometry of both limbs and tails. Species-specific differences in limb and tail length were exhibited when limb and tail buds first protruded from the body wall. Genes known to be associated with early limb development of tetrapods are obvious targets for studies on the genetic mechanisms that determine interspecific differences in relative limb length. Broadly comparative studies of gene regulation would facilitate understanding of the mechanisms underlying adaptive variation in limb size, including limb reduction and loss, of squamate reptiles. © 2017 Wiley Periodicals, Inc.

Chromosomal aberrations and DNA damage in human populations exposed to the processing of electronics waste.

PubMed

Liu, Qiang; Cao, Jia; Li, Ke Qiu; Miao, Xu Hong; Li, Guang; Fan, Fei Yue; Zhao, Yong Cheng

2009-05-01

It has been known that the pollutants of electronic wastes (E-wastes) can lead to severe pollution to the environment. It has been reported that about 50% to 80% of E-wastes from developed countries are exported to Asia and Africa. It has become a major global environmental problem to deal with 'E-wastes'. E-waste recycling has remained primitive in Jinghai, China. This not only produces enormous environmental pollution but also can bring about toxic or genotoxic effects on the human body, threatening the health of both current residents and future generations living in the local environment. The concentration of lead in the blood of children in the E-waste polluted area in China is higher than that of the control area. But little is known about the cytogenetic effect to human beings caused by the pollution of E-wastes. In the present study, experiments have been performed to investigate the genetics of permanent residents of three villages with numerous E-waste disposal sites and to analyze the harmful effects of exposure to E-wastes. In total, 171 villagers (exposed group) were randomly selected from permanent residents of three villages located in Jinghai County of Tianjin, China, where there has been massive disposal of E-wastes. Thirty villagers were selected from the neighboring towns without E-waste disposal sites to serve as controls. Chromosomal aberrations and cytokinesis blocking micronucleus were performed to detect the cytogenetic effect, dic + r (dicentric and ring chromosome), monomer, fragments (acentric fragments, minute chromosomes, and acentric rings), translocation, satellite, quadriradial, total aberrations, and micronuclear rate were scored for each subject. DNA damage was detected using comet assay; the DNA percentage in the comet tail (TDNA%), tail moment (TM), and Olive tail moment (OTM) were recorded to describe DNA damage to lymphocytes. The total chromosome aberration rates (5.50%) and micronuclear rates (16.99%) of the exposure group were significantly higher than in the control group (P = 0.000). The percentage of DNA in the comet tail, tail moment, and Olive tail moment detected by comet assay showed that there was a significant difference in DNA damage in the exposure group (P = 0.000). The chromosome aberration, micronucleus rate, and DNA damage observed in women were significantly higher than those in men. Chromosome aberration and micronuclear rates of both smokers and non-smokers in the exposure group are obviously higher than that in the control group (P = 0.000). The use of outdated (and unsafe) ways to deal with E-wastes can lead to exposure to a variety of substances harmful to human health. The components of pollution may enter the human body through the air, drinking water, and food chain to damage human genetic material, resulting in genomic instability. The rates of chromosomal aberration, micronucleus formation, and the degree of DNA damage in women in the group exposed to electronic waste were significantly higher than in men. The reason for this may be concerned with the traditional lifestyle of the local residents or the difference of sensitivity to the exposure to E-wastes or any others. Further investigations are needed to provide evidence to demonstrate this. Here, we report the obviously cytogenetic toxicity to the exposure population by the E-waste pollution for the first time. E-waste pollution may be a potential agent of genetic mutation, and may induce cytogenetic damage within the general population exposed to the pollution. These findings need to be considered, and steps should be taken to protect the current population and future generations from the effects of pollution with E-wastes. The above results remind us that the impact of E-waste recycling on environmental quality of Jinghai should be evaluated soon. Moreover, it is urgent for the government to prohibit E-waste import and its processing by outdated ways. The future studies such as pollutant details of drinking water, air, and soil in the area as well as epidemiological investigations on the harmful effect to children must be performed eagerly. All the data available do provide a compelling case for immediate action in both countries to address workplace health and safety and waste management.

Assessing the genetic diversity of Cu resistance in mine tailings through high-throughput recovery of full-length copA genes

PubMed Central

Li, Xiaofang; Zhu, Yong-Guan; Shaban, Babak; Bruxner, Timothy J. C.; Bond, Philip L.; Huang, Longbin

2015-01-01

Characterizing the genetic diversity of microbial copper (Cu) resistance at the community level remains challenging, mainly due to the polymorphism of the core functional gene copA. In this study, a local BLASTN method using a copA database built in this study was developed to recover full-length putative copA sequences from an assembled tailings metagenome; these sequences were then screened for potentially functioning CopA using conserved metal-binding motifs, inferred by evolutionary trace analysis of CopA sequences from known Cu resistant microorganisms. In total, 99 putative copA sequences were recovered from the tailings metagenome, out of which 70 were found with high potential to be functioning in Cu resistance. Phylogenetic analysis of selected copA sequences detected in the tailings metagenome showed that topology of the copA phylogeny is largely congruent with that of the 16S-based phylogeny of the tailings microbial community obtained in our previous study, indicating that the development of copA diversity in the tailings might be mainly through vertical descent with few lateral gene transfer events. The method established here can be used to explore copA (and potentially other metal resistance genes) diversity in any metagenome and has the potential to exhaust the full-length gene sequences for downstream analyses. PMID:26286020

The morphology of cometary nuclei

NASA Astrophysics Data System (ADS)

Keller, H. U.; Jorda, L.

The sudden appearance of a bright comet stretching over a large part of the night sky must have been one of the most awesome phenomena for early humans watching the sky. The nature of comets remained obscure well into the Middle Ages. Only with the introduction of astronomical techniques and analyses in Europe was the parallax of a comet determined by Tycho Brahe for the first time. He proved that comets are not phenomena of the Earth's atmosphere but are farther away than the Moon; in other words they are interplanetary objects. Later Kepler first predicted that comets follow straight lines, then Hevelius suggested parabolic orbits roughly a hundred years later. It was Halley who suggested that the comets of the years 1531, 1607 and 1682 were apparitions of one and the same comet that would return again in 1758. The success of this prediction made it clear that comets are members of our Solar System. While it was now established that periodic comets are objects of the planetary system, their origin and nature continued to be debated. Were they formed together with the planets from the solar nebula (Kant) or were they of extrasolar origin as suggested by Laplace? This debate lasted for 200 years until well into the second half of the last century. Öpik (1932) suggested that a cloud of comets surrounded our Solar System. This hypothesis was quantified and compared to the observed distribution of orbital parameters (essentially the semi-major axes) of new comets by Oort (1950) (Section 2.1). Comets are scattered into the inner Solar System by perturbations caused by galactic tides, passing stars and large molecular clouds. The Oort cloud would have a radius of 2 105AU, a dimension comparable to the distances of stars in our neighbourhood. The lifetime (limited by decay due to activity and by perturbations caused by encounters with planets) even of the new comets on almost parabolic orbits and typical periods of the order of 106 years is short compared to the age of the planetary system (4.5 Gy). Therefore, observed comets could only recently have arrived on their orbits dipping inside the inner Solar System. This reservoir of comets must have been established during the formation process of the planetary system itself. Cometesimals were agglomerated from interstellar/interplanetary gas and dust and scattered out of the inner Solar System by the giant outer planets (Section 2.3). This scheme implies that a central part of a comet, its nucleus, is stable enough to survive these perturbations. It must also be stable enough to pass the vicinity of the sun for many times in the case of a short-period comet. Comets are bright and large when they are close to the sun and fade quickly when they recede beyond about 2AU. Only with the advent of photography and large astronomical telescopes could a comet be followed until it becomes a starlike point source. What makes comets active near the Sun, blowing their appearances up to the order of 105 km? Bright comets often develop tails two orders of magnitude longer. In an attempt to explain the cometary appearance, Bredichin (1903) introduced a mechanical model where repulsive forces drive the particles away from a central condensation. Spectroscopy revealed that dust grains reflect the solar irradiation. In addition, simple molecules, radicals and ions were found as constituents of the cometary coma and tail. The nature of the central condensation remained mysterious for a long time because of the observational dilemma. When the comet is close to the Earth and therefore to the Sun the dense coma obscures the view into its centre. When activity recedes the comet is too far away and too dim for detailed observations of its central condensation. During the middle of the nineteenth century the connection between comets and meteor streams was established. Schiaparelli (1866) calculated the dispersion of cometary dust within the orbital plane. From this time on the perception that the central condensations of comets were agglomerations of dust particles prevailed for about a century. The gas coma was explained by desorption of molecules from dust particles with large surfaces (Levin 1943). The storage of highly reactive radicals (most observed species (CN, CH, NH2, etc.) were of this category) posed a major difficulty to be explained. The inference that these radicals should be dissociation products of stable parent molecules (such as (CN)2, CH4, NH3, etc.) by Wurm (1934, 1935, 1943) led to our present understanding that these molecules are stored as ices within the central nucleus of a comet. Whipple (1950a,b) combined the astrometrical observations of changes of the orbital periods of comets with the existence of an icy cometary nucleus. The sublimation of ices cause reactive (rocket) non-gravitational forces that increase or decrease the orbital period of an active comet according to the sense of rotation of its nucleus. Evidence in support of the icy conglomerate nucleus became more and more compelling by the derived high gas production rates that could not be stored by adsorption on dust grains (Biermann and Trefftz 1964, Huebner 1965, Keller 1976a,b) and by the same account by the large quantities of dust moving into the cometary tail (Finson and Probstein 1968b). The `sand bank' model (Lyttleton 1953) was clearly dismissed in favour of a solid icy nucleus. Its formation and origin could now be explored. While there was some knowledge about the chemical composition of the nucleus, its physical properties, even the basic ones like size, shape and mass, remained largely unknown because the nucleus could not be observed. Early attempts to derive the nucleus size from the `nuclear' magnitudes of comets at large heliocentric distances while they are inactive (Roemer 1966a,b) led to a systematic overestimation of the size because their residual activity could not be eliminated. The advent of modern detectors and large ground-based telescopes revealed that most comets display residual activity or clouds of dust grains around their nuclei. Taking the residual signal into account (mostly using simple models for the brightness distribution) the size estimates of the nuclei could be improved. The (nuclear) magnitude of a comet depends on the product of its albedo and cross-section. Only in a few cases could the albedo and size of a cometary nucleus be separated by additional observation of its thermal emission at infrared wavelengths. By comparison with outer Solar System asteroids Cruikshank et al. (1985) derived a surprisingly low albedo of about 0.04. A value in clear contradiction to the perception of an icy surface but fully confirmed by the first resolved images of a cometary nucleus during the flybys of the Vega and Giotto spacecraft of comet Halley (Sagdeev et al. 1986, Keller et al. 1986). The improvements of radar techniques led to the detection of reflected signals and finally to the derivation of nuclear dimensions and rotation rates. The observations, however, are also model dependent (rotation and size are similarly interwoven as are albedo and size) and sensitive to large dust grains in the vicinity of a nucleus. As an example, Kamoun et al. (1982) determined the radius of comet Encke to 1.5 (2.3, 1.0) km using the spin axis determination of Whipple and Sekanina (1979). The superb spatial resolution of the Hubble Space Telescope (HST) is not quite sufficient to resolve a cometary nucleus. The intensity distribution of the inner coma, however, can be observed and extrapolated toward the nucleus based on models of the dust distribution. If this contribution is subtracted from the central brightness the signal of the nucleus can be derived and hence its product of albedo times cross-section (Lamy and Toth 1995, Rembor 1998, Keller and Rembor 1998; Section 4.3). It has become clear that cometary nuclei are dark, small, often irregular bodies with dimensions ranging from about a kilometre (comet Wirtanen, the target of the Rosetta comet rendezvous mission) to about 50 km (comet Hale- Bopp, comet P/Schwassman-Wachmann 1). Their albedos are very low, about 0.04. Their shapes are irregular, axes ratios of 2:1 are often derived. Even though comets are characterized by their activity, in most cases only a small fraction of the nuclear surface (in some cases less than 1%) is active. An exception seems to be comet P/Wirtanen where all its surface is required to be active in order to explain its production rates (Rickman and Jorda 1998). The detection of trans-Neptunian objects (TNOs) in the Kuiper belt (Jewitt and Luu 1993) reveals a new population of cometary bodies with dimensions an order of magnitude bigger (100 km and larger) than the typical comet observed in the inner planetary system. Little is known about the extent, density, size distribution and physical characteristics of these objects. This region is supposedly the reservoir for short-period comets, manly those controlled by Jupiter (Jupiter family comets). Our present concept of a cometary nucleus has been strongly influenced by the first pictures of the nucleus of comet Halley achieved during the Giotto flyby in 1986. While this revelation seems to be confirmed as typical by modern observations it carries the danger of prototyping new observational results and inferences. Missions and spacecraft are already on their way (Deep Space, Contour, Stardust, Deep Impact) or in preparation (Rosetta) to diversify our knowledge. The morphology of cometary nuclei is determined by their formation process in the early solar nebula, their dynamics and evolution. The physics of the processes leading to their apparent activity while approaching the Sun are still obscure in many details but determine the small- and intermediate-scale morphology. The large-scale morphology, the shape, of a cometary nucleus is determined by its fragility and inner structure and by its generally complex rotational state. These topics will be reviewed in the following sections. Chemical and compositional aspects will be only discussed where they are important in the framework of the physical evolution of cometary nuclei. More details are given in Chapter 53. A brief survey of the current modelling efforts is given. The fate of cometary nuclei and their decay products follows. A summary and outlook ends this chapter on the morphology of cometary nuclei.

Genotoxicity in child populations exposed to Polycyclic Aromatic Hydrocarbons (PAHs) in the air from Tabasco, Mexico

PubMed Central

Gamboa, Rodríguez T.; Gamboa, Aldeco R.; Bravo, Alvarez H.; Ostrosky, Wegman P.

2008-01-01

The economy of the state of Tabasco is based on oil extraction. However, this imposes major effects to the environment and communities. Examples are the Polycyclic Aromatic Hydrocarbons (PAHs) that may be found in the soil, water and sediment of the region. Their volatility makes them available to living beings and results in genotoxic activity. The purpose of this study was to quantify the levels of PAHs in the air at several points in the state, and to analyze their relationship with possible damage to DNA on local inhabitants. Single Cell Gel Electrophoresis Assay (Comet Assay) was applied to peripheral blood lymphocytes of five groups of children between six and 15 years of age. PAH samples were analyzed following US/EPA TO-13-A method. Results indicated the presence in the air of most of the 16 PAHs considered as high priority by EPA, some of which have been reported with carcinogenic activity. Differences (p<0.05) were found between PAHs concentration in the gaseous component and in the particulate component of air samples, with the greatest values for the gaseous component. Greatest PAH concentrations were detected in areas with high oil extraction activities. Children groups from high oil activity areas presented genotoxic damage labeled from moderate to high according to DNA migration from nuclei (Tail Length: 14.2 – 42.14 μm and Tail/Head: 0.97 – 2.83 μm) compared with control group (12.25 and 0.63 μm, respectively). The group with greatest cell damage was located in the area with the greatest oil activity. We conclude that the presence of PAHs in the air may represent a health risk to populations that are chronically exposed to them at high oil activity regions. PMID:19151429

Description of Globodera ellingtonae n. sp. (Nematoda: Heteroderidae) from Oregon

PubMed Central

Handoo, Zafar A.; Carta, Lynn K.; Skantar, Andrea M.; Chitwood, David J.

2012-01-01

A new species of cyst nematode, Globodera ellingtonae, is described from soil collected from a field in Oregon. Second-stage juveniles (J2) of the species are characterized by body length of 365-515 μm, stylet length of 19-22.5 μm, basal knobs rounded posteriorly and pointed anteriorly, tail 39-55 μm, hyaline tail terminus 20-32.5 μm, and tail tapering uniformly but abruptly narrowing and constricted near the posterior third of the hyaline portion, ending with a peg-like, finely rounded to pointed terminus. Cysts are spherical to sub-spherical, dark to light brown and circumfenestrate and cyst wall pattern is ridge-like with heavy punctations. Males have a stylet length of 21-25 μm and spicule length of 30-37 μm with a pointed thorn-like tip. Females have a stylet length of 20-22.5 μm, one head annule and labial disc, heavy punctations on the cuticle, and short vulval slit 7.5-8 μm long. Morphologically this new, round-cyst species differs from the related species G. pallida, G. rostochiensis, G. tabacum complex and G. mexicana by its distinctive J2 tail, and by one or another of the following: shorter mean stylet length in J2, females and males; number of refractive bodies in the hyaline tail terminus of J2; cyst morphology including Granek’s ratio; number of cuticular ridges between the anus and vulva; and in the shape and length of spicules in males. Its relationship to these closely related species are discussed. Based upon analysis of ribosomal internal transcribed spacer (ITS) sequences, G. ellingtonae n. sp. is distinct from G. pallida, G. rostochiensis, G. tabacum and G. mexicana. Bayesian and Maximum Parsimony analysis of cloned ITS rRNA gene sequences indicated three clades, with intraspecific variability as high as 2.8%. In silico analysis revealed ITS restriction fragment length polymorphisms for enzymes Bsh 1236I, Hinf I, and Rsa I that overlap patterns for other Globodera species. PMID:23483076

Description of Globodera ellingtonae n. sp. (Nematoda: Heteroderidae) from Oregon.

PubMed

Handoo, Zafar A; Carta, Lynn K; Skantar, Andrea M; Chitwood, David J

2012-03-01

A new species of cyst nematode, Globodera ellingtonae, is described from soil collected from a field in Oregon. Second-stage juveniles (J2) of the species are characterized by body length of 365-515 μm, stylet length of 19-22.5 μm, basal knobs rounded posteriorly and pointed anteriorly, tail 39-55 μm, hyaline tail terminus 20-32.5 μm, and tail tapering uniformly but abruptly narrowing and constricted near the posterior third of the hyaline portion, ending with a peg-like, finely rounded to pointed terminus. Cysts are spherical to sub-spherical, dark to light brown and circumfenestrate and cyst wall pattern is ridge-like with heavy punctations. Males have a stylet length of 21-25 μm and spicule length of 30-37 μm with a pointed thorn-like tip. Females have a stylet length of 20-22.5 μm, one head annule and labial disc, heavy punctations on the cuticle, and short vulval slit 7.5-8 μm long. Morphologically this new, round-cyst species differs from the related species G. pallida, G. rostochiensis, G. tabacum complex and G. mexicana by its distinctive J2 tail, and by one or another of the following: shorter mean stylet length in J2, females and males; number of refractive bodies in the hyaline tail terminus of J2; cyst morphology including Granek's ratio; number of cuticular ridges between the anus and vulva; and in the shape and length of spicules in males. Its relationship to these closely related species are discussed. Based upon analysis of ribosomal internal transcribed spacer (ITS) sequences, G. ellingtonae n. sp. is distinct from G. pallida, G. rostochiensis, G. tabacum and G. mexicana. Bayesian and Maximum Parsimony analysis of cloned ITS rRNA gene sequences indicated three clades, with intraspecific variability as high as 2.8%. In silico analysis revealed ITS restriction fragment length polymorphisms for enzymes Bsh 1236I, Hinf I, and Rsa I that overlap patterns for other Globodera species.

New evidence from China for the nature of the pterosaur evolutionary transition

NASA Astrophysics Data System (ADS)

Wang, Xiaoli; Jiang, Shunxing; Zhang, Junqiang; Cheng, Xin; Yu, Xuefeng; Li, Yameng; Wei, Guangjin; Wang, Xiaolin

2017-02-01

Pterosaurs are extinct flying reptiles, the first vertebrates to achieve powered flight. Our understanding of the evolutionary transition between basal, predominantly long-tailed forms to derived short-tailed pterodactyloids remained poor until the discovery of Wukongopterus and Darwinopterus in western Liaoning, China. In this paper we report on a new genus and species, Douzhanopterus zhengi, that has a reduced tail, 173% the length of the humerus, and a reduced fifth pedal digit, whose first phalange is ca. 20% the length of metatarsal III, both unique characters to Monofenestra. The morphological comparisons and phylogenetic analysis presented in this paper demonstrate that Douzhanopterus is the sister group to the ‘Painten pro-pterodactyloid’ and the Pterodactyloidea, reducing the evolutionary gap between long- and short-tailed pterosaurs.

[Protective Effect of S-isopentenyl-L-cysteine against DNA Damage in Irradiated Mice].

PubMed

Zheng, Qi-sheng; Yu, Guang-yun; He, Xin; Jiang, Ming; Chu, Xiao-fei; Zhao, Shu-yi; Fan, Sai-jun; Liu, Pei-xun

2015-10-01

To evaluate the protective effect of S-isopentenyl-L-cysteine,a new cysteine derivative,on DNA damage induced by radiation by using acute radiation injury animal models. Forty ICR mice were randomly divided into five groups:the control group,1.0Gy gamma irradiation group,1.0Gy gamma irradiation combined with S-isopentenyl-L-cysteine group,7.2Gy gamma irradiation group,and 7.2Gy gamma irradiation combined with S-isopentenyl-L-cysteine group,with 8 mice in each group.The comet assay and bone marrow polychromatic micronucleus experiments were performed to evaluate the double-strand DNA breaks in ICR mice exposed to 1.0 and 7.2Gy gamma-ray, respectively. The tail DNA percentage,tail length,tail moment,and olive tail moment of peripheral blood lymphocytes in 7.2Gy gamma irradiation group were significantly higher than that of the control group (P<0.01).And it was also observed that above experimental indexes of 7.2Gy gamma irradiation combined with S-isopentenyl-L-cysteine group was significantly less than that of 7.2Gy gamma irradiation group (P<0.05). In addition,the micronucleus rate of 1.0Gy gamma irradiation group and 7.2Gy gamma irradiation group were both significantly higher than in the control group (P<0.01). In addition,in mice given S-isopentenyl-L-cysteine before irradiation,the micronucleus rate of ICR mice exposed to 1.0 and 7.2Gy gamma-ray decreased from (39.5000 ± 3.3141)‰ to (28.1667±4.1345)‰ (P=0.033) and from (76.5000 ± 4.6242)‰ to (22.8333 ± 3.6553)‰(P=0.000),respectively. The bone marrow polychromatic micronucleus experiment indicated that the value of polychromatic erythrocyte (PCE)/normochromatic erythrocyte(NCE) of ICR mice exposed to 1.0 and 7.2Gy gamma-ray was less than the control group(P<0.05). Meanwhile,after irradiating by certain dose,the value of PCE/NCE in mice given S-isopentenyl-L-cysteine before irradiation was significantly higher than the corresponding groups (P<0.05). S-isopentenyl-L-cysteine has a good protective effect against DNA damage induced by radiation.

Reduction of astrometric plates

NASA Technical Reports Server (NTRS)

Stock, J.

1984-01-01

A rapid and accurate method for the reduction of comet or asteroid plates is described. Projection equations, scale length correction, rotation of coordinates, linearization, the search for additional reference stars, and the final solution are examined.

Survival and reproductive rate of mites in relation to resistance of their barn swallow hosts.

PubMed

Møller, A P

2000-08-01

Parasite resistance may act via a number of different mechanisms that regulate or control the survival and the reproductive rate of parasites. Observations and experiments were used to test for effects of host resistance on parasite survival and rate of reproduction. Natural levels of infestation of barn swallow Hirundo rustica nests by the tropical fowl mite Ornithonyssus bursa were positively related to brood size, inversely related to the length of the outermost tail feathers of male nest owners (a secondary sexual character) and affected by time of reproduction by the host. A mite inoculation experiment, in which 50 adult mites were introduced into nests during the laying period of the host, was used to test for differential survival and reproduction of mites as a function of host resistance. The relationship between survival and reproduction of parasites, male tail length and host resistance was investigated. There was a negative relationship between mite numbers per nest after fledging of nestlings and male tail length. This relationship was mainly caused by a reduction in the number of mites in the first and second nymph stage with increasing tail length of male hosts, implying a reduction in rate of reproduction of mites. The proportion of mites that had recently fed was inversely related to tail length of male hosts. The proportion of nymph stages was positively related to the proportion of mites that had recently had a blood meal. Parasite resistance of barn swallows to the tropical fowl mite thus appeared to act through increased mortality rate of adult and nymph stages of mites, and through reduced reproductive rates of mites on resistant hosts. This is the first study demonstating a direct relationship between fitness components of a parasite and the expression of a secondary sexual character of a host.

Pendular motion in the brachiation of captive Lagothrix and Ateles.

PubMed

Turnquist, J E; Schmitt, D; Rose, M D; Cant, J G

1999-01-01

Pendular motion during brachiation of captive Lagothrix lagothricha lugens and Ateles fusciceps robustus was analyzed to demonstrate similarities, and differences, between these two closely related large bodied atelines. This is the first captive study of the kinematics of brachiation in Lagothrix. Videorecordings of one adult male of each species were made in a specially designed cage constructed at the DuMond Conservancy/Monkey Jungle, Miami, FL. Java software (Jandel Scientific Inc., San Rafael, CA) was used for frame-by-frame kinematic analysis of individual strides/steps. Results demonstrate that the sequence of hand and tail contacts differ significantly between the two species with Lagothrix using a new tail hold with every hand hold, while Ateles generally utilizes a new tail hold with only every other hand hold. Stride length and stride frequency, even after adjusting for limb length, also differ significantly between the two species. Lagothrix brachiation utilizes short, choppy strides with quick hand holds, while Ateles uses long, fluid strides with longer hand holds. During brachiation not only is Lagothrix's body significantly less horizontal than that of Ateles but also, within Ateles, there are significant differences between steps depending on tail use. Because of the unique nature of tail use in Ateles, many aspects of body positioning in Lagothrix more closely resemble Ateles steps without a simultaneous tail hold rather than those with one. Overall pendulum length in Lagothrix is shorter than in Ateles. Tail use in Ateles has a significant effect on maximum pendulum length during a step. Although neither species achieves the extreme pendulum effect and long period of free-flight of hylobatids in fast ricochetal brachiation, in captivity both consistently demonstrate effective brachiation with brief periods of free-flight and pendular motion. Morphological similarities between ateline brachiators and hylobatids are fewer and less pronounced in Lagothrix than in Ateles. This study demonstrates that Lagothrix brachiation is also less hylobatid-like than that of Ateles.

Modeled Image of ISON

NASA Image and Video Library

2013-11-22

In this modeled image of ISON, the coma has been subtracted, leaving behind the nucleus. Credit: NASA, ESA, the Hubble Heritage Team (AURA/STScI) and Jian-Yang Li (Planetary Science Institute) -------- More details on Comet ISON: Comet ISON began its trip from the Oort cloud region of our solar system and is now travelling toward the sun. The comet will reach its closest approach to the sun on Thanksgiving Day -- 28 Nov 2013 -- skimming just 730,000 miles above the sun's surface. If it comes around the sun without breaking up, the comet will be visible in the Northern Hemisphere with the naked eye, and from what we see now, ISON is predicted to be a particularly bright and beautiful comet. Catalogued as C/2012 S1, Comet ISON was first spotted 585 million miles away in September 2012. This is ISON's very first trip around the sun, which means it is still made of pristine matter from the earliest days of the solar system’s formation, its top layers never having been lost by a trip near the sun. Comet ISON is, like all comets, a dirty snowball made up of dust and frozen gases like water, ammonia, methane and carbon dioxide -- some of the fundamental building blocks that scientists believe led to the formation of the planets 4.5 billion years ago. NASA has been using a vast fleet of spacecraft, instruments, and space- and Earth-based telescope, in order to learn more about this time capsule from when the solar system first formed. The journey along the way for such a sun-grazing comet can be dangerous. A giant ejection of solar material from the sun could rip its tail off. Before it reaches Mars -- at some 230 million miles away from the sun -- the radiation of the sun begins to boil its water, the first step toward breaking apart. And, if it survives all this, the intense radiation and pressure as it flies near the surface of the sun could destroy it altogether. This collection of images show ISON throughout that journey, as scientists watched to see whether the comet would break up or remain intact. The comet reaches its closest approach to the sun on Thanksgiving Day -- Nov. 28, 2013 -- skimming just 730,000 miles above the sun’s surface. If it comes around the sun without breaking up, the comet will be visible in the Northern Hemisphere with the naked eye, and from what we see now, ISON is predicted to be a particularly bright and beautiful comet. ISON stands for International Scientific Optical Network, a group of observatories in ten countries who have organized to detect, monitor, and track objects in space. ISON is managed by the Keldysh Institute of Applied Mathematics, part of the Russian Academy of Sciences. NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Empirical scaling of the length of the longest increasing subsequences of random walks

NASA Astrophysics Data System (ADS)

Mendonça, J. Ricardo G.

2017-02-01

We provide Monte Carlo estimates of the scaling of the length L n of the longest increasing subsequences of n-step random walks for several different distributions of step lengths, short and heavy-tailed. Our simulations indicate that, barring possible logarithmic corrections, {{L}n}∼ {{n}θ} with the leading scaling exponent 0.60≲ θ ≲ 0.69 for the heavy-tailed distributions of step lengths examined, with values increasing as the distribution becomes more heavy-tailed, and θ ≃ 0.57 for distributions of finite variance, irrespective of the particular distribution. The results are consistent with existing rigorous bounds for θ, although in a somewhat surprising manner. For random walks with step lengths of finite variance, we conjecture that the correct asymptotic behavior of L n is given by \\sqrt{n}\\ln n , and also propose the form for the subleading asymptotics. The distribution of L n was found to follow a simple scaling form with scaling functions that vary with θ. Accordingly, when the step lengths are of finite variance they seem to be universal. The nature of this scaling remains unclear, since we lack a working model, microscopic or hydrodynamic, for the behavior of the length of the longest increasing subsequences of random walks.

DNA Damage in Euonymus japonicus Leaf Cells Caused by Roadside Pollution in Beijing

PubMed Central

Li, Tianxin; Zhang, Minjie; Gu, Ke; Herman, Uwizeyimana; Crittenden, John; Lu, Zhongming

2016-01-01

The inhalable particles from vehicle exhaust can cause DNA damage to exposed organisms. Research on DNA damage is primarily focused on the influence of specific pollutants on certain species or the effect of environmental pollution on human beings. To date, little research has quantitatively studied the relationship between roadside pollution and DNA damage. Based on an investigation of the roadside pollution in Beijing, Euonymus japonicus leaves of differing ages grown in heavily-polluted sections were chosen as biomonitors to detect DNA damage using the comet assay technique. The percentage of DNA in the tail and tail moment was chosen as the analysis index based on SPSS data analysis. The roadside samples showed significantly higher levels of DNA damage than non-roadside samples, which increased in older leaves, and the DNA damage to Euonymus japonicus leaf cells was positively correlated with haze-aggravated roadside pollution. The correlation between damage and the Air Quality Index (AQI) are 0.921 (one-year-old leaves), 0.894 (two-year-old leaves), and 0.878 (three-year-old leaves). Over time, the connection between DNA damage and AQI weakened, with the sensitivity coefficient for δyear 1 being larger than δyear 2 and δyear 3. These findings support the suitability and sensitivity of the comet assay for surveying plants for an estimation of DNA damage induced by environmental genotoxic agents. This study might be applied as a preliminary quantitative method for Chinese urban air pollution damage assessment caused by environmental stress. PMID:27455298

Evaluation of Genetic Variations in Maize Seedlings Exposed to Electric Field Based on Protein and DNA Markers

PubMed Central

AL-Huqail, Asma A.; Abdelhaliem, Ekram

2015-01-01

The current study analyzed proteins and nuclear DNA of electric fields (ELF) exposed and nonexposed maize seedlings for different exposure periods using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), isozymes, random amplified polymorphic DNA (RAPD), and comet assay, respectively. SDS-PAGE analysis revealed total of 46 polypeptides bands with different molecular weights ranging from 186.20 to 36.00 KDa. It generated distinctive polymorphism value of 84.62%. Leucine-aminopeptidase, peroxidase, and catalase isozymes showed the highest values of polymorphism (100%) based on zymograms number, relative front (R f), and optical intensity while esterase isozyme generated polymorphism value of 83.33%. Amino acids were analyzed using high-performance liquid chromatography, which revealed the presence of 17 amino acids of variable contents ranging from 22.65% to 28.09%. RAPD revealed that 78 amplified DNA products had highly polymorphism value (95.08%) based on band numbers, with variable sizes ranging from 120 to 992 base pairs and band intensity. Comet assay recorded the highest extent of nuclear DNA damage as percentage of tailed DNA (2.38%) and tail moment unit (5.36) at ELF exposure of maize nuclei for 5 days. The current study concluded that the longer ELF exposing periods had genotoxic stress on macromolecules of maize cells and biomarkers used should be augmented for reliable estimates of genotoxicity after exposure of economic plants to ELF stressors. PMID:26180815

Rrp6p controls mRNA polyA tail length and its decoration with polyA binding proteins

PubMed Central

Schmid, Manfred; Poulsen, Mathias Bach; Olszewski, Pawel; Pelechano, Vicent; Saguez, Cyril; Gupta, Ishaan; Steinmetz, Lars M.; Moore, Claire; Jensen, Torben Heick

2012-01-01

PolyA (pA) tail binding proteins (PABPs) control mRNA polyadenylation, stability and translation. In a purified system, S. cerevisiae PABPs, Pab1p and Nab2p, are individually sufficient to provide normal pA tail length. However, it is unknown how this occurs in more complex environments. Here we find that the nuclear exosome subunit Rrp6p counteracts the in vitro and in vivo extension of mature pA tails by the non-canonical pA polymerase Trf4p. Moreover, PABP loading onto nascent pA tails is controlled by Rrp6p; while Pab1p is the major PABP, Nab2p only associates in the absence of Rrp6p. This is because Rrp6p can interact with Nab2p and displace it from pA tails, potentially leading to RNA turnover as evidenced for certain pre-mRNAs. We suggest that a nuclear mRNP surveillance step involves targeting of Rrp6p by Nab2p-bound pA-tailed RNPs and that pre-mRNA abundance is regulated at this level. PMID:22683267

HT-COMET: a novel automated approach for high throughput assessment of human sperm chromatin quality

PubMed Central

Albert, Océane; Reintsch, Wolfgang E.; Chan, Peter; Robaire, Bernard

2016-01-01

STUDY QUESTION Can we make the comet assay (single-cell gel electrophoresis) for human sperm a more accurate and informative high throughput assay? SUMMARY ANSWER We developed a standardized automated high throughput comet (HT-COMET) assay for human sperm that improves its accuracy and efficiency, and could be of prognostic value to patients in the fertility clinic. WHAT IS KNOWN ALREADY The comet assay involves the collection of data on sperm DNA damage at the level of the single cell, allowing the use of samples from severe oligozoospermic patients. However, this makes comet scoring a low throughput procedure that renders large cohort analyses tedious. Furthermore, the comet assay comes with an inherent vulnerability to variability. Our objective is to develop an automated high throughput comet assay for human sperm that will increase both its accuracy and efficiency. STUDY DESIGN, SIZE, DURATION The study comprised two distinct components: a HT-COMET technical optimization section based on control versus DNAse treatment analyses (n = 3–5), and a cross-sectional study on 123 men presenting to a reproductive center with sperm concentrations categorized as severe oligozoospermia, oligozoospermia or normozoospermia. PARTICIPANTS/MATERIALS, SETTING, METHODS Sperm chromatin quality was measured using the comet assay: on classic 2-well slides for software comparison; on 96-well slides for HT-COMET optimization; after exposure to various concentrations of a damage-inducing agent, DNAse, using HT-COMET; on 123 subjects with different sperm concentrations using HT-COMET. Data from the 123 subjects were correlated to classic semen quality parameters and plotted as single-cell data in individual DNA damage profiles. MAIN RESULTS AND THE ROLE OF CHANCE We have developed a standard automated HT-COMET procedure for human sperm. It includes automated scoring of comets by a fully integrated high content screening setup that compares well with the most commonly used semi-manual analysis software. Using this method, a cross-sectional study on 123 men showed no significant correlation between sperm concentration and sperm DNA damage, confirming the existence of hidden chromatin damage in men with apparently normal semen characteristics, and a significant correlation between percentage DNA in the tail and percentage of progressively motile spermatozoa. Finally, the use of DNA damage profiles helped to distinguish subjects between and within sperm concentration categories, and allowed a determination of the proportion of highly damaged cells. LIMITATIONS, REASONS FOR CAUTION The main limitations of the HT-COMET are the high, yet indispensable, investment in an automated liquid handling system and heating block to ensure accuracy, and the availability of an automated plate reading microscope and analysis software. WIDER IMPLICATIONS OF THE FINDINGS This standardized HT-COMET assay offers many advantages, including higher accuracy and evenness due to automation of sensitive steps, a 14.4-fold increase in sample analysis capacity, and an imaging and scoring time of 1 min/well. Overall, HT-COMET offers a decrease in total experimental time of more than 90%. Hence, this assay constitutes a more efficient option to assess sperm chromatin quality, paves the way to using this assay to screen large cohorts, and holds prognostic value for infertile patients. STUDY FUNDING/COMPETING INTEREST(S) Funded by the CIHR Institute of Human Development, Child and Youth Health (IHDCYH; RHF 100625). O.A. is a fellow supported by the Fonds de la Recherche du Québec - Santé (FRQS) and the CIHR Training Program in Reproduction, Early Development, and the Impact on Health (REDIH). B.R. is a James McGill Professor. The authors declare no conflicts of interest. PMID:26975326

Cometary jets in interaction with the solar wind: a hybrid simulation study

NASA Astrophysics Data System (ADS)

Wiehle, Stefan; Motschmann, Uwe; Gortsas, Nikolaos; Mueller, Joachim; Kriegel, Hendrik; Koenders, Christoph; Glassmeier, Karl-Heinz

The effect of a cometary jet on the solar wind interaction is studied using comet 67P/Churyumov-Gerasimenko as case study. This comet is the target of the Rosetta-mission which will arrive in 2014. Observations suggest that cometary outgassing is confined to only a few percent of the cometary surface; thus, the measurement of jets is expected. Most former comet simulations did not attend to this fact and used an isotropic outgassing scheme or simplified outgassing patterns. Here, a single sun-facing jet is set to be the only source of cometary gas produc-tion. Using an analytic profile, this outgassing jet was implemented in a hybrid simulation code which treats protons and cometary heavy ions as particles and electrons as massless fluid. In a simulation series, the geometric parameters of the jet were varied to study the effect of different opening angles while the integrated outgassing rate remained constant. It was shown that the resulting solar wind interaction is highly dependent on the geometry of the jet. The plasma-structures like the solar wind pile-up found in the situation with isotropic outgassing are moved more and more sunward as the opening angle of the jet decreases. Furthermore, the cometary ion tail shows some kind of splitting which is not known from isotropic models.

Ultrastructural Interactions and Genotoxicity Assay of Cerium Dioxide Nanoparticles on Mouse Oocytes

PubMed Central

Courbiere, Blandine; Auffan, Mélanie; Rollais, Raphaël; Tassistro, Virginie; Bonnefoy, Aurélie; Botta, Alain; Rose, Jérôme; Orsière, Thierry; Perrin, Jeanne

2013-01-01

Cerium dioxide nanoparticles (CeO2 ENPs) are on the priority list of nanomaterials requiring evaluation. We performed in vitro assays on mature mouse oocytes incubated with CeO2 ENPs to study (1) physicochemical biotransformation of ENPs in culture medium; (2) ultrastructural interactions with follicular cells and oocytes using Transmission Electron Microscopy (TEM); (3) genotoxicity of CeO2 ENPs on follicular cells and oocytes using a comet assay. DNA damage was quantified as Olive Tail Moment. We show that ENPs aggregated, but their crystal structure remained stable in culture medium. TEM showed endocytosis of CeO2 ENP aggregates in follicular cells. In oocytes, CeO2 ENP aggregates were only observed around the zona pellucida (ZP). The comet assay revealed significant DNA damage in follicular cells. In oocytes, the comet assay showed a dose-related increase in DNA damage and a significant increase only at the highest concentrations. DNA damage decreased significantly both in follicular cells and in oocytes when an anti-oxidant agent was added in the culture medium. We hypothesise that at low concentrations of CeO2 ENPs oocytes could be protected against indirect oxidative stress due to a double defence system composed of follicular cells and ZP. PMID:24185910

Primary DNA damage in chrome-plating workers.

PubMed

Gambelunghe, A; Piccinini, R; Ambrogi, M; Villarini, M; Moretti, M; Marchetti, C; Abbritti, G; Muzi, G

2003-06-30

In order to evaluate the primary DNA damage due to occupational exposure to chromium (VI), DNA strand-breaks and apoptosis in peripheral lymphocytes were measured in a group of 19 chrome-plating workers. DNA strand-breaks was assessed by alkaline (pH>13) single-cell microgel electrophoresis ('comet') assay, while apoptosis was measured by flow-cytometry after propidium iodide staining of the cells. Concentrations of chromium in urine, erythrocytes and lymphocytes were investigated as biological indicators of exposure. A group of 18 hospital workers (control group I) and another 20 university personnel (control group II) without exposure to chromium were also studied as controls. The results of the study show that chrome-plating workers have higher levels of chromium in urine, erythrocytes and lymphocytes than unexposed workers. Comet tail moment values, assumed as index of DNA damage, are increased in chromium-exposed workers and results are significantly correlated to chromium lymphocyte concentrations. No difference emerged in the percentage of apoptotic nuclei in exposed and unexposed workers. The study confirms that measurements of chromium in erythrocytes and lymphocytes may provide useful information about recent and past exposure to hexavalent chromium at the workplace. The increase in DNA strand-breaks measured by comet assay suggests this test is valid for the biological monitoring of workers exposed to genotoxic compounds such as chromium (VI).

Variation in torpor patterns of free-ranging black-tailed and Utah prairie dogs across gradients of elevation

USGS Publications Warehouse

Lehmer, E.M.; Biggins, D.E.

2005-01-01

We compared over-winter body temperature (Tb) patterns for more than 6 months in adult (> 1 year) black-tailed (Cynomys ludovicianus) and Utah (C. parvidens) prairie dogs from colonies located along gradients of elevation in northern Colorado and southern Utah. In general, black-tailed prairie dogs entered torpor facultatively during winter, whereas Utah prairie dogs hibernated continuously for extended periods. Both black-tailed and Utah prairie dogs displayed significant differences in Tb patterns across elevations, with lower elevation populations entering more shallow and infrequent torpor than prairie dogs at higher elevations. Tb patterns of black-tailed prairie dogs followed 24-h cycles, as most prairie dogs entered into and aroused from torpor between 1100 and 1700 h and bout lengths were clustered around 24-h intervals and multiples thereof. Torpor in Utah prairie dogs did not display the same daily patterns; they entered into and aroused from torpor at all times of the day, and bout lengths were variable. Although black-tailed and Utah prairie dogs are closely related, mechanisms that stimulate and control torpor might differ between them.

Trimodal Control of Ion-Transport Activity on Cyclo-oligo-(1→6)-β-D-glucosamine-Based Artificial Ion-Transport Systems.

PubMed

Roy, Arundhati; Saha, Tanmoy; Gening, Marina L; Titov, Denis V; Gerbst, Alexey G; Tsvetkov, Yury E; Nifantiev, Nikolay E; Talukdar, Pinaki

2015-11-23

Cyclo-oligo-(1→6)-β-D-glucosamines functionalized with hydrophobic tails are reported as a new class of transmembrane ion-transport system. These macrocycles with hydrophilic cavities were introduced as an alternative to cyclodextrins, which are supramolecular systems with hydrophobic cavities. The transport activities of these glycoconjugates were manipulated by altering the oligomericity of the macrocycles, as well as the length and number of attached tails. Hydrophobic tails of 3 different sizes were synthesized and coupled with each glucosamine scaffold through the amide linkage to obtain 18 derivatives. The ion-transport activity increased from di- to tetrameric glucosamine macrocycles, but decreased further when flexible pentameric glucosamine was introduced. The ion-transport activity also increased with increasing length of attached linkers. For a fixed length of linkers, the transport activity decreased when the number of such tails was reduced. All glycoconjugates displayed a uniform anion-selectivity sequence: Cl(-) >Br(-) >I(-) . From theoretical studies, hydrogen bonding between the macrocycle backbone and the anion bridged through water molecules was observed. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Periodic Comet Showers, Mass Extinctions, and the Galaxy

NASA Technical Reports Server (NTRS)

Rampino, M. R.; Stothers, R. B.

2000-01-01

Geologic data on mass extinctions of life and evidence of large impacts on the Earth are thus far consistent with a quasi-periodic modulation of the flux of Oort cloud comets. Impacts of large comets and asteroids are capable of causing mass extinction of species, and the records of large impact craters and mass show a correlation. Impacts and extinctions display periods in the range of approximately 31 +/- 5 m.y., depending on dating methods, published time scales, length of record, and number of events analyzed. Statistical studies show that observed differences in the formal periodicity of extinctions and craters are to be expected, taking into consideration problems in dating and the likelihood that both records would be mixtures of periodic and random events. These results could be explained by quasi-periodic showers of Oort Cloud comets with a similar cycle. The best candidate for a pacemaker for comet showers is the Sun's vertical oscillation through the plane of the Galaxy, with a half-period over the last 250 million years in the same range. We originally suggested that the probability of encounters with molecular clouds that could perturb the Oort comet cloud and cause comet showers is modulated by the Sun's vertical motion through the galactic disk. Tidal forces produced by the overall gravitational field of the Galaxy can also cause perturbations of cometary orbits. Since these forces vary with the changing position of the solar system in the Galaxy, they provide a mechanism for the periodic variation in the flux of Oort cloud comets into the inner solar system. The cycle time and degree of modulation depend critically on the mass distribution in the galactic disk. Additional information is contained in the original extended abstract.

Parametric Dielectric Model of Comet Churyumov-Gerasimenko

NASA Astrophysics Data System (ADS)

Heggy, E.; Palmer, E. M.; Kofman, W. W.; Clifford, S. M.; Righter, K.; Herique, A.

2012-12-01

In 2014, the European Space Agency's Rosetta mission is scheduled to rendezvous with Comet 67P/Churyumov-Gerasimenko (Comet 67P). Rosetta's CONSERT experiment aims to explore the cometary nucleus' geophysical properties using radar tomography. The expected scientific return and inversion algorithms are mainly dependent on our understanding of the dielectric properties of the comet nucleus and how they vary with the spatial distribution of geophysical parameters. Using observations of comets 9P/Tempel 1 and 81P/Wild 2 in combination with dielectric laboratory measurements of temperature, porosity, and dust-to-ice mass ratio dependencies for cometary analog material, we have constructed two hypothetical three-dimensional parametric dielectric models of Comet 67P's nucleus to assess different dielectric scenarios of the inner structure. Our models suggest that dust-to-ice mass ratios and porosity variations generate the most significant measurable dielectric contrast inside the comet nucleus, making it possible to explore the structural and compositional hypotheses of cometary nuclei. Surface dielectric variations, resulting from temperature changes induced by solar illumination of the comet's faces, have also been modeled and suggest that the real part of the dielectric constant varies from 1.9 to 3.0, hence changing the surface radar reflectivity. For CONSERT, this variation could be significant at low incidence angles, when the signal propagates through a length of dust mantle comparable to the wavelength. The overall modeled dielectric permittivity spatial and temporal variations are therefore consistent with the expected deep penetration of CONSERT's transmitted wave through the nucleus. It is also clear that changes in the physical properties of the nucleus induce sufficient variation in the dielectric properties of cometary material to allow their inversion from radar tomography.

Correlational selection leads to genetic integration of body size and an attractive plumage trait in dark-eyed juncos.

PubMed

McGlothlin, Joel W; Parker, Patricia G; Nolan, Val; Ketterson, Ellen D

2005-03-01

When a trait's effect on fitness depends on its interaction with other traits, the resultant selection is correlational and may lead to the integration of functionally related traits. In relation to sexual selection, when an ornamental trait interacts with phenotypic quality to determine mating success, correlational sexual selection should generate genetic correlations between the ornament and quality, leading to the evolution of honest signals. Despite its potential importance in the evolution of signal honesty, correlational sexual selection has rarely been measured in natural populations. In the dark-eyed junco (Junco hyemalis), males with experimentally elevated values of a plumage trait (whiteness in the tail or "tail white") are more attractive to females and dominant in aggressive encounters over resources. We used restricted maximum-likelihood analysis of a long-term dataset to measure the heritability of tail white and two components of body size (wing length and tail length), as well as genetic correlations between pairs of these traits. We then used multiple regression to assess directional, quadratic, and correlational selection as they acted on tail white and body size via four components of lifetime fitness (juvenile and adult survival, mating success, and fecundity). We found a positive genetic correlation between tail white and body size (as measured by wing length), which indicates past correlational selection. Correlational selection, which was largely due to sexual selection on males, was also found to be currently acting on the same pair of traits. Larger males with whiter tails sired young with more females, most likely due to a combination of female choice, which favors males with whiter tails, and male-male competition, which favors both tail white and larger body size. To our knowledge, this is the first study to show both genetic correlations between sexually selected traits and currently acting correlational sexual selection, and we suggest that correlational sexual selection frequently may be an important mechanism for maintaining the honesty of sexual signals.

Potential Jupiter-Family comet contamination of the main asteroid belt

NASA Astrophysics Data System (ADS)

Hsieh, Henry H.; Haghighipour, Nader

2016-10-01

We present the results of "snapshot" numerical integrations of test particles representing comet-like and asteroid-like objects in the inner Solar System aimed at investigating the short-term dynamical evolution of objects close to the dynamical boundary between asteroids and comets as defined by the Tisserand parameter with respect to Jupiter, TJ (i.e., TJ = 3). As expected, we find that TJ for individual test particles is not always a reliable indicator of initial orbit types. Furthermore, we find that a few percent of test particles with comet-like starting elements (i.e., similar to those of Jupiter-family comets) reach main-belt-like orbits (at least temporarily) during our 2 Myr integrations, even without the inclusion of non-gravitational forces, apparently via a combination of gravitational interactions with the terrestrial planets and temporary trapping by mean-motion resonances with Jupiter. We estimate that the fraction of real Jupiter-family comets occasionally reaching main-belt-like orbits on Myr timescales could be on the order of ∼ 0.1-1%, although the fraction that remain on such orbits for appreciable lengths of time is certainly far lower. For this reason, the number of JFC-like interlopers in the main-belt population at any given time is likely to be small, but still non-zero, a finding with significant implications for efforts to use apparently icy yet dynamically asteroidal main-belt comets as tracers of the primordial distribution of volatile material in the inner Solar System. The test particles with comet-like starting orbital elements that transition onto main-belt-like orbits in our integrations appear to be largely prevented from reaching low eccentricity, low inclination orbits, suggesting that the real-world population of main-belt objects with both low eccentricities and inclinations may be largely free of this potential occasional Jupiter-family comet contamination. We therefore find that low-eccentricity, low-inclination main-belt comets may provide a more reliable means for tracing the primordial ice content of the main asteroid belt than the main-belt comet population as a whole.

On the Dust Environment of Comet C/2012 S1 (ISON) from 12 AU Pre-perihelion to the End of its Activity around Perihelion

NASA Astrophysics Data System (ADS)

Moreno, F.; Pozuelos, F.; Aceituno, F.; Casanova, V.; Duffard, R.; López-Moreno, J. J.; Molina, A.; Ortiz, J. L.; Santos-Sanz, P.; Sota, A.; Diepvens, A.; Segundo, A. S.; Bell, C.; Labordena, C.; Bryssinck, E.; Cortés, E.; Reina, E.; García, F.; Gómez, F.; Limón, F.; Soldán, F.; Tifner, F.; Muler, G.; Almendros, I.; Aledo, J.; Bel, J.; Carrillo, J.; Castellano, J.; Curto, J.; Gaitan, J.; Salto, J. L.; Lopesino, J.; Lozano, J.; Hernández, J. F.; González, J. J.; Martín, J. L.; Aymamí, J. M.; Bosch, J. M.; Fernández, J. M.; Vidal, J. R.; Montoro, L.; Tremosa, L.; Campas, M.; Canales, O.; Dekelver, P. J.; Benavides, R.; Naves, R.; Castillo, R.; Climent, T.; Cupillari, T.; Yanamandra-Fisher, P.

2014-08-01

A Monte Carlo dust tail model has been applied to extract the dust environment parameters of the comet C/2012 S1 (ISON) from both Earth-based and SOHO LASCO C3 observations, performed from about six astronomical units (AU) inbound, to just after perihelion passage, when only a small portion of the original comet nucleus has survived in the form of a cloud of tiny particles. The early Afρ and image data are consistent with particle ejection from an extended active area located at latitudes 35°N to 90°N (for a prograde rotating nucleus), with the spin axis having a large obliquity (I ~ 70°). This configuration nicely fits the early images and Afρ data until 3.9 AU inbound, when the emission should become isotropic in order to fit the data. The analysis of LASCO images reveals that, assuming an original nucleus of RN = 500 m with ρ = 1000 kg m-3, at least half of its mass was vaporized when the comet was at about 17 R ⊙ inbound. We conclude that at that time the nucleus suffered a cataclysmic fragmentation releasing a huge amount of material of 2.3 ×1011 kg, equivalent to a sphere of 380 m in radius with density 1000 kg m-3. The surviving material after perihelion passage consists of very small dust particles of 0.1-50 μm in radius with a total mass of just 6.7×108 kg.

Genotoxic effects of vinclozolin on the aquatic insect Chironomus riparius (Diptera, Chironomidae).

PubMed

Aquilino, Mónica; Sánchez-Argüello, Paloma; Martínez-Guitarte, José-Luis

2018-01-01

Vinclozolin (Vz) is a pollutant found in aquatic environments whose antiandrogenic effects in reproduction are well known in mammals. Although its reproductive effects have been less studied in invertebrates, other effects, including genotoxicity, have been described. Therefore, in this work, we studied the genotoxic effects of Vz in the freshwater benthic invertebrate Chironomus riparius. DNA damage was evaluated with the comet assay (tail area, olive moment, tail moment and % DNA in tail), and the transcriptional levels of different genes involved in DNA repair (ATM, NLK and XRCC1) and apoptosis (DECAY) were measured by RT-PCR. Fourth instar larvae of C. riparius, were exposed to Vz for 24 h at 20 and 200 μg/L. The Vz exposures affected the DNA integrity in this organism, since a dose-response relationship occurred, with DNA strand breaks significantly increased with increased dose for tail area, olive moment and tail moment parameters. Additionally, the lower concentration of Vz produced a significant induction of the transcripts of three genes under study (ATM, NLK and XRCC1) showing the activation of the cellular repair mechanism. In contrast, the expression of these genes with the highest concentration were downregulated, indicating failure of the cellular repair mechanism, which would explain the higher DNA damage. These data report for the first time the alterations of Vz on gene transcription of an insect and confirm the potential genotoxicity of this compound on freshwater invertebrates. Copyright © 2017 Elsevier Ltd. All rights reserved.

Molecular modeling of proteinlike inclusions in lipid bilayers: lipid-mediated interactions.

PubMed

Kik, Richard A; Leermakers, Frans A M; Kleijn, J Mieke

2010-02-01

We investigated the insertion of transmembrane structures in a lipid bilayer and their interactions using self-consistent field theory. The lipids are coarse-grained on a united-atom level and consist of a phosphatidylcholinelike headgroup and two hydrophobic tails. The inclusions, acting as simple models for proteins that span biological membranes, are rigid rods (radius R ) with a hydrophobic surface and hydrophilic end caps. The insertion free energy Omega of an individual rod is strongly regulated by the affinity between its hydrophobic surface and the lipid tails. This affinity also controls the best match of the hydrophobic length of the rod with that of the bilayer. The line tension tau(=Omega/2piR) is practically independent of R . The perturbations in the bilayer as a function of distance from the inclusion, have the shape of a damped oscillation. The wavelength and decay length are related to the elastic properties of the bilayer and do not depend on R . These results are used to analyze how the lipid matrix affects the interaction between transmembrane objects, for computational reasons considering the limit of R-->infinity . Contributions on different length scales can be distinguished: (i) a long-range elastic interaction, which is an exponentially decaying oscillation; (ii) an exponentially decaying repulsion on an intermediate length scale, resulting from the loss of conformational entropy of the lipid tails; and (iii) a short-range interaction due to the finite compressibility of the lipid tails, which manifests either as a depletion attraction if there is no affinity between the tails and the inclusions' surface or, otherwise, as an oscillatory structural force.

Utilization of multi-body trajectories in the Sun-Earth-Moon system

NASA Technical Reports Server (NTRS)

Farquhar, R. W.

1980-01-01

An overview of three uncommon trajectory concepts for space missions in the Sun-Earth-Moon System is presented. One concept uses a special class of libration-point orbits called 'halo orbits.' It is shown that members of this orbit family are advantageous for monitoring the solar wind input to the Earth's magnetosphere, and could also be used to establish a continuous communications link between the Earth and the far side of the Moon. The second concept employs pretzel-like trajectories to explore the Earth's geomagnetic tail. These trajectories are formed by using the Moon to carry out a prescribed sequence of gravity-assist maneuvers. Finally, there is the 'boomerang' trajectory technique for multiple-encounter missions to comets and asteroids. In this plan, Earth-swingby maneuvers are used to retarget the original spacecraft trajectory. The boomerang method could be used to produce a triple-encounter sequence which includes flybys of comets Halley and Tempel-2 as well as the asteroid Geographos.

Mission design for a ballistic slow flyby Comet Encke 1980

NASA Technical Reports Server (NTRS)

Farquhar, R. W.; Mccarthy, D. K.; Muhonen, D. P.; Yeomans, D. K.

1974-01-01

Preliminary mission analyses for a proposed 1980 slow flyby (7-9 km/s) of comet Encke are presented. Among the topics covered are science objectives, Encke's physical activity and ephemeris accuracy, trajectory and launch-window analysis, terminal guidance, and spacecraft concepts. The nominal mission plan calls for a near-perihelion intercept with two spacecraft launched on a single launch vehicle. Both spacecraft will arrive at the same time, one passing within 500 km from Encke's nucleus on its sunward side, the other cutting through the tail region. By applying a small propulsive correction about three weeks after the encounter, it is possible to retarget both spacecraft for a second Encke intercept in 1984. The potential science return from the ballistic slow flyby is compared with other proposed mission modes for the 1980 Encke flyby mission, including the widely advocated slow flyby using solar-electric propulsion. It is shown that the ballistic slow flyby is superior in every respect.

Once a myth, now an object of study - How the perception of comets has changed over the centuries

NASA Astrophysics Data System (ADS)

2004-02-01

In February 2004, Rosetta will be setting off on its long journey through our solar system to meet up with Comet Churyumov-Gerasimenko. It will take the European Space Agency (ESA) space probe ten years to reach its destination. The comet, which moves in an elliptical orbit around the Sun, will at rendezvous be some 675 million kilometres from the Sun, near the point in its orbit farthest from the Sun. The meeting point was not chosen at random: at this point the comet is still barely active, it is still in fact a frozen lump of ice and interplanetary dust, in all probability the matter from which our solar system emerged four and a half billion years ago. Rosetta’s job is to find out more about these strange bodies that travel through our solar system. As it moves on, the comet will begin to change. As it approaches the Sun, it will - like all comets - become active: in the warmth of the Sun’s rays, the ices evaporate, tearing small dust particles from the surface. This produces the comet head (the coma) and tail. Only these two phenomena are visible from Earth. The comet nucleus itself is far too tiny - Churyumov-Gerasimenko measures about 4 kilometres across - to be viewed from Earth. As Dr Uwe Keller of the Max Planck Institute for Aeronomy in Kaltenburg-Lindau, the scientist responsible for the Osiris camera carried by Rosetta, explains, “Formation of the coma and tail during solar flyby skims several metres of matter off the comet’s surface. In the case of a small comet like Churyumov-Gerasimenko, the shrinkage is a good 1% each time round.” As it flies past the Sun every 6.6 years it can look forward to a short future, especially on a cosmic timescale. Comets - a mystical view Visible cometary phenomena have fascinated human beings from time immemorial - and frightened them too. Even today mystical explanations prevail among some of the Earth’s peoples. The Andaman islanders, a primitive people living in the Gulf of Bengal, see comets as burning torches hurled into the air by forest spirits - the more easily to detect humans foolish enough to stay out at night. For some Australian aborigines, comets are flaming sticks ridden by mighty shamans. Efforts to provide a scientific explanation of the ‘cometa aster’ (‘hairy star’) phenomenon stretch back to ancient times. A widely held view was that comets were in some way connected with processes at work in the atmosphere. In Meteorologica, Aristotle (384-322 BC) described how inflammable gases escape from clefts in rocks, collect in the upper layers of the sub-lunar world (‘world under the Moon’) and ignite. Rapid release of such gases produced a shooting star; when let out slowly, they gave rise to a comet. That was Aristotle’s best shot - and he was well aware of his limited insight into the question. As he himself acknowledged: “As we have no demonstrable basis for assertions about comets, I have to settle for an interpretation that does not conflict with established truths.” Admittedly such truths were thin on the ground at the time. Comets - something of a disaster As the centuries unfolded, what could be called the opposite view - that the comets were responsible for intense heat spells - also gained a considerable audience, though there was just as little truth in it. The natural philosophers went one further. They said comets lead to heat, heat to storms and storms to natural disasters. Pliny the Elder for example (born circa 23 AD) listed twelve cometary phenomena according to their external appearances. And he assigned one natural disaster to each class. The Christian Middle Ages no longer saw cometary phenomena as the blind raging of an even blinder nature, preferring to interpret them as signs from God. Theologians such as Saint Hildegard of Bingen (1098-1179) and Albert Magnus (1200-1280) cited holy scripture. The Book of Jeremiah for example (1:11,12), in which God caused a fearsome “rod of an almond tree” to appear in the sky, a symbol of the prophet’s empowerment. Or again Luke 21:11: “And great earthquakes shall be in divers places, and famines, and pestilences; and fearful sights and great signs shall there be from heaven.” In 1066, Halley’s Comet appeared to many as a harbinger of the Norman conquest of Britain, so vividly portrayed in the Bayeux tapestry, with its scenes from the Battle of Hastings. The decisive step towards overturning the view that comets are atmospheric phenomena was taken in 1577 by Danish astronomer, Tycho Brahe. For two and a half months he observed from his observatory in Uranienburg the progress of a comet across the heavens. Relying on the phenomenon of the daily parallax - an apparent “shuddering” motion of heavenly bodies in fact attributable to the observer’s position on the revolving Earth - he was able to establish that the comet had to be located beyond the lunar orbit. Halley discovers an elliptical orbit The scientific description of comets took another major step forward in 1705 thanks to the work of the British astronomer and physicist, Edmond Halley, a friend and patron of Isaac Newton. Investigating recorded comet measurements, he observed that the orbits of a number of bright comets were very similar: his own calculation of the orbit of a comet observed in 1682 coincided with the data recorded by Johannes Kepler in 1607 and by Apianus in 1531. He concluded that various comet observations were attributable to one and the same comet. Halley was proved right when in December 1758, the comet whose return he had predicted, thenceforth named after him, did indeed make a repeat appearance. This confirmed his theory that apparently parabolic comet orbits were in fact “simply” sections of one enormous elliptical orbit. Since then observations recorded in China in 240 BC have been identified as relating to a sighting of Halley’s comet, the oldest known document dealing with this phenomenon. What was described in the Bible as a sign from God was seen by Fred Hoyle, the British astrophysicist, as a possible explanation for the great hiatal breaks in history. He took the view that such extraordinary developments as the extinction of the mammoth were attributable to strikes by comet fragments. His views incorporated the theory advanced by British astronomers Victor Clube and Bill Napier in 1982 that a giant comet was trapped by our solar system 15000 years ago. With the return of that comet every 1600 years, the accompanying debris - so the argument goes - prompted some of the world’s great turning points. This might also be an explanation for such legends as the Flood. A lump of icy sludgew So what does the actual nucleus of a comet look like? One answer was supplied by the Giotto space probe in a mission masterminded by ESA. The probe was named after the major Italian painter Giotto di Bondone, who, in the early 14th century, portrayed a comet in his fresco in the Scrovegni Chapel in Padua. On 14 March 1986, the probe succeeded in taking 100-metre-resolution pictures of the nucleus of Halley’s Comet from only 600 kilometres away. In the words of Uwe Keller: “The mission forced us to revisit our long-standing image of a comet nucleus as a ‘dirty snowball’. The pictures showed that it was more like a lump of icy sludge. The solid part of the nucleus is much larger than the icy part.” Bur hardly had Giotto trained its electronic eye on the heavenly body than the photo opportunity was already over; a dust particle measuring about a millimetre hit the probe. As the velocity differential between probe and comet was at that point 68.4 km per second, the force of the involuntary encounter was enough to put paid to any further snapshots. All the same, despite the damage to the camera, it proved possible to go on with the mission. Following two periods of “hibernation”, Giotto achieved a successful flyby of the Grigg-Skjellerup comet on 10 July 1992. Rosetta should now bring us entirely new knowledge about comet nuclei. It will orbit the comet and deposit a small lander probe on its surface. So for the first time in history a comet travelling sunwards will be investigated from close quarters. For further information on Rosetta and ESA projects, please consult our portal at : http://www.esa.int/science or http:// www.esa.int/rosetta

Simulation study of natural UV-B radiation on Catla catla and its impact on physiology, oxidative stress, Hsp 70 and DNA fragmentation.

PubMed

Singh, Moirangthem Kameshwor; Sharma, Jai Gopal; Chakrabarti, Rina

2015-08-01

UV-B radiation is a potential stressor to the aquacultural species. Catla catla, catla larvae (1.08±0.065g) were exposed to different doses of UV-B radiation, 0 (control), 504, 1008, 1512 and 2016mJ/cm(2) at a mean radiant energy of 80μW/cm(2) for 21days. The dose of UV-B radiation was selected on the basis of the field study conducted in Lake Naini, Delhi, India (Latitude: 28°41'26″N and Longitude: 77°12″37″E). Significantly (P<0.05) lower survival, average weight and specific growth rate were found in UV-B irradiated larvae compared to the control one. Food conversion ratio was 1.5-4-fold higher in UV-B treated larvae compared to the control one. The carbonyl protein (CP), thiobarbituric acid reactive substances (TBARS), superoxide dismutase (SOD) levels were significantly (P <0.05) higher in UV-B irradiated larvae compared to the control group. Among the treated larvae, CP and SOD were significantly (P <0.05) higher in larvae exposed at 1512mJ/cm(2) UV-B. A correlation was found between the CP and SOD (R(2)=0.834). Highest TBARS level was found in 2016mJ/cm(2) UV-B exposed catla. Nitric oxide synthase level was significantly (P <0.05) lower in UV-B exposed larvae compared to the control one. A 3-fold increased Hsp 70 level was recorded in UV-B irradiated catla compared to the control larvae. Comet assay analysis indicated that UV-B irradiation enhanced DNA fragmentation. Tail extent moment and the olive tail moment were significantly (P <0.05) higher in 2016mJ/cm(2) UV-B exposed catla compared to others. The tail length was significantly (P <0.05) higher in 1512 and 2016mJ/cm(2) UV-B exposed larvae compared to the other doses. The present study suggests that the catla is a useful species for the biomonitoring of stress in the aquatic environment. Copyright © 2015 Elsevier B.V. All rights reserved.

The C Terminus of the Histone Chaperone Asf1 Cross-Links to Histone H3 in Yeast and Promotes Interaction with Histones H3 and H4

PubMed Central

Dennehey, Briana K.; Noone, Seth; Liu, Wallace H.; Smith, Luke

2013-01-01

The central histone H3/H4 chaperone Asf1 comprises a highly conserved globular core and a divergent C-terminal tail. While the function and structure of the Asf1 core are well known, the function of the tail is less well understood. Here, we have explored the role of the yeast (yAsf1) and human (hAsf1a and hAsf1b) Asf1 tails in Saccharomyces cerevisiae. We show, using a photoreactive, unnatural amino acid, that Asf1 tail residue 210 cross-links to histone H3 in vivo and, further, that loss of C-terminal tail residues 211 to 279 weakens yAsf1-histone binding affinity in vitro nearly 200-fold. Via several yAsf1 C-terminal truncations and yeast-human chimeric proteins, we found that truncations at residue 210 increase transcriptional silencing and that the hAsf1a tail partially substitutes for full-length yAsf1 with respect to silencing but that full-length hAsf1b is a better overall substitute for full-length yAsf1. In addition, we show that the C-terminal tail of Asf1 is phosphorylated at T270 in yeast. Loss of this phosphorylation site does not prevent coimmunoprecipitation of yAsf1 and Rad53 from yeast extracts, whereas amino acid residue substitutions at the Asf1-histone H3/H4 interface do. Finally, we show that residue substitutions in yAsf1 near the CAF-1/HIRA interface also influence yAsf1's function in silencing. PMID:23184661

Rosetta - a new target to solve planetary mysteries

NASA Astrophysics Data System (ADS)

2004-01-01

This delay meant that the original mission's target, Comet Wirtanen, could no longer be reached. Instead, a new target has been selected, Comet 67P/Churyumov-Gerasimenko, which Rosetta will encounter in 2014 after a ‘billiard ball’ journey through the Solar System lasting more than ten years. Rosetta’s name comes from the famous ‘Rosetta Stone’, from which Egyptian hieroglyphics were deciphered almost 200 years ago. In a similar way, scientists hope that the Rosetta spacecraft will unlock the mysteries of the Solar System. Comets are very interesting objects for scientists, since their composition reflects how the Solar System was when it was very young and still 'unfinished', more than 4600 million years ago. Comets have not changed much since then. In orbiting Comet Churyumov-Gerasimenko and landing on it, Rosetta will collect information essential to an understanding of the origin and evolution of our Solar System. It will also help discover whether comets contributed to the beginnings of life on Earth. In fact comets are carriers of complex organic molecules that, delivered to Earth through impacts, perhaps played a role in the origin of living forms. Furthermore, ‘volatile’ light elements carried by comets might also have played an important role in forming the Earth’s oceans and atmosphere. “Rosetta is one of the most challenging missions undertaken so far,” says Professor David Southwood, ESA Director of Science. “No one has ever attempted such a mission, unique for its scientific implications as well as for its complex and spectacular interplanetary space manoeuvres.” Before reaching its target in 2014, Rosetta will circle the Sun four times on wide loops in the inner Solar System. During its long trek, the spacecraft will have to endure some extreme thermal conditions. Once it is close to Comet Churyumov-Gerasimenko, scientists will take it through a delicate braking manoeuvre; the spacecraft will then closely orbit the comet, and gently drop a lander on it. It will be landing on a small, fast-moving ‘cosmic bullet’ about whose 'geography' very little is known yet. An amazing 10-year interplanetary trek Rosetta is a three-tonne box-type spacecraft about three metres high, with two 14-metre solar panels. It consists of an orbiter and a lander. The lander is approximately one metre across and 80 centimetres high. It will be attached to the side of the orbiter during the journey to Comet Churyumov-Gerasimenko. Rosetta carries 21 experiments in total, 10 of them on the lander. They will be kept in hibernation during most of its 10-year trek towards the comet. Why does Rosetta's cruise need to take so long? To reach Comet Churyumov-Gerasimenko, the spacecraft needs to go out into deep space as far out from the Sun as Jupiter. No launcher could possibly get Rosetta there directly. ESA's spacecraft will gather speed from gravitational ‘kicks’ provided by four planetary fly-bys: one of Mars in 2007 and three of Earth in 2005, 2007 and 2009. During the trip, Rosetta will also twice pass through the asteroid belt, where a fly-by with one or more of these primitive objects is possible. A number of candidate targets have already been identified, but the final selection will be made after launch, once the amount of surplus fuel has been verified by mission engineers. During these encounters, scientists plan to switch on Rosetta's instruments for scientific studies of these largely unexplored Solar System bodies. Long trips in deep space include many hazards, such as extreme changes in temperature. Rosetta will leave the benign environment of near-Earth space to the dark, frigid regions beyond the asteroid belt. To manage these thermal loads, experts have done very tough pre-launch tests to study Rosetta's endurance. For example, they have heated its external surfaces to more than 150°C, then cooled it to -150°C in the next test. The spacecraft will be fully reactivated prior to the comet rendezvous manoeuvre in 2014. Then, Rosetta will orbit the comet - an object only about 4 kilometres in diameter - while it cruises through the inner Solar System at 135 000 kilometres per hour. At the time of the rendezvous - around 675 million kilometres from the Sun - Comet Churyumov-Gerasimenko will hardly show any surface activity. This means that the characteristic ‘coma’ (the comet’s ‘atmosphere’) and the tail will not be formed yet, because of the distance from the Sun. The comet's tail is in fact made of dust grains and frozen gases from the comet's surface that vaporise because of the Sun's heat. Over a period of six months, Rosetta will extensively map the comet's surface, prior to selecting a landing site. In November 2014, the lander will be ejected from the spacecraft from a height which could be as low as one kilometre. Touchdown will be at walking speed, about one metre per second. Immediately after touchdown, the lander will fire a harpoon into the ground to avoid bouncing off the surface back into space, since the comet’s extremely weak gravity alone would not hold onto the lander. Operations and scientific observations on the surface will last at least a week, but may continue for many months. Besides taking close-up pictures, the lander will drill into the dark organic crust and sample the primordial ices and gases. During and after the lander operations, Rosetta will continue orbiting and studying the comet: it will be the first spacecraft to witness at close quarters the changes taking place in a comet when the comet approaches the Sun and grows its coma and tail and then travels away from it. The trip will end in December 2015, after 12 years of adventure, when the comet has made its closest approach to the Sun and is on its way towards the outer Solar System. Studying a comet on the spot Rosetta's goal is to examine the comet in great detail. The instruments on the orbiter include several cameras and spectrometers that work at different wavelengths: infrared, ultraviolet, visible and microwave. In addition, there are various other instruments to make in situ analysis. Together, they will provide, amongst other things, very high-resolution images and information about the shape, density, temperature and chemical composition of the comet. Rosetta’s instruments will analyse the gases and dust grains in the coma that forms when the comet becomes active, as well as the interaction with the solar wind. The ten experiments on the lander will make an on-the-spot analysis of the composition and structure of the comet’s surface and subsurface material. A drilling system will take samples down to 30 centimetres below the surface and feed these to the ‘composition analysers’. Other instruments will measure properties such as near-surface strength, density, texture, porosity, ice phases and thermal properties. Microscopic studies of individual grains will tell us about the texture. Ground operations All scientific data including those relayed from the lander will be stored on the orbiter for downlink to Earth at the next ground station contact. ESA has installed a new deep-space antenna at New Norcia, near Perth in Western Australia, as the main communications link between the spacecraft and ESOC Mission Control in Darmstadt, Germany. This 35-metre diameter parabolic antenna allows the radio signal to reach distances of more than a million kilometres from Earth. The radio signals, travelling at the speed of light, will take up to 50 minutes to cover the distance between the spacecraft and Earth. Rosetta's Science Operations Centre, which will be responsible for collecting and distributing the scientific data, will share locations at ESOC and ESTEC in Noordwijk, The Netherlands. The Lander Control Centre is located at DLR in Cologne, Germany, and the Lander Science Centre at CNES in Toulouse, France. Building Rosetta Rosetta was selected as a mission in 1993. The spacecraft has been built by Astrium Germany as prime contractor. Major subcontractors are Astrium UK (spacecraft platform), Astrium France (spacecraft avionics), and Alenia Spazio (assembly, integration, and verification). Rosetta’s industrial team involves more than 50 contractors from 14 European countries, Canada and the United States. Scientific consortia from institutes across Europe and the United States have provided the instruments on the orbiter. A European consortium under the leadership of the German Aerospace Research Institute (DLR) has provided the lander. Rosetta has cost ESA EUR 770 million at 2000 economic conditions. This includes the launch and the entire period of development and mission operations from 1996 to 2015. The lander and the experiments, the so-called 'payload', are not included since they are funded by the member states through scientific institutes.

Varieties of charge distributions in coat proteins of ssRNA+  viruses

NASA Astrophysics Data System (ADS)

Lošdorfer Božič, Anže; Podgornik, Rudolf

2018-01-01

A major part of the interactions involved in the assembly and stability of icosahedral, positive-sense single-stranded RNA (ssRNA+) viruses is electrostatic in nature, as can be inferred from the strong pH- and salt-dependence of their assembly phase diagrams. Electrostatic interactions do not act only between the capsid coat proteins (CPs), but just as often provide a significant contribution to the interactions of the CPs with the genomic RNA, mediated to a large extent by positively charged, flexible N-terminal tails of the CPs. In this work, we provide two clear and complementary definitions of an N-terminal tail of a protein, and use them to extract the tail sequences of a large number of CPs of ssRNA+  viruses. We examine the pH-dependent interplay of charge on both tails and CPs alike, and show that—in contrast to the charge on the CPs—the net positive charge on the N-tails persists even to very basic pH values. In addition, we note a limit to the length of the wild-type genomes of those viruses which utilize positively charged tails, when compared to viruses without charged tails and similar capsid size. At the same time, we observe no clear connection between the charge on the N-tails and the genome lengths of the viruses included in our study.

209P/LINEAR: a peacefully demising comet?

NASA Astrophysics Data System (ADS)

Ye, Quanzhi; Brown, Peter; Wiegert, Paul; Hui, Man-To; Campbell-Brown, Margaret

2014-11-01

Comet 209P/LINEAR made one of the closest cometary approaches to the Earth in May 2014. It is also responsible for the Camelopardalid meteor outburst which occurred on May 24, 2014. Here we report the optical/infrared observations of 209P/LINEAR and radar observations of the meteor outburst. Continuous monitoring of 209P/LINEAR with the XOSS facilities from Feb to May 2014 reveals the lowest perihelion dust production level of any comet on record, with Afρ << 1 cm. Spectroscopic observation with Gemini GMOS-N at T0-27 days also reveals very low gas emission rates of 8*10**22 mol/s for CN, <3*10**22 mol/s for C2, and <2*10**23 mol/s for C3. Infrared imaging with the Gemini Flamingos-2 revealed an anti-solar fan-like tail that cannot be explained by viewing geometry. At the Earth, the Canadian Meteor Orbit Radar (CMOR) observed 105 multi-station Camelopardalid meteor echoes during 0 - 24 h UT May 24, showing a mass distribution index of s=1.86+/-0.02, appropriate to meteors of magnitude ~6-7. We also identified 63 overdense meteor trails in CMOR data which showed a mass distribution index of s=2.12+/-0.02, appropriate to meteors of magnitude ~>4. The large difference in the mass index in different magnitude ranges indicates that the Camelopardalid meteoroids do not follow power law distribution at mm-sizes. Considering that the outburst was caused by direct encounters with multiple dust trails released in the 1800s and 1900s, the low visual/radar flux of the outburst 0.02 hr**-1 km**-2 from IMO visual data; ~0.06 hr**-1 km**-2 from CMOR data) may indicate that P/LINEAR has been largely inactive in the past few centuries, supporting the idea that the comet is currently transitioning into a dormant/extinct comet.

Optical and Near-infrared Polarimetry of Non-periodic Comet C/2013 US10 (Catalina)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kwon, Yuna Grace; Ishiguro, Masateru; Lee, Myung Gyoon

We present an optical and near-infrared (hereafter NIR) polarimetric study of a comet C/2013 US10 (Catalina) observed on UT 2015 December 17–18 at phase angles of α  = 52.°1–53.°1. Additionally, we obtained an optical spectrum and multi-band images to examine the influence of gas emission. We find that the observed optical signals are significantly influenced by gas emission; that is, the gas-to-total intensity ratio varies from 5 to 30% in the R {sub C} and 3%–18% in the I {sub C} bands, depending on the position in the coma. We derive the “gas-free dust polarization degrees” of 13.8% ± 1.0% in the Rmore » {sub C} and 12.5% ± 1.1% in the I {sub C} bands and a gray polarimetric color, i.e., −8.7% ± 9.9% μ m{sup −1} in optical and 1.6% ± 0.9% μ m{sup −1} in NIR. The increments of polarization obtained from the gas correction show that the polarimetric properties of the dust in this low-polarization comet are not different from those in high-polarization comets. In this process, the cometocentric distance dependence of polarization has disappeared. We also find that the R {sub C}-band polarization degree of the southeast dust tail, which consists of large dust particles (100 μ m–1 mm), is similar to that in the outer coma where small and large ones are mixed. Our study confirms that the dichotomy of cometary polarization does not result from the difference of dust properties, but from depolarizing gas contamination. This conclusion can provide a strong support for similarity in origin of comets.« less

The fragmentation of dust in the innermost comae of comets: Possible evidence from ground-based images

NASA Technical Reports Server (NTRS)

Combi, Michael R.

1994-01-01

Dust particles when released from the nucleus of a comet are entrained in the expanding gas flow created by the vaporization of ices (mainly water ice). Traditional approaches to dusty-gas dynamics in the inner comae of comets consider there to be an initial distribution of dust particle sizes which do not fragment or evaporate. The standard Finson-Probstein model (and subsequent variations) yields a one-to-one-to-one correspondence between the size of a dust particle, its terminal velocity owing to gas drag, and its radiation pressure acceleration which creates the notable cometary dust tail. The comparison of a newly developed dust coma model shows that the typical elongated shapes of isophotes in the dust comae of comets on the scale of greater than 10(exp 4) km from the nucleus requires that the one-to-one-to-one relationship between particle size, terminal velocity and radiation pressure acceleration cannot in general be correct. There must be a broad range of particles including those having a small velocity but large radiation pressure acceleration in order to explain the elongated shape. A straightforward way to create such a distribution is if particle fragmentation, or some combination of fragmentation with vaporization, routinely occurs within and/or just outside of the dusty-gas dynamic acceleration region (i.e., up to several hundred km). In this way initially large particles, which are accelerated to fairly slow velocities by gas-drag, fragment to form small particles which still move slowly but are subject to a relatively large radiation pressure acceleration. Fragmentation has already been suggested as one possible interpretation for the flattened gradient in the spatial profiles of dust extracted from Giotto images of Comet Halley. Grain vaporization has been suggested as a possible spatially extended source of coma gases. The general elongated isophote shapes seen in ground-based images for many years represents another possible signature of fragmentation.

CHARACTERIZING THE DUST COMA OF COMET C/2012 S1 (ISON) AT 4.15 AU FROM THE SUN

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Jian-Yang; Kelley, Michael S. P.; Farnham, Tony L.

2013-12-10

We report results from broadband visible images of comet C/2012 S1 (ISON) obtained with the Hubble Space Telescope Wide Field Camera 3 on 2013 April 10. C/ISON's coma brightness follows a 1/ρ (where ρ is the projected distance from the nucleus) profile out to 5000 km, consistent with a constant speed dust outflow model. The turnaround distance in the sunward direction suggests that the dust coma is composed of sub-micron-sized particles emitted at speeds of tens of m s{sup –1}. A(θ)fρ, which is commonly used to characterize the dust production rate, was 1340 and 1240 cm in the F606W and F438W filters, respectively,more » in apertures <1.''6 in radius. The dust colors are slightly redder than solar, with a slope of 5.0% ± 0.2% per 100 nm, increasing to >10% per 100 nm 10,000 km down the tail. The colors are similar to those of comet C/1995 O1 (Hale-Bopp) and other long-period comets, but somewhat bluer than typical values for short-period comets. The spatial color variations are also reminiscent of C/Hale-Bopp. A sunward jet is visible in enhanced images, curving to the north and then tailward in the outer coma. The 1.''6 long jet is centered at a position angle of 291°, with an opening angle of ∼45°. The jet morphology remains unchanged over 19 hr of our observations, suggesting that it is near the rotational pole of the nucleus, and implying that the pole points to within 30° of (R.A., decl.) = (330°, 0°). This pole orientation indicates a high obliquity of 50°-80°.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharma, Manisha; Jamieson, Cara; Lui, Christina

β-catenin is a key mediator of Wnt signaling and its deregulated nuclear accumulation can drive cancer progression. While the central armadillo (Arm) repeats of β-catenin stimulate nuclear entry, the N- and C-terminal “tail” sequences are thought to regulate turnover and transactivation. We show here that the N- and C-tails are also potent transport sequences. The unstructured tails of β-catenin, when individually fused to a GFP-reporter, could enter and exit the nucleus rapidly in live cells. Proximity ligation assays and pull-down assays identified a weak interaction between the tail sequences and the FG-repeats of nucleoporins, consistent with a possible direct translocationmore » of β-catenin through the nuclear pore complex. Extensive alanine mutagenesis of the tail sequences revealed that nuclear translocation of β-catenin was dependent on specific uniformly distributed patches of hydrophobic residues, whereas the mutagenesis of acidic amino acids had no effect. Moreover, the mutation of hydrophobic patches within the N-tail and C-tail of full length β-catenin reduced nuclear transport rate and diminished its ability to activate transcription. We propose that the tail sequences can contribute to β-catenin transport and suggest a possible similar role for hydrophobic unstructured regions in other proteins. - Highlights: • We show that the N- and C-tails of beta-catenin possess nuclear transport activity. • Nuclear transport of the N- or C-tails requires specific hydrophobic amino acids. • Mutagenesis of the N-terminus diminished nuclear entry of full-length beta-catenin. • We propose the N-tail contributes to beta-catenin nuclear entry and transactivation.« less

Estimated areal extent of colonies of black-tailed prairie dogs in the northern Great Plains

USGS Publications Warehouse

Sidle, John G.; Johnson, Douglas H.; Euliss, Betty R.

2001-01-01

During 1997–1998, we undertook an aerial survey, with an aerial line-intercept technique, to estimate the extent of colonies of black-tailed prairie dogs (Cynomys ludovicianus) in the northern Great Plains states of Nebraska, North Dakota, South Dakota, and Wyoming. We stratified the survey based on knowledge of colony locations, computed 2 types of estimates for each stratum, and combined ratio estimates for high-density strata with average density estimates for low-density strata. Estimates of colony areas for black-tailed prairie dogs were derived from the average percentages of lines intercepting prairie dog colonies and ratio estimators. We selected the best estimator based on the correlation between length of transect line and length of intercepted colonies. Active colonies of black-tailed prairie dogs occupied 2,377.8 km2 ± 186.4 SE, whereas inactive colonies occupied 560.4 ± 89.2 km2. These data represent the 1st quantitative assessment of black-tailed prairie dog colonies in the northern Great Plains. The survey dispels popular notions that millions of hectares of colonies of black-tailed prairie dogs exist in the northern Great Plains and can form the basis for future survey efforts.

The “Main-Belt Comets” are not comets, nor active asteroids; they are temporary shaken asteroids

NASA Astrophysics Data System (ADS)

Tancredi, Gonzalo

2015-08-01

Several objects in asteroidal orbits have presented comaes and tails similar to the ones presented by comets for short period of times. There are at present 16 objects in this group. Several hypotheses have been proposed to explain the activity of this object [Jewitt 2012]. Among them, the most accepted scenario for many objects is the ice sublimation and the ejection of dust, in a similar way as the cometary activity. Therefore several authors have coined these objects “Main Belt Comets” [Hsieh & Jewitt 2006]. Nevertheless, in some cases, some authors have concluded that the ejection of dust must be due to an impact.We propose an alternative model for the formation of the dusty comaes and tails.The impact of a small body against a larger one initially produces a crater and the ejection of dust at high velocity (>100 m/s). The dust is rapidly dispersed and it should be only observable just after the impact. In addition the impact generates a shock wave, which propagates to the body interior. The asteroid is globally shaken. Material is ejected at low velocities from the entire surface, similar to the low escape velocities at the surface. The particles move away from the asteroid due to the solar radiation pressure, forming the thin tails aligned with the orbital plane. These tails could persist for various months, as they have been seen in these objects.In addition, chunks of rock could be ejected in suborbital flights lasting for days; which, at return they would induce a new low-velocity ejection of particles. This process can explain some of the long-lasting events.The recurrence of the activity for some objects could be explained due to the collision with a dense meteor shower present in the main-belt.The so-called “Main Belt Comets” could be explained with a hypothesis that does not require the presence of ice on the surface of these objects. We also do not favor the term “Activated asteroids”, because it implies some kind of endogenous process. The objects are plain asteroids that suffered a recent collision, and the entire body is shaken, ejecting dust from the surface at low velocities.

Insecticidal and genotoxic activity of Psoralea corylifolia Linn. (Fabaceae) against Culex quinquefasciatus Say, 1823

PubMed Central

2013-01-01

Background Indiscriminate use of synthetic insecticides to eradicate mosquitoes has caused physiological resistance. Plants provide a reservoir of biochemical compounds; among these compounds some have inhibitory effect on mosquitoes. In the present study the larvicidal, adulticidal and genotoxic activity of essential oil of Psoralea corylifolia Linn. against Culex quinquefasciatus Say was explored. Methods Essential oil was isolated from the seeds of P. corylifolia Linn. Larvicidal and adulticidal bioassay of Cx. quinquefasciatus was carried out by WHO method. Genotoxic activity of samples was determined by comet assay. Identification of different compounds was carried out by gas chromatography- mass spectrometry analysis. Results LC50 and LC90 values of essential oil were 63.38±6.30 and 99.02±16.63 ppm, respectively against Cx. quinquefasciatus larvae. The LD50 and LD90 values were 0.057±0.007 and 0.109±0.014 mg/cm2 respectively against adult Cx. quinquefasciatus,. Genotoxicity of adults was determined at 0.034 and 0.069 mg/cm2. The mean comet tail length was 6.2548±0.754 μm and 8.47±0.931 μm and the respective DNA damage was significant i.e. 6.713% and 8.864% in comparison to controls. GCMS analysis of essential oil revealed 20 compounds. The major eight compounds were caryophyllene oxide (40.79%), phenol,4-(3,7-dimethyl-3-ethenylocta-1,6-dienyl) (20.78%), caryophyllene (17.84%), α-humulene (2.15%), (+)- aromadendrene (1.57%), naphthalene, 1,2,3,4-tetra hydro-1,6-dimethyle-4-(1-methyl)-, (1S-cis) (1.53%), trans- caryophyllene (0.75%), and methyl hexadecanoate (0.67%). Conclusion Essential oil obtained from the seeds of P. corylifolia showed potent toxicity against larvae and adult Cx. quinquefasciatus. The present work revealed that the essential oil of P. corylifolia could be used as environmentally sound larvicidal and adulticidal agent for mosquito control. PMID:23379981

Monitoring of the impact of Prestige oil spill on Mytilus galloprovincialis from Galician coast.

PubMed

Laffon, Blanca; Rábade, Tamara; Pásaro, Eduardo; Méndez, Josefina

2006-04-01

In November 2002, the Prestige oil tanker was wrecked in front of Galician coast (NW of Spain), spilling near 63,000 tons of heavy oil until February 2003. Contamination produced was very extensive (70% of Galician beaches were reached by the oil) but heterogeneous, alternating intensely affected zones with neighbour locations where the repercussion was minimal. The objective of this study was to monitor sea environment contamination caused by Prestige oil spill during an 11-month period (August 2003-June 2004, nine samplings) in two locations of Galician coast with different geographical properties (Lira and Ancoradoiro beaches), by means of chemical determination of total polycyclic aromatic hydrocarbons (TPAH) in seawater, and using as exposure biomarker TPAH content in mussel (Mytilus galloprovincialis) tissues, and as effect biomarker DNA damage in mussel gills, evaluated by the comet assay. In addition, recovery ability of the mussels was determined after a 7-day stay in the laboratory. TPAH contents in seawater were very high in the earliest samplings, but then they maintained below 200 ng L(-)(1), similar to reference seawater. However, TPAH levels in mussel tissues were more variable: they increased again from January 2004, probably due to the adverse meteorological conditions that turned over the sea bottom and dispersed the oil accumulated in sediments. In most samplings, these levels decreased during the recovery stage. DNA damage in oil-exposed mussels was significantly higher than in reference mussels, both before and after the recovery phase, but they did not differ to one another. Comet tail length was slightly reduced during the recovery stage, indicative of a certain DNA repair in exposed mussels. This study showed up the importance of monitoring sea contamination events during an extended time, not only in evaluating the presence of the contaminants in the environment but also in determining their bioaccumulation and their effect on the exposed organisms.

Use of photogrammetry as a means to assess hybrids of rhesus (Macaca mulatta) and long-tailed (M. fascicularis) macaques.

PubMed

Jadejaroen, Janya; Hamada, Yuzuru; Kawamoto, Yoshi; Malaivijitnond, Suchinda

2015-01-01

Rhesus (Macaca mulatta) and long-tailed (M. fascicularis) macaques are the most commonly used non-human primate models for biomedical research, but it is difficult to identify these two species in the hybrid zone (15-20°N). In this work, we used morphological values obtained via photogrammetry to assess hybrids of rhesus and long-tailed macaques at Khao Khieow Open Zoo (KKZ; 13°21'N, 101°06'E), eastern Thailand. Long-tailed and rhesus macaques have species-specific tail lengths and contrasts of their yellowish pelages. The accuracy and precision of the relative tail length (%RTL) and the contrast of the yellow hue (Cb*) of the pelage, as obtained from photographs, were compared with the corresponding direct measurements (morphometrics). The photogrammetric and morphometric measurements of %RTL and Cb* were highly significantly correlated (r = 0.989 and 0.980, p < 0.001), and there were no significant differences between the two datasets (t test, p = 0.13 and 0.41; n = 42 and 17 for %RTL and Cb*, respectively). The reproducibilities of the %RTL and Cb* measurements (calculated in the photogrammetric case by taking photographs of the same macaques in two different environments) were significantly correlated between the datasets (r = 0.983 and 0.914, p < 0.001 and 0.005), and there were no significant differences between the datasets (t test, p = 0.539 and 0.344; n = 30 each for %RTL and Cb*, respectively). The %RTL and Cb* data were combined with data on the crown and cheek hair patterns and sex skin reddening of the macaques, and this combined data set was then analyzed by multiple correspondence analysis and agglomerative hierarchical cluster analysis, leading to the categorization of the rhesus macaques, long-tailed macaques, and hybrids at KKZ into five groups. Thus, photogrammetry can be utilized to identify macaque species or hybrids when species identification relies mainly on tail length and pelage color.

Combined effects of land reclamation, channel dredging upon the bioavailable concentration of polycyclic aromatic hydrocarbons (PAHs) in Victoria Harbour sediment, Hong Kong.

PubMed

Chan, J T K; Leung, H M; Yue, P Y K; Au, C K; Wong, Y K; Cheung, K C; Li, W C; Yung, K K L

2017-01-15

The up-to-date concentration of polycyclic aromatic hydrocarbons (PAHs) in sediment materials of Victoria Harbour was investigated so as to evaluate the pollution potential associated with the reclamation projects in Hong Kong. A total of 100 sediment samples were collected at 20 locations. Except the control point in reservoir, the PAHs concentrations were detectable levels all sites (131-628.3ng/g, dw) and such values were higher than Dutch Target and Intervention Values (the New Dutch standard in 2016). The PAHs concentration indicating that construction waste and wastewater discharges were the main pollutant sources. Results of correlation in single cell gel electrophoresis assay (comet assay) studies also revealed that the PAHs concentration was highly correlated (<0.01) with DNA migration (i.e. the length of tail moment of fish cells) in 5mg/ml of PAHs. The above observation indicates that the PAHs present in the sediment may substantially effect the marine ecosystem. Although the dredged sediment can be a useful sea-filling material for land reclamation; however, the continuing leaching of PAHs and its impact on the aquatic environment need to be studied further. Copyright © 2016 Elsevier Ltd. All rights reserved.

Enhanced bioremoval of lead by earthworm-Lumbricus terrestris co-cultivated with bacteria-Klebsiella variicola.

PubMed

Das, Anamika; Osborne, Jabez W

2017-10-01

Lead is a toxic heavy metal having devastating effects on the environment. The current study was focussed on bioremoval of lead using earthworm and lead resistant bacteria. Earthworms were subjected to various concentrations of lead in the soil bioaugmented with lead resistant bacteria (VITMVCJ1) to enhance the uptake of lead from the contaminated soil. Significant increase was observed in the length and body weight of the earthworms supplemented with lead resistant bacteria. Similarly, there was a substantial increase in the locomotion rate of the earthworms treated with lead resistant bacteria in comparison with the control. The gut micro flora of bacterial treated earthworms had increased number of bacterial cells than the untreated earthworms. The histopathological studies revealed the toxic effects of lead on the gut of earthworms indicating severe damage in lead resistant bacteria untreated worms, whereas the cells were intact in lead resistant bacteria treated worms. COMET assay showed increased DNA damage with higher tail DNA percent in the untreated earthworms. Further, the colonisation of the bacteria supplemented, onto the gut region of earthworms was observed by scanning electron microscopy. Atomic absorption spectrophotometry indicated a fair 50% uptake of lead within the biomass of earthworm treated with lead resistant bacteria. Copyright © 2017 Elsevier B.V. All rights reserved.

Use of Arctium lappa Extract Against Acetaminophen-Induced Hepatotoxicity in Rats

PubMed Central

El-Kott, Attalla Farag; Bin-Meferij, Mashael Mohammed

2015-01-01

Background Severe destructive hepatic injuries can be induced by acetaminophen overdose and may lead to acute hepatic failure. Objective To investigate the ameliorative effects of Arctium lappa root extract on acetaminophen-induced hepatotoxicity. Methods Rats were divided into 4 groups: normal control group, Arctium lappa extract group, acetaminophen-injected group, and acetaminophen treated with Arctium lappa extract group. Results The treatment with Arctium lappa extract reduced serum alanine transaminase, aspartate aminotransferase, and alkaline phosphatase in the acetaminophen group when compared with the control group. DNA fragments in the acetaminophen-injected group were also significantly increased (P < 0.05). The comet assay revealed increased detaching tail length and DNA concentration during the hepatic toxicity in the acetaminophen group. The malondialdehyde content was inhibited by Arctium lappa treatment (12.97±0.89 nmol/mg) when compared with the acetaminophen-treated-only group (12.97±0.89 nmol/mg). Histopathologic examination revealed that acetaminophen administration produced hepatic cell necrosis, infiltrate of lymphocytes, and vacuolation that were associated with the acetaminophen-treated animal group, but the degree of acetaminophen-induced hepatotoxicity was mediated by treatment with Arctium lappa extract. Conclusions Arctium lappa can prevent most of the hepatic tissue damage caused by acetaminophen overdose in rats. PMID:26543508

Comets

NASA Astrophysics Data System (ADS)

Brownlee, D. E.

2003-12-01

Comets are surviving members of a formerly vast distribution of solid bodies that formed in the cold regions of the solar nebula. Cometary bodies escaped incorporation into planets and ejection from the solar system and they have been stored in two distant reservoirs, the Oort cloud and the Kuiper Belt, for most of the age of the solar system. Observed comets appear to have formed between 5 AU and 55 AU. From a cosmochemical viewpoint, comets are particularly interesting bodies because they are preserved samples of the solar nebula's cold ice-bearing regions that occupied 99% of the areal extent of the solar nebula disk. All comets formed beyond the "snow line" of the nebula, where the conditions were cold enough for water ice to condense, but they formed from environments that significantly differed in temperature. Some formed in the comparatively "warm" regions near Jupiter where the nebular temperature may have been greater than 120 K and others clearly formed beyond Neptune where temperatures may have been less than 30 K (Bell et al., 1997). Although comets are the best-preserved materials from the early solar system, they should be a mix of nebular and presolar materials that accreted over a vast range of distances from the Sun in environments that differed in temperature, pressure, and accretional conditions such as impact speed.Comets, by conventional definition, are unstable near the Sun; they contain highly volatile ices that vigorously sublime within 2-3 AU of the Sun. When heated, they release gas and solids due to "cometary activity," a series of processes usually detected from afar by the presence of a coma of gas and dust surrounding the cometary nucleus and or elongated tails composed of dust and gas. Active comets clearly have not been severely modified by the moderate to extreme heating that has affected all other solar system materials, including planets, moons, and even the asteroids that produced the most primitive meteorites. Comets have been widely described as the most primitive solar system materials, preserved at cryogenic temperature and low pressure since the formation of the Sun. This is likely to be true, in general, but there is a growing body of recent evidence suggesting that comets are both more physically complex and have had more complex histories than formerly believed. They formed over an order of magnitude range of distances from the Sun; some are fragments of relatively large bodies and collisional effects must have processed at least some comets, as they have processed asteroids (McSween and Weissman, 1989).Comet-like materials are presumed to be the building blocks of Uranus and Neptune (the ice giants); they may have played a role in the formation of Jupiter and Saturn (the gas giants) and they also played some role in transporting outer solar system volatile materials to inner planets (Delsemme, 2000). The inner solar system flux of comets may have been much higher in the past and comets may have played a role in producing the late heavy bombardment on terrestrial planets ( Levison et al., 2001). Comets also exist outside the solar system and there is good evidence that they orbit a major fraction of Sun-like stars. Circumstellar dust, which appears to have been generated by comets, is detected as thermal infrared emission and sometimes as scattered starlight ( Backman et al., 1997; Weissman, 1984; Jewitt and Luu, 1995). It is particularly interesting that the amount of dust around stars declines with stellar age and is highest around stars younger than a few hundred million years. The common presence of what appears to be comet-generated dust around other stars suggests that comet formation is a normal and common consequence of star formation ( Figure 1). (6K)Figure 1. The ratio of infrared excess/stellar luminosity is a measure of the fraction of starlight absorbed by circumstellar dust and re-radiated in the infrared. The plot from Spangler et al. (2001) shows the temporal decline of dust around "Vega-like" stars (points) and stars in clusters with measured ages (circles). At least for the longer ages, the dust is most probably generated by comets.

Chasing Manxes: Long-Period Comets Without Tails

NASA Astrophysics Data System (ADS)

Stephens, Haynes; Meech, Karen Jean; Kleyna, Jan; Keane, Jacqueline; Hainaut, Olivier; Yang, Bin; Wainscoat, Richard J.; Micheli, Marco; Bhatt, Bhuwan; Sahu, Devendra

2017-10-01

A Manx is a minor body on a long-period comet orbit that is inactive or minimally active at small perihelion distances (where water would be expected to be strongly sublimating), resulting in the lack of a significant tail. These objects are being discovered at a rate of about a dozen per year from large all-sky surveys, and the Pan-STARRS1 telescope in Hawai'i is the most prolific at discovering these weakly active objects. Manxes are theorized to be planetesimals that formed in the inner solar system, perhaps some even in the Earth-forming region, that were subsequently ejected out into the Oort cloud due to the migration of Jupiter and Saturn as the Solar System evolved. We use spectral reflectivities obtained with the Gemini North 8m telescope and ESO's Very Large Telescope to determine the surface composition of these objects. The observed Manxes exhibit a wide variety of surface properties, from primitive materials (i.e. C-, P- or D-types) to anhydrous materials (i.e. S-types). The relative numbers of objects with surface materials that are consistent with relatively dry, rocky inner solar system material may be used to constrain dynamical solar system formation models which make different predictions about the amount and sources of material that gets ejected to the Oort cloud. To date, we have observed 27 Manxes from 2013-2017. Here, we present preliminary results from this survey of spectral reflectivities for various Manxes. In addition, for some of the objects, we have sufficient heliocentric photometry to model the activity in terms of water-ice sublimation and can obtain estimates of the amount of near-surface water in comparison to comets. This work is supported in part by an NSF award AST-1617015, and is based in part on observations obtained at the Gemini Observatory acquired through the Gemini Observatory Archive (GN2015A-FT18, GN2016A-Q15, GN2016A-FT22, GN2016B-Q19, GN-2016B-FT-24, GN-2017A-Q-14) and the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programmes 098.C-0303 and 099.C-0787.

Evaluation of genetic damage in tobacco and arsenic exposed population of Southern Assam, India using buccal cytome assay and comet assay.

PubMed

Roy, Prasenjit; Mukherjee, Anita; Giri, Sarbani

2016-02-01

Ground water is the principal source of drinking water in Assam. Ground water contamination of arsenic in drinking water is a great concern for human health and considered as a human carcinogen. The present cytogenetic biomonitoring study was undertaken to investigate the genotoxic effects associated with people of southern Assam consuming arsenic contaminated water and chewing tobacco. Employing the buccal cytome assay, exfoliated cells were analyzed in 138 individuals of age range 22-42 years and divided into four groups. Group I (n=54) are participants residing in localities where ground water contains arsenic concentration below the permissible limit (<10μg/l) and without any tobacco chewing history. Group II (n=32) participants from the same area but they are tobacco chewers. Group III (n=24) participants from localities where significantly high arsenic contamination in ground water were observed. Whereas the Group IV (n=28) consists of participants from the arsenic contaminated area and also tobacco chewers. Body mass index (BMI) in all the groups are found to be nearly same and in normal range. Statistically significant (P<0.001) increase in genotoxic, cell death parameters and cell proliferation biomarkers were observed in the Group IV compared to other groups. In the comet assay, percent of tail DNA gradually increases among the groups and has statistical significance. Spearman correlation revealed strong positive correlation between the arsenic exposed peoples and the binucleated cells (r=0.4763; P<0.001). Amount of chewing tobacco had significant positive correlation with micronucleus frequency (r=0.268; P<0.05) and karyolitic cells (r=0.217; P<0.05) and also in the percentage of tail DNA (r=0.5532, P<0.001). A statistically significant increase in glucose content and decrease in hemoglobin content as well as acetylcholine esterase in the blood of exposed individuals was observed. Our preliminary study indicate that population exposed to arsenic through drinking water may become more susceptible towards chewing tobacco induced nuclear damage as evaluated by buccal cytome assay and comet assay. Copyright © 2015 Elsevier Inc. All rights reserved.

Genotoxicity of citrate-coated silver nanoparticles to human keratinocytes assessed by the comet assay and cytokinesis blocked micronucleus assay.

PubMed

Bastos, V; Duarte, I F; Santos, C; Oliveira, H

2017-02-01

Silver nanoparticles (AgNPs) are widely used in industrial, cosmetic, and biomedical products, and humans are frequently exposed to these products through the skin. It is widely recognized that the characteristics of AgNPs (e.g., size, coating) may influence their cytotoxic effects, but their correlation with DNA damage and mitotic disorders remains poorly explored. In this study, human keratinocytes (HaCaT cell line) were exposed to well-characterized 30 nm AgNPs coated with citrate, and their effects on viability, DNA fragmentation (assessed by the comet assay), and micronuclei (MNi) induction (assessed by the cytokinesis-block micronucleus cytome assays, CBMN) were investigated. The results showed that 10 and 40 μg/mL AgNPs decreased cell proliferation and viability, and induced a significant genetic damage. This was observed by an increase of DNA amount in comet tail, which linearly correlated with dose and time of exposure. Also, cytostaticity (increase of mononucleated cells) and MNi rates increased in treated cells. In contrast, no significant changes were observed in nucleoplasmatic bridges (NPBs) or nuclear buds (NBUDs), although NBUDs tended to increase in all conditions and periods. The cytostatic effects on HaCaT cells were also shown by the decrease of their nuclear division index. Thus, both comet and CBMN assays supported the observation that citrate-AgNPs induced genotoxic effects on HaCaT cells. Considering that AgNPs are present in a vast number of consumer products and also in multiple nanomedicine skin applications and formulations, more research is needed to determine the properties that confer less toxicity of AgNPs to different cell lines.

Discovery of Main-belt Comet P/2006 VW139 by Pan-STARRS1

NASA Astrophysics Data System (ADS)

Hsieh, Henry H.; Yang, Bin; Haghighipour, Nader; Kaluna, Heather M.; Fitzsimmons, Alan; Denneau, Larry; Novaković, Bojan; Jedicke, Robert; Wainscoat, Richard J.; Armstrong, James D.; Duddy, Samuel R.; Lowry, Stephen C.; Trujillo, Chadwick A.; Micheli, Marco; Keane, Jacqueline V.; Urban, Laurie; Riesen, Timm; Meech, Karen J.; Abe, Shinsuke; Cheng, Yu-Chi; Chen, Wen-Ping; Granvik, Mikael; Grav, Tommy; Ip, Wing-Huen; Kinoshita, Daisuke; Kleyna, Jan; Lacerda, Pedro; Lister, Tim; Milani, Andrea; Tholen, David J.; Vereš, Peter; Lisse, Carey M.; Kelley, Michael S.; Fernández, Yanga R.; Bhatt, Bhuwan C.; Sahu, Devendra K.; Kaiser, Nick; Chambers, K. C.; Hodapp, Klaus W.; Magnier, Eugene A.; Price, Paul A.; Tonry, John L.

2012-03-01

The main-belt asteroid (300163) 2006 VW139 (later designated P/2006 VW139) was discovered to exhibit comet-like activity by the Pan-STARRS1 (PS1) survey telescope using automated point-spread-function analyses performed by PS1's Moving Object Processing System. Deep follow-up observations show both a short (~10'') antisolar dust tail and a longer (~60'') dust trail aligned with the object's orbit plane, similar to the morphology observed for another main-belt comet (MBC), P/2010 R2 (La Sagra), and other well-established comets, implying the action of a long-lived, sublimation-driven emission event. Photometry showing the brightness of the near-nucleus coma remaining constant over ~30 days provides further evidence for this object's cometary nature, suggesting it is in fact an MBC, and not a disrupted asteroid. A spectroscopic search for CN emission was unsuccessful, though we find an upper limit CN production rate of Q CN < 1.3 × 1024 mol s-1, from which we infer a water production rate of Q_H_2O<10^{26} mol s-1. We also find an approximately linear optical spectral slope of 7.2%/1000 Å, similar to other cometary dust comae. Numerical simulations indicate that P/2006 VW139 is dynamically stable for >100 Myr, while a search for a potential asteroid family around the object reveals a cluster of 24 asteroids within a cutoff distance of 68 m s-1. At 70 m s-1, this cluster merges with the Themis family, suggesting that it could be similar to the Beagle family to which another MBC, 133P/Elst-Pizarro, belongs.

Student-to-Scientist (S2S) via the PACA Project: Connecting Astronomers, Educators and Students

NASA Astrophysics Data System (ADS)

Yanamandra-Fisher, P. A.

2015-12-01

Student to Scientist (S2S), provides pathways for observational and research tools for K-12 and undergraduate students to improve science proficiency through conducting real scientific observations. Our approach lies in the integration of professional and amateur astronomers, educators, students, and communicators to identify multiple paths for the student to become a scientist. I report on the ensuing project, also known as the PACA Project, which is an ecosystem of various activities that take advantage of the social media and immediate connectivity amongst amateur astronomers worldwide and that can be galvanized to participate in a given observing campaign. The PACA Project has participated in organized campaigns such as NASA Comet ISON Observing Campaign in 2013; NASA Comet Integrated Observations Campaign to observe Comet Siding Spring as it flew by very close to Mars on 19 October 2014. Currently the PACA Project is involved in the Ground-based Amateur campaign to observer ESA/Rosetta mission's target, 67P/Churyumov-Gerasimenko (CG) that is en route to its perihelion on 13 August 2015 (at the time of abstract submission). The PACA Project provides access to the professional community and the student/educator and informal/public communities via various social media like Facebook, Twitter, Flickr, Pinterest, Vimeo, Google+. With the popularity of mobile platforms and instant connections with other peers globally, the multi-faceted social universe has become a vital part of engagement of multiple communities. The PACA project currently has initiated a Comet Tails and Disconnection Events campaign to relate to the changing solar wind conditions. Other PACA projects include Saturn Solstice 2017 and outreach projects with Astroproject (India). These and other citizen-science enabled activities and their integration with S2S project will be discussed.

DISCOVERY OF MAIN-BELT COMET P/2006 VW{sub 139} BY Pan-STARRS1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hsieh, Henry H.; Yang Bin; Haghighipour, Nader

2012-03-20

The main-belt asteroid (300163) 2006 VW{sub 139} (later designated P/2006 VW{sub 139}) was discovered to exhibit comet-like activity by the Pan-STARRS1 (PS1) survey telescope using automated point-spread-function analyses performed by PS1's Moving Object Processing System. Deep follow-up observations show both a short ({approx}10'') antisolar dust tail and a longer ({approx}60'') dust trail aligned with the object's orbit plane, similar to the morphology observed for another main-belt comet (MBC), P/2010 R2 (La Sagra), and other well-established comets, implying the action of a long-lived, sublimation-driven emission event. Photometry showing the brightness of the near-nucleus coma remaining constant over {approx}30 days provides furthermore » evidence for this object's cometary nature, suggesting it is in fact an MBC, and not a disrupted asteroid. A spectroscopic search for CN emission was unsuccessful, though we find an upper limit CN production rate of Q{sub CN} < 1.3 Multiplication-Sign 10{sup 24} mol s{sup -1}, from which we infer a water production rate of Q{sub H{sub 2O}}<10{sup 26} mol s{sup -1}. We also find an approximately linear optical spectral slope of 7.2%/1000 A, similar to other cometary dust comae. Numerical simulations indicate that P/2006 VW{sub 139} is dynamically stable for >100 Myr, while a search for a potential asteroid family around the object reveals a cluster of 24 asteroids within a cutoff distance of 68 m s{sup -1}. At 70 m s{sup -1}, this cluster merges with the Themis family, suggesting that it could be similar to the Beagle family to which another MBC, 133P/Elst-Pizarro, belongs.« less

On the dust environment of comet C/2012 S1 (ISON) from 12 AU pre-perihelion to the end of its activity around perihelion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moreno, F.; Pozuelos, F.; Aceituno, F.

2014-08-20

A Monte Carlo dust tail model has been applied to extract the dust environment parameters of the comet C/2012 S1 (ISON) from both Earth-based and SOHO LASCO C3 observations, performed from about six astronomical units (AU) inbound, to just after perihelion passage, when only a small portion of the original comet nucleus has survived in the form of a cloud of tiny particles. The early Afρ and image data are consistent with particle ejection from an extended active area located at latitudes 35°N to 90°N (for a prograde rotating nucleus), with the spin axis having a large obliquity (I ∼more » 70°). This configuration nicely fits the early images and Afρ data until 3.9 AU inbound, when the emission should become isotropic in order to fit the data. The analysis of LASCO images reveals that, assuming an original nucleus of R{sub N} = 500 m with ρ = 1000 kg m{sup –3}, at least half of its mass was vaporized when the comet was at about 17 R {sub ☉} inbound. We conclude that at that time the nucleus suffered a cataclysmic fragmentation releasing a huge amount of material of 2.3 ×10{sup 11} kg, equivalent to a sphere of 380 m in radius with density 1000 kg m{sup –3}. The surviving material after perihelion passage consists of very small dust particles of 0.1-50 μm in radius with a total mass of just 6.7×10{sup 8} kg.« less

Poly(A) tail length regulates PABPC1 expression to tune translation in the heart.

PubMed

Chorghade, Sandip; Seimetz, Joseph; Emmons, Russell; Yang, Jing; Bresson, Stefan M; Lisio, Michael De; Parise, Gianni; Conrad, Nicholas K; Kalsotra, Auinash

2017-06-27

The rate of protein synthesis in the adult heart is one of the lowest in mammalian tissues, but it increases substantially in response to stress and hypertrophic stimuli through largely obscure mechanisms. Here, we demonstrate that regulated expression of cytosolic poly(A)-binding protein 1 (PABPC1) modulates protein synthetic capacity of the mammalian heart. We uncover a poly(A) tail-based regulatory mechanism that dynamically controls PABPC1 protein synthesis in cardiomyocytes and thereby titrates cellular translation in response to developmental and hypertrophic cues. Our findings identify PABPC1 as a direct regulator of cardiac hypertrophy and define a new paradigm of gene regulation in the heart, where controlled changes in poly(A) tail length influence mRNA translation.

Citral degradation in micellar structures formed with polyoxyethylene-type surfactants.

PubMed

Park, Sung Joon; Hong, Chi Rac; Choi, Seung Jun

2015-03-01

In a micellar solution, the chemical degradation of poorly water-soluble food flavours can be influenced by the properties of the surfactants forming the micelles in aqueous solutions. To evaluate how hydrophilic head size and hydrophobic tail length influence the chemical degradation rate of food flavour, micelles were prepared with Brij surfactants (Brij 35, 58, 78 and 700), each of which had very similar molecular structures (polyoxyethylene fatty acid ether). The chemical degradation of citral in Brij micelles was found to be highest in an acidic environment. There was no significant difference in the chemical degradation rate of citral in Brij micelles in non-acidic conditions, regardless of the hydrophilic head size or hydrophobic tail length. Brij surfactants with larger hydrophilic heads effectively retarded the chemical degradation of citral in an acidic environment. Our findings suggest that the length of the hydrophobic tail rarely influenced the micelle's ability to chemically stabilize citral. Copyright © 2014 Elsevier Ltd. All rights reserved.

Spermatozoon structure and motility in the anuran Lepidobatrachus laevis.

PubMed

Waggener, W L; Carroll, E J

1998-02-01

Synthetic human gonadotropin releasing hormone (GnRH) injections were used for induction of spermatozoon release followed by cloacal lavage or mechanical stimulation of sperm release in Lepidobatrachus laevis. Light microscopic observations of Lepidobatrachus laevis spermatozoa indicated an acrosomal segment with a length of 4.1 microm delineated by an indentation, a nuclear region of 12.6 microm in length and a midpiece of 0.87 microm in length. The tail was 54.9 microm long by 1.35 microm wide with two lateral axial fibers and a central undulating membrane. At the electron microscopic level, the unusual tail had two complete axonemes that emanated from the distal centriole. The tail also contained two axial fibers 77 nm in diameter medial to the axonemes and was connected by an undulating membrane. An unusual accessory cell adherent to the head of the spermatozoon was noted in freshly obtained suspensions of spermatozoa. Spermatozoa with the accessory cell were motile and a subsequent loss of motility was correlated with the shedding of the accessory cell.

Nematodes of the Order Rhabditida from Andalucía Oriental, Spain. The Genera Nothacrobeles Allen &Noffsinger, 1971 and Zeldia Thorne, 1937

PubMed Central

Abolafia, J.; Peña-Santiago, R.

2003-01-01

A new species of the genus Nothacrobeles is described from natural areas (a salt lake) in the Southeast Iberian Peninsula. Nothacrobeles lanceolatus sp. n. is characterized by its body length, two rows of cuticular punctations per annulus, labial probolae bifurcate with divergent prongs, pharyngeal corpus 2.4 to 3.5 times isthmus length, spermatheca length, postuterine sac 0.5 to 1.1 times the corresponding body diameter ratio, female tail conical and bearing a spindle-shaped or conical mucro with acute terminus, phasmid at 8 to 17 µm posterior to the anus, male tail conical with acute mucro, spicules length, and gubernaculum length. In addition, Nothacrobeles cf. lunensis and Zeldia punctata are studied. Cervidellus capricornis is transferred to genus Nothacrobeles. A key to species of Nothacrobeles is also provided. PMID:19262756

An Analysis of the Effects of Wing Aspect Ratio and Tail Location on Static Longitudinal Stability Below the Mach Number of Lift Divergence

NASA Technical Reports Server (NTRS)

Axelson, John A.; Crown, J. Conrad

1948-01-01

An analysis is presented of the influence of wing aspect ratio and tail location on the effects of compressibility upon static longitudinal stability. The investigation showed that the use of reduced wing aspect ratios or short tail lengths leads to serious reductions in high-speed stability and the possibility of high-speed instability.

A continued program of planetary study at the University of Texas McDonald Observatory

NASA Technical Reports Server (NTRS)

Smith, H. J.; Barker, E. S.; Cochran, W. D.; Trafton, L. M.

1986-01-01

The beginning of eclipses of the Pluto-Charon system was detected. The onset of coma formation of P/Halley at 5.4 au was detected and evidence of sublimation at 4.8 au when CN emission was detected. Extensive spatial maps of the gas in the comae of comets Halley and Giacobini-Zinner were obtained in fall 1985. Halley was time variable, and Giacobini-Zinner was depleted in C2 and C3 relative to CN. Comet Kopff was shown to have a pre-perihelion brightness maximum of its gas, consistent with mantle development if the comet is a high obliquity object. New Haser model scale lengths for CN, C3, and C2 were determined using results from the Faint Comet Survey. Spectra of 12 asteroids in unusual orbits showed no evidence of any comet-like emission features. In particular, 3200 Phaethon (1983 TB) has no gas or dust coma, in spite of the similarity of its orbit with the Geminid meteor stream. Data were analyzed on Saturn's H2 and CH4 bands for the recent southern summer using a Tomasko-Doose type of haze distribution. This haze model fits the data moderately well, giving a CH4 mixing ratio of (4.2 + or 0.4)x003. Simple functions were found to approximate the collision-induced rotation-translation thermal opacity of H2.

Evaluating some computer exhancement algorithms that improve the visibility of cometary morphology

NASA Technical Reports Server (NTRS)

Larson, Stephen M.; Slaughter, Charles D.

1992-01-01

Digital enhancement of cometary images is a necessary tool in studying cometary morphology. Many image processing algorithms, some developed specifically for comets, have been used to enhance the subtle, low contrast coma and tail features. We compare some of the most commonly used algorithms on two different images to evaluate their strong and weak points, and conclude that there currently exists no single 'ideal' algorithm, although the radial gradient spatial filter gives the best overall result. This comparison should aid users in selecting the best algorithm to enhance particular features of interest.

Studies on fate and toxicity of nanoalumina in male albino rats: Lethality, bioaccumulation and genotoxicity.

PubMed

Morsy, Gamal M; El-Ala, Kawther S Abou; Ali, Atef A

2016-02-01

The purpose of this study is to follow-up the distribution, lethality percentile doses (LDs) and bioaccumulation of aluminium oxide nanoparticles (Al2O3-NPs, average diameter 9.83 ± 1.61 nm) in some tissues of male albino rats, and to evaluate its genotoxicity to the brain tissues, during acute and sublethal experiments. The LDs of Al2O3-NPs, including median lethal dose (LD50), were estimated after intraperitoneal injection. The computed LD50 at 24 and 48 h were 15.10 and 12.88 g/kg body weight (b.w.), respectively. For acute experiments, the bioaccumulation of aluminium (Al) in the brain, liver, kidneys, intestine and spleen was estimated after 48 h of injection with a single acute dose (3.9, 6.4 and 8.5 g/kg b.w.), while for sublethal experiments it was after 1, 3, 7, 14 and 28 days of injection with 1.3 g/kg b.w. once in 2 days. Multi-way analysis of variance affirmed that Al uptake, in acute experiments, was significantly affected by the injected doses, organs (brain, liver, kidneys, intestine and spleen) and their interactions, while for sublethal experiments an altogether effect based on time (1, 3, 7, 14, 28 days), doses (0 and 1.3 g), organs and their interactions was reported. In addition, Al accumulated in the brain, liver, kidney, intestine and spleen of rats administered with Al2O3-NPs were significantly higher than the corresponding controls, during acute and sublethal experiments. The uptake of Al by the spleen of rats injected with acute doses was greater than that accumulated by kidney>brain>intestine>liver, whereas the brain of rats injected with sublethal dose accumulated lesser amount of Al followed by the kidney

ISO's analysis of Comet Hale-Bopp

NASA Astrophysics Data System (ADS)

1997-03-01

The European Space Agency's Infrared Space Observatory ISO inspected Comet Hall-Bopp during the spring and autumn of 1996. The need to keep ISO's telescope extremely cold restricts the spacecraft's pointing in relation to the Sun and the Earth and it ruled out observations at other times. The analyses of the 1996 observations are not yet complete, but already they give new insight into the nature of comets. Comet Hale-Bopp is believed to be a large comet with a nucleus up to 40 kilometres wide. It was discovered in July 1995 by two American astronomers working independently, Alan Hale and Thomas Bopp. At that time, the comet was a billion kilometres away from the Sun, but 200 times brighter than Halley's Comet was, when at a comparable distance. Comet Hale-Bopp will make its closest approach to the Earth on 22 March, and its closest approach to the Sun (perihelion) on 1 April 1997. Some scientific results from ISO The discovery of Comet Hale-Bopp occurred before ISO's launch in November 1995. When first observed by ISO in March and April 1996, the comet was still 700 million kilometres from the Sun, and almost as far from the Earth and ISO. With its privileged view of infrared wavebands inaccessible from the Earth's surface, ISO's photometer ISOPHOT discovered that carbon dioxide was an important constituent of the comet's emissions of vapour.ISOPHOT measured the temperature of the dust cloud around Comet Hale-Bopp. In March 1996, when the comet was still more than 700 million kilometres from the Sun, the dust cloud was at minus 120 degrees C. When ISOPHOT made similar observations in October 1996, the comet was 420 million kilometres from the Sun, and the dust cloud had warmed to about minus 50 degrees C. Intensive observations of Comet Hale-Bopp were also made by ISO's Short-Wave Spectrometer SWS, the Long-Wave Spectrometer LWS, and the ISOPHOT spectrometer PHOT-S. Results are due for publication at the end of March. They will give details about the composition of the comet's dust and vapour, and also rates of escape of vapour, which will help in assessing the loss of material from Comet Hale-Bopp during this visit to the Sun's vicinity. "Watch out for some fascinating news," says Thijs de Graauw of Groningen University, who is in charge of the SWS instrument used in this study. "What excites me is the opportunity we shall have to compare dusty Comet Hale-Bopp, seen in the Solar System, with dusty objects far away among the stars which seem to be made of similar materials. Infrared astronomy has a special ability to unify cosmic chemistry at all scales from little dust grains in the Earth's vicinity to vast and distant galaxies." The dust itself interests the infrared astronomers, not least because their view of the Universe at large is spoiled to some extent by dust left behind by comets. Together with fine debris from asteroids, the comet dust makes a bright infrared band around the sky, which corresponds with the zodiacal light sometimes seen by eye, slanting above the horizon at twilight. ISO's predecessor, the US-Dutch-UK infrared astronomical satellite IRAS, found trails of comet dust much longer and more persistent than the familiar comet tails. ISO has seen a trail from Comet Kopff. By detecting dust grains that are typically much larger than those seen by visible light, ISO scientists hope to learn more about the dust's long-term behaviour in the Solar System. A series of images of Comet Hale-Bopp, obtained by the camera ISOCAM in October 1996, is the subject of continuing analysis. Leading this work in progress is Philippe Lamy of Marseille, France. "We hope to unveil the nucleus of the comet," Professor Lamy explains. "In principle, the Hubble Space Telescope can see finer details by visible light, but the contrast of the nucleus against the bright surrounding coma is superior at infrared wavelengths. This is because the thermal emission from the nucleus is very large and can be detected thanks to the high spatial resolution of ISO. We have a long time coverage of the comet, so we hope to determine the light-curve of the nucleus -- which, in turn, will reveal its gross shape and an estimate of its rotation period." A commanding role in comet research As comets are relics from the construction of the Solar System, and played a major role in the formation of the planets, they are a link between the Earth and the wider Universe of stars. The carbon compounds contained in comets probably contributed raw materials for the origin of life on the Earth, and according to one theory the Earth's oceans were made from comet ice. Growing knowledge of the composition and behaviour of comets is therefore crucial for a fuller understanding of our cosmic origins. ESA has a commanding role in space research on comets. Its Giotto spacecraft was the most daring of the international fleet of spacecraft that visited Halley's Comet in March 1986. Giotto obtained exceptional pictures and other data as it passed within 600 kilometres of the nucleus. Dust from the comet badly damaged the spacecraft, but in a navigational tour de force Giotto made an even closer approach to Comet Grigg-Skjellerup in July 1992. Now ESA is planning the Rosetta mission that will rendezvous with Comet Wirtanen and fly in company with it, making observations far more detailed than the fast flybys of Halley's Comet and Comet Grigg-Skjellerup could achieve. As for space astronomy, the International Ultraviolet Explorer, in which ESA was a partner, made unrivalled observations of Halley's Comet by ultraviolet light. ESA is also a partner in the Hubble Space Telescope, which saw the historic impacts of Comet Shoemaker-Levy 9 on Jupiter in July 1994, and has recently observed Comet Hyakutake as well as Hale-Bopp. The SOHO spacecraft, built by ESA for a joint ESA-NASA project to examine the Sun, has a distinctive view of comets. It has observed the hydrogen coronas of comets with its SWAN instrument. SOHO's coronagraph LASCO observed Comet Hyakutake rounding the Sun (when it was invisible to ground-based observers) and has discovered seven new comets very close to the Sun. Only ISO provides astronomers with information from comets across a very wide range of infrared wavelengths unobservable from the ground. Besides Comet Hale-Bopp, ISO has examined Comets Schwassmann-Wachmann 1, Chiron, Kopff, IRAS 1 and Wirtanen. The last of these, Comet Wirtanen, is the target of the Rosetta mission and is now making one of its six-yearly visits to the Sun's vicinity. Dietrich Lemke of Heidelberg, Germany, who is in charge of the ISOPHOT instrument in ISO, summarizes ISO's unique contribution. "By measuring the extremely weak heat rays from these frosty objects at different distances," Professor Lemke says, "we have a thermometer to gauge a comet's growing fever when it nears the Sun. As the temperature rises, first one kind of ice evaporates, and then another, producing various chemical signatures in the infrared spectrum. We can also characterize the mineral dust coming out of the comet. So ISO offers a vivid impression of comets in action which no other instrument can match." Photos are available on the ESA home page on Internet : http://www.estec.esa.nl/spdwww/iso/html/hale-bopp.htm

Principal component analysis of biometric traits to reveal body confirmation in local hill cattle of Himalayan state of Himachal Pradesh, India.

PubMed

Verma, Deepak; Sankhyan, Varun; Katoch, Sanjeet; Thakur, Yash Pal

2015-12-01

In the present study, biometric traits (body length [BL], heart girth [HG], paunch girth (PG), forelimb length (FLL), hind limb length (HLL), face length, forehead width, forehead length, height at hump, hump length (HL), hook to hook distance, pin to pin distance, tail length (TL), TL up to switch, horn length, horn circumference, and ear length were studied in 218 adult hill cattle of Himachal Pradesh for phenotypic characterization. Morphological and biometrical observations were recorded on 218 hill cattle randomly selected from different districts within the breeding tract. Multivariate statistics and principal component analysis are used to account for the maximum portion of variation present in the original set of variables with a minimum number of composite variables through Statistical software, SAS 9.2. Five components were extracted which accounted for 65.9% of variance. The first component explained general body confirmation and explained 34.7% variation. It was represented by significant loading for BL, HG, PG, FLL, and HLL. Communality estimate ranged from 0.41 (HL) to 0.88 (TL). Second, third, fourth, and fifth component had a high loading for tail characteristics, horn characteristics, facial biometrics, and rear body, respectively. The result of component analysis of biometric traits suggested that indigenous hill cattle of Himachal Pradesh are small and compact size cattle with a medium hump, horizontally placed short ears, and a long tail. The study also revealed that factors extracted from the present investigation could be used in breeding programs with sufficient reduction in the number of biometric traits to be recorded to explain the body confirmation.

DNA repair kinetic of hydrogen peroxide and UVA/B induced lesions in peripheral blood leucocytes from xeroderma pigmentosum patients and healthy subjects.

PubMed

Gonzalez, Elio A Prieto; Mudry, Marta D; Palermo, Ana Maria

2014-01-01

The objective of the present work was to study the fine kinetics of DNA repair in xeroderma pigmentosum (XP) syndrome, a complex disorder linked to a deficiency in repair that increases cancer susceptibility. The repair process was evaluated by the comet assay (CA) in cells from 2 XP patients and 9 controls exposed to UVA/B (UVA 366/UVB 280 nm) and H2O2 (150 μM) at temperatures of 4, 15, and 37°C. Samples were taken at 2-min intervals during the first 10 min to analyze the "fine kinetics" repair during the initial phase of the curve, and then at 15, 20, 25, 30, 45, 60, and 120 min. CA evaluation of DNA repair activity points to BER/NER initiation in the first 30 min with both inductors at 37°C and 15°C, but final comet length showed differences according to treatment. Repair kinetics during 120 min showed a good correlation with clinical features in both XP patients. Differences in final comet length were less pronounced in XP cells treated with H2O2 than with UVA/B, probably because the peroxide produces mainly base oxidation but less bulky lesions; UVA/B generates a mixture of both. These findings reinforce the value of CA in testing in DNA repair ability or exposure monitoring.

Novel full-length major histocompatibility complex class I allele discovery and haplotype definition in pig-tailed macaques.

PubMed

Semler, Matthew R; Wiseman, Roger W; Karl, Julie A; Graham, Michael E; Gieger, Samantha M; O'Connor, David H

2018-06-01

Pig-tailed macaques (Macaca nemestrina, Mane) are important models for human immunodeficiency virus (HIV) studies. Their infectability with minimally modified HIV makes them a uniquely valuable animal model to mimic human infection with HIV and progression to acquired immunodeficiency syndrome (AIDS). However, variation in the pig-tailed macaque major histocompatibility complex (MHC) and the impact of individual transcripts on the pathogenesis of HIV and other infectious diseases is understudied compared to that of rhesus and cynomolgus macaques. In this study, we used Pacific Biosciences single-molecule real-time circular consensus sequencing to describe full-length MHC class I (MHC-I) transcripts for 194 pig-tailed macaques from three breeding centers. We then used the full-length sequences to infer Mane-A and Mane-B haplotypes containing groups of MHC-I transcripts that co-segregate due to physical linkage. In total, we characterized full-length open reading frames (ORFs) for 313 Mane-A, Mane-B, and Mane-I sequences that defined 86 Mane-A and 106 Mane-B MHC-I haplotypes. Pacific Biosciences technology allows us to resolve these Mane-A and Mane-B haplotypes to the level of synonymous allelic variants. The newly defined haplotypes and transcript sequences containing full-length ORFs provide an important resource for infectious disease researchers as certain MHC haplotypes have been shown to provide exceptional control of simian immunodeficiency virus (SIV) replication and prevention of AIDS-like disease in nonhuman primates. The increased allelic resolution provided by Pacific Biosciences sequencing also benefits transplant research by allowing researchers to more specifically match haplotypes between donors and recipients to the level of nonsynonymous allelic variation, thus reducing the risk of graft-versus-host disease.

The ultimate and proximate mechanisms driving the evolution of long tails in forest deer mice

PubMed Central

Kingsley, Evan P.; Kozak, Krzysztof M.; Pfeifer, Susanne P.; Yang, Dou‐Shuan; Hoekstra, Hopi E.

2016-01-01

Understanding both the role of selection in driving phenotypic change and its underlying genetic basis remain major challenges in evolutionary biology. Here, we use modern tools to revisit a classic system of local adaptation in the North American deer mouse, Peromyscus maniculatus, which occupies two main habitat types: prairie and forest. Using historical collections, we find that forest‐dwelling mice have longer tails than those from nonforested habitat, even when we account for individual and population relatedness. Using genome‐wide SNP data, we show that mice from forested habitats in the eastern and western parts of their range form separate clades, suggesting that increased tail length evolved independently. We find that forest mice in the east and west have both more and longer caudal vertebrae, but not trunk vertebrae, than nearby prairie forms. By intercrossing prairie and forest mice, we show that the number and length of caudal vertebrae are not correlated in this recombinant population, indicating that variation in these traits is controlled by separate genetic loci. Together, these results demonstrate convergent evolution of the long‐tailed forest phenotype through two distinct genetic mechanisms, affecting number and length of vertebrae, and suggest that these morphological changes—either independently or together—are adaptive. PMID:27958661

Micellization Behavior of Long-Chain Substituted Alkylguanidinium Surfactants

PubMed Central

Bouchal, Roza; Hamel, Abdellah; Hesemann, Peter; In, Martin; Prelot, Bénédicte; Zajac, Jerzy

2016-01-01

Surface activity and micelle formation of alkylguanidinium chlorides containing 10, 12, 14 and 16 carbon atoms in the hydrophobic tail were studied by combining conductivity and surface tension measurements with isothermal titration calorimetry. The purity of the resulting surfactants, their temperatures of Cr→LC and LC→I transitions, as well as their propensity of forming birefringent phases, were assessed based on the results of 1H and 13C NMR, differential scanning calorimetry (DSC), and polarizing microscopy studies. Whenever possible, the resulting values of Krafft temperature (TK), critical micelle concentration (CMC), minimum surface tension above the CMC, chloride counter-ion binding to the micelle, and the standard enthalpy of micelle formation per mole of surfactant (ΔmicH°) were compared to those characterizing alkyltrimethylammonium chlorides or bromides with the same tail lengths. The value of TK ranged between 292 and 314 K and increased strongly with the increase in the chain length of the hydrophobic tail. Micellization was described as both entropy and enthalpy-driven. Based on the direct calorimetry measurements, the general trends in the CMC with the temperature, hydrophobic tail length, and NaCl addition were found to be similar to those of other types of cationic surfactants. The particularly exothermic character of micellization was ascribed to the hydrogen-binding capacity of the guanidinium head-group. PMID:26861309

Full-length genome sequence of a simian immunodeficiency virus from a wild-captured sun-tailed monkey in Gabon provides evidence for a species-specific monophyletic SIVsun lineage.

PubMed

Liégeois, Florian; Butel, Christelle; Mouinga-Ondéme, Augustin; Verrier, Delphine; Motsch, Peggy; Gonzalez, Jean-Paul; Peeters, Martine; Rouet, François; Onanga, Richard

2011-11-01

Since the first characterization of SIVsun (L14 strain) from a sun-tailed monkey (Cercopithecus solatus) in Gabon in 1999, no further information exists about the evolutionary history and geographic distribution of this lentivirus. Here, we report the full-length molecular characterization of a second SIVsun virus (SIVsunK08) naturally infecting a wild-caught sun-tailed monkey. The SIVsunK08 strain was most closely related to SIVsunL14 and clustered with members of the SIVmnd-1/SIVlhoest group. SIVsunK08 shared identical functional motifs in the LTR, Gag and Env proteins with SIVsunL14. Our data indicate that C. solatus is naturally infected with a monophyletic SIVsun strain.

Spin-tunnel investigation of the spinning characteristics of typical single-engine general aviation airplane designs. 2: Low-wing model A; tail parachute diameter and canopy distance for emergency spin recovery

NASA Technical Reports Server (NTRS)

Burk, S. M., Jr.; Bowman, J. S., Jr.; White, W. L.

1977-01-01

A spin tunnel study is reported on a scale model of a research airplane typical of low-wing, single-engine, light general aviation airplanes to determine the tail parachute diameter and canopy distance (riser length plus suspension-line length) required for energency spin recovery. Nine tail configurations were tested, resulting in a wide range of developed spin conditions, including steep spins and flat spins. The results indicate that the full-scale parachute diameter required for satisfactory recovery from the most critical conditions investigated is about 3.2 m and that the canopy distance, which was found to be critical for flat spins, should be between 4.6 and 6.1 m.

Thermal emission from large solid particles in the coma of comet C/2012 S1 (ISON) around perihelion

NASA Astrophysics Data System (ADS)

Keane, J.; Milam, S.; Coulson, I.; Gicquel, A.; Meech, K.; Yang, B.; Riesen, T.; Remijan, A.; Villanueva, G.; Corrinder, M.; Charnley, S.; Mumma, M.

2014-07-01

We report submillimeter dust-continuum observations for comet C/2012 S1 (ISON) obtained during the time period immediately before perihelion on 2013 November 28 (r = 0.0125 au). The variability and time resolution obtained in these images has revealed significant dust outbursts and have likely captured the onset of the final disruption event of comet ISON. The measured 450-μ m and 850-μ m submillimeter continuua are the strongest yet detected from a comet. Data were obtained with the SCUBA-2 submillimetre camera on the James Clerk Maxwell Telescope (JCMT) located at the 4000-m level of Mauna Kea, Hawaii during a week of scheduled day-time observing. Imaging is achieved simultaneously at wavelengths of 850 μ m and 450 μ m. Conditions necessary to obtain valuable results at 450 μ m occur relatively infrequently, and while atmospheric zenith opacities on the days involved were good (low), ranging between 0.08 (nepers at 225 GHz on the first day) and 0.05 (on the day of perihelion), the relatively low elevations of the observations (30--45 degrees), and consequent high line-of-sight opacities, limit the impact of the 450-μ m data. Each of the focal planes of SCUBA-2 is populated with 5000 bolometers, and provides an instantaneous Field of View of almost 10 arc minutes. In order to account effectively for the rapidly varying sky transmissions, the observational strategies adopted at JCMT involve scanning the telescope rapidly around the target in a daisy pattern, which produces fairly uniform coverage in exposure time of an area of diameter 3 arc minutes around the target centre. When comet ISON was first detected at 850 μ m, the 1-mm-sized dust particles were tightly bound to the comet nucleus until at least November 23. Three days later the dust was less tightly bound and became elongated and diffuse, spread out over as much as 120 arc seconds (80,000 km) in the anti-solar direction. Preliminary analyses of these observations suggest the detection of either a large-scale fragmentation event and/or the comet's disruption. The ratio of fluxes at 450 μ m and 850 μ m is 3.5±0.4, which compares well with the expected value of 3.7 if both data come from the Rayleigh-Jeans tail of a black-body spectrum of these temperatures. We discuss both the significance and limitations of our findings and compare them to other investigations obtained simultaneously at complementary wavelengths (such as SOHO and STEREO).

Evaluation of γ-radiation-induced DNA damage in two species of bivalves and their relative sensitivity using comet assay.

PubMed

Praveen Kumar, M K; Shyama, S K; Sonaye, B S; Naik, U Roshini; Kadam, S B; Bipin, P D; D'costa, A; Chaubey, R C

2014-05-01

Ionizing radiation is known to induce genetic damage in diverse groups of organisms. Under accidental situations, large quantities of radioactive elements get released into the environment and radiation emitted from these radionuclides may adversely affect both the man and the non-human biota. The present study is aimed (a) to know the genotoxic effect of gamma radiation on aquatic fauna employing two species of selected bivalves, (b) to evaluate the possible use of 'Comet assay' for detecting genetic damage in haemocytes of bivalves as a biomarker for environmental biomonitoring and also (c) to compare the relative sensitivity of two species of bivalves viz. Paphia malabarica and Meretrix casta to gamma radiation. The comet assays was optimized and validated using different concentrations (18, 32 and 56 mg/L) of ethyl methanesulfonate (EMS), a direct-acting reference genotoxic agent, to which the bivalves were exposed for various times (24, 48 and 72 h). Bivalves were irradiated (single acute exposure) with 5 different doses (viz. 2, 4, 6, 8 and 10 Gy) of gamma radiation and their genotoxic effects on the haemocytes were studied using the comet assay. Haemolymph was collected from the adductor muscle at 24, 48 and 72 h of both EMS-exposed and irradiated bivalves and comet assay was carried out using standard protocol. A significant increase in DNA damage was observed as indicated by an increase in % tail DNA damage at different concentrations of EMS and all the doses of gamma radiation as compared to controls in both bivalve species. This showed a dose-dependent increase of genetic damage induced in bivalves by EMS as well as gamma radiation. Further, the highest DNA damage was observed at 24h. The damage gradually decreased with time, i.e. was smaller at 48 and 72 h than at 24h post irradiation in both species of bivalves. This may indicate repair of the damaged DNA and/or loss of heavily damaged cells as the post irradiation time advanced. The present study reveals that gamma radiation induces single strand breaks in DNA as measured by alkaline comet assay in bivalves and comet assay serves as a sensitive and rapid method to detect genotoxicity of gamma radiation. This study further indicates that both M. casta and P. malabarica exhibit almost identical sensitivity to gamma radiation as measured by DNA damage. Copyright © 2014 Elsevier B.V. All rights reserved.

Tank tests to determine the effect of varying design parameters of planing-tail hulls II : effect of varying depth of step, angle of after- body keel, length of afterbody chine, and gross load

NASA Technical Reports Server (NTRS)

Dawson, John R; Mckann, Robert; Hay, Elizabeth S

1946-01-01

The second part of a series of tests made in Langley tank no. 2 to determine the effect of varying design parameters of planing-tail hulls is presented. Results are given to show the effects on resistance characteristics of varying angle of afterbody keel, depth of step, and length of afterbody chine. The effect of varying the gross load is shown for one configuration. The resistance characteristics of planing-tail hulls are compared with those of a conventional flying-boat hull. The forces on the forebody and afterbody of one configuration are compared with the forces on a conventional hull. Increasing the angle of afterbody keel had small effect on hump resistance and no effect on high-speed resistance but increased free-to-trim resistance at intermediate speeds. Increasing the depth of step increased hump resistance, had little effect on high-speed resistance, and increased free-to-trim resistance at intermediate speeds. Omitting the chines on the forward 25 percent of the afterbody had no appreciable effect on resistance. Omitting 70 percent of the chine length had almost no effect on maximum resistance but broadened the hump and increased spray around the afterbody. Load-resistance ratio at the hump decreased more rapidly with increasing load coefficient for the planing-tail hull than for the representative conventional hull, although the load-resistance ratio at the hump was greater for the planing-tail hull than for the conventional hull throughout the range of loads tested. At speeds higher than hump speed, load-resistance ratio for the planing-tail hull was a maximum at a particular gross load and was slightly less at heavier and lighter gross loads. The planing-tail hull was found to have lower resistance than the conventional hull at both the hump and at high speeds, but at intermediate speeds there was little difference. The lower hump resistance of the planing-tail hull was attributed to the ability of the afterbody to carry a greater percentage of the total load while maintaining a higher value of load-resistance ratio.

Simulation studies of structure and edge tension of lipid bilayer edges: effects of tail structure and force-field.

PubMed

West, Ana; Ma, Kevin; Chung, Jonathan L; Kindt, James T

2013-08-15

Molecular dynamics simulations of lipid bilayer ribbons have been performed to investigate the structures and line tensions associated with free bilayer edges. Simulations carried out for dioleoyl phosphatidylcholine with three different force-field parameter sets yielded edge line tensions of 45 ± 2 pN, over 50% greater than the most recently reported experimentally determined value for this lipid. Edge tensions obtained from simulations of a series of phosphatidylcholine lipid bilayer ribbons with saturated acyl tails of length 12-16 carbons and with monounsaturated acyl tails of length 14-18 carbons could be correlated with the excess area associated with forming the edge, through a two-parameter fit. Saturated-tail lipids underwent local thickening near the edge, producing denser packing that correlated with lower line tensions, while unsaturated-tail lipids showed little or no local thickening. In a dipalmitoyl phosphatidylcholine ribbon initiated in a tilted gel-phase structure, lipid headgroups tended to tilt toward the nearer edge producing a herringbone pattern, an accommodation that may account for the reported edge-induced stabilization of an ordered structure at temperatures near a lipid gel-fluid phase transition.

THE DUST ENVIRONMENT OF MAIN-BELT COMET P/2012 T1 (PANSTARRS)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moreno, F.; Pozuelos, F.; Cabrera-Lavers, A.

2013-06-20

The Main-Belt Comet P/2012 T1 (PANSTARRS) has been imaged using the 10.4 m Gran Telescopio Canarias and the 4.2 m William Herschel Telescope at six epochs in the period from 2012 November to 2013 February, with the aim of monitoring its dust environment. The dust tails' brightness and morphology are best interpreted in terms of a model of sustained dust emission spanning four to six months. The total dust mass ejected is estimated at {approx}6-25 Multiplication-Sign 10{sup 6} kg. We assume a time-independent power-law size distribution function, with particles in the micrometer to centimeter size range. Based on the qualitymore » of the fits to the isophote fields, an anisotropic emission pattern is favored against an isotropic one, in which the particle ejection is concentrated toward high latitudes ({+-}45 Degree-Sign to {+-}90 Degree-Sign ) in a high-obliquity object (I = 80 Degree-Sign ). This seasonally driven ejection behavior, along with the modeled particle ejection velocities, are in remarkable agreement to those we found for P/2010 R2 (La Sagra).« less

The tail sheath structure of bacteriophage T4: a molecular machine for infecting bacteria

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aksyuk, Anastasia A.; Leiman, Petr G.; Kurochkina, Lidia P.

2009-07-22

The contractile tail of bacteriophage T4 is a molecular machine that facilitates very high viral infection efficiency. Its major component is a tail sheath, which contracts during infection to less than half of its initial length. The sheath consists of 138 copies of the tail sheath protein, gene product (gp) 18, which surrounds the central non-contractile tail tube. The contraction of the sheath drives the tail tube through the outer membrane, creating a channel for the viral genome delivery. A crystal structure of about three quarters of gp18 has been determined and was fitted into cryo-electron microscopy reconstructions of themore » tail sheath before and after contraction. It was shown that during contraction, gp18 subunits slide over each other with no apparent change in their structure.« less

The cytoplasmic tail of L-selectin interacts with the adaptor-protein complex AP-1 subunit μ1A via a novel basic binding motif

PubMed Central

Tikhonova, Irina G.; Ivetic, Aleksandar; Schu, Peter

2017-01-01

L-selectin regulates leukocyte adhesion and rolling along the endothelium. Proteins binding to the cytoplasmic tail of L-selectin regulate L-selectin functions. We used L-selectin cytoplasmic tail peptide pulldown assays combined with high sensitivity liquid chromatography/mass spectrometry to identify novel L-selectin tail-binding proteins. Incubation of the L-selectin tail with cell extracts from phorbol 12-myristate 13-acetate-stimulated Raw 264.7 macrophages resulted in the binding of μ1A of the clathrin-coated vesicle AP-1 complex. Furthermore, full-length GST-μ1A and the GST-μ1A C-terminal domain, but not the GST-μ1A N-terminal domain, bind to L-selectin tail peptide, and the intracellular pool of L-selectin colocalizes with AP-1 at the trans-Golgi network. We identified a novel basic protein motif consisting of a cluster of three dibasic residues (356RR357, 359KK360, and 362KK363) in the membrane-proximal domain of the L-selectin tail as well as a doublet of aspartic acid residues (369DD370) in the membrane-distal end of the L-selectin tail involved in μ1A binding. Stimulation of Raw 264.7 macrophages with PMA augmented the amount of μ1A associated with anti-L-selectin immunoprecipitates. However, full-length GST-μ1A did not bind to the phospho-L-selectin tail or phospho-mimetic S364D L-selectin tail. Accordingly, we propose that phosphorylation of μ1A is required for interaction with the L-selectin tail and that L-selectin tail phosphorylation may regulate this interaction in vivo. Molecular docking of the L-selectin tail to μ1A was used to identify the μ1A surface domain binding the L-selectin tail and to explain how phosphorylation of the L-selectin tail abrogates μ1A interaction. Our findings indicate that L-selectin is transported constitutively by the AP-1 complex, leading to the formation of a trans-Golgi network reserve pool and that phosphorylation of the L-selectin tail blocks AP-1-dependent retrograde transport of L-selectin. PMID:28235798

The cytoplasmic tail of L-selectin interacts with the adaptor-protein complex AP-1 subunit μ1A via a novel basic binding motif.

PubMed

Dib, Karim; Tikhonova, Irina G; Ivetic, Aleksandar; Schu, Peter

2017-04-21

L-selectin regulates leukocyte adhesion and rolling along the endothelium. Proteins binding to the cytoplasmic tail of L-selectin regulate L-selectin functions. We used L-selectin cytoplasmic tail peptide pulldown assays combined with high sensitivity liquid chromatography/mass spectrometry to identify novel L-selectin tail-binding proteins. Incubation of the L-selectin tail with cell extracts from phorbol 12-myristate 13-acetate-stimulated Raw 264.7 macrophages resulted in the binding of μ1A of the clathrin-coated vesicle AP-1 complex. Furthermore, full-length GST-μ1A and the GST-μ1A C-terminal domain, but not the GST-μ1A N-terminal domain, bind to L-selectin tail peptide, and the intracellular pool of L-selectin colocalizes with AP-1 at the trans -Golgi network. We identified a novel basic protein motif consisting of a cluster of three dibasic residues ( 356 RR 357 , 359 KK 360 , and 362 KK 363 ) in the membrane-proximal domain of the L-selectin tail as well as a doublet of aspartic acid residues ( 369 DD 370 ) in the membrane-distal end of the L-selectin tail involved in μ1A binding. Stimulation of Raw 264.7 macrophages with PMA augmented the amount of μ1A associated with anti-L-selectin immunoprecipitates. However, full-length GST-μ1A did not bind to the phospho-L-selectin tail or phospho-mimetic S364D L-selectin tail. Accordingly, we propose that phosphorylation of μ1A is required for interaction with the L-selectin tail and that L-selectin tail phosphorylation may regulate this interaction in vivo Molecular docking of the L-selectin tail to μ1A was used to identify the μ1A surface domain binding the L-selectin tail and to explain how phosphorylation of the L-selectin tail abrogates μ1A interaction. Our findings indicate that L-selectin is transported constitutively by the AP-1 complex, leading to the formation of a trans -Golgi network reserve pool and that phosphorylation of the L-selectin tail blocks AP-1-dependent retrograde transport of L-selectin. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Real-time tracheal ultrasonography for confirmation of endotracheal tube placement during cardiopulmonary resuscitation.

PubMed

Chou, Hao-Chang; Chong, Kah-Meng; Sim, Shyh-Shyong; Ma, Matthew Huei-Ming; Liu, Shih-Hung; Chen, Nai-Chuan; Wu, Meng-Che; Fu, Chia-Ming; Wang, Chih-Hung; Lee, Chien-Chang; Lien, Wan-Ching; Chen, Shyr-Chyr

2013-12-01

This study aimed to evaluate the accuracy of tracheal ultrasonography for assessing endotracheal tube position during cardiopulmonary resuscitation (CPR). We performed a prospective observational study of patients undergoing emergency intubation during CPR. Real-time tracheal ultrasonography was performed during the intubation with the transducer placed transversely just above the suprasternal notch, to assess for endotracheal tube positioning and exclude esophageal intubation. The position of trachea was identified by a hyperechoic air-mucosa (A-M) interface with posterior reverberation artifact (comet-tail artifact). The endotracheal tube position was defined as endotracheal if single A-M interface with comet-tail artifact was observed. Endotracheal tube position was defined as intraesophageal if a second A-M interface appeared, suggesting a false second airway (double tract sign). The gold standard of correct endotracheal intubation was the combination of clinical auscultation and quantitative waveform capnography. The main outcome was the accuracy of tracheal ultrasonography in assessing endotracheal tube position during CPR. Among the 89 patients enrolled, 7 (7.8%) had esophageal intubations. The sensitivity, specificity, positive predictive value, and negative predictive value of tracheal ultrasonography were 100% (95% confidence interval [CI]: 94.4-100%), 85.7% (95% CI: 42.0-99.2%), 98.8% (95% CI: 92.5-99.0%) and 100% (95% CI: 54.7-100%), respectively. Positive and negative likelihood ratios were 7.0 (95% CI: 1.1-43.0) and 0.0, respectively. Real-time tracheal ultrasonography is an accurate method for identifying endotracheal tube position during CPR without the need for interruption of chest compression. Tracheal ultrasonography in resuscitation management may serve as a powerful adjunct in trained hands. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Oxidative Stress and Genotoxicity of Long-Term Occupational Exposure to Low Levels of BTEX in Gas Station Workers

PubMed Central

Xiong, Feng; Li, Qin; Zhou, Bo; Huang, Jiongli; Liang, Guiqiang; Zhang, Li’e; Ma, Shuyan; Qing, Li; Liang, Linhan; Su, Jing; Peng, Xiaowu; Li, Qin; Zou, Yunfeng

2016-01-01

Atmospheric benzene, toluene, ethylbenzene, and xylenes (BTEX) can lead to multiple health injuries. However, what remains uncertain is the effect of long-term exposure to low levels of BTEX. Thus, we determined the BTEX levels in the air from the refueling and office areas in gas stations. Then we collected workers’ (200 refueling vs. 52 office workers) peripheral blood samples to analyze the serum total-superoxide dismutase (T-SOD), glutathione (GSH), malondialdehyde (MDA), and 8-hydroxydeoxyguanosine (8-OHdG) levels. DNA damage was analyzed by the comet assay and micronucleus test in buccal epithelial cells. We found that the levels of BTEX in refueling areas were significantly higher than those in office areas (p < 0.001). The serum T-SOD and GSH of refueling workers were significantly lower than those in office workers (p < 0.001). By contrast, the serum MDA and 8-OHdG of refueling workers were significantly higher than those of office workers (p < 0.001, MDA; p = 0.025, 8-OHdG). Furthermore, tail and Olive tail moments in refueling workers were longer (p = 0.004, tail moment; p = 0.001, Olive tail moment), and the micronucleus rate was higher (p < 0.001) than those in office workers. Taken together, long-term exposure to low levels of BTEX may reduce the antioxidant ability and increase the risk of DNA damage in refueling workers of gas stations. PMID:27929445

Comparison of two wild rodent species as sentinels of environmental contamination by mine tailings.

PubMed

Tovar-Sánchez, E; Cervantes, L T; Martínez, C; Rojas, E; Valverde, M; Ortiz-Hernández, M L; Mussali-Galante, P

2012-06-01

Contamination with heavy metals is among the most hazardous environmental concerns caused by mining activity. A valuable tool for monitoring these effects is the use of sentinel organisms. Particularly, small mammals living inside mine tailings are an excellent study system because their analysis represents a realistic approach of mixtures and concentrations of metal exposure. We analyzed metal tissue concentrations and DNA damage levels for comparison between genders of a sentinel (Peromyscus melanophrys) and a nonsentinel (Baiomys musculus) species. Also, the relationship between DNA damage and the distance from the contamination source was evaluated. This study was conducted in an abandoned mine tailing at Morelos, Mexico. Thirty-six individuals from both species at the exposed and reference sites were sampled. Metal concentrations in bone and liver of both species were analyzed by atomic absorption spectrophotometry, and DNA damage levels were assayed using the alkaline comet assay. In general, concentrations of zinc, nickel, iron, and manganese were statistically higher in exposed individuals. A significant effect of the organ and the site on all metal tissue concentrations was detected. Significant DNA damage levels were registered in the exposed group, being higher in B. musculus. Females registered higher DNA damage levels than males. A negative relationship between distance from the mine tailing and DNA damage in B. musculus was observed. We consider that B. musculus is a suitable species to assess environmental quality, especially for bioaccumulable pollutants--such as metals--and recommend that it may be considered as a sentinel species.