Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The mycotoxin alternariol (AOH), a frequent contaminant in fruit and grain, is known to induce cellular stress responses such as reactive oxygen production, DNA damage and cell cycle arrest. Cellular stress is often connected to autophagy, and we employed the RAW264.7 macrophage model to test the hypothesis that AOH induces autophagy. Indeed, AOH treatment led to a massive increase in acidic vacuoles often observed upon autophagy induction. Moreover, expression of the autophagy marker LC3 was markedly increased and there was a strong accumulation of LC3-positive puncta. Increased autophagic activity was verified biochemically by measuring the degradation rate of long-lived proteins. Furthermore, AOH induced expression of Sestrin2 and phosphorylation of AMPK as well as reduced phosphorylation of mTOR and S6 kinase, common mediators of signaling pathways involved in autophagy. Transmission electron microscopy analyzes of AOH treated cells not only clearly displayed structures associated with autophagy such as autophagosomes and autolysosomes, but also the appearance of lamellar bodies. Prolonged AOH treatment resulted in changed cell morphology from round into more star-shaped as well as increased β-galactosidase activity. This suggests that the cells eventually entered senescence. In conclusion, our data identify here AOH as an inducer of both autophagy and senescence. These effects are suggested to be to be linked to AOH-induced DSB (via a reported effect on topoisomerase activity), resulting in an activation of p53 and the Sestrin2-AMPK-mTOR-S6K signaling pathway.
ISSN: 0300-483X

hal-01117627
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01117627
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01117627/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01117627/file/Autophagy%20and%20senescence_accepted.pdf
PUBMED : 25456271

Éditeur(s) : Springer
Résumé : We present the global general circulation model IPSL-CM5 developed to study the long-term response of the climate system to natural and anthropogenic forcings as part of the 5th Phase of the Coupled Model Intercomparison Project (CMIP5). This model includes an interactive carbon cycle, a representation of tropospheric and stratospheric chemistry, and a comprehensive representation of aerosols. As it represents the principal dynamical, physical, and bio-geochemical processes relevant to the climate system, it may be referred to as an Earth System Model. However, the IPSL-CM5 model may be used in a multitude of configurations associated with different boundary conditions and with a range of complexities in terms of processes and interactions. This paper presents an overview of the different model components and explains how they were coupled and used to simulate historical climate changes over the past 150 years and different scenarios of future climate change. A single version of the IPSL-CM5 model (IPSL-CM5A-LR) was used to provide climate projections associated with different socio-economic scenarios, including the different Representative Concentration Pathways considered by CMIP5 and several scenarios from the Special Report on Emission Scenarios considered by CMIP3. Results suggest that the magnitude of global warming projections primarily depends on the socio-economic scenario considered, that there is potential for an aggressive mitigation policy to limit global warming to about two degrees, and that the behavior of some components of the climate system such as the Arctic sea ice and the Atlantic Meridional Overturning Circulation may change drastically by the end of the twenty-first century in the case of a no climate policy scenario. Although the magnitude of regional temperature and precipitation changes depends fairly linearly on the magnitude of the projected global warming (and thus on the scenario considered), the geographical pattern of these changes is strikingly similar for the different scenarios. The representation of atmospheric physical processes in the model is shown to strongly influence the simulated climate variability and both the magnitude and pattern of the projected climate changes.
Climate Dynamics (0930-7575) (Springer), 2013-05 , Vol. 40 , N. 9-10 , P. 2123-2165

Droits : The Author(s) 2013. This article is published with open access at Springerlink.com
http://archimer.ifremer.fr/doc/00138/24966/23079.pdf
DOI:10.1007/s00382-012-1636-1
http://archimer.ifremer.fr/doc/00138/24966/

Résumé : Le cycle biologique du principal stock de crevettes pénéïdes (Penaeus subtilis) exploité sur le plateau continental guyanais est court (18 mois environ). Les variabilités intra et inter annuelles de l'abondance des individus appartenant aux différentes composantes des premières phases du cycle (larves, post-larves, juvéniles) sont considérées comme très fortes, ce phénomène étant exacerbé par le double changement de milieu au cours du cycle, passage d'un habitat en eau salée à celui en eau douce, puis retour au premier. La pêcherie de la flottille crevettière guyanaise est ainsi basée sur un stock au renouvellement rapide et variable, aussi l'optimisation de sa gestion implique une meilleure compréhension des mécanismes de recrutement des crevettes et notamment leur facteurs de variation. Ainsi, depuis octobre 1992 une étude est conduite pour analyser ces mécanismes de recrutement. Elle s'intègre dans un programme de coopération régionale entre l'IFREMER et le Ministère de l'Agriculture, de l'Elevage et des Pêches du Surinam financé par des fonds FEDER et du FIC, et elle est menée par l'IFREMER dans la Zone Economique Exclusive française et par le laboratoire du Département des pêches du Surinam sur le plateau surinamien. Le programme prévoit une série de huit campagnes en mer qui seront conduites en parallèle par chacun des deux laboratoires Français et Surinarnien sur les plateaux de Guyane (campagnes RESUBGUY) et du Surinam (campagnes RESUBSUR) afin d'analyser le phénomène de recrutement sur la plus large échelle possible d'observation (plateau guyano-surinamien). Deux campagnes annuelles ont été programmées pour chaque pays, en mai et en octobre. La périodicité de ces campagnes est fonction des résultats des travaux conduits par l'IFREMER et l'ORSTOM sur la phase pré-recrutée de Penaeus subtilis qui ont mis en évidence deux principales périodes annuelles distinctes de recrutement (avril-mai; septembre-octobre). Cette campagne est la quatrième de la série initiée en octobre 1992. L'étude n'est pas limitée à l'examen des seules captures de crevettes Penaeus subtilis, puisqu'elle incluse également l'analyse de la composition des prises accessoires des crevettiers. Les "by-catches" considérées dans ce travail sont surtout représentées par la crevette "sea-bob", Xiphopenaeus kroyeri, ainsi que par les principales espèces de poissons d'intérêt commercial (ou ayant une forte probabilité de le devenir dans un futur proche). Enfin, une attention particulière a également été portée sur les captures accidentelles de tortues marines afin d’en estimer l’importance réelle.

Droits : 1994 Ifremer
http://archimer.ifremer.fr/doc/00076/18750/16321.pdf
http://archimer.ifremer.fr/doc/00076/18750/

Éditeur(s) : Université Paul Sabatier, Toulouse III
Résumé : The marine phytoplankton in the ocean represents only less than 1% of global biomass. Phytoplankton performs half of all photosynthesis. This autotrophic biomass in ocean is then an essential element in the climate regulation through processes as carbon dioxide absorption during the photosynthesis. Therefore, we need to estimate precisely this biomass as well as the processes which affect it. Using remotely sensed data (altimetry and ocean colour) and a coupled physical/biogeochemical model (MERCATOR-OPA/NPZDDON), Rossby waves and their influence on phytoplankton biomass are specifically studied in the North Atlantic Ocean. Their features and their influences on surface chlorophyll concentrations were analysed. Through the different mechanisms identified, we estimated that these waves can induce local increases from 60% to 150% of the estimated primary production.
Même si l'océan ne représente que moins de 1% de la biomasse liée aux plantes sur la terre, il est responsable de près de la moitié de la photosynthèse nette de la biosphère. Cette biomasse est par conséquent un élément essentiel dans la régulation du climat à travers par exemple le cycle océanique du carbone. Il est donc nécessaire d'estimer correctement cette biomasse ainsi que les processus qui l'affectent. A l'aide de données satellites altimétriques et couleur de l'eau et d'un modèle couplé physique/biogéochimie (MERCATOR-OPA / NPZDDON), les ondes de Rossby et leur influence sur cette biomasse sont spécifiquement étudiées dans l'océan Atlantique Nord. Leurs propriétés et leur influence sur les concentrations en chlorophylle de surface sont analysées. Au travers des mécanismes mis en jeu identifiés, nous estimons que ces ondes peuvent entraîner une augmentation locale comprise entre 60% et 150% de la production primaire estimée.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/2005/these-2454.pdf
http://archimer.ifremer.fr/doc/00000/2454/

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
BOI1 and BOI2 are paralogs important for the actin cytoskeleton andpolar growth. BOI1 encodes a meiotic transcript isoform with an extended5-untranslated region predicted to impair protein translation. It is,however, unknown how the isoform is repressed during mitosis, and ifBoi1 is present during sporulation. By interpreting microarray data fromMATa cells, MATa/ cells, a starving MAT/ control, and a meiosis-impairedrrp6 mutant, we classified BOI1's extended isoform as earlymeiosis-specific. These results were confirmed by RNA-Sequencing, andextended by a 5-RACE assay and Northern blotting, showing that meioticcells induce the long isoform while the mitotic isoform remainsdetectable during meiosis. We provide evidence via motif predictions, anin vivo binding assay and genetic experiments that the Rpd3/Sin3/Ume6histone deacetylase complex, which represses meiotic genes duringmitosis, also prevents the induction of BOI1's 5-extended isoform inmitosis by direct binding of Ume6 to its URS1 target. Finally, we findthat Boi1 protein levels decline when cells switch from fermentation torespiration and sporulation. The histone deacetylase Rpd3 is conserved,and eukaryotic genes frequently encode transcripts with variable 5-UTRs.Our findings are therefore relevant for regulatory mechanisms involvedin the control of transcript isoforms in multi-cellular organisms.
ISSN: 0950-382X

hal-01122120
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01122120
DOI : 10.1111/mmi.12976
PUBMED : 25708805

Résumé : En Guyane comme dans l'ensemble de la région amazonienne, le risque de maladie de Chagas pour l'homme a longtemps été sous estimé du fait de l'absence de vecteur domestique et de l'existence d'un réservoir animal exclusivement sauvage. Le travail présenté répond aux besoins de compléter et d'actualiser les connaissances épidémiologiques disponibles sur la maladie de Chagas dans ce département , en précisant les modalités de circulation de Trypanosoma cruzi et les facteurs impliqués dans le cycle à l'origine des cas humains. Les données cumilées entre 2001 et 2023 représentent 971 spécimens de triatomes. Nous avons choisi de différencier les triatomes provenant des zones non habitées (forêts primaire ou secondaire) de ceux provenant de zones habitées, collectées dans les maisons à la faveur d'intrusion. Une espère, Panstrongylus geniculatus, s'est distinguée par son abondance (61,1%) et son omniprésence dans les différents types de milieux explorés. Au total, neuf espèces ont été retrouvées. En zone non habitée, avec une prédominance de P. geniculatus, P. lignarius, Rhodnius pictipes et R. robustus. L'infection des triatomes par T. cruzi a été étudiée, avec une mise en évidence d'un taux d'infection plus élevé chez les triatomes collectés à l'intérieur des habitations (53.9%) que chez ceux provenant des zones non habitées (46%). L'étude sur les mammifères sauvages a montré des taux d'infection élevés pour T. cruzi chez deux espèces : didelphis marsupialis (62.5%) et Philander opossum (35%). Cette étude a été complétée par l'analyse de la variabilité génétique de T. cruzi identifié par des techniques de génotypage réalisées sur du matériel obtenu à partir de triatomes, de mammifères sauvages et domestiques et des hommes. En zone non habitée trois groupes, TcI, TcII-TcV-TcVI et TcIII-TcIV, ont été caractérisés, avec une prédominance de TcI. Parmi les acteurs du cycle parasite, les chiens et P. geniculatus hébergent le groupe TcIII-TcIV à la différence du genre Rhodnius et des marsupiaux qui hébergent le groupe TcI. Nos résultats ont permis d'émettre un certain nombre d'hypothèses sur la circulation des génotypes de T. cruzi en Guyane
In French Guiana, as in the whole of Amazon region, the risk of Chagas disease to humans has long been underestimated due to the presence of non-domiciled triatomines and wild animal reservoir. Overall, this thesis aims at reactualizing and improving epidemiological knowledge about Chagas disease in French Guiana, by specific modalities of circulation of Trypanosoma cruzi and the factorsinvolved in the transmission cycle of the origin of human cases. Accumulated data, between 2001 and 2013, represent 971 triatomine specimens collected. We chose to differentiate triatomine collected in uninhabited areas (primary or secondary forests) and those frominhabited areas, collected in homes by intrusion. One species, Panstrongylus geniculatus, was distinguished by its abundance (61.1%) and its presence in different types of habitats investigated. A total of nine species were found in uninhabited area, with the predominance of four species: P. geniculatus, P. lignarius, Rhodnius pictipes and Eratyrus mucronatus. In inhabited area, five species of triatomine were collected, with the predominance of P. geniculatus, R. pictipes and R. robustus. The triatomine infection rate with T. cruzi has been studied, with a highlighting of higher rate of infection in triatomine collected inside houses (53.9%) than those from uninhabited area (46%). The study on wild mammals showed high T. cruzi infection rates for two species: Didelphis marsupialis (62.5%) and Philander opossum (35%).This study was completed by the analysis of the genetic variability of T. cruzi identified by genotyping techniques performed on material obtained from triatomine, wild and domestic mammals and humans. In uninhabited area, three groups$ TcI, TcII-TcV-TcVI and TcIII-TcIV have been characterized, with a predominance of TcIII-TcIV group. In inhabited area, only two groups were characterized (TcI andTcIII-TcIV), with a predominance of TcI. Among the actor’s transmission cycle of parasite, dogs and P. geniculatus were characterized by TcIII-TcIV group. Contrary to Rhodnius genus and marsupials were characterized by the TcI group. Our results have allowed issuing a number of assumptions about the circulation of T. cruzi genotypes in French Guiana

http://www.theses.fr/2013AGUY0734/document

Éditeur(s) : Elsevier
Résumé : The accumulation of nine heavy metals in fine-grained sediments from the mangrove fringed coast of French Guiana is evaluated. The dynamic features of the South American tropical coastline, from the Amazon to the Orinoco Rivers, result in mangrove sediments being alternately submitted to phases of erosion and net sedimentation a few tens of years long. This process influences the distribution of the heavy metals associated with these frequently re-mobilized deposits. Sedimentary cores and mangrove plant samples were collected, at different seasons, in various swamps characterized by different properties (content of sedimentary organic matter, distance from sea water and fresh water). The ranges of measured concentrations expressed in mu mol g(-1) were the following: Cu (0.06 to 0.61), Co (0.12 to 0.68), Pb (0.08 to 0.18), Ni (0.32 to 0.76), Cr (0.61 to 1.40), Zn (1.25 to 5.94), Mn (4.36 to 45.4) and Fe (441 to 1128). No differences were found between sediments from mangroves developing upstream and downstream of urban areas, i.e. Cayenne and Kourou. This suggests that the content of mangrove sediments in heavy metals along the coastline of French Guiana is essentially the result of the continuous alternation of accumulation and transport phases occurring upstream after departing from the Amazon watershed. The sources of this heavy metals content are thus difficult to identify. However it is well known that the alluvium produced by the natural erosion of the Amazonian soils is naturally enriched in mercury. Also, the run-off from gold mining activities is known to contribute to mercury pollution. Ranges in total Hg were between 0.15 and 2.57 nmol g(-1), with mean values close to 0.41 nmol g(-1), and were clearly correlated with total organic carbon except for some outstanding high values, which may be a result of rapid geochemical changes. Heavy metal concentrations showed variations with depth. The redox conditions and the decay processes affecting the organic matter control the cycling of iron and manganese, which in turn control the concentrations and associations of heavy metals. These preliminary results suggest that the variations in heavy metal content with depth or between mangrove areas result largely from diagenetic processes rather than changes in metal input resulting from local human activities. (c) 2005 Elsevier B.V. All rights reserved.
Marine Chemistry (0304-4203) (Elsevier), 2006 , Vol. 98 , N. 1 , P. 1-17

Droits : 2005 Elsevier B.V. All rights reserved
http://archimer.ifremer.fr/doc/2006/publication-1041.pdf
DOI:10.1016/j.marchem.2005.06.001
http://archimer.ifremer.fr/doc/00000/1041/

Éditeur(s) : Université de Bretagne Occidentale
Résumé : Study of mineral suspended particulate matter (SPM) is essential to understand ecosystem dynamics. SPM influences light penetration which is closely related to primary production and carries pollutants and nutrients within the water masses. This work aims to study near-surface mineral SPM dynamics in the English Channel using two complementary methods: remote-sensing by satellites and numerical modelling. Firstly, MODIS and MERIS satellite images processed by the IFREMER semi-analytical algorithm and describing non-algal SPM, are analysed to build three statistical models which are able to estimate near-surface SPM using simple variables, e.g., tidal coefficient, significant wave height and mean chlorophyll-a concentration. Secondly, the three-dimensional hydrosedimentary model ROMS (Regional Ocean Modeling System) is applied in the English Channel. It considers tidal forcing along open boundaries, wind stress at the sea-surface, wave-current interactions in the bottom boundary layer and realistic heterogeneous bottom sediments. Results of the more sophisticated statistical model is also used to impose SPM concentrations at open boundaries. Sensitivity tests on SPM boundary conditions show the importance of prescribing realistic sediment concentrations to improve the model predictions. Biological influences on mineral SPM are also tested using settling velocity and critical shear stress for erosion which vary with seasons. Both statistical and numerical models highlight and locate respective influences of tide, waves and biology on mineral SPM. Numerical predictions indicate that near-surface SPM is mainly composed of silts (>70%). Near-surface suspended silts come largely from seabed resuspension alongshore in the Eastern Channel and from the open boundaries of our limited-area coastal model at the West of Cotentin Peninsula and offshore. Near-surface SPM variations are investigated at semi-diurnal, neap-spring tidal cycle time scales and during a wave event. Finally, dynamics of sediments in the turbidity maximum zone around the Isle of Wight is examined depending on hydrodynamical conditions in order to distinguish the role played by advection and local erosion/settling processes in this area. Keywords: Suspended particulate matter, satellite, remote-sensing, modelling, English Channel, sediments, turbidity, tide, wave
L'étude des matières en suspension (MES) minérales est essentielle pour comprendre le fonctionnement des écosystèmes en Manche : les MES influencent la pénétration de la lumière dans la colonne d'eau, paramètre clé pour la production biologique, et sont susceptibles de transporter des polluants et nutriments. Lors de ce travail, la dynamique des MES minérales de surface en Manche est étudiée à l'aide de deux méthodes complémentaires : l'observation par satellite et la modélisation numérique tridimensionnelle. Dans un premier temps, les images satellite MODIS et MERIS, traitées par l'algorithme semi-analytique développé par l'IFREMER et représentant les MES non-algales de surface, sont analysées afin d'élaborer trois modèles statistiques permettant d'estimer la MES de surface en fonction de variables basiques telles que le coefficient de marée, la hauteur significative des vagues et la concentration moyenne en chlorophylle-a. Dans un deuxième temps, le modèle hydrosédimentaire multiclasse tridimensionnel ROMS (Regional Ocean Modeling System) est implémenté en Manche. Il prend en considération le forçage par la marée aux frontières ouvertes, la contrainte exercée par le vent à la surface de la mer, l'interaction houle-courant en couche limite de fond et l’hétérogénéité spatiale réaliste du lit sédimentaire. Les résultats du modèle statistique le plus sophistiqué sont également utilisés pour forcer la concentration en MES aux frontières ouvertes du domaine de calcul. Des tests de sensibilité sur les conditions limites montrent l'importance de considérer de manière réaliste les sédiments entrant en Manche par les frontières ouvertes lors de la modélisation numérique. L'influence de la biologie sur les MES minérales est testée en utilisant une formulation de la vitesse de chute et de la contrainte critique d'érosion variant saisonnièrement. Grâce à ces deux outils associés, les influences respectives de la marée, de la houle et de la biologie sur les MES minérales sont mises en avant et localisées en Manche. Le modèle numérique prédit que les MES de surface sont composées principalement de silts (>70%). Les silts en suspension en surface proviennent majoritairement du lit sédimentaire près des côtes en Manche orientale et des frontières ouvertes du domaine de calcul à l'ouest de la presqu'île du Cotentin et au large en Manche centrale et orientale. Les variations des MES de surface sont ensuite étudiées aux échelles des cycles de marée semi-diurnes, vive-eau/morte-eau et autour d'un épisode de houles. Enfin, l'évolution de la concentration de sédiments dans la zone de forte turbidité autour de l'île de Wight peut être analysée suivant les conditions hydrodynamiques afin d'évaluer les rôles respectifs des processus locaux d'érosion/dépot et d'advection dans la génération de ces turbidités remarquables. Mots-clés : Matière en suspension, télédétection, satellite, modélisation, Manche, sédiments, turbidité, marée, houle

Droits : 2013 UBO
http://archimer.ifremer.fr/doc/00157/26783/24884.pdf
http://archimer.ifremer.fr/doc/00157/26783/

Éditeur(s) : HAL CCSD
Résumé : International audience
The geology of the North Pyrenean Zone in the central Pyrenees allows for the observation in the field of theentire section of the Pyrenean rift, from the mantle to the crust and the Mesozoic cover (pre, syn and post rift).The good knowledge we have of the pre-Alpine history of the Pyrenees allows us to properly constrain the Alpinegeological evolution of the pre-Triassic rocks which record both Variscan and Alpine orogenic cycles.The mantle outcrop as kilometric to centimetric fragments of peridotite dispersed within a carbonate metamorphicbreccia. The study of peridotite serpentinisation shows several events of low-temperature serpentinisation, incontact with seawater. In some locallities, we can observe a mixture of fragments of variously serpentinizedperidotites. This suggests a tectonic context where fragments of peridotites from different structural levels weresampled more or less synchronously.The granulitic basement is characterized by a Variscan syndeformational HT event (300-280 Ma). So farwe have not found any trace of a Cretaceous HT event (> 500C). On the other hand, the basement is affectedby a regional metasomatism that began during the Jurassic and became more spatially focused with time until itwas restricted to the Pyrenean rift during the Aptien, Albian and Cenomanian. The talc-chlorite metasomatism(120-95 Ma) shows an evolution from a static toward a syn-deformation hydrothermal event, under a more or lessnormal geothermal gradient. Extensional deformation is recorded by the reworking of several inherited low-angleVariscan tectonic contacts, but also by dispersed high-angle extensional shear zones formed under greenshistconditions.The metamorphic Mesozoic cover of the basement massifs, which constitute the so-called Internal MetamorphicZone, is an allochtonous unit made of lenses of Mesozoic rocks enclosed into the breccia, whichlocally contains peridotite and basement clasts. The Mesozoic metamorphic carbonates show a first phase ofsyn-metamorphic (450-600C, P < 2 kb) ductile deformation, and subsequent phases of folding and fracturing.The datation of neoformed minerals give a 108-85 Ma time span for the metamorphism. We interpret this brecciaas an abandonment breccia which marks the emergence of the main detachment. The basal contact of the Mesozoiccover has a complex 3D geometry traced by Triassic evaporites. It corresponds to a major pre- and synorogenicpolyphased tectonic contact.All these data show a geometrically complex hyper-extended rift where the crust was not stretched under ahigh geothermal gradient but thinned by the tectonic extraction of relatively thin lenses and perhaps cut by highangle low-grade shear zones. The 3D geometry, as well as the strain records and the breccia lithologies stronglysuggest a non-cylindricity for the exhumation process, probably within a transtentional system
Geophysical Research Abstracts
Vienne, Austria

insu-01510371
https://hal-insu.archives-ouvertes.fr/insu-01510371

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 Human Kinetics
Résumé : International audience
Purpose: Postexercise alveolar-capillary membrane-diffusing capacity (DLco) often decreases in highly trained endurance athletes and seems linked to their training status. To test the hypothesis that training status influences postexercise DLco, 13 male and 2 female triathletes (20.2 ± 4.4 y old, 175.2 ± 6.7 cm tall; weight in a range of 66.6 ± 7.4 kg to 67.4 ± 7.8 kg during the 1-y study) were randomized into experimental (n = 7) and control (n = 8) groups and performed VO2max cycle tests and simulated cycle-run successions (CR) of 30 min + 20 min after 3 periods in the competitive season. Methods: Both groups were tested before (pre- HTP) and after a 30-wk high-training period (HTP) with high training volume, intensity, and frequency. The experimental group was then also tested after a 6-wk low-training period (LTP) with low training volume, intensity, and frequency, while the control group continued training according to the HTP schedule for these 6 wk. Ventilatory data were collected continuously. DLco testing was performed before and 30, 60, and 120 min after the CR trials. Results: Whatever the period or group, DLco was significantly decreased 30 min after CR, with a significantly greater decrease in the experimental group than the control group in LTP (–15.7% and –9.3% of DLco, respectively). Conclusions: Six weeks of low training volume and intensity were sufficient to reverse the effects of high training volume and intensity on the alveolar-capillary membrane after a CR succession in competitive triathletes.
ISSN: 1555-0265

hal-01163434
https://hal.univ-antilles.fr/hal-01163434

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The biogeochemistry of sulfur and carbon during early-diagenetic processes within organic-rich marine mangrove sediments was studied in the “Manche à Eau” lagoon, Guadeloupe, West Indies. These sediments are characterized by a total organic carbon content (TOC) mostly above 11 wt%, δ13CTOC below − 25‰ VPDB and C/Nmolar ratios exceeding 15. Rates of mangrove-derived organic carbon accumulation vary between ~ 200 and 400 gOC·m− 2·yr− 1, with highest rates at the shore of the lagoon. On the lagoon border, where colorless filamentous sulfur-oxidizing bacteria colonize the sediments, active sulfate reduction within the upper 20 cm, with a net removal rate of ~ 0.5 μmol·cm− 3·d− 1, is assumed to be essentially driven by organic carbon oxidation. This is expressed by relatively low apparent sulfur isotope fractionation (34εnet = − 33‰) and a gentle δ18O/δ34Ssulfate apparent slope of 0.36 ± 0.03 (2s). Further inside the lagoon, in the absence of sulfur-oxidizing bacteria, higher apparent sulfur isotope fractionation and a steeper δ18O/δ34Ssulfate slope (0.67 ± 0.20) suggest an overall lower sulfate removal rate that may be coupled to minor sulfur disproportionation. Spatial and vertical variation in sulfur cycling, reflected by oxygen and sulfur isotopic characteristics, seem to be mainly controlled by unsteady to relatively steady organic matter deposition and its reactivity. In all sediments, δ34S values of pyrite are positively correlated with the TOC/TS ratio and negatively correlated with δ13CTOC; suggesting a primary control of the quantity and quality of organic matter on the pyrite isotope records, despite potential iron-limiting conditions for the most active sites. Our results provide insights into the role of organic carbon input on sulfur cycling; stimulating sulfate reduction and in turn the presence of sulfur-oxidizing microbial mats, resulting in an intense cycling of both carbon and sulfur in these marine mangrove sediments.
ISSN: 0009-2541

hal-01507696
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01507696
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01507696/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01507696/file/Cr%C3%A9mi%C3%A8re%20et%20al.%20-%20Sulfur%20diagenesis%20under%20rapid%20accumulation%20of%20orga.pdf
DOI : 10.1016/j.chemgeo.2017.02.017

Éditeur(s) : HAL CCSD Elsevier Masson
Résumé : International audience
INTRODUCTION: Light chain deposition disease is a rare clinical entity characterized by deposition of monoclonal immunoglobulin light chains in organs. The kidneys are almost always affected, while the lung manifestations that have been reported, including nodular or diffuse disease, especially cystic lesions, are unusual. CASE REPORT: We report the case of a 60-year-old man with a diffuse infiltrative lung disease characterized by numerous apical cysts. The diagnosis of light chain deposition cystic lung disease was obtained by surgical lung biopsy. Light chain deposits in the salivary glands were the only extrapulmonary manifestation. Despite 12 chemotherapy cycles, the patient's lung function and radiological appearances worsened. CONCLUSION: This is the fourth case describing a cystic lung disease due to light chain deposition in the literature. It highlights the need for comprehensive investigations so as not to miss this rare cause of cystic lung disease, which appears to be related to a primary pulmonary lymphoproliferative disorder. The only treatment that appears to be effective is lung transplantation.
ISSN: 0761-8425

hal-00873356
https://hal.archives-ouvertes.fr/hal-00873356
https://hal.archives-ouvertes.fr/hal-00873356/document
https://hal.archives-ouvertes.fr/hal-00873356/file/DA_pots_chaines_lA_gA_res_non_amyloides_version_finale.pdf
DOI : 10.1016/j.rmr.2013.02.003

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Over the last decades, numerous studies have emphasized the role of serpentinites in the subduction zone geodynamics. Their presence and role in subduction environments are recognized through geophysical, geochemical and field observations of modern and ancient subduction zones and large amounts of geochemical database of serpentinites have been created. Here, we present a review of the geochemistry of serpentinites, based on the compilation of ~ 900 geochemical data of abyssal, mantle wedge and exhumed serpentinites after subduction. The aim was to better understand the geochemical evolution of these rocks during their subduction as well as their impact in the global geochemical cycle. When studying serpentinites, it is essential to determine their protoliths and their geological history before serpentinization. The geochemical data of serpentinites shows little mobility of compatible and rare earth elements (REE) at the scale of hand-specimen during their serpentinization. Thus, REE abundance can be used to identify the protolith for serpentinites, as well as magmatic processes such as melt/rock interactions before serpentinization. In the case of subducted serpentinites, the interpretation of trace element data is difficult due to the enrichments of light REE, independent of the nature of the protolith. We propose that enrichments are probably not related to serpentinization itself, but mostly due to (sedimentary-derived) fluid/rock interactions within the subduction channel after the serpentinization. It is also possible that the enrichment reflects the geochemical signature of the mantle protolith itself which could derive from the less refractory continental lithosphere exhumed at the ocean-continent transition. Additionally, during the last ten years, numerous analyses have been carried out, notably using in situ approaches, to better constrain the behavior of fluid-mobile elements (FME; e.g. B, Li, Cl, As, Sb, U, Th, Sr) incorporated in serpentine phases. The abundance of these elements provides information related to the fluid/rock interactions during serpentinization and the behavior of FME, from their incorporation to their gradual release during subduction. Serpentinites are considered as a reservoir of the FME in subduction zones and their role, notably on arc magma composition, is underestimated presently in the global geochemical cycle.
ISSN: 0024-4937

hal-00903601
https://hal.archives-ouvertes.fr/hal-00903601
DOI : 10.1016/j.lithos.2013.05.019

Éditeur(s) : HAL CCSD Laboratoire Arago
Résumé : International audience
The analysis of the C-O stable isotope composition of coral reef fish otoliths from Taiaro, a French Polynesian atoll normally isolated from the Pacific Ocean, has been performed to address two main questions. The first is to confirm previous results which suggest that a lagoonal coral reef fish population is able to achieve its ontogenetic cycle without any open ocean phase. If so, are O isotopic values of otoliths an indicator of temperature fluctuations in the tropical Pacific Ocean related to climate change and in particular temperature variations of water masses? δ18O and δ13C values on both lagoon and open ocean fish otoliths caught in 2006 indicated clearly that O-isotopes reached the isotopic equilibrium; in contrast, all δ13C values exhibited a strong isotopic disequilibrium related to metabolic activity. Stable isotope compositions revealed a clear differentiation between fish from lagoons and those from the open ocean (with a δ18O enrichment of 1 ‰ in favour of the lagoon). This confirmed a lack of connectivity between habitats and that fish from lagoon lived their entire life cycle in the lagoon. Both δ18O and δ13C data indicated differences between nucleus and edge signatures with changes in fish behavior from the larval life to adulthood (habitat, diet, etc.), and a clear adaptation of dietary behavior of lagoon fish. The comparison of the 2006 data set with those of 1994 showed that environmental conditions were stable in the lagoon, leading to a very narrow range of variations in the δ18O values. δ18O of fish otoliths of the open ocean exhibited a wider variation (+0.25 ‰) between 1994 and 2006, suggesting a decrease in temperature linked to a change of SST, which can be interpreted in terms of climate change associated with El Nino Southern Oscilation (ENENSO). These differences could also be due to a switch of habitats during the life cycle of fish from the open ocean.
ISSN: 0240-8759

hal-01162477
https://hal-univ-perp.archives-ouvertes.fr/hal-01162477

Éditeur(s) : HAL CCSD Wiley-Blackwell
Résumé : International audience
Lawsonite pseudomorphs are used to identify and distinguish the kinematic records of subduction and exhumation in blueschist-facies rocks from Syros (Cyclades; Greece). Lawsonite is a hydrous mineral that crystallizes at high-pressure and low-temperature conditions. During decompression, lawsonite is typically pseudomorphed by an aggregate dominated by epidote and paragonite. Such aggregates are easily deformable and if deformation occurs after the lawsonite breakdown, the pseudomorphs are difficult to distinguish from the matrix. The preservation of the lawsonite crystal shape, despite complete retrogression, indicates therefore that the host blueschist rock has not been affected by penetrative deformation during exhumation, thus providing indication of strain-free conditions. Therefore, tracking the lawsonite growth and destabilization along the P-T path followed by the rocks during a subduction/exhumation cycle provides information about the subduction/exhumation-related deformation. Using microstructural observations and P-T pseudosections calculated with thermocalc, it is inferred that top-to-the-south sense of shear preserved in lawsonite pseudomorph-bearing blueschists on Syros occurred during the prograde metamorphic path within the lawsonite stability field, and is therefore associated with subduction. On the contrary, the deformation with a top-to-the-north sense of shear is observed in surrounding rocks, where lawsonite pseudomorphs are deformed or apparently lacking. This deformation occurred after the lawsonite breakdown during exhumation. At the regional scale, exhumation-related deformation is heterogeneous, allowing the preservation of lawsonite pseudomorphs in significant volumes of blueschists of the central and southern Cyclades. It is argued that such successive shearing deformation events with opposite senses more likely correspond to an exhumation process driven by slab rollback, in which subduction and exhumation are not synchronous
ISSN: 0263-4929

insu-00841214
https://hal-insu.archives-ouvertes.fr/insu-00841214
DOI : 10.1111/jmg.12035

Éditeur(s) : HAL CCSD Society for Range Management
Résumé : Grasslands and agroecosystems occupy one-third of the terrestrial area, but their contribution to the global carbon cycle remains uncertain. We used a set of 316 site-years of CO(2) exchange measurements to quantify gross primary productivity, respiration, and light-response parameters of grasslands, shrublands/savanna, wetlands, and cropland ecosystems worldwide. We analyzed data from 72 global flux-tower sites partitioned into gross photosynthesis and ecosystem respiration with the use of the light-response method (Gilmanov, T. G., D. A. Johnson, and N. Z. Saliendra. 2003. Growing season CO(2) fluxes in a sagebrushsteppe ecosystem in Idaho: Bowen ratio/energy balance measurements and modeling. Basic and Applied Ecology 4:167-183) from the RANGEFLUX and WORLDGRASSAGRIFLUX data sets supplemented by 46 sites from the FLUXNET La Thuile data set partitioned with the use of the temperature-response method (Reichstein, M., E. Falge, D. Baldocchi, D. Papale, R. Valentini, M. Aubinet, P. Berbigier, C. Bernhofer, N. Buchmann, M. Falk, T. Gilmanov, A. Granier, T. Grunwald, K. Havrankova, D. Janous, A. Knohl, T. Laurela, A. Lohila, D. Loustau, G. Matteucci, T. Meyers, F. Miglietta, J.M. Ourcival, D. Perrin, J. Pumpanen, S. Rambal, E. Rotenberg, M. Sanz, J. Tenhunen, G. Seufert, F. Vaccari, T. Vesala, and D. Yakir. 2005. On the separation of net ecosystem exchange into assimilation and ecosystem respiration: review and improved algorithm. Global Change Biology 11: 1.424-1439). Maximum values of the quantum yield (alpha = 75 mmol.mol(-1)), photosynthetic capacity (A(max) = 3.4 mg CO(2) . m(-2).s-1), gross photosynthesis (P(g,max) = 1.16 g CO(2) . m(-2).d(-1)), and ecological light-use efficiency (epsilon(ecol) = 59 mmol . mol(-1)) of managed grasslands and high-production croplands exceeded those of most forest ecosystems, indicating the potential of nonforest ecosystems for uptake of atmospheric CO(2). Maximum values of gross primary production (8 600 g CO(2) . m(-2).yr(-1)), total ecosystem respiration (7 900 g CO(2) . m(-2).yr(-1)), and net CO(2) exchange (2 400 g CO(2) . m(-2).yr(-1)) were observed for intensively managed grasslands and high-yield crops, and are comparable to or higher than those for forest ecosystems, excluding some tropical forests. On average, 80% of the nonforest sites were apparent sinks for atmospheric CO(2), with mean net uptake of 700 g CO(2) . m(-2).yr(-1) for intensive grasslands and 933 g CO(2) . m(-2).d(-1) for croplands. However, part of these apparent sinks is accumulated in crops and forage, which are carbon pools that are harvested, transported, and decomposed off site. Therefore, although agricultural fields may be predominantly sinks for atmospheric CO(2), this does not imply that they are necessarily increasing their carbon stock.
ISSN: 1550-7424

hal-01190754
https://hal.archives-ouvertes.fr/hal-01190754
DOI : 10.2111/rem-d-09-00072.1
PRODINRA : 214043

Éditeur(s) : Elsevier Science Bv
Résumé : For many trace elements, continental margins are the location of intense exchange processes between sediment and seawater, which control their distribution in the water column, but have yet to be fully understood. In this study, we have investigated the impact of fluid seepage at cold seeps on the marine cycle of neodymium. We determined dissolved and total dissolvable (TD) concentrations for REE and well-established tracers of fluid seepage (CH4, TDFe, TDMn), and Nd isotopic compositions in seawater samples collected above cold seeps and a reference site (i.e. away from any fluid venting area) from the Niger Delta margin. We also analyzed cold seep authigenic phases and various core-top sediment fractions (pore water, detrital component, easily leachable phases, uncleaned foraminifera) recovered near the hydrocast stations. Methane, TDFe and TDMn concentrations clearly indicate active fluid venting at the studied seeps, with plumes rising up to about 100 m above the seafloor. Depth profiles show pronounced REE enrichments in the non-filtered samples (TD concentrations) within plumes, whereas filtered samples (dissolved concentrations) exhibit slight REE depletion in plumes relative to the overlying water column and display typical seawater REE patterns. These results suggest that the net flux of REE emitted into seawater at cold seeps is controlled by the presence of particulate phases, most probably Fe-Mn oxyhydroxides associated to resuspended sediments. At the reference site, however, our data reveal significant enrichment for dissolved REE in bottom waters, that clearly relates to diffusive benthic fluxes from surface sediments. Neodymium isotopic ratios measured in the water column range from epsilon(Nd) similar to-15.7 to -10.4. Evidence that the epsilon(Nd) values for Antarctic Intermediate waters (AAIW) differed from those reported for the same water mass at open ocean settings shows that sediment/water interactions take place in the Gulf of Guinea. At each site, however, the bottom water epsilon(Nd) signature generally differs from that for cold seep minerals, easily leachable sediment phases, and detrital fractions from local sediments, ruling out the possibility that seepage of methane-rich fluids and sediment dissolution act as a substantial source of dissolved Nd to seawater in the Gulf of Guinea. Taken together, our data hence suggest that co-precipitation of Fe-Mn oxyhydroxide phases in sub-surface sediments leads to quantitative scavenging of dissolved REE at cold seeps, preventing their emission into bottom waters. Most probably, it is likely that diffusion from suboxic surface sediments dominates the exchange processes affecting the marine Nd cycle at the Niger Delta margin. (C) 2011 Elsevier B.V. All rights reserved.
Earth And Planetary Science Letters (0012-821X) (Elsevier Science Bv), 2011-12 , Vol. 312 , N. 3-4 , P. 443-452

Droits : 2011 Elsevier B.V. All rights reserved.
http://archimer.ifremer.fr/doc/00066/17754/15571.pdf
DOI:10.1016/j.epsl.2011.10.008
http://archimer.ifremer.fr/doc/00066/17754/

Éditeur(s) : HAL CCSD Elsevier Masson
Résumé : 14 pages
International audience
Central Africa hosts the world's second largest tropical forest after the Amazonian basin. However, as compared to its Amazonian counterpart, the Central Africa forests receive much less rain (∼1500 mm/year in mean spread over two rainy seasons in March-May and September-November, and two dry seasons). They also experience a slower deforestation rate, so that the main threat for the next decades might come from climate variations. Nonetheless, their response to the annual cycle of solar radiation and rainfall/clouds is still poorly known. Analysing high resolution remote sensing data of Enhanced Vegetation Index, rainfall, cloudiness, and solar radiation for a target region located between 0 and 5°N and 12–19°E, we explore the climatic drivers of the forests greenness mean annual cycle. Three main points emerge; first, the diurnal cycle is a key-scale for understanding the mean annual cycles of rainfall and incoming solar radiation at surface, then how climate shapes the greenness mean annual evolution; second, neither the two dry seasons nor the two rainy seasons resemble each other in terms of cloud cover, solar radiation and rainfall, and their links with greenness levels; third, whereas the first rainy season (March-May) appears optimal for greenness especially because of favorable light conditions, water availability is the main controlling factor during the main dry season and at the start of the first vegetative season (February). Regarding the little dry season (mid-June-mid-August) and the second rainy season (September-October), light availability might be the main limiting factor. These findings pave the way for further studies of the climate interannual variability and change impacts on the Central Africa forests, taking into account time-scale interactions.
ISSN: 0168-1923

hal-01309565
https://hal.archives-ouvertes.fr/hal-01309565
DOI : 10.1016/j.agrformet.2016.04.005

Éditeur(s) : HAL CCSD Elsevier
Résumé : While around 20% of the Amazonian forest has been cleared for pastures and agriculture, one fourth of the remaining forest is dedicated to wood production [1] . Most of these production forests have been or will be selectively harvested for commercial timber, but recent studies show that even soon after logging, harvested stands retain much of their tree-biomass carbon and biodiversity [2,3] . Comparing species richness of various animal taxa among logged and unlogged forests across the tropics, Burivalova et al. [4] found that despite some variability among taxa, biodiversity loss was generally explained by logging intensity (the number of trees extracted). Here, we use a network of 79 permanent sample plots (376 ha total) located at 10 sites across the Amazon Basin [5] to assess the main drivers of time-to-recovery of post-logging tree carbon ( Table S1 ). Recovery time is of direct relevance to policies governing management practices (i.e., allowable volumes cut and cutting cycle lengths), and indirectly to forest-based climate change mitigation interventions.
ISSN: 0960-9822

hal-01536542
https://hal.archives-ouvertes.fr/hal-01536542
DOI : 10.1016/j.cub.2015.07.034
PRODINRA : 343217
PUBMED : 26394096