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1

Measurement of background translocation frequencies in individuals with clones  

SciTech Connect

In the leukemia case the unseparated B and T lymphocytes had a high translocation frequency even after 0.0014, respectively. After purging all clones from the data, the translocation frequencies for Bio 8 and Bio 23 were 0.00750.0014 and 0.0073 metaphases were scored for chromosomal aberrations,, specifically reciprocal translocations, using fluorescence in situ hybridization (FISH). Metaphase spreads were used from two healthy, unexposed individuals (not exposed to radiation, chemotherapy or radiotherapy) and one early B- precursor acute lymphocytic leukemia (ALL) patient (metaphase spreads from both separated T lymphocytes and unseparated B and T lymphocytes were scored). All three individuals had an abnormally high translocation frequency. The high translocation frequencies resulted from clonal expansion of specific translocated chromosomes. I show in this thesis that by purging (discounting or removing) clones from the data of unexposed individuals, one can obtain true background translocation frequencies. In two cases, Bio 8 and Bio 23, the measured translocation frequency for chromosomes 1, 2 and 4 was 0.0124 purging all of the clones from the data. This high translocation frequency may be due to a low frequency of some clones and may not be recognized. The separated T lymphocytes had a higher translocation frequency than expected.

Wade, M.J.

1996-08-01

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

Rapid translocation frequency analysis in humans decades after exposure to ionizing radiation.  

PubMed

This paper presents an analysis of the utility of fluorescence in situ hybridization (FISH) with whole-chromosome probes for measurement of the genomic frequency of translocations found in the peripheral blood of individuals exposed to ionizing radiation. First, we derive the equation: Fp = 2.05fp(1-fp)FG, relating the translocation frequency, Fp, measured using FISH to the genomic translocation frequency, FG, where fp is the fraction of the genome covered by the composite probe. We demonstrate the validity of this equation by showing that: (a) translocation detection efficiency predicted by the equation is consistent with experimental data as fp is changed; (b) translocation frequency dose-response curves measured in vitro using FISH agree well with dicentric frequency dose-response curves measured in vitro using conventional cytogenetic procedures; and (c) the genomic translocation frequencies estimated from FISH measurements for 20 Hiroshima A-bomb survivors and four workers exposed to ionizing radiation during the Y-12 criticality accident are approximately the same as the translocation frequencies measured using G-banding. We also show that translocation frequency dose response curves estimated using FISH are similar for Hiroshima A-bomb survivors and for first division lymphocytes irradiated in vitro. We conclude with a discussion of the potential utility of translocation frequency analysis for assessment of the level of acute radiation exposure independent of the time between analysis and exposure. PMID:1353776

Lucas, J N; Awa, A; Straume, T; Poggensee, M; Kodama, Y; Nakano, M; Ohtaki, K; Weier, H U; Pinkel, D; Gray, J

1992-07-01

4

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

5

Increased Frequency of Chromosome Translocations Associated with Diagnostic X-Ray Examinations  

PubMed Central

Informative studies of cancer risks associated with medical radiation are difficult to conduct owing to low radiation doses, poor recall of diagnostic X rays, and long intervals before cancers occur. Chromosome aberrations have been associated with increased cancer risk and translocations are a known radiation biomarker. Seventy-nine U.S. radiologic technologists were selected for blood collection, and translocations were enumerated by whole chromosome painting. We developed a dose score to the red bone marrow for medical radiation exposure from X-ray examinations reported by the technologists that they received as patients. Using Poisson regression, we analyzed translocations in relation to the dose scores. Each dose score unit approximated 1 mGy. The estimated mean cumulative red bone marrow radiation dose score was 42 (range 1–265). After adjustment for age, occupational radiation, and radiotherapy for benign conditions, translocation frequencies significantly increased with increasing red bone marrow dose score with an estimate of 0.007 translocations per 100 CEs per score unit (95% CI, 0.002 to 0.013; P = 0.01). Chromosome damage has been linked with elevated cancer risk, and we found that cumulative radiation exposure from medical X-ray examinations was associated with increased numbers of chromosome translocations. PMID:18666821

Bhatti, Parveen; Doody, Michele M.; Preston, Dale L.; Kampa, Diane; Ron, Elaine; Weinstock, Robert W.; Simon, Steven; Edwards, Alan A.; Sigurdson, Alice J.

2009-01-01

6

Chromosome translocation frequencies measured in interphase lymphocytes of A-bomb survivors  

SciTech Connect

The authors have compared metaphase chromosome translocation frequencies with interphase chromosome aberration frequencies measured in lymphocytes of A-bomb survivors using FISH. Whole chromosome probes for chromosomes 1, 2, and 4 were used to measure metaphase translocations, and a repetitive probe that binds to the paracentromeric 1q12 locus of chromosome 1 (pUC1.77) was used to measure interphase chromosome aberrations. Doses for the individuals studied ranged from 0 to 4 Gy. The interphase hybridization pattern appeared as one or two distinct spots in normal interphase cells, and as three distinct spots in cells carrying a translocation. Although pUC1.77 is small ([approximately]1% of genome), the increased speed in scoring interphase cells (a factor of 50 faster than scoring metaphase cells) compensates for the small size of the probe. A linear correlation was found between interphase and metaphase aberration frequencies. The data suggest that aberration frequencies may be obtained from interphase cells of individuals exposed decades previously, where dicentrics have decayed. Detection of interphase chromosome aberrations should facilitate automation of chromosome aberration scoring.

Cantu, A.; Richards, C.; Burroughs, F.; Lucas, J.N. (Lawrence Livermore National Lab., CA (United States))

1993-01-01

7

High frequency of t(14;18) translocation in salivary gland lymphomas from Sjogren's syndrome patients  

PubMed Central

Sjogren's syndrome (SS) is a chronic autoimmune disorder characterized by lymphocytic infiltration of the salivary and lacrimal glands. These patients have a markedly increased frequency of developing non- Hodgkin's lymphoma in their salivary glands and cervical lymph nodes. Translocations of proto-oncogene bcl-2 t(14;18) were observed in five of seven SS-associated lymphomas by Southern blot analysis. Using primers specific for chromosomes 14 and 18, translocation of the proto- oncogene bcl-2 was detected by polymerase chain reaction (PCR) in all five lymphomas positive by Southern blot analysis. Among SS patients lacking clinical evidence of coexistent lymphoma, no bcl-2 translocations were detected in 50 consecutive salivary gland biopsies. Of particular interest, pre-lymphoma biopsies were available from the seven SS patients who subsequently developed lymphoma and these DNA samples lacked detectable t(14;18) translocations even though they exhibited oligoclonal rearrangements of their immunoglobulin genes. We conclude that the great sensitivity of PCR can help us in detecting early onset of lymphoma in SS patients and aid in understanding the transition from autoimmunity to lymphoma. PMID:1940802

1991-01-01

8

International study of factors affecting human chromosome translocations  

Microsoft Academic Search

Chromosome translocations in peripheral blood lymphocytes of normal, healthy humans increase with age, but the effects of gender, race, and cigarette smoking on background translocation yields have not been examined systematically. Further, the shape of the relationship between age and translocation frequency (TF) has not been definitively determined. We collected existing data from 16 laboratories in North America, Europe, and

Alice J. Sigurdson; Mina Ha; Michael Hauptmann; Parveen Bhatti; Radim J. Sram; Olena Beskid; E. Janet Tawn; Caroline A. Whitehouse; Carita Lindholm; Mimako Nakano; Yoshiaki Kodama; Nori Nakamura; Irena Vorobtsova; Ursula Oestreicher; Günther Stephan; Lee C. Yong; Manfred Bauchinger; Ernst Schmid; Hai Won Chung; Firouz Darroudi; Laurence Roy; Phillipe Voisin; Joan F. Barquinero; Gordon Livingston; David Blakey; Isamu Hayata; Wei Zhang; Chunyan Wang; L. Michelle Bennett; L. Gayle Littlefield; Alan A. Edwards; Ruth A. Kleinerman; James D. Tucker

2008-01-01

9

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

10

Determination of the optimal excitation frequency range in background flows.  

PubMed

The chaotization of a vortical flow caused by a nonstationary incident flow is studied by the examples of several dynamically consistent models. It is shown that for relatively small values of excitation amplitude, the chaotization of such flows and, correspondingly, chaotic transport of passive scalars is determined by a small number of nonlinear resonances with frequencies close to the excitation frequency. Hence, the analysis of locations and overlaps of these resonances in the considered models makes it possible to derive fairly good estimates of excitation frequencies that are optimal for the chaotic transport. PMID:18377058

Izrailsky, Yu G; Koshel, K V; Stepanov, D V

2008-03-01

11

Background spatial frequency influences perception of luminance-based apparent movement.  

PubMed

Apparent movement occurs when stimulus figures are presented at different spatial locations at different times. In the present studies, the periodicity of the background upon which stimuli were presented was manipulated. Subjects viewed a bistable movement display presented on a background consisting of a variable-frequency grating. The type of movement perceived varied systematically with the spatial frequency of the background, suggesting that more than the target stimuli are processed in the generation of apparent movement. PMID:10214652

Petersik, J T

1999-02-01

12

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

13

Speech intelligibility in background noise with ideal binary time-frequency masking  

E-print Network

Speech intelligibility in background noise with ideal binary time-frequency masking DeLiang Wanga 2009 Ideal binary time-frequency masking is a signal separation technique that retains mixture energy masking on speech intelligibility of both normal-hearing NH and hearing-impaired HI listeners in different

Wang, DeLiang "Leon"

14

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

PubMed

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

2013-01-01

15

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

16

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.

17

Theta Frequency Background Tunes Transmission but Not Summation of Spiking Responses  

PubMed Central

Hippocampal neurons are known to fire as a function of frequency and phase of spontaneous network rhythms, associated with the animal's behaviour. This dependence is believed to give rise to precise rate and temporal codes. However, it is not well understood how these periodic membrane potential fluctuations affect the integration of synaptic inputs. Here we used sinusoidal current injection to the soma of CA1 pyramidal neurons in the rat brain slice to simulate background oscillations in the physiologically relevant theta and gamma frequency range. We used a detailed compartmental model to show that somatic current injection gave comparable results to more physiological synaptically driven theta rhythms incorporating excitatory input in the dendrites, and inhibitory input near the soma. We systematically varied the phase of synaptic inputs with respect to this background, and recorded changes in response and summation properties of CA1 neurons using whole-cell patch recordings. The response of the cell was dependent on both the phase of synaptic inputs and frequency of the background input. The probability of the cell spiking for a given synaptic input was up to 40% greater during the depolarized phases between 30–135 degrees of theta frequency current injection. Summation gain on the other hand, was not affected either by the background frequency or the phasic afferent inputs. This flat summation gain, coupled with the enhanced spiking probability during depolarized phases of the theta cycle, resulted in enhanced transmission of summed inputs during the same phase window of 30–135 degrees. Overall, our study suggests that although oscillations provide windows of opportunity to selectively boost transmission and EPSP size, summation of synaptic inputs remains unaffected during membrane oscillations. PMID:23383242

Parameshwaran, Dhanya; Bhalla, Upinder S.

2013-01-01

18

Efficient Induction of Wheat-Agropyron cristatum 6P Translocation Lines and GISH Detection  

PubMed Central

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 60Co-?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

19

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

20

Complementation studies with mouse translocations  

Microsoft Academic Search

When heterozygotes for reciprocal translocations are intercrossed, the fusion of complementary unbalanced gametes normally gives fully viable, balanced zygotes. If one parent is homozygous for a genetic marker not carried by the other, the frequency of homozygous progeny resulting from such complementation can indicate whether the marker is distal or proximal to the translocation break point and thus fix the

A. G. Searle; C. V. Beechey

1978-01-01

21

Background-free quantum frequency conversion of single photons from a semiconductor quantum dot  

E-print Network

We demonstrate background-free quantum frequency conversion of single photons from an epitaxially-grown InAs quantum dot. Single photons at \\approx 980 nm are combined with a pump laser near 1550 nm inside a periodically-poled lithium niobate (PPLN) waveguide, generating single photons at \\approx 600 nm. The large red-detuning between the pump and signal wavelengths ensures nearly background-free conversion, avoiding processes such as upconversion of anti-Stokes Raman scattered pump photons in the PPLN crystal. Second-order correlation measurements on the single photon stream are performed both before and after conversion, confirming the preservation of photon statistics during the frequency conversion process.

Ates, Serkan; Badolato, Antonio; Srinivasan, Kartik

2012-01-01

22

Position and frequency shifts induced by massive modes of the gravitational wave background in alternative gravity  

E-print Network

Alternative theories of gravity predict the presence of massive scalar, vector, and tensor gravitational wave modes in addition to the standard massless spin~2 graviton of general relativity. The deflection and frequency shift effects on light from distant sources propagating through a stochastic background of gravitational waves, containing such modes, differ from their counterparts in general relativity. Such effects are considered as a possible signature for alternative gravity in attempts to detect deviations from Einstein's gravity by astrophysical means.

S. Bellucci; S. Capozziello; M. De Laurentis; V. Faraoni

2008-12-07

23

Position and frequency shifts induced by massive modes of the gravitational wave background in alternative gravity  

SciTech Connect

Alternative theories of gravity predict the presence of massive scalar, vector, and tensor gravitational wave modes in addition to the standard massless spin 2 graviton of general relativity. The deflection and frequency shift effects on light from distant sources propagating through a stochastic background of gravitational waves, containing such modes, differ from their counterparts in general relativity. Such effects are considered as a possible signature for alternative gravity in attempts to detect deviations from Einstein's gravity by astrophysical means.

Bellucci, Stefano [INFN Laboratori Nazionali di Frascati, Via Enrico Fermi 40, I-00044 Frascati (Italy); Capozziello, Salvatore; De Laurentis, Mariafelicia [Dip. di Scienze Fisiche, Universita di Napoli 'Federico II' and INFN Sez. di Napoli, Compl. Universitario Monte S. Angelo, Ed. N, Via Cinthia, I-80126 Napoli (Italy); Faraoni, Valerio [Physics Department, Bishop's University, Sherbrooke, Quebec, Canada J1M 1Z7 (Canada)

2009-05-15

24

Low-frequency measurement of the spectrum of the cosmic background radiation  

SciTech Connect

Measurements have been made of the cosmic-background-radiation spectrum at five wavelengths (0.33, 0.9, 3, 6.3, and 12 cm) with use of radiometers with wavelength-scaled corrugated-horn antennas having very low sidelobes. A single large-mouth (0.7-m-diam) liquid-helium--cooled absolute reference load was used for all five radiometers. The results of the observations are consistent with previous measurements and represent a significant improvement in accuracy at low frequencies.

Smoot, G.F.; De Amici, G.; Friedman, S.D.; Witebsky, C.; Mandolesi, N.; Partridge, R.B.; Sironi, G.; Danese, L.; De Zotti, G.

1983-09-19

25

Determination of the transmission frequency of chromosome 4S (l) of Aegilops sharonensis in a range of wheat genetic backgrounds.  

PubMed

The transmission of chromosome 4S (l) from Aegilops sharonensis was observed in a range of wheat genetic backgrounds. Chromosome 4S (l) was transmitted at a very high frequency (at least 97.8%) in all crosses. The genetic background appears to only have a small effect on transmission. The frequency of transmission of chromosome 4S (l) was the same in each genetic background through both the male and female gametes. PMID:24221318

King, I P; Miller, T E; Koebner, R M

1991-04-01

26

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

27

Toward a high-temporal-frequency grass canopy thermal IR model for background signatures  

NASA Astrophysics Data System (ADS)

In this paper, we present our first results towards understanding high temporal frequency thermal infrared response from a dense grass canopy. The model is driven by slowly varying, time-averaged meteorological conditions and by high frequency measurements of local and within canopy profiles of relative humidity and wind speed, and compared to high frequency thermal infrared observations. Previously, we have employed three-dimensional ray tracing to compute the intercepted and scattered solar and IR radiation fluxes and for final scene rendering. For the turbulent fluxes, simple resistance models for latent and sensible heat with one-dimensional profiles of relative humidity and wind speed are used. 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 sec to 5 min 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.

2004-08-01

28

Upper bounds on the low-frequency stochastic gravitational wave background from pulsar timing observations: current limits and future prospects  

Microsoft Academic Search

Using a statistically rigorous analysis method, we place limits on the\\u000aexistence of an isotropic stochastic gravitational wave background using pulsar\\u000atiming observations. We consider backgrounds whose characteristic strain\\u000aspectra may be described as a power-law dependence with frequency. Such\\u000abackgrounds include an astrophysical background produced by coalescing\\u000asupermassive black-hole binary systems and cosmological backgrounds due to\\u000arelic gravitational waves

F. A. Jenet; G. B. Hobbs; W. van Straten; R. N. Manchester; M. Bailes; J. P. W. Verbiest; R. T. Edwards; A. W. Hotan; J. M. Sarkissian; S. M. Ord

2006-01-01

29

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

30

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

31

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

32

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

33

Microbiology of bacterial translocation in humans  

Microsoft Academic Search

Background—Gut translocation of bacteria has been shown in both animal and human studies. Evidence from animal studies that links bacterial translocation to the development of postoperative sepsis and multiple organ failure has yet to be confirmed in humans.Aims—To examine the spectrum of bacteria involved in translocation in surgical patients undergoing laparotomy and to determine the relation between nodal migration of

C J O’Boyle; J MacFie; C J Mitchell; D Johnstone; P M Sagar; P C Sedman

1998-01-01

34

Toward a high-temporal-frequency grass canopy thermal IR model for background signatures  

Microsoft Academic Search

In this paper, we present our first results towards understanding high temporal frequency thermal infrared response from a dense grass canopy. The model is driven by slowly varying, time-averaged meteorological conditions and by high frequency measurements of local and within canopy profiles of relative humidity and wind speed, and compared to high frequency thermal infrared observations. Previously, we have employed

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

2004-01-01

35

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

36

The Pontin series of recombinant alien translocations in bread wheat: single translocations integrating combinations of Bdv2, Lr19 and Sr25 disease-resistance genes from Thinopyrum intermedium and Th. ponticum.  

PubMed

Two bread wheat lines each with a translocation on chromosome 7DL from either Thinopyrum intermedium (TC5 and TC14) or Thinopyrum ponticum (T4m), were hybridized in a ph1b mutant background to enhance recombination between the two translocated chromosomal segments. The frequency of recombinants was high in lines derived from the larger and similar-sized translocations (TC5/T4m), but much lower when derived from different-sized translocations (TC14/T4m). Recombinant translocations contained combinations of resistance genes Bdv2, Lr19 and Sr25 conferring resistance to Barley yellow dwarf virus (BYDV), leaf rust and stem rust, respectively. Their genetic composition was identified using bioassays and molecular markers specific for the two progenitor Thinopyrum species. This set of 7DL Th. ponticum/intermedium recombinant translocations was termed the Pontin series. In addition to Thinopyrum markers, the size of the translocation was estimated with the aid of wheat markers mapped on each of the 7DL deletion bins. Bioassays for BYDV, leaf rust and stem rust were performed under greenhouse and field conditions. Once separated from ph1b background, the Pontin recombinant translocations were stable and showed normal inheritance in successive backcrosses. The reported Pontin translocations integrate important resistance genes in a single linkage block which will allow simultaneous selection of disease resistance. Combinations of Bdv2 + Lr19 or Lr19 + Sr25 in both long and short translocations, are available to date. The smaller Pontins, comprising only 20 % of the distal portion of 7DL, will be most attractive to breeders. PMID:23807636

Ayala-Navarrete, L I; Mechanicos, A A; Gibson, J M; Singh, D; Bariana, H S; Fletcher, J; Shorter, S; Larkin, Philip J

2013-10-01

37

Spectroscopic measurement of high-frequency electric fields in the interaction of explosive debris plasma with magnetized background plasma  

NASA Astrophysics Data System (ADS)

The collision-less transfer of momentum and energy from explosive debris plasma to magnetized background plasma is a salient feature of various astrophysical and space environments. While much theoretical and computational work has investigated collision-less coupling mechanisms and relevant parameters, an experimental validation of the results demands the measurement of the complex, collective electric fields associated with debris-background plasma interaction. Emission spectroscopy offers a non-interfering diagnostic of electric fields via the Stark effect. A unique experiment at the University of California, Los Angeles, that combines the Large Plasma Device (LAPD) and the Phoenix laser facility has investigated the marginally super-Alfvénic, quasi-perpendicular expansion of a laser-produced carbon (C) debris plasma through a preformed, magnetized helium (He) background plasma via emission spectroscopy. Spectral profiles of the He II 468.6 nm line measured at the maximum extent of the diamagnetic cavity are observed to intensify, broaden, and develop equally spaced modulations in response to the explosive C debris, indicative of an energetic electron population and strong oscillatory electric fields. The profiles are analyzed via time-dependent Stark effect models corresponding to single-mode and multi-mode monochromatic (single frequency) electric fields, yielding temporally resolved magnitudes and frequencies. The proximity of the measured frequencies to the expected electron plasma frequency suggests the development of the electron beam-plasma instability, and a simple saturation model demonstrates that the measured magnitudes are feasible provided that a sufficiently fast electron population is generated during C debris-He background interaction. Potential sources of the fast electrons, which likely correspond to collision-less coupling mechanisms, are briefly considered.

Bondarenko, A. S.; Schaeffer, D. B.; Everson, E. T.; Clark, S. E.; Constantin, C. G.; Niemann, C.

2014-12-01

38

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

39

Low Frequency measurment of the Spectrum of the Cosmic BackgroundRadiation  

SciTech Connect

We have made measurements of the cosmic background radiation spectrum at 5 wavelengths (0.33, 0.9, 3, 6.3, and 12 cm) using radiometers with wavelength-scaled corrugated horn antennas having very low sidelobes. A single large-mouth (0.7 m diameter) liquid-helium-cooled absolute reference load was used for all five radiometers. The results of the observations are consistent with previous measurements and represent a significant improvement in accuracy.

Smoot, G.F.; De Amici, G.; Friedman, S.D.; Witebsky, C.; Mandolesi, N.; Partridge, R.b.; Sironi, G.; Danese, L.; De Zotti, G.

1983-06-01

40

Translocation Renal Cell Carcinomas in Adults: A Single Institution Experience  

PubMed Central

Translocation renal cell carcinoma is a newly recognized subtype of renal cell carcinoma (RCC) with chromosomal translocations involving TFE3 (Xp11.2) or, less frequently, TFEB (6p21). Xp11 translocation RCC was originally described as a pediatric neoplasm representing 20–40% of pediatric RCCs with a much lower frequency in the adult population. TFEB translocation RCC is very rare, with approximately 10 cases reported in the literature. Here, we describe the clinicopathological features of adult translocation RCC from a single institution. Utilizing tissue microarray (TMA), immunohistochemistry, cytogenetic examination, and FISH, we identified 6 (~5%) cases of TFE3 translocation RCC and 1 (<1%) case of TFEB translocation RCC in 121 consecutive adult renal cell carcinoma cases between 2001 and 2009. Our results suggest that weak TFE3 staining of a significant proportion of RCC cases may due to expression of the full length TFE3 protein rather than the chimeric fusion protein resulting from chromosomal translocation. PMID:22446944

Zhong, Minghao; De Angelo, Patricia; Osborne, Lisa; Mondolfi, Paniz; Geller, Matthew; Yang, Youfeng; Linehan, W. Marston; Merino, Maria J.; Cordon-Cardo, Carlos; Cai, Dongming

2012-01-01

41

Whole blood thallium determination by GFAAS with high-frequency modulation polarization Zeeman effect background correction.  

PubMed

A new technique of blood thallium direct determination based on graphite furnace atomic absorption spectrometry with Zeeman background absorption correction system was designed. The developed technique does not require sample digestion. Sample treatment includes only a fivefold per volume dilution of blood sample with 0.1% (m/v) Triton X-100. L'vov integrated platform was modified with 400 ?g of Rh. Matrix modifier (200 ?g NH(4)NO(3) and 160 ?g Pd(NO(3))(2)) was suggested for coping chloride and blood organic matter interferences. Standard reference material (Clincheck® Plasma Control for trace elements) analysis was used for validation. Additional validation was performed by analyzing spiked blood samples in the whole dynamic range. The dynamic range was 2-50 ?g/L. Precision (RSD) was found <12%. Blood thallium limit of detection was 0.2 ?g/L. PMID:20922499

Solovyev, Nikolay D; Ivanenko, Natalya B; Ivanenko, Anatoly A

2011-10-01

42

Production and identification of wheat - Agropyron cristatum (1.4P) alien translocation lines.  

PubMed

The P genome of Agropyron Gaertn., a wild relative of wheat, contains an abundance of desirable genes that can be utilized as genetic resources to improve wheat. In this study, wheat - Aegilops cylindrica Host gametocidal chromosome 2C addition lines were crossed with wheat - Agropyron cristatum (L.) Gaertn. disomic addition line accession II-21 with alien recombinant chromosome (1.4)P. We successfully induced wheat - A. cristatum alien chromosomal translocations for the first time. The frequency of translocation in the progeny was 3.75%, which was detected by molecular markers and genomic in situ hybridization (GISH). The translocation chromosomes were identified by dual-color GISH /fluorescence in situ hybridization (FISH). The P genomic DNA was used as probe to detect the (1.4)P chromosome fragment, and pHvG39, pAs1, or pSc119.2 repeated sequences were used as probes to identify wheat translocated chromosomes. The results showed that six types of translocations were identified in the three wheat - A. cristatum alien translocation lines, including the whole arm or terminal portion of a (1.4)P chromosome. The (1.4)P chromosome fragments were translocated to wheat chromosomes 1B, 2B, 5B, and 3D. The breakpoints were located at the centromeres of 1B and 2B, the pericentric locations of 5BS, and the terminals of 5BL and 3DS. In addition, we obtained 12 addition-deletion lines that contained alien A. cristatum chromosome (1.4)P in wheat background. All of these wheat - A. cristatum alien translocation lines and addition-deletion lines would be valuable for identifying A. cristatum chromosome (1.4)P-related genes and providing genetic resources and new germplasm accessions for the genetic improvement of wheat. The specific molecular markers of A. cristatum (1.4)P chromosome have been developed and used to track the (1.4)P chromatin. PMID:20555436

Liu, Wei-Hua; Luan, Yang; Wang, Jing-Chang; Wang, Xiao-Guang; Su, Jun-Ji; Zhang, Jin-Peng; Yang, Xin-Ming; Gao, Ai-Nong; Li, Li-Hui

2010-06-01

43

Two-photon interference using background-free quantum frequency conversion of single photons from a semiconductor quantum dot  

E-print Network

We show that quantum frequency conversion (QFC) can overcome the spectral distinguishability common to inhomogeneously broadened solid-state quantum emitters. QFC is implemented by combining single photons from an InAs quantum dot (QD) at 980 nm with a 1550 nm pump laser in a periodically-poled lithium niobate (PPLN) waveguide to generate photons at 600 nm with a signal-to-background ratio exceeding 100:1. Photon correlation and two-photon interference measurements confirm that both the single photon character and wavepacket interference of individual QD states are preserved during frequency conversion. Finally, we convert two spectrally separate QD transitions to the same wavelength in a single PPLN waveguide and show that the resulting field exhibits non-classical two-photon interference.

Ates, Serkan; Gulinatti, Angelo; Rech, Ivan; Rakher, Matthew T; Badolato, Antonio; Srinivasan, Kartik

2012-01-01

44

A Measurement of the Temperature of the Cosmic MicrowaveBackground at a Frequency of 7.5 GHz  

SciTech Connect

We have measured the intensity of the cosmic microwave background (CMB) at a frequency of 7.5 GHz (wavelength 4.0 cm) using a ground-based, total power radiometer calibrated at the horn aperture by an external cryogenic reference target. The radiometer measured the difference in antenna temperature between the reference target and the zenith sky from a dry, high-altitude site. Subtraction of foreground signals (primarily atmospheric and galactic emission) measured with the same instrument leaves the CMB as the residual. The radiometer measured the atmospheric antenna temperature by correlating the signal change with the airmass in the beam during tip scans. The small galactic signal was subtracted based on extrapolation from lower frequencies, and was checked by differential drift scans. The limiting uncertainty in the CMB measurement was the effect of ground radiation in the antenna sidelobes during atmospheric measurements. The thermodynamic temperature of the CMB at 7.5 GHz is 2.59 {+-} 0.07 K (68% confidence level).

Kogut, A.; Bensadoun, M.; De Amici, Giovanni; Levin, S.; Smoot,George F.; Witebsky, C.

1989-06-01

45

Protein Translocation across Membranes  

Microsoft Academic Search

Many newly synthesized proteins must be translocated across a membrane to reach their final destinations. Translocation requires a signal on the protein itself, a loose conformation of the protein, energy, and receptor-like components in the cytosol and on the target membrane.

Keith Verner; Gottfried Schatz

1988-01-01

46

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

2010-06-17

47

Bacterial translocation in dianhydrodulcitol-treated mice.  

PubMed

Escherichia, Proteus, Klebsiella and Streptococcus strains were isolated from mesenteric lymph nodes, spleens and livers of conventional mice treated with dianhydrodulcitol (DAD), indicating that intestinal bacteria had appeared in organs usually containing no bacteria. The frequency of bacterial translocation showed direct relation to the dose of the drug and appeared simultaneously with the spleen atrophy caused by DAD. PMID:3293340

Anderlik, P; Szeri, I; Bános, Z

1988-01-01

48

Translocating Laysan Teal  

USGS Multimedia Gallery

John Klavitter of the US Fish and Wildlife Service, left, and USGS biologist Michelle Reynolds attach transmitters to critically endangered Laysan teal that were translocated from Laysan to Midway Island to expand the species' population and range. ...

49

International study of factors affecting human chromosome translocations  

PubMed Central

Chromosome translocations in peripheral blood lymphocytes of normal, healthy humans increase with age, but the effects of gender, race, and cigarette smoking on background translocation yields have not been examined systematically. Further, the shape of the relationship between age and translocation frequency (TF) has not been definitively determined. We collected existing data from sixteen laboratories in North America, Europe, and Asia on TFs measured in peripheral blood lymphocytes by fluorescence in situ hybridization whole chromosome painting among 1933 individuals. In Poisson regression models, age, ranging from newborns (cord blood) to 85 years, was strongly associated with TF and this relationship showed significant upward curvature at older ages vs. a linear relationship (p <0.001). Ever smokers had significantly higher TFs than non-smokers (rate ratio (RR) = 1.19, 95% confidence interval (CI), 1.09–1.30) and smoking modified the effect of age on TFs with a steeper age-related increase among ever smokers compared to non-smokers (p<0.001). TFs did not differ by gender. Interpreting an independent effect of race was difficult owing to laboratory variation. Our study is three times larger than any pooled effort to date, confirming a suspected curvilinear relationship of TF with age. The significant effect of cigarette smoking has not been observed with previous pooled studies of TF in humans. Our data provide stable estimates of background TF by age, gender, race, and smoking status and suggest an acceleration of chromosome damage above age 60 and among those with a history of smoking cigarettes. PMID:18337160

Sigurdson, Alice J.; Ha, Mina; Hauptmann, Michael; Bhatti, Parveen; Sram, Radim J.; Beskid, Olena; Tawn, E. Janet; Whitehouse, Caroline A.; Lindholm, Carita; Nakano, Mimako; Kodama, Yoshiaki; Nakamura, Nori; Vorobtsova, Irena; Oestreicher, Ursula; Stephan, Günther; Yong, Lee C.; Bauchinger, Manfred; Schmid, Ernst; Chung, Hai Won; Darroudi, Firouz; Roy, Laurence; Voisin, Phillipe; Barquinero, Joan F.; Livingston, Gordon; Blakey, David; Hayata, Isamu; Zhang, Wei; Wang, Chunyan; Bennett, L. Michelle; Littlefield, L. Gayle; Edwards, Alan A.; Kleinerman, Ruth A.; Tucker, James D.

2009-01-01

50

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

51

Molecular analysis of nondisjunction in mice heterozygous for a Robertsonian translocation.  

PubMed Central

A Robertsonian translocation results in a metacentric chromosome produced by the fusion of two acrocentric chromosomes. Rb heterozygous mice frequently generate aneuploid gametes and embryos, providing a good model for studying meiotic nondisjunction. We intercrossed mice heterozygous for a (7.18) Robertsonian translocation and performed molecular genotyping of 1812 embryos from 364 litters with known parental origin, strain, and age. Nondisjunction events were scored and factors influencing the frequency of nondisjunction involving chromosomes 7 and 18 were examined. We concluded the following: 1. The frequency of nondisjunction among 1784 embryos (3568 meioses) was 15.9%. 2. Nondisjunction events were distributed nonrandomly among progeny. This was inferred from the distribution of the frequency of trisomics and uniparental disomics (UPDs) among all litters. 3. There was no evidence to show an effect of maternal or paternal age on the frequency of nondisjunction. 4. Strain background did not play an appreciable role in nondisjunction frequency. 5. The frequency of nondisjunction for chromosome 18 was significantly higher than that for chromosome 7 in males. 6. The frequency of nondisjunction for chromosome 7 was significantly higher in females than in males. These results show that molecular genotyping provides a valuable tool for understanding factors influencing meiotic nondisjunction in mammals. PMID:12136024

Underkoffler, Lara A; Mitchell, Laura E; Localio, A Russell; Marchegiani, Shannon M; Morabito, Justin; Collins, Joelle N; Oakey, Rebecca J

2002-01-01

52

Sensitivity of pulsar timing observations to low-frequency noise and search for the Gravitational Wave Background using Pulsar Timing Array  

NASA Astrophysics Data System (ADS)

Timing of millisecond and binary pulsars gives us an unique possibility to search for the stochastic gravitational wave background (GWB). Low-frequency GWB will cause fluctuations in the Times of Arrival (TOA) of the observed pulsars' pulses. Such fluctuations will manifest themselves as a low-frequency correlated noise in the TOA residuals (timing noise). Analysis of the correlations between TOA residuals in the ensemble of pulsars (further referred as Pulsar Timing Array-PTA) gives us one of the most effective method to search for GWB up to date. In this work we analyze how much the standard timing data processing procedure may influence the efficiency of this method.

Potapov, Vladimir A.

2011-08-01

53

Cytogenetics of human sperm: meiotic segregation in two translocation carriers.  

PubMed Central

Meiotic segregation products were studied in sperm from two men heterozygous for the reciprocal translocations t(8;15)(p22;q21) and t(3;16)(p23;q24). A total of 226 and 201 sperm complements, respectively, were analyzed. In each translocation, 63% of complements were unbalanced, and alternate and adjacent 1 percentages were similar. The 3:1 segregation frequencies produced by the two translocations were 3.5% and 5.0%. Images Fig. 2 Fig. 3 Fig. 4 Fig. 5 PMID:3946422

Brandriff, B; Gordon, L; Ashworth, L K; Littman, V; Watchmaker, G; Carrano, A V

1986-01-01

54

DNA damage defines sites of recurrent chromosomal translocations in B lymphocytes.  

PubMed

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

2012-04-01

55

Protein Translocation Across Biological Membranes  

NSDL National Science Digital Library

This article provides a review of progress made in the study of protein translocation. Subcellular compartments have unique protein compositions, yet protein synthesis only occurs in the cytosol and in mitochondria and chloroplasts. How do proteins get where they need to go? The first steps are targeting to an organelle and efficient translocation across its limiting membrane. Given that most transport systems are exquisitely substrate specific, how are diverse protein sequences recognized for translocation? Are they translocated as linear polypeptide chains or after folding? During translocation, how are diverse amino acyl side chains accommodated? What are the proteins and the lipid environment that catalyze transport and couple it to energy? How is translocation coordinated with protein synthesis and folding, and how are partially translocated transmembrane proteins released into the lipid bilayer? We review here the marked progress of the past 35 years and salient questions for future work.

William Wickner (Dartmouth Medical School; Department of Biological Chemistry)

2005-12-02

56

Clinical significance of translocation.  

PubMed Central

The gastrointestinal tract, besides being the organ responsible for nutrient absorption, is also a metabolic and immunological system, functioning as an effective barrier against endotoxin and bacteria in the intestinal lumen. The passage of viable bacteria from the gastrointestinal tract through the epithelial mucosa is called bacterial translocation. Equally important may be the passage of bacterial endotoxin through the mucosal barrier. This article reviews the evidence that translocation of both endotoxin and bacteria is of clinical significance. It summarises recent published works indicating that translocation of endotoxin in minute amounts is a physiological important phenomenon to boost the reticuloendothelial system (RES), especially the Kupffer cells, in the liver. Breakdown of both the mucosal barrier and the RES capacity results in systemic endotoxaemia. Systemic endotoxaemia results in organ dysfunction, impairs the mucosal barrier, the clotting system, the immune system, and depresses Kupffer cell function. If natural defence mechanisms such as lipopolysaccharide binding protein, high density lipoprotein, in combination with the RES, do not respond properly, dysfunction of the gut barrier results in bacterial translocation. Extensive work on bacterial translocation has been performed in animal models and occurs notably in haemorrhagic shock, thermal injury, protein malnutrition, endotoxaemia, trauma, and intestinal obstruction. It is difficult to extrapolate these results to humans and its clinical significance is not clear. The available data show that the resultant infection remains important in the development of sepsis, especially in the critically ill patient. Uncontrolled infection is, however, neither necessary nor sufficient to account for the development of multiple organ failure. A more plausible sequelae is that bacterial translocation is a later phenomenon of multiple organ failure, and not its initiator. It is hypothesized that multiple organ failure is more probably triggered by the combination of tissue damage and systemic endotoxaemia. Endotoxaemia, as seen in trauma patients especially during the first 24 hours, in combination with tissue elicits a systemic inflammation, called Schwartzmann reaction. Interferon gamma, a T cell produced cytokine, is thought to play a pivotal part in the pathogenesis of this reaction. This reaction might occur only if the endotoxin induced cytokines like tumour necrosis factor and interleukin 1, act on target cells prepared by interferon gamma. After exposure to interferon gamma target cells become more sensitive to stimuli like endotoxin, thus boosting the inflammatory cycle. Clearly, following this line of reasoning, minor tissue damage or retroperitoneal haematoma combined with systemic endotoxaemia could elicit this reaction. The clinically observed failure of multiple organ systems might thus be explained by the interaction of tissue necrosis and high concentrations of endotoxin because of translocation. Future therapeutic strategies could therefore focus more on binding endotoxin in the gut before the triggering event, for example before major surgery. Such a strategy could be combined with the start of early enteral feeding, which has been shown in animal studies to have a beneficial effect on intestinal mucosal barrier function and in traumatized patients to reduce the incidence of septic complications. PMID:8125386

Van Leeuwen, P A; Boermeester, M A; Houdijk, A P; Ferwerda, C C; Cuesta, M A; Meyer, S; Wesdorp, R I

1994-01-01

57

Centrifugally driven microfluidic disc for detection of chromosomal translocations.  

PubMed

Chromosome translocations are a common cause of congenital disorders and cancer. Current detection methods require use of expensive and highly specialized techniques to identify the chromosome regions involved in a translocation. There is a need for rapid yet specific detection for diagnosis and prognosis of patients. In this work we demonstrate a novel, centrifugally-driven microfluidic system for controlled manipulation of oligonucleotides and subsequent detection of chromosomal translocations. The device is fabricated in the form of a disc with capillary burst microvalves employed to control the fluid flow. The microvalves in series are designed to enable fluid movement from the center towards the periphery of the disc to handle DNA sequences representing translocation between chromosome 3 and 9. The translocation detection is performed in two hybridization steps in separate sorting and detection chambers. The burst frequencies of the two capillary burst microvalves are separated by 180 rpm enabling precise control of hybridization in each of the chambers. The DNA probes targeting a translocation are immobilized directly on PMMA by a UV-activated procedure, which is compatible with the disc fabrication method. The device performance was validated by successful specific hybridization of the translocation derivatives in the sorting and detection chambers. PMID:22911443

Brøgger, Anna Line; Kwasny, Dorota; Bosco, Filippo G; Silahtaroglu, Asli; Tümer, Zeynep; Boisen, Anja; Svendsen, Winnie E

2012-11-21

58

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.

59

Two-photon interference using background-free quantum frequency conversion of single photons emitted by an InAs quantum dot.  

PubMed

We show that quantum frequency conversion (QFC) can overcome the spectral distinguishability common to inhomogeneously broadened solid-state quantum emitters. QFC is implemented by combining single photons from an InAs/GaAs quantum dot (QD) at 980 nm with a 1550 nm pump laser in a periodically poled lithium niobate (PPLN) waveguide to generate photons at 600 nm with a signal-to-background ratio exceeding 100:1. Photon correlation and two-photon interference measurements confirm that both the single photon character and wave packet interference of individual QD states are preserved during frequency conversion. Finally, we convert two spectrally separate QD transitions to the same wavelength in a single PPLN waveguide and show that the resulting field exhibits nonclassical two-photon interference. PMID:23083286

Ates, Serkan; Agha, Imad; Gulinatti, Angelo; Rech, Ivan; Rakher, Matthew T; Badolato, Antonio; Srinivasan, Kartik

2012-10-01

60

Detection of the subthalamic nucleus in microelectrographic recordings in Parkinson disease using the high-frequency (> 500 hz) neuronal background. Technical note.  

PubMed

Accurate and fast localization of the subthalamic nucleus (STN) during intraoperative electrophysiological monitoring can improve the outcome of deep brain stimulation surgery. The authors show a simple method of detecting the STN that is based on an analysis of the high-frequency (> 500 Hz) background (HFB) activity of neurons. The HFB reflects multiunit spiking activity close to the recording electrode, and its characteristic profile, which is higher in the STN than in neighboring structures, and facilitates delineation of both the dorsal and ventral STN borders. PMID:17236505

Novak, Peter; Daniluk, Slawomir; Ellias, Samuel A; Nazzaro, Jules M

2007-01-01

61

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

62

Acrylamide: induction of heritable translocations in male mice  

SciTech Connect

Acrylamide (AA), known to induce dominant lethals in male rodents, was studied in the mouse heritable translocation test by using intraperitoneal injections on 5 consecutive days. Matings on days 7-10 following the last injection yielded a high frequency of translocation carriers in the F/sub 1/ male population, which demonstrated that acrylamide is an effective inducer of translocations in postmeiotic germ cells. As an inducer of both dominant lethals and heritable translocations in late spermatids and early spermatozoa, AA is similar to alkylating agents such as ethylmethanesulfonate and ethylene oxide. However, AA's chemical structure, the nature of adducts formed with DNA, and its lack of mutagenicity in bacteria suggest a different mechanism as the basis for AA's germ cell mutagenicity.

Shelby, M.D.; Cain, K.T.; Cornett, C.V.; Generoso, W.M.

1987-01-01

63

Jumping translocations in spontaneous abortions  

Microsoft Academic Search

Chromosome translocations involving one donor chromosome and multiple recipient chromosomes have been referred to as jumping translocations (JTs). Acquired JTs are commonly observed in cancer patients, mainly involving chromosome 1. Constitutional forms of JTs mostly involve the acrocentric chromosomes and their satellites and have been reported in patients with clinical abnormalities. Recognizable phenotypes resulting from these events have included Down,

B. Levy; T. M. Dunn; K. Hirschhorn; N. Kardon

2000-01-01

64

Macromolecular mechanisms of protein translocation.  

PubMed

When macromolecules such as proteins are forced to translocate through a narrow pore, their conformational entropy is reduced, resulting in a free energy barrier. This free energy barrier is additionally modulated by protein-pore interactions. Furthermore, the driving force of the translocation such as the electrochemical potential gradient and electroosmotic flow navigates the transport of the protein through the free energy landscape. Depending on the specifics of the protein-pore system and the driving force, the details of the translocation process and their statistical properties such as the average translocation time can vary significantly. Nevertheless, there are a few fundamental physical concepts that underly the ubiquitous phenomenon of polymer translocation, which are reviewed here. PMID:24370256

Muthukumar, M

2014-03-01

65

Translocation of a heterogeneous polymer  

PubMed Central

We present results on the sequence dependence of translocation kinetics for a partially charged heteropolymer moving through a very thin pore using theoretical tools and Langevin dynamics simulational techniques. The chain is composed of two types of monomers of differing frictional interaction with the pore and charge. We present exact analytical expressions for passage probability, mean first passage time, and mean successful passage times for both reflecting/absorbing and absorbing/absorbing boundary conditions, showing rich and unexpected dependence of translocation behavior on charge fraction, distribution along the chain, and electric field configuration. We find excellent qualitative and good quantitative agreement between theoretical and simulation results. Surprisingly, there emerges a threshold charge fraction of a diblock copolymer beyond which the success rate of translocation is independent of charge fraction. Also, the mean successful translocation time of a diblock copolymer displays non-monotonic behavior with increasing length of the charged block; there is an optimum length of the charged block where the mean translocation rate is the slowest; and there can be a substantial range of higher charge fractions which make the translocation slower than even a minimally charged chain. Additionally, we find for a fixed total charge on the chain, finer distribution along the backbone significantly decreases mean translocation time. PMID:22897308

Mirigian, Stephen; Wang, Yanbo; Muthukumar, Murugappan

2012-01-01

66

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

67

Mechanism of helicase translocation along nucleic acid  

E-print Network

In cells, helicase translocation along nucleic acid is essential for many biological processes. However, so far, the mechanism of this translocation is not fully understood. Recent studies show that helicase might translocate through two processes, active process and passive process, with different translocation rate. In this study, a model including such two processes is presented. In which, each of these two processes consists of two sub-processes, chemical sub-process in which needed translocation factors are attached, and mechanochemical sub-process in which helicase makes a forward translocation step. Helicase can switch stochastically between these two processes with external force dependent rates. By this model, ribosome translocation along message RNA is detailed discussed. We found that, with the increase of external force, the mean translocation rate of ribosome increases from one lower limit to one upper limit, and both of these two limits increase with concentrations of the translocation factors. ...

Zhang, Yunxin

2012-01-01

68

Nonequilibrium Dynamics of Polymer Translocation  

NASA Astrophysics Data System (ADS)

When a flexible chain is pulled or sucked, it can initially respond only locally, and sequential nonequilibrium processes with large conformational distortion follow in line with the propagation of tensile force along the chain backbone. This is a generic dynamical response property of polymers, the understanding of which provides us with a viewpoint to capture an essential aspect of the driven translocation process. In the meeting, I will summarize a basic framework to analyze the nonequilibrium dynamics of driven translocation process alongside of recent progresses. [4pt] References:[0pt] T. Sakaue, Phys. Rev. E, 76, 021803 (2007) ``Nonequilibrium dynamics of polymer translocation and straightening''[0pt] T. Sakaue, Phys. Rev. E, 81, 041808 (2010) ``Sucking genes into pores: Insight into driven translocation''[0pt] T. Saito and T. Sakaue, Eur. Phys. J. E, 34, 145 (2011) ``Dynamical diagram and scaling in polymer driven translocation''[0pt] T. Saito and T. Sakaue, Phys. Rev. E, 85, 061803 (2012) ``Process time distribution of driven polymer transport''

Sakaue, Takahiro

2013-03-01

69

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.

70

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

Microsoft Academic Search

Evaluating translocation outcomes is important for improving wildlife management and conservation actions. Often, when quick decisions need to be made and long-lived animals with slow reproduction rates are translocated, traditional assessment methods such as long-term survival and reproductive success cannot be used for assessing translocation outcomes. Thus, alternative, seldom used, measures such as comparing the behavior and physiology of translocated

Noa Pinter-Wollman; Lynne A. Isbell; Lynette A. Hart

2009-01-01

71

Pleiotropic effects of the twin-arginine translocation system on biofilm formation, colonization, and virulence in Vibrio cholerae  

Microsoft Academic Search

BACKGROUND: The Twin-arginine translocation (Tat) system serves to translocate folded proteins, including periplasmic enzymes that bind redox cofactors in bacteria. The Tat system is also a determinant of virulence in some pathogenic bacteria, related to pleiotropic effects including growth, motility, and the secretion of some virulent factors. The contribution of the Tat pathway to Vibrio cholerae has not been explored.

Lijuan Zhang; Zhaoqin Zhu; Huaiqi Jing; Jingyun Zhang; Yanwen Xiong; Meiying Yan; Shouyi Gao; Long-Fei Wu; Jianguo Xu; Biao Kan

2009-01-01

72

Disease dynamics during wildlife translocations: disruptions to the host population and potential consequences for transmission in desert tortoise contact networks  

USGS Publications Warehouse

Wildlife managers consider animal translocation a means of increasing the viability of a local population. However, augmentation may disrupt existing resident disease dynamics and initiate an outbreak that would effectively offset any advantages the translocation may have achieved. This paper examines fundamental concepts of disease ecology and identifies the conditions that will increase the likelihood of a disease outbreak following translocation. We highlight the importance of susceptibility to infection, population size and population connectivity – a characteristic likely affected by translocation but not often considered in risk assessments – in estimating outbreak risk due to translocation. We then explore these features in a species of conservation concern often translocated in the presence of infectious disease, the Mojave Desert tortoise, and use data from experimental tortoise translocations to detect changes in population connectivity that may influence pathogen transmission. Preliminary analyses comparing contact networks inferred from spatial data at control and translocation plots and infection simulation results through these networks suggest increased outbreak risk following translocation due to dispersal-driven changes in contact frequency and network structure. We outline future research goals to test these concepts and aid managers in designing effective risk assessment and intervention strategies that will improve translocation success.

Aiello, Christina M.; Nussear, Kenneth E.; Walde, Andrew D.; Esque, Todd C.; Emblidge, Patrick G.; Sah, Pratha; Bansal, S.; Hudson, Peter J.

2014-01-01

73

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

74

DNA ligase III promotes alternative nonhomologous end-joining during chromosomal translocation formation.  

PubMed

Nonhomologous end-joining (NHEJ) is the primary DNA repair pathway thought to underlie chromosomal translocations and other genomic rearrangements in somatic cells. The canonical NHEJ pathway, including DNA ligase IV (Lig4), suppresses genomic instability and chromosomal translocations, leading to the notion that a poorly defined, alternative NHEJ (alt-NHEJ) pathway generates these rearrangements. Here, we investigate the DNA ligase requirement of chromosomal translocation formation in mouse cells. Mammals have two other DNA ligases, Lig1 and Lig3, in addition to Lig4. As deletion of Lig3 results in cellular lethality due to its requirement in mitochondria, we used recently developed cell lines deficient in nuclear Lig3 but rescued for mitochondrial DNA ligase activity. Further, zinc finger endonucleases were used to generate DNA breaks at endogenous loci to induce translocations. Unlike with Lig4 deficiency, which causes an increase in translocation frequency, translocations are reduced in frequency in the absence of Lig3. Residual translocations in Lig3-deficient cells do not show a bias toward use of pre-existing microhomology at the breakpoint junctions, unlike either wild-type or Lig4-deficient cells, consistent with the notion that alt-NHEJ is impaired with Lig3 loss. By contrast, Lig1 depletion in otherwise wild-type cells does not reduce translocations or affect microhomology use. However, translocations are further reduced in Lig3-deficient cells upon Lig1 knockdown, suggesting the existence of two alt-NHEJ pathways, one that is biased toward microhomology use and requires Lig3 and a back-up pathway which does not depend on microhomology and utilizes Lig1. PMID:21655080

Simsek, Deniz; Brunet, Erika; Wong, Sunnie Yan-Wai; Katyal, Sachin; Gao, Yankun; McKinnon, Peter J; Lou, Jacqueline; Zhang, Lei; Li, James; Rebar, Edward J; Gregory, Philip D; Holmes, Michael C; Jasin, Maria

2011-06-01

75

Direct and Acclimatory Responses of Dark Respiration and Translocation to Temperature  

PubMed Central

Background and Aims Accounting for the acclimation of respiration of plants to temperature remains a major problem in analysis of carbon balances of plants and ecosystems. Translocation of carbohydrates out of leaves in the dark requires energy from respiration. In this study relationships between the responses of leaf respiration and translocation to temperature are examined. Methods Direct and acclimatory responses to temperature of respiration and translocation in the dark were investigated in mature leaves of soybean and amaranth. In some cases translocation from leaves was prevented by heat-girdling the phloem in the leaf petiole, or photosynthesis during the previous day was altered. Key Results In both species short-term increases in temperature early in the dark period led to exponential increases in rates of respiration. However, respiration rates decreased toward the end of the dark period at higher temperatures. Stopping translocation largely prevented this decrease in respiration, suggesting that the decrease in respiration was due to low availability of substrates. In soybean, translocation also increased with temperature, and both respiration and translocation fully acclimated to temperature. In amaranth, translocation in the dark was independent of temperature, and respiration did not acclimate to temperature. Respiration and translocation rates both decreased with lower photosynthesis during the previous day in the two species. Conclusions Substrate supply limited total night-time respiration in both species at high temperatures and following days with low photosynthesis. This resulted in an apparent acclimation of respiration to high temperatures within one night in both species. However, after long-term exposure to different temperatures there was no evidence that lack of substrates limited respiration in either species. In amaranth, respiration did not limit translocation rates over the temperature range of 20–35 °C. PMID:17483153

Bunce, James A.

2007-01-01

76

Problems with mitigation translocation of herpetofauna.  

PubMed

Mitigation translocation of nuisance animals is a commonly used management practice aimed at resolution of human-animal conflict by removal and release of an individual animal. Long considered a reasonable undertaking, especially by the general public, it is now known that translocated subjects are negatively affected by the practice. Mitigation translocation is typically undertaken with individual adult organisms and has a much lower success rate than the more widely practiced conservation translocation of threatened and endangered species. Nonetheless, the public and many conservation practitioners believe that because population-level conservation translocations have been successful that mitigation translocation can be satisfactorily applied to a wide variety of human-wildlife conflict situations. We reviewed mitigation translocations of reptiles, including our own work with 3 long-lived species (Gila monsters [Heloderma suspectum], Sonoran desert tortoises [Gopherus morafkai], and western diamond-backed rattlesnakes [Crotalus atrox]). Overall, mitigation translocation had a low success rate when judged either by effects on individuals (in all studies reviewed they exhibited increased movement or increased mortality) or by the success of the resolution of the human-animal conflict (translocated individuals often returned to the capture site). Careful planning and identification of knowledge gaps are critical to increasing success rates in mitigation translocations in the face of increasing pressure to find solutions for species threatened by diverse anthropogenic factors, including climate change and exurban and energy development. Problemas con la Mitigación por Traslocación de Herpetofauna. PMID:25040040

Sullivan, Brian K; Nowak, Erika M; Kwiatkowski, Matthew A

2015-02-01

77

Local time variation of high-frequency gravity wave momentum flux and its relationship with background wind derived from LIDAR measurements  

NASA Astrophysics Data System (ADS)

Gravity waves and atmospheric tides have strong interactions in the mesopause region and is a major contributor to the large variabilities in this region. How these two large perturbations interact with each other is not well understood. Observational studies of their relationships are needed to help clarify some contradictory results from modeling studies. Due to large differences in temporal and spatial scales between gravity waves and tides, they are not easily observed simultaneously and consistently with extended periods of time. In this work, we use four-hundred hours of Na LIDAR observation at Starfire Optical Range (SOR, 35.0 N, 106.5 W), New Mexico to derive the local time variation of gravity wave momentum flux and corresponding background wind. Their relationship is then examined in detail. The effects of gravity waves on the background wind at the tidal time scale are deduced. These results are explained through gravity wave propagation in a varying background atmosphere.

Agner, R. M.; Liu, A. Z.

2013-12-01

78

A De Novo Case of Floating Chromosomal Polymorphisms by Translocation in Quasipaa boulengeri (Anura, Dicroglossidae)  

PubMed Central

Very few natural polymorphisms involving interchromosomal reciprocal translocations are known in amphibians even in vertebrates. In this study, thirty three populations, including 471 individuals of the spiny frog Quasipaa boulengeri, were karyotypically examined using Giemsa stain or FISH. Five different karyomorphs were observed. The observed heteromorphism was autosomal but not sex-related, as the same heteromorphic chromosomes were found both in males and females. Our results indicated that the variant karyotypes resulted from a mutual interchange occurring between chromosomes 1 and 6. The occurrence of a nearly whole-arm translocation between chromosome no. 1 and no. 6 gave rise to a high frequency of alternate segregation and probably resulted in the maintenance of the translocation polymorphisms in a few populations. The translocation polymorphism is explained by different frequencies of segregation modes of the translocation heterozygote during meiosis. Theoretically, nine karyomorphs should be investigated, however, four expected karyotypes were not found. The absent karyomorphs may result from recessive lethal mutations, position effects, duplications and deficiencies. The phylogenetic inference proved that all populations of Q. boulengeri grouped into a monophyletic clade. The mutual translocation likely evolved just once in this species and the dispersal of the one karyomorph (type IV) can explain the chromosomal variations among populations. PMID:23056254

Qing, Liyan; Xia, Yun; Zheng, Yuchi; Zeng, Xiaomao

2012-01-01

79

Insulin Phosphorylates Tyrosine Residue 464 of Tub and Translocates Tubby into the Nucleus in HIRcB Cells  

PubMed Central

Background The tubby protein has a motif that might be relevant for its action in the insulin signaling pathway. Previous studies have indicated that tubby undergoes phosphorylation on tyrosine residues in response to several stimuli and is known to localize in the nucleus as well as in the plasma membrane. However, the relationship between phosphorylation and nuclear translocation is not well understood. Here, we report that insulin directly phosphorylates tubby, which translocates into the nucleus. Methods The effects of insulin on Tubby were performed with Western blot. The immunoprecipitation and confocal microscopy were performed to prove phosphorylation and nuclear translocation. Results Mutation study reveals that tyrosine residue 464 of tubby gene (Tub) is a phosphorylation site activated by insulin. In addition, major portions of tubby protein in the plasma membrane are translocated into the nucleus after insulin treatment. Tyrosine kinase inhibitor pretreatment blocked insulin-induced tubby translocation, suggesting that phosphorylation is important for nuclear translocation. Moreover, mutant tyrosine residue 464 did not translocate into the nucleus in respond to insulin. These findings demonstrate that insulin phosphorylates tyrosine residue 464 of Tub, and this event is important for insulin-induced tubby nuclear translocation. Conclusion Insulin phosphorylates tyrosine residue 464 of Tub and translocates tubby into the nuclei of HIRcB cells. PMID:25031889

Kim, Jin Wook; Kim, Hyeon Soo; Kim, Sang Dae

2014-01-01

80

Haloarchaeal Protein Translocation via the Twin Arginine Translocation Pathway  

SciTech Connect

Protein transport across hydrophobic membranes that partition cellular compartments is essential in all cells. The twin arginine translocation (Tat) pathway transports proteins across the prokaryotic cytoplasmic membranes. Distinct from the universally conserved Sec pathway, which secretes unfolded proteins, the Tat machinery is unique in that it secretes proteins in a folded conformation, making it an attractive pathway for the transport and secretion of heterologously expressed proteins that are Sec-incompatible. During the past 7 years, the DOE-supported project has focused on the characterization of the diversity of bacterial and archaeal Tat substrates as well as on the characterization of the Tat pathway of a model archaeon, Haloferax volcanii, a member of the haloarchaea. We have demonstrated that H. volcanii uses this pathway to transport most of its secretome.

Pohlschroder Mechthild

2009-02-03

81

Original article Grooming behaviors and the translocation  

E-print Network

-grooming resulted in the translocation of synthetic queen mandibular gland phero- mone from the mouthparts and head for pheromone translocation. Little if any, phero- mone moved passively on the cuticle. This study provides a pseudo- queen lure, despite the fact that this phero- mone is gathered primarly with the mouth- parts

Paris-Sud XI, Université de

82

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

PubMed Central

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 in the San Andres Mountains in New Mexico, USA. Results Although the free-ranging source population had significantly higher multi-locus heterozygosity at 30 microsatellite loci than the captive bred animals, neither source population nor genetic background significantly influenced survival or cause of death. The presence of antibodies to a respiratory virus known to cause pneumonia was associated with increased survival, but there was no correlation between genetic heterozygosity and the presence of antibodies to this virus. Conclusions Although genetic theory predicts otherwise, increased heterozygosity was not associated with increased fitness (survival) among translocated animals. While heterosis or genetic rescue effects may occur in F1 and later generations as the two source populations interbreed, we conclude that previous pathogen exposure was a more important marker than genetic heterozygosity for predicting survival of translocated animals. Every wildlife translocation is an experiment, and whenever possible, translocations should be designed and evaluated to test hypotheses that will further improve our understanding of how pathogen exposure and genetic variability influence fitness. PMID:21284886

2011-01-01

83

Electrically facilitated translocation of protein through solid nanopore  

NASA Astrophysics Data System (ADS)

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.

Wu, Lingzhi; Liu, Hang; Zhao, Wenyuan; Wang, Lei; Hou, Chuanrong; Liu, Quanjun; Lu, Zuhong

2014-03-01

84

Reciprocal translocations in myelodysplastic syndromes and chronic myelomonocytic leukemias: review of 5,654 patients with an evaluable karyotype.  

PubMed

The infrequency of translocations in myelodysplastic syndromes (MDS) and chronic myelomonocytic leukemias (CMML) makes their identification and reporting interesting for the recognition of the recurrent ones and the genes involved in these neoplasias. The aims of this study were to identify new translocations associated with MDS and CMML and to establish their frequency in a cohort of 8,016 patients from the Spanish Group of MDS database. The karyotype was evaluable in 5,654 (70%) patients. Among those, 2,014 (36%) had chromosomal abnormalities, including 213 (10%) translocations identified in 195 patients. The translocations were balanced in 183 (86%) cases and unbalanced in 30 (14%) cases. All chromosomes were found to be involved in translocations, with the single exception of the Y chromosome. The chromosomes most frequently involved were in decreasing frequency: 3, 1, 7, 2, 11, 5, 12, 6, and 17. Translocations were found in karyotypes as the unique chromosomal abnormality (33%), associated with another chromosomal abnormality (11%), as a part of a complex karyotype (17%), and as a part of a monosomal karyotype (38%). There were 155 translocations not previously described in MDS or CMML and nine of them appeared to be recurrent. PMID:23686965

Costa, Dolors; Muñoz, Concha; Carrió, Ana; Nomdedeu, Meritxell; Calvo, Xavier; Solé, Francesc; Luño, Elisa; Cervera, José; Vallespí, Teresa; Berneaga, Daniela; Gómez, Cándida; Arias, Amparo; Such, Esperanza; Sanz, Guillermo; Grau, Javier; Insunza, Andrés; Calasanz, María J; Ardañaz, María T; Hernández, Jesús M; Azaceta, Gemma; Álvarez, Sara; Sánchez, Joaquín; Martín, María L; Bargay, Joan; Gómez, Valle; Cervero, Carlos Javier; Allegue, María J; Collado, Rosa; Campo, Elias; Nomdedeu, Benet

2013-08-01

85

Dynamics of RNA Translocation through a Nanopore  

E-print Network

We present a simplified model of the dynamics of translocation of RNA through a nanopore which only allows the passage of unbound nucleotides. In particular, we consider the disorder averaged translocation dynamics of random, two-component, single-stranded nucleotides, by reducing the dynamics to the motion of a random walker on a one-dimensional free energy landscape of translocation. These translocation landscapes are calculated from the folds of the RNA sequences and the voltage bias applied across the nanopore. We compute these landscapes for 1500 randomly drawn two-letter sequences of length 4000. Simulations of the dynamics on these landscapes display anomalous characteristics, similar to random forcing energy landscapes, where the translocation process proceeds slower than linearly in time for sufficiently small voltage biases across the nanopore, but moves linearly in time at large voltage biases. We argue that our simplified model provides an upper bound to the more realistic translocation dynamics, and thus we expect that all RNA translocation models will exhibit anomalous regimes.

J. B. Lucks; Y. Kafri

2007-03-12

86

Counting and dynamic studies of the small unilamellar phospholipid vesicle translocation with single conical glass nanopores.  

PubMed

Phospholipid vesicles are ubiquitous cellular organelles that perform vital functions including materials transport and information transmission and have found promising biomedical applications. Although the transmembrane translocation (via nanopores) of phospholipid vesicles, especially small unilamellar phospholipid vesicles (SUVs), is recognized to be very important for these processes and applications, the details and dynamics remain not very clear. Herein, we use single conical glass nanopores as a model platform to systematically investigate the translocation dynamics of SUVs (?50-60 nm in diameter) through small nanopores with orifice diameters ranging from ?14 to 72 nm. Dynamic translocation of individual SUVs one by one through the nanopores was clearly observed and was analyzed by the occurrence of periodic oscillation in ionic current blockage signal under a negatively applied voltage. Translocation behaviors of the SUVs, in terms of magnitude and duration of ionic current blockage signal, varied and can be modulated by changing nanopore size, solution pH, vesicle concentration, applied voltage, and inner surface charge properties of the nanopores. The translocation rate of the SUVs through an ?72 nm nanopore is typically on a time scale of a few seconds (per SUV translocation event) and found nonlinearly proportional to the concentration of the SUVs. Moreover, the electrophoretic force has been verified as a main force to drive the SUVs through the nanopore since there is a nearly linear relationship between the current blockage frequency of SUVs translocation and the applied bias potentials ranging from -0.6 to -1 V. The findings provide fundamental insights into the translocation and interactions of SUVs with nanopores, and the reported nanopore platform may find potential useful bioapplications in single-cell and single-vesicle studies. PMID:25489990

Chen, Lizhen; He, Haili; Jin, Yongdong

2015-01-01

87

The influence of hydrogen peroxide and histamine on lung permeability and translocation of iridium nanoparticles in the isolated perfused rat lung  

Microsoft Academic Search

BACKGROUND: Translocation of ultrafine particles (UFP) into the blood that returns from the lungs to the heart has been forwarded as a mechanism for particle-induced cardiovascular effects. The objective of this study was to evaluate the role of the endothelial barrier in the translocation of inhaled UFP from the lung into circulation. METHODS: The isolated perfused rat lung (IPRL) was

James J Meiring; Paul JA Borm; Karim Bagate; Manuela Semmler; Jürgen Seitz; Shinji Takenaka; Wolfgang G Kreyling

2005-01-01

88

DNA translocation through a periodically patterned nanoprobe  

NASA Astrophysics Data System (ADS)

The Al Nano apertures surrounded by periodic patterns on the pyramidal structures were fabricated. The nanometric size aperture with ~ 100 nm diameter surrounded by equidistant elliptic groove patterns presented greater transmission than the aperture with circular groove patterns. The translocation of ?-DNA through these fabricated nanostructures was tested using electrically biased techniques. We observed the strong fluorescent optical signal from the translocated DNA through the nanoprobe with a charge coupled device camera. The optical force driven DNA translocation though a nanoprobe surrounded with elliptically patterned grooves is under investigation.

Choi, Seong Soo; Park, Myoung Jin; Park, Nam kyou; Park, Seung Min; Lee, Luke

2013-05-01

89

Double Translocation: An Interesting Family History  

PubMed Central

Double balanced translocations are particularly rare and the risk of a fetus with an unbalanced chromosomal anomaly is greater than for single translocation carriers. In this present case, we describe an interesting family history which included three generations. A couple, married for 4 years, was referred to the genetic clinic due to infertility and family chromosome anomalies. A GTG-band chromosome analysis indicated that the male partner’s karyotype was 45,XY, t(3;18)(q11;ptel)t(13;14)(q10;q10). The same double balanced translocation was found in two others family members. PMID:24265590

Uysal, A; Uluda?, A; S?lan, F; Erçelen, N; Zafer, C; Özdemir, Ö

90

Cell Host & Microbe Translocation of Sickle Cell Erythrocyte MicroRNAs  

E-print Network

a variant hemoglobin allele (HbS), which causes sickle cell disease and resists infection by the malaria, including sickle cell diseases, occur at relatively high frequencies (Livincstone, 1971; Nagel and RothCell Host & Microbe Article Translocation of Sickle Cell Erythrocyte MicroRNAs into Plasmodium

Nicchitta, Chris

91

Trigenomic chromosomes by recombination of Thinopyrum intermedium and Th. ponticum translocations in wheat.  

PubMed

Rusts and barley yellow dwarf virus (BYDV) are among the main diseases affecting wheat production world wide for which wild relatives have been the source of a number of translocations carrying resistance genes. Nevertheless, along with desirable traits, alien translocations often carry deleterious genes. We have generated recombinants in a bread wheat background between two alien translocations: TC5, ex-Thinopyrum (Th) intermedium, carrying BYDV resistance gene Bdv2; and T4m, ex-Th. ponticum, carrying rust resistance genes Lr19 and Sr25. Because both these translocations are on the wheat chromosome arm 7DL, homoeologous recombination was attempted in the double hemizygote (TC5/T4m) in a background homozygous for the ph1b mutation. The identification of recombinants was facilitated by the use of newly developed molecular markers for each of the alien genomes represented in the two translocations and by studying derived F(2), F(3) and doubled haploid populations. The occurrence of recombination was confirmed with molecular markers and bioassays on families of testcrosses between putative recombinants and bread wheat, and in F(2) populations derived from the testcrosses. As a consequence it has been possible to derive a genetic map of markers and resistance genes on these previously fixed alien linkage blocks. We have obtained fertile progeny carrying new tri-genomic recombinant chromosomes. Furthermore we have demonstrated that some of the recombinants carried resistance genes Lr19 and Bdv2 yet lacked the self-elimination trait associated with shortened T4 segments. We have also shown that the recombinant translocations are fixed and stable once removed from the influence of the ph1b. The molecular markers developed in this study will facilitate selection of individuals carrying recombinant Th. intermedium-Th. ponticum translocations (Pontin series) in breeding programs. PMID:17906848

Ayala-Navarrete, L; Bariana, H S; Singh, R P; Gibson, J M; Mechanicos, A A; Larkin, P J

2007-12-01

92

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

93

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

Microsoft Academic Search

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

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

2006-01-01

94

Background Notes  

NSDL National Science Digital Library

Country Background Notes, distributed on the DOSBACK list, are updated periodically and include information on US bilateral relations with foreign countries and on their governments, political conditions, and foreign relations. You can expect the DOSBACK list to generate about 3-4 email messages per month. Via DOSBACK you will receive the full-text version of newly released Background Notes. Archives of these two lists are also available at the Department of State Foreign Affairs Network (DOSFAN) gopher at the University of Illinois-Chicago.

95

Ratcheting up protein translocation with anthrax toxin  

PubMed Central

Energy-consuming nanomachines catalyze the directed movement of biopolymers in the cell. They are found both dissolved in the aqueous cytosol as well as embedded in lipid bilayers. Inquiries into the molecular mechanism of nanomachine-catalyzed biopolymer transport have revealed that these machines are equipped with molecular parts, including adjustable clamps, levers, and adaptors, which interact favorably with substrate polypeptides. Biological nanomachines that catalyze protein transport, known as translocases, often require that their substrate proteins unfold before translocation. An unstructured protein chain is likely entropically challenging to bind, push, or pull in a directional manner, especially in a way that produces an unfolding force. A number of ingenious solutions to this problem are now evident in the anthrax toxin system, a model used to study protein translocation. Here we highlight molecular ratchets and current research on anthrax toxin translocation. A picture is emerging of proton-gradient-driven anthrax toxin translocation, and its associated ratchet mechanism likely applies broadly to other systems. We suggest a cyclical thermodynamic order-to-disorder mechanism (akin to a heat-engine cycle) is central to underlying protein translocation: peptide substrates nonspecifically bind to molecular clamps, which possess adjustable affinities; polypeptide substrates compress into helical structures; these clamps undergo proton-gated switching; and the substrate subsequently expands regaining its unfolded state conformational entropy upon translocation. PMID:22374876

Feld, Geoffrey K; Brown, Michael J; Krantz, Bryan A

2012-01-01

96

Background & Publications  

E-print Network

Home Background & Projects Calendar Publications Staff Directory Station Videos Links Search Northern Michigan FruitNet 2008 Weekly Update NW Michigan Horticultural Research Station Nikki Rothwell maggot from growers. European red mites and two-spotted spider mites have reached threshold levels

97

Molecular studies of free and translocation trisomy  

SciTech Connect

Twenty cases of trisomy 13 were examined with molecular markers to determine the origin of the extra chromosome. Six cases had translocation trisomy: two de novo rob(13q;14q), one paternally derived rob(13q;14q), two de novo t(13q;13q), and one mosaic de novo t(13q;14q), one paternally derived rob(13q;14q), two de novo t(13q;13q), and one mosaic de novo t(13q;13q)r(13). Eighteen of nineteen informative patients were consistant with a maternal origin of the extra chromosome. Lack of a third allele at any locus in any of the three t(13q;13q) cases indicate that all were most likely isochromosomes of post-meiotic origin. In addition, two free trisomy cases were compatible with a somatic origin. Two mosaic free trisomy-13 cases, however, were both consistent with a maternal meiotic origin. The patient with a paternal inheritance of the translocation chromosome was purely coincidental. Since there is not a significantly increased risk for unbalanced offspring of a t(13;14) carrier and most trisomies are maternal in origin, this result should not be surprising; however it illustrates that one cannot infer the origin of translocation trisomy based on parental origin of the translocation. One balanced (non-trisomic) case with a non-mosaic 45,-13,-13,+t(13;13) karyotype was also investigated and was determined to be a somatic Robertsonian translocation between the maternal and paternal homologs, as has been found for all homologous Robertsonian translocations so far investigated. It is therefore also incorrect to assume in de novo translocation cases that the two involved chromosomes are even from the same parent. We cannot therefore infer anything about the origin of the chromosomes 13 and 14 involved in the two cases with de novo t(13q;14q) plus a maternally derived trisomy 13.

Robinson, W.P.; Bernasconi, F.; Lefort, G. [Univ. of Zuerich (Switzerland)] [and others

1994-09-01

98

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

99

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

100

A recurrent translocation is mediated by homologous recombination between HERV-H elements  

PubMed Central

Background Chromosome rearrangements are caused by many mutational mechanisms; of these, recurrent rearrangements can be particularly informative for teasing apart DNA sequence-specific factors. Some recurrent translocations are mediated by homologous recombination between large blocks of segmental duplications on different chromosomes. Here we describe a recurrent unbalanced translocation casued by recombination between shorter homologous regions on chromosomes 4 and 18 in two unrelated children with intellectual disability. Results Array CGH resolved the breakpoints of the 6.97-Megabase (Mb) loss of 18q and the 7.30-Mb gain of 4q. Sequencing across the translocation breakpoints revealed that both translocations occurred between 92%-identical human endogenous retrovirus (HERV) elements in the same orientation on chromosomes 4 and 18. In addition, we find sequence variation in the chromosome 4 HERV that makes one allele more like the chromosome 18 HERV. Conclusions Homologous recombination between HERVs on the same chromosome is known to cause chromosome deletions, but this is the first report of interchromosomal HERV-HERV recombination leading to a translocation. It is possible that normal sequence variation in substrates of non-allelic homologous recombination (NAHR) affects the alignment of recombining segments and influences the propensity to chromosome rearrangement. PMID:22260357

2012-01-01

101

A girl with the Prader-Willi Syndrome and Robertsonian translocation 45,XX,t(14;15)(p11;q11) which was present in three normal family members  

Microsoft Academic Search

A 21-year-old girl with classical Prader-Willi Syndrome was found to have a 14;15 Robertsonian translocation—45,XX,t(14;15)(p11;q11). This type of Robertsonian translocation was not found in any patient from 8 surveys covering 6144 patients with mental retardation. Chromosome 15 has been involved in translocations in patients with the Prader-Willi Syndrome with greater than expected frequency. This is the first report of a

Arabella Smith; Michael Noel

1980-01-01

102

Cosmic Microwave Background Theory  

Microsoft Academic Search

A long-standing goal of theorists has been to constrain cosmological parameters that define the structure formation theory from cosmic microwave background (CMB) anisotropy experiments and large-scale structure (LSS) observations. The status and future promise of this enterprise is described. Current band-powers in ell -space are consistent with a Delta T flat in frequency and broadly follow inflation-based expectations. That the

J. Richard Bond

1998-01-01

103

[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

104

Translocation of Rodlike Polymers through Membrane Channels  

PubMed Central

A theory of channel-facilitated transport of long rodlike macromolecules through thin membranes under the influence of a driving force of arbitrary strength is developed. Analytic expressions are derived for the translocation probability and the Laplace transform of the probability density of time that a macromolecule spends in the channel. We also derive expressions for the (conditional) probability densities of time spent in the channel by translocating and nontranslocating (returning back) macromolecules. These results are used to study how the distribution of the macromolecule lifetime in the channel depends on a polymer chain length and the driving force. It is shown that depending on the values of the parameters, the lifetime probability density may have one or two peaks. Our theory is a generalization of the theory developed by Lubensky and Nelson, who were inspired by recent experiments on driven translocation of single-stranded RNA and DNA molecules through single channels in narrow membranes. PMID:12547763

Berezhkovskii, A. M.; Gopich, I. V.

2003-01-01

105

Protein Translocation across the Rough Endoplasmic Reticulum  

PubMed Central

The rough endoplasmic reticulum is a major site of protein biosynthesis in all eukaryotic cells, serving as the entry point for the secretory pathway and as the initial integration site for the majority of cellular integral membrane proteins. The core components of the protein translocation machinery have been identified, and high-resolution structures of the targeting components and the transport channel have been obtained. Research in this area is now focused on obtaining a better understanding of the molecular mechanism of protein translocation and membrane protein integration. PMID:23251026

Mandon, Elisabet C.; Trueman, Steven F.; Gilmore, Reid

2013-01-01

106

Macromolecular Micromovements: How RNA Polymerase Translocates  

PubMed Central

Multisubunit DNA-dependent RNA polymerases synthesize RNA molecules thousands of nucleotides long. The reiterative reaction of nucleotide condensation occurs at rates of tens of nucleotides per second, invariably linked to the translocation of the enzyme along the DNA template, or threading of the DNA and the nascent RNA molecule through the enzyme. Reiteration of the nucleotide addition/translocation cycle without dissociation from the DNA and RNA requires both iso- and metamorphic conformational flexibility of a magnitude substantial enough to accommodate the requisite molecular motions. Here we review some of the more recently acquired insights into the structural flexibility and morphic fluctuations of RNA polymerases and their mechanistic implications. PMID:19889534

Svetlov, Vladimir; Nudler, Evgeny

2013-01-01

107

Cytokine-induced nuclear translocation of signaling proteins and their analysis using the inducible translocation trap system  

PubMed Central

Binding of cytokines to their specific receptors induces activation of signal transduction pathways, many of which involve nuclear translocation of signaling proteins. In this review, an overview of cytokine-induced nuclear translocation of signaling proteins is provided. In addition, inducible translocation trap (ITT), a novel reporter-based system to detect nuclear translocation, and its application for identification of nuclear translocating proteins are elaborated. Finally, analysis of “nuclear translocatome”, the entire set of proteins that translocate into or out of the nucleus in response to extracellular stimuli, by ITT is discussed. PMID:18203617

Fleur, Shella Saint; Fujii, Hodaka

2008-01-01

108

H2AX prevents DNA breaks from progressing to chromosome breaks and translocations.  

PubMed

Histone H2AX promotes DNA double-strand break (DSB) repair and immunoglobulin heavy chain (IgH) class switch recombination (CSR) in B-lymphocytes. CSR requires activation-induced cytidine deaminase (AID) and involves joining of DSB intermediates by end joining. We find that AID-dependent IgH locus chromosome breaks occur at high frequency in primary H2AX-deficient B cells activated for CSR and that a substantial proportion of these breaks participate in chromosomal translocations. Moreover, activated B cells deficient for ATM, 53BP1, or MDC1, which interact with H2AX during the DSB response, show similarly increased IgH locus breaks and translocations. Thus, our findings implicate a general role for these factors in promoting end joining and thereby preventing DSBs from progressing into chromosomal breaks and translocations. As cellular p53 status does not markedly influence the frequency of such events, our results also have implications for how p53 and the DSB response machinery cooperate to suppress generation of lymphomas with oncogenic translocations. PMID:16427010

Franco, Sonia; Gostissa, Monica; Zha, Shan; Lombard, David B; Murphy, Michael M; Zarrin, Ali A; Yan, Catherine; Tepsuporn, Suprawee; Morales, Julio C; Adams, Melissa M; Lou, Zhenkun; Bassing, Craig H; Manis, John P; Chen, Junjie; Carpenter, Phillip B; Alt, Frederick W

2006-01-20

109

Single Stranded DNA Translocation Through a Fluctuating Nanopore  

E-print Network

We investigate the translocation of a single stranded DNA (ssDNA) through a pore, which fluctuates between two conformations, by using coupled master equations (ME). The probability density function (PDF) of the first passage times (FPT) of the translocation process is calculated, displaying a triple, double or mono-peaked behavior, depending on the system parameters. An analytical expression for the mean first passage time (MFPT) of the translocation process is derived, and provides an extensive characterization of the translocation process.

O. Flomenbom; J. Klafter

2005-01-11

110

Twelve Unrelated Translocation Mongols: Cytogenetic, Genetic and Parental Age Data  

Microsoft Academic Search

Cytogenetic analyses of 6 unrelated 13–15\\/21 translocation mongols, 6 unrelated 21–22\\/21 translocation mongols and almost all of their parents and sibs have been carried out. Parents carrying the translocation chromosome were found in 2 of the 13–15\\/21 families, but not in any of the 21–22\\/21 families (one father could not be tested). Mean parental ages for either type of translocation

F. R. Sergovich; H. C. Soltan; D. H. Carr

1964-01-01

111

Uptake and Translocation of Copper in Brassicaceae  

Microsoft Academic Search

Ten cvs. of four Brassicaceae species were tested to evaluate their copper (Cu) uptake and translocation. Germination and root length tests indicated that Brassica juncea cv. Aurea and Raphanus sativus cvs. Rimbo and Saxa were the species with the highest germinability and longest roots at Cu concentrations ranging from 25 up to 200 µM. Raphanus sativus cv. Rimbo grown in hydroponic

Mike F. Quartacci; Elena Cosi; Sandra Meneguzzo; Cristina Sgherri

2003-01-01

112

Familial cryptic translocation in Angelman syndrome  

SciTech Connect

The majority of patients with Angelman syndrome have been shown to have a cytogenetic or molecular deletion on the maternally derived chromosome 15. We report on a case of Angelman syndrome in which this deletion occurs as an unbalanced cryptic translocation involving chromosomes 14 and 15. The proband was diagnosed clinically as having Angelman syndrome. Multiple cytogenetic studies were done without detecting any deletion. When DNA probes (Oncor) specific for the Prader Willi/Angelman locus became available, the patient was restudied and found to be deleted for {open_quotes}region A{close_quotes} (D15S11) but not for {open_quotes}region B{close_quotes} (GABRB3). No other abnormality was detected. The proband`s mother was then studied. The chromosome 15 marker probe and D15S11 were detected on different chromosomes. Using alpha-satellite probes, a cryptic 14;15 translocation was uncovered. This balanced translocation was also found to be carried by the sister of the proband. This case, along with a case presented at the 1993 ASHG meeting, illustrates the need for using acrocentric probes when studying Angelman syndrome patients. The proband was studied using additional probes specific for this region and found to be deleted for SNRPN but not for D15S10. The breakpoint of the translocation in this patient delineates the smallest deletion of the Angelman syndrome region reported to date and therefore may represent the specific gene involved.

Weyerts, L.K.; Wiley, J.E.; Loud, K.M. [ECU School of Medicine, Greenville, NC (United States)] [and others

1994-09-01

113

Coupled dynamics of RNA folding and nanopore translocation  

E-print Network

The translocation of structured RNA or DNA molecules through narrow pores necessitates the opening of all base pairs. Here, we study the interplay between the dynamics of translocation and base-pairing theoretically, using kinetic Monte Carlo simulations and analytical methods. We find that the transient formation of basepairs that do not occur in the ground state can significantly speed up translocation.

Ralf Bundschuh; Ulrich Gerland

2005-08-01

114

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 of translocation of double-strand DNA through a siliconoxide nanopore. Long DNA molecules with different lengths of oligonucleotides.2-6 Recently, various groups have started to use solid-state nanopores for DNA translocation

Dekker, Cees

115

Anomalous scaling in nanopore translocation of structured heteropolymers  

E-print Network

Anomalous scaling in nanopore translocation of structured heteropolymers Malcolm McCauley1 , Robert. Translocation through nanopores has emerged as a new experimental technique to probe physical properties sequences to translocate through an idealized nanopore. It is believed that with respect to secondary

Bundschuh, Ralf

116

Slowing DNA Translocation in a Solid-State Nanopore  

E-print Network

Slowing DNA Translocation in a Solid-State Nanopore Daniel Fologea, James Uplinger, Brian Thomas ABSTRACT 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

Li, Jiali

117

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

PubMed Central

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. Such a system includes specific targeting signals of the proteins needed for the function of the plastid and membrane-bound machineries performing the transfer of these proteins across the envelope membranes. At present, most information on protein translocation is obtained by the analysis of land plants. However, the analysis of protein import into the primitive plastids of glaucocystophyte algae, revealed distinct features placing this system as a tool to understand the evolutionary development of translocation systems. Here, bacterial outer membrane proteins of the Omp85 family have recently been discussed as evolutionary seeds for the development of translocation systems. Results To further explore the initial mode of protein translocation, the observed phenylalanine dependence for protein translocation into glaucophyte plastids was pursued in detail. We document that indeed the phenylalanine has an impact on both, lipid binding and binding to proteoliposomes hosting an Omp85 homologue. Comparison to established import experiments, however, unveiled a major importance of the phenylalanine for recognition by Omp85. This finding is placed into the context of the evolutionary development of the plastid translocon. Conclusion The phenylalanine in the N-terminal domain signs as a prerequisite for protein translocation across the outer membrane assisted by a "primitive" translocon. This amino acid appears to be optimized for specifically targeting the Omp85 protein without enforcing aggregation on the membrane surface. The phenylalanine has subsequently been lost in the transit sequence, but can be found at the C-terminal position of the translocating pore. Thereby, the current hypothesis of Omp85 being the prokaryotic contribution to the ancestral Toc translocon can be supported. PMID:18045484

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

2007-01-01

118

A reciprocal translocation induced in an oocyte and affecting fertility in male mice  

Microsoft Academic Search

The reciprocal translocation T(5;12)31H, induced by irradiation of oocytes, causes sterility in most heterozygous male carriers, a tenfold reduction in mean sperm count, and a high frequency of abnormal sperm. Chromosome breakpoints are in bands 5B and 12F1, leading to a long (125) and a short (512) marker chromosome. Ninety five percent of germ cells showed chain quadrivalents or trivalents

C. V. Beechey; M. Kirk; A. G. Searle

1980-01-01

119

Translocation of indigenous microflora in an experimental model of sepsis.  

PubMed

Translocation of viable bacteria from gut to bloodstream and other sterile body sites during shock has been demonstrated in several experimental and clinical studies. The factors causing translocation and its incidence at different stages of shock are not known. The aim of the study was to evaluate the importance of several factors causing translocation of indigenous microflora in an experimental model of septic shock based on intraperitoneal Escherichia coli sepsis in rats. Counts of inoculated E. coli and translocated bacteria in different locations, gut morphology and haematological values were evaluated at different stages of sepsis. Sepsis developed in all animals and E. coli achieved the highest counts in blood 6 h after inoculation. Translocation was commonest at 6 and 12 h after inoculation. Frequently translocating bacteria were lactobacilli, bifidobacteria, bacteroides and peptostreptococci. In early sepsis, translocation was associated with high E. coli counts in blood, yet in late sepsis the opposite correlation was present. Low infiltration by neutrophils in the ileum and decreased mitotic activity in the colon were associated with a high translocation rate. In early sepsis, translocation was associated with low lymphocyte counts, but in late sepsis, with low neutrophil counts. Translocation of bacteria (including anaerobes) that colonise the gut in high counts takes place during sepsis. Putative influencing factors such as activity of the primary disease (bacterial counts in blood), gut morphology or haematological values seem to have different impacts on translocation, depending on the stage of the disease. PMID:10798556

Naaber, P; Smidt, I; Tamme, K; Liigant, A; Tapfer, H; Mikelsaar, M; Talvik, R

2000-05-01

120

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 Å 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

121

Molecular dynamics and mutational analysis of the catalytic and translocation cycle of RNA polymerase  

PubMed Central

Background During elongation, multi-subunit RNA polymerases (RNAPs) cycle between phosphodiester bond formation and nucleic acid translocation. In the conformation associated with catalysis, the mobile “trigger loop” of the catalytic subunit closes on the nucleoside triphosphate (NTP) substrate. Closing of the trigger loop is expected to exclude water from the active site, and dehydration may contribute to catalysis and fidelity. In the absence of a NTP substrate in the active site, the trigger loop opens, which may enable translocation. Another notable structural element of the RNAP catalytic center is the “bridge helix” that separates the active site from downstream DNA. The bridge helix may participate in translocation by bending against the RNA/DNA hybrid to induce RNAP forward movement and to vacate the active site for the next NTP loading. The transition between catalytic and translocation conformations of RNAP is not evident from static crystallographic snapshots in which macromolecular motions may be restrained by crystal packing. Results All atom molecular dynamics simulations of Thermus thermophilus (Tt) RNAP reveal flexible hinges, located within the two helices at the base of the trigger loop, and two glycine hinges clustered near the N-terminal end of the bridge helix. As simulation progresses, these hinges adopt distinct conformations in the closed and open trigger loop structures. A number of residues (described as “switch” residues) trade atomic contacts (ion pairs or hydrogen bonds) in response to changes in hinge orientation. In vivo phenotypes and in vitro activities rendered by mutations in the hinge and switch residues in Saccharomyces cerevisiae (Sc) RNAP II support the importance of conformational changes predicted from simulations in catalysis and translocation. During simulation, the elongation complex with an open trigger loop spontaneously translocates forward relative to the elongation complex with a closed trigger loop. Conclusions Switching between catalytic and translocating RNAP forms involves closing and opening of the trigger loop and long-range conformational changes in the atomic contacts of amino acid side chains, some located at a considerable distance from the trigger loop and active site. Trigger loop closing appears to support chemistry and the fidelity of RNA synthesis. Trigger loop opening and limited bridge helix bending appears to promote forward nucleic acid translocation. PMID:22676913

2012-01-01

122

Translocation Capture Sequencing: A Method for High Throughput Mapping of Chromosomal Rearrangements  

PubMed Central

Chromosomal translocations require formation and joining of DNA double strand breaks (DSBs). These events disrupt the integrity of the genome and are involved in producing leukemias, lymphomas and sarcomas. Translocations are frequent, clonal and recurrent in mature B cell lymphomas, which bear a particularly high DNA damage burden by virtue of Activation Induced Cytidine Deaminase (AID) expression. Despite the ubiquity of genomic rearrangements, the forces that underlie their genesis are not well understood. Here, we provide a detailed description of a new method for studying these events, Translocation Capture Sequencing (TC-Seq). TC-Seq provides the means to document chromosomal rearrangements genome-wide in primary cells, and to discover recombination hotspots. Demonstrating its effectiveness, we successfully estimate the frequency of c-myc/IgH translocations in primary B cells, and identify hotspots of AID-mediated recombination. Furthermore, TC-Seq can be adapted to generate genome-wide rearrangement maps in any cell type and under any condition. PMID:22033343

Oliveira, Thiago; Resch, Wolfgang; Jankovic, Mila; Casellas, Rafael; Nussenzweig, Michel C.; Klein, Isaac A.

2012-01-01

123

Financial Costs of Large Carnivore Translocations – Accounting for Conservation  

PubMed Central

Human-carnivore conflict continues to present a major conservation challenge around the world. Translocation of large carnivores is widely implemented but remains strongly debated, in part because of a lack of cost transparency. We report detailed translocation costs for three large carnivore species in Namibia and across different translocation scenarios. We consider the effect of various parameters and factors on costs and translocation success. Total translocation cost for 30 individuals in 22 events was $80,681 (US Dollars). Median translocation cost per individual was $2,393, and $2,669 per event. Median cost per cheetah was $2,760 (n?=?23), and $2,108 per leopard (n?=?6). One hyaena was translocated at a cost of $1,672. Tracking technology was the single biggest cost element (56%), followed by captive holding and feeding. Soft releases, prolonged captivity and orphaned individuals also increased case-specific costs. A substantial proportion (65.4%) of the total translocation cost was successfully recovered from public interest groups. Less than half the translocations were confirmed successes (44.4%, 3 unknown) with a strong species bias. Four leopards (66.7%) were successfully translocated but only eight of the 20 cheetahs (40.0%) with known outcome met these strict criteria. None of the five habituated cheetahs was translocated successfully, nor was the hyaena. We introduce the concept of Individual Conservation Cost (ICC) and define it as the cost of one successfully translocated individual adjusted by costs of unsuccessful events of the same species. The median ICC for cheetah was $6,898 and $3,140 for leopard. Translocations are costly, but we demonstrate that they are not inherently more expensive than other strategies currently employed in non-lethal carnivore conflict management. We conclude that translocation should be one available option for conserving large carnivores, but needs to be critically evaluated on a case-by-case basis. PMID:25126849

Weise, Florian J.; Stratford, Ken J.; van Vuuren, Rudolf J.

2014-01-01

124

Financial costs of large carnivore translocations--accounting for conservation.  

PubMed

Human-carnivore conflict continues to present a major conservation challenge around the world. Translocation of large carnivores is widely implemented but remains strongly debated, in part because of a lack of cost transparency. We report detailed translocation costs for three large carnivore species in Namibia and across different translocation scenarios. We consider the effect of various parameters and factors on costs and translocation success. Total translocation cost for 30 individuals in 22 events was $80,681 (US Dollars). Median translocation cost per individual was $2,393, and $2,669 per event. Median cost per cheetah was $2,760 (n?=?23), and $2,108 per leopard (n?=?6). One hyaena was translocated at a cost of $1,672. Tracking technology was the single biggest cost element (56%), followed by captive holding and feeding. Soft releases, prolonged captivity and orphaned individuals also increased case-specific costs. A substantial proportion (65.4%) of the total translocation cost was successfully recovered from public interest groups. Less than half the translocations were confirmed successes (44.4%, 3 unknown) with a strong species bias. Four leopards (66.7%) were successfully translocated but only eight of the 20 cheetahs (40.0%) with known outcome met these strict criteria. None of the five habituated cheetahs was translocated successfully, nor was the hyaena. We introduce the concept of Individual Conservation Cost (ICC) and define it as the cost of one successfully translocated individual adjusted by costs of unsuccessful events of the same species. The median ICC for cheetah was $6,898 and $3,140 for leopard. Translocations are costly, but we demonstrate that they are not inherently more expensive than other strategies currently employed in non-lethal carnivore conflict management. We conclude that translocation should be one available option for conserving large carnivores, but needs to be critically evaluated on a case-by-case basis. PMID:25126849

Weise, Florian J; Stratford, Ken J; van Vuuren, Rudolf J

2014-01-01

125

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

126

Regulating DNA translocation through functionalized soft nanopores  

NASA Astrophysics Data System (ADS)

Nanopores have emerged as promising next-generation devices for DNA sequencing technology. The two major challenges in such devices are: (i) find an efficient way to raise the DNA capture rate prior to funnelling a nanopore, and (ii) reduce the translocation velocity inside it so that single base resolution can be attained efficiently. To achieve these, a novel soft nanopore comprising a solid-state nanopore and a functionalized soft layer is proposed to regulate the DNA electrokinetic translocation. We show that, in addition to the presence of an electroosmotic flow (EOF), which reduces the DNA translocation velocity, counterion concentration polarization (CP) occurs near the entrance of the nanopore. The latter establishes an enrichment of the counterion concentration field, thereby electrostatically enhancing the capture rate. The dependence of the ionic current on the bulk salt concentration, the soft layer properties, and the length of the nanopore are investigated. We show that if the salt concentration is low, the ionic current depends largely upon the length of the nanopore, and the density of the fixed charge of the soft layer, but not upon its degree of softness. On the other hand, if it is high, ionic current blockade always occurs, regardless of the levels of the other parameters. The proposed soft nanopore is capable of enhancing the performance of DNA translocation while maintaining its basic signature of the ionic current at high salt concentration. The results gathered provide the necessary information for designing devices used in DNA sequencing.Nanopores have emerged as promising next-generation devices for DNA sequencing technology. The two major challenges in such devices are: (i) find an efficient way to raise the DNA capture rate prior to funnelling a nanopore, and (ii) reduce the translocation velocity inside it so that single base resolution can be attained efficiently. To achieve these, a novel soft nanopore comprising a solid-state nanopore and a functionalized soft layer is proposed to regulate the DNA electrokinetic translocation. We show that, in addition to the presence of an electroosmotic flow (EOF), which reduces the DNA translocation velocity, counterion concentration polarization (CP) occurs near the entrance of the nanopore. The latter establishes an enrichment of the counterion concentration field, thereby electrostatically enhancing the capture rate. The dependence of the ionic current on the bulk salt concentration, the soft layer properties, and the length of the nanopore are investigated. We show that if the salt concentration is low, the ionic current depends largely upon the length of the nanopore, and the density of the fixed charge of the soft layer, but not upon its degree of softness. On the other hand, if it is high, ionic current blockade always occurs, regardless of the levels of the other parameters. The proposed soft nanopore is capable of enhancing the performance of DNA translocation while maintaining its basic signature of the ionic current at high salt concentration. The results gathered provide the necessary information for designing devices used in DNA sequencing. Electronic supplementary information (ESI) available: Details of the theoretical derivation, numerical implementation, code validation, and the results of the normalized DNA translational velocity for the case of Fig. 5. See DOI: 10.1039/c2nr30102d

Yeh, Li-Hsien; Zhang, Mingkan; Qian, Shizhi; Hsu, Jyh-Ping

2012-03-01

127

Translocation can drive the unfolding of a preprotein domain.  

PubMed Central

Precursor proteins are believed to have secondary and tertiary structure prior to translocation across the Escherichia coli plasma membrane. We now find that preprotein unfolding during translocation can be driven by the translocation event itself. At certain stages, translocation and unfolding can occur without exogenous energy input. To examine this unfolding reaction, we have prepared proOmpA-Dhfr, a fusion protein of the well studied cytosolic enzyme dihydrofolate reductase (Dhfr) connected to the C-terminus of proOmpA, the precursor form of outer membrane protein A. At an intermediate stage of its in vitro translocation, the N-terminal proOmpA domain has crossed the membrane while the folded Dhfr portion, stabilized by its ligands NADPH and methotrexate, has not. When the ligands are removed from this intermediate, translocation occurs by a two-step process. First, 20-30 amino acid residues of the fusion protein translocate concomitant with unfolding of the Dhfr domain. This reaction requires neither ATP, delta mu H+ nor the SecA subunit of translocase. Strikingly, this translocation accelerates the net unfolding of the Dhfr domain. In a second step, SecA and ATP hydrolysis drive the rapid completion of translocation. Thus energy derived from translocation can drive the unfolding of a substantial protein domain. Images PMID:8428582

Arkowitz, R A; Joly, J C; Wickner, W

1993-01-01

128

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

129

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

130

Two Children with Acute Lymphoblastic Leukemia and “Jumping” Translocations  

Microsoft Academic Search

“Jumping” translocations (JT) are relatively rare and are associated with poor prognosis. We report two male patients with childhood acute lymphoblastic leukemia (ALL) and abnormal cell lines detected on bone marrow cytogenetics. Diagnostic marrow cytogenetics were not available for either patient. In patient 1, approximately 11 years after diagnosis, cytogenetics revealed a single translocation, t(1;2)(q23;q32), which was followed by translocations

Angela Jarvis; Praveen Sharma; Neville Watson; Arabella Smith

1999-01-01

131

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

132

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

133

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

134

Genetic instability in mass-rearing colonies of a sex-linked translocation strain of Lucilia cuprina (Wiedemann) (Diptera: Calliphoridae) during a field trial of genetic control.  

PubMed

Genetic breakdown occurred in a strain of Lucilia cuprina constructed for the purpose of genetic control of this pest. The strain incorporated autosomal recessive eye colour mutations linked in repulsion with a translocation involving the Y chromosome (male-determining) and two autosomes. In the original strain females had white eyes and males were wild type. The spontaneous breakdown involved a failure of the sex-limited inheritance of the eye colour mutations. Characteristically the frequency of white-eyed males increased rapidly in the strain, whereas the frequencies of the three other phenotypically recognizable breakdown products did not. This suggested that the white-eyed males had a selective advantage over both the wild type males and the other breakdown products. Genetic analysis revealed that recombination, which is normally rare in L. cuprina males, is considerably more frequent in the presence of a Y-autosome translocation, but that recombination alone was insufficient to account for the rate of increase of the white-eyed males in the colony. Genetic and cytological analysis of the breakdown products revealed that reversion of the multi-break translocation also occurred, and that many of the white-eyed males had either only a Y-single-autosome translocation or no translocation at all; thus these males were more fertile than the wild type multi-translocation males. In addition, under colony cage conditions the white-eyed males may have had a behavioural advantage in competition with the wild type males. PMID:24301349

Foster, G G; Maddern, R H; Mills, A T

1980-05-01

135

Microdeletion syndromes, balanced translocations, and gene mapping.  

PubMed Central

High resolution prometaphase chromosome banding has allowed the detection of discrete chromosome aberrations which escaped earlier metaphase examinations. Consistent tiny deletions have been detected in some well established malformation syndromes: an interstitial deletion in 15q11/12 in the majority of patients with the Prader-Willi syndrome and in a minority of patients with the Angelman (happy puppet) syndrome; a terminal deletion of 17p13.3 in most patients examined with the Miller-Dieker syndrome; an interstitial deletion of 8q23.3/24.1 in a large majority of patients with the Giedion-Langer syndrome; an interstitial deletion of 11p13 in virtually all patients with the WAGR (Wilms' tumour-aniridia-gonadoblastoma-retardation) syndrome; and an interstitial deletion in 22q11 in about one third of patients with the DiGeorge sequence. In addition, a combination of chromosome prometaphase banding and DNA marker studies has allowed the localisation of the genes for retinoblastoma and for Wilms' tumour and the clarification of both the autosomal recessive nature of the mutation and the possible somatic mutations by which the normal allele can be lost in retina and kidney cells. After a number of X linked genes had been mapped, discrete deletions in the X chromosome were detected by prometaphase banding with specific attention paid to the sites of the gene(s) in males who had from one to up to four different X linked disorders plus mental retardation. Furthermore, the detection of balanced translocations in probands with disorders caused by autosomal dominant or X linked genes has allowed a better insight into the localisation of these genes. In some females with X linked disorders, balanced X; autosomal translocations have allowed the localisation of X linked genes at the breakpoint on the X chromosome. Balanced autosome; autosome translocations segregating with autosomal dominant conditions have provided some clues to the gene location of these conditions. In two conditions, Greig cephalopolysyndactyly and dominant aniridia, two translocation families with one common breakpoint have allowed quite a confident location of the genes at the common breakpoint at 7p13 and 11p13, respectively. PMID:3050093

Schinzel, A

1988-01-01

136

Primary photochemical event in vision: proton translocation.  

PubMed Central

Picosecond studies of rhodopsin in low-temperature glasses have been carried out in order to observe directly the risetime of prelumirhodopsin, the first intermediate in the visual pathway. Only at 20 K or below can the risetime of this intermediate be resolved and even at 4 K it is astoundingly rapid, about 36 psec. An examination of the Arrhenius dependence on temperature of the rate of formation of prelumirhodopsin shows a strong deviation from linearity at low temperatures, i.e., non-Arrhenius behavior. This marked non-linear behavior is characteristic of a quantum mechanical tunneling event such as the translocation of hydrogen. An excellent candidate for the tunnelling process is the hydrogen of the protonated Schiff base formed between opsin and its retinal chromophore. Deuterium-exchanged rhodopsin, in which the Schiff base hydrogen is replaced by a deuterium, also shows a marked non-Arrhenius temperature dependence at low temperatures, consistent with tunneling. The rate of formation of prelumirhodopsin in deuterium-exchanged samples is much slower and a deuterium isotope effect kH/kD approximately or equal to 7 is observed. The data support a model in which the formation of prelumirhodopsin involves translocation of a proton toward the Schiff base nitrogen of the retinal chromophore. PMID:20620

Peters, K; Applebury, M L; Rentzepis, P M

1977-01-01

137

Multistep protein unfolding during nanopore translocation  

NASA Astrophysics Data System (ADS)

Cells are divided into compartments and separated from the environment by lipid bilayer membranes. Essential molecules are transported back and forth across the membranes. We have investigated how folded proteins use narrow transmembrane pores to move between compartments. During this process, the proteins must unfold. To examine co-translocational unfolding of individual molecules, we tagged protein substrates with oligonucleotides to enable potential-driven unidirectional movement through a model protein nanopore, a process that differs fundamentally from extension during force spectroscopy measurements. Our findings support a four-step translocation mechanism for model thioredoxin substrates. First, the DNA tag is captured by the pore. Second, the oligonucleotide is pulled through the pore, causing local unfolding of the C terminus of the thioredoxin adjacent to the pore entrance. Third, the remainder of the protein unfolds spontaneously. Finally, the unfolded polypeptide diffuses through the pore into the recipient compartment. The unfolding pathway elucidated here differs from those revealed by denaturation experiments in solution, for which two-state mechanisms have been proposed.

Rodriguez-Larrea, David; Bayley, Hagan

2013-04-01

138

Factors Influencing Success of Greenback Cutthroat Trout Translocations  

Microsoft Academic Search

Native subspecies of cutthroat trout Oncorhynchus clarki have declined drastically because of the introduction of nonnative salmonids, overharvesting, and habitat degradation. Conservation of most declining subspecies will include establishing new populations through translocation of genetically pure fish. Recovery of greenback cutthroat trout O. clarki stomias has been ongoing for 25 years, so the attempted translocations of this subspecies provide unique

Amy L. Harig; Kurt D. Fausch; Michael K. Young

2000-01-01

139

Cytogenetic observations on a Robertsonian translocation in Saanen goats (1)  

E-print Network

Cytogenetic observations on a Robertsonian translocation in Saanen goats (1) I. BURGUETE D. DI type was detected in a herd of 15 goats of the Saanen breed, reared on a farm located in southern Italy-armed chromosome. Key words : Robertsonian translocation, goat, chromosomes. Résumé Etude cytogénétique d

Boyer, Edmond

140

Tools and Technology Post-Release Acclimation of Translocated  

E-print Network

system, GPS, movement rate, Ovis canadensis, translocation, Wyoming. The increasing availability of high objective was to quantify temporal acclimation for low-elevation, non-migratory bighorn sheep (Ovis canadensis) from 3 translocations to the Seminoe Mountains in south-central Wyoming, USA, from 2009 to 2010

Beck, Jeffrey L.

141

Polymer translocation through a long nanopore Elena Slonkina  

E-print Network

Polymer translocation through a long nanopore Elena Slonkina Department of Chemistry, Moscow State, Texas 77005 Received 9 September 2002; accepted 23 January 2003 Polymer translocation through a nanopore through a nanopore indicate that the size and geometry of the pore are important factors in polymer

142

Translocation events in a single walled carbon nanotube  

PubMed Central

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

2010-01-01

143

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

144

RNA Polymerase II Flexibility During Translocation From Normal Mode Analysis  

PubMed Central

The structural dynamics in eukaryotic RNA polymerase II (RNAPII) is described from computational normal mode analysis based on a series of crystal structures of pre- and post-translocated states with open and closed trigger loops. Conserved modes are identified that involve translocation of the nucleic acid complex coupled to motions of the enzyme, in particular in the clamp and jaw domains of RNAPII. A combination of these modes is hypothesized to be involved during active transcription. The NMA modes indicate furthermore that downstream DNA translocation may occur separately from DNA:RNA hybrid translocation. A comparison of the modes between different states of RNAPII suggests that productive translocation requires an open trigger loop and is inhibited by the presence of an NTP in the active site. This conclusion is also supported by a comparison of the overall flexibility in terms of root mean square fluctuations. PMID:19714773

Feig, Michael; Burton, Zachary F.

2013-01-01

145

Polymer translocation into a fluidic channel through a nanopore  

E-print Network

Using two dimensional Langevin dynamics simulations, we investigate the dynamics of polymer translocation into a fluidic channel with diameter $R$ through a nanopore under a driving force $F$. Due to the crowding effect induced by the partially translocated monomers, the translocation dynamics is significantly altered in comparison to an unconfined environment, namely, we observe a nonuniversal dependence of the translocation time $\\tau$ on the chain length $N$. $\\tau$ initially decreases rapidly and then saturates with increasing $R$, and a dependence of the scaling exponent $\\alpha$ of $\\tau$ with $N$ on the channel width $R$ is observed. The otherwise inverse linear scaling of $\\tau$ with $F$ breaks down and we observe a minimum of $\\alpha$ as a function of $F$. These behaviors are interpreted in terms of the waiting time of an individual segment passing through the pore during translocation.

Kaifu Luo; Ralf Metzler

2010-08-13

146

Range-wide success of red-cockaded woodpecker translocations.  

SciTech Connect

Edwards, John W.; Costa, Ralph. 2004. Range-wide success of red-cockaded woodpecker translocations. In: Red-cockaded woodpecker; Road to Recovery. Proceedings of the 4th Red-cockaded woodpecker Symposium. Ralph Costa and Susan J. Daniels, eds. Savannah, Georgia. January, 2003. Chapter 6. Translocation. Pp 307-311. Abstract: Red-cockaded woodpeckers (Picoides borealis) have declined range-wide during the past century, suffering from habitat loss and the effects of fire exclusion in older southern pine forests. Red-cockaded woodpecker translocations are a potentially important tool in conservation efforts to reestablish red-cockaded woodpeckers in areas from which they have been extirpated. Currently, translocations are critical in ongoing efforts to save and restore the many existing small populations. We examined the effects of demographic and environmental factors on the range-wide success of translocations between 1989 and 1995.

Edwards, John W.; Costa, Ralph

2004-12-31

147

Crystal structure of the Yersinia enterocolitica type III secretion chaperone SycD in complex with a peptide of the minor translocator YopD  

PubMed Central

Background Type III secretion systems are used by Gram-negative bacteria as “macromolecular syringes” to inject effector proteins into eukaryotic cells. Two hydrophobic proteins called translocators form the necessary pore in the host cell membrane. Both translocators depend on binding to a single chaperone in the bacterial cytoplasm to ensure their stability and efficient transport through the secretion needle. It was suggested that the conserved chaperones bind the more divergent translocators via a hexapeptide motif that is found in both translocators and conserved between species. Results We crystallized a synthetic decapeptide from the Yersinia enterocolitica minor type III secretion translocator YopD bound to its cognate chaperone SycD and determined the complex structure at 2.5?Å resolution. The structure of peptide-bound SycD is almost identical to that of apo SycD with an all helical fold consisting of three tetratricopeptide repeats (TPRs) and an additional C-terminal helix. Peptide-bound SycD formed a kinked head-to-head dimer that had previously been observed for the apo form of SycD. The homodimer interface comprises both helices of the first tetratricopeptide repeat. The YopD peptide bound in extended conformation into a mainly hydrophobic groove on the concave side of SycD. TPRs 1 and 2 of SycD form three hydrophobic pockets that accommodated the conserved hydrophobic residues at position 1, 3 and 6 of the translocator hexapeptide sequence. Two tyrosines that are highly conserved among translocator chaperones contribute to the hydrophobic patches but also form hydrogen bonds to the peptide backbone. Conclusions The interaction between SycD and YopD is very similar to the binding of the Pseudomonas minor translocator PopD to its chaperone PcrH and the Shigella major translocator IpaB to its chaperone IpgC. This confirms the prediction made by Kolbe and co-workers that a hexapeptide with hydrophobic residues at three positions is a conserved chaperone binding motif. Because the hydrophobic groove on the concave side of translocator chaperones is involved in binding of the major and the minor translocator, simultaneous binding of both translocators to a single type III secretion class II chaperone appears unlikely. PMID:22708907

2012-01-01

148

Absence of Anaplastic Lymphoma Kinase Translocations in Signet Ring Cell Carcinomas of the Upper Gastrointestinal Tract  

PubMed Central

ABSTRACT BACKGROUND: Anaplastic lymphoma kinase (ALK) fusion oncogenes are present in multiple cancer types. The inversion of echinoderm microtubule-associated protein-like 4 (EML4) and anaplastic lymphoma kinase (ALK) genes on chromosome 2 is present in a subset of patients with non-small-cell lung cancer (NSCLC). ALK-rearranged lung cancers demonstrate a significantly higher incidence of signet ring cell histology than do ALK-negative tumors. Based on the histologic similarities of ALK-rearranged NSCLC and signet ring cell carcinomas (SRCCs) of the gastrointestinal tract, we hypothesized that SRCC of the upper gastrointestinal (GI) tract may also harbor ALK translocations. METHODS: Thirty-five formalin-fixed, paraffin-embedded (FFPE) diagnostic tissue specimens of SRCC or poorly differentiated adenocarcinoma with greater than 10% signet ring cell features originating from the upper GI tract were obtained and confirmed by a board-certified, GI pathologist. SRCC specimens were analyzed by fluorescence in situ hybridization (FISH) analysis, with an ALK (2p23) break-apart probe. RESULTS: The FISH analysis revealed no evidence of ALK translocation. All 35 (100%) SRCC specimens showed intact ALK FISH signals. CONCLUSIONS: These data indicate that, despite histologic similarities between SRCC of the upper GI tract and ALK-positive NSCLC, ALK translocations are unlikely to be a significant contributor to the molecular etiology of SRCC. Further genomic investigations are ongoing. PMID:24799969

Miller, Jill; Peng, Zhihua; Wilcox, Rebecca; Evans, Mark; Ades, Steven

2014-01-01

149

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

150

Characterization of Robertsonian translocations by using fluorescence in situ hybridization.  

PubMed Central

Fluorescence in situ hybridization with five biotin-labeled probes (three alphoid probes, a probe specific for beta-satellite sequences in all acrocentric chromosomes, and an rDNA probe) was used to characterize 30 different Robertsonian translocations, including three t(13;13); one t(15;15), four t(21;21), three t(13;14), two t(13;15), two (13;21), two t(13;22), one t(14;15), eight t(14;21), two t(14;22), and two t(21;22). Of 8 de novo homologous translocations, only one t(13;13) chromosome was interpreted as dicentric, while 19 of 22 nonhomologous Robertsonian translocations were dicentric. The three monocentric nonhomologous translocations included both of the t(13;21) and one t(21;22). Two of 26 translocations studied using the beta-satellite probe showed a positive signal, while rDNA was undetectable in 10 cases studied. These results indicate that most homologous Robertsonian translocations appear monocentric, while the bulk of nonhomologous translocations show two alphoid signals. A majority of the breakpoints localized using this analysis seem to be distal to the centromere and just proximal to the beta-satellite and nuclear-organizing regions. Images Figure 4 Figure 1 Figure 2 Figure 3 Figure 5 PMID:1729886

Wolff, D J; Schwartz, S

1992-01-01

151

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

152

Slowing DNA Translocation through a Nanopore Using a Functionalized Electrode  

PubMed Central

Nanopores were fabricated with an integrated microscale Pd electrode coated with either a hydrogen-bonding, or hydrophobic monolayer. Bare pores, or those coated with octane thiol, translocated single-stranded DNA with times of a few microseconds per base. Pores functionalized with 4(5)-(2-mercaptoethyl)-1H-imidazole-2-carboxamide slowed average translocation times, calculated as the duration of the event divided by the number of bases translocated, to about 100 microseconds per base at biases in the range of 50 to 80 mV. PMID:24161197

Krishnakumar, Padmini; Gyarfas, Brett; Song, Weisi; Sen, Suman; Zhang, Peiming; Krsti?, Predrag; Lindsay, Stuart

2013-01-01

153

Polymer translocation through a nanopore under a pulling force  

E-print Network

We investigate polymer translocation through a nanopore under a pulling force using Langevin dynamics simulations. We concentrate on the influence of the chain length $N$ and the pulling force $F$ on the translocation time $\\tau$. The distribution of $\\tau$ is symmetric and narrow for strong $F$. We find that $\\tau\\sim N^{2}$ and translocation velocity $v\\sim N^{-1}$ for both moderate and strong $F$. For infinitely wide pores, three regimes are observed for $\\tau$ as a function of $F$. With increasing $F$, $\\tau$ is independent of $F$ for weak $F$, and then $\\tau\\sim F^{-2+\

Ilkka Huopaniemi; Kaifu luo; Tapio Ala-Nissila; See-Chen Ying

2006-08-23

154

De Novo microdeletion on an inherited Robertsonian translocation chromosome: A cause for dysmorphism in the apparently balanced translocation carrier  

SciTech Connect

Robertsonian translocations are usually ascertained through abnormal children, making proposed phenotypic effects of apparently balanced translocations difficult to study in an unbiased way. From molecular genetic studies, though, some apparently balanced rearrangments are now known to be associated with phenotypic abnormalities resulting from uniparental disomy. Molecular explanations for other cases in which abnormality is seen in a balanced translocation carrier are being sought. In the present paper, an infant is described who has retarded growth, developmental delay, gross muscular hypotonia, slender habitus, frontal bossing, micrognathia, hooked nose, abundant wispy hair, and blue sclerae. Cytogenetically, she appeared to be a carrier of a balanced, paternally derived 14;21 Robertsonian translocation. Analysis of DNA polymorphisms showed that she had no paternal allele at the D14S13 locus (14q32). Study of additional DNA markers within 14q32 revealed that her previously undescribed phenotype results from an interstitial microdeletion within 14q32. Fluorescent in situ hybridization was used to show that this microdeletion had occurred de novo on the Robertsonian translocation chromosome. These observations may reactivate old suspicions of a causal association between Robertsonian translocations and de novo rearrangements in offspring; a systematic search for similar subcytogentic rearrangements in other families, in which there are phenotypically abnormal children with apparently balanced translocations, may be fruitful. The clinical and molecular genetic data presented also define a new contiguous gene syndrome due to interstitial 14q32 deletion. 42 refs., 4 figs., 1 tab.

Bonthron, D.T.; Smith, S.J.L.; Fantes, J.; Gosden, C.M.

1993-09-01

155

Sequence dependence of DNA translocation through a nanopore  

E-print Network

We investigate the dynamics of DNA translocation through a nanopore using 2D Langevin dynamics simulations, focusing on the dependence of the translocation dynamics on the details of DNA sequences. The DNA molecules studied in this work are built from two types of bases $A$ and $C$, which has been shown previously to have different interactions with the pore. We study DNA with repeating blocks $A_nC_n$ for various values of $n$, and find that the translocation time depends strongly on the {\\em block length} $2n$ as well as on the {\\em orientation} of which base entering the pore first. Thus, we demonstrate that the measurement of translocation dynamics of DNA through nanopore can yield detailed information about its structure. We have also found that the periodicity of the block sequences are contained in the periodicity of the residence time of the individual nucleotides inside the pore.

Kaifu Luo; Tapio Ala-Nissila; See-Chen Ying; Aniket Bhattacharya

2007-11-21

156

Relations between Light Level, Sucrose Concentration, and Translocation of Carbon 11 in Zea mays Leaves  

PubMed Central

The mechanism of carbon transport in Zea mays leaves was investigated using carbon 11 which is a short lived (half-life 20.4 min) positronemitting isotope. The gamma radiation produced on annihilation allows in vivo or nondestructive measurement of the isotope and the short half-life allows many measurements of translocation to be made on the same leaf within the same day. Carbon 11 produced by the 10B (d,n)11C nuclear reaction was converted to 11CO2, fed to a leaf as a short pulse, and assimilated during photosynthesis. The progress of the radioactive pulse along the leaf in the phloem was monitored in several positions simultaneously with counters. The counters were NaI crystals with photomultipliers and the output was amplified, passed to single channel analyzers, and the counts accumulated for 20 seconds every 30 seconds. Corrections were made for the half-life and background radiation by computer, and the results were displayed on a high speed plotter. Information derived from the corrected data included the speed of translocation, the shape of the radioactive carbon pulse, and the influence of light and distance along the leaf on these parameters. The plants were kept under controlled environment conditions during all measurements. A speed was derived from the time displacement of the midpoint of the front of the pulse, measured at two positions along the leaf. This was an apparent mean speed of translocation because it averaged a variation in speed with distance, variation in speed between or within sieve tubes, and it averaged the mean speed of all of the particles in the pulse. A wide range of speeds of translocation from 0.25 to 11 cm min?1 was observed but most of the variability was due to the variation in light available to the leaf. For example, the speed of translocation was proportional to the light level on either the whole plant or individual leaf. Shading of the leaf established that the light effect was not localized in either the feeding area or in the portion of the leaf on which the measurements were made. It was proposed that the speed was dependent on the proportion of the leaf in the light upstream from the last counter. The speed of translocation was relatively independent of the stage of growth of the plant, age of the leaf, and the time during the diurnal light cycle. Data obtained on the level of the reducing sugars, starch, and sucrose in the leaf were related to the speed of translocation. A biphasic relationship between speed and sucrose concentration in the leaf was established and the high speeds measured during experiments only occurred when sucrose concentrations in the leaf exceeded 8% of the dry weight. The shape of the pulse loaded into and translocated in the phloem was estimated from the half-width of the pulse. The half-width was primarily determined by loading phenomena which resulted in an increase in the half-width from 2 minutes when fed to the leaf to more than 40 minutes in the phloem. In many examples, the pulse continued to broaden with distance along the leaf from the fed region. The half-width was independent of the speed but highly dependent on the light level. PMID:16659948

Troughton, John H.; Currie, B. G.; Chang, F. H.

1977-01-01

157

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

158

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

159

Two new X-autosome translocations in the mouse  

Microsoft Academic Search

The reciprocal translocations T(X;4)37H and T(X;11)38H were induced by acute X-irradiation of spermatozoa. Male heterozygotes are completely aspermic with a spermatogenic block at pachytene and testis masses about one third of normal, though metaphase I is very occasionally reached in T37H. For both translocations the X chromosome breakpoints are in band XA2, and the autosomal breakpoints are in 4D3 for

A. G. Searle; C. V. Beechey; E. P. Evans; M. Kirk

1983-01-01

160

Survival of mountain quail translocated from two distinct source populations  

USGS Publications Warehouse

Translocation of mountain quail (Oreortyx pictus) to restore viable populations to their former range has become a common practice. Because differences in post-release vital rates between animals from multiple source populations has not been well studied, wildlife and land managers may arbitrarily choose the source population or base the source population on immediate availability when planning translocation projects. Similarly, an understanding of the optimal proportion of individuals from different age and sex classes for translocation would benefit translocation planning. During 2006 and 2007, we captured and translocated 125 mountain quail from 2 ecologically distinct areas: 38 from southern California and 87 from southwestern Oregon. We released mountain quail in the Bennett Hills of south-central Idaho. We radio-marked and monitored a subsample of 58 quail and used them for a 2-part survival analysis. Cumulative survival probability was 0.23?±?0.05 (SE) at 150 days post-release. We first examined an a priori hypothesis (model) that survival varied between the 2 distinct source populations. We found that source population did not explain variation in survival. This result suggests that wildlife managers have flexibility in selecting source populations for mountain quail translocation efforts. In a post hoc examination, we pooled the quail across source populations and evaluated differences in survival probabilities between sex and age classes. The most parsimonious model indicated that adult male survival was substantially less than survival rates of other mountain quail age and sex classes (i.e., interaction between sex and age). This result suggests that translocation success could benefit by translocating yearling males rather than adult males, perhaps because adult male breeding behavior results in vulnerability to predators

Troy, Ronald J.; Coates, Peter S.; Connelly, John W.; Gillette, Gifford; Delehanty1, David J.

2013-01-01

161

Polymer translocation through a nanopore - a showcase of anomalous diffusion  

E-print Network

The translocation dynamics of a polymer chain through a nanopore in the absence of an external driving force is analyzed by means of scaling arguments, fractional calculus, and computer simulations. The problem at hand is mapped on a one dimensional {\\em anomalous} diffusion process in terms of reaction coordinate $s$ (i.e. the translocated number of segments at time $t$) and shown to be governed by an universal exponent $\\alpha = 2/(2\

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

2007-01-26

162

Fast DNA Translocation through a Solid-State Nanopore  

Microsoft Academic Search

We report translocation experiments on double-strand DNA through a silicon oxide nanopore. Samples containing DNA fragments with seven different lengths between 2000 to 96000 basepairs have been electrophoretically driven through a 10 nm pore. We find a power-law scaling of the translocation time versus length, with an exponent of 1.26 $\\\\pm$ 0.07. This behavior is qualitatively different from the linear

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

2005-01-01

163

Voltage-Driven DNA Translocations through a Nanopore  

Microsoft Academic Search

We measure current blockade and time distributions for single-stranded DNA polymers during voltage-driven translocations through a single alpha-hemolysin pore. We use these data to determine the velocity of the polymers in the pore. Our measurements imply that, while polymers longer than the pore are translocated at a constant speed, the velocity of shorter polymers increases with decreasing length. This velocity

Amit Meller; Lucas Nivon; Daniel Branton

2001-01-01

164

15\\/15 translocation in Prader-Willi syndrome  

Microsoft Academic Search

Two further cases (one previously published as D\\/D translocation) of 15\\/15 translocation in Prader-Willi syndrome are reported, which brings the total cases of this specific chromosomal anomaly in connection with this specific syndrome up to three or possibly four. It is suggested that Prader-Willi syndrome might be caused by loss of short arm material of chromosome 15.

M Fraccaro; O Zuffardi; E M Buhler; L P Jurik

1977-01-01

165

Controlled translocation of DNA segments through nanoelectrode gaps  

SciTech Connect

Molecular dynamics simulations show that electrophoresis of DNA segments through a nanoscale electrode gap can be controlled by applying appropriate biased voltages in the transmembrane direction. The translocation velocities are dependent on both the DNA molecular weight and nucleotide structure. Application of alternating driving fields results in oscillatory motion of DNA inside the gap. Interruption of the driving field can effectively pause the translocation of DNA segments. Results from this work are useful for designing novel sequencing devices.

Zhao, Xiongce [ORNL; Payne, Christina M [Vanderbilt University; Cummings, Peter T [ORNL

2008-01-01

166

Reductions in Platelet 18-kDa Translocator Protein Density Are Associated with Adult Separation Anxiety in Patients with Bipolar Disorder  

Microsoft Academic Search

Background: Recent studies indicate that adult separation anxiety disorder is a discrete diagnostic entity and worthy of attention. Previously, we found a significant association between platelet expression of the 18-kDa translocator protein (TSPO) and adult separation anxiety in patients with panic disorder or major depression. The aim of this study was to explore whether adult separation anxiety might be a

Marianna Abelli; Beatrice Chelli; Barbara Costa; Lisa Lari; Alessandra Cardini; Camilla Gesi; Matteo Muti; Antonio Lucacchini; Claudia Martini; Giovanni B. Cassano; Stefano Pini

2010-01-01

167

Sec61?, a subunit of the Sec61 protein translocation channel at the Endoplasmic Reticulum, is involved in the transport of Gurken to the plasma membrane  

Microsoft Academic Search

BACKGROUND: Protein translocation across the membrane of the Endoplasmic Reticulum (ER) is the first step in the biogenesis of secretory and membrane proteins. Proteins enter the ER by the Sec61 translocon, a proteinaceous channel composed of three subunits, ?, ? and ?. While it is known that Sec61? forms the actual channel, the function of the other two subunits remains

Anshuman Kelkar; Bernhard Dobberstein

2009-01-01

168

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

169

Surface modification of graphene nanopores for protein translocation  

PubMed Central

Studies of DNA translocation through graphene nanopores have revealed their potential for DNA sequencing. Here we report a study of protein translocation through chemically modified graphene nanopores. A transmission electron microscope (TEM) was used to cut nanopores with diameters between 5-20 nm in multilayer graphene prepared by chemical vapor deposition (CVD). After oxygen plasma treatment, the dependence of the measured ionic current on salt concentration and pH was consistent with a small surface charge induced by the formation of carboxyl groups. While translocation of gold nanoparticles (10 nm) was readily detected through such treated pores of a larger diameter, translocation of protein ferritin was not observed either for oxygen plasma treated pores, or for pores modified with mercaptohexadecanoic acid. Ferritin translocation events were reliably observed after the pores were modified with the phospholipid-PEG (DPPE-PEG750) amphiphile. The ion current signature of translocation events was complex, suggesting that a series of interactions between the protein and pore occur during the process. PMID:24231385

Shan, Y. P.; Tiwari, P. B.; Krishnakumar, P.; Vlassiouk, I.; Li, W.Z.; Wang, X.W.; Darici, Y.; Lindsay, S.M.; Wang, H. D.; Smirnov, S.; He, J.

2014-01-01

170

Millisecond dynamics of RNA polymerase II translocation at atomic resolution.  

PubMed

Transcription is a central step in gene expression, in which the DNA template is processively read by RNA polymerase II (Pol II), synthesizing a complementary messenger RNA transcript. At each cycle, Pol II moves exactly one register along the DNA, a process known as translocation. Although X-ray crystal structures have greatly enhanced our understanding of the transcription process, the underlying molecular mechanisms of translocation remain unclear. Here we use sophisticated simulation techniques to observe Pol II translocation on a millisecond timescale and at atomistic resolution. We observe multiple cycles of forward and backward translocation and identify two previously unidentified intermediate states. We show that the bridge helix (BH) plays a key role accelerating the translocation of both the RNA:DNA hybrid and transition nucleotide by directly interacting with them. The conserved BH residues, Thr831 and Tyr836, mediate these interactions. To date, this study delivers the most detailed picture of the mechanism of Pol II translocation at atomic level. PMID:24753580

Silva, Daniel-Adriano; Weiss, Dahlia R; Pardo Avila, Fátima; Da, Lin-Tai; Levitt, Michael; Wang, Dong; Huang, Xuhui

2014-05-27

171

Surface modification of graphene nanopores for protein translocation  

NASA Astrophysics Data System (ADS)

Studies of DNA translocation through graphene nanopores have revealed their potential for DNA sequencing. Here we report a study of protein translocation through chemically modified graphene nanopores. A transmission electron microscope (TEM) was used to cut nanopores with diameters between 5 and 20 nm in multilayer graphene prepared by chemical vapor deposition (CVD). After oxygen plasma treatment, the dependence of the measured ionic current on salt concentration and pH was consistent with a small surface charge induced by the formation of carboxyl groups. While translocation of gold nanoparticles (10 nm) was readily detected through such treated pores of a larger diameter, translocation of the protein ferritin was not observed either for oxygen plasma treated pores, or for pores modified with mercaptohexadecanoic acid. Ferritin translocation events were reliably observed after the pores were modified with the phospholipid-PEG (DPPE-PEG750) amphiphile. The ion current signature of translocation events was complex, suggesting that a series of interactions between the protein and pores occurs during the process.

Shan, Y. P.; Tiwari, P. B.; Krishnakumar, P.; Vlassiouk, I.; Li, W. Z.; Wang, X. W.; Darici, Y.; Lindsay, S. M.; Wang, H. D.; Smirnov, S.; He, J.

2013-12-01

172

Cytologically integrated physical restriction fragment length polymorphism maps for the barley genome based on translocation breakpoints.  

PubMed Central

We have developed a new technique for the physical mapping of barley chromosomes using microdissected translocation chromosomes for PCR with sequence-tagged site primers derived from >300 genetically mapped RFLP probes. The positions of 240 translocation breakpoints were integrated as physical landmarks into linkage maps of the seven barley chromosomes. This strategy proved to be highly efficient in relating physical to genetic distances. A very heterogeneous distribution of recombination rates was found along individual chromosomes. Recombination is mainly confined to a few relatively small areas spaced by large segments in which recombination is severely suppressed. The regions of highest recombination frequency (frequencies and marker densities are highly conserved between the genomes of barley and wheat. The findings for barley support the conclusions drawn from deletion mapping in wheat that for all plant genomes, notwithstanding their size, the marker-rich regions are all of similar gene density and recombination activity and, therefore, should be equally accessible to map-based cloning. PMID:10628998

Künzel, G; Korzun, L; Meister, A

2000-01-01

173

Background Subtraction Techniques  

Microsoft Academic Search

Background subtraction is a commonly used class of techniques for segmenting out objects of interest in a scene for applications such as surveillance. This paper surveys a repre- sentative sample of the published techiques for background subtraction, and analyses them with respect to three important attributes: foreground detection; background maintenance; and postprocessing.

Alan M. McIvor

174

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

175

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

176

Translocation and Endocytosis for Cell-penetrating Peptide Internalization  

PubMed Central

Cell-penetrating peptides (CPPs) share the property of cellular internalization. The question of how these peptides reach the cytoplasm of cells is still widely debated. Herein, we have used a mass spectrometry-based method that enables quantification of internalized and membrane-bound peptides. Internalization of the most used CPP was studied at 37 °C (endocytosis and translocation) and 4 °C (translocation) in wild type and proteoglycan-deficient Chinese hamster ovary cells. Both translocation and endocytosis are internalization pathways used by CPP. The choice of one pathway versus the other depends on the peptide sequence (not the number of positive changes), the extracellular peptide concentration, and the membrane components. There is no relationship between the high affinity of these peptides for the cell membrane and their internalization efficacy. Translocation occurs at low extracellular peptide concentration, whereas endocytosis, a saturable and cooperative phenomenon, is activated at higher concentrations. Translocation operates in a narrow time window, which implies a specific lipid/peptide co-import in cells. PMID:19833724

Jiao, Chen-Yu; Delaroche, Diane; Burlina, Fabienne; Alves, Isabel D.; Chassaing, Gérard; Sagan, Sandrine

2009-01-01

177

Sulfur Dioxide Inhibition of Translocation in Bean Plants 1  

PubMed Central

Exposure of the source leaf of bean (Phaseolus vulgaris L. cv. Black Valentine) for 2 hours to 2.9 microliters per liter SO2 inhibited the net photosynthetic rate an average of 75% and, simultaneously, the translocation rate an average of 45%. Calculations indicated that the experimentally determined translocation rates from SO2-stressed leaves were lower than were the rates expected on the basis of the observed reductions in photosynthesis. It is inferred that, under SO2 stress, the phloem-loading system becomes a major limiting step in controlling the translocation rate. Following removal of SO2, photosynthesis recovered quite rapidly (to about 60% of its preexposure rate within 2 hours), but the translocation rate failed to increase during this time interval. This delayed response of translocation to removal of SO2 does not appear to be due to an injury effect of SO2, inasmuch as a similar effect was obtained by exposing the source leaf to a short (2-hour) interval of dark. PMID:16662191

Teh, Kwang Ho; Swanson, Carroll A.

1982-01-01

178

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

179

A Somatic Origin of Homologous Robertsonian Translocations and Isochromosomes  

PubMed Central

One t(14q14q), three t(15q15q), 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. ImagesFigure 1 PMID:8304346

Robinson, W. P.; Bernasconi, F.; Basaran, S.; Yüksel-Apak, M.; Neri, G.; Serville, F.; Balicek, P.; Haluza, R.; Farah, L. M. S.; Lüleci, G.; Schinzel, A. A.

1994-01-01

180

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

181

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

182

[Current aspects of sepsis caused by bacterial translocation].  

PubMed

Bacterial translocation has been put forward as a concept to explain sepsis without an infectious focus, but it has been difficult to prove in humans. Dysfunction of the intestinal barrier, which is composed of physical, biochemical and immunological factors, is the pathophysiological prerequisite for bacterial translocation. Recent findings indicate that not only viable bacteria but also pathogen associated molecular patterns may translocate and cause sepsis. Molecular detection methods for bacteria or their components have been developed to address these new concepts, but they have not yet become widely available. Specific therapeutic interventions within the sepsis cascades and signaling pathways of the innate and specific immune system so far have not been successful. Selective oral decontamination (SOD) und selective digestive tract decontamination (SDD) are efficacious prophylactic measures against nosocomial septic complications. An increased incidence of resistant pathogens has not been encountered. The use of probiotics as prophylaxis against septic complications is controversial and has led in some studies to a worse prognosis. PMID:22711326

Lamprecht, G; Heininger, A

2012-06-01

183

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

184

A nanopore-nanofiber mesh biosensor to control DNA translocation  

PubMed Central

Solid-state nanopores show promise as single-molecule sensors for biomedical applications, but to increase their resolution and efficiency analyte molecules must remain longer in the nanopore sensing volume. Here we demonstrate a novel, facile, and customizable nanopore sensor modification that reduces double stranded DNA translocation velocity by two orders of magnitude or more via interactions outside the nanopore. This is achieved by electrospinning a copolymer nanofiber mesh (NFM) directly onto a solid-state nanopore (NP) chip. The effect of NFMs on dsDNA translocation through a nanopore is highlighted using a set of NFMs of varying mesh composition that reduce translocation speed relative to a bare pore from 1× to >100×. A representative NFM from this set is effective on DNA as long as 20 kbp, improves nanopore resolution, and allows discrimination among different DNA lengths. PMID:24143914

Squires, Allison; Hersey, Joseph S.; Grinstaff, Mark W.; Meller, Amit

2014-01-01

185

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

186

The Cosmic Background Explorer.  

ERIC Educational Resources Information Center

Outlines the Cosmic Background Explorer (COBE) mission to measure celestial radiation. Describes the instruments used and experiments involving differential microwave radiometers, and a far infrared absolute spectrophotometer. (YP)

Gulkis, Samuel; And Others

1990-01-01

187

Comparative analysis of mitochondrial and amyloplast adenylate translocators.  

PubMed

Structurally intact and metabolically competent mitochondria isolated from liquid-culture cells of sycamore (Acer pseudoplatanus L.) were shown to incorporate ADPglucose. Employing the double silicone oil layer filtering centrifugation method, we examined the kinetic properties of the uptake of various adenylates as well as the inhibitory effects exerted by carboxyatractyloside, atractyloside and bongkrekic acid, known specific inhibitors of the mitochondrial adenylate translocator. Immunoblot patterns of peptides derived from the partial proteolytic digestion of the mitochondrial and plastid adenylate translocators were shown to be essentially the same. We conclude that the molecular entities engaged in the adenylate transport system operating in two different organelles, mitochondria and amyloplasts, are very similar. PMID:1879538

Pozueta-Romero, J; Viale, A M; Akazawa, T

1991-08-01

188

Free energy evaluation in polymer translocation via Jarzynski equality  

NASA Astrophysics Data System (ADS)

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.

Mondaini, Felipe; Moriconi, L.

2014-05-01

189

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

2014-04-21

190

Overwintering of Gopher Tortoises (Gopherus polyphemus) Translocated to the Northern Limit of Their Geographic Range: Temperatures, Timing, and Survival  

E-print Network

Overwintering of Gopher Tortoises (Gopherus polyphemus) Translocated to the Northern Limit in gopher tortoises (Gopherus polyphemus) translocated to the northern periphery of their geographic range WORDS. ­ Reptilia; Testudines; Testudinidae; thermal ecology; conservation; translocation; gopher

Georgia, University of

191

Background music reactive games  

Microsoft Academic Search

In this paper, we discuss the concept of games that react to their background music. Instead of limiting the player to a fixed set of songs, the background music can be any song chosen from the player's own music collection. Due to the relative simplicity of such existing game titles, we wanted to explore the potential of the concept more

Juha Arrasvuori; Jukka Holm

2010-01-01

192

Correlators in nontrivial backgrounds  

SciTech Connect

Operators in N=4 super Yang-Mills theory with an R-charge of O(N{sup 2}) are dual to backgrounds which are asymtotically AdS{sub 5}xS{sup 5}. In this article we develop efficient techniques that allow the computation of correlation functions in these backgrounds. We find that (i) contractions between fields in the string words and fields in the operator creating the background are the field theory accounting of the new geometry, (ii) correlation functions of probes in these backgrounds are given by the free field theory contractions but with rescaled propagators and (iii) in these backgrounds there are no open string excitations with their special end point interactions; we have only closed string excitations.

Mello Koch, Robert de [National Institute for Theoretical Physics, Department of Physics and Centre for Theoretical Physics, University of the Witwatersrand, Wits, 2050 (South Africa); Stellenbosch Institute for Advanced Studies, Stellenbosch (South Africa); Ives, Norman; Stephanou, Michael [National Institute for Theoretical Physics, Department of Physics and Centre for Theoretical Physics, University of the Witwatersrand, Wits, 2050 (South Africa)

2009-01-15

193

Combined Effects of Tauroursodeoxycholic Acid and Glutamine on Bacterial Translocation in Obstructive Jaundiced Rats:  

PubMed Central

Background: Bacterial Translocation is believed to be an important factor on mortality and morbidity in Obstructive Jaundiced. Aims: We investigated the probable or estimated positive effects of tauroursodeoxycholic acid, which has antibacterial and regulatory effects on intestinal flora, together with glutamine on BT in an experimental obstructive jaundiced rat model. Study Design: Animal experimentation. Methods: Forty adult, male, Sprague Dawley rats were used in this study. Animals were randomised and divided into five groups of eight each: sham (Sh); control (common bile duct ligation, CBDL); and supplementation groups administered tauroursodeoxycholic acid (CBDL+T), glutamine (CBDL+G), or tauroursodeoxycholic acid plus glutamine (CBDL+TG). Blood and liver, spleen, MLN, and ileal samples were taken via laparotomy under sterile conditions for investigation of bacterial translocation and intestinal mucosal integrity and hepatic function tests on the tenth postoperative day. Results: There were statistically significant differences in BT rates in all samples except the spleen of the CBDL+TG group compared with the CBDL group (p=0.041, p=0.026, and p=0.041, respectively). Conclusion: It is essential to protect hepatic functions besides maintaining intestinal mucosal integrity in the active struggle against BT occurring in obstructive jaundice. The positive effect on intestinal mucosal integrity can be increased if glutamine is used with tauroursodeoxycholic acid, which also has hepatoprotective and immunomodulatory features. PMID:25207142

Hatipo?lu, Ahmet Rahmi; O?uz, Serhat; Gürcan, ?aban; Yalta, Tülin; Albayrak, Do?an; Ereno?lu, Cengiz; Sa??ro?lu, Tamer; Sezer, Yavuz Atakan

2013-01-01

194

Translocation d'acides nucleiques au travers d'une bicouche lipidique : du nanopore au bacteriophage.  

E-print Network

??Ce travail porte sur l'étude expérimentale de deux mécanismes de translocations d'acides nucléiques au travers d'une membrane lipidique : la translocation, forcée électrophorétiquement, d'oligomères au… (more)

Chiaruttini, Nicolas

2010-01-01

195

The cosmic neutrino background  

NASA Technical Reports Server (NTRS)

The cosmic neutrino background is expected to consist of relic neutrinos from the big bang, of neutrinos produced during nuclear burning in stars, of neutrinos released by gravitational stellar collapse, and of neutrinos produced by cosmic ray interactions with matter and radiation in the interstellar and intergalactic medium. Formation of baryonic dark matter in the early universe, matter-antimatter annihilation in a baryonic symmetric universe, and dark matter annihilation could have also contributed significantly to the cosmic neutrino background. The purpose of this paper is to review the properties of these cosmic neutrino backgrounds, the indirect evidence for their existence, and the prospects for their detection.

Dar, Arnon

1991-01-01

196

Computer simulation study of fullerene translocation through lipid membranes  

Microsoft Academic Search

Recent toxicology studies suggest that nanosized aggregates of fullerene molecules can enter cells and alter their functions, and also cross the blood–brain barrier. However, the mechanisms by which fullerenes penetrate and disrupt cell membranes are still poorly understood. Here we use computer simulations to explore the translocation of fullerene clusters through a model lipid membrane and the effect of high

Jirasak Wong-Ekkabut; Svetlana Baoukina; Wannapong Triampo; I.-Ming Tang; D. Peter Tieleman; Luca Monticelli

2008-01-01

197

Single Molecule Fluorescence Measurements of Ribosomal Translocation Dynamics  

PubMed Central

We employ single-molecule fluorescence resonance energy transfer (smFRET) to study structural dynamics over the first two elongation cycles of protein synthesis, using ribosomes containing either Cy3-labeled ribosomal protein L11 and A- or P-site Cy5-labeled tRNA or Cy3 and Cy5 labeled tRNAs. Pre-translocation (PRE) complexes demonstrate fluctuations between classical and hybrid forms, with concerted motions of tRNAs away from L11 and from each other when classical complex converts to hybrid complex. EF-G·GTP binding to both hybrid and classical PRE complexes halts these fluctuations prior to catalyzing translocation to form the post-translocation (POST) complex. EF-G dependent translocation from the classical PRE complex proceeds via transient formation of a short-lived hybrid intermediate. A-site binding of either EF-G to the PRE complex or of aminoacyl-tRNA·EF-Tu ternary complex to the POST complex markedly suppresses ribosome conformational lability. PMID:21549313

Chen, Chunlai; Stevens, Benjamin; Kaur, Jaskarin; Cabral, Diana; Liu, Hanqing; Wang, Yuhong; Zhang, Haibo; Rosenblum, Gabriel; Smilansky, Zeev; Goldman, Yale E.; Cooperman, Barry S.

2011-01-01

198

Gene flow and endangered species translocations: a topic revisited  

Microsoft Academic Search

Understanding the evolutionary role of gene flow is pivotal to the conservation of endangered populations. Gene flow can be enhanced through population translocations that are conducted to maintain genetic variation and combat the negative consequences of inbreeding depression (two of the major concerns in the conservation of subdivided or isolated populations). While researchers have given extensive consideration to the idea

Andrew Storfer

1999-01-01

199

Translocation and Absorption of Glyphosate in Flowering Sicklepod (Senna obtusifolia)  

Technology Transfer Automated Retrieval System (TEKTRAN)

Sicklepod is a competitive and prolific weed that emerges throughout the crop season. Glyphosate applications at sicklepod flowering have been shown to greatly reduce seed production, although there is limited information on glyphosate translocation in flowering weeds. Therefore, a laboratory stud...

200

DNA Translocation through a Peridically Patterned Pyramidal Probe  

NASA Astrophysics Data System (ADS)

The Al nanoapertures surrounded by periodic patterns on the pyramid were fabricated. The nanosize aperture surrounded by equidistant elliptic groove patterns presented greater transmission than the aperture with circular groove patterns. The translocation of ?-DNA through these fabricated nanostructures was examined.

Choi, Seong Soo; Park, Myoung Jin; Kyoo Park, Nam; Park, Seung Min; Lee, Luke

2013-03-01

201

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

202

Diphtheria toxin translocation across cellular membranes is regulated by sphingolipids  

SciTech Connect

Diphtheria toxin is translocated across cellular membranes when receptor-bound toxin is exposed to low pH. To study the role of sphingolipids for toxin translocation, both a mutant cell line lacking the first enzyme in de novo sphingolipid synthesis, serine palmitoyltransferase, and a specific inhibitor of the same enzyme, myriocin, were used. The serine palmitoyltransferase-deficient cell line (LY-B) was found to be 10-15 times more sensitive to diphtheria toxin than the genetically complemented cell line (LY-B/cLCB1) and the wild-type cell line (CHO-K1), both when toxin translocation directly across the plasma membrane was induced by exposing cells with surface-bound toxin to low pH, and when the toxin followed its normal route via acidified endosomes into the cytosol. Toxin binding was similar in these three cell lines. Furthermore, inhibition of serine palmitoyltransferase activity by addition of myriocin sensitized the two control cell lines (LY-B/cLCB1 and CHO-K1) to diphtheria toxin, whereas, as expected, no effect was observed in cells lacking serine palmitoyltransferase (LY-B). In conclusion, diphtheria toxin translocation is facilitated by depletion of membrane sphingolipids.

Spilsberg, Bjorn [Institute for Cancer Research, The Norwegian Radium Hospital, Montebello, N-0310 Oslo (Norway); Hanada, Kentaro [Department of Biochemistry and Cell Biology, National Institute of Infectious Diseases, 1-23-1, Toyama, Shinjuku-ku, Tokyo 162-8640 (Japan); Sandvig, Kirsten [Institute for Cancer Research, The Norwegian Radium Hospital, Montebello, N-0310 Oslo (Norway)]. E-mail: ksandvig@radium.uio.no

2005-04-08

203

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

204

PROTOCOLS FOR SUCCESSFUL TRANSLOCATION OF PTARMIGAN CLAIT E. BRAUN1  

E-print Network

E. EBBERT3 , ROBB S. A. KALER4,5 , AND BRETT K. SANDERCOCK4 1 Grouse Inc., 5572 North Ventana Vista for future translocation of ptarmigan and other grouse. Received 31 December 2010, accepted 21 June 2011.4080/gpcw.2011.0313 Key words: Alaska, California, Colorado, New Mexico, Oregon, Utah, grouse, ptarmigan

Sandercock, Brett K.

205

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, Andrés; Blanco, Luis

2013-01-01

206

Dynamics of DNA translocation through an attractive nanopore  

E-print Network

We investigate the dynamics of DNA translocation through a nanopore driven by an external force using Langevin dynamics simulations in two dimensions (2D) to study how the translocation dynamics depend on the details of the DNA sequences. We consider a coarse-grained model of DNA built from two bases $A$ and $C$, having different base-pore interactions, {\\textit e.g.}, a strong (weak) attractive force between the pore and the base $A$ ($C$) inside the pore. From a series of studies on hetero-DNAs with repeat units $A_mC_n$, we find that the translocation time decreases exponentially as a function of the volume fraction $f_C$ of the base $C$. %($\\epsilon_{pC} < \\epsilon_{pA}$). For longer $A$ sequences with $f_C \\le 0.5$, the translocation time strongly depends on the orientation of DNA, namely which base enters the pore first. Our studies clearly demonstrate that for a DNA of certain length $N$ with repeat units $A_mC_n$, the pattern exhibited by the waiting times of the individual bases and their periodicity can unambiguously determine the values of $m$, $n$ and $N$ respectively. Therefore, a prospective experimental realization of this phenomenon may lead to fast and efficient sequence detection technic.

Kaifu Luo; Tapio Ala-Nissila; See-Chen Ying; Aniket Bhattacharya

2008-10-16

207

Kinetics of RNA translocation through a nanopore Ralf Bundschuh  

E-print Network

Kinetics of RNA translocation through a nanopore Ralf Bundschuh The Ohio State University Collaborator: Ulrich Gerland, LMU M¨unchen Outline: · Introduction to RNA and nanopores · Limiting cases - very RNA folding kinetics very complex · Nanopore experiments ideal because time scale is set by experiment

Bundschuh, Ralf

208

Translocation Dynamics with Attractive Nanopore-Polymer Interactions  

E-print Network

Using Langevin dynamics simulations, we investigate the influence of polymer-pore interactions on the dynamics of biopolymer translocation through nanopores. We find that an attractive interaction can significantly change the translocation dynamics. This can be understood by examining the three components of the total translocation time $\\tau \\approx \\tau_1+\\tau_2+\\tau_3$ corresponding to the initial filling of the pore, transfer of polymer from the \\textit{cis} side to the \\textit{trans} side, and emptying of the pore, respectively. We find that the dynamics for the last process of emptying of the pore changes from non-activated to activated in nature as the strength of the attractive interaction increases, and $\\tau_3$ becomes the dominant contribution to the total translocation time for strong attraction. This leads to a new dependence of $\\tau$ as a function of driving force and chain length. Our results are in good agreement with recent experimental findings, and provide a possible explanation for the different scaling behavior observed in solid state nanopores {\\it vs.} that for the natural $\\alpha$-hemolysin channel.

Kaifu Luo; Tapio Ala-Nissila; See-Chen Ying; Aniket Bhattacharya

2008-05-28

209

Soil translocation by pocket gophers in a Mima moundfield  

Microsoft Academic Search

We measured soil translocation due to the tunneling of valley pocket gophers (Thomomys bottae) in a Mima moundfield at Miramar Mounds National Landmark, San Diego, California, from December, 1984 through December, 1985. We placed 1-l soil plugs containing 20 11-g iron pellets into pocket gopher tunnels at locations between mound tops and points about one mound radius beyond mound edges.

G. W. Cox; D. W. Allen

1987-01-01

210

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

211

The trisomy 18 syndrome with an E\\/G translocation  

Microsoft Academic Search

An infant with a typical Edwards syndrome and a modal chromosome number of 46 is reported. In all cells analyzed one chromosome G was missing and an additional chromosome similar to a pair No. 16 was present. The phenotype of the child indicates that the extra element is a translocation between G and 18 chromosomes as in one case described

Danuta Dziekanowska; P. Dziuba; T. Sobafiski

1976-01-01

212

Factors Influencing Success of Greenback Cutthroat Trout Translocations  

Microsoft Academic Search

Native subspecies of cutthroat trout Oncorhynchus clarki have declined drastically because of the introduction of nonnative salmonids, overharvesting, and habitat degradation. Con- servation of most declining subspecies will include establishing new populations through trans- location of genetically pure fish. Recovery of greenback cutthroat trout O. clarki stomias has been ongoing for 25 years, so the attempted translocations of this subspecies

Amy L. Harig; Kurt D. Fausch; Michael K. Young

2000-01-01

213

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

214

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 these fusions translocated the AvrBs2 reporter in a TTSS-dependent manner into resistant BS2 pepper cells during repeat and is required for full Xcv pathogenicity in pepper and tomato. The translocated effectors

Mudgettt, Mary Beth

215

Dynamics of initiation, termination and reinitiation of DNA translocation by the motor protein  

E-print Network

unit of the enzyme loads the motor subunits onto adjacent DNA by allowing them to bind and initiate translocation. Termination of translocation occurs owing to dissociation of the motors from the core unitDynamics of initiation, termination and reinitiation of DNA translocation by the motor protein Eco

Dekker, Nynke

216

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

217

Mating system in a gopher tortoise population established through multiple translocations: Apparent advantage of prior residence  

E-print Network

Mating system in a gopher tortoise population established through multiple translocations: Apparent, and reproduction. We investigated the mating system of a translocated population of gopher tortoises (Gopherus in this gopher tortoise population has important implications for the design of future translocation projects. Ã?

Georgia, University of

218

ERK Nuclear Translocation Is Dimerization-independent but Controlled by the Rate of Phosphorylation*S  

E-print Network

ERK Nuclear Translocation Is Dimerization-independent but Controlled by the Rate of Phosphorylation, Universite´ de Nice, Centre A. Lacassagne, 06189 Nice, France Upon activation, ERKs translocate from the molecular mechanisms that regulate ERK nuclear translocation are not fully understood. We have used a mouse

Rieger, Bernd

219

Initiation of translocation by Type I restriction-modification enzymes is associated with a  

E-print Network

Initiation of translocation by Type I restriction- modification enzymes is associated with a short involves DNA translocation by the restriction subunit HsdR. Type I R-M enzymes are composed of three (Hsd the recognition-translocation switch of Type I restriction enzymes forms an important first step in resolving

Dekker, Cees

220

The GLAST Background Model  

NASA Astrophysics Data System (ADS)

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.; Atwood, W.; Burnett, T.; Grove, E.; Longo, F.; McEnery, J.; Mizuno, T.; Ritz, S.

2007-07-01

221

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

222

IR-background database  

Microsoft Academic Search

The Swedish Defence Research Agency (FOI) has recently performed systematic measurements in order to establish an IR-background database. It will be used for a wide range of applications and provide a basis for the modeling of IR-background properties of Swedish terrain. Experimental data like this is also necessary for the validation of methods and programs for synthetic IR-scene simulation. The

Claes Nelsson; Paer Nilsson; Roland Lindell; Emma Bernhardsson

2001-01-01

223

Effects of Mitochondrial Translocation of Telomerase on Drug Resistance in Hepatocellular Carcinoma Cells  

PubMed Central

Hepatocellular carcinoma (HCC) cells exhibit multidrug resistance (MDR), but the underlying mechanisms remain unclear. Cancer cells that overexpress telomerase are resistant to chemotherapeutic drugs. This study aimed to determine the effects of mitochondrial translocation of telomerase on MDR in HCC cells. HepG2 cells were transfected with negative plasmid and PTPN11 (Shp-2) short hairpin RNA (ShRNA) plasmid to establish HepG2-negative (HepG2 transfected with negative plasmid) and HepG2-ShShp-2 (HepG2 transfected with Shp-2 ShRNA plasmid) cells. Sensitivity to chemotherapeutic drugs was assessed by Cell Counting Kit-8 (CCK-8) assays. Distribution of human telomerase reverse transcriptase (hTERT) within mitochondria was detected by western blotting and immunofluorescence combined with laser scanning confocal microscopy. Mitochondrial reactive oxygen species (ROS) generation was demonstrated by flow cytometry with the mitochondrial superoxide (Mito-Sox) indicator. The frequency of damaged mitochondrial DNA (mtDNA) was illustrated by quantitative real-time polymerase chain reaction (Q-PCR). Expression of mitochondrial respiratory chain complex subunits ND1 and COXII were also demonstrated by western blotting. Knockdown of Shp-2 in HepG2 cells resulted in upregulation of mitochondrial TERT expression and increased resistance to cisplatin (CDDP) and 5-fluorouracil (5-FU) (resistance indices, 2.094 and 1.863, respectively). In addition, both the mitochondrial ROS and the frequency of mtDNA damage were decreased, and COXII expression was upregulated. Our results suggest that Mitochondrial translocation of hTERT may lead to chemotherapeutic resistance in HCC cells. Mitochondrial hTERT contributes to the drug resistance of tumor cells by reducing ROS production and mtDNA damage, and exerting a protective effect on the mitochondrial respiratory chain. PMID:25561980

Yan, Jing; Zhou, Yuan; Chen, DaiXing; Li, LiLi; Yang, Xin; You, Yang; Ling, Xianlong

2015-01-01

224

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

225

ADP/ATP Translocator from Pea Root Plastids (Comparison with Translocators from Spinach Chloroplasts and Pea Leaf Mitochondria).  

PubMed

The kinetic properties of the adenosine 5[prime]-diphosphate/adenosine 5[prime]-triphosphate (ADP/ATP) translocator from pea (Pisum sativum L.) root plastids were determined by silicone oil filtering centrifugation and compared with those of spinach (Spinacia oleracea L.) chloroplasts and pea leaf mitochondria. In addition, the ADP/ATP transporting activities from the above organelles were reconstituted into liposomes. The Km(ATP) value of the pea root ADP/ATP translocator was 10 [mu]M and that for ADP was 46 [mu]M. Corresponding values of the spinach ADP/ATP translocator were 25 [mu]M and 28 [mu]M, respectively. Comparable results were obtained for the reconstituted ATP transport activities. The transport was highly specific for ATP and ADP. Adenosine 5[prime]-monophosphate (AMP) caused only a slight inhibition and phosphoenolpyruvate and inorganic pyrophosphate caused no inhibition of ATP uptake. With pea root plastids and spinach chloroplasts, Km values >1 mM were obtained for ADP-glucose. Since the concentrations of ATP and ADP-glucose in the cytosolic compartment of spinach leaves have been determined as 2.5 and 0.6 mM, respectively, a transport of ADP-glucose by the ADP/ATP translocator does not appear to have any physiological significance in vivo. Although both the plastidial and the mitochondrial ADP/ATP translocators were inhibited to some extent by carboxyatractyloside, no immunological cross-reactivity was detected between the plastidial and the mitochondrial proteins. It seems probable that these proteins derive from different ancestors. PMID:12231920

Schunemann, D.; Borchert, S.; Flugge, U. I.; Heldt, H. W.

1993-09-01

226

Two cases of Y; autosome translocations: A 45,X male and a clinically trisomy 18 patient  

SciTech Connect

The authors report on 2 cases of Y; autosome translocations. One is a male with normal external genitalia and 45,X karyotype without evidence of mosaicism or apparent translocation on cytogenetic analysis. In situ hybridization showed that the euchromatic portion of the Y-chromosome is translocated to chromosome 15. The other case is a clinically trisomy 18 male patient, with modal number of 46, a small metacentric marker with appearance of an i(18p) and cytogenic and molecular evidence of Y;18 translocation. The occurrence of Y;18 translocation associated with clinical signs of trisomy 18 is reported here for the first time. 32 refs., 2 figs., 1 tab.

Farah, S.B.; Ramos, C.F.; Mello, M.P. de; Sartorato, E.L.; Lopes, V.L.G.S.; Cavalcanti, D.P.; Hackel, C. [Universidade Estadual de Campinas, SP (Brazil); Horeilli-Kuitunen, N. [Univ. of Helsinki (Finland)

1994-02-15

227

Cosmic Microwave Background  

NSDL National Science Digital Library

In this lesson, students explore the cosmic microwave background to understand why it permeates the universe and why it peaks as microwave radiation. Students should be able to explain that the origin of the background radiation is the uniform thermal radiation of the big bang and that the radiation produced was evenly distributed around the small early universe, causing it to permeate today's universe. This activity is part of the Cosmic Times teachers guide and is intended to be used in conjunction with the 1965 Cosmic Times Poster.

228

The Cosmic Background Explorer  

NASA Technical Reports Server (NTRS)

The Cosmic Background Explorer (CBE), NASA's cosmological satellite which will observe a radiative relic of the big bang, is discussed. The major questions connected to the big bang theory which may be clarified using the CBE are reviewed. The satellite instruments and experiments are described, including the Differential Microwave Radiometer, which measures the difference between microwave radiation emitted from two points on the sky, the Far-Infrared Absolute Spectrophotometer, which compares the spectrum of radiation from the sky at wavelengths from 100 microns to one cm with that from an internal blackbody, and the Diffuse Infrared Background Experiment, which searches for the radiation from the earliest generation of stars.

Gulkis, Samuel; Lubin, Philip M.; Meyer, Stephan S.; Silverberg, Robert F.

1990-01-01

229

The cosmic microwave background  

NASA Technical Reports Server (NTRS)

Recent limits on spectral distortions and angular anisotropies in the cosmic microwave background are reviewed. The various backgrounds are described, and the theoretical implications are assessed. Constraints on inflationary cosmology dominated by cold dark matter (CDM) and on open cosmological models dominated by baryonic dark matter (BDM), with, respectively, primordial random phase scale-invariant curvature fluctuations or non-gaussian isocurvature fluctuations are described. More exotic theories are addressed, and I conclude with the 'bottom line': what theorists expect experimentalists to be measuring within the next two to three years without having to abandon their most cherished theories.

Silk, Joseph

1991-01-01

230

Gq-mediated Akt translocation to the membrane: a novel PIP3-independent mechanism in platelets.  

PubMed

Akt is an important signaling molecule regulating platelet aggregation. Akt is phosphorylated after translocation to the membrane through Gi signaling pathways by a phosphatidylinositol-3,4,5-trisphosphate (PIP3)-dependent mechanism. However, Akt is more robustly phosphorylated by thrombin compared with adenosine 5'-diphosphate in platelets. This study investigated the mechanisms of Akt translocation as a possible explanation for this difference. Stimulation of washed human platelets with protease-activated receptor agonists caused translocation of Akt to the membrane rapidly, whereas phosphorylation occurred later. The translocation of Akt was abolished in the presence of a Gq-selective inhibitor or in Gq-deficient murine platelets, indicating that Akt translocation is regulated downstream of Gq pathways. Interestingly, phosphatidylinositol 3-kinase (PI3K) inhibitors or P2Y12 antagonist abolished Akt phosphorylation without affecting Akt translocation to the membrane, suggesting that Akt translocation occurs through a PI3K/PIP3/Gi-independent mechanism. An Akt scaffolding protein, p21-activated kinase (PAK), translocates to the membrane after stimulation with protease-activated receptor agonists in a Gq-dependent manner, with the kinetics of translocation similar to that of Akt. Coimmunoprecipitation studies showed constitutive association of PAK and Akt, suggesting a possible role of PAK in Akt translocation. These results show, for the first time, an important role of the Gq pathway in mediating Akt translocation to the membrane in a novel Gi/PI3K/PIP3-independent mechanism. PMID:25331114

Badolia, Rachit; Manne, Bhanu Kanth; Dangelmaier, Carol; Chernoff, Jonathan; Kunapuli, Satya P

2015-01-01

231

Translocation of alkane through graphene nanopore: A molecular dynamics simulation study  

NASA Astrophysics Data System (ADS)

The process of molecules translocation through nanopore is important to understand many interesting phenomena. Molecular dynamics simulations have been carried out to study the translocation of alkane through graphene nanopore. The results detail relative distance, average translation time, etc. The translocation process can be divided into three stages: finding-entering-moving through the nanopore. Alkane must climb an energy barrier in every stage. The dependence of translocation on chain length is also discussed. Shorter alkanes are easy to transport through the nanopore and the average translocation time is short when alkane translocates through nanopore one by one. Our simulations show a visualized translocation process, which can favor our understanding of this important process.

Li, Jun-Yin; Yang, Hua; Sheng, Yan-Zhen; Zhao, Xin-Ting; Sun, Miao

2015-02-01

232

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

233

Radioactive Decay 1. Background  

E-print Network

Radioactive Decay 1. Background It is well known that many nuclei are unstable and are transformed into other nuclear species by means of either alpha decay or beta decay. The rate at which those radioactive on the number N of radioactive nuclei in the sample and also on the probability for each nucleus to decay

Elster, Charlotte

234

Country background Forest history  

E-print Network

33 Country background Forest history During the Gallo-Roman period (1st­4th century AD), forests this proportion decreased dramatically to only 15­17 % of the land area. This residual forest was then severely Colbert's Forest Ordinance was instituted in 1669 a gradual restoration took place. High forests produced

Paris-Sud XI, Université de

235

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

236

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

237

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 Soares

2014-11-13

238

A complicated translocation involving five chromosomes (Nos. 9, 11, 12, 21 and 22) in a patient with chronic myelocytic leukemia (CML).  

PubMed

A new complicated Ph1 translocation involving five chromosomes, t(9;22;21;11;inv ins(12)-(q15p12p13))(q34;q11;q22;q13;q15), was found in a 64-year-old Korean woman with chronic myelocytic leukemia (CML). At presentation, the patient was found to be in the accelerated phase, she entered the chronic phase after six cycles of chemotherapy including a vincristine (VCR) and prednisolone (PSL) regimen (VP). The chronic phase continued for 2 years, and 33 months after her first admission she died due to severe pneumonia and congestive heart failure in the re-accelerated phase. In the literature, the frequency of the involvement of chromosome No. 11 in three-way Ph1 translocations (4.9%) is lower than that in four- and five-way Ph1 translocations (33.3%). It may be worth noting that chromosome No. 11 is easily involved in highly complicated Ph1 translocations. PMID:1793830

Abe, R; Shiga, Y; Ookoshi, T; Tanaka, T; Maruyama, Y

1991-12-01

239

Poison Domains Block Transit of Translocated Substrates via the Legionella pneumophila Icm/Dot System  

PubMed Central

Legionella pneumophila uses the Icm/Dot type 4B secretion system (T4BSS) to deliver translocated protein substrates to the host cell, promoting replication vacuole formation. The conformational state of the translocated substrates within the bacterial cell is unknown, so we sought to determine if folded substrates could be translocated via this system. Fusions of L. pneumophila Icm/Dot-translocated substrates (IDTS) to dihydrofolate reductase (DHFR) or ubiquitin (Ub), small proteins known to fold rapidly, resulted in proteins with low translocation efficiencies. The folded moieties did not cause increased aggregation of the IDTS and did not impede interaction with the adaptor protein complex IcmS/IcmW, which is thought to form a soluble complex that promotes translocation. The translocation defect was alleviated with a Ub moiety harboring mutations known to destabilize its structure, indicating that unfolded proteins are preferred substrates. Real-time analysis of translocation, following movement during the first 30 min after bacterial contact with host cells, revealed that the folded moiety caused a kinetic defect in IDTS translocation. Expression of an IDTS fused to a folded moiety interfered with the translocation of other IDTS, consistent with it causing a blockage of the translocation channel. Furthermore, the folded protein fusions also interfered with intracellular growth, consistent with inefficient or impaired translocation of proteins critical for L. pneumophila intracellular growth. These studies indicate that substrates of the Icm/Dot T4SS are translocated to the host cytosol in an unfolded conformation and that folded proteins are stalled within the translocation channel, impairing the function of the secretion system. PMID:23798536

Amyot, Whitney M.; deJesus, Dennise

2013-01-01

240

Dynamics of RhoA and ROKalpha translocation in single living cells.  

PubMed

The RhoA-binding kinase (ROK) is one of the target kinases of RhoA and is known to play a critical role in regulating cytoskeletal rearrangement in cells. ROK translocates to the plasma membrane fraction; however, the mechanism of the translocation of ROK still remains obscure. To clarify the molecular mechanisms of the translocation of ROK, we co-transfected MDCK cells with cyan fluorescent protein-tagged RhoA and yellow fluorescent protein-tagged ROKalpha, or their variants, and monitored the localization and translocation of the two different fluorescent tagged-molecules in single living cells during epithelial growth factor (EGF) stimulation. Both RhoA (wild-type) and ROKalpha (wild-type) translocated to ruffling membrane with EGF stimulation in several minutes. A ROKalpha mutant, in which Rho-binding ability is disrupted, is unable to translocate to the membrane with RhoA. However, RhoA mutant Q63L/C190R, an active form lacking membrane localization activity, abolished the translocation of wild-type ROKalpha, suggesting that the translocation of RhoA is critical for ROK translocation to the membrane. Another mutant lacking the pleckstrin homology domain failed in translocation as well. On the other hand, it was surprising that the kinase dead mutant succeeded in translocation to the membrane after EGF stimulation. Based on these results, we propose the following ROKalpha translocation mechanism. ROKalpha binds to RhoA in cytosol and translocates to the membrane based on the membrane-targeting ability of active RhoA. After ROKalpha associates with the membrane, the pleckstrin homology domain provides the stability of ROKalpha on the membrane. The activation of enzymatic activity or adenosine triphosphate binding, however, is not directly related to the translocation mechanism, although we found that the membrane association is critical for the activation of the kinase activity. PMID:16845171

Miyazaki, Koji; Komatsu, Satoshi; Ikebe, Mitsuo

2006-01-01

241

Markov chain modeling of polymer translocation through pores.  

PubMed

We solve the Chapman-Kolmogorov equation and study the exact splitting probabilities of the general stochastic process which describes polymer translocation through membrane pores within the broad class of Markov chains. Transition probabilities, which satisfy a specific balance constraint, provide a refinement of the Chuang-Kantor-Kardar relaxation picture of translocation, allowing us to investigate finite size effects in the evaluation of dynamical scaling exponents. We find that (i) previous Langevin simulation results can be recovered only if corrections to the polymer mobility exponent are taken into account and (ii) the dynamical scaling exponents have a slow approach to their predicted asymptotic values as the polymer's length increases. We also address, along with strong support from additional numerical simulations, a critical discussion which points in a clear way the viability of the Markov chain approach put forward in this work. PMID:21950882

Mondaini, Felipe; Moriconi, L

2011-09-21

242

Slowing down DNA translocation through a nanopore in lithium chloride  

PubMed Central

The charge of a DNA molecule is a crucial parameter in many DNA detection and manipulation schemes such as gel electrophoresis and lab-on-a-chip applications. Here, we study the partial reduction of the DNA charge due to counterion binding by means of nanopore translocation experiments and all-atom molecular dynamics (MD) simulations. Surprisingly, we find that the translocation time of a DNA molecule through a solid-state nanopore strongly increases as the counterions decrease in size from K+ to Na+ to Li+, both for double-stranded DNA (dsDNA) and single-stranded DNA (ssDNA). MD simulations elucidate the microscopic origin of this effect: Li+ and Na+ bind DNA stronger than K+. These fundamental insights into the counterion binding to DNA also provide a practical method for achieving at least ten-fold enhanced resolution in nanopore applications. PMID:22229707

Kowalczyk, Stefan W.; Wells, David B.; Aksimentiev, Aleksei; Dekker, Cees

2012-01-01

243

A Novel Mode of Translocation for Cytolethal Distending Toxin  

PubMed Central

Summary Thermal instability in the toxin catalytic subunit may be a common property of toxins that exit the endoplasmic reticulum (ER) by exploiting the mechanism of ER-associated degradation (ERAD). The Haemophilus ducreyi cytolethal distending toxin (HdCDT) does not utilize ERAD to exit the ER, so we predicted the structural properties of its catalytic subunit (HdCdtB) would differ from other ER-translocating toxins. Here, we document the heat-stable properties of HdCdtB which distinguish it from other ER-translocating toxins. Cell-based assays further suggested that HdCdtB does not unfold before exiting the ER and that it may move directly from the ER lumen to the nucleoplasm. These observations suggest a novel mode of ER exit for HdCdtB. PMID:19118582

Guerra, Lina; Nemec, Kathleen N.; Massey, Shane; Tatulian, Suren A.; Thelestam, Monica; Frisan, Teresa; Teter, Ken

2008-01-01

244

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

245

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

246

Dynamical Scaling Exponents for Polymer Translocation through a Nanopore  

E-print Network

We determine the scaling exponents of polymer translocation (PT) through a nanopore by extensive computer simulations of various microscopic models for chain lengths extending up to N=800 in some cases. We focus on the scaling of the average PT time $\\tau \\sim N^{\\alpha}$ and the mean-square change of the PT coordinate $ \\sim t^\\beta$. We find $\\alpha=1+2\

Kaifu Luo; Santtu T. T. Ollila; Ilkka Huopaniemi; Tapio Ala-Nissila; Pawel Pomorski; Mikko Karttunen; See-Chen Ying; Aniket Bhattacharya

2008-05-28

247

Microscopic Kinetics of DNA Translocation through Synthetic Nanopores  

Microsoft Academic Search

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

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

2004-01-01

248

Patch-clamp detection of macromolecular translocation along nuclear pores  

Microsoft Academic Search

The present paper reviews the application of patch-clamp principles to the detection and measurement of macromolecular translocation along the nuclear pores. We demonstrate that the tight-seal 'gigaseal' be- tween the pipette tip and the nuclear membrane is possible in the presence of fully operational nuclear pores. We show that the ability to form a gigaseal in nucleus-attached configurations does not

J. O. Bustamante; W. A. Varanda

1998-01-01

249

Human gene mapping using an X\\/autosome translocation  

Microsoft Academic Search

Human fibroblasts containing a translocation between the X chromosome and chromosome 15 were fused with the 6-thioguanine-resistant mouse cell line, IR. Resulting hybrids, selected in HAT medium, retained the X\\/15 chromosome. Hybrids which were counterselected in 6-thioguanine lost this chromosome. The X-linked markers glucose-6-phosphate dehydrogenase (G6PD), phosphoglycerate kinase (PGK), and hypoxanthine phosphoribosyl transferase (HPRT), and the non-X-linked markers pyruvate kinase

E. Solomon; M. Bobrow; P. N. Goodfellow; W. F. Bodmer; D. M. Swallow; S. Povey; B. Noël

1976-01-01

250

Kinetic and thermodynamic aspects of lipid translocation in biological membranes.  

PubMed Central

A theoretical analysis of the lipid translocation in cellular bilayer membranes is presented. We focus on an integrative model of active and passive transport processes determining the asymmetrical distribution of the major lipid components between the monolayers. The active translocation of the aminophospholipids phosphatidylserine and phosphatidylethanolamine is mathematically described by kinetic equations resulting from a realistic ATP-dependent transport mechanism. Concerning the passive transport of the aminophospholipids as well as of phosphatidylcholine, sphingomyelin, and cholesterol, two different approaches are used. The first treatment makes use of thermodynamic flux-force relationships. Relevant forces are transversal concentration differences of the lipids as well as differences in the mechanical states of the monolayers due to lateral compressions. Both forces, originating primarily from the operation of an aminophospholipid translocase, are expressed as functions of the lipid compositions of the two monolayers. In the case of mechanical forces, lipid-specific parameters such as different molecular surface areas and compression force constants are taken into account. Using invariance principles, it is shown how the phenomenological coefficients depend on the total lipid amounts. In a second approach, passive transport is analyzed in terms of kinetic mechanisms of carrier-mediated translocation, where mechanical effects are incorporated into the translocation rate constants. The thermodynamic as well as the kinetic approach are applied to simulate the time-dependent redistribution of the lipid components in human red blood cells. In the thermodynamic model the steady-state asymmetrical lipid distribution of erythrocyte membranes is simulated well under certain parameter restrictions: 1) the time scales of uncoupled passive transbilayer movement must be different among the lipid species; 2) positive cross-couplings of the passive lipid fluxes are needed, which, however, may be chosen lipid-unspecifically. A comparison of the thermodynamic and the kinetic approaches reveals that antiport mechanisms for passive lipid movements may be excluded. Simulations with kinetic symport mechanisms are in qualitative agreement with experimental data but show discrepancies in the asymmetrical distribution for sphingomyelin. PMID:10049313

Frickenhaus, S; Heinrich, R

1999-01-01

251

Evaluation of collared peccary translocations in the Texas Hill Country  

E-print Network

) found that soft releases of black bear (Ursus americanus) also increased survival in a restoration program in Kentucky and Tennessee. My data also suggests that family structure of translocated individuals is an important factor in the success... beaver (Castor canadensis) (Rothmeyer et al. 2002), black bear (Ursus americanus) (Lee and Vaughan 2004), and grizzly bear (Ursus arctos) (Servheen et al. 1981, Garshelis et al. 2005). The effectiveness of ear tag transmitters on collared peccaries...

Porter, Brad Alan

2007-09-17

252

Sec61?, a subunit of the Sec61 protein translocation channel at the Endoplasmic Reticulum, is involved in the transport of Gurken to the plasma membrane.  

PubMed Central

Background Protein translocation across the membrane of the Endoplasmic Reticulum (ER) is the first step in the biogenesis of secretory and membrane proteins. Proteins enter the ER by the Sec61 translocon, a proteinaceous channel composed of three subunits, ?, ? and ?. While it is known that Sec61? forms the actual channel, the function of the other two subunits remains to be characterized. Results In the present study we have investigated the function of Sec61? in Drosophila melanogaster. We describe its role in the plasma membrane traffic of Gurken, the ligand for the Epidermal Growth Factor (EGF) receptor in the oocyte. Germline clones of the mutant allele of Sec61? show normal translocation of Gurken into the ER and transport to the Golgi complex, but further traffic to the plasma membrane is impeded. The defect in plasma membrane traffic due to absence of Sec61? is specific for Gurken and is not due to a general trafficking defect. Conclusion Based on our study we conclude that Sec61?, which is part of the ER protein translocation channel affects a post-ER step during Gurken trafficking to the plasma membrane. We propose an additional role of Sec61? beyond protein translocation into the ER. PMID:19226464

Kelkar, Anshuman; Dobberstein, Bernhard

2009-01-01

253

Traumatic ulnar translocation of the carpus: early recognition and treatment.  

PubMed

This study evaluated the clinical outcomes and radiographic features of surgically treated traumatic ulnocarpal translocation in nine patients (ten cases). All ligament and fracture repairs were completed within 2 months of injury. Seven cases were examined at a mean of 6.5 years, and information in three cases was obtained from medical records at a mean of 13 months after injury. At final evaluation, the mean disabilities of the arm, shoulder, and hand score was 6 (range, 0-16), and the mean Mayo modified wrist score was 76 (range, 40-100). Ulnocarpal translocation was evident in nine of the injured wrists, six of which showed arthritis, and in four of the uninjured wrists. Ulnar variance measured negative in nine cases and neutral in one case. Pre-existing medial alignment of the carpus and ulnar minus variance may predispose to traumatic ulnocarpal translocation. Early injury repair does not assure restoration of radiocarpal alignment or prevent joint deterioration; however, these changes do not always portend a suboptimal result. PMID:22357328

Berschback, J C; Kalainov, D M; Husain, S N; Wiedrich, T A; Cohen, M S; Nagle, D J

2012-10-01

254

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

255

Coliphage HK022 Nun protein inhibits RNA polymerase translocation  

PubMed Central

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

2014-01-01

256

Smooth muscle-protein translocation and tissue function.  

PubMed

Smooth muscle (SM) tissue is a complex organization of multiple cell types and is regulated by numerous signaling molecules (neurotransmitters, hormones, cytokines, etc.). SM contractile function can be regulated via expression and distribution of the contractile and cytoskeletal proteins, and activation of any of the second messenger pathways that regulate them. Spatial-temporal changes in the contractile, cytoskeletal or regulatory components of SM cells (SMCs) have been proposed to alter SM contractile activity. Ca(2+) sensitization/desensitization can occur as a result of changes at any of these levels, and specific pathways have been identified at all of these levels. Understanding when and how proteins can translocate within the cytoplasm, or to-and-from the plasmalemma and the cytoplasm to alter contractile activity is critical. Numerous studies have reported translocation of proteins associated with the adherens junction and G protein-coupled receptor activation pathways in isolated SMC systems. Specific examples of translocation of vinculin to and from the adherens junction and protein kinase C (PKC) and 17 kDa PKC-potentiated inhibitor of myosin light chain phosphatase (CPI-17) to and from the plasmalemma in isolated SMC systems but not in intact SM tissues are discussed. Using both isolated SMC systems and SM tissues in parallel to pursue these studies will advance our understanding of both the role and mechanism of these pathways as well as their possible significance for Ca(2+) sensitization in intact SM tissues and organ systems. PMID:25125185

Eddinger, Thomas J

2014-09-01

257

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

258

Aminoglycoside activity observed on single pre-translocation ribosome complexes  

PubMed Central

Aminoglycoside-class antibiotics bind directly to ribosomal RNA, imparting pleiotropic effects on ribosome function. Despite in-depth structural investigations of aminoglycoside–RNA oligonucleotide and aminoglycoside-ribosome interactions, mechanisms explaining the unique ribosome inhibition profiles of chemically similar aminoglycosides remain elusive. Here, using single-molecule fluorescence resonance energy transfer (smFRET) methods, we show that high-affinity aminoglycoside binding to the conserved decoding site region of the functional pre-translocation ribosome complex specifically remodels the nature of intrinsic dynamic processes within the particle. The extents of these effects, which are distinct for each member of the aminoglycoside class, strongly correlate with their inhibition of EF-G–catalyzed translocation. Neomycin, a 4,5-linked amino-glycoside, binds with lower affinity to one or more secondary binding sites, mediating distinct structural and dynamic perturbations that further enhance translocation inhibition. These new insights help explain why closely related aminoglycosides elicit pleiotropic translation activities and demonstrate the potential utility of smFRET as a tool for dissecting the mechanisms of antibiotic action. PMID:19946275

Feldman, Michael B; Terry, Daniel S; Altman, Roger B; Blanchard, Scott C

2010-01-01

259

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

260

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

2014-10-10

261

DNA translocation through nanopores: effect of salt concentration  

NASA Astrophysics Data System (ADS)

Recent experiments on the detection of single molecules of linear polyelectrolytes through nanopores could lead to an ultrafast and inexpensive method of rapidly sequencing linear polymer chains such as DNA and RNA. In earlier work (see Ghosal, S. in APS DFD06 abstracts) a hydrodynamic model for determining the electrophoretic speed of a polyelectrolyte through an axially symmetric slowly varying nanopore was presented in the limit of vanishingly small Debye length. Here the case of a finite Debye layer thickness is considered within the Debye-H"uckel and Stokes flow approximations while restricting the pore geometry to that of a cylinder of length much larger than the diameter. Further, the possibility of a uniform surface charge on the walls of the nanopore is taken into account. The model admits an exact analytical solution from which translocation times are calculated and found to be consistent with recent measurements in solidstate nanopores. It is suggested, based on the solution to the model problem, that the translocation speed can be greatly reduced if the ?-potential of the nanopore walls could be fine tuned to match closely the ?-potential of the polyelectrolyte. Physically this amounts to balancing the net electrical force on the polyelectrolyte inside the pore by the viscous drag of the electroosmotic flow inside the nanopore. Reduction of the translocation speed by several orders of magnitude is essential for achieving single base resolution.

Ghosal, Sandip

2007-11-01

262

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

263

Antibiotics that bind to the A site of the large ribosomal subunit can induce mRNA translocation.  

PubMed

In the absence of elongation factor EF-G, ribosomes undergo spontaneous, thermally driven fluctuation between the pre-translocation (classical) and intermediate (hybrid) states of translocation. These fluctuations do not result in productive mRNA translocation. Extending previous findings that the antibiotic sparsomycin induces translocation, we identify additional peptidyl transferase inhibitors that trigger productive mRNA translocation. We find that antibiotics that bind the peptidyl transferase A site induce mRNA translocation, whereas those that do not occupy the A site fail to induce translocation. Using single-molecule FRET, we show that translocation-inducing antibiotics do not accelerate intersubunit rotation, but act solely by converting the intrinsic, thermally driven dynamics of the ribosome into translocation. Our results support the idea that the ribosome is a Brownian ratchet machine, whose intrinsic dynamics can be rectified into unidirectional translocation by ligand binding. PMID:23249745

Ermolenko, Dmitri N; Cornish, Peter V; Ha, Taekjip; Noller, Harry F

2013-02-01

264

Antibiotics that bind to the A site of the large ribosomal subunit can induce mRNA translocation  

PubMed Central

In the absence of elongation factor EF-G, ribosomes undergo spontaneous, thermally driven fluctuation between the pre-translocation (classical) and intermediate (hybrid) states of translocation. These fluctuations do not result in productive mRNA translocation. Extending previous findings that the antibiotic sparsomycin induces translocation, we identify additional peptidyl transferase inhibitors that trigger productive mRNA translocation. We find that antibiotics that bind the peptidyl transferase A site induce mRNA translocation, whereas those that do not occupy the A site fail to induce translocation. Using single-molecule FRET, we show that translocation-inducing antibiotics do not accelerate intersubunit rotation, but act solely by converting the intrinsic, thermally driven dynamics of the ribosome into translocation. Our results support the idea that the ribosome is a Brownian ratchet machine, whose intrinsic dynamics can be rectified into unidirectional translocation by ligand binding. PMID:23249745

Ermolenko, Dmitri N.; Cornish, Peter V.; Ha, Taekjip; Noller, Harry F.

2013-01-01

265

Reduced genetic diversity and significant genetic differentiation after translocation: Comparison of the remnant and translocated populations of bridled nailtail wallabies ( Onychogalea fraenata )  

Microsoft Academic Search

Loss of genetic diversity and increased population differentiation from source populations are common problems associated with translocation programmes established from captive-bred stock or a small number of founders. The bridled nailtail wallaby is one of the most endangered macropods in Australia, having been reduced to a single remnant population in the last 100 years. A translocated population of bridled nailtail wallabies

Dominique P. Sigg

2006-01-01

266

The cosmic microwave background  

NASA Technical Reports Server (NTRS)

Recent observational and theoretical investigations of the cosmic microwave background radiation (CMBR) are reviewed. Particular attention is given to spectral distortions and CMBR temperature anisotropies at large, intermediate, and small angular scales. The implications of the observations for inflationary cosmological models with curvature fluctuation are explored, and it is shown that the limits determined for intermediate-scale CMBR anisotropy almost rule out a baryon-dominated cosmology.

Silk, Joseph

1989-01-01

267

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

268

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

269

Interrupted Catalysis: The EF4 (LepA) Effect on Back Translocation  

PubMed Central

EF4, though similar structurally to the translocase EF-G, promotes back translocation of tRNAs on the ribosome, and is important for bacterial growth under certain conditions. Here, using a coordinated set of in vitro kinetic measures, including changes in the puromycin reactivity of peptidyl tRNA and in the fluorescence of labeled tRNAs and mRNA, we elucidate the kinetic mechanism of EF4-catalyzed back translocation and determine the effects of the translocation inhibitors spectinomycin and viomycin on the process. EF4-dependent back translocation proceeds from post-translocation complex (POST) to pre-translocation complex (PRE) via a four-step kinetic scheme, i.e., POST ? I1 ? I2 ? I3 ? PRE, that is not the simple reverse of translocation. During back translocation, movements of the tRNA core regions and of mRNA are closely coupled to one another, but are sometimes decoupled from movement of the 3?-end of peptidyl–tRNA. EF4 may be thought of as performing an interrupted catalysis of back translocation, stopping at the formation of I3 rather than catalyzing the complete process of back translocation culminating in PRE complex formation. The delay in polypeptide elongation resulting from transient accumulation of I3 is likely to be important for optimizing functional protein biosynthesis. PMID:20045415

Liu, Hanqing; Pan, Dongli; Pech, Markus; Cooperman, Barry S.

2011-01-01

270

Fitness costs of neighborhood disruption in translocations of a solitary mammal.  

PubMed

Translocation is used to reestablish wild populations of animals, but translocation projects often do not meet their objectives because postrelease mortality of animals is high. One reason for translocation failure is that the behavioral or ecological requirements of released animals are unmet. Maintaining founder-group social relationships during release can affect reestablishment of social species. Solitary territorial species with stable neighbors (restricted dispersal and lifetime occupation of a home range) of the same species may also benefit from the maintenance of these social relationships during translocation. We translocated Stephens' kangaroo rats (Dipodomys stephensi), a solitary species listed as endangered under the U.S. Endangered Species Act, with and without neighboring kangaroo rats. We compared the settlement (establishment of a stable home range) decisions and fitness of kangaroo rats between the 2 treatments. Kangaroo rats translocated with neighbors traveled shorter distances before establishing territories, had higher survival rates, and had significantly higher reproductive success than kangaroo rats translocated without neighbors. Number of offspring was 24-fold higher for kangaroo rats translocated with neighbors than those translocated without neighbors. Differences in behavior following release may partially explain differences in survival between the 2 groups. Immediately following release, animals translocated with neighbors fought less and spent significantly more time foraging and digging burrows than animals translocated without neighbors. Our results indicate that even for solitary species, maintaining relationships among members of a translocated group of animals can influence translocation success. This study is the first empirical demonstration of the fitness consequences of disrupting social relationships among territorial neighbors. PMID:21978094

Shier, Debra M; Swaisgood, Ronald R

2012-02-01

271

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; Oberdörster, Günter

2006-01-01

272

Induced translocation of glycosylphosphatidylinositol-anchored proteins from lipid droplets to adiposomes in rat adipocytes  

PubMed Central

Background and purpose: Adipocytes release membrane vesicles called adiposomes, which harbor the glycosylphosphatidylinositol-anchored proteins (GPI proteins), Gce1 and CD73, after induction with palmitate, H2O2 and the sulphonylurea drug glimepiride. The role of lipid droplets (LD) in trafficking of GPI proteins from detergent-insoluble, glycolipid-enriched, plasma membrane microdomains (DIGs) to adiposomes in rat adipocytes was studied. Experimental approach: Redistribution of Gce1 and CD73 was followed by pulse-chase and long-term labelling, western blot analysis and activity determinations with subcellular fractions and cell-free systems exposed to palmitate, H2O2 and glimepiride. Key results: In response to these signals, Gce1 and CD73 disappeared from DIGs, then transiently appeared in LD and finally were released into adiposomes from small, and, more efficiently, large adipocytes. From DIGs to LD, Gce1 and CD73 were accompanied by cholesterol. Cholesterol depletion from DIGs or LD caused accumulation at DIGs or accelerated loss from LD and release into adiposomes, respectively, of the GPI proteins. Blockade of translocation of Gce1, CD73, caveolin-1 and perilipin-A from DIGs to LD blocked LD biogenesis and long term-accumulation of LD interfered with induced release of the GPI proteins into adiposomes. GPI protein release was up-regulated upon long term-depletion of LD. Adiposomes were released by a DIGs-based cell-free system, but only in presence of LD. Conclusions: GPI proteins are translocated from DIGs to LD prior to their release into adiposomes, which is regulated by cholesterol, LD content and LD biogenesis. This detour may serve to transfer information about the LD content and to control lipolysis/esterification between large and small adipocytes via GPI protein-harbouring adiposomes. PMID:19703169

Müller, G; Jung, C; Wied, S; Biemer-Daub, G

2009-01-01

273

Targets, backgrounds, and discrimination  

NASA Astrophysics Data System (ADS)

The present volume discusses a model-based aircraft identification technique, target intensity and angle scintillations, spatiotemporal nonstationary scene generation, an overview of the Strategic Scene Generation Model (SSGM), nuclear backgrounds for SSGM, and an atmospheric and transmittance code for 50-300 km altitudes. Also discussed are a data base for airborne target signatures, the auroral module of the Strategic High Altitude Radiance Code, and the 3D characteristics of underexpanded and overexpanded rectangular jets. (No individual items are abstracted in this volume)

Accetta, J. S.; Kelley, G. H.

274

The Extragalactic Radio Background  

NASA Technical Reports Server (NTRS)

The existence of an isotropic component of the high-latitude radio sky has been recognized for nearly fifty years, but has typically been assumed to be Galactic in origin. We use recent radio observations to test whether the observed high-latitude component could originate within either an extended Galactic halo or a more local "bubble" structure. The lack of significant polarization from the isotropic component, combined with the lack of significant correlation with the Galactic far-infrared emission, rule out an origin within the Galaxy. We conclude that an extragalactic origin is the only viable alternative for the bulk of the isotropic high-latitude emission. The extragalactic component is 2-3 times brighter than local (Galactic) emission towards the Galactic poles and is consistent with a power law in frequency with amplitude T(sub r) = 24.1 plus or minus 2.1 K and spectral index beta = -2.599 plus or minus 0.036 evaluated at reference frequency 310 MHz.

Kogut, A.; Fixsen, D. J.; Levin, S. M.; Limon, M.; Lubin, P. M.; Seiffert, M.; Singal, J.; Villela, T.; Wollack, E.; Wuensche, C. A.

2011-01-01

275

Translocation of integron-associated resistance in a natural system: acquisition of resistance determinants by Inc P and Inc W plasmids from Salmonella enterica Typhimurium DT104.  

PubMed

Salmonella enterica Typhimurium DT104, 961368, a veterinary field isolate that encodes a chromosomal cluster of resistance genes as well as two integrons, was used to study the mobility of resistance cassettes (aadA2 and pse-1) and nonintegron-associated resistance determinants (chloramphenicol and tetracycline). A range of natural plasmids was used as targets for the translocation of resistance. Plasmids that acquired resistance from the DT104 chromosome were segregated by conjugation into Escherichia coli K12. Plasmids R751, R388, and RP4::Tn7 acquired several combinations of resistance determinant (including single cassettes) at frequencies comparable with transposition. RP4 and pOG660 did not acquire any determinants from DT104. Phenotypic and PCR-based analysis of all the transconjugants that were translocated-both cassettes and more complex combinations of determinants-was carried out to determinate the genetic content. Translocation to R751 and R388 was associated with the loss of the indigenous trimethoprim cassette to both plasmids and also acquisition of sulfonamide resistance by R751 and RP4::Tn7, which indicated movement of the 3' terminus of one or both of the DT104 integrons. Sequencing of the R751 transconjugants confirmed these findings and showed that the translocation of streptomycin and ampicillin cassettes was associated with the precise excision of dhfrIIc and orfD cassettes. Furthermore, the translocation of multiple determinants occurred by at least two mechanisms, one of which was likely to involve a circular intermediate analogous to a composite cassette. Instability was detected in some of the transconjugants. The implication of the findings for the dissemination of resistance among clinical isolates is discussed. PMID:12363003

Sandvang, Dorthe; Diggle, Mathew; Platt, David J

2002-01-01

276

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

277

Backgrounds Data Center  

NASA Astrophysics Data System (ADS)

The Backgrounds Data Center (BDC) is the designated archive for backgrounds data collected by Ballistic Missile Defense Organization (BMDO) programs, some of which include ultraviolet sensors. Currently, the BDC holds ultraviolet data from the IBSS, UVPI, UVLIM, and FUVCAM sensors. The BDC will also be the prime archive for Midcourse Space Experiment (MSX) data and is prepared to negotiate with program managers to handle other datasets. The purpose of the BDC is to make data accessible to users and to assist them in analyzing it. The BDC maintains the Science Catalog Information Exchange System (SCIES) allowing remote users to log in, read or post notices about current programs, search the catalogs for datasets of interest, and submit orders for data. On-site facilities are also available for the analysis of data, and consist of VMS and UNIX workstations with access to software analysis packages such as IDL, IRAF, and Khoros. Either on-site or remotely, users can employ the BDC-developed graphical user interface called the Visual Interface for Space and Terrestrial Analysis (VISTA) to generate catalog queries and to display and analyze data. SCIES and VISTA permit nearly complete access to BDC services and capabilities without the need to be physically present at the data center.

Snyder, William A.; Gursky, Herbert; Heckathorn, Harry M.; Lucke, Bob L.; Dorland, Bryan N.; Kessel, R. A.; Berg, S. L.; Dombrowski, E. G.

1994-09-01

278

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

2008-11-10

279

Dynamics of polymer translocation into a circular nanocontainer through a nanopore  

E-print Network

Using Langevin dynamics simulations, we investigate the dynamics of polymer translocation into a circular nanocontainer through a nanopore under a driving force $F$. We observe that the translocation probability initially increases and then saturates with increasing $F$, independent of $\\phi$, which is the average density of the whole chain in the nanocontainer. The translocation time distribution undergoes a transition from a Gaussian distribution to an asymmetric distribution with increasing $\\phi$. Moreover, we find a nonuniversal scaling exponent of the translocation time as chain length, depending on $\\phi$ and $F$. These results are interpreted by the conformation of the translocated chain in the nanocontainer and the time of an individual segment passing through the pore during translocation.

Zhang, Kehong; 10.1063/1.4712618

2012-01-01

280

Cosmic microwave?background?theory  

PubMed Central

A long-standing goal of theorists has been to constrain cosmological parameters that define the structure formation theory from cosmic microwave background (CMB) anisotropy experiments and large-scale structure (LSS) observations. The status and future promise of this enterprise is described. Current band-powers in ?-space are consistent with a ?T flat in frequency and broadly follow inflation-based expectations. That the levels are ?(10?5)2 provides strong support for the gravitational instability theory, while the Far Infrared Absolute Spectrophotometer (FIRAS) constraints on energy injection rule out cosmic explosions as a dominant source of LSS. Band-powers at ? ? 100 suggest that the universe could not have re-ionized too early. To get the LSS of Cosmic Background Explorer (COBE)-normalized fluctuations right provides encouraging support that the initial fluctuation spectrum was not far off the scale invariant form that inflation models prefer: e.g., for tilted ? cold dark matter sequences of fixed 13-Gyr age (with the Hubble constant H0 marginalized), ns = 1.17 ± 0.3 for Differential Microwave Radiometer (DMR) only; 1.15 ± 0.08 for DMR plus the SK95 experiment; 1.00 ± 0.04 for DMR plus all smaller angle experiments; 1.00 ± 0.05 when LSS constraints are included as well. The CMB alone currently gives weak constraints on ? and moderate constraints on ?tot, but theoretical forecasts of future long duration balloon and satellite experiments are shown which predict percent-level accuracy among a large fraction of the 10+ parameters characterizing the cosmic structure formation theory, at least if it is an inflation variant. PMID:9419321

Bond, J. Richard

1998-01-01

281

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

282

Dynamics of RhoA and ROK? translocation in single living cells  

Microsoft Academic Search

The RhoA-binding kinase (ROK) is one of the target kinases of RhoA and is known to play a critical role in regulating cytoskeletal\\u000a rearrangement in cells. ROK translocates to the plasma membrane fraction; however, the mechanism of the translocation of ROK\\u000a still remains obscure. To clarify the molecular mechanisms of the translocation of ROK, we co-transfected MDCK cells wity\\u000a cyan

Koji Miyazaki; Satoshi Komatsu; Mitsuo Ikebe

2006-01-01

283

Male pachytene pairing in single and double translocation heterozygotes and spermatogenic impairment in the mouse  

Microsoft Academic Search

In order to clarify the relationship between meiotic pairing and progress of spermatogenesis, an analysis of male meiotic pairing was carried out in four reciprocal translocation heterozygotes and two double heterozygotes for two semi-identical reciprocal translocations. The reciprocal translocations were chosen to range from fertility (T70H\\/+) through almost complete sterility (T31H\\/+) to complete sterility (T32H\\/+, T42\\/H+). If meiotic pairing in

P. de Boer; A. G. Searle; F. A. Hoeven; D. G. Rooij; C. V. Beechey

1986-01-01

284

Driven polymer translocation through a nanopore: a manifestation of anomalous diffusion  

E-print Network

We study the translocation dynamics of a polymer chain threaded through a nanopore by an external force. By means of diverse methods (scaling arguments, fractional calculus and Monte Carlo simulation) we show that the relevant dynamic variable, the translocated number of segments $s(t)$, displays an {\\em anomalous} diffusive behavior even in the {\\em presence} of an external force. The anomalous dynamics of the translocation process is governed by the same universal exponent $\\alpha = 2/(2\

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

2007-02-20

285

Cryoelectron microscopy structures of the ribosome complex in intermediate states during tRNA translocation  

PubMed Central

mRNA–tRNA translocation is a central and highly regulated process during translational elongation. Along with the mRNA, tRNA moves through the ribosome in a stepwise fashion. Using cryoelectron microscopy on ribosomes with a P-loop mutation, we have identified novel structural intermediates likely to exist transiently during translocation. Our observations suggest a mechanism by which the rate of translocation can be regulated. PMID:21383139

Fu, Jie; Munro, James B.; Blanchard, Scott C.; Frank, Joachim

2011-01-01

286

Uptake and translocation of paclobutrazol by shoots of M.26 apple rootstock  

Microsoft Academic Search

When 14C-paclobutrazol, a gibberellin synthesis inhibitor, was applied to different parts of actively-growing M.26 apple rootstock shoots it was translocated acropetally when applied to the young stem and, to a lesser extent, from the youngest unrolled leaf. Paclobutrazol was not translocated out of leaf laminae, shoot tips or from one-year-old wood but translocation occurred out of a treated petiole into

P. J. Richardson; J. D. Quinlan

1986-01-01

287

Biopersistence and Brain Translocation of Aluminum Adjuvants of Vaccines  

PubMed Central

Aluminum oxyhydroxide (alum) is a crystalline compound widely used as an immunological adjuvant of vaccines. Concerns linked to the use of alum particles emerged following recognition of their causative role in the so-called macrophagic myofasciitis (MMF) lesion detected in patients with myalgic encephalomyelitis/chronic fatigue/syndrome. MMF revealed an unexpectedly long-lasting biopersistence of alum within immune cells in presumably susceptible individuals, stressing the previous fundamental misconception of its biodisposition. We previously showed that poorly biodegradable aluminum-coated particles injected into muscle are promptly phagocytosed in muscle and the draining lymph nodes, and can disseminate within phagocytic cells throughout the body and slowly accumulate in brain. This strongly suggests that long-term adjuvant biopersistence within phagocytic cells is a prerequisite for slow brain translocation and delayed neurotoxicity. The understanding of basic mechanisms of particle biopersistence and brain translocation represents a major health challenge, since it could help to define susceptibility factors to develop chronic neurotoxic damage. Biopersistence of alum may be linked to its lysosome-destabilizing effect, which is likely due to direct crystal-induced rupture of phagolysosomal membranes. Macrophages that continuously perceive foreign particles in their cytosol will likely reiterate, with variable interindividual efficiency, a dedicated form of autophagy (xenophagy) until they dispose of alien materials. Successful compartmentalization of particles within double membrane autophagosomes and subsequent fusion with repaired and re-acidified lysosomes will expose alum to lysosomal acidic pH, the sole factor that can solubilize alum particles. Brain translocation of alum particles is linked to a Trojan horse mechanism previously described for infectious particles (HIV, HCV), that obeys to CCL2, signaling the major inflammatory monocyte chemoattractant.

Gherardi, Romain Kroum; Eidi, Housam; Crépeaux, Guillemette; Authier, François Jerome; Cadusseau, Josette

2015-01-01

288

Holography for Schrodinger backgrounds  

E-print Network

We discuss holography for Schrodinger solutions of both topologically massive gravity in three dimensions and massive vector theories in (d+1) dimensions. In both cases the dual field theory can be viewed as a d-dimensional conformal field theory (two dimensional in the case of TMG) deformed by certain operators that respect the Schrodinger symmetry. These operators are irrelevant from the viewpoint of the relativistic conformal group but they are exactly marginal with respect to the non-relativistic conformal group. The spectrum of linear fluctuations around the background solutions corresponds to operators that are labeled by their scaling dimension and the lightcone momentum k_v. We set up the holographic dictionary and compute 2-point functions of these operators both holographically and in field theory using conformal perturbation theory and find agreement. The counterterms needed for holographic renormalization are non-local in the v lightcone direction.

Monica Guica; Kostas Skenderis; Marika Taylor; Balt van Rees

2010-08-11

289

The diffuse UV background  

NASA Technical Reports Server (NTRS)

The diffuse radiation field in the UV (900-3,000 A) affects the structure of galactic molecular clouds and conveys important information concerning the physical characteristics and spatial distribution of gas and dust in the universe. Continuum emission in this range is probably dominated by interstellar dust scattering in our galaxy. For view directions and angular resolutions allowing observations in the rifts between galactic dust clouds, the background due to the integrated light of spiral galaxies may be detected, providing important information on their structure and evolution. The redshifted emission from an intergalactic medium may be observable in the regions between nearby bright galaxies. Present observations provide weak constraints on the radiation field required to ionize the intergalactic medium at the level required by the Gunn-Peterson test.

Paresce, F.; Jakobsen, P.

1980-01-01

290

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

291

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

292

Return to the wild: Translocation as a tool in conservation of the Desert Tortoise (Gopherus agassizii)  

USGS Publications Warehouse

Translocation could be used as a tool in conservation of the threatened Mojave Desert Tortoise (Gopherus agassizii) by moving individuals from harm's way and into areas where they could contribute to conservation of the species. Numerous factors may affect the success of translocations, including the conditions experienced by tortoises in holding facilities while awaiting translocation. The tortoises available for our translocation study had been provided supplemental water during their years spent in a captive holding facility, potentially inducing carelessness in water conservation. In addition to generally investigating the efficacy of translocation, we compared the effects of continuing with the effects of ceasing the holding facility's water supplementation regimen. After exposure to one of the two water regimens, all tortoises were given the opportunity to hydrate immediately prior to release. We examined behavior, body mass, carapace length, movement, and mortality of tortoises for two activity seasons following release to the wild. Water supplementation was correlated with high rates of carapace growth and distant movements by males after release. Lengthy movements following translocation may be problematic for conservation planning, but this should be evaluated in light of the goals and circumstances of each translocation project. Although the mortality rate was 21.4% in 1997, data suggest that drought conditions at the site rather than the translocation itself negatively affected the tortoises. None of the tortoises died during their second season at the site. Our results indicate that translocation should be considered a useful tool in conservation of the Desert Tortoise. ?? 2006 Elsevier Ltd. All rights reserved.

Field, K.J.; Tracy, C.R.; Medica, P.A.; Marlow, R.W.; Corn, P.S.

2007-01-01

293

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. PMID:25426325

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

2014-01-01

294

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

295

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

296

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

297

Sucking genes into pores: Insight into driven translocation  

NASA Astrophysics Data System (ADS)

Flexible polymers such as long DNA, RNA molecules, and proteins, can pass through a narrow pore whose size is comparable to their molecular thickness. We highlight the richness and complexity involved in the dynamics of this unique mode of molecular transport, called translocation, actively driven by external forces. In particular, the process takes place in the condition far from equilibrium accompanying of large conformational distortion in line with the propagation of the tensile force along the chain backbone. A general framework is proposed, which captures such essential features, whereby can account for reported various experimental data from a unified viewpoint.

Sakaue, Takahiro

2010-04-01

298

Background sources in optical communications  

NASA Technical Reports Server (NTRS)

The characterization and measurement of background radiation relevant to optical communications system performance is addressed. The necessary optical receiver parameters are described, and radiometric concepts required for the calculation of collected background power are developed. The most important components of optical background power are discussed, and their contribution to the total collected background power in various communications scenarios is examined.

Vilnrotter, V. A.

1983-01-01

299

Cosmic Microwave Background  

NASA Astrophysics Data System (ADS)

The cosmic microwave background (CMB) radiation, the relic of the early phases of the expanding universe, is bright, full of information, and difficult to measure. Along with the recession of galaxies and the primordial nucleosynthesis, it is one of the strongest signs that the Hot Big Bang Model of the universe is correct. It is brightest around 2 mm wavelength, has a temperature of T_{cmb} = 2.72548 ± 0.00057 K, and has a blackbody spectrum within 50 parts per million. Its spatial fluctuations (around 0.01% on 1{}^{circ } scales) are possibly the relics of quantum mechanical processes in the early universe, modified by processes up to the decoupling at a redshift of about 1,000 (when the primordial plasma became mostly transparent). In the cold dark matter (DM) model with cosmic acceleration (? CDM), the fluctuation statistics are consistent with the model of inflation and can be used to determine other parameters within a few percent, including the Hubble constant, the ? constant, the densities of baryonic and dark matter, and the primordial fluctuation amplitude and power spectrum slope. In addition, the polarization of the fluctuations reveals the epoch of reionization at a redshift approximately twice that determined from the Gunn-Peterson trough due to optically thick Lyman ? absorption in QSO spectra. It is of historic importance, and a testament to the unity of theory and experiment, that we now have a standard model of cosmology that is consistent with all of the observations.Current observational challenges include (1) improvement of the spectrum distortion measurements, especially at long wavelengths, where the measured background is unexpectedly bright; (2) the search for the B-mode polarization (the divergence-free part of the polarization map), arising from propagating gravitational waves; and (3) the extension of fluctuation measurements to smaller angular scales. Much more precise spectrum observations near 2 mm are likely and would test some very interesting theories. Current theoretical challenges include explanation of the dark matter and dark energy; understanding, estimating, and removing the interference of foreground sources that limit the measurements of the CMB; detailed understanding of the influence of nonequilibrium processes on the decoupling and reionization phases; and searches for signs of the second order or exotic processes (e.g., isocurvature fluctuations, cosmic strings, non-Gaussian fluctuations). At this writing, we await the cosmological results of the Planck mission.

Mather, John; Hinshaw, Gary; Page, Lyman

300

Curcumin prevents leptin raising glucose levels in hepatic stellate cells by blocking translocation of glucose transporter-4 and increasing glucokinase  

PubMed Central

BACKGROUND AND PURPOSE Hyperleptinemia is commonly found in obese patients, associated with non-alcoholic steatohepatitis and hepatic fibrosis. Hepatic stellate cells (HSCs) are the most relevant effectors during hepatic fibrogenesis. We recently reported that leptin stimulated HSC activation, which was eliminated by curcumin, a phytochemical from turmeric. This study was designed to explore the underlying mechanisms, focusing on their effects on intracellular glucose in HSCs. We hypothesized that leptin stimulated HSC activation by elevating the level of intracellular glucose, which was eliminated by curcumin by inhibiting the membrane translocation of glucose transporter-4 (GLUT4) and inducing the conversion of glucose to glucose-6-phosphate (G-6-P). EXPERIMENTAL APPROACH Levels of intracellular glucose were measured in rat HSCs and immortalized human hepatocytes. Contents of GLUT4 in cell fractions were analysed by Western blotting analyses. Activation of signalling pathways was assessed by comparing phosphorylation levels of protein kinases. KEY RESULTS Leptin elevated the level of intracellular glucose in cultured HSCs, which was diminished by curcumin. Curcumin suppressed the leptin-induced membrane translocation of GLUT4 by interrupting the insulin receptor substrates/phosphatidyl inositol 3-kinase/AKT signalling pathway. Furthermore, curcumin stimulated glucokinase activity, increasing conversion of glucose to G-6-P. CONCLUSIONS AND IMPLICATIONS Curcumin prevented leptin from elevating levels of intracellular glucose in activated HSCs in vitro by inhibiting the membrane translocation of GLUT4 and stimulating glucose conversion, leading to the inhibition of HSC activation. Our results provide novel insights into mechanisms of curcumin in inhibiting leptin-induced HSC activation. PMID:20977462

Tang, Youcai; Chen, Anping

2010-01-01

301

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

302

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

303

Mitogenic activation, phosphorylation, and nuclear translocation of protein kinase Bbeta.  

PubMed

Protein kinase B (PKB) is a member of the second messenger-dependent family of serine/threonine kinases that has been implicated in signaling pathways downstream of growth factor receptor tyrosine kinases and phosphatidylinositol 3-kinase. Here we report the characterization of the human beta-isoform of PKB (PKBbeta). PKBbeta is ubiquitously expressed in a number of human tissues, with mRNA and protein levels elevated in heart, liver, skeletal muscle, and kidney. After transfection into HEK-293 or COS-1 cells, PKBbeta is activated 2- to 12-fold by mitogens and survival factors. Activation was due to phosphorylation on Thr-309 and Ser-474, which correspond to Thr-308 and Ser-473 implicated in the regulation of PKBalpha. Both phosphorylation and activation were prevented by the phosphatidylinositol 3-kinase inhibitor wortmannin. Moreover, membrane-targeted PKBbeta was constitutively activated when overexpressed in HEK-293 cells. Although the specific activity of PKBbeta was lower than that of PKBalpha toward Crosstide as a substrate (23 nmol/min/mg compared with 178 nmol/min/mg for PKBalpha), both enzymes showed similar substrate specificities. Using confocal microscopy, we show that activation of PKBbeta results in its nuclear translocation within 20 to 30 min after stimulation. These observations provide evidence that PKBbeta undergoes nuclear translocation upon mitogenic activation and support a role for PKB in signaling from receptor tyrosine kinases to the nucleus through phosphatidylinositol 3-kinase. PMID:9374542

Meier, R; Alessi, D R; Cron, P; Andjelkovi?, M; Hemmings, B A

1997-11-28

304

Toxicity and translocation of graphene oxide in Arabidopsis thaliana.  

PubMed

We investigated the possible safety property and translocation of graphene oxide (GO) in the range of ?g/L in Arabidopsis. GO exposure did not obviously influence germination, seed development, shoot and root development of seedlings, and flowering time. Meanwhile, GO exposure could not induce severe H2O2 production, increase in malondialdehyde content, formation of oxidative stress, and altered activities of antioxidant enzymes. Moreover, GO exposure did not change expression patterns of examined genes required for germination, photomorphogenesis, root development, and transition from vegetative to reproductive development. In the seedling, we did not observe severe GO accumulation in mesophyll and parenchyma cells of leaf or stem, and in sieve element in leaf, stem, or root. In contrast, we observed the severe GO accumulation in root hair and root parenchyma cells. Our results provide the physiological basis for safety property of GO at the examined concentrations in Arabidopsis plants. Furthermore, our data imply that although GO was absorbed by Arabidopsis plants through root hairs, plants might still have strong ability to be against GO translocation into stem or leaves. In addition, we found that cotyledon might serve as an important site for GO distribution during the early development. PMID:25499792

Zhao, Shengqing; Wang, Qianqian; Zhao, Yunli; Rui, Qi; Wang, Dayong

2015-01-01

305

Isosporoid coccidiosis in translocated cirl buntings (Emberiza cirlus).  

PubMed

Four of 17 cirl buntings (Emberiza cirlus) involved in a trial translocation in 2004 for conservation purposes died and were examined postmortem. Two of the cirl buntings showed intestinal and hepatic lesions, including necrotising enteritis, consistent with isosporoid coccidiosis, and a third had an intestinal infestation of isosporoid coccidia. Sporulated oocysts from faecal samples from the birds were identified as Isospora normanlevinei, a parasite previously detected in cirl bunting populations in continental Europe. In a subsequent translocation of 75 cirl buntings from Devon to Cornwall in 2006, each brood of birds was placed in strict quarantine at low stocking density, with improved hygienic precautions and detailed health surveillance, and each bird was treated prophylactically with toltrazuril in an attempt to control the disease but not eliminate the I normanlevinei parasites. Seventy-two of the 75 birds were successfully reared and released, and there were no apparent clinical or pathological signs of isosporoid coccidiosis in any bird. I normanlevinei was detected in the released population, an indication that it had been successfully conserved. PMID:21257466

McGill, I; Feltrer, Y; Jeffs, C; Sayers, G; Marshall, R N; Peirce, M A; Stidworthy, M F; Pocknell, A; Sainsbury, A W

2010-10-23

306

Translocator protein (TSPO) and neurosteroids: implications in psychiatric disorders.  

PubMed

The translocator protein (TSPO) is a five transmembrane domain protein localised primarily in the outer mitochondrial membrane of steroid-synthesizing tissues, including the brain. The TSPO mediates the rate-limiting step of steroidogenesis, consisting of the translocation of the substrate cholesterol from the outer to the inner mitochondrial membrane. In the recent years TSPO function has received attention in several psychiatric disorders since these diseases have been associated with unbalanced steroid levels. Accordingly, an alteration in the levels of TSPO has been found in various psychiatric disorders, including social phobia, post-traumatic stress disorder, adult separation anxiety and schizophrenia. The discovery that TSPO drug ligands are able to stimulate neurosteroid production in the brain, independently of peripheral endocrine sources, and restore neurosteroid-mediated neurotransmission, has made the TSPO an attractive drug target for treating a number of psychiatric disorders. In anxiety TSPO drug ligands have shown in vivo efficacy in pharmacologically induced anxiety models in both animals and humans. The focus of this review is to illustrate the currently available literature regarding the role of TSPO in psychiatric disorders. PMID:22348611

Da Pozzo, E; Costa, B; Martini, C

2012-05-01

307

Translocator protein ligands as promising therapeutic tools for anxiety disorders.  

PubMed

The Translocator protein (TSPO), formerly known as the peripheral-type benzodiazepine receptor, is an 18 kDa mitochondrial protein primarily involved in steroid biosynthesis in both peripheral and glial cells. It has been extensively reported that TSPO regulates the rate-limiting translocation of cholesterol from the outer to the inner mitochondrial membrane before its transformation by cytochrome P450(scc) into pregnenolone, which is further converted into an array of different steroids. In the brain, neurosteroids such as allopregnanolone and pregnenolone, acting as positive modulators of gamma-aminobutyric type A (GABA(A)) receptors, exert anxiolytic activity. Specific ligands targeting TSPO increase neurosteroid production and for this reason they have been suggested to play an important role in anxiety modulation. Unlike benzodiazepines (Bzs), which represent the most common anti-anxiety drugs administered around the world, selective TSPO ligands have shown anxiolytic effects in animal models without any of the side effects associated with Bzs. Therefore, specific TSPO ligands that are able to promote neurosteroidogenesis may represent the future of therapeutic treatment of anxiety disorders. Furthermore, TSPO expression levels are altered in several different psychiatric disorders in which anxiety is the main symptom. This article reviews the primary and patent literature over the last decade concerning the development of novel TSPO ligands that have resulted effective in various models of anxiety, taking into special consideration their structure-activity relationships. PMID:19548867

Taliani, S; Da Settimo, F; Da Pozzo, E; Chelli, B; Martini, C

2009-01-01

308

SecA-mediated targeting and translocation of secretory proteins.  

PubMed

More than 30 years of research have revealed that the dynamic nanomotor SecA is a central player in bacterial protein secretion. SecA associates with the SecYEG channel and transports polypeptides post-translationally to the trans side of the cytoplasmic membrane. It comprises a helicase-like ATPase core coupled to two domains that provide specificity for preprotein translocation. Apart from SecYEG, SecA associates with multiple ligands like ribosomes, nucleotides, lipids, chaperones and preproteins. It exerts its essential contribution in two phases. First, SecA, alone or in concert with chaperones, helps mediate the targeting of the secretory proteins from the ribosome to the membrane. Next, at the membrane it converts chemical energy to mechanical work and translocates preproteins through the SecYEG channel. SecA is a highly dynamic enzyme, it exploits disorder-order kinetics, swiveling and dissociation of domains and dimer to monomer transformations that are tightly coupled with its catalytic function. Preprotein signal sequences and mature domains exploit these dynamics to manipulate the nanomotor and thus achieve their export at the expense of metabolic energy. This article is part of a Special Issue entitled: Protein trafficking and secretion in bacteria. Guest Editors: Anastassios Economou and Ross Dalbey. PMID:24583121

Chatzi, Katerina E; Sardis, Marios Frantzeskos; Economou, Anastassios; Karamanou, Spyridoula

2014-08-01

309

Molecular determinants of nucleolar translocation of RNA helicase A  

SciTech Connect

RNA helicase A (RHA) is a member of the DEAH-box family of DNA/RNA helicases involved in multiple cellular processes and the life cycles of many viruses. The subcellular localization of RHA is dynamic despite its steady-state concentration in the nucleoplasm. We have previously shown that it shuttles rapidly between the nucleus and the cytoplasm by virtue of a bidirectional nuclear transport domain (NTD) located in its carboxyl terminus. Here, we investigate the molecular determinants for its translocation within the nucleus and, more specifically, its redistribution from the nucleoplasm to nucleolus or the perinucleolar region. We found that low temperature treatment, transcription inhibition or replication of hepatitis C virus caused the intranuclear redistribution of the protein, suggesting that RHA shuttles between the nucleolus and nucleoplasm and becomes trapped in the nucleolus or the perinucleolar region upon blockade of transport to the nucleoplasm. Both the NTD and ATPase activity were essential for RHA's transport to the nucleolus or perinucleolar region. One of the double-stranded RNA binding domains (dsRBD II) was also required for this nucleolar translocation (NoT) phenotype. RNA interference studies revealed that RHA is essential for survival of cultured hepatoma cells and the ATPase activity appears to be important for this critical role.

Liu Zhe; Kenworthy, Rachael; Green, Christopher [Department of Biological Science, Florida State University, Tallahassee, FL 32306-4370 (United States); Tang, Hengli [Department of Biological Science, Florida State University, Tallahassee, FL 32306-4370 (United States)], E-mail: tang@bio.fsu.edu

2007-10-15

310

Out of Equilibrium Characteristics of a Forced Translocating Chain through a Nanopore  

E-print Network

Polymer translocation through a nano-pore in a thin membrane is studied using a coarse-grained bead-spring model and Langevin dynamics simulation with a particular emphasis to explore out of equilibrium characteristics of the translocating chain. We analyze the out of equilibrium chain conformations both at the $cis$ and the $trans$ side separately either as a function of the time during the translocation process or as as function of the monomer index $m$ inside the pore. A detailed picture of translocation emerges by monitoring the center of mass of the translocating chain, longitudinal and transverse components of the gyration radii and the end to end vector. We observe that polymer configurations at the $cis$ side are distinctly different from those at the $trans$ side. During the translocation, and immediately afterwards, the chain is clearly out of equilibrium, as different parts of the chain are characterized by a series of effective Flory exponents. We further notice that immediately after the translocation the last set of beads that have just translocated take a relatively compact structure compared to the first set of beads that translocated earlier, and the chain immediately after translocation is described by an effective Flory exponent $0.45 \\pm 0.01$. The analysis of these results is further strengthened by looking at the conformations of chain segments of equal length as they cross from the $cis$ to the $trans$ side, We discuss implications of these results to the theoretical estimates and numerical simulation studies of the translocation exponent reported by various groups.

Aniket Bhattacharya; Kurt Binder

2009-12-04

311

Absolute calibration and beam background of the Squid Polarimeter  

SciTech Connect

The problem of beam background in Squid Polarimetry is not without residual benefits. The authors may deliberately generate beam background by gently kicking the beam at the spin tune frequency. This signal may be used to accomplish a simple and accurate absolute calibration of the polarimeter. The authors present details of beam background calculations and their application to polarimeter calibration, and suggest a simple proof-of-principle accelerator experiment.

Blaskiewicz, M.M.; Cameron, P.R.; Shea, T.J. [and others

1996-12-31

312

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, Françoise

2009-01-01

313

Somatic chromosomal translocation between Ewsr1 and Fli1 loci leads to dilated cardiomyopathy in a mouse model.  

PubMed

A mouse model that recapitulates the human Ewing's sarcoma-specific chromosomal translocation was generated utilizing the Cre/loxP-mediated recombination technique. A cross between Ewsr1-loxP and Fli1-loxP mice and expression of ubiquitous Cre recombinase induced a specific translocation between Ewsr1 and Fli1 loci in systemic organs of both adult mice and embryos. As a result Ewsr1-Fli1 fusion transcripts were expressed, suggesting a functional Ews-Fli1 protein might be synthesized in vivo. However, by two years of age, none of the Ewsr1-loxP/Fli1-loxP/CAG-Cre (EFCC) mice developed any malignancies, including Ewing-like small round cell sarcoma. Unexpectedly, all the EFCC mice suffered from dilated cardiomyopathy and died of chronic cardiac failure. Genetic recombination between Ewsr1 and Fli1 was confirmed in the myocardial tissue and apoptotic cell death of cardiac myocytes was observed at significantly higher frequency in EFCC mice. Moreover, expression of Ews-Fli1 in the cultured cardiac myocytes induced apoptosis. Collectively, these results indicated that ectopic expression of the Ews-Fli1 oncogene stimulated apoptotic signals, and suggested an important relationship between oncogenic signals and cellular context in the cell-of-origin of Ewing's sarcoma. PMID:25591392

Tanaka, Miwa; Yamaguchi, Shuichi; Yamazaki, Yukari; Kinoshita, Hideyuki; Kuwahara, Koichiro; Nakao, Kazuwa; Jay, Patrick Y; Noda, Tetsuo; Nakamura, Takuro

2015-01-01

314

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

315

Chromosome aberrations and spermatogenic disorders in mice with Robertsonian translocation (11; 13)  

PubMed Central

Objective: To determine the diagnostic features of Robertsonian (Rob) translocation (11; 13) in mice and the mechanisms underlying the effect on spermatogenesis and reproductive decline. Methods: A Rob translocation (11; 13) mouse model was established by cross-breeding, and confirmed by chromosome analysis. Chromosome aberrations and translocation patterns were identified in mice with Rob translocation (11; 13) by fluorescence in situ hybridization (FISH). Spermatogenic disorders were investigated at different stages of spermatogenesis. Immunofluorescent analysis was performed on sections of testis and epididymis specimens during spermatogenic meiosis. The weight of the testes and reproductive decline were recorded. Results: The crossed Rob translocation (11; 13) mouse has 39 chromosomes, including a fusion chromosome (included chromosomes 11 and 13) using dual color FISH. There was no difference in the distribution pattern of SYCP3 and ?H2AX in spermatocytes between Rob translocation and wild-type mice; however, round haploid spermatids presented characteristic morphologic changes of apoptosis and the number of haploid spermatids was decreased. Furthermore, the immature germ cells were released into the epididymis and the number of mature sperm was reduced. Conclusions: Chromosome aberrations and spermatogenic disorders may result from apoptosis of round haploid spermatids and a reduced number of mature sperm in Rob translocation (11; 13) mice. Abnormal sperm and reduced number of sperm may be one of the main reasons for reproductive decline and male infertility in Rob translocation (11; 13) mice.

Zhuang, Xinjie; Huang, Jin; Jin, Xiaohu; Yu, Yang; Li, Junsheng; Qiao, Jie; Liu, Ping

2014-01-01

316

Y autosome translocation and complex chromosome rearrangement in cri du chat syndrome  

Microsoft Academic Search

An unbalanced Y autosome translocation t(5;Y) and an apparently balanced translocation t(2;13) are identified with the Q and R banding in a 7-year-old boy with severe encephalopathy and a multiple malformation syndrome. At birth, the clinical diagnosis of 'cri du chat' syndrome based on the characteristic crying was not confirmed after karyotyping, using conventional staining techniques.

J F Mattei; M G Mattei; J Coignet; F Giraud

1978-01-01

317

A High-Content Glucocorticoid Receptor Translocation Assay for Compound Mechanism-of-Action Evaluation  

Microsoft Academic Search

Ligand-induced cytoplasm to nucleus translocation is a critical event in the nuclear receptor (NR) signal transduction cascade. The development of green fluorescent proteins and their color variants fused with NRs, along with the recent developments in automated cellular imaging technologies, has provided unique tools to monitor and quantify the NR translocation events. These technology developments have important implications in the

Michele Agler; Margaret Prack; Yingjie Zhu; Janet Kolb; Kimberly Nowak; Rolf Ryseck; Ding Shen; Mary Ellen Cvijic; John Somerville; Steve Nadler; Taosheng Chen

2007-01-01

318

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

319

Fall fertilization enhanced nitrogen storage and translocation in Larix olgensis seedlings  

E-print Network

loading of deciduous forest nursery seedlings is of special interest because of foliage abscission use efficiency Á Deciduous forest seedling Á Nitrogen storage Á Nutrient translocation Introduction and varied translocation patterns. For non-deciduous seed- lings in the nursery, fall fertilization typically

320

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

321

Cytologically Integrated Physical Restriction Fragment Length Polymorphism Maps for the Barley Genome Based on Translocation Breakpoints  

Microsoft Academic Search

We have developed a new technique for the physical mapping of barley chromosomes using microdis- sected translocation chromosomes for PCR with sequence-tagged site primers derived from .300 geneti- cally mapped RFLP probes. The positions of 240 translocation breakpoints were integrated as physical landmarks into linkage maps of the seven barley chromosomes. This strategy proved to be highly efficient in relating

Gottfried Kunzel; Larissa Korzun; Armin Meister

322

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

323

Slowing down DNA Translocation through a Nanopore in Lithium Stefan W. Kowalczyk,,  

E-print Network

Slowing down DNA Translocation through a Nanopore in Lithium Chloride Stefan W. Kowalczyk,,§ David. Here, we study the partial reduction of the DNA charge due to counterion binding by means of nanopore that the translocation time of a DNA molecule through a solid-state nanopore strongly increases as the counterions

Dekker, Cees

324

Effect of charge distribution on the translocation of an inhomogeneously charged polymer through a nanopore  

E-print Network

We investigate the voltage-driven translocation of an inhomogeneously charged polymer through a nanopore by utilizing discrete and continuous stochastic models. As a simplified illustration of the effect of charge distribution on translocation, we consider the translocation of a polymer with a single charged site in the presence and absence of interactions between the charge and the pore. We find that the position of the charge that minimizes the translocation time in the absence of pore--polymer interactions is determined by the entropic cost of translocation, with the optimum charge position being at the midpoint of the chain for a rodlike polymer and close to the leading chain end for an ideal chain. The presence of attractive or repulsive pore--charge interactions yields a shift in the optimum charge position towards the trailing end and the leading end of the chain, respectively. Moreover, our results show that strong attractive or repulsive interactions between the charge and the pore lengthen the translocation time relative to translocation through an inert pore. We generalize our results to accommodate the presence of multiple charged sites on the polymer. Our results provide insight into the effect of charge inhomogeneity on protein translocation through biological membranes.

Aruna Mohan; Anatoly B. Kolomeisky; Matteo Pasquali

2007-11-01

325

Sec and Tat-Dependent Translocation of  -Lactamases across the Escherichia coli Inner Membrane  

Microsoft Academic Search

-Lactamases represent the major resistance mechanism of gram-negative bacteria against -lactam anti- biotics. The amino acid sequences of these proteins vary widely, but all are located in the periplasm of bacteria. In this study, we investigated the translocation mechanism of representative -lactamases in an Escherichia coli model. N-terminal signal sequence analyses, antibiotic activity assay, and direct measurement of translocation of

N. Pradel; J. Delmas; L. F. Wu; C. L. Santini; R. Bonnet

2009-01-01

326

Long-term apparent survival of translocated gopher tortoises: A comparison of newly released  

E-print Network

Long-term apparent survival of translocated gopher tortoises: A comparison of newly released disturbance as a result of increased mortality or dispersal of released animals. The gopher tortoise (Gopherus-term apparent survival of two groups of gopher tortoises translocated during separate periods to St. Catherines

Georgia, University of

327

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

328

Sequence-directed DNA export guides chromosome translocation during sporulation in Bacillus subtilis  

E-print Network

translocation by SpoIIIE in vitro and in vivo. These data allow us to propose a sequence-directed DNA exporterSequence-directed DNA export guides chromosome translocation during sporulation in Bacillus & Carlos Bustamante3­5 In prokaryotes, the transfer of DNA between cellular compartments is essential

Nollmann, Marcelo

329

Genome-wide translocation sequencing reveals mechanisms of chromosome breaks and rearrangements in B cells.  

PubMed

Whereas chromosomal translocations are common pathogenetic events in cancer, mechanisms that promote them are poorly understood. To elucidate translocation mechanisms in mammalian cells, we developed high-throughput, genome-wide translocation sequencing (HTGTS). We employed HTGTS to identify tens of thousands of independent translocation junctions involving fixed I-SceI meganuclease-generated DNA double-strand breaks (DSBs) within the c-myc oncogene or IgH locus of B lymphocytes induced for activation-induced cytidine deaminase (AID)-dependent IgH class switching. DSBs translocated widely across the genome but were preferentially targeted to transcribed chromosomal regions. Additionally, numerous AID-dependent and AID-independent hot spots were targeted, with the latter comprising mainly cryptic I-SceI targets. Comparison of translocation junctions with genome-wide nuclear run-ons revealed a marked association between transcription start sites and translocation targeting. The majority of translocation junctions were formed via end-joining with short microhomologies. Our findings have implications for diverse fields, including gene therapy and cancer genomics. PMID:21962511

Chiarle, Roberto; Zhang, Yu; Frock, Richard L; Lewis, Susanna M; Molinie, Benoit; Ho, Yu-Jui; Myers, Darienne R; Choi, Vivian W; Compagno, Mara; Malkin, Daniel J; Neuberg, Donna; Monti, Stefano; Giallourakis, Cosmas C; Gostissa, Monica; Alt, Frederick W

2011-09-30

330

Translocation of Shiga-toxin producting cells of Escherichia coli in chemically-injected beef subprimals  

Technology Transfer Automated Retrieval System (TEKTRAN)

Introduction: Relatively little information is available regarding the translocation of Escherichia coli O157:H7 (ECOH) and non-O157:H7 verocytotoxigenic E. coli (STEC) into beef subprimals following chemical tenderization. Purpose: Quantify translocation of ECOH or STEC from the surface into the i...

331

Nuchal Translucency Thickness in Fetuses With Chromosomal Translocation at 11-12 Weeks of Gestation  

Microsoft Academic Search

OBJECTIVE: To investigate differences in nuchal translu- cency thickness among fetuses in which either parent is a balanced chromosome translocation carrier. METHODS: A prospective observational study was con- ducted with 98 pregnant women in the first trimester. Each hadbeenadvisedtoundergochorionicvilloussamplingfor fetal karyotyping for the indication of parental balanced chromosomal translocation. Fetal nuchal translucency measurement was performed before chorionic villous sam- pling.

Po-Jen Cheng; Shuenn-Dhy Chang; Sheng-Wen Shaw; Yung-Kuei Soong

2005-01-01

332

Response of Mountain Yellow-Legged Frogs, Rana muscosa, to Short Distance Translocation  

Microsoft Academic Search

To determine the response of Mountain Yellow-Legged Frogs to short distance translocations, I placed transmitters on 20 adult frogs and moved them short distances from 144-630 m and monitored their responses for up to 30 days. Of the 20 translocated frogs, seven frogs returned to their original capture site, four frogs moved in the direction of their capture site but

Kathleen R. Matthews

2003-01-01

333

Molecular characterization of the rare translocation t(3;10)(q26;q21) in an acute myeloid leukemia patient  

PubMed Central

Background In acute myeloid leukemia (AML), the MDS1 and EVI1 complex locus - MECOM, also known as the ecotropic virus integration site 1 - EVI1, located in band 3q26, can be rearranged with a variety of partner chromosomes and partner genes. Here we report on a 57-year-old female with AML who presented with the rare translocation t(3;10)(q26;q21) involving the MECOM gene. Our aim was to identify the fusion partner on chromosome 10q21 and to characterize the precise nucleotide sequence of the chromosomal breakpoint. Methods Cytogenetic and molecular-cytogenetic techniques, chromosome microdissection, next generation sequencing, long-range PCR and direct Sanger sequencing were used to map the chromosomal translocation. Results Using a combination of cytogenetic and molecular approaches, we mapped the t(3;10)(q26;q21) to the single nucleotide level, revealing a fusion of the MECOM gene (3q26.2) and C10orf107 (10q21.2). Conclusions The approach described here opens up new possibilities in characterizing acquired as well as congenital chromosomal aberrations. In addition, DNA sequences of chromosomal breakpoints may be a useful tool for unique molecular minimal residual disease target identification in acute leukemia patients. PMID:25071866

2014-01-01

334

Role of JNK Activation and Mitochondrial Bax Translocation in Allicin-Induced Apoptosis in Human Ovarian Cancer SKOV3 Cells.  

PubMed

Background. Allicin, the major component of freshly crushed garlic, is one of the most biologically active compounds of garlic; it has been reported to induce apoptosis in cancer cells; however, the mechanism by which allicin exerts its apoptotic effects is not fully understood. The aim of the present study was to further elucidate the apoptotic pathways induced by allicin in the human ovarian cancer cell line SKOV3. Methods. Cell proliferation and apoptosis were measured by cell-counting assay and flow cytometry analysis. Activation of the signaling pathway was screened by human phospho-kinase array analysis, and the activated pathway and its related proteins were further confirmed by western blot analysis. Results. Allicin induced SKOV3 cell apoptosis and JNK phosphorylation in a time- and dose-dependent manner, but these were significantly blocked by SP600125 (an inhibitor of JNK). The findings suggest that JNK phosphorylation is related to the action of allicin on SKOV3 cells. Furthermore, JNK activation induced Bcl-2 family activation, triggered mitochondria-mediated signaling pathways, and led to the translocation of a considerable amount of Bax and cytochrome c release. Conclusions. JNK activation and mitochondrial Bax translocation are involved in allicin-induced apoptosis in SKOV3 cells. Our data input new insights to the literature of allicin-induced apoptosis. PMID:25097657

Xu, Ling; Yu, Jin; Zhai, Dongxia; Zhang, Danying; Shen, Wei; Bai, Lingling; Cai, Zailong; Yu, Chaoqin

2014-01-01

335

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. PMID:25408709

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

2014-01-01

336

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

2014-10-03

337

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

338

Translocation of a Polymer through a Nanopore across a Viscosity Gradient  

E-print Network

The translocation of a polymer through a pore in a membrane separating fluids of different viscosities is studied via several computational approaches. Starting with the polymer halfway, we find that as a viscosity difference across the pore is introduced, translocation will predominately occur towards one side of the membrane. These results suggest an intrinsic pumping mechanism for translocation across cell walls which could arise whenever the fluid across the membrane is inhomogeneous. Somewhat surprisingly, the sign of the preferred direction of translocation is found to be strongly dependent on the simulation algorithm: for Langevin Dynamics (LD) simulations, a bias towards the low viscosity side is found while for Brownian Dynamics (BD), a bias towards the high viscosity is found. Examining the translocation dynamics in detail across a wide range of viscosity gradients and developing a simple force model to estimate the magnitude of the bias, the LD results are demonstrated to be more physically realist...

de Haan, Hendrick W

2012-01-01

339

Translocation of stiff polymers through a nanopore driven by binding particles  

E-print Network

We investigate the translocation of stiff polymers in the presence of binding particles through a nanopore by two-dimensional Langevin dynamics simulations. We find that the mean translocation time shows a minimum as a function of the binding energy $\\epsilon$ and the particle concentration $\\phi$, due to the interplay of the force from binding and the frictional force. Particularly, for the strong binding the translocation proceeds with a decreasing translocation velocity induced by a significant increase of the frictional force. In addition, both $\\epsilon$ and $\\phi$ have an notable impact on the distribution of the translocation time. With increasing $\\epsilon$ and $\\phi$, it undergoes a transition from an asymmetric and broad distribution under the weak binding to a nearly Gaussian one under the strong binding, and its width becomes gradually narrower.

Yu, Wancheng; Luo, Kaifu

2012-01-01

340

Rotation of the head of the 30S ribosomal subunit during mRNA translocation.  

PubMed

Elongation factor-G-catalyzed translocation of mRNA and tRNAs during protein synthesis involves large-scale conformational changes in the ribosome. Formation of hybrid-state intermediates is coupled to counterclockwise (forward) rotation of the body of the 30S subunit. Recent structural studies implicate intrasubunit rotation of the 30S head in translocation. Here, we observe rotation of the head during translocation in real time using ensemble stopped-flow FRET with ribosomes containing fluorescent probes attached to specific positions in the head and body of the 30S subunit. Our results allow ordering of the rates of movement of the 30S subunit body and head during translocation: body forward > head forward > head reverse ? body reverse. The rate of quenching of pyrene-labeled mRNA is consistent with coupling of mRNA translocation to head rotation. PMID:23188795

Guo, Zhuojun; Noller, Harry F

2012-12-11

341

Directed translocation of a flexible polymer through a cone-shaped nano-channel.  

PubMed

Translocation of a flexible polymer through a cone-shaped channel is studied, theoretically and using computer simulations. Our simulations show that the shape of the channel causes the polymer translocation to be a driven process. The effective driving force of entropic origin acting on the polymer is calculated as a function of the length and the apex-angle of the channel, theoretically. It is found that the translocation time is a non-monotonic function of the apex-angle of the channel. By increasing the apex-angle from zero, the translocation time shows a minimum and then a maximum. Also, it is found that regardless of the value of the apex-angle, the translocation time is a uniformly decreasing function of the channel length. The results of the theory and the simulation are in good qualitative agreement. PMID:23968109

Nikoofard, Narges; Khalilian, Hamidreza; Fazli, Hossein

2013-08-21

342

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

PubMed

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. PMID:23742512

Chen, Yuhao; Luo, Kaifu

2013-05-28

343

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

344

Transducin translocation contributes to rod survival and enhances synaptic transmission from rods to rod bipolar cells  

PubMed Central

In rod photoreceptors, several phototransduction components display light-dependent translocation between cellular compartments. Notably, the G protein transducin translocates from rod outer segments to inner segments/spherules in bright light, but the functional consequences of translocation remain unclear. We generated transgenic mice where light-induced transducin translocation is impaired. These mice exhibited slow photoreceptor degeneration, which was prevented if they were dark-reared. Physiological recordings showed that control and transgenic rods and rod bipolar cells displayed similar sensitivity in darkness. After bright light exposure, control rods were more strongly desensitized than transgenic rods. However, in rod bipolar cells, this effect was reversed; transgenic rod bipolar cells were more strongly desensitized than control. This sensitivity reversal indicates that transducin translocation in rods enhances signaling to rod bipolar cells. The enhancement could not be explained by modulation of inner segment conductances or the voltage sensitivity of the synaptic Ca2+ current, suggesting interactions of transducin with the synaptic machinery. PMID:23836670

Majumder, Anurima; Pahlberg, Johan; Boyd, Kimberly K.; Kerov, Vasily; Kolandaivelu, Saravanan; Ramamurthy, Visvanathan; Sampath, Alapakkam P.; Artemyev, Nikolai O.

2013-01-01

345

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

346

Cathepsin-K immunoreactivity distinguishes MiTF\\/TFE family renal translocation carcinomas from other renal carcinomas  

Microsoft Academic Search

The microphthalmia transcription factor\\/transcription factor E (TFE)-family translocation renal cell carcinomas bear specific translocations that result in overexpression of TFE3 or TFEB. TFE3 fusion gene product overexpression occurs as consequence of different translocations involving chromosome Xp11.2, whereas TFEB overexpression is the result of the specific translocation t(6;11)(p21;q12), which fuses the Alpha gene to TFEB. Both TFE3 and TFEB are closely

G Martignoni; M Pea; S Gobbo; M Brunelli; F Bonetti; D Segala; Chin-Chen Pan; G Netto; C Doglioni; O Hes; P Argani; M Chilosi

2009-01-01

347

Beam induced backgrounds: CDF experience  

SciTech Connect

We summarize the experiences of the Collider Detector at Fermilab (CDF) experiment in the presence of backgrounds originating from the counter circulating beams in the Fermilab Tevatron. These backgrounds are measured and their sources identified. Finally, we outline the strategies employed to reduce the effects of these backgrounds on the experiment.

Tesarek, R.J.; /Fermilab

2008-05-01

348

Cis-trans dynamical asymmetry in driven polymer translocation.  

PubMed

During polymer translocation driven by, e.g., voltage drop across a nanopore, the segments in the cis side are incessantly pulled into the pore, which are then pushed out of it into the trans side. This pulling and pushing of polymer segments are described in the continuum level by nonlinear transport processes known, respectively, as fast and slow diffusions. By matching solutions of both sides through the mass conservation across the pore, we provide a physical basis for the cis and trans dynamical asymmetry, a feature repeatedly reported in recent numerical simulations. We then predict how the total driving force is dynamically allocated between cis (pulling) and trans (pushing) sides, demonstrating that the trans-side event adds a weak finite-chain length effect to the dynamical scaling. PMID:24229205

Saito, Takuya; Sakaue, Takahiro

2013-10-01

349

Measurement of outward translocation of phospholipids across human erythrocyte membrane.  

PubMed Central

Spin-labeled phospholipids have been used to study the outside----inside and inside----outside transport of phospholipids across the human erythrocyte membrane at 37 degrees C. As already shown, inward transport is much faster for aminophospholipids than for phosphatidylcholine. In addition, we show here that outward transport of the phosphatidylserine and phosphatidylethanolamine analogues is three to four times faster than that of phosphatidylcholine. Magnesium depletion of the erythrocytes considerably decreases the outward rate of both aminophospholipids to values close to that of phosphatidylcholine. These results suggest that the outward aminophospholipid translocation is, at least partly, protein mediated. The protein involved could be identical to the inward Mg-ATP-dependent aminophospholipid carrier. PMID:3137572

Bitbol, M; Devaux, P F

1988-01-01

350

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

351

Opposite translocation of long and short oligomers through a nanopore  

E-print Network

We consider elongated cylindrical particles, modeling e.g. DNA fragments or nano-rods, while translocating under the action of an externally applied voltage through a solid state nanopore. Particular emphasis is put on the concomitant potential energy landscape, encountered by the particle on its passage through the pore due to the complex interplay of various electrohydrodynamic effects beyond the realm of small Debye lengths. We find that the net potential energy difference across the membrane may be of opposite sign for short and long particles of equal diameters and charge densities (e.g. oligomers). Thermal noise thus leads to biased diffusion through the pore into opposite directions. By means of an additional membrane gate electrode it is even possible to control the specific particle length at which this transport inversion occurs.

Getfert, Sebastian; Reimann, Peter

2013-01-01

352

Opposite translocation of long and short oligomers through a nanopore  

E-print Network

We consider elongated cylindrical particles, modeling e.g. DNA fragments or nano-rods, while translocating under the action of an externally applied voltage through a solid state nanopore. Particular emphasis is put on the concomitant potential energy landscape, encountered by the particle on its passage through the pore due to the complex interplay of various electrohydrodynamic effects beyond the realm of small Debye lengths. We find that the net potential energy difference across the membrane may be of opposite sign for short and long particles of equal diameters and charge densities (e.g. oligomers). Thermal noise thus leads to biased diffusion through the pore into opposite directions. By means of an additional membrane gate electrode it is even possible to control the specific particle length at which this transport inversion occurs.

Sebastian Getfert; Thomas Töws; Peter Reimann

2013-07-12

353

Requirements for a conservative protein translocation pathway in chloroplasts.  

PubMed

The chloroplast inner envelope translocon subunit Tic110 is imported via a soluble stromal translocation intermediate. In this study an in-organellar import system is established which allows for an accumulation of this intermediate in order to analyze its requirements for reexport. All results demonstrate that the re-export of Tic110 from the soluble intermediate stage into the inner envelope requires ATP hydrolysis, which cannot be replaced by other NTPs. Furthermore, the molecular chaperone Hsp93 seems prominently involved in the reexport pathway of Tic110, because other stromal intermediates like that of the oxygen evolving complex subunit OE33 (iOE33) en route to the thylakoid lumen interacts preferentially with Hsp70. PMID:17507010

Vojta, Lea; Soll, Jürgen; Bölter, Bettina

2007-06-12

354

DNA translocation through an array of kinked nanopores  

SciTech Connect

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.; Brinker, C. Jeffrey (UNM); (Sandia); (UIUC); (Purdue)

2010-08-06

355

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

356

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

357

Identication and expression of alternatively spliced aryl hydrocarbon nuclear translocator 2 (ARNT2) cDNAs from zebrash with  

E-print Network

hydrocarbon receptor nuclear translocator (ARNT) is a member of the PAS family of transcription factorsIdenti¢cation and expression of alternatively spliced aryl hydrocarbon nuclear translocator 2 (ARNT hydrocarbon receptor/aryl hydrocarbon receptor nuclear translocator (AhR/ARNT) signaling pathways

Tullos, Desiree

358

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

Microsoft Academic Search

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

James D. Tucker

2008-01-01

359

In utero origin of t(8;21) AML1-ETO translocations in childhood acute myeloid leukemia  

E-print Network

NEOPLASIA In utero origin of t(8;21) AML1-ETO translocations in childhood acute myeloid leukemia Greaves Recent reports have established the prena- tal origin of leukemia translocations and resultant leukemia (AML). The t(8;21) AML1- ETO translocations were sequenced at the genomic level in 10 diagnostic

California at Berkeley, University of

360

Microwave Frequency Polarizers  

NASA Technical Reports Server (NTRS)

This article describes the fabrication and analysis of microwave frequency polarizing grids. The grids are designed to measure polarization from the cosmic microwave background. It is effective in the range of 500 to 1500 micron wavelength. It is cryogenic compatible and highly robust to high load impacts. Each grid is fabricated using an array of different assembly processes which vary in the types of tension mechanisms to the shape and size of the grids. We provide a comprehensive study on the analysis of the grids' wire heights, diameters, and spacing.

Ha, Vien The; Mirel, Paul; Kogut, Alan J.

2013-01-01

361

Background issues for defensive interceptors  

SciTech Connect

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 motions and backgrounds give signal to clutter ratios too low to be useful. Clutter leakage due to line-of-sight drift can be reduced by stabilizing the line of sight around the background clutter itself. Current interceptors have detector arrays large enough for operation independent of nuclear backgrounds in their fields of view. 6 refs., 2 figs.

Canavan, G.H.

1991-03-01

362

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

363

Slow CCL2-dependent translocation of biopersistent particles from muscle to brain  

PubMed Central

Background Long-term biodistribution of nanomaterials used in medicine is largely unknown. This is the case for alum, the most widely used vaccine adjuvant, which is a nanocrystalline compound spontaneously forming micron/submicron-sized agglomerates. Although generally well tolerated, alum is occasionally detected within monocyte-lineage cells long after immunization in presumably susceptible individuals with systemic/neurologic manifestations or autoimmune (inflammatory) syndrome induced by adjuvants (ASIA). Methods On the grounds of preliminary investigations in 252 patients with alum-associated ASIA showing both a selective increase of circulating CCL2, the major monocyte chemoattractant, and a variation in the CCL2 gene, we designed mouse experiments to assess biodistribution of vaccine-derived aluminum and of alum-particle fluorescent surrogates injected in muscle. Aluminum was detected in tissues by Morin stain and particle induced X-ray emission) (PIXE) Both 500 nm fluorescent latex beads and vaccine alum agglomerates-sized nanohybrids (Al-Rho) were used. Results Intramuscular injection of alum-containing vaccine was associated with the appearance of aluminum deposits in distant organs, such as spleen and brain where they were still detected one year after injection. Both fluorescent materials injected into muscle translocated to draining lymph nodes (DLNs) and thereafter were detected associated with phagocytes in blood and spleen. Particles linearly accumulated in the brain up to the six-month endpoint; they were first found in perivascular CD11b+ cells and then in microglia and other neural cells. DLN ablation dramatically reduced the biodistribution. Cerebral translocation was not observed after direct intravenous injection, but significantly increased in mice with chronically altered blood-brain-barrier. Loss/gain-of-function experiments consistently implicated CCL2 in systemic diffusion of Al-Rho particles captured by monocyte-lineage cells and in their subsequent neurodelivery. Stereotactic particle injection pointed out brain retention as a factor of progressive particle accumulation. Conclusion Nanomaterials can be transported by monocyte-lineage cells to DLNs, blood and spleen, and, similarly to HIV, may use CCL2-dependent mechanisms to penetrate the brain. This occurs at a very low rate in normal conditions explaining good overall tolerance of alum despite its strong neurotoxic potential. However, continuously escalating doses of this poorly biodegradable adjuvant in the population may become insidiously unsafe, especially in the case of overimmunization or immature/altered blood brain barrier or high constitutive CCL-2 production. PMID:23557144

2013-01-01

364

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

365

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

366

Adhesins and Host Serum Factors Drive Yop Translocation by Yersinia into Professional Phagocytes during Animal Infection  

PubMed Central

Yersinia delivers Yops into numerous types of cultured cells, but predominantly into professional phagocytes and B cells during animal infection. The basis for this cellular tropism during animal infection is not understood. This work demonstrates that efficient and specific Yop translocation into phagocytes by Yersinia pseudotuberculosis (Yptb) is a multi-factorial process requiring several adhesins and host complement. When WT Yptb or a multiple adhesin mutant strain, ?ail?inv?yadA, colonized tissues to comparable levels, ?ail?inv?yadA translocated Yops into significantly fewer cells, demonstrating that these adhesins are critical for translocation into high numbers of cells. However, phagocytes were still selectively targeted for translocation, indicating that other bacterial and/or host factors contribute to this function. Complement depletion showed that complement-restricted infection by ?ail?inv?yadA but not WT, indicating that adhesins disarm complement in mice either by prevention of opsonophagocytosis or by suppressing production of pro-inflammatory cytokines. Furthermore, in the absence of the three adhesins and complement, the spectrum of cells targeted for translocation was significantly altered, indicating that Yersinia adhesins and complement direct Yop translocation into neutrophils during animal infection. In summary, these findings demonstrate that in infected tissues, Yersinia uses adhesins both to disarm complement-dependent killing and to efficiently translocate Yops into phagocytes. PMID:23818844

Maldonado-Arocho, Francisco J.; Green, Carlos; Fisher, Michael L.; Paczosa, Michelle K.; Mecsas, Joan

2013-01-01

367

A voltage-gated pore for translocation of tRNA  

SciTech Connect

Highlights: •A tRNA translocating complex was assembled from purified proteins. •The complex translocates tRNA at a membrane potential of ?60 mV. •Translocation requires Cys and His residues in the Fe–S center of RIC6 subunit. -- Abstract: Very little is known about how nucleic acids are translocated across membranes. The multi-subunit RNA Import Complex (RIC) from mitochondria of the kinetoplastid protozoon Leishmania tropica induces translocation of tRNAs across artificial or natural membranes, but the nature of the translocation pore remains unknown. We show that subunits RIC6 and RIC9 assemble on the membrane in presence of subunit RIC4A to form complex R3. Atomic Force Microscopy of R3 revealed particles with an asymmetric surface groove of ?20 nm rim diameter and ?1 nm depth. R3 induced translocation of tRNA into liposomes when the pH of the medium was lowered to ?6 in the absence of ATP. R3-mediated tRNA translocation could also be induced at neutral pH by a K{sup +} diffusion potential with an optimum of 60–70 mV. Point mutations in the Cys{sub 2}–His{sub 2} Fe-binding motif of RIC6, which is homologous to the respiratory Complex III Fe–S protein, abrogated import induced by low pH but not by K{sup +} diffusion potential. These results indicate that the R3 complex forms a pore that is gated by a proton-generated membrane potential and that the Fe–S binding region of RIC6 has a role in proton translocation. The tRNA import complex of L. tropica thus contains a novel macromolecular channel distinct from the mitochondrial protein import pore that is apparently involved in tRNA import in some species.

Koley, Sandip; Adhya, Samit, E-mail: nilugrandson@gmail.com

2013-09-13

368

Translocation Down syndrome in Ohio 1970-1981: epidemiologic and cytogenetic factors and mutation rate estimates.  

PubMed Central

Sixteen hundred eighty-eight Down syndrome live births, including 65 (5.2%) translocations, were ascertained in Ohio between 1970 and 1981. Translocations of known origin were 24.4% maternal, 2.2% paternal, and 73.3% de novo. Translocation subtypes were 14/21 (45.7%), 15/21 (2.9%), 21/21 (40.0%), 21/22 (2.9%), and other (8.5%). Among 14/21 translocations, 33.3% were maternal in origin and 66.7% were de novo, while 100% of 21/21 translocations were de novo. No differences were found when the maternal- and paternal-age distributions of all translocations or various translocation subsets were compared with the live-birth control distributions. However, mean maternal and paternal ages of de novo translocations were significantly lower than that of the live-birth controls. Ohio data showed the average maternal age of de novo D/21 cases to be significantly lower than the control. Ages of both parents of de novo G/21 cases and paternal age of D/21 cases were not different from the control. De novo translocation mutation rate estimates were 0.8 X 10(-5) for 14/21, 1.2 X 10(-5) for 21/21, and 2.2 X 10(-5) overall. Ohio estimates (3.2 X 10(-5) for 1970-1972 and 1.4 X 10(-5) for 1973-1975) did not reflect the increase in mutation rate previously found in New York during 1973-1977. PMID:2945428

Pulliam, L H; Huether, C A

1986-01-01

369

Premature ovarian failure in a woman with a balanced 15;21 translocation: a case report  

PubMed Central

Introduction A case of premature ovarian failure with concomitant findings of Robertsonian translocation between 15 and 21 chromosomes is reported here. The aforementioned karyotypic aberration has not been reported in the context of premature ovarian failure to date. Case presentation We present a case of premature ovarian failure in a 27-year-old infertile Kurdish Iranian woman with a Robertsonian 15;21 translocation. Conclusions The diagnosis of premature ovarian failure of unknown etiology, but with karyotypic evidence of a balanced autosomal translocation, suggests the possible role of autosomal genes in the pathogenesis of ovarian follicular attrition. PMID:21714880

2011-01-01

370

Tourette syndrome in a pedigree with a 7;18 translocation: Identification of a YAC spanning the translocation breakpoint at 18q22.3  

SciTech Connect

Tourette syndrome is a neuropsychiatric disorder characterized by the presence of multiple, involuntary motor and vocal tics. Associated pathologies include attention deficit disorder and obsessive-compulsive disorder (OCD). Extensive linkage analysis based on an autosomal dominant mode of transmission with reduced penetrance has failed to show linkage with polymorphic markers, suggesting either locus heterogeneity or a polygenic origin for Tourette syndrome. An individual diagnosed with Tourette syndrome has been described carrying a constitutional chromosome translocation. Other family members carrying the translocation exhibit features seen in Tourette syndrome including motor tics, vocal tics, and OCD. Since the disruption of specific genes by a chromosomal rearrangement can elicit a particular phenotype, we have undertaken the physical mapping of the 7;18 translocation such that genes mapping at the site of the breakpoint can be identified and evaluated for a possible involvement in Tourette syndrome. Using somatic cell hybrids retaining either the der(7) or the der(18), a more precise localization of the breakpoints on chromosomes 7 and 18 have been determined. Furthermore, physical mapping has identified two YAC clones that span the translocation breakpoint on chromosome 18 as determined by FISH. These YAC clones will be useful for the eventual identification of genes that map to chromosomes 7 and 18 at the site of the translocation. 41 refs., 3 figs., 1 tab.

Boghosian-Sell, L.; Overhauser, J. [Thomas Jefferson Univ., Philadelphia, PA (United States); Comings, D.E. [City of Hope Medical Center, Duarte, CA (United States)

1996-11-01

371

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 people demonstrated at the National Congress in Brasilia, capital of Brazil, following the announcement in the 1990s in the midst of extensive protests in Brazil and around the world. On February 8, an indigenous

Milchberg, Howard

372

Background Check Summary Type Needs background check if began  

E-print Network

form. Background check is required if, 2) Upon receipt of form, HR BGC emails candidate a link Check Coordinator receives outcome; if candidate meets Yale policy, HR BGC notifies primary department; completes a Postdoc/Postgrad Background Check Request Form. 5) Upon receipt of this form, HR BGC emails

Haller, Gary L.

373

SIRT1 interacts with and protects glyceraldehyde-3-phosphate dehydrogenase (GAPDH) from nuclear translocation: Implications for cell survival after irradiation  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer SIRT1 serves to retain GAPDH in the cytosol, preventing GAPDH nuclear translocation. Black-Right-Pointing-Pointer When SIRT1 is depleted, GAPDH translocation occurs even in the absence of stress. Black-Right-Pointing-Pointer Upon irradiation, SIRT1 interacts with GAPDH. Black-Right-Pointing-Pointer SIRT1 prevents irradiation-induced nuclear translocation of GAPDH. Black-Right-Pointing-Pointer SIRT1 presence rather than activity is essential for inhibiting GAPDH translocation. -- Abstract: Upon apoptotic stimulation, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), a cytosolic enzyme normally active in glycolysis, translocates into the nucleus and activates an apoptotic cascade therein. In the present work, we show that SIRT1 prevents nuclear translocation of GAPDH via interaction with GAPDH. SIRT1 depletion triggered nuclear translocation of cytosolic GAPDH even in the absence of apoptotic stress. Such translocation was not, however, observed when SIRT1 enzymatic activity was inhibited, indicating that SIRT1 protein per se, rather than the deacetylase activity of the protein, is required to inhibit GAPDH translocation. Upon irradiation, SIRT1 prevented irradiation-induced nuclear translocation of GAPDH, accompanied by interaction of SIRT1 and GAPDH. Thus, SIRT1 functions to retain GAPDH in the cytosol, protecting the enzyme from nuclear translocation via interaction with these two proteins. This serves as a mechanism whereby SIRT1 regulates cell survival upon induction of apoptotic stress by means that include irradiation.

Joo, Hyun-Yoo [Division of Radiation Cancer Research, Korea Institute of Radiological and Medical Sciences, Seoul 139-706 (Korea, Republic of) [Division of Radiation Cancer Research, Korea Institute of Radiological and Medical Sciences, Seoul 139-706 (Korea, Republic of); Laboratory of Biochemistry, School of Life Sciences and Biotechnology, Korea University, Seoul 136-713 (Korea, Republic of); Woo, Seon Rang; Shen, Yan-Nan; Yun, Mi Yong; Shin, Hyun-Jin; Park, Eun-Ran; Kim, Su-Hyeon; Park, Jeong-Eun; Ju, Yeun-Jin; Hong, Sung Hee; Hwang, Sang-Gu [Division of Radiation Cancer Research, Korea Institute of Radiological and Medical Sciences, Seoul 139-706 (Korea, Republic of)] [Division of Radiation Cancer Research, Korea Institute of Radiological and Medical Sciences, Seoul 139-706 (Korea, Republic of); Cho, Myung-Haing [Laboratory of Toxicology, College of Veterinary Medicine, Seoul National University, Seoul 151-742 (Korea, Republic of)] [Laboratory of Toxicology, College of Veterinary Medicine, Seoul National University, Seoul 151-742 (Korea, Republic of); Kim, Joon, E-mail: joonkim@korea.ac.kr [Laboratory of Biochemistry, School of Life Sciences and Biotechnology, Korea University, Seoul 136-713 (Korea, Republic of)] [Laboratory of Biochemistry, School of Life Sciences and Biotechnology, Korea University, Seoul 136-713 (Korea, Republic of); Lee, Kee-Ho, E-mail: khlee@kirams.re.kr [Division of Radiation Cancer Research, Korea Institute of Radiological and Medical Sciences, Seoul 139-706 (Korea, Republic of)] [Division of Radiation Cancer Research, Korea Institute of Radiological and Medical Sciences, Seoul 139-706 (Korea, Republic of)

2012-08-10

374

Light-Dependent Translocation of Arrestin in Rod Photoreceptors is Signaled Through a Phospholipase C Cascade and Requires ATP  

PubMed Central

Partitioning of cellular components is a critical mechanism by which cells can regulate their activity. In rod photoreceptors, light induces a large-scale translocation of arrestin from the inner segments to the outer segments. The purpose of this project is to elucidate the signaling pathway necessary to initiate arrestin translocation to the outer segments and the mechanism for arrestin translocation. Mouse retinal organotypic cultures and eyes from transgenic Xenopus tadpoles expressing a fusion of GFP and rod arrestin were treated with both activators and inhibitors of proteins in the phosphoinositide pathway. Confocal microscopy was used to image the effects of the pharmacological agents on arrestin translocation in rod photoreceptors. Retinas were also depleted of ATP using potassium cyanide to assess the requirement for ATP in arrestin translocation. In this study, we demonstrate that components of the G-protein-linked phospholipase C (PLC) pathway play a role in initiating arrestin translocation. Our results show that arrestin translocation can be stimulated by activators of PLC and protein kinase C (PKC), and by cholera toxin in the absence of light. Arrestin translocation to the outer segments is significantly reduced by inhibitors of PLC and PKC. Importantly, we find that treatment with potassium cyanide inhibits arrestin translocation in response to light. Collectively, our results suggest that arrestin translocation is initiated by a G-protein-coupled cascade through PLC and PKC signaling. Furthermore, our results demonstrate that at least the initiation of arrestin translocation requires energy input. PMID:19887106

Orisme, Wilda; Li, Jian; Goldmann, Tobias; Bolch, Susan; Wolfrum, Uwe; Smith, W. Clay

2009-01-01

375

Muscle contraction increases carnitine uptake via translocation of OCTN2  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer Muscle contraction augmented carnitine uptake into rat hindlimb muscles. Black-Right-Pointing-Pointer An increase in carnitine uptake was due to an intrinsic clearance, not blood flow. Black-Right-Pointing-Pointer Histochemical analysis showed sarcolemmal OCTN2 was emphasized after contraction. Black-Right-Pointing-Pointer OCTN2 protein in sarcolemmal fraction was increased in contracting muscles. -- Abstract: Since carnitine plays an important role in fat oxidation, influx of carnitine could be crucial for muscle metabolism. OCTN2 (SLC22A5), a sodium-dependent solute carrier, is assumed to transport carnitine into skeletal muscle cells. Acute regulation of OCTN2 activity in rat hindlimb muscles was investigated in response to electrically induced contractile activity. The tissue uptake clearance (CL{sub uptake}) of L-[{sup 3}H]carnitine during muscle contraction was examined in vivo using integration plot analysis. The CL{sub uptake} of [{sup 14}C]iodoantipyrine (IAP) was also determined as an index of tissue blood flow. To test the hypothesis that increased carnitine uptake involves the translocation of OCTN2, contraction-induced alteration in the subcellular localization of OCTN2 was examined. The CL{sub uptake} of L-[{sup 3}H]carnitine in the contracting muscles increased 1.4-1.7-fold as compared to that in the contralateral resting muscles (p < 0.05). The CL{sub uptake} of [{sup 14}C]IAP was much higher than that of L-[{sup 3}H]carnitine, but no association between the increase in carnitine uptake and blood flow was obtained. Co-immunostaining of OCTN2 and dystrophin (a muscle plasma membrane marker) showed an increase in OCTN2 signal in the plasma membrane after muscle contraction. Western blotting showed that the level of sarcolemmal OCTN2 was greater in contracting muscles than in resting muscles (p < 0.05). The present study showed that muscle contraction facilitated carnitine uptake in skeletal muscles, possibly via the contraction-induced translocation of its specific transporter OCTN2 to the plasma membrane.

Furuichi, Yasuro [Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa (Japan)] [Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa (Japan); Sugiura, Tomoko; Kato, Yukio [Faculty of Pharmacy, Kanazawa University, Kanazawa (Japan)] [Faculty of Pharmacy, Kanazawa University, Kanazawa (Japan); Takakura, Hisashi [Faculty of Human Sciences, Kanazawa University, Kanazawa (Japan)] [Faculty of Human Sciences, Kanazawa University, Kanazawa (Japan); Hanai, Yoshiteru [Nagoya Institute of Technology, Nagoya (Japan)] [Nagoya Institute of Technology, Nagoya (Japan); Hashimoto, Takeshi [Ritsumeikan University, Kusatsu (Japan)] [Ritsumeikan University, Kusatsu (Japan); Masuda, Kazumi, E-mail: masuda@ed.kanazawa-u.ac.jp [Faculty of Human Sciences, Kanazawa University, Kanazawa (Japan)] [Faculty of Human Sciences, Kanazawa University, Kanazawa (Japan)

2012-02-24

376

A squid dynein isoform promotes axoplasmic vesicle translocation  

PubMed Central

Axoplasmic vesicles that translocate on isolated microtubules in an ATP- dependent manner have an associated ATP-binding polypeptide with a previously estimated relative molecular mass of 292 kD (Gilbert, S. P., and R. D. Sloboda. 1986. J. Cell Biol. 103:947-956). Here, data are presented showing that this polypeptide (designated H1) and another high molecular mass polypeptide (H2) can be isolated in association with axoplasmic vesicles or optic lobe microtubules. The H1 and H2 polypeptides dissociate from microtubules in the presence of MgATP and can be further purified by gel filtration chromatography. The peak fraction thus obtained demonstrates MgATPase activity and promotes the translocation of salt-extracted vesicles (mean = 0.87 microns/s) and latex beads (mean = 0.92 microns/s) along isolated microtubules. The H1 polypeptide binds [alpha 32P]8-azidoATP and is thermosoluble, but the H2 polypeptide does not share these characteristics. In immunofluorescence experiments with dissociated squid axoplasm, affinity-purified H1 antibodies yield a punctate pattern that corresponds to vesicle-like particles, and these antibodies inhibit the bidirectional movement of axoplasmic vesicles. H2 is cleaved by UV irradiation in the presence of MgATP and vanadate to yield vanadate- induced peptides of 240 and 195 kD, yet H1 does not cleave under identical conditions. These experiments also demonstrate that the actual relative molecular mass of the H1 and H2 polypeptides is approximately 435 kD. On sucrose density gradients, H1 and H2 sediment at 19-20 S, and negatively stained samples reveal particles comprised of two globular heads with stems that contact each other and extend to a common base. The results demonstrate that the complex purified is a vesicle-associated ATPase whose characteristics indicate that it is a squid isoform of dynein. Furthermore, the data suggest that this vesicle-associated dynein promotes membranous organelle motility during fast axoplasmic transport. PMID:2478567

1989-01-01

377

Ceramide dissociates 3'-phosphoinositide production from pleckstrin homology domain translocation.  

PubMed Central

Numerous hormones, cytokines and transforming oncogenes activate phosphoinositide 3-kinase (PI-3K), a lipid kinase that initiates signal transduction cascades regulating cellular proliferation, survival, protein synthesis and glucose metabolism. PI-3K catalyses the production of the 3'-phosphoinositides PtdIns(3,4)P(2) and PtdIns(3,4,5)P(3), which recruit downstream effector enzymes to the membrane via their pleckstrin homology (PH) domains. Recent studies have indicated that another signalling lipid, the sphingolipid ceramide, inhibits several PI-3K-dependent events, including insulin-stimulated glucose uptake and growth-factor-stimulated cell survival. Here we show that ceramide analogues specifically prevent the recruitment of the PtdIns(3,4,5)P(3)-binding proteins Akt/protein kinase B (PKB) or the general receptor for phosphoinositides-1 (GRP1). Specifically, the short-chain ceramide derivative C2-ceramide inhibited the platelet-derived growth factor (PDGF)-stimulated translocation of full-length Akt/PKB, as well as truncated proteins encoding only the PH domains of Akt/PKB or GRP1. C2-ceramide did not alter the membrane localization of the PH domain for phospholipase Cdelta, which preferentially binds PtdIns(4,5)P(2), nor did it affect the PDGF-stimulated production of PtdIns(3,4)P(2) or PtdIns(3,4,5)P(3). Interestingly, a glucosylceramide synthase inhibitor, 1-phenyl-2-decanoylamino-3-morpholinopropan-1-ol (PDMP), shown previously to increase intracellular ceramide concentrations without affecting PI-3K [Rani, Abe, Chang, Rosenzweig, Saltiel, Radin and Shayman (1995) J. Biol. Chem. 270, 2859-2867], recapitulated the inhibitory effects of C2-ceramide on PDGF-stimulated Akt/PKB phosphorylation. These studies indicate that ceramide prevents the translocation of certain PtdIns(3,4,5)P(3)-binding proteins, despite the presence of a full complement of PtdIns(3,4)P(2) or PtdIns(3,4,5)P(3). Furthermore, these findings suggest a mechanism by which stimuli that induce ceramide synthesis could negate the fundamental signalling pathways initiated by PI-3K. PMID:11171115

Stratford, S; DeWald, D B; Summers, S A

2001-01-01

378

Background  

E-print Network

Chronic Obstructive Pulmonary Disease (COPD) is a lung disease characterized by chronic inflammation of the airways. The primary risk factor for COPD is cigarette smoking; other risk factors include long-term exposure to environmental lung irritants and certain genetic conditions. 1 COPD is also found to be associated with significant comorbidities, including heart disease, kidney disease, asthma, and arthritis, as well as various types of cancer. 2 A large-scale study, using electronic primary care records of more than 1.2 million patients, found that COPD was associated with significantly higher odds of cardiovascular disease, stroke, and diabetes mellitus. 3 There is growing evidence to suggest that systemic inflammation is potentially a common pathway for multiple chronic conditions found among adults with COPD. 4 COPD can adversely affect one’s quality of life (QoL). Depression has often been associated with COPD. In an observational study of 35,722 patients with COPD, the incidence rate of new-onset diagnoses of depression was significantly higher in the COPD group, compared to the COPD-free group. 5 Sleeping difficulties and physical inactivity are also common among those with COPD. 6,7 The aim of this report is to enumerate the prevalence and risk of secondary chronic diseases, and poor quality of life, among North Carolina adults with COPD.

unknown authors

2011-01-01

379

Background  

NASA Technical Reports Server (NTRS)

An analysis was made of the UF6 fueled gas core reactor as a function of cavity reactor criticality and fluid mechanics tests, investigations of uranium optical emission spectra, and radiant heat transfer power plant studies. Data are also given on nuclear and thermodynamic cycle analysis.

1976-01-01

380

Background  

E-print Network

• Requirement to control a team of 5-a-side soccer playing robots • Due to camera and communication time delays it is very difficult to control a mobile robot moving faster than 1 m/sec • Robots currently use an independent term PID controller • Investigate FLCs as an alternative

unknown authors

381

Estimating stochastic gravitational wave backgrounds with the Sagnac calibration  

NASA Astrophysics Data System (ADS)

Armstrong et al. have recently presented new ways of combining signals to precisely cancel laser frequency noise in spaceborne interferometric gravitational wave detectors such as LISA. One of these combinations, which we will call the ``symmetrized Sagnac observable,'' is much less sensitive to external signals at low frequencies than other combinations, and thus can be used to determine the instrumental noise level. We note here that this calibration of the instrumental noise permits smoothed versions of the power spectral density of stochastic gravitational wave backgrounds to be determined with considerably higher accuracy than earlier estimates, at frequencies where one type of noise strongly dominates and is not substantially correlated between the six main signals generated by the antenna. We illustrate this technique by analyzing simple estimators of gravitational wave background power, and show that the instrumental sensitivity to broad-band backgrounds at some frequencies can be improved by a significant factor of as much as (f?/2)1/2 in spectral density h2rms over the standard method, where f denotes frequency and ? denotes integration time, comparable to that which would be achieved by cross-correlating two separate antennas. The applications of this approach to studies of astrophysical gravitational wave backgrounds generated after recombination and to searches for a possible primordial background are discussed. With appropriate mission design, this technique allows an estimate of the cosmological background from extragalactic white dwarf binaries and will enable LISA to reach the astrophysical confusion noise of compact binaries from about 0.1 mHz to about 20 mHz. In a smaller-baseline follow-on mission, the technique allows several orders of magnitude improvement in sensitivity to primordial backgrounds up to about 1 Hz.

Hogan, Craig J.; Bender, Peter L.

2001-09-01

382

Radiative emission of neutrino pair free of quantum electrodynamic backgrounds  

E-print Network

A scheme of quantum electrodynamic (QED) background-free radiative emission of neutrino pair (RENP) is proposed in order to achieve precision determination of neutrino properties so far not accessible. The important point for the background rejection is the fact that the dispersion relation between wave vector along propagating direction in wave guide (and in a photonic-crystal type fiber) and frequency is modified by a discretized non-vanishing effective mass. This effective mass acts as a cutoff of allowed frequencies, and one may select the RENP photon energy region free of all macro-coherently amplified QED processes by choosing the cutoff larger than the mass of neutrinos.

Yoshimura, M; Tanaka, M

2015-01-01

383

Background: Extratropical Cyclones and NWP  

E-print Network

Chapter 2 Background: Extratropical Cyclones and NWP 2.1 Introduction This chapter provides background information about extratropical cyclones, numerical weather prediction (NWP) and ensemble prediction. It is organised as follows. Section 2.2 discusses extratropical cyclones and begins with a brief

Froude, Lizzie

384

Cosmic Superstring Scattering in Backgrounds  

E-print Network

We generalize the calculation of cosmic superstring reconnection probability to non-trivial backgrounds. This is done by modeling cosmic strings as wound tachyon modes in the 0B theory, and the spacetime effective action is then used to couple this to background fields. Simple examples are given including trivial and warped compactifications. Generalization to $(p,q)$ strings is discussed.

Mark G. Jackson

2006-08-22

385

Background reduction in cryogenic detectors  

SciTech Connect

This paper discusses the background reduction and rejection strategy of the Cryogenic Dark Matter Search (CDMS) experiment. Recent measurements of background levels from CDMS II at Soudan are presented, along with estimates for future improvements in sensitivity expected for a proposed SuperCDMS experiment at SNOLAB.

Bauer, Daniel A.; /Fermilab

2005-04-01

386

Background events in microchannel plates  

NASA Technical Reports Server (NTRS)

Measurements have been made to assess the characteristics and origins of background events in microchannel plates (MCPs). An overall background rate of about 0.4 events/sq cm persec has been achieved consistently for MCPs that have been baked and scrubbed. The temperature and gain of the MCPs are found to have no significant effect on the background rate. Detection of 1.46-MeV gamma rays from the MCP glass confirms the presence of K-40, with a concentration of 0.0007 percent, in MCP glass. It is shown that beta decay from K-40 is sufficient to cause the background rate and spectrum observed. Anticoincidence measurements indicate the the background rate caused by cosmic ray interactions is small (less than 0.016 events/sq cm per sec).

Siegmund, O. H. W.; Vallerga, J.; Wargelin, B.

1988-01-01

387

mRNA Translocation Occurs During the Second Step of Ribosomal Intersubunit Rotation  

PubMed Central

During protein synthesis, mRNA and tRNA undergo coupled translocation through the ribosome in a process that is catalyzed by elongation factor EF-G. Based on cryo-EM reconstructions, counterclockwise and clockwise rotational movements between the large and small ribosomal subunits have been implicated in a proposed ratcheting mechanism to drive the unidirectional movement of translocation. We have used a combination of two fluorescence-based approaches to study the timing of these events: Intersubunit FRET measurements to observe relative rotational movement of the subunits and a fluorescence quenching assay to monitor translocation of mRNA. Binding of EF-G·GTP first induces rapid counterclockwise intersubunit rotation, followed by a slower, clockwise reversal of the rotational movement. Comparison of the rates of these movements reveals that mRNA translocation occurs during the second, clockwise rotation event, corresponding to the transition from the hybrid state to the classical state. PMID:21399643

Ermolenko, Dmitri N.; Noller, Harry F.

2010-01-01

388

Disease dynamics during wildlife translocations: disruptions to the host population and potential  

E-print Network

complications due to disease (reviewed in Cunningham, 1996; Kock et al., 2010)Disease dynamics during wildlife translocations: disruptions to the host population and potential Research Center, U.S. Geological Survey, Henderson, NV, USA 2 Center for Infectious Disease Dynamics

Bansal, Shweta

389

Investigating the translocation of lambda-DNA molecules through PDMS nanopores  

E-print Network

We investigate the translocation of ?-DNA molecules through resistive-pulse polydimethylsiloxane (PDMS) nanopore sensors. Single molecules of ?-DNA were detected as a transient current increase due to the effect of DNA ...

Karnik, Rohit N.

390

Crystal Structures of EF-G-Ribosome Complexes Trapped in Intermediate States of Translocation  

PubMed Central

Translocation of mRNA and tRNA through the ribosome is a crucial step in protein synthesis, whose mechanism is not yet understood. The crystal structures of three Thermus ribosome·tRNA·mRNA·EF-G complexes trapped with GDPNP or fusidic acid reveal conformational changes occurring during intermediate states of translocation, including large-scale rotation of the 30S subunit head and body. In all complexes, the tRNA acceptor ends occupy the 50S subunit E site, while their anticodon stem-loops move with the head of the 30S subunit to positions between the P and E sites, forming chimeric intermediate states. Two universally conserved bases of 16S rRNA that intercalate between bases of the mRNA may act as “pawls” of a translocational ratchet. These findings provide new insights into the molecular mechanism of ribosomal translocation. PMID:23812722

Zhou, Jie; Lancaster, Laura; Donohue, John Paul; Noller, Harry F.

2014-01-01

391

Reciprocal translocations in man. 3:1 Meiotic disjunction resulting in 47- or 45-chromosome offspring.  

PubMed Central

Five cases of chromosome imbalance resulting from 3:1 disjunction of reciprocal translocations are described. A review of the literature suggests this phenomenon is more common than has previously been recognized. Images PMID:123589

Lindenbaum, R H; Bobrow, M

1975-01-01

392

SecA-mediated targeting and translocation of secretory proteins Katerina E. Chatzi a,c  

E-print Network

. Secretion is an essential process that localizes hydrolytic enzymes, motility elements, electron chain to mechanical work and translocates preproteins through the SecYEG channel. SecA is a highly dynamic enzyme

Economou, Tassos

393

Effect of charge patterns along a solid-state nanopore on polyelectrolyte translocation  

NASA Astrophysics Data System (ADS)

We investigate the effectiveness of charge patterns along a nanopore on translocation dynamics of a flexible polyelectrolyte. We perform a three dimensional Langevin dynamics simulation of a uniformly charged flexible polyelectrolyte translocating under uniform external electric field through a solid-state nanopore. We maintain the total charge along the pore to be constant, while varying its distribution by placing alternate charged and uncharged sections of different lengths along the pore length. Longest average translocation time is observed for a pattern corresponding to an optimum section length, with a major delay in the translocation time during the pore ejection stage. This optimum section length is independent of lengths of polyelectrolyte and pore within the range studied. A theory based on the Fokker-Planck formalism is found to successfully describe the observed trends with reasonable quantitative agreement.

Katkar, H. H.; Muthukumar, M.

2014-04-01

394

The antibiotic viomycin traps the ribosome in an intermediate state of translocation.  

PubMed

During protein synthesis, transfer RNA and messenger RNA undergo coupled translocation through the ribosome's A, P and E sites, a process catalyzed by elongation factor EF-G. Viomycin blocks translocation on bacterial ribosomes and is believed to bind at the subunit interface. Using fluorescent resonance energy transfer and chemical footprinting, we show that viomycin traps the ribosome in an intermediate state of translocation. Changes in FRET efficiency show that viomycin causes relative movement of the two ribosomal subunits indistinguishable from that induced by binding of EF-G with GDPNP. Chemical probing experiments indicate that viomycin induces formation of a hybrid-state translocation intermediate. Thus, viomycin inhibits translation through a unique mechanism, locking ribosomes in the hybrid state; the EF-G-induced 'ratcheted' state observed by cryo-EM is identical to the hybrid state; and, since translation is viomycin sensitive, the hybrid state may be present in vivo. PMID:17515906

Ermolenko, Dmitri N; Spiegel, P Clint; Majumdar, Zigurts K; Hickerson, Robyn P; Clegg, Robert M; Noller, Harry F

2007-06-01

395

SYSTEMIC TRANSLOCATION OF PARTICULATE MATTER-ASSOCIATED METALS FOLLOWING A SINGLE INTRATRACHEAL INSTILLATION IN RATS  

EPA Science Inventory

Respirable ambient particulate matter (PM) exposure has been associated with an increased risk of cardiovascular disease. Direct translocation of PM associated metals from the lungs into systemic circulation may be partly responsible. We measured elemental content of lungs, pla...

396

A mentally retarded child with a translocation involving chromosomes 12 and 19.  

PubMed

This report concerns a de novo reciprocal translocation between the long arms of the chromosomes 12 and 19 in a mentally retarded child with bilateral radioulnar synostosis, agenesis of the corpus callosum, and several minor congenital malformations. PMID:1142383

Histinx, T W; Gabreëls, F J; Rutten, F J; Korten, I I; Scheres, J M; Joosten, E M

1975-06-01

397

Human Immunoglobulin Heavy Chain Genes Map to a Region of Translocations in Malignant B Lymphocytes  

Microsoft Academic Search

A human immunoglobulin heavy chain (gamma 4) gene is mapped by chromosome hybridization in situ. This gene is located at band 14q32, a site commonly involved in a chromosomal translocation characteristic of malignant B cells.

Ilan R. Kirsch; Cynthia C. Morton; Kenneth Nakahara; Philip Leder

1982-01-01

398

Assessing the benefits and risks of translocations in changing environments: a genetic perspective  

PubMed Central

Translocations are being increasingly proposed as a way of conserving biodiversity, particularly in the management of threatened and keystone species, with the aims of maintaining biodiversity and ecosystem function under the combined pressures of habitat fragmentation and climate change. Evolutionary genetic considerations should be an important part of translocation strategies, but there is often confusion about concepts and goals. Here, we provide a classification of translocations based on specific genetic goals for both threatened species and ecological restoration, separating targets based on ‘genetic rescue’ of current population fitness from those focused on maintaining adaptive potential. We then provide a framework for assessing the genetic benefits and risks associated with translocations and provide guidelines for managers focused on conserving biodiversity and evolutionary processes. Case studies are developed to illustrate the framework. PMID:22287981

Weeks, Andrew R; Sgro, Carla M; Young, Andrew G; Frankham, Richard; Mitchell, Nicki J; Miller, Kim A; Byrne, Margaret; Coates, David J; Eldridge, Mark D B; Sunnucks, Paul; Breed, Martin F; James, Elizabeth A; Hoffmann, Ary A

2011-01-01

399

Early microbial translocation blockade reduces SIV-mediated inflammation and viral replication  

PubMed Central

Damage to the intestinal mucosa results in the translocation of microbes from the intestinal lumen into the circulation. Microbial translocation has been proposed to trigger immune activation, inflammation, and coagulopathy, all of which are key factors that drive HIV disease progression and non-HIV comorbidities; however, direct proof of a causal link is still lacking. Here, we have demonstrated that treatment of acutely SIV-infected pigtailed macaques with the drug sevelamer, which binds microbial lipopolysaccharide in the gut, dramatically reduces immune activation and inflammation and slightly reduces viral replication. Furthermore, sevelamer administration reduced coagulation biomarkers, confirming the contribution of microbial translocation in the development of cardiovascular comorbidities in SIV-infected nonhuman primates. Together, our data suggest that early control of microbial translocation may improve the outcome of HIV infection and limit noninfectious comorbidities associated with AIDS. PMID:24837437

Kristoff, Jan; Haret-Richter, George; Ma, Dongzhu; Ribeiro, Ruy M.; Xu, Cuiling; Cornell, Elaine; Stock, Jennifer L.; He, Tianyu; Mobley, Adam D.; Ross, Samantha; Trichel, Anita; Wilson, Cara; Tracy, Russell; Landay, Alan; Apetrei, Cristian; Pandrea, Ivona

2014-01-01

400

RNA translocation between parasitic plants and their hosts.  

PubMed

Recent research indicates that RNA translocation occurs between certain parasitic plant species and their hosts. The movement of at least 27 mRNAs has been demonstrated between hosts and Cuscuta pentagona Engelm., with the largest proportion of these being regulatory genes. Movement of RNAi signals has been documented from hosts to the parasites Triphysaria versicolor (Frisch & CA Mey) and Orobanche aegyptiaca (Pers.), demonstrating that the regulation of genes in one species can be influenced by transfer of RNA signals through a parasitic association. This review considers the implications of these findings in light of present understanding of host-parasite connections and the growing body of evidence that RNAs are able to act as signal molecules that convey regulatory information in a cell- and tissue-specific manner. Together, this suggests that parasitic plants can exchange RNAs with their hosts, and that this may be part of the coordinated growth and development that occurs during the process of parasitism. This phenomenon offers promise for new insights into parasitic plants, and new opportunities for the control of parasitic weeds. PMID:19253417

Westwood, James H; Roney, Jeannine K; Khatibi, Piyum A; Stromberg, Verlyn K

2009-05-01

401

DNA translocation through graphene nanopores: a first-principles study  

NASA Astrophysics Data System (ADS)

With first-principles transport simulation, a biosensor device built from a graphene nanoribbon containing a nanopore is designed for DNA sequencing. The four DNA nucleobases can be distinguished from one another by detecting the transverse-currents of this device. To investigate the transport properties and mechanisms of such a device, we examine the motion effects of nucleobases. The analysis of the transmission spectra and frontier orbital energy shows that the transverse-currents variation of the device strongly results from the long-range interaction between nucleobases and the device. This interaction makes transverse-currents ultra-sensitive to the molecule inside the pore. By rotating the nucleotides inside the pore, the transverse-currents of the device vary along with the changes of molecular orientation. Due to the long-range interaction, when nucleobases chain translocates through nanopore of the device, the influences of adjacent nucleobases on transverse-currents cannot be ignored. These novel effects of nucleobases on the transport capacity of the device provide some theoretical guidance for the design of graphene-based nanopore sensor devices.

Peng, Shenglin; Yang, Zhixiong; Ni, Xiang; Zhang, Hua; Ouyang, Jun; Fangping, Ouyang

2014-03-01

402

Role of the macrophage in the translocation of intestinal bacteria.  

PubMed

To clarify the role of the macrophage in the translocation of intestinal bacteria, groups (n = 10) of Swiss Webster mice (Immunocompetent) and C3H/HeJ mice (macrophage defective) were given bacitracin/streptomycin in their drinking water to eliminate the majority of the intestinal microflora. These mice were then "monoassociated" with a streptomycin-resistant strain of Escherichia coli. Forty-eight hours later, E coli was present in all animals at a concentration of 10(11)/g of cecum. In four separate experiments, E coli was recovered from 100% of the mesenteric lymph nodes (MLNs) of the immunocompetent Swiss Webster mice and from 10%, 40%, 30%, and 50% of the MLNs of macrophage-defective C3H/HeJ mice. Swiss Webster mice were then similarly monoassociated by antibiotic decontamination followed by administration of antibiotic-resistant, fluorescein-labeled E coli in their drinking water; cohort groups of mice were given fluorescein-labeled latex beads (1 micron in diameter) in their drinking water. Two, four, and 11 days later, the MLNs were removed and single cell suspensions were analyzed in the fluorescence-activated cell sorter. The fluorescein label was detected exclusively in the macrophage (esterase-positive) population. These results support the hypothesis that intestinal macrophages may play a key role in the transport of intestinal particles (including bacteria) into extraintestinal sites. PMID:3541854

Wells, C L; Maddaus, M A; Simmons, R L

1987-01-01

403

DNA Translocation through Hydrophilic Nanopore in Hexagonal Boron Nitride  

PubMed Central

Ultra-thin solid-state nanopore with good wetting property is strongly desired to achieve high spatial resolution for DNA sequencing applications. Atomic thick hexagonal boron nitride (h-BN) layer provides a promising two-dimensional material for fabricating solid-state nanopores. Due to its good oxidation resistance, the hydrophilicity of h-BN nanopore device can be significantly improved by UV-Ozone treatment. The contact angle of a KCl-TE droplet on h-BN layer can be reduced from 57° to 26° after the treatment. Abundant DNA translocation events have been observed in such devices, and strong DNA-nanopore interaction has been revealed in pores smaller than 10?nm in diameter. The 1/f?noise level is closely related to the area of suspended h-BN layer, and it is significantly reduced in smaller supporting window. The demonstrated performance in h-BN nanopore paves the way towards base discrimination in a single DNA molecule. PMID:24256703

Zhou, Zhi; Hu, Ying; Wang, Hao; Xu, Zhi; Wang, Wenlong; Bai, Xuedong; Shan, Xinyan; Lu, Xinghua

2013-01-01

404

Translocation of CIDEC in hepatocytes depends on fatty acids.  

PubMed

The CIDEC protein is located in lipid droplets (LDs) and the endoplasmic reticulum (ER) and is induced in fat deposition. However, the binding domain, the functional domain and the underlying mechanism of CIDEC in stimulating lipid accumulation remain unclear. Here, we investigated the subcellular localization and function of pig CIDEC and confirmed CIDEC promotes unilocular development of LDs, reduces the specific surface area (SSA) of LDs and stimulates lipid accumulation in HepG2 cells. By analyzing a series of CIDEC mutants, we showed the N-domain (1-173 amino acid) is involved in LD localization and the C-domain (174-238 amino acid) is necessary for LD fusion. Further analysis indicated that the 106-173 amino acid region includes an ER-binding domain. Moreover, CIDEC stayed in the ER under lipid-deficient conditions and translocated to LDs under fatty acid stimulation suggesting that localization of CIDEC in the ER is before the LD. Our data indicated additional fatty acids stimulated hepatic CIDEC expression and an increasing level of CIDEC induced hepatic LD fusion and lipid accumulation. Our work suggests that CIDEC protects LDs by decreasing the SSA of LDs and is involved in the regulation of hepatic lipid deposition. PMID:25255829

Li, Hongqiang; Chen, Ao; Shu, Le; Yu, Xiaolan; Gan, Li; Zhou, Lei; Yang, Zaiqing

2014-11-01

405

High-performance analysis of single interphase cells with custom DNA probes spanning translocation break points  

NASA Astrophysics Data System (ADS)

The chromatin organization of interphase cell nuclei, albeit an object of intense investigation, is only poorly understood. In the past, this has hampered the cytogenetic analysis of tissues derived from specimens where only few cells were actively proliferating or a significant number of metaphase cells could be obtained by induction of growth. Typical examples of such hard to analyze cell systems are solid tumors, germ cells and, to a certain extent, fetal cells such as amniocytes, blastomeres or cytotrophoblasts. Balanced reciprocal translocations that do not disrupt essential genes and thus do not led to disease symptoms exit in less than one percent of the general population. Since the presence of translocations interferes with homologue pairing in meiosis, many of these individuals experience problems in their reproduction, such as reduced fertility, infertility or a history of spontaneous abortions. The majority of translocation carriers enrolled in our in vitro fertilization (IVF) programs carry simple translocations involving only two autosomes. While most translocations are relatively easy to spot in metaphase cells, the majority of cells biopsied from embryos produced by IVF are in interphase and thus unsuitable for analysis by chromosome banding or FISH-painting. We therefore set out to analyze single interphase cells for presence or absence of specific translocations. Our assay, based on fluorescence in situ hybridization (FISH) of breakpoint-spanning DNA probes, detects translocations in interphase by visual microscopic inspection of hybridization domains. Probes are prepared so that they span a breakpoint and cover several hundred kb of DNA adjacent to the breakpoint. On normal chromosomes, such probes label a contiguous stretch of DNA and produce a single hybridization domain per chromosome in interphase cells. The translocation disrupts the hybridization domain and the resulting two fragments appear as physically separated hybridization domains in the nucleus. To facilitate the detection, DNA probes for breakpoints on different chromosomes are labeled in different colors, so the translocation event can be detected as a fusion of red and green hybridization domains. We applied this scheme successfully for the analysis of somatic and germ cells from more than 20 translocation patients, each with individual breakpoints, and provide summaries of our experience as well as strategies, cost and time frames to prepare case-specific translocation probes.

Weier, Heinz-Ulli G.; Munne, S.; Lersch, Robert A.; Marquez, C.; Wu, J.; Pedersen, Roger A.; Fung, Jingly

1999-06-01

406

Familial Robertsonian Translocation 13;21 in a Down Syndrome Patient with XYY\\/XY Mosaicism  

Microsoft Academic Search

KEYWORDS Down syndrome; mosaicism; Robertsonian translocation; XYY males ABSTRACT Double aneuploidy involving XYY and trisomy 21 is rare. XYY\\/XY mosaicism has been described in only a single Down syndrome patient. The Robertsonian translocation t(13;21) is also rare among these individuals. We report for the first time the occurrence of t(13;21) in a mosaic XYY Down male. Analysis of GTG-banded metaphases

Cyril Cyrus; Solomon F. D. Paul

407

Absence probable de la translocation robertsonienne 1/29 en race bovine  

E-print Network

Note Absence probable de la translocation robertsonienne 1/29 en race bovine Blanc Bleu Belge N voulu connaître sa fréquence en race bovine Blanc Bleu Belge, jusqu'alors non étudiée pour ce facteur. Au sein d'un échantillon de 138 taureaux de race Blanc Bleu Belge, la translocation 1/29 n'a pas pu

Paris-Sud XI, Université de

408

A Y\\/5 translocation in a 45,X male with cri du chat syndrome  

Microsoft Academic Search

In a patient described as a 45,X male with cri du chat syndrome, combined cytogenetic and molecular methods revealed Y euchromatic material to be translocated onto the short arm of one chromosome 5, resulting in a chromosome der(5)(5qter?5p14::Yp11.31?Ypter). The translocated Y euchromatin comprised only the distal short arm including the pseudoautosomal region and the so-called deletion intervals 1 and 2.

Bernhard Weber; Werner Schempp; Ulrike Orth; Heide Seidel; Andreas Gal

1987-01-01

409

Genetic Analysis of Pathway Specificity during Posttranslational Protein Translocation across the Escherichia coli Plasma Membrane  

Microsoft Academic Search

In Escherichia coli, the SecB\\/SecA branch of the Sec pathway and the twin-arginine translocation (Tat) pathway represent two alternative possibilities for posttranslational translocation of proteins across the cytoplasmic membrane. Maintenance of pathway specificity was analyzed using a model precursor consisting of the mature part of the SecB-dependent maltose-binding protein (MalE) fused to the signal peptide of the Tat-dependent TorA protein.

Natascha Blaudeck; Peter Kreutzenbeck; Roland Freudl; Georg A. Sprenger

2003-01-01

410

Genetic segregation and the detection of spontaneous wheat-alien translocations  

Microsoft Academic Search

Robertsonian translocation between homoeologous chromosomes is one means for introducing alien genes from related species\\u000a into common wheat. This study was undertaken to determine if selection for normal segregation of an alien trait could be used\\u000a to identify favourable translocations. Agrotana (an octoploid agrotriticum, probably derived from Thinopyrum ponticum) carries\\u000a resistance to the wheat curl mite (Eriophyes tulipae Keifer) which

J. Thomas; Q. Chen; L. Talbert

1998-01-01

411

A cellular oncogene is translocated to the Philadelphia chromosome in chronic myelocytic leukaemia  

Microsoft Academic Search

The transforming genes of oncogenic retroviruses are homologous to a group of evolutionary conserved cellular onc genes1. The human cellular homologue (c-abl) of the transforming sequence of Abelson murine leukaemia virus (A-MuLV) was recently shown2 to be located on chromosome 9. The long arm of this chromosome is involved in a specific translocation with chromosome 22, the Philadelphia translocation (Ph1),

Annelies De Klein; Ad Geurts Van Kessel; Gerard Grosveld; Claus R. Bartram; Anne Hagemeijer; Dirk Bootsma; Nigel K. Spurr; Nora Heisterkamp; John Groffen; John R. Stephenson

1982-01-01

412

Cytological Study of an X-Autosome Translocation in Mus musculus  

Microsoft Academic Search

Earlier genetic studies on this stock of mice with an X-autosome translocation revealed that wild-type alleles of pink-eye and chinchilla of linkage group I have been translocated to the X. When the Xt was accompanied by an Xn, animals heterozygous for pp and cchcch showed variegated coat colors but the Xt alone led only to the wild-type coat color. The

S. Ohno; B. M. Cattanach

1962-01-01

413

Determinants of the rate of mRNA translocation in bacterial protein synthesis.  

PubMed

To study the rate of translocation of mRNA and tRNAs on the translating ribosome is technically difficult, since the rate limiting steps involve large conformational changes without covalent bond formation or disruption. Here, we have developed a unique assay system for precise estimation of the full translocation cycle time at any position in any type of open reading frame (ORF). Using a buffer system optimized for high accuracy of transfer RNA selection together with high concentration of elongation factor G we obtained in vivo compatible translocation rates. We found that translocation was comparatively slow early in the ORF and faster further downstream of the initiation codon. The maximal translocation rate decreased from the in vivo compatible value of 30s(-1) at 1mM free Mg(2+) concentration to the detrimentally low value of 1s(-1) at 6mM free Mg(2+) concentration. Thus, high and in vivo compatible accuracy of codon translation as well as high and in vivo compatible translocation rate required a remarkably low Mg(2+) concentration. Finally, we found that the rate of translocation deep inside an ORF was not significantly affected upon variation of the standard free energy of interaction between a 6-nt upstream SD-like sequence and the anti-SD sequence of 16S rRNA in the zero to 6kcal/mole range. Based on these experiments we discuss the optimal choice of Mg(2+) concentration for maximal fitness of the living cell by taking its effects on the accuracy of translation, the peptide bond formation rate and the translocation rate into account. PMID:25451025

Borg, Anneli; Ehrenberg, Måns

2014-11-14

414

Evaluating the Applicability of the Fokker-Planck Equation in Polymer Translocation: A Brownian Dynamics Study  

E-print Network

Brownian dynamics (BD) simulations are used to study the translocation dynamics of a coarse-grained polymer through a cylindrical nanopore. We consider the case of short polymers, with a polymer length, N, in the range N=21-61. The rate of translocation is controlled by a tunable friction coefficient, gamma_{0p}, for monomers inside the nanopore. In the case of unforced translocation, the mean translocation time scales with polymer length N as ~ (N-N_p)^alpha, where N_p is the average number of monomers in the nanopore. The exponent approaches the value alpha=2 when the pore friction is sufficiently high, in accord with the prediction for the case of the quasi-static regime where pore friction dominates. In the case of forced translocation, the polymer chain is stretched and compressed on the cis and trans sides, respectively, for low gamma_{0p}. However, the chain approaches conformational quasi-equilibrium for sufficiently large gamma_{0p}. In this limit the observed scaling of with driving force and chain length supports the FP prediction that is proportional to N/f_d for sufficiently strong driving force. Monte Carlo simulations are used to calculate translocation free energy functions for the system. The free energies are used with the Fokker-Planck equation to calculate translocation time distributions. At sufficiently high gamma_{0p}, the predicted distributions are in excellent agreement with those calculated from the BD simulations. Thus, the FP equation provides a valid description of translocation dynamics for sufficiently high pore friction for the range of polymer lengths considered here. Increasing N will require a corresponding increase in pore friction to maintain the validity of the FP approach. Outside the regime of low N and high pore friction, the polymer is out of equilibrium, and the FP approach is not valid.

James M. Polson; Taylor Dunn

2014-03-28

415

A rare cause of childhood renal cysts: Xp11.2 translocation renal cell carcinoma  

PubMed Central

Pediatric renal cysts are rare, usually asymptomatic and incidentally detected in children. Cyst associated renal cell carcinoma (RCC) or cystic RCC is extremely rare in children. Bosniak classification system has been accepted for the management of cystic renal masses. Xp11.2 translocation RCC is a recently classified distinct subtype and usually affects children and adolescents. We report the case of a 10-year-old girl with Xp11.2 translocation RCC from a cyst of the right kidney.

Ta?k?nlar, Hakan; Avlan, Dinçer; Ç?tak, Ça?lar; Polat, Ay?e; Nayc?, Ali

2015-01-01

416

Salt Dependence of Ion Transport and DNA Translocation through Solid-State Nanopores  

Microsoft Academic Search

We report experimental measurements of the salt dependence of ion transport and DNA translocation through solid-state nanopores. The ionic conductance shows a three-order-of-magnitude decrease with decreasing salt concentrations fro m1Mt o 1ÌM, strongly deviating from bulk linear behavior. The data are described by a model that accounts for a salt-dependent surface charge of the pore. Subsequently, we measure translocation of

Ralph M. M. Smeets; Ulrich F. Keyser; Diego Krapf; Meng-Yue Wu; Nynke H. Dekker; Cees Dekker

2006-01-01

417

Evaluating the applicability of the Fokker-Planck equation in polymer translocation: A Brownian dynamics study  

NASA Astrophysics Data System (ADS)

Brownian dynamics (BD) simulations are used to study the translocation dynamics of a coarse-grained polymer through a cylindrical nanopore. We consider the case of short polymers, with a polymer length, N, in the range N = 21-61. The rate of translocation is controlled by a tunable friction coefficient, ?0p, for monomers inside the nanopore. In the case of unforced translocation, the mean translocation time scales with polymer length as ??1? ˜ (N - Np)?, where Np is the average number of monomers in the nanopore. The exponent approaches the value ? = 2 when the pore friction is sufficiently high, in accord with the prediction for the case of the quasi-static regime where pore friction dominates. In the case of forced translocation, the polymer chain is stretched and compressed on the cis and trans sides, respectively, for low ?0p. However, the chain approaches conformational quasi-equilibrium for sufficiently large ?0p. In this limit the observed scaling of ??1? with driving force and chain length supports the Fokker-Planck (FP) prediction that ??? ? N/fd for sufficiently strong driving force. Monte Carlo simulations are used to calculate translocation free energy functions for the system. The free energies are used with the FP equation to calculate translocation time distributions. At sufficiently high ?0p, the predicted distributions are in excellent agreement with those calculated from the BD simulations. Thus, the FP equation provides a valid description of translocation dynamics for sufficiently high pore friction for the range of polymer lengths considered here. Increasing N will require a corresponding increase in pore friction to maintain the validity of the FP approach. Outside the regime of low N and high pore friction, the polymer is out of equilibrium, and the FP approach is not valid.

Polson, James M.; Dunn, Taylor R.

2014-05-01

418

fd Virus as a Model Stiff Polymer for Translocation Experiments with Solid-State Nanopores  

NASA Astrophysics Data System (ADS)

We report preliminary experimental results of the translocation of the filamentous virus fd through a solid-state nanopore. fd virus is suitable for translocation and detection in a voltage-biased nanopore because it is highly charged, 880 nm long, and 6.6 nm in diameter. Importantly, fd has a persistence length of ˜2 ?m, a forty-fold increase over dsDNA, making fd a model stiff polymer for testing theories of polymer translocation dynamics. fd cannot coil in solution, therefore the dispersion of fd translocation times can test a model by Lu et al. that ascribes DNA translocation velocity fluctuations to the distribution of initial conformations of the DNA coil. That picture is in contrast with an alternative model by Li et al., which attributes the spread of DNA translocation times to thermal velocity fluctuations. The physics of fd capture by a nanopore also differs significantly from DNA since the ends of the virus cannot diffusively search for the pore independently of the middle. As a result, the rate of fd capture from solution may not increase monotonically with the applied voltage across the pore; it is possible for fd to become kinetically trapped against the nanopore membrane by the electric field. We will compare the distribution of translocation times of fd virus to distributions for DNA and discuss the influence of the virus's orientation and interactions with the nanopore on the translocation speed and the measured current blockage. We will also examine the dependence of capture rate on the applied voltage.

McMullen, Angus; Liu, Xu; Mihovilovic, Mirna; Stein, Derek; Tang, Jay

2012-02-01

419

Translocation of carnivores as a method for managing problem animals: a review  

Microsoft Academic Search

Translocation of individual carnivores has been a standard management tool for decades in North America and southern Africa\\u000a in response to livestock depredation and other conflict behaviours. As carnivore populations across Europe begin to increase\\u000a it is expected that management problems will also increase. Before translocation becomes established as a management tool\\u000a in Europe its success needs to be reviewed.

JOHN D. C. LINNELL; RONNY AANES; JON E. SWENSON; JOHN ODDEN; MARTIN E. SMITH

1997-01-01

420

Y autosome translocation and complex chromosome rearrangement in cri du chat syndrome.  

PubMed Central

An unbalanced Y autosome translocation t(5;Y) and an apparently balanced translocation t(2;13) are identified with the Q and R banding in a 7-year-old boy with severe encephalopathy and a multiple malformation syndrome. At birth, the clinical diagnosis of 'cri du chat' syndrome based on the characteristic crying was not confirmed after karyotyping, using conventional staining techniques. Images PMID:641952

Mattei, J F; Mattei, M G; Coignet, J; Giraud, F

1978-01-01

421

Protein Translocation in Photoreceptor Light Adaptation: A Common Theme in Vertebrate and Invertebrate Vision  

NSDL National Science Digital Library

How do our eyes adjust to daily light levels that vary by almost 11 orders of magnitude? Research shows that, in both vertebrates and invertebrates, signaling proteins are translocated in a light-dependent manner between the photoreceptor cellular compartments where visual transduction takes place, and the rest of the photoreceptor cell. Protein translocation is likely to contribute to photoreceptor light adaptation by adjusting the sensitivity and speed of photoresponse to ever-changing conditions of ambient illumination.

Vadim Y. Arshavsky (Harvard Medical School and the Massachusetts Eye and Ear Infirmary; REV)

2003-10-14

422

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

Microsoft Academic Search

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\\u000a size and range, translocation sites were established beginning in the 1960's by moving squirrels from the natural range to\\u000a sites outside the current range. Although translocations have served as the primary component of

Stacey L. Lance; Jesús E. Maldonado; Carol I. Bocetti; O. H. Pattee; Jonathan D. Ballou; Robert C. Fleischer

2003-01-01

423

Phylogeography of the New Zealand blue duck ( Hymenolaimus malacorhynchos ): implications for translocation and species recovery  

Microsoft Academic Search

Translocation of individuals among extant populations is an important tool in species conservation that allows managers to\\u000a supplement dwindling populations and potentially alleviate the deleterious effects of inbreeding. Ideal translocation strategy\\u000a should consider historical relationships among existing populations to avoid potential disruption of population subdivision\\u000a and local adaptation. Here, we examine mitochondrial sequence variation in the endangered blue duck Hymenolaimus

Bruce C. Robertson; Tammy E. Steeves; Katherine P. McBride; Sharyn J. Goldstien; Murray Williams; Neil J. Gemmell

2007-01-01

424

The cytosolic entry of diphtheria toxin catalytic domain requires a host cell cytosolic translocation factor complex  

Microsoft Academic Search

n vitro delivery of the diphtheria toxin catalytic (C) domain from the lumen of purified early endosomes to the external milieu requires the addition of both ATP and a cytosolic translocation factor (CTF) complex. Using the translocation of C-domain ADP-ribosyltransferase activity across the endo- somal membrane as an assay, the CTF complex activity was 650-800-fold purified from human T cell

Ryan Ratts; Huiyan Zeng; Eric A. Berg; Clare Blue; Mark E. McComb; Cathy E. Costello; Johanna C. vanderSpek; John R. Murphy

2003-01-01

425

Evaluating the applicability of the Fokker-Planck equation in polymer translocation: a Brownian dynamics study.  

PubMed

Brownian dynamics (BD) simulations are used to study the translocation dynamics of a coarse-grained polymer through a cylindrical nanopore. We consider the case of short polymers, with a polymer length, N, in the range N = 21-61. The rate of translocation is controlled by a tunable friction coefficient, ?0p, for monomers inside the nanopore. In the case of unforced translocation, the mean translocation time scales with polymer length as ? (N - Np)(?), where Np is the average number of monomers in the nanopore. The exponent approaches the value ? = 2 when the pore friction is sufficiently high, in accord with the prediction for the case of the quasi-static regime where pore friction dominates. In the case of forced translocation, the polymer chain is stretched and compressed on the cis and trans sides, respectively, for low ?0p. However, the chain approaches conformational quasi-equilibrium for sufficiently large ?0p. In this limit the observed scaling of with driving force and chain length supports the Fokker-Planck (FP) prediction that ? N/fd for sufficiently strong driving force. Monte Carlo simulations are used to calculate translocation free energy functions for the system. The free energies are used with the FP equation to calculate translocation time distributions. At sufficiently high ?0p, the predicted distributions are in excellent agreement with those calculated from the BD simulations. Thus, the FP equation provides a valid description of translocation dynamics for sufficiently high pore friction for the range of polymer lengths considered here. Increasing N will require a corresponding increase in pore friction to maintain the validity of the FP approach. Outside the regime of low N and high pore friction, the polymer is out of equilibrium, and the FP approach is not valid. PMID:24832303

Polson, James M; Dunn, Taylor R

2014-05-14

426

Disruption of two novel genes by a translocation co-segregating with schizophrenia  

Microsoft Academic Search

A balanced (1;11)(q42.1;q14.3) translocation segregates with schizophrenia and related psychiatric disorders in a large Scottish family (maximum LOD = 6.0). We hypoth- esize that the translocation is the causative event and that it directly disrupts gene function. We previously reported a dearth of genes in the breakpoint region of chromosome 11 and it is therefore unlikely that the expression of

J. Kirsty Millar; Julie C. Wilson-Annan; Susan Anderson; Sheila Christie; M artin S. Taylor; Colin A. M. Semple; Rebecca S. Devon; D avid M. St Clair; W alter J. Muir; Douglas H. R. Blackwood; David J. Porteous

2000-01-01

427

Partial 18 trisomy (with 47 chromosomes) resulting from a familial maternal translocation  

Microsoft Academic Search

A newborn female infant presented with the classical picture of 18 trisomy syndrome. Her karyotyping was 47,XX,+der(18)t(12;18)(q24;q21)mat. The mother was a balanced reciprocal translocation carrier and so too was one of the two maternal uncles of the proposita, indicating that the translocation was already present in one of the grandparents who were not available for examination. This family suggests that

K Fried; A Bar-Yochai; M Rosenblatt; G Mundel

1978-01-01

428

Follow-up of a familial translocation t(10;16) with an unusual segregation pattern  

SciTech Connect

Bofinger et al. reported on a four-generation family with an unusual segregation pattern involving a translocation t(10;16)(q26.3;p13.1). All relatives either had a balanced or unbalanced translocation. We report on five additional relatives, none of whom have a normal karyotype. This unusual segregation pattern may be due to chance or be the result of meiotic drive. 17 refs., 1 fig., 1 tab.

Resta, R.G.; Luthardt, F. [Swedish Medical Center, Seattle, WA (United States)] [Swedish Medical Center, Seattle, WA (United States); Kapur, R. [Univ. of Washington, Seattle, WA (United States)] [Univ. of Washington, Seattle, WA (United States)

1996-05-17

429

Aluminum as a source of background in low background experiments  

E-print Network

Neutrinoless double beta decay would be a key to understanding the nature of neutrino masses. The next generation of High Purity Germanium experiments will have to be operated with a background rate of better than 10^-5 counts/(kg y keV) in the region of interest around the Q value of the decay. Therefore, so far irrelevant sources of background have to be considered. The metalization of the surface of germanium detectors is in general done with aluminum. The background from the decays of 22Na, 26Al, 226Ra and 228Th introduced by this metalization is discussed. It is shown that only a special selection of aluminum can keep these background contributions acceptable.

B. Majorovits; I. Abt; M. Laubenstein; O. Volynets

2011-05-18

430

Low background counting at the LBNL low background facility  

SciTech Connect

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 TeO{sub 2} for CUORE, and environmental monitoring of Fukushima fallout.

Thomas, K. J.; Norman, E. B. [Department of Nuclear Engineering, University of California, Berkeley, CA 94720, United States and Nuclear Science Division, Lawrence Berkeley Laboratory, CA 94720 (United States)] [Department of Nuclear Engineering, University of California, Berkeley, CA 94720, United States and Nuclear Science Division, Lawrence Berkeley Laboratory, CA 94720 (United States); Smith, A. R.; Chan, Y. D.; Hurley, D. L. [Nuclear Science Division, Lawrence Berkeley Laborato