Résumé : Cette thèse concerne la modélisation des dynamiques de maladies foliaires de cultures pérennes tropicales à différentes échelles spatiales. Cette approche de modélisation est appliquée à la cercosporiose noire du bananier. Il s’agit d’explorer et de déterminer les paramètres environnementaux et de résistance de l’hôte ayant une influence significative sur la dynamique spatiotemporelle de la maladie et d’apporter des éléments associés au contrôle de la cercosporiose noire.Deux modèles ont été développés dans le cadre de cette thèse. La dynamique épidémiologique au niveau de la plante est décrite par un modèle mécaniste décomposé en un modèle de croissance de la plante et un module épidémiologique décrivant le cycle épidémique du pathogène. L’architecture du bananier est prise en compte par le biais de compartiments foliaires positionnés dans l’espace. Le modèle a été validé par un jeu de données indépendant. Les expérimentations numériques et l’analyse de sensibilité du modèle réalisées par les méthodes de Morris et de e-FAST ont permis de mieux comprendre le fonctionnement épidémique de cette maladie et d’identifier les paramètres influant le plus la dynamique épidémique en particulier la vitesse d’extension des lésions, la durée d’incubation et l’efficacité d’infection .L’approche bayésienne a permis de prendre en compte l’information a priori disponible pour ces trois paramètres sur lesquels a porté l’inférence statistique. L’analyse de sensibilité du modèle a également permis d’identifier l’influence de deux paramètres liés à la croissance de la plante : le nombre de feuilles sur une plante et le rythme d’émission foliaire Un modèle de dynamique spatio-temporelle de la cercosporiose noire a été développé à l’échelle d’un territoire à partir d’enquêtes effectuées enMartinique pendant la période d’invasion de cette maladie de septembre 2010 à mai 2012. Les données récoltées étant censurées, l’inférence des paramètres du modèle a été réalisée dans un cadre bayésien en utilisant un algorithme d’augmentation de données. Le modèle et l’inférence développés permettent de reconstruire la dynamique spatio-temporelle de l’invasion et de prédire la fin d’invasion sur le territoire.Les deux modèles de dynamiques spatio-temporelles développés à deux échelles spatiales différentes ont permis d’acquérir des informations importantes pour construire des outils de conception de méthode de contrôle de la cercosporiose noire des bananiers.
This thesis concerns the modeling of the dynamics of foliar diseases of tropical tree crops at different spatial scales. This modeling approach is applied to black Sigatoka of banana. It is to explore and determine the environmental parameters and host resistance has a significant influence on the spatiotemporal dynamics of the disease and to provide elements associated with the control of Sigatoka noire.Deux models were developed as part of this thesis. The epidemiological dynamics at the plant is described by a mechanistic model decomposed into a growth model of the plant and an epidemiological unit describing the pathogen epidemic cycle. The architecture of the banana is taken into account through foliar compartments positioned in space. The model was validated by an independent data set. Numerical experiments and model sensitivity analysis performed by the methods of Morris and e-FAST enabled to better understand the functioning of this epidemic disease and identify the parameters affecting the most dynamic epidemic especially speed extension of the lesions, the incubation period and efficiency of Bayesian .L'approche infection allowed to take into account prior information available for these three parameters that were the statistical inference. The model sensitivity analysis also identified the influence of two parameters related to plant growth: the number of leaves on a plant and rate of leaf emission A dynamic model of space-time Black Sigatoka has been developed at the scale of a territory from surveys enMartinique during the period of invasion of the disease from September 2010 to May 2012. The data collected being censored, inference of model parameters has was performed in a Bayesian framework, using a data augmentation algorithm. The model developed and inference possible to reconstruct the spatiotemporal dynamics of the invasion and predict the end of the invasion territoire.Les two spatio-temporal dynamics models developed at two different spatial scales has been gained important information for build tools design method of control of black Sigatoka of banana.

http://www.theses.fr/2015AGUY0835/document

Éditeur(s) : Actes de colloques Ifremer, Tahiti, French Polynesia, 20 Feb - 4 Mar 1989, n°9, chap. 62, pp.661-675
Résumé : The red drum Sciaenops ocellata (Linneaus, 1766) was introduced in Martinique (F.W.I.) from the United States (Texas and Florida). Thirteen intensive larval rearing attempts, from 7 batches of imported eggs, have been conducted for two years.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/1989/acte-1434.pdf
http://archimer.ifremer.fr/doc/00000/1434/

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Wasilewski et al. (1979) concluded that no magnetic remanence existed in the uppermost mantle and that even if present, such sources would be at temperatures too high to contribute to long wavelength magnetic anomalies (LWMA). However, new collections of unaltered mantle xenoliths indicate that the uppermost mantle could contain ferromagnetic minerals. 1. The analysis of some LWMA over cratons and forearcs suggest magnetic sources in the uppermost mantle. 2. The most common ferromagnetic phase in the uppermost mantle is stoichiometric magnetite. Assuming a 30 km-thick crust, and crustal and mantle geotherms of 15 °C/km and 5 °C/km, respectively, the 600 °C Curie temperature implies a 30 km-thick layer of mantle. 3. The uppermost mantle is cooler than 600 °C in Archean and Proterozoic shields (> 350 °C), subduction zones (> 300 °C) and old oceanic basins (> 250 °C). 4. Recently investigated sets of unaltered mantle xenoliths contain pure magnetite inclusions in olivine and pyroxene formed in equilibrium with the host silicate. 5. The ascent of mantle xenoliths occurs in less than a day. Diffusion rates in olivine suggest that the growth of magnetite possible within this time frame cannot account for the size and distribution of magnetite particles in our samples. 6. Demagnetization of natural remanent magnetization (NRM) of unaltered mantle xenoliths unambiguously indicates only a single component acquired upon cooling at the Earth's surface. This is most easily explained as a thermoremanent magnetization acquired by pre-existing ferromagnetic minerals as xenoliths cool rapidly at the Earth's surface from magmatic temperatures, acquired during ascent. 7. Modern experimental data suggest that the wüstite-magnetite oxygen buffer and the fayalite-magnetite-quartz oxygen buffer extend several tens of km within the uppermost mantle. 8. The magnetic properties of mantle xenoliths vary consistently across tectonic settings. In conclusion, the model of a uniformly non-magnetic mantle should be revisited. Keywords
ISSN: 0040-1951

hal-01053923
https://hal.archives-ouvertes.fr/hal-01053923
DOI : 10.1016/j.tecto.2014.01.004

Résumé : Le pâturage, principal mode d’alimentation en zone tropicale, est souvent dévalorisé car il est associé à des performances animales jugées insuffisantes, et peut avoir des effets néfastes sur l’environnement. Même si l’alimentation à l’auge permet de meilleures productions, ce mode de conduite présente également des inconvénients, en termes d’investissements, de rentabilité économique, d’impact des rejets sur l’environnement et de qualité des produits. Une intensification de la conduite au pâturage semble donc une voie d’avenir, mais nécessite une meilleure connaissance de ce mode de conduite et de ses conséquences sur l’alimentation et les performances des animaux. Il apparait également nécessaire de comparer l’élevage au pâturage et à l’auge sur des critères homogènes, en dissociant les composantes de ces modes de conduite.L’objectif de la thèse est d’évaluer et de comparer la conduite au pâturage et la conduite hors sol, en tenant compte également de la distribution ou non de concentré, sur l’alimentation, la croissance, les caractéristiques d’abattage et la consommation d’eau. Dans un premier temps, nous avons étudié au cours d’une expérimentation, les effets de ces deux modes de conduite sur la croissance, les caractéristiques d’abattage et de carcasse de taurillons Créoles abattus à deux âges (précoce vs tardif). Les taurillons à l’auge avaient une croissance plus rapide, des poids de carcasse plus élevés, ainsi que des carcasses plus grasses. Nous avons observé qu’abattre plus tardivement au pâturage (17 et 21 mois vs 14 et 17 mois à l’auge), permettait d’atteindre des poids finaux similaires à ceux obtenus à l’auge et des carcasses de meilleure qualité, plus riche en muscle. Nous avons expliqué la majorité de nos résultats par les effets combinés des modes de conduite et de l’alimentation et avons voulu étudier leurs effets respectifs. Dans un second temps, l’étude des effets du mode de conduite a été faite dans un premier temps, par le biais d’une méta-analyse. Les performances des animaux à l’auge étaient meilleures qu’au pâturage, mais ces effets dépendaient de la stratégie de complémentation. De cette méta-analyse est également apparu le manque d’études auge vs pâturage sur l’alimentation et à ration égale. Afin d’étudier les effets respectifs du mode de conduite et de la stratégie de complémentation, un dispositif analytique avec des taurillons élevés à l’auge et au pâturage complémentés ou non avec du concentré a été mis en place. Dans un premier temps, une étude méthodologique menée grâce à ce dispositif nous a permis d’identifier que la SPIR permettait la meilleure estimation de la dMO, l’OMI et la MODI au pâturage. Les résultats de l’étude analytique ont montré que les animaux au pâturage utilisaient mieux leur alimentation pour leur croît que ceux à l’auge et la stratégie de complémentation influençait davantage ces variables que le mode de conduite. Avec une stratégie de complémentation appropriée, les animaux au pâturage peuvent atteindre des performances similaires à celles obtenues à l’auge.
Grazing, main way of feeding ruminants in the tropics, is often undervalued because it is associated with animal performance deemed insufficient, and may have adverse effects on the environment. Even if stall feeding allows better production, this way of feeding has drawbacks in terms of investment, profitability, impact of emissions on the environment and product quality. Intensification of grazing seems a way forward, but requires a better understanding of this way of feeding and its impact on feeding and animal performance. It also appears necessary to compare grazing and stalls feeding on homogeneous criteria, separating the components of these modes of management.The aim of the thesis is to evaluate and compare stalls and pasture feeding environment, taking into account also the distribution or not of concentrate on feeding, growth, slaughter characteristics and water consumption. At first , we studied in an experiment , the effects of these two feeding systems on growth, slaughter and carcass characteristics of Creoles bulls slaughtered at two ages (early vs. late ). Bulls fed in trough grew faster, had greater carcass weight and fatter carcasses. We observed that a later slaughter of grazing animals (17 and 21 months vs. 14 and 17 months in stalls), allowed to reach final weights similar to those obtained in stalls and carcasses richer in muscle. We explained most of our results by the combined effects of feeding environment and complementation strategy and wanted to study their effects. In a second step, the study of the effects of feeding environment was made in first instance, through a meta-analysis. Stalls fed animals had greater performances than pasture fed ones, but these effects depended on complementation strategy. This meta-analysis also highlighted the lack of knowledge on intake and digestibility at pasture, which is a limitation on attempts to compare with measurements carried out in trough-fed animals. To investigate the relative effects of feeding environment and complementation strategy, we conceived an analytical trial with Creole bulls reared in stalls and at pasture, supplemented or not with concentrate. First of all, this analytical trial was the support of a methodological study, which identified that the NIRS method allows the best estimate of the OMD, OMI and DOMI at pasture. The analytical trial showed that grazing animals had better feed efficiency feed for their growth than stall fed ones and complementation strategy influenced more these variables than feeding environment. With an appropriate strategy for complementation, grazing animals can achieve similar performance to those obtained at the trough.

http://www.theses.fr/2013AGUY0675/document

Éditeur(s) : HAL CCSD Royal Society, The
Résumé : Species engaged in multiple, simultaneous mutualisms are subject to trade-offs in their mutualistic investment if the traits involved in each interaction are overlapping, which can lead to conflicts and affect the longevity of these associations. We investigate this issue via a tripartite mutualism involving an ant plant, two competing ant species and a fungus the ants cultivate to build galleries under the stems of their host plant to capture insect prey. The use of the galleries represents an innovative prey capture strategy compared with the more typical strategy of foraging on leaves. However, because of a limited worker force in their colonies, the prey capture behaviour of the ants results in a trade-off between plant protection (i.e. the ants patrol the foliage and attack intruders including herbivores) and ambushing prey in the galleries, which has a cascading effect on the fitness of all of the partners. The quantification of partners' traits and effects showed that the two ant species differed in their mutualistic investment. Less investment in the galleries (i.e. in fungal cultivation) translated into more benefits for the plant in terms of less herbivory and higher growth rates and vice versa. However, the greater vegetative growth of the plants did not produce a positive fitness effect for the better mutualistic ant species in terms of colony size and production of sexuals nor was the mutualist compensated by the wider dispersal of its queens. As a consequence, although the better ant mutualist is the one that provides more benefits to its host plant, its lower host–plant exploitation does not give this ant species a competitive advantage. The local coexistence of the ant species is thus fleeting and should eventually lead to the exclusion of the less competitive species.
ISSN: 0962-8452

hal-01608641
https://hal.archives-ouvertes.fr/hal-01608641
DOI : 10.1098/rspb.2016.1679
PRODINRA : 405078

Éditeur(s) : HAL CCSD Cambridge University Press (CUP)
Résumé : International audience
Leishmania parasites can escape the immune response by invading cell types lacking leishmanicidal mechanisms. Silent persistence of Leishmania parasites in the host organism is responsible for asymptomatic carriage and relapses after cured leishmaniasis. Here, we studied the interaction between Hepatic Stellate Cells (HSC) and Leishmania. An original model of human HSC in primary culture infected with L. donovani was developed. The presence of intracellular parasites was studied and quantified using optical and confocal microscopy. HSC characteristics were studied using microscopy, methylene blue assay, long-term cultures and qPCR. We showed for the first time that human HSC are permissive to L. donovani infection, with no modification of HSC survival, growth rate and proinflammatory and fibrogenic characteristics. Intracellular parasites did not replicate but HSC had no effect on their survival. Indeed, after a 40-day culture, infected HSC cultures transferred on NNN medium yielded new promastigotes that were able to proliferate and efficiently infect new cells. HSC are permissive to L. donovani, with neither parasite killing nor apparent cell damage. Thus, HSC could act as potent sanctuary cells for Leishmania in the liver, which could partially explain parasite reactivation after an asymptomatic carriage or a cured visceral leishmaniasis.
ISSN: 0031-1820

inserm-00825803
http://www.hal.inserm.fr/inserm-00825803
DOI : 10.1017/S0031182012001965
PUBMED : 23253952

Éditeur(s) : HAL CCSD
Résumé : Atmospheric carbon dioxide records indicate that the land surface has acted as a strong global carbon sink over recent decades, with a substantial fraction of this sink probably located in the tropics, particularly in the Amazon. Nevertheless, it is unclear how the terrestrial carbon sink will evolve as climate and atmospheric composition continue to change. Here we analyse the historical evolution of the biomass dynamics of the Amazon rainforest over three decades using a distributed network of 321 plots. While this analysis confirms that Amazon forests have acted as a long-term net biomass sink, we find a long-term decreasing trend of carbon accumulation. Rates of net increase in above-ground biomass declined by one-third during the past decade compared to the 1990s. This is a consequence of growth rate increases levelling off recently, while biomass mortality persistently increased throughout, leading to a shortening of carbon residence times. Potential drivers for the mortality increase include greater climate variability, and feedbacks of faster growth on mortality, resulting in shortened tree longevity. The observed decline of the Amazon sink diverges markedly from the recent increase in terrestrial carbon uptake at the global scale, and is contrary to expectations based on models.
ISSN: 1476-4687

hal-01204223
https://hal.archives-ouvertes.fr/hal-01204223
DOI : 10.1038/nature14283
PRODINRA : 294797
PUBMED : 25788097

Éditeur(s) : HAL CCSD European Geosciences Union
Résumé : International audience
During the GWADASEIS cruise (Lesser Antilles volcanic arc, February-March 2009) a very high resolution (VHR) seismic-reflection survey was performed in order to constrain Late Quaternary to Present faulting. The profiles we obtained evidence frequent "ponding" of reworked sediments in the deepest areas, similar to the deposition of Mediterranean "homogenites". These bodies are acoustically transparent (few ms t.w.t. thick) and are often deposited on the hanging walls of dominantly normal faults, at the base of scarps. Their thickness appears sufficient to compensate (i.e. bury) co-seismic scarps between successive earthquakes, resulting in a flat and horizontal sea floor through time. In a selected area (offshore Montserrat and Nevis islands), piston coring (4 to 7 m long) was dedicated to a sedimentological analysis of the most recent of these particular layers. It corresponds to non-stratified homogenous calcareous silty sand (reworked calcareous plankton and minor volcanoclastics). This layer can be up to 2 m thick, and overlies finegrained hemipelagites. The upper centimeters of the latter represent the normal RedOx water/sediment interface. 210Pb and 137Cs activities lack in the massive sands, while a normal profile of unsupported 210Pb decrease is observed in the hemipelagite below, together with a 137Cs peak correspond- ing to the Atmospheric Nuclear Experiments (1962). The RedOx level was thus capped by a recent instantaneous major sedimentary event considered as post-1970 AD; candidate seismic events to explain this sedimentary deposits are either the 16 March 1985 earthquake or the 8 October 1974 one (Mw=6.3 and Mw=7.4, respectively). This leads to consider that the syntectonic sedimentation in this area is not continuous but results from accumulation of thick homogenites deposited after the earthquakes (as observed in the following weeks after Haiti January 2010 event, McHugh et al., 2011). The existence of such deposits suggests that, in the area of study, vertical throw likely results from cumulated effects of separated earthquakes rather than from aseismic creep. Examination of VHR profiles shows that all major co-seismic offsets are recorded in the fault growth sequence and that co-seismic offsets can be precisely estimated. By using a sedimentation rate deduced from 210Pb decrease curve (0.5 mm yr−1) and taking into account minor reworking events detected in cores, we show that the Redonda system may have been responsible for five >M6 events during the last 34 000 yr. The approach presented in this work differs from fault activity analyses using displaced sets of isochronous surfaces and postulating co-seismic offsets. Combining VHR seismic imagery and coring we can decipher co-seismic vs. slow continuous displacement, and thus actually estimate the amplitude and the time distribution of major co-seismic offsets.
ISSN: 1561-8633

insu-00844581
https://hal-insu.archives-ouvertes.fr/insu-00844581
https://hal-insu.archives-ouvertes.fr/insu-00844581/document
https://hal-insu.archives-ouvertes.fr/insu-00844581/file/nhess-12-1755-2012.pdf
DOI : 10.5194/nhess-12-1755-2012

Éditeur(s) : Elsevier
Résumé : The "Summer Syndrome", a septicemic vibriosis caused by Vibrio nigripulchritudo, is responsible for one of the two main seasonal mortalities which affect shrimp aquaculture in New Caledonia. It was identified for the first time in December 1997 in an intensive shrimp farm (called farm DF) and has been enzootic ever since. The "Summer syndrome" affects shrimp during warm-season growout. Although the geographic area concerned is limited, it is a potential threat for the industry in that the disease could spread. Analysis of grow out data from 1991 to 2002 in this farm was carried out in order to characterize the disease and the environmental conditions in relation to mortality. Results of farm DF were compared to data from farms not affected by the disease (called farms HC). The "Summer syndrome" occurs during the warm season which is characterized by an increase in water temperature and sunny duration. This disease is characterized by simultaneously highest densities and weakest drying duration between crops in the farms studied. Between 1991 and 2002, the increase of feed input and nitrogen rate in feed has led to a significant increase of the growth rate over the years in farm DF. At the same time, water management has not changed and has induced an increase in environmental waste production. In consequence, an early eutrophication of water is observed, which is concomitant with the beginning of the mortality outbreaks. This could play a role by inducing directly or indirectly a stress for shrimp and/or a growth and/or virulence factors of the pathogen.
Aquaculture (0044-8486) (Elsevier), 2006-08 , Vol. 261 , N. 3 , P. 1039-1047

Droits : 2006 Elsevier
http://archimer.ifremer.fr/doc/2006/publication-1868.pdf
DOI:10.1016/j.aquaculture.2006.08.036
http://archimer.ifremer.fr/doc/00000/1868/

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
In mutualisms, each interacting species obtains resources from its partner that it would obtain less efficiently if alone, and so derives a net fitness benefit. In exchange for shelter (domatia) and food, mutualistic plant-ants protect their host myrmecophytes from herbivores, encroaching vines and fungal pathogens. Although selective filters enable myrmecophytes to host those ant species most favorable to their fitness, some insects can by-pass these filters, exploiting the rewards supplied whilst providing nothing in return. This is the case in French Guiana for Cecropia obtusa (Cecropiaceae) as Pseudocabima guianalis caterpillars (Lepidoptera, Pyralidae) can colonize saplings before the installation of their mutualistic Azteca ants. The caterpillars shelter in the domatia and feed on food bodies (FBs) whose production increases as a result. They delay colonization by ants by weaving a silk shield above the youngest trichilium, where the FBs are produced, blocking access to them. This probable temporal priority effect also allows female moths to lay new eggs on trees that already shelter caterpillars, and so to occupy the niche longer and exploit Cecropia resources before colonization by ants. However, once incipient ant colonies are able to develop, they prevent further colonization by the caterpillars. Although no higher herbivory rates were noted, these caterpillars are ineffective in protecting their host trees from a pathogenic fungus, Fusarium moniliforme (Deuteromycetes), that develops on the trichilium in the absence of mutualistic ants. Therefore, the Cecropia treelets can be parasitized by two often overlooked species: the caterpillars that shelter in the domatia and feed on FBs, delaying colonization by mutualistic ants, and the fungal pathogen that develops on old trichilia. The cost of greater FB production plus the presence of the pathogenic fungus likely affect tree growth.
PLoS ONE

hal-00912399
https://hal.archives-ouvertes.fr/hal-00912399
https://hal.archives-ouvertes.fr/hal-00912399/document
DOI : 10.1371/journal.pone.0020538
OATAO : 10156

Éditeur(s) : HAL CCSD Elsevier
Résumé : We have studied the phase transformation of forsterite to wadsleyite under shear stress at the Earth's transition zone pressure and temperature conditions. Two-step experiments were performed using a multi-anvil press. First, we hot pressed iron-free forsterite at 6 or 11 GPa and 1100 degrees C. Then we deformed a slab of this starting material using a direct simple shear assembly at 16 GPa and 1400 degrees C for 1, 15, 35, 40, or 60 min. Both the starting material and the deformed samples were characterized using optical and scanning electron microscopy including measurements of crystal preferred orientations (CPO) by electron back scattered diffraction (EBSD), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR). The phase transformation occurs very rapidly, in less than 1 min, and metastable forsterite relics are not observed after deformation. The grain size of wadsleyite is slightly smaller than the forsterite starting material. The water contents obtained from FTIR analyses in forsterite and wadsleyite are 65-124 wt ppm H2O and 114-736 wt ppm H2O, respectively, which are well below water solubility at similar conditions in the presence of free water. Wadsleyite aggregates display weak CPO patterns with [1 0 0] axes concentrated at low angle to the shear direction, [0 1 0] axes perpendicular to the shear plane and nearly random [0 0 1] axes. Only a few dislocations were observed in wadsleyite with TEM. This observation is consistent with the assumption that most dislocations formed during the initial high-stress stages of these stress-relaxation experiments, were consumed in the phase transformation, probably enhancing the transformation rate. CPO patterns vary as a function of the water content: with increasing water content the density of [1 0 0] axes parallel to the shear direction decreases, and the density of [0 0 1] axes increases. Viscoplastic self-consistent modeling of CPO evolution using previously reported glide systems for wadsleyite, i.e., [1 0 0]{0 k 1} and 1/2 (1 1 1){1 0 1}, cannot reproduce the measured CPO, unless the [0 0 1](0 1 0) system, for which dislocations have not been observed by TEM, is also activated. In addition, wadsleyite grain growth suggests the participation of diffusion-assisted processes in deformation. Calculated anisotropies for P and S-waves using measured CPO are always below 1%. This very low anisotropy is due to both the low finite strain achieved in the experiments, which leads to weak wadsleyite CPO, and to the diluting effect of added majorite. The present experiments emphasize the importance of stress, grain size evolution and water content in the forsterite to wadsleyite phase transformation and subsequent deformation in the transition zone.
ISSN: 0031-9201

hal-00617430
https://hal.archives-ouvertes.fr/hal-00617430
DOI : 10.1016/j.pepi.2010.11.001

Résumé : In an effort to implement new fishing activities for the small scale fisheries of Reunion Island, a prospecting cruise targeting deep demersal fish (200 to 600 m) was set up on the west coast of Reunion Island in 2000. This project was carried out by the Regional Fishery Committee and the French Institute for the Exploration of the Sea (Ifremer). Large commercial stocks were identified, and numerous professional or recreational fishermen started employing electric winches to exploit these deep resources. However, the deep demersal species are a fragile resource due mainly to low growth rates and late sexual maturation. Due to the rapid increase in fishing pressure, Ifremer was asked to set up a new study and two scientific campaigns were carried out in 2011 (68 fishing trips being conducted with 559 dropline operations). The first cruise was conducted at the same sites, using the same types of fishing gear and methods used in 2000. A marked drop of greater than 90% was observed in the catches of commercial species, together with a decrease of most fish sizes, attesting the overexploitation of these stocks. Only, catches of the small non-commercial shark (Squalus megalops) remained important (50% in number and weight of total catches). The second cruise extended the prospection area to all waters surrounding Reunion Island . The overexploitation was confirmed in the west of Reunion Island, and in to a lesser degree in the north. Yields were better along the east and the south coasts. Concurrently, the efficiency of 2 hook sizes was compared : small hooks caught significantly more fish but of significantly smaller body sizes, resulting in comparable total weight of fish. We conclude that medium size hooks (i.e. type 7/0) have a significant selectivity on the fish size without loss in the global catch yield. Various types of baits were also tested with the flesh of small local pelagic fish species (Selar crumenophtalmus and Decapterus macarellus) appearing to be the most efficient. This study provides helpful indicators for the management of demersal fish stocks in Reunion island, which have been poorly surveyed and poorly regulated until now. However, the total fishing effort, especially from recreational fishermen, remains the most important factor to be quantified.
Dans la perspective de diversifier la Petite Pêche réunionnaise, une campagne de prospection des stocks de poissons démersaux profonds (200 à 600 m) avait été réalisée en 2000 par le Comité Régional des Pêches Maritimes (CRPM) et l'Institut Français de Recherche pour L'Exploitation de la Mer (Ifremer) dans l'ouest de l'île de La Réunion. Elle a montré l'existence de stocks commercialement intéressants et de nombreux pêcheurs, professionnels et plaisanciers se sont équipés en moulinets électriques pour exploiter ces ressources profondes. Cependant les poissons démersaux profonds représentent une ressource fragile du fait, notamment, de leur croissance lente et de leur maturité sexuelle tardive. Aussi, face à cette augmentation rapide de la pression de pêche, Ifremer a été sollicité pour mener une nouvelle étude ; et deux nouvelles campagnes expérimentales ont été réalisées en 2011 (68 marées ayant permis la réalisation de 559 filages). La première campagne a repris les mêmes sites de pêche, le même matériel et la même méthodologie qu’en 2000. Elle montre que les rendements en espèces commerciales ont diminué de façon très nette (plus de 90%) ainsi que la taille de certaines espèces, indicateurs caractéristiques d'une surexploitation des stocks. Seules les captures de requins zépines (Squalus megalops,) non commercialisées à La Réunion, restent comparables à celles de 2000 avec la moitié des captures totales. La 2e campagne a étendu la prospection à tout le tour de l'île. La surpêche (baisse des rendements et des tailles de poisson) est confirmée dans l'ouest et à un moindre degré sur la côte nord. Les rendements sont meilleurs dans l'est et le sud. Parallèlement, 2 tailles d'hameçons ont été comparées : les petits hameçons capturent un nombre significativement plus élevé de poissons par filage, mais de tailles plus petites, ce qui se traduit par un poids global comparable. Les hameçons de taille moyenne (type 7/0) ont donc une sélectivité significative sur la taille des poissons capturés sans nuire au rendement global. Des comparaisons ont aussi porté sur les types d'appât : Les laizes de petits pélagiques locaux (pêche-cavale et bancloche) se révèlent les plus efficaces et les plus sélectives vis-à-vis des espèces commerciales. Cette étude fournit des indicateurs utiles à la gestion des stocks démersaux jusqu'ici peu étudiés et peu encadrés. Mais la grande inconnue reste l'effort de pêche total sur cette ressource et notamment celui des pêcheurs plaisanciers.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00098/20902/18837.pdf
DOI:10.13155/20902
http://archimer.ifremer.fr/doc/00098/20902/

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Metalloproteases involved in extracellular matrix remodeling play a pivotal role in cell response by regulating the bioavailability of cytokines and growth factors. Recently, the disintegrin and metalloprotease, ADAMTS1 has been demonstrated to be able to activate the transforming growth factor TGF-β, a major factor in fibrosis and cancer. The KTFR sequence from ADAMTS1 is responsible for the interaction with the LSKL peptide from the latent form of TGF-β, leading to its activation. While the atomic details of the interaction site can be the basis of the rational design of efficient inhibitory molecules, the binding mode of interaction is totally unknown. In this study, we show that recombinant fragments of human ADAMTS1 containing KTFR sequence keep the ability to bind the latent form of TGF-β. The recombinant fragment with the best affinity is modeled to investigate the binding mode of LSKL peptide with ADAMTS1 at the atomic level. Using a combined approach with molecular docking and multiple independent molecular dynamics (MD) simulations, we provide the binding mode of LSKL peptide with ADAMTS1. The MD simulations starting with the two lowest energy model predicted by molecular docking shows stable interactions characterized by 3 salt bridges (K3-NH3+ with E626-COO−; L4-COO− with K619-NH3+; L1-NH3+ with E624-COO−) and 2 hydrogen bonds (S2-OH with E623-COO−; L4-NH with E623-COO−). The knowledge of this interaction mechanism paves the way to the design of more potent and more specific inhibitors against the inappropriate activation of TGF-β by ADAMTS1 in liver diseases
ISSN: 1476-9271

hal-01269916
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01269916
DOI : 10.1016/j.compbiolchem.2016.01.012
PUBMED : 26878129

Éditeur(s) : Wiley-blackwell Publishing, Inc
Résumé : Red shrimp, Farfantepenaeus brasiliensis, larvae's response to different concentrations of live foods (diatoms Chaetoceros gracilis: 20-100 x 103 cells/mL; flagellate Tetraselmis chuii: 2-10 x 103 cells/mL and Artemia nauplii [NA]: 1-5 NA/mL) was investigated in three experiments. Experimental assessments were based on four variables: survival rate, weight gain, development index (DI), and resistance to salinity stress. A combination of C. gracilis 80 x 103 cells/mL, T. chuii 2 x 103 cells/mL, and Artemia 4 NA/mL provided the best experimental response. Specifically, F. brasiliensis larvae fed with the above-mentioned optimal concentrations of microalgae and Artemia grew faster and reached the postlarval stage in less time (168 h) than larvae in other feeding regimes evaluated. The effect of C. gracilis concentration on larval growth, survival, and the DI demonstrated that microalgae-based foods could be a highly productive alternative to more traditional aquaculture feeding regimes.
Journal Of The World Aquaculture Society (0893-8849) (Wiley-blackwell Publishing, Inc), 2010-06 , Vol. 41 , N. 3 , P. 402-410

Droits : Copyright by the World Aquaculture Society 2010
http://archimer.ifremer.fr/doc/00028/13928/11639.pdf
DOI:10.1111/j.1749-7345.2010.00381.x
http://archimer.ifremer.fr/doc/00028/13928/

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
ISSN: 0021-8901

hal-01093618
https://hal-agroparistech.archives-ouvertes.fr/hal-01093618
DOI : 10.1111/j.1365-2664.2010.01826.x

Éditeur(s) : HAL CCSD
Résumé : The genus Cecropia includes pioneer trees that colonize canopy gaps and cleared areas. It is widely distributed from Mexico to Northern Argentina. Cecropia trees have architecture, which corresponds to the Rauh’s architectural model. In recent studies we have found that C. obtusa/ and C. sciadophylla, in French Guiana, have a strong annual periodicity for growth, branching and flowering processes, with annual emission of 35 nodes for C. obtusa and 25 for C. sciadophylla. Those species show different life histories since C. sciadophylla has longer life expectancy. In addition, C. sciadophylla is found more frequently in forest gaps, although in French Guiana mixed populations are found. The aim of this work was to compare developmental strategies of both species in three different field stations in French Guiana and to determine how these two species coexist during its first years of life. We studied a 20-year old population of /C. sciadophylla/ at Saint Elie’s Road, a 10-year old population of /C. obtusa/ at Paracou’s field station, and a 7-year old mixed population at Counami’s Road. /C. sciadophylla /emits 25 nodes per year in both studied populations, while/ C. obtusa /emits 35 nodes in the monospecific population and 30 nodes in the mixed population. In the monocaule stage, the lower number of nodes emitted by /C. sciadophylla/ compared to /C. obtusa /is compensated with a higher internodal length, which allows finding individuals with similar ages and lengths, but different number of nodes. The branching and flowering processes start on average three years before in /C. obtusa/, however for 12-year old individuals we observed a dominancy of C. sciadophylla over C. obtusa. In the mixed population it is likely that the different life histories would decrease competition effects allowing coexistence of both species during the first stages of life
Botany 2008
Vancouver, Canada

hal-01190209
https://hal.archives-ouvertes.fr/hal-01190209
PRODINRA : 182910

Éditeur(s) : HAL CCSD Wiley
Résumé : Diversified deep-water corals and associated communities occur in early Pleistocene (early Calabrian; ∼1.7–1.6 Ma) calcareous crusts discovered on the south-western coast of Karpathos Island (eastern Greece). Apart from abundant and conspicuous solitary and colonial corals (12 species), the accompanying fauna comprises mostly bivalves (10 species), serpulid worms (4 species), and bryozoans (40 species). The growth and deposition of the studied organisms occurred in an upper bathyal environment at water depths around 400–600 m. The calculated mean uplift rate after deposition of the crusts indicates that Karpathos was drowned during the earliest Calabrian and experienced severe uplifts by the late Calabrian. A comparison between these communities and those of the Pleistocene to Recent Mediterranean and north-east Atlantic shows that a common stock of taxa exist(ed); among them two azooxanthellate colonial scleractinians (Lophelia pertusa and Madrepora oculata) are predominant.
ISSN: 0267-8179

hal-01622744
https://hal.archives-ouvertes.fr/hal-01622744
DOI : 10.1002/jqs.2966

Éditeur(s) : HAL CCSD
Résumé : International audience
The influence of Mn solute atoms on sub-grain boundary mobilities in Al has been determined by accurate electron backscatter diffraction analysis of the sub-grain sizes and misorientations during recovery annealing. High purity Al-0.1 and 0.3 wt.% Mn alloys were deformed by plane strain compression at room temperature to equivalent strains of 1.8 and annealed in the temperature range 150-300 °C. An original method of image analysis on sub-boundaries from electron backscatter diffraction maps was applied to quantify the sub-grain size distributions. The change in average sub-grain size with time at several temperatures was then used to estimate sub-grain boundary mobilities in both Al-Mn alloys. The activation energies for sub-grain mobility were found to be 48 and 52 and kJ.mol^-1 for the 0.1 and 0.3 % Mn alloys respectively, with the higher Mn alloy exhibiting lower rates. The sub-boundary mobilities are higher than expected from previous similar work on deformed Al-Si crystals. The orientation dependence of sub-grain growth is also examined.
International Journal of Materials Research

emse-00463551
https://hal-emse.ccsd.cnrs.fr/emse-00463551
DOI : 10.3139/146.110057

Éditeur(s) : Elsevier
Résumé : Clinoforms on modern shelves and slopes, as well as in ancient rock records, are widely recognized as a fundamental building element of continental margin growth. Regardless of their dominant lithology, clinoforms are composed of three geometric elements: topset, foreset and bottomset. Traditionally, much emphasis in the study of clinoforms was put on the geometry of the topset, viewed as the most energetic portion of a clinoform and studied to discern if aggradation was active rather than erosional truncation, and on the foreset, the area with the highest sediment accumulation rates. Here we focus on the factors forcing clinoforms to taper out and on the inferred mechanisms for bottomset creation. We base our analysis on muddy shelf clinoforms, a particular class of clinoforms that is typical of low-gradient settings and is characterized by a substantial component of shore-parallel sediment transport. This paper is based on a large dataset of CHIRP-sonar profiles, bathymetric and isopach maps of the Late Holocene clinoform on the Adriatic shelf, where integrated stratigraphic studies from sediment cores allow a very high (in some cases century-scale) chronological resolution. Knowledge on the dominant oceanographic regime affecting sediment dispersal and, ultimately, clinoform development, has been recently refined during the EuroSTRATAFORM collaboration. Muddy clinoforms are markedly three-dimensional features that cannot be entirely understood solely on two-dimensional shore normal sections. We suggest that this class of clinoform is advection dominated and that an increase in the energy regime at the toe of the foreset may prevent sediment from reaching beyond the transition to the bottomset region.
Continental Shelf Research (0278-4343) (Elsevier), 2007-02 , Vol. 27 , N. 3-4 , P. 506-525

Droits : 2006 Elsevier Ltd All rights reserved
http://archimer.ifremer.fr/doc/2007/publication-2409.pdf
DOI:10.1016/j.csr.2006.11.013
http://archimer.ifremer.fr/doc/00000/2409/

Éditeur(s) : Natl Acad Sciences
Résumé : The marine realm represents 70% of the surface of the biosphere and contains a rich variety of organisms, including more than 34 of the 36 living phyla, some of which are only found in the oceans. The number of marine species used by humans is growing at unprecedented rates, including the rapid domestication of marine species for aquaculture and the discovery of natural products and genes of medical and biotechnological interest in marine biota. The rapid growth in the human appropriation of marine genetic resources (MGRs), with over 18,000 natural products and 4,900 patents associated with genes of marine organisms, with the latter growing at 12% per year, demonstrates that the use of MGRs is no longer a vision but a growing source of biotechnological and business opportunities. The diversification of the use of marine living resources by humans calls for an urgent revision of the goals and policies of marine protected areas, to include the protection of MGRs and address emerging issues like biopiracy or benefit sharing. Specific challenges are the protection of these valuable resources in international waters, where no universally accepted legal framework exists to protect and regulate the exploitation of MGRs, and the unresolved issues on patenting components of marine life. Implementing steps toward the protection of MGRs is essential to ensure their sustainable use and to support the flow of future findings of medical and biotechnological interest.
Proceedings Of The National Academy Of Sciences Of The United States Of America (0027-8424) (Natl Acad Sciences), 2010-10 , Vol. 107 , N. 43 , P. 18318-18324

Droits : 2010 by the National Academy of Sciences
http://archimer.ifremer.fr/doc/00018/12897/9935.pdf
DOI:10.1073/pnas.0911897107
http://archimer.ifremer.fr/doc/00018/12897/