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Sample records for background translocation frequencies

  1. Measurement of background translocation frequencies in individuals with clones

    SciTech Connect

    Wade, M.J.

    1996-08-01

    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.

  2. Elevated chromosome translocation frequencies in New Zealand nuclear test veterans.

    PubMed

    Wahab, M A; Nickless, E M; Najar-M'kacher, R; Parmentier, C; Podd, J V; Rowland, R E

    2008-01-01

    In 1957/58 the British Government conducted a series of nuclear tests in the mid-Pacific codenamed Operation Grapple, which involved several naval vessels from Britain and New Zealand. Two New Zealand frigates with 551 personnel onboard were stationed at various distances between 20 and 150 nautical miles from ground zero. In the present study we applied the cytomolecular technique mFISH (multicolour fluorescent in situ hybridisation) to investigate a potential link between chromosome abnormalities and possible past radiation exposure in New Zealand nuclear test veterans who participated in Operation Grapple. Compared to age matched controls, the veterans showed significantly higher (P < 0.0001) frequencies of chromosomal abnormalities (275 translocations and 12 dicentrics in 9,360 cells vs. 96 translocations and 1 dicentric in 9,548 cells in the controls), in addition to a significant excess of CCRs (complex chromosomal rearrangements) in the veterans. A Kolmogorov-Smirnoff test showed that the distributions of translocations for the two groups were significantly different. PMID:18544930

  3. Translocation frequency of double-stranded DNA through a solid-state nanopore

    NASA Astrophysics Data System (ADS)

    Bell, Nicholas A. W.; Muthukumar, Murugappan; Keyser, Ulrich F.

    2016-02-01

    Solid-state nanopores are single-molecule sensors that measure changes in ionic current as charged polymers such as DNA pass through. Here, we present comprehensive experiments on the length, voltage, and salt dependence of the frequency of double-stranded DNA translocations through conical quartz nanopores with mean opening diameter 15 nm. We observe an entropic barrier-limited, length-dependent translocation frequency at 4M LiCl salt concentration and a drift-dominated, length-independent translocation frequency at 1M KCl salt concentration. These observations are described by a unifying convection-diffusion equation, which includes the contribution of an entropic barrier for polymer entry.

  4. Novel effects of chain flexibility, external force, and background stochasticity on polymer translocation

    NASA Astrophysics Data System (ADS)

    Sung, Wokyung

    2011-03-01

    The polymer translocation through membranes and the polymer crossing over activation barriers in general, are ubiquitous in cell biology and biotechnological applications. Because they are interconnected flexible systems, polymers in translocation incur entropic barriers but can thermally surmount them with unusual sensitivity to background biases. In the presence of non-equilibrium noises characteristic of living environments, the translocation can speed up much when resonant activation occurs. As a related issue, I will also discuss the problem of polymer surmounting a potential barrier, where the chain flexibility enhances the crossing. Furthermore, when the chain flexibility leads to conformational changes, the crossing rate can be even more dramatically increased. This conformational flexibility and variability enhance the stochastic resonance, where the chain crossing dynamics at an optimal temperature and chain length is maximally coherent and resonant to a minute periodic force. Utilizing the self-organizing behaviors mentioned above, we may learn about bio-molecular machinery of living as well as clever means of manipulating it. Korea Research Foundation.

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

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

    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.

  6. Analysis of chromosome translocation frequency after a single CT scan in adults.

    PubMed

    Abe, Yu; Miura, Tomisato; Yoshida, Mitsuaki A; Ujiie, Risa; Kurosu, Yumiko; Kato, Nagisa; Katafuchi, Atsushi; Tsuyama, Naohiro; Kawamura, Fumihiko; Ohba, Takashi; Inamasu, Tomoko; Shishido, Fumio; Noji, Hideyoshi; Ogawa, Kazuei; Yokouchi, Hiroshi; Kanazawa, Kenya; Ishida, Takashi; Muto, Satoshi; Ohsugi, Jun; Suzuki, Hiroyuki; Ishikawa, Tetsuo; Kamiya, Kenji; Sakai, Akira

    2016-06-01

    We recently reported an increase in dicentric chromosome (DIC) formation after a single computed tomography (CT) scan (5.78-60.27 mSv: mean 24.24 mSv) and we recommended analysis of 2000 metaphase cells stained with Giemsa and centromere-FISH for dicentric chromosome assay (DCA) in cases of low-dose radiation exposure. In the present study, we analyzed the frequency of chromosome translocations using stored Carnoy's-fixed lymphocyte specimens from the previous study; these specimens were from 12 patients who were subject to chromosome painting of Chromosomes 1, 2 and 4. Chromosomes 1, 2 and 4 were analyzed in ∼5000 cells, which is equivalent to the whole-genome analysis of almost 2000 cells. The frequency of chromosome translocation was higher than the number of DICs formed, both before and after CT scanning. The frequency of chromosome translocations tended to be higher, but not significantly higher, in patients with a treatment history compared with patients without such a history. However, in contrast to the results for DIC formation, the frequency of translocations detected before and after the CT scan did not differ significantly. Therefore, analysis of chromosome translocation may not be a suitable assay for detecting chromosome aberrations in cases of low-dose radiation exposure from a CT scan. A significant increase in the frequency of chromosome translocations was not likely to be detected due to the high baseline before the CT scan; the high and variable frequency of translocations was probably due to multiple confounding factors in adults. PMID:26874116

  7. Analysis of chromosome translocation frequency after a single CT scan in adults

    PubMed Central

    Abe, Yu; Miura, Tomisato; Yoshida, Mitsuaki A.; Ujiie, Risa; Kurosu, Yumiko; Kato, Nagisa; Katafuchi, Atsushi; Tsuyama, Naohiro; Kawamura, Fumihiko; Ohba, Takashi; Inamasu, Tomoko; Shishido, Fumio; Noji, Hideyoshi; Ogawa, Kazuei; Yokouchi, Hiroshi; Kanazawa, Kenya; Ishida, Takashi; Muto, Satoshi; Ohsugi, Jun; Suzuki, Hiroyuki; Ishikawa, Tetsuo; Kamiya, Kenji; Sakai, Akira

    2016-01-01

    We recently reported an increase in dicentric chromosome (DIC) formation after a single computed tomography (CT) scan (5.78–60.27 mSv: mean 24.24 mSv) and we recommended analysis of 2000 metaphase cells stained with Giemsa and centromere-FISH for dicentric chromosome assay (DCA) in cases of low-dose radiation exposure. In the present study, we analyzed the frequency of chromosome translocations using stored Carnoy's-fixed lymphocyte specimens from the previous study; these specimens were from 12 patients who were subject to chromosome painting of Chromosomes 1, 2 and 4. Chromosomes 1, 2 and 4 were analyzed in ∼5000 cells, which is equivalent to the whole-genome analysis of almost 2000 cells. The frequency of chromosome translocation was higher than the number of DICs formed, both before and after CT scanning. The frequency of chromosome translocations tended to be higher, but not significantly higher, in patients with a treatment history compared with patients without such a history. However, in contrast to the results for DIC formation, the frequency of translocations detected before and after the CT scan did not differ significantly. Therefore, analysis of chromosome translocation may not be a suitable assay for detecting chromosome aberrations in cases of low-dose radiation exposure from a CT scan. A significant increase in the frequency of chromosome translocations was not likely to be detected due to the high baseline before the CT scan; the high and variable frequency of translocations was probably due to multiple confounding factors in adults. PMID:26874116

  8. Translocation frequency of double-stranded DNA through a solid-state nanopore

    PubMed Central

    Bell, Nicholas A. W.; Muthukumar, Murugappan; Keyser, Ulrich F.

    2016-01-01

    Solid-state nanopores are single-molecule sensors that measure changes in ionic current as charged polymers such as DNA pass through. Here, we present comprehensive experiments on the length, voltage, and salt dependence of the frequency of double-stranded DNA translocations through conical quartz nanopores with mean opening diameter 15 nm. We observe an entropic barrier-limited, length-dependent translocation frequency at 4M LiCl salt concentration and a drift-dominated, length-independent translocation frequency at 1M KCl salt concentration. These observations are described by a unifying convection-diffusion equation, which includes the contribution of an entropic barrier for polymer entry. PMID:26986356

  9. Retrospective biodosimetry using translocation frequency in a stable cell of occupationally exposed to ionizing radiation.

    PubMed

    Cho, Min Su; Lee, Jin Kyung; Bae, Keum Seok; Han, Eun-Ae; Jang, Seong Jae; Ha, Wi-Ho; Lee, Seung-Sook; Barquinero, Joan Francesc; Kim, Wan Tae

    2015-07-01

    Two cases of hematological malignancies were reported in an industrial radiography company over a year, which were reasonably suspected of being consequences of prolonged exposure to ionizing radiation because of the higher incidence than expected in the general population. We analyzed chromosomal aberrations in the peripheral blood lymphocytes from the other workers who had been working under similar circumstances as the patients in the company. Among the subjects tested, 10 workers who belonged to the highest band were followed up periodically for 1.5 years since the first analysis. The aim of this study was to clarify pertinence of translocation analysis to an industrial set-up where chronic exposure was commonly expected. To be a useful tool for a retrospective biodosimetry, the aberrations need to be persistent for a decade or longer. Therefore we calculated the decline rates and half-lives of frequency for both a reciprocal translocation and a dicentric chromosome and compared them. In this study, while the frequency of reciprocal translocations was maintained at the initial level, dicentric chromosomes were decreased to 46.9% (31.0-76.5) of the initial frequency over the follow-up period. Our results support the long-term stability of reciprocal translocation through the cell cycle and validate the usefulness of translocation analysis as a retrospective biodosimetry for cases of occupational exposure. PMID:25922373

  10. Retrospective biodosimetry using translocation frequency in a stable cell of occupationally exposed to ionizing radiation

    PubMed Central

    Cho, Min Su; Lee, Jin Kyung; Bae, Keum Seok; Han, Eun-Ae; Jang, Seong Jae; Ha, Wi-Ho; Lee, Seung-Sook; Barquinero, Joan Francesc; Kim, Wan Tae

    2015-01-01

    Two cases of hematological malignancies were reported in an industrial radiography company over a year, which were reasonably suspected of being consequences of prolonged exposure to ionizing radiation because of the higher incidence than expected in the general population. We analyzed chromosomal aberrations in the peripheral blood lymphocytes from the other workers who had been working under similar circumstances as the patients in the company. Among the subjects tested, 10 workers who belonged to the highest band were followed up periodically for 1.5 years since the first analysis. The aim of this study was to clarify pertinence of translocation analysis to an industrial set-up where chronic exposure was commonly expected. To be a useful tool for a retrospective biodosimetry, the aberrations need to be persistent for a decade or longer. Therefore we calculated the decline rates and half-lives of frequency for both a reciprocal translocation and a dicentric chromosome and compared them. In this study, while the frequency of reciprocal translocations was maintained at the initial level, dicentric chromosomes were decreased to 46.9% (31.0–76.5) of the initial frequency over the follow-up period. Our results support the long-term stability of reciprocal translocation through the cell cycle and validate the usefulness of translocation analysis as a retrospective biodosimetry for cases of occupational exposure. PMID:25922373

  11. A biophysical model for estimating the frequency of radiation-induced mutations resulting from chromosomal translocations

    NASA Astrophysics Data System (ADS)

    Wu, Honglu; Durante, Marco

    Gene mutations can be induced by radiation as a result of chromosomal translocations. A biophysical model is developed to estimate the frequency of this type of mutation induced by low-LET radiation. Mutations resulting from translocations are assumed to be formed by misrejoining of two DNA double strand breaks (DSB), one within the gene and one on a different chromosome. The chromosome containing the gene is assumed to occupy a spherical territory and does not overlap spatially with other chromosomes. Misrejoining between two DSB can occur only if the two DSB are closer than an interaction distance at the time of their induction. Applying the model to mutations of the hprt gene induced in G0 human lymphocyte cells by low-LET radiation, it is calculated that mutations resulting from translocations account for about 14% of the total mutations. The value of the interaction distance is determined to be 0.6 μm by comparing with the observed frequency of translocations in the X-chromosome.

  12. Characterization of Common Chromosomal Translocations and Their Frequencies in Acute Myeloid Leukemia Patients of Northwest Iran

    PubMed Central

    Amanollahi Kamaneh, Elnaz; Shams Asenjan, Karim; Movassaghpour Akbari, Aliakbar; Akbarzadeh Laleh, Parvin; Chavoshi, Hadi; Eivazi Ziaei, Jamal; Nikanfar, Alireza; Asvadi Kermani, Iraj; Esfahani, Ali

    2016-01-01

    Objective Detection of chromosomal translocations has an important role in diagnosis and treatment of hematological disorders. We aimed to evaluate the 46 new cases of de novo acute myeloid leukemia (AML) patients for common translocations and to assess the effect of geographic and ethnic differences on their frequencies. Materials and Methods In this descriptive study, reverse transcriptase-polymerase chain reaction (RT-PCR) was used on 46 fresh bone marrow or peripheral blood samples to detect translocations t (8; 21), t (15; 17), t (9; 11) and inv (16). Patients were classified using the French-American-British (FAB) criteria in to eight sub-groups (M0-M7). Immunophenotyping and biochemical test results of patients were compared with RT-PCR results. Results Our patients were relatively young with a mean age of 44 years. AML was relatively predominant in female patients (54.3%) and most of patients belonged to AML-M2. Translocation t (8; 21) had the highest frequency (13%) and t (15; 17) with 2.7% incidence was the second most frequent. CD19 as an immunophenotypic marker was at a relatively high frequency (50%) in cases with t (8; 21), and patients with this translocation had a specific immunophenotypic pattern of complete expression of CD45, CD38, CD34, CD33 and HLA-DR. Conclusion Similarities and differences of results in Iran with different parts of the world can be explained with ethnic and geographic factors in characterizations of AML. Recognition of these factors especially in other comprehensive studies may aid better diagnosis and management of this disease. PMID:27054117

  13. Frequency Modulated Translocational Oscillations of Nrf2 Mediate the Antioxidant Response Element Cytoprotective Transcriptional Response

    PubMed Central

    Xue, Mingzhan; Momiji, Hiroshi; Rabbani, Naila; Barker, Guy; Bretschneider, Till; Shmygol, Anatoly; Rand, David A.

    2015-01-01

    Abstract Aims: Stress responsive signaling coordinated by nuclear factor erythroid 2-related factor 2 (Nrf2) provides an adaptive response for protection of cells against toxic insults, oxidative stress and metabolic dysfunction. Nrf2 regulates a battery of protective genes by binding to regulatory antioxidant response elements (AREs). The aim of this study was to examine how Nrf2 signals cell stress status and regulates transcription to maintain homeostasis. Results: In live cell microscopy we observed that Nrf2 undergoes autonomous translocational frequency-modulated oscillations between cytoplasm and nucleus. Oscillations occurred in quiescence and when cells were stimulated at physiological levels of activators, they decrease in period and amplitude and then evoke a cytoprotective transcriptional response. We propose a mechanism whereby oscillations are produced by negative feedback involving successive de-phosphorylation and phosphorylation steps. Nrf2 was inactivated in the nucleus and reactivated on return to the cytoplasm. Increased frequency of Nrf2 on return to the cytoplasm with increased reactivation or refresh-rate under stress conditions activated the transcriptional response mediating cytoprotective effects. The serine/threonine-protein phosphatase PGAM5, member of the Nrf2 interactome, was a key regulatory component. Innovation: We found that Nrf2 is activated in cells without change in total cellular Nrf2 protein concentration. Regulation of ARE-linked protective gene transcription occurs rather through translocational oscillations of Nrf2. We discovered cytoplasmic refresh rate of Nrf2 is important in maintaining and regulating the transcriptional response and links stress challenge to increased cytoplasmic surveillance. We found silencing and inhibition of PGAM5 provides potent activation of Nrf2. Conclusion: Frequency modulated translocational oscillations of Nrf2 mediate the ARE-linked cytoprotective transcriptional response. Antioxid. Redox

  14. Search for a high frequency stochastic background of gravitational waves

    NASA Astrophysics Data System (ADS)

    Giampanis, Stefanos

    Over the past decades significant efforts have been made worldwide in the search for gravitational waves. Ground-based interferometry, primarily with the LIGO detectors, has reached a crucial point and it is believed that over the next few years a detection will take place. LIGO interferometers have recently completed collecting data from the longest science run that has been attempted so far. This thesis describes the search for a stochastic gravitational wave background radiation at high frequencies using data from the LIGO detectors located in Hanford, Washington USA. This is the first ever search for a stochastic signal at high frequencies by using data from two co-located interferometers. Chapter 1 provides a brief introduction to gravitational radiation as predicted by the general theory of relativity and the expected sources of gravitational waves with an emphasis on the stochastic background. Chapter 2 discusses the basic principles of laser interferometry and the experimental techniques used in modern ground-based interferometers such as the LIGO interferometers. Chapter 3 discusses in more detail the configuration, validation and characterization of the set of channels, "Fast Channels", that are used in the search for a high frequency stochastic background radiation. Chapter 4 is an introduction to the LIGO calibration and a more formal discussion on the calibration of the "Fast Channels". Chapter 5 introduces the cross-correlation analysis technique used in the search for a stochastic background and gives a thorough description of the data selection and analysis in searching for a high frequency stochastic signal with data from LIGO's fifth science run (S5). Chapter 6 concludes with the results obtained from the stochastic high frequency S5 analysis, discusses upper limits set at low and high frequencies from other searches and makes connection with Chapter 1 and the theoretical predictions and experimental bounds set within LIGO's frequency band of

  15. Real-time background suppression during frequency domain lifetime measurements.

    PubMed

    Herman, Petr; Maliwal, Badri P; Lakowicz, Joseph R; Maliwal, Baldri P

    2002-10-01

    We describe real time background suppression of autofluorescence from biological samples during frequency domain or phase modulation measurements of intensity decays. For these measurements the samples were excited with a train of light pulses with widths below 1 ps. The detector was gated off for a short time period of 10 to 40 ns during and shortly after the excitation pulse. The reference signal needed for the frequency domain measurement was provided by a long-lifetime reference fluorophore which continues to emit following the off-gating pulse. Both the sample and the reference were measured under identical optical and electronic conditions avoiding the need for correction of the photomultiplier tube signal for the gating sequence. We demonstrate frequency domain background suppression using a mixture of short- and long-lifetime probes and for a long-lifetime probe in human plasma with significant autofluorescence. PMID:12381357

  16. Frequency modulated translocational oscillations of Nrf2, a transcription factor functioning like a wireless sensor.

    PubMed

    Xue, Mingzhan; Momiji, Hiroshi; Rabbani, Naila; Bretschneider, Till; Rand, David A; Thornalley, Paul J

    2015-08-01

    The discovery that nuclear factor erythroid 2-related factor 2 (Nrf2) undergoes translocational oscillations from cytoplasm to nucleus in human cells with frequency modulation linked to activation of a stress-stimulated cytoprotective response raises the prospect that the Nrf2 works mechanistically analogous to a wireless sensor. Herein, we consider how this new model of Nrf2 oscillation resolves previous inexplicable experimental findings on Nrf2 regulation and why it is fit-for-purpose. Further investigation is required to assess how generally applicable the oscillatory mechanism is and if characteristics of this regulatory control can be found in vivo. It suggests there are multiple, potentially re-enforcing receptors for Nrf2 activation, indicating that potent Nrf2 activation for improved health and treatment of disease may be achieved through combination of Nrf2 system stimulants. PMID:26551710

  17. Low Frequency Electromagnetic Background Radiation From Electron Acceleration Above Thunderclouds

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    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.

  18. Frequency-domain fluorometry in the presence of high in-phase background

    NASA Astrophysics Data System (ADS)

    Vitta, P.; Reklaitis, I.; Žukauskas, A.

    2012-03-01

    We report on an approach to the measurement of fluorescence lifetimes in the frequency domain in the presence of high levels of background that is in phase with the sine-wave excitation. At high background levels, the frequency response of fluorescence waveform phase shift is shown to translate into a multicomponent function, which allows for deducing fluorescence lifetimes from the peak frequencies and magnitude of the components without explicitly knowing the level of background. Examples of the simple estimation of fluorescence lifetimes from the analysis of fluorescence frequency response for a single-exponent and two-exponent decay in inorganic phosphors within operating white light-emitting diodes are presented.

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

    PubMed

    Gibble, Kurt

    2013-05-01

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

  20. Reciprocal translocations

    SciTech Connect

    1993-12-31

    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.

  1. Combined effects of frequency and layer removal on background track characteristics of ECE polycarbonate detectors

    NASA Astrophysics Data System (ADS)

    Sohrabi, Mehdi; Soltani, Zahra; Hakimi, Amir

    2016-02-01

    Polycarbonate track detectors (PCTD) when electrochemically etched (ECE) provide excellent characteristics for registering relatively lower-LET charged particles (e.g. alphas, fast-neutron-induced recoils) for many health physics and ion detection applications.The layer removal method of PCTDs by ethylenediamine (EDA) developed in our laboratory reduces the background track (BGT) density significantly. The frequency of the applied electric field strongly affects the BGT density and diameter and thus affects the minimum detection limit (MDL). In order to study the combined effects of the frequency and layer removal on the BGT density and thus on the MDL, this research was conducted. The BGT density versus the layer thickness removed at frequencies up to 12 kHz decrease rapidly to about 10-20 μm above which they reach a minimum constant level, while the mean BGT diameter verses layer removed at all frequencies are constant with flat responses. On the other hand the BGT density and diameter versus frequency at different layers removed up to ~50 μm increase till 4 kHz above which they reach plateaus. The PCTDs with ~20 μm layer removal at frequencies up 1 to 2 kHz showed the lowest MDL. The results are presented and discussed.

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

    SciTech Connect

    Bellucci, Stefano; Capozziello, Salvatore; De Laurentis, Mariafelicia; Faraoni, Valerio

    2009-05-15

    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.

  3. Dolphins Adjust Species-Specific Frequency Parameters to Compensate for Increasing Background Noise

    PubMed Central

    Papale, Elena; Gamba, Marco; Perez-Gil, Monica; Martin, Vidal Martel; Giacoma, Cristina

    2015-01-01

    An increase in ocean noise levels could interfere with acoustic communication of marine mammals. In this study we explored the effects of anthropogenic and natural noise on the acoustic properties of a dolphin communication signal, the whistle. A towed array with four elements was used to record environmental background noise and whistles of short-beaked common-, Atlantic spotted- and striped-dolphins in the Canaries archipelago. Four frequency parameters were measured from each whistle, while Sound Pressure Levels (SPL) of the background noise were measured at the central frequencies of seven one-third octave bands, from 5 to 20 kHz. Results show that dolphins increase the whistles’ frequency parameters with lower variability in the presence of anthropogenic noise, and increase the end frequency of their whistles when confronted with increasing natural noise. This study provides the first evidence that the synergy among SPLs has a role in shaping the whistles' structure of these three species, with respect to both natural and anthropogenic noise. PMID:25853825

  4. The effects of fundamental frequency contour manipulations on speech intelligibility in background noise.

    PubMed

    Miller, Sharon E; Schlauch, Robert S; Watson, Peter J

    2010-07-01

    Previous studies have documented that speech with flattened or inverted fundamental frequency (F0) contours is less intelligible than speech with natural variations in F0. The purpose of this present study was to further investigate how F0 manipulations affect speech intelligibility in background noise. Speech recognition in noise was measured for sentences having the following F0 contours: unmodified, flattened at the median, natural but exaggerated, inverted, and sinusoidally frequency modulated at rates of 2.5 and 5.0 Hz, rates shown to make vowels more perceptually salient in background noise. Five talkers produced 180 stimulus sentences, with 30 unique sentences per F0 contour condition. Flattening or exaggerating the F0 contour reduced key word recognition performance by 13% relative to the naturally produced speech. Inverting or sinusoidally frequency modulating the F0 contour reduced performance by 23% relative to typically produced speech. These results support the notion that linguistically incorrect or misleading cues have a greater deleterious effect on speech understanding than linguistically neutral cues. PMID:20649237

  5. Background frequency of Bacillus species at the Canberra Airport: A 12 month study.

    PubMed

    Gahan, Michelle E; Thomas, Rory; Rossi, Rebecca; Nelson, Michelle; Roffey, Paul; Richardson, Michelle M; McNevin, Dennis

    2015-12-01

    Anthrax, caused by Bacillus anthracis, is a naturally occurring disease in Australia. Whilst mainly limited to livestock in grazing regions of Victoria and New South Wales, movement of people, stock and vehicles means B. anthracis could be present outside this region. Of particular interest is the "background" prevalence of B. anthracis at transport hubs including airports. The aim of this study was to determine the background frequency of B. anthracis and the commonly used hoax agent Bacillus thuringiensis at the Canberra Airport over a 12 month period. Samples were collected daily for seven days each month from August 2011-July 2012 and analyzed using species specific real-time polymerase chain reaction. Fourteen samples (of a total of 575) were positive for the B. anthracis PL3 genomic marker, 24 for the cya (pXO1) plasmid marker and five for the capB (pXO2) plasmid marker. Whilst five samples were positive for both PL3 and cya, no samples were positive for all three markers hence there is no evidence to suggest the presence of pathogenic B. anthracis strains. B. anthracis targets were detected primarily in February 2012 and B. thuringiensis peaked in October and November 2011 and again in April and May 2012. This study provides a rapid method to screen for, and differentiate, Bacillus species. Armed with this information investigators will be able to discriminate a "threat" from "background" frequencies should the need arise. PMID:26298416

  6. Multi-frequency survey of background radiations of the Universe. The "Cosmological Gene" project. First results

    NASA Astrophysics Data System (ADS)

    Parijskij, Yu. N.; Mingaliev, M. G.; Nizhel'Skii, N. A.; Bursov, N. N.; Berlin, A. B.; Grechkin, A. A.; Zharov, V. I.; Zhekanis, G. V.; Majorova, E. K.; Semenova, T. A.; Stolyarov, V. A.; Tsybulev, P. G.; Kratov, D. V.; Udovitskii, R. Yu.; Khaikin, V. B.

    2011-10-01

    The results of the first stage of the "Cosmological Gene" project of the Russian Academy of Sciences are reported. These results consist in the accumulation of multi-frequency data in 31 frequency channels in the wavelength interval 1-55 cm with maximum achievable statistical sensitivity limited by the noise of background radio sources at all wavelengths exceeding 1.38 cm. The survey region is determined by constraints 00 h < RA < 24 h and 40°30' < DEC < 42°30'. The scientific goals of the project are refined in view of recent proposals to use cosmological background radiation data for the development of a unified physical theory. Experimental data obtained with the RATAN-600 radio telescope are used to refine the contribution of the main "screens" located between the observer and the formation epoch of cosmic background radiation ( z = 1100). Experimental data for synchrotron radiation and free-free noise on scales that are of interest for the anisotropy of cosmic microwave background are reported as well as the contribution of these noise components in millimeter-wave experiments to be performed in the nearest years. The role of dipole radio emission of fullerene-type dust nanostructures is shown to be small. The most precise estimates of the role of background radio sources with inverted spectra are given and these sources are shown to create no serious interference in experiments. The average spectral indices of the weakest sources of the NVSS and FIRST catalogs are estimated. The "saturation" data for all wavelengths allowed a constraint to be imposed on the Sunyaev-Zeldovich noise (the SZ noise) at all wavelengths, and made it possible to obtain independent estimates of the average sky temperature from sources, substantially weaker than those listed in the NVSS catalog. These estimates are inconsistent with the existence of powerful extragalactic synchrotron background associated with radio sources. Appreciable "quadrupole" anisotropy in is detected in the

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

    NASA Astrophysics Data System (ADS)

    Kalugin, Alexander; Bronshtein, Alexander; Mazar, Reuven

    2004-07-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

    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. .

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

    SciTech Connect

    Levin, S.M.

    1987-04-01

    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.

  10. Cross-terms and weak frequency-dependent signals in the cosmic microwave background sky

    NASA Astrophysics Data System (ADS)

    Hernández-Monteagudo, C.; Sunyaev, R. A.

    2005-05-01

    In this paper, we study the amplification of weak frequency-dependent signals in the cosmic microwave background (CMB) sky due to their cross-correlation to intrinsic anisotropies. In particular, we centre our attention on mechanisms generating a weak signal, of peculiar spectral behaviour, such as resonant scattering in ionic, atomic or molecular lines, the thermal Sunyaev-Zel'dovich (tSZ) effect or extragalactic foreground emissions, whose typical amplitude (denoted by ɛ) is significantly smaller than the intrinsic CMB fluctuations. We find that all these effects involve either the autocorrelation of anisotropies generated during recombination (zrec) or the cross-correlation of those anisotropies with fluctuations arising at redshift zi. The former case accounts for the slight blurring of original anisotropies generated in the last scattering surface, and shows up in the small angular scale (high multipole) range. The latter term describes, instead, the generation of new anisotropies, and is non-zero only if fluctuations generated at redshifts zrec, zi, are correlated. The degree of this correlation can be computed under the assumption that density fluctuations were generated as standard inflationary models dictate and that they evolved in time according to linear theory. When the weak signal is frequency dependent (i.e. the spectral dependence of the secondary anisotropies is distinct from that of the CMB), we show that, by subtracting power spectra at different frequencies, it is possible to avoid the limit associated with cosmic variance and unveil weaker terms linear in ɛ. We find that the correlation term shows a different spectral dependence than the squared (~ɛ2) term usually considered, making its extraction particularly straightforward for the tSZ effect. Furthermore, we find that in most cases the correlation terms are particularly relevant at low multipoles due to the integrated Sachs-Wolfe effect and must be taken into account when characterizing

  11. Calibration of low-frequency radio telescopes using the galactic background radiation

    NASA Astrophysics Data System (ADS)

    Dulk, G. A.; Erickson, W. C.; Manning, R.; Bougeret, J.-L.

    2001-01-01

    We consider the calibration of flux densities of radio bursts from decametric to kilometric wavelengths using ground-based and space-based data. The method we derive is applicable to low-frequency radio telescopes where galactic background radiation is the principal contribution to system temperature. It can be particularly useful for telescopes of low angular resolution observing spectra of radio bursts from the Sun and the planets because absolute calibration of these telescopes is very difficult with conventional techniques. Here we apply the method to observations from about 7 to 47 MHz that were made on the ground with the Bruny Island Radio Spectrometer located in Tasmania, Australia, and those from about 20 kHz to 13.8 MHz were made with the radio experiment WAVES on the WIND spacecraft. The spectrum of the galactic background radiation from <1 to >30 MHz has been carefully measured with low-resolution telescopes, starting more than a decade ago. We use this known spectrum to calibrate both BIRS and WAVES on an absolute scale. The accuracy we achieve is about a factor of two, whereas the flux densities of solar and planetary radio sources vary by many orders of magnitude. Our method permits inter-calibration of ground-based and space-based observations, and allows corrections to be made for instrumental uncertainties on both radio experiments. In addition, on the ground, it allows the spectra to be corrected for ionospheric absorption and partial ground reflections. As an application we show the spectrum of a solar type III burst observed from 47 MHz to 20 kHz. Its flux density was largest, S~ 10-17 W m-2 Hz-1, at about 3 MHz, while at 60 kHz and at 47 MHz it was lower by a factor of about 300.

  12. Observations of the radio noise background in the frequency range 150-180 kHz

    NASA Astrophysics Data System (ADS)

    Knowles, S. H.; Kelly, F. J.; Waltman, W. B.; Odenwald, S.

    1985-05-01

    Observations were made of the radio noise background in the frequency range 150-180 kHz to provide reference data for the design of the ground wave emergency network system. These observations were undertaken at Nanjemoy, Maryland, during early summer 1983 and included 41 days of data recording. The noise environment was found to be dominated by impulsive thunderstorm noise. A typical nighttime mean noise power spectral density was 1×10-15 W m-2 Hz-1 (noise factor of 107 dB above kT0), while a typical daytime level was at least 14 dB quieter. However, the daytime level was at times significantly higher, especially during the presence of a local thunderstorm front. During local thunderstorm activity, impulses with peak power spectral density of 1×10-14 W m-2 Hz-1 were observed frequently, while the most energetic pulse detected during our monitoring period had a peak power spectral density of 6.8×10-14 W m-2 Hz-1 (Fa = 125 dB). Sample amplitude probability distributions and time probability distributions are presented for day/quiet, night, and thunderstorm conditions. Agreement with the mean noise level predictions of CCIR report 322 is satisfactory within the accuracy limits of the CCIR data.

  13. Phenomenal Background Frequency and the Concreteness/Imagery Effect in Verbal Discrimination Learning.

    ERIC Educational Resources Information Center

    Ghatala, Elizabeth S.; Levin, Joel R.

    This study consisted of two experiments. In the first experiment, 40 college students gave frequency ratings for concrete and abstract words which were equated on normative frequency. From the results it was concluded that abstract (low imagery) words, even though the two sets of words are of equal frequency. In the second experiment, different…

  14. Lack of evidence for an association between the frequency of mutants or translocations in circulating lymphocytes and exposure to radon gas in the home

    SciTech Connect

    Cole, J.; Green, M.H.L.; Bridges, B.A.

    1996-01-01

    Radon measurements in the living room and main bedroom of 41 houses in the town of Street, Somerset, England have been made. Exposure levels, weighted using the formula of the UK National Radiological Protection Board, of 19-484 Bq m{sup -3} (about half >100 Bq m{sup -3}) were found. Blood samples were obtained from a total of 66 occupants in these homes, and the frequency of genetic alterations in lymphocytes was estimated using two different end points. Gene mutations at the hypoxanthine guanine phosphoribosyl transferase locus were determined in T lymphocytes for 65 subjects using a clonal assay, and the frequency of the BCL-2 t(14;18) translocation, a chromosomal event associated with leukemia/lymphoma, was estimated in lymphocytes using a polymerase chain reaction-based technique for 64 subjects. In neither case was a significant correlation with radon levels in the home found, in contrast to our earlier observation with a smaller series. 52 refs., 5 figs., 2 tabs.

  15. Cryocooled terahertz photoconductive detector system with background-limited performance in 1.5-4 THz frequency range

    NASA Astrophysics Data System (ADS)

    Aoki, Makoto; Hiromoto, Norihisa

    2015-10-01

    We describe a 4-K-cryocooled dual-band terahertz (THz) photoconductive detector system with background-limited performance. The detector system comprises two THz photoconductive detectors covering a response in a wide frequency range from 1.5 to 4 THz, low noise amplifiers, optical low-pass filters to eliminate input radiation of higher frequencies, and a mechanical 4 K Gifford-McMahon refrigerator that provides practical and convenient operation without a liquid He container. The electrical and optical performances of the THz detector system were evaluated at a detector temperature of 4 K under 300 K background radiation. We proved that the detector system can achieve background-limited noise-equivalent-power on the order of 10-14 W/Hz1/2 in the frequency range from 1.5 to 4 THz even if the vibration noise of the mechanical refrigerator is present.

  16. Cryocooled terahertz photoconductive detector system with background-limited performance in 1.5-4 THz frequency range.

    PubMed

    Aoki, Makoto; Hiromoto, Norihisa

    2015-10-01

    We describe a 4-K-cryocooled dual-band terahertz (THz) photoconductive detector system with background-limited performance. The detector system comprises two THz photoconductive detectors covering a response in a wide frequency range from 1.5 to 4 THz, low noise amplifiers, optical low-pass filters to eliminate input radiation of higher frequencies, and a mechanical 4 K Gifford-McMahon refrigerator that provides practical and convenient operation without a liquid He container. The electrical and optical performances of the THz detector system were evaluated at a detector temperature of 4 K under 300 K background radiation. We proved that the detector system can achieve background-limited noise-equivalent-power on the order of 10(-14) W/Hz(1/2) in the frequency range from 1.5 to 4 THz even if the vibration noise of the mechanical refrigerator is present. PMID:26520978

  17. Cryocooled terahertz photoconductive detector system with background-limited performance in 1.5–4 THz frequency range

    SciTech Connect

    Aoki, Makoto; Hiromoto, Norihisa

    2015-10-15

    We describe a 4-K-cryocooled dual-band terahertz (THz) photoconductive detector system with background-limited performance. The detector system comprises two THz photoconductive detectors covering a response in a wide frequency range from 1.5 to 4 THz, low noise amplifiers, optical low-pass filters to eliminate input radiation of higher frequencies, and a mechanical 4 K Gifford-McMahon refrigerator that provides practical and convenient operation without a liquid He container. The electrical and optical performances of the THz detector system were evaluated at a detector temperature of 4 K under 300 K background radiation. We proved that the detector system can achieve background-limited noise-equivalent-power on the order of 10{sup −14} W/Hz{sup 1/2} in the frequency range from 1.5 to 4 THz even if the vibration noise of the mechanical refrigerator is present.

  18. Fringe-free, background-free, collinear third-harmonic generation frequency-resolved optical gating measurements for multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Chadwick, Rebecca; Spahr, Erik; Squier, Jeff A.; Durfee, Charles G.; Walker, Barry C.; Fittinghoff, David N.

    2006-11-01

    A background-free, fringe-free form of frequency-resolved optical gating using the third-harmonic signal generated from a glass coverslip is used to characterize 100 fs pulses at the focus of a 0.65 NA objective.

  19. Effects of fast-acting high-frequency compression on the intelligibility of speech in steady and fluctuating background sounds.

    PubMed

    Stone, M A; Moore, B C; Wojtczak, M; Gudgin, E

    1997-08-01

    This study examines whether speech intelligibility in background sounds can be improved for persons with loudness recruitment by the use of fast-acting compression applied at high frequencies, when the overall level of the sounds is held constant by means of a slow-acting automatic gain control (AGC) system and when appropriate frequency-response shaping is applied. Two types of fast-acting compression were used in the high-frequency channel of a two-channel system: a compression limiter with a 10:1 compression ratio and with a compression threshold about 9 dB below the peak level of the signal in the high-frequency channel; and a wide dynamic range compressor with a 2:1 compression ratio and with the compression threshold about 24 dB below the peak level of the signal in the high-frequency channel. A condition with linear processing in the high-frequency channel was also used. Speech reception thresholds (SRTs) were measured for two background sounds: a steady speech-shaped noise and a single male talker. All subjects had moderate-to-severe sensorineural hearing loss. Three different types of speech material were used: the adaptive sentence lists (ASL), the Bamford-Kowal-Bench (BKB) sentence lists and the Boothroyd word lists. For the steady background noise, the compression generally led to poorer performance than for the linear condition, although the deleterious effect was only significant for the 10:1 compression ratio. For the background of a single talker, the compression had no significant effect except for the ASL sentences, where the 10:1 compression gave significantly better performance than the linear condition. Overall, the results did not show any clear benefits of the fast-acting compression, possibly because the slow-acting AGC allowed the use of gains in the linear condition that were markedly higher than would normally be used with linear hearing aids. PMID:9307821

  20. Low-Frequency Measurments of the Cosmic Background RadiationSpectrum

    SciTech Connect

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

    1984-11-01

    The long-wavelength spectrum of the cosmic background radiation has been measured at five wavelengths (0.33, 0.9, 3.0, 6.3, and 12.0 cm). These measurements represent a continuation of the work reported by Smoot et al. (1983). The combine results have a weighted average of 2.73 {+-} 0.05 K and are consistent with past measurements. They limit the possible Compton distortion of the Cosmic Background Radiation spectrum to less than 8%.

  1. Robertsonian translocations

    SciTech Connect

    1993-12-31

    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.

  2. Low Frequency Measurement of the Spectrum of the Cosmic Background Radiation

    DOE R&D Accomplishments Database

    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

    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.

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

    SciTech Connect

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

    2014-12-15

    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.

  4. Frequency multiplexed superconducting quantum interference device readout of large bolometer arrays for cosmic microwave background measurements.

    PubMed

    Dobbs, M A; Lueker, M; 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

    2012-07-01

    A technological milestone for experiments employing transition edge sensor 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 operating at 4 K. Room temperature electronics demodulate the carriers to recover the bolometer signals, which are digitized separately and stored to disk. This readout system contributes little noise relative to the detectors themselves, is remarkably insensitive to unwanted microphonic excitations, and provides a technology pathway to multiplexing larger numbers of sensors. PMID:22852677

  5. Major Existence of Very Low Frequency Earthquakes in Background Seismicity Along Subduction Zone of South-western Japan

    NASA Astrophysics Data System (ADS)

    Ishihara, Y.

    2003-12-01

    distributed in island arc side. The very low frequency earthquakes occur in outer area of seismic generation zone. The other zone is coincided with extended zone generating low frequency seismic events. Very low frequency earthquake occurs intermittently in limited area. Frequently, activity increases for some days and swarm type activity generates occasionally. To evaluate integrated seismicity for anomalous events, same class magnitude, greater than 3.0, events occurred in same and surrounding area are picked up from JMA earthquake catalogue. The analysis shows that seismicity of very low frequency earthquakes is comparative with one of normal earthquakes in background activity. We concluded that very low frequency earthquake is one of factors playing seismically important role.

  6. Polarimeter Arrays with Comprehensive Frequency Coverage for the Next Generation of Precision Microwave Background Experiments

    NASA Astrophysics Data System (ADS)

    Austermann, Jason Edward; Beall, James; Becker, Dan; Cho, Hsiao-Mei; Duff, Shannon; gao, jiansong; Hilton, Gene; Hubmayr, Johannes; Irwin, Kent; li, dale; McKenney, Christopher; Ullom, Joel; van lanen, jeffrey; Vissers, Michael

    2016-06-01

    Spectral resolution at (sub-)millimeter wavelengths is now understood to be crucially important in precision measurements of the cosmic microwave background (CMB). Recent results from the Planck and BICEP/KECK experiments have established that measurements of the CMB polarization signal is limited, in part, by polarized foreground emission. In particular, polarized emission from galactic dust has been found to dominate and obscure potential signals of cosmic inflation, even in regions of the sky specifically identified as having relatively low galactic emission. Current and future experiments aim to address foreground contamination by conducting high-sensitivity observations with broad spectral coverage that will allow for differentiation within the measured signal between foreground sources of polarization and that of the CMB, which each have distinct spectral characteristics. To efficiently achieve these goals within a limited focal plane area, NIST-Boulder has developed multi-band TES-based polarimeters that simultaneously measure multiple spectral bands in each of two orthogonal polarizations. This acts to both increase pixel sensitivity through an increased total bandwidth, as well as providing broad spectral information for differentiation of emission sources. Here, we describe recent achievements and ongoing efforts at NIST-Boulder in the development of millimeter and sub-millimeter detector and focal plane technologies for future experiments, including the stage-IV CMB experiment, CMB-S4. NIST-Boulder provides critical cryogenic components to a large number of current and in-development CMB experiments. Recent milestones include the fielding of the first broadband multi-chroic mm-wave polarimeters in the ACTPol experiment, multi-band array fabrication on large-format 150 mm wafers, and development of matching 150 mm silicon platelet feedhorn arrays. We also review several related development efforts in detector, optical coupling, and readout technologies

  7. Frequency and genetic background of the position 122 (Val----Ile) variant transthyretin gene in the black population.

    PubMed Central

    Jacobson, D R; Reveille, J D; Buxbaum, J N

    1991-01-01

    Transthyretin (TTR) (122 Val----Ile), caused by a point mutation which destroys a MaeIII restriction site, is associated with cardiac amyloidosis in black individuals. To estimate the frequency of the MaeIII(-) gene in the black population without overt cardiac disease, DNA from 177 black individuals without amyloidosis was amplified by the PCR around TTR codon 122 and was digested with MaeIII. The MaeIII(-) gene frequency was 4/354 (1.1%; 95% confidence interval 0.32%2.7%), suggesting that the variant is relatively common in blacks. HLA genotype testing did not suggest that the TTR (122 Val----Ile) heterozygotes were of a closely related genetic background. Images Figure 2 PMID:2063870

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

    PubMed

    Speir, Jacqueline A; Hietpas, Jack

    2014-09-01

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

  9. High Frequency Propagation modeling in a disturbed background ionosphere: Results from the Metal Oxide Space Cloud (MOSC) experiment

    NASA Astrophysics Data System (ADS)

    Joshi, D. R.; Groves, K. M.

    2015-12-01

    The Air Force Research Laboratory (AFRL) launched two sounding rockets in the Kwajalein Atoll, Marshall Islands, in May 2013 known as the Metal Oxide Space Cloud (MOSC) experiment to study the interactions of artificial ionization and the background plasma. The rockets released samarium metal vapor in the lower F-region of the ionosphere that ionized forming a plasma cloud. A host of diagnostic instruments were used to probe and characterize the cloud including the ALTAIR incoherent scatter radar, multiple GPS and optical instruments, satellite radio beacons, and a dedicated network of high frequency (HF) radio links. Data from ALTAIR incoherent scatter radar and HF radio links have been analyzed to understand the impacts of the artificial ionization on radio wave propagation. During the first release the ionosphere was disturbed, rising rapidly and spread F formed within minutes after the release. To address the disturbed conditions present during the first release, we have developed a new method of assimilating oblique ionosonde data to generate the background ionosphere that can have numerous applications for HF systems. The link budget analysis of the received signals from the HF transmitters explains the missing low frequencies in the received signals along the great circle path. Observations and modeling confirm that the small amounts of ionized material injected in the lower-F region resulted in significant changes to the natural propagation environment.

  10. Adaptation of frequency-domain readout for Transition Edge Sensor bolometers for the POLARBEAR-2 Cosmic Microwave Background experiment

    NASA Astrophysics Data System (ADS)

    Hattori, Kaori; Arnold, Kam; Barron, Darcy; Dobbs, Matt; de Haan, Tijmen; Harrington, Nicholas; Hasegawa, Masaya; Hazumi, Masashi; Holzapfel, William L.; Keating, Brian; Lee, Adrian T.; Morii, Hideki; Myers, Michael J.; Smecher, Graeme; Suzuki, Aritoki; Tomaru, Takayuki

    2013-12-01

    The POLARBEAR-2 Cosmic Microwave Background (CMB) experiment aims to observe B-mode polarization with high sensitivity to explore gravitational lensing of CMB and inflationary gravitational waves. POLARBEAR-2 is an upgraded experiment based on POLARBEAR-1, which had first light in January 2012. For POLARBEAR-2, we will build a receiver that has 7588 Transition Edge Sensor (TES) bolometers coupled to two-band (95 and 150 GHz) polarization-sensitive antennas. For the large array's readout, we employ digital frequency-domain multiplexing and multiplex 32 bolometers through a single superconducting quantum interference device (SQUID). An 8-bolometer frequency-domain multiplexing readout has been deployed with the POLARBEAR-1 experiment. Extending that architecture to 32 bolometers requires an increase in the bandwidth of the SQUID electronics to 3 MHz. To achieve this increase in bandwidth, we use Digital Active Nulling (DAN) on the digital frequency multiplexing platform. In this paper, we present requirements and improvements on parasitic inductance and resistance of cryogenic wiring and capacitors used for modulating bolometers. These components are problematic above 1 MHz. We also show that our system is able to bias a bolometer in its superconducting transition at 3 MHz.

  11. Spectroscopic Measurement of High-Frequency Electric Fields in the Interaction of Explosive Debris Plasma with Ambient, Magnetized Background Plasma

    NASA Astrophysics Data System (ADS)

    Bondarenko, Anton; Schaeffer, Derek; Everson, Erik; Clark, Eric; Vincena, Stephen; van Compernolle, Bart; Tripathi, Shreekrishna; Constantin, Carmen; Niemann, Chris

    2014-10-01

    The explosive expansion of dense, high-beta debris plasma into relatively tenuous, magnetized background plasma is relevant to a wide variety of astrophysical and space environments. Electric fields play a fundamental role in the coupling of momentum and energy from debris to background, and emission spectroscopy provides a powerful diagnostic for assessing electric fields via the Stark effect. A recent experiment utilizing a unique experimental platform at UCLA that combines the Large Plasma Device and the Raptor laser facility has investigated the super-Alfvénic, quasi-perpendicular expansion of a laser-produced carbon (C) debris plasma through a preformed, ambient, magnetized helium (He) background plasma via emission spectroscopy. Spectral profiles of the He II 468.6 nm line have been analyzed via single-mode and multi-mode time-dependent Stark broadening models for hydrogen-like ions, yielding large magnitude (~100 kV/cm), high-frequency (~100 GHz) electric fields. The measurements suggest the development of an electron beam-plasma instability, and a simple instability saturation model demonstrates that the measured electric field magnitudes are feasible under the experimental conditions.

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

    SciTech Connect

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

    1989-06-01

    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).

  13. IL-21 and Probiotic Therapy Improve TH17 Frequencies, Microbial Translocation, and Microbiome in ARV-Treated, SIV-Infected Macaques

    PubMed Central

    Ortiz, Alexandra M.; Klase, Zachary A.; DiNapoli, Sarah R.; Vujkovic-Cvijin, Ivan; Carmack, Kirby; Perkins, Molly R.; Calantone, Nina; Vinton, Carol L.; Riddick, Nadeene E.; Gallagher, John; Klatt, Nichole R.; McCune, Joseph M.; Estes, Jacob D.; Paiardini, Mirko; Brenchley, Jason M.

    2015-01-01

    Increased mortality in antiretroviral (ARV)-treated, HIV-infected individuals has been attributed to persistent immune dysfunction, in part due to abnormalities at the gastrointestinal barrier. In particular, the poor reconstitution of gastrointestinal TH17 cells correlates with residual translocation of dysbiotic, immunostimulatory microflora across a compromised intestinal epithelial barrier. We have previously demonstrated that oral probiotics promote increased intestinal CD4+ T-cell reconstitution during ARV treatment in a non-human primate model of HIV infection; however, essential mucosal T-cell subsets, such as TH17 cells, had limited recovery. Here, we sought to promote TH17 cell recovery by administering IL-21 to a limited number of ARV-treated, probiotic-supplemented, SIV-infected pigtailed macaques. We demonstrate that probiotic and IL-21 supplementation of ARVs is associated with enhanced polyfunctional TH17 expansion and reduced markers of microbial translocation and dysbiosis as compared to infected controls receiving ARVs alone. Importantly, treatment resulted in fewer morbidities compared to controls, and was independent of increased immune activation or loss of viral suppression. We propose that combining ARVs with therapeutics aimed at restoring intestinal stasis may significantly improve disease prognosis of ARV-treated, HIV-infected, individuals. PMID:26286233

  14. Signal photon flux and background noise in a coupling electromagnetic detecting system for high-frequency gravitational waves

    NASA Astrophysics Data System (ADS)

    Li, Fangyu; Yang, Nan; Fang, Zhenyun; Baker, Robert M. L., Jr.; Stephenson, Gary V.; Wen, Hao

    2009-09-01

    A coupling system among Gaussian-type microwave photon flux, a 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 the pure inverse Gertsenshtein effect (G effect) caused by the HFGWs in the gigahertz band, the electromagnetic (EM) detecting scheme proposed by China and the U.S. HFGW groups is based on the composite effect of the synchroresonance effect and the inverse G effect. The key parameter in the scheme is the 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 ˜103-105 seconds for the typical laboratory condition and parameters of hrms˜10-26-10-30/Hz at 5 GHz with bandwidth ˜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.

  15. Long-distance translocations to create a second millerbird population and reduce extinction risk

    USGS Publications Warehouse

    Holly Freifeld; Sheldon Plentovich; Chris Farmer; Charles Kohley; Peter Luscomb; Work, Thierry M.; Daniel Tsukayama; George Wallace; Mark MacDonald; Sheila Conant

    2016-01-01

    Translocation is a conservation tool used with increasing frequency to create additional populations of threatened species. In addition to following established general guidelines for translocations, detailed planning to account for unique circumstances and intensive post-release monitoring to document outcomes and guide management are essential components of these projects. Recent translocation of the critically endangered Nihoa millerbird (Acrocephalus familiaris kingi) provides an example of this planning and monitoring. The Nihoa millerbird is a passerine bird endemic to Nihoa Island in the remote Northwestern Hawaiian Islands. The closely related, ecologically similar Laysan millerbird (Acrocephalus familiaris familiaris) went extinct on Laysan Island in the early 20th century when the island was denuded by introduced rabbits. To reduce extinction risk, we translocated 50 adult Nihoa millerbirds more than 1000 km by sea to Laysan, which has recovered substantially in the past century and has ample habitat and a rich prey-base for millerbirds. Following five years of intensive background research and planning, including development of husbandry techniques, fundraising, and regulatory compliance, translocations occurred in 2011 and 2012. Of 11 females in each cohort, 8 (2011 cohort) and 11 (2012 cohort) produced at least one brood of fledglings during their first year on Laysan. At the conclusion of monitoring in September 2014, 37 of the translocated birds were known to survive, and the population was estimated at 164 birds. The reintroduction of millerbirds to Laysan represents a milestone in the island's ongoing restoration.

  16. Background rhythm frequency and theta power of quantitative EEG analysis: predictive biomarkers for cognitive impairment post-cerebral infarcts.

    PubMed

    Song, Yang; Zang, Da-Wei; Jin, Yan-Yu; Wang, Zhi-Jun; Ni, Hong-Yan; Yin, Jian-Zhong; Ji, Dong-Xu

    2015-04-01

    In clinical settings, cerebral infarct is a common disease of older adults, which usually increases the risk of cognitive impairment. This study aims to assess the quantitative electroencephalography (qEEG) as a predictive biomarker for the development of cognitive impairment, post-cerebral infarcts, in subjects from the Department of Neurology. They underwent biennial EEG recording. Cerebral infarct subjects, with follow-up cognitive evaluation, were analyzed for qEEG measures of background rhythm frequency (BRF) and relative δ, θ, α, and β band power. The relationship between cognitive impairment and qEEG, and other possible predictors, was assessed by Cox regression. The results showed that the risk hazard of developing cognitive impairment was 14 times higher for those with low BRF than for those with high BRF (P < .001). Hazard ratio (HR) was also significant for more than median θ band power (HR = 5, P = .002) compared with less than median θ band power. The HRs for δ, α, and β bands were equal to the baseline demographic, and clinical characteristics were not significantly different. In conclusion, qEEG measures of BRF, and relative power in θ band, are potential predictive biomarkers for cognitive impairment in patients with cerebral infarcts. These biomarkers might be valuable in early prediction of cognitive impairment in patients with cerebral infarcts. PMID:24699438

  17. Investigating binding particles distribution effects on polymer translocation through nanopore

    NASA Astrophysics Data System (ADS)

    Haji Abdolvahab, Rouhollah

    2016-03-01

    Chaperone driven polymer translocation is an important model for biopolymer's translocation in vivo. Binding proteins spatial distribution is a significant factor in calculating the translocation time of the polymer in this type of translocation. Here using a dynamical Monte Carlo simulation we compare the results of the usual uniform distribution with the exponential distribution of different rates for a stiff polymer. Our simulation results show that just by changing the chaperones spatial distribution the translocation time of the biopolymer will change by as large as an order. It can change the translocation regime of the polymer completely from a diffusive to a ballistic one. Although generally increasing the exponential rate and the background concentration will increase the translocation velocity, it is not always true and one should consider both the sequence and the background concentration. We show that the results depend on the sequence and changing the distribution rates for increasing the translocation velocity will change the whole Probability Density Function (PDF) of the polymer translocation time accordance to its sequence. The translocation time sequence dependency will change in the extreme cases e.g. in the high exponential rate. Investigating the binding protein size, λ, also shows the importance of the so called parking lot effect in distribution dependency of the translocation velocity. Although there is not any important dependency for λ = 1, translocation time depends clearly on the chaperone spatial distribution for the case of λ ≥ 2.

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

    PubMed

    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

    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

  19. Mode of ATM-dependent suppression of chromosome translocation

    SciTech Connect

    Yamauchi, Motohiro; Suzuki, Keiji; Oka, Yasuyoshi; Suzuki, Masatoshi; Kondo, Hisayoshi; Yamashita, Shunichi

    2011-12-09

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

  20. Increase in frequencies of circulating Th-17 cells correlates with microbial translocation, immune activation and exhaustion in HIV-1 infected patients with poor CD4 T-cell reconstitution.

    PubMed

    Valiathan, Ranjini; Asthana, Deshratn

    2016-05-01

    We analyzed the association of circulating Th-17 cells (cTh-17) with immune activation (IA), immune exhaustion (IE) and regulatory T-cells (T-regs) in 20 human immunodeficiency virus-1 (HIV-1) infected patients with impaired restoration of CD4 T-cell counts despite prolonged suppression of plasma viremia (discordant) and compared it with 20 HIV-1 infected patients showing good immunologic and virologic responses (concordant) following highly active antiretroviral therapy (HAART). Discordant HIV-1 infected patients showed significantly higher frequencies of cTh-17 cells compared to concordant patients and healthy controls after PMA+Ionomicin stimulation. Discordant patients also showed higher CD4 T-cell immune activation (HLA-DR+CD38+) than concordant patients which directly correlated with microbial translocation. Additionally, CD4 T-cells of discordant patients showed higher frequencies of CD4 T-cells expressing multiple immune exhaustion markers (Tim3+PD-1+) which correlated with immune activation indicating that combined analysis of inhibitory molecules along with PD-1 might be a better predictor for immune exhaustion of CD4 T-cells. Increased cTh-17 cell frequency correlated inversely with CD4 T-cell percentages and absolute counts and directly with CD4 T-cell immune activation and T-reg frequencies. Persistent CD4 T-cell immune activation might favor differentiation of activated CD4 T-cells toward cTh-17 phenotype in discordant patients. Discordant patients had significantly lower baseline CD4 T-cell counts and higher viral load at the initiation of HAART and higher immune activation and immune exhaustion after being on HAART for long time indicating that these factors might be associated with an increase in cTh-17 cell frequency, thus, increasing the risk of disease progression despite virologic control. PMID:26817581

  1. Physiology in conservation translocations

    PubMed Central

    Tarszisz, Esther; Dickman, Christopher R.; Munn, Adam J.

    2014-01-01

    Conservation translocations aim to restore species to their indigenous ranges, protect populations from threats and/or reinstate ecosystem functions. They are particularly important for the conservation and management of rare and threatened species. Despite tremendous efforts and advancement in recent years, animal conservation translocations generally have variable success, and the reasons for this are often uncertain. We suggest that when little is known about the physiology and wellbeing of individuals either before or after release, it will be difficult to determine their likelihood of survival, and this could limit advancements in the science of translocations for conservation. In this regard, we argue that physiology offers novel approaches that could substantially improve translocations and associated practices. As a discipline, it is apparent that physiology may be undervalued, perhaps because of the invasive nature of some physiological measurement techniques (e.g. sampling body fluids, surgical implantation). We examined 232 publications that dealt with translocations of terrestrial vertebrates and aquatic mammals and, defining ‘success’ as high or low, determined how many of these studies explicitly incorporated physiological aspects into their protocols and monitoring. From this review, it is apparent that physiological evaluation before and after animal releases could progress and improve translocation/reintroduction successes. We propose a suite of physiological measures, in addition to animal health indices, for assisting conservation translocations over the short term and also for longer term post-release monitoring. Perhaps most importantly, we argue that the incorporation of physiological assessments of animals at all stages of translocation can have important welfare implications by helping to reduce the total number of animals used. Physiological indicators can also help to refine conservation translocation methods. These approaches fall

  2. Cryptic genomic imbalances in patients with de novo or familial apparently balanced translocations and abnormal phenotype

    PubMed Central

    Sismani, Carolina; Kitsiou-Tzeli, Sofia; Ioannides, Marios; Christodoulou, Christodoulos; Anastasiadou, Violetta; Stylianidou, Goula; Papadopoulou, Eleftheria; Kanavakis, Emanuel; Kosmaidou-Aravidou, Zoe; Patsalis, Philippos C

    2008-01-01

    Background Carriers of apparently balanced translocations are usually phenotypically normal; however in about 6% of de novo cases, an abnormal phenotype is present. In the current study we investigated 12 patients, six de novo and six familial, with apparently balanced translocations and mental retardation and/or congenital malformations by applying 1 Mb resolution array-CGH. In all de novo cases, only the patient was a carrier of the translocation and had abnormal phenotype. In five out of the six familial cases, the phenotype of the patient was abnormal, although the karyotype appeared identical to other phenotypically normal carriers of the family. In the sixth familial case, all carriers of the translocations had an abnormal phenotype. Results Chromosomal and FISH analyses suggested that the rearrangements were "truly balanced" in all patients. However, array-CGH, revealed cryptic imbalances in three cases (3/12, 25%), two de novo (2/12, 33.3%) and one familial (1/12, 16.6%). The nature and type of abnormalities differed among the cases. In the first case, what was identified as a de novo t(9;15)(q31;q26.1), a complex rearrangement was revealed involving a ~6.1 Mb duplication on the long arm of chromosome 9, an ~10 Mb deletion and an inversion both on the long arm of chromosome 15. These imbalances were located near the translocation breakpoints. In the second case of a de novo t(4;9)(q25;q21.2), an ~6.6 Mb deletion was identified on the short arm of chromosome 7 which is unrelated to the translocation. In the third case, of a familial, t(4;7)(q13.3;p15.3), two deletions of ~4.3 Mb and ~2.3 Mb were found, each at one of the two translocation breakpoints. In the remaining cases the translocations appeared balanced at 1 Mb resolution. Conclusion This study investigated both de novo and familial apparently balanced translocations unlike other relatively large studies which are mainly focused on de novo cases. This study provides additional evidence that cryptic

  3. The adult polyglucosan body disease mutation GBE1 c.1076A>C occurs at high frequency in persons of Ashkenazi Jewish background.

    PubMed

    Hussain, Abrar; Armistead, Joy; Gushulak, Lara; Kruck, Christa; Pind, Steven; Triggs-Raine, Barbara; Natowicz, Marvin R

    2012-09-21

    Mutations of the glycogen branching enzyme gene, GBE1, result in glycogen storage disease (GSD) type IV, an autosomal recessive disorder having multiple clinical forms. One mutant allele of this gene, GBE1 c.1076A>C, has been reported in Ashkenazi Jewish cases of an adult-onset form of GSD type IV, adult polyglucosan body disease (APBD), but no epidemiological analyses of this mutation have been performed. We report here the first epidemiological study of this mutation in persons of Ashkenazi Jewish background and find that this mutation has a gene frequency of 1 in 34.5 (95% CI: 0.0145-0.0512), similar to the frequency of the common mutation causing Tay-Sachs disease among Ashkenazi Jews. This finding reveals APBD to be another monogenic disorder that occurs with increased frequency in persons of Ashkenazi Jewish ancestry. PMID:22943850

  4. Stochastic resonance during a polymer translocation process.

    PubMed

    Mondal, Debasish; Muthukumar, M

    2016-04-14

    We have studied the occurrence of stochastic resonance when a flexible polymer chain undergoes a single-file translocation through a nano-pore separating two spherical cavities, under a time-periodic external driving force. The translocation of the chain is controlled by a free energy barrier determined by chain length, pore length, pore-polymer interaction, and confinement inside the donor and receiver cavities. The external driving force is characterized by a frequency and amplitude. By combining the Fokker-Planck formalism for polymer translocation and a two-state model for stochastic resonance, we have derived analytical formulas for criteria for emergence of stochastic resonance during polymer translocation. We show that no stochastic resonance is possible if the free energy barrier for polymer translocation is purely entropic in nature. The polymer chain exhibits stochastic resonance only in the presence of an energy threshold in terms of polymer-pore interactions. Once stochastic resonance is feasible, the chain entropy controls the optimal synchronization conditions significantly. PMID:27083746

  5. Stochastic resonance during a polymer translocation process

    NASA Astrophysics Data System (ADS)

    Mondal, Debasish; Muthukumar, M.

    2016-04-01

    We have studied the occurrence of stochastic resonance when a flexible polymer chain undergoes a single-file translocation through a nano-pore separating two spherical cavities, under a time-periodic external driving force. The translocation of the chain is controlled by a free energy barrier determined by chain length, pore length, pore-polymer interaction, and confinement inside the donor and receiver cavities. The external driving force is characterized by a frequency and amplitude. By combining the Fokker-Planck formalism for polymer translocation and a two-state model for stochastic resonance, we have derived analytical formulas for criteria for emergence of stochastic resonance during polymer translocation. We show that no stochastic resonance is possible if the free energy barrier for polymer translocation is purely entropic in nature. The polymer chain exhibits stochastic resonance only in the presence of an energy threshold in terms of polymer-pore interactions. Once stochastic resonance is feasible, the chain entropy controls the optimal synchronization conditions significantly.

  6. Translocation of reptating chains

    NASA Astrophysics Data System (ADS)

    Żurek, S.; Drzewiński, A.; van Leeuwen, J. M. J.

    2011-05-01

    Voltage-driven translocation is modeled with the Rubinstein-Duke rules for hopping reptons in one- and two-dimensional lattices. The chain is driven through the pore by a bias potential promoting the transition of stored length in one direction. Coupling states give a semi-periodicity of the process that enables us to relate the properties to the stationary state of the master equation. The exact solution for short chains and Monte Carlo simulations for longer chains are used to calculate displacements, velocities and the translocation time.

  7. Problem-Elephant Translocation: Translocating the Problem and the Elephant?

    PubMed Central

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

    2012-01-01

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

  8. Simulations of Polymer Translocation

    NASA Astrophysics Data System (ADS)

    Vocks, H.

    2008-07-01

    Transport of molecules across membranes is an essential mechanism for life processes. These molecules are often long, and the pores in the membranes are too narrow for the molecules to pass through as a single unit. In such circumstances, the molecules have to squeeze -- i.e., translocate -- themselves through the pores. DNA, RNA and proteins are such naturally occuring long molecules in a variety of biological processes. Understandably, the process of translocation has been an active topic of current research: not only because it is a cornerstone of many biological processes, but also due to its relevance for practical applications. Translocation is a complicated process in living organisms -- the presence of chaperone molecules, pH, chemical potential gradients, and assisting molecular motors strongly influence its dynamics. Consequently, the translocation process has been empirically studied in great variety in biological literature. Study of translocation as a biophysical process is more recent. Herein, the polymer is simplified to a sequentially connected string of N monomers as it passes through a narrow pore on a membrane. The quantities of interest are the typical time scale for the polymer to leave a confining cell (the ``escape of a polymer from a vesicle'' time scale), and the typical time scale the polymer spends in the pore (the ``dwell'' time scale) as a function of N and other parameters like membrane thickness, membrane adsorption, electrochemical potential gradient, etc. Our research is focused on computer simulations of translocation. Since our main interest is in the scaling properties, we use a highly simplified description of the translocation process. The polymer is described as a self-avoiding walk on a lattice, and its dynamics consists of single-monomer jumps from one lattice site to another neighboring one. Since we have a very efficient program to simulate such polymer dynamics, which we decribe in Chapter 2, we can perform long

  9. Oncogene Translocations and NHL

    Cancer.gov

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

  10. Reciprocal translocations in Saccharomyces cerevisiae formed by nonhomologous end joining.

    PubMed

    Yu, Xin; Gabriel, Abram

    2004-02-01

    Reciprocal translocations are common in cancer cells, but their creation is poorly understood. We have developed an assay system in Saccharomyces cerevisiae to study reciprocal translocation formation in the absence of homology. We induce two specific double-strand breaks (DSBs) simultaneously on separate chromosomes with HO endonuclease and analyze the subsequent chromosomal rearrangements among surviving cells. Under these conditions, reciprocal translocations via nonhomologous end joining (NHEJ) occur at frequencies of approximately 2-7 x 10(-5)/cell exposed to the DSBs. Yku80p is a component of the cell's NHEJ machinery. In its absence, reciprocal translocations still occur, but the junctions are associated with deletions and extended overlapping sequences. After induction of a single DSB, translocations and inversions are recovered in wild-type and rad52 strains. In these rearrangements, a nonrandom assortment of sites have fused to the DSB, and their junctions show typical signs of NHEJ. The sites tend to be between open reading frames or within Ty1 LTRs. In some cases the translocation partner is formed by a break at a cryptic HO recognition site. Our results demonstrate that NHEJ-mediated reciprocal translocations can form in S. cerevisiae as a consequence of DSB repair. PMID:15020464

  11. Multiscale control of summertime persistent heavy precipitation events over South China in association with synoptic, intraseasonal, and low-frequency background

    NASA Astrophysics Data System (ADS)

    Li, Richard C. Y.; Zhou, Wen

    2015-08-01

    This study examines persistent and short-lived heavy precipitation events (PHPEs and SHPEs, respectively) in South China during summer (July-September) 1975-2009 in association with large-scale circulation and moisture processes at different timescales. Compared to SHPEs, PHPEs are characterized by long-lasting enhanced convection and cyclonic moisture circulation as well as strengthened moisture convergence over South China. Examination of environmental variables at different timescales suggests that intraseasonal and synoptic components play a deterministic role in regulating the overall changes in convection and moisture convergence, while the low-frequency background state plays only a marginal role. Further analysis of the moisture divergence terms also reveals that the overall changes in moisture divergence during PHPEs and SHPEs stem primarily from variations in the intraseasonal and synoptic wind fields rather than in the humidity fields. Overall, it is found that the location and strength of the intraseasonal oscillation (ISO) and the synoptic disturbances play a decisive role in controlling the severity and duration of rainfall events over South China. The synchronization and persistence of the enhanced convection and moisture circulation of the ISO and synoptic disturbances jointly contribute to prolonged heavy precipitation over South China, while the weakening and asynchrony of the associated convection and moisture circulation at different timescales result in rainfall events of weaker intensity and shorter duration.

  12. Within-Range Translocations and Their Consequences in European Larch

    PubMed Central

    Wagner, Stefanie; Liepelt, Sascha; Gerber, Sophie; Petit, Rémy J.

    2015-01-01

    In contrast to biological invasions, translocations of individuals within a species range are understudied, due to difficulties in systematically detecting them. This results in limited knowledge about the corresponding processes and uncertainties regarding the status of extant populations. European larch, a forest tree whose fragmented native distribution is restricted to the Alps and to other Central European mountains, has been massively planted for at least 300 years. Here we focus on the genetic characterization of translocations having taken place within its native range. Microsatellite variation at 13 nuclear loci and sequence data of two mitochondrial DNA fragments were analyzed on the basis of a comprehensive range-wide population sample. Two complementary methods (Geneclass and Structure) were used to infer translocation events based on nuclear data whereas mitochondrial data were used for validation of these inferences. Using Geneclass, we found translocation events in a majority of populations. Additional cases of translocation and many instances of admixture were identified using Structure, thanks to the clear-cut ancestral genetic structure detected in this species. In particular, a strong divide between Alpine and Central European populations, also apparent at mitochondrial markers, helped uncover details on translocation events and related processes. Translocations and associated admixture events were found to be heterogeneously distributed across the species range, with a particularly high frequency in Central Europe. Furthermore, translocations frequently involved multiple geographic sources, some of which were over-represented. Our study illustrates the importance of range-wide investigations for tracing translocations back to their origins and for revealing some of their consequences. It provides some first clues for developing suitable conservation and management strategies. PMID:26000791

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

    NASA Astrophysics Data System (ADS)

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

    2003-06-01

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

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

    SciTech Connect

    Mankuzhiyil, Nijil; Persic, Massimo; Tavecchio, Fabrizio

    2010-05-20

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

  15. High-frequency-peaked BL Lacertae Objects as Spectral Candles to Measure the Extragalactic Background Light in the Fermi and Air Cherenkov Telescopes Era

    NASA Astrophysics Data System (ADS)

    Mankuzhiyil, Nijil; Persic, Massimo; Tavecchio, Fabrizio

    2010-05-01

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

  16. Genomic Comparison of Translocating and Non-Translocating Escherichia coli

    PubMed Central

    Bachmann, Nathan L.; Katouli, Mohammad; Polkinghorne, Adam

    2015-01-01

    Translocation of E. coli across the gut epithelium can result in fatal sepsis in post-surgical patients. In vitro and in vivo experiments have identified the existence of a novel pathotype of translocating E. coli (TEC) that employs an unknown mechanism for translocating across epithelial cells to the mesenteric lymph nodes and the blood stream in both humans and animal models. In this study the genomes of four TEC strains isolated from the mesenteric lymph nodes of a fatal case of hospitalised patient (HMLN-1), blood of pigs after experimental shock (PC-1) and after non-lethal haemorrhage in rats (KIC-1 and KIC-2) were sequenced in order to identify the genes associated with their adhesion and/or translocation. To facilitate the comparison, the genomes of a non-adhering, non-translocating E. coli (46–4) and adhering but non-translocating E. coli (73–89) were also sequenced and compared. Whole genome comparison revealed that three (HMLN-1, PC-1 and KIC-2) of the four TEC strains carried a genomic island that encodes a Type 6 Secretion System that may contribute to adhesion of the bacteria to gut epithelial cells. The human TEC strain HMLN-1 also carried the invasion ibeA gene, which was absent in the animal TEC strains and is likely to be associated with host-specific translocation. Phylogenetic analysis revealed that the four TEC strains were distributed amongst three distinct E. coli phylogroups, which was supported by the presence of phylogroup specific fimbriae gene clusters. The genomic comparison has identified potential genes that can be targeted with knock-out experiments to further characterise the mechanisms of E. coli translocation. PMID:26317913

  17. Abdominal radiation causes bacterial translocation

    SciTech Connect

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

    1989-02-01

    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.

  18. Structural insights into ribosome translocation.

    PubMed

    Ling, Clarence; Ermolenko, Dmitri N

    2016-09-01

    During protein synthesis, tRNA and mRNA are translocated from the A to P to E sites of the ribosome thus enabling the ribosome to translate one codon of mRNA after the other. Ribosome translocation along mRNA is induced by the universally conserved ribosome GTPase, elongation factor G (EF-G) in bacteria and elongation factor 2 (EF-2) in eukaryotes. Recent structural and single-molecule studies revealed that tRNA and mRNA translocation within the ribosome is accompanied by cyclic forward and reverse rotations between the large and small ribosomal subunits parallel to the plane of the intersubunit interface. In addition, during ribosome translocation, the 'head' domain of small ribosomal subunit undergoes forward- and back-swiveling motions relative to the rest of the small ribosomal subunit around the axis that is orthogonal to the axis of intersubunit rotation. tRNA/mRNA translocation is also coupled to the docking of domain IV of EF-G into the A site of the small ribosomal subunit that converts the thermally driven motions of the ribosome and tRNA into the forward translocation of tRNA/mRNA inside the ribosome. Despite recent and enormous progress made in the understanding of the molecular mechanism of ribosome translocation, the sequence of structural rearrangements of the ribosome, EF-G and tRNA during translocation is still not fully established and awaits further investigation. WIREs RNA 2016, 7:620-636. doi: 10.1002/wrna.1354 For further resources related to this article, please visit the WIREs website. PMID:27117863

  19. Light-regulated translocation of signaling proteins in Drosophila photoreceptors

    PubMed Central

    Frechter, Shahar; Minke, Baruch

    2007-01-01

    Illumination of Drosophila photoreceptor cells induces multi-facet responses, which include generation of the photoreceptor potential, screening pigment migration and translocation of signaling proteins which is the focus of recent extensive research. Translocation of three signaling molecules is covered in this review: (1) Light-dependent translocation of arrestin from the cytosol to the signaling membrane, the rhabdomere, determines the lifetime of activated rhodopsin. Arrestin translocates in PIP3 and NINAC myosin III dependent manner, and specific mutations which disrupt the interaction between arrestin and PIP3 or NINAC also impair the light-dependant translocation of arrestin and the termination of the response to light. (2) Activation of Drosophila visual G protein, DGq, causes a massive and reversible, translocation of the α subunit from the signaling membrane to the cytosol, accompanied by activity-dependent architectural changes. Analysis of the translocation and the recovery kinetics of DGqα in wild-type flies and specific visual mutants indicated that DGqα is necessary but not sufficient for the architectural changes. (3) The TRP-like (TRPL) but not TRP channels translocate in a light-dependent manner between the rhabdomere and the cell body. As a physiological consequence of this light-dependent modulation of the TRP/TRPL ratio, the photoreceptors of dark-adapted flies operate at a wider dynamic range, which allows the photoreceptors enriched with TRPL to function better in darkness and dim background illumination. Altogether, signal-dependent movement of signaling proteins plays a major role in the maintenance and function of photoreceptor cells. PMID:16458490

  20. Detection and Identification of Translocations by Increased Specific Nondisjunction in ASPERGILLUS NIDULANS

    PubMed Central

    Upshall, Alan; Käfer, Etta

    1974-01-01

    A meiotic technique for visual detection of translocations has been applied to ten mitotically identified interchanges, and three new translocations were discovered using this method. Testcrosses between "standard" strains and potential translocation strains—e.g. strains with newly induced mutants or descendants from translocation crosses—are inspected for the frequency of abnormal-looking colonies. In all heterozygous translocation crosses "abnormals" are increased at least tenfold compared to the average control level of 0.15%. Most of these are disomics, and can be recognized by their characteristic phenotypes. Each translocation produces a few specific types, since nondisjunction is increased mainly in the linkage groups involved in the translocation (50–100-fold over control values). Therefore, translocations were not only detected but often tentatively assigned to linkage groups from the analysis of the disomic progeny in crosses. In addition, this technique allows reciprocal and nonreciprocal translocations to be distinguished, since only the latter produce one-third phenotypically abnormal duplication progeny. While results are clearcut in most cases, occasionally problems are encountered, e.g. when morphological mutants segregate in crosses, or when other genetic factors which increase or reduce the frequency of nondisjunction are present in certain strains. PMID:4594334

  1. Downside risk of wildlife translocation.

    PubMed

    Chipman, R; Slate, D; Rupprecht, C; Mendoza, M

    2008-01-01

    Translocation has been used successfully by wildlife professionals to enhance or reintroduce populations of rare or extirpated wildlife, provide hunting or wildlife viewing opportunities, farm wild game, and reduce local human-wildlife conflicts. However, accidental and intentional translocations may have multiple unintended negative consequences, including increased stress and mortality of relocated animals, negative impacts on resident animals at release sites, increased conflicts with human interests, and the spread of diseases. Many wildlife professionals now question the practice of translocation, particularly in light of the need to contain or eliminate high profile, economically important wildlife diseases and because using this technique may jeopardize international wildlife disease management initiatives to control rabies in raccoons, coyotes, and foxes in North America. Incidents have been documented where specific rabies variants (Texas gray fox, canine variant in coyotes, and raccoon) have been moved well beyond their current range as a result of translocation, including the emergence of raccoon rabies in the eastern United States. Here, we review and discuss the substantial challenges of curtailing translocation in the USA, focusing on movement of animals by the public, nuisance wildlife control operators, and wildlife rehabilitators. PMID:18634483

  2. The mechanics of ribosomal translocation.

    PubMed

    Achenbach, John; Nierhaus, Knud H

    2015-07-01

    The ribosome translates the sequence of codons of an mRNA into the corresponding sequence of amino acids as it moves along the mRNA with a codon-step width of about 10 Å. The movement of the million-dalton complex ribosome is triggered by the universal elongation factor G (EF2 in archaea and eukaryotes) and is termed translocation. Unraveling the molecular details of translocation is one of the most challenging tasks of current ribosome research. In the last two years, enormous progress has been obtained by highly-resolved X-ray and cryo-electron microscopic structures as well as by sophisticated biochemical approaches concerning the trigger and control of the movement of the tRNA2·mRNA complex inside the ribosome during translocation. This review inspects and surveys these achievements. PMID:25514765

  3. Protein translocation: what's the problem?

    PubMed

    Corey, Robin A; Allen, William J; Collinson, Ian

    2016-06-15

    We came together in Leeds to commemorate and celebrate the life and achievements of Prof. Stephen Baldwin. For many years we, together with Sheena Radford and Roman Tuma (colleagues also of the University of Leeds), have worked together on the problem of protein translocation through the essential and ubiquitous Sec system. Inspired and helped by Steve we may finally be making progress. My seminar described our latest hypothesis for the molecular mechanism of protein translocation, supported by results collected in Bristol and Leeds on the tractable bacterial secretion process-commonly known as the Sec system; work that will be published elsewhere. Below is a description of the alternative and contested models for protein translocation that we all have been contemplating for many years. This review will consider their pros and cons. PMID:27284038

  4. Protein translocation: what's the problem?

    PubMed Central

    Corey, Robin A.; Allen, William J.; Collinson, Ian

    2016-01-01

    We came together in Leeds to commemorate and celebrate the life and achievements of Prof. Stephen Baldwin. For many years we, together with Sheena Radford and Roman Tuma (colleagues also of the University of Leeds), have worked together on the problem of protein translocation through the essential and ubiquitous Sec system. Inspired and helped by Steve we may finally be making progress. My seminar described our latest hypothesis for the molecular mechanism of protein translocation, supported by results collected in Bristol and Leeds on the tractable bacterial secretion process–commonly known as the Sec system; work that will be published elsewhere. Below is a description of the alternative and contested models for protein translocation that we all have been contemplating for many years. This review will consider their pros and cons. PMID:27284038

  5. Chromosomal translocations deregulating c-myc are associated with normal immune responses.

    PubMed

    Roschke, V; Kopantzev, E; Dertzbaugh, M; Rudikoff, S

    1997-06-26

    Plasmacytomas induced in BALB/c mice by pristane consistently evidence chromosomal translocations involving the c-myc gene and one of the Ig loci. This observation has lead to the suggestion that c-myc deregulation is a critical event in the generation of such tumors. However, it is not clear whether c-myc translocation is related to pristane treatment or occurs in normal lymphocyte populations nor whether such translocations occur normally, and at similar frequencies, in strains genetically resistant to plasmacytoma development, such as DBA/2. In order to address these questions, a Long Distance PCR assay with single copy sensitivity was employed to assess the frequency of c-myc/IgA translocations in normal and immunized mice of both plasmacytoma resistant and susceptible lineages in the absence of pristane treatment. Our data demonstrate that spontaneous translocations occur in normal DBA/2 and BALB/c mice with no significant differences in frequency. A 3-5-fold increase in translocation frequency was observed in mice immunized with cholera toxin, a strong stimulator of IgA responses. We conclude that c-myc deregulation by chromosomal translocation is associated with normal physiological processes of B-cell differentiation and, as such, can not be the determining factor leading to malignancy. PMID:9223664

  6. Temperature dependence of DNA translocations through solid-state nanopores

    PubMed Central

    Verschueren, Daniel V.; Jonsson, Magnus P.; Dekker, Cees

    2015-01-01

    In order to gain a better physical understanding of DNA translocations through solid-state nanopores, we study the temperature dependence of λ-DNA translocations through 10 nm-in-diameter silicon-nitride nanopores, both experimentally and theoretically. The measured ionic conductance G, the DNA-induced ionic-conductance blockades ΔG and the event frequency Γ all increase with increasing temperature while the DNA translocation time τ decreases. G and ΔG are accurately described when bulk and surface conductances of the nanopore are considered and access resistance is incorporated appropriately. Viscous drag on the untranslocated part of the DNA coil is found to dominate the temperature dependence of the translocation times and the event rate is well described by a balance between diffusion and electrophoretic motion. The good fit between modeled and measured properties of DNA translocations through solid-state nanopores in this first comprehensive temperature study, suggest that our model captures the relevant physics of the process. PMID:25994084

  7. 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)

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

    2013-12-01

    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.

  8. Partners with reciprocal translocations: genetic counseling for the 'double translocation'.

    PubMed

    Cook, L; Hartsfield, J K; Vance, G H

    1998-05-01

    SV at age 2 years presented with multiple congenital anomalies including an absent left kidney, anal stenosis, vertebral abnormalities, partial sacral agenesis, microcephaly, dysmorphic facial features, growth deficiency, and developmental delay. She was found to have a complex chromosomal rearrangement derived from balanced translocations in each parent. PMID:9660061

  9. Bacterial translocation in experimental uremia.

    PubMed

    de Almeida Duarte, Joãn Bosco; de Aguilar-Nascimento, José Eduardo; Nascimento, Mariana; Nochi, Rubens Jardim

    2004-08-01

    The aim of this study was to investigate whether or not experimental uremia would induce bacterial translocation. Forty male Wistar rats were randomized into two groups: uremic (n = 20) and control (n = 20). Under anesthesia, the upper and lower left renal poles and the marginal lateral parenchyma were excised in uremic group. Seven days later, in a second operation, the liver, spleen and the mesenteric lymph nodes (MLN) were excised and cultured. Blood samples were sent for biochemical analysis (BUN, creatinine, sodium and potassium) and cultured. Specimens of the jejunum (1 cm below the Treitz angle) and ileum (1 cm above the ileocecal valve) were collected and sent for histological examination and scored for the degree of inflammation of the mucosa using a classification proposed by Chiu et al. in 1970. Uremic rats presented higher BUN, creatinine and potassium than controls. Bacterial translocation was more frequent in uremic than in control animals (8/20 (40%) vs. 1/20 (5%); p = 0.02). Translocation in uremic rats was observed mainly at the MLN (all eight cases). Both at the jejunum (uremic = 3 [0-5] vs. control = 2 [0-4]; p = 0.04) and the ileum (uremic - 2 [0-5] vs. control = 0 [0-3]; p = 0.01), inflammation score was higher in uremic rats than in controls. The intestinal mucosa barrier is impaired and bacterial translocation occurs in experimental uremia. PMID:15497213

  10. Suitability of amphibians and reptiles for translocation.

    PubMed

    Germano, Jennifer M; Bishop, Phillip J

    2009-02-01

    Translocations are important tools in the field of conservation. Despite increased use over the last few decades, the appropriateness of translocations for amphibians and reptiles has been debated widely over the past 20 years. To provide a comprehensive evaluation of the suitability of amphibians and reptiles for translocation, we reviewed the results of amphibian and reptile translocation projects published between 1991 and 2006. The success rate of amphibian and reptile translocations reported over this period was twice that reported in an earlier review in 1991. Success and failure rates were independent of the taxonomic class (Amphibia or Reptilia) released. Reptile translocations driven by human-wildlife conflict mitigation had a higher failure rate than those motivated by conservation, and more recent projects of reptile translocations had unknown outcomes. The outcomes of amphibian translocations were significantly related to the number of animals released, with projects releasing over 1000 individuals being most successful. The most common reported causes of translocation failure were homing and migration of introduced individuals out of release sites and poor habitat. The increased success of amphibian and reptile translocations reviewed in this study compared with the 1991 review is encouraging for future conservation projects. Nevertheless, more preparation, monitoring, reporting of results, and experimental testing of techniques and reintroduction questions need to occur to improve translocations of amphibians and reptiles as a whole. PMID:19143783

  11. Linkage map construction involving a reciprocal translocation.

    PubMed

    Farré, A; Benito, I Lacasa; Cistué, L; de Jong, J H; Romagosa, I; Jansen, J

    2011-03-01

    This paper is concerned with a novel statistical-genetic approach for the construction of linkage maps in populations obtained from reciprocal translocation heterozygotes of barley (Hordeum vulgare L.). Using standard linkage analysis, translocations usually lead to 'pseudo-linkage': the mixing up of markers from the chromosomes involved in the translocation into a single linkage group. Close to the translocation breakpoints recombination is severely suppressed and, as a consequence, ordering markers in those regions is not feasible. The novel strategy presented in this paper is based on (1) disentangling the "pseudo-linkage" using principal coordinate analysis, (2) separating individuals into translocated types and normal types and (3) separating markers into those close to and those more distant from the translocation breakpoints. The methods make use of a consensus map of the species involved. The final product consists of integrated linkage maps of the distal parts of the chromosomes involved in the translocation. PMID:21153624

  12. Successive Translocation of the Rings in a [3]Rotaxane.

    PubMed

    Jagesar, Dhiredj C; Wiering, Piet G; Kay, Euan R; Leigh, David A; Brouwer, Albert M

    2016-06-17

    A [2]rotaxane, a [3]rotaxane and the corresponding thread containing two succinamide (succ) binding stations and a central redox-active pyromellitimide (pmi) station were studied. Infrared spectroelectrochemical experiments revealed the translocation of the macrocycle between the succinamide station and the electrochemically reduced pmi station (radical anion and dianion). Remarkably, in the [3]rotaxane, the rings can be selectively translocated. One-electron reduction leads to the translocation of one of the two macrocycles from the succinamide to the pyromellitimide station, whereas activation of the shuttle through two-electron reduction results in the translocation of both macrocycles: the dianion, due to its higher electron density and hence greater hydrogen-bond accepting affinity, is hydrogen bonded to both macrocycles. Systems with such an on-command contraction are known as molecular muscles. The relative strengths of the binding between the macrocycle and the imide anions could be estimated from the hydrogen-bond-induced shifts in the C=O stretching frequencies of hydrogen-bond accepting amide groups of the macrocycle. PMID:26918870

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

    USGS Publications Warehouse

    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

    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.

  14. Problems with mitigation translocation of herpetofauna.

    PubMed

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

    2015-02-01

    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. PMID:25040040

  15. Adaptive background model

    NASA Astrophysics Data System (ADS)

    Lu, Xiaochun; Xiao, Yijun; Chai, Zhi; Wang, Bangping

    2007-11-01

    An adaptive background model aiming at outdoor vehicle detection is presented in this paper. This model is an improved model of PICA (pixel intensity classification algorithm), it classifies pixels into K-distributions by color similarity, and then a hypothesis that the background pixel color appears in image sequence with a high frequency is used to evaluate all the distributions to determine which presents the current background color. As experiments show, the model presented in this paper is a robust, adaptive and flexible model, which can deal with situations like camera motions, lighting changes and so on.

  16. Translocation (Y;12) in lipoma.

    PubMed

    Liang, Cher-Wei; Mariño-Enríquez, Adrian; Johannessen, Catherine; Hornick, Jason L; Dal Cin, Paola

    2011-01-01

    Lipomas are the most common benign mesenchymal neoplasm in adults, and have been extensively characterized at the cytogenetic level. Chromosomal aberrations have been observed in the majority of lipomas, two-thirds of which involve chromosomal region 12q14.3. To date, structural rearrangements have been reported affecting every chromosome except chromosome Y. Here we report a case of a lipoma that shows a novel apparently balanced translocation involving chromosomes Y and 12. Fluorescence in situ hybridization using a break-apart HMGA2 in-house probe set detected a single signal on the normal chromosome 12 but not on either the derivative chromosome Y or 12, indicating a cryptic loss of 12q14.3, where HMGA2 is mapped. Immunohistochemical studies, however, revealed overexpression of HMGA2 with nuclear expression in the majority of tumor cells, whereas MDM2 and CDK4 were negative. The overexpression of HMGA2 may be caused by a cryptic chromosomal aberration affecting either the cytogenetically unaltered HMGA2 allele or HMGA2 regulators elsewhere. The current case broadens our knowledge about the translocation partners of HMGA2 in lipomas and highlights the biological complexity in regulating HMGA2 expression. PMID:21356192

  17. Haloarchaeal Protein Translocation via the Twin Arginine Translocation Pathway

    SciTech Connect

    Pohlschroder Mechthild

    2009-02-03

    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.

  18. Tasmanian low frequency Galactic background surveys

    NASA Technical Reports Server (NTRS)

    Cane, H. V.

    1987-01-01

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

  19. Population demographics and genetic diversity in remnant and translocated populations of sea otters

    USGS Publications Warehouse

    Bodkin, J.L.; Ballachey, B.E.; Cronin, M.A.; Scribner, K.T.

    1999-01-01

    The effects of small population size on genetic diversity and subsequent population recovery are theoretically predicted, but few empirical data are available to describe those relations. We use data from four remnant and three translocated sea otter (Enhydra lutris) populations to examine relations among magnitude and duration of minimum population size, population growth rates, and genetic variation. Metochondrial (mt)DNA haplotype diversity was correlated with the number of years at minimum population size (r = -0.741, p = 0.038) and minimum population size (r = 0.709, p = 0.054). We found no relation between population growth and haplotype diversity, altough growth was significantly greater in translocated than in remnant populations. Haplotype diversity in populations established from two sources was higher than in a population established from a single source and was higher than in the respective source populations. Haplotype frequencies in translocated populations of founding sizes of 4 and 28 differed from expected, indicating genetic drift and differential reproduction between source populations, whereas haplotype frequencies in a translocated population with a founding size of 150 did not. Relations between population demographics and genetic characteristics suggest that genetic sampling of source and translocated populations can provide valuable inferences about translocations.

  20. DNA translocation through graphene nanopores.

    PubMed

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

    2010-08-11

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

  1. Phosphorus Compounds in Translocating Phloem

    PubMed Central

    Bieleski, R. L.

    1969-01-01

    Phosphate-32P was introduced into a turnip leaf, and 3 hr later, the vascular bundles were stripped from the petiole and their phosphate ester pattern was studied. The pattern did not alter along their length and was like that of other tissues. Pumpkin leaves were painted with phosphate-32P; and later, the petioles were cut, the sieve tube exudates were collected and their phosphate ester patterns were studied. Exudates collected after 10 min had a high proportion of their 32P present in Pi and nucleoside triphosphates, while exudates collected after long translocation times (4-22 hr) had a lower proportion in these, and a higher proportion in hexose monophosphates and UDP glucose. In general, the ester patterns were like those of other tissues. The results indicate that sieve tubes are metabolically active, and that Pi is the primary form in which phosphorus moves in the phloem. Images PMID:16657091

  2. Chromosomal Translocations in the Parasite Leishmania by a MRE11/RAD50-Independent Microhomology-Mediated End Joining Mechanism

    PubMed Central

    Laffitte, Marie-Claude N.; Leprohon, Philippe; Hainse, Maripier; Légaré, Danielle; Masson, Jean-Yves; Ouellette, Marc

    2016-01-01

    The parasite Leishmania often relies on gene rearrangements to survive stressful environments. However, safeguarding a minimum level of genome integrity is important for cell survival. We hypothesized that maintenance of genomic integrity in Leishmania would imply a leading role of the MRE11 and RAD50 proteins considering their role in DNA repair, chromosomal organization and protection of chromosomes ends in other organisms. Attempts to generate RAD50 null mutants in a wild-type background failed and we provide evidence that this gene is essential. Remarkably, inactivation of RAD50 was possible in a MRE11 null mutant that we had previously generated, providing good evidence that RAD50 may be dispensable in the absence of MRE11. Inactivation of the MRE11 and RAD50 genes led to a decreased frequency of homologous recombination and analysis of the null mutants by whole genome sequencing revealed several chromosomal translocations. Sequencing of the junction between translocated chromosomes highlighted microhomology sequences at the level of breakpoint regions. Sequencing data also showed a decreased coverage at subtelomeric locations in many chromosomes in the MRE11-/-RAD50-/- parasites. This study demonstrates an MRE11-independent microhomology-mediated end-joining mechanism and a prominent role for MRE11 and RAD50 in the maintenance of genomic integrity. Moreover, we suggest the possible involvement of RAD50 in subtelomeric regions stability. PMID:27314941

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

    PubMed Central

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

    2012-01-01

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

  4. Human Immunodeficiency Virus-related Microbial Translocation and Progression of Hepatitis C

    PubMed Central

    Balagopal, Ashwin; Philp, Frances H.; Astemborski, Jacquie; Block, Timothy M.; Mehta, Anand; Long, Ronald; Kirk, Gregory D.; Mehta, Shruti H.; Cox, Andrea L.; Thomas, David L.; Ray, Stuart C.

    2009-01-01

    Background & Aims HIV-1 infection has been associated with enhanced microbial translocation, and microbial translocation is a mechanism through which alcohol and some enteric conditions cause liver disease. We hypothesized that HIV promotes liver disease by enhancing microbial translocation. Methods We studied human cohorts in which hepatitis C virus (HCV) and HIV outcomes were carefully characterized. Results HIV-related CD4+ lymphocyte depletion was strongly associated with microbial translocation as indicated by elevated levels of circulating lipopolysaccharide (LPS), LPS binding protein, soluble CD14, fucose-binding lectin (AAL) reactive to IgG specific for the alpha galactose epitope, and suppressed levels of endotoxin-core antibodies (EndoCAb IgM) in HIV-infected subjects compared with the same persons before they had HIV infection and compared with HIV-uninfected subjects. The same measures of microbial translocation were strongly associated with HCV-related liver disease progression (cirrhosis), e.g. LPS, odds ratio 19.0 (p = 0.002), AAL, odds ratio 27.8 (p<0.0001); in addition, levels of LPS were elevated prior to recognition of cirrhosis. Conclusions Microbial translocation may be a fundamental mechanism through which HIV accelerates progression of chronic liver disease. PMID:18457674

  5. Intersubunit movement is required for ribosomal translocation

    PubMed Central

    Horan, Lucas H.; Noller, Harry F.

    2007-01-01

    Translocation of tRNA and mRNA during protein synthesis is believed to be coupled to structural changes in the ribosome. The “ratchet model,” based on cryo-EM reconstructions of ribosome complexes, invokes relative movement of the 30S and 50S ribosomal subunits in this process; however, evidence that directly demonstrates a requirement for intersubunit movement during translocation is lacking. To address this problem, we created an intersubunit disulfide cross-link to restrict potential movement. The cross-linked ribosomes were unable to carry out polypeptide synthesis; this inhibition was completely reversed upon reduction of the disulfide bridge. In vitro assays showed that the cross-linked ribosomes were specifically blocked in elongation factor G-dependent translocation. These findings show that intersubunit movement is required for ribosomal translocation, accounting for the universal two-subunit architecture of ribosomes. PMID:17360328

  6. What Drives the Translocation of Proteins?

    NASA Astrophysics Data System (ADS)

    Simon, Sanford M.; Peskin, Charles S.; Oster, George F.

    1992-05-01

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

  7. Mechanochemical aspects of axonemal dynein activity studied by in vitro microtubule translocation.

    PubMed

    Hamasaki, T; Holwill, M E; Barkalow, K; Satir, P

    1995-12-01

    We have determined the relationship between microtubule length and translocation velocity from recordings of bovine brain microtubules translocating over a Paramecium 22S dynein substratum in an in vitro assay chamber. For comparison with untreated samples, the 22S dynein has been subjected to detergent and/or to pretreatments that induce phosphorylation of an associated 29 kDa light chain. Control and treated dyneins have been used at the same densities in the translocation assays. In any given condition, translocation velocity (v) shows an initial increase with microtubule length (L) and then reaches a plateau. This situation may be represented by a hyperbola of the general form v = aL/(L+b), which is formally analogous to the Briggs-Haldane relationship, which we have used to interpret our data. The results indicate that the maximum translocation velocity Vo(= a) is increased by pretreatment, whereas the length constant KL(= b), which corresponds to Km, does not change with pretreatment, implying that the mechanochemical properties of the pretreated dyneins differ from those of control dyneins. The conclusion that KL is constant for defined in vitro assays rules out the possibility that the velocity changes seen are caused by changes in geometry in the translocation assays or by the numbers of dyneins or dynein heads needed to produce maximal translocational velocity. From our analysis, we determine that f, the fraction of cycle time during which the dynein is in the force-generating state, is small--roughly 0.01, comparable to the f determined previously for heavy meromyosin. The practical limits of these mechanochemical changes imply that the maximum possible ciliary beat frequency is about 120 Hz, and that in the physiological range of 5-60 Hz, beat frequency could be controlled by varying the numbers of phosphorylated outer arm dyneins along an axonemal microtubule. PMID:8599664

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

    PubMed Central

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

    2009-01-01

    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

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

    PubMed

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

    2009-06-01

    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

  10. Defining chromosomal translocation risks in cancer

    PubMed Central

    Hogenbirk, Marc A.; Heideman, Marinus R.; de Rink, Iris; Velds, Arno; Kerkhoven, Ron M.; Wessels, Lodewyk F. A.; Jacobs, Heinz

    2016-01-01

    Chromosomal translocations are a hallmark of cancer. Unraveling the molecular mechanism of these rare genetic events requires a clear distinction between correlative and causative risk-determinants, where technical and analytical issues can be excluded. To meet this goal, we performed in-depth analyses of publicly available genome-wide datasets. In contrast to several recent reports, we demonstrate that chromosomal translocation risk is causally unrelated to promoter stalling (Spt5), transcriptional activity, or off-targeting activity of the activation-induced cytidine deaminase. Rather, an open chromatin configuration, which is not promoter-specific, explained the elevated translocation risk of promoter regions. Furthermore, the fact that gene size directly correlates with the translocation risk in mice and human cancers further demonstrated the general irrelevance of promoter-specific activities. Interestingly, a subset of translocations observed in cancer patients likely initiates from double-strand breaks induced by an access-independent process. Together, these unexpected and novel insights are fundamental in understanding the origin of chromosome translocations and, consequently, cancer. PMID:27303044

  11. Ratcheting up protein translocation with anthrax toxin

    PubMed Central

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

    2012-01-01

    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

  12. Defining chromosomal translocation risks in cancer.

    PubMed

    Hogenbirk, Marc A; Heideman, Marinus R; de Rink, Iris; Velds, Arno; Kerkhoven, Ron M; Wessels, Lodewyk F A; Jacobs, Heinz

    2016-06-28

    Chromosomal translocations are a hallmark of cancer. Unraveling the molecular mechanism of these rare genetic events requires a clear distinction between correlative and causative risk-determinants, where technical and analytical issues can be excluded. To meet this goal, we performed in-depth analyses of publicly available genome-wide datasets. In contrast to several recent reports, we demonstrate that chromosomal translocation risk is causally unrelated to promoter stalling (Spt5), transcriptional activity, or off-targeting activity of the activation-induced cytidine deaminase. Rather, an open chromatin configuration, which is not promoter-specific, explained the elevated translocation risk of promoter regions. Furthermore, the fact that gene size directly correlates with the translocation risk in mice and human cancers further demonstrated the general irrelevance of promoter-specific activities. Interestingly, a subset of translocations observed in cancer patients likely initiates from double-strand breaks induced by an access-independent process. Together, these unexpected and novel insights are fundamental in understanding the origin of chromosome translocations and, consequently, cancer. PMID:27303044

  13. Driven Polymer Translocation into a Crosslinked Gel

    NASA Astrophysics Data System (ADS)

    Sean, David; Slater, Gary

    2015-03-01

    In a typical polymer translocation setup, a thin membrane is used to separate two chambers and a polyelectrolyte is driven by an electric field to translocate from one side of the membrane to the other via a small nanopore. However, the high translocation rate that results from the forces required to drive this process makes optical and/or electrical analysis of the translocating polymer challenging. Using coarse-grained Langevin Dynamics simulations we investigate how the translocation process can be slowed down by placing a crosslinked gel on the trans-side of the membrane. Since the driving electric field is localized in the neighborhood of the nanopore, electrophoretic migration is only achieved by a ``pushing'' action from the polymer segment residing in the nanopore. For the case of a flexible polymer we find that the polymer fills the gel pores via multiple ``herniation'' processes, whereas for a semi-flexible chain in a tight gel there are no hernias and the polymer follows a smooth curvilinear path. Moreover, for the case of a semi-flexible polymer the gel makes the translocation process more uniform by reducing the acceleration at the end of the process.

  14. Translocation of DNA across bacterial membranes.

    PubMed Central

    Dreiseikelmann, B

    1994-01-01

    DNA translocation across bacterial membranes occurs during the biological processes of infection by bacteriophages, conjugative DNA transfer of plasmids, T-DNA transfer, and genetic transformation. The mechanism of DNA translocation in these systems is not fully understood, but during the last few years extensive data about genes and gene products involved in the translocation processes have accumulated. One reason for the increasing interest in this topic is the discussion about horizontal gene transfer and transkingdom sex. Analyses of genes and gene products involved in DNA transfer suggest that DNA is transferred through a protein channel spanning the bacterial envelope. No common model exists for DNA translocation during phage infection. Perhaps various mechanisms are necessary as a result of the different morphologies of bacteriophages. The DNA translocation processes during conjugation, T-DNA transfer, and transformation are more consistent and may even be compared to the excretion of some proteins. On the basis of analogies and homologies between the proteins involved in DNA translocation and protein secretion, a common basic model for these processes is presented. PMID:7968916

  15. Molecular studies of free and translocation trisomy

    SciTech Connect

    Robinson, W.P.; Bernasconi, F.; Lefort, G.

    1994-09-01

    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.

  16. Microbiology of bacterial translocation in humans

    PubMed Central

    O'Boyle, C; MacFie, J; Mitchell, C; Johnstone, D; Sagar, P; Sedman, P

    1998-01-01

    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 bacteria and the development of postoperative septic complications. 
Methods—Mesenteric lymph nodes (MLN), serosal scrapings, and peripheral blood from 448 surgical patients undergoing laparotomy were analysed using standard microbiological techniques. 
Results—Bacterial translocation was identified in 69 patients (15.4%). The most common organism identified was Escherichia coli (54%). Both enteric bacteria, typical of indigenous intestinal flora, and non-enteric bacteria were isolated. Postoperative septic complications developed in 104 patients (23%). Enteric organisms were responsible in 74% of patients. Forty one per cent of patients who had evidence of bacterial translocation developed sepsis compared with 14% in whom no organisms were cultured (p<0.001). Septic morbidity was more frequent when a greater diversity of bacteria resided within the MLN, but this was not statistically significant. 
Conclusion—Bacterial translocation is associated with a significant increase in the development of postoperative sepsis in surgical patients. The organisms responsible for septic morbidity are similar in spectrum to those observed in the mesenteric lymph nodes. These data strongly support the gut origin hypothesis of sepsis in humans. 

 Keywords: bacterial translocation; mesenteric lymph nodes; serosal scrapings; enteric bacteria; postoperative sepsis PMID:9505882

  17. Translocation involving 1p and 17q is a recurrent genetic alteration of human neuroblastoma cells

    SciTech Connect

    Savelyeva, L.; Corvi, R.; Schwab, M. )

    1994-08-01

    Human neuroblastoma cells often are monosomic for the distal portion of 1p (1p36). The authors report that the deleted 1p material in cells of neuroblastoma lines is preferentially replaced by material from chromosome 17, resulting from an unbalanced 1;17 translocation. Chromosome 17 often acquires instability, followed by the integration of fragments into various marker chromosomes. As a consequence, 17q material can increase over 17p material. The nonrandom frequency of 1;17 translocations appears to indicate an as-yet-undefined contribution to neuroblastoma development. 35 refs., 4 figs., 1 tab.

  18. Theory of polymer translocation through a flickering nanopore under an alternating driving force

    NASA Astrophysics Data System (ADS)

    Sarabadani, Jalal; Ikonen, Timo; Ala-Nissila, Tapio

    2015-08-01

    We develop a theory for polymer translocation driven by a time-dependent force through an oscillating nanopore. To this end, we extend the iso-flux tension propagation theory [Sarabadani et al., J. Chem. Phys. 141, 214907 (2014)] for such a setup. We assume that the external driving force in the pore has a component oscillating in time, and the flickering pore is similarly described by an oscillating term in the pore friction. In addition to numerically solving the model, we derive analytical approximations that are in good agreement with the numerical simulations. Our results show that by controlling either the force or pore oscillations, the translocation process can be either sped up or slowed down depending on the frequency of the oscillations and the characteristic time scale of the process. We also show that while in the low and high frequency limits, the translocation time τ follows the established scaling relation with respect to chain length N0, in the intermediate frequency regime small periodic, fluctuations can have drastic effects on the dynamical scaling. The results can be easily generalized for non-periodic oscillations and elucidate the role of time dependent forces and pore oscillations in driven polymer translocation.

  19. Stochastic resonance during a polymer translocation process

    NASA Astrophysics Data System (ADS)

    Mondal, Debasish; Muthukumar, Murugappan

    We study the translocation of a flexible polymer in a confined geometry subjected to a time-periodic external drive to explore stochastic resonance. We describe the equilibrium translocation process in terms of a Fokker-Planck description and use a discrete two-state model to describe the effect of the external driving force on the translocation dynamics. We observe that no stochastic resonance is possible if the associated free-energy barrier is purely entropic in nature. The polymer chain experiences a stochastic resonance effect only in presence of an energy threshold in terms of polymer-pore interaction. Once stochastic resonance is feasible, the chain entropy controls the optimal synchronization conditions significantly.

  20. DNA nanopore translocation in glutamate solutions

    NASA Astrophysics Data System (ADS)

    Plesa, C.; van Loo, N.; Dekker, C.

    2015-08-01

    Nanopore experiments have traditionally been carried out with chloride-based solutions. Here we introduce silver/silver-glutamate-based electrochemistry as an alternative, and study the viscosity, conductivity, and nanopore translocation characteristics of potassium-, sodium-, and lithium-glutamate solutions. We show that it has a linear response at typical voltages and can be used to detect DNA translocations through a nanopore. The glutamate anion also acts as a redox-capable thickening agent, with high-viscosity solutions capable of slowing down the DNA translocation process by up to 11 times, with a corresponding 7 time reduction in signal. These results demonstrate that glutamate can replace chloride as the primary anion in nanopore resistive pulse sensing.

  1. [Identification of the 1RS-7DS.7DL wheat-rye small segment translocation lines].

    PubMed

    Jun, Li; Xinguo, Zhu; Hongshen, Wan; Qin, Wang; Zongxiang, Tang; Shulan, Fu; Zujun, Yang; Manyu, Yang; Wuyun, Yang

    2015-06-01

    Rye (Secale cereale L., RR) is a valuable genetic resource for the improvement of common wheat (Triticum aestivum L., AABBDD). Transferring alien rye genes into wheat by distant hybridization and automatic chromosome doubling is an important and efficient method to boost agronomic traits, disease resistance and widening the gene pool in wheat. In this study, an octoploid triticale CD-13 (AABBDDRR) was obtained via automatic chromosome doubling by crossing landrace Penganbaimaizi (T. aestivum L., AABBDD) and rye "Qinling rye" (S. cereale cv. Qinling, RR). GISH and FISH analyses indicated that CD-13 contained a 1RS-7DS.7DL wheat-rye small segment translocation chromosome. In order to transfer the 1RS-7DS small segment translocation into hexaploid wheat, 58 lines of the F5 inbred population from the cross CD-13 x Chuanmai 42 were screened for rye chromosome segments by GISH and FISH analyses. The results showed that 13 lines contained the 1RS-7DS.7DL small segment translocation chromosome by reciprocal translocation between 1RS and 7DS. These translocation lines carrying 1RS small rye alien segment were tested for the translocation breakpoints and the presence of a storage protein locus Sec-1. The Sec-1 locus was absent in the line 811, a stable 1RS-7DS.7DL small segment translocation line. The translocation breakpoint of 1RS-7DS.7DL of this line was located in the interval of IB267-IAG95 around the telomere of 1RS chromosome. Thousand-kernel weight of the line 811 was much higher than the parent CD-13, but not significantly different from Chuanmai 42. This indicated that 1RS-7DS.7DL small segment translocation had no negative effect on thousand-kernel weight in the genetic background of Chuanmai 42. The line with 1RS-7DS.7DL translocation chromosomes can be used as a new genetic material for further studies of valuable genes and their genetic effect on 1RS small segment. PMID:26351056

  2. Analyzing disease risks associated with translocations.

    PubMed

    Sainsbury, Anthony W; Vaughan-Higgins, Rebecca J

    2012-06-01

    Translocations of species are expected to be used increasingly to counter the undesirable effects of anthropogenic changes to ecosystems, including loss of species. Methods to assess the risk of disease associated with translocations have been compiled in a comprehensive manual of disease-risk analysis for movement of domestic animals. We used this manual to devise a qualitative method for assessing the probability of the occurrence of disease in wild animals associated with translocations. We adapted the method such that we considered a parasite (any agent of infectious or noninfectious disease) a hazard if it or the host had crossed an ecological or geographical barrier and was novel to the host. We included in our analyses hazards present throughout the translocation pathway derived from the interactions between host immunity and the parasite, the effect of parasites on populations, the effect of noninfectious disease agents, and the effect of stressors on host-parasite interactions. We used the reintroduction of Eurasian Cranes (Grus grus) to England to demonstrate our method. Of the 24 hazards identified, 1 was classified as high risk (coccidia) and 5 were medium risk (highly pathogenic avian influenza virus, Mycobacterium avium, Aspergillus fumigatus, tracheal worms [Syngamus sp. and Cyathostoma sp.], and Tetrameres spp.). Seventeen other hazards were considered low or very low risk. In the absence of better information on the number, identity, distribution, and pathogenicity of parasites of wild animals, there is uncertainty in the risk of disease to translocated animals and recipient populations. Surveys of parasites in source and destination populations and detailed health monitoring after release will improve the information available for future analyses of disease risk. We believe our method can be adapted to assess the risks of disease in other translocated populations. PMID:22533691

  3. Founder event and its effect on genetic variation in translocated populations of noble crayfish (Astacus astacus).

    PubMed

    Bláha, Martin; Žurovcová, Martina; Kouba, Antonín; Policar, Tomáš; Kozák, Pavel

    2016-02-01

    Establishing translocated populations is a common process to preserve and maintain genetic diversity of threatened species. In 2001, three translocated populations of noble crayfish (Astacus astacus) were established in the Czech Republic, founded by either adult or juvenile individuals from three particular source populations. We assessed genetic diversity at seven microsatellite loci after one decade (assumed three generations) from establishment. Although the translocated populations exhibited a slight but non-significant reduction in genetic diversity (A R = 2.2-5.0; H O = 0.11-0.31), the most striking result was generally very low genetic diversity in source populations (A R = 3.0-5.3; H O = 0.15-0.38). Similarly, a high degree of inbreeding (F IS = 0.36-0.60) demonstrates the nature of source populations, already affected by isolation and small size. In spite of that, based on the results of this study, the establishment of new translocated noble crayfish populations was successful, since there is no significant decline in genetic variability and all populations are still viable. Although source populations did not exhibit high genetic diversity, their distinctiveness makes them possible to use for conservation purposes. Continued monitoring is necessary to track the long-term progress of the translocation program, including other parameters describing the state of the population, such as the occurrence and frequency of diseases or morphological changes. PMID:26077200

  4. Protein Translocation across the Rough Endoplasmic Reticulum

    PubMed Central

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

    2013-01-01

    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

  5. What drives the translocation of proteins?

    PubMed Central

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

    1992-01-01

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

  6. Detection of interchromosomal translocations within the Triticeae by RFLP analysis.

    PubMed

    King, I P; Purdie, K A; Liu, C J; Reader, S M; Pittaway, T S; Orford, S E; Miller, T E

    1994-10-01

    Twenty-three wheat/alien addition or substitution lines were screened using restriction fragment length polymorphisms for the presence or absence of 4/5 and 4/7 reciprocal translocations in the alien chromosomes. Such translocations have previously been identified in wheat and rye. Group 4 and group 5 Aegilops umbellulata, Triticum urartu, and Thinopyrum bessarabicum chromosomes were found to carry 4/5 translocations. Evidence for a 4/7 translocation was also found in Secale montanum. The presence of the 4/5 translocations in T. urartu indicates that the translocation predates the polyploidization of wheat. The implications of these results are discussed. PMID:18470131

  7. Molecular cytogenetic characterization of novel wheat-Thinopyrum bessarabicum recombinant lines carrying intercalary translocations.

    PubMed

    Patokar, Chetan; Sepsi, Adel; Schwarzacher, Trude; Kishii, Masahiro; Heslop-Harrison, J S

    2016-03-01

    Thinopyrum bessarabicum (2n = 2x = 14, JJ or E(b)E(b)) is a valuable source of genes for bread wheat (2n = 6x = 42) improvement because of its salinity tolerance and disease resistance. Development of wheat-Th. bessarabicum translocation lines by backcrossing the amphiploid in the absence of the Ph1 gene (allowing intergenomic recombination) can assist its utilization in wheat improvement. In this study, six novel wheat-Th. bessarabicum translocation lines involving different chromosome segments (T4BS.4BL-4JL, T6BS.6BL-6JL, T5AS.5AL-5JL, T5DL.5DS-5JS, T2BS.2BL-2JL, and the whole arm translocation T1JS.1AL) were identified and characterized using genomic in situ hybridization (GISH) and fluorescent in situ hybridization (FISH). No background translocations between wheat genomes were observed. The involvement of five of the seven chromosomes and small terminal segments of Th. bessarabicum chromosome arm were important, contributing to both reduced linkage drag of the derived lines by minimizing agronomically deleterious genes from the alien species and high stability including transmission of the alien segment. All three wheat genomes were involved in the translocations with the alien chromosome, and GISH showed the Th. bessarabicum genome was more closely related to the D genome in wheat. All the introgression lines were disomic, stable, and with good morphological characters. PMID:26238987

  8. Safety of probiotics: translocation and infection.

    PubMed

    Liong, Min-Tze

    2008-04-01

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

  9. Familial cryptic translocation in Angelman syndrome

    SciTech Connect

    Weyerts, L.K.; Wiley, J.E.; Loud, K.M.

    1994-09-01

    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.

  10. Stat1 Nuclear Translocation by Nucleolin upon Monocyte Differentiation

    PubMed Central

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

    2009-01-01

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

  11. Tailoring particle translocation via dielectrophoresis in pore channels.

    PubMed

    Tanaka, Shoji; Tsutsui, Makusu; Theodore, Hu; Yuhui, He; Arima, Akihide; Tsuji, Tetsuro; Doi, Kentaro; Kawano, Satoyuki; Taniguchi, Masateru; Kawai, Tomoji

    2016-01-01

    Understanding and controlling electrophoretic motions of nanoscopic objects in fluidic channels are a central challenge in developing nanopore technology for molecular analyses. Although progress has been made in slowing the translocation velocity to meet the requirement for electrical detections of analytes via picoampere current measurements, there exists no method useful for regulating particle flows in the transverse directions. Here, we report the use of dielectrophoresis to manipulate the single-particle passage through a solid-state pore. We created a trap field by applying AC voltage between electrodes embedded in a low-aspect-ratio micropore. We demonstrated a traffic control of particles to go through center or near side surface via the voltage frequency. We also found enhanced capture efficiency along with faster escaping speed of particles by virtue of the AC-mediated electroosmosis. This method is compatible with nanopore sensing and would be widely applied for reducing off-axis effects to achieve single-molecule identification. PMID:27527126

  12. Tailoring particle translocation via dielectrophoresis in pore channels

    PubMed Central

    Tanaka, Shoji; Tsutsui, Makusu; Theodore, Hu; Yuhui, He; Arima, Akihide; Tsuji, Tetsuro; Doi, Kentaro; Kawano, Satoyuki; Taniguchi, Masateru; Kawai, Tomoji

    2016-01-01

    Understanding and controlling electrophoretic motions of nanoscopic objects in fluidic channels are a central challenge in developing nanopore technology for molecular analyses. Although progress has been made in slowing the translocation velocity to meet the requirement for electrical detections of analytes via picoampere current measurements, there exists no method useful for regulating particle flows in the transverse directions. Here, we report the use of dielectrophoresis to manipulate the single-particle passage through a solid-state pore. We created a trap field by applying AC voltage between electrodes embedded in a low-aspect-ratio micropore. We demonstrated a traffic control of particles to go through center or near side surface via the voltage frequency. We also found enhanced capture efficiency along with faster escaping speed of particles by virtue of the AC-mediated electroosmosis. This method is compatible with nanopore sensing and would be widely applied for reducing off-axis effects to achieve single-molecule identification. PMID:27527126

  13. Post-release dispersal in animal translocations: social attraction and the "vacuum effect".

    PubMed

    Mihoub, Jean-Baptiste; Robert, Alexandre; Le Gouar, Pascaline; Sarrazin, François

    2011-01-01

    Animal translocations are human-induced colonizations that can represent opportunities to contribute to the knowledge on the behavioral and demographic processes involved in the establishment of animal populations. Habitat selection behaviors, such as social cueing, have strong implications on dispersal and affect the establishment success of translocations. Using modeling simulations with a two-population network model (a translocated population and a remnant population), we investigated the consequences of four habitat selection strategies on post-translocation establishment probabilities in short- and long-lived species. Two dispersal strategies using social cues (conspecific attraction and habitat copying) were compared to random and quality-based strategies. We measured the sensitivity of local extinctions to dispersal strategies, life cycles, release frequencies, remnant population and release group sizes, the proportion of breeders and the connectivity between populations. Our results indicate that social behaviors can compromise establishment as a result of post-release dispersal, particularly in long-lived species. This behavioral mechanism, the "vacuum effect", arises from increased emigration in populations that are small relative to neighboring populations, reducing their rate of population growth. The vacuum effect can drive small remnant populations to extinction when a translocated group is large. In addition, the magnitude of the vacuum effect varies non-linearly with connectivity. The vacuum effect represents a novel form of the behaviorally mediated Allee effect that can cause unexpected establishment failures or population extinctions in response to social cueing. Accounting for establishment probabilities as a conditional step to the persistence of populations would improve the accuracy of predicting the fates of translocated or natural (meta)populations. PMID:22194784

  14. Translocation strategies for multiple species depend on interspecific interaction type.

    PubMed

    Plein, Michaela; Bode, Michael; Moir, Melinda L; Vesk, Peter A

    2016-06-01

    Conservation translocations, anthropogenic movements of species to prevent their extinction, have increased substantially over the last few decades. Although multiple species are frequently moved to the same location, current translocation guidelines consider species in isolation. This practice ignores important interspecific interactions and thereby risks translocation failure. We model three different two-species systems to illustrate the inherent complexity of multispecies translocations and to assess the influence of different interaction types (consumer-resource, mutualism, and competition) on translocation strategies. We focus on how these different interaction types influence the optimal founder population sizes for successful translocations and the order in which the species are moved (simultaneous or sequential). Further, we assess the effect of interaction strength in simultaneous translocations and the time delay between translocations when moving two species sequentially. Our results show that translocation decisions need to reflect the type of interaction. While all translocations of interacting species require a minimum founder population size, which is demarked by an extinction boundary, consumer-resource translocations also have a maximum founder population limit. Above the minimum founder size, increasing the number of translocated individuals leads to a substantial increase in the extinction boundary of competitors and consumers, but not of mutualists. Competitive and consumer-resource systems benefit from sequential translocations, but the order of translocations does not change the outcomes for mutualistic interaction partners noticeably. Interspecific interactions are important processes that shape population dynamics and should therefore be incorporated into the quantitative planning of multispecies translocations. Our findings apply whenever interacting species are moved, for example, in reintroductions, conservation introductions, biological

  15. A new approach to polymer translocation

    NASA Astrophysics Data System (ADS)

    Dubbeldam, Johan; Rostiashvili, Vakhtang; Milchev, Andrey; Vilgis, Thomas

    2011-03-01

    Polymer translocation is ubiquitous in nature. It plays a role in phenomena like virus infections and in trafficking of proteins through pores in a cell membrane. Many theoretical models have been developed to explain scaling properties of simple polymer chains through tiny nanopores. This has not resolved the controversies in this field, however. In this paper we employ novel methods to shed light on the results that were obtained using the different models that are in use today. We use, for example fractional Brownian motion to explain the scaling of the variance in the translocation length with time and find good agreement between simulation results and theoretical predictions. An extension of the theory to nanopores with more complex geometries are discussed.

  16. Origin of translocation barriers for polyelectrolyte chains.

    PubMed

    Kumar, Rajeev; Muthukumar, M

    2009-11-21

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

  17. Pore formation and translocation of melittin.

    PubMed Central

    Matsuzaki, K; Yoneyama, S; Miyajima, K

    1997-01-01

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

  18. Translocation in the nonpolytrichaceous moss grimmia laevigata

    SciTech Connect

    Alpert, P. )

    1989-10-01

    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.

  19. A novel selection system for chromosome translocations in Saccharomyces cerevisiae.

    PubMed Central

    Tennyson, Rachel B; Ebran, Nathalie; Herrera, Anissa E; Lindsley, Janet E

    2002-01-01

    Chromosomal translocations are common genetic abnormalities found in both leukemias and solid tumors. While much has been learned about the effects of specific translocations on cell proliferation, much less is known about what causes these chromosome rearrangements. This article describes the development and use of a system that genetically selects for rare translocation events using the yeast Saccharomyces cerevisiae. A translocation YAC was created that contains the breakpoint cluster region from the human MLL gene, a gene frequently involved in translocations in leukemia patients, flanked by positive and negative selection markers. A translocation between the YAC and a yeast chromosome, whose breakpoint falls within the MLL DNA, physically separates the markers and forms the basis for the selection. When RAD52 is deleted, essentially all of the selected and screened cells contain simple translocations. The detectable translocation rates are the same in haploids and diploids, although the mechanisms involved and true translocation rates may be distinct. A unique double-strand break induced within the MLL sequences increases the number of detectable translocation events 100- to 1000-fold. This novel system provides a tractable assay for answering basic mechanistic questions about the development of chromosomal translocations. PMID:11973293

  20. Unforced polymer translocation compared to the forced case.

    PubMed

    Lehtola, V V; Linna, R P; Kaski, K

    2010-03-01

    We present results for unforced polymer translocation from simulations using Langevin dynamics in two dimensions (2D) to four dimensions and stochastic rotation dynamics supporting hydrodynamic modes in three dimensions (3D). We compare our results to forced translocation and a simplified model where the polymer escapes from an infinite pore. The simple model shows that the scaling behavior of unforced translocation is independent of the dimension of the side to which the polymer is translocating. We find that, unlike its forced counterpart, unforced translocation dynamics is insensitive to pore design. Hydrodynamics is seen to markedly speed up the unforced translocation process but not to affect the scaling relations. Average mean-squared displacement shows scaling with average transition time in unforced but not in forced translocation. The waiting-time distribution in unforced translocation follows closely Poissonian distribution. Our measured transfer probabilities align well with those obtained from an equilibrium theory in 3D, but somewhat worse in 2D, where a polymer's relaxation toward equilibrium with respect to its translocation time is slower. Consequently, in stark contrast to forced translocation, unforced translocation is seen to remain close to equilibrium and shows clear universality. PMID:20365761

  1. Translocation and encapsulation of siRNA inside carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Mogurampelly, Santosh; Maiti, Prabal K.

    2013-01-01

    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 τ 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.

  2. Stepwise nucleosome translocation by RSC remodeling complexes

    PubMed Central

    Harada, Bryan T; Hwang, William L; Deindl, Sebastian; Chatterjee, Nilanjana; Bartholomew, Blaine; Zhuang, Xiaowei

    2016-01-01

    The SWI/SNF-family remodelers regulate chromatin structure by coupling the free energy from ATP hydrolysis to the repositioning and restructuring of nucleosomes, but how the ATPase activity of these enzymes drives the motion of DNA across the nucleosome remains unclear. Here, we used single-molecule FRET to monitor the remodeling of mononucleosomes by the yeast SWI/SNF remodeler, RSC. We observed that RSC primarily translocates DNA around the nucleosome without substantial displacement of the H2A-H2B dimer. At the sites where DNA enters and exits the nucleosome, the DNA moves largely along or near its canonical wrapping path. The translocation of DNA occurs in a stepwise manner, and at both sites where DNA enters and exits the nucleosome, the step size distributions exhibit a peak at approximately 1–2 bp. These results suggest that the movement of DNA across the nucleosome is likely coupled directly to DNA translocation by the ATPase at its binding site inside the nucleosome. DOI: http://dx.doi.org/10.7554/eLife.10051.001 PMID:26895087

  3. Stepwise translocation of nucleic acid motors

    PubMed Central

    Myong, Sua; Ha, Taekjip

    2010-01-01

    Summary Recent single molecule studies have made a significant contribution to the understanding of the molecular mechanism involved in the movement of motor proteins which process DNA and RNA. Measurement of stepsize in two disparate motors, NS3 helicase and ribosome both revealed three basepair steps which consist of three hidden substeps. Combined with previous structural studies, NS3 is likely taking a single nucleotide step of translocation coupled to one ATP binding event and this mode may be conserved in multitude of helicases. Such a stepwise translocation movement appears to occur through main contacts with the phosphate backbone. Double stranded RNA and DNA motor, RIG-I and Φ29 respectively showed translocation on a duplex while tracking exclusively a single stranded RNA/DNA in a directional manner, 5′ to 3′ in both cases. Spontaneous dynamics displayed by ribosome ratcheting and SSB (single stranded DNA binding protein) diffusing on DNA were rectified by interacting cofactors and proteins, EF-G and RecA respectively. PMID:20061135

  4. Stepwise nucleosome translocation by RSC remodeling complexes.

    PubMed

    Harada, Bryan T; Hwang, William L; Deindl, Sebastian; Chatterjee, Nilanjana; Bartholomew, Blaine; Zhuang, Xiaowei

    2016-01-01

    The SWI/SNF-family remodelers regulate chromatin structure by coupling the free energy from ATP hydrolysis to the repositioning and restructuring of nucleosomes, but how the ATPase activity of these enzymes drives the motion of DNA across the nucleosome remains unclear. Here, we used single-molecule FRET to monitor the remodeling of mononucleosomes by the yeast SWI/SNF remodeler, RSC. We observed that RSC primarily translocates DNA around the nucleosome without substantial displacement of the H2A-H2B dimer. At the sites where DNA enters and exits the nucleosome, the DNA moves largely along or near its canonical wrapping path. The translocation of DNA occurs in a stepwise manner, and at both sites where DNA enters and exits the nucleosome, the step size distributions exhibit a peak at approximately 1-2 bp. These results suggest that the movement of DNA across the nucleosome is likely coupled directly to DNA translocation by the ATPase at its binding site inside the nucleosome. PMID:26895087

  5. Kinetics of C-14 Translocation in Soybean

    PubMed Central

    Fisher, Donald B.

    1970-01-01

    The kinetics of 14C-assimilates in the soybean leaf were studied in pulse labeling and steady state labeling experiments. 14C-Sucrose apparently served as the ultimate source, at least, of translocated 14C-sucrose. However, since the specific activity of leaf sucrose reached a maximum within 5 minutes after pulse labeling, whereas that of exported sucrose did not reach a maximum until at least 20 minutes, it appeared that there were two sucrose compartments in the leaf. A possible physical basis for the two compartments may be the mesophyll (a photosynthetic compartment) and a specialized “paraveinal mesophyll” (a nonphotosynthetic compartment), through which photosynthate must pass on its way to the veins. The 14C kinetics of sterol glucoside, and probably esterified sterol glucoside, were similar to those for 14C-sucrose export. Sterol glucoside was labeled only in its glucose moiety and was the only stem lipid which became strongly labeled during 14C-sucrose translocation. These sterol derivatives may act as membrane carriers of sucrose between the translocation stream and surrounding cells. The kinetics of 14C-sucrose and its movement to the veins are discussed with reference to compartmentation within the leaf and metabolic exchange with other compounds, particularly with starch. Although a simple compartmental model gave a fairly accurate description of 14C-sucrose kinetics, an entirely accurate model could not be provided, primarily because of loss of 14C from sucrose, at an unknown rate, to starch. PMID:16657287

  6. Bolaamphiphiles Promote Phospholipid Translocation Across Vesicle Membranes

    PubMed Central

    Forbes, Christopher C.; DiVittorio, Kristy M.; Smith, Bradley D.

    2008-01-01

    A series of membrane-spanning bolaamphiphiles (molecules with two hydrophilic end-groups connected by a hydrophobic linker) were prepared by a modular synthetic method and evaluated for their abilities to affect the dynamics of a surrounding bilayer membrane. The goal was to determine if the bolaamphiphiles promote the translocation of phospholipids across vesicle membranes. The bolaamphiphiles were incorporated at low levels (up to 5 mol%) in vesicles composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC). Inward translocation assays were performed using fluorescent, NBD-labeled phospholipid probes with phosphocholine (PC) or phosphoglycerol (PG) head-groups. The membrane-spanning bolaamphiphiles promote the translocation of both phospholipid probes in the order PG > PC, while shorter bolaamphiphiles (structures that must adopt a U-shape and keep both end-groups in the same leaflet of the membrane), and regular amphiphiles with one hydrophilic end-group, are inactive. These results are an exception to the rule-of-thumb that membrane-spanning bolaamphiphiles are inherently membrane stabilizing molecules that inhibit all types of membrane transport. PMID:16834395

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

    PubMed Central

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

    2014-01-01

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

  8. Financial Costs of Large Carnivore Translocations – Accounting for Conservation

    PubMed Central

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

    2014-01-01

    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

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

    PubMed

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

    2014-01-01

    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

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

    PubMed Central

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

    2007-01-01

    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

  11. Breakpoint Mapping and Array CGH in Translocations: Comparison of a Phenotypically Normal and an Abnormal Cohort

    PubMed Central

    Baptista, Julia; Mercer, Catherine; Prigmore, Elena; Gribble, Susan M.; Carter, Nigel P.; Maloney, Viv; Thomas, N. Simon; Jacobs, Patricia A.; Crolla, John A.

    2008-01-01

    We report the analyses of breakpoints in 31 phenotypically normal and 14 abnormal carriers of balanced translocations. Our study assesses the differences between balanced translocations in normal carriers and those in abnormal carriers, focusing on the presence of genomic imbalances at the breakpoints or elsewhere in the genome, presence of cryptic chromosome rearrangements, and gene disruption. Our hypothesis is that all four features will be associated with phenotypic abnormalities and absent or much less frequent in a normal population. In the normal cohort, we identified neither genomic imbalances at the breakpoints or elsewhere in the genome nor cryptic chromosome rearrangements. In contrast, we identified candidate disease-causing imbalances in 4/14 abnormal patients. These were three breakpoint associated deletions and three deletions unrelated to the breakpoints. All six de novo deletions originated on the paternally inherited chromosome. Additional complexity was also present in one of these cases. Gene disruption by the breakpoints was present in 16/31 phenotypically normal individuals and in 5/14 phenotypically abnormal patients. Our results show that translocations in phenotypically abnormal patients are molecularly distinct from those in normal individuals: the former are more likely to be associated with genomic imbalances at the breakpoints or elsewhere and with chromosomal complexity, whereas the frequency of gene disruption is similar in both normal and abnormal translocation carriers. PMID:18371933

  12. FISH analysis with locus-specific probes in sperm from two translocation carrier men.

    PubMed

    Durak, B; Ozön, Y H; Ozdemir, M; Artan, S; Basaran, N; Basaran, S; Ozkinay, C

    1999-08-01

    Meiotic segregation of normal and derivative chromosomes was analysed in sperm samples from two balanced reciprocal translocation carrier men by use of dual-colour fluorescence in situ hybridisation (FISH) technique. The translocations were t(4;8)(p15;p12) and t(15;22)(q(23:q13.2), and the digoxigenin-labelled FISH probes were specific to either the translocated or centric segments of the chromosomes involved in the translocations. A total of 1000 spermatozoa for each probe were analysed and the modes of segregation were described on the basis of signals in each sperm cell. The mean frequency of alternate and/or adjacent-1 (adj-1) segregation types was 69.47%, whereas they were 30.51 and 78.70% for the adjacent-2 (adj-2) and alternate/adj-2 segregation types, respectively. This study illustrated that FISH is a valuable technique for analysing the meiotic segregation products of the heterozygotes in respect to aneuploidy risk. PMID:10517249

  13. Targeted Chromosomal Translocations and Essential Gene Knockout Using CRISPR/Cas9 Technology in Caenorhabditis elegans.

    PubMed

    Chen, Xiangyang; Li, Mu; Feng, Xuezhu; Guang, Shouhong

    2015-12-01

    Many genes play essential roles in development and fertility; their disruption leads to growth arrest or sterility. Genetic balancers have been widely used to study essential genes in many organisms. However, it is technically challenging and laborious to generate and maintain the loss-of-function mutations of essential genes. The CRISPR/Cas9 technology has been successfully applied for gene editing and chromosome engineering. Here, we have developed a method to induce chromosomal translocations and produce genetic balancers using the CRISPR/Cas9 technology and have applied this approach to edit essential genes in Caenorhabditis elegans. The co-injection of dual small guide RNA targeting genes on different chromosomes resulted in reciprocal translocation between nonhomologous chromosomes. These animals with chromosomal translocations were subsequently crossed with animals that contain normal sets of chromosomes. The F1 progeny were subjected to a second round of Cas9-mediated gene editing. Through this method, we successfully produced nematode strains with specified chromosomal translocations and generated a number of loss-of-function alleles of two essential genes (csr-1 and mes-6). Therefore, our method provides an easy and efficient approach to generate and maintain loss-of-function alleles of essential genes with detailed genetic background information. PMID:26482793

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

    PubMed Central

    2010-01-01

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

  15. Genomic Heterogeneity of Translocation Renal Cell Carcinoma

    PubMed Central

    Couturier, Jérôme; Molinié, Vincent; Escudier, Bernard; Camparo, Philippe; Su, Xiaoping; Yao, Hui; Tamboli, Pheroze; Lopez-Terrada, Dolores; Picken, Maria; Garcia, Marileila; Multani, Asha S.; Pathak, Sen; Wood, Christopher G.; Tannir, Nizar M.

    2013-01-01

    Purpose Translocation renal cell carcinoma (tRCC) is a rare subtype of kidney cancer involving the TFEB/TFE3 genes. We aimed to investigate the genomic and epigenetic features of this entity. Experimental design Cytogenomic analysis was performed with 250K single-nucleotide polymorphism microarrays on 16 tumor specimens and 4 cell lines. LINE-1 methylation, a surrogate marker of DNA methylation, was performed on 27 cases using pyrosequencing. Results tRCC showed cytogenomic heterogeneity, with 31.2% and 18.7% of cases presenting similarities with clear-cell and papillary RCC profiles, respectively. The most common alteration was a 17q gain in 7 tumors (44%), followed by a 9p loss in 6 cases (37%). Less frequent were losses of 3p and 17p in 5 cases (31%) each. Patients with 17q gain were older (P = 0.0006), displayed more genetic alterations (P < 0.003) and had a worse outcome (P = 0.002) than patients without it. Analysis comparing gene-expression profiling of a subset of tumors bearing 17q gain and those without suggest large scale dosage effects and TP53 haploinsufficiency without any somatic TP53 mutation identified. Cell-line based cytogenetic studies revealed that 17q gain can be related to isochromosome 17 and/or to multiple translocations occurring around 17q breakpoints. Finally, LINE-1 methylation was lower in tRCC tumors from adults compared to tumors from young patients (71.1% vs. 76.7%, P = 0.02). Conclusions Our results reveal genomic heterogeneity of tRCC with similarities to other renal tumor subtypes and raise important questions about the role of TFEB/TFE3 translocations and other chromosomal imbalances in tRCC biology. PMID:23817689

  16. Microbial Translocation Across the GI Tract*

    PubMed Central

    Brenchley, Jason M.; Douek, Daniel C.

    2012-01-01

    The lumen of the gastrointestinal (GI) tract is home to an enormous quantity of different bacterial species, our microbiota, that thrive in an often symbiotic relationship with the host. Given that the healthy host must regulate contact between the microbiota and its immune system to avoid overwhelming systemic immune activation, humans have evolved several mechanisms to attenuate systemic microbial translocation (MT) and its consequences. However, several diseases are associated with the failure of one or more of these mechanisms, with consequent immune activation and deleterious effects on health. Here, we discuss the mechanisms underlying MT, diseases associated with MT, and therapeutic interventions that aim to decrease it. PMID:22224779

  17. Genomic Hallmarks of Genes Involved in Chromosomal Translocations in Hematological Cancer

    PubMed Central

    Shugay, Mikhail; Ortiz de Mendíbil, Iñigo; Vizmanos, José L.; Novo, Francisco J.

    2012-01-01

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

  18. Geographic Translocation of Bats: Known and Potential Problems

    PubMed Central

    2003-01-01

    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

  19. The Type III Secretion Translocation Pore Senses Host Cell Contact

    PubMed Central

    Armentrout, Erin I.; Rietsch, Arne

    2016-01-01

    Type III secretion systems (T3SS) are nano-syringes used by a wide range of Gram-negative pathogens to promote infection by directly injecting effector proteins into targeted host cells. Translocation of effectors is triggered by host-cell contact and requires assembly of a pore in the host-cell plasma membrane, which consists of two translocator proteins. Our understanding of the translocation pore, how it is assembled in the host cell membrane and its precise role in effector translocation, is extremely limited. Here we use a genetic technique to identify protein-protein contacts between pore-forming translocator proteins, as well as the T3SS needle-tip, that are critical for translocon function. The data help establish the orientation of the translocator proteins in the host cell membrane. Analysis of translocon function in mutants that break these contacts demonstrates that an interaction between the pore-forming translocator PopD and the needle-tip is required for sensing host cell contact. Moreover, tethering PopD at a dimer interface also specifically prevents host-cell sensing, arguing that the translocation pore is actively involved in detecting host cell contact. The work presented here therefore establishes a signal transduction pathway for sensing host cell contact that is initiated by a conformational change in the translocation pore, and is subsequently transmitted to the base of the apparatus via a specific contact between the pore and the T3SS needle-tip. PMID:27022930

  20. Chaperone-assisted translocation of flexible polymers in three dimensions

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

    Polymer translocation through a nanometer-scale pore assisted by chaperones binding to the polymer is a process encountered in vivo for proteins. Studying the relevant models by computer simulations is computationally demanding. Accordingly, previous studies are either for stiff polymers in three dimensions or flexible polymers in two dimensions. Here, we study chaperone-assisted translocation of flexible polymers in three dimensions using Langevin dynamics. We show that differences in binding mechanisms, more specifically, whether a chaperone can bind to a single site or multiple sites on the polymer, lead to substantial differences in translocation dynamics in three dimensions. We show that the single-binding mode leads to dynamics that is very much like that in the constant-force driven translocation and accordingly mainly determined by tension propagation on the cis side. We obtain β ≈1.26 for the exponent for the scaling of the translocation time with polymer length. This fairly low value can be explained by the additional friction due to binding particles. The multiple-site binding leads to translocation the dynamics of which is mainly determined by the trans side. For this process we obtain β ≈1.36 . This value can be explained by our derivation of β =4 /3 for constant-bias translocation, where translocated polymer segments form a globule on the trans side. Our results pave the way for understanding and utilizing chaperone-assisted translocation where variations in microscopic details lead to rich variations in the emerging dynamics.

  1. The protein translocation machinery of the endoplasmic reticulum.

    PubMed

    Walter, P; Gilmore, R; Müller, M; Blobel, G

    1982-12-24

    The rough endoplasmic reticulum (r.e.r.) has been postulated to possess a single translation-coupled translocation system (in multiple copies) that effects signal sequence-mediated translocation of all secretory and lysosomal proteins and integration of all integral membrane proteins whose port of entry is the rough endoplasmic reticulum (G. Blobel 1980 Proc. natn. Acad. Sci. U.S.A. 77, 1496-1500). Two proteins have been isolated that are components of the r.e.r. translocation system. Their properties and function in protein translocation across and integration into membranes are discussed. PMID:6131460

  2. Multistep protein unfolding during nanopore translocation

    NASA Astrophysics Data System (ADS)

    Rodriguez-Larrea, David; Bayley, Hagan

    2013-04-01

    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.

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

    SciTech Connect

    Lucas, J.N.; Straume, T.

    1995-10-01

    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.

  4. Ratchet rectification effect on the translocation of a flexible polyelectrolyte chain.

    PubMed

    Mondal, Debasish; Muthukumar, M

    2016-08-28

    We report a three dimensional Langevin dynamics simulation of a uniformly charged flexible polyelectrolyte chain, translocating through an asymmetric narrow channel with periodically varying cross sections under the influence of a periodic external electric field. When reflection symmetry of the channel is broken, a rectification effect is observed with a favored direction for the chain translocation. For a given volume of the channel unit and polymer length, the rectification occurs below a threshold frequency of the external periodic driving force. We have also observed that the extent of the rectification varies non-monotonically with increasing molecular weight and the strength of geometric asymmetry of the channel. Observed non-monotonicity of the rectification performance has been interpreted in terms of a competition between two effects arising from the channel asymmetry and change in conformational entropy. An analytical model is presented with predictions consistent with the simulation results. PMID:27586945

  5. Association between simple sequence repeat-rich chromosome regions and intergenomic translocation breakpoints in natural populations of allopolyploid wild wheats

    PubMed Central

    Molnár, István; Cifuentes, Marta; Schneider, Annamária; Benavente, Elena; Molnár-Láng, Márta

    2011-01-01

    Background and Aims Repetitive DNA sequences are thought to be involved in the formation of chromosomal rearrangements. The aim of this study was to analyse the distribution of microsatellite clusters in Aegilops biuncialis and Aegilops geniculata, and its relationship with the intergenomic translocations in these allotetraploid species, wild genetic resources for wheat improvement. Methods The chromosomal localization of (ACG)n and (GAA)n microsatellite sequences in Ae. biuncialis and Ae. geniculata and in their diploid progenitors Aegilops comosa and Aegilops umbellulata was investigated by sequential in situ hybridization with simple sequence repeat (SSR) probes and repeated DNA probes (pSc119·2, Afa family and pTa71) and by dual-colour genomic in situ hybridization (GISH). Thirty-two Ae. biuncialis and 19 Ae. geniculata accessions were screened by GISH for intergenomic translocations, which were further characterized by fluorescence in situ hybridization and GISH. Key Results Single pericentromeric (ACG)n signals were localized on most U and on some M genome chromosomes, whereas strong pericentromeric and several intercalary and telomeric (GAA)n sites were observed on the Aegilops chromosomes. Three Ae. biuncialis accessions carried 7Ub–7Mb reciprocal translocations and one had a 7Ub–1Mb rearrangement, while two Ae. geniculata accessions carried 7Ug–1Mg or 5Ug–5Mg translocations. Conspicuous (ACG)n and/or (GAA)n clusters were located near the translocation breakpoints in eight of the ten translocated chromosomes analysed, SSR bands and breakpoints being statistically located at the same chromosomal site in six of them. Conclusions Intergenomic translocation breakpoints are frequently mapped to SSR-rich chromosomal regions in the allopolyploid species examined, suggesting that microsatellite repeated DNA sequences might facilitate the formation of those chromosomal rearrangements. The (ACG)n and (GAA)n SSR motifs serve as additional chromosome markers

  6. Functional characterization of the trans-membrane domain interactions of the Sec61 protein translocation complex beta-subunit

    PubMed Central

    Zhao, Xueqiang; Jäntti, Jussi

    2009-01-01

    Background In eukaryotic cells co- and post-translational protein translocation is mediated by the trimeric Sec61 complex. Currently, the role of the Sec61 complex β-subunit in protein translocation is poorly understood. We have shown previously that in Saccharomyces cerevisiae the trans-membrane domain alone is sufficient for the function of the β-subunit Sbh1p in co-translational protein translocation. In addition, Sbh1p co-purifies not only with the protein translocation channel subunits Sec61p and Sss1p, but also with the reticulon family protein Rtn1p. Results We used random mutagenesis to generate novel Sbh1p mutants in order to functionally map the Sbh1p trans-membrane domain. These mutants were analyzed for their interactions with Sec61p and how they support co-translational protein translocation. The distribution of mutations identifies one side of the Sbh1p trans-membrane domain α-helix that is involved in interactions with Sec61p and that is important for Sbh1p function in protein translocation. At the same time, these mutations do not affect Sbh1p interaction with Rtn1p. Furthermore we show that Sbh1p is found in protein complexes containing not only Rtn1p, but also the two other reticulon-like proteins Rtn2p and Yop1p. Conclusion Our results identify functionally important amino acids in the Sbh1p trans-membrane domain. In addition, our results provide additional support for the involvement of Sec61β in processes unlinked to protein translocation. PMID:19857245

  7. DAX-1 Expression in Pediatric Rhabdomyosarcomas: Another Immunohistochemical Marker Useful in the Diagnosis of Translocation Positive Alveolar Rhabdomyosarcoma

    PubMed Central

    Virgone, Calogero; Lalli, Enzo; Bisogno, Gianni; Lazzari, Elena; Roma, Josep; Zin, Angelica; Poli, Elena; Cecchetto, Giovanni; Dall’Igna, Patrizia; Alaggio, Rita

    2015-01-01

    Objectives The aim of this study was to investigate the expression of DAX-1 in a series of pediatric rhabdomyosarcomas (RMS) with known translocation and compare it to Ap2β, known to be selectively expressed in ARMS. Design We revised a series of 71 alveolar rhabdomyosarcomas (ARMS), enrolled in the Italian Protocols RMS 79 and 96, and 23 embryonal rhabdomyosarcomas (ERMS) as controls. Before investigating Ap2β and DAX-1, ARMS were reviewed and reclassified as 48 ARMS and 23 non-ARMS. Results Translocation positive ARMS showed a characteristic Ap2β/DAX-1+ staining pattern in 78% of cases, while 76% of classic ERMS were negative for both. Ap2β alone was positive in 3.9% of RMS lacking translocation, whereas DAX-1 alone was positive in 25.4%. Conversely, 9% and 6% of translocation positive ARMS were positive only for DAX-1 or Ap2β, respectively. The 23 non-ARMS shared the same phenotype as ERMS but had a higher frequency of DAX-1 expression. Conclusions DAX-1 is less specific than Ap2β, however it is a sensitive marker for translocation positive ARMS and can be helpful in their diagnosis if used in combination with Ap2β. PMID:26168243

  8. Background sources at PEP

    SciTech Connect

    Lynch, H.; Schwitters, R.F.; Toner, W.T.

    1988-01-01

    Important sources of background for PEP experiments are studied. Background particles originate from high-energy electrons and positrons which have been lost from stable orbits, ..gamma..-rays emitted by the primary beams through bremsstrahlung in the residual gas, and synchrotron radiation x-rays. The effect of these processes on the beam lifetime are calculated and estimates of background rates at the interaction region are given. Recommendations for the PEP design, aimed at minimizing background are presented. 7 figs., 4 tabs.

  9. Building Background Knowledge

    ERIC Educational Resources Information Center

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

    2014-01-01

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

  10. Adsorption-driven translocation of polymer chain into nanopores

    NASA Astrophysics Data System (ADS)

    Yang, Shuang; Neimark, Alexander V.

    2012-06-01

    The polymer translocation into nanopores is generally facilitated by external driving forces, such as electric or hydrodynamic fields, to compensate for entropic restrictions imposed by the confinement. We investigate the dynamics of translocation driven by polymer adsorption to the confining walls that is relevant to chromatographic separation of macromolecules. By using the self-consistent field theory, we study the passage of a chain trough a small opening from cis to trans compartments of spherical shape with adsorption potential applied in the trans compartment. The chain transfer is modeled as the Fokker-Plank diffusion along the free energy landscape of the translocation pass represented as a sum of the free energies of cis and trans parts of the chain tethered to the pore opening. We investigate how the chain length, the size of trans compartment, the magnitude of adsorption potential, and the extent of excluded volume interactions affect the translocation time and its distribution. Interplay of these factors brings about a variety of different translocation regimes. We show that excluded volume interactions within a certain range of adsorption potentials can cause a local minimum on the free energy landscape, which is absent for ideal chains. The adsorption potential always leads to the decrease of the free energy barrier, increasing the probability of successful translocation. However, the translocation time depends non-monotonically of the magnitude of adsorption potential. Our calculations predict the existence of the critical magnitude of adsorption potential, which separates favorable and unfavorable regimes of translocation.

  11. Adsorption-driven translocation of polymer chain into nanopores.

    PubMed

    Yang, Shuang; Neimark, Alexander V

    2012-06-01

    The polymer translocation into nanopores is generally facilitated by external driving forces, such as electric or hydrodynamic fields, to compensate for entropic restrictions imposed by the confinement. We investigate the dynamics of translocation driven by polymer adsorption to the confining walls that is relevant to chromatographic separation of macromolecules. By using the self-consistent field theory, we study the passage of a chain trough a small opening from cis to trans compartments of spherical shape with adsorption potential applied in the trans compartment. The chain transfer is modeled as the Fokker-Plank diffusion along the free energy landscape of the translocation pass represented as a sum of the free energies of cis and trans parts of the chain tethered to the pore opening. We investigate how the chain length, the size of trans compartment, the magnitude of adsorption potential, and the extent of excluded volume interactions affect the translocation time and its distribution. Interplay of these factors brings about a variety of different translocation regimes. We show that excluded volume interactions within a certain range of adsorption potentials can cause a local minimum on the free energy landscape, which is absent for ideal chains. The adsorption potential always leads to the decrease of the free energy barrier, increasing the probability of successful translocation. However, the translocation time depends non-monotonically of the magnitude of adsorption potential. Our calculations predict the existence of the critical magnitude of adsorption potential, which separates favorable and unfavorable regimes of translocation. PMID:22697566

  12. Microbial translocation in the pathogenesis of HIV infection and AIDS.

    PubMed

    Marchetti, Giulia; Tincati, Camilla; Silvestri, Guido

    2013-01-01

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

  13. Multistep current signal in protein translocation through graphene nanopores.

    PubMed

    Bonome, Emma Letizia; Lepore, Rosalba; Raimondo, Domenico; Cecconi, Fabio; Tramontano, Anna; Chinappi, Mauro

    2015-05-01

    In nanopore sensing experiments, the properties of molecules are probed by the variation of ionic currents flowing through the nanopore. In this context, the electronic properties and the single-layer thickness of graphene constitute a major advantage for molecule characterization. Here we analyze the translocation pathway of the thioredoxin protein across a graphene nanopore, and the related ionic currents, by integrating two nonequilibrium molecular dynamics methods with a bioinformatic structural analysis. To obtain a qualitative picture of the translocation process and to identify salient features we performed unsupervised structural clustering on translocation conformations. This allowed us to identify some specific and robust translocation intermediates, characterized by significantly different ionic current flows. We found that the ion current strictly anticorrelates with the amount of pore occupancy by thioredoxin residues, providing a putative explanation of the multilevel current scenario observed in recently published translocation experiments. PMID:25866995

  14. Strandwise translocation of a DNA glycosylase on undamaged DNA

    SciTech Connect

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

    2012-05-14

    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.

  15. [Mechanism of tRNA translocation on the ribosome].

    PubMed

    Rodnina, M V; Semenkov, Iu P; Savelsbergh, A; Katunin, V I; Peske, F; Wilden, B; Wintermeyer, W

    2001-01-01

    During the translocation step of the elongation cycle of peptide synthesis two tRNAs together with the mRNA move synchronously and rapidly on the ribosome. Translocation is catalyzed by the elongation factor G (EF-G) and requires GTP hydrolysis. The fundamental biochemical features of the process were worked out in the 1970-80s, to a large part by A.S. Spirin and his colleagues. Recent results from pre-steady-state kinetic analysis and cryoelectron microscopy suggest that translocation is a multistep dynamic process that entails large-scale structural rearrangements of both ribosome and EF-G. Kinetic and thermodynamic data, together with the structural information on the conformational changes of the ribosome and of EF-G, provide a detailed mechanistic model of translocation and suggest a mechanism of translocation catalysis by EF-G. PMID:11524952

  16. Polypeptide translocation by the AAA+ ClpXP protease machine

    PubMed Central

    Barkow, Sarah R.; Levchenko, Igor; Baker, Tania A.; Sauer, Robert T.

    2009-01-01

    In the AAA+ ClpXP protease, ClpX uses repeated cycles of ATP hydrolysis to pull native proteins apart and to translocate the denatured polypeptide into ClpP for degradation. Here, we probe polypeptide features important for translocation. ClpXP degrades diverse synthetic peptide substrates despite major differences in side-chain chirality, size, and polarity. Moreover, translocation occurs without a peptide –NH and with 10 methylenes between successive peptide bonds. Pulling on homopolymeric tracts of glycine, proline, and lysine also allows efficient ClpXP degradation of a stably folded protein. Thus, minimal chemical features of a polypeptide chain are sufficient for translocation and protein unfolding by the ClpX machine. These results suggest that the translocation pore of ClpX is highly elastic, allowing interactions with a wide-range of chemical groups, a feature likely to be shared by many AAA+ unfoldases. PMID:19549599

  17. Range-wide success of red-cockaded woodpecker translocations.

    SciTech Connect

    Edwards, John W.; Costa, Ralph

    2004-12-31

    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.

  18. Toward a structural understanding of co-translational protein translocation.

    PubMed

    Voorhees, Rebecca M; Hegde, Ramanujan S

    2016-08-01

    The translocation of most eukaryotic secreted and integral membrane proteins occurs co-translationally at the endoplasmic reticulum (ER). These nascent polypeptides are recognized on the ribosome by the signal recognition particle (SRP), targeted to the ER, and translocated across or inserted into the membrane by the Sec61 translocation channel. Structural analysis of these co-translational processes has been challenging due to the size, complexity, and flexibility of the targeting and translocation machinery. Recent technological advances in cryo-electron microscopy (cryo-EM) have resulted in increasingly powerful tools to study large, heterogeneous, and low-abundance samples. These advances are being utilized to obtain near-atomic resolution reconstructions of functional translation, targeting, and translocation intermediates, paving the way to a mechanistic understanding of protein biogenesis. PMID:27155805

  19. Translocations of amphibians: Proven management method or experimental technique

    USGS Publications Warehouse

    Seigel, Richard A.; Dodd, C. Kenneth, Jr.

    2002-01-01

    In an otherwise excellent review of metapopulation dynamics in amphibians, Marsh and Trenham (2001) make the following provocative statements (emphasis added): If isolation effects occur primarily in highly disturbed habitats, species translocations may be necessary to promote local and regional population persistence. Because most amphibians lack parental care, they areprime candidates for egg and larval translocations. Indeed, translocations have already proven successful for several species of amphibians. Where populations are severely isolated, translocations into extinct subpopulations may be the best strategy to promote regional population persistence. We take issue with these statements for a number of reasons. First, the authors fail to cite much of the relevant literature on species translocations in general and for amphibians in particular. Second, to those unfamiliar with current research in amphibian conservation biology, these comments might suggest that translocations are a proven management method. This is not the case, at least in most instances where translocations have been evaluated for an appropriate period of time. Finally, the authors fail to point out some of the negative aspects of species translocation as a management method. We realize that Marsh and Trenham's paper was not concerned primarily with translocations. However, because Marsh and Trenham (2001) made specific recommendations for conservation planners and managers (many of whom are not herpetologists or may not be familiar with the pertinent literature on amphibians), we believe that it is essential to point out that not all amphibian biologists are as comfortable with translocations as these authors appear to be. We especially urge caution about advocating potentially unproven techniques without a thorough review of available options.

  20. Minimizing the cost of translocation failure with decision-tree models that predict species' behavioral response in translocation sites.

    PubMed

    Ebrahimi, Mehregan; Ebrahimie, Esmaeil; Bull, C Michael

    2015-08-01

    The high number of failures is one reason why translocation is often not recommended. Considering how behavior changes during translocations may improve translocation success. To derive decision-tree models for species' translocation, we used data on the short-term responses of an endangered Australian skink in 5 simulated translocations with different release conditions. We used 4 different decision-tree algorithms (decision tree, decision-tree parallel, decision stump, and random forest) with 4 different criteria (gain ratio, information gain, gini index, and accuracy) to investigate how environmental and behavioral parameters may affect the success of a translocation. We assumed behavioral changes that increased dispersal away from a release site would reduce translocation success. The trees became more complex when we included all behavioral parameters as attributes, but these trees yielded more detailed information about why and how dispersal occurred. According to these complex trees, there were positive associations between some behavioral parameters, such as fight and dispersal, that showed there was a higher chance, for example, of dispersal among lizards that fought than among those that did not fight. Decision trees based on parameters related to release conditions were easier to understand and could be used by managers to make translocation decisions under different circumstances. PMID:25737134

  1. The Cosmic Background Explorer.

    ERIC Educational Resources Information Center

    Gulkis, Samuel; And Others

    1990-01-01

    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)

  2. Palindrome-Mediated Translocations in Humans: A New Mechanistic Model for Gross Chromosomal Rearrangements

    PubMed Central

    Inagaki, Hidehito; Kato, Takema; Tsutsumi, Makiko; Ouchi, Yuya; Ohye, Tamae; Kurahashi, Hiroki

    2016-01-01

    Palindromic DNA sequences, which can form secondary structures, are widely distributed in the human genome. Although the nature of the secondary structure—single-stranded “hairpin” or double-stranded “cruciform”—has been extensively investigated in vitro, the existence of such unusual non-B DNA in vivo remains controversial. Here, we review palindrome-mediated gross chromosomal rearrangements possibly induced by non-B DNA in humans. Recent advances in next-generation sequencing have not yet overcome the difficulty of palindromic sequence analysis. However, a dozen palindromic AT-rich repeat (PATRR) sequences have been identified at the breakpoints of recurrent or non-recurrent chromosomal translocations in humans. The breakages always occur at the center of the palindrome. Analyses of polymorphisms within the palindromes indicate that the symmetry and length of the palindrome affect the frequency of the de novo occurrence of these palindrome-mediated translocations, suggesting the involvement of non-B DNA. Indeed, experiments using a plasmid-based model system showed that the formation of non-B DNA is likely the key to palindrome-mediated genomic rearrangements. Some evidence implies a new mechanism that cruciform DNAs may come close together first in nucleus and illegitimately joined. Analysis of PATRR-mediated translocations in humans will provide further understanding of gross chromosomal rearrangements in many organisms. PMID:27462347

  3. Palindrome-Mediated Translocations in Humans: A New Mechanistic Model for Gross Chromosomal Rearrangements.

    PubMed

    Inagaki, Hidehito; Kato, Takema; Tsutsumi, Makiko; Ouchi, Yuya; Ohye, Tamae; Kurahashi, Hiroki

    2016-01-01

    Palindromic DNA sequences, which can form secondary structures, are widely distributed in the human genome. Although the nature of the secondary structure-single-stranded "hairpin" or double-stranded "cruciform"-has been extensively investigated in vitro, the existence of such unusual non-B DNA in vivo remains controversial. Here, we review palindrome-mediated gross chromosomal rearrangements possibly induced by non-B DNA in humans. Recent advances in next-generation sequencing have not yet overcome the difficulty of palindromic sequence analysis. However, a dozen palindromic AT-rich repeat (PATRR) sequences have been identified at the breakpoints of recurrent or non-recurrent chromosomal translocations in humans. The breakages always occur at the center of the palindrome. Analyses of polymorphisms within the palindromes indicate that the symmetry and length of the palindrome affect the frequency of the de novo occurrence of these palindrome-mediated translocations, suggesting the involvement of non-B DNA. Indeed, experiments using a plasmid-based model system showed that the formation of non-B DNA is likely the key to palindrome-mediated genomic rearrangements. Some evidence implies a new mechanism that cruciform DNAs may come close together first in nucleus and illegitimately joined. Analysis of PATRR-mediated translocations in humans will provide further understanding of gross chromosomal rearrangements in many organisms. PMID:27462347

  4. Backgrounds in Language.

    ERIC Educational Resources Information Center

    Maxwell, John C.; Long, Barbara K.

    "Backgrounds in Language," a field-tested inservice course designed for use by groups of 15 or 25 language arts teachers, provides the subject matter background teachers need to make informed decisions about what curriculum materials to use in what way, at what time, and with which students. The course is comprised of eight 2-hour sessions,…

  5. EML4-ALK translocation is associated with early onset of disease and other clinicopathological features in Chinese female never-smokers with non-small-cell lung cancer

    PubMed Central

    REN, WEIHONG; ZHANG, BO; MA, JIE; LI, WENCAI; LAN, JIANYUN; MEN, HUI; ZHANG, QINXIAN

    2015-01-01

    Non-small-cell lung cancer (NSCLC) with echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase (EML4-ALK) translocation is resistant to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs), including gefitinib and erlotinib, but responds to the ALK-TKI crizotinib. Characterization of EML4-ALK translocation may provide invaluable information to facilitate disease diagnosis and improve the outcome of customized treatment. Although the occurrence of EML4-ALK translocation is likely to be affected by the smoking habits and gender of patients, the translocation has not been characterized extensively in female never-smokers with NSCLC. Therefore, 280 female never-smokers that were diagnosed with NSCLC were enrolled in the present study, and characteristics of EML4-ALK translocation, including the frequency, were determined in these NSCLC patients. EML4-ALK fusion variants were detected using Multiplex one-step reverse transcription-polymerase chain reaction and subsequently confirmed by DNA sequencing and Vysis ALK Break Apart fluorescence in situ hybridization analysis. The EML4-ALK fusion variants were detected in 21 carcinoma tissue specimens, accounting for 7.5% of the enrolled patients. Out of these patients with EML4-ALK fusion variants, EML4-ALK fusion variant 1 was identified in 12 patients, indicating that variant 1 is the most common type of EML4-ALK fusion gene in the present cohort of patients. ALK mRNA was aberrantly expressed in all the tissues with EML4-ALK translocation, but not in the carcinoma tissues without EML4-ALK translocation. In addition, the EML4-ALK translocation was more frequently found in younger patients. The median age of patients with EML4-ALK translocation was 50.95±2.29 years, which was significantly younger (P<0.01) than the median age of the patients without EML4-ALK translocation (57.15±0.56). The EML4-ALK translocation was detected exclusively in undifferentiated tumors that were graded as

  6. Forced Translocation of Polymer through Nanopore: Deterministic Model and Simulations

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

    We propose a new theoretical model of forced translocation of a polymer chain through a nanopore. We assume that DNA translocation at high fields proceeds too fast for the chain to relax, and thus the chain unravels loop by loop in an almost deterministic way. So the distribution of translocation times of a given monomer is controlled by the initial conformation of the chain (the distribution of its loops). Our model predicts the translocation time of each monomer as an explicit function of initial polymer conformation. We refer to this concept as ``fingerprinting''. The width of the translocation time distribution is determined by the loop distribution in initial conformation as well as by the thermal fluctuations of the polymer chain during the translocation process. We show that the conformational broadening δt of translocation times of m-th monomer δtm^1.5 is stronger than the thermal broadening δtm^1.25 The predictions of our deterministic model were verified by extensive molecular dynamics simulations

  7. Analyzing kinesin motor domain translocation in cultured hippocampal neurons

    PubMed Central

    Huang, Chung-Fang; Banker, Gary

    2016-01-01

    Neuronal microtubules are subject to extensive posttranslational modifications and are bound by MAPs, tip-binding proteins, and other accessory proteins. All of these features, which are difficult to replicate in vitro, are likely to influence the translocation of kinesin motors. Here we describe assays for evaluating the translocation of a population of fluorescently labeled kinesin motor domains, based on their accumulation in regions of the cell enriched in microtubule plus ends. Neurons lend themselves to these experiments because of their microtubule organization. In axons, microtubules are oriented with their plus ends out; dendrites contain a mixed population of microtubules, but those near the tips are also plus end out. The assays involve the expression of constitutively active kinesins that can walk processively, but that lack the autoinhibitory domain in the tail that normally prevents their binding to microtubules until they attach to vesicles. The degree to which such motor domains accumulate at neurite tips serves as a measure of the efficiency of their translocation. Although these assays cannot provide the kind of quantitative kinetic information obtained from in vitro assays, they offer a simple way to examine kinesin translocation in living neurons. They can be used to compare the translocation efficiency of different kinesin motors and to evaluate how mutations or posttranslational modifications within the motor domain influence kinesin translocation. Changes to motor domain accumulation in these assays can also serve as readout for changes in the microtubule cytoskeleton that affect kinesin translocation. PMID:26794516

  8. Does translocation influence physiological stress in the desert tortoise?

    USGS Publications Warehouse

    Drake, K.K.; Nussear, K.E.; Esque, T.C.; Barber, A.M.; Vittum, K.M.; Medica, P.A.; Tracy, C.R.; Hunter, K.W.

    2012-01-01

    Wildlife translocation is increasingly used to mitigate disturbances to animals or habitat due to human activities, yet little is known about the extent to which translocating animals causes stress. To understand the relationship between physiological stress and translocation, we conducted a multiyear study (2007–2009) using a population of desert tortoises (Gopherus agassizii) near Fort Irwin, California. Blood samples were collected from adult tortoises in three treatment groups (resident, translocated and control) for 1 year prior to and 2 years after translocation. Samples were analyzed by radioimmunoassay for plasma total corticosterone (CORT), a glucocorticoid hormone commonly associated with stress responses in reptiles. CORT values were analyzed in relation to potential covariates (animal sex, date, behavior, treatment, handling time, air temperature, home-range size, precipitation and annual plant production) among seasons and years. CORT values in males were higher than in females, and values for both varied monthly throughout the activity season and among years. Year and sex were strong predictors of CORT, and translocation explained little in terms of CORT. Based on these results, we conclude that translocation does not elicit a physiological stress response in desert tortoises.

  9. Correlators in nontrivial backgrounds

    SciTech Connect

    Mello Koch, Robert de; Ives, Norman; Stephanou, Michael

    2009-01-15

    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.

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

    PubMed Central

    2014-01-01

    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

  11. Translocation of threatened plants as a conservation measure in China.

    PubMed

    Liu, Hong; Ren, Hai; Liu, Qiang; Wen, XiangYing; Maunder, Michael; Gao, JiangYun

    2015-12-01

    We assessed the current status of plant conservation translocation efforts in China, a topic poorly reported in recent scientific literature. We identified 222 conservation translocation cases involving 154 species, of these 87 were Chinese endemic species and 101 (78%) were listed as threatened on the Chinese Species Red List. We categorized the life form of each species and, when possible, determined for each case the translocation type, propagule source, propagule type, and survival and reproductive parameters. A surprisingly large proportion (26%) of the conservation translocations in China were conservation introductions, largely implemented in response to large-scale habitat destruction caused by the Three-Gorge Dam and another hydropower project. Documentation and management of the translocations varied greatly. Less than half the cases had plant survival records. Statistical analyses showed that survival percentages were significantly correlated with plant life form and the type of planting materials. Thirty percent of the cases had records on whether or not individuals flowered or fruited. Results of information theoretic model selection indicated that plant life form, translocation type, propagule type, propagule source, and time since planting significantly influenced the likelihood of flowering and fruiting on the project level. We suggest that the scientific-based application of species conservation translocations should be promoted as part of a commitment to species recovery management. In addition, we recommend that the common practice of within and out of range introductions in nature reserves to be regulated more carefully due to its potential ecological risks. We recommend the establishment of a national office and database to coordinate conservation translocations in China. Our review effort is timely considering the need for a comprehensive national guideline for the newly announced nation-wide conservation program on species with extremely

  12. Can hunting of translocated nuisance Canada geese reduce local conflicts?

    USGS Publications Warehouse

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

    2006-01-01

    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.

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

    PubMed Central

    2012-01-01

    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

  14. Slowing DNA Translocation through a Nanopore Using a Functionalized Electrode

    PubMed Central

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

    2013-01-01

    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

  15. Ribosomal Translocation: One Step Closer to the Molecular Mechanism

    PubMed Central

    Shoji, Shinichiro; Walker, Sarah E.; Fredrick, Kurt

    2010-01-01

    Protein synthesis occurs in ribosomes, the targets of numerous antibiotics. How these large and complex machines read and move along mRNA have proven to be challenging questions. In this Review, we focus on translocation, the last step of the elongation cycle in which movement of tRNA and mRNA is catalyzed by elongation factor G. Translocation entails large-scale movements of the tRNAs and conformational changes in the ribosome that require numerous tertiary contacts to be disrupted and reformed. We highlight recent progress toward elucidating the molecular basis of translocation and how various antibiotics influence tRNA–mRNA movement. PMID:19173642

  16. Breakpoint analysis of the recurrent constitutional t(8;22)(q24.13;q11.21) translocation

    PubMed Central

    2014-01-01

    Backgrounds The t(8;22)(q24.13;q11.2) has been identified as one of several recurrent constitutional translocations mediated by palindromic AT-rich repeats (PATRRs). Although the breakage on 22q11 utilizes the same PATRR as that of the more prevalent constitutional t(11;22)(q23;q11.2), the breakpoint region on 8q24 has not been elucidated in detail since the analysis of palindromic sequence is technically challenging. Results In this study, the entire 8q24 breakpoint region has been resolved by next generation sequencing. Eight polymorphic alleles were identified and compared with the junction sequences of previous and two recently identified t(8;22) cases . All of the breakpoints were found to be within the PATRRs on chromosomes 8 and 22 (PATRR8 and PATRR22), but the locations were different among cases at the level of nucleotide resolution. The translocations were always found to arise on symmetric PATRR8 alleles with breakpoints at the center of symmetry. The translocation junction is often accompanied by symmetric deletions at the center of both PATRRs. Rejoining occurs with minimal homology between the translocation partners. Remarkably, comparison of der (8) to der(22) sequences shows identical breakpoint junctions between them, which likely represent products of two independent events on the basis of a classical model. Conclusions Our data suggest the hypothesis that interactions between the two PATRRs prior to the translocation event might trigger illegitimate recombination resulting in the recurrent palindrome-mediated translocation. PMID:25478009

  17. Pseudomonas fluorescens alters epithelial permeability and translocates across Caco-2/TC7 intestinal cells

    PubMed Central

    2010-01-01

    Background Pseudomonas fluorescens has long been considered as a psychrotrophic microorganism. Recently, we have shown that clinical strains of P. fluorescens (biovar 1) are able to adapt at a growth temperature of 37°C or above and induce a specific inflammatory response. Interestingly, a highly specific antigen of P. fluorescens, I2, is detected in the serum of patients with Crohn's disease but the possible role of this bacterium in the disease has not yet been explored. In the present study, we examined the ability of a psychrotrophic and a clinical strain of P. fluorescens to modulate the permeability of a Caco-2/TC7 intestinal epithelial model, reorganize the actin cytoskeleton, invade the target cells and translocate across the epithelium. The behaviour of these two strains was compared to that of the well known opportunistic pathogen P. aeruginosa PAO1. Results Both strains of P. fluorescens were found to decrease the transepithelial resistance (TER) of Caco-2/TC7 differentiated monolayers. This was associated with an increase in paracellular permeability and F-actin microfilaments rearrangements. Moreover, the invasion and translocation tests demonstrated that the two strains used in this study can invade and translocate across the differentiated Caco-2/TC7 cell monolayers. Conclusions The present work shows for the first time, that P. fluorescens is able to alter the intestinal epithelial barrier function by disorganizing the F-actin microfilament network. Moreover, we reveal that independently of their origins, the two P. fluorescens strains can translocate across differentiated Caco-2/TC7 cell monolayers by using the transcellular pathway. These findings could, at least in part, explain the presence of the P. fluorescens specific I2 antigen in the serum of patients with Crohn's disease. PMID:21110894

  18. Translocation of signalling proteins to the plasma membrane revealed by a new bioluminescent procedure

    PubMed Central

    2011-01-01

    Background Activation by extracellular ligands of G protein-coupled (GPCRs) and tyrosine kinase receptors (RTKs), results in the generation of second messengers that in turn control specific cell functions. Further, modulation/amplification or inhibition of the initial signalling events, depend on the recruitment onto the plasma membrane of soluble protein effectors. High throughput methodologies to monitor quantitatively second messenger production, have been developed over the last years and are largely used to screen chemical libraries for drug development. On the contrary, no such high throughput methods are yet available for the other aspect of GPCRs regulation, i.e. protein translocation to the plasma membrane, despite the enormous interest of this phenomenon for the modulation of receptor downstream functions. Indeed, to date, the experimental procedures available are either inadequate or complex and expensive. Results Here we describe the development of a novel conceptual approach to the study of cytosolic proteins translocation to the inner surface of the plasma membrane. The basis of the technique consists in: i) generating chimeras between the protein of interests and the calcium (Ca2+)-sensitive, luminescent photo-protein, aequorin and ii) taking advantage of the large Ca2+ concentration [Ca2+] difference between bulk cytosolic and the sub-plasma membrane rim. Conclusion This approach, that keeps unaffected the translocation properties of the signalling protein, can in principle be applied to any protein that, upon activation, moves from the cytosol to the plasma membrane. Thus, not only the modulation of GPCRs and RTKs can be investigated in this way, but that of all other proteins that can be recruited to the plasma membrane also independently of receptor activation. Moreover, its automated version, which can provide information about the kinetics and concentration-dependence of the process, is also applicable to high throughput screening of drugs

  19. The cortical thickness phenotype of individuals with DISC1 translocation resembles schizophrenia

    PubMed Central

    Doyle, Orla M.; Bois, Catherine; Thomson, Pippa; Romaniuk, Liana; Whitcher, Brandon; Williams, Steven C.R.; Turkheimer, Federico E.; Stefansson, Hreinn; McIntosh, Andrew M.; Mehta, Mitul A.; Lawrie, Stephen M.

    2015-01-01

    BACKGROUND. The disrupted in schizophrenia 1 (DISC1) gene locus was originally identified in a Scottish pedigree with a high incidence of psychiatric disorders that is associated with a balanced t(1;11)(q42.1;q14.3) chromosomal translocation. Here, we investigated whether members of this family carrying the t(1;11)(q42.1;q14.3) translocation have a common brain-related phenotype and whether this phenotype is similar to that observed in schizophrenia (SCZ), using multivariate pattern recognition techniques. METHODS. We measured cortical thickness, cortical surface area, subcortical volumes, and regional cerebral blood flow (rCBF) in healthy controls (HC) (n = 24), patients diagnosed with SCZ (n = 24), patients diagnosed with bipolar disorder (BP) (n = 19), and members of the original Scottish family (n = 30) who were either carriers (T+) or noncarriers (T–) of the DISC1 translocation. Binary classification models were developed to assess the differences and similarities across groups. RESULTS. Based on cortical thickness, 72% of the T– group were assigned to the HC group, 83% of the T+ group were assigned to the SCZ group, and 45% of the BP group were classified as belonging to the SCZ group, suggesting high specificity of this measurement in predicting brain-related phenotypes. Shared brain-related phenotypes between SCZ and T+ individuals were found for cortical thickness only. Finally, a classification accuracy of 73% was achieved when directly comparing the pattern of cortical thickness of T+ and T– individuals. CONCLUSION. Together, the results of this study suggest that the DISC1 translocation may increase the risk of psychiatric disorders in this pedigree by affecting neurostructural phenotypes such as cortical thickness. FUNDING. This work was supported by the National Health Service Research Scotland, the Scottish Translational Medicine Research Collaboration, the Innovative Medicines Initiative (IMI), the Engineering and Physical Sciences Research

  20. The cosmic neutrino background

    NASA Technical Reports Server (NTRS)

    Dar, Arnon

    1991-01-01

    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.

  1. Background Underground at WIPP

    NASA Astrophysics Data System (ADS)

    Esch, Ernst-Ingo; Hime, A.; Bowles, T. J.

    2001-04-01

    Recent interest to establish a dedicated underground laboratory in the United States prompted an experimental program at to quantify the enviromental backgrounds underground at the Waste Isolation Pilot Plant (WIPP) in Carlsbad, New Mexico. An outline of this program is provided along with recent experimental data on the cosmic ray muon flux at the 650 meter level of WIPP. The implications of the cosmic ray muon and fast neutron background at WIPP will be discussed in the context of new generation, low background experiments envisioned in the future.

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

    SciTech Connect

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

    1993-09-01

    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.

  3. Multiscale model of platelet translocation and collision

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

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

  4. Biphasic translocation of Bax to mitochondria.

    PubMed Central

    Capano, Michela; Crompton, Martin

    2002-01-01

    Using green fluorescent protein-tagged Bax, we demonstrate that Bax is sequestered from the cytosol of cardiomyocytes in two distinct phases following the induction of apoptosis with staurosporine. In the first phase, lasting several hours, Bax removal from the cytosol was relatively small. In the second phase, Bax was very largely removed from the cytosol and sequestered into large aggregates associated with the mitochondria. To test which of the phases involved cytochrome c release, cells were transfected with a red fluorescent protein-cytochrome c fusion. The cytochrome c fusion protein was accumulated by mitochondria of healthy cells and was released by staurosporine in phase 1. When green fluorescent protein-Bax was immunoprecipitated from extracts of cells in phase 1 and phase 2, the voltage-dependent anion channel (mitochondrial outer membrane) and the adenine nucleotide translocase (mitochondrial inner membrane) were also precipitated. These data support a two-phase model of Bax translocation in which Bax targets the mitochondrial intermembrane contact sites and releases cytochrome c in the first phase, and is then packaged into large aggregates on mitochondria in the second. PMID:12097139

  5. The GLAST Background Model

    SciTech Connect

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

    2007-10-17

    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.

  6. The GLAST Background Model

    SciTech Connect

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

    2007-07-12

    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.

  7. Improvement of the agronomic traits of a wheat-barley centric fusion by introgressing the 3HS.3BL translocation into a modern wheat cultivar.

    PubMed

    Türkösi, Edina; Farkas, András; Aranyi, Nikolett Réka; Hoffmann, Borbála; Tóth, Viola; Molnár-Láng, Márta

    2014-11-01

    The 3HS.3BL spontaneous Robertsonian translocation obtained from the progenies of wheat-barley (Chinese Spring × Betzes) hybrids backcrossed with wheat line Mv9kr1 was transferred into the modern Martonvásár wheat cultivar Mv Bodri. The translocation was identified with molecular cytogenetic methods. The inheritance of the translocation was traced using genomic in situ hybridization. Fluorescence in situ hybridization using barley subtelomeric (HvT01) and centromere-specific [(AGGGAG)4] repetitive DNA probes confirmed that the complete barley chromosome arm was involved in the Robertsonian translocation. The wheat-specific repetitive DNA probes identified the presence of the whole wheat genome, except the short arm of the 3B chromosome. Genotypes homozygous for the centric fusion were selected, after which morphological analysis was performed on the plants and the yield components were measured in the field during two consecutive vegetative seasons. The introgression of the 3HS.3BL translocation into the modern wheat cultivar Mv Bodri significantly reduced the plant height due to the incorporation of the dwarfing allele RhtD1b. The presence of the 3HS.3BL translocation in the Mv9kr1 and Mv Bodri wheat background improved tillering and seeds per plant productivity in field experiments carried out in Martonvásár and Keszthely, Hungary. PMID:25806585

  8. Translocation of flexible polymersomes across pores at the nanoscale.

    PubMed

    Pegoraro, Carla; Cecchin, Denis; Madsen, Jeppe; Warren, Nicholas; Armes, Steven P; MacNeil, Sheila; Lewis, Andrew; Battaglia, Giuseppe

    2014-04-01

    Hierarchical biological systems such as tissues and organs are often characterised by highly crowded and packed environments with nanoscopic interconnections between them. Engineering nanovectors that can penetrate and diffuse across these is critical to ensure enhanced delivery and targeting. Here we demonstrate that flexible polymeric vesicles, known as polymersomes, enable the translocation of large macromolecules across both synthetic and biological porous systems. We compare the translocation across narrow pores of different polymersome formulations. We demonstrate that effective translocation depends on the right combination of mechanical properties and surface lubrication. We prove that with the effect of external gradients (e.g. osmotic pressure, capillarity, hydration, etc.) polymersomes can translocate across pores with diameters one order of magnitude smaller without breaking. We demonstrate that these properties are essential to develop effective tissue penetration and show polymersome mediated transdermal delivery of large macromolecules such as dextran and antibodies using human ex vivo skin. PMID:26828800

  9. Translocation of an Incompressible Vesicle through a Pore.

    PubMed

    Shojaei, Hamid R; Muthukumar, Murugappan

    2016-07-01

    We have derived the free energy landscape for the translocation of a single vesicle through a narrow pore by accounting for bending and stretching of the vesicle, and the deformation of the vesicle by the pore. Emergence of a free energy barrier for translocation is a general result, and the magnitude of the barrier is calculated in terms of the various material parameters. The extent of the reduction in the barrier by the presence of an external constant force is calculated. Using the Fokker-Planck formalism, we have calculated the average translocation time corresponding to the various free energy landscapes representing different parameter sets. The dependencies of the average translocation time on the strength of the external force, vesicle size, bending and stretching moduli of the vesicle, and radius and length of the pore are derived, and the computed results are discussed. PMID:27089012

  10. DNA Translocations through Solid-State Plasmonic Nanopores

    PubMed Central

    2015-01-01

    Nanopores enable label-free detection and analysis of single biomolecules. Here, we investigate DNA translocations through a novel type of plasmonic nanopore based on a gold bowtie nanoantenna with a solid-state nanopore at the plasmonic hot spot. Plasmonic excitation of the nanopore is found to influence both the sensor signal (nanopore ionic conductance blockade during DNA translocation) and the process that captures DNA into the nanopore, without affecting the duration time of the translocations. Most striking is a strong plasmon-induced enhancement of the rate of DNA translocation events in lithium chloride (LiCl, already 10-fold enhancement at a few mW of laser power). This provides a means to utilize the excellent spatiotemporal resolution of DNA interrogations with nanopores in LiCl buffers, which is known to suffer from low event rates. We propose a mechanism based on plasmon-induced local heating and thermophoresis as explanation of our observations. PMID:25347403

  11. Translocation of α-Synuclein Expressed in Escherichia coli▿

    PubMed Central

    Ren, Guoping; Wang, Xi; Hao, Shufeng; Hu, Hongyu; Wang, Chih-chen

    2007-01-01

    α-Synuclein is a major component of Lewy bodies in Parkinson's disease. Although no signal sequence is apparent, α-synuclein expressed in Escherichia coli is mostly located in the periplasm. The possibilities that α-synuclein translocated into the periplasm across the inner membrane by the SecA or the Tat targeting route identified in bacteria and that α-synuclein was released through MscL were excluded. The signal recognition particle-dependent pathway is involved in the translocation of α-synuclein. The C-terminal 99-to-140 portion of the α-synuclein molecule plays a signal-like role for its translocation into the periplasm, cooperating with the central 61-to-95 section. The N-terminal 1-to-60 region is not required for this translocation. PMID:17277073

  12. Translocation of an Incompressible Vesicle through a Pore

    PubMed Central

    Shojaei, Hamid R.; Muthukumar, Murugappan

    2016-01-01

    We have derived the free energy landscape for the translocation of a single vesicle through a narrow pore by accounting for bending and stretching of the vesicle, and the deformation of the vesicle by the pore. Emergence of a free energy barrier for translocation is a general result, and the magnitude of the barrier is calculated in terms of the various material parameters. The extent of the reduction in the barrier by the presence of an external constant force is calculated. Using the Fokker–Planck formalism, we have calculated the average translocation time corresponding to the various free energy landscapes representing different parameter sets. The dependencies of the average translocation time on the strength of the external force, vesicle size, bending and stretching moduli of the vesicle, and radius and length of the pore are derived, and the computed results are discussed. PMID:27089012

  13. Molecular studies of translocations and trisomy involving chromosome 13

    SciTech Connect

    Robinson, W.P.; Bernasconi, F.; Dutly, F.; Schinzel, A.A.

    1996-01-11

    Twenty-four cases of trisomy 13 and one case with disomy 13, but a de novo dic(13,13)(p12p12) chromosome, were examined with molecular markers to determine the origin of the extra (or rearranged) chromosome. Twenty-one of 23 informative patients were consistent with a maternal origin of the extra chromosome. Lack of a third allele at any locus in both paternal origin cases indicate a somatic duplication of the paternal chromosome occurred. Five cases had translocation trisomy. The patient with a paternal rob(13q14q) had a maternal meiotic origin of the trisomy; thus, the paternal inheritance of the translocation chromosome was purely coincidental. Since there is not a significantly increased risk for unbalanced offspring of a t(13q14q) 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. Lack of a third allele at any locus in one of the three t(13q13q) cases indicates that it was most likely an isochromosome of postmeiotic origin, whereas the other two cases showed evidence of recombination. One balanced (nontrisomic) case with a nonmosaic 45, -13, -13, +t(13;13) karyotype was also investigated and was determined to be a somatic Robertsonian translocation between the maternal and paternal homologues, as has been found for all balanced homologous Robertsonian translocations so far investigated. Thus, it is also incorrect to assume in de novo translocation cases that the two involved chromosomes are even from the same parent. Despite a maternal origin of the trisomy, we cannot therefore infer anything about the parental origin of the chromosomes 13 and 14 involved in the translocation in the de novo t(13q14q) case nor for the two t(13;13) chromosomes showing a meiotic origin of the trisomy. 30 refs., 1 fig., 2 tabs.

  14. Survival of mountain quail translocated from two distinct source populations

    USGS Publications Warehouse

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

    2013-01-01

    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

  15. Slowing DNA Translocation in a Nanofluidic Field-Effect Transistor.

    PubMed

    Liu, Yifan; Yobas, Levent

    2016-04-26

    Here, we present an experimental demonstration of slowing DNA translocation across a nanochannel by modulating the channel surface charge through an externally applied gate bias. The experiments were performed on a nanofluidic field-effect transistor, which is a monolithic integrated platform featuring a 50 nm-diameter in-plane alumina nanocapillary whose entire length is surrounded by a gate electrode. The field-effect transistor behavior was validated on the gating of ionic conductance and protein transport. The gating of DNA translocation was subsequently studied by measuring discrete current dips associated with single λ-DNA translocation events under a source-to-drain bias of 1 V. The translocation speeds under various gate bias conditions were extracted by fitting event histograms of the measured translocation time to the first passage time distributions obtained from a simple 1D biased diffusion model. A positive gate bias was observed to slow the translocation of single λ-DNA chains markedly; the translocation speed was reduced by an order of magnitude from 18.4 mm/s obtained under a floating gate down to 1.33 mm/s under a positive gate bias of 9 V. Therefore, a dynamic and flexible regulation of the DNA translocation speed, which is vital for single-molecule sequencing, can be achieved on this device by simply tuning the gate bias. The device is realized in a conventional semiconductor microfabrication process without the requirement of advanced lithography, and can be potentially further developed into a compact electronic single-molecule sequencer. PMID:27019102

  16. Elongation factor G initiates translocation through a power stroke.

    PubMed

    Chen, Chunlai; Cui, Xiaonan; Beausang, John F; Zhang, Haibo; Farrell, Ian; Cooperman, Barry S; Goldman, Yale E

    2016-07-01

    During the translocation step of prokaryotic protein synthesis, elongation factor G (EF-G), a guanosine triphosphatase (GTPase), binds to the ribosomal PRE-translocation (PRE) complex and facilitates movement of transfer RNAs (tRNAs) and messenger RNA (mRNA) by one codon. Energy liberated by EF-G's GTPase activity is necessary for EF-G to catalyze rapid and precise translocation. Whether this energy is used mainly to drive movements of the tRNAs and mRNA or to foster EF-G dissociation from the ribosome after translocation has been a long-lasting debate. Free EF-G, not bound to the ribosome, adopts quite different structures in its GTP and GDP forms. Structures of EF-G on the ribosome have been visualized at various intermediate steps along the translocation pathway, using antibiotics and nonhydolyzable GTP analogs to block translocation and to prolong the dwell time of EF-G on the ribosome. However, the structural dynamics of EF-G bound to the ribosome have not yet been described during normal, uninhibited translocation. Here, we report the rotational motions of EF-G domains during normal translocation detected by single-molecule polarized total internal reflection fluorescence (polTIRF) microscopy. Our study shows that EF-G has a small (∼10°) global rotational motion relative to the ribosome after GTP hydrolysis that exerts a force to unlock the ribosome. This is followed by a larger rotation within domain III of EF-G before its dissociation from the ribosome. PMID:27313204

  17. Atomic structure of anthrax protective antigen pore elucidates toxin translocation.

    PubMed

    Jiang, Jiansen; Pentelute, Bradley L; Collier, R John; Zhou, Z Hong

    2015-05-28

    Anthrax toxin, comprising protective antigen, lethal factor, and oedema factor, is the major virulence factor of Bacillus anthracis, an agent that causes high mortality in humans and animals. Protective antigen forms oligomeric prepores that undergo conversion to membrane-spanning pores by endosomal acidification, and these pores translocate the enzymes lethal factor and oedema factor into the cytosol of target cells. Protective antigen is not only a vaccine component and therapeutic target for anthrax infections but also an excellent model system for understanding the mechanism of protein translocation. On the basis of biochemical and electrophysiological results, researchers have proposed that a phi (Φ)-clamp composed of phenylalanine (Phe)427 residues of protective antigen catalyses protein translocation via a charge-state-dependent Brownian ratchet. Although atomic structures of protective antigen prepores are available, how protective antigen senses low pH, converts to active pore, and translocates lethal factor and oedema factor are not well defined without an atomic model of its pore. Here, by cryo-electron microscopy with direct electron counting, we determine the protective antigen pore structure at 2.9-Å resolution. The structure reveals the long-sought-after catalytic Φ-clamp and the membrane-spanning translocation channel, and supports the Brownian ratchet model for protein translocation. Comparisons of four structures reveal conformational changes in prepore to pore conversion that support a multi-step mechanism by which low pH is sensed and the membrane-spanning channel is formed. PMID:25778700

  18. Translocation of α-helix chains through a nanopore

    NASA Astrophysics Data System (ADS)

    Yang, Zhiyong; Li, Shiben; Zhang, Linxi; ur Rehman, Ateeq; Liang, Haojun

    2010-10-01

    The translocation of α-helix chains through a nanopore is studied through Langevin dynamics simulations. The α-helix chains exhibit several different characteristics about their average translocation times and the α-helix structures when they transport through the nanopores under the driving forces. First, the relationship between average translocation times τ and the chain length N satisfies the scaling law, τ ˜Nα, and the scaling exponent α depends on the driving force f for the small forces while it is close to the Flory exponent (ν) in the other force regions. For the chains with given chain lengths, it is observed that the dependence of the average translocation times can be expressed as τ ˜f-1/2 for the small forces while can be described as τ ˜f in the large force regions. Second, for the large driving force, the average number of α-helix structures Nh decreases first and then increases in the translocation process. The average waiting time of each bead, especially of the first bead, is also dependent on the driving forces. Furthermore, an elasticity spring model is presented to reasonably explain the change of the α-helix number during the translocation and its elasticity can be locally damaged by the large driving forces. Our results demonstrate the unique behaviors of α-helix chains transporting through the pores, which can enrich our insights into and knowledge on biopolymers transporting through membranes.

  19. Atomic structure of anthrax PA pore elucidates toxin translocation

    PubMed Central

    Jiang, Jiansen; Pentelute, Bradley L.; Collier, R. John; Zhou, Z. Hong

    2015-01-01

    Summary Anthrax toxin, comprising protective antigen (PA), lethal factor (LF) and edema factor (EF), is the major virulence factor of Bacillus anthracis, an agent that causes high mortality in human and animals. PA forms oligomeric prepores that undergo conversion to membrane-spanning pores by endosomal acidification, and these pores translocate the enzymes LF and EF into the cytosol of target cells1. PA is not only a vaccine component and therapeutic target for anthrax infections but also an excellent model system for understanding the mechanism of protein translocation. Based on biochemical and electrophysiological results, researchers have proposed that a Φ-clamp composed of Phe427 residues of PA catalyzes protein translocation via a charge-state dependent Brownian ratchet2–9. Although atomic structures of PA prepores are available10–14, how PA senses low pH, converts to active pore and translocates LF and EF are not well defined without an atomic model of the PA pore. Here, by cryo electron microscopy (cryoEM) with direct electron counting, we have determined the PA pore structure at 2.9-Å resolution. The structure reveals the long-sought-after catalytic Φ-clamp and the membrane-spanning translocation channel, and supports the Brownian ratchet model for protein translocation. Comparisons of four structures reveal conformational changes in prepore to pore conversion that support a multi-step mechanism by which low-pH is sensed and the membrane-spanning channel is formed. PMID:25778700

  20. Surface modification of graphene nanopores for protein translocation

    PubMed Central

    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

    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

  1. Protein kinase C translocation in human blood platelets

    SciTech Connect

    Wang, Hoauyan; Friedman, E. )

    1990-01-01

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

  2. Surface modification of graphene nanopores for protein translocation.

    PubMed

    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

    2013-12-13

    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. PMID:24231385

  3. Using survival analysis to study translocation success in the Gila topminnow (Poeciliopsis occidentalis).

    PubMed

    Sheller, Frances J; Fagan, William F; Unmack, Peter J

    2006-10-01

    Translocation, the intentional release of captive-propagated and/or wild-caught animals into the wild in an attempt to establish, reestablish, or augment a population, is a commonly used approach to species conservation. Despite the frequent mention of translocation as an aid in threatened or endangered species recovery plans, translocations have resulted in the establishment of few sustainable populations. To improve the effectiveness of translocation efforts, it is essential to identify and adopt features that contribute to successful translocations. This study analyzed 148 translocations of the endangered Gila topminnow (Poeciliopsis occidentalis) to identify various factors that have significantly influenced translocation success. We quantified success as the "persistence time" of translocated populations and used survival analysis to interpret the role of several factors. The following factors affected persistence times of translocated populations: season in which the fish were translocated, habitat type of the translocation site, and genetic origin of the fish stocked. In general, factors associated with stocking, the population stocked, and the site of translocation can significantly affect the persistence of translocated populations and thus increase the probability of translocation success. For Gila topminnow, future translocations should be undertaken in late summer or fall (not early summer), should occur into ponds (not streams, wells, or tanks), and should generally utilize individuals from genetic lineages other than Monkey Spring. For other species, a key lesson emerging from this work is that life history attributes for each translocated species need to be considered carefully. PMID:17069370

  4. Carbon translocation in zooanthaellae-coelenterate symbioses

    SciTech Connect

    Battey, J.F.

    1985-01-01

    When host and algal triglycerides synthesized in the symbiotic sea anemone Condylactis gigantea during light and dark incubations in /sup 14/C-bicarbonate and /sup 14/C-acetate were deacylated, more then 80% of the radioactivity was found in the fatty acid moiety. In contrast, triglycerides isolated from zooxanthellae and host incubated in /sup 14/C-glycerol in the dark were found to have more then 95% of their radioactivity in the glycerol moiety. During /sup 14/C-glycerol incubations in the light, radioactivity in the fatty acid moiety of zooxanthellae triglyceride fatty acid moiety stayed below 5% during /sup 14/C-glycerol incubations in the light. These results show neither the zooxanthellae nor host can rapidly convert glycerol to fatty acid. Radioactivity from /sup 14/C-glycerol that does eventually appear in host lipid may have been respired to /sup 14/CO/sub 2/ then photosynthetically fixed by the zooxanthellae and synthesized into lipid fatty acid. The isolated zooxanthellae of C. gigantea contained 3.62 +/- 0.33 mM glycerol, which was 26x the 0.141 +/- 0.02 mM found in the coelenterate tissue. Aposymbiotic coelenterate tissue contained 0.169 +/- 0.05 mM glycerol. The metabolic inhibitors, sodium cyanide, aminooxyacetic acid and cerulenin were used to try and uncouple the production of glycerol by the zooxanthellae from its utilization by the coelenterate host. 10/sup -5/ M NaCN increased the ratio of cross photosynthesis to respiration in both intact tentacles and isolated zooxanthellae, increased translocation from 17.7 +/- 3.5% of total fixed carbon in controls to 43.5 +/- 5.79%, and doubled the amount of photosynthetically fixed carbon accumulating in the coelenterate host over that in controls.

  5. COMMUNICATION: Resonant activation in polymer translocation: new insights into the escape dynamics of molecules driven by an oscillating field

    NASA Astrophysics Data System (ADS)

    Pizzolato, N.; Fiasconaro, A.; Persano Adorno, D.; Spagnolo, B.

    2010-09-01

    The translocation of molecules across cellular membranes or through synthetic nanopores is strongly affected by thermal fluctuations. In this work we study how the dynamics of a polymer in a noisy environment changes when the translocation process is driven by an oscillating electric field. An improved version of the Rouse model for a flexible polymer has been adopted to mimic the molecular dynamics, by taking into account the harmonic interactions between adjacent monomers and the excluded-volume effect by introducing a Lennard-Jones potential between all beads. A bending recoil torque has also been included in our model. The polymer dynamics is simulated in a two-dimensional domain by numerically solving the Langevin equations of motion. Thermal fluctuations are taken into account by introducing a Gaussian uncorrelated noise. The mean first translocation time of the polymer centre of inertia shows a minimum as a function of the frequency of the oscillating forcing field. This finding represents the first evidence of the resonant activation behaviour in the dynamics of polymer translocation.

  6. Fertility of male and female mice heterozygous for the reciprocal translocation T(7;17)3BKM.

    PubMed

    Koleva, M; Benova, D

    1992-01-01

    The present paper describes the fertility of male and female mice heterozygous for the reciprocal translocation T(7;17)3BKM. This translocation was induced by gamma rays in the spermatozoa of an irradiated parent. It is characterized by "asymmetrical" localization of the breakpoints, distally in Chromosome 7 (7F5) and proximally in Chromosome 17 (17B1). The data presented here relate only those matings in which, for both partners, heterozygosity or normality could be confirmed cytogenetically. The results indicate that both male and female translocation heterozygotes are fertile, their mean litter size being reduced to about 50% of that of normal littermates. This leads to the conclusion that the multivalents mainly undergo either alternate or adjacent-1 2:2 segregation. No viable tertiary trisomics were observed among the progeny of the translocation carriers. Analysis of the frequency of the different types of multivalents in diakinesis-metaphase I spermatocytes showed a significant predominance of chain-type figures (CIV and CIII+I), with chains of four elements (CIV) being more frequent than other configurations. This demonstrates that the small marker chromosome remains attached by one of its segments to the tetravalent. PMID:1486808

  7. Refinement of background environmental monitoring measurements using meteorological frequency distribution

    SciTech Connect

    Schwartz, P.E. )

    1991-01-01

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

  8. The Cosmic Background Explorer

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

    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.

  9. Low frequency cultural noise

    NASA Astrophysics Data System (ADS)

    Sheen, Dong-Hoon; Shin, Jin Soo; Kang, Tae-Seob; Baag, Chang-Eob

    2009-09-01

    Abnormal cultural seismic noise is observed in the frequency range of 0.01-0.05 Hz. Cultural noise generated by human activities is generally observed in frequencies above 1 Hz, and is greater in the daytime than at night. The low-frequency noise presented in this paper exhibits a characteristic amplitude variation and can be easily identified from time domain seismograms in the frequency range of interest. The amplitude variation is predominantly in the vertical component, but the horizontal components also show variations. Low-frequency noise is markedly periodic, which reinforces its interpretation as cultural noise. Such noise is observed world-wide, but is limited to areas in the vicinity of railways. The amplitude variation in seismograms correlates strongly with railway timetables, and the waveform shows a wavelength shift associated with the Doppler effect, which indicates that the origin of seismic background noise in the frequency range 0.01-0.05 Hz is railways.

  10. Conflict bear translocation: investigating population genetics and fate of bear translocation in Dachigam National Park, Jammu and Kashmir, India.

    PubMed

    Mukesh; Sharma, Lalit Kumar; Charoo, Samina Amin; Sathyakumar, Sambandam

    2015-01-01

    The Asiatic black bear population in Dachigam landscape, Jammu and Kashmir is well recognized as one of the highest density bear populations in India. Increasing incidences of bear-human interactions and the resultant retaliatory killings by locals have become a serious threat to the survivorship of black bears in the Dachigam landscape. The Department of Wildlife Protection in Jammu and Kashmir has been translocating bears involved in conflicts, henceforth 'conflict bears' from different sites in Dachigam landscape to Dachigam National Park as a flagship activity to mitigate conflicts. We undertook this study to investigate the population genetics and the fate of bear translocation in Dachigam National Park. We identified 109 unique genotypes in an area of ca. 650 km2 and observed bear population under panmixia that showed sound genetic variability. Molecular tracking of translocated bears revealed that mostly bears (7 out of 11 bears) returned to their capture sites, possibly due to homing instincts or habituation to the high quality food available in agricultural croplands and orchards, while only four bears remained in Dachigam National Park after translocation. Results indicated that translocation success was most likely to be season dependent as bears translocated during spring and late autumn returned to their capture sites, perhaps due to the scarcity of food inside Dachigam National Park while bears translocated in summer remained in Dachigam National Park due to availability of surplus food resources. Thus, the current management practices of translocating conflict bears, without taking into account spatio-temporal variability of food resources in Dachigam landscape seemed to be ineffective in mitigating conflicts on a long-term basis. However, the study highlighted the importance of molecular tracking of bears to understand their movement patterns and socio-biology in tough terrains like Dachigam landscape. PMID:26267280

  11. Conflict Bear Translocation: Investigating Population Genetics and Fate of Bear Translocation in Dachigam National Park, Jammu and Kashmir, India

    PubMed Central

    Mukesh; Sharma, Lalit Kumar; Charoo, Samina Amin; Sathyakumar, Sambandam

    2015-01-01

    The Asiatic black bear population in Dachigam landscape, Jammu and Kashmir is well recognized as one of the highest density bear populations in India. Increasing incidences of bear-human interactions and the resultant retaliatory killings by locals have become a serious threat to the survivorship of black bears in the Dachigam landscape. The Department of Wildlife Protection in Jammu and Kashmir has been translocating bears involved in conflicts, henceforth ‘conflict bears’ from different sites in Dachigam landscape to Dachigam National Park as a flagship activity to mitigate conflicts. We undertook this study to investigate the population genetics and the fate of bear translocation in Dachigam National Park. We identified 109 unique genotypes in an area of ca. 650 km2 and observed bear population under panmixia that showed sound genetic variability. Molecular tracking of translocated bears revealed that mostly bears (7 out of 11 bears) returned to their capture sites, possibly due to homing instincts or habituation to the high quality food available in agricultural croplands and orchards, while only four bears remained in Dachigam National Park after translocation. Results indicated that translocation success was most likely to be season dependent as bears translocated during spring and late autumn returned to their capture sites, perhaps due to the scarcity of food inside Dachigam National Park while bears translocated in summer remained in Dachigam National Park due to availability of surplus food resources. Thus, the current management practices of translocating conflict bears, without taking into account spatio-temporal variability of food resources in Dachigam landscape seemed to be ineffective in mitigating conflicts on a long-term basis. However, the study highlighted the importance of molecular tracking of bears to understand their movement patterns and socio-biology in tough terrains like Dachigam landscape. PMID:26267280

  12. Frequency curves

    USGS Publications Warehouse

    Riggs, H.C.

    1968-01-01

    This manual describes graphical and mathematical procedures for preparing frequency curves from samples of hydrologic data. It also discusses the theory of frequency curves, compares advantages of graphical and mathematical fitting, suggests methods of describing graphically defined frequency curves analytically, and emphasizes the correct interpretations of a frequency curve.

  13. Berkeley Low Background Facility

    SciTech Connect

    Thomas, K. J.; Norman, E. B.; Smith, A. R.; Poon, A. W. P.; Chan, Y. D.; Lesko, K. T.

    2015-08-17

    The Berkeley Low Background Facility (BLBF) at Lawrence Berkeley National Laboratory (LBNL) in Berkeley, California provides low background gamma spectroscopy services to a wide array of experiments and projects. The analysis of samples takes place within two unique facilities; locally within a carefully-constructed, low background laboratory on the surface at LBNL and at the Sanford Underground Research Facility (SURF) in Lead, SD. 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/anthropogenic products; active screening via neutron activation analysis for U,Th, and K as well as a variety of stable isotopes; and neutron flux/beam characterization measurements through the use of monitors. A general overview of the facilities, services, and sensitivities will be presented. Recent activities and upgrades will also be described including an overview of the recently installed counting system at SURF (recently relocated from Oroville, CA in 2014), the installation of a second underground counting station at SURF in 2015, and future plans. The BLBF is open to any users for counting services or collaboration on a wide variety of experiments and projects.

  14. Berkeley Low Background Facility

    NASA Astrophysics Data System (ADS)

    Thomas, K. J.; Smith, A. R.; Poon, A. W. P.; Chan, Y. D.; Norman, E. B.; Lesko, K. T.

    2015-08-01

    The Berkeley Low Background Facility (BLBF) at Lawrence Berkeley National Laboratory (LBNL) in Berkeley, California provides low background gamma spectroscopy services to a wide array of experiments and projects. The analysis of samples takes place within two unique facilities; locally within a carefully-constructed, low background laboratory on the surface at LBNL and at the Sanford Underground Research Facility (SURF) in Lead, SD. 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/anthropogenic products; active screening via neutron activation analysis for U,Th, and K as well as a variety of stable isotopes; and neutron flux/beam characterization measurements through the use of monitors. A general overview of the facilities, services, and sensitivities will be presented. Recent activities and upgrades will also be described including an overview of the recently installed counting system at SURF (recently relocated from Oroville, CA in 2014), the installation of a second underground counting station at SURF in 2015, and future plans. The BLBF is open to any users for counting services or collaboration on a wide variety of experiments and projects.

  15. China: Background Notes Series.

    ERIC Educational Resources Information Center

    Reams, Joanne Reppert

    Concise background information on the People's Republic of China is provided. The publication begins with a profile of the country, outlining the people, geography, economy, and membership in international organizations. The bulk of the document then discusses in more detail China's people, geography, history, government, education, economy, and…

  16. Monitored background radiometer

    NASA Technical Reports Server (NTRS)

    Ruel, C.; Larouche, M.; Donato, M.

    1986-01-01

    The infrared (IR) testing of the Olympus thermal model has provided a capability to perform cost effective thermal balance testing of satellites and satellite components. A high-accuracy monitored background radiometer was developed for the measurement of absorbed radiation heat flux encountered during IR thermal vacuum testing of spacecraft. The design, development, and calibration of this radiometer is described.

  17. Nonthermal cosmic neutrino background

    NASA Astrophysics Data System (ADS)

    Chen, Mu-Chun; Ratz, Michael; Trautner, Andreas

    2015-12-01

    We point out that, for Dirac neutrinos, in addition to the standard thermal cosmic neutrino background (C ν B ), there could also exist a nonthermal neutrino background with comparable number density. As the right-handed components are essentially decoupled from the thermal bath of standard model particles, relic neutrinos with a nonthermal distribution may exist until today. The relic density of the nonthermal (nt) background can be constrained by the usual observational bounds on the effective number of massless degrees of freedom Neff and can be as large as nν nt≲0.5 nγ. In particular, Neff can be larger than 3.046 in the absence of any exotic states. Nonthermal relic neutrinos constitute an irreducible contribution to the detection of the C ν B and, hence, may be discovered by future experiments such as PTOLEMY. We also present a scenario of chaotic inflation in which a nonthermal background can naturally be generated by inflationary preheating. The nonthermal relic neutrinos, thus, may constitute a novel window into the very early Universe.

  18. Foregrounding the Background.

    ERIC Educational Resources Information Center

    Robbins, Bruce

    1998-01-01

    Argues that when introductory activities to the classics begin with background information, it can upstage or confine the life of the story, and shows little faith in the students as readers or in the literature itself. Suggests sometimes letting the literature begin, and then helping students make sense of it. Discusses examples from "To Kill a…

  19. Computer simulation of viral-assembly and translocation

    NASA Astrophysics Data System (ADS)

    Mahalik, Jyoti Prakash

    We investigated four different problems using coarse grained computational models : self-assembly of single stranded (ss) DNA virus, ejection dynamics of double stranded(ds) DNA from phages, translocation of ssDNA through MspA protein pore, and segmental dynamics of a polymer translocating through a synthetic nanopore. In the first part of the project, we investigated the self-assembly of a virus with and without its genome. A coarse-grained model was proposed for the viral subunit proteins and its genome (ssDNA). Langevin dynamics simulation, and replica exchange method were used to determine the kinetics and energetics of the self-assembly process, respectively. The self-assembly follows a nucleation-growth kind of mechanism. The ssDNA plays a crucial role in the self-assembly by acting as a template and enhancing the local concentration of the subunits. The presence of the genome does not changes the mechanism of the self-assembly but it reduces the nucleation time and enhances the growth rate by almost an order of magnitude. The second part of the project involves the investigation of the dynamics of the ejection of dsDNA from phages. A coarse-grained model was used for the phage and dsDNA. Langevin dynamics simulation was used to investigate the kinetics of the ejection. The ejection is a stochastic process and a slow intermediate rate kinetics was observed for most ejection trajectories. We discovered that the jamming of the DNA at the pore mouth at high packing fraction and for a disordered system is the reason for the intermediate slow kinetics. The third part of the project involves translocation of ssDNA through MspA protein pore. MspA protein pore has the potential for genome sequencing because of its ability to clearly distinguish the four different nucleotides based on their blockade current, but it is a challenge to use this pore for any practical application because of the very fast traslocation time. We resolved the state of DNA translocation

  20. Specific chromosomal IG translocations have different prognoses in chronic lymphocytic leukemia

    PubMed Central

    Nguyen-Khac, Florence; Chapiro, Elise; Lesty, Claude; Grelier, Aurore; Luquet, Isabelle; Radford-Weiss, Isabelle; Lefebvre, Christine; Fert-Ferrer, Sandra; Callet-Bauchu, Evelyne; Lippert, Eric; Raggueneau, Victoria; Michaux, Lucienne; Barin, Carole; Collonge-Rame, Marie-Agnes; Mugneret, Francine; Eclache, Virginie; Taviaux, Sylvie; Dastugue, Nicole; Richebourg, Steven; Struski, Stéphanie; Talmant, Pascaline; Baranger, Laurence; Gachard, Nathalie; Gervais, Carine; Quilichini, Benoit; Settegrana, Catherine; Maloum, Karim; Davi, Frederic; Merle-Béral, Hélène

    2011-01-01

    Background Chromosomal translocations are usually analyzed as a single entity, and are associated with a poor outcome in chronic lymphocytic leukemia. Translocations involving immunoglobulin genes are recurrent, but uncommon (<5%), and their individual prognosis is not clear. The two most frequent partners are BCL2 (18q21) and BCL3 (19q13). Designs and methods Herein, 75 cases are reported of chronic lymphocytic leukemia and t(14;18) (BCL2-CLLs). Our series benefits from morphological, immunological and cytogenetical reviews. The IGHV status analyses were performed by referring laboratories. Comparison was made with our previously published series of chronic lymphocytic leukemia patients with t(14;19) (BCL3-CLLs, n=29). Results Compared with BCL3-CLLs, lymphocytosis was lower in BCL2-CLLs (p<0.008), and splenomegaly was less frequent (p<0.0001). There were more “typical” morphologies (p<0.005) and Matutes scores >4 (p<0.001) in the BCL2-CLLs group, and less CD38 expression (p<0.04). More variant BCL2-translocations were observed (t(18;22), n=11; 2t(2;18), n=2; p<0.02), and BCL2-translocation was frequently single (p<0.002). Complex karyotypes (p<0.02), trisomy 12 (p<0.03), 6q deletion (p<0.002) and TP53 deletion (p<0.02) were less frequent in BCL2-CLLs, whereas 13q deletion was more frequent (p<0.005). The IGHV gene was frequently mutated in BCL2-CLLs (p<0.0001). Treatment-free survival was longer in BCL2-CLLs (p<0.0001). Conclusions BCL2-CLL.S express CD5 and lack expression of CD38, and have a Matutes score ≥4, frequent trisomy 12, no ATM and 6q deletions, and a mutated IGHV status. Compared to BCL3-CLLs, BCL2-CLLs are much less aggressive; indicating that identifying individual translocations and cytogenetic partners would allow improved patient stratification. PMID:22432063

  1. Confusion background from compact binaries

    NASA Astrophysics Data System (ADS)

    Regimbau, T.; Hughes, Scott A.

    2010-05-01

    Double neutron stars are one of the most promizing sources for terrestrial gravitational wave interferometers. For actual interferometers and their planned upgrades, the probability of having a signal present in the data is small, but as the sensitivity improves, the detection rate increases and the waveforms may start to overlap, creating a confusion background, ultimately limiting the capabilities of future detectors. The third generation Einstein Telescope, with an horizon of z > 1 and very low frequency "seismic wall" may be affected by such confusion noise. At a minimum, careful data analysis will be require to separate signals which will appear confused. This result should be borne in mind when designing highly advanced future instruments.

  2. High-speed detection of DNA translocation in nanopipettes

    NASA Astrophysics Data System (ADS)

    Fraccari, Raquel L.; Ciccarella, Pietro; Bahrami, Azadeh; Carminati, Marco; Ferrari, Giorgio; Albrecht, Tim

    2016-03-01

    We present a high-speed electrical detection scheme based on a custom-designed CMOS amplifier which allows the analysis of DNA translocation in glass nanopipettes on a microsecond timescale. Translocation of different DNA lengths in KCl electrolyte provides a scaling factor of the DNA translocation time equal to p = 1.22, which is different from values observed previously with nanopipettes in LiCl electrolyte or with nanopores. Based on a theoretical model involving electrophoresis, hydrodynamics and surface friction, we show that the experimentally observed range of p-values may be the result of, or at least be affected by DNA adsorption and friction between the DNA and the substrate surface.We present a high-speed electrical detection scheme based on a custom-designed CMOS amplifier which allows the analysis of DNA translocation in glass nanopipettes on a microsecond timescale. Translocation of different DNA lengths in KCl electrolyte provides a scaling factor of the DNA translocation time equal to p = 1.22, which is different from values observed previously with nanopipettes in LiCl electrolyte or with nanopores. Based on a theoretical model involving electrophoresis, hydrodynamics and surface friction, we show that the experimentally observed range of p-values may be the result of, or at least be affected by DNA adsorption and friction between the DNA and the substrate surface. Electronic supplementary information (ESI) available: Gel electrophoresis confirming lengths and purity of DNA samples, comparison between Axopatch 200B and custom-built setup, comprehensive low-noise amplifier characterization, representative I-V curves of nanopipettes used, typical scatter plots of τ vs. peak amplitude for the four LDNA's used, table of most probable τ values, a comparison between different fitting models for the DNA translocation time distribution, further details on the stochastic numerical simulation of the scaling statistics and the derivation of the extended

  3. Effects of rifaximin on bacterial translocation in thioacetamide-induced liver injury in rats.

    PubMed

    Harputluoglu, Murat M M; Demirel, Ulvi; Gul, Mehmet; Temel, Ismail; Gursoy, Sule; Selcuk, Engin Burak; Aladag, Murat; Bilgic, Yilmaz; Gunduz, Ercan; Seckin, Yuksel

    2012-08-01

    Intestinal bacterial overgrowth (IBO) and increased mucosal permeability are suggested to increase bacterial translocation (BT) in liver injury. Rifaximin (RIF) is a minimally absorbed oral antimicrobial agent that restores gut microflora imbalance. The aim of the present study was to investigate the effects of RIF on BT frequency in thioacetamide (TAA)-induced liver injury. Group 1 was the control. In group 2 (TAA), rats received TAA daily for 3 days. In group 3 (TAA + RIF), RIF was commenced on the same day as the first dose of TAA. In group 4 (RIF), rats received only RIF. Ileal aspirate Escherichia coli counts were significantly lower in the TAA + RIF group than in TAA group. There was no difference in BT frequency between the TAA and TAA + RIF groups. Our results suggest that factors such as intestinal barrier dysfunction and impaired host immune shield, apart from IBO, play an important role in BT in this model. PMID:22527146

  4. Low-background trace-gas detector

    NASA Technical Reports Server (NTRS)

    Rosengren, L.

    1978-01-01

    Spectrophone detects very small concentrations of trace gases. With gas in sample cell, laser is tuned to absorption line of interest. Molecular absorption in cell produces pulsed acoustical pressure at chopper frequency. Two optical paths with very different absorption lengths are used to pretune cell to balance out background absorption by cell windows.

  5. Background illumination simulator

    SciTech Connect

    Towry, E.R.

    1992-05-12

    This patent describes a testing apparatus for testing and evaluating the performance of laser seeking warheads for missiles, under simulated weather conditions. It comprises support means for supporting a warhead seeker; laser means for generating a laser beam and for directing a laser beam towards the seeker; a diffusion screen interposed between the seeker support means and the laser means for diffusing the laser beam; a collimating lens interposed between the diffusion screen and the seeker support means for collimating the diffused laser beam and for directing the collimated laser beam onto a warhead seeker, supported in the seeker support; background illuminator means for illuminating the seeker support and a seeker disposed therein, supported for movement into and out of an operating position between the diffusion means and the collimating lens for providing background lighting in simulation of weather lighting conditions; and control means for controlling the intensity of the light provided by the illuminator means to simulate various weather conditions.

  6. Some background about satellites

    NASA Technical Reports Server (NTRS)

    Burns, Joseph A.

    1986-01-01

    Four tables of planetary and satellite data are presented which list satellite discoveries, planetary parameters, satellite orbits, and satellite physical properties respectively. A scheme for classifying the satellites is provided and it is noted that most known moons fall into three general classes: regular satellites, collisional shards, and irregular satellites. Satellite processes are outlined with attention given to origins, dynamical and thermal evolution, surface processes, and composition and cratering. Background material is provided for each family of satellites.

  7. Sulfur Dioxide Inhibition of Translocation in Bean Plants 1

    PubMed Central

    Teh, Kwang Ho; Swanson, Carroll A.

    1982-01-01

    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

  8. Meiotic behaviour of evolutionary sex-autosome translocations in Bovidae.

    PubMed

    Vozdova, Miluse; Ruiz-Herrera, Aurora; Fernandez, Jonathan; Cernohorska, Halina; Frohlich, Jan; Sebestova, Hana; Kubickova, Svatava; Rubes, Jiri

    2016-09-01

    The recurrent occurrence of sex-autosome translocations during mammalian evolution suggests common mechanisms enabling a precise control of meiotic synapsis, recombination and inactivation of sex chromosomes. We used immunofluorescence and FISH to study the meiotic behaviour of sex chromosomes in six species of Bovidae with evolutionary sex-autosome translocations (Tragelaphus strepsiceros, Taurotragus oryx, Tragelaphus imberbis, Tragelaphus spekii, Gazella leptoceros and Nanger dama ruficollis). The autosomal regions of fused sex chromosomes showed normal synapsis with their homologous counterparts. Synapsis in the pseudoautosomal region (PAR) leads to the formation of characteristic bivalent (in T. imberbis and T. spekii with X;BTA13/Y;BTA13), trivalent (in T. strepsiceros and T. oryx with X/Y;BTA13 and G. leptoceros with X;BTA5/Y) and quadrivalent (in N. dama ruficollis with X;BTA5/Y;BTA16) structures at pachynema. However, when compared with other mammals, the number of pachynema lacking MLH1 foci in the PAR was relatively high, especially in T. imberbis and T. spekii, species with both sex chromosomes involved in sex autosome translocations. Meiotic transcriptional inactivation of the sex-autosome translocations assessed by γH2AX staining was restricted to their gonosomal regions. Despite intraspecies differences, the evolutionary fixation of sex-autosome translocations among bovids appears to involve general mechanisms ensuring sex chromosome pairing, synapsis, recombination and inactivation. PMID:27136937

  9. Electrostatics of polymer translocation events in electrolyte solutions

    NASA Astrophysics Data System (ADS)

    Buyukdagli, Sahin; Ala-Nissila, T.

    2016-07-01

    We develop an analytical theory that accounts for the image and surface charge interactions between a charged dielectric membrane and a DNA molecule translocating through the membrane. Translocation events through neutral carbon-based membranes are driven by a competition between the repulsive DNA-image-charge interactions and the attractive coupling between the DNA segments on the trans and the cis sides of the membrane. The latter effect is induced by the reduction of the coupling by the dielectric membrane. In strong salt solutions where the repulsive image-charge effects dominate the attractive trans-cis coupling, the DNA molecule encounters a translocation barrier of ≈10 kBT. In dilute electrolytes, the trans-cis coupling takes over image-charge forces and the membrane becomes a metastable attraction point that can trap translocating polymers over long time intervals. This mechanism can be used in translocation experiments in order to control DNA motion by tuning the salt concentration of the solution.

  10. Low processivity for DNA translocation by the ISWI molecular motor.

    PubMed

    Eastlund, Allen; Al-Ani, Gada; Fischer, Christopher J

    2015-10-01

    The motor protein ISWI (Imitation SWItch) is the conserved catalytic ATPase domain of the ISWI family of chromatin remodelers. Members of the ISWI family are involved in regulating the structure of cellular chromatin during times of transcription, translation, and repair. Current models for the nucleosome repositioning activity of ISWI and other chromatin remodelers require the translocation of the remodeling protein along double-stranded DNA through an ATP-dependent mechanism. Here we report results from spectrofluorometric stopped-flow experiments which demonstrate that ISWI displays very low processivity for free DNA translocation. By combining these results with those from experiments monitoring the DNA stimulated ATPase activity of ISWI we further demonstrate that the DNA translocation by ISWI is tightly coupled to ATP hydrolysis. The calculated coupling efficiency of 0.067±0.018 ATP/ISWI/bp is seemingly quite low in comparison to similar DNA translocases and we present potential models to account for this. Nevertheless, the tight coupling of ATP hydrolysis to DNA translocation suggests that DNA translocation is not energetically rate limiting for nucleosome repositioning by ISWI. PMID:26116984