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Search Results: 1 - 10 of 193228 matches for " Frédéric Catez "
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Centromere Architecture Breakdown Induced by the Viral E3 Ubiquitin Ligase ICP0 Protein of Herpes Simplex Virus Type 1
Sylvain Gross, Frédéric Catez, Hiroshi Masumoto, Patrick Lomonte
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0044227
Abstract: The viral E3 ubiquitin ligase ICP0 protein has the unique property to temporarily localize at interphase and mitotic centromeres early after infection of cells by the herpes simplex virus type 1 (HSV-1). As a consequence ICP0 induces the proteasomal degradation of several centromeric proteins (CENPs), namely CENP-A, the centromeric histone H3 variant, CENP-B and CENP-C. Following ICP0-induced centromere modification cells trigger a specific response to centromeres called interphase Centromere Damage Response (iCDR). The biological significance of the iCDR is unknown; so is the degree of centromere structural damage induced by ICP0. Interphase centromeres are complex structures made of proximal and distal protein layers closely associated to CENP-A-containing centromeric chromatin. Using several cell lines constitutively expressing GFP-tagged CENPs, we investigated the extent of the centromere destabilization induced by ICP0. We show that ICP0 provokes the disappearance from centromeres, and the proteasomal degradation of several CENPs from the NAC (CENP-A nucleosome associated) and CAD (CENP-A Distal) complexes. We then investigated the nucleosomal occupancy of the centromeric chromatin in ICP0-expressing cells by micrococcal nuclease (MNase) digestion analysis. ICP0 expression either following infection or in cell lines constitutively expressing ICP0 provokes significant modifications of the centromeric chromatin structure resulting in higher MNase accessibility. Finally, using human artificial chromosomes (HACs), we established that ICP0-induced iCDR could also target exogenous centromeres. These results demonstrate that, in addition to the protein complexes, ICP0 also destabilizes the centromeric chromatin resulting in the complete breakdown of the centromere architecture, which consequently induces iCDR.
HSV-1 Genome Subnuclear Positioning and Associations with Host-Cell PML-NBs and Centromeres Regulate LAT Locus Transcription during Latency in Neurons
Frédéric Catez,Christel Picard,Kathrin Held,Sylvain Gross,Antoine Rousseau,Diethilde Theil,Nancy Sawtell,Marc Labetoulle,Patrick Lomonte
PLOS Pathogens , 2012, DOI: 10.1371/journal.ppat.1002852
Abstract: Major human pathologies are caused by nuclear replicative viruses establishing life-long latent infection in their host. During latency the genomes of these viruses are intimately interacting with the cell nucleus environment. A hallmark of herpes simplex virus type 1 (HSV-1) latency establishment is the shutdown of lytic genes expression and the concomitant induction of the latency associated (LAT) transcripts. Although the setting up and the maintenance of the latent genetic program is most likely dependent on a subtle interplay between viral and nuclear factors, this remains uninvestigated. Combining the use of in situ fluorescent-based approaches and high-resolution microscopic analysis, we show that HSV-1 genomes adopt specific nuclear patterns in sensory neurons of latently infected mice (28 days post-inoculation, d.p.i.). Latent HSV-1 genomes display two major patterns, called “Single” and “Multiple”, which associate with centromeres, and with promyelocytic leukemia nuclear bodies (PML-NBs) as viral DNA-containing PML-NBs (DCP-NBs). 3D-image reconstruction of DCP-NBs shows that PML forms a shell around viral genomes and associated Daxx and ATRX, two PML partners within PML-NBs. During latency establishment (6 d.p.i.), infected mouse TGs display, at the level of the whole TG and in individual cells, a substantial increase of PML amount consistent with the interferon-mediated antiviral role of PML. “Single” and “Multiple” patterns are reminiscent of low and high-viral genome copy-containing neurons. We show that LAT expression is significantly favored within the “Multiple” pattern, which underlines a heterogeneity of LAT expression dependent on the viral genome copy number, pattern acquisition, and association with nuclear domains. Infection of PML-knockout mice demonstrates that PML/PML-NBs are involved in virus nuclear pattern acquisition, and negatively regulate the expression of the LAT. This study demonstrates that nuclear domains including PML-NBs and centromeres are functionally involved in the control of HSV-1 latency, and represent a key level of host/virus interaction.
What Are the Ethical Problems Raised by the Increase of Cognitive Capabilities in the Defence Structure: The French Legal Structure, the Ethical Position of the French Military Health Service  [PDF]
Marion Trousselard, Frédéric Canini
Psychology (PSYCH) , 2015, DOI: 10.4236/psych.2015.64047
Abstract: All contemporary discussions concerning the ethics of human experimentation are grounded in the Nuremberg Code (Macklin, 1992) which listed what for many are the basic principles underlying the ethical conduct of human research. By law all scientific researches that use human research volunteers are governed by regulations prescribing the ethical treatment of these volunteers (Jones, 1993). The present purpose concerns what Ethics is in order to discuss about how military researches are directly affected by these regulations. They particularly concern neurosciences and precisely how to improve cognition for military individuals. Main arsenal was discussed according the risk-benefit balance. Furthermore, implications for medical reflexion were proposed. The French law prescribing the ethical principles for conducting research on humans as animals have been successively defined in accordance with European texts (French Public Health Code, 1994, 2004; Favre, Vallet, Renaudeau et al., 2004). All of these have consequences for conducting the French biomedical research for the defence.
Combining Internal Data with Scenario Analysis  [PDF]
Elias Karam, Frédéric Planchet
Modern Economy (ME) , 2015, DOI: 10.4236/me.2015.65055
Abstract: A Bayesian inference approach offers a methodical concept that combines internal data with experts’ opinions. Joining these two elements with precision is certainly one of the challenges in operational risk. In this paper, we are interested in applying a Bayesian inference technique in a robust manner to be able to estimate a capital requirement that best approaches the reality. In addition, we illustrate the importance of a consistent scenario analysis in showing that the expert opinion coherence leads to a robust estimation of risk.
Improvement of Bare Soil Semi-Empirical Radar Backscattering Models (Oh and Dubois) with SAR Multi-Spectral Satellite Data (X-, C- and L-Bands)  [PDF]
Rémy Fieuzal, Frédéric Baup
Advances in Remote Sensing (ARS) , 2016, DOI: 10.4236/ars.2016.54023
Abstract: The objective of this study is to improve the performance of semi-empirical radar backscatter models, which are mainly used in microwave remote sensing (Oh 1992, Oh 2004 and Dubois). The study is based on satellite and ground data collected on bare soil surfaces during the Multispectral Crop Monitoring experimental campaign of the CESBIO laboratory in 2010 over an agricultural region in southwestern France. The dataset covers a wide range of soil (viewing top soil moisture, surface roughness and texture) and satellite (at different frequencies: X-, C- and L-bands, and different incidence angles: 24.3° to 53.3°) configurations. The proposed methodology consists in identifying and correcting the residues of the models, depending on the surface properties (roughness, moisture, texture) and/or sensor characteristics (frequency, incidence angle). Finally, one model has been retained for each frequency domain. Results show that the enhancements of the models significantly increase the simulation performances. The coefficient of correlation increases of 23% in mean and the simulation errors (RMSE) are reduced to below 2 dB (at the X and C-bands) and to 1 dB at the L-band, compared to the initial models. At the X- and C-bands, the best performances of the modified models are provided by Dubois, whereas Oh 2004 is more suitable for the L-band (r is equal to 0.69, 0.65 and 0.85). Moreover, the modified models of Oh 1992 and 2004 and Dubois, developed in this study, offer a wider domain of validity than the initial formalism and increase the capabilities of retrieving the backscattering signal in view of applications of such approaches to stronglycontrasted agricultural surface states.
Quantitative Evaluation of the Lifshitz-Type Temperature Effect on the Casimir Force  [PDF]
Frédéric Schuller, Renaud Savalle
Journal of Modern Physics (JMP) , 2017, DOI: 10.4236/jmp.2017.811105
Abstract: We consider the extension of the Casimir effect to finite temperatures in the ideal case of perfectly reflecting plates. We apply Lifshitz’s theory in its Dzyaloshinskii version, and calculate the resulting force numerically for various plate distances. We show that the limiting expression found in the literature corresponds to unrealistic values of the parameters for which the force is too small to be measurable. Preliminary remark: There exists a huge literature on the Casimir effect both theoretical and experimental. In this note we concentrate on a particular point of the subject, quoting only references directly related to this point.
The Geomagnetic Effects of Solar Activity as Measured at Ouagadougou Station  [PDF]
Aristide Marie Frédéric Gyébré, Doua Allain Gnabahou, Frédéric Ouattara
International Journal of Astronomy and Astrophysics (IJAA) , 2018, DOI: 10.4236/ijaa.2018.82013
Abstract: The coronal mass ejections (CMEs) produce by Sun poloidal magnetic fields contribute to geomagnetic storms. The geomagnetic storm effects produced by one-day-shock, two-days-shock and three-days-shock activities on Ouagadougou station F2 layer critical frequency time variation are analyzed. It is found that during the solar minimum and the increasing phases, the shock activity produces both positive and negative storms. The positive storm is observed during daytime. At the solar maximum and the decreasing phases only the positive storm is produced. At the solar minimum there is no three-days-shock activity. During the solar increasing phase the highest amplitude of the storm effect is due to the one-day-shock activity and the lowest is produced by the two-days-shock activity. At the solar maximum phase the ionosphere electric current system is not affected by the shock activity. Nevertheless, the highest amplitude of the storm effect is caused by the two-days-shock activity and the lowest by the one-day-shock activity. During the solar decreasing phase, the highest amplitude provoked by the storm is due to the three-days-shock activity and the lowest by the one-day-shock activity.
The Alarming Proximity of Parasites
Frédéric Thomas
PLOS Biology , 2012, DOI: 10.1371/journal.pbio.1000526
Army Ants Trapped by Their Evolutionary History
Frédéric Delsuc
PLOS Biology , 2012, DOI: 10.1371/journal.pbio.0000037
A New Calibrated Bayesian Internal Goodness-of-Fit Method: Sampled Posterior p-Values as Simple and General p-Values That Allow Double Use of the Data
Frédéric Gosselin
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0014770
Abstract: Recent approaches mixing frequentist principles with Bayesian inference propose internal goodness-of-fit (GOF) p-values that might be valuable for critical analysis of Bayesian statistical models. However, GOF p-values developed to date only have known probability distributions under restrictive conditions. As a result, no known GOF p-value has a known probability distribution for any discrepancy function.
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