Éditeur(s) : Pêche thonière et dispositifs de concentration de poissons, Caribbean-Martinique, 15-19 Oct 1999
Résumé : Installation and maintenance of FADs by the Government of Guam began in 1979, initially with funding from the Salstonstall-Kennedy Act through the Pacific Tuna Development Foundation. Current funding for the Guam FAD project is provided through the Dingell-Johnson/Wallop-Breaux Sport Fish Restoration programme, a Federal Aid Project funded by taxes collected on the purchase of fishing equipment and motorboat fuels nationwide. There are now sixteen operational FAD sites in Guam's waters. At a cost of approximately US$10,000 per system, concern for the rising costs of replacing and maintaining FAD systems has prompted the Department of Agriculture's Division of Aquatic and Wildlife Resources (DAWR) to investigate alternative FAD maintenance strategies and system design. Several cost-cutting measures being considered include the use of reliable solar-powered navigation lights to reduce the number of maintenance trips required, and switching to a newer generation of lighter, more durable buoys and mooring systems. Average time on station for a dawr fad system is nearing two years. Interestingly, in most cases where an errant system is recovered, the failure in the mooring system was observed to occur at a depth from 35 to 500 metres. These observations have led to speculation that additional protection of the mooring line down to 500 m may result in doubling the average time on station of most FAD systems.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00042/15324/12650.pdf
http://archimer.ifremer.fr/doc/00042/15324/

Éditeur(s) : HAL CCSD
Résumé : International audience
In addition to soluble factors, mechanical constraints and extracellular matrix stiffness are important regulators of cell fate that are mediated by cytoskeletal modifications. The EMT (epithelial-mesenchymal transition) that occurs during normal development and malignant progression is a typical example of the phenotypic switch associated with profound actin remodelling and changes in gene expression. For instance, actin dynamics control motile cell functions in EMT, in part, through regulating the subcellular localization of the myocardin-related transcription factor MKL1 (megakaryoblastic leukaemia translocation 1), a co-activator of SRF (serum-responsive factor). In the present paper, we show that MKL1 participates also to the control of the cellular switch between growth and quiescence. Experimental disconnection between MKL1 and G-actin (globular actin), by using an MKL1 mutant or enhancing the F (filamentous)-/G-actin ratio, generates a widely open chromatin state and a global increase in biosynthetic activity, classically associated with cell growth. Conversely, G-actin accumulation favours nuclear condensation and cell quiescence. These large-scale chromatin changes rely upon extensive histone modifications, exemplified by that of H3K9 (H3 Lys9) shifting from trimethylation, a heterochromatin mark, to acetylation, a mark of euchromatin. The present study provides the first evidence for a global reversible hetero/euchromatinization phenomenon triggered by the actin/MKL1 signalling pathway.
The Biochemical Journal

hal-01063933
https://hal.archives-ouvertes.fr/hal-01063933
DOI : 10.1042/BJ20131240
PUBMED : 24762104

Éditeur(s) : Elsevier Science Inc
Résumé : The sex-determining system of Crassostrea gigas is still poorly known, especially regarding the potential influence of temperature. In order to address this question, mRNA expressions of actors of the molecular cascade (Cg-DMI, Cg-SoxE, Cg-beta-catenin, Cg-Foxl2/Cg-FoxI2os) and of Oyvlg, a germ cell marker, were investigated by real-time PCR in spat grown at different temperatures (18, 22, 25 and 28 degrees C). In parallel, gonadic differentiation, gametogenesis and sex ratios were assessed by histology at each of these temperatures. Whatever the temperature, Cg-DMI, Cg-SoxE, Cg-beta-catenin and Oyvlg expressions peaked at the same developmental stage, always after Cg-Foxl2/Cg-Foxl2os (around 40-44 dpf for spat grown at 18 degrees C). Temperatures increased the kinetics of first gonadic differentiation and gametogenesis. At 25 degrees C a significant switch occurred in sex ratio towards males and in the balance of expression between male and female genes, in favor of males. A slight gametogenesis disturbance was also observed. These results strengthen the hypotheses about the sex-determining time window and molecular cascade governing the development of C gigas, with notably the involvement of Cg-Foxl2/Cg-Foxl2os in the very early steps. They also suggest an influence of temperature on the oyster's sex determination which, associated to genetic control, would induce a mixed sex determination system (GSD +TSD). (C) 2013 Elsevier Inc. All rights reserved.
Comparative Biochemistry And Physiology A-molecular & Integrative Physiology (1095-6433) (Elsevier Science Inc), 2013-05 , Vol. 165 , N. 1 , P. 61-69

Droits : 2013 Elsevier Inc. All rights reserved
http://archimer.ifremer.fr/doc/00136/24767/22874.pdf
DOI:10.1016/j.cbpa.2013.02.007
http://archimer.ifremer.fr/doc/00136/24767/

Éditeur(s) : HAL CCSD
Résumé : Macrophages (MΦ), well-known to play a key role in immune response, also respond to environmental toxic chemicals such as diesel exhaust particles (DEP), an air pollutant recently classified as carcinogenic to humans. MΦ are heterogeneous and plastic cells which activate according to their microenvironment into either an M1 subtype (so called classically activated or pro-inflammatory) under IFNγ and LPS stimulation or an M2 subtype (so called alternatively activated or anti-inflammatory) under IL-4 and/or IL-13 stimulation. However, potential effects of DEPs on M1/M2 MΦ polarization remain poorly documented. First, we characterized the expression marker of in vitro M-CSF-differentiated MΦ from human monocytes and activated into the M1 or M2 subtypes. Our main results show that M-CSF-generated MΦ considered as anti-inflammatory are actually able to switch to an M1 phenotype after IFNγ/LPS stimulation. Furthermore, the markers identified in this study were used to assess the impact of organic extracts of DEP (DEPe) on MΦ polarization and more generally on their physiology. DEPe alter some M1 and M2 markers expressed by polarized MΦ, without causing the overall inhibition of the M1 and M2 polarization process or the switch to a different phenotype. This phenotype alteration is associated with a decrease in the LPS-dependent inflammatory response in M1 MΦ and the chemotactic capacities in M2 MΦ. DEPe decrease the secretion of some cytokines and chemokines such as IL-6, IL-12p40 and CCL18 via AhR and/or Nrf2 activation. At the same time, we show that M1 and M2 MΦ in response to DEPe are able to secrete a sufficient level of a pro-fibrotic growth factor, the platelet derived growth factor B (PDGF-B) via AhR activation, leading to stimulation of lung fibroblast proliferation. Finally, these works show that DEPe have immunotoxic properties with regards to the physiology of human in vitro polarized MΦ. This immunotoxicity may then contribute to the deleterious effects of these urban environmental contaminants on human health.
Les macrophages (MΦ), des cellules clefs de la réponse immunitaire peuvent répondre à des contaminants environnementaux comme les particules diesel (DEP), des polluants atmosphériques récemment classés cancérigènes pour l'Homme. Les MΦ sont des cellules hétérogènes et plastiques qui s'activent en fonction de leur microenvironnement soit en MΦ M1 (dits classiquement activés ou pro-inflammatoires) sous l'effet de l'INFγ et du LPS soit en MΦ M2 (dits alternativement activés ou réparateurs) sous l'effet de l'IL-4 et/ou de l'IL-13. Les effets des DEP sur la polarisation M1/M2 des MΦ restent peu documentés. Nous avons dans un premier temps caractérisé l'expression des marqueurs des MΦ différenciés in vitro en présence de M-CSF à partir de monocytes humains et polarisés en sous-type M1 ou M2. Nos principaux résultats montrent que les MΦ différenciés au M-CSF considérés comme des MΦ anti-inflammatoires, sont en réalité capables de s'activer vers un phénotype M1 après une stimulation au LPS/IFNγ. De plus, les marqueurs mis en évidence au cours de ce travail ont permis d'évaluer l'impact d'extraits organiques de DEP (DEPe) sur la polarisation des MΦ et plus généralement sur leur physiologie. Les DEPe altèrent l'expression de certains marqueurs M1 et M2 des MΦ, sans toutefois provoquer d'inhibition globale des processus de polarisation M1 et M2 ou de transition d'un phénotype vers un autre. Cette altération du phénotype est associée à une diminution de la réponse inflammatoire LPS-dépendante dans les MΦ M1 et des capacités chimiotactiques des MΦ M2. Les DEPe diminuent la sécrétion de certaines cytokines et chimiokines comme l'IL-6, l'IL-12p40 et le CCL18 via l'activation d'AhR et/ou de Nrf2. Parallèlement, nous montrons que les MΦ M1 et M2 exposés aux DEPe sécrètent le platelet deried growth factor B (PDGF-B), un facteur de croissance profibrosant, via l'activation d'AhR en quantité suffisante pour stimuler la prolifération de fibroblastes pulmonaires. Au total, ces travaux démontrent que les DEP possèdent des propriétés immunotoxiques vis-à-vis de la physiologie des macrophages humains polarisés in vitro. Cette immunotoxicité pourrait participer aux effets délétères de ces contaminants environnementaux urbains sur la santé humaine.
https://tel.archives-ouvertes.fr/tel-01188679

NNT : 2015REN1S011
tel-01188679
https://tel.archives-ouvertes.fr/tel-01188679
https://tel.archives-ouvertes.fr/tel-01188679/document
https://tel.archives-ouvertes.fr/tel-01188679/file/JAGUIN_Marie.pdf

Éditeur(s) : HAL CCSD Wiley-Blackwell
Résumé : International audience
The Alboran Domain, situated at the western end of the Mediterranean subductionsystem, is characterized by the Ronda Peridotites, one of the world largest exposures of subcontinental mantle. Using U-Pb (LA-ICP-MS) and Ar-Ar dating, we precisely dated twotectonic events associated with the Tertiary exhumation of the Ronda Peridotites. First,shearing along the Crust-Mantle Extensional Shear Zone caused, at ca. 22.5 Ma, mantleexhumation, local partial melting in the deep crust and coeval cooling in the upper crust.Second, the Ronda Peridotites Thrust triggered the final crustal emplacement of theperidotites onto the continental crust at ca. 21 Ma, as testified by granitic intrusions in thethrust hanging-wall. The tectonic evolution of the western Alboran Domain is thereforecharacterized by a fast switch from a continental lithosphere extension in a backarc setting,with sub-continental mantle exhumation, to a rift inversion by thrusting driven by shorteningof the subduction upper plate
ISSN: 0954-4879

insu-01441962
https://hal-insu.archives-ouvertes.fr/insu-01441962
https://hal-insu.archives-ouvertes.fr/insu-01441962/document
https://hal-insu.archives-ouvertes.fr/insu-01441962/file/Frasca-TerraNova-2017.pdf
DOI : 10.1111/ter.12255

Éditeur(s) : HAL CCSD
Résumé : Ce document de synthèse retrace les différents travaux menés depuis la soutenance de ma thèse en 2003 en STAPS à l’université des Antilles et de la Guyane. Parti de l’étude de la place et des effets du créole en éducation physique et sportive en Guadeloupe, mon recrutement comme maître de conférences à l’IUFM de Guadeloupe et mon rattachement au CRREF (laboratoire en Science de l’éducation) m’ont amené à élargir mon champ d’étude à d’autres langues, à différentes disciplines scolaires et à plusieurs territoires d’Outre-mer français. Mon questionnement du passage d’une langue à une autre entre les différentes acteurs du système éducatif en situation d’enseignement, non pas dans une dimension strictement linguistique, mais selon les relations que ces contacts de langues permettent de développer sur un plan pédagogique et didactique, m’ont conduit à m'intéresser plus précisément aux formes et aux fonctions des alternances et mélanges codiques au cours des interactions didactiques en contexte multilingue. L’angle d’approche privilégié n’est donc pas seulement de décrire la manière dont les personnes co-construisent des savoirs en passant d’une langue à une autre, mais aussi d’identifier les rôles et les effets de ces alternances et mélanges codiques sur les processus d’enseignement-apprentissage. L’objectif est, d’une part, de produire des connaissances sur les pratiques langagières réelles dans l’enseignement aux Antilles et en Guyane françaises, et d’autre part, d’expérimenter des dispositifs d’enseignement bi-plurilingue et de proposer des pistes de réflexion sur la gestion du plurilinguisme en contexte didactique multilingue. Cette réflexion pose de la sorte constamment la double question de la place et de la fonction des langues au cours des interactions didactiques aux Antilles et en Guyane françaises. Ainsi, mes recherches se sont organisées selon deux axes : le premier concerne une étude descriptive et compréhensive des phénomènes d’alternances et de mélanges des langues au cours des interactions entre enseignants et élèves en situation d’enseignement en Guadeloupe, à Saint-Martin et en Guyane française, le second est une analyse des effets de ces passages alternés ou mélangés d’une langue à une autre sur les processus d’enseignement-apprentissage en contexte multilingue. Partant de ces deux axes étroitement articulés, je propose une approche didactique contextuelle du plurilinguisme en éducation et en formation en Outre-mer français qui fait appel à la fois aux sciences du langage et aux sciences de l’éducation. À l’issue de cette synthèse, certaines perspectives de recherche portant sur l’alternance et le mélange codiques au cours des interactions seront présentées en élargissant mon champ d’étude à des dispositifs scolaires spécifiques (accompagnement spécialisé, classes bilingues), à des situations éducatives hors du champs scolaire (éducation thérapeutique, médiation scientifique), ainsi qu’à des contextes informels (langage SMS, conversations en famille).
https://hal.univ-antilles.fr/tel-01612728

Droits : info:eu-repo/semantics/OpenAccess
tel-01612728
https://hal.univ-antilles.fr/tel-01612728
https://hal.univ-antilles.fr/tel-01612728/document
https://hal.univ-antilles.fr/tel-01612728/file/Vol%201%20-%20HDR%20Anciaux.pdf

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
We investigate the timing of end of motion along the South Tibet Detachment System (STDS), a major normal fault system that runs parallel to the Himalayan range for more than 1500 km. Near Dinggye (similar to 28 degrees 10'N, 87 degrees 40'E), the STD dips similar to 10 +/- 5 degrees to the North and separates Paleozoic Tethyan series from Upper Himalayan Crystalline Series (UHCS). Immediately below the STD, the UHCS is highly deformed in the STD shear zone, lineations trend NNE and the shear senses are top to the NE. In micaschist, the P-T path constrained by pseudosection and garnet chemistry, shows successive metamorphic conditions of similar to 0.6 GPa and similar to 550 degrees C and 0.5 GPa and 625 degrees C. U/Pb dating of monazites and zircons in deformed and undeformed leucogranites suggests that ductile deformation lasted until at least similar to 16 Ma but ended prior to similar to 15 Ma in the STD shear zone similar to 100 m below the detachment. Ar/Ar micas ages in the footwall span between similar to 14.6 and 13.6 Ma, indicating rapid cooling down to similar to 320 degrees C, and suggesting persistence of normal faulting, at that time. The STDS is cut and offset by the N-S trending Dinggye active normal fault which initiated prior to 11 Ma thus providing a minimum bound for the end of STDS motion. These data are interpreted as reflecting 0.3 GPa (11 km) to 0.6 GPa (22 km) of exhumation along the STDS starting prior to similar to 16 Ma, ending between 13.6 and 11 Ma. The 1000 km long stretch of the STDS east of the Gurla Mandata probably stopped almost synchronously between 13 and 11 Ma ago, coevally with a sudden switch from NNE-SSW to E-W extension at the top of the accretionary prism, with a jump of the major thrust from the lower Main Central Thrust (MCTI) to the Main Boundary Thrust (MBT), and with a change in the India and Asia convergence direction. This synchronism is probably better explained in the frame of a thrust wedge or thrust system model than a lower channel flow model. West of the Gurla Mandata the STDS appears to stop 5 to 3 Ma earlier, possibly related to local interactions with the Karakorum fault in a way that needs to be understood.
ISSN: 0012-821X

hal-00475652
https://hal.archives-ouvertes.fr/hal-00475652
DOI : 10.1016/j.epsl.2009.12.035

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
The development of inflammatory granulomas around infected Kupffer cells is necessary for hepatic parasite clearance during visceral leishmaniasis. Invariant NKT (iNKT) cells are predominant T cells in the mouse liver and can synthesize large quantities of IL-4 and IFN-γ, two cytokines involved in granuloma formation. This study analyzed the role of iNKT cells in the hepatic immune response during Leishmania donovani infection, using a murine model of wild-type (WT) and iNKT cell-deficient (Jα18⁻/⁻) C57BL/6 mice sacrificed 15, 30 or 60 days post-infection. We recorded hepatic parasite loads, cytokine expression, and analyzed granulomatous response by immunohistochemistry and hepatic immune cell infiltration by flow cytometry. Whereas WT animals rapidly controlled the infection and developed an inflammatory response associated with a massive influx of iNKT cells observed by flow cytometry, Jα18⁻/⁻ mice had significantly higher parasitic loads on all time points. This lack of control of parasite burden was associated with a delay in granuloma maturation (28.1% of large granulomas at day 60 versus 50.7% in WT). Cytokine transcriptome analysis showed that mRNA of 90/101 genes encoding chemokines, cytokines and their receptors, was underexpressed in Jα18⁻/⁻ mice. Detection of IL-4 and TNF-α by ELISA in liver extracts was also significantly lower in Jα18⁻/⁻ mice. Consistent with flow cytometry analysis, cytokinome profile in WT mice showed a bias of expression towards T cell-chemoattractant chemokines on D15, and displayed a switch towards expression of granulocytes and/or monocytes -chemoattractant chemokines on D60. In Jα18⁻/⁻ mice, the significantly lower expression of CXCL5, MIP-2 and CCL2 mRNA was correlated with a defect in myeloperoxidase positive-cell attraction observed by immunohistochemistry and with a lower granulocyte and monocyte infiltration in the liver, as shown by flow cytometry. These data indicate that iNKT cells play a role in early and sustained pro-inflammatory cytokine response warranting efficient organization of hepatic granulomas and parasite clearance.
ISSN: 1932-6203

hal-00696897
https://hal.archives-ouvertes.fr/hal-00696897
https://hal.archives-ouvertes.fr/hal-00696897/document
https://hal.archives-ouvertes.fr/hal-00696897/file/Invariant_NKT_Cells_Drive-accepted.pdf
DOI : 10.1371/journal.pone.0033413

Éditeur(s) : HAL CCSD
Résumé : International audience
The strength of the lithospheric mantle controls the mode of lithosphere deformation: the presence or absence ofa high strength brittle mantle respectively leads to localized or distributed rifting. However, first order geophysicaldata question the existence of such a brittle mantle. Here we use 2-D finite-element large strain modelling toquantify the impact of a ductile localizing mantle – instead of brittle – in triggering continental rifting. As a novelty,the mantle rheology considers the effect of grain boundary sliding during strain-induced grain size reduction,which may promote a significant strength drop and subsequent strain localization at low mantle temperature (<700-800°C). Our results reveal that such ductile localizing mantle implies varying modes of continental rifting thatmainly depend on both the amount of weakening in the ductile mantle and the strength of the lower ductile crust. Amedium to strong lower crust implies coupling between the upper crust and ductile localizing mantle, yielding tonarrow continental rifting. In contrast, a weak lower crust implies decoupling between the upper crust and ductilelocalizing mantle, giving rise to a switch from distributed faulting at incipient strain to localized faulting at largestrain. Ductile strain localization in the lithospheric mantle is therefore sufficient to trigger continental rifting,although a critical amount of weakening is required. Such ductile localizing mantle provides a relevant geologicaland mechanical alternative to the brittle mantle. It moreover provides a wider variety of modes of upper crustalfaulting that are commonly observed in nature.
EGU General Assembly 2014
Vienne, Austria

insu-01565161
https://hal-insu.archives-ouvertes.fr/insu-01565161

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Subduction infancy corresponds to the first few million years following subduction initiation, when slabs start their descent into the mantle. It coincides with the transient (yet systematic) transfer of material from the top of the slab to the upper plate, as witnessed by metamorphic soles welded beneath obducted ophiolites. Combining structure–lithology–pressure–temperature–time data from metamorphic soles with flow laws derived from experimental rock mechanics, this study highlights two main successive rheological switches across the subduction interface (mantle wedge vs. basalts, then mantle wedge vs. sediments; at ∼800 °C and ∼600 °C, respectively), during which interplate mechanical coupling is maximized by the existence of transiently similar rheologies across the plate contact. We propose that these rheological switches hinder slab penetration and are responsible for slicing the top of the slab and welding crustal pieces (high- then low-temperature metamorphic soles) to the base of the mantle wedge during subduction infancy. This mechanism has implications for the rheological properties of the crust and mantle (and for transient episodes of accretion/exhumation of HP-LT rocks in mature subduction systems) and highlights the role of fluids in enabling subduction to overcome the early resistance to slab penetration.
ISSN: 0012-821X

hal-01383368
http://hal.upmc.fr/hal-01383368
http://hal.upmc.fr/hal-01383368/document
http://hal.upmc.fr/hal-01383368/file/Agard_2016_Plate_interface.pdf
DOI : 10.1016/j.epsl.2016.06.054

Éditeur(s) : HAL CCSD
Résumé : International audience
A long standing debate in biochemistry is to determine whether the conformational changes observed during biomolecular interactions proceed through conformational selection (of preexisting isoforms) or induced fit (ligand-induced 3D reshaping). The latter mechanism had been invoked in certain circumstances, for example to explain the non-Michaelian activity of monomeric enzymes like glucokinase. But the relative importance of induced fit has been recently depreciated in favor of conformational selection, assumed to be always sufficient, predominant in general and in particular for glucokinase. The relative contributions of conformational selection and induced fit are reconsidered here in and out of equilibrium, in the light of earlier concepts such as the cyclic equilibrium rule and the turning wheel of Wyman, using single molecule state probability, one-way fluxes and net fluxes. The conditions for a switch from conformational selection to induced fit at a given ligand concentration are explicitly determined. Out of equilibrium, the inspection of the enzyme states circuit shows that conformational selection alone would give a Michaelian reaction rate but not the established nonlinear behaviour of glucokinase. Moreover, when induced fit and conformational selection coexist and allow kinetic cooperativity, the net flux emerging in the linkage cycle necessarily corresponds to the induced fit path. © 2016 Elsevier B.V. and Société Française de Biochimie et Biologie Molé
Biochimie

hal-01367150
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01367150
DOI : 10.1016/j.biochi.2016.06.012

Éditeur(s) : HAL CCSD
Résumé : National audience
Objectives To define the different stages of spontaneous labour. To determine the indications, modalities of use and the effects of administering synthetic oxytocin. And to describe undesirable maternal and perinatal outcomes associated with the use of synthetic oxytocin. Method A systematic review was carried out by searching Medline database and websites of obstetrics learned societies until March 2016. Results The 1st stage of labor is divided in a latence phase and an active phase, which switch at 5 cm of cervical dilatation. Rate of cervical dilatation is considered as abnormal below 1 cm per 4 hour during the first part of the active phase, and blow 1 cm per 2 hours above 7 cm of dilatation. During the latent phase of the first stage of labor, i.e. before 5 cm of cervical dilatation, it is recommended that an amniotomy not be performed routinely and not to use oxytocin systematically. It is not recommended to expect the active phase of labor to start the epidural analgesia if patient requires it. If early epidural analgesia was performed, the administration of oxytocin must not be systematic. If dystocia during the active phase, an amniotomy is recommended in first-line treatment. In the absence of an improvement within an hour, oxytocin should be administrating. However, in the case of an extension of the second stage beyond 2 hours, it is recommended to administer oxytocin to correct a lack of progress of the presentation. If dynamic dystocia, it is recommended to start initial doses of oxytocin at 2 mUI/min, to respect at least 30 min intervals between increases in oxytocin doses delivered, and to increase oxytocin doses by 2 mUI/min intervals without surpassing a maximum IV flow rate of 20 mUI/min. The reported maternal adverse effects concern uterine hyper-stimulation, uterine rupture and postpartum haemorrhage, and those of neonatal adverse effects concern foetal heart rate anomalies associated with uterine hyper-stimulation, neonatal morbidity and mortality, neonatal jaundice, weak suck/poor breastfeeding latch and autism. Conclusion The widespread use of oxytocin during spontaneous labour must not be considered as simply another inoffensive prescription without any possible deleterious consequences for mother or foetus. Conditions for administering the oxytocin must therefore respect medical protocols. Indications and patient consent have to be report in the medical file. © 2016 Elsevier Masson SAS
Revue Sage - Femme

hal-01467543
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01467543
DOI : 10.1016/j.sagf.2016.11.006

Éditeur(s) : HAL CCSD Humana Press
Résumé : International audience
The sodium-proton exchanger 1 (NHE-1) is a membrane transporter that exchanges Na(+) for H(+) ion across the membrane of eukaryotic cells. It is cooperatively activated by intracellular protons, and this allosteric regulation is modulated by the biophysical properties of the plasma membrane and related lipid environment. Consequently, NHE-1 is a mechanosensitive transporter that responds to osmotic pressure, and changes in membrane composition. The purpose of this study was to develop the relationship between membrane surface tension, and the allosteric balance of a mechanosensitive transporter such as NHE-1. In eukaryotes, the asymmetric composition of membrane leaflets results in a difference in surface tensions that is involved in the creation of a reservoir of intracellular vesicles and membrane buds contributing to buffer mechanical constraints. Therefore, we took this phenomenon into account in this study and developed a set of relations between the mean surface tension, membrane asymmetry, fluid phase endocytosis and the allosteric equilibrium constant of the transporter. We then used the experimental data published on the effects of osmotic pressure and membrane modification on the NHE-1 allosteric constant to fit these equations. We show here that NHE-1 mechanosensitivity is more based on its high sensitivity towards the asymmetry between the bilayer leaflets compared to mean global membrane tension. This compliance to membrane asymmetry is physiologically relevant as with their slower transport rates than ion channels, transporters cannot respond as high pressure-high conductance fast-gating emergency valves.
ISSN: 1085-9195

inserm-00871709
http://www.hal.inserm.fr/inserm-00871709
http://www.hal.inserm.fr/inserm-00871709/document
http://www.hal.inserm.fr/inserm-00871709/file/art_3A10.1007_2Fs12013-012-9340-7.pdf
DOI : 10.1007/s12013-012-9340-7

Éditeur(s) : HAL CCSD
Résumé : High Pressure - Low Temperature (HP-LT) rocks testify for burying and exhumation of crustal material in subduction zones. Their complete exhumation is the result of processes acting during (syn-orogenic) and after (post-orogenic) subduction is active, the latter partly obliterating the first. In the Aegean domain, the Attic-Cycladic Blueschist unit (ACBU) is a HP-LT unit exhumed in metamorphic core complexes (MCCs) in the back-arc domain of the Hellenic subduction zone. This study is an attempt to distinguish features related to syn-orogenic exhumation processes responsible for the first stages of exhumation This syn-orogenic "message" has to be read through the post-convergence structural and thermal overprint that accompanied the formation of the MCCs. Particularly, the geometry, the timing and the amount of the syn-orogenic exhumation has to be determined. We investigate these features with coupled field, metamorphic petrology and radiochronology studies First, based on observations on Ios (southern Cyclades), it has recently been proposed that syn-orogenic exhumation of the ACBU was accommodated by a basal thrust over the Cycladic Basement (CB) [Huet, et al., 2009]. The peak conditions, deduced from pseudosections calculation for the Ios main lithologies, are 500 °C-19 kbar for the ACBU and 550 °C-16 kbar for the CB. Exhumation until 400 °C-8 kbar is considered as syn-orogenic. Second, phengites populations, single grains and in situ 40Ar-39Ar geochronology has been carried out on samples from Tinos and Andros (northern Cyclades), Syros (central Cyclades) and Ios. The results gather in several clusters: 50-55 Ma, 40-45 Ma, 30-35 Ma, and 22-26 Ma. Based on these new P-T-t data and a synthesis of published data, we are able to refine the geometry and the timing of the exhumation of the ACBU. Data from the whole Cyclades exhibit little differences in ages and P-T conditions for the successive stages of exhumation. The peak of pressure (500±50 °C-18±1 kbar) has been reached at 50-55 Ma from Tinos to Ios. The onset of the exhumation occurred at 40-45 Ma in blueschist facies conditions, between a thrust at their bottom and a detachment at their top. The following decompression was accompanied by cooling until 30-35 Ma (400±50 °C-8±1 kbar). At that time, the boundary conditions switched to extension. Finally, we propose a model for the exhumation of HP-LT units accounting for these data. We also consider the rheological implications of the syn-orogenic structuration of the Aegean wedge on the post-orogenic evolution. B. Huet, L. Labrousse, and L. Jolivet [2009] Thrust or detachment? Exhumation processes in the Aegean: Insight from a field study on Ios (Cyclades, Greece), Tectonics, 28, 3, doi:10.1029/2008TC002397.
EGU General Assembly
Vienne, Austria

insu-00839054
https://hal-insu.archives-ouvertes.fr/insu-00839054
BIBCODE : 2010EGUGA..1214098H

Éditeur(s) : HAL CCSD Oxford University Press (OUP)
Résumé : International audience
The nature of factors governing the tempo and mode of protein evolution is a fundamental issue in evolutionary biology. Specifically, whether or not interactions between different sites, or epistasis, are important in directing the course of evolution became one of the central questions. Several recent reports have scrutinized patterns of long-term protein evolution claiming them to be compatible only with an epistatic fitness landscape. However, these claims have not yet been substantiated with a formal model of protein evolution. Here, we formulate a simple covarion-like model of protein evolution focusing on the rate at which the fitness impact of amino acids at a site changes with time. We then apply the model to the data on convergent and divergent protein evolution to test whether or not the incorporation of epistatic interactions is necessary to explain the data. We find that convergent evolution cannot be explained without the incorporation of epistasis and the rate at which an amino acid state switches from being acceptable at a site to being deleterious is faster than the rate of amino acid substitution. Specifically, for proteins that have persisted in modern prokaryotic organisms since the last universal common ancestor for one amino acid substitution approximately ten amino acid states switch from being accessible to being deleterious, or vice versa. Thus, molecular evolution can only be perceived in the context of rapid turnover of which amino acids are available for evolution.
ISSN: 0737-4038

hal-01544755
https://hal.archives-ouvertes.fr/hal-01544755
DOI : 10.1093/molbev/msu318

Éditeur(s) : HAL CCSD
Résumé : International audience
Abstract : Since 2011, the organization of linguistic education for foreigners has changed in France. Now, the FLI concept controls the integration of foreigners in the french society by a transmission of french language and republican values. Our paper is about the questions coming from the West Indies context, specifically in Guadeloupe, and it is looking at the educational matters closed to Haitians natives' people. We are asking questions about the code switching phenomena and are trying to find, out of the blue, how some contextual specific experiments can help the students in being proud of their culture and in changing their vision of scholar and learning system. Feedback from those oral original sessions are aimed at offering solutions to establish a suitable teaching method named FLR.
Depuis 2011, la loi française a renforcé sa politique linguistique en faveur d'une intégration des migrants, mettant en place l'enseignement du français langue d'intégration (FLI). Notre contribution considère dans ce cadre épistémologique les particularités sociolinguistiques et migratoires du territoire de la Guadeloupe et s'intéresse à une didactique contextualisée, notamment en ce qui concerne le public des migrants venus d'Haïti. Les effets de contexte sont interrogés à travers une analyse du dispositif de formation, des postures des formateurs, des écarts observés entre objectifs attendus et réalisés et de l'influence des représentations des apprenants. Nous interrogeons le rôle du contact entre les langues créoles et le français dans les apprentissages. Cette note propose également un projet de remédiation pédagogique adapté aux difficultés relevées et pose les bases d'une approche didactique idoine caractérisée par un travail centré sur la réassurance affective et culturelle.Mots clés : Insécurité linguistique, diglossie, créole haïtien, confiance en soi, langue vernaculaire, langue véhiculaire, outils pédagogiques, didactique contextualisée, didactique sociolinguistique, andragogie, remédiation pédagogique, réassurance.
Troubles du langage, Langue d'enseignement et rendement scolaire. Essai de diagnostic du système éducatif haïtien dans le département de l'Artibonite, Ouvrage collectif (Coordination : Rochambeau LAINY), 2016, L'Harmattan, Paris , 320 pages.

hal-01673268
https://hal.univ-antilles.fr/hal-01673268
https://hal.univ-antilles.fr/hal-01673268/document
https://hal.univ-antilles.fr/hal-01673268/file/FINAL%20ARTICLE%20Fr%C3%A9d%C3%A9ric%20Beaubrun%20communication%20-%20Colloque%20%20Ha%C3%AFti%20pathologies%20du%20langage%20et%20rendement%20scolaire.pdf

Éditeur(s) : HAL CCSD Elsevier Masson
Résumé : International audience
The seismological study of recent seismic crises near Oleron Island confirms the coexistence of an extensional deformation and a transtensive regime in the Atlantic margin of France, which is different from the general western European stress field corresponding to a strike-slip regime. We argue that the switch of the principal stress axes σ1/σ2 in a NW-SE vertical plane is linked with the existence of crustal heterogeneities. Events of magnitude larger than 5 sometimes occur along the Atlantic margin of France, such as the 7 September 1972 (ML = 5.2) earthquake near Oleron island and the 30 September 2002 (ML = 5.7) Hennebont event in Brittany. To test the mechanism of local strain localization, we model the deformation of the hypocentral area of the Hennebont earthquake using a 3D thermo-mechanical finite element code. We conclude that the occurrence of moderate earthquakes located in limited parts of the Hercynian shear zones (as the often reactivated swarms near Oleron) could be due to local reactivation of pre-existing faults. These sporadic seismic ruptures are favoured by stress concentration due to rheological heterogeneities.
ISSN: 1631-0713

hal-00936220
https://hal.archives-ouvertes.fr/hal-00936220
DOI : 10.1016/j.crte.2013.07.004

Éditeur(s) : HAL CCSD
Résumé : International audience
This article aims to explore the bilingual practices (English and French) used by students from St Martin in a collaborative situation, in order to enrich the debate on languages and knowledge. This research is based on two corpora consisting of interactions between high school pupils during their educational support sessions, and which are studied using conversational analysis; the study uses this combination of collaborative methods and bilingual education to model the management of linguistic resources with regard to the factual knowledge and practical skills brought into play during the interaction. The challenge of this study is therefore to establish what is involved, and under which conditions and through which mechanisms the interactions between two languages (English and French) may contribute to the construction of cognitive learning skills.
Francisola : : revue indonésienne de la langue et de la littérature françaises

hal-01532983
https://hal.archives-ouvertes.fr/hal-01532983

Éditeur(s) : HAL CCSD American Society for Microbiology
Résumé : International audience
Here we report in a human, a renal transplant patient, the first disseminated infection with Nocardia cerradoensis, isolated after a brain biopsy. Species identification was based on 16S rRNA, gyrB, and hsp65 gene analyses. Antibiotic treatment was successful by combining carbapenems and aminoglycosides and then switching to oral trimethoprim-sulfamethoxazole.
ISSN: 0095-1137

hal-01130428
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01130428
DOI : 10.1128/JCM.02979-14
PUBMED : 25568436

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The quasi-equilibrium approximation is acceptable when molecular interactions are fast enough compared to circuit dynamics, but is no longer allowed when cellular activities are governed by rare events. A typical example is the lactose operon (lac), one of the most famous paradigms of transcription regulation, for which several theories still coexist to describe its behaviors. The lac system is generally analyzed by using equilibrium constants, contradicting single-event hypotheses long suggested by Novick and Weiner (1957). Enzyme induction as an all-or-none phenomenon. Proc. Natl. Acad. Sci. USA 43, 553-566) and recently refined in the study of (Choi et al., 2008. A stochastic single-molecule event triggers phenotype switching of a bacterial cell. Science 322, 442-446). In the present report, a lac repressor (LacI)-mediated DNA immunoprecipitation experiment reveals that the natural LacI-lac DNA complex built in vivo is extremely tight and long-lived compared to the time scale of lac expression dynamics, which could functionally disconnect the abortive expression bursts and forbid using the standard modes of lac bistability. As alternatives, purely kinetic mechanisms are examined for their capacity to restrict induction through: (i) widely scattered derepression related to the arrival time variance of a predominantly backward asymmetric random walk and (ii) an induction threshold arising in a single window of derepression without recourse to nonlinear multimeric binding and Hill functions. Considering the complete disengagement of the lac repressor from the lac promoter as the probabilistic consequence of a transient stepwise mechanism, is sufficient to explain the sigmoidal lac responses as functions of time and of inducer concentration. This sigmoidal shape can be misleadingly interpreted as a phenomenon of equilibrium cooperativity classically used to explain bistability, but which has been reported to be weak in this system.
ISSN: 0022-5193

inserm-00818506
http://www.hal.inserm.fr/inserm-00818506
http://www.hal.inserm.fr/inserm-00818506/document
http://www.hal.inserm.fr/inserm-00818506/file/LacI-TeX.pdf
ARXIV : 1312.5566