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1

Reciprocal translocations in cattle: frequency estimation.  

PubMed

Chromosomal anomalies, like Robertsonian and reciprocal translocations, represent a big problem in cattle breeding as their presence induces, in the carrier subjects, a well-documented fertility reduction. In cattle, reciprocal translocations (RCPs, a chromosome abnormality caused by an exchange of material between non-homologous chromosomes) are considered rare as to date only 19 reciprocal translocations have been described. In cattle, it is common knowledge that the Robertsonian translocations represent the most common cytogenetic anomalies, and this is probably due to the existence of the endemic 1;29 Robertsonian translocation. However, these considerations are based on data obtained using techniques that are unable to identify all reciprocal translocations, and thus, their frequency is clearly underestimated. The purpose of this work is to provide a first realistic estimate of the impact of RCPs in the cattle population studied, trying to eliminate the factors that have caused an underestimation of their frequency so far. We performed this work using a mathematical as well as a simulation approach and, as biological data, we considered the cytogenetic results obtained in the last 15 years. The results obtained show that only 16% of reciprocal translocations can be detected using simple Giemsa techniques, and consequently, they could be present in no <0.14% of cattle subjects, a frequency five times higher than that shown by de novo Robertsonian translocations. This data is useful to open a debate about the need to introduce a more efficient method to identify RCP in cattle. PMID:22963362

De Lorenzi, L; Morando, P; Planas, J; Zannotti, M; Molteni, L; Parma, P

2012-10-01

2

Increased frequency of chromosome translocations in airline pilots with long-term flying experience  

PubMed Central

Background Chromosome translocations are an established biomarker of cumulative exposure to external ionising radiation. Airline pilots are exposed to cosmic ionising radiation, but few flight crew studies have examined translocations in relation to flight experience. Methods We determined the frequency of translocations in the peripheral blood lymphocytes of 83 airline pilots and 50 comparison subjects (mean age 47 and 46 years, respectively). Translocations were scored in an average of 1039 cell equivalents (CE) per subject using fluorescence in situ hybridisation (FISH) whole chromo-some painting and expressed per 100 CE. Negative binomial regression models were used to assess the relationship between translocation frequency and exposure status and flight years, adjusting for age, diagnostic x ray procedures, and military flying. Results There was no significant difference in the adjusted mean translocation frequency of pilots and comparison subjects (0.37 (SE 0.04) vs 0.38 (SE 0.06) translocations/100 CE, respectively). However, among pilots, the adjusted translocation frequency was significantly associated with flight years (p = 0.01) with rate ratios of 1.06 (95% CI 1.01 to 1.11) and 1.81 (95% CI 1.16 to 2.82) for a 1- and 10-year incremental increase in flight years, respectively. The adjusted rate ratio for pilots in the highest compared to the lowest quartile of flight years was 2.59 (95% CI 1.26 to 5.33). Conclusions This data suggests that pilots with long-term flying experience may be exposed to biologically significant doses of ionising radiation. Epidemiological studies with longer follow-up of larger cohorts of pilots with a wide range of radiation exposure levels are needed to clarify the relationship between cosmic radiation exposure and cancer risk. PMID:19074211

Yong, L C; Sigurdson, A J; Ward, E M; Waters, M A; Whelan, E A; Petersen, M R; Bhatti, P; Ramsey, M J; Ron, E; Tucker, J D

2008-01-01

3

Stability of the translocation frequency following whole-body irradiation measured in rhesus monkeys  

NASA Technical Reports Server (NTRS)

Chromosome translocations are persistent indicators of prior exposure to ionizing radiation and the development of 'chromosome painting' to efficiently detect translocations has resulted in a powerful biological dosimetry tool for radiation dose reconstruction. However, the actual stability of the translocation frequency with time after exposure must be measured before it can be used reliably to obtain doses for individuals exposed years or decades previously. Human chromosome painting probes were used here to measure reciprocal translocation frequencies in cells from two tissues of 8 rhesus monkeys (Macaca mulatta) irradiated almost three decades previously. Six of the monkeys were exposed in 1965 to whole-body (fully penetrating) radiation and two were unexposed controls. The primates were irradiated as juveniles to single doses of 0.56, 1.13, 2.00, or 2.25 Gy. Blood lymphocytes (and skin fibroblasts from one individual) were obtained for cytogenetic analysis in 1993, near the end of the animals' lifespans. Results show identical dose-response relationships 28 y after exposure in vivo and immediately after exposure in vitro. Because chromosome aberrations are induced with identical frequencies in vivo and in vitro, these results demonstrate that the translocation frequencies induced in 1965 have not changed significantly during the almost three decades since exposure. Finally, our emerging biodosimetry data for individual radiation workers are now confirming the utility of reciprocal translocations measured by FISH in radiation dose reconstruction.

Lucas, J. N.; Hill, F. S.; Burk, C. E.; Cox, A. B.; Straume, T.

1996-01-01

4

Low Frequency Electromagnetic Background Radiation From Electron Acceleration Above Thunderclouds  

NASA Astrophysics Data System (ADS)

It was recently proposed that the acceleration of electrons during the growth and branching of streamers above thunderclouds initiated by intense lightning discharges could result in detectable low frequency electromagnetic radiation from several tens of kHz up to several hundreds of kHz (Qin et al., GRL, 2012). The intensity of the predicted radiation scales with the streamer density which is particularly large during spectacular sprite occurrences such as jellyfish sprites and/or dancing sprites. Dancing sprites are up to one second long sequences of consecutive sprites or sprite groups which are typically separated by some hundreds of milliseconds and which tend to follow the spatial development of large scale intracloud lightning discharges. A particularly spectacular series of 10 dancing sprite events over a Mediterranean mesoscale convective system was recorded with a low light video camera in south-eastern France during the early morning hours of August 31, 2012. Each dancing sprite event was composed of ~3-4 consecutive sprites or groups of sprites. All of these sprite occurrences were associated with a sudden enhancement ~2 uV/m/Hz-1/2 of the low frequency electromagnetic background radiation as measured with a radio receiver in south-west England. It is estimated that ~1000 streamers at a height of ~40 km are necessary to epxlain the observed electric field strengths. These sudden enhancements are superimposed on a more continuous low frequency electromagnetic background radiation which accompanies each dancing sprite event. It is speculated that this low frequency 'radio glow' results from filamentary streamers near the cloud top as a result of the large scale electrostatic charging of the thundercloud and that it may be used as an indicator for sprite occurrences in future studies.

Fullekrug, Martin; Mezentsev, Andrew; Soula, Serge; van der Velde, Oscar; Farges, Thomas

2013-04-01

5

Prevalence and frequency of circulating t(14;18)-MBR translocation carrying cells in healthy individuals  

PubMed Central

The t(14;18) translocation is a common genetic aberration that can be seen as an early step in pathogenesis of follicular lymphoma (FL). The significance of low level circulating t(14;18)-positive cells in healthy individuals as clonal lymphoma precursors or indicators of risk is still unclear. We determined the age dependent prevalence and frequency of BCL2/IgH rearrangements in 715 healthy individuals ranging from newborns to octo- and nonagenarians. These results were compared with number of circulating t(14;18)-positive cells in 108 FL patients at initial presentation. The overall prevalence of BCL2/IgH junctions in this large sample was 46% (327/715). However, there was a striking dependence upon age. Specifically, among individuals up to 10 years old, none had detectable circulating t(14;18)-positive cells. In the age groups representing 10–50 years old, we found a steady elevation in the prevalence of BCL2/IgH junctions up to a prevalence of 66%. Further increases of the prevalence in individuals older than 50 years were not seen. The mean frequency of BCL2/IgH junctions in healthy individuals ?40 years (18–26 × 10?6) was significantly higher than in younger subjects (7–9 × 10?6). Four percent (31/715) of individuals carried more than one t(14;18)-positive cell per 25,000 peripheral blood mononuclear cells (PBMNCs). In comparison, 108 stage III/IV FL patients had a median number of circulating t(14;18)-positive malignant FL cells of about 9200/1 million PBMNCs (range 7–1,000,000). These findings will further improve the understanding of the relevance of t(14;18)-positive cells in healthy individuals as a risk marker toward the development into lymphoma precursors. PMID:19030176

Schuler, Frank; Dolken, Lars; Hirt, Carsten; Kiefer, Thomas; Berg, Tobias; Fusch, Gerhard; Weitmann, K.; Hoffmann, W.; Fusch, Christoph; Janz, Siegfried; Rabkin, Charles S.; Dolken, Gottfried

2014-01-01

6

Persistence of translocation frequencies in blood lymphocytes following radiotherapy: implications for retrospective radiation biodosimetry  

Microsoft Academic Search

Chromosome aberration analysis using a G-banding technique was performed on peripheral blood lymphocyte cultures from eight individuals over a 5 year period following therapeutic radiation exposure. Samples were placed in three time periods comprising 0–12, 12–36 and 36–60 months post-treatment. The group was heterogeneous with respect to exposure and this resulted in wide differences in initial total translocation yields. Total

E Janet Tawn; Caroline A Whitehouse

2003-01-01

7

Very high frequency gravitational wave background in the universe  

E-print Network

Astrophysical sources of high frequency gravitational radiation are considered in association with a new interest to very sensitive HFGW receivers required for the laboratory GW Hertz experiment. A special attention is paid to the phenomenon of primordial black holes evaporation. They act like black body to all kinds of radiation, including gravitons, and, therefore, emit an equilibrium spectrum of gravitons during its evaporation. Limit on the density of high frequency gravitons in the Universe is obtained, and possibilities of their detection are briefly discussed.

G. S. Bisnovatyi-Kogan; V. N. Rudenko

2004-06-22

8

Scattering of cold-atom coherences by hot atoms: frequency shifts from background-gas collisions.  

PubMed

Frequency shifts from background-gas collisions currently contribute significantly to the inaccuracy of atomic clocks. Because nearly all collisions with room-temperature background gases that transfer momentum eject the cold atoms from the clock, the interference between the scattered and unscattered waves in the forward direction dominates these frequency shifts. We show they are ? 10 times smaller than in room-temperature clocks and that van der Waals interactions produce the cold-atom background-gas shift. General considerations allow the loss of the Ramsey fringe amplitude to bound this frequency shift. PMID:23683186

Gibble, Kurt

2013-05-01

9

Scattering of Cold-Atom Coherences by Hot Atoms: Frequency Shifts from Background-Gas Collisions  

NASA Astrophysics Data System (ADS)

Frequency shifts from background-gas collisions currently contribute significantly to the inaccuracy of atomic clocks. Because nearly all collisions with room-temperature background gases that transfer momentum eject the cold atoms from the clock, the interference between the scattered and unscattered waves in the forward direction dominates these frequency shifts. We show they are ?10 times smaller than in room-temperature clocks and that van der Waals interactions produce the cold-atom background-gas shift. General considerations allow the loss of the Ramsey fringe amplitude to bound this frequency shift.

Gibble, Kurt

2013-05-01

10

Reciprocal translocations  

SciTech Connect

Chapter 26, describes reciprocal translocations of chromosomes: their occurrence, breakpoints, and multiple rearrangements. In addition, phenotypes of balanced and unbalanced translocation carriers and fetal death are discussed. Examples of translocation families are given. Meiosis and genetic risk in translocation carriers is presented. Finally, sperm chromosomes in meiotic segregation analysis is mentioned. 39 refs., 3 figs., 1 tab.

NONE

1993-12-31

11

Gut microbiota, tight junction protein expression, intestinal resistance, bacterial translocation and mortality following cholestasis depend on the genetic background of the host  

PubMed Central

Failure of the intestinal barrier is a characteristic feature of cholestasis. We have previously observed higher mortality in C57BL/6J compared with A/J mice following common bile duct ligation (CBDL). We hypothesized the alteration in gut barrier function following cholestasis would vary by genetic background. Following one week of CBDL, jejunal TEER was significantly reduced in each ligated mouse compared with their sham counterparts; moreover, jejunal TEER was significantly lower in both sham and ligated C57BL/6J compared with sham and ligated A/J mice, respectively. Bacterial translocation to mesenteric lymph nodes was significantly increased in C57BL/6J mice vs. A/J mice. Four of 15 C57BL/6J mice were bacteremic; whereas, none of the 17 A/J mice were. Jejunal IFN-? mRNA expression was significantly elevated in C57BL/6J compared with A/J mice. Western blot analysis demonstrated a significant decrease in occludin protein expression in C57BL/6J compared with A/J mice following both sham operation and CBDL. Only C57BL/6J mice demonstrated a marked decrease in ZO-1 protein expression following CBDL compared with shams. Pyrosequencing of the 16S rRNA gene in fecal samples showed a dysbiosis only in C57BL/6J mice following CBDL when compared with shams. This study provides evidence of strain differences in gut microbiota, tight junction protein expression, intestinal resistance and bacterial translocation which supports the notion of a genetic predisposition to exaggerated injury following cholestasis. PMID:23652772

Alaish, Samuel M.; Smith, Alexis D.; Timmons, Jennifer; Greenspon, Jose; Eyvazzadeh, Daniel; Murphy, Ebony; Shea-Donahue, Terez; Cirimotich, Shana; Mongodin, Emmanuel; Zhao, Aiping; Fasano, Alessio; Nataro, James P.; Cross, Alan S

2013-01-01

12

Background  

Cancer.gov

Extensive evidence has demonstrated that 24-hour dietary recalls provide the highest quality, least biased dietary data. Traditional 24-hour recalls, however, are expensive and impractical for large-scale research because they rely on trained interviewers and multiple administrations to estimate usual intakes. As a result, researchers often make use of food frequency questionnaires, which are less expensive but contain substantial error.

13

Propagation of the two-frequency coherence function in an inhomogeneous background random medium  

NASA Astrophysics Data System (ADS)

The spatial and temporal structures of time-dependent signals can be appreciably affected by random changes of the parameters of the medium characteristic of almost all geophysical environments. The dispersive properties of random media cause distortions in the propagating signal, particularly in pulse broadening and time delay. When there is also spatial variation of the background refractive index, the observer can be accessed by a number of background rays. In order to compute the pulse characteristics along each separate ray, there is a need to know the behaviour of the two-frequency mutual coherence function. In this work, we formulate the equation of the two-frequency mutual coherence function along a curved background ray trajectory. To solve this equation, a recently developed reference-wave method is applied. This method is based on embedding the problem into a higher dimensional space and is accompanied by the introduction of additional coordinates. Choosing a proper transform of the extended coordinate system allows us to emphasize 'fast' and 'slow' varying coordinates which are consequently normalized to the scales specific to a given type of problem. Such scaling usually reveals the important expansion parameters defined as ratios of the characteristic scales and allows us to present the proper ordering of terms in the desired equation. The performance of the main order solution is demonstrated for the homogeneous background case when the transverse structure function of the medium can be approximated by a quadratic term. This article is dedicated to the memory of Professor Reuven Mazar, a top notch scientist, whose creativity influenced many random media researchers. Professor Mazar passed away suddenly a few weeks before the publication of this paper.

Kalugin, Alexander; Bronshtein, Alexander; Mazar, Reuven

2004-07-01

14

Towards a High Temporal Frequency Grass Canopy Thermal IR Model for Background Signatures  

NASA Technical Reports Server (NTRS)

In this paper, we present our first results towards understanding high temporal frequency thermal infrared response from a dense plant canopy and compare the application of our model, driven both by slowly varying, time-averaged meteorological conditions and by high frequency measurements of local and within canopy profiles of relative humidity and wind speed, to high frequency thermal infrared observations. Previously, we have employed three-dimensional ray tracing to compute the intercepted and scattered radiation fluxes and for final scene rendering. For the turbulent fluxes, we employed simple resistance models for latent and sensible heat with one-dimensional profiles of relative humidity and wind speed. Our modeling approach has proven successful in capturing the directional and diurnal variation in background thermal infrared signatures. We hypothesize that at these scales, where the model is typically driven by time-averaged, local meteorological conditions, the primary source of thermal variance arises from the spatial distribution of sunlit and shaded foliage elements within the canopy and the associated radiative interactions. In recent experiments, we have begun to focus on the high temporal frequency response of plant canopies in the thermal infrared at 1 second to 5 minute intervals. At these scales, we hypothesize turbulent mixing plays a more dominant role. Our results indicate that in the high frequency domain, the vertical profile of temperature change is tightly coupled to the within canopy wind speed In the results reported here, the canopy cools from the top down with increased wind velocities and heats from the bottom up at low wind velocities. .

Ballard, Jerrell R., Jr.; Smith, James A.; Koenig, George G.

2004-01-01

15

SKY reveals a high frequency of unbalanced translocations involving chromosome 6 in t(12;21)-positive acute lymphoblastic leukemia.  

PubMed

The G-band cryptic t(12;21)(p13;q22) is the most common chromosomal rearrangement in childhood acute lymphoblastic leukemia (ALL). To investigate the nature of additional chromosomal events in this group of patients spectral karyotyping (SKY) following G-banding analysis was performed in 14 cases. From these cases six showed structural aberrations of chromosome 6, including both simple deletions and unbalanced translocations, and involved both q (n=4) and p (n=3) arms. The results show that rearrangements of 6p are also non-random events t(12;21)-positive ALL. This study illustrates the value of a combined SKY and G-banding approach in identifying novel karyotypic events in childhood ALL. PMID:17418891

Betts, David R; Stanchescu, Racheli; Niggli, Felix K; Cohen, Ninette; Rechavi, Gideon; Amariglio, Ninette; Trakhtenbrot, Luba

2008-01-01

16

Efficient induction of Wheat-agropyron cristatum 6P translocation lines and GISH detection.  

PubMed

The narrow genetic background restricts wheat yield and quality improvement. The wild relatives of wheat are the huge gene pools for wheat improvement and can broaden its genetic basis. Production of wheat-alien translocation lines can transfer alien genes to wheat. So it is important to develop an efficient method to induce wheat-alien chromosome translocation. Agropyroncristatum (P genome) carries many potential genes beneficial to disease resistance, stress tolerance and high yield. Chromosome 6P possesses the desirable genes exhibiting good agronomic traits, such as high grain number per spike, powdery mildew resistance and stress tolerance. In this study, the wheat-A. cristatum disomic addition was used as bridge material to produce wheat-A. cristatum translocation lines induced by (60)Co-?irradiation. The results of genomic in situ hybridization showed that 216 plants contained alien chromosome translocation among 571 self-pollinated progenies. The frequency of translocation was 37.83%, much higher than previous reports. Moreover, various alien translocation types were identified. The analysis of M2 showed that 62.5% of intergeneric translocation lines grew normally without losing the translocated chromosomes. The paper reported a high efficient technical method for inducing alien translocation between wheat and Agropyroncristatum. Additionally, these translocation lines will be valuable for not only basic research on genetic balance, interaction and expression of different chromosome segments of wheat and alien species, but also wheat breeding programs to utilize superior agronomic traits and good compensation effect from alien chromosomes. PMID:23874966

Song, Liqiang; Jiang, Lili; Han, Haiming; Gao, Ainong; Yang, Xinming; Li, Lihui; Liu, Weihua

2013-01-01

17

A measurement of the low frequency spectrum of the cosmic microwave background radiation  

SciTech Connect

As part of a larger effort to measure the spectrum of the Cosmic Background Radiation (CBR) at low frequencies, the intensity of the CBR has been measured at a frequency of 1.410 GHz. The measurement was made by comparing the power received from the sky with the power received from a specially designed cooled calibration target with known properties. Sources of radiation other than the CBR were then identified and subtracted to calculate the antenna temperature of the CBR at 1.410 GHz. The instrument used to measure the CBR was a total-power microwave radiometer with a 25 MHz bandwidth centered at 1.410 GHz. The radiometer had a noise temperature of 80 K, and sufficient data were taken that radiometer noise did not contribute significantly to the total measurement error. The sources of error were predominantly systematic in nature, and the largest error was due to uncertainty in the reflection characteristics of the cold-load calibrator. Identification and subtraction of signals from the Galaxy (0.7 K) and the Earth's atmosphere (0.8 K) were also significant parts of the data reduction and error analysis. The brightness temperature of the Cosmic Background Radiation at 1.410 GHz is 222. +- 0.55 Kelvin. The spectrum of the CBR, as determined by this measurement and other published results, is consistent with a blackbody spectrum of temperature 2.741 +- 0.016. Constraints on the amount by which the CBR spectrum deviates from Planck spectrum are used to place limits on energy releases early in the history of the universe. 55 refs., 25 figs., 8 tabs.

Levin, S.M.

1987-04-01

18

Haplotypic Background of a Private Allele at High Frequency in the Americas  

PubMed Central

Recently, the observation of a high-frequency private allele, the 9-repeat allele at microsatellite D9S1120, in all sampled Native American and Western Beringian populations has been interpreted as evidence that all modern Native Americans descend primarily from a single founding population. However, this inference assumed that all copies of the 9-repeat allele were identical by descent and that the geographic distribution of this allele had not been influenced by natural selection. To investigate whether these assumptions are satisfied, we genotyped 34 single nucleotide polymorphisms across ?500 kilobases (kb) around D9S1120 in 21 Native American and Western Beringian populations and 54 other worldwide populations. All chromosomes with the 9-repeat allele share the same haplotypic background in the vicinity of D9S1120, suggesting that all sampled copies of the 9-repeat allele are identical by descent. Ninety-one percent of these chromosomes share the same 76.26 kb haplotype, which we call the “American Modal Haplotype” (AMH). Three observations lead us to conclude that the high frequency and widespread distribution of the 9-repeat allele are unlikely to be the result of positive selection: 1) aside from its association with the 9-repeat allele, the AMH does not have a high frequency in the Americas, 2) the AMH is not unusually long for its frequency compared with other haplotypes in the Americas, and 3) in Latin American mestizo populations, the proportion of Native American ancestry at D9S1120 is not unusual compared with that observed at other genomewide microsatellites. Using a new method for estimating the time to the most recent common ancestor (MRCA) of all sampled copies of an allele on the basis of an estimate of the length of the genealogy descended from the MRCA, we calculate the mean time to the MRCA of the 9-repeat allele to be between 7,325 and 39,900 years, depending on the demographic model used. The results support the hypothesis that all modern Native Americans and Western Beringians trace a large portion of their ancestry to a single founding population that may have been isolated from other Asian populations prior to expanding into the Americas. PMID:19221006

Schroeder, Kari B.; Jakobsson, Mattias; Crawford, Michael H.; Schurr, Theodore G.; Boca, Simina M.; Conrad, Donald F.; Tito, Raul Y.; Osipova, Ludmilla P.; Tarskaia, Larissa A.; Zhadanov, Sergey I.; Wall, Jeffrey D.; Pritchard, Jonathan K.; Malhi, Ripan S.; Smith, David G.; Rosenberg, Noah A.

2009-01-01

19

Eliminating background noise in EMI test based on frequency-domain adaptive filtering  

Microsoft Academic Search

In non-standard test sites, background noise makes great influence to electromagnetic interference (EMI) measurements as a result of submergence of Equipment Under Test (EUT)'s own emission in the background noise. Accurate emission from a EUT is difficult to be obtained directly from measurement results. Focusing on this situation, this paper presents a method which eliminates background noise in EMI test

Qi Qiao; Fei Dai; Donglin Su; Haopeng Zheng; Jian Xu

2011-01-01

20

Production and identification of wheat-Agropyron cristatum 6P translocation lines.  

PubMed

The narrow genetic background of wheat is the primary factor that has restricted the improvement of crop yield in recent years. The kernel number per spike is the most important factor of the many potential characteristics that determine wheat yield. Agropyron cristatum (L.) Gaertn., a wild relative of wheat, has the characteristics of superior numbers of florets and kernels per spike, which are controlled by chromosome 6P. In this study, the wheat-A. cristatum disomic addition and substitution lines were used as bridge materials to produce wheat-A. cristatum 6P translocation lines induced by gametocidal chromosomes and irradiation. The results of genomic in situ hybridization showed that the frequency of translocation induced by gametocidal chromosomes was 5.08%, which was higher than the frequency of irradiated hybrids (2.78%) and irradiated pollen (2.12%). The fluorescence in situ hybridization results of the translocation lines showed that A. cristatum chromosome 6P could be translocated to wheat ABD genome, and the recombination frequency was A genome > B genome > D genome. The alien A. cristatum chromosome 6P was translocated to wheat homoeologous groups 1, 2, 3, 5 and 6. We obtained abundant translocation lines that possessed whole-arm, terminal, segmental and intercalary translocations. Three 6PS-specific and four 6PL-specific markers will be useful to rapidly identify and trace the translocated fragments. The different wheat-A. cristatum 6P translocation lines obtained in this study can provide basic materials for analyzing the alien genes carried by chromosome 6P. The translocation line WAT33-1-3 and introgression lines WAI37-2 and WAI41-1, which had significant characteristics of multikernel (high numbers of kernels per spike), could be utilized as novel germplasms for high-yield wheat breeding. PMID:20490543

Luan, Yang; Wang, Xiaoguang; Liu, Weihua; Li, Chunye; Zhang, Jinpeng; Gao, Ainong; Wang, Yandong; Yang, Xinming; Li, Lihui

2010-07-01

21

Robertsonian translocations  

SciTech Connect

Chapter 27, describes the occurrence of Robertsonian translocations (RTs), which refer to the recombination of whole chromosome arms, in both monocentric and dicentric chromosomes. The nonrandom participation of acrocentric chromosomes in RTs is documented by various methods, including unbiased ascertainment and ascertainment through trisomy, infertility, unspecified mental retardation, and Prader-Willi syndrome. Causes of nonrandom participation of chromosomes in RTs is presented, as are the following topics: segregation in carriers of RTs and segregation in sperm cells of RT carriers, interchromosomal effects and conclusions. 48 refs., 3 figs., 2 tabs.

NONE

1993-12-31

22

Adapting the buccal micronucleus cytome assay for use in wild birds: age and sex affect background frequency in pigeons.  

PubMed

Micronucleus (MN) formation has been used extensively as a biomarker of damage from genotoxic exposures. The Buccal MN Cytome (BMCyt) assay provides a noninvasive means of quantifying MN frequency in humans, but it has not been developed for use in wildlife. We adapted the BMCyt assay for use in wild birds, with a focus on feral pigeons (Columba livia) as a potential indicator species. Five of six urban bird species sampled using oral cavity swabs produced sufficient buccal cells for the BMCyt assay. The body size of species sampled ranged almost 100-fold (~60 to 5,000 g), but was a not major factor influencing the number of buccal cells collected. Pigeon cells were stained and scored following published BMCyt assay protocols for humans, but with a modified fixation approach using heat and methanol. Pigeons had the same common nuclear abnormalities reported in human studies, and a similar background MN formation frequency of 0.88 MN/1,000 cells. Adult pigeons had on average a threefold higher rate of MN formation than juveniles, and males had a 1.4- to 2.2-fold higher frequency than females. Domestic and feral pigeons did not differ in overall MN frequency. Our results indicate that the BMCyt assay can be used on wild birds, and could provide a means of assessing environmental genotoxicity in pigeons, a useful indicator species. However, bird age and sex are important factors affecting background MN frequency, and thereby the design of environmental studies. PMID:22121057

Shepherd, G L; Somers, C M

2012-03-01

23

A study of resonance structures with different frequency scales in the spectrum of background extremely low-frequency noise at middle latitudes  

NASA Astrophysics Data System (ADS)

Using the data of continuous monitoring of low-frequency background noise at the station "Novaya Zhizn" (Nizhny Novgorod Province, Russia) for 2006-2010, we studied a new spectral structure appearing in quasi-harmonic oscillations of the noise intensity with frequency scales a factor of 3 to 4 smaller than the scales of an ordinary spectral resonance structure. The features of the fine spectral structure were studied, i.e., frequency of occurrence, diurnal dynamics, and the frequency bandwidth. The features of an ordinary resonance structure were also studied in the "fine structure" appearance and the transition solar-activity periods (2010-2011). Using the calculations of the low-frequency magnetic fields propagating in a spherically horizontally inhomogeneous Earth-ionosphere waveguide, we analyzed the possible influence of the nonlocal ionospheric properties on the magnetic-component spectra in the range 0.1-20 Hz. It is shown that the influence of the nonlocal ionospheric properties on the extremely low-frequency spectra can be observed in the presence of an ionospheric horizontal inhomogeneity due to different shapes of the ionospheric-parameter profiles along the radio-wave propagation path.

Ermakova, E. N.; Polyakov, S. V.; Semenova, N. V.

2012-05-01

24

Frequency Multiplexed SQUID Readout of Large Bolometer Arrays for Cosmic Microwave Background Measurements  

E-print Network

A technological milestone for experiments employing Transition Edge Sensor (TES) bolometers operating at sub-kelvin temperature is the deployment of detector arrays with 100s--1000s of bolometers. One key technology for such arrays is readout multiplexing: the ability to read out many sensors simultaneously on the same set of wires. This paper describes a frequency-domain multiplexed readout system which has been developed for and deployed on the APEX-SZ and South Pole Telescope millimeter wavelength receivers. In this system, the detector array is divided into modules of seven detectors, and each bolometer within the module is biased with a unique ~MHz sinusoidal carrier such that the individual bolometer signals are well separated in frequency space. The currents from all bolometers in a module are summed together and pre-amplified with Superconducting Quantum Interference Devices (SQUIDs) operating at 4 K. Room-temperature electronics demodulate the carriers to recover the bolometer signals, which are digi...

Dobbs, M A; Aird, K A; Bender, A N; Benson, B A; Bleem, L E; Carlstrom, J E; Chang, C L; Cho, H -M; Clarke, J; Crawford, T M; Crites, A T; Flanigan, D I; de Haan, T; George, E M; Halverson, N W; Holzapfel, W L; Hrubes, J D; Johnson, B R; Joseph, J; Keisler, R; Kennedy, J; Kermish, Z; Lanting, T M; Lee, A T; Leitch, E M; Luong-Van, D; McMahon, J J; Mehl, J; Meyer, S S; Montroy, T E; Padin, S; Plagge, T; Pryke, C; Richards, P L; Ruhl, J E; Schaffer, K K; Schwan, D; Shirokoff, E; Spieler, H G; Staniszewski, Z; Stark, A A; Vanderlinde, K; Vieira, J D; Vu, C; Westbrook, B; Williamson, R

2011-01-01

25

Low-dose ionizing radiation and chromosome translocations: a review of the major considerations for human biological dosimetry.  

PubMed

Chromosome translocations are a molecular signature of ionizing radiation exposure. Translocations persist significantly longer after exposure than other types of chromosome exchanges such as dicentrics. This persistence makes translocations the preferred aberration type for performing radiation dosimetry under conditions of protracted exposure or when exposure assessments are temporally delayed. Low doses of radiation are inherently difficult to quantify because the frequency of induced events is low and the background level of translocations among unexposed subjects can show considerable variability. Analyses of translocation frequencies can be confounded by several factors, including age of the subject, lifestyle choices such as cigarette smoking, the presence of clones of abnormal cells, and possibly genotypic variability among subjects. No significant effects of gender or race have been observed, but racial differences have not been completely ruled out. Translocation analyses may be complicated by the presence of different types of exchanges, i.e., reciprocal or non-reciprocal, and because translocations sometimes occur as a component of complex exchanges that include other forms of chromosome rearrangements. Rates of radiation exposure, ranging from acute to chronic, are known to influence the accumulation of translocations and may also affect their persistence. The influences on translocation frequencies of low-dose radiation hypersensitivity as well as the bystander effect and the adaptive response remain poorly characterized. Thus, quantifying the relationship between radiation dose and the frequency of translocations in any given subject requires attention to multiple issues. Part of the solution to understanding the in vivo dose-response relationship is to have accurate estimates of the baseline levels of translocations in healthy unexposed subjects, and some work in this area has been accomplished. Long-term cytogenetic follow-up of exposed subjects is needed to characterize translocation persistence, which is especially relevant for risk analyses. More work also needs to be done in the area of quantifying the role of known confounders. Characterizing the role of genotype will be especially important. Improvements in the ability to use translocation frequencies for low-dose biological dosimetry will require scoring very large numbers of cells per subject, which may be accomplished by developing a rapid automated image analysis system. This work would enhance our comprehension of the effects of low-dose radiation exposure and could lead to significant improvements in understanding the relationship between chromosome damage and human health. PMID:18485804

Tucker, James D

2008-01-01

26

Frequency filtering to suppress background noise in fingerprint evidence: quantifying the fidelity of digitally enhanced fingerprint images.  

PubMed

Fingerprint evidence can benefit in image quality if transformed using digital image processing techniques. This is especially true when considering prints that cannot be easily lifted (such as those deposited on porous paper substrates), or when the mechanism of lifting does not effectively reduce background interferences. In these instances, frequency filtering is one type of mathematical transformation that can serve to increase image clarity and the ability to extract minutiae relevant to pairwise comparisons. To quantify the impact of frequency filtering on image quality, high quality and low quality (noisy) prints were collected. The high quality prints served as exemplars that were compared to the low quality prints both pre- and post-filtering. The resulting pairwise match scores indicate that: (1) frequency filtering has a low probability of creating false positive associations, (2) 90% of the post-filtered images result in a normalized gain in match score, (3) frequency filtering doubled the probability of obtaining match scores greater than 30% (for the automated algorithm employed in this study), and (4) filtering can double the probability of obtaining 10 or more matching minutiae when comparing same source prints. Overall, the research indicates a reasonable and quantifiable payoff in increased clarity, matching minutiae and pairwise similarity for post-filtered images when compared to known-match exemplars. PMID:25047216

Speir, Jacqueline A; Hietpas, Jack

2014-09-01

27

Spatial frequency characteristics at image decision-point locations for observers with different radiological backgrounds in lung nodule detection  

NASA Astrophysics Data System (ADS)

Aim: The goal of the study is to determine the spatial frequency characteristics at locations in the image of overt and covert observers' decisions and find out if there are any similarities in different observers' groups: the same radiological experience group or the same accuracy scored level. Background: The radiological task is described as a visual searching decision making procedure involving visual perception and cognitive processing. Humans perceive the world through a number of spatial frequency channels, each sensitive to visual information carried by different spatial frequency ranges and orientations. Recent studies have shown that particular physical properties of local and global image-based elements are correlated with the performance and the level of experience of human observers in breast cancer and lung nodule detections. Neurological findings in visual perception were an inspiration for wavelet applications in vision research because the methodology tries to mimic the brain processing algorithms. Methods: The wavelet approach to the set of postero-anterior chest radiographs analysis has been used to characterize perceptual preferences observers with different levels of experience in the radiological task. Psychophysical methodology has been applied to track eye movements over the image, where particular ROIs related to the observers' fixation clusters has been analysed in the spaces frame by Daubechies functions. Results: Significance differences have been found between the spatial frequency characteristics at the location of different decisions.

Pietrzyk, Mariusz W.; Manning, David J.; Dix, Alan; Donovan, Tim

2009-02-01

28

Promiscuity of translocation partners in multiple myeloma.  

PubMed

Multiple myeloma (MM) is characterized by karyotypic instability, including chromosomal translocations involving the IGH locus. MM cells display a promiscuity of translocation partners, only some of which are recurrent. We propose that several factors, including temporal and spatial nuclear positioning of potential partner loci, "off-target" IGH diversification mechanisms, and aberrant repair pathways contribute to the promiscuity of translocation partners in MM. We speculate that in MM, IGH diversification processes [V(D)J recombination, somatic hypermutation, and class switch recombination] in B cells may not be restricted to specific stages of B-cell development or within specific immune tissues, but may occur in different temporal "windows." Before or during MM evolution, off-target activities of the enzymes involved in IGH modification processes may contribute to the generation of double-strand breaks (DSB) in translocation partner loci. In the parent B cells from which MM originates, spatial proximity within the nucleus of IGH and potential translocation partners contributes to the selection of a translocation partner and the clinical frequency at which a specific translocation occurs. The spatial proximity of IGH and specific translocation partners may be temporal and contribute not only to partner selection but also to the promiscuity of partners seen in MM. Lastly, aberrant repair mechanisms in MM progenitors (including the possibility that a Ku 86 variant allows for positional instability at DSBs) may also contribute to the promiscuity of chromosome translocation partners in MM. PMID:20127714

Martin, Lorri D; Belch, Andrew R; Pilarski, Linda M

2010-04-15

29

Signal Photon Flux and Background Noise in a Coupling Electromagnetic Detecting System for High Frequency Gravitational Waves  

E-print Network

A coupling system between Gaussian type-microwave photon flux, static magnetic field and fractal membranes (or other equivalent microwave lenses) can be used to detect high-frequency gravitational waves (HFGWs) in the microwave band. We study the signal photon flux, background photon flux and the requisite minimal accumulation time of the signal in the coupling system. Unlike pure inverse Gertsenshtein effect (G-effect) caused by the HFGWs in the GHz band, the the electromagnetic (EM) detecting scheme (EDS) proposed by China and the US HFGW groups is based on the composite effect of the synchro-resonance effect and the inverse G-effect. Key parameters in the scheme include first-order perturbative photon flux (PPF) and not the second-order PPF; the distinguishable signal is the transverse first-order PPF and not the longitudinal PPF; the photon flux focused by the fractal membranes or other equivalent microwave lenses is not only the transverse first-order PPF but the total transverse photon flux, and these photon fluxes have different signal-to-noise ratios at the different receiving surfaces. Theoretical analysis and numerical estimation show that the requisite minimal accumulation time of the signal at the special receiving surfaces and in the background noise fluctuation would be $\\sim10^3-10^5$ seconds for the typical laboratory condition and parameters of $h_{r.m.s.}\\sim10^{-26}-10^{-30}$ at 5GHz with bandwidth $\\sim$1Hz. In addition, we review the inverse G-effect in the EM detection of the HFGWs, and it is shown that the EM detecting scheme based only on the pure inverse G-effect in the laboratory condition would not be useful to detect HFGWs in the microwave band.

F. Y. Li; N. Yang; Z. Y. Fang; R. M. L. Baker Jr.; G. V. Stephenson; H. Wen

2009-09-23

30

Mode of ATM-dependent suppression of chromosome translocation  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer We addressed how ATM suppresses frequency of chromosome translocation. Black-Right-Pointing-Pointer We found ATM/p53-dependent G1 checkpoint suppresses translocation frequency. Black-Right-Pointing-Pointer We found ATM and DNA-PKcs function in a common pathway to suppress translocation. -- Abstract: It is well documented that deficiency in ataxia telangiectasia mutated (ATM) protein leads to elevated frequency of chromosome translocation, however, it remains poorly understood how ATM suppresses translocation frequency. In the present study, we addressed the mechanism of ATM-dependent suppression of translocation frequency. To know frequency of translocation events in a whole genome at once, we performed centromere/telomere FISH and scored dicentric chromosomes, because dicentric and translocation occur with equal frequency and by identical mechanism. By centromere/telomere FISH analysis, we confirmed that chemical inhibition or RNAi-mediated knockdown of ATM causes 2 to 2.5-fold increase in dicentric frequency at first mitosis after 2 Gy of gamma-irradiation in G0/G1. The FISH analysis revealed that ATM/p53-dependent G1 checkpoint suppresses dicentric frequency, since RNAi-mediated knockdown of p53 elevated dicentric frequency by 1.5-fold. We found ATM also suppresses dicentric occurrence independently of its checkpoint role, as ATM inhibitor showed additional effect on dicentric frequency in the context of p53 depletion and Chk1/2 inactivation. Epistasis analysis using chemical inhibitors revealed that ATM kinase functions in the same pathway that requires kinase activity of DNA-dependent protein kinase catalytic subunit (DNA-PKcs) to suppress dicentric frequency. From the results in the present study, we conclude that ATM minimizes translocation frequency through its commitment to G1 checkpoint and DNA double-strand break repair pathway that requires kinase activity of DNA-PKcs.

Yamauchi, Motohiro, E-mail: motoyama@nagasaki-u.ac.jp [Graduate School of Biomedical Sciences, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523 (Japan)] [Graduate School of Biomedical Sciences, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523 (Japan); Suzuki, Keiji; Oka, Yasuyoshi; Suzuki, Masatoshi; Kondo, Hisayoshi; Yamashita, Shunichi [Graduate School of Biomedical Sciences, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523 (Japan)] [Graduate School of Biomedical Sciences, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523 (Japan)

2011-12-09

31

Adaptive method of recognition of signals for one and two-frequency signal system in the telephony on the background of speech  

NASA Astrophysics Data System (ADS)

For reliable teamwork of various systems of automatic telecommunication including transferring systems of optical communication networks it is necessary authentic recognition of signals for one- or two-frequency service signal system. The analysis of time parameters of an accepted signal allows increasing reliability of detection and recognition of the service signal system on a background of speech.

Kuznetsov, Michael V.

2006-05-01

32

Origin of chromosomal translocations in lymphoid cancer  

PubMed Central

Summary Aberrant fusions between heterologous chromosomes are among the most prevalent cytogenetic abnormalities found in cancer cells. Oncogenic chromosomal translocations provide cells with a proliferative or survival advantage. They may either initiate transformation or be acquired secondarily as a result of genomic instability. Here we highlight recent advances toward understanding the origin of chromosomal translocations in incipient lymphoid cancers and how tumor-suppressive pathways normally limit the frequency of these aberrant recombination events. Deciphering the mechanisms that mediate chromosomal fusions will open new avenues for developing therapeutic strategies aimed at eliminating lesions that lead to the initiation, maintenance, and progression of cancer. PMID:20371343

Nussenzweig, André; Nussenzweig, Michel C.

2010-01-01

33

An integrated maritime surveillance system based on high-frequency surface-wave radars. 1. Theoretical background and numerical simulations  

Microsoft Academic Search

An integrated maritime surveillance (IMS) system, based on high-frequency surface-wave radars (HFSWR), is described. IMS provides low-cost, 24-hour, real-time, over-the-horizon surveillance of large ocean areas, out to the 200 nautical mile Exclusive Economic Zone (EEZ). The system can be used to coordinate search and rescue operations, and to combat smuggling, drug trafficking, illegal dumping of pollutants, and other undesirable activities.

Levenf Sevgi; Anthony Ponsford; H. C. Chan

2001-01-01

34

Anomalous Dynamics of Translocation  

E-print Network

We study the dynamics of the passage of a polymer through a membrane pore (translocation), focusing on the scaling properties with the number of monomers $N$. The natural coordinate for translocation is the number of monomers on one side of the hole at a given time. Commonly used models which assume Brownian dynamics for this variable predict a mean (unforced) passage time $\\tau$ that scales as $N^2$, even in the presence of an entropic barrier. However, the time it takes for a free polymer to diffuse a distance of the order of its radius by Rouse dynamics scales with an exponent larger than 2, and this should provide a lower bound to the translocation time. To resolve this discrepancy, we perform numerical simulations with Rouse dynamics for both phantom (in space dimensions $d=1$ and 2), and self-avoiding (in $d=2$) chains. The results indicate that for large $N$, translocation times scale in the same manner as diffusion times, but with a larger prefactor that depends on the size of the hole. Such scaling implies anomalous dynamics for the translocation process. In particular, the fluctuations in the monomer number at the hole are predicted to be non-diffusive at short times, while the average pulling velocity of the polymer in the presence of a chemical potential difference is predicted to depend on $N$.

Jeffrey Chuang; Yacov Kantor; Mehran Kardar

2001-08-17

35

Background activity of neurons of the supraoptic hypothalamic nucleus in rats under conditions of vibrational stimulation and electromagnetic extrahigh-frequency irradiation  

Microsoft Academic Search

We analyzed background impulse activity of neurons of the supraoptic nucleus of the rat hypothalamus in the course of 15-day-long\\u000a isolated action of generalized vibrational stimulation and combination of such stimulation with irradiation of the animal’s\\u000a head with low-intensity extrahigh-frequency (EHF, millimeter-range) electromagmetic waves. The distributions of the neurons\\u000a by the level of regularity and dynamics of spike trains, separate

G. Yu. Grigoryan; S. M. Minasyan; S. G. Saakyan

2007-01-01

36

Problem-elephant translocation: translocating the problem and the elephant?  

PubMed

Human-elephant conflict (HEC) threatens the survival of endangered Asian elephants (Elephas maximus). Translocating "problem-elephants" is an important HEC mitigation and elephant conservation strategy across elephant range, with hundreds translocated annually. In the first comprehensive assessment of elephant translocation, we monitored 16 translocations in Sri Lanka with GPS collars. All translocated elephants were released into national parks. Two were killed within the parks where they were released, while all the others left those parks. Translocated elephants showed variable responses: "homers" returned to the capture site, "wanderers" ranged widely, and "settlers" established home ranges in new areas soon after release. Translocation caused wider propagation and intensification of HEC, and increased elephant mortality. We conclude that translocation defeats both HEC mitigation and elephant conservation goals. PMID:23236404

Fernando, Prithiviraj; Leimgruber, Peter; Prasad, Tharaka; Pastorini, Jennifer

2012-01-01

37

Chromosome translocations: Dangerous liaisons  

Microsoft Academic Search

Many chromosome abnormalities, especially translocations or inversions, are closely associated with a particular morphologic or phenotypic subtype of leukemia, lymphoma, or sarcoma. Cloning the genes at the breakpoints of these rearrangements has provided critical tools for more-precise diagnosis; in some cases the particular diagnosis has prognostic implications. In addition, many of the genes had not been previously identified; their discovery

Janet D. Rowley

1998-01-01

38

Translocation through environments with time dependent mobility.  

PubMed

We consider single particle and polymer translocation where the frictional properties experienced from the environment are changing in time. This work is motivated by the interesting frequency responsive behaviour observed when a polymer is passing through a pore with an oscillating width. In order to explain this better we construct general diffusive and non-diffusive frequency response of the gain in translocation time for a single particle in changing environments and look at some specific variations. For two state confinement, where the particle either has constant drift velocity or is stationary, we find exact expressions for both the diffusive and non-diffusive gain. We then apply this approach to polymer translocation under constant forcing through a pore with a sinusoidally varying width. We find good agreement for small polymers at low frequency oscillation with deviations occurring at longer lengths and higher frequencies. Unlike periodic forcing of a single particle at constant mobility, constant forcing with time dependent mobility is amenable to exact solution through manipulation of the Fokker-Planck equation. PMID:23206035

Cohen, Jack A; Chaudhuri, Abhishek; Golestanian, Ramin

2012-11-28

39

The Incidence and Type of Chromosomal Translocations from Prenatal Diagnosis of 3800 Patients in the Republic of Macedonia  

PubMed Central

Robertsonian and reciprocal chromosomal translocations are the most frequent type of structural chromosomal aberrations in the human population. We report the frequency and type of detected translocations in 10 years of prenatal diagnosis of 3800 prenatal samples. The materials came from amniocentesis and chorionic villus samples (CVS). We detected seven Robertsonian translocations (0.18%), eight autosomal reciprocal translocations (0.21%) and one sex chromosome translocation (0.03%). The overall frequency of all translocations was 0.42%. Balanced state translocations were 0.29% and the frequency of translocations in an unbalanced state was 0.13%. There was one balanced de novo X-autosome translocation [46,X,t(X;10)(p11.23;q22.3)] and one balanced double translocation [46,XX,t(1;21);t(7;16)(1p21; 21q11) (7q31;16q23)] inherited from the mother. Most of the detected translocations were the result of unknown familial translocations, but some of them had been previously detected in one of the parents. In order to detect the recurrence risk for future pregnancies, we proposed genetic counseling in each of the cases and we established whether the parents were heterozygous for the same translocation. Histopatological findings for some unbalanced translocations correlated with phenotypes of detected unbalanced karyotypes. PMID:24778559

Vasilevska, M; Ivanovska, E; Kubelka Sabit, K; Sukarova-Angelovska, E; Dimeska, G

2013-01-01

40

DNA damage defines sites of recurrent chromosomal translocations in B lymphocytes  

PubMed Central

Recurrent chromosomal translocations underlie both haematopoietic and solid tumours. Their origin has been ascribed to selection of random rearrangements, targeted DNA damage, or frequent nuclear interactions between translocation partners; however, the relative contribution of each of these elements has not been measured directly or on a large scale. Here we examine the role of nuclear architecture and frequency of DNA damage in the genesis of chromosomal translocations by measuring these parameters simultaneously in cultured mouse B lymphocytes. In the absence of recurrent DNA damage, translocations between Igh or Myc and all other genes are directly related to their contact frequency. Conversely, translocations associated with recurrent site-directed DNA damage are proportional to the rate of DNA break formation, as measured by replication protein A accumulation at the site of damage. Thus, non-targeted rearrangements reflect nuclear organization whereas DNA break formation governs the location and frequency of recurrent translocations, including those driving B-cell malignancies. PMID:22314321

Hakim, Ofir; Resch, Wolfgang; Yamane, Arito; Klein, Isaac; Kieffer-Kwon, Kyong-Rim; Jankovic, Mila; Oliveira, Thiago; Bothmer, Anne; Voss, Ty C.; Ansarah-Sobrinho, Camilo; Mathe, Ewy; Liang, Genqing; Cobell, Jesse; Nakahashi, Hirotaka; Robbiani, Davide F.; Nussenzweig, Andre; Hager, Gordon L.; Nussenzweig, Michel C.; Casellas, Rafael

2012-01-01

41

Foliar Absorption and Phloem Translocation  

NSDL National Science Digital Library

Herbicides must be absorbed into plants in order to be effective. Herbicide absorption can occur through leaves, roots or both. The process by which herbicides kill weeds, called mode of action, requires herbicide absorption and may also require herbicide movement or translocation within the plant. Translocation means that the herbicide moves from the site of absorption to some other plant part. Foliar applied herbicides that have the necessary characteristics to move in the phloem will translocate to areas of the plant that are actively growing; however, not all foliar-applied herbicides move from the leaves that intercepted the spray solution. Herbicides that are absorbed but not translocated are calledcontact herbicides, while herbicides that translocate to shoot or root meristems are called systemic herbicides. Absorption and translocation of xylem mobile herbicides will be discussed in another lesson.

42

Translocations in epithelial cancers  

PubMed Central

Genomic translocations leading to the expression of chimeric transcripts characterize several hematologic, mesenchymal and epithelial malignancies. While several gene fusions have been linked to essential molecular events in hematologic malignancies, the identification and characterization of recurrent chimeric transcripts in epithelial cancers has been limited. However, the recent discovery of the recurrent gene fusions in prostate cancer has sparked a revitalization of the quest to identify novel rearrangements in epithelial malignancies. Here, the molecular mechanisms of gene fusions that drive several epithelial cancers and the recent technological advances that increase the speed and reliability of recurrent gene fusion discovery are explored. PMID:19406209

Chad Brenner, J.; Chinnaiyan, Arul M.

2009-01-01

43

Mechanisms of oncogenic chromosomal translocations.  

PubMed

Chromosome translocations are caused by inappropriate religation of two DNA double-strand breaks (DSBs) in heterologous chromosomes. These DSBs can be generated by endogenous or exogenous sources. Endogenous sources of DSBs leading to translocations include inappropriate recombination activating gene (RAG) or activation-induced deaminase (AID) activity during immune receptor maturation. Endogenous DSBs can also occur at noncanonical DNA structures or at collapsed replication forks. Exogenous sources of DSBs leading to translocations include ionizing radiation (IR) and cancer chemotherapy. Spatial proximity of the heterologous chromosomes is also important for translocations. While three distinct pathways for DNA DSB repair exist, mounting evidence supports alternative nonhomologous end joining (aNHEJ) as the predominant pathway through which the majority of translocations occur. Initiated by poly (ADP-ribose) polymerase 1 (PARP1), aNHEJ is utilized less frequently in DNA DSB repair than other forms of DSB repair. We recently found that PARP1 is essential for chromosomal translocations to occur and that small molecule PARP1 inhibitors, already in clinical use, can inhibit translocations generated by IR or topoisomerase II inhibition. These data confirm the central role of PARP1 in aNHEJ-mediated chromosomal translocations and raise the possibility of using clinically available PARP1 inhibitors in patients who are at high risk for secondary oncogenic chromosomal translocations. PMID:24528169

Byrne, Michael; Wray, Justin; Reinert, Brian; Wu, Yuehan; Nickoloff, Jac; Lee, Suk-Hee; Hromas, Robert; Williamson, Elizabeth

2014-03-01

44

Translocations induced by fast neutrons and X-rays in Delia antiqua.  

PubMed

A comparison was made using X-rays and fast neutrons for the induction of translocations in Delia antiqua. Using the same radiation dose, no difference in efficiency between the two radiation types could be observed. However, with fast neutrons many multiple translocations were induced, including a quadruple translocation involving 4 out of 5 autosomes. One male linked translocation was also induced.The reciprocal translocations were assigned into two classes: symmetrical and asymmetrical, and ten of the latter were chosen for inbreeding to produce homozygotes. Asymmetrical exchanges were chosen so that translocation homozygotes could be differentiated cytologically from the normal karyotype. In seven different translocations, homozygous larvae were observed, but often at a low frequency. In four of these lines, viable adult homozygotes were observed. Subsequent random sib-crossing failed to produce a homozygous line. PMID:24276515

Robinson, A S; van Heemert, K

1981-09-01

45

Fluorescence in situ hybridization analysis using PAX8- and PPARG-specific probes reveals the presence of PAX8-PPARG translocation and 3p25 aneusomy in follicular thyroid neoplasms.  

PubMed

At the present time, the differentiation between follicular thyroid carcinoma (FTC) and adenoma can be made only postoperatively and is based on the presence of capsular or vascular invasion. The ability to differentiate preoperatively between the malignant and benign forms of follicular thyroid tumors assumes greater importance in any clinical setting. The PAX8-PPARG translocation has been reported to occur in the majority of FTC. In this study, a group of 60 follicular thyroid neoplasms [18 FTC, 1 Hurthle cell carcinoma (HCC), 24 follicular thyroid adenomas (FTA), 5 Hurthle cell adenomas (HCA), and 12 follicular variants of papillary thyroid carcinomas (FV-PTC)] were analyzed to determine the prevalence of the PAX8-PPARG translocation by fluorescence in situ hybridization. The PAX8-PPARG translocation was detected in 2/18 FTC (11.1%). In addition, 2/18 (11.1%) FTC and 1/5 (20%) HCA showed 3p25 aneusomy only. The frequency of the translocation detected in the study was lower compared to the earlier studies conducted in Western countries. This might be attributed to the ethnic background and geographic location. Detection of either the PAX8-PPARG translocation or the 3p25 aneusomy in FTC indicates that these are independent genetic events. It is hereby concluded that 3p25 aneusomy or PAX8-PPARG translocation may play an important role in the molecular pathogenesis of follicular thyroid tumors. PMID:19963130

Chia, Wai Kit; Sharifah, Noor Akmal; Reena, Rahayu Md Zin; Zubaidah, Zakaria; Clarence-Ko, Ching Huat; Rohaizak, Muhammad; Naqiyah, Ibrahim; Srijit, Das; Hisham, Abdullah Nor; Asmiati, Arbi; Rafie, Md Kaslan

2010-01-01

46

Structure and inheritance of some heterozygous Robertsonian translocation in man.  

PubMed Central

Banding studies in 25 Robertsonian translocations showed that all could be interpreted as stable dicentrics. The mechanism for their stability is likely to be the proximity of their centromeres but centromeric suppression could also have a role. In many of these dicentric translocations, discontinuous centromeric suppression, as indicated by chromatid separation at one of the centromeric regions, was observed in C-banded preparations. A further observation of undefined relation to the first was that the ratio of the two constitutive centromeric heterochromatin (CCH) regions from the component chromosomes of the translocations was variable in the same translocation type, e.g. t(13;14). It is proposed that this ratio may influence the segregation ratio. Abnormal spermatogenesis is suggested as the likely mechanism for the difference in the proportion of aneuploid offspring in the progeny of maternal and paternal heterozygotes. Neither of the t dic(21;21)s could be interpreted as isochromosomes. It is proposed that Robertsonian fusion translocations be defined as stable, dicentric, whole-arm translocations, with both centromeres in a median position and resulting in the loss of a small acentric fragment during this formation. It is suggested that they occur at high frequency between telocentric or, as in man, certain acrocentric chromosomes because of some intrinsic property of those chromosomes not possessed by metacentric chromosomes and mediated by interphase association of centromeres. Images PMID:1003449

Daniel, A; Lam-Po-Tang, P R

1976-01-01

47

Abdominal radiation causes bacterial translocation  

SciTech Connect

The purpose of this study was to determine if a single dose of radiation to the rat abdomen leads to bacterial translocation into the mesenteric lymph nodes (MLN). A second issue addressed was whether translocation correlates with anatomic damage to the mucosa. The radiated group (1100 cGy) which received anesthesia also was compared with a control group and a third group which received anesthesia alone but no abdominal radiation. Abdominal radiation lead to 100% positive cultures of MLN between 12 hr and 4 days postradiation. Bacterial translocation was almost nonexistent in the control and anesthesia group. Signs of inflammation and ulceration of the intestinal mucosa were not seen until Day 3 postradiation. Mucosal damage was maximal by Day 4. Bacterial translocation onto the MLN after a single dose of abdominal radiation was not apparently dependent on anatomical, histologic damage of the mucosa.

Guzman-Stein, G.; Bonsack, M.; Liberty, J.; Delaney, J.P.

1989-02-01

48

Are double translocations double trouble?  

PubMed Central

Double translocation heterozygotes are rare, but need not necessarily pose more of a counselling problem than single reciprocal translocation heterozygotes. Nine cases of double translocation are presented, together with a review of the few reports published to date. An attempt is made to provide simple counselling guidelines in the assessment of the risk of producing a liveborn abnormal child. This is not based on theoretical considerations of segregation patterns, but extrapolated from what is known empirically about the viable segregation patterns in carriers of single reciprocal translocations. It assumes that there is no interference with the independent assortment of the two separate exchanges, unless a common participating chromosome is involved. The possibility of an interchromosomal effect has not been taken into consideration. Images PMID:3290489

Bowser-Riley, S M; Griffiths, M J; Creasy, M R; Farndon, P A; Martin, K E; Thomson, D A; Larkins, S A; Johnson, R A; Watt, J L

1988-01-01

49

Multi-frequency polarimetry of the Galactic radio background around 350 MHz. I. A region in Auriga around l = 161 deg, b = 16 deg  

NASA Astrophysics Data System (ADS)

With the Westerbork Synthesis Radio Telescope (WSRT), multi-frequency polarimetric images were taken of the diffuse radio synchrotron background in a ~ 5 deg times 7 deg region centered on (l,b) = (161 deg ,16 deg ) in the constellation of Auriga. The observations were done simultaneously in 5 frequency bands, from 341 MHz to 375 MHz, and have a resolution of ~ 5.0arcminx5 .0arcmin cosec delta . The polarized intensity P and polarization angle phi show ubiquitous structure on arcminute and degree scales, with polarized brightness temperatures up to about 13 K. On the other hand, no structure at all is observed in total intensity I to an rms limit of 1.3 K, indicating that the structure in the polarized radiation must be due to Faraday rotation and depolarization mostly in the warm component of the nearby Galactic interstellar medium (ISM). Different depolarization processes create structure in polarized intensity P. Beam depolarization creates ``depolarization canals'' of one beam wide, while depth depolarization is thought to be responsible for creating most of the structure on scales larger than a beam width. Rotation measures (RM) can be reliably determined, and are in the range -17 <~ RM <~ 10 rad m-2 with a non-zero average RM0 ~ -3.4 rad m-2. The distribution of RMs on the sky shows both abrupt changes on the scales of the beam and a gradient in the direction of positive Galactic longitude of ~ 1 rad m-2 per degree. The gradient and average RM are consistent with a regular magnetic field of ~ 1 mu G which has a pitch angle of p = -14 deg. There are 13 extragalactic sources in the field for which RMs could be derived, and those have |RM| <~ 13 rad m-2, with an estimated intrinsic source contribution of ~ 3.6 rad m-2. The RMs of the extragalactic sources show a gradient that is about 3 times larger than the gradient in the RMs of the diffuse emission and that is approximately in Galactic latitude. This difference is ascribed to a vastly different effective length of the line of sight. The RMs of the extragalactic sources also show a sign reversal which implies a reversal of the magnetic field across the region on scales larger than about ten degrees. The observations are interpreted in terms of a simple single-cell-size model of the warm ISM which contains gas and magnetic fields, with a polarized background. The observations are best fitted with a cell size of 10 to 20 pc and a ratio of random to regular magnetic fields Bran/Breg ~ 0.7+/-0.5. The polarization horizon, beyond which most diffuse polarized emission is depolarized, is estimated to be at a distance of about 600 pc.

Haverkorn, M.; Katgert, P.; de Bruyn, A. G.

2003-06-01

50

HIGH-FREQUENCY-PEAKED BL LACERTAE OBJECTS AS SPECTRAL CANDLES TO MEASURE THE EXTRAGALACTIC BACKGROUND LIGHT IN THE FERMI AND AIR CHERENKOV TELESCOPES ERA  

SciTech Connect

The extragalactic background light (EBL) is the integrated light from all the stars that have ever formed, and spans the IR-UV range. The interaction of very high-energy (VHE: E > 100 GeV) {gamma}-rays, emitted by sources located at cosmological distances, with the intervening EBL results in e {sup -} e {sup +} pair production that leads to energy-dependent attenuation of the observed VHE flux. This introduces a fundamental ambiguity into the interpretation of measured VHE {gamma}-ray spectra: neither the intrinsic spectrum nor the EBL are separately known-only their combination is. In this Letter, we propose a method to measure the EBL photon number density. It relies on using simultaneous observations of BL Lac objects in the optical, X-ray, high-energy (HE: E > 100 MeV) {gamma}-ray (from the Fermi telescope), and VHE {gamma}-ray (from Cherenkov telescopes) bands. For each source, the method involves best-fitting the spectral energy distribution from optical through HE {gamma}-rays (the latter being largely unaffected by EBL attenuation as long as z {approx_lt} 1) with a synchrotron self-Compton model. We extrapolate such best-fitting models into the VHE regime and assume they represent the BL Lacs' intrinsic emission. Contrasting measured versus intrinsic emission leads to a determination of the {gamma}{gamma} opacity to VHE photons. Using, for each given source, different states of emission will only improve the accuracy of the proposed method. We demonstrate this method using recent simultaneous multifrequency observations of the high-frequency-peaked BL Lac object PKS 2155-304 and discuss how similar observations can more accurately probe the EBL.

Mankuzhiyil, Nijil [Physics Department, Udine University, via delle Scienze 208, I-33100 Udine (Italy); Persic, Massimo [INAF-Trieste, via G. B. Tiepolo 11, I-34143 Trieste (Italy); Tavecchio, Fabrizio [INAF-Brera, via E. Bianchi 46, I-23807 Merate (Italy)

2010-05-20

51

Anomalous Dynamics of Forced Translocation  

E-print Network

We consider the passage of long polymers of length N through a hole in a membrane. If the process is slow, it is in principle possible to focus on the dynamics of the number of monomers s on one side of the membrane, assuming that the two segments are in equilibrium. The dynamics of s(t) in such a limit would be diffusive, with a mean translocation time scaling as N^2 in the absence of a force, and proportional to N when a force is applied. We demonstrate that the assumption of equilibrium must break down for sufficiently long polymers (more easily when forced), and provide lower bounds for the translocation time by comparison to unimpeded motion of the polymer. These lower bounds exceed the time scales calculated on the basis of equilibrium, and point to anomalous (sub-diffusive) character of translocation dynamics. This is explicitly verified by numerical simulations of the unforced translocation of a self-avoiding polymer. Forced translocation times are shown to strongly depend on the method by which the force is applied. In particular, pulling the polymer by the end leads to much longer times than when a chemical potential difference is applied across the membrane. The bounds in these cases grow as N^2 and N^{1+\

Yacov Kantor; Mehran Kardar

2003-10-22

52

Root Absorption and Xylem Translocation  

NSDL National Science Digital Library

Overview: Herbicides must be absorbed into plants inorder to be effective. Plant roots and below ground shoots have fewbarriers to herbicide absorption; however, interactions with soilparticles and soil organic matter have significant impacts on theamount of herbicide available for plant absorption. Plant roots andbelow ground shoots (hypocotyls or coleoptiles) are lipophilic bynature and do not have thick, waxy cuticles like leaves. Lipophilic andhydrophilic herbicides reach the root surface by bulk transport in soilwater; however, there are a few examples of herbicides that reach theroot as a vapor or gas. Soil-applied herbicides can translocate to theshoot or remain in the root system. Soil-applied herbicides translocateto the shoot in the xylem and tend to accumulate in mature leaves thattranspire the most water. The lipophilic/hydrophilic nature of theherbicide will determine if the herbicide translocates to the shoot.Absorption and translocation of phloem-mobile herbicides will bediscussed in another lesson.

53

How does DNA break during chromosomal translocations?  

PubMed Central

Chromosomal translocations are one of the most common types of genetic rearrangements and are molecular signatures for many types of cancers. They are considered as primary causes for cancers, especially lymphoma and leukemia. Although many translocations have been reported in the last four decades, the mechanism by which chromosomes break during a translocation remains largely unknown. In this review, we summarize recent advances made in understanding the molecular mechanism of chromosomal translocations. PMID:21498543

Nambiar, Mridula; Raghavan, Sathees C.

2011-01-01

54

DNA translocation through graphene nanopores.  

PubMed

Nanopores--nanosized holes that can transport ions and molecules--are very promising devices for genomic screening, in particular DNA sequencing. Solid-state nanopores currently suffer from the drawback, however, that the channel constituting the pore is long, approximately 100 times the distance between two bases in a DNA molecule (0.5 nm for single-stranded DNA). This paper provides proof of concept that it is possible to realize and use ultrathin nanopores fabricated in graphene monolayers for single-molecule DNA translocation. The pores are obtained by placing a graphene flake over a microsize hole in a silicon nitride membrane and drilling a nanosize hole in the graphene using an electron beam. As individual DNA molecules translocate through the pore, characteristic temporary conductance changes are observed in the ionic current through the nanopore, setting the stage for future single-molecule genomic screening devices. PMID:20608744

Schneider, Grégory F; Kowalczyk, Stefan W; Calado, Victor E; Pandraud, Grégory; Zandbergen, Henny W; Vandersypen, Lieven M K; Dekker, Cees

2010-08-11

55

DNA Translocation through Graphene Nanopores  

E-print Network

Nanopores -- nanosized holes that can transport ions and molecules -- are very promising devices for genomic screening, in particular DNA sequencing. Both solid-state and biological pores suffer from the drawback, however, that the channel constituting the pore is long, viz. 10-100 times the distance between two bases in a DNA molecule (0.5 nm for single-stranded DNA). Here, we demonstrate that it is possible to realize and use ultrathin nanopores fabricated in graphene monolayers for single-molecule DNA translocation. The pores are obtained by placing a graphene flake over a microsize hole in a silicon nitride membrane and drilling a nanosize hole in the graphene using an electron beam. As individual DNA molecules translocate through the pore, characteristic temporary conductance changes are observed in the ionic current through the nanopore, setting the stage for future genomic screening.

Schneider, Grégory F; Calado, Victor E; Pandraud, Grégory; Zandbergen, Henny W; Vandersypen, Lieven M K; Dekker, Cees

2010-01-01

56

DNA translocation through graphene nanopores  

NASA Astrophysics Data System (ADS)

Nanopores are versatile platform for studying structure and behaviour of individual biopolymers. In a nanopore device, an individual DNA molecule in aqueous solution is electrophoretically threaded through the nano-scale pore in a linear fashion. Resulting modulation of the ionic current through the nanopore is characteristic of the geometrical and chemical properties of the translocating molecule. It has been shown that a new class of nanopore fabricated in free-standing single-layer graphene membrane -- graphene nanopores -- have excellent predisposition to achieve sub-nanometre resolution in discerning features along the length of individual DNA molecules [1]. In this talk, we will demonstrate very high sensitivity of the graphene nanopore current on small variation of the diameter of translocating molecule, and we will examine the dynamics of the DNA molecule within the graphene nanopore. The implications of those results on prospects of physical DNA sequencing will be discussed. [4pt] [1] S. Garaj et al., Nature 467, 190-193 (2010).

Garaj, Slaven

2013-03-01

57

Glycerol translocation in Condylactis gigantea  

Microsoft Academic Search

Sodium cyanide (NaCN) was used to partially uncouple respiration and photosynthesis in the symbiotic sea anemone Condylactis gigantea. NaCN significantly increased the ratio of gross photosynthesis to respiration in both intact tentacles and isolated zooxanthellae (Symbiodinium microadriaticum), increased carbon translocation from 17.7±3.5% of total fixed in controls to 43.5±5.8%, and doubled the amount of photosynthetically fixed carbon accumulating in the

J. F. Battey; J. S. Patton

1987-01-01

58

Glutamine deprivation facilitates tumour necrosis factor induced bacterial translocation in Caco-2 cells by depletion of enterocyte fuel substrate  

Microsoft Academic Search

Background and aims: Factors that induce luminal bacteria to cross the intestinal epithelium following injury remain poorly defined. The aim of this study was to investigate the interaction between glutamine metabolism, energy supply, and inflammatory mediators in determining the translocation of non-pathogenic bacteria across cultured enterocytes.Methods: The effect of tumour necrosis factor ? (TNF-?) on translocation of Escherichia coli C25

E C Clark; S D Patel; P R Chadwick; G Warhurst; A Curry; G L Carlson

2003-01-01

59

Evidence for separate translocation pathways in determining cadmium accumulation in grain and aerial plant parts in rice  

Microsoft Academic Search

BACKGROUND: Cadmium (Cd) translocation and accumulation in the grain and aerial plant parts of rice (Oryza sativa L.) is an important aspect of food safety and phytoextraction in areas with contaminated soil. Because control of Cd translocation and accumulation is likely to be determined by the plants genetics, the Cd contents of grain and the aerial parts of rice may

Takayuki Kashiwagi; Kumiko Shindoh; Naoki Hirotsu; Ken Ishimaru

2009-01-01

60

Detection of chemical agents in the atmosphere by open-path FT-IR spectroscopy under conditions of background interference: I. High-frequency flashes.  

PubMed

Open-path FT-IR spectra were measured while fireworks were emitting smoke and incandescent particles into the infrared beam. These conditions were designed to simulate the appearance of smoke and explosions in a battlefield. Diethyl ether was used to simulate the vapor-phase spectra of G agents such as sarin. The measured interferograms were corrected by a high-pass filter and were rejected when interfering features were of such high frequency that they could not be removed by application of this filter. The concentration of diethyl ether was calculated correctly by partial least squares regression in the absence of fireworks but significant errors were encountered when the spectra of the oxide particles were not included in the calibration set. Target factor analysis allowed the presence of the analyte to be detected even when the incandescent particles were present in the beam. PMID:20401469

Shao, Limin; Roske, Christopher W; Griffiths, Peter R

2010-06-01

61

Pollen germination and tube growth in rye (Secade cereale L.) homozygous and heterozygous for reciprocal translocations.  

PubMed

To contribute to the knowledge of the role of reciprocal translocations in rye, a component of fertility was estimated by comparing germination and pollen tube growth in homozygous and heterozygous plants for reciprocal translocations. The results obtained indicate that there are no differences in germination and pollen tube growth rate when homozygous and heterozygous plants as a whole are compared. However, there are significant differences in pollen tube growth between plants carrying different translocations. This suggests that the chromosome constitution of a plant is relevant to these fitness-estimating parameters together with its particular genetic background. PMID:24254028

Figueiras, A M; Candela, M; Lacadena, J R

1985-03-01

62

Cytological study of Searle's X-autosome translocation in Mus musculus  

Microsoft Academic Search

Genetic studies on Searle'S X-autosome translocation of Mus musculus have shown that a segment of the X carrying the loci for two sex-linked genes, Ta and Blo, has been translocated to an autosome. Females heterozygous for Tabby normally have variegated hair structures, with transverse Ta bands visible against a background of wildtype fur. When the wild-type allele of Ta or

Susumu Ohno; Mary F. Lyon

1965-01-01

63

Underground statistical measurements of the world-wide magnetic-background level in the millihertz frequency range with the [SQUID]2 magnetometer  

NASA Astrophysics Data System (ADS)

The passive ground sensor system [SQUID]2 (SQUID with Shielding QUalified for Ionosphere Detection) is a three-axis cryogenically cooled magnetometer installed within the LSBB (Laboratoire Souterrain à Bas Bruit) in the South-East of France. This permanent operating device is sheltered by a unique underground shielded cell buried under 518m of karstic rock in a low noise environment, leading to a noise level lower than 3 fT/?Hz above 40Hz. Various phenomena, mainly linked to earthquakes contributions, have been identified at the local scale through a magneto-hydrodynamic correlation or at the global ones, resulting from the Earth-ionosphere coupling. As standing waves altering the surface of the Earth, free oscillations of Earth consecutive to earthquake events can also contribute to the magnetic field variation. Because the ionosphere is a complex and nonlinear system affected by a large number of independent parameters, it appears obvious to constrain the number of sources. Investigation of the ULF magnetic pulsations detected by [SQUID]2 over very quiet seismic and ionospheric conditions allows to defined a first experimental baseline of ionosphere magnetic noise [Marfaing et al. 2009]. Here, the analysis is performed to a set of 24 magnetically quiet days in order to establish a statistical baseline for the "global minimal magnetic level" in the site. The mean magnetic spectrum obtained in the millihertz range is characterized by several pulsations of noticeable amplitude above the flicker noise. An attempt of discrimination of the seismogenic contribution has been proposed through the polarization analysis proposed by Hayakawa et al. [2007]. Some frequencies coincide with the Earth's eigenmodes with less than 1% deviation; this includes the possibility of the superposition of several interplaying signals in the spectra of ionospheric or Earth's origin, assumed by the weak turbulence theory. These results provide complementary analysis to validate the various theoretical models of the free oscillations of Earth and extend the knowledge of the Earth-ionosphere coupling.

Pozzo di Borgo, E.; Marfaing, J.; Waysand, G.

2012-04-01

64

Short communication: Robertsonian translocations, chimerism, and aneuploidy in cattle.  

PubMed

The aim of this study was to evaluate frequencies of Robertsonian translocations, aneuploidy, and chimerism in Holstein-Friesian, Czech Simmental, and different beef breeds in the Czech Republic from 1996 to 2007. A total of 2,425 animals were examined: 2,377 males, (991 Holstein-Friesians, 1,218 Czech Simmental sires, 168 sires of beef breeds) and 48 females. Translocation was found in 10 Czech Simmental sires, 2 Highland, 1 Charolais, and 3 Blonde d' Aquitaine sires, and in 13 females. Chimerism (XX/XY) was found in 9 Czech Simmental sires, and in 5 Holstein-Friesian sires; XXX trisomy was found in 2 heifers and XXY trisomy in 3 Charolais sires. We recommend that animals with such anomalies should be disqualified from siring stock bulls. PMID:19528626

Citek, J; Rubes, J; Hajkova, J

2009-07-01

65

Persistence of radiation-induced translocations in rat peripheral blood determined by chromosome painting  

SciTech Connect

In this article, we address the issue of persistence of chromosome exchanges following acute in vitro exposure of rat peripheral blood to {sup 137}Cs. Irradiation occurred 24 hr after culture initiation, and metaphase chromosomes were prepared 2, 3, 4, and 5 days later. Chromosomes 1, 2, and 4 were painted in unique colors and scored for structural aberrations. Dicentric chromosomes an acentric fragments diminished rapidly with time, as expected. Translocations exhibited greater persistence, but still showed a reduction in frequency, reaching a plateau of approximately 65 and 55% of their initial values, 4 days after exposure to 1 and 2 Gy, respectively. An exponentially declining model was fit to the combined dicentric, acentric fragment, and translocation frequencies, which showed that all three aberration types declined at equivalent rates. The frequencies of dicentrics and fragments declined to a plateau of zero, while translocations reached a plateau at frequencies significantly greater than zero. The decline in translocations with time is inconsistent with prevailing theoretical expectations, but is consistent with a model where some translocations are fully stable (persistent) and some are unstable (not persistent) through cell division. These results may have implications for radiation biodosimetry in humans.

Tucker, J.D.; Briner, J.F.; Eveleth, G.G. [Lawrence Livermore National Lab., CA (United States)] [and others] [Lawrence Livermore National Lab., CA (United States); and others

1997-12-31

66

Chloroplast translocations induced by light pulses  

Microsoft Academic Search

The effect of single blue-light pulses on chloroplast rearrangement was studied in the leaves of Tradescantia albiflora, Chlorophytum elatum, and Lemna trisulca. For measuring translocations in terrestrial plants the method of transmission changes was used; translocations in the water plant Lemna were studied by direct microscopic observation and counting. Strong light (30 W m-2) applied in the form of short

H. Gabrygl; T. Walczak; J. Zurzyckil

1981-01-01

67

Bacterial translocation from the gastrointestinal tract  

Microsoft Academic Search

Bacterial translocation is defined as the passage of viable indigenous bacteria from the gastrointestinal tract to extraintestinal sites, such as the mesenteric-lymph-node complex, liver, spleen and bloodstream. Three major mechanisms promote bacterial translocation: intestinal bacterial overgrowth, deficiencies in host immune defenses and increased permeability or damage to the intestinal mucosal barrier.

Rodney D. Berg

1995-01-01

68

Translocation in the nonpolytrichaceous moss grimmia laevigata  

Microsoft Academic Search

A superficially rhizomatous habit suggested that the moss Grimmia laevigata might function as a clonal, rhizomatous plant and translocate photoassimilates to below ground organs, even though the species is outside the order Polytrichales, which includes the only mosses known to posses sieve cells. Labelling with ¹⁴COâ indicated that at least 10% of newly assimilated carbon was translocated out of leafy

Peter Alpert

1989-01-01

69

Translocations among Antibody Genes in Human Cancer  

Microsoft Academic Search

The characteristic chromosomal translocations that occur in certain human malignancies offer opportunities to understand how two gene systems can affect one another when they are accidentally juxtaposed. In the case of Burkitt lymphoma, such a translocation joins the cellular oncogene, c-myc, to a region encoding one of the immunoglobulin genes. In at least one example, the coding sequence of the

Philip Leder; Jim Battey; Gilbert Lenoir; Christopher Moulding; William Murphy; Huntington Potter; Timothy Stewart; Rebecca Taub

1983-01-01

70

DNA translocation through graphene nanopores.  

PubMed

We report on DNA translocations through nanopores created in graphene membranes. Devices consist of 1-5 nm thick graphene membranes with electron-beam sculpted nanopores from 5 to 10 nm in diameter. Due to the thin nature of the graphene membranes, we observe larger blocked currents than for traditional solid-state nanopores. However, ionic current noise levels are several orders of magnitude larger than those for silicon nitride nanopores. These fluctuations are reduced with the atomic-layer deposition of 5 nm of titanium dioxide over the device. Unlike traditional solid-state nanopore materials that are insulating, graphene is an excellent electrical conductor. Use of graphene as a membrane material opens the door to a new class of nanopore devices in which electronic sensing and control are performed directly at the pore. PMID:20698604

Merchant, Christopher A; Healy, Ken; Wanunu, Meni; Ray, Vishva; Peterman, Neil; Bartel, John; Fischbein, Michael D; Venta, Kimberly; Luo, Zhengtang; Johnson, A T Charlie; Drndi?, Marija

2010-08-11

71

Tasmanian low frequency Galactic background surveys  

NASA Technical Reports Server (NTRS)

The results of LF (2-20-MHz) radio-astronomy observations obtained in Tasmania during solar-minimum winters since 1956 are briefly summarized. The low ionospheric f0F2 values (near 1 MHz) occurring in Tasmania in these periods are noted; the 2000-ft-diameter Llanherne array used for Galactic mapping at 2-20 MHz is described; the techniques employed are discussed; and sample maps are shown.

Cane, H. V.

1987-01-01

72

Electrically facilitated translocation of protein through solid nanopore  

PubMed Central

Nanopores have been proven as versatile single-molecule sensors for individual unlabeled biopolymer detection and characterization. In the present work, a relative large nanopore with a diameter of about 60 nm has been used to detect protein translocation driven by a series of applied voltages. Compared with previous studied small nanopores, a distinct profile of protein translocation through a larger nanopore has been characterized. First, a higher threshold voltage is required to drive proteins into the large nanopore. With the increase of voltages, the capture frequency of protein into the nanopore has been markedly enhanced. And the distribution of current blockage events is characterized as a function of biased voltages. Due to the large dimension of the nanopore, the adsorption and desorption phenomenon of proteins observed with a prolonged dwell time has been weakened in our work. Nevertheless, the protein can still be stretched into an unfolded state by increased electric forces at high voltages. In consideration of the high throughput of the large nanopore, a couple of proteins passing through the nanopore simultaneously occur at high voltage. As a new feature, the feasibility and specificity of a nanopore with distinct geometry have been demonstrated for sensing protein translocation, which broadly expand the application of nanopore devices. PMID:24661490

2014-01-01

73

Markovian Description of Unbiased Polymer Translocation  

E-print Network

We perform, with the help of cloud computing resources, extensive Langevin simulations which provide compelling evidence in favor of a general markovian framework for unbiased polymer translocation. Our statistical analysis consists of careful evaluations of (i) two-point correlation functions of the translocation coordinate and (ii) the empirical probabilities of complete polymer translocation (taken as a function of the initial number of monomers on a given side of the membrane). We find good agreement with predictions derived from the Markov chain approach recently addressed in the literature by the present authors.

Felipe Mondaini; L. Moriconi

2012-03-20

74

Evidence of Microbial Translocation Associated with Perturbations in T Cell and Antigen-Presenting Cell Homeostasis in Hookworm Infections  

PubMed Central

Background Microbial translocation (MT) is the process by which microbes or microbial products translocate from the intestine to the systemic circulation. MT is a common cause of systemic immune activation in HIV infection and is associated with reduced frequencies of CD4+ T cells; no data exist, however, on the role of MT in intestinal helminth infections. Methods We measured the plasma levels of MT markers, acute-phase proteins, and pro- and anti - inflammatory cytokines in individuals with or without hookworm infections. We also estimated the absolute counts of CD4+ and CD8+ T cells as well as the frequencies of memory T cell and dendritic cell subsets. Finally, we also measured the levels of all of these parameters in a subset of individuals following treatment of hookworm infection. Results Our data suggest that hookworm infection is characterized by increased levels of markers associated with MT but not acute-phase proteins nor pro-inflammatory cytokines. Hookworm infections were also associated with increased levels of the anti – inflammatory cytokine – IL-10, which was positively correlated with levels of lipopolysaccharide (LPS). In addition, MT was associated with decreased numbers of CD8+ T cells and diminished frequencies of particular dendritic cell subsets. Antihelmintic treatment of hookworm infection resulted in reversal of some of the hematologic and microbiologic alterations. Conclusions Our data provide compelling evidence for MT in a human intestinal helminth infection and its association with perturbations in the T cell and antigen-presenting cell compartments of the immune system. Our data also reveal that at least one dominant counter-regulatory mechanism i.e. increased IL-10 production might potentially protect against systemic immune activation in hookworm infections. PMID:23056659

George, Palakkal Jovvian; Anuradha, Rajamanickam; Kumar, Nathella Pavan; Kumaraswami, Vasanthapuram; Nutman, Thomas B.; Babu, Subash

2012-01-01

75

Nanoelectropulse-induced phosphatidylserine translocation.  

PubMed

Nanosecond, megavolt-per-meter, pulsed electric fields induce phosphatidylserine (PS) externalization, intracellular calcium redistribution, and apoptosis in Jurkat T-lymphoblasts, without causing immediately apparent physical damage to the cells. Intracellular calcium mobilization occurs within milliseconds of pulse exposure, and membrane phospholipid translocation is observed within minutes. Pulsed cells maintain cytoplasmic membrane integrity, blocking propidium iodide and Trypan blue. Indicators of apoptosis-caspase activation and loss of mitochondrial membrane potential-appear in nanoelectropulsed cells at later times. Although a theoretical framework has been established, specific mechanisms through which external nanosecond pulsed electric fields trigger intracellular responses in actively growing cells have not yet been experimentally characterized. This report focuses on the membrane phospholipid rearrangement that appears after ultrashort pulse exposure. We present evidence that the minimum field strength required for PS externalization in actively metabolizing Jurkat cells with 7-ns pulses produces transmembrane potentials associated with increased membrane conductance when pulse widths are microseconds rather than nanoseconds. We also show that nanoelectropulse trains delivered at repetition rates from 2 to 2000 Hz have similar effects, that nanoelectropulse-induced PS externalization does not require calcium in the external medium, and that the pulse regimens used in these experiments do not cause significant intra- or extracellular Joule heating. PMID:15189899

Vernier, P Thomas; Sun, Yinghua; Marcu, Laura; Craft, Cheryl M; Gundersen, Martin A

2004-06-01

76

Nanoelectropulse-Induced Phosphatidylserine Translocation  

PubMed Central

Nanosecond, megavolt-per-meter, pulsed electric fields induce phosphatidylserine (PS) externalization, intracellular calcium redistribution, and apoptosis in Jurkat T-lymphoblasts, without causing immediately apparent physical damage to the cells. Intracellular calcium mobilization occurs within milliseconds of pulse exposure, and membrane phospholipid translocation is observed within minutes. Pulsed cells maintain cytoplasmic membrane integrity, blocking propidium iodide and Trypan blue. Indicators of apoptosis—caspase activation and loss of mitochondrial membrane potential—appear in nanoelectropulsed cells at later times. Although a theoretical framework has been established, specific mechanisms through which external nanosecond pulsed electric fields trigger intracellular responses in actively growing cells have not yet been experimentally characterized. This report focuses on the membrane phospholipid rearrangement that appears after ultrashort pulse exposure. We present evidence that the minimum field strength required for PS externalization in actively metabolizing Jurkat cells with 7-ns pulses produces transmembrane potentials associated with increased membrane conductance when pulse widths are microseconds rather than nanoseconds. We also show that nanoelectropulse trains delivered at repetition rates from 2 to 2000 Hz have similar effects, that nanoelectropulse-induced PS externalization does not require calcium in the external medium, and that the pulse regimens used in these experiments do not cause significant intra- or extracellular Joule heating. PMID:15189899

Vernier, P. Thomas; Sun, Yinghua; Marcu, Laura; Craft, Cheryl M.; Gundersen, Martin A.

2004-01-01

77

Gene Translocations in Musculoskeletal Neoplasms  

PubMed Central

Establishing the best diagnosis for musculoskeletal neoplasms requires a multidisciplinary approach using clinical, radiographic, and histologic analyses. Despite this rigorous approach, establishing accurate diagnoses and prognoses remains challenging. Improved diagnostic methods are expected as unique molecular signals for specific bone and soft tissue cancers are identified. We performed a systematic review of the best available evidence to explore three major applications of molecular genetics that will best benefit clinical management of musculoskeletal neoplasms: diagnostic, prognostic, and therapeutic applications. The specific questions addressed in this systematic review are: (1) What sets of histopathologic sarcoma subtypes will benefit from molecular evaluation and diagnosis? (2) What molecular methods are best applied to histopathologic sarcomas to distinguish between major subtypes? (3) How do the molecular patterns discovered on genetic diagnosis affect prognosis of certain sarcomas? (4) Which sarcoma translocations can benefit from an improved response and outcome using existing and forthcoming pharmacogenetic approaches targeting molecular events? This review summarizes recent advances in molecular genetics that are available and will soon be available to clinicians to better predict outcomes and subsequently help make future treatment decisions. Level of Evidence: Level IV, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence. PMID:18566876

Krishnan, Balaji; Khanna, Gaurav

2008-01-01

78

Methylation of the nonhomologous end joining repair pathway genes does not explain the increase of translocations with aging.  

PubMed

Chromosome translocations are especially frequent in human lymphomas and leukemias but are insufficient to drive carcinogenesis. Indeed, several of the so-called tumor specific translocations have been detected in peripheral blood of healthy individuals, finding a higher frequency of some of them with aging. The inappropriate repair of DNA double strand breaks by the nonhomologous end joining (NHEJ) pathway is one of the reasons for a translocation to occur. Moreover, fidelity of this pathway has been shown to decline with age. Although the mechanism underlying this inefficacy is unknown, other repair pathways are inactivated by methylation with aging. In this study, we analyzed the implication of NHEJ genes methylation in the increase of translocations with the age. To this aim, we determined the relationship between translocations and aging in 565 Spanish healthy individuals and correlated these data with the methylation status of 11 NHEJ genes. We found higher frequency of BCL2-JH and BCR-ABL (major) translocations with aging. In addition, we detected that two NHEJ genes (LIG4 and XRCC6) presented age-dependent promoter methylation changes. However, we did not observe a correlation between the increase of translocations and methylation, indicating that other molecular mechanisms are involved in the loss of NHEJ fidelity with aging. PMID:25399073

Martín-Guerrero, Idoia; de Prado, Elena; Lopez-Lopez, Elixabet; Ardanaz, Maite; Vitoria, Juan Carlos; Parada, Luis A; García-Orad, Cristina; García-Orad, Africa

2014-12-01

79

K(+) , Na(+) , and Mg(2+) on DNA translocation in silicon nitride nanopores.  

PubMed

In this work, we report on how salt concentration and cation species affect DNA translocation in voltage-biased silicon nitride nanopores. The translocation of dsDNA in linear, circular, and supercoiled forms was measured in salt solutions containing KCl, NaCl, and MgCl(2) . As the KCl concentrations were decreased from 1 to 0.1 M, the time taken by a DNA molecule to pass through a nanopore was shorter and the frequency of the translocation in a folded configuration was reduced, suggesting an increase in DNA electrophoretic mobility and DNA persistence length. When the salt concentration was kept at 1 M, but replacing K(+) with Na(+) , longer DNA translocation times (t(d) ) were observed. The addition of low concentrations of MgCl(2) with 1.6 M KCl resulted in longer t(d) and an increased frequency of supercoiled DNA molecules in a branched form. These observations were consistent with the greater counterion charge screening ability of Na(+) and Mg(2+) as compared to K(+) . In addition, we demonstrated that dsDNA molecules indeed translocated through a ?10 nm nanopore by PCR amplification and gel electrophoresis. We also compared the dependence of DNA mobility and conformation on KCl concentration and cation species measured at single molecule level by silicon nitride nanopores with existing bulk-based experimental results and theoretical predictions. PMID:23147752

Uplinger, James; Thomas, Brian; Rollings, Ryan; Fologea, Daniel; McNabb, David; Li, Jiali

2012-12-01

80

Polymer Translocation Induced by a Bad Solvent  

E-print Network

We employ 3D Langevin Dynamics simulations to study the dynamics of polymer chains translocating through a nanopore in presence of asymmetric solvent conditions. Initially a large fraction ($>$ 50%) of the chain is placed at the \\textit{cis} side in a good solvent while the $trans$ segments are placed in a bad solvent that causes the chain to collapse and promotes translocation from the $cis$ to the $trans$ side. In particular, we study the ratcheting effect of a globule formed at the \\textit{trans} side created by the translocated segment, and how this ratchet drives the system towards faster translocation. Unlike in the case of unbiased or externally forced translocation where the mean first passage time $\\langle \\tau \\rangle $ is often characterized by algebraic scaling as a function of the chain length $N$ with a single scaling exponent $\\alpha$, and the histogram of the mean first passage time $P(\\tau/\\langle\\tau \\rangle)$ exhibits scaling, we find that scaling is not well obeyed. For relatively long chains we find $\\langle \\tau \\rangle \\sim N^\\alpha$ where $\\alpha \\approx 1$ for $\\varepsilon/k_{B}T > 1$. In this limit, we also find that translocation proceeds with a nearly constant velocity of the individual beads(monomers), which is attributed to the coiling of the globule. We provide an approximate theory assuming rotat ional motion restricted on a 2D disc to demonstrate that there is a crossover from diffusive behavior of the center of mass for short chains to a single file translocation for long chains, where the average translocation time scales linearly with the chain length $N$.

Christopher Lorscher; Tapio Ala-Nissila; Aniket Bhattacharya

2010-06-08

81

Stress and translocation: alterations in the stress physiology of translocated birds.  

PubMed

Translocation and reintroduction have become major conservation actions in attempts to create self-sustaining wild populations of threatened species. However, avian translocations have a high failure rate and causes for failure are poorly understood. While 'stress' is often cited as an important factor in translocation failure, empirical evidence of physiological stress is lacking. Here we show that experimental translocation leads to changes in the physiological stress response in chukar partridge, Alectoris chukar. We found that capture alone significantly decreased the acute glucocorticoid (corticosterone, CORT) response, but adding exposure to captivity and transport further altered the stress response axis (the hypothalamic-pituitary-adrenal axis) as evident from a decreased sensitivity of the negative feedback system. Animals that were exposed to the entire translocation procedure, in addition to the reduced acute stress response and disrupted negative feedback, had significantly lower baseline CORT concentrations and significantly reduced body weight. These data indicate that translocation alters stress physiology and that chronic stress is potentially a major factor in translocation failure. Under current practices, the restoration of threatened species through translocation may unwittingly depend on the success of chronically stressed individuals. This conclusion emphasizes the need for understanding and alleviating translocation-induced chronic stress in order to use most effectively this important conservation tool. PMID:19324794

Dickens, Molly J; Delehanty, David J; Romero, L Michael

2009-06-01

82

Stress and translocation: alterations in the stress physiology of translocated birds  

PubMed Central

Translocation and reintroduction have become major conservation actions in attempts to create self-sustaining wild populations of threatened species. However, avian translocations have a high failure rate and causes for failure are poorly understood. While ‘stress’ is often cited as an important factor in translocation failure, empirical evidence of physiological stress is lacking. Here we show that experimental translocation leads to changes in the physiological stress response in chukar partridge, Alectoris chukar. We found that capture alone significantly decreased the acute glucocorticoid (corticosterone, CORT) response, but adding exposure to captivity and transport further altered the stress response axis (the hypothalamic–pituitary–adrenal axis) as evident from a decreased sensitivity of the negative feedback system. Animals that were exposed to the entire translocation procedure, in addition to the reduced acute stress response and disrupted negative feedback, had significantly lower baseline CORT concentrations and significantly reduced body weight. These data indicate that translocation alters stress physiology and that chronic stress is potentially a major factor in translocation failure. Under current practices, the restoration of threatened species through translocation may unwittingly depend on the success of chronically stressed individuals. This conclusion emphasizes the need for understanding and alleviating translocation-induced chronic stress in order to use most effectively this important conservation tool. PMID:19324794

Dickens, Molly J.; Delehanty, David J.; Romero, L. Michael

2009-01-01

83

Translocation of imperiled species under changing climates.  

PubMed

Conservation translocation of species varies from restoring historic populations to managing the relocation of imperiled species to new locations. We review the literature in three areas--translocation, managed relocation, and conservation decision making--to inform conservation translocation under changing climates. First, climate change increases the potential for conflict over both the efficacy and the acceptability of conservation translocation. The emerging literature on managed relocation highlights this discourse. Second, conservation translocation works in concert with other strategies. The emerging literature in structured decision making provides a framework for prioritizing conservation actions--considering many possible alternatives that are evaluated based on expected benefit, risk, and social-political feasibility. Finally, the translocation literature has historically been primarily concerned with risks associated with the target species. In contrast, the managed relocation literature raises concerns about the ecological risk to the recipient ecosystem. Engaging in a structured decision process that explicitly focuses on stakeholder engagement, problem definition and specification of goals from the outset will allow creative solutions to be developed and evaluated based on their expected effectiveness. PMID:23574620

Schwartz, Mark W; Martin, Tara G

2013-05-01

84

Spatial dynamics of chromosome translocations in living cells.  

PubMed

Chromosome translocations are a hallmark of cancer cells. We have developed an experimental system to visualize the formation of translocations in living cells and apply it to characterize the spatial and dynamic properties of translocation formation. We demonstrate that translocations form within hours of the occurrence of double-strand breaks (DSBs) and that their formation is cell cycle-independent. Translocations form preferentially between prepositioned genome elements, and perturbation of key factors of the DNA repair machinery uncouples DSB pairing from translocation formation. These observations generate a spatiotemporal framework for the formation of translocations in living cells. PMID:23929981

Roukos, Vassilis; Voss, Ty C; Schmidt, Christine K; Lee, Seungtaek; Wangsa, Darawalee; Misteli, Tom

2013-08-01

85

Somatic inactivation of Tp53 in hematopoietic stem cells or thymocytes predisposes mice to thymic lymphomas with clonal translocations  

PubMed Central

TP53 protects cells from transformation by responding to stresses including aneuploidy and DNA double-strand breaks (DSBs). TP53 induces apoptosis of lymphocytes with persistent DSBs at antigen receptor loci and other genomic loci to prevent these lesions from generating oncogenic translocations. Despite this critical function of TP53, germline Tp53?/? mice succumb to immature T-cell (thymic) lymphomas that exhibit aneuploidy and lack clonal translocations. However, Tp53?/? mice occasionally develop B lineage lymphomas and Tp53 deletion in pro-B cells causes lymphomas with oncogenic immunoglobulin (Ig) locus translocations. In addition, human lymphoid cancers with somatic TP53 inactivation often harbor oncogenic IG or T-cell receptor (TCR) locus translocations. To determine whether somatic Tp53 inactivation unmasks translocations or alters the frequency of B lineage tumors in mice, we generated and analyzed mice with conditional Tp53 deletion initiating in hematopoietic stem cells (HSCs) or in lineage-committed thymocytes. Median tumor-free survival of each strain was similar to the lifespan of Tp53?/? mice. Mice with HSC deletion of Tp53 predominantly succumbed to thymic lymphomas with clonal translocations not involving Tcr loci; however, these mice occasionally developed mature B-cell lymphomas that harbored clonal Ig translocations. Deletion of Tp53 in thymocytes caused thymic lymphomas with aneuploidy and/or clonal translocations, including oncogenic Tcr locus translocations. Our data demonstrate that the developmental stage of Tp53 inactivation affects karyotypes of lymphoid malignancies in mice where somatic deletion of Tp53 initiating in thymocytes is sufficient to cause thymic lymphomas with oncogenic translocations. PMID:24036547

DeMicco, Amy; Yang-Iott, Katherine; Bassing, Craig H

2013-01-01

86

Bacterial translocation: the influence of dietary variables.  

PubMed

Transmucosal passage of bacteria in critically ill patients may lead to a significant incidence of systemic sepsis. This has attracted much clinical interest, as it has been shown that malnutrition in itself, impairs various aspects of barrier function. Bacterial translocation is increased in animal models where nutrients are given by the parenteral route, while enteral feeding reverses this. Translocation is also considerably increased in response to a non-lethal endotoxin challenge, if there is pre-existing protein energy malnutrition. Similar results have been obtained where the insult is caused by the inflammatory agent, zymosan. Dietary fibre reduces the deleterious effects of either agent on translocation, although the type of fibre is important. Bulk forming but non-fermentable fibres are more effective than easily fermentable types (for example, pectin). Glutamine was not effective in preventing elemental diet induced bacterial translocation. Thus, although fermentable fibre and glutamine have positive effects on mucosal mass, they do not affect translocation. Enteral nutrition thus seems to be superior to parenteral nutrition in maintaining the functional barrier of the gut. A clearer understanding of the physiology of these effects may lead to use of specifically modified enteral diets in the critically ill patient. PMID:8125385

Deitch, E A

1994-01-01

87

Chemical mutagenesis testing in Drosophila. I. Comparison of positive and negative control data for sex-linked recessive lethal mutations and reciprocal translocations in three laboratories  

SciTech Connect

As part of the validation phase of the Drosophila melanogaster segment of the National Toxicology Program, a comparison has been made of positive and negative controls for sex-linked recessive lethal mutations and reciprocal translocations from three laboratories. This comparison involves approximately 700,000 spontaneous recessive lethal mutation tests, 70,000 spontaneous translocation tests, and screens for genetic damage induced by N-nitrosodimethylamine and ..beta..-propiolactone. Spontaneous frequencies for lethal mutations and translocations were homogeneous in the laboratories regardless of solvent or broods sampled. Inhomogeneity was observed in induced frequencies among laboratories, but the variation was no greater than that found within a laboratory.

Woodruff, R.C.; Mason, J.M.; Valencia, R.; Zimmering, S.

1984-01-01

88

Wildlife translocation: the conservation implications of pathogen exposure and genetic heterozygosity  

Microsoft Academic Search

BACKGROUND: A key challenge for conservation biologists is to determine the most appropriate demographic and genetic management strategies for wildlife populations threatened by disease. We explored this topic by examining whether genetic background and previous pathogen exposure influenced survival of translocated animals when captive-bred and free-ranging bighorn sheep (Ovis canadensis) were used to re-establish a population that had been extirpated

Walter M Boyce; Mara E Weisenberger; M Cecilia T Penedo; Christine K Johnson

2011-01-01

89

[Bacterial translocation: gap in the shield].  

PubMed

The gastrointestinal tract is not only regarded as a system where nutrient absorption takes place, but also as a vital barrier against intraluminal pathogens entering the circulation and the maintenance of immune homeostasis. Bacterial translocation is defined as the penetration of viable bacteria or bacterial compounds from the gastrointestinal tract to extraintestinal sites. This disorder has been described in several clinical conditions. The main promoting factors for bacterial translocation have been proposed to be changes in the intestinal microflora, mucosal barrier failure and defects in host immunity. The presence of bacterial translocation has been associated with higher complications and mortality rates; therefore it should be taken into account in the therapeutic strategies of patients with predisposing factors. PMID:24534878

Rosero, Olivér; Kovács, Tibor; Onody, Péter; Harsányi, László; Szijártó, Attila

2014-02-23

90

Factors predisposing to adjacent 2 and 3:1 disjunctions: study of 161 human reciprocal translocations.  

PubMed Central

Reciprocal translocations produce imbalances by three types of disjunction which are, in decreasing frequency, adjacent 1, 3:1, and adjacent 2. Adjacent 1 disjunction produces duplication deficiencies of inverse topography to those of adjacent 2. The imbalanced chromosome segments in one of these types are balanced in the other. The disjunction 3:1 produces pure trisomies and monosomies. The following situations predispose to adjacent 2 disjunction: translocations between the long arms of two acrocentric chromosomes or between one of these and that of a No 9 chromosome; centric segments, either short or carrying a heterochromatic zone (9qh); a balanced translocation in the mother. The factors predisposing to the disjunction adjacent 2 operate by selection, or directly on the meiotic configuration. Some of them (shortness of the interstitial segment, shortness of the short arms of translocation chromosomes) act in both these ways. Their influence is probably responsible for the repetitive and exclusive character of this disjunction. The conditions for the occurrence of the 3:1 disjunctions seem less strict than those for adjacent 2, although they should be of the same nature (involvement of acrocentrics or a chromosome 9 in the translocation, maternal origin). Images PMID:395305

Jalbert, P; Sele, B

1979-01-01

91

What drives the translocation of proteins?  

PubMed Central

We propose that protein translocation across membranes is driven by biased random thermal motion. This "Brownian ratchet" mechanism depends on chemical asymmetries between the cis and trans sides of the membrane. Several mechanisms could contribute to rectifying the thermal motion of the protein, such as binding and dissociation of chaperonins to the translocating chain, chain coiling induced by pH and/or ionic gradients, glycosylation, and disulfide bond formation. This helps explain the robustness and promiscuity of these transport systems. Images PMID:1349170

Simon, S M; Peskin, C S; Oster, G F

1992-01-01

92

The Polymer Translocation and Barrier Crossing  

NASA Astrophysics Data System (ADS)

Dynamics of polymers crossing barriers is not only a basic problem in soft matter physics but also important in biological applications such as polymer transport across membranes, DNA gel electrophoresis, etc. In this paper we review our theoretical investigations on (1) polymer translocation through a narrow pore in a membrane [1-4], and (2) dynamics of a polymer surmounting a potential barrier [5-6]. The process of polymer translocation into or across biomembrane is a ubiquitous phenomenon occurring in cells [7]. Proteins are transported across a cellular membrane and endoplasmic reticulum, while RNAs are transported across a nuclear membrane after their synthesis...

Sung, Wokyung

2001-09-01

93

Hyaluronan synthase mediates dye translocation across liposomal membranes  

PubMed Central

Background Hyaluronan (HA) is made at the plasma membrane and secreted into the extracellular medium or matrix by phospolipid-dependent hyaluronan synthase (HAS), which is active as a monomer. Since the mechanism by which HA is translocated across membranes is still unresolved, we assessed the presence of an intraprotein pore within HAS by adding purified Streptococcus equisimilis HAS (SeHAS) to liposomes preloaded with the fluorophore Cascade Blue (CB). Results CB translocation (efflux) was not observed with mock-purified material from empty vector control E. coli membranes, but was induced by SeHAS, purified from membranes, in a time- and dose-dependent manner. CB efflux was eliminated or greatly reduced when purified SeHAS was first treated under conditions that inhibit enzyme activity: heating, oxidization or cysteine modification with N-ethylmaleimide. Reduced CB efflux also occurred with SeHAS K48E or K48F mutants, in which alteration of K48 within membrane domain 2 causes decreased activity and HA product size. The above results used liposomes containing bovine cardiolipin (BCL). An earlier study testing many synthetic lipids found that the best activating lipid for SeHAS is tetraoleoyl cardiolipin (TO-CL) and that, in contrast, tetramyristoyl cardiolipin (TM-CL) is an inactivating lipid (Weigel et al, J. Biol. Chem. 281, 36542, 2006). Consistent with the effects of these CL species on SeHAS activity, CB efflux was more than 2-fold greater in liposomes made with TO-CL compared to TM-CL. Conclusions The results indicate the presence of an intraprotein pore in HAS and support a model in which HA is translocated to the exterior by HAS itself. PMID:22276637

2012-01-01

94

Stat1 Nuclear Translocation by Nucleolin upon Monocyte Differentiation  

PubMed Central

Background Members of the signal transducer and activator of transcription (Stat) family of transcription factors traverse the nuclear membrane through a specialized structure, called the nuclear pore complex (NPC), which represents a selective filter for the import of proteins. Karyophilic molecules can bind directly to a subset of proteins of the NPC, collectively called nucleoporins. Alternatively, the transport is mediated via a carrier molecule belonging to the importin/karyopherin superfamily, which transmits the import into the nucleus through the NPC. Methodology/Principal Findings In this study, we provide evidence for an alternative Stat1 nuclear import mechanism, which is mediated by the shuttle protein nucleolin. We observed Stat1-nucleolin association, nuclear translocation and specific binding to the regulatory DNA element GAS. Using expression of nucleolin transgenes, we found that the nuclear localization signal (NLS) of nucleolin is responsible for Stat1 nuclear translocation. We show that this mechanism is utilized upon differentiation of myeloid cells and is specific for the differentiation step from monocytes to macrophages. Conclusions/Significance Our data add the nucleolin-Stat1 complex as a novel functional partner for the cell differentiation program, which is uniquely poised to regulate the transcription machinery via Stat1 and nuclear metabolism via nucleolin. PMID:20011528

Jerke, Uwe; Tkachuk, Sergey; Kiyan, Julia; Stepanova, Victoria; Kusch, Angelika; Hinz, Michael; Dietz, Rainer; Haller, Hermann; Fuhrman, Bianca; Dumler, Inna

2009-01-01

95

Bacterial Translocation in Adult Small Bowel Transplantation  

Microsoft Academic Search

The application of intestinal transplantation is limited by the high rate of infectious complications that can occur; the migration of enteric microorganisms to extraintestinal sites (bacterial translocation) has been suggested to be responsible for this event. We reviewed 95 intestinal biopsies performed on 28 transplanted patients to identify histologic features predictive of isolation of enteric microorganisms in extraintestinal sites within

A. Cucchetti; A. Siniscalchi; A. Bagni; A. Lauro; M. Cescon; N. Zucchini; A. Dazzi; C. Zanfi; S. Faenza; A. D. Pinna

2009-01-01

96

Safety of probiotics: translocation and infection.  

PubMed

The long history of safety has contributed to the acceptance of probiotics as a safe food adjunct. Consequently, many probiotic products and their applications have been granted GRAS (generally regarded as safe) status. However, this classification has been frequently generalized for all probiotic strains regardless of their application. Cases of probiotics from the genera Lactobacillus, Leuconostoc, Pediococcus, Enterococcus, and Bifidobacterium have been isolated from infection sites, leading to the postulation that these probiotics can translocate. Probiotic translocation is difficult to induce in healthy humans, and even if it does occur, detrimental effects are rare. Despite this, various reports have documented health-damaging effects of probiotic translocation in immunocompromised patients. Due to probiotics' high degree of safety and their morphological confusion with other pathogenic bacteria, they are often overlooked as contaminants and are least suspected as pathogens. However, the antibiotic resistance of some strains has increased the complexity of their eradication. Probiotic translocation and infection deserve further investigation and should become a facet of safety assessment so the negative effects of probiotics do not outweigh the benefits. PMID:18366533

Liong, Min-Tze

2008-04-01

97

Antigen receptor diversification and chromosome translocations  

Microsoft Academic Search

Double-stranded DNA breaks (DSBs) can result in chromosomal abnormalities, including deletions, translocations and aneuploidy, which can promote neoplastic transformation. DSBs arise accidentally during DNA replication and can be induced by environmental factors such as ultraviolet light or ionizing radiation, and they are generated during antigen receptor–diversification reactions in lymphocytes. Cellular pathways that maintain genomic integrity use sophisticated mechanisms that recognize

Mila Jankovic; André Nussenzweig; Michel C Nussenzweig

2007-01-01

98

40 CFR 798.5460 - Rodent heritable translocation assays.  

Code of Federal Regulations, 2011 CFR

...which distal segments of nonhomologous chromosomes are involved in a reciprocal exchange...cytologically for the presence of multivalent chromosome association characteristic of translocation...Translocations between non-homologous chromosomes in which at least one of the...

2011-07-01

99

40 CFR 798.5460 - Rodent heritable translocation assays.  

Code of Federal Regulations, 2013 CFR

...which distal segments of nonhomologous chromosomes are involved in a reciprocal exchange...cytologically for the presence of multivalent chromosome association characteristic of translocation...Translocations between non-homologous chromosomes in which at least one of the...

2013-07-01

100

40 CFR 798.5460 - Rodent heritable translocation assays.  

Code of Federal Regulations, 2010 CFR

...which distal segments of nonhomologous chromosomes are involved in a reciprocal exchange...cytologically for the presence of multivalent chromosome association characteristic of translocation...Translocations between non-homologous chromosomes in which at least one of the...

2010-07-01

101

40 CFR 798.5460 - Rodent heritable translocation assays.  

Code of Federal Regulations, 2012 CFR

...which distal segments of nonhomologous chromosomes are involved in a reciprocal exchange...cytologically for the presence of multivalent chromosome association characteristic of translocation...Translocations between non-homologous chromosomes in which at least one of the...

2012-07-01

102

40 CFR 798.5460 - Rodent heritable translocation assays.  

...which distal segments of nonhomologous chromosomes are involved in a reciprocal exchange...cytologically for the presence of multivalent chromosome association characteristic of translocation...Translocations between non-homologous chromosomes in which at least one of the...

2014-07-01

103

Coupling Translocation with Nucleic Acid Unwinding by NS3 Helicase  

E-print Network

Coupling Translocation with Nucleic Acid Unwinding by NS3 Helicase Jin Yu1 , Wei Cheng2 , Carlos to be on the order of 10 s-1 . The generic features of coupling single-stranded nucleic acid translocation metabolism.1­3 Like most motor proteins, helicases use the free energy from NTP hydrolysis to translocate

Oster, George

104

Geographic Translocation of Bats: Known and Potential Problems  

Microsoft Academic Search

Natural, accidental, and intentional translocation of bats, both intra- and intercontinentally, has been documented. Some bats have been translocated while incubating infectious dis- eases, including rabies or related lyssavirus infections; others have escaped confinement en route to or at their destinations, while others have been released deliberately. Known events and potential consequences of bat translocation are reviewed, including a proposed

Denny G. Constantine

2003-01-01

105

Secreted Listeria adhesion protein (Lap) influences Lap-mediated Listeria monocytogenes paracellular translocation through epithelial barrier  

PubMed Central

Background Listeria adhesion protein (Lap), an alcohol acetaldehyde dehydrogenase (lmo1634) promotes bacterial paracellular translocation through epithelial cell junctions during gastrointestinal phase of infection. Secreted Lap is critical for pathogenesis and is mediated by SecA2 system; however, if strain dependent variation in Lap secretion would affect L. monocytogenes paracellular translocation through epithelial barrier is unknown. Methods Amounts of Lap secretion were examined in clinical isolates of L. monocytogenes by cell fractionation analysis using Western blot. Quantitative reverse transcriptase PCR (qRT-PCR) was used to verify protein expression profiles. Adhesion and invasion of isolates were analyzed by in vitro Caco-2 cell culture model and paracellular translocation was determined using a trans-well model pre-seeded with Caco-2 cells. Results Western blot revealed that expression of Lap in whole cell preparation of isolates was very similar; however, cell fractionation analysis indicated variable Lap secretion among isolates. The strains showing high Lap secretion in supernatant exhibited significantly higher adhesion (3.4 - 4.8% vs 1.5 - 2.3%, P?translocation in Caco-2 cells than the low secreting isolates. In cell wall fraction, Lap level was mostly uniform for both groups, while Lap accumulated in cytosol in low secreting strains indicating that Lap distribution in cellular compartments is a strain-dependent phenomenon, which may be controlled by the protein transport system, SecA2. ?secA2 mutants showed significantly reduced paracellular translocation through epithelial barrier (0.48?±?0.01 vs 0.24?±?0.02, P?translocation through paracellular route and may serve as an indicator for pathogenic potential of an isolate. PMID:23799938

2013-01-01

106

Dynamics of polymer translocation into an anisotropic confinement  

E-print Network

Using Langevin dynamics simulations, we investigate the dynamics of a flexible polymer translocation into a confined area under a driving force through a nanopore. We choose an ellipsoidal shape for the confinement and consider the dependence of the asymmetry of the ellipsoid measured by the aspect ratio on the translocation time. Compared with an isotropic confinement (sphere), an anisotropic confinement (ellipsoid) with the same volume slows down the translocation, and the translocation time increases with increasing the aspect ratio of the ellipsoid. We further find that it takes different time for polymer translocation into the same ellipsoid through major-axis and minor-axis directions, depending on the average density of the whole chain in the ellipsoid, $\\phi$. For $\\phi$ lower than a critical value $\\phi_c$, the translocation through minor axis is faster, and vice versa. These complicated behaviors are interpreted by the degree of the confinement and anisotropic confinement induced folding of the translocated chain.

Kehong Zhang; Kaifu Luo

2012-12-05

107

Stiff filamentous virus translocations through solid-state nanopores  

NASA Astrophysics Data System (ADS)

The ionic conductance through a nanometer-sized pore in a membrane changes when a biopolymer slides through it, making nanopores sensitive to single molecules in solution. Their possible use for sequencing has motivated numerous studies on how DNA, a semi-flexible polymer, translocates nanopores. Here we study voltage-driven dynamics of the stiff filamentous virus fd with experiments and simulations to investigate the basic physics of polymer translocations. We find that the electric field distribution aligns an approaching fd with the nanopore, promoting its capture, but it also pulls fd sideways against the membrane after failed translocation attempts until thermal fluctuations reorient the virus for translocation. fd is too stiff to translocate in folded configurations. It therefore translocates linearly, exhibiting a voltage-independent mobility and obeying first-passage-time statistics. Surprisingly, lengthwise Brownian motion only partially accounts for the translocation velocity fluctuations. We also observe a voltage-dependent contribution whose origin is only partially determined.

McMullen, Angus; de Haan, Hendrick W.; Tang, Jay X.; Stein, Derek

2014-06-01

108

Translocation and encapsulation of siRNA inside carbon nanotubes  

NASA Astrophysics Data System (ADS)

We report spontaneous translocation of small interfering RNA (siRNA) inside carbon nanotubes (CNTs) of various diameters and chirality using all atom molecular dynamics simulations with explicit solvent. We use umbrella sampling method to calculate the free energy landscape of the siRNA entry and translocation event. Free energy profiles show that siRNA gains free energy while translocating inside CNT, and barrier for siRNA exit from CNT ranges from 40 to 110 kcal/mol depending on CNT chirality and salt concentration. The translocation time ? decreases with the increase of CNT diameter with a critical diameter of 24 A? for the translocation. In contrast, double strand DNA of the same sequence does not translocate inside CNT due to large free energy barrier for the translocation. This study helps in understanding the nucleic acid transport through nanopores at microscopic level and may help designing carbon nanotube based sensor for siRNA.

Mogurampelly, Santosh; Maiti, Prabal K.

2013-01-01

109

A Novel de novo Balanced Reciprocal Translocation t(18;22) Associated with Recurrent Miscarriages: A Case Report  

PubMed Central

Background Recurrent miscarriage is a major concern in the couples with reproductive problems. The chromosomal abnormalities, mainly balanced rearrangements are reported in variable phenotypes and the prevalence of them is 2-8% in such couples. Case Presentation In this study, the clinical, cytogenetic and molecular cytogenetic evaluations were performed on a couple with RM. The cytogenetic analysis of the husband revealed a balanced reciprocal translocation of t(18;22)(q21.1;q12) whereas wife had a normal karyotype of 46,XX. Further spectral karyotyping was performed to rule out the involvement of any other chromosomal aberrations present in the genome. Additional whole chromosome paint FISH (Fluorescence in situ hybridization) with paint probes 18 and 22 confirmed the translocation. Conclusion To our knowledge, this is the first report of a novel (18;22) translocation with unique breakpoints and their association with RM. The reciprocal translocations provide a good opportunity for the identification of disease associated genes. However, in recurrent miscarriages, most of them do not disrupt any gene at the breakpoint but can lead to unbalanced gametes and hence poor reproductive outcome like RM or birth of a child with malformations and intellectual disability. The translocation breakpoints might be risk factors for RM. Moreover, the impact of the balanced translocations in association with RM is discussed in this report. PMID:24918085

Dutta, Usha R.; Ponnala, Rajitha; Dalal, Ashwin

2014-01-01

110

Translocation of knotted proteins through a pore  

NASA Astrophysics Data System (ADS)

We report the results of molecular dynamics simulations of translocation of knotted proteins through pores. The protein is pulled into the pore with a constant force, which in many cases leads to the tightening of the knot. Since the radius of tightened knot is larger than that of the pore opening, the tight knot can block the pore thus preventing further translocation of the chain. Analyzing six different proteins, we show that the stuck probability increases with the applied force and that final positions of the tightened knot along the protein backbone are not random but are usually associated with sharp turns in the polypeptide chain. The combined effect of the confining geometry of the pore and the inhomogeneous character of the protein chain leads thus to the appearance of topological traps, which can immobilize the knot and lead to the jamming of the pore.

Szymczak, P.

2014-09-01

111

Translocation of Thorotrast in the body.  

PubMed

To investigate whether there is a permanent translocation of Thorotrast in the body, the liver of male Lewis rats was removed 4 weeks after injection of Thorotrast (300 microliters) and replaced by a donor liver. In half of the animals the spleen was removed as well. Measuring the 232Th content in the donor liver at different times after implantation demonstrated a permanent transport of 232Th into the surrogate organ. After 231 days a 232Th depot of about 1.1 mg was found, representing about 3% of the total body burden. The additional removal of the spleen resulted in a significantly lower transport of 232Th into the implanted liver. Histological examinations of the donated livers revealed increasing local concentration of Thorotrast granules, leading to the development of conglomerates. A comparable translocation of Thorotrast was verified in two humans who required liver transplantation more than 40 years after Thorotrast injection. PMID:8184016

Spiethoff, A; Wesch, H; Wegener, K; Hanisch, E; Kaul, A

1994-06-01

112

Translocation of coyote rabies--Florida, 1994.  

PubMed

Translocation of a rabies variant from one area to another has been identified increasingly in the United States. During November and December 1994, rabies was diagnosed in five dogs from two associated kennels in Florida; in addition, two other dogs being kept at one of the kennels died with suspected, but unconfirmed, rabies. Rabies virus recovered from the five dogs was identified as a variant not previously found in Florida but endemic in coyotes (Canis latrans) in south Texas. The suspected source of infection was translocation of infected coyotes from Texas to Florida. This report summarizes the findings of an investigation of these cases by the Alachua County Public Health Unit, the Florida Department of Health and Rehabilitative Services, and CDC. PMID:7623760

1995-08-11

113

Origin of translocation barriers for polyelectrolyte chains  

PubMed Central

For single-file translocations of a charged macromolecule through a narrow pore, the crucial step of arrival of an end at the pore suffers from free energy barriers, arising from changes in intrachain electrostatic interaction, distribution of ionic clouds and solvent molecules, and conformational entropy of the chain. All contributing factors to the barrier in the initial stage of translocation are evaluated by using the self-consistent field theory for the polyelectrolyte and the coupled Poisson–Boltzmann description for ions without radial symmetry. The barrier is found to be essentially entropic due to conformational changes. For moderate and high salt concentrations, the barriers for the polyelectrolyte chain are quantitatively equivalent to that of uncharged self-avoiding walks. Electrostatic effects are shown to increase the free energy barriers, but only slightly. The degree of ionization, electrostatic interaction strength, decreasing salt concentration, and the solvent quality all result in increases in the barrier. PMID:19929072

Kumar, Rajeev; Muthukumar, M.

2009-01-01

114

Pore formation and translocation of melittin.  

PubMed Central

Melittin, a bee venom, is a basic amphiphilic peptide, which mainly acts on the lipid matrix of membranes, lysing various cells. To elucidate the molecular mechanism, we investigated its interactions with phospholipid vesicles. The peptide formed a pore with a short lifetime in the membrane, as revealed by the release of an anionic fluorescent dye, calcein, from the liposomes. Our new double-labeling method clarified that the pore size increased with the peptide-to-lipid ratio. Upon the disintegration of the pore, a fraction of the peptides translocated across the bilayer. The pore formation was coupled with the translocation, which was proved by three fluorescence experiments recently developed by our laboratory. A novel model for the melittin pore formation was discussed in comparison with other pore-forming peptides. PMID:9251799

Matsuzaki, K; Yoneyama, S; Miyajima, K

1997-01-01

115

Polymer translocation through a gradient channel.  

PubMed

The translocation of polymer through a channel with a gradient interaction between the polymer and the channel is studied. The interaction is expressed by E = E0 + kx, where E0 is the initial potential energy at the entrance, x is the position of the monomer inside the channel, and k is the energy gradient. The mean first passage time ? is calculated by using Fokker-Planck equation for two cases (1) N > L and (2) N < L under the assumption that the diffusion rate D is a constant, here N is the polymer length and L is the length of channel. Results show that there is a minimum of ? at k = k(c) for both cases, and the value kc is dependent on E0 and driving force f. At large f, the scaling relation ? ? N is observed for long polymer chains. But the scaling relation is dependent on the energy gradient k for an unforced driving translocation. PMID:23902014

Zhang, Shuang; Wang, Chao; Sun, Li-Zhen; Li, Chao-Yang; Luo, Meng-Bo

2013-07-28

116

Translocation in the nonpolytrichaceous moss grimmia laevigata  

SciTech Connect

A superficially rhizomatous habit suggested that the moss Grimmia laevigata might function as a clonal, rhizomatous plant and translocate photoassimilates to below ground organs, even though the species is outside the order Polytrichales, which includes the only mosses known to posses sieve cells. Labelling with {sup 14}CO{sub 2} indicated that at least 10% of newly assimilated carbon was translocated out of leafy shoot portions within 26 hr. Of this carbon, approximately 75% was apparently moved into leafless, basal shoot portions and 25% into below ground stems. Infrared gas analysis of net CO{sup 2} flux was used to check that labelling gave a realistic measure of photosynthesis. Physiological integration and clonal spread may account for the unusual ability of this moss to colonize extremely xeric microsites.

Alpert, P. (Univ. of Massachusetts, Amherst (USA))

1989-10-01

117

Chromosome pairing and recombination in mice heterozygous for different translocations in chromosomes 16 and 17  

Microsoft Academic Search

In order to clarify the relationship between meiotic pairing and recombination, and electron microscopic (EM) study of synaptonemal complexes (SC) and an analysis of chiasma frequency and distribution were made in male mice singly and doubly heterozygous for Robertsonian [Rb(16.17)7Bnr] and reciprocal [T(16:17)43H] translocations and also in tertiary trisomics for the proximal region of chromosome 17. In all these genotypes

Pavel M. Borodin; Ivan P. Gorlov; Alexandr I. Agulnik; Sergei I. Agulnik; Anatoly O. Ruvinsky

1991-01-01

118

Structural insight into the protein translocation channel  

Microsoft Academic Search

A structurally conserved protein translocation channel is formed by the heterotrimeric Sec61 complex in eukaryotes, and SecY complex in archaea and bacteria. Electron microscopy studies suggest that the channel may function as an oligomeric assembly of Sec61 or SecY complexes. Remarkably, the recently determined X-ray structure of an archaeal SecY complex indicates that the pore is located at the center

William M Clemons; Jean-François Ménétret; Christopher W Akey; Tom A Rapoport

2004-01-01

119

De novo (11;13) translocation  

Microsoft Academic Search

A male infant is described with unusual facial appearance, clubfeet, and moderate hydrocephalus internus without obvious deficiency in mental and physical development. Cytogenetic studies revealed a karyotype of 45,XY-C,-D+t(C;D). A chromosome 11 and a 13 are involved in the formation of the translocation chromosome. The long arm of chromosome 13 is linearly attached to the end of the long arm

Christa Fonatsch; Sibylle D. Flatz; Angelika Stendel

1975-01-01

120

Mechanical Design of Translocating Motor Proteins  

Microsoft Academic Search

Translocating motors generate force and move along a biofilament track to achieve diverse functions including gene transcription,\\u000a translation, intracellular cargo transport, protein degradation, and muscle contraction. Advances in single molecule manipulation\\u000a experiments, structural biology, and computational analysis are making it possible to consider common mechanical design principles\\u000a of these diverse families of motors. Here, we propose a mechanical parts list

Wonmuk Hwang; Matthew J. Lang

2009-01-01

121

Iron translocation by free fatty acids.  

PubMed Central

Organic extracts of cigarette smoke and uncombusted tobacco contain substances capable of translocating iron from aqueous solutions into immiscible organic solvents. Such extracts will also effect the organic solvation of iron present in ferruginous forms of asbestos such as amosite and crocidolite (Qian and Eaton, Arch Biochem Biophys 1989, 275:280). These substances, previously detected by their iron-translocating properties, have now been purified and identified by mass spectroscopy as saturated fatty acids, predominantly stearic and palmitic acids. Organic extracts of tobacco smoke, as well as the pure fatty acids, also transfer ferrous iron into both isolated red cell membranes and intact human erythrocytes. The increased membrane iron may enhance cellular susceptibility to exogenous oxidants; erythrocyte membranes subject to fatty acid-mediated iron accumulation show elevated peroxidation of endogenous polyunsaturated fatty acids. These observations may help explain the phlogistic effects of tobacco use and suggest, in a broader context, that free fatty acids may act as physiologic and pathologic mediators of metal translocation. PMID:1750512

Qian, M. W.; Eaton, J. W.

1991-01-01

122

Translocation of Crohn's disease Escherichia coli across M-cells: contrasting effects of soluble plant fibres and emulsifiers  

PubMed Central

Background Crohn's disease is common in developed nations where the typical diet is low in fibre and high in processed food. Primary lesions overlie Peyer's patches and colonic lymphoid follicles where bacterial invasion through M-cells occurs. We have assessed the effect of soluble non-starch polysaccharide (NSP) and food emulsifiers on translocation of Escherichia coli across M-cells. Methods To assess effects of soluble plant fibres and food emulsifiers on translocation of mucosa-associated E coli isolates from Crohn's disease patients and from non-Crohn's controls, we used M-cell monolayers, generated by co-culture of Caco2-cl1 and Raji B cells, and human Peyer's patches mounted in Ussing chambers. Results E coli translocation increased across M-cells compared to parent Caco2-cl1 monocultures; 15.8-fold (IQR 6.2–32.0) for Crohn's disease E coli (N=8) and 6.7-fold (IQR 3.7–21.0) for control isolates (N=5). Electron microscopy confirmed E coli within M-cells. Plantain and broccoli NSP markedly reduced E coli translocation across M-cells at 5?mg/ml (range 45.3–82.6% inhibition, p<0.01); apple and leek NSP had no significant effect. Polysorbate-80, 0.01% vol/vol, increased E coli translocation through Caco2-cl1 monolayers 59-fold (p<0.05) and, at higher concentrations, increased translocation across M-cells. Similarly, E coli translocation across human Peyer's patches was reduced 45±7% by soluble plantain NSP (5?mg/ml) and increased 2-fold by polysorbate-80 (0.1% vol/vol). Conclusions Translocation of E coli across M-cells is reduced by soluble plant fibres, particularly plantain and broccoli, but increased by the emulsifier Polysorbate-80. These effects occur at relevant concentrations and may contribute to the impact of dietary factors on Crohn's disease pathogenesis. PMID:20813719

Roberts, Carol L; Keita, Asa V; Duncan, Sylvia H; O'Kennedy, Niamh; Soderholm, Johan D; Rhodes, Jonathan M

2010-01-01

123

Macular translocation with 360° retinotomy for management of retinal pigment epithelial tear: long-term results  

Microsoft Academic Search

BackgroundTo determine long-term functional and morphological changes after full macular translocation (FMT) with 360° retinotomy in patients with retinal pigment epithelium (RPE) tears, in light of the increasing number of reports of this complication following vascular endothelial growth factor (VEGF)-modulating therapy.MethodsWe retrospectively reviewed a consecutive series of six patients with RPE tears secondary to neovascular age-related macular degeneration who underwent

A. Polito; M. Cereda; F. Romanelli; G. Pertile

2010-01-01

124

DNA damage-induced translocation of S100A11 into the nucleus regulates cell proliferation  

PubMed Central

Background Proteins are able to react in response to distinct stress stimuli by alteration of their subcellular distribution. The stress-responsive protein S100A11 belongs to the family of multifunctional S100 proteins which have been implicated in several key biological processes. Previously, we have shown that S100A11 is directly involved in DNA repair processes at damaged chromatin in the nucleus. To gain further insight into the underlying mechanism subcellular trafficking of S100A11 in response to DNA damage was analyzed. Results We show that DNA damage induces a nucleolin-mediated translocation of S100A11 from the cytoplasm into the nucleus. This translocation is impeded by inhibition of the phosphorylation activity of PKC?. Translocation of S100A11 into the nucleus correlates with an increased cellular p21 protein level. Depletion of nucleolin by siRNA severely impairs translocation of S100A11 into the nucleus resulting in a decreased p21 protein level. Additionally, cells lacking nucleolin showed a reduced colony forming capacity. Conclusions These observations suggest that regulation of the subcellular distribution of S100A11 plays an important role in the DNA damage response and p21-mediated cell cycle control. PMID:21167017

2010-01-01

125

The invariant phenylalanine of precursor proteins discloses the importance of Omp85 for protein translocation into cyanelles  

Microsoft Academic Search

BACKGROUND: Today it is widely accepted that plastids are of cyanobacterial origin. During their evolutionary integration into the metabolic and regulatory networks of the host cell the engulfed cyanobacteria lost their independency. This process was paralleled by a massive gene transfer from symbiont to the host nucleus challenging the development of a retrograde protein translocation system to ensure plastid functionality.

Tobias Wunder; Roman Martin; Wolfgang Löffelhardt; Enrico Schleiff; Jürgen M Steiner

2007-01-01

126

Commensal microflora induce host defense and decrease bacterial translocation in burn mice through toll-like receptor 4  

Microsoft Academic Search

BACKGROUND: Major burn is associated with decreased gut barrier function and increased bacterial translocation (BT). This study is to investigate whether commensal microflora induce host defense and decrease BT in burn mice. METHODS: First, we treated Wild type (WT) mice with antibiotics in drinking water for 4 weeks to deplete gut commensal microflora. At week 3, drinking water was supplemented

Lee-Wei Chen; Wei-Jung Chang; Pei-Hsuan Chen; Ching-Mei Hsu

2010-01-01

127

Distribution and Translocation of 141Ce (III) in Horseradish  

PubMed Central

Background and Aims Rare earth elements (REEs) are used in agriculture and a large amount of them contaminate the environment and enter foods. The distribution and translocation of 141Ce (III) in horseradish was investigated in order to help understand the biochemical behaviour and toxic mechanism of REEs in plants. Method The distribution and translocation of 141Ce (III) in horseradish were investigated using autoradiography, liquid scintillation counting (LSC) and electron microscopic autoradiography (EMARG) techniques. The contents of 141Ce (III) and nutrient elements were analysed using an inductively coupled plasma-atomic emission spectrometer (ICP-AES). Results The results from autoradiography and LSC indicated that 141Ce (III) could be absorbed by horseradish and transferred from the leaf to the leaf-stalk and then to the root. The content of 141Ce (III) in different parts of horseradish was as follows: root > leaf-stalk > leaf. The uptake rates of 141Ce (III) in horseradish changed with the different organs and time. The content of 141Ce (III) in developing leaves was greater than that in mature leaves. The results from EMARG indicated that 141Ce (III) could penetrate through the cell membrane and enter the mesophyll cells, being present in both extra- and intra-cellular deposits. The contents of macronutrients in horseradish were decreased by 141Ce (III) treatment. Conclusions 141Ce (III) can be absorbed and transferred between organs of horseradish with time, and the distribution was found to be different at different growth stages. 141Ce (III) can enter the mesophyll cells via apoplast and symplast channels or via plasmodesmata. 141Ce (III) can disturb the metabolism of macronutrients in horseradish. PMID:17921527

Guo, Xiaoshan; Zhou, Qing; Lu, Tianhong; Fang, Min; Huang, Xiaohua

2007-01-01

128

Dynamics of polymer translocation into an anisotropic confinement  

E-print Network

Using Langevin dynamics simulations, we investigate the dynamics of a flexible polymer translocation into a confined area under a driving force through a nanopore. We choose an ellipsoidal shape for the confinement and consider the dependence of the asymmetry of the ellipsoid measured by the aspect ratio on the translocation time. Compared with an isotropic confinement (sphere), an anisotropic confinement (ellipsoid) with the same volume slows down the translocation, and the translocation time increases with increasing the aspect ratio of the ellipsoid. We further find that it takes different time for polymer translocation into the same ellipsoid through major-axis and minor-axis directions, depending on the average density of the whole chain in the ellipsoid, $\\phi$. For $\\phi$ lower than a critical value $\\phi_c$, the translocation through minor axis is faster, and vice versa. These complicated behaviors are interpreted by the degree of the confinement and anisotropic confinement induced folding of the tran...

Zhang, Kehong

2012-01-01

129

High potential for methodical improvements of FISH-based translocation analysis for retrospective radiation biodosimetry.  

PubMed

Due to their high stability and accumulation over time, translocations are currently the cytogenetic marker of choice for radiation dose estimation following protracted radiation overexposures or overexposures that occurred up to several decades in the past (environmental/occupational/medical exposures). In the course of this, particular intention is focused on the quantification of low doses (? 1.0 Gy) for the purpose of evaluating potential associations between different radiation-induced chromosomal aberrations and future health impairments, usually cancer. However, existing limitations of FISH-based translocation analysis give occasion to further optimize this method. In particular, the practical and technical aspects of the method offer a great scope for potential improvements considerably facilitating the performance of extensive studies. On the one hand, huge studies encompassing a considerable number of different collectives aiming at the determination of spontaneous translocation frequencies due to several already determined and potentially not yet known confounders are essential for improved individual dosimetry in the very low dose range. An accurate and reliable individual dosimetry and the methodical feasibility of extensive FISH-based studies are prerequisites to further elucidate the characteristics of radiation induced cancer; e.g., radiation and radiation quality specificity or total dose and dose rate dependencies. This paper focuses on the practical and technical limitations of FISH-based translocation analysis, in fact the tremendous workload and costs of huge approaches, and points out how this could be overcome by method optimization, namely standardizing and automating translocation scoring to allow sharing of future work and planning of more extensive studies. PMID:22951470

Beinke, Christina; Meineke, Viktor

2012-08-01

130

Genomic Hallmarks of Genes Involved in Chromosomal Translocations in Hematological Cancer  

PubMed Central

Reciprocal chromosomal translocations (RCTs) leading to the formation of fusion genes are important drivers of hematological cancers. Although the general requirements for breakage and fusion are fairly well understood, quantitative support for a general mechanism of RCT formation is still lacking. The aim of this paper is to analyze available high-throughput datasets with computational and robust statistical methods, in order to identify genomic hallmarks of translocation partner genes (TPGs). Our results show that fusion genes are generally overexpressed due to increased promoter activity of 5? TPGs and to more stable 3?-UTR regions of 3? TPGs. Furthermore, expression profiling of 5? TPGs and of interaction partners of 3? TPGs indicates that these features can help to explain tissue specificity of hematological translocations. Analysis of protein domains retained in fusion proteins shows that the co-occurrence of specific domain combinations is non-random and that distinct functional classes of fusion proteins tend to be associated with different components of the gene fusion network. This indicates that the configuration of fusion proteins plays an important role in determining which 5? and 3? TPGs will combine in specific fusion genes. It is generally accepted that chromosomal proximity in the nucleus can explain the specific pairing of 5? and 3? TPGS and the recurrence of hematological translocations. Using recently available data for chromosomal contact probabilities (Hi-C) we show that TPGs are preferentially located in early replicated regions and occupy distinct clusters in the nucleus. However, our data suggest that, in general, nuclear position of TPGs in hematological cancers explains neither TPG pairing nor clinical frequency. Taken together, our results support a model in which genomic features related to regulation of expression and replication timing determine the set of candidate genes more likely to be translocated in hematological tissues, with functional constraints being responsible for specific gene combinations. PMID:23236267

Shugay, Mikhail; Ortiz de Mendibil, Inigo; Vizmanos, Jose L.; Novo, Francisco J.

2012-01-01

131

Geographic Translocation of Bats: Known and Potential Problems  

PubMed Central

Natural, accidental, and intentional translocation of bats, both intra- and intercontinentally, has been documented. Some bats have been translocated while incubating infectious diseases, including rabies or related lyssavirus infections; others have escaped confinement en route to or at their destinations, while others have been released deliberately. Known events and potential consequences of bat translocation are reviewed, including a proposed solution to the attendant problems. PMID:12533276

2003-01-01

132

Assessing translocation outcome: Comparing behavioral and physiological aspects of translocated and resident African elephants (Loxodonta africana)  

E-print Network

and resident African elephants (Loxodonta africana) Noa Pinter-Wollman a,*, Lynne A. Isbell a,b , Lynette A African elephants (Loxodonta africana) and compared these measures to the local resident population at the release site. Adult male and female translocated elephants' death rates were higher than those

Pinter-Wollman, Noa

133

The clinical significance of the FUS-CREB3L2 translocation in low-grade fibromyxoid sarcoma  

Microsoft Academic Search

Background  Low-grade fibromyxoid sarcoma (LGFMS) is a rare soft-tissue neoplasm with a deceptively benign histological appearance. Local\\u000a recurrences and metastases can manifest many years following excision. The FUS-CREB3L2 gene translocation, which occurs commonly in LGFMS, may be detected by reverse-transcriptase polymerase chain reaction (RT-PCR)\\u000a and fluorescence in situ hybridisation (FISH). We assessed the relationship between clinical outcome and translocation test\\u000a result

Barry Rose; George S Tamvakopoulos; Kamaljit Dulay; Robin Pollock; John Skinner; Timothy Briggs; Steven Cannon

2011-01-01

134

Three Translocations Involving C- or G-group Chromosomes  

PubMed Central

Three translocations each involving C or G chromosomes are reported. A familial translocation t(Cq+; Eq?) was identified to be rcp(6;18) (q2;q1) and two malformed children were then found to have a 46,XY(or XX),?6, +der(6) constitution. One of the carrier's pregnancy in this family was monitored by amniocentesis and a fetus was identified as being a male translocation carrier (balanced). Two other translocations were identified as rcp(11;14) (q12 or 13;q32?) and t(17;22) (p12 or 13?;q11?), respectively. Images PMID:4714586

Nakagome, Yasuo; Iinuma, Kazuso; Matsui, Ichiro

1973-01-01

135

The protein translocation systems in plants - composition and variability on the example of Solanum lycopersicum  

PubMed Central

Background Protein translocation across membranes is a central process in all cells. In the past decades the molecular composition of the translocation systems in the membranes of the endoplasmic reticulum, peroxisomes, mitochondria and chloroplasts have been established based on the analysis of model organisms. Today, these results have to be transferred to other plant species. We bioinformatically determined the inventory of putative translocation factors in tomato (Solanum lycopersicum) by orthologue search and domain architecture analyses. In addition, we investigated the diversity of such systems by comparing our findings to the model organisms Saccharomyces cerevisiae, Arabidopsis thaliana and 12 other plant species. Results The literature search end up in a total of 130 translocation components in yeast and A. thaliana, which are either experimentally confirmed or homologous to experimentally confirmed factors. From our bioinformatic analysis (PGAP and OrthoMCL), we identified (co-)orthologues in plants, which in combination yielded 148 and 143 orthologues in A. thaliana and S. lycopersicum, respectively. Interestingly, we traced 82% overlap in findings from both approaches though we did not find any orthologues for 27% of the factors by either procedure. In turn, 29% of the factors displayed the presence of more than one (co-)orthologue in tomato. Moreover, our analysis revealed that the genomic composition of the translocation machineries in the bryophyte Physcomitrella patens resemble more to higher plants than to single celled green algae. The monocots (Z. mays and O. sativa) follow more or less a similar conservation pattern for encoding the translocon components. In contrast, a diverse pattern was observed in different eudicots. Conclusions The orthologue search shows in most cases a clear conservation of components of the translocation pathways/machineries. Only the Get-dependent integration of tail-anchored proteins seems to be distinct. Further, the complexity of the translocation pathway in terms of existing orthologues seems to vary among plant species. This might be the consequence of palaeoploidisation during evolution in plants; lineage specific whole genome duplications in Arabidopsis thaliana and triplications in Solanum lycopersicum. PMID:23506162

2013-01-01

136

Chromosome translocations measured by fluorescence in-situ hybridization: A promising biomarker  

SciTech Connect

A biomarker for exposure and risk assessment would be most useful if it employs an endpoint that is highly quantitative, is stable with time, and is relevant to human risk. Recent advances in chromosome staining using fluorescence in situ hybridization (FISH) facilitate fast and reliable measurement of reciprocal translocations, a kind of DNA damage linked to both prior exposure and risk. In contrast to other biomarkers available, the frequency of reciprocal translocations in individuals exposed to whole-body radiation is stable with time post exposure, has a rather small inter-individual variability, and can be measured accurately at the low levels. Here, the authors discuss results from their studies demonstrating that chromosome painting can be used to reconstruct radiation dose for workers exposed within the dose limits, for individuals exposed a long time ago, and even for those who have been diagnosed with leukemia but not yet undergone therapy.

Lucas, J.N.; Straume, T.

1995-10-01

137

Microbial Translocation in Chronic Liver Diseases  

PubMed Central

The intestinal microflora is not only involved in the digestion of nutrients, but also in local immunity, forming a barrier against pathogenic microorganisms. The derangement of the gut microflora may lead to microbial translocation, defined as the passage of viable microorganisms or bacterial products (i.e., LPS, lipopeptides) from the intestinal lumen to the mesenteric lymph nodes and other extraintestinal sites. The most recent evidence suggests that microbial translocation (MT) may occur not only in cirrhosis, but also in the early stage of several liver diseases, including alcoholic hepatopathy and nonalcoholic fatty liver disease. Different mechanisms, such as small intestinal bacterial overgrowth, increased permeability of intestinal mucosa, and impaired immunity, may favor MT. Furthermore, MT has been implicated in the pathogenesis of the complications of cirrhosis, which are a significant cause of morbidity and mortality in cirrhotic subjects. Therapeutic strategies aiming at modulating the gut microflora and reducing MT have focused on antibiotic-based options, such as selective intestinal decontamination, and nonantibiotic-based options, such as prokinetics and probiotics. In particular, probiotics may represent an attractive strategy, even though the promising results of experimental models and limited clinical studies need to be confirmed in larger randomized trials. PMID:22848224

Pinzone, Marilia Rita; Celesia, Benedetto Maurizio; Di Rosa, Michele; Cacopardo, Bruno; Nunnari, Giuseppe

2012-01-01

138

Melanotic Xp11 translocation renal cancer: report of a case with a unique intratumoral sarcoid-like reaction  

PubMed Central

Background Melanotic Xp11 translocation renal cancer is a rare tumor belonging to the family of microphthalmia-associated transcription factor (MiTF)/transcription factor E (TFE) neoplasms. This tumor family also includes alveolar soft part sarcoma, perivascular epithelioid cell neoplasms, Xp11 translocation renal cell carcinoma, and melanoma. To date, six confirmed melanotic Xp11 translocation cancers (five renal, one ovarian) have been reported in the literature. Case Report Here, we report the clinical, histologic, immunohistochemical, and molecular features of a unique melanotic Xp11 translocation renal cancer arising in a 34-year-old African-American female. Histologically, the tumor was composed of epithelioid tumor cells arranged in a nested pattern. The cells had clear to eosinophilic granular cytoplasm, vesicular nuclear chromatin, and prominent nucleoli. Multifocal intracytoplasmic deposits of granular brown melanin pigment were identified and confirmed by Fontana-Masson stain. An unusual histologic feature, not previously reported in melanotic Xp11 translocation renal cancer, was a sarcoid-like granulomatous reaction consisting of tight epithelioid granulomas with lymphocytic cuffing, numerous giant cells, and calcifications. Nuclear transcription factor E3 expression was identified by immunohistochemistry and TFE3 rearrangement was confirmed by fluorescence in situ hybridization. Additional immunohistochemical findings included immunoreactivity for HMB45, cathepsin K, and progesterone receptor; negative staining was seen with actin, desmin, cytokeratins, epithelial membrane antigen, CD10, vimentin, and PAX-8. The patient is currently free of disease, two years following initial clinicoradiologic presentation and twenty-two months following partial nephrectomy without additional therapy. Conclusion This report further expands the spectrum of morphologic and clinical findings previously described in melanotic Xp11 translocation renal cancer, a distinctive tumor showing overlapping features between Xp11 translocation renal cell carcinoma, melanoma, and perivascular epithelioid cell neoplasms. Virtual slides The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/7225796341180634 PMID:24735727

2014-01-01

139

Mineralocorticoid and glucocorticoid receptor mRNA expression in the brain of translocated chukar ( Alectoris chukar)  

Microsoft Academic Search

Although translocation is an important conservation tool in the effort to create self-sustaining wild populations of threatened species, avian translocations have a high failure rate and causes for failure are poorly understood. While “stress” is considered to play a major role in translocation failure, the physiological changes associated with chronic stress resulting from translocation have been investigated only recently. Translocation

Molly J. Dickens; Simone L. Meddle; L. Michael Romero

2011-01-01

140

Evaluation of translocation criteria: case study with trumpeter swans ( Cygnus buccinator)  

Microsoft Academic Search

Translocations are a common conservation technique; however, the feasibility and success of translocations are evaluated rarely. We translocated 57 trumpeter swans (Cygnus buccinator) from Idaho to Utah during 1996 to encourage migration to more southern wintering areas. We evaluated the feasibility and success of the translocation by studying biological and socio-political criteria prior to and during the translocation. Lack of

Katharina A. M Engelhardt; John A Kadlec; Victoria L Roy; James A Powell

2000-01-01

141

Studies of DNA Translocation Dynamics Using Asymmetrical Nanopores  

NASA Astrophysics Data System (ADS)

Despite extensive studies of DNA translocations through voltage-biased solid-state nanopores, the influence of the DNA coil on the translocation dynamics remains poorly understood. We investigated this issue experimentally by controlling the separation between the DNA coil and the nanopore. We studied lambda DNA translocations through devices comprising a 400 nm-high, 2500 nm-wide, disc-shaped cavity bounded from above by a 20 nm-thin silicon nitride membrane with a 10 nm wide nanopore in the center, and from below by at 400 nm-thick silicon nitride membrane with a 300 nm-wide opening in the center. The asymmetric nanopore-cavity structure introduced an 800 nm gap between the initial DNA coil and the nanopore when a molecule translocated from below, but no gap when it translocated from above. Translocation times were longer and the integrated charge deficit was larger for molecules translocating from below. These results are explained by the viscous drag on the DNA outside the pore, whose importance relative to the drag inside the pore we quantify. We outline a consistent model of DNA translocation speeds that depends on the initial configuration of the DNA coil, similar to the velocity fluctuation model of Lu et al.

Liu, Xu; Dipetrillo, Karri; Chan, Jason; Stein, Derek

2012-02-01

142

Microbial Translocation in the Pathogenesis of HIV Infection and AIDS  

PubMed Central

In pathogenic simian immunodeficiency virus (SIV) and human immunodeficiency virus (HIV) infections, the translocation of microbial products from the gastrointestinal (GI) tract to portal and systemic circulation has been proposed as a major driver of the chronic immune activation that is associated with disease progression. Consistently, microbial translocation is not present in nonpathogenic SIV infections of natural host species. In vivo studies demonstrated that HIV/SIV-associated microbial translocation results from a series of immunopathological events occurring at the GI mucosa: (i) early and severe mucosal CD4+ depletion, (ii) mucosal immune hyperactivation/persistent inflammation; (iii) damage to the integrity of the intestinal epithelium with enterocyte apoptosis and tight junction disruption; and (iv) subverted the gut microbiome, with a predominance of opportunistic bacteria. Direct in situ evidence of microbial translocation has been provided for SIV-infected rhesus macaques showing translocated microbial products in the intestinal lamina propria and distant sites. While the mechanisms by which microbial translocation causes immune activation remain controversial, a key pathogenic event appears to be innate immunity activation via Toll-like receptors and other pathogen recognition receptors. Accumulating clinical observations suggest that microbial translocation might affect HIV disease progression, response to therapy, and non-AIDS comorbidities. Given its detrimental effect on overall immunity, several interventions to prevent/block microbial translocation are currently under investigation as novel therapeutic agents for HIV/AIDS. PMID:23297256

Tincati, Camilla; Silvestri, Guido

2013-01-01

143

Two reciprocal translocations associated with microcephaly and retardation  

Microsoft Academic Search

The first case is reported of a karyotype containing two apparently unrelated reciprocal translocations, involving chromosomes 1, 2, 5, and 7. It is suggested that the patient's psychomotor retardation and microcephaly may be the result of the loss of a small amount of chromosomal material accompanying these translocations.

E F Bell; D Warburton

1977-01-01

144

Translocation and fidelity of Escherichia coli RNA polymerase  

PubMed Central

Exonuclease (exo) III was used as a probe of the Escherichia coli RNA polymerase (RNAP) ternary elongation complex (TEC) downstream border. In the absence of NTPs, RNAP appears to stall primarily in a post-translocated state and to return slowly to a pre-translocated state. Exo III mapping, therefore, appears inconsistent with an unrestrained thermal ratchet model for translocation, in which RNAP freely and rapidly oscillates between pre- and post-translocated positions. The forward translocation state is made more stable by lowering the pH and/or by elevating the salt concentration, indicating a probable role of protonated histidine(s) in regulating accurate NTP loading and translocation. Because the post-translocated TEC can be strongly stabilized by NTP addition, NTP analogs were ranked for their ability to preserve the post-translocation state, giving insight into RNAP fidelity. Effects of NTPs (and analogs) and analysis of chemically modified RNA 3? ends demonstrate that patterns of exo III mapping arise from intrinsic and subtle alterations at the RNAP active site, far from the site of exo III action. PMID:23863783

Nedialkov, Yuri A.; Burton, Zachary F.

2013-01-01

145

Translocation of Canada Geese branta canadensis in great Britain  

Microsoft Academic Search

In Britain, Canada Geese Branta canadensis have been translocated into new areas and\\/or areas of low abundance, principally in order to solve problems of local damage to crops or amenity grasslands and to provide new sport?shooting opportunities for wildfowling clubs. This paper, based on a compilation of the available translocation records, provides the most definitive record of the extent of

J. S. Kirby; W. G. Haines; G. E. Austin

1999-01-01

146

Strandwise translocation of a DNA glycosylase on undamaged DNA  

SciTech Connect

Base excision repair of genotoxic nucleobase lesions in the genome is critically dependent upon the ability of DNA glycosylases to locate rare sites of damage embedded in a vast excess of undamaged DNA, using only thermal energy to fuel the search process. Considerable interest surrounds the question of how DNA glycosylases translocate efficiently along DNA while maintaining their vigilance for target damaged sites. Here, we report the observation of strandwise translocation of 8-oxoguanine DNA glycosylase, MutM, along undamaged DNA. In these complexes, the protein is observed to translocate by one nucleotide on one strand while remaining untranslocated on the complementary strand. We further report that alterations of single base-pairs or a single amino acid substitution (R112A) can induce strandwise translocation. Molecular dynamics simulations confirm that MutM can translocate along DNA in a strandwise fashion. These observations reveal a previously unobserved mode of movement for a DNA-binding protein along the surface of DNA.

Qi, Yan; Nam, Kwangho; Spong, Marie C.; Banerjee, Anirban; Sung, Rou-Jia; Zhang, Michael; Karplus, Martin; Verdine, Gregory L. (Harvard)

2012-05-14

147

Translocation events in a single walled carbon nanotube.  

PubMed

Translocation of DNA oligomers through a single walled carbon nanotube was demonstrated recently. Translocation events are accompanied by giant current pulses, the origin of which remains obscure. Here, we show that introduction of a nucleotide alone, guanosine triphosphate into the input reservoir of a carbon nanotube nanofluidic also gives giant current pulses. Taken together with data on oligomer translocation, theses new results suggest that pulse width has a non-linear, power-law dependence on the number of nucleotides in a DNA molecule. We have also measured the time for the onset of DNA translocation pulses after bias reversal, finding that the time for the onset of translocation is directly proportional to the period of bias reversal. PMID:21179393

He, Jin; Liu, Hao; Pang, Pei; Cao, Di; Lindsay, Stuart

2010-11-17

148

Translocation events in a single-walled carbon nanotube  

NASA Astrophysics Data System (ADS)

Translocation of DNA oligomers through a single-walled carbon nanotube was demonstrated recently. Translocation events are accompanied by giant current pulses, the origin of which remains obscure. Here, we show that the introduction of a nucleotide, guanosine triphosphate, alone into the input reservoir of a carbon nanotube nanofluidic device also gives giant current pulses. Taken together with data on oligomer translocation, these new results suggest that the pulse width has a nonlinear, power-law dependence on the number of nucleotides in a DNA molecule. We have also measured the time for the onset of DNA translocation pulses after bias reversal, finding that the time for the onset of translocation is directly proportional to the period of the bias reversal.

He, Jin; Liu, Hao; Pang, Pei; Cao, Di; Lindsay, Stuart

2010-11-01

149

Cosmic Microwave Background Tutorials  

NSDL National Science Digital Library

Probing whether space is curved or flat, cosmologists have been searching for clues in ripples in the universe's microwave background left from the big bang. These tutorials explain the cosmic microwave background for neophytes, as well as more advanced readers.

Hu, Wayne

2003-10-10

150

Aberrant immunoglobulin class switch recombination and switch translocations in activated B cell-like diffuse large B cell lymphoma.  

PubMed

To elucidate the mechanisms underlying chromosomal translocations in diffuse large B cell lymphoma (DLBCL), we investigated the nature and extent of immunoglobulin class switch recombination (CSR) in these tumors. We used Southern blotting to detect legitimate and illegitimate CSR events in tumor samples of the activated B cell-like (ABC), germinal center B cell-like (GCB), and primary mediastinal B cell lymphoma (PMBL) subgroups of DLBCL. The frequency of legitimate CSR was lower in ABC DLBCL than in GCB DLBCL and PMBL. In contrast, ABC DLBCL had a higher frequency of internal deletions within the switch mu (Smu) region compared with GCB DLBCL and PMBL. ABC DLBCLs also had frequent deletions within Sgamma and other illegitimate switch recombinations. Sequence analysis revealed ongoing Smu deletions within ABC DLBCL tumor clones, which were accompanied by ongoing duplications and activation-induced cytidine deaminase-dependent somatic mutations. Unexpectedly, short fragments derived from multiple chromosomes were interspersed within Smu in one case. These findings suggest that ABC DLBCLs have abnormalities in the regulation of CSR that could predispose to chromosomal translocations. Accordingly, aberrant switch recombination was responsible for translocations in ABC DLBCLs involving BCL6, MYC, and a novel translocation partner, SPIB. PMID:17353367

Lenz, Georg; Nagel, Inga; Siebert, Reiner; Roschke, Anna V; Sanger, Warren; Wright, George W; Dave, Sandeep S; Tan, Bruce; Zhao, Hong; Rosenwald, Andreas; Muller-Hermelink, Hans Konrad; Gascoyne, Randy D; Campo, Elias; Jaffe, Elaine S; Smeland, Erlend B; Fisher, Richard I; Kuehl, W Michael; Chan, Wing C; Staudt, Louis M

2007-03-19

151

Building Background Knowledge  

ERIC Educational Resources Information Center

This article make a case for the importance of background knowledge in children's comprehension. It suggests that differences in background knowledge may account for differences in understanding text for low- and middle-income children. It then describes strategies for building background knowledge in the age of common core standards.

Neuman, Susan B.; Kaefer, Tanya; Pinkham, Ashley

2014-01-01

152

Micro-Evolution in Grasshoppers Mediated by Polymorphic Robertsonian Translocations  

PubMed Central

This review focuses on grasshoppers that are polymorphic for Robertsonian translocations because in these organisms the clarity of meiotic figures allows the study of both chiasma distribution and the orientation of trivalents and multivalents in metaphase I. Only five species of such grasshoppers were found in the literature, and all of them were from the New World: Oedaleonotus enigma (Scudder) (Orthoptera: Acrididae), Leptysma argentina Bruner, Dichroplus pratensis Bruner, Sinipta dalmani Stål, and Cornops aquaticum Bruner. A general feature of these species (except O. enigma) is that fusion carriers suffer a marked reduction of proximal and interstitial (with respect to the centromere) chiasma frequency; this fact, along with the reduction in the number of linkage groups with the consequent loss of independent segregation, produces a marked decrease of recombination in fusion carriers. This reduction in recombination has led to the conclusion that Robertsonian polymorphic grasshopper species share some properties with inversion polymorphic species of Drosophila, such as the central-marginal pattern (marginal populations are monomorphic, central populations are highly polymorphic). This pattern might be present in D. pratensis, which is certainly the most complex Robertsonian polymorphism system in the present study. However, L. argentina and C. aquaticum do not display this pattern. This issue is open to further research. Since C. aquaticum is soon to be released in South Africa as a biological control, the latitudinal pattern found in South America may repeat there. This experiment's outcome is open and deserves to be followed. PMID:23909914

Colombo, Pablo C.

2013-01-01

153

Complex chromosomal translocations in the Philadelphia chromosome leukemias. Serial translocations or a concerted genomic rearrangement?  

PubMed

Joining of the BCR and ABL genes is an essential feature of the group of human leukemias characterized by the Philadelphia chromosome and there is recent evidence that the human BCR-ABL fusion gene induces leukemia in experimental animals. Joining of these two genes is the result of cytogenetic translocation, usually the t(9;22)(q34;q11), but sometimes of more complex translocations involving one or more chromosomes in addition to chromosomes 9 and 22. The leukemic cells of some patients carry the BCR-ABL fusion gene but have an apparently normal karyotype. Recent studies show that these cells conceal complex chromosome rearrangements. Because the BCR-ABL fusion gene appears to be the result of cytogenetic rearrangement in all cases of these leukemias, the causes and mechanism of chromosome rearrangement will be relevant to the development of leukemia in man. We examine mechanisms of chromosome rearrangement and propose that both simple and complex chromosome translocations result from a single, though sometimes complex, interchange event. PMID:1756491

Fitzgerald, P H; Morris, C M

1991-12-01

154

Gravitational wave background from coalescing compact stars in eccentric orbits  

Microsoft Academic Search

Gravitational wave background produced by a stationary coalescing population of binary neutron stars in the Galaxy is calculated. This background is found to constitute a confusion limit within the LISA frequency band up to a limiting frequency nulim~10-3 Hz, leaving the frequency window ~10-3-10-2 Hz open for the potential detection of cosmological stochastic GW. .

A. G. Kuranov; V. B. Ignatiev; K. A. Postnov; M. E. Prokhorov

2001-01-01

155

A DNA translocating Snf2 molecular motor: S. cerevisiae Rdh54 displays processive translocation and can extrude DNA loops  

PubMed Central

We have used total internal reflection fluorescence microscopy (TIRFM) to investigate the characteristics of the yeast homologous recombination factor Rdh54 on DNA. Our results demonstrate translocation of Rdh54 on DNA and extrusion of DNA loops by Rdh54 in an ATP hydrolysis-dependent manner. The translocating Rdh54 was highly processive and displayed a variety of different behaviors, including variations in translocation rate and distance, pauses, and reversals. We provide evidence that The DNA loops generated encompass an average of six kilobases and Rdh54 often abruptly releases the extruded DNA. Rdh54 forms a multimeric complex which we speculate has at least two functionally distinct DNA-binding sites, one of which enables translocation while the other remains anchored to another DNA locale. Our work, together with other recent studies, suggests that translocation-coupled DNA loop extrusion is a common mechanistic feature among the Snf2-family of chromatin-remodeling proteins. PMID:17467735

Prasad, Tekkatte Krishnamurthy; Robertson, Ragan B.; Visnapuu, Mari-Liis; Chi, Peter; Sung, Patrick; Greene, Eric C.

2009-01-01

156

Translocation of Carbon in Powdery Mildewed Barley 1  

PubMed Central

This paper compares translocation in healthy and powdery mildew (Erysiphe graminis f. sp. hordei, race CR3) infected barley (Hordeum vulgare, variety Manchuria). The sink-like properties of the powdery mildew infection were used to determine what effect imposing a sink in the midst of normal source tissue (mature primary leaf) had on the translocation process. The pattern of translocation was determined by monitoring the movement of 14C which was photosynthetically incorporated from 14C either by the primary or second leaf. In the healthy primary leaf of barley, 14C fixed in the tip section of the blade was preferentially translocated to the root, whereas 14C fixed in the basal section was primarily translocated to the shoot. When a sporulating powdery mildew infection was present in the mid-section of the primary leaf, 14C fixed in that section or in the acropetal healthy tip section readily accumulated in the infection area. Labeled carbon fixed in the healthy basal section was translocated into the other parts of the plant with only a small fraction moving acropetally into the infected mid-section. The 14C fixed by the second leaf was translocated to the root and younger shoot with very little entering the primary leaf. The presence of the mildew infection did not alter this pattern. PMID:16657616

Edwards, H. H.

1971-01-01

157

The archaeal Sec-dependent protein translocation pathway.  

PubMed Central

Over the past three decades, transport of proteins across cellular membranes has been studied extensively in various model systems. One of the major transport routes, the so-called Sec pathway, is conserved in all domains of life. Very little is known about this pathway in the third domain of life, archaea. The core components of the archaeal, bacterial and eucaryal Sec machinery are similar, although the archaeal components appear more closely related to their eucaryal counterparts. Interestingly, the accessory factors of the translocation machinery are similar to bacterial components, which indicates a unique hybrid nature of the archaeal translocase complex. The mechanism of protein translocation in archaea is completely unknown. Based on genomic sequencing data, the most likely system for archaeal protein translocation is similar to the eucaryal co-translational translocation pathway for protein import into the endoplasmic reticulum, in which a protein is pushed across the translocation channel by the ribosome. However, other models can also be envisaged, such as a bacterial-like system in which a protein is translocated post-translationally with the aid of a motor protein analogous to the bacterial ATPase SecA. This review discusses the different models. Furthermore, an overview is given of some of the other components that may be involved in the protein translocation process, such as those required for protein targeting, folding and post-translational modification. PMID:15306407

Bolhuis, Albert

2004-01-01

158

Forced Translocation of Polymer through Nanopore: Deterministic Model and Simulations  

NASA Astrophysics Data System (ADS)

We propose a new theoretical model of forced translocation of a polymer chain through a nanopore. We assume that DNA translocation at high fields proceeds too fast for the chain to relax, and thus the chain unravels loop by loop in an almost deterministic way. So the distribution of translocation times of a given monomer is controlled by the initial conformation of the chain (the distribution of its loops). Our model predicts the translocation time of each monomer as an explicit function of initial polymer conformation. We refer to this concept as ``fingerprinting''. The width of the translocation time distribution is determined by the loop distribution in initial conformation as well as by the thermal fluctuations of the polymer chain during the translocation process. We show that the conformational broadening ?t of translocation times of m-th monomer ?tm^1.5 is stronger than the thermal broadening ?tm^1.25 The predictions of our deterministic model were verified by extensive molecular dynamics simulations

Wang, Yanqian; Panyukov, Sergey; Liao, Qi; Rubinstein, Michael

2012-02-01

159

?-PCR, A Simple Method to Detect Translocations and Insertion/Deletion Mutations  

PubMed Central

PCR detection of chromosomal translocations and small insertion/deletion mutations is challenging when potential amplicon size varies greatly. Molecular diagnostic laboratories face such difficulties with the BCL2-IGH translocation in follicular lymphoma and with internal tandem duplication mutation of the FLT3 gene in leukemia, where breakpoints are widely distributed, mutations may be multiple, signal strength is low, and background noise is elevated. We developed a strategy, called ?-PCR, that ensures PCR specificity and identifies individual breakpoints. ?-PCR uses two forward primers (external and internal) and a reverse primer simultaneously. The internal primer functions as a probe with a defined distance ? from the external primer. For follicular lymphoma, we prepared upstream, BCL2-specific primers for potential breakpoints to pair with a common, downstream VLJH primer. Multiplexed PCR amplicons are sized by capillary electrophoresis. Each of the upstream pairs has a defined interval separating them that uniquely identifies the breakpoint. The presence of two amplicons with a defined size difference confirms validity of the rearrangement and identity of the specific breakpoint, even if signal strength is low. By testing 40 follicular lymphoma and 12 control specimens from formalin-fixed, paraffin-embedded (FFPE) blocks, we showed that multiplex ?-PCR is a simple, sensitive strategy to identify translocations with multiple breakpoints or partners. The strategy was also applied to detect minor leukemic clones with internal tandem duplication mutations and could have broader applications for other insertion/deletion and duplication mutations. PMID:21227398

Lin, Ming-Tseh; Tseng, Li-Hui; Rich, Roy G.; Hafez, Michael J.; Harada, Shuko; Murphy, Kathleen M.; Eshleman, James R.; Gocke, Christopher D.

2011-01-01

160

Titanium dioxide nanoparticle impact and translocation through ex vivo, in vivo and in vitro gut epithelia  

PubMed Central

Background TiO2 particles are commonly used as dietary supplements and may contain up to 36% of nano-sized particles (TiO2-NPs). Still impact and translocation of NPs through the gut epithelium is poorly documented. Results We show that, in vivo and ex vivo, agglomerates of TiO2-NPs cross both the regular ileum epithelium and the follicle-associated epithelium (FAE) and alter the paracellular permeability of the ileum and colon epithelia. In vitro, they accumulate in M-cells and mucus-secreting cells, much less in enterocytes. They do not cause overt cytotoxicity or apoptosis. They translocate through a model of FAE only, but induce tight junctions remodeling in the regular ileum epithelium, which is a sign of integrity alteration and suggests paracellular passage of NPs. Finally we prove that TiO2-NPs do not dissolve when sequestered up to 24 h in gut cells. Conclusions Taken together these data prove that TiO2-NPs would possibly translocate through both the regular epithelium lining the ileum and through Peyer’s patches, would induce epithelium impairment, and would persist in gut cells where they would possibly induce chronic damage. PMID:24666995

2014-01-01

161

Can hunting of translocated nuisance Canada geese reduce local conflicts?  

USGS Publications Warehouse

Resident Canada geese (Branta canadensis) nest or reside in the temperate latitudes of North America. In past years, translocation-the capture and subsequent release of geese at distant locations-has been used to establish resident goose populations and to reduce nuisance problems. However, with new special hunting seasons designed to target resident Canada geese, we can now evaluate translocation as a management tool when hunting is allowed at release sites. We selected 2 study sites, representative of urban and suburban locations with nuisance resident geese, in central and western New York, USA. In June 2003, we translocated 80 neck-banded adult geese, 14 radiomarked adult females, and 83 juveniles 150 km east and southwest from urban and suburban problem sites in western New York to state-owned Wildlife Management Areas. At these same capture sites, we used 151 neck-banded adult geese, 12 radiomarked females, and 100 juveniles as controls to compare dispersal movements and harvest vulnerability to translocated geese. All observations (n = 45) of translocated radiomarked geese were <20 km from release sites, in areas where hunting was permitted. Only 25 of 538 observations (4.6%) of radiomarked geese at control sites were in areas open to hunting. The remainder of observations occurred at nonhunting locations within 10 km of control sites. More translocated adult geese (23.8%) were harvested than control geese (6.6%; ??2 = 72.98, P = 0.0009). More translocated juvenile geese were harvested (22.9%) than juvenile controls (5.0%; ??2 = 72.30, P = 0.0005). Only 7 (8.8%) translocated adult geese returned to the original capture sites during Canada goose hunting seasons. Translocation of adult and juvenile geese in family groups may alleviate nuisance problems at conflict sites through increased harvest, reducing the number of birds returning in subsequent years.

Holevinski, R.A.; Malecki, R.A.; Curtis, P.D.

2006-01-01

162

High-throughput analysis of chromosome translocations and other genome rearrangements in epithelial cancers  

E-print Network

for therapy [1]. For example, the BCR-ABL fusion gene defines a group of leukemias and is the target of treatment with the kinase inhibitor Glivec. In stark contrast to leukemias, lymphomas and sarcomas, in which many important oncogenes have been... . Howarth KD, Blood KA, Ng BL, Beavis JC, Chua Y, Cooke SL, Raby S, Ichimura K, Collins VP, Carter NP, Edwards PA: Array painting reveals a high frequency of balanced translocations in breast cancer cell lines that break in cancer- relevant genes. Oncogene...

Newman, Scott; Edwards, Paul A W

2010-03-17

163

Slowing DNA translocation in a solid-state nanopore.  

PubMed

Reducing a DNA molecule's translocation speed in a solid-state nanopore is a key step toward rapid single molecule identification. Here we demonstrate that DNA translocation speeds can be reduced by an order of magnitude over previous results. By controlling the electrolyte temperature, salt concentration, viscosity, and the electrical bias voltage across the nanopore, we obtain a 3 base/micros translocation speed for 3 kbp double-stranded DNA in a 4-8 nm diameter silicon nitride pore. Our results also indicate that the ionic conductivity inside such a nanopore is smaller than it is in bulk. PMID:16159215

Fologea, Daniel; Uplinger, James; Thomas, Brian; McNabb, David S; Li, Jiali

2005-09-01

164

Extremely low frequency magnetic fields in residences in Germany. Distribution of measurements, comparison of two methods for assessing exposure, and predictors for the occurrence of magnetic fields above background level.  

PubMed

We examined the results of 1,835 magnetic field measurements in German residences conducted between November 1997 and September 1999. The measurements were part of an epidemiological study on the relationship between magnetic fields and childhood leukemia. We performed a fixed-location measurement of the magnetic field at 50 Hz and 16 2/3 Hz (frequency of the German railway system) over 24 h in the child's bedroom in the residence of each study participant. In addition, we conducted a second 24 h-measurement in the living room at 50 Hz, and spot measurements while walking through all rooms of the respective dwelling. Median 50 Hz magnetic fields above 0.2 muT were found to be infrequent in Germany (only 1.4% of all residences). Fields produced by high-voltage power lines (123-420 kV) were lower than expected: the median magnetic field was above 0.2 muT in only 8 (32.0%) of 25 residences located 50 m or closer to a high-voltage power line indicating that power lines in Germany are usually run well below the maximum power load. We found that magnetic fields were correlated with the type of residence and higher magnetic fields were measured in apartment buildings. There was also some evidence for a positive correlation between magnetic fields and traffic density and an inverse association between magnetic fields and family net income. The 24 h-magnetic field measurements correlated well with the spot measurements (r>0.7). However, when dichotomized with a cut-off point of 0.2 muT, there was only a poor agreement between the two measurement methods. A loss of the strength of the association after categorization was also observed when comparing the arithmetic mean and median of the same 24 h-measurement. In summary, these analyses give a valuable overview of magnetic field distributions in German residences. PMID:11200967

Schüz, J; Grigat, J P; Störmer, B; Rippin, G; Brinkmann, K; Michaelis, J

2000-12-01

165

Conductivity in an anisotropic background  

SciTech Connect

By using the gauge/gravity duality, we investigate the dual field theories of the anisotropic backgrounds, which are exact solutions of Einstein-Maxwell-dilaton theory with a Liouville potential. When we turn on the bulk gauge field fluctuation A{sub x} with a nontrivial dilaton coupling, the AC conductivity of this dual field theory is proportional to the frequency with an exponent depending on parameters of the anisotropic background. In some parameter regions, we find that this conductivity can have the negative exponent like the strange metal. In addition, we also investigate another U(1) gauge field fluctuation, which is not coupled with a dilaton field. We classify all possible conductivities of this system and find that the exponent of the conductivity is always positive.

Lee, Bum-Hoon [Department of Physics, Sogang University, Seoul 121-742 (Korea, Republic of); Center for Quantum Spacetime (CQUeST), Sogang University, Seoul 121-742 (Korea, Republic of); Nam, Siyoung [Department of Physics, Sogang University, Seoul 121-742 (Korea, Republic of); Pang, Da-Wei; Park, Chanyong [Center for Quantum Spacetime (CQUeST), Sogang University, Seoul 121-742 (Korea, Republic of)

2011-03-15

166

Effects of granulocyte-colony stimulating factor on peritoneal defense mechanisms and bacterial translocation after administration of systemic chemotherapy in rats  

PubMed Central

AIM: To investigate the effects of granulocyte-colony stimulating factor (G-CSF) on peritoneal defense mechanisms and bacterial translocation after systemic 5-Fluorouracil (5-FU) administration. METHODS: Thirty Wistar albino rats were divided into three groups; the control, 5-FU and 5-FU + G-CSF groups. We measured bactericidal activity of the peritoneal fluid, phagocytic activity of polymorphonuclear leucocytes in the peritoneal fluid, total peritoneal cell counts and cell types of peritoneal washing fluid. Bacterial translocation was quantified by mesenteric lymph node, liver and spleen tissue cultures. RESULTS: Systemic 5-FU reduced total peritoneal cell counts, neutrophils and macrophage numbers. It also altered bactericidal activity of the peritoneal fluid and phagocytic activity of polymorphonuclear leucocytes in the peritoneal fluid. 5-FU also caused significant increase in frequencies of bacterial translocation at the liver and mesenteric lymph nodes. G-CSF decreased bacterial translocation, it significantly enhanced bactericidal activity of the peritoneal fluid and phagocytic activity of polymorphonuclear leucocytes in the peritoneal fluid. It also increased total peritoneal cell counts, neutrophils and macrophage numbers. CONCLUSION: Systemic 5-FU administration caused bacterial translocation, decreased the bactericidal activity of peritoneal fluid and phagocytic activity of polymorphonuclear leucocytes in the peritoneal fluid. G-CSF increased both bactericidal activity of the peritoneal fluid and phagocytic activity of polymorphonuclear leucocytes in the peritoneal fluid, and prevented the bacterial translocation. We conclude that intraperitoneal GCSF administration protects the effects of systemic 5-FU on peritoneal defense mechanisms. PMID:17552008

Cerci, Celal; Ergin, Cagri; Eroglu, Erol; Agalar, Canan; Agalar, Fatih; Cerci, Sureyya; Bulbul, Mahmut

2007-01-01

167

Background Check Presentation  

E-print Network

·July 1, 2012 ­ The UNM Division of Human Resources engaged in an RFP process to identify a NationalBackground Check Presentation Kim Herron-Singleton, Recruitment & UNMTemps Services Manager #12 check website to include BC and FP processes and resources · New background check request e-mail box

New Mexico, University of

168

Multiscale model of platelet translocation and collision  

PubMed Central

The tethering of platelets on the injured vessel surface mediated by glycoprotein Ib? (GPIb?) - Von Willebrand factor (vWF) bonds, as well as the interaction between flowing platelets and adherent platelets, are two key events that take place immediately following blood vessel injury. This early-stage platelet deposition and accumulation triggers the initiation of hemostasis, a self-defensive mechanism to prevent the body from excessive blood loss. To understand and predict this complex process, one must integrate experimentally determined information on the mechanics and biochemical kinetics of participating receptors over very small time frames (1–1000 µs) and length scales (10–100 nm), to collective phenomena occurring over seconds and tens of microns. In the present study, a unique three dimensional multiscale computational model, platelet adhesive dynamics (PAD), was applied to elucidate the unique physics of (i) a non-spherical, disk-shaped platelet interacting and tethering onto the damaged vessel wall followed by (ii) collisional interactions between a flowing platelet with a downstream adherent platelet. By analyzing numerous simulations under different physiological conditions, we conclude that the platelet’s unique spheroid-shape provides heterogeneous, orientation-dependent translocation (rolling) behavior which enhances cell-wall interactions. We also conclude that platelet-platelet near field interactions are critical for cell-cell communication during the initiation of microthrombi. The PAD model described here helps to identify the physical factors that control the initial stages of platelet capture during this process. PMID:23853387

Wang, Weiwei; Mody, Nipa A.; King, Michael R.

2012-01-01

169

Multiscale model of platelet translocation and collision  

NASA Astrophysics Data System (ADS)

The tethering of platelets on the injured vessel surface mediated by glycoprotein Ib? (GPIb?) - Von Willebrand factor (vWF) bonds, as well as the interaction between flowing platelets and adherent platelets, are two key events that take place immediately following blood vessel injury. This early-stage platelet deposition and accumulation triggers the initiation of hemostasis, a self-defensive mechanism to prevent the body from excessive blood loss. To understand and predict this complex process, one must integrate experimentally determined information on the mechanics and biochemical kinetics of participating receptors over very small time frames (1-1000 ?s) and length scales (10-100 nm), to collective phenomena occurring over seconds and tens of microns. In the present study, a unique three dimensional multiscale computational model, Platelet Adhesive Dynamics (PAD), was applied to elucidate the unique physics of (i) a non-spherical, disk-shaped platelet interacting and tethering onto the damaged vessel wall followed by (ii) collisional interactions between a flowing platelet with a downstream adherent platelet. By analyzing numerous simulations under different physiological conditions, we conclude that the platelet's unique spheroid-shape provides heterogeneous, orientation-dependent translocation (rolling) behavior which enhances cell-wall interactions. We also conclude that platelet-platelet near field interactions are critical for cell-cell communication during the initiation of microthrombi. The PAD model described here helps to identify the physical factors that control the initial stages of platelet capture during this process.

Wang, Weiwei; Mody, Nipa A.; King, Michael R.

2013-07-01

170

Energy-dependent intracellular translocation of proparathormone.  

PubMed

We previously suggested that after synthesis, proparathormone is transferred from rough endoplasmic reticulum to the Golgi region where its conversion to parathormone occurs. We have attempted to define more closely this transfer process. In the first type of study, bovine parathyroid slices were incubated with [3H]leucine for 10 min and then radioisotope labeling was restricted by addition of a large excess of nonradioactive leucine. Under these conditions, more than 90% of the initially labeled proparathormone was converted to parathormone in 40 min. Lowered temperature in the chase period markedly inhibited the conversion. Several chemical agents were employed individually in the chase period to examine their effect on the conversion process. Antimycin A, dinitrophenol, oligomycin, and anaerobiosis (N2) inhibited the conversion, whereas sodium flouride and cycloheximide had no effect. In the second type of study, parathyroid slices were incubated with [3H]leucine for the entire incubation period. Lowered temperature and inhibitors of energy metabolism and microtubular function all lengthened the interval (lag) between the initial synthesis of [3H]parathormone. Cycloheximide, Tris, and chloroquine decreased the rates of protein synthesis and conversion, respectively, but none had any effect on the lag. We interpret the lag to represent the time of transit for proparathormone from rough endoplasmic reticulum to the Golgi region. We conclude that this transfer process is independent of the synthesis of the prohormone and its conversion to the hormone. Moreover, this translocation requires metabolic energy and appears to be mediated by microtubules. PMID:556615

Chu, L L; MacGregor, R R; Cohn, D V

1977-01-01

171

Control of Protein Function through Optochemical Translocation.  

PubMed

Controlled manipulation of proteins and their function is important in almost all biological disciplines. Here, we demonstrate control of protein activity with light. We present two different applications-light-triggered transcription and light-triggered protease cleavage-both based on the same concept of protein mislocation, followed by optochemically triggered translocation to an active cellular compartment. In our approach, we genetically encode a photocaged lysine into the nuclear localization signal (NLS) of the transcription factor SATB1. This blocks nuclear import of the protein until illumination induces caging group removal and release of the protein into the nucleus. In the first application, prepending this NLS to the transcription factor FOXO3 allows us to optochemically switch on its transcription activity. The second application uses the developed light-activated NLS to control nuclear import of TEV protease and subsequent cleavage of nuclear proteins containing TEV cleavage sites. The small size of the light-controlled NLS (only 20 amino acids) minimizes impact of its insertion on protein function and promises a general approach to a wide range of optochemical applications. Since the light-activated NLS is genetically encoded and optically triggered, it will prove useful to address a variety of problems requiring spatial and temporal control of protein function, for example, in stem-cell, developmental, and cancer biology. PMID:24933258

Engelke, Hanna; Chou, Chungjung; Uprety, Rajendra; Jess, Phillip; Deiters, Alexander

2014-10-17

172

Thermal inflation and the gravitational wave background  

SciTech Connect

We consider the impact of thermal inflation-a short, secondary period of inflation that can arise in supersymmetric scenarios-on the stochastic gravitational wave background. We show that while the primordial inflationary gravitational wave background is essentially unchanged at cosmic microwave background scales, it is massively diluted at solar system scales and would be unobservable by a Big Bang Observer (BBO) style experiment. Conversely, bubble collisions at the end of thermal inflation can generate a new stochastic background. We calculate the likely properties of the bubbles created during this phase transition, and show that the expected amplitude and frequency of this signal would fall within the BBO range.

Easther, Richard; Giblin Jr, John T [Department of Physics, Yale University, New Haven, CT 06520 (United States)] [Department of Physics, Yale University, New Haven, CT 06520 (United States); Lim, Eugene A [ISCAP and Physics Department, Columbia University, NY 10027 (United States)] [ISCAP and Physics Department, Columbia University, NY 10027 (United States); Park, Wan-Il; Stewart, Ewan D, E-mail: richard.easther@yale.edu, E-mail: john.giblin@yale.edu, E-mail: eugene.a.lim@gmail.com, E-mail: wipark@muon.kaist.ac.kr, E-mail: stewart@hep.kaist.ac.kr [Department of Physics, KAIST, Daejeon (Korea, Republic of)

2008-05-15

173

A Thermal Graviton Background from Extra Dimensions  

E-print Network

Inflationary cosmology predicts a low-amplitude graviton background across a wide range of frequencies. This Letter shows that if one or more extra dimensions exist, the graviton background may have a thermal spectrum instead, dependent on the fundamental scale of the extra dimensions. The energy density is shown to be significant enough that it can affect nucleosynthesis in a substantial way. The possibility of direct detection of a thermal graviton background using the 21-cm hydrogen line is discussed. Alternative explanations for the creation of a thermal graviton background are also examined.

E. R. Siegel; J. N. Fry

2005-03-07

174

Polypeptide translocation by the AAA+ ClpXP protease machine  

E-print Network

In the AAA+ ClpXP protease, ClpX uses repeated cycles of ATP hydrolysis to pull native proteins apart and to translocate the denatured polypeptide into ClpP for degradation. Here, we probe polypeptide features important ...

Barkow, Sarah R.

175

Polymer translocation: the first two decades and the recent diversification.  

PubMed

Probably no other field of statistical physics at the borderline of soft matter and biological physics has caused such a flurry of papers as polymer translocation since the 1994 landmark paper by Bezrukov, Vodyanoy, and Parsegian and the study of Kasianowicz in 1996. Experiments, simulations, and theoretical approaches are still contributing novel insights to date, while no universal consensus on the statistical understanding of polymer translocation has been reached. We here collect the published results, in particular, the famous-infamous debate on the scaling exponents governing the translocation process. We put these results into perspective and discuss where the field is going. In particular, we argue that the phenomenon of polymer translocation is non-universal and highly sensitive to the exact specifications of the models and experiments used towards its analysis. PMID:25301107

Palyulin, Vladimir V; Ala-Nissila, Tapio; Metzler, Ralf

2014-12-01

176

PROTOCOLS FOR SUCCESSFUL TRANSLOCATION OF PTARMIGAN CLAIT E. BRAUN1  

E-print Network

translocated within North America with most early efforts directed at Greater Prairie-Chickens (Tympanuchus cupido) and Sharp-tailed Grouse (T. phasianel- lus) (Leopold 1933, Snyder et al. 1999), and later

Sandercock, Brett K.

177

Background stratospheric aerosol layer  

SciTech Connect

Balloonborne aerosol particle counter measurements are used in studying the stratospheric sulfate layer at Laramie, Wyoming, during 1978 and 1979, a 2-year volcanically quiescent period in which the layer appears to have been in a near equilibrium background state. Subtracting the background aerosol concentration from data obtained during an earlier volcanically active period indicates that the actual decay rate of volcanic aerosol is over 30% faster than one would obtain without this correction. At background, the aerosol size distribution is found to remain remarkably constant between the tropopause and an altitude of approx.25 km, with a sudden transition to a distribution dominated by smaller particles above this altitude. The observations, in some respects, compare favorably with equilibrium one-dimensional stratospheric aerosol models and thus to some extent support the concept of relatively inert tropospheric sulfurous gases, such as carbonyl sulfide and carbon disulfide, as the main background stratospheric aerosol sulfur source. Models which incorporate sulfur chemistry are apparently not able to predict the observed variation of particle size with altitude. The 2-year background period is not long enough in itself to establish long-term trends. The eruption of Mt. St. Helens in May 1980 has considerably disrupted the background stratospheric aerosol which will probably not recover for several years. A comparison of the 1978--79 observations with Junge's original measurements made some 20 years earlier, also during a period void of volcanic perturbations, does not preclude a long-term increase in the background stratospheric aerosol level.

Hofmann, D.J.; Rosen, J.M.

1981-01-01

178

Fragility in the 14q21q translocation region  

Microsoft Academic Search

Aphidicolin (APC)-induced chromosomal breakage was analyzed for women representing three generations of a single family and carrying a Robertsonian translocation rob(14q21q). Fluorescence in situ hybridization (FISH) analysis confirmed the dicentric constitution of the derived chromosome and indicated the absence of ?-satellite signal at the translocation region. Per-individual analysis of metaphases from APC-treated peripheral blood lymphocyte cultures identified significantly nonrandom chromosomal

Stacy R. Denison; Asha S. Multani; Sen Pathak; Ira F. Greenbaum

2002-01-01

179

Driven translocation of a polymer: Fluctuations at work  

NASA Astrophysics Data System (ADS)

The impact of thermal fluctuations on the translocation dynamics of a polymer chain driven through a narrow pore has been investigated theoretically and by means of extensive molecular dynamics (MD) simulation. The theoretical consideration is based on the so-called velocity Langevin (V-Langevin) equation which determines the progress of the translocation in terms of the number of polymer segments, s(t), that have passed through the pore at time t due to a driving force f. The formalism is based only on the assumption that, due to thermal fluctuations, the translocation velocity v=?(t) is a Gaussian random process as suggested by our MD data. With this in mind we have derived the corresponding Fokker-Planck equation (FPE) which has a nonlinear drift term and diffusion term with a time-dependent diffusion coefficient D(t). Our MD simulation reveals that the driven translocation process follows a super diffusive law with a running diffusion coefficient D(t)?t? where ?<1. This finding is then used in the numerical solution of the FPE which yields an important result: For comparatively small driving forces fluctuations facilitate the translocation dynamics. As a consequence, the exponent ? which describes the scaling of the mean translocation time with the length N of the polymer, ?N? is found to diminish. Thus, taking thermal fluctuations into account, one can explain the systematic discrepancy between theoretically predicted duration of a driven translocation process, considered usually as a deterministic event, and measurements in computer simulations. In the nondriven case, f=0, the translocation is slightly subdiffusive and can be treated within the framework of fractional Brownian motion (fBm).

Dubbeldam, J. L. A.; Rostiashvili, V. G.; Milchev, A.; Vilgis, T. A.

2013-03-01

180

Translocations induced by fast neutrons and X-rays in Delia antiqua  

Microsoft Academic Search

A comparison was made using X-rays and fast neutrons for the induction of translocations in Delia antiqua. Using the same radiation dose, no difference in efficiency between the two radiation types could be observed. However, with fast neutrons many multiple translocations were induced, including a quadruple translocation involving 4 out of 5 autosomes. One male linked translocation was also induced.

A. S. Robinson; K. Heemert

1981-01-01

181

Translocating Adult Pacific Lamprey within the Columbia River Basin: State of the Science  

Microsoft Academic Search

The Pacific lamprey (Entosphenus tridentatus) is in decline in the Columbia River Basin, and translocating adult lamprey to bypass difficult migration corridors has been implemented since 2000. We describe and report results from two current translocation programs, provide context for use of translocation, and discuss potential benefits, risks, and uncertainties. Both translocation programs appear to have increased the number of

David L. Ward; Benjamin J. Clemens; David Clugston; Aaron D. Jackson; Mary L. Moser; Chris Peery; David P. Statler

2012-01-01

182

Structure and Folding of Nascent Polypeptide Chains during Protein Translocation in the Endoplasmic Reticulum*  

E-print Network

a disulfide-bonded loop domain. In COS-7 cells, mutant prolactin accumulated in the endoplasmic reticulum-nascent chain interactions in translocation across the endoplasmic reticulum membrane, the translocation of wild translocation across the mamma- lian endoplasmic reticulum (ER)1 depict translocation as a process in which

Nicchitta, Chris

183

Haploinsufficiency of activation-induced deaminase for antibody diversification and chromosome translocations both in vitro and in vivo.  

PubMed

The humoral immune response critically relies on the secondary diversification of antibodies. This diversification takes places through somatic remodelling of the antibody genes by two molecular mechanisms, Class Switch Recombination (CSR) and Somatic Hypermutation (SHM). The enzyme Activation Induced Cytidine Deaminase (AID) initiates both SHM and CSR by deaminating cytosine residues on the DNA of immunoglobulin genes. While crucial for immunity, AID-catalysed deamination is also the triggering event for the generation of lymphomagenic chromosome translocations. To address whether restricting the levels of AID expression in vivo contributes to the regulation of its function, we analysed mice harbouring a single copy of the AID gene (AID(+/-)). AID(+/-) mice express roughly 50% of normal AID levels, and display a mild hyperplasia, reminiscent of AID deficient mice and humans. Moreover, we found that AID(+/-) cells have an impaired competence for CSR and SHM, which indicates that AID gene dose is limiting for its physiologic function. We next evaluated the impact of AID reduction in AID(+/-) mice on the generation of chromosome translocations. Our results show that the frequency of AID-promoted c-myc/IgH translocations is reduced in AID(+/-) mice, both in vivo and in vitro. Therefore, AID is haploinsufficient for antibody diversification and chromosome translocations. These findings suggest that limiting the physiologic levels of AID expression can be a regulatory mechanism that ensures an optimal balance between immune proficiency and genome integrity. PMID:19079594

Sernández, Isora V; de Yébenes, Virginia G; Dorsett, Yair; Ramiro, Almudena R

2008-01-01

184

Diffuse Background Radiation  

E-print Network

A new determination of the upper limit to the cosmic diffuse background radiation, at ~110 nm, of 300 photons s-1 cm-2 sr-1 nm-1, is placed in the context of diffuse background measurements across the entire electromagnetic spectrum, including new optical, infrared, visible, and gamma-ray background measurements. The possibility that observed excess diffuse visible radiation is due to redshifted cosmological Lyman alpha recomination radiation is explored. Also, a new standard of units for the display of spectra is advocated.

Richard C. Henry

1999-03-18

185

The role of translocation in recovery of woodland caribou populations.  

PubMed

Maintenance of viable populations of many endangered species will require conservation action in perpetuity. Efforts to conserve these species are more likely to be successful if their reliance on conservation actions is assessed at the population level. Woodland caribou (Rangifer tarandus caribou) were extirpated recently from Banff National Park, Canada, and translocations of caribou to Banff and neighboring Jasper National Park are being considered. We used population viability analysis to assess the relative need for and benefits from translocation of individuals among caribou populations. We measured stochastic growth rates and the probability of quasi extinction of four populations of woodland caribou with and without translocation. We used two vital rates in our analysis: mean adult female survival and mean number of calves per breeding-age female as estimates of mean fecundity. We isolated process variance for each vital rate. Our results suggested the Tonquin caribou population in Jasper is likely to remain viable without translocation, but that translocation is probably insufficient to prevent eventual extirpation of the two other populations in Jasper. Simulated reintroductions of caribou into Banff resulted in a 53-98% probability of >8 females remaining after 20 years, which suggests translocation may be an effective recovery tool for some caribou populations. PMID:21091770

Decesare, Nicholas J; Whittington, Jesse; Hebblewhite, Mark; Robinson, Hugh; Bradley, Mark; Neufeld, Lalenia; Musiani, Marco

2011-04-01

186

Characterization of MYC translocations in multiple myeloma cell lines.  

PubMed

Translocations involving an MYC gene (c > N >L) are very late tumor progression events and provide a paradigm for secondary translocations in multiple myeloma. Using a combination of fluorescent in situ hybridization and comparative genomic hybridization arrays (aCGH), we have identified rearrangements of an MYC gene in 40 of 43 independent myeloma cell lines. A majority of MYC translocations involve an Ig locus (IgH > Iglambda > Igkappa), but the breakpoints only infrequently occur near or within switch regions or V(D)J sequences. Surprisingly, about 40% of MYC translocations do not involve an Ig locus. The MYC translocations mostly are nonreciprocal translocations or insertions, often with the involvement of three chromosomes and sometimes with associated duplication, amplification, inversion, and other associated chromosomal abnormalities. High-density aCGH analyses should facilitate the cloning of MYC breakpoints, enabling the determination of their structures and perhaps elucidating how rearrangements not involving an Ig gene cause dysregulation of an MYC gene. PMID:18647998

Dib, Amel; Gabrea, Ana; Glebov, Oleg K; Bergsagel, P Leif; Kuehl, W Michael

2008-01-01

187

Protein kinase C translocation in human blood platelets  

SciTech Connect

Protein kinase C (PKC) activity and translocation in response to the phorbol ester, phorbol 12-myristate, 13-acetate (PMA), serotonin (5-HT) and thrombin was assessed in human platelets. Stimulation with PMA and 5-HT for 10 minutes or thrombin for 1 minute elicited platelet PKC translocation from cytosol to membrane. The catecholamines, norepinephrine or epinephrine at 10 {mu}M concentrations did not induce redistribution of platelet PKC. Serotonin and the specific 5-HT{sub 2} receptor agonist, 1-(2,5-dimethoxy-4-iodophenyl)-2-amino-propane (DOI) but not the 5-HT{sub 1A} or 5-HT{sub 1B} agonists, ({plus minus}) 8-hydroxy-dipropylamino-tetralin (8-OH-DPAT) or 5-methoxy-3-3-(1,2,3,6-tetrahydro-4-pyridin) 1H-indole succinate (RU 24969) induced dose-dependent PKC translocations. Serotonin-evoked PKC translocation was blocked by selective 5-HT{sub 2} receptor antagonists, ketanserin and spiroperidol. These results suggest that, in human platelets, PMA, thrombin and 5-HT can elicit PKC translocation from cytosol to membrane. Serotonin-induced PKC translocation in platelets is mediated via 5-HT{sub 2} receptors.

Wang, Hoauyan; Friedman, E. (Medical College of Pennsylvania, Philadelphia (USA))

1990-01-01

188

Genic Heterozygosity and Variation in Permanent Translocation Heterozygotes of the OENOTHERA BIENNIS Complex  

PubMed Central

Genic heterozygosity and variation were studied in the permanent translocation heterozygotes Oenothera biennis I, Oe. biennis II, Oe. biennis III, Oe. strigosa, Oe. parviflora I, Oe. parviflora II, and in the related bivalent formers Oe. argillicola and Oe. hookeri. From variation at 20 enzyme loci, we find that translocation heterozygosity for the entire chromosome complex is accompanied by only moderate levels of genic heterozygosity: 2.8% in Oe. strigosa, 9.5% in Oe. biennis and 14.9% in Oe. parviflora. Inbred garden strains of Oe. argillicola exhibited 8% heterozygosity; neither garden nor wild strains of Oe. hookeri displayed heterozygosity and only a single allozyme genotype was found. The mean number of alleles per locus is only 1.30 in Oe. strigosa, 1.40 in Oe. biennis, and 1.55 in Oe. parviflora, compared to 1.40 in Oe. argillicola. Clearly, the ability to accumulate and/or retain heterozygosity and variability has not been accompanied by extraordinary levels of either. Clinal variation is evident at some loci in each ring-former. A given translocation complex may vary geographically in its allozymic constitution. From gene frequencies, Oe. biennis I, II, and III, Oe. strigosa and Oe. hookeri are judged to be very closely related, whereas Oe. argillicola seems quite remote; Oe. parviflora is intermediate to the two phylads. Gene frequencies also suggest that Oe. argillicola diverged from the Euoenothera progenitor about 1,000,000 years ago, whereas most of the remaining evolution in the complex has occurred within the last 150,000 years. PMID:17248680

Levy, Morris; Levin, Donald A.

1975-01-01

189

Isochromosome Yp and jumping translocation of Yq resulting in five cell lines in an infertile male: a case report and review of the literature  

PubMed Central

Background Jumping translocations are a rare type of mosaicism in which the same portion of one donor chromosome is translocated to several recipient chromosomes. Constitutional forms of jumping translocations are rare, and the 48 cases reported to date have been associated with both normal and abnormal phenotypes. Concurrence of isochromosome (i) of one arm and translocation of the other is also rare, with seven reported cases. We describe a unique case involving concurrence of i(Yp) and a jumping translocation of Yq to the telomere of chromosomes 12q and 17q, which resulted in five cell lines. Case presentation The patient, an otherwise healthy 35-year-old man, was referred for cytogenetic studies because of absolute azoospermia. He had elevated levels of follicle stimulating hormone and luteinizing hormone, consistent with abnormal spermatogenesis, and decreased levels of free testosterone and inhibin B. G-banded chromosome analysis revealed a mosaic male karyotype involving five abnormal cell lines. One of the cell lines showed loss of chromosome Y and presence of i(Yp) as the sole abnormality. Three cell lines exhibited jumping translocation: two involved 17qter, and the other involved 12qter as the recipient and Yq as the common donor chromosome. One of the cell lines with der(17) additionally showed i(Yp). The other der(17) and der(12) cell lines had a missing Y chromosome. All five cell lines were confirmed by FISH. Subtelomric FISH study demonstrated no loss of chromosome material from the recipient chromosomes at the translocation junctions. Conclusions We postulate that a postzygotic pericentromeric break of the Y chromosome led to formation of isochromosome Yp, whereas Yq formed a jumping translocation through recombination between its internal telomere repeats and telomeric repeats of recipient chromosomes. This in turn led to either pairing or an exchange at the complimentary sequences. Such translocation junctions appear to be unstable and to result in a jumping translocation. Cryptic deletion or disruption of AZF (azoospermic factor) genes at Yq11 during translocation or defective pairing of X and Y chromosomes during meiosis, with abnormal sex vesicle formation and consequent spermatogenetic arrest, might be the main cause of the azoospermia in our patient. PMID:24020961

2013-01-01

190

The Cosmic Background Radiation  

E-print Network

We summarise the current status of cosmic microwave background spectrum and anisotropy measurements, and their theoretical interpretation. This is the update of the mini-review for the 1997 web-version of the Review of Particle Properties.

George Smoot; Douglas Scott

1997-11-08

191

The GLAST Background Model  

SciTech Connect

In order to estimate the ability of the GLAST/LAT to reject unwanted background of charged particles, optimize the on-board processing, size the required telemetry and optimize the GLAST orbit, we developed a detailed model of the background particles that would affect the LAT. In addition to the well-known components of the cosmic radiation, we included splash and reentrant components of protons, electrons (e+ and e-) from 10 MeV and beyond as well as the albedo gamma rays produced by cosmic ray interactions with the atmosphere. We made estimates of the irreducible background components produced by positrons and hadrons interacting in the multilayered micrometeorite shield and spacecraft surrounding the LAT and note that because the orbital debris has increased, the shielding required and hence the background are larger than were present in EGRET. Improvements to the model are currently being made to include the east-west effect.

Ormes, J. F. [University of Denver (United States); Atwood, W. [University of California at Santa Cruz (United States); Burnett, T. [University of Washington (United States); Grove, E. [Naval Research Laboratory (United States); Longo, F. [Instituto Nazionale di Fisica Nucleare (INFN)-Pisa (Italy); McEnery, J.; Ritz, S. [NASA Goddard Space Flight Center (United States); Mizuno, T. [Hiroshima University (Japan)

2007-07-12

192

The GLAST Background Model  

SciTech Connect

In order to estimate the ability of the GLAST/LAT to reject unwanted background of charged particles, optimize the on-board processing, size the required telemetry and optimize the GLAST orbit, we developed a detailed model of the background particles that would affect the LAT. In addition to the well-known components of the cosmic radiation, we included splash and reentrant components of protons, electrons (e+ and e-) from 10 MeV and beyond as well as the albedo gamma rays produced by cosmic ray interactions with the atmosphere. We made estimates of the irreducible background components produced by positrons and hadrons interacting in the multilayered micrometeorite shield and spacecraft surrounding the LAT and note that because the orbital debris has increased, the shielding required and hence the background are larger than were present in EGRET. Improvements to the model are currently being made to include the east-west effect.

Ormes, J.F.; /Denver U.; Atwood, W.; /UC, Santa Cruz; Burnett, T.; /Washington U., Seattle; Grove, E.; /Naval Research Lab, Wash., D.C.; Longo, F.; /INFN, Pisa; McEnery, J.; /NASA, Goddard; Mizuno, T.; /Hiroshima U.; Ritz, S.; /NASA, Goddard

2007-10-17

193

Introduction 1 Background 1  

E-print Network

squirrel (Sciurus carolinensis). The grey squirrel was introduced to Britain in the late 19 th century populations in Northern Ireland. Background The red squirrel (Sciurus vulgaris) was once ubiquitous

194

Background Studies for EXIST  

NASA Technical Reports Server (NTRS)

We present results from a study of the trapped proton and electron background for several orbital inclinations and altitudes. This study includes time dependent effects. In addition we describe a 3 component cosmic background model developed at the University of Southampton, UK. The three components are cosmic diffuse gamma rays, atmospheric albedo gamma rays, and cosmic ray protons. We present examples of how this model was applied to BATSE and discuss its application to EXIST.

Wilson, Colleen A.; Pendleton, G. N.; Fishman, G. J.

2004-01-01

195

Photocontrol of STAT6 dimerization and translocation.  

PubMed

Phosphorylation of signal transducers and activators of transcription (STAT) proteins is a key step in activation of the JAK-STAT signal transduction cascade. Here we describe an approach to selectively analyze the impact of STAT6 phosphorylation on STAT dimerization, DNA binding and nuclear import by accessing six types of semisynthetic STAT6 proteins via expressed protein ligation (EPL). All STAT6 analogs carry a modified C-terminus, which comprises the key phosphorylation site (Tyr641) responsible for homodimerization via reciprocal SH2 domain binding, a fluorescence label and a hexahistidine tag. Protecting the phosphate moiety of tyrosine residue 641 by a photolabile protection (caged) group in two of the STAT6 variants allowed control over STAT6 dimerization. Using electrophoretic mobility shift assay (EMSA) techniques, comparative studies with STAT6 analogues proved the need for dimerization for the successful binding to oligonucleotides carrying the gamma-activated site (GAS) sequence. Furthermore, we demonstrated that light-induced decaging fully restored dimerization and DNA binding of STAT6. In addition to binding experiments, we focused on the influence of caged Tyr641 on nuclear import by microinjection of STAT6 into the cytoplasm of living cells. Decaging of monomers resulted in a rapid increase of the fluorescence signal inside the nucleus and a simultaneous decrease in the cytoplasm. We have established a powerful light-controllable system by EPL for analyzing STAT6 in vitro and in live cells that can be used for studying phosphorylation-dependent signal transduction as well as for setting up screening systems for inhibitors of STAT6 dimerization and translocation. PMID:20668749

Lahiri, Sunanda; Seidel, Ralf; Engelhard, Martin; Becker, Christian F W

2010-12-01

196

Expression profiling of starch metabolism-related plastidic translocator genes in rice  

Microsoft Academic Search

The genes encoding the major putative rice plastidic translocators involved in the carbon flow related to starch metabolism\\u000a were identified by exhaustive database searches. The genes identified were two for the triose phosphate\\/phosphate translocator\\u000a (TPT), five for the glucose 6-phosphate\\/phosphate translocator (GPT) including putatively non-functional ones, four for the phosphoenolpyruvate\\/phosphate translocator (PPT), three for the putative ADP-glucose translocator (or Brittle-1

Kentaro Toyota; Masahiro Tamura; Takashi Ohdan; Yasunori Nakamura

2006-01-01

197

Intermingling of Chromosome Territories in Interphase Suggests Role in Translocations and Transcription-Dependent Associations  

PubMed Central

After mitosis, mammalian chromosomes partially decondense to occupy distinct territories in the cell nucleus. Current models propose that territories are separated by an interchromatin domain, rich in soluble nuclear machinery, where only rare interchromosomal interactions can occur via extended chromatin loops. In contrast, recent evidence for chromatin mobility and high frequency of chromosome translocations are consistent with significant levels of chromosome intermingling, with important consequences for genome function and stability. Here we use a novel high-resolution in situ hybridization procedure that preserves chromatin nanostructure to show that chromosome territories intermingle significantly in the nucleus of human cells. The degree of intermingling between specific chromosome pairs in human lymphocytes correlates with the frequency of chromosome translocations in the same cell type, implying that double-strand breaks formed within areas of intermingling are more likely to participate in interchromosomal rearrangements. The presence of transcription factories in regions of intermingling and the effect of transcription impairment on the interactions between chromosomes shows that transcription-dependent interchromosomal associations shape chromosome organization in mammalian cells. These findings suggest that local chromatin conformation and gene transcription influence the extent with which chromosomes interact and affect their overall properties, with direct consequences for cell-type specific genome stability. PMID:16623600

Branco, Miguel R

2006-01-01

198

Inhibition of Intestinal Bacterial Translocation with Rifaximin Modulates Lamina propria Monocytic Cells Reactivity and Protects against Inflammation in a Rodent Model of Colitis  

Microsoft Academic Search

Background: A modification of the intestinal flora and an increased bacterial translocation is a common finding in patients with inflammatory bowel disease as well as in animal model of colitis. Rifaximin, a non-absorbable derivative of rifamycin, is an effective antibiotic that acts by inhibiting bacterial ribonucleic acid synthesis. Aims: In the present study, we investigated the effect of the administration

Stefano Fiorucci; Eleonora Distrutti; Andrea Mencarelli; Miriam Barbanti; Ernesto Palazzini; Antonio Morelli

2002-01-01

199

On Background Independence  

E-print Network

This paper concerns what Background Independence itself is (as opposed to some particular physical theory that is background independent). The notions presented mostly arose from a layer-by-layer analysis of the facets of the Problem of Time in Quantum Gravity. Part of this coincides with two relational postulates which are thus identified as classical precursors of two of the facets of the Problem of Time. These are furthemore tied to the forms of each of the GR Hamiltonian and momentum constraints. Other aspects of Background Independence include the algebraic closure of these constraints, expressing physics in terms of beables, foliation independence as implemented by refoliation invariance, the reconstruction of spacetime from space. The final picture is that Background Independence - a philosophically desirable and physically implementable feature for a theory to have - has the facets of the Problem of Time among its consequences. Thus these arise naturally and are problems to be resolved, as opposed to avoided `by making one's physics background-dependent in order not to have these problems'. This serves as a selection criterion that limits the use of a number of model arenas and physical theories.

Edward Anderson

2013-10-05

200

Distinguishing primary and secondary translocations in multiple myeloma.  

PubMed

Multiple myeloma (MM) is a malignant post-germinal center tumor of somatically-mutated, isotype-switched plasma cells that accumulate in the bone marrow. It often is preceded by a stable pre-malignant tumor called monoclonal gammopathy of undetermined significance (MGUS), which can sporadically progress to MM. Five recurrent primary translocations involving the immunoglobulin heavy chain (IgH) locus on chromosome 14q32 have been identified in MGUS and MM tumors. The five partner loci include 11q13, 6p21, 4p16, 16q23, and 20q12, with corresponding dysregulation of CYCLIN D1, CYCLIN D3, FGFR3/MMSET, c-MAF, and MAFB, respectively, by strong enhancers in the IgH locus. The five recurrent translocations, which are present in 40% of MM tumors, typically are simple reciprocal translocations, mostly having breakpoints within or near IgH switch regions but sometimes within or near VDJ or JH sequences. It is thought that these translocations are caused by aberrant IgH switch recombination, and possibly by aberrant somatic hypermutation in germinal center B cells, thus providing an early and perhaps initiating event in transformation. A MYC gene is dysregulated by complex translocations and insertions as a very late event during the progression of MM tumors. Since the IgH switch recombination and somatic hypermutation mechanism are turned off in plasma cells and plasma cell tumors, the MYC rearrangements are thought to be mediated by unknown mechanisms that contribute to structural genomic instability in all kinds of tumors. These rearrangements, which often but not always juxtapose MYC near one of the strong immunoglobulin enhancers, provide a paradigm for secondary translocations. It is hypothesized that secondary translocations not involving a MYC gene can occur at any stage of tumorigenesis, including in pre-malignant MGUS tumor cells. PMID:16829212

Gabrea, Ana; Leif Bergsagel, P; Michael Kuehl, W

2006-09-01

201

Supersymmetric heterotic string backgrounds  

E-print Network

We present the main features of the solution of the gravitino and dilatino Killing spinor equations derived in hep-th/0510176 and hep-th/0703143 which have led to the classification of geometric types of all type I backgrounds. We then apply these results to the supersymmetric backgrounds of the heterotic string. In particular, we solve the gaugino Killing spinor equation together with the other two Killing spinor equations of the theory. We also use our results to classify all supersymmetry conditions of ten-dimensional gauge theory.

Ulf Gran; George Papadopoulos; Diederik Roest

2007-06-29

202

Cosmological Gravitational Wave Backgrounds  

E-print Network

An overview is presented of possible cosmologically distant sources of gravitational wave backgrounds, especially those which might produce detectable backgrounds in the LISA band between 0.1 and 100 mHz. Examples considered here include inflation-amplified vacuum fluctuations in inflaton and graviton fields, bubble collisions in first-order phase transitions, Goldstone modes of classical self-ordering scalars, and cosmic strings and other gauge defects. Characteristic scales and basic mechanisms are reviewed and spectra are estimated for each of these sources. The unique impact of a LISA detection on fundamental physics and cosmology is discussed.

Craig J. Hogan

1998-09-28

203

Understanding publication bias in reintroduction biology by assessing translocations of New Zealand's herpetofauna.  

PubMed

The intentional translocation of animals is an important tool for species conservation and ecosystem restoration, but reported success rates are low, particularly for threatened and endangered species. Publication bias further distorts success rates because the results of successful translocations may be more likely to be published than failed translocations. We conducted the first comprehensive review of all published and unpublished translocations of herpetofauna in New Zealand to assess publication bias. Of 74 translocations of 29 species in 25 years, 35 have been reported in the published literature, and the outcomes of 12 have been published. Using a traditional definition of success, publication bias resulted in a gross overestimate of translocation success rates (41.7% and 8.1% for published and all translocations, respectively), but bias against failed translocations was minimal (8.3% and 6.8%, respectively). Publication bias against translocations with uncertain outcomes, the vast majority of projects, was also strong (50.0% and 85.1% for published and all translocations, respectively). Recent translocations were less likely to be published than older translocations. The reasons behind translocations were related to publication. A greater percentage of translocations for conservation and research were published (63.3% and 40.0%, respectively) than translocations for mitigation during land development (10.0%). Translocations conducted in collaboration with a university were more frequently published (82.7% and 24.4%, respectively). To account for some of this publication bias, we reassessed the outcome of each translocation using a standardized definition of success, which takes into consideration the species' life history and the time since release. Our standardized definition of translocation success provided a more accurate summary of success rates and allows for a more rigorous evaluation of the causes of translocation success and failure in large-scale reviews. PMID:24606604

Miller, Kimberly A; Bell, Trent P; Germano, Jennifer M

2014-08-01

204

Refinement of background environmental monitoring measurements using meteorological frequency distribution  

SciTech Connect

Since the Radiological Environmental Monitoring Program's inception in 1969, the direct radiation monitoring network around the Oyster Creek nuclear generating station has incorporated both monthly and quarterly thermoluminescent dosimetry (TLD). In 1988, the environmental controls department of GPU Nuclear decided to eliminate the monthly TLD network for scientific and economic reasons. The most obvious scientific basis on which to designate TLD stations is by meteorology. It would be the plume path that dictates off-site direct radiation contribution from the plant and not simply distance from the site. Through meteorological and statistical analysis of existing TLD results, the appropriate basis for designating TLD stations has been accomplished that will provide the most accurate and comprehensive data on environmental measurement of releases from Oyster Creek.

Schwartz, P.E. (GPU Nuclear Corp., Forked River, NJ (United States))

1991-01-01

205

Increased transperitoneal bacterial translocation in laparoscopic surgery  

Microsoft Academic Search

Background: The indications for laparoscopic surgery have expanded to include diseases possibly associated with peritonitis such as appendicitis, perforated peptic ulcers, and diverticulitis. The safety of carbon dioxide (CO 2) pneumoperitoneum in the presence of peritonitis has not been proved. Our previous investigations demonstrated increased bacteremia associated with CO 2 insufflation. In effort to clarify the relative effects of intraabdominal

M. C. Horattas; N. Haller; D. Ricchiutti

2003-01-01

206

Cosmic background radiation  

Microsoft Academic Search

We summarise the current status of cosmic microwave background spectrum and\\u000aanisotropy measurements, and their theoretical interpretation. This is the\\u000aupdate of the mini-review for the 1997 web-version of the Review of Particle\\u000aProperties.

George Smoot; Douglas Scott

2000-01-01

207

PANDEMIC INFLUENZA background briefing  

E-print Network

PANDEMIC INFLUENZA background briefing Biomedicine Forum 5 November 2008 compiled by David Evans, Dave Carr, David Lynn and Phil Green Transmission electron micrograph of Influenza A virus (Wellcome influenza!' Page 2 #12;Consequences of an influenza pandemic THE PANDEMIC THREAT DEATH If the next pandemic

Rambaut, Andrew

208

David Smith Academic background  

E-print Network

David Smith Academic background Ph.D. in Mathematics (Algebra), Université de Sherbrooke, Canada project program (I. Assem, F. Bergeron, C. Reutenauer, D. Smith) $132,000 ($44,000 per year for 3 years. Schiffler and D. Smith, Friezes, strings and cluster variables, to appear in Glasgow Mathematcal Journal. 2

209

INDIAN BACKGROUNDS Patuxent Wildlife  

E-print Network

of Sport Fisheries and Wildlife Circular 138 #12;#12;INDIAN BACKGROUNDS of the Patuxent Wildlife Research of the Interior Fish and Wildlife Service Bureau of Sport Fisheries and Wildlife Circular 138 #12; Exhibit the Indian hunted with spear and arrow to supply the necessities of life--food, clothing, and shelter

210

Local microwave background radiation  

E-print Network

An inquiry on a possible local origin for the Microwave Background Radiation is made. Thermal MBR photons are contained in a system called {\\it magnetic bottle} which is due to Earth magnetic field and solar wind particles, mostly electrons. Observational tests are anticipated.

Domingos S. L. Soares

2006-07-11

211

Criteria for minimal model of driven polymer translocation  

NASA Astrophysics Data System (ADS)

While the characteristics of the driven translocation for asymptotically long polymers are well understood, this is not the case for finite-sized polymers, which are relevant for real-world experiments and simulation studies. Most notably, the behavior of the exponent ?, which describes the scaling of the translocation time with polymer length, when the driving force fp in the pore is changed, is under debate. By Langevin dynamics simulations of regular and modified translocation models using the freely jointed-chain polymer model we find that a previously reported incomplete model, where the trans side and fluctuations were excluded, gives rise to characteristics that are in stark contradiction with those of the complete model, for which ? increases with fp. Our results suggest that contribution due to fluctuations is important. We construct a minimal model where dynamics is completely excluded to show that close alignment with a full translocation model can be achieved. Our findings set very stringent requirements for a minimal model that is supposed to describe the driven polymer translocation correctly.

Suhonen, P. M.; Kaski, K.; Linna, R. P.

2014-10-01

212

A somatic origin of homologous Robertsonian translocations and isochromosomes  

SciTech Connect

One t(14q 14q), three t(15q 15q), two t(21q21q), and two t(22q22q) nonmosaic, apparently balanced, de novo Robertsonian translocation cases were investigated with polymorphic markers to establish the origin of the translocated chromosomes. Four cases had results indicative of an isochromosome: one t(14q14q) case with mild mental retardation and maternal uniparental disomy (UPD) for chromosome 14, one t(15q15q) case with the Prader-Willi syndrome and UPD(15), a phenotypically normal carrier of t(22q22q) with maternal UPD(22), and a phenotypically normal t(21q21q) case of paternal UPD(21). All UPD cases showed complete homozygosity throughout the involved chromosome, which is supportive of a postmeiotic origin. In the remaining four cases, maternal and paternal inheritance of the involved chromosome was found, which unambiguously implies a somatic origin. One t(15q15q) female had a child with a ring chromosome 15, which was also of probable postmeiotic origin as recombination between grandparental haplotypes had occurred prior to ring formation. UPD might be expected to result from de novo Robertsonian translocations of meiotic origin; however, all de novo homologous translocation cases, so far reported, with UPD of chromosomes 14, 15, 21, or 22 have been isochromosomes. These data provide the first direct evidence that nonmosaic Robertsonian translocations, as well as isochromosomes, are commonly the result of a mitotic exchange. 75 refs., 1 fig., 4 tabs.

Robinson, W.P.; Bernasconi, F.; Schinzel, A.A. (Univ. of Zurich (Switzerland)); Basaran, S.; Yueksel-Apak, M. (Univ. of Istanbul (Turkey)); Neri, G. (Universita Cattolica, Rome (Italy)); Serville, F. (Hopital d'Enfants Pellegrin, Bordeaux (France)); Balicek, P.; Haluza, R. (Univ. Hospital of Hradeck Kralove, Hradec Kralove (Czech Republic)); Farah, L.M.S. (Escuola Paulista de Medicina, Sao Paulo (Brazil)) (and others)

1994-02-01

213

Intracellular calcium modulates the nuclear translocation of calsenilin.  

PubMed

Calsenilin, which was originally identified as a presenilin interacting protein, has since been shown to be involved in the processing of presenilin(s), the modulation of amyloid beta-peptide (Abeta) levels and apoptosis. Subsequent to its original identification, calsenilin was shown to act as a downstream regulatory element antagonist modulator (and termed DREAM), as well as to interact with and modulate A-type potassium channels (and termed KChIP3). Calsenilin is primarily a cytoplasmic protein that must translocate to the nucleus to perform its function as a transcriptional repressor. This study was designed to determine the cellular events that modulate the translocation of calsenilin from the cytoplasm to the nucleus. The nuclear translocation of calsenilin was found to be enhanced following serum deprivation. A similar effect was observed when cells were treated with pharmacological agents that directly manipulate the levels of intracellular calcium (caffeine and the calcium ionophore A23187), suggesting that the increased levels of calsenilin in the nucleus are mediated by changes in intracellular calcium. A calsenilin mutant that was incapable of binding calcium retained the ability to translocate to the nucleus. Taken together, these findings indicate that the level of intracellular calcium can modulate the nuclear translocation of calsenilin and that this process does not involve the direct binding of calcium to calsenilin. PMID:15086516

Zaidi, Nikhat F; Thomson, Emma E; Choi, Eun-Kyoung; Buxbaum, Joseph D; Wasco, Wilma

2004-05-01

214

Timing of Canopy Closure Influences Carbon Translocation and Seed Production of an Understorey Herb, Trillium apetalon (Trilliaceae)  

PubMed Central

Background and Aims The light availability on a temperate, deciduous-forest floor varies greatly, reflecting the seasonal leaf dynamics of the canopy trees. The growth and/or reproductive activity of understorey plants should be influenced by the length of the high-irradiance period from snowmelt to canopy closure. The aim of the present study was to clarify how spring-blooming species regulate the translocation of photosynthetic products to current reproduction and storage organs during a growing season in accordance with the changing light conditions. Methods Growth pattern, net photosynthetic rate, seed production, and shoot and flower production in the next year of Trillium apetalon were compared between natural and experimentally shaded conditions. Furthermore, translocation of current photosynthetic products within plants was assessed by a labelled carbon-chase experiment. Key Results During the high-irradiance period, plants showed high photosynthetic ability, in which current products were initially used for shoot growth, then reserved in the rhizome. Carbon translocation to developing fruit occurred after canopy closure, but this was very small due to low photosynthetic rates under the darker conditions. The shading treatment in the early season advanced the time of carbon translocation to fruit, but reduced seed production in the current year and flower production of the next year. Conclusions Carbon translocation to the storage organ had priority over seed production under high-irradiance conditions. A shortened bright period due to early canopy closure effectively restricts carbon assimilation, which greatly reduces subsequent reproductive output owing to low photosynthetic products for fruit development and small carbon storage for future reproduction. As populations of this species are maintained by seedling recruitment, acceleration of canopy closure timing may influence the maintenance and dynamics of populations. PMID:18056055

Ida, Takashi Y.; Kudo, Gaku

2008-01-01

215

Cosmic Microwave Background Theory J. Richard Bond  

E-print Network

Cosmic Microwave Background Theory J. Richard Bond CIAR Cosmology Program, Canadian Institute of this enterprise is described. Current band­powers in `­space are consistent with a \\DeltaT flat in frequency­ plosions as a dominant source of large scale struc­ ture. Band­powers at ` ¸ ? 100 suggest the universe

Bond, Dick

216

Probing nanoparticle translocation across the permeable endothelium in experimental atherosclerosis  

PubMed Central

Therapeutic and diagnostic nanomaterials are being intensely studied for several diseases, including cancer and atherosclerosis. However, the exact mechanism by which nanomedicines accumulate at targeted sites remains a topic of investigation, especially in the context of atherosclerotic disease. Models to accurately predict transvascular permeation of nanomedicines are needed to aid in design optimization. Here we show that an endothelialized microchip with controllable permeability can be used to probe nanoparticle translocation across an endothelial cell layer. To validate our in vitro model, we studied nanoparticle translocation in an in vivo rabbit model of atherosclerosis using a variety of preclinical and clinical imaging methods. Our results reveal that the translocation of lipid–polymer hybrid nanoparticles across the atherosclerotic endothelium is dependent on microvascular permeability. These results were mimicked with our microfluidic chip, demonstrating the potential utility of the model system. PMID:24395808

Kim, YongTae; Lobatto, Mark E.; Kawahara, Tomohiro; Lee Chung, Bomy; Mieszawska, Aneta J.; Sanchez-Gaytan, Brenda L.; Fay, Francois; Senders, Max L.; Calcagno, Claudia; Becraft, Jacob; Tun Saung, May; Gordon, Ronald E.; Stroes, Erik S. G.; Ma, Mingming; Farokhzad, Omid C.; Fayad, Zahi A.; Mulder, Willem J. M.; Langer, Robert

2014-01-01

217

Uptake and translocation of hexachlorobenzene: Oilpumpkin and sunflower  

SciTech Connect

The uptake of hexachlorobenzene (HCB) and its translocation to seeds were studied with oil pumpkin and sunflower plants. Open air pot experiments were conducted with soil treated with different amounts of HCB. 14C-labelled HCB was used in solution culture experiments with young plants to investigate the distribution of HCB within the plants. During the experiments the contaminant was taken up by the root system of pumkin plant and translocated intensity to the reproductive organs. Autoradiographic pictures of crossections of stems and young fruits confirm this. Such translocation mechanism was not found in sunflower. Nevertheless it can be assumed that under field conditions the uptake of vaporized HCB from contamination soil by foliage and fruits of oil pumpkin is the main pathway of contamination.

NONE

1993-10-01

218

Resistance to glyphosate from altered herbicide translocation patterns.  

PubMed

Glyphosate-resistant weeds have evolved as a result of the intensive use of glyphosate for weed control. An alteration in the way glyphosate is translocated within the plant has been identified as a mechanism of glyphosate resistance in populations of Lolium rigidum Gaud., L. multiflorum Lam. and Conyza canadensis (L.) Cronq. In these resistant plants, glyphosate becomes concentrated in the leaves rather than being translocating throughout the plant. This type of resistance is inherited as a single dominant or semi-dominant allele. Resistance due to reduced translocation appears to be a common mechanism of resistance in L. rigidum and C. canadensis, probably because it provides a greater level of resistance than other mechanisms. This type of glyphosate resistance also appears to reduce the fitness of plants that carry it. This may influence how glyphosate resistance can be managed. PMID:18080284

Preston, Christopher; Wakelin, Angela M

2008-04-01

219

Translocation of Sugar and Tritiated Water in Squash Plants 1  

PubMed Central

When 14C-sugar and THO were simultaneously introduced through a cut side vein or flap of a squash leaf (Cucurbita melopepo, Bailey cv. torticollis) concurrent translocation of 14C-sugars, T-photosynthates and THO with parallel, almost flat, gradients was observed in the petiole for periods of 1 to 3 hr. Parallel translocation gradients were not observed when 14C was introduced as 14CO2 and T by painting a leaf with THO. Autoradiography of frozen sections to locate the tissues in which THO was moving was unsuccessful. Steam-girdling blocked the movement of 14C and T when 14C-glucose and THO were introduced simultaneously by the flap-feeding technique. If THO moved as liquid water in the phloem along with the 14C-sugars, as blockage by steam girdling suggests, then solution flow of sugar cannot be excluded as a mechanism of translocation. PMID:16656978

Trip, P.; Gorham, P. R.

1968-01-01

220

Crystallographic snapshot of cellulose synthesis and membrane translocation  

PubMed Central

Cellulose, the most abundant biological macromolecule, is an extracellular, linear polymer of glucose molecules. It represents an essential component of plant cell walls but is also found in algae and bacteria. In bacteria, cellulose production frequently correlates with the formation of biofilms, a sessile, multicellular growth form. Cellulose synthesis and transport across the inner bacterial membrane is mediated by a complex of the multi-spanning catalytic BcsA subunit and the membrane-anchored, periplasmic BcsB protein. Here we present the crystal structure of a complex of BcsA and BcsB from Rhodobacter sphaeroides containing a translocating polysaccharide. The structure of the BcsA-B translocation intermediate reveals the architecture of the cellulose synthase, demonstrates how BcsA forms a cellulose-conducting channel, and suggests a model for the coupling of cellulose synthesis and translocation in which the nascent polysaccharide is extended by one glucose molecule at a time. PMID:23222542

Morgan, Jacob L.W.; Strumillo, Joanna; Zimmer, Jochen

2012-01-01

221

Gravitational wave background from coalescing compact stars in eccentric orbits  

Microsoft Academic Search

Stochastic gravitational wave background produced by a stationary coalescing population of binary neutron stars in the Galaxy is calculated. This background is found to constitute a confusion limit within the LISA frequency band up to a limiting frequency of nulim~10-3Hz, leaving the frequency window ~10-3-10-2Hz open for the potential detection of cosmological stochastic GWs and of signals involving massive black

V. B. Ignatiev; A. G. Kuranov; K. A. Postnov; M. E. Prokhorov

2001-01-01

222

Microscopic Kinetics of DNA Translocation through Synthetic and Biological Nanopores  

NASA Astrophysics Data System (ADS)

Using highly focused electron beams, artificial pores of nanometer diameters can be manufactured in ultra-thin silicon membranes with a sub-nanometer precision. A trans-membrane voltage bias can drive DNA strands through such pores; the resulting electrical signals can be recorded. As the diameter of the pore as well as the thickness of the silicon membrane can be made to match precisely the dimensions of a DNA nucleotide, the electrical signals produced by the interaction of DNA with the pore were proposed to contain information about the DNA sequence. In order to relate the DNA sequence to the measured electrical signals we characterized DNA conformations inside the pore through molecular dynamics simulations. A typical simulated system included a patch of a silicon membrane dividing electrolyte solution into two compartments connected by the nanopore. External electrical fields induced capturing of the DNA molecules by the pore from the solution and subsequent translocation. To calibrate our methodology, we carried out MD simulations of DNA translocation through an ?-hemolysin channel suspended in a lipid bilayer. Our results suggest that the rate-limiting step for DNA translocation through narrow synthetic pores is not the actual transit of DNA, but rather the search for such initial conformation that facilitates subsequent translocation. At the same time, hydrophobic adhesion of DNA bases to the pore walls may considerably slow down or halt DNA translocation. We observed a threshold electric field for translocation of double stranded DNA through pores smaller in diameter than a DNA double helix occurring due to the overstretching transition at load forces of ˜60 pN. In narrow pores, DNA bases were observed to tilt collectively towards the 5'-end of the strand, which explains experimentally observed directionality of single stranded DNA in the transmembrane pore of ?-hemolysin.

Aksimentiev, Aleksei

2006-03-01

223

Gate effects on DNA translocation through silicon dioxide nanopore.  

PubMed

The effects of gate voltage on the translocation of DNA molecules through a nanopore are studied. A twenty-fold increase in the translocation time is observed with a positive gate voltage applied, without changing too much of the ionic current. The amplitude of the current blockage by the DNA molecules was reduced by roughly the same factor. At the same time, the number of the blocking events decreases significantly. The applied gate voltage also modulates the scatter plot of the amplitude of the current blockage against the dwell time. The observations are consistent with the recent theoretical results. PMID:22462940

Yen, Pei-chun; Wang, Chung-hsuan; Hwang, Gwo-Jen; Chou, Y C

2012-03-01

224

Gate effects on DNA translocation through silicon dioxide nanopore  

NASA Astrophysics Data System (ADS)

The effects of gate voltage on the translocation of DNA molecules through a nanopore are studied. A twenty-fold increase in the translocation time is observed with a positive gate voltage applied, without changing too much of the ionic current. The amplitude of the current blockage by the DNA molecules was reduced by roughly the same factor. At the same time, the number of the blocking events decreases significantly. The applied gate voltage also modulates the scatter plot of the amplitude of the current blockage against the dwell time. The observations are consistent with the recent theoretical results.

Yen, Pei-chun; Wang, Chung-hsuan; Hwang, Gwo-Jen; Chou, Y. C.

2012-03-01

225

Free Energy Evaluation in Polymer Translocation via Jarzynski Equality  

E-print Network

We perform, with the help of cloud computing resources, extensive Langevin simulations which provide free energy estimates for unbiased three dimensional polymer translocation. We employ the Jarzynski equality in its rigorous setting, to compute the variation of the free energy in single monomer translocation events. In our three-dimensional Langevin simulations, the excluded-volume and van der Waals interactions between beads (monomers and membrane atoms) are modeled through a repulsive Lennard-Jones (LJ) potential and consecutive monomers are subject to the Finite-Extension Nonlinear Elastic (FENE) potential. Analysing data for polymers with different lengths, the free energy profile is noted to have interesting finite size scaling properties.

Felipe Mondaini; Luca Moriconi

2014-01-31

226

Changes in gut bacterial populations and their translocation into liver and ascites in alcoholic liver cirrhotics  

PubMed Central

Background The liver is the first line of defence against continuously occurring influx of microbial-derived products and bacteria from the gut. Intestinal bacteria have been implicated in the pathogenesis of alcoholic liver cirrhosis. Escape of intestinal bacteria into the ascites is involved in the pathogenesis of spontaneous bacterial peritonitis, which is a common complication of liver cirrhosis. The association between faecal bacterial populations and alcoholic liver cirrhosis has not been resolved. Methods Relative ratios of major commensal bacterial communities (Bacteroides spp., Bifidobacterium spp., Clostridium leptum group, Enterobactericaea and Lactobacillus spp.) were determined in faecal samples from post mortem examinations performed on 42 males, including cirrhotic alcoholics (n?=?13), non-cirrhotic alcoholics (n?=?15), non-alcoholic controls (n?=?14) and in 7 healthy male volunteers using real-time quantitative PCR (RT-qPCR). Translocation of bacteria into liver in the autopsy cases and into the ascites of 12 volunteers with liver cirrhosis was also studied with RT-qPCR. CD14 immunostaining was performed for the autopsy liver samples. Results Relative ratios of faecal bacteria in autopsy controls were comparable to those of healthy volunteers. Cirrhotics had in median 27 times more bacterial DNA of Enterobactericaea in faeces compared to the healthy volunteers (p?=?0.011). Enterobactericaea were also the most common bacteria translocated into cirrhotic liver, although there were no statistically significant differences between the study groups. Of the ascites samples from the volunteers with liver cirrhosis, 50% contained bacterial DNA from Enterobactericaea, Clostridium leptum group or Lactobacillus spp.. The total bacterial DNA in autopsy liver was associated with the percentage of CD14 expression (p?=?0.045). CD14 expression percentage in cirrhotics was significantly higher than in the autopsy controls (p?=?0.004). Conclusions Our results suggest that translocation of intestinal bacteria into liver may be involved as a one factor in the pathogenesis of alcoholic liver cirrhosis. PMID:24564202

2014-01-01

227

Microbial Translocation Is Associated with Extensive Immune Activation in Dengue Virus Infected Patients with Severe Disease  

PubMed Central

Background Severe dengue virus (DENV) disease is associated with extensive immune activation, characterized by a cytokine storm. Previously, elevated lipopolysaccharide (LPS) levels in dengue were found to correlate with clinical disease severity. In the present cross-sectional study we identified markers of microbial translocation and immune activation, which are associated with severe manifestations of DENV infection. Methods Serum samples from DENV-infected patients were collected during the outbreak in 2010 in the State of São Paulo, Brazil. Levels of LPS, lipopolysaccharide binding protein (LBP), soluble CD14 (sCD14) and IgM and IgG endotoxin core antibodies were determined by ELISA. Thirty cytokines were quantified using a multiplex luminex system. Patients were classified according to the 2009 WHO classification and the occurrence of plasma leakage/shock and hemorrhage. Moreover, a (non-supervised) cluster analysis based on the expression of the quantified cytokines was applied to identify groups of patients with similar cytokine profiles. Markers of microbial translocation were linked to groups with similar clinical disease severity and clusters with similar cytokine profiles. Results Cluster analysis indicated that LPS levels were significantly increased in patients with a profound pro-inflammatory cytokine profile. LBP and sCD14 showed significantly increased levels in patients with severe disease in the clinical classification and in patients with severe inflammation in the cluster analysis. With both the clinical classification and the cluster analysis, levels of IL-6, IL-8, sIL-2R, MCP-1, RANTES, HGF, G-CSF and EGF were associated with severe disease. Conclusions The present study provides evidence that both microbial translocation and extensive immune activation occur during severe DENV infection and may play an important role in the pathogenesis. PMID:23717702

de Araújo, Evaldo S. A.; van den Ham, Henk-Jan; Andeweg, Arno C.; Boas, Lucy S. V.; Felix, Alvina C.; Carvalho, Karina I.; de Matos, Andreia M.; Levi, José E.; Romano, Camila M.; Centrone, Cristiane C.; de Lima Rodrigues, Celia L.; Luna, Expedito; van Gorp, Eric C. M.; Osterhaus, Albert D. M. E.; Martina, Byron E. E.; Kallas, Esper G.

2013-01-01

228

POLYFLOW theoretical background  

NASA Astrophysics Data System (ADS)

In the scope of the 1990-04 lecture series on computational fluid dynamics, a finite element program is described. POLYFLOW was designed for the analysis of industrial processes dominated by nonlinear viscous phenomena and viscoelastic effects. It is based on the general principles of continuum mechanics, together with phenomenological or kinetic theoretical models for describing the rheological behavior of the fluid. The theoretical background, necessary to understand the models, and numerical techniques used in POLYFLOW, are provided. The governing equations, their finite element formulations and the solution procedures are summarized.

Crochet, M. J.

229

The Iron Line Background  

E-print Network

We investigate the presence of iron line emission among faint X-ray sources identified in the 1Ms Chandra Deep Field South and in the 2Ms Chandra Deep Field North. Individual source spectra are stacked in seven redshift bins over the range z=0.5-4. We find that iron line emission is an ubiquitous property of X-ray sources up to z~3. The measured line strengths are in good agreement with those expected by simple pre-Chandra estimates based on X-ray background synthesis models. The average rest frame equivalent width of the iron line does not show significant changes with redshift.

Marcella Brusa; Roberto Gilli; Andrea Comastri

2005-01-25

230

Correlation between missed abortion and insertional translocation involving chromosomes 1 and 7  

PubMed Central

Background: Missed abortion (Silent miscarriage) is defined as intrauterine fetal death before twenty weeks gestation. One of the most common causes of early missed abortions (before 10 weeks gestation) is cytogenetic abnormalities. Objective: To asses if there is a correlation between chromosomal aberrations (especially in chromosome 7) and missed abortion among at least two generations. Materials and Methods: After exclusion of direct causes of missed abortion, this study included 60 women (the study group) who had first trimestric missed abortion and 30 healthy women who did not suffer from any diseases during their pregnancy and had apparently normal outcome (the control group). All cases were diagnosed; the blood and tissue samples were collected from the mothers and abortuses from the Department of Obstetrics and Gynecology, Maternity Hospital, Ain Shams University. Cytogenetic analyses were performed by using conventional technique and G/T banding techniques and Fluorescence In Situ Hybridization (FISH) analysis with a whole chromosome 7 painting probe (WCP7) and a 7q subterminal probe (7q36, qter), prepared by chromosome micro dissection technique was used for confirming the specific chromosomal abnormality. Results: translocation between chromosomes 1 and 7 (46, XX, ins. (1; 7) (p32; q32.35). This insertion has appeared in two families and among two generations, and in one family among three generations. Conclusion: Chromosome 7 insertional translocation is a possible autosomal dominant inherited trait and may cause missed abortion.

Ashaat, Neveen; Husseiny, Ahmed

2012-01-01

231

Identification of chromosomes involved in a Robertsonian translocation in cattle  

E-print Network

Note Identification of chromosomes involved in a Robertsonian translocation in cattle E.P. Cribiu M (received 29 June 1989; accepted 30 August 1989) Summary - The chromosomes involved in the robertsonian(RBA) and C(CBG) banding techniques. The chromosomes in question were identified as chromosomes 9 and 23

Paris-Sud XI, Université de

232

Computer simulation study of fullerene translocation through lipid membranes  

E-print Network

Computer simulation study of fullerene translocation through lipid membranes JIRASAK WONG-EKKABUT1 aggregates of fullerene molecules can enter cells and alter their functions, and also cross the blood­brain barrier. However, the mechanisms by which fullerenes penetrate and disrupt cell membranes are still poorly

Wong-Ekkabut, Jirasak

233

A putative twin-arginine translocation pathway in Legionella pneumophila  

Microsoft Academic Search

Legionella pneumophila is a facultative intracellular human pathogen causing Legionnaires’ disease, a severe form of pneumonia. Because of the importance of secretion pathways in virulence, we were interested in the possible presence of the twin-arginine translocation (Tat) pathway in L. pneumophila. This secretion pathway is used to transport folded proteins, characterized by two arginines in their signal peptide, across the

Emmy De Buck; Ilya Lebeau; Liesbeth Maes; Nick Geukens; Eef Meyen; Lieve Van Mellaert; Jozef Anné; Elke Lammertyn

2004-01-01

234

Contributed Paper The Role of Translocation in Recovery of Woodland  

E-print Network

(Rangifer tarandus caribou) were extirpated recently from Banff National Park, Canada, and translocations, conservation reliant species, protected area, PVA, Rangifer tarandus, recovery plan, reintroduction tarandus caribou) fue extirpado recientemente del Parque Nacional Banff, Canad´a, y se ha estado

Hebblewhite, Mark

235

Translocation of twinflower (Linnaea borealis L.) in the Scottish Borders  

Microsoft Academic Search

Twinflower, Linnaea borealis L., is a creeping, woody, clonal perennial nationally scarce in the UK, with its distribution confined to discrete patches in Scotland. Translocation of twinflower from natural patches into either existing patches, with a view to increasing genetic variation and outcrossing rates, or to unoccupied habitat, with a view to increasing its overall prevalence, could effectively increase the

D. Kohn; P. Lusby

2004-01-01

236

DNA translocation through low-noise glass nanopores.  

PubMed

The effect of electron irradiation-induced shrinking on glass nanocapillaries with diameters ranging from 75 to 14 nm was analyzed by measuring the conductance characteristics with and without DNA translocation. We have investigated nanocapillary shrinking with a scanning electron microscope from several perspectives to understand the geometry of the shrunken nanocapillary. On the basis of this observation, the conductance was modeled with respect to the nanocapillary diameter, which allowed reproducing the experimental results. We then translocated DNA through the shrunken nanocapillaries and measured higher conductance drops for smaller diameters, reaching 1.7 nS for the 14 nm diameter nanocapillary. A model taking into account the conical shape of the shrunken nanocapillaries also supported this dependence. Next, we calculated the noise in the form of the standard deviation of the ionic conductance (between 0.04 and 0.15 nS) to calculate a signal-to-noise ratio (SNR) and compared it with nanopores embedded in 20 nm thick silicon nitride membranes. This shows that although nanocapillaries have smaller signal amplitudes due to their conical shape, they benefit from a lower noise. The glass nanocapillaries have a good SNR of about 25 compared with the SNR of 15 for smaller sized nanopores in silicon nitride membranes. The ability to use a modified model of nanopores to mimic the block conductance by DNA translocation provides a theoretical framework to support experimental results from translocating polymers such as DNA. PMID:24274458

Steinbock, Lorenz J; Bulushev, Roman D; Krishnan, Swati; Raillon, Camille; Radenovic, Aleksandra

2013-12-23

237

Nuclear translocation of urokinase-type plasminogen activator  

PubMed Central

Urokinase-type plasminogen activator (uPA) participates in diverse (patho)physiological processes through intracellular signaling events that affect cell adhesion, migration, and proliferation, although the mechanisms by which these occur are only partially understood. Here we report that upon cell binding and internalization, single-chain uPA (scuPA) translocates to the nucleus within minutes. Nuclear translocation does not involve proteolytic activation or degradation of scuPA. Neither the urokinase receptor (uPAR) nor the low-density lipoprotein-related receptor (LRP) is required for nuclear targeting. Rather, translocation involves the binding of scuPA to the nucleocytoplasmic shuttle protein nucleolin through a region containing the kringle domain. RNA interference and mutational analysis demonstrate that nucleolin is required for the nuclear transport of scuPA. Furthermore, nucleolin is required for the induction smooth muscle ?-actin (?-SMA) by scuPA. These data reveal a novel pathway by which uPA is rapidly translocated to the nucleus where it might participate in regulating gene expression. PMID:18337556

Lebedeva, Tatiana; Kuo, Alice; Yarovoi, Serge; Tkachuk, Sergei; Zaitsev, Sergei; Bdeir, Khalil; Dumler, Inna; Marks, Michael S.; Parfyonova, Yelena; Tkachuk, Vsevolod A.; Higazi, Abd Al-Roof; Cines, Douglas B.

2008-01-01

238

Mechanistic stoichiometry of proton translocation by cytochrome cbb3  

PubMed Central

Cytochrome cbb3 belongs to the superfamily of respiratory heme-copper oxidases that couple the reduction of molecular oxygen to proton translocation across the bacterial or mitochondrial membrane. The cbb3-type enzymes are found only in bacteria, and are both structurally and functionally the most distant from their mitochondrial counterparts. The mechanistic H+/e? stoichiometry of proton translocation in these cbb3-type cytochrome c oxidases has remained controversial. A stoichiometric efficiency of only one-half that of the mitochondrial aa3-type enzyme was recently proposed to be related to adaptation of the organism to microaerobic environments. Here, proton translocation by the Rhodobacter sphaeroides enzyme was studied using purified cytochrome cbb3 reconstituted into liposomes. An H+/e? stoichiometry of proton translocation close to unity was observed using the oxygen pulse method, but solely in conditions in which the vast majority of the enzyme was fully reduced in the anaerobic state before the O2 pulse. These data were compared with results using whole cells or spheroplasts, and the discrepancies in the literature data were discussed. Our results suggest that a proton-pumping efficiency of 1 H+/e? may be achieved using the single-proton uptake pathway identified in the structure of cytochrome cbb3. The mechanism of proton pumping thus differs from that of the aa3-type oxidases of mitochondria and bacteria. PMID:22529361

Rauhamaki, Virve; Bloch, Dmitry A.; Wikstrom, Marten

2012-01-01

239

Cholesterol Translocation in a Phospholipid Membrane Amit Choubey,  

E-print Network

Cholesterol Translocation in a Phospholipid Membrane Amit Choubey, Rajiv K. Kalia,§ * Noah of Southern California, Los Angeles, California ABSTRACT Cholesterol (CHOL) molecules play a key role), this is not the case for cholesterol (CHOL). Although the transport rate of CHOL has been elusive from an experimental

Southern California, University of

240

DNA Translocation Governed by Interactions with Solid-State Nanopores  

E-print Network

DNA Translocation Governed by Interactions with Solid-State Nanopores Meni Wanunu, Jason Sutin, Ben dynamics of individual DNA molecules through solid-state nanopores in the diameter range 2.7­5 nm. Our with DNA length by two power laws: for short DNA molecules, in the range 150­3500 bp, we find an exponent

Meller, Amit

241

Female Pressure: A translocal feminist youth-oriented cultural network  

Microsoft Academic Search

This article explores the potentials and limitations of Female Pressure, a collective of female DJs, music producers and club organizers that makes use of mailing lists, social networking platforms and a database to form a translocal feminist network. The article's empirical sections are based on the analysis of the two Female Pressure mailing lists, complemented by the analysis of the

Rosa Reitsamer

2012-01-01

242

Fast DNA Translocation through a Solid-State Nanopore  

E-print Network

Fast DNA Translocation through a Solid-State Nanopore Arnold J. Storm, Cornelis Storm,,§ Jianghua UniVersity of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands, and Physicochimie Curie (CNRS, one can detect individual single-strand molecules that are pulled through the pore by the electric

Dekker, Cees

243

Nitrogen translocation in a clonal dune perennial, Hydrocotyle bonariensis  

Microsoft Academic Search

Hydrocotyle bonariensis, a common rhizomatous perennial of coastal North Carolina, forms extensive clones in dune systems characterized by a patchy nitrogen distribution. An experiment was conducted in which Hydrocotyle clones were grown across artificially created soil nitrogen gradients to determine: (1) the effect of soil nitrogen availability and nitrogen translocation on clonal structure and (2) the costs versus benefits of

Jonathan P. Evans

1988-01-01

244

Climate change and trans-local solidarities Paul Routledge  

E-print Network

Climate change and trans-local solidarities Paul Routledge Paul.Routledge@ges.gla.ac.uk This project will consider local responses and adaptations to climate change across a range of different sites in the Global North and Global South, and consider how effective, carbon-sensitive solidarities around climate

Guo, Zaoyang

245

A new case of Robertsonian translocation in cattle.  

PubMed

A new Robertsonian translocation was found in several animals of the Blonde d'Aquitaine breed. The fused chromosome analyzed by G- and R-banding results from the fusion of chromosomes 21 and 27. C-banding suggests that the fused chromosome is dicentric. PMID:3367034

Berland, H M; Sharma, A; Cribiu, E P; Darre, R; Boscher, J; Popescu, C P

1988-01-01

246

HSP70 inhibits Bax translocation during Photofrin-PDT apoptosis  

NASA Astrophysics Data System (ADS)

Apoptosis is an important cellular event that plays a key role in therapy of many diseases. The mechanisms of the initiation and regulation of photodynamic therapy (PDT) -induced apoptosis is complex. Some PDT-associated apoptosis pathways involved plasma membrane death receptors, mitochondria, lysosomes and endoplasmic reticulum (ER). Our previous study found that Photofrin were localized primarily in mitochondria, the primary targets of Photofrin-PDT. The key role of Bax in the mitochondrion-mediated apoptosis has been demonstrated in many systems. In order to determine the role of Bax in the mitochondrion-mediated apoptosis induced by Photofrin-PDT, we used the CFP/GFP-Bax plasmid to monitor the dynamics of Bax activation and translocation after PDT treatment. With laser scanning confocal microscopy, we found that PDT induced Bax translocation from the cytosol to mitochondria; however, with cells over-expressing YFP-HSP70 plasmids, Bax translocation was not detected. Thus, for Photofrin-PDT, Bax activation and translocation were inhibited by HSP70, not influence the cell death.

Zhou, Feifan; Chen, Wei R.; Song, Sheng

2009-02-01

247

Yeast Pol4 Promotes Tel1-Regulated Chromosomal Translocations  

PubMed Central

DNA double-strand breaks (DSBs) are one of the most dangerous DNA lesions, since their erroneous repair by nonhomologous end-joining (NHEJ) can generate harmful chromosomal rearrangements. PolX DNA polymerases are well suited to extend DSB ends that cannot be directly ligated due to their particular ability to bind to and insert nucleotides at the imperfect template-primer structures formed during NHEJ. Herein, we have devised genetic assays in yeast to induce simultaneous DSBs in different chromosomes in vivo. The repair of these breaks in trans could result in reciprocal chromosomal translocations that were dependent on classical Ku-dependent NHEJ. End-joining events leading to translocations were mainly based on the formation of short base pairing between 3?-overhanging DNA ends coupled to gap-filling DNA synthesis. A major proportion of these events were specifically dependent on yeast DNA polymerase Pol4 activity. In addition, we have discovered that Pol4-Thr540 amino acid residue can be phosphorylated by Tel1/ATM kinase, which could modulate Pol4 activity during NHEJ. Our data suggest that the role of Tel1 in preventing break-induced chromosomal translocations can, to some extent, be due to its stimulating effect on gap-filling activity of Pol4 to repair DSBs in cis. Overall, this work provides further insight to the molecular mechanisms of DSB repair by NHEJ and presents a new perspective to the understanding of how chromosomal translocations are formed in eukaryotic cells. PMID:23874240

Sastre-Moreno, Guillermo; Aguilera, Andres; Blanco, Luis

2013-01-01

248

Oncogene Translocations and Non-Hodgkin Lymphoma (NHL)  

Cancer.gov

A colloboration with several large population-based cohorts to determine whether the prevalence or level of t14;18 is associated with risk of NHL and to investigate the clonal relationship between translocation-bearing cells and subsequent tumors

249

What happens to translocated game birds that `disappear'? M. J. Dickens1  

E-print Network

-translocation. In this study, we used chukar Alectoris chukar as a surrogate for translocated game birds in order to conduct; movement; homing; chukar. Correspondence Molly Dickens, Department of Biology, Tufts University, 163

Reed, Michael

250

Cosmic Microwave Background Polarization  

E-print Network

Cosmic microwave background (CMB) anisotropy is our richest source of cosmological information; the standard cosmological model was largely established thanks to study of the temperature anisotropies. By the end of the decade, the Planck satellite will close this important chapter and move us deeper into the new frontier of polarization measurements. Numerous ground--based and balloon--borne experiments are already forging into this new territory. Besides providing new and independent information on the primordial density perturbations and cosmological parameters, polarization measurements offer the potential to detect primordial gravity waves, constrain dark energy and measure the neutrino mass scale. A vigorous experimental program is underway worldwide and heading towards a new satellite mission dedicated to CMB polarization.

James G. Bartlett

2006-01-25

251

Gaussianity of LISA's confusion backgrounds  

SciTech Connect

Data analysis for the proposed Laser Interferometer Space Antenna (LISA) will be complicated by the huge number of sources in the LISA band. In the frequency band {approx}10{sup -4}-2x10{sup -3} Hz, galactic white dwarf binaries (GWDBs) are sufficiently dense in frequency space that it will be impossible to resolve most of them, and ''confusion noise'' from the unresolved Galactic binaries will dominate over instrumental noise in determining LISA's sensitivity to other sources in that band. Confusion noise from unresolved extreme-mass-ratio inspirals (EMRIs) could also contribute significantly to LISA's total noise curve. To date, estimates of the effect of LISA's confusion noise on matched-filter searches and their detection thresholds have generally approximated the noise as Gaussian, based on the central limit theorem. However in matched-filter searches, the appropriate detection threshold for a given class of signals may be located rather far out on the tail of the signal-to-noise probability distribution, where a priori it is unclear whether the Gaussian approximation is reliable. Using the Edgeworth expansion and the theory of large deviations, we investigate the probability distribution of the usual matched-filter detection statistic, far out on the tail of the distribution. We apply these tools to four somewhat idealized versions of LISA data searches: searches for EMRI signals buried in GWDB confusion noise, and searches for massive black hole binary signals buried in (i) GWDB noise, (ii) EMRI noise, and (iii) a sum of EMRI noise and Gaussian noise. Assuming reasonable short-distance cutoffs in the populations of confusion sources (since the very closest and hence strongest sources will be individually resolvable), modifications to the appropriate detection threshold, due to the non-Gaussianity of the confusion noise, turn out to be quite small for realistic cases. The smallness of the correction is partly due to the fact that these three types of sources evolve on quite different time scales, so no single background source closely resembles any search template. We also briefly discuss other types of LISA searches where the non-Gaussianity of LISA's confusion backgrounds could perhaps have a much greater impact on search reliability and efficacy.

Racine, Etienne [Department of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena, California 91125 (United States); Cutler, Curt [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109 (United States)

2007-12-15

252

Gravitational wave background from binary systems  

SciTech Connect

Basic aspects of the background of gravitational waves and its mathematical characterization are reviewed. The spectral energy density parameter {Omega}(f), commonly used as a quantifier of the background, is derived for an ensemble of many identical sources emitting at different times and locations. For such an ensemble, {Omega}(f) is generalized to account for the duration of the signals and of the observation, so that one can distinguish the resolvable and unresolvable parts of the background. The unresolvable part, often called confusion noise or stochastic background, is made by signals that cannot be either individually identified or subtracted out of the data. To account for the resolvability of the background, the overlap function is introduced. This function is a generalization of the duty cycle, which has been commonly used in the literature, in some cases leading to incorrect results. The spectra produced by binary systems (stellar binaries and massive black hole binaries) are presented over the frequencies of all existing and planned detectors. A semi-analytical formula for {Omega}(f) is derived in the case of stellar binaries (containing white dwarfs, neutron stars or stellar-mass black holes). Besides a realistic expectation of the level of background, upper and lower limits are given, to account for the uncertainties in some astrophysical parameters such as binary coalescence rates. One interesting result concerns all current and planned ground-based detectors (including the Einstein Telescope). In their frequency range, the background of binaries is resolvable and only sporadically present. In other words, there is no stochastic background of binaries for ground-based detectors.

Rosado, Pablo A. [Albert Einstein Institute, Max Planck Institute for Gravitational Physics, 30167 Hannover (Germany)

2011-10-15

253

Meiotic behaviour and spermatogenesis in male mice heterozygous for translocation types also occurring in man  

Microsoft Academic Search

In this thesis a start was made with meiotic observations of mouse translocation types - a Robertsonian translocation and a translocation between a metacentric and an acrocentric chromosome - which also occur in man. It is generally accepted that, when no chromosomal rearrangements are involved, man shows a higher level of non-disjunction than the mouse. When the meiotic behaviour of

J. H. Nijhoff

1981-01-01

254

Translocation as a conservation tool: site fidelity and movement of repatriated gopher tortoises (Gopherus polyphemus)  

Microsoft Academic Search

Efforts to evaluate the efficacy of translocation as a conservation tool have mostly been inadequate, particularly for reptiles and amphibians, leading many biologists to discount translocation as a viable management option. Nevertheless, with two-thirds of the world's tortoise and freshwater turtle species at risk, translocation may be one of the few remaining options for re-establishing extirpated populations and reconnecting fragmented

Tracey D. Tuberville; Erin E. Clark; Kurt A. Buhlmann; J. Whitfield Gibbons

2005-01-01

255

A Gatekeeper Chaperone Complex Directs Translocator Secretion during Type Three Secretion  

PubMed Central

Many Gram-negative bacteria use Type Three Secretion Systems (T3SS) to deliver effector proteins into host cells. These protein delivery machines are composed of cytosolic components that recognize substrates and generate the force needed for translocation, the secretion conduit, formed by a needle complex and associated membrane spanning basal body, and translocators that form the pore in the target cell. A defined order of secretion in which needle component proteins are secreted first, followed by translocators, and finally effectors, is necessary for this system to be effective. While the secreted effectors vary significantly between organisms, the ?20 individual protein components that form the T3SS are conserved in many pathogenic bacteria. One such conserved protein, referred to as either a plug or gatekeeper, is necessary to prevent unregulated effector release and to allow efficient translocator secretion. The mechanism by which translocator secretion is promoted while effector release is inhibited by gatekeepers is unknown. We present the structure of the Chlamydial gatekeeper, CopN, bound to a translocator-specific chaperone. The structure identifies a previously unknown interface between gatekeepers and translocator chaperones and reveals that in the gatekeeper-chaperone complex the canonical translocator-binding groove is free to bind translocators. Structure-based mutagenesis of the homologous complex in Shigella reveals that the gatekeeper-chaperone-translocator complex is essential for translocator secretion and for the ordered secretion of translocators prior to effectors. PMID:25375170

Archuleta, Tara L.; Spiller, Benjamin W.

2014-01-01

256

Interchromosome effects on chiasma distribution due to translocations in Locusta migratoria  

Microsoft Academic Search

Two different strains carrying translocations were obtained by irradiation of Locusta migratoria males. The presence of translocations produced an increase in chiasma number in the chromosomes not involved in the translocation, compared to the same chromosomes in wild-type individuals. This increase was higher in the individuals carrying the octovalent than in those carrying the quadrivalent.

M. Diez; M. J. Puertas

1984-01-01

257

Signal sequences directing cotranslational translocation expand the range of proteins amenable to phage display  

Microsoft Academic Search

Even proteins that fold well in bacteria are frequently displayed poorly on filamentous phages. Low protein presentation on phage might be caused by premature cytoplasmic folding, leading to inefficient translocation into the periplasm. As translocation is an intermediate step in phage assembly, we tested the display levels of a range of proteins using different translocation pathways by employing different signal

Daniel Steiner; Patrik Forrer; Michael T Stumpp; Andreas Plückthun

2006-01-01

258

Complex Y-linked translocations in Delia antiqua produced by irradiation of a fertile Y-linked translocation.  

PubMed

In the onion fly, Delia antiqua, a fertile, Y-linked translocation involving chromosomes Y and 2 was irradiated with fast neutrons to induce new complexes involving the Y-chromosome. This chromosome is male determining in the onion fly. Such complexes can be used for the development of genetic sexing systems and also for the introduction of sterility into field populations following release. Irradiation reduced egg fertility by 54 per cent and significantly reduced larval survival but it had no effect on the F1 sex ratio. By measuring the fertility of 807 F1 males following outcrossing, 112 semi-sterile progenies were isolated of which 11 were lost, 29 showed no inheritance of the semi-sterility, 59 were new autosomal translocations and 13 were new complex Y-linked translocations. This classification was accomplished by checking the fertilities of outcrossed F2 males and females. Following cytological observation it was revealed that one of these new complexes involved four chromosome pairs, the remainder involved three. There appeared to be no correlation between the fertility of the translocation and the complexity of the rearrangement. The utilization of these rearrangements in the development of the genetic sexing technique for the onion fly is discussed, together with an assessment of their use for fertility reduction in natural populations. PMID:7263278

Robinson, A S; van Heemert, K

1981-02-01

259

Noise correlations in cosmic microwave background experiments  

NASA Technical Reports Server (NTRS)

Many analysis of microwave background experiments neglect the correlation of noise in different frequency of polarization channels. We show that these correlations, should they be present, can lead to serve misinterpretation of an experiment. In particular, correlated noise arising from either electronics or atmosphere may mimic a cosmic signal. We quantify how the likelihood function for a given experiment varies with noise correlation, using both simple analytic models and actual data. For a typical microwave background anisotropy experiment, noise correlations at the level of 1% of the overall noise can seriously reduce the significance of a given detection.

Dodelson, Scott; Kosowsky, Arthur; Myers, Steven T.

1995-01-01

260

Cosmology and the Cosmic Background Explorer (COBE)  

NASA Technical Reports Server (NTRS)

COBE, planned for launch aboard a Delta rocket, is NASA's first space mission specifically designed to study the diffuse IR and microwave background radiation. COBE has three instruments for performing precision measurements of the spectrum and angular distribution of the 3 K cosmic background radiation and for making an all-sky survey of the diffuse IR emission at wavelengths of 1-300 microns. COBE will carry differential microwave radiameters to search for anisotropies to a sensitivity per 7-deg pixel of 0.15 mK at frequencies of 53 and 90 GHz and of 0.3 mK at 32 GHz.

Boggess, Nancy W.

1989-01-01

261

Optical detection of DNA translocation through silicon nanopore by ultraviolet light  

NASA Astrophysics Data System (ADS)

In this paper, we propose a new optical detection scheme for nanopore-based DNA sequencing with high resolution towards eventual base identification. We use ultraviolet light for excitation of a fluorescent probe attached to DNA and a nanopore in the silicon membrane that has a significantly large refractive index and an extinction coefficient at ultraviolet wavelengths. In this study, numerical electromagnetic simulation revealed that the z-polarization component (perpendicular to the membrane plane) of the electric field was dominant near the nanopore and generated a large electric field gradient at the nanopore exit, typically with a decay length of 2 nm for a nanopore with diameter of 7 nm. The large extinction coefficient contributed to reduction in background noise coming from fluorophore-labeled DNA strands that remain behind the membrane (the cis side of the membrane). We observed a high signal-to-noise ratio of single DNA translocation events under the application of an electric field.

Yamazaki, Hirohito; Kimura, Shinji; Tsukahara, Mutsumi; Esashika, Keiko; Saiki, Toshiharu

2014-04-01

262

The clinical significance of the FUS-CREB3L2 translocation in low-grade fibromyxoid sarcoma  

PubMed Central

Background Low-grade fibromyxoid sarcoma (LGFMS) is a rare soft-tissue neoplasm with a deceptively benign histological appearance. Local recurrences and metastases can manifest many years following excision. The FUS-CREB3L2 gene translocation, which occurs commonly in LGFMS, may be detected by reverse-transcriptase polymerase chain reaction (RT-PCR) and fluorescence in situ hybridisation (FISH). We assessed the relationship between clinical outcome and translocation test result by both methods. Methods We report genetic analysis of 23 LGFMS cases and clinical outcomes of 18 patients with mean age of 40.6 years. During follow-up (mean 24.8 months), there were no cases of local recurrence or metastasis. One case was referred with a third recurrence of a para-spinal tumour previously incorrectly diagnosed as a neurofibroma. Results Results showed 50% of cases tested positive for the FUS-CREB3L2 translocation by RT-PCR and 81.8% by FISH, suggesting FISH is more sensitive than RT-PCR for confirming LGFMS diagnosis. Patients testing positive by both methods tended to be younger and had larger tumours. Despite this, there was no difference in clinical outcome seen during short and medium-term follow-up. Conclusions RT-PCR and FISH for the FUS-CREB3L2 fusion transcript are useful tools for confirming LGFMS diagnosis, but have no role in predicting medium-term clinical outcome. Due to the propensity for late recurrence or metastasis, wide excision is essential, and longer-term follow-up is required. This may identify a difference in long-term clinical outcome between translocation-positive and negative patients. PMID:21406083

2011-01-01

263

Translocation of particles and inflammatory responses after exposure to fine particles and nanoparticles in an epithelial airway model  

PubMed Central

Background Experimental studies provide evidence that inhaled nanoparticles may translocate over the airspace epithelium and cause increased cellular inflammation. Little is known, however, about the dependence of particle size or material on translocation characteristics, inflammatory response and intracellular localization. Results Using a triple cell co-culture model of the human airway wall composed of epithelial cells, macrophages and dendritic cells we quantified the entering of fine (1 ?m) and nano-sized (0.078 ?m) polystyrene particles by laser scanning microscopy. The number distribution of particles within the cell types was significantly different between fine and nano-sized particles suggesting different translocation characteristics. Analysis of the intracellular localization of gold (0.025 ?m) and titanium dioxide (0.02–0.03 ?m) nanoparticles by energy filtering transmission electron microscopy showed differences in intracellular localization depending on particle composition. Titanium dioxide nanoparticles were detected as single particles without membranes as well as in membrane-bound agglomerations. Gold nanoparticles were found inside the cells as free particles only. The potential of the different particle types (different sizes and different materials) to induce a cellular response was determined by measurements of the tumour necrosis factor-? in the supernatants. We measured a 2–3 fold increase of tumour necrosis factor-? in the supernatants after applying 1 ?m polystyrene particles, gold nanoparticles, but not with polystyrene and titanium dioxide nanoparticles. Conclusion Quantitative laser scanning microscopy provided evidence that the translocation and entering characteristics of particles are size-dependent. Energy filtering transmission electron microscopy showed that the intracellular localization of nanoparticles depends on the particle material. Both particle size and material affect the cellular responses to particle exposure as measured by the generation of tumour necrosis factor-?. PMID:17894871

Rothen-Rutishauser, Barbara; Muhlfeld, Christian; Blank, Fabian; Musso, Claudia; Gehr, Peter

2007-01-01

264

Entropic effects in formation of chromosome territories: towards understanding of radiation-induced gene translocation frequency  

NASA Astrophysics Data System (ADS)

A detailed understanding of structural organization of biological target, such as geometry of an inter-phase chromosome, is an essential prerequisite for gaining deeper insight into relationship between radiation track structure and radiation-induced biological damage [1]. In particular, coupling of biophysical models aimed to describe architecture of chromosomes and their positioning in a cell nucleus [2-4] with models of local distribution of ionizations caused by passing projectiles, are expected to result in more accurate estimates of aberration induction caused by radiation. There is abundant experimental evidence indicating that arrangements of chromosomes in eukaryotic cell nucleus is non-random and has been evolutionary conserved in specific cell types. Moreover, the radial position of a given chromosome territory (CT) within the cell nucleus has been shown to correlate with its size and gene density. Usually it is assumed that chromosomal geometry and positioning result from the action of specific forces acting locally, such as hydrogen bonds, electrostatic, Van der Waals or hydrophobic interactions operating between nucleosomes and within their interiors. However, it is both desirable and instructive to learn to what extend organization of inter-phase chromosomes is affected by nonspecific entropic forces. In this study we report results of a coarse-grained analysis of a chromatin structure modeled by two distinct approaches. In the first method, we adhere to purely statistical analysis of chromatin packing within a chromosome territory. On the basis of the polymer theory, the chromatin fiber of diameter 30nm is approximated by a chain of spheres, each corresponding to about 30 kbp. Random positioning of the center of the domain is repeated for 1000 spherical nuclei. Configuration of the domain is determined by a random packing of a polymer (a string of identical beads) in estimated fraction of space occupied by a chromosome of a given length and mass. The degree of condensation of the chromatin fiber is modeled by changing length of the string: e.g. loosening of the structure is achieved by distributing the chromosome mass into a higher number of smaller beads and tighter configuration corresponds to a lower number of fragments (balls) with a bigger radius. Additionally, for each configuration, a degree of possible overlapping between domains is assumed. This procedure effectively intensifies loosening/tightening of the chromosome structure by changing the radial dimension of the domain while keeping a constant volume of the polymer chain. Such a positioning model is confronted with a minimalistic molecular dynamics model [5] on a similar structure, in which a chain of beads becomes connected by entropic spring energy and subjected to thermal fluctuations. Comparison of both Monte Carlo models allows to discuss variability of possible configurations as observed in static and dynamic models of chromosome territories along with the effect of compaction and relative arrangements of territorial polymer structures. Acknowledgements: Project is operated within the Foundation for Polish Science International Ph.D. Projects Programme co-financed by the European Regional Development Fund covering, under the agreement no. MPD/2009/6, the Jagiellonian University International Ph.D. Studies in Physics of Complex Systems. References: [1] F. Ballarini, M. Biaggi, and A. Ottolenghi, Radiation Protection Dosimetry 99, 175 (2002). [2] M. Nicodemi and A. Prisco, Biophysical Journal 96, 2168 (2009). [3] P. Cook and D. Marenduzzo, Journal of Cell Biology 186, 825 (2009). [4] M. Tark-Dame, R. van Driel, and D. Heermann, Journal of Cell Science 124, 839 (2011). [5] W. Swope, H. Andersen, P. Berens, and K. Wilson, J. Chem. Phys. 76, 637 (1982).

Gudowska-Nowak, Ewa; Ritter, Sylvia; Durante, Marco; Deperas-Standylo, Joanna; Ciesla, Michal

2012-07-01

265

Force-induced calcium concentration change and focal adhesion translocation : effects of force amplitude and frequency  

E-print Network

Vascular endothelial cells rapidly sense and transduce external forces into biological signals through a process known as mechanotransduction. Numerous biological processes are involved in mechanotransduction, including ...

Mack, Peter J. (Peter Joseph), 1980-

2004-01-01

266

Integrable Background Geometries  

NASA Astrophysics Data System (ADS)

This work has its origins in an attempt to describe systematically the integrable geometries and gauge theories in dimensions one to four related to twistor theory. In each such dimension, there is a nondegenerate integrable geometric structure, governed by a nonlinear integrable differential equation, and each solution of this equation determines a background geometry on which, for any Lie group G, an integrable gauge theory is defined. In four dimensions, the geometry is selfdual conformal geometry and the gauge theory is selfdual Yang-Mills theory, while the lower-dimensional structures are nondegenerate (i.e., non-null) reductions of this. Any solution of the gauge theory on a k-dimensional geometry, such that the gauge group H acts transitively on an ?-manifold, determines a (k+?)-dimensional geometry (k+??4) fibering over the k-dimensional geometry with H as a structure group. In the case of an ?-dimensional group H acting on itself by the regular representation, all (k+?)-dimensional geometries with symmetry group H are locally obtained in this way. This framework unifies and extends known results about dimensional reductions of selfdual conformal geometry and the selfdual Yang-Mills equation, and provides a rich supply of constructive methods. In one dimension, generalized Nahm equations provide a uniform description of four pole isomonodromic deformation problems, and may be related to the {SU}(?) Toda and dKP equations via a hodograph transformation. In two dimensions, the {Diff}(S^1) Hitchin equation is shown to be equivalent to the hyperCR Einstein-Weyl equation, while the {SDiff}(?^2) Hitchin equation leads to a Euclidean analogue of Plebanski's heavenly equations. In three and four dimensions, the constructions of this paper help to organize the huge range of examples of Einstein-Weyl and selfdual spaces in the literature, as well as providing some new ! ones. The nondegenerate reductions have a long ancestry. More ! recently , degenerate or null reductions have attracted increased interest. Two of these reductions and their gauge theories (arguably, the two most significant) are also described.

Calderbank, David M. J.

2014-03-01

267

Recurrent translocations involving the IRF4 oncogene locus in peripheral T-cell lymphomas.  

PubMed

Oncogenes involved in recurrent chromosomal translocations serve as diagnostic markers and therapeutic targets in hematopoietic tumors. In contrast to myeloid and B-cell neoplasms, translocations in peripheral T-cell lymphomas (PTCLs) are poorly understood. Here, we identified recurrent translocations involving the multiple myeloma oncogene-1/interferon regulatory factor-4 (IRF4) locus in PTCLs. IRF4 translocations exist in myeloma and some B-cell lymphomas, but have not been reported earlier in PTCLs. We studied 169 PTCLs using fluorescence in situ hybridization and identified 12 cases with IRF4 translocations. Two cases with t(6;14)(p25;q11.2) had translocations between IRF4 and the T-cell receptor-alpha (TCRA) locus. Both were cytotoxic PTCLs, unspecified (PTCL-Us) involving bone marrow and skin. In total, 8 of the remaining 10 cases were cutaneous anaplastic large-cell lymphomas (ALCLs) without TCRA rearrangements (57% of cutaneous ALCLs tested). These findings identified IRF4 translocations as a novel recurrent genetic abnormality in PTCLs. Cytotoxic PTCL-Us involving bone marrow and skin and containing IRF4/TCRA translocations might represent a distinct clinicopathologic entity. Translocations involving IRF4 but not TCRA appear to occur predominantly in cutaneous ALCLs. Detecting these translocations may be useful in lymphoma diagnosis. Further, due to its involvement in translocations, MUM1/IRF4 protein may play an important biologic role in some PTCLs, and might represent a possible therapeutic target. PMID:18987657

Feldman, A L; Law, M; Remstein, E D; Macon, W R; Erickson, L A; Grogg, K L; Kurtin, P J; Dogan, A

2009-03-01

268

Chromosomal translocations in human cells are generated by canonical nonhomologous end-joining.  

PubMed

Breakpoint junctions of the chromosomal translocations that occur in human cancers display hallmarks of nonhomologous end-joining (NHEJ). In mouse cells, translocations are suppressed by canonical NHEJ (c-NHEJ) components, which include DNA ligase IV (LIG4), and instead arise from alternative NHEJ (alt-NHEJ). Here we used designer nucleases (ZFNs, TALENs, and CRISPR/Cas9) to introduce DSBs on two chromosomes to study translocation joining mechanisms in human cells. Remarkably, translocations were altered in cells deficient for LIG4 or its interacting protein XRCC4. Translocation junctions had significantly longer deletions and more microhomology, indicative of alt-NHEJ. Thus, unlike mouse cells, translocations in human cells are generated by c-NHEJ. Human cancer translocations induced by paired Cas9 nicks also showed a dependence on c-NHEJ, despite having distinct joining characteristics. These results demonstrate an unexpected and striking species-specific difference for common genomic rearrangements associated with tumorigenesis. PMID:25201414

Ghezraoui, Hind; Piganeau, Marion; Renouf, Benjamin; Renaud, Jean-Baptiste; Sallmyr, Annahita; Ruis, Brian; Oh, Sehyun; Tomkinson, Alan E; Hendrickson, Eric A; Giovannangeli, Carine; Jasin, Maria; Brunet, Erika

2014-09-18

269

Fast DNA translocation through a solid-state nanopore.  

PubMed

We report experiments and modeling of translocation of double-strand DNA through a siliconoxide nanopore. Long DNA molecules with different lengths ranging from 6500 to 97000 base pairs have been electrophoretically driven through a 10 nm pore. We observe a power-law caling of the translocation time with the length, with an exponent of 1.27. This nonlinear scaling is strikingly different from the well-studied linear behavior observed in similar experiments performed on protein pores. We present a theoretical model where hydrodynamic drag on the ection of the polymer outside the pore is the dominant force counteracting the electrical driving force. We show that this applies to our experiments, and we derive a power-law scaling with an exponent of 1.22, in good agreement with the data. PMID:16178209

Storm, Arnold J; Storm, Cornelis; Chen, Jianghua; Zandbergen, Henny; Joanny, Jean-François; Dekker, Cees

2005-07-01

270

Protein translocation by the Sec61/SecY channel.  

PubMed

The conserved protein-conducting channel, referred to as the Sec61 channel in eukaryotes or the SecY channel in eubacteria and archaea, translocates proteins across cellular membranes and integrates proteins containing hydrophobic transmembrane segments into lipid bilayers. Structural studies illustrate how the protein-conducting channel accomplishes these tasks. Three different mechanisms, each requiring a different set of channel binding partners, are employed to move polypeptide substrates: The ribosome feeds the polypeptide chain directly into the channel, a ratcheting mechanism is used by the eukaryotic endoplasmic reticulum chaperone BiP, and a pushing mechanism is utilized by the bacterial ATPase SecA. We review these translocation mechanisms, relating biochemical and genetic observations to the structures of the protein-conducting channel and its binding partners. PMID:16212506

Osborne, Andrew R; Rapoport, Tom A; van den Berg, Bert

2005-01-01

271

Microscopic Kinetics of DNA Translocation through synthetic nanopores.  

PubMed

We have previously demonstrated that a nanometer-diameter pore in a nanometer-thick metal-oxide-semiconductor-compatible membrane can be used as a molecular sensor for detecting DNA. The prospects for using this type of device for sequencing DNA are avidly being pursued. The key attribute of the sensor is the electric field-induced (voltage-driven) translocation of the DNA molecule in an electrolytic solution across the membrane through the nanopore. To complement ongoing experimental studies developing such pores and measuring signals in response to the presence of DNA, we conducted molecular dynamics simulations of DNA translocation through the nanopore. A typical simulated system included a patch of a silicon nitride membrane dividing water solution of potassium chloride into two compartments connected by the nanopore. External electrical fields induced capturing of the DNA molecules by the pore from the solution and subsequent translocation. Molecular dynamics simulations suggest that 20-basepair segments of double-stranded DNA can transit a nanopore of 2.2 x 2.6 nm(2) cross section in a few microseconds at typical electrical fields. Hydrophobic interactions between DNA bases and the pore surface can slow down translocation of single-stranded DNA and might favor unzipping of double-stranded DNA inside the pore. DNA occluding the pore mouth blocks the electrolytic current through the pore; these current blockades were found to have the same magnitude as the blockade observed when DNA transits the pore. The feasibility of using molecular dynamics simulations to relate the level of the blocked ionic current to the sequence of DNA was investigated. PMID:15345583

Aksimentiev, Aleksij; Heng, Jiunn B; Timp, Gregory; Schulten, Klaus

2004-09-01

272

Subcellular distribution and translocation of radionuclides in plants  

SciTech Connect

The subcellular distribution of radionuclides in Glycine max Merr. (soybean) and Cucumis sativus L. (cucumber) and translocation of plant absorbed radionuclides with growth in soybean were studied. More than 60% of cellular incorporated Rb{sup {minus}83}, Sr{sup {minus}85}, Mn{sup {minus}54}, Nb{sup {minus}95}, and Se{sup {minus}75} remained in the supernatant fraction; 55% and 20% of Cr{sup {minus}51} was bound to soybean and cucumber cell wall fractions, respectively; 70% or more of Be{sup {minus}7}, Y{sup {minus}88}, and Fe{sup {minus}59} was fixed in the chloroplast fraction; and approx. 10% of Sc{sup {minus}46}, Fe{sup {minus}59}, V{sup {minus}48}, and As were fixed in the mitochondrial fraction. Translocation of nuclides within the soybean plant at different stages of growth has been determined. Vanadium, Y{sup {minus}88}, Be{sup {minus}7}, Se{sup {minus}75}, Nb{sup {minus}95}, Sc{sup {minus}46}, Cr{sup {minus}51}, and Zr{sup {minus}88} were predominantly accumulated in the root. Although the total percentage of plant uptake of Sc{sup {minus}46}, Zr{sup {minus}88}, Nb{sup {minus}95}, Sc{sup {minus}46}, and Cr{sup {minus}51} was high, because of low mobility and translocation to shoot, their accumulation in the fruit fraction was negligible. The translocation of mobile nuclides in plants was demonstrated clearly by Rb{sup {minus}83}, Zn{sup {minus}65}, and Fe{sup {minus}59}. Data on the nuclide fraction mobilized from vegetative parts into edible parts was used to assess the percentage of accumulated radionuclides in plants that may reach humans through beans.

Gouthu, S.; Weginwar, R.; Arie, Tsutomu; Ambe, Shizuko; Ozaki, Takuo; Enomoto, Shuichi; Ambe, Fumitoshi; Yamaguchi, Isamu

1999-09-01

273

Seaside transportation—from structure to function of translocation machines  

PubMed Central

The EMBO conference ‘From Structure to Function of Translocation Machines' took place in April 2013 in Dubrovnik, Croatia. The meeting brought together a mix of established and aspiring researchers to discuss a wealth of unpublished data and ideas in a lively scientific programme of talks designed to shatter the established dogma. From new ways to envisage known protein transport pathways to a brand new and totally unconventional protein transport system, surprises were part and parcel of this excellent EMBO conference. PMID:23764920

Lithgow, Trevor; Waksman, Gabriel

2013-01-01

274

Repetitive telomeric sequences in chromosomal translocations involving chromosome 21  

SciTech Connect

Telomeres perform key functions in maintaining chromosome integrity. In some structural rearrangements the structure and polymorphism in human telomeres may play a significant role. However, of all the telomeric and subtelomeric sequences, only the terminal TTAGGG repeats are believed essential for telomere function. During the course of a study on the role of telomere structure and polymorphism in chromosomal rearrangements observed in families referred for prenatal diagnosis, we studied three cases in which chromosome 21 was involved. Repetitive TTAGGG sequences for all human chromosomes were used as probes (Oncor). Case 1, a de novo cryptic translocation (2;21) was initially identified as monosomy 21 in a child with psychomotor delay and mild dysmorphism. Using a cosmid probe specific for region 21q22.3 and whole chromosome 21 specific painting probe, the long arm of 21 was found on the short arm of chromosome 2 with an interstitial telomere at the breakpoint junction. All the cells were monosomic for 21pter{yields}q21. Case 2 is a familial (19;21) translocation. GTG-banding and FISH with a satellite probe showed no apparent loss of material at the end of either 19q or 21q, with an interstitial telomere at the fusion site of the two intact chromosomes. In case 3, a four generation reciprocal (20;21) translocation, there was no interstitial telomere. The persistence of an interstitial telomere is a relatively rare event which can now be observed with in situ hybridization. Its study may lead to a better understanding of the dynamics of translocations and of chromosome imbalance.

Qu, J.; Dallaire, L.; Fetni, R. [Universite de Montreal, Quebec (Canada)] [and others

1994-09-01

275

Reducing atelectasis attenuates bacterial growth and translocation in experimental pneumonia  

Microsoft Academic Search

Abstract Besides being one of the mechanisms responsible for ventilator-induced lung injury, atelectasis also seems to aggravate the course of experimental pneumonia. In this study, we examined,the effect of reducing the degree of atelectasis by natural modified surfactant and\\/or open lung ventilation, on bacterial growth and translocation in a piglet model of group B streptococcal pneumonia. After creating surfactant-deficiency by

Kaam van A. H. L. C; Robert A. Lachmann; Egbert Herting; Anne De Jaegere; F. Iwaarden; L. Arnold Noorduyn; Joke H. Kok; Jack J. Haitsma; Burkhard Lachmann

2004-01-01

276

Frequency-Shift Hearing Aid  

NASA Technical Reports Server (NTRS)

Proposed hearing aid maps spectrum of speech into band of lower frequencies at which ear remains sensitive. By redirecting normal speech frequencies into frequency band from 100 to 1,500 Hz, hearing aid allows people to understand normal conversation, including telephone calls. Principle operation of hearing aid adapted to other uses such as, clearing up noisy telephone or radio communication. In addition, loud-speakers more easily understood in presence of high background noise.

Weinstein, Leonard M.

1994-01-01

277

Kinetic mechanism of translocation and dNTP binding in individual DNA polymerase complexes.  

PubMed

Complexes formed between phi29 DNA polymerase (DNAP) and DNA fluctuate discretely between the pre-translocation and post-translocation states on the millisecond time scale. The translocation fluctuations can be observed in ionic current traces when individual complexes are captured atop the ?-hemolysin nanopore in an electric field. The presence of complementary 2'-deoxynucleoside triphosphate (dNTP) shifts the equilibrium across the translocation step toward the post-translocation state. Here we have determined quantitatively the kinetic relationship between the phi29 DNAP translocation step and dNTP binding. We demonstrate that dNTP binds to phi29 DNAP-DNA complexes only after the transition from the pre-translocation state to the post-translocation state; dNTP binding rectifies the translocation but it does not directly drive the translocation. Based on the measured time traces of current amplitude, we developed a method for determining the forward and reverse translocation rates and the dNTP association and dissociation rates, individually at each dNTP concentration and each voltage. The translocation rates, and their response to force, match those determined for phi29 DNAP-DNA binary complexes and are unaffected by dNTP. The dNTP association and dissociation rates do not vary as a function of voltage, indicating that force does not distort the polymerase active site and that dNTP binding does not directly involve a displacement in the translocation direction. This combined experimental and theoretical approach and the results obtained provide a framework for separately evaluating the effects of biological variables on the translocation transitions and their effects on dNTP binding. PMID:23705688

Lieberman, Kate R; Dahl, Joseph M; Mai, Ai H; Cox, Ashley; Akeson, Mark; Wang, Hongyun

2013-06-19

278

Compositions and methods for detecting gene rearrangements and translocations  

DOEpatents

Disclosed is a series of nucleic acid probes for use in diagnosing and monitoring certain types of leukemia using, e.g., Southern and Northern blot analyses and fluorescence in situ hybridization (FISH). These probes detect rearrangements, such as translocations involving chromosome band 11q23 with other chromosomes bands, including 4q21, 6q27, 9p22, 19p13.3, in both dividing leukemic cells and interphase nuclei. The breakpoints in all such translocations are clustered within an 8.3 kb BamHI genomic region of the MLL gene. A novel 0.7 kb BamH1 cDNA fragment derived from this gene detects rearrangements on Southern blot analysis with a single BamHI restriction digest in all patients with the common 11q23 translocations and in patients with other 11q23 anomalies. Northern blot analyses are presented demonstrating that the MLL gene has multiple transcripts and that transcript size differentiates leukemic cells from normal cells. Also disclosed are MLL fusion proteins, MLL protein domains and anti-MLL antibodies.

Rowley, Janet D. (Chicago, IL); Diaz, Manuel O. (Chicago, IL)

2000-01-01

279

Dominant-lethal mutations and heritable translocations in mice  

SciTech Connect

Chromosome aberrations are a major component of radiation or chemically induced genetic damage in mammalian germ cells. The types of aberration produced are dependent upon the mutagen used and the germ-cell stage treated. For example, in male meiotic and postmeiotic germ cells certain alkylating chemicals induce both dominant-lethal mutations and heritable translocations while others induce primarily dominant-lethal mutations. Production of these two endpoints appears to be determined by the stability of alkylation products with the chromosomes. If the reaction products are intact in the male chromosomes at the time of sperm entry, they may be repaired in fertilized eggs. If repair is not effected and the alkylation products persist to the time of pronuclear chromosome replication, they lead to chromatid-type aberrations and eventually to dominant-lethality. The production of heritable translocations, on the other hand, requires a transformation of unstable alkylation products into suitable intermediate lesions. The process by which these lesions are converted into chromosome exchange within the male genome takes place after sperm enters the egg but prior to the time of pronuclear chromosome replication (i.e., chromosome-type). Thus, dominant-lethal mutations result from both chromatid- and chromosome-type aberrations while heritable translocations result primarily from the latter type. DNA target sites associated with the production of these two endpoints are discussed.

Generoso, W.M.

1983-01-01

280

Protein translocating as unfolded chains through solid-state nanopores  

NASA Astrophysics Data System (ADS)

We have detected translocation of the protein shrimp alkaline phosphatase (SAP) through a solid-state nanopore. The nanopores were fabricated in a silicon nitride membrane using a highly focused electron beam in a transmission electron microscope. Once formed, the nanopore was wet with an electrolytic solution and current was driven through it by application of an electric potential. When introduced to the negative side of the nanopore, the negatively charged SAP produced current blockages as the protein molecules were driven through the pore by the electric field. No current blockages occurred when protein had not been added to the electrolytic solution nor when polarity of the applied electric field was reversed. Furthermore, this globular protein does not appear to translocate as a sphere as might be expected, but rather goes through as an unfolded chain. Our current blockage events are similar to signals produced by lambda DNA translocating through a nanopore significantly larger than the DNA's diameter. This has implications for future experiments using nanopores to probe proteins.

Aref, Thomas; Bezryadin, Alexey

2007-03-01

281

Lipid nanobilayers to host biological nanopores for DNA translocations.  

PubMed

We characterize a recently introduced novel nanobilayer technique [Gornall, J. L., Mahendran, K. R., Pambos, O. J., Steinbock, L. J., Otto, O., Chimerel, C., Winterhalter, M., and Keyser, U. F. Simple reconstitution of protein pores in nano lipid bilayers. Nano Lett. 2011, 11 (8), 3334-3340] and its practical aspects for incorporating the biological nanopore ?-hemolysin from Staphylococcus aureus and subsequent studies on the translocation of biomolecules under various conditions. This technique provides advantages over classical bilayer methods, especially the quick formation and extended stability of a bilayer. We have also developed a methodology to prepare a uniform quality of giant unilamellar vesicles (GUVs) in a reproducible way for producing nanobilayers. The process and the characteristics of the reconstitution of ?-hemolysin in nanobilayers were examined by exploiting various important parameters, including pH, applied voltage, salt concentration, and number of nanopores. Protonation of ?-hemolysin residues in the low pH region affects the translocation durations, which, in turn, changes the statistics of event types as a result of electrostatics and potentially the structural changes in DNA. When the pH and applied voltage were varied, it was possible to investigate and partly control the capture rates and type of translocation events through ?-hemolysin nanopores. This study could be helpful to use the nanobilayer technique for further explorations, particularly owing to its advantages and technical ease compared to existing bilayer methods. PMID:23214950

Göpfrich, Kerstin; Kulkarni, Chandrashekhar V; Pambos, Oliver J; Keyser, Ulrich F

2013-01-01

282

Controlling Polymer Translocation and Ion Transport via Charge Correlations.  

PubMed

We develop a correlation-corrected transport theory in order to predict ionic and polymer transport properties of membrane nanopores under physical conditions where mean-field electrostatics breaks down. The experimentally observed low KCl conductivity of open ?-hemolysin pores is quantitatively explained by the presence of surface polarization effects. Upon the penetration of a DNA molecule into the pore, these polarization forces combined with the electroneutrality of DNA sets a lower boundary for the ionic current, explaining the weak salt dependence of blocked pore conductivities at dilute ion concentrations. The addition of multivalent counterions to the solution results in the reversal of the polymer charge and the direction of the electroosmotic flow. With trivalent spermidine or quadrivalent spermine molecules, the charge inversion is strong enough to stop the translocation of the polymer and to reverse its motion. This mechanism can be used efficiently in translocation experiments in order to improve the accuracy of DNA sequencing by minimizing the translocation velocity of the polymer. PMID:25310861

Buyukdagli, Sahin; Ala-Nissila, T

2014-11-01

283

Coliphage HK022 Nun protein inhibits RNA polymerase translocation.  

PubMed

The Nun protein of coliphage HK022 arrests RNA polymerase (RNAP) in vivo and in vitro at pause sites distal to phage ? N-Utilization (nut) site RNA sequences. We tested the activity of Nun on ternary elongation complexes (TECs) assembled with templates lacking the ? nut sequence. We report that Nun stabilizes both translocation states of RNAP by restricting lateral movement of TEC along the DNA register. When Nun stabilized TEC in a pretranslocated register, immediately after NMP incorporation, it prevented binding of the next NTP and stimulated pyrophosphorolysis of the nascent transcript. In contrast, stabilization of TEC by Nun in a posttranslocated register allowed NTP binding and nucleotidyl transfer but inhibited pyrophosphorolysis and the next round of forward translocation. Nun binding to and action on the TEC requires a 9-bp RNA-DNA hybrid. We observed a Nun-dependent toe print upstream to the TEC. In addition, mutations in the RNAP ?' subunit near the upstream end of the transcription bubble suppress Nun binding and arrest. These results suggest that Nun interacts with RNAP near the 5' edge of the RNA-DNA hybrid. By stabilizing translocation states through restriction of TEC lateral mobility, Nun represents a novel class of transcription arrest factors. PMID:24853501

Vitiello, Christal L; Kireeva, Maria L; Lubkowska, Lucyna; Kashlev, Mikhail; Gottesman, Max

2014-06-10

284

The 18?kDa Translocator Protein, Microglia and Neuroinflammation.  

PubMed

The 18?kDa translocator protein (TSPO), previously known as the peripheral benzodiazepine receptor, is expressed in the injured brain. It has become known as an imaging marker of "neuroinflammation" indicating active disease, and is best interpreted as a nondiagnostic biomarker and disease staging tool that refers to histopathology rather than disease etiology. The therapeutic potential of TSPO as a drug target is mostly based on the understanding that it is an outer mitochondrial membrane protein required for the translocation of cholesterol, which thus regulates the rate of steroid synthesis. This pivotal role together with the evolutionary conservation of TSPO has underpinned the belief that any loss or mutation of TSPO should be associated with significant physiological deficits or be outright incompatible with life. However, against prediction, full Tspo knockout mice are viable and across their lifespan do not show the phenotype expected if cholesterol transport and steroid synthesis were significantly impaired. Thus, the "translocation" function of TSPO remains to be better substantiated. Here, we discuss the literature before and after the introduction of the new nomenclature for TSPO and review some of the newer findings. In light of the controversy surrounding the function of TSPO, we emphasize the continued importance of identifying compounds with confirmed selectivity and suggest that TSPO expression is analyzed within specific disease contexts rather than merely equated with the reified concept of "neuroinflammation." PMID:25345894

Liu, Guo-Jun; Middleton, Ryan J; Hatty, Claire R; Kam, Winnie Wai-Ying; Chan, Ronald; Pham, Tien; Harrison-Brown, Meredith; Dodson, Eoin; Veale, Kelly; Banati, Richard B

2014-11-01

285

Controlling polymer translocation and ion transport via charge correlations  

E-print Network

We develop a correlation-corrected transport theory in order to predict ionic and polymer transport properties of membrane nanopores in physical conditions where mean-field electrostatics breaks down. The experimentally observed low KCl conductivity of open alpha-Hemolysin pores is quantitatively explained by the presence of surface polarization effects. Upon the penetration of a DNA molecule into the pore, these polarization forces combined with the electroneutrality of DNA sets a lower boundary for the ionic current, explaining the weak salt dependence of blocked pore conductivities at dilute ion concentrations. The addition of multivalent counterions into the solution results in the reversal of the polymer charge and the direction of the electroosmotic flow. With trivalent spermidine or quadrivalent spermine molecules, the charge inversion is strong enough to stop the translocation of the polymer and to reverse its motion. This mechanism can be used efficiently in translocation experiments in order to improve the accuracy of DNA sequencing by minimizing the translocation velocity of the polymer.

Sahin Buyukdagli; Tapio Ala-Nissila

2014-08-19

286

MAR Background Report MAR Background Report: Indigenous Protest in Brazil  

E-print Network

MAR Background Report MAR Background Report: Indigenous Protest in Brazil Hundreds of indigenous. According to MAR data, several violent incidents against landowners, miners and others have been observed groups worldwide #12;MAR Background Report About the Minorities at Risk Project The Minorities at Risk

Milchberg, Howard

287

MAR Background Report MAR Background Report: The Revolution in Bahrain  

E-print Network

MAR Background Report MAR Background Report: The Revolution in Bahrain Unrest in Tunisia, Egypt forces. MAR data also reports that social services in Shi'a neighborhoods are inferior to those in Sunni of ethnic groups worldwide #12;MAR Background Report In Bahrain, the freedom of press and expression

Milchberg, Howard

288

Assessing losses of genetic diversity due to translocation: long-term case histories in Merriam's turkey ( Meleagris gallopavo merriami )  

Microsoft Academic Search

Translocation is a widely used tool in wildlife management, but populations established as a result of translocations may be subject to a range of genetic problems, including loss of genetic diversity and founder effects. The genetic impact of single translocation events can be difficult to assess because of complex management histories in translocated or source populations. Here we use molecular

Karen E. Mock; E. K. Latch; O. E. Rhodes Jr

2004-01-01

289

A jumping Robertsonian translocation; a molecular and cytogenetic study  

SciTech Connect

Lejeune et al. were the first to use the term {open_quotes}translocation sauteuse{close_quotes} or jumping translocation to describe mosaicism due to the presence of multiple structural rearrangements. In this study, we report the cytogenetic and molecular analyses of a patient with mosaicism for two different Robertsonian translocations, both involving chromosome 21. The proband`s karyotype based on lymphocyte cultures is 45,XX,t(21q22q)/46,XX,-21,+i(21q21q) (98%/2%). Chromosome analysis of skin fibroblasts showed 100% of cells with a 45,XX,t(21q22q) complement. A high level of mosaicism was seen in an ovarian biopsy, where 1/3 of cells exhibited the unbalanced cell line with the 21/21 rearrangement. The proband`s pregnancy history is consistent with the high proportion of the 21/21 rearrangement in her ovary. She has had spontaneous abortions and two livebirths, both of whom are affected with Down syndrome [46,XX,-21,+i(21q21q) and 46,XY,-21,+i(21q21q)]. Analysis of cord blood cultures showed that the second child exhibits low level mosaicism for a normal cell line, which further suggests instability of the 21/21 rearrangement. FISH with alphoid probes showed that the 21/21 and 21/22 rearrangements are dicentric and that each long arm segment retains its appropriate centromere. Segregation studies using microsatellite polymorphisms indicated that the 21/21 rearrangement is an isochromosome. The same technique was used to establish that the proband`s rearrangements formed de novo from her mother`s chromosome 21. An uncommon chromosome 22p polymorphism is maternally derived and is present in the proband`s unbalanced cell line. However, this 22 is absent in the balanced 45,XX,t(21q22q) cell line of the proband because it is involved in the translocation. Therefore, we propose a model in which the i(21q) was the progenitor rearrangement and participated in subsequent nonreciprocal rearrangements characteristic of a jumping translocation.

Park, V.M.; Gross, S.J.; Tharapel, A.T. [Univ. of Tennessee, Memphis, TN (United States)] [and others

1994-09-01

290

Complex Y-linked translocations in Delia antiqua produced by irradiation of a fertile Y-linked translocation  

Microsoft Academic Search

In the onion fly, Delia antiqua. a fertile, Y-linked translocation involving chromosomes Y and 2 was irradiated with fast neutrons to induce new complexes involving the Y-chromosome. This chromosome is male determining in the onion fly. Such complexes can be used for the development of genetic sexing systems and also for the introduction of sterility into field populations following release.Irradiation

Alan S Robinson; Kees van Heemert

1981-01-01

291

Direction Finding Algorithm with Virtual Antenna Array Background  

E-print Network

antennas are virtually implemented for DF algorithm, by sliding 2 antennas along the same line (Figure;Frequency Domain Eye Diagram for Orthogonal Frequency-Division Multiplexing Background: In conventional single-carrier communication systems, investigation of the signals along with multipath channel

Arslan, Hüseyin

292

Background issues for defensive interceptors.  

National Technical Information Service (NTIS)

Mean nuclear backgrounds are large, but are arguably amenable to frame-to-frame subtraction. Striated backgrounds on the sensors for defensive interceptors could, however, cause clutter leak-through, which could make detection and track difficult. Nominal...

G. H. Canavan

1991-01-01

293

p38 Mitogen-activated protein kinase regulates Bax translocation in cyanide-induced apoptosis.  

PubMed

Execution of cyanide-induced apoptosis is mediated by release of cytochrome c from mitochondria. To determine how cyanide initiates cytochrome c release, Bax translocation was investigated in primary cultures of cortical neurons. Under nonapoptotic (control) conditions, Bax resided predominantly in the cytoplasm. After 300-microM cyanide treatment for 1 h, Bax translocated to the mitochondria, as shown by immunocytochemical staining and subcellular fractionation; Western blot analysis confirmed "cytosol-to-mitochondria" translocation of Bax. Temporal analysis showed that Bax translocation preceded cytochrome c release from the mitochondria, which was initiated 3 h after cyanide treatment. In double-immunofluorescence labeling for both Bax and cytochrome c, it was observed that cytochrome c was released only in cells showing Bax in mitochondria. The role of p38 mitogen-activated protein (MAP) kinase in Bax translocation was studied. The p38 MAP kinase was activated 30 min after cyanide, and its phosphorylation level of activity began to decrease 3 h later. SB203580, a p38 MAP kinase inhibitor, blocked translocation of Bax to mitochondria, whereas SB202474, a control peptide, had no effect on translocation. Inhibition of p38 MAP kinase by SB203580 blocked all downstream effects of Bax translocation, including cytochrome c release, caspase activation, and internucleosomal DNA fragmentation. These results demonstrated that Bax translocation is critical for cyanide-induced cytochrome c release and that p38 MAP kinase regulates Bax translocation from cytosol to mitochondria. PMID:12805646

Shou, Y; Li, L; Prabhakaran, K; Borowitz, J L; Isom, G E

2003-09-01

294

Internal and External Radioactive Backgrounds  

E-print Network

Chapter 3 Internal and External Radioactive Backgrounds New physics is often discovered by pushing of the low energies involved. There are many radioactive elements that have decays at lower energies which;Chapter 3: Internal and External Radioactive Backgrounds 104 the rate of background. High-energy neutrino

295

REPORT NO. 5 background material  

E-print Network

REPORT NO. 5 background material for the development of radiation protection standards July 1964 Staff Report of the FEDERAL RADIATION COUNCIL #12;REPORT NO. 5 background material for the development INTRODUCTION This report contains background material used in the development of guidance for Federal agencies

296

Voltage-driven translocation of DNA through a high throughput conical solid-state nanopore.  

PubMed

Nanopores have become an important tool for molecule detection at single molecular level. With the development of fabrication technology, synthesized solid-state membranes are promising candidate substrates in respect of their exceptional robustness and controllable size and shape. Here, a 30-60 (tip-base) nm conical nanopore fabricated in 100 nm thick silicon nitride (Si(3)N(4)) membrane by focused ion beam (FIB) has been employed for the analysis of ?-DNA translocations at different voltage biases from 200 to 450 mV. The distributions of translocation time and current blockage, as well as the events frequencies as a function of voltage are investigated. Similar to previously published work, the presence and configurations of ?-DNA molecules are characterized, also, we find that greater applied voltages markedly increase the events rate, and stretch the coiled ?-DNA molecules into linear form. However, compared to 6-30 nm ultrathin solid-state nanopores, a threshold voltage of 181 mV is found to be necessary to drive DNA molecules through the nanopore due to conical shape and length of the pore. The speed is slowed down ?5 times, while the capture radius is ?2 fold larger. The results show that the large nanopore in thick membrane with an improved stability and throughput also has the ability to detect the molecules at a single molecular level, as well as slows down the velocity of molecules passing through the pore. This work will provide more motivations for the development of nanopores as a Multi-functional sensor for a wide range of biopolymers and nano materials. PMID:23029365

Liu, Quanjun; Wu, Hongwen; Wu, Lingzhi; Xie, Xiao; Kong, Jinglin; Ye, Xiaofeng; Liu, Liping

2012-01-01

297

Voltage-Driven Translocation of DNA through a High Throughput Conical Solid-State Nanopore  

PubMed Central

Nanopores have become an important tool for molecule detection at single molecular level. With the development of fabrication technology, synthesized solid-state membranes are promising candidate substrates in respect of their exceptional robustness and controllable size and shape. Here, a 30–60 (tip-base) nm conical nanopore fabricated in 100 nm thick silicon nitride (Si3N4) membrane by focused ion beam (FIB) has been employed for the analysis of ?-DNA translocations at different voltage biases from 200 to 450 mV. The distributions of translocation time and current blockage, as well as the events frequencies as a function of voltage are investigated. Similar to previously published work, the presence and configurations of ?-DNA molecules are characterized, also, we find that greater applied voltages markedly increase the events rate, and stretch the coiled ?-DNA molecules into linear form. However, compared to 6–30 nm ultrathin solid-state nanopores, a threshold voltage of 181 mV is found to be necessary to drive DNA molecules through the nanopore due to conical shape and length of the pore. The speed is slowed down ?5 times, while the capture radius is ?2 fold larger. The results show that the large nanopore in thick membrane with an improved stability and throughput also has the ability to detect the molecules at a single molecular level, as well as slows down the velocity of molecules passing through the pore. This work will provide more motivations for the development of nanopores as a Multi-functional sensor for a wide range of biopolymers and nano materials. PMID:23029365

Liu, Quanjun; Wu, Hongwen; Wu, Lingzhi; Xie, Xiao; Kong, Jinglin; Ye, Xiaofeng; Liu, Liping

2012-01-01

298

Tyrosine kinase chromosomal translocations mediate distinct and overlapping gene regulation events  

PubMed Central

Background Leukemia is a heterogeneous disease commonly associated with recurrent chromosomal translocations that involve tyrosine kinases including BCR-ABL, TEL-PDGFRB and TEL-JAK2. Most studies on the activated tyrosine kinases have focused on proximal signaling events, but little is known about gene transcription regulated by these fusions. Methods Oligonucleotide microarray was performed to compare mRNA changes attributable to BCR-ABL, TEL-PDGFRB and TEL-JAK2 after 1 week of activation of each fusion in Ba/F3 cell lines. Imatinib was used to control the activation of BCR-ABL and TEL-PDGFRB, and TEL-JAK2-mediated gene expression was examined 1 week after Ba/F3-TEL-JAK2 cells were switched to factor-independent conditions. Results Microarray analysis revealed between 800 to 2000 genes induced or suppressed by two-fold or greater by each tyrosine kinase, with a subset of these genes commonly induced or suppressed among the three fusions. Validation by Quantitative PCR confirmed that eight genes (Dok2, Mrvi1, Isg20, Id1, gp49b, Cxcl10, Scinderin, and collagen V?1(Col5a1)) displayed an overlapping regulation among the three tested fusion proteins. Stat1 and Gbp1 were induced uniquely by TEL-PDGFRB. Conclusions Our results suggest that BCR-ABL, TEL-PDGFRB and TEL-JAK2 regulate distinct and overlapping gene transcription profiles. Many of the genes identified are known to be involved in processes associated with leukemogenesis, including cell migration, proliferation and differentiation. This study offers the basis for further work that could lead to an understanding of the specificity of diseases caused by these three chromosomal translocations. PMID:22204395

2011-01-01

299

Overexpression of full-length ETV1 transcripts in clinical prostate cancer due to gene translocation.  

PubMed

ETV1 is overexpressed in a subset of clinical prostate cancers as a fusion transcript with many different partners. However, ETV1 can also be overexpressed as a full-length transcript. Full-length ETV1 protein functions differently from truncated ETV1 produced by fusion genes. In this study we describe the genetic background of full-length ETV1 overexpression and the biological properties of different full-length ETV1 isoforms in prostate cancer. Break-apart FISH showed in five out of six patient samples with overexpression of full-length ETV1 a genomic rearrangement of the gene, indicating frequent translocation. We were able to study the rearrangements in more detail in two tumors. In the first tumor 5'-RACE on cDNA showed linkage of the complete ETV1 transcript to the first exon of a prostate-specific two exon ncRNA gene that maps on chromosome 14 (EST14). This resulted in the expression of both full-length ETV1 transcripts and EST14-ETV1 fusion transcripts. In chromosome spreads of a xenograft derived from the second prostate cancer we observed a complex ETV1 translocation involving a chromosome 7 fragment that harbors ETV1 and fragments of chromosomes 4 and 10. Further studies revealed the overexpression of several different full-length transcripts, giving rise to four protein isoforms with different N-terminal regions. Even the shortest isoform synthesized by full-length ETV1 stimulated in vitro anchorage-independent growth of PNT2C2 prostate cells. This contrasts the lack of activity of even shorter N-truncated ETV1 produced by fusion transcripts. Our findings that in clinical prostate cancer overexpression of full-length ETV1 is due to genomic rearrangements involving different chromosomes and the identification of a shortened biologically active ETV1 isoform are highly relevant for understanding the mechanism of ETV1 function in prostate cancer. PMID:21298110

Gasi, Delila; van der Korput, Hetty A; Douben, Hannie C; de Klein, Annelies; de Ridder, Corrina M; van Weerden, Wytske M; Trapman, Jan

2011-01-01

300

HMGB1 neutralization is associated with bacterial translocation during acetaminophen hepatotoxicity  

PubMed Central

Background Acetaminophen (APAP) hepatotoxicity is associated with a high rate of gram-negative enteric bacterial infection; however, the underlying mechanism is still unknown. APAP overdose induces massive hepatocyte necrosis, necrotic tissue releases high mobility group B1 (HMGB1) and exogenous HMGB1 is able to induce gut bacterial translocation (BT) in normal mice; therefore, it is possible that HMGB1 mediates gut BT in APAP hepatotoxicity. This study aims to test this hypothesis by using anti-HMGB1 neutralizing antibody to treat APAP overdose for 24-48 hours. Methods Male C57BL/6 mice were intraperitoneally (i.p.) injected with a single dose of APAP (350 mg/kg dissolved in 1 mL sterile saline). 2 hrs after APAP injection, the APAP challenged mice were randomized to receive treatment with either anti-HMGB1 antibody (400 ?g per dose) or non-immune (sham) IgG every 24 h for a total of 2 doses. Results 24 and 48 hrs after APAP challenge, anti-HMGB1 treatment instead of sham IgG therapy significantly decreased serum HMGB1 concentrations and reduced BT by 85%; serum HMGB1 levels were positively correlated with the amount of BT; anti-HMGB1 therapy decreased hepatic BT at 48 h, which was associated with better recovered liver structure and better restored hepatic immune system that was shown by enhanced hepatic mRNA expression of TNF-?, IL-6 and extensive proliferation of inflammatory and reticuloendothelial cells; however, anti-HMGB1 treatment did not decrease gut mucosal permeability as compared to the sham IgG therapy at either 24 or 48 hrs. Conclusion HMGB1 neutralization is associated with bacterial translocation during APAP hepatotoxicity. PMID:24708589

2014-01-01

301

Translocation of Inhaled Ultrafine Manganese Oxide Particles to the Central Nervous System  

PubMed Central

Background Studies in monkeys with intranasally instilled gold ultrafine particles (UFPs; < 100 nm) and in rats with inhaled carbon UFPs suggested that solid UFPs deposited in the nose travel along the olfactory nerve to the olfactory bulb. Methods To determine if olfactory translocation occurs for other solid metal UFPs and assess potential health effects, we exposed groups of rats to manganese (Mn) oxide UFPs (30 nm; ~ 500 ?g/m3) with either both nostrils patent or the right nostril occluded. We analyzed Mn in lung, liver, olfactory bulb, and other brain regions, and we performed gene and protein analyses. Results After 12 days of exposure with both nostrils patent, Mn concentrations in the olfactory bulb increased 3.5-fold, whereas lung Mn concentrations doubled; there were also increases in striatum, frontal cortex, and cerebellum. Lung lavage analysis showed no indications of lung inflammation, whereas increases in olfactory bulb tumor necrosis factor-? mRNA (~ 8-fold) and protein (~ 30-fold) were found after 11 days of exposure and, to a lesser degree, in other brain regions with increased Mn levels. Macrophage inflammatory protein-2, glial fibrillary acidic protein, and neuronal cell adhesion molecule mRNA were also increased in olfactory bulb. With the right nostril occluded for a 2-day exposure, Mn accumulated only in the left olfactory bulb. Solubilization of the Mn oxide UFPs was < 1.5% per day. Conclusions We conclude that the olfactory neuronal pathway is efficient for translocating inhaled Mn oxide as solid UFPs to the central nervous system and that this can result in inflammatory changes. We suggest that despite differences between human and rodent olfactory systems, this pathway is relevant in humans. PMID:16882521

Elder, Alison; Gelein, Robert; Silva, Vanessa; Feikert, Tessa; Opanashuk, Lisa; Carter, Janet; Potter, Russell; Maynard, Andrew; Ito, Yasuo; Finkelstein, Jacob; Oberdorster, Gunter

2006-01-01

302

Systemic Immune Activation and Microbial Translocation in Dual HIV/Tuberculosis-Infected Subjects  

PubMed Central

Background.?Systemic immune activation is a strong predictor of progression of human immunodeficiency virus type 1 (HIV-1) disease and a prominent feature of infection with Mycobacterium tuberculosis. Objective.?To understand the role of systemic immune activation and microbial translocation in HIV/tuberculosis dually infected patients over the full spectrum of HIV-1 immunodeficiency, we studied circulating sCD14 and lipopolysaccharide (LPS) and their relationship to HIV-1 activity. Methods.?Two cohorts of HIV/tuberculosis subjects defined by CD4 T-cell count at time of diagnosis of tuberculosis were studied: those with low (<350/?L) and those with high (?350/?L) CD4 T-cell count. Circulating soluble CD14 (sCD14) and LPS were assessed. Results.?Levels of sCD14 were higher in HIV/tuberculosis with high (?350/?L) as compared to low CD4 T-cell count (P < .001). Whereas sCD14 levels remained elevated in HIV/tuberculosis subjects with lower CD4 T-cell counts despite treatment of tuberculosis, in HIV/tuberculosis patients with higher CD4 T-cell count (?350/?L), levels declined regardless of whether highly active antiretroviral therapy (HAART) was included with the anti-tuberculosis regimen. Circulating LPS levels in HIV/tuberculosis patients with CD4 T-cell count ?350/?L were unaffected by treatment of tuberculosis with or without HAART. Conclusion.?During HIV/tuberculosis, systemic immune activation is dissociated from microbial translocation. Changes in circulating sCD14 and LPS are dependent on CD4 T-cell count. PMID:23479321

Toossi, Zahra; Funderburg, Nicholas T.; Sirdeshmuk, Sohani; Whalen, Christopher C.; Nanteza, Maria W.; Johnson, Denise F.; Mayanja-Kizza, Harriet; Hirsch, Christina S.

2013-01-01

303

Stabilization of Dicentric Translocations through Secondary Rearrangements Mediated by Multiple Mechanisms in S. cerevisiae  

PubMed Central

Background The gross chromosomal rearrangements (GCRs) observed in S. cerevisiae mutants with increased rates of accumulating GCRs include predicted dicentric GCRs such as translocations, chromosome fusions and isoduplications. These GCRs resemble the genome rearrangements found as mutations underlying inherited diseases as well as in the karyotypes of many cancers exhibiting ongoing genome instability Methodology/Principal Findings The structures of predicted dicentric GCRs were analyzed using multiple strategies including array-comparative genomic hybridization, pulse field gel electrophoresis, PCR amplification of predicted breakpoints and sequencing. The dicentric GCRs were found to be unstable and to have undergone secondary rearrangements to produce stable monocentric GCRs. The types of secondary rearrangements observed included: non-homologous end joining (NHEJ)-dependent intramolecular deletion of centromeres; chromosome breakage followed by NHEJ-mediated circularization or broken-end fusion to another chromosome telomere; and homologous recombination (HR)-dependent non-reciprocal translocations apparently mediated by break-induced replication. A number of these GCRs appeared to have undergone multiple bridge-fusion-breakage cycles. We also observed examples of chromosomes with extensive ongoing end decay in mec1 tlc1 mutants, suggesting that Mec1 protects chromosome ends from degradation and contributes to telomere maintenance by HR. Conclusions/Significance HR between repeated sequences resulting in secondary rearrangements was the most prevalent pathway for resolution of dicentric GCRs regardless of the structure of the initial dicentric GCR, although at least three other resolution mechanisms were observed. The resolution of dicentric GCRs to stable rearranged chromosomes could in part account for the complex karyotypes seen in some cancers. PMID:19636429

Pennaneach, Vincent; Kolodner, Richard D.

2009-01-01

304

Background  

E-print Network

This Provisional PDF corresponds to the article as it appeared upon acceptance. Fully formatted PDF and full text (HTML) versions will be made available soon. Embryonic diapause in humans: time to consider?

Grazyna E Ptak; Jacek A Modlinski; Grazyna E Ptak; Jacek A Modlinski; Pasqualino Loi

2013-01-01

305

Background  

E-print Network

Obligate intracellular bacteria commonly have much reduced genome sizes compared to their nearest free-living relatives. One reason for this is reductive evolution: the loss of genes rendered non-essential due to the intracellular habitat. This can occur because of the presence of orthologous genes in the host, combined with the ability of the bacteria to import the protein or metabolite products of the host genes. In this article we take a look at three such bacteria whose genomes have been fully sequenced. Buchnera is an endosymbiont of the pea aphid, Acyrthosiphon pisum, the relationship between these two organisms being so essential that neither can reproduce in the absence of the other. Rickettsia prowazekii is the causative agent of louse-borne typhus in humans and Mycobacterium leprae infection of humans leads to leprosy. Both of these human pathogens have fastidious growth requirements, which has made them very difficult to

Comp Funct Genom; Jo Wixon

306

Background  

E-print Network

OCA is a group of autosomal recessive disorders characterized by hypopigmentation and abnormalities related to ocular development. Mutations in genes regulating melanin-biosynthesis cause four classical types of OCA (OCA 1-4). The clinical spectrum of OCA often depends on the pigmentation threshold of a patient, highlighting the importance of ethnic- specific SNPs. We aimed to understand the molecular bases of OCA in India, where it is one of the four major causes of childhood blindness. Materials and methods Blood samples were collected from OCA patients and family members, mostly from eastern and southern India. Seven pigmentation related genes were screened for variations. Relevant non-synonymous changes in tyrosinase (TYR) were functionally validated. Eighteen SNPs from three OCA genes were genotyped in 552 normal individuals covering various ethnic groups of India. Results Our data suggest that defects in TYR cause albinism in 58 % (36/62) of the cases [1] (and unpublished data; see Figure 1). Functional assays with missense mutations proved that none of mutants are enzymatically active and are retained in the endoplasmic reticulum [1]. Screening of the remaining cases (43%) revealed OCA2 to be the second common locus followed by SLC45A2 [2] (Figure 1). Evaluation of SNPs in TYR, OCA2 and SLC45A2 in normal population suggested definitive bias for some of the SNPs towards specific populations.

Kunal Ray; Mainak Sengupta; Moumita Chaki; Maitreyee Mondal; Swapan Samanta

307

Background  

Cancer.gov

The discovery that proteins and peptides are "leaked" by tumors into clinically accessible bodily fluids such as blood has led to the possibility of diagnosing cancer at an early stage or monitoring response to treatment by collecting these fluids and testing for the presence of cancer-related biomarkers. Prostate-specific antigen (PSA) and cancer antigen 125 (CA-125) are examples of blood-borne cancer protein biomarkers that are currently being used in the clinic.

308

Akt phosphorylation is essential for nuclear translocation and retention in NGF-stimulated PC12 cells  

SciTech Connect

Nerve growth factor (NGF) elicits Akt translocation into the nucleus, where it phosphorylates nuclear targets. Here, we describe that Akt phosphorylation can promote the nuclear translocation of Akt and is necessary for its nuclear retention. Overexpression of Akt-K179A, T308A, S473A-mutant failed to show either nuclear translocation or nuclear Akt phosphorylation, whereas expression of wild-type counterpart elicited profound Akt phosphorylation and induced nuclear translocation under NGF stimulation. Employing the PI3K inhibitor and a variety of mutants PI3K, we showed that nuclear translocation of Akt was mediated by activation of PI3K, and Akt phosphorylation status in the nucleus required PI3K activity. Thus the activity of PI3K might contribute to the nuclear translocation of Akt, and that Akt phosphorylation is essential for its nuclear retention under NGF stimulation conditions.

Truong Le Xuan Nguyen [Department of Molecular Cell Biology, Center for Molecular Medicine, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon 440-746 (Korea, Republic of); Choi, Joung Woo [Department of Molecular Cell Biology, Center for Molecular Medicine, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon 440-746 (Korea, Republic of); Lee, Sang Bae [Department of Molecular Cell Biology, Center for Molecular Medicine, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon 440-746 (Korea, Republic of); Ye, Keqiang [Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30322 (United States); Woo, Soo-Dong [Department of Plant Medicine, College of Agriculture, Life and Environment Sciences, Chungbuk National University, Cheongju 361-763 (Korea, Republic of); Lee, Kyung-Hoon [Department of Anatomy, Sungkyunkwan University School of Medicine, Suwon 440-746 (Korea, Republic of); Ahn, Jee-Yin [Department of Molecular Cell Biology, Center for Molecular Medicine, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon 440-746 (Korea, Republic of)]. E-mail: jyahn@med.skku.ac.kr

2006-10-20

309

Use of chromosome translocations for measuring prior environment exposures in humans  

SciTech Connect

Recent advances in cytogenetic methodology are beginning to have a major impact upon our ability to provide assessments of environmental exposure in humans. The advent of fluorescent-based techniques for `painting` whole chromosomes has made the analysis of chromosome translocations rapid, specific, sensitive and routine. Chromosome painting has been used to address a wide variety of scientific questions, resulting in an increased understanding of the biological consequences of adverse environmental exposure. This paper describes the use of chromosome translocations as a biological marker of exposure and effect in humans. The relevance of translocations is discussed, as are the advantages and disadvantages of painting compared to classical cytogenetic methods for translocation evaluation. The factors to consider in the use of translocations as a retrospective indicator of exposure are then described. Several theoretical parameters that are important to the use of translocations are provided, and the paper concludes with a vision for the future of cytogenetic methodology.

Tucker, J. D.

1997-05-01

310

Translocation dynamics of freely jointed Lennard-Jones chains into adsorbing pores.  

PubMed

Polymer translocation into adsorbing nanopores is studied by using the Fokker-Planck equation of chain diffusion along the energy landscape calculated with Monte Carlo simulations using the incremental gauge cell method. The free energy profile of a translocating chain was found by combining two independent sub-chains, one free but tethered to a hard wall, and the other tethered inside an adsorbing pore. Translocation dynamics were revealed by application of the Fokker-Planck equation for normal diffusion. Adsorption of polymer chains into nanopores involves a competition of attractive adsorption and repulsive steric hindrance contributions to the free energy. Translocation times fell into two regimes depending on the strength of the adsorbing pore. In addition, we found a non-monotonic dependence of translocation times with increasing adsorption strength, with sharp peak associated with local free energy minima along the translocation coordinate. PMID:23061861

Rasmussen, Christopher J; Vishnyakov, Aleksey; Neimark, Alexander V

2012-10-14

311

Scaling exponents of Forced Polymer Translocation through a nano-pore  

E-print Network

We investigate several scaling properties of a translocating homopolymer through a thin pore driven by an external field present inside the pore only using Langevin Dynamics (LD) simulation in three dimension (3D). Specifically motivated by several recent theoretical and numerical studies that are apparently at odds with each other, we determine the chain length dependence of the scaling exponents of the average translocation time, the average velocity of the center of mass, $$, the effective radius of gyration during the translocation process, and the scaling exponent of the translocation coordinate ($s$-coordinate) as a function of the translocation time. We further discuss the possibility that in the case of driven translocation the finite pore size and its geometry could be responsible that the veclocity scaling exponent is less than unity and discuss the dependence of the scaling exponents on the pore geometry for the range of $N$ studied here.

Aniket Bhattacharya; William H. Morrison; Kaifu Luo; Tapio Ala-Nissila; See-Chen Ying; Andrey Milchev; Kurt Binder

2008-08-13

312

Proton translocation coupled to quinol oxidation in ox heart mitochondria  

PubMed Central

The suitability of ubiquinol1 and duroquinol as pulse reductants for initiating respirationdriven proton translocation by aerobic ox heart mitochondria was investigated. At 25°C the Vmax. for oxidation was close to 280nmol of quinol oxidized/min per mg of protein, and the Km values were 8?m for ubiquinol1 and 28?m for duroquinol. Pulses of ubiquinol1 and duroquinol were rapidly and completely oxidized by aerobic mitochondria with a simultaneous acidification of the suspending medium as detected with a glass electrode. The ?H+/2e? ratios (Mitchell, 1966) calculated from the observed extent of acidification and the amount of quinol added were 3.62 for ubiquinol1 and 2.98 for duroquinol. These values are underestimates of the true value owing to proton back-flow across the membrane. An analogue computer model was used to correct the observed extent of respirationdriven acidification for proton back-flow. The corrected ?H+/2e? values were 4.01 for ubiquinol and 3.86 for duroquinol oxidation. Attempts to measure the rate of proton translocation with a pH-measuring system with a response time of 0.4s were not entirely satisfactory, owing to the relative slowness of the electrode response. Nevertheless the maximal rate of proton generation during ubiquinol1 oxidation was about 1200ng-ions of H+/min per mg of mitochondrial protein. It is concluded, contrarily to Chance & Mela (1967), that mitochondria exhibit a proton-translocating ubiquinol oxidase activity with a ?H+/2e? ratio of 4.0. PMID:4780696

Lawford, Hugh G.; Garland, Peter B.

1973-01-01

313

Mitochondrial Function in Antarctic Nototheniids with ND6 Translocation  

PubMed Central

Fish of the suborder Notothenioidei have successfully radiated into the Southern Ocean and today comprise the dominant fish sub-order in Antarctic waters in terms of biomass and species abundance. During evolution in the cold and stable Antarctic climate, the Antarctic lineage of notothenioids developed several unique physiological adaptations, which make them extremely vulnerable to the rapid warming of Antarctic waters currently observed. Only recently, a further phenomenon exclusive to notothenioid fish was reported: the translocation of the mitochondrial gene encoding the NADH Dehydrogenase subunit 6 (ND6), an indispensable part of complex I in the mitochondrial electron transport system. This study investigated the potential physiological consequences of ND6 translocation for the function and thermal sensitivity of the electron transport system in isolated liver mitochondria of the two nototheniid species Notothenia coriiceps and Notothenia rossii, with special attention to the contributions of complex I (NADH DH) and complex II (Succinate DH) to oxidative phosphorylation. Furthermore, enzymatic activities of NADH?Cytochrome c Oxidoreductase and Cytochrome C Oxidase were measured in membrane-enriched tissue extracts. During acute thermal challenge (0–15°C), capacities of mitochondrial respiration and enzymatic function in the liver could only be increased until 9°C. Mitochondrial complex I (NADH Dehydrogenase) was fully functional but displayed a higher thermal sensitivity than the other complexes of the electron transport system, which may specifically result from its unique amino acid composition, revealing a lower degree of stability in notothenioids in general. We interpret the translocation of ND6 as functionally neutral but the change in amino acid sequence as adaptive and supportive of cold stenothermy in Antarctic nototheniids. From these findings, an enhanced sensitivity to ocean warming can be deduced for Antarctic notothenioid fish. PMID:22363756

Mark, Felix C.; Lucassen, Magnus; Strobel, Anneli; Barrera-Oro, Esteban; Koschnick, Nils; Zane, Lorenzo; Patarnello, Tomaso; Portner, Hans O.; Papetti, Chiara

2012-01-01

314

Discriminability measures for predicting readability of text on textured backgrounds  

NASA Technical Reports Server (NTRS)

Several discriminability measures were examined for their ability to predict reading search times for three levels of text contrast and a range of backgrounds (plain, a periodic texture, and four spatial-frequency-filtered textures created from the periodic texture). Search times indicate that these background variations only affect readability when the text contrast is low, and that spatial frequency content of the background affects readability. These results were not well predicted by the single variables of text contrast (Spearman rank correlation = -0.64) and background RMS contrast (0.08), but a global masking index and a spatial-frequency-selective masking index led to better predictions (-0.84 and -0.81, respectively). c2000 Optical Society of America.

Scharff, L. F.; Hill, A. L.; Ahumada, A. J. Jr; Watson, A. B. (Principal Investigator)

2000-01-01

315

Fabrication of Electrically Addressable Nanopore Arrays for DNA Translocation Studies  

NASA Astrophysics Data System (ADS)

We will present a novel method of fabricating the nanopore arrays in the range of 10 20 nm size utilizing Si processing. Using e-beam lithography and anisotropic wet etching with KOH, we make a series of V-grooves on the top of the wafer and one at the right angle on the bottom surface. This opens up a series of nanopores. The unique feature of electrically addressable nanopore arrays (EANA) allows us to control the ionic solution flow and detect DNA translocations in each pore independently. Preliminary results of application of EANA device for studying biomolecules will be shown. This work is supported by NSF-NER-0304325.

Ryul Park, Sang; Ling, X. S.

2004-03-01

316

Carbon Dioxide Concentration at Night Affects Translocation from Soybean Leaves  

PubMed Central

Studies have indicated that the concentration of carbon dioxide [CO2] during the dark period may influence plant dry matter accumulation. It is often suggested that these effects on growth result from effects of [CO2] on rates of respiration, but responses of respiration to [CO2] remain controversial, and connections between changes in respiration rate and altered growth rate have not always been clear. The present experiments tested whether translocation, a major consumer of energy from respiration in exporting leaves, was sensitive to [CO2]. Nineteen?day?old soybean plants grown initially at a constant [CO2] of 350 µmol mol–1 were exposed to three consecutive nights with a [CO2] of 220–1400 µmol mol–1, with a daytime [CO2] of 350 µmol mol–1. Change in dry mass of the individual second, third and fourth trifoliate leaves over the 3?d period was determined, along with rates of respiration and photosynthesis of second leaves, measured by net CO2 exchange. Translocation was determined from mass balance for second leaves. Additional experiments were conducted where the [CO2] around individual leaves was controlled separately from that of the rest of the plant. Results indicated that low [CO2] at night increased both respiration and translocation and elevated [CO2] decreased both processes, to similar relative extents. The effect of [CO2] during the dark on the change in leaf mass over 3 d was largest in second leaves, where the change in mass was about 50 % greater at 1400 µmol mol–1 CO2 than at 220 µmol mol–1 CO2. The response of translocation to [CO2] was localized in individual leaves. Results indicated that effects of [CO2] on net carbon dioxide exchange rate in the dark either caused or reflected a change in a physiologically important process which is known to depend on energy supplied by respiration. Thus, it is unlikely that the observed effects of [CO2] on respiration were artefacts of the measurement process in this case. PMID:12234152

BUNCE, JAMES A.

2002-01-01

317

Modeling the mechanochemistry of the ?29 DNA translocation motor  

NASA Astrophysics Data System (ADS)

We present a study of the DNA translocation of the bacteriophage ?29 packaging molecular motor. From the available experimental information we present a model system based on a stochastic flashing potential, which reproduces the experimental observations such as detailed trajectories, steps and substeps, spatial correlation, and velocity. Moreover, the model allows the evaluation of the power and efficiency of this motor. We have found that the maximum power regime does not correspond with that of the maximum efficiency. This information can stimulate further experiments.

Perez-Carrasco, R.; Fiasconaro, A.; Falo, F.; Sancho, J. M.

2013-03-01

318

Hyperthermia increases gamma-ray and fission neutron-induced translocations in Drosophila  

SciTech Connect

Hyperthermia has been reported in Drosophila melanogaster to increase radiation-induced chromosome rearrangements, chromosome loss, recessive and dominant lethals. To determine whether hyperthermia would also affect high linear energy transfer (LET)-induced genetic damage such as translocations, which involve breakage and reunion of chromosomes, a genetic system was employed not only allowing detection of ordinary 2;3 translocations, but also permitting a more accurate measure of Y-autosome translocations.

Mittler, S.

1984-01-01

319

DNA Translocation Dependence on Ionic Solution Concentration in a Solid-State Nanopore Device  

NASA Astrophysics Data System (ADS)

Our work describes dsDNA translocations through a silicon nitride nanopore subjected to an applied electric field in solutions of different ionic strengths. We demonstrate how the ion concentration affects DNA shielding and, consequently, its effective negative charge. These modifications alter key parameters of the translocation process, such as the dwell time and current drop of the event. In this way, the DNA/salt interaction process can be explored by translocation experiments.

Thomas, Brian; Fologea, Daniel; Li, Jiali

2006-03-01

320

S-nitrosylated GAPDH initiates apoptotic cell death by nuclear translocation following Siah1 binding  

Microsoft Academic Search

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) influences cytotoxicity, translocating to the nucleus during apoptosis. Here we report a signalling pathway in which nitric oxide (NO) generation that follows apoptotic stimulation elicits S-nitrosylation of GAPDH, which triggers binding to Siah1 (an E3 ubiquitin ligase), nuclear translocation and apoptosis. S-nitrosylation of GAPDH augments its binding to Siah1, whose nuclear localization signal mediates translocation of GAPDH.

Makoto R. Hara; Nishant Agrawal; Sangwon F. Kim; Matthew B. Cascio; Masahiro Fujimuro; Yuji Ozeki; Masaaki Takahashi; Jaime H. Cheah; Stephanie K. Tankou; Lynda D. Hester; Christopher D. Ferris; S. Diane Hayward; Solomon H. Snyder; Akira Sawa

2005-01-01

321

Translocation of 14C in the Sugarcane Plant During the Day and Night 1  

PubMed Central

The time-course of translocation of 14C from the blades of the sugarcane plant was investigated by analysis and radioactive counting of successive samples punched from a single blade. In 1 experiment, the time-course was studied by determining the specific activity of the carbon dioxide respired by the roots. The rate of translocation, expressed as percentage, was highest immediately after the application of the radioactive carbon dioxide. Morning-made photosynthate translocated a higher percentage during the morning than during the afternoon in 90-minute periods in the light. Afternoon-made photosynthate translocated as well or better than morning-made photosynthate for the first hour in the light. The leaf-disk data and the specific activity of the carbon dioxide respired by the roots corresponded by showing lower rates of translocation by night than by day for several successive days. Also, the translocation of 12C sucrose was slower at night. The 14C sucrose translocated by day was made primarily by photosynthesis; the sucrose translocated by night was made primarily by the conversion of other labeled compounds, e.g. organic acids, organic phosphates, and insoluble residue. The radioactive constituent of the residue, which was converted to sucrose, was tentatively identified as a glucose-xylose-glucuronic acid hemicellulose, with most or all of the 14C in the glucose moiety. Translocation of sucrose may be triggered by different mechanisms during the night than the day. The conversion of insoluble residue to sucrose by increasing the osmotic potential at the source would favor a pressure-flow mechanism for nocturnal translocation; whereas translocation by day is thought to be a process of phototranslocation, a photoactivation of the translocation mechanism. PMID:16656489

Hartt, Constance E.; Kortschak, Hugo P.

1967-01-01

322

Highly sensitive measurement of single DNA translocation through an ultraviolet light spot on silicon nanopore  

NASA Astrophysics Data System (ADS)

Nanopore-based sensing is an attractive candidate for developing single-molecule DNA sequencing technology. Recently, optical detection with a parallel nanopore array has been demonstrated. Although this method is a promising approach to develop high thorough-put measurement, the approach requires observation at low-background condition. In this paper, we propose a new optical method for nanopore DNA sequencing with high resolution and a high signal-tonoise ratio. We use ultraviolet light for the excitation of a fluorescent probe and a nanopore in a silicon membrane. Because silicon has a large refractive index and an extinction coefficient at ultraviolet wavelengths, light transmission thorough the membrane is negligible. This contributes to low background measurement of fluorescence from fluorophore-labeled DNA strands. In addition, the z-polarization component of the electric field is attributed to generating a large electric field gradient at the nanopore exit due to its boundary condition at the silicon surface. Our numerical electromagnetic simulation revealed that the z-component electric field was dominant compared to the xcomponent electric filed. The intensity of the electric field increased steeply in 2 nm, when ultraviolet light of 375nm wavelength was focused on a 10nm-thick silicon membrane with a 7 nm-diameter nanopore. This steeply increasing electric field can be sufficient resolution for the sequencing of designed DNA polymer. Finally, our experimental results demonstrated optical detection of single DNA translocation events with a high signal-to-noise ratio under applied voltage.

Yamazaki, Hirohito; Kimura, Shinji; Tsukahara, Mutsumi; Ito, Shintaro; Esashika, Keiko; Saiki, Toshiharu

2014-02-01

323

Unstable familial translocations: A t(11;22)mat inherited as a t(11;15).  

PubMed Central

Unusual inheritance of a reciprocal translocation, t(11;22)(p11;p12)mat was discovered in a family with one daughter having a different translocation, t(11;15)(p11;p12). Another daughter inherited the same translocation as her mother. The breakpoints through the nucleolar organizing regions (NORs) of chromosomes 15 and 22 were determined by silver staining. A review of the literature has demonstrated that such unstable familial translocations are very rare and can occur either in mitosis or meiosis. They usually involve exchanges between centromeres, telomeres, or NORs. Images Fig. 2 Fig. 3 PMID:7294023

Tomkins, D J

1981-01-01

324

Dynamics of Forward and Backward Translocation of mRNA in the Ribosome  

PubMed Central

Translocation of the mRNA-tRNA complex in the ribosome, which is catalyzed by elongation factor EF-G, is one of critical steps in the elongation cycle of protein synthesis. Besides this conventional forward translocation, the backward translocation can also occur, which can be catalyzed by elongation factor LepA. However, the molecular mechanism of the translocation remains elusive. To understand the mechanism, here we study theoretically the dynamics of the forward translocation under various nucleotide states of EF-G and the backward translocation in the absence of and in the presence of LepA. We present a consistent explanation of spontaneous forward translocations in the absence of EF-G, the EF-G-catalyzed forward translocations in the presence of a non-hydrolysable GTP analogue and in the presence of GTP, and the spontaneous and LepA-catalyzed backward translocation. The theoretical results provide quantitative explanations of a lot of different, independent experimental data, and also provide testable predictions. PMID:23951009

Xie, Ping

2013-01-01

325

Dynamics of forward and backward translocation of mRNA in the ribosome.  

PubMed

Translocation of the mRNA-tRNA complex in the ribosome, which is catalyzed by elongation factor EF-G, is one of critical steps in the elongation cycle of protein synthesis. Besides this conventional forward translocation, the backward translocation can also occur, which can be catalyzed by elongation factor LepA. However, the molecular mechanism of the translocation remains elusive. To understand the mechanism, here we study theoretically the dynamics of the forward translocation under various nucleotide states of EF-G and the backward translocation in the absence of and in the presence of LepA. We present a consistent explanation of spontaneous forward translocations in the absence of EF-G, the EF-G-catalyzed forward translocations in the presence of a non-hydrolysable GTP analogue and in the presence of GTP, and the spontaneous and LepA-catalyzed backward translocation. The theoretical results provide quantitative explanations of a lot of different, independent experimental data, and also provide testable predictions. PMID:23951009

Xie, Ping

2013-01-01

326

Protein translocation without specific quality control in a computational model of the Tat system  

NASA Astrophysics Data System (ADS)

The twin-arginine translocation (Tat) system transports folded proteins of various sizes across both bacterial and plant thylakoid membranes. The membrane-associated TatA protein is an essential component of the Tat translocon, and a broad distribution of different sized TatA-clusters is observed in bacterial membranes. We assume that the size dynamics of TatA clusters are affected by substrate binding, unbinding, and translocation to associated TatBC clusters, where clusters with bound translocation substrates favour growth and those without associated substrates favour shrinkage. With a stochastic model of substrate binding and cluster dynamics, we numerically determine the TatA cluster size distribution. We include a proportion of targeted but non-translocatable (NT) substrates, with the simplifying hypothesis that the substrate translocatability does not directly affect cluster dynamical rate constants or substrate binding or unbinding rates. This amounts to a translocation model without specific quality control. Nevertheless, NT substrates will remain associated with TatA clusters until unbound and so will affect cluster sizes and translocation rates. We find that the number of larger TatA clusters depends on the NT fraction f. The translocation rate can be optimized by tuning the rate of spontaneous substrate unbinding, {{\\Gamma }_{U}}. We present an analytically solvable three-state model of substrate translocation without cluster size dynamics that follows our computed translocation rates, and that is consistent with in vitro Tat-translocation data in the presence of NT substrates.

Nayak, Chitra R.; Brown, Aidan I.; Rutenberg, Andrew D.

2014-10-01

327

Involvement of Chromosome X in Primary Cytogenetic Change in Human Neoplasia: Nonrandom Translocation in Synovial Sarcoma  

Microsoft Academic Search

A translocation that involves chromosome X (band p11.2) and chromosome 18 (band q11.2) was observed in short-term in vitro cultures of cells from five synovial sarcomas and one malignant fibrous histiocytoma. In four of these tumors, the translocation t(X;18)(p11.2;q11.2) was reciprocal. The two other tumors had complex translocations: t(X;18;21)(p11.2;q11.2;p13) and t(X;15;18)(p11.2;q23;q11.2). A translocation between chromosomes X and 18 was not

C. Turc-Carel; P. dal Cin; J. Limon; U. Rao; F. P. Li; J. M. Corson; R. Zimmerman; D. M. Parry; J. M. Cowan; A. A. Sandberg

1987-01-01

328

Tagetitoxin inhibits transcription by stabilizing pre-translocated state of the elongation complex.  

PubMed

Transcription elongation consists of repetition of the nucleotide addition cycle: phosphodiester bond formation, translocation and binding of the next nucleotide. Inhibitor of multi-subunit RNA polymerase tagetitoxin (TGT) enigmatically slows down addition of nucleotides in a sequence-dependent manner, only at certain positions of the template. Here, we show that TGT neither affects chemistry of RNA synthesis nor induces backward translocation, nor competes with the nucleoside triphosphate (NTP) in the active center. Instead, TGT increases the stability of the pre-translocated state of elongation complex, thus slowing down addition of the following nucleotide. We show that the extent of inhibition directly depends on the intrinsic stability of the pre-translocated state. The dependence of translocation equilibrium on the transcribed sequence results in a wide distribution (~1-10(3)-fold) of inhibitory effects of TGT at different positions of the template, thus explaining sequence-specificity of TGT action. We provide biochemical evidence that, in pre-translocated state, TGT stabilizes folded conformation of the Trigger Loop, which inhibits forward and backward translocation of the complex. The results suggest that Trigger Loop folding in the pre-translocated state may serve to reduce back-tracking of the elongation complex. Overall, we propose that translocation may be a limiting and highly regulated step of RNA synthesis. PMID:23935117

Yuzenkova, Yulia; Roghanian, Mohammad; Bochkareva, Aleksandra; Zenkin, Nikolay

2013-11-01

329

Translocation of a Polymer Chain across a Nanopore: A Brownian Dynamics Simulation Study  

NASA Technical Reports Server (NTRS)

We carried out Brownian dynamics simulation studies of the translocation of single polymer chains across a nanosized pore under the driving of an applied field (chemical potential gradient). The translocation process can be either dominated by the entropic barrier resulted from restricted motion of flexible polymer chains or by applied forces (or chemical gradient across the wall), we focused on the latter case in our studies. Calculation of radius of gyrations at the two opposite sides of the wall shows that the polymer chains are not in equilibrium during the translocation process. Despite this fact, our results show that the one-dimensional diffusion and the nucleation model provide an excellent description of the dependence of average translocation time on the chemical potential gradients, the polymer chain length and the solvent viscosity. In good agreement with experimental results and theoretical predictions, the translocation time distribution of our simple model shows strong non-Gaussian characteristics. It is observed that even for this simple tubelike pore geometry, more than one peak of translocation time distribution can be generated for proper pore diameter and applied field strengths. Both repulsive Weeks-Chandler-Anderson and attractive Lennard-Jones polymer-nanopore interaction were studied, attraction facilitates the translocation process by shortening the total translocation time and dramatically improve the capturing of polymer chain. The width of the translocation time distribution was found to decrease with increasing temperature, increasing field strength, and decreasing pore diameter.

Tian, Pu; Smith, Grant D.

2003-01-01

330

Protein translocation without specific quality control in a computational model of the Tat system  

E-print Network

The twin-arginine translocation (Tat) system transports folded proteins of various sizes across both bacterial and plant thylakoid membranes. The membrane-associated TatA protein is an essential component of the Tat translocon, and a broad distribution of different sized TatA-clusters is observed in bacterial membranes. We assume that the size dynamics of TatA clusters are affected by substrate binding, unbinding, and translocation to associated TatBC clusters, where clusters with bound translocation substrates favour growth and those without associated substrates favour shrinkage. With a stochastic model of substrate binding and cluster dynamics, we numerically determine the TatA cluster size distribution. We include a proportion of targeted but non-translocatable (NT) substrates, with the simplifying hypothesis that the substrate translocatability does not directly affect cluster dynamical rate constants or substrate binding or unbinding rates. This amounts to a translocation model without specific quality control. Nevertheless, NT substrates will remain associated with TatA clusters until unbound and so will affect cluster sizes and translocation rates. We find that the number of larger TatA clusters depends on the NT fraction $f$. The translocation rate can be optimized by tuning the rate of spontaneous substrate unbinding, $\\Gamma_U$. We present an analytically solvable three-state model of substrate translocation without cluster size dynamics that follows our computed translocation rates, and that is consistent with {\\em in vitro} Tat-translocation data in the presence of NT substrates.

Chitra R. Nayak; Aidan I. Brown; Andrew D. Rutenberg

2014-08-20

331

A G-protein subunit translocation embedded network motif underlies GPCR regulation of calcium oscillations.  

PubMed

G-protein ?? subunits translocate reversibly from the plasma membrane to internal membranes on receptor activation. Translocation rates differ depending on the ? subunit type. There is limited understanding of the role of the differential rates of G?? translocation in modulating signaling dynamics in a cell. Bifurcation analysis of the calcium oscillatory network structure predicts that the translocation rate of a signaling protein can regulate the damping of system oscillation. Here, we examined whether the G?? translocation rate regulates calcium oscillations induced by G-protein-coupled receptor activation. Oscillations in HeLa cells expressing ? subunit types with different translocation rates were imaged and quantitated. The results show that differential G?? translocation rates can underlie the diversity in damping characteristics of calcium oscillations among cells. Mathematical modeling shows that a translocation embedded motif regulates damping of G-protein-mediated calcium oscillations consistent with experimental data. The current study indicates that such a motif may act as a tuning mechanism to design oscillations with varying damping patterns by using intracellular translocation of a signaling component. PMID:24988358

Giri, Lopamudra; Patel, Anilkumar K; Karunarathne, W K Ajith; Kalyanaraman, Vani; Venkatesh, K V; Gautam, N

2014-07-01

332

Reciprocal X;1 translocation in a calf B. Mayr H. Korb S. Kiendlera G. Brem  

E-print Network

for Animal Breeding and Genetics, Veterinary University, Veterinarplatz 1, 1210 Vienna, Austria b impossible. However, it is justified to expect higher fertility depression from a reciprocal translocation

Paris-Sud XI, Université de

333

Imaging cytosolic translocation of Mycobacteria with two-photon fluorescence resonance energy transfer microscopy  

PubMed Central

Transition from latency to active tuberculosis requires Mycobacterium tuberculosis (Mtb) to penetrate the phagosomal membrane and translocate to the cytosol of the host macrophage. Quantitative two-photon fluorescence resonance energy transfer (FRET) microscopy is developed to measure cytosolic translocation using Mycobacterium marinum (Mm) as a model organism for Mtb. Macrophages were infected with Mm or non-pathogenic Mycobacterium smegmatis (Ms) as a control, then loaded with a FRET substrate. Once translocation occurs, mycobacterium-bearing ?-lactamase cleaves the substrate, resulting in decrease of FRET signal. Quantification of this FRET signal change revealed that Mm, but not Ms, is capable of translocating to the cytosol.

Acosta, Yassel; Zhang, Qi; Rahaman, Arifur; Ouellet, Hugues; Xiao, Chuan; Sun, Jianjun; Li, Chunqiang

2014-01-01

334

A Comparison of the Effects of Carbon Dioxide Concentration and Temperature on Respiration, Translocation and Nitrate Reduction in Darkened Soybean Leaves  

PubMed Central

• Background and aims Respiration of autotrophs is an important component of their carbon balance as well as the global carbon dioxide budget. How autotrophic respiration may respond to increasing carbon dioxide concentrations, [CO2], in the atmosphere remains uncertain. The existence of short?term responses of respiration rates of plant leaves to [CO2] is controversial. Short?term responses of respiration to temperature are not disputed. This work compared responses of dark respiration and two processes dependent on the energy and reductant supplied by dark respiration, translocation and nitrate reduction, to changes in [CO2] and temperature. • Methods Mature soybean leaves were exposed for a single 8?h dark period to one of five combinations of air temperature and [CO2], and rates of respiration, translocation and nitrate reduction were determined for each treatment. • Key results Low temperature and elevated [CO2] reduced rates of respiration, translocation and nitrate reduction, while increased temperature and low [CO2] increased rates of all three processes. A given change in the rate of respiration was accompanied by the same change in the rate of translocation or nitrate reduction, regardless of whether the altered respiration was caused by a change in temperature or by a change in [CO2]. • Conclusions These results make it highly unlikely that the observed responses of respiration rate to [CO2] were artefacts due to errors in the measurement of carbon dioxide exchange rates in this case, and indicate that elevated [CO2] at night can affect translocation and nitrate reduction through its effect on respiration. PMID:15051622

BUNCE, JAMES A.

2004-01-01

335

Cosmic Background Explorer (COBE): Emergency support  

NASA Technical Reports Server (NTRS)

The Cosmic Background Explorer (COBE) Mission will measure the diffuse radiation from the universe in the wavelength band 1 micron to 9.6 mm. The band includes the 3 K cosmic background radiation, the known relic of the primeval cosmic explosion. The COBE satellite will be launched from the Western Space and Missile Center (EWSMC) via a Delta launch vehicle into a circular parking orbit of about 300 km. COBE will be placed into a 900-km altitude circular orbit. Coverage will be provided by the Deep Space Network (DSN) for COBE emergencies that would prevent communications via the normal channels of the Tracking and Data Relay Satellite System (TDRSS). Emergency support will be provided by the DSN 26-m subnetwork. Information is given in tabular form for DSN network support, frequency assignments, telemetry, and command.

Stanford, R.; Mattson, R.

1991-01-01

336

Novel class of potential therapeutics that target ricin retrograde translocation.  

PubMed

Ricin toxin, an A-B toxin from Ricinus communis, induces cell death through the inhibition of protein synthesis. The toxin binds to the cell surface via its B chain (RTB) followed by its retrograde trafficking through intracellular compartments to the ER where the A chain (RTA) is transported across the membrane and into the cytosol. Ricin A chain is transported across the ER membrane utilizing cellular proteins involved in the disposal of aberrant ER proteins by a process referred to as retrograde translocation. Given the current lack of therapeutics against ricin intoxication, we developed a high-content screen using an enzymatically attenuated RTA chimera engineered with a carboxy-terminal enhanced green fluorescent protein (RTA(E177Q)egfp) to identify compounds that target RTA retrograde translocation. Stabilizing RTA(E177Q)egfp through the inclusion of proteasome inhibitor produced fluorescent peri-nuclear granules. Quantitative analysis of the fluorescent granules provided the basis to discover compounds from a small chemical library (2080 compounds) with known bioactive properties. Strikingly, the screen found compounds that stabilized RTA molecules within the cell and several compounds limited the ability of wild type RTA to suppress protein synthesis. Collectively, a robust high-content screen was developed to discover novel compounds that stabilize intracellular ricin and limit ricin intoxication. PMID:24366208

Redmann, Veronika; Gardner, Thomas; Lau, Zerlina; Morohashi, Keita; Felsenfeld, Dan; Tortorella, Domenico

2014-01-01

337

Cardiolipin prevents membrane translocation and permeabilization by daptomycin.  

PubMed

Daptomycin is an acidic lipopeptide antibiotic that, in the presence of calcium, forms oligomeric pores on membranes containing phosphatidylglycerol. It is clinically used against various Gram-positive bacteria such as Staphylococcus aureus and Enterococcus species. Genetic studies have indicated that an increased content of cardiolipin in the bacterial membrane may contribute to bacterial resistance against the drug. Here, we used a liposome model to demonstrate that cardiolipin directly inhibits membrane permeabilization by daptomycin. When cardiolipin is added at molar fractions of 10 or 20% to membranes containing phosphatidylglycerol, daptomycin no longer forms pores or translocates to the inner membrane leaflet. Under the same conditions, daptomycin continues to form oligomers; however, these oligomers contain only close to four subunits, which is approximately half as many as observed on membranes without cardiolipin. The collective findings lead us to propose that a daptomycin pore consists of two aligned tetramers in opposite leaflets and that cardiolipin prevents the translocation of tetramers to the inner leaflet, thereby forestalling the formation of complete, octameric pores. Our findings suggest a possible mechanism by which cardiolipin may mediate resistance to daptomycin, and they provide new insights into the action mode of this important antibiotic. PMID:24616102

Zhang, TianHua; Muraih, Jawad K; Tishbi, Nasim; Herskowitz, Jennifer; Victor, Rachel L; Silverman, Jared; Uwumarenogie, Stephanie; Taylor, Scott D; Palmer, Michael; Mintzer, Evan

2014-04-25

338

Electronic transduction of proton translocations in nanoassembled lamellae of bacteriorhodopsin.  

PubMed

An organic field-effect transistor (OFET) integrating bacteriorhodopsin (bR) nanoassembled lamellae is proposed for an in-depth study of the proton translocation processes occurring as the bioelectronic device is exposed either to light or to low concentrations of general anesthetic vapors. The study involves the morphological, structural, electrical, and spectroscopic characterizations necessary to assess the functional properties of the device as well as the bR biological activity once integrated into the functional biointerlayer (FBI)-OFET structure. The electronic transduction of the protons phototranslocation is shown as a current increase in the p-type channel only when the device is irradiated with photons known to trigger the bR photocycle, while Raman spectroscopy reveals an associated C?C isomer switch. Notably, higher energy photons bring the cis isomer back to its trans form, switching the proton pumping process off. The investigation is extended also to the study of a PM FBI-OFET exposed to volatile general anesthetics such as halothane. In this case an electronic current increase is seen upon exposure to low, clinically relevant, concentrations of anesthetics, while no evidence of isomer-switching is observed. The study of the direct electronic detection of the two different externally triggered proton translocation effects allows gathering insights into the underpinning of different bR molecular switching processes. PMID:25077939

Palazzo, Gerardo; Magliulo, Maria; Mallardi, Antonia; Angione, Maria Daniela; Gobeljic, Danka; Scamarcio, Gaetano; Fratini, Emiliano; Ridi, Francesca; Torsi, Luisa

2014-08-26

339

Exertional myopathy in translocated river otters from New York.  

PubMed

Lesions consistent with exertional myopathy (EM) were documented postmortem in four North American river otters (Lutra canadensis) during translocation for a population restoration project. Clinical signs in these otters included depression, anorexia and shock. Gross lesions in one otter included locally extensive linear, pale areas within the subscapularis, rectus abdominis, quadriceps, and dorsal laryngeal muscles. Microscopic lesions were characterized by acute to subacute myofiber necrosis of varying severity, and occurred in a variety of skeletal muscles as well as cardiac muscle in one otter. Based on these observations, we conducted a retrospective review of records of otters which experienced similar capture, transfer, and holding protocols between 1995 and 1997, but with a successful outcome (n = 69). Significant elevations in serum aspartate aminotransferase (AST) and creatine kinase (CK) were observed in 19 (28%) of the otters, but may have been higher due to delayed sample collection from some otters. However, none of the otters with elevated enzymes exhibited clinical signs suggestive of EM. These findings indicate that river otters may develop EM when translocated, but many cases may be mild or clinically inapparent. PMID:10479089

Hartup, B K; Kollias, G V; Jacobsen, M C; Valentine, B A; Kimber, K R

1999-07-01

340

Translocation of nanoparticles through a polymer brush-modified nanochannel  

PubMed Central

A basic understanding of the transport mechanisms of nanostructures in a polymer brush-modified nanochannel as well as the brush-nanostructure interactions at molecular level is important to design and fabricate emerging smart nano/microfluidic channels. In this work, we report coarse-grained molecular dynamics simulations of the translocation of nanoparticles through a cylindrical nanochannel coated with the polymer brush. The effects of the interparticle interaction and grafting density on the distribution and electrokinetic transport of nanoparticles are addressed in detail. Analysis of the distribution and velocity profiles of nanoparticles from the simulations indicate that the location of nanoparticles along the radial direction and their migration velocity are very sensitive to the change of interparticle interaction. We find complicated transport dynamics of nanoparticles under the influence of various grafting densities. The nanoparticles show markedly different translocation behavior upon increasing the grafting density, which depends on the counterion distribution, free room within the brush, nanoparticle-polymer friction, and brush configuration. Our results may serve as a useful starting point for the transport of nanostructures in polymer-modified channels and help to guide the design of novel smart nanofluidic channels for controlling the migration behavior of nanostructures. PMID:23853678

Cao, Qianqian; Zuo, Chuncheng; Li, Lujuan; Li, Yingjie; Yang, Yang

2012-01-01

341

FAMILY BACKGROUND OF RURAL YOUTH.  

ERIC Educational Resources Information Center

FAMILY BACKGROUNDS OF RURAL YOUTH ARE DISCUSSED. THE BACKGROUND PROVIDED BY THE FAMILY HAS IMPLICATIONS FOR THE ADJUSTMENT OF RURAL YOUTH IN AN URBANIZED, HIGHLY TECHNICAL SOCIETY. THE BASIC ECOLOGICAL CONDITIONS OF RURAL AREAS INFLUENCE THE RATE OF SOCIAL CHANGE, THE IMPORTANCE OF THE FAMILY AS A SOCIAL UNIT, AND THE ORIENTATION TOWARD LEGAL…

COPP, JAMES H.

342

Lattice QCD in Background Fields  

SciTech Connect

Electromagnetic properties of hadrons can be computed by lattice simulations of QCD in background fields. We demonstrate new techniques for the investigation of charged hadron properties in electric fields. Our current calculations employ large electric fields, motivating us to analyze chiral dynamics in strong QED backgrounds, and subsequently uncover surprising non-perturbative effects present at finite volume.

William Detmold, Brian Tiburzi, Andre Walker-Loud

2009-06-01

343

Backgrounds and characteristics of arsonists  

Microsoft Academic Search

The aim of this study was to gain more insight in the backgrounds and characteristics of arsonists. For this, the psychiatric, psychological, personal, and criminal backgrounds of all arsonists (n=25), sentenced to forced treatment in the maximum security forensic hospital “De Kijvelanden”, were compared to the characteristics of a control group of patients (n=50), incarcerated at the same institution for

Wim Labree; Henk Nijman; Hjalmar van Marle; Eric Rassin

2010-01-01

344

The Relationship of Rhythmic and Melodic Perception with Background Music Distraction in College Level Students  

E-print Network

This study investigated relationships among the ability to audiate musical stimuli, background music condition, familiarity, gender, general academic achievement, age, and frequency of use on the level of distraction caused by background music...

Dove, Michael Karl

2009-04-27

345

Low background counting at the LBNL low background facility  

NASA Astrophysics Data System (ADS)

The Low Background Facility (LBF) at the Lawrence Berkeley National Laboratory (LBNL) in Berkeley, California provides low background gamma spectroscopy services to end-users in two unique facilities: locally within a carefully-constructed, low background laboratory space; and a satellite underground station (600 m.w.e) in Oroville, CA. These facilities provide a variety of gamma spectroscopy services to low background experiments primarily in the form of passive material screening for primordial radioisotopes (U, Th, K) or common cosmogenic and anthropogenic products, as well as active screening via neutron activation analysis for specific applications. A general overview of the facilities, services, and capabilities will be discussed. Recent activities will also be presented, including the recent installation of a 3? muon veto at the surface facility, cosmogenic activation studies of TeO2 for CUORE, and environmental monitoring of Fukushima fallout.

Thomas, K. J.; Smith, A. R.; Chan, Y. D.; Norman, E. B.; Wang, B. S.; Hurley, D. L.

2013-08-01

346

A new reciprocal translocation involving chromosomes 1/14 C. TAROCCO Fabrizia FRANCHI G. CROCI  

E-print Network

Note A new reciprocal translocation involving chromosomes 1/14 in a boar C. TAROCCO Fabrizia and carrier of a reciprocal balanced translocation involving chromosomes 1 and 14 is presented. High resolution chromosomes are analyzed and the break-points of the rearrangement are compared to those

Paris-Sud XI, Université de

347

Cytotoxic Necrotizing Factor-Y Boosts Yersinia Effector Translocation by Activating Rac Protein*  

PubMed Central

Pathogenic Yersinia spp. translocate the effectors YopT, YopE, and YopO/YpkA into target cells to inactivate Rho family GTP-binding proteins and block immune responses. Some Yersinia spp. also secrete the Rho protein activator cytotoxic necrotizing factor-Y (CNF-Y), but it has been unclear how the bacteria may benefit from Rho protein activation. We show here that CNF-Y increases Yop translocation in Yersinia enterocolitica-infected cells up to 5-fold. CNF-Y strongly activated RhoA and also delayed in time Rac1 and Cdc42, but when individually expressed, constitutively active mutants of Rac1, but not of RhoA, increased Yop translocation. Consistently, knock-out or knockdown of Rac1 but not of RhoA, -B, or -C inhibited Yersinia effector translocation in CNF-Y-treated and control cells. Activation or knockdown of Cdc42 also affected Yop translocation but much less efficiently than Rac. The increase in Yop translocation induced by CNF-Y was essentially independent of the presence of YopE, YopT, or YopO in the infecting Yersinia strain, indicating that none of the Yops reported to inhibit translocation could reverse the CNF-Y effect. In summary, the CNF-Y activity of Yersinia strongly enhances Yop translocation through activation of Rac. PMID:23803609

Wolters, Manuel; Boyle, Erin C.; Lardong, Kerstin; Trülzsch, Konrad; Steffen, Anika; Rottner, Klemens; Ruckdeschel, Klaus; Aepfelbacher, Martin

2013-01-01

348

HELMINTH PARASITES OF TRANSLOCATED RACCOONS (Procyon lotor) IN THE SOUTHEASTERN UNITED STATES n  

Microsoft Academic Search

Raccoons (Pnocyon lotor) typical of animals released by private hunting clubs in the Appalachian Mountains were examined for helminth parasites to evaluate the influence raccoon translocation might have on parasitic diseases. Results were compared with data from resident raccoons from characteristic release areas. Translocated raccoons harbored 19 helminth species that were exotic to resident animals. Most of these exotic parasites

GARY D. SCHAFFER; WILLIAM R DAVIDSON; VICTOR F. NETTLES; A. ROLLOR

349

Factors affecting the survival of founding individuals in translocated New Zealand Saddlebacks Philesturnus carunculatus  

Microsoft Academic Search

Successful founders of new populations may represent a non-random sample of potential founding individuals. Using a recent Saddleback Philesturnus carunculatus translocation as a natural experiment, we related morphology, parasite load and genetic variation of translocated individuals to subsequent survivorship to assess the traits of successful founders. We also included capture location and holding time in our models to account for

SABRINA S. TAYLOR; IAN G. JAMIESON

2007-01-01

350

Aggressive bowel preparation does not enhance bacterial translocation, provided the mucosal barrier is not disrupted  

Microsoft Academic Search

PURPOSE: Prospective, randomized studies have shown that bowel preparation may adversely affect infectious complications following colonic resections. However, very little is known about the effects of bacterial translocation on these infectious complications. The aim of this prospective, randomized study was to assess the effects of bowel preparation on bacterial translocation. METHODS: A total of 82 consecutive patients undergoing elective abdominal

Taner I. Kale; Mehmet A. Kuzu; Alper Tekeli; Adil Tanik; Murat Aksoy; Mükerrem Cete

1998-01-01

351

Effect of phenological development on radiophosphorus translocation from leaves in crested wheatgrass  

Microsoft Academic Search

The effect of phenological development on the pattern of photosynthate translocation was studied in crested wheatgrass [Agropyron cristatum (L.) Gaertn.] plants grown in a nursery under semi-natural environmental conditions at Logan, Utah. Radiophosphorus was used to trace the photosynthate translocation from April 13, 1968, through December 2, 1968.

Ronald E. Sosebee; Herman H. Wiebe

1973-01-01

352

Short-term survival and dispersal of translocated European wild rabbits. Improving the release protocol  

Microsoft Academic Search

Translocation of European wild rabbit Oryctolagus cuniculus L. is one of the most frequent management tools to increase rabbit density in Spain, both as prey of several predators that are threatened with extinction and for sport hunting. Nevertheless the elevated short-term mortality by predation makes translocations unsuccessful and increases their biological cost. Information on the factors affecting the short-term survival

Carlos Calvete; Rosa Estrada

2004-01-01

353

No evidence that dietary nutrient deficiency is related to poor reproductive success of translocated takahe  

Microsoft Academic Search

The aim of the study was to identify from the existing literature the essential nutrients that are known to affect egg fertility and hatching success in birds, and compare the concentrations of these between source and translocated populations of the endangered New Zealand takahe. Takahe are herbivorous, and those that have been translocated to highly modified island sites with pasture

Ian G. Jamieson

2004-01-01

354

Protein targeting to and translocation across the membrane of the endoplasmic reticulum  

E-print Network

Protein targeting to and translocation across the membrane of the endoplasmic reticulum Jodi targeting to and translocation across the membrane of the endoplasmic reticulum. Two experimental systems understanding of how proteins are targeted to the endoplasmic reticulum membrane. Current Opinion in Cell

Walter, Peter

355

Retro-translocation of proteins from the endoplasmic reticulum into the cytosol  

Microsoft Academic Search

Proteins that are misfolded in the endoplasmic reticulum are transported back into the cytosol for destruction by the proteasome. This retro-translocation pathway has been co-opted by certain viruses, and by plant and bacterial toxins. The mechanism of retro-translocation is still mysterious, but several aspects of this process are now being unravelled.

Billy Tsai; Yihong Ye; Tom A. Rapoport

2002-01-01

356

In vivo Dissection of the Tat Translocation Pathway in Escherichia coli  

E-print Network

-ColV. The translocation of RR-ColV fully inhibited the growth of wild-type Escherichia coli and those of the Átat for bacteria only under certain growth conditions. Escherichia coli Tat components are encoded by the tatIn vivo Dissection of the Tat Translocation Pathway in Escherichia coli Be�rengeÁre Ize1 , Fabien

Palmer, Tracy

357

Export Pathway Selectivity of Escherichia coli Twin Arginine Translocation Signal Peptides*S  

E-print Network

Export Pathway Selectivity of Escherichia coli Twin Arginine Translocation Signal Peptides encodes at least 29 putative sig- nal peptides containing a twin arginine motif characteristic of proteins exported via the twin arginine translocation (Tat) path- way. Fusions of the putative Tat signal peptides

Palmer, Tracy

358

Insulin-Induced Translocation of Protein Kinase B to the Plasma Membrane in Rat Adipocytes  

Microsoft Academic Search

Protein kinase B (PKB) has previously been shown to be activated in response to insulin and growth factor stimulation. The activation mechanism has been suggested to involve translocation of PKB to membranes, where it is phosphorylated and activated. Insulin-induced translocation of PKB has not been demonstrated in a physiological target cell. Therefore we have used the primary rat adipocyte to

Olga Göransson; Jonny Wijkander; Vincent Manganiello; Eva Degerman

1998-01-01

359

Antigenicity of Fusion Proteins from Sarcoma-associated Chromosomal Translocations1  

Microsoft Academic Search

Synovial sarcoma (SS), clear cell sarcoma (CCS), and desmoplastic small round cell tumor (DSRCT) are soft-tissue malignancies occurring primarily in adolescents and young adults. These tumors contain specific chromosomal translocations that fuse the 5 region of one gene with the 3 region of another, resulting in the formation of characteristic fusion proteins. These translocations are unique to tumor cells and

B. Scott Worley; Leon T. van den Broeke; Theresa J. Goletz; C. David Pendleton; Emily M. Daschbach; Elaine K. Thomas; Francesco M. Marincola; Lee J. Helman; Jay A. Berzofsky

2001-01-01

360

Tandem 1;30 translocation: a new structural abnormality in the horse (Equus caballus)  

Microsoft Academic Search

A 1;30 tandem translocation was found in an 8-yr-old thoroughbred stallion referred because of reduced fertility. The diagnosis was confirmed by GTG and CBG staining. This is the first report of a tandem translocation in the horse.Copyright © 1996 S. Karger AG, Basel

S. E. Long

1996-01-01

361

The influence of phosphorus, zinc and manganese on absorption and translocation of iron in watercress  

Microsoft Academic Search

Absorption and translocation of iron by intact watercress plants (Rorippa nasturtium-aquaticum (L) Hayek) was studied in short period uptake experiments utilising 59Fe labelled ferric chloride. Total translocation of iron was inhibited by increasing levels of phosphorus, zinc and manganese in the nutrient medium; the elevated phosphorus and zinc concentrations enhanced iron absorption into roots, but increased retention of absorbed iron

I. P. Cumbus; D. J. Hornsey; L. W. Robinson

1977-01-01

362

Maternal serum analyte levels in pregnancies with fetal Down syndrome resulting from translocations  

Microsoft Academic Search

OBJECTIVE: Our purpose was to determine whether pregnancies affected by fetal Down syndrome resulting from Robertsonian translocations are associated with second-trimester maternal serum analyte levels different from those resulting from fetal trisomy 21.STUDY DESIGN: Pregnancies with Down syndrome caused by Robertsonian translocations were identified through the cytogenetics laboratories at the participating institutions. Those with maternal serum screening values between 15

Devereux N. Saller; Jacob A. Canick; Leonard H. Kellner; Nancy C. Rose; Judy Garza; Carol A. French; Robert A. Mooney

1997-01-01

363

Preprotein translocation across the endoplasmic reticulum membrane in milieus crowded by proteins  

NASA Astrophysics Data System (ADS)

Translocation of preproteins chains between the cytoplasm and the endoplasmic reticulum lumen takes place in a milieu crowded primarily by proteins. We compute translocation and retrotranslocation times for chains of different length in a milieu crowded by spherical agents at volume fractions equivalent to that found in cells. These numerical times obtained from a diffusion-equation model subject to a potential given by the free energy of one chain, indicate that crowding increases the translocation time by up to five times compared to those in dilute conditions for average-size chains and by up to a thousand times for long chains. Retrotranslocation times become smaller than translocation ones, in approximately 75%. Translocation rates obtained in this work are similar to those found in a theoretical model for Brownian-ratchet translocation and coincide with in vitro experimental results (1-8 aminoacid/s) only in the limit of very long chains; for shorter chains, translocation rates are much faster. Our prediction that for long chains translocation rates would be significantly slowed by crowding can be tested experimentally using vesicles. Discrepancy of time-scales with experiments for short chains indicates that other factors beside crowding must be included in our model.

Vélez, José. Antonio; Guzmán, Orlando; Navarro, Fernando

2012-02-01

364

A reevaluation of the role of glycerol in carbon translocation in zooxanthellae-coelenterate symbiosis  

Microsoft Academic Search

Glycerol has been traditionally viewed as the main form of carbon translocated from zooxanthellae to the coelenterate host. Most of this glycerol was postulated to be used by the coelenterate host for lipid synthesis. Recent work suggests that large amounts of photosynthetically fixed carbon is synthesized into lipid in the algae, and then translocated as lipid droplets to the host.

J. F. Battey; J. S. Patton

1984-01-01

365

A genetic screen to isolate type III effectors translocated into pepper cells during  

E-print Network

A genetic screen to isolate type III effectors translocated into pepper cells during Xanthomonas the identity of many proteins translocated through this apparatus is not known. We used a genetic screen peptide resulted in the creation of chimeric TTSS effector::AvrBs2 fusion proteins. Xcv strains containing

Mudgettt, Mary Beth

366

Translocation of Phospholipids and Dithionite Permeability in Liquid-Ordered and Liquid-Disordered Membranes  

PubMed Central

We present a detailed study of the translocation rate of two headgroup-labeled phospholipid derivatives, one with two acyl chains, NBD-DMPE, and the other with a single acyl chain, NBD-lysoMPE, in lipid bilayer membranes in the liquid-disordered state (POPC) and in the liquid-ordered states (POPC/cholesterol (Chol), molar ratio 1:1, and sphingomyelin (SpM)/Chol, molar ratio 6:4). The study was performed as a function of temperature and the thermodynamic parameters of the translocation process have been obtained. The most important findings are 1), the translocation of NBD-DMPE is significantly faster than the translocation of NBD-lysoMPE for all bilayer compositions and temperatures tested; and 2), for both phospholipid derivatives, the translocation in POPC bilayers is ?1 order of magnitude faster than in POPC/Chol (1:1) bilayers and ?2–3 orders of magnitude faster than in SpM/Chol (6:4) bilayers. The permeability of the lipid bilayers to dithionite has also been measured. In liquid disordered membranes, the permeability rate constant obtained is comparable to the translocation rate constant of NBD-DMPE. However, in liquid-ordered bilayers, the permeability of dithionite is significantly faster then the translocation of NBD-DMPE. The change in enthalpy and entropy associated with the formation of the activated state in the translocation and permeation processes has also been obtained. PMID:16617082

Moreno, Maria Joao; Estronca, Luis M. B. B.; Vaz, Winchil L. C.

2006-01-01

367

Light-Driven Cone Arrestin Translocation in Cones of Postnatal Guanylate Cyclase-1 Knockout Mouse Retina  

E-print Network

Retina Treated with AAV-GC1 Shannon E. Haire,1 Jijing Pang,2 Sanford L. Boye,2 Izabel Sokal,3 Cheryl M of the light-driven translocation of cone arrestin is one of the pheno- types of cone cells in this retina- stores cone arrestin translocation in the cone cells of postnatal GC1 knockout mouse retina. METHODS

Palczewski, Krzysztof

368

Parp1 facilitates alternative NHEJ, whereas Parp2 suppresses IgH/c-myc translocations during immunoglobulin class switch recombination  

PubMed Central

Immunoglobulin class switch recombination (CSR) is initiated by DNA breaks triggered by activation-induced cytidine deaminase (AID). These breaks activate DNA damage response proteins to promote appropriate repair and long-range recombination. Aberrant processing of these breaks, however, results in decreased CSR and/or increased frequency of illegitimate recombination between the immunoglobulin heavy chain locus and oncogenes like c-myc. Here, we have examined the contribution of the DNA damage sensors Parp1 and Parp2 in the resolution of AID-induced DNA breaks during CSR. We find that although Parp enzymatic activity is induced in an AID-dependent manner during CSR, neither Parp1 nor Parp2 are required for CSR. We find however, that Parp1 favors repair of switch regions through a microhomology-mediated pathway and that Parp2 actively suppresses IgH/c-myc translocations. Thus, we define Parp1 as facilitating alternative end-joining and Parp2 as a novel translocation suppressor during CSR. PMID:19364882

Robert, Isabelle; Dantzer, Francoise

2009-01-01

369

Meghan Miller Background and Significance  

E-print Network

1 Meghan Miller Background and Significance Autistic spectrum disorders (ASDs) represent variable pathological symptoms from one individual to the next, representing a continual spectrum rather within the autism spectrum include Asperger, Fragile X, Angelman, Rett, Williams, Prader

Gleeson, Joseph G.

370

Nongeometric fluxes as supergravity backgrounds  

SciTech Connect

We consider examples of D=4 string theory vacua which, although globally nongeometric, admit a local description in terms of D=10 supergravity backgrounds. We analyze such backgrounds and find that the supersymmetry spinors vary nontrivially along the internal manifold, reproducing the interpolating supergravity solutions found by Frey and Grana. Finally, we propose a simple, local expression for nongeometric fluxes in terms of the internal spinors of the compactification.

Marchesano, Fernando [ASC, Ludwig-Maximilians-Universitaet, Theresienstrasse 37, 80333 Munich (Germany); Schulgin, Waldemar [Max Planck Institut fuer Physik, Foehringer Ring 6, 80805 Munich (Germany)

2007-08-15

371

Controlling protein translocation through nanopores with bio-inspired fluid walls  

NASA Astrophysics Data System (ADS)

Synthetic nanopores have been used to study individual biomolecules in high throughput, but their performance as sensors does not match that of biological ion channels. Challenges include control of nanopore diameters and surface chemistry, modification of the translocation times of single-molecule analytes through nanopores, and prevention of non-specific interactions with pore walls. Here, inspired by the olfactory sensilla of insect antennae, we show that coating nanopores with a fluid lipid bilayer tailors their surface chemistry and allows fine-tuning and dynamic variation of pore diameters in subnanometre increments. Incorporation of mobile ligands in the lipid bilayer conferred specificity and slowed the translocation of targeted proteins sufficiently to time-resolve translocation events of individual proteins. Lipid coatings also prevented pores from clogging, eliminated non-specific binding and enabled the translocation of amyloid-beta (A?) oligomers and fibrils. Through combined analysis of their translocation time, volume, charge, shape and ligand affinity, different proteins were identified.

Yusko, Erik C.; Johnson, Jay M.; Majd, Sheereen; Prangkio, Panchika; Rollings, Ryan C.; Li, Jiali; Yang, Jerry; Mayer, Michael

2011-04-01

372

Quantitative Analysis of Protein Translocations by Microfluidic Total Internal Reflection Fluorescence Flow Cytometry  

PubMed Central

Protein translocation, or the change in a protein’s location between different subcellular compartments, is a critical process by which intracellular proteins carry out their cellular functions. Aberrant translocation events contribute to various diseases ranging from metabolic disorders to cancer. In this study, we demonstrate the use of a newly developed single-cell tool, microfluidic total internal reflection fluorescence flow cytometry (TIRF-FC), for detecting both cytosol to plasma membrane and cytosol to nucleus translocations using the tyrosine kinase Syk and the transcription factor NF-?B as models. This technique detects fluorescent molecules at the plasma membrane and in the membrane-proximal cytosol in single cells. We were able to record quantitatively changes in the fluorescence density in the evanescent field associated with these translocation processes for large cell populations with single cell resolution. We envision that TIRF-FC will provide a new approach to explore the molecular biology and clinical relevance of protein translocations. PMID:20820633

Wang, Jun; Fei, Bei; Geahlen, Robert L.

2010-01-01

373

Dynamics of polymer translocation through a nanopore induced by different sizes of crowding agents  

NASA Astrophysics Data System (ADS)

Using both theoretical analysis and Langevin dynamics simulations in two dimensions, we investigate the dynamics of polymer translocation through a nanopore induced by different sizes of the mobile crowding agents, where the crowding agents have equal area fraction ? and their diameters are ? and ?b ? ? at cis and trans sides, respectively. The chain prefers moving to the side with bigger crowding agents as expected, however, we find the size difference between crowding agents plays a complicated role in the probability of polymer translocation from cis to trans side, the translocation time ? and its distribution, and the translocation exponent. In particular, with increasing ?b, the translocation probability shows a maximum value and ? has a minimum value. These results can be interpreted by the effective driving force, which always increases with increasing ? but has a maximum value with increasing ?b.

Chen, Yuhao; Luo, Kaifu

2013-05-01

374

Driven translocation of a polymer: role of pore friction and crowding  

E-print Network

Force-driven translocation of a macromolecule through a nanopore is investigated by taking into account the monomer-pore friction as well as the "crowding" of monomers on the {\\it trans} - side of the membrane which counterbalance the driving force acting in the pore. The set of governing differential-algebraic equations for the translocation dynamics is derived and solved numerically. The analysis of this solution shows that the crowding of monomers on the trans side hardly affects the dynamics, but the monomer-pore friction can substantially slow down the translocation process. Moreover, the translocation exponent $\\alpha$ in the translocation time - vs. - chain length scaling law, $\\tau \\propto N^{\\alpha}$, becomes smaller when monomer-pore friction coefficient increases. This is most noticeable for relatively strong forces. Our findings may explain the variety of $\\alpha$ values which were found in experiments and computer simulations.

Johan L. A. Dubbeldam; V. G. Rostiashvili; T. A. Vilgis

2014-04-01

375

Versatile in vitro system to study translocation and functional integration of bacterial outer membrane proteins.  

PubMed

Gram-negative bacteria use the type-V secretion pathway to expose proteins at their cell surface, many of which have virulence functions. Translocation of those proteins across the outer membrane occurs either by means of dedicated translocator proteins (two-partner secretion) or covalently fused translocator domains (autotransporters). Translocator proteins and translocator domains are ?-barrels requiring the ?-barrel assembly machinery (BAM) for membrane integration. However, the molecular details of their passage across the envelope and insertion into the outer membrane remain enigmatic, owing in part to the fact that in vitro systems are not available. Here we describe a versatile in vitro reconstitution system that faithfully reproduces both branches of the type-V secretion pathway and the assembly of ?-barrel outer membrane proteins. This system will allow an in-depth analysis of protein secretion across and integration into outer membranes. PMID:25369922

Norell, Derrick; Heuck, Alexander; Tran-Thi, Thuy-Anh; Götzke, Hansjörg; Jacob-Dubuisson, Françoise; Clausen, Tim; Daley, Daniel O; Braun, Volkmar; Müller, Matthias; Fan, Enguo

2014-01-01

376

Nonallelic homologous recombination between retrotransposable elements is a driver of de novo unbalanced translocations  

PubMed Central

Large-scale analysis of balanced chromosomal translocation breakpoints has shown nonhomologous end joining and microhomology-mediated repair to be the main drivers of interchromosomal structural aberrations. Breakpoint sequences of de novo unbalanced translocations have not yet been investigated systematically. We analyzed 12 de novo unbalanced translocations and mapped the breakpoints in nine. Surprisingly, in contrast to balanced translocations, we identify nonallelic homologous recombination (NAHR) between (retro)transposable elements and especially long interspersed elements (LINEs) as the main mutational mechanism. This finding shows yet another involvement of (retro)transposons in genomic rearrangements and exposes a profoundly different mutational mechanism compared with balanced chromosomal translocations. Furthermore, we show the existence of compound maternal/paternal derivative chromosomes, reinforcing the hypothesis that human cleavage stage embryogenesis is a cradle of chromosomal rearrangements. PMID:23212949

Robberecht, Caroline; Voet, Thierry; Esteki, Masoud Zamani; Nowakowska, Beata A.; Vermeesch, Joris R.

2013-01-01

377

Heterologous protein production using the twin arginine translocation pathway  

DOEpatents

Provided are means for evaluating and identifying putative substrates of the twin arginine translocation (Tat) secretory pathway in Streptomyces and other bacterial species. Also provided, therefore, are simple ways to express, secrete and purify correctly folded heterologous proteins on a large scale using host microorganisms, such as, Streptomyces and the Tat pathway therein. Many of the thus-produced proteins are of significant therapeutic value in the pharmaceutical and biochemical industries, particularly when they can be secreted from the host in fully-folded active form. Accordingly, there are further provided the heterologous proteins produced by the Tat secretion pathway using the foregoing methods, and the computer algorithm used to identify the Tat signal sequence and putative substrates.

Pohlschroder, Mechtild (Philadelphia, PA); Kissinger, Jessica C (Athens, GA); Rose, R. Wesley (Glenside, PA); Brueser, Thomas (Halle, DE); Dilks, Kieran (Collingswood, NJ)

2008-11-04

378

Protein translocation through Tom40: kinetics of peptide release.  

PubMed

Mitochondrial proteins are almost exclusively imported into mitochondria from the cytosol in an unfolded or partially folded conformation. Regardless of whether they are destined for the outer or inner membrane, the intermembrane space, or the matrix, proteins begin the importation process by crossing the mitochondrial outer membrane via a specialized protein import machinery whose main component is the Tom40 channel. High-resolution ion conductance measurements through the Tom40 channel in the presence of the mitochondrial presequence peptide pF(1)? revealed the kinetics of peptide binding. Here we show that the rates for association k(on) and dissociation k(off) strongly depend on the applied transmembrane voltage. Both kinetic constants increase with an increase in the applied voltage. The increase of k(off) with voltage provides strong evidence of peptide translocation. This allows us to distinguish quantitatively between substrate blocking and permeation. PMID:22225796

Mahendran, Kozhinjampara R; Romero-Ruiz, Mercedes; Schlösinger, Andrea; Winterhalter, Mathias; Nussberger, Stephan

2012-01-01

379

Microhomology Directs Diverse DNA Break Repair Pathways and Chromosomal Translocations  

PubMed Central

Chromosomal structural change triggers carcinogenesis and the formation of other genetic diseases. The breakpoint junctions of these rearrangements often contain small overlapping sequences called “microhomology,” yet the genetic pathway(s) responsible have yet to be defined. We report a simple genetic system to detect microhomology-mediated repair (MHMR) events after a DNA double-strand break (DSB) in budding yeast cells. MHMR using >15 bp operates as a single-strand annealing variant, requiring the non-essential DNA polymerase subunit Pol32. MHMR is inhibited by sequence mismatches, but independent of extensive DNA synthesis like break-induced replication. However, MHMR using less than 14 bp is genetically distinct from that using longer microhomology and far less efficient for the repair of distant DSBs. MHMR catalyzes chromosomal translocation almost as efficiently as intra-chromosomal repair. The results suggest that the intrinsic annealing propensity between microhomology sequences efficiently leads to chromosomal rearrangements. PMID:23144625

Villarreal, Diana D.; Lee, Kihoon; Deem, Angela; Shim, Eun Yong; Malkova, Anna; Lee, Sang Eun

2012-01-01

380

Protein Translocation through Tom40: Kinetics of Peptide Release  

PubMed Central

Mitochondrial proteins are almost exclusively imported into mitochondria from the cytosol in an unfolded or partially folded conformation. Regardless of whether they are destined for the outer or inner membrane, the intermembrane space, or the matrix, proteins begin the importation process by crossing the mitochondrial outer membrane via a specialized protein import machinery whose main component is the Tom40 channel. High-resolution ion conductance measurements through the Tom40 channel in the presence of the mitochondrial presequence peptide pF1? revealed the kinetics of peptide binding. Here we show that the rates for association kon and dissociation koff strongly depend on the applied transmembrane voltage. Both kinetic constants increase with an increase in the applied voltage. The increase of koff with voltage provides strong evidence of peptide translocation. This allows us to distinguish quantitatively between substrate blocking and permeation. PMID:22225796

Mahendran, Kozhinjampara R.; Romero-Ruiz, Mercedes; Schlosinger, Andrea; Winterhalter, Mathias; Nussberger, Stephan

2012-01-01

381

Biosynthesis and Translocation of Unsulfated Acyltrehaloses in Mycobacterium tuberculosis.  

PubMed

A number of species-specific polymethyl-branched fatty acid-containing trehalose esters populate the outer membrane of Mycobacterium tuberculosis. Among them, 2,3-diacyltrehaloses (DAT) and penta-acyltrehaloses (PAT) not only play a structural role in the cell envelope but also contribute to the ability of M. tuberculosis to multiply and persist in the infected host, promoting the intracellular survival of the bacterium and modulating host immune responses. The nature of the machinery, topology, and sequential order of the reactions leading to the biosynthesis, assembly, and export of these complex glycolipids to the cell surface are the object of the present study. Our genetic and biochemical evidence corroborates a model wherein the biosynthesis and translocation of DAT and PAT to the periplasmic space are coupled and topologically split across the plasma membrane. The formation of DAT occurs on the cytosolic face of the plasma membrane through the action of PapA3, FadD21, and Pks3/4; that of PAT occurs on the periplasmic face via transesterification reactions between DAT substrates catalyzed by the acyltransferase Chp2 (Rv1184c). The integral membrane transporter MmpL10 is essential for DAT to reach the cell surface, and its presence in the membrane is required for Chp2 to be active. Disruption of mmpL10 or chp2 leads to an important build-up of DAT inside the cells and to the formation of a novel form of unsulfated acyltrehalose esterified with polymethyl-branched fatty acids normally found in sulfolipids that is translocated to the cell surface. PMID:25124040

Belardinelli, Juan Manuel; Larrouy-Maumus, Gérald; Jones, Victoria; Sorio de Carvalho, Luiz Pedro; McNeil, Michael R; Jackson, Mary

2014-10-01

382

DNA translocation through an array of kinked nanopores.  

PubMed

Synthetic solid-state nanopores are being intensively investigated as single-molecule sensors for detection and characterization of DNA, RNA and proteins. This field has been inspired by the exquisite selectivity and flux demonstrated by natural biological channels and the dream of emulating these behaviours in more robust synthetic materials that are more readily integrated into practical devices. So far, the guided etching of polymer films, focused ion-beam sculpting, and electron-beam lithography and tuning of silicon nitride membranes have emerged as three promising approaches to define synthetic solid-state pores with sub-nanometre resolution. These procedures have in common the formation of nominally cylindrical or conical pores aligned normal to the membrane surface. Here we report the formation of 'kinked' silica nanopores, using evaporation-induced self-assembly, and their further tuning and chemical derivatization using atomic-layer deposition. Compared with 'straight through' proteinaceous nanopores of comparable dimensions, kinked nanopores exhibit up to fivefold reduction in translocation velocity, which has been identified as one of the critical issues in DNA sequencing. Additionally, we demonstrate an efficient two-step approach to create a nanopore array exhibiting nearly perfect selectivity for ssDNA over dsDNA. We show that a coarse-grained drift-diffusion theory with a sawtooth-like potential can reasonably describe the velocity and translocation time of DNA through the pore. By control of pore size, length and shape, we capture the main functional behaviours of protein pores in our solid-state nanopore system. PMID:20651807

Chen, Zhu; Jiang, Yingbing; Dunphy, Darren R; Adams, David P; Hodges, Carter; Liu, Nanguo; Zhang, Nan; Xomeritakis, George; Jin, Xiaozhong; Aluru, N R; Gaik, Steven J; Hillhouse, Hugh W; Brinker, C Jeffrey

2010-08-01

383

DNA translocation through an array of kinked nanopores  

NASA Astrophysics Data System (ADS)

Synthetic solid-state nanopores are being intensively investigated as single-molecule sensors for detection and characterization of DNA, RNA, and proteins. This field has been inspired by the exquisite selectivity and flux demonstrated by natural biological channels and the dream of emulating these behaviors in more robust synthetic materials that are more readily integrated into practical devices. To date, the guided etching of polymer films, focused ion beam sculpting, and electron-beam lithography and tuning of silicon nitride membranes have emerged as three promising approaches to define synthetic solid-state pores with sub-nanometer resolution. These procedures have in common the formation of nominally cylindrical or conical pores aligned normal to the membrane surface. Here we report the formation of 'kinked' silica nanopores, using evaporation induced self-assembly, and their further tuning and chemical derivatization using atomic layer deposition. Compared to 'straight-through' proteinaceous nanopores of comparable dimensions, kinked nanopores exhibit a factor of up to 5x reduction in translocation velocity, which has been identified as one of the critical issues in DNA sequencing. Additionally we demonstrate an efficient two-step approach to create a nanopore array exhibiting nearly perfect selectivity for ssDNA over dsDNA. We show that a coarse-grained drift-diffusion theory with a sawtooth like potential can reasonably describe the velocity and translocation time of DNA through the pore. By control of pore size, length, and shape, we capture the major functional behaviors of protein pores in our solid-state nanopore system.

Chen, Zhu

384

DNA translocation through an array of kinked nanopores  

NASA Astrophysics Data System (ADS)

Synthetic solid-state nanopores are being intensively investigated as single-molecule sensors for detection and characterization of DNA, RNA and proteins. This field has been inspired by the exquisite selectivity and flux demonstrated by natural biological channels and the dream of emulating these behaviours in more robust synthetic materials that are more readily integrated into practical devices. So far, the guided etching of polymer films, focused ion-beam sculpting, and electron-beam lithography and tuning of silicon nitride membranes have emerged as three promising approaches to define synthetic solid-state pores with sub-nanometre resolution. These procedures have in common the formation of nominally cylindrical or conical pores aligned normal to the membrane surface. Here we report the formation of `kinked' silica nanopores, using evaporation-induced self-assembly, and their further tuning and chemical derivatization using atomic-layer deposition. Compared with `straight through' proteinaceous nanopores of comparable dimensions, kinked nanopores exhibit up to fivefold reduction in translocation velocity, which has been identified as one of the critical issues in DNA sequencing. Additionally, we demonstrate an efficient two-step approach to create a nanopore array exhibiting nearly perfect selectivity for ssDNA over dsDNA. We show that a coarse-grained drift-diffusion theory with a sawtooth-like potential can reasonably describe the velocity and translocation time of DNA through the pore. By control of pore size, length and shape, we capture the main functional behaviours of protein pores in our solid-state nanopore system.

Chen, Zhu; Jiang, Yingbing; Dunphy, Darren R.; Adams, David P.; Hodges, Carter; Liu, Nanguo; Zhang, Nan; Xomeritakis, George; Jin, Xiaozhong; Aluru, N. R.; Gaik, Steven J.; Hillhouse, Hugh W.; Jeffrey Brinker, C.

2010-08-01

385

Resolution of ion translocating proteolipid subclasses active in bacterial calcification.  

PubMed

Formation of calcium hydroxyapatite occurs on membrane surfaces via interaction of calcium, inorganic phosphate, phospholipids, calcifiable proteolipids, and ion flux to and from the nucleating site. Recently, this laboratory reported that proteolipids from the calcifying bacterium, Bacterionema matruchotti, act as an ionophore when reconstituted into bacteriorhodopsin-proteoliposomes. This ionophoric activity is blocked by [14C]dicyclohexylcarbodiimide ([14C]DCCD). SDS-PAGE shows that [14C]DCCD binds to a single band of Mr 8500. To determine whether proteins other than the [14C]DCCD-binding protein are involved, we examined the function of proteolipid species extracted by solvents of differing polarity. Proteolipids were isolated independently from chloroform:methanol (2:1) and chloroform:methanol:HCl (200:100:1) extracts of the bacteria by Sephadex LH-20 chromatography and were electrophoresed on 12.5% acrylamide gels. The chloroform:methanol extract contained a major hand at Mr 10,000 that was not present in gels of proteolipid isolated by acidified solvent. Proteolipids extracted in chloroform:methanol:HCl included a broad band at Mr 8500, which co-migrated with the [14C] DCCD-binding protein. The rate and extent of proton translocation were not altered when either proteolipid extract was added individually to bacteriorhodopsin proteoliposomes. However, when proteolipids isolated from the chloroform:methanol and chloroform:methanol:HCl extracts were combined, the rate and extent of translocation were increased. These data demonstrate that at least two proteolipid proteins are necessary for ionophoric activity, the Mr 10,000 protein isolated by chloroform:methanol 2:1 and the [14C]DCCD-binding protein requiring acidified solvent for extraction. PMID:2478602

Swain, L D; Renthal, R D; Boyan, B D

1989-06-01

386

Biosynthesis and Translocation of Unsulfated Acyltrehaloses in Mycobacterium tuberculosis*  

PubMed Central

A number of species-specific polymethyl-branched fatty acid-containing trehalose esters populate the outer membrane of Mycobacterium tuberculosis. Among them, 2,3-diacyltrehaloses (DAT) and penta-acyltrehaloses (PAT) not only play a structural role in the cell envelope but also contribute to the ability of M. tuberculosis to multiply and persist in the infected host, promoting the intracellular survival of the bacterium and modulating host immune responses. The nature of the machinery, topology, and sequential order of the reactions leading to the biosynthesis, assembly, and export of these complex glycolipids to the cell surface are the object of the present study. Our genetic and biochemical evidence corroborates a model wherein the biosynthesis and translocation of DAT and PAT to the periplasmic space are coupled and topologically split across the plasma membrane. The formation of DAT occurs on the cytosolic face of the plasma membrane through the action of PapA3, FadD21, and Pks3/4; that of PAT occurs on the periplasmic face via transesterification reactions between DAT substrates catalyzed by the acyltransferase Chp2 (Rv1184c). The integral membrane transporter MmpL10 is essential for DAT to reach the cell surface, and its presence in the membrane is required for Chp2 to be active. Disruption of mmpL10 or chp2 leads to an important build-up of DAT inside the cells and to the formation of a novel form of unsulfated acyltrehalose esterified with polymethyl-branched fatty acids normally found in sulfolipids that is translocated to the cell surface. PMID:25124040

Belardinelli, Juan Manuel; Larrouy-Maumus, Gerald; Jones, Victoria; Sorio de Carvalho, Luiz Pedro; McNeil, Michael R.; Jackson, Mary

2014-01-01

387

Molecular cytogenetic characterization of t(14;19)(q32;p13), a new recurrent translocation in B cell malignancies.  

PubMed

Translocations involving an immunoglobulin (IG) locus are a recurring theme in B cell neoplasia. The rearrangements lead to the joining of an IG gene with a (proto)oncogene, whereby the latter comes under the influence of transcription-stimulating sequences in the constitutively active IG locus resulting in deregulation of the oncogene and neoplastic growth. We present here three cases of B cell neoplasia that showed a t(14;19)(q32;p13) by karyotypic analysis. Detailed molecular cytogenetic characterization of the breakpoints on chromosomes 14 and 19 in the two cases from which extra material was available, demonstrated the involvement of the immunoglobulin heavy-chain (IGH@)-variable region on chromosome 14 in both and, in one case, that the breakpoint was within the BRD4 gene on chromosome 19. Against the background of what one knows about IGH@ involvement in lymphatic malignancies, it is difficult to envisage a fusion gene with qualitatively altered protein product as the crucial pathogenetic outcome of the translocation. In spite of the fact that we found BRD4 split by the t(14;19)(q32;p13) in one of the two informative cases, we cannot be sure that this was the pathogenetically relevant target gene. Other pathogenetic possibilities could be deregulation of the neighboring NOTCH3 and/or ABHD9 genes, located distal to BRD4 in 19p13. PMID:17406891

Micci, Francesca; Panagopoulos, Ioannis; Tjønnfjord, Geir E; Kolstad, Arne; Delabie, Jan; Beiske, Klaus; Heim, Sverre

2007-05-01

388

Robertsonian translocation between chromosomes (no.21/14) in relation to the history of spontaneous abortion in a family  

PubMed Central

Background: Approximately 205 million pregnancies occur each year in the worldwide. On the other hand, Spontaneous abortion has been reported in 15-20% of all diagnosed pregnancies. The most common cause of spontaneous abortion is chromosomal abnormalities of the embryo. Robertsonian translocation carriers specially 21-14 are the most common balanced rearrangement among the carrier couples with the history of spontaneous abortion. In order to search for balanced chromosomal rearrangement and cytogenetic disorders, 10 members of related family with consanguinity marriage with the history of recurrent miscarriage were assessed. Case: Cytogenetic evaluation on the basis G-banding technique at high resolution was performed in 3 couples and their related family with the history of idiopathic RSA in order to postulate any balanced chromosomal rearrangement. Conclusion: six members of them appeared with robertsonian balanced translocation between chromosome No.21 to No. 14 with the karyotype of 45, XX, t (14, 21) and 45, XY, t (14, 21), which this results are in agreement with several similar works which claimed that the risk of spontaneous abortion in couples with balanced chromosomal rearrangements is higher compared with general population. Considering to results of present study, it seems as if the cytogenetic analysis of couples with the history of recurrent abortions should be suggested compulsory to estimate the probable presence of any chromosomal rearrangement. This offer wills valuable information for genetic consulting.

Hasanzadeh-NazarAbadi, Mohammad; Baghbani, Fatemeh; Namazi, Iman; Mirzaee, Salmeh

2014-01-01

389

Impact of Robertsonian translocation on meiosis and reproduction: an impala (Aepyceros melampus) model.  

PubMed

The captive bred animal populations showing centric fusion polymorphism can serve as a model for analysis of the impact of the rearrangement on meiosis and reproduction. The synapsis of homologous chromosomes and the frequency and distribution of meiotic recombination events were studied in pachytene spermatocytes of captive bred male impalas (Aepyceros melampus) polymorphic for der(14;20) by immunofluorescent analysis and fluorescence in situ hybridization. The chromosomes 14 and 20 involved in the centric fusion were significantly shorter due to the loss of sat I repeats indicating ancient origin of the rearrangement. The fused chromosome and the normal acrocentric chromosomes 14 and 20 formed trivalent in pachynema which showed either protruding proximal ends of the acrocentric chromosomes or single axis with synaptic adjustment in the pericentromeric region. There was no significant difference in the number of recombination events per cell between the group of translocation heterozygotes and the animals with normal karyotype. A significant reduction in the number of recombination events was observed in the trivalent chromosomes compared to the normal chromosomes 14 and 20. The level of the recombination reduction was related to the trivalent configuration. The centric fusion der(14;20) was not apparently demonstrated by any spermatogenic defects or reproductive impairment in heterozygous impalas. However, the high incidence of the chromosomal polymorphism within the captive bred population shows the importance of cytogenetic examinations in captive breeding and wildlife conservation programs, especially in the case of reintroduction of the endangered species. PMID:24464333

Vozdova, Miluse; Sebestova, Hana; Kubickova, Svatava; Cernohorska, Halina; Awadova, Thuraya; Vahala, Jiri; Rubes, Jiri

2014-05-01

390

Performance Evaluation of Reverberant Chamber Background Noise Levels  

E-print Network

? fan-? background? separati on,? the? loudness? rating? of? the? fan? does?not?change?as?the?minimum?perceived?loudness?a t?these?frequencies?is?very?high.?At? very? high? frequencies? (greater? than? 5? kHz),? the? fan ? does? not? generate? any...?Rating?with?Different?BKG?Levels?..... .......................................?? 52? 1? ? 1. ? INTRODUCTION? Proper? Ventilation? is? essential? in? order? to? maintai n? acceptable? indoor? air? quality.? Ventilation? is? primarily? provided? through? mechanica l? devices? such? as? inline? fans,? bathroom/utility? fans...

Ravi, Sankaranarayana

2012-02-14

391

Looking for Cosmic Neutrino Background  

NASA Astrophysics Data System (ADS)

Since the discovery of neutrino oscillation in atmospheric neutrinos by the Super-Kamiokande experiment in 1998, study of neutrinos has been one of exciting fields in high-energy physics. All the mixing angles were measured. Quests for 1) measurements of the remaining parameters, the lightest neutrino mass, the CP violating phase(s), and the sign of mass splitting between the mass eigenstates m3 and m1, and 2) better measurements to determine whether the mixing angle theta23 is less than pi/4, are in progress in a well-controlled manner. Determining the nature of neutrinos, whether they are Dirac or Majorana particles is also in progress with continuous improvement. On the other hand, although the ideas of detecting cosmic neutrino background have been discussed since 1960s, there has not been a serious concerted effort to achieve this goal. One of the reasons is that it is extremely difficult to detect such low energy neutrinos from the Big Bang. While there has been tremendous accumulation of information on Cosmic Microwave Background since its discovery in 1965, there is no direct evidence for Cosmic Neutrino Background. The importance of detecting Cosmic Neutrino Background is that, although detailed studies of Big Bang Nucleosynthesis and Cosmic Microwave Background give information of the early Universe at ~a few minutes old and ~300 k years old, respectively, observation of Cosmic Neutrino Background allows us to study the early Universe at ˜ 1 sec old. This article reviews progress made in the past 50 years on detection methods of Cosmic Neutrino Background.

Yanagisawa, Chiaki

2014-06-01

392

Jumping translocations are common in solid tumor cell lines and result in recurrent fusions of whole chromosome arms  

Microsoft Academic Search

Jumping translocations (JTs) and segmental jumping translocations (SJTs) are unbalanced translocations involving a donor chromosome arm or chromosome segment that has fused to multiple recipient chromosomes. In leukemia, where JTs have been predominantly observed, the donor segment (usually 1q) preferentially fuses to the telomere regions of recipient chromosomes. In this study, spectral karyotyping (SKY) and FISH analysis revealed 188 JTs

Hesed M. Padilla-Nash; Kerstin Heselmeyer-Haddad; Danny Wangsa; Hongen Zhang; B. Michael Ghadimi; Merryn Macville; Meena Augustus; Eva Hilgenfeld; Thomas Ried

2001-01-01

393

Stochastic gravitational-wave background from cosmological supernovae  

SciTech Connect

Based on new developments in the understanding of supernovae (SNe) as gravitational-wave (GW) sources we estimate the GW background from all cosmic SNe. For a broad range of frequencies around 1 Hz, this background is crudely comparable to the GW background expected from standard inflationary models. While our estimate remains uncertain within several orders of magnitude, the SN GW background may become detectable by second-generation space-based interferometers such as the proposed Big Bang Observatory (BBO). By the same token, the SN GWs may become a foreground for searches of the inflationary GWs, in particular, for sub-Hz frequencies where the SN background is Gaussian and where the BBO will be most sensitive. SN simulations lasting far beyond the usual cutoff of about 1 s are needed for more robust predictions in the sub-Hz frequency band. An even larger GW background can arise from a hypothetical early population of massive stars, although their GW source strength as well as their abundance are currently poorly understood.

Buonanno, Alessandra; Sigl, Guenter [GReCO, Institut d'Astrophysique de Paris, C.N.R.S., 98 bis boulevard Arago, F-75014 Paris (France); AstroParticule et Cosmologie (APC), 11, place Marcelin Berthelot, F-75005 Paris (France); Raffelt, Georg G. [Max-Planck-Institut fuer Physik (Werner-Heisenberg-Institut), Foehringer Ring 6, 80805 Munich (Germany); Janka, Hans-Thomas; Mueller, Ewald [Max-Planck-Institut fuer Astrophysik, Karl-Schwarzschild-Str. 1, 85741 Garching (Germany)

2005-10-15

394

Detector Background at Muon Colliders  

SciTech Connect

Physics goals of a Muon Collider (MC) can only be reached with appropriate design of the ring, interaction region (IR), high-field superconducting magnets, machine-detector interface (MDI) and detector. Results of the most recent realistic simulation studies are presented for a 1.5-TeV MC. It is shown that appropriately designed IR and MDI with sophisticated shielding in the detector have a potential to substantially suppress the background rates in the MC detector. The main characteristics of backgrounds are studied.

Mokhov, N.V.; Striganov, S.I.; /Fermilab

2011-09-01

395

Background music and cognitive performance.  

PubMed

The present experiment employed standardized test batteries to assess the effects of fast-tempo music on cognitive performance among 56 male and female university students. A linguistic processing task and a spatial processing task were selected from the Criterion Task Set developed to assess verbal and nonverbal performance. Ten excerpts from Mozart's music matched for tempo were selected. Background music increased the speed of spatial processing and the accuracy of linguistic processing. The findings suggest that background music can have predictable effects on cognitive performance. PMID:20865993

Angel, Leslie A; Polzella, Donald J; Elvers, Greg C

2010-06-01

396

Translocation dynamics of tRNA-mRNA in the ribosome.  

PubMed

Translocation of tRNA-mRNA complex in the ribosome is an essential step in the elongation cycle of protein synthesis. However, some important issues concerning the molecular mechanism of the tRNA-mRNA translocation catalyzed by EF-G.GTP or by EF-G.GDPNP remain controversial. For example, can EF-G.GTP selectively bind to the hybrid pretranslocation state or bind to both the non-rotated pretranslocation and the hybrid pretranslocation states? Does the greater potency of EF-G in the presence of GTP rather than GDPNP in facilitating translocation derive from the effects on transition from the classical non-rotated to hybrid state (the first step of the translocation) or on transition from the hybrid to posttranslocation state (the second step)? Here, based on our proposed model, we study theoretically the dynamics of the tRNA-mRNA translocation through the ribosome catalyzed by EF-G.GTP and by EF-G.GDPNP. By comparing our theoretical results with the available experimental data, we show that EF-G.GTP can also bind to the classical non-rotated pretranslocation state and the greater potency of GTP hydrolysis in facilitating translocation of tRNA-mRNA complex derives from its effects on the second step of the translocation process. PMID:23811427

Xie, Ping

2013-01-01

397

The effect of translocation on movement behaviour--a test of the assumptions of behavioural studies.  

PubMed

Animal movement behaviour is intensively investigated with capture-mark-recapture studies. For the analysis of such experiments, the influence of marking technique, handling and translocation of marked animals on movement pattern is of crucial importance since it may mask or overrule the effects of the main research question. Here we present a capture-mark-recapture experiment on the movement behaviour of the blue-winged grasshopper Oedipoda caerulescens. We analyzed the influence of translocation of individuals from familiar to unfamiliar sites. Our study clearly demonstrates a significant influence of translocation to unfamiliar sites on the movement behaviour of O. caerulescens. Translocated individuals moved longer distances, showed smaller daily turning angles, and thus movements were more directed than those of resident individuals. The effect of translocation on daily moved distances was most pronounced on the first day of the experiment. We thus conclude that at least for the first day after translocation, movement behaviour is significantly influenced by translocation itself. Data ignoring this influence will be unsuitable for the prediction of dispersal behaviour, habitat detection capability or habitat preference. PMID:19615610

Heidinger, Ina Monika Margret; Poethke, Hans-Joachim; Bonte, Dries; Hein, Silke

2009-09-01

398

Controlling DNA translocation through gate modulation of nanopore wall surface charges.  

PubMed

One major challenge of nanopore-based DNA sequencing technology is to find an efficient way to reduce DNA translocation speed so that each nucleotide can reside long enough in the pore for interrogation. Here we report the electrical tuning of DNA translocation speed by gate modulation of nanopore wall surface charges. We find that native surface-charge-induced counterions in the electroosmotic layer substantially enhance advection flow of fluid, which exerts stronger dragging forces on the translocating DNA, and thereby lowering the DNA translocation speed. We propose a feedback device architecture to regulate DNA translocation by modulating the effective wall surface charge density ?w*via lateral gate voltages--at the beginning, a positive gate bias is applied to weaken ?w* in order to enhance the capture rate of DNA molecule; upon detection of ionic current variance indicating DNA has been driven into the nanopore, gate bias is turned to be negative so that ?w* is reinforced and DNA translocation is retarded. We show that a gate electric field can dramatically decrease the DNA translocation speed at a rate about 55 ?m/s per 1 mV/nm. PMID:21662982

He, Yuhui; Tsutsui, Makusu; Fan, Chun; Taniguchi, Masateru; Kawai, Tomoji

2011-07-26

399

Quantitative Analysis of the Nanopore Translocation Dynamics of Simple Structured Polynucleotides  

PubMed Central

Nanopore translocation experiments are increasingly applied to probe the secondary structures of RNA and DNA molecules. Here, we report two vital steps toward establishing nanopore translocation as a tool for the systematic and quantitative analysis of polynucleotide folding: 1), Using ?-hemolysin pores and a diverse set of different DNA hairpins, we demonstrate that backward nanopore force spectroscopy is particularly well suited for quantitative analysis. In contrast to forward translocation from the vestibule side of the pore, backward translocation times do not appear to be significantly affected by pore-DNA interactions. 2), We develop and verify experimentally a versatile mesoscopic theoretical framework for the quantitative analysis of translocation experiments with structured polynucleotides. The underlying model is based on sequence-dependent free energy landscapes constructed using the known thermodynamic parameters for polynucleotide basepairing. This approach limits the adjustable parameters to a small set of sequence-independent parameters. After parameter calibration, the theoretical model predicts the translocation dynamics of new sequences. These predictions can be leveraged to generate a baseline expectation even for more complicated structures where the assumptions underlying the one-dimensional free energy landscape may no longer be satisfied. Taken together, backward translocation through ?-hemolysin pores combined with mesoscopic theoretical modeling is a promising approach for label-free single-molecule analysis of DNA and RNA folding. PMID:22225801

Schink, Severin; Renner, Stephan; Alim, Karen; Arnaut, Vera; Simmel, Friedrich C.; Gerland, Ulrich

2012-01-01

400

Mineralocorticoid and glucocorticoid receptor mRNA expression in the brain of translocated chukar (Alectoris chukar).  

PubMed

Although translocation is an important conservation tool in the effort to create self-sustaining wild populations of threatened species, avian translocations have a high failure rate and causes for failure are poorly understood. While "stress" is considered to play a major role in translocation failure, the physiological changes associated with chronic stress resulting from translocation have been investigated only recently. Translocation results in chronic stress-induced alterations of stress response physiology in the chukar (Alectoris chukar) and in the present study we tested the hypothesis that changes in the hypothalamic-pituitary-adrenal axis (HPA) are correlated with changes in the brain, specifically at the level of the glucocorticoid and mineralocorticoid receptors (GR and MR, respectively) in the hippocampus and hypothalamus. Our previous research has shown that there are apparent changes in GR and MR expression in the brain of experimentally chronically stressed European starlings (Sturnus vulgaris). In the present study however, translocation had no major detectable effect on levels of GR or MR mRNA expression in the hippocampus or hypothalamus of wild chukar suggesting that the observed dysregulation of the HPA axis by translocation may not be a result of such upstream changes. PMID:21118689

Dickens, Molly J; Meddle, Simone L; Michael Romero, L

2011-02-01

401

Genetic variation in natural and translocated populations of the endangered Delmarva fox squirrel (Sciurus niger cinereus)  

USGS Publications Warehouse

The Delmarva fox squirrel, Sciurus niger cinereus, is a federally listed endangered subspecies whose range has been reduced by 90%. In an attempt to increase both population size and range, translocation sites were established beginning in the 1960's by moving squirrels from the natural range to sites outside the current range. Although translocations have served as the primary component of the DFS recovery program, there has been very little post-release examination of the genetics of the translocation sites. In this study, we developed ten microsatellite loci, screened the three polymorphic loci, and sequenced a 330 bp fragment of the mitochondrial control region in order to assess levels of genetic variation in natural and translocated regions of Delmarva fox squirrels and to compare them to Southeastern fox squirrels (S. n. niger). Although we found low levels of microsatellite polymorphism, there were no differences in heterozygosity between natural and translocated regions, or between Delmarva and Southeastern fox squirrels. We found high levels of polymorphism in the mitochondrial control region. Our patterns of haplotype diversity suggest incomplete lineage sorting of the two subspecies. In general, our data suggest that the current levels of genetic variation in the translocated sites are representative of those found in the natural population, and we encourage the continued use of translocations as a major component of Delmarva fox squirrel recovery.

Lance, S.L.; Maldonado, J.E.; Bocetti, C.I.; Pattee, O.H.; Ballou, J.D.; Fleischer, R.C.

2003-01-01

402

Cosmic backgrounds of relic gravitons and their absolute normalization  

E-print Network

Provided the consistency relations are not violated, the recent Bicep2 observations pin down the absolute normalization, the spectral slope and the maximal frequency of the cosmic graviton background produced during inflation. The properly normalized spectra are hereby computed from the lowest frequencies (of the order of the present Hubble rate) up to the highest frequency range in the GHz region. Deviations from the conventional paradigm cannot be excluded and are examined by allowing for different physical possibilities including, in particular, a running of the tensor spectral index, an explicit breaking of the consistency relations and a spike in the high-frequency tail of the spectrum coming either from a post-inflationary phase dominated by a stiff fluid of from the contribution of waterfall fields in a hybrid inflationary context. The direct determinations of the tensor to scalar ratio at low frequencies, if confirmed by the forthcoming observations, will also affect and constrain the high-frequencies uncertainties. The limits on the cosmic graviton backgrounds coming from wide-band interferometers (such as Ligo/Virgo, Lisa and Bbo/Decigo) together with a more accurate scrutiny of the tensor B mode polarization at low frequencies will set direct bounds on the post-inflationary evolution and on other unconventional completions of the standard lore.

Massimo Giovannini

2014-05-24

403

Cosmic backgrounds of relic gravitons and their absolute normalization  

NASA Astrophysics Data System (ADS)

Provided the consistency relations are not violated, the recent BICEP2 observations pin down the absolute normalization, the spectral slope and the maximal frequency of the cosmic graviton background produced during inflation. The properly normalized spectra are hereby computed from the lowest frequencies (of the order of the present Hubble rate) up to the highest frequency range in the GHz region. Deviations from the conventional paradigm cannot be excluded and are examined by allowing for different physical possibilities including, in particular, a running of the tensor spectral index, an explicit breaking of the consistency relations and a spike in the high-frequency tail of the spectrum coming either from a post-inflationary phase dominated by a stiff fluid or from the contribution of waterfall fields in a hybrid inflationary context. The direct determinations of the tensor to scalar ratio at low frequencies, if confirmed by the forthcoming observations, will also affect and constrain the high-frequency uncertainties. The limits on the cosmic graviton backgrounds coming from wide-band interferometers (such as LIGO/Virgo, LISA and BBO/DECIGO) together with a more accurate scrutiny of the tensor B-mode polarization at low frequencies will set direct bounds on the post-inflationary evolution and on other unconventional completions of the standard lore.

Giovannini, Massimo

2014-11-01

404

EGFR and EGFRvIII undergo stress- and EGFR kinase inhibitor-induced mitochondrial translocalization: A potential mechanism of EGFR-driven antagonism of apoptosis  

PubMed Central

Background Epidermal growth factor receptor (EGFR) plays an essential role in normal development, tumorigenesis and malignant biology of human cancers, and is known to undergo intracellular trafficking to subcellular organelles. Although several studies have shown that EGFR translocates into the mitochondria in cancer cells, it remains unclear whether mitochondrially localized EGFR has an impact on the cells and whether EGFRvIII, a constitutively activated variant of EGFR, undergoes mitochondrial transport similar to EGFR. Results We report that both receptors translocate into the mitochondria of human glioblastoma and breast cancer cells, following treatments with the apoptosis inducers, staurosporine and anisomycin, and with an EGFR kinase inhibitor. Using mutant EGFR/EGFRvIII receptors engineered to undergo enriched intracellular trafficking into the mitochondria, we showed that glioblastoma cells expressing the mitochondrially enriched EGFRvIII were more resistant to staurosporine- and anisomycin-induced growth suppression and apoptosis and were highly resistant to EGFR kinase inhibitor-mediated growth inhibition. Conclusions These findings indicate that apoptosis inducers and EGFR-targeted inhibitors enhance mitochondrial translocalization of both EGFR and EGFRvIII and that mitochondrial accumulation of these receptors contributes to tumor drug resistance. The findings also provide evidence for a potential link between the mitochondrial EGFR pathway and apoptosis. PMID:21388543

2011-01-01

405

Reciprocal chromosome translocation associated with TDNA-insertion mutation in Arabidopsis: genetic and cytological analyses of consequences for gametophyte development and for construction of doubly mutant lines  

PubMed Central

Chromosomal rearrangements may complicate construction of Arabidopsis with multiple TDNA-insertion mutations. Here, crossing two lines homozygous for insertions in AtREV3 and AtPOLH (chromosomes I and V, respectively) and selfing F1 plants yielded non-Mendelian F2 genotype distributions: frequencies of +/++/+ and 1/1 2/2 progeny were only 0.42 and 0.25%. However, the normal development and fertility of double mutants showed AtPOLH-1 and AtREV3-2 gametes and 1/1 2/2 embryos to be fully viable. F2 distributions could be quantitatively predicted by assuming that F1 selfing produced inviable (1,2) and (+,+) gametophytes 86% of the time. Some defect intrinsic to the F1 selfing process itself thus appeared responsible. In selfing AtREV3 +/2 single mutants, imaging of ovules and pollen showed arrest or abortion, respectively, of half of gametophytes; however, gametogenesis was normal in AtREV3 2/2 homozygotes. These findings, taken together, suggested that T-DNA insertion at AtREV3 on chromosome I had caused a reciprocal I–V translocation. Spreads of meiosis I chromosomes in selfing AtREV3 +/2 heterozygotes revealed the predicted cruciform four-chromosome structures, which fluorescence in situ hybridization showed to invariably include both translocated and normal chromosomes I and V. Sequencing of the two junctions of T-DNA with AtREV3 DNA and the two with gene At5g59920 suggested translocation via homologous recombination between independent inverted-repeat T-DNA insertions. Thus, when crosses between TDNA-insertion mutants yield anomalous progeny distributions, TDNA-linked translocations should be considered. PMID:19082841

Curtis, Marc J.; Belcram, Katia; Bollmann, Stephanie R.; Tominey, Colin M.; Hoffman, Peter D.; Mercier, Raphael; Hays, John B.

2014-01-01

406

Recombination suppression in the vicinity of the breakpoints of a balanced 1:11 autosomal translocation associated with schizophrenia and other forms of major mental illness  

SciTech Connect

The frequency and extent of pairing failure around human translocations is unknown. We have examined the pattern of recombination around the breakpoints of a balanced autosomal translocation t(1:11)(q43:q21) associated with major mental illness. We have postulated that the association with mental illness in the family has not arisen by chance, but rather that functional disruption of a gene at or near a breakpoint site is responsible. Efforts to isolate the breakpoints for molecular analysis of the region are now at an advanced stage. On the other hand if pairing failure is occurring in the family in the region of the breakpoints, a susceptibility allele for mental illness, acting independently of the translocation, may be located some distance away. DNA was available from seventeen carriers and ten non-translocation carriers, giving a total of thirty-one informative meioses spanning 4 generations. The derivative one and eleven chromosomes were also isolated in somatic cell hybrids and were used to confirm allele phase. We genotyped the pedigree members using nine markers covering 30 cMs on either side of both the chromosome one and eleven breakpoints. No recombinants were found with markers within 3 cMs of either breakpoint. Four markers at an average of 7 cMs respectively on either side of the two breakpoints gave a total of three crossovers from thirty-one meioses versus an expected 9, demonstrating (p<0.05) significant recombination suppression. By contrast, examination of chromosome regions at greater distances from the breakpoints showed recombination rates similar to those expected from CEPH data with no evidence of suppression. We conclude that crossover suppression occurs in this family but is restricted to a region within 7 cMs of the breakpoints.

He, L.; Blackwood, D.H.R.; Maclean, A.W. [MRC Human Genetics Unit, Edinburgh (United Kingdom)] [and others

1994-09-01

407

Mathematical background of Parrondo's paradox  

NASA Astrophysics Data System (ADS)

Parrondo's paradox states that there are losing gambling games which, when being combined stochastically or in a suitable deterministic way, give rise to winning games. Here we investigate the probabilistic background. We show how the properties of the equilibrium distributions of the Markov chains under consideration give rise to the paradoxical behavior, and we provide methods how to find the best a priori strategies.

Behrends, Ehrhard

2004-05-01

408

Educational Attainment and Family Background  

Microsoft Academic Search

This paper analyses the effect of aspects of family background, such as family income and parental education, on the educational attainment of persons born from 1967 to 1972. Family income is measured at different periods of a child's life to separate long-term versus short-term effects of family income on educational choices. We find that permanent income matters to a certain

Arild Aakvik; Kjell Gunnar Salvanes; Kjell Vaage

2005-01-01

409

Hurricanes and Tropical Meteorology Background  

E-print Network

- 1 - Hurricanes and Tropical Meteorology Background: Over the last 20 years, hurricane research at AOML has focused on improved scientific understanding of hurricanes and of tropical meteorology scientific goals for AOMLs hurricane research derive from the U.S. Weather Research Programs (USWRP

410

Wormhole on the Lobachevsky background.  

National Technical Information Service (NTIS)

The exact spherical symmetric static solution of Rosen like equations of the bi metric theory is investigated. The background metric is not flat, but curved, with the Lobachevsky spatial sections and 'cosmic time' c(sup 2) d t(sup 2). There are two branch...

M. N. Tentyukov

1994-01-01

411

Shark Fact or Fiction? Background  

E-print Network

Shark Fact or Fiction? Background: This is a fun classroom activity based on the basic biology of sharks. This goes well with the enclosed Project Shark Awareness PowerPoint and should be used in conjunction with the presentation. Materials: Shark Fact of Fiction activity sheet and answer key

Watson, Craig A.

412

A Little Background Music, Please.  

ERIC Educational Resources Information Center

Background music could be used to provide a pleasant beginning for the school day, to help keep students quiet and relaxed in the school cafeteria at lunchtime, and to provide a midafternoon lift for bored and tired children. The most effective music pleases children without overly exciting them through jarring rhythms and loud dynamics. (nine…

Giles, Martha Mead

1991-01-01

413

Teacher Pensions: A Background Paper  

ERIC Educational Resources Information Center

Pensions are an important but comparatively unexamined component of human resource policies in education. In an increasingly competitive world where employees are more mobile than ever, pension policies that were designed in the last century may be out of step with the needs of both individuals and schools. This background paper aims to foster…

Hansen, Janet S.

2008-01-01

414

Teaching about Natural Background Radiation  

ERIC Educational Resources Information Center

Ambient gamma dose rates in air were measured at different locations (indoors and outdoors) to demonstrate the ubiquitous nature of natural background radiation in the environment and to show that levels vary from one location to another, depending on the underlying geology. The effect of a lead shield on a gamma radiation field was also…

Al-Azmi, Darwish; Karunakara, N.; Mustapha, Amidu O.

2013-01-01

415

Modeling Dense Stellar Systems: Background  

E-print Network

I provide some background about recent efforts made in modeling dense stellar systems, within the context of the MODEST initiative. During the last four years, we have seen more than fifteen MODEST workshops, with an attendance between twenty and a hundred participants, and topics ranging from very specialized discussions to rather general overviews.

Piet Hut

2006-10-07

416

Quantization by cosmic background radiation  

Microsoft Academic Search

It is suggested that various modes in the cosmic background radiation field may account for the discrete properties exhibited by small systems. In particular, this view is applied to the 1, 2-, and 3-D oscillators and the hydrogen atom, systems which were treated by Schrodinger in his first papers on quantum mechanics. The usual energy formulas for the above systems

James T. Dehn

1989-01-01

417

Fifty Percent Law: Background Paper.  

ERIC Educational Resources Information Center

This paper provides background information about a statute that affects the fiscal operation of California community colleges. The Fifty Percent Law (Education Code 84362) requires "there shall be expended each fiscal year for payment of salaries of classroom instructors by a community college district, 50 percent of the district's current expense…

Community Coll. League of California, Sacramento.

418

The Cosmic Microwave Background Radiation  

NSDL National Science Digital Library

This online article, from Cosmic Horizons: Astronomy at the Cutting Edge, provides an overview of how scientists are working to explain the origin of the universe. Specifically, it discusses the two major theories about the origin of the universe (Big Bang and Steady State), the search for microwave background radiation, and the discovery of the first observational evidence to support the Big Bang theory.

419

Translocation to a fragmented landscape: survival, movement, and site fidelity of Northern Bobwhites.  

PubMed

Habitat fragmentation, degradation, and loss have taxed early-successional species including the Northern Bobwhite (Colinus virginianus) and numerous grassland obligate birds. Translocation is often applied to counteract the consequences of habitat fragmentation through the creation, reestablishment, or augmentation of wild populations for the purposes of conservation, biodiversity maintenance. However, the implementation of these techniques is often conducted without valid experimental designs and therefore lacks robust, empirical data needed to evaluate and advance the knowledge and application of translocation. Despite the increasing amount of habitat management applied to patches among fragmented landscapes, a paucity of source populations often limits natural (re)colonization. As such, translocation may serve as a surrogate to natural dispersal, but its efficacy among fragmented landscapes is uncertain. Few studies exist that have assessed site fidelity, movement, and survival of individuals following translocation among fragmented landscapes. Thus, we experimentally evaluated the efficacy of translocation using known-fate and multi-strata models to evaluate hypotheses of temporal, biological, and group effects on survival and movement of translocated and resident bobwhites. We did not detect differences in survival or movement between translocated and resident bobwhites, suggesting that movement of individuals to a fragmented habitat does not negatively influence these demographic attributes. Based on these data, we suggest that two site-specific criteria should be met prior to instituting translocation: habitat management should be conducted to ensure that quality habitat exists and the patch size should be a minimum of 600 ha of quality habitat (poorer sites may warrant even larger patches). Translocation is a viable conservation method for increasing abundance in patches when habitat quality is high but source populations are limited. PMID:20597288

Terhune, Theron M; Sisson, D Clay; Palmer, William E; Faircloth, Brant C; Stribling, H Lee; Carroll, John P

2010-06-01

420

Translocation of ethanolamine phosphoglyceride is required for initiation of apoptotic death in OLN-93 oligodendroglial cells.  

PubMed

The possible interplay between extracellular signal-regulated protein kinase (ERK) activation and ethanolamine phosphoglycerides (PG) membrane bilayer translocation following oxidative stress (OS) (0.5 mM H2O2/0.05 mM Fe2+), was examined in oligodendroglia, OLN93, cells with altered plasma membrane PG composition. Cells supplemented with 50 microM docosahexaenoic acid (DHA, 22:6n3) to increase the number of potential double bond targets for OS in ethanolamine-PG (EPG) were compared to cells with diminished content of EPG, attained by the addition of 0.5 mM N,N-dimethylethanolamine (dEa). After 30 min OS, EPG translocation accompanied by sustained ERK activation and nuclear translocation culminating in apoptosis was found in DHA-supplemented cells in contrast to no EPG translocation, a brief ERK activation, but no nuclear translocation, and no cell death in DHA/dEa-supplemented cells. DHA/dEa-supplemented cells pretreated with the protein-tyrosine phosphatases inhibitor Na3VO4 followed by OS, although expressing a sustained ERK activation and nuclear translocation, failed to show apoptosis and lacked EPG translocation. In DHA-supplemented cells U0126, a MEK inhibitor, prevented ERK activation and EPG translocation and protected from cell death. These findings most likely indicate that ERK activation is an indispensable component for the signaling cascades leading to EPG translocation but only activation of the latter is leading to OS-induced apoptotic cell death. PMID:16341587

Brand, Annette; Yavin, Ephraim

2005-10-01