Éditeur(s) : Université de Guyane. DFR Lettres et sciences humaines
Description : Dans une étude consacrée à l'Université d'Etat d'Haïti, Marianne Palisse examine le rôle déterminant, bien que peu connu, de Léon Gontran Damas dans la création des études ethnologiques dans ce pays. Son étude met également en lumière l'influence de l'écrivain guyanais dans les réseaux intellectuels haïtiens.
Siècle(s) traité(s) : 20
Droits : CC-BY-NC-ND - Attribution - Pas d'utilisation commerciale - Pas de modification
Permalien : http://www.manioc.org/fichiers/V18251
V18251

Éditeur(s) : Wiley-blackwell Publishing, Inc
Résumé : Vibrio splendidus, strain LGP32, is an oyster pathogen associated with the summer mortalities affecting the production of Crassostrea gigas oysters worldwide. Vibrio splendidus LGP32 was shown to resist to up to 10 mu M Cg-Def defensin and Cg-BPI bactericidal permeability increasing protein, two antimicrobial peptides/proteins (AMPs) involved in C. gigas immunity. The resistance to both oyster Cg-Def and Cg-BPI and standard AMPs (polymyxin B, protegrin, human BPI) was dependent on the ompU gene. Indeed, upon ompU inactivation, minimal bactericidal concentrations decreased by up to fourfold. AMP resistance was restored upon ectopic expression of ompU. The susceptibility of bacterial membranes to AMP-induced damages was independent of the ompU-mediated AMP resistance. Besides its role in AMP resistance, ompU proved to be essential for the adherence of V. splendidus LGP32 to fibronectin. Interestingly, in vivo, ompU was identified as a major determinant of V. spiendidus pathogenicity in oyster experimental infections. Indeed, the V. splendidus-induced oyster mortalities dropped from 56% to 11% upon ompU mutation (Kaplan Meier survival curves, P < 0.01). Moreover, in co-infection assays, the ompU mutant was out competed by the wild-type strain with competitive indexes in the range of 0.1-0.2. From this study, ompU is required for virulence of V. splendidus. Contributing to AMP resistance, conferring adhesive properties to V. splendidus, and being essential for in vivo fitness, the OmpU porin appears as an essential effector of the C. gigas/V. splendidus interaction.
Environmental Microbiology (1462-2912) (Wiley-blackwell Publishing, Inc), 2010-04 , Vol. 12 , N. 4 , P. 951-963

Droits : 2010 Society for Applied Microbiology and Blackwell Publishing Ltd
http://archimer.ifremer.fr/doc/00003/11421/8044.pdf
DOI:10.1111/j.1462-2920.2009.02138.x
http://archimer.ifremer.fr/doc/00003/11421/

Éditeur(s) : HAL CCSD
Résumé : The present PhD thesis is devoted to the numerical simulation and analysis of shear on cohesive granular materials. In the framework of the Contact Dynamics method, we developed a model of cohesive bonding, which mimics cohesion by cementation. This model involves three contact strength parameters (a tensile strength, a coefficient of sliding friction, and a coefficient of rolling friction) as well as a local criterion, which controls the creation and the breaking of cohesive bonds. All contacts are cohesive at the beginning of the numerical simulations, and contact rupture leads to an irreversible loss of tensile strength (debonding). We varied systematically the three contact strength parameters and studied their influence on the shear strength, the dilatancy, and the microstructure of the granular media. Our results show that internal friction and macroscopic tensile strength have different origins at the contact scale. We also find that the microstructure of the granular media, when sheared at the steady state (also known as the `critical state"), is strongly affected by the local coefficients of sliding and rolling friction. In particular, the mechanical role of the weak network changes with these two contact parameters, which results from the formation of a new structure of force transmission. On the other hand, we also applied the same numerical simulation method to the simulation of landslides. We developed a methodology, which takes into account the initial morphology of the hillslope, the strength of geomaterials, and a triggering factor, integrating in the same model the initiation and propagation phases of the landslide. To illustrate this methodology, we applied it to the simulation of a hypothetical example of avalanche triggered by the progressive rise of a water table.
Ce travail de thèse porte sur la modélisation numérique et l'analyse du cisaillement dans les milieux granulaires cohésifs. Dans le cadre de la méthode de la Dynamique des Contacts, nous avons développé un modèle de cohésion qui cherche à imiter la cohésion par cimentation. Ce modèle fait intervenir trois paramètres de résistance au niveau des contacts (une résistance à la traction, un coefficient de frottement de glissement, et un coefficient de frottement de roulement) ainsi qu'un critère de création et de rupture des liens cohésifs. Les contacts sont cohésifs au début des simulations et leur rupture entraîne la perte irréversible de la résistance à la traction. Nous avons fait varier les trois paramètres microscopiques et nous avons étudié leur influence dans la résistance au cisaillement, la dilatance, et la microstructure du milieu. Nos résultats montrent que le frottement interne et l'adhésion macroscopiques ont des origines microscopiques différentes. Nous observons aussi que la microstructure du milieu cisaillé à l'état stationnaire (aussi connu comme ``l'état critique") est fortement affectée par l'angle de frottement et la résistance au roulement au niveau des contacts. En particulier, le rôle mécanique du réseau faible change avec ces deux paramètres microscopiques, ce qui résulte de la formation d'une nouvelle structure de transmission de forces. D'autre part, nous avons appliqué cette méthode de simulation numérique à l'étude d'un processus naturel : les glissements de terrain. Nous avons développé une méthodologie qui tient compte de la morphologie initiale du système, de la résistance des géomatériaux, et d'un mécanisme de déclanchement, ce qui permet d'intégrer dans le même modèle les phases d'initiation et de propagation du glissement. Pour illustrer cette méthodologie, nous l'avons appliquée à la modélisation d'un exemple hypothétique d'avalanche déclenchée par la montée progressive du niveau d'une nappe d'eau.
https://tel.archives-ouvertes.fr/tel-00311303

tel-00311303
https://tel.archives-ouvertes.fr/tel-00311303
https://tel.archives-ouvertes.fr/tel-00311303/document
https://tel.archives-ouvertes.fr/tel-00311303/file/these_estrada.pdf

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Laboratory models have been conducted to improve our understanding of the role that the resistance of the slab to bending and its coupling to the ambient mantle play in subduction dynamics over geological time scales. Our models are set up with a viscous plate of silicone (lithosphere) subducting under negative buoyancy in a viscous layer of glucose syrup (mantle). For our study, the lithosphere/upper mantle viscosity contrast has been systematically varied, from similar to 10 to similar to 10(5) in order to explore the parameter space between weak and strong slab dynamics. We found that subduction is characterized by a retreating mode for viscosity ratios > 10(4), by the coexistence of a retreating mode and an advancing mode for viscosity ratios between similar to 10(4) and similar to 10(2), and quasi-stationary, Rayleigh-Taylor like behaviour for ratios < 10(2). By combining our experimental results and kinematic data from current subduction zones in four reference frames which differ in the amount of net rotation, we infer that a lithosphere/upper mantle viscosity contrast of 150-500 is necessary to obtain realistic trench/subducting plate velocity ratios as well as the variability of subduction styles observed in nature.
ISSN: 0012-821X

hal-00412008
https://hal.archives-ouvertes.fr/hal-00412008
DOI : 10.1016/j.epsl.2008.04.006

Résumé : Les variétés modernes de canne à sucre sont d'origine bispécifique et possèdent une structure génétique complexe, aneuploïde et hautement polyploïde rendant difficile les études de résistance génétique. La feuille jaune de la canne a sucre est une maladie dont l'agent causal est le sugarcane yellow leaf virus (scylv). Ce virus a une large diversité. Seuls trois génotypes viraux, différenciables par rtpcr, ont été trouves en Guadeloupe. Les objectifs de l'étude sont d'évaluer: l/la possibilité de marquer la résistance de la plante au scylv grâce a une étude d'association pan-génomique 2/l'impact de la diversité de l'agent pathogène sur la résistance de la canne a sucre au scylv. Les études d'association ont été menées avec plus de 4000 marqueurs aflp et d'art sur quatre types de données phénotypiques (intensité et densité virale dans les feuilles et les tiges). Les phénotypes ont été mesures sur 189 variétés de cannes à sucre dans deux essais successifs dans un dispositif en trois blocs randomises. De ces variétés, 40 ont été sélectionnées et ont permis d'obtenir 10 croisements biparentaux. Les descendances obtenues ont été suivies sur deux essais. L'incidence et la diversité du scylv ont été évaluées pour les 40 variétés et les descendances. L'héritabilité au sens strict de la résistance aux scylv a été déterminée. Six marqueurs de résistance au scylv ont été identifies ainsi que deux gènes ayant potentiellement un rôle dans la résistance au virus. L'étude montre également que la résistance de la plante est variable en fonction du génotype du scylv et que cette résistance est en partie transmise aux descendances. Créer des variétés résistantes au scylv est donc possible.
Modern varieties of sugarcane have a bispecific origin and a complex genetic structure, aneuploid and highly polyploid, maklng genetic resistance study uneasy to perform. Yellow leaf of sugarcane is a viral disease whose causal agent is the sugarcane yellow leaf virus (scylv). This virus has a wide range of diversity. Only three viral genotypes, distinguishable by rt-pcr, were found in guadeloupe. The objectives of this srudy are to assess: l/the possibility to find markers associated with plant resistance to scylv through a genome wide association study 2 1 the impact of the pathogen diversity on the resistance of sugarcane to scylv. Association studies have been conducted with more than 4000 aflp and dart markers on four types of phenotypic data (virus intensity and density in leaves and canes). Phenotypes were measured on 189 varieties of sugarcane in two successive trials in a three randomized complete block design. From these varieties, 40 were selected and allowed to obtain 10 biparental crosses. The offspring were followed during two trials. The incidence and the diversity of scylv were evaluated in the 40 varieties and the offspring. The narrow sense heritability of the resistance to the scylvs was determined. Six markers of the resistance to the scylv and two genes, with potential contribution in virus resistance, have been identified. The study also shows that the resistance of the plant is variable depending on the scylv genotype and that this resistance is partly transmitted to the offspring. Breeding for scylv resistance is practicable.

http://www.theses.fr/2012AGUY0554/document

Éditeur(s) : HAL CCSD
Résumé : International audience
In this paper, we compare the effect of rolling resistance at the contacts in granular systems composed of disks with the effect of angularity in granular systems composed of regular polygonal particles. For this purpose, we use contact dynamics simulations. By means of a simple shear numerical device, we investigate the mechanical behavior of these materials in the steady state in terms of shear strength, solid fraction, force and fabric anisotropies, and probability distribution of contact forces. We find that, based on the energy dissipation associated with relative rotation between two particles in contact, the effect of rolling resistance can explicitly be identified with that of the number of sides in a regular polygonal particle. This finding supports the use of rolling resistance as a shape parameter accounting for particle angularity and shows unambiguously that one of the main influencing factors behind the mechanical behavior of granular systems composed of noncircular particles is the partial hindrance of rotations as a result of angular particle shape.
AIP Conference Proceedings
Sydney, Australia

hal-00842799
https://hal.archives-ouvertes.fr/hal-00842799
https://hal.archives-ouvertes.fr/hal-00842799/document
https://hal.archives-ouvertes.fr/hal-00842799/file/Comparison_effects_rolling_Estrada_al.pdf

Résumé : Les deux principaux objectifs de ce travail sont de proposer des outils pour la selection d'animaux résistants aux strongles gastro-intestinaux, parasites du tube digestif, et de faire progresser la compréhension des mécanismes de résistance chez la chèvre créole. La variabilité génétique du caractère de résistance au parasitisme digestif a été étudiée afin de vérifier quels critères décrivant le mieux la résistance, peuvent être utilisés pour la sélection. L'ensemble des résultats obtenus suggèrent que le critère d'excrétion d'oeufs et le critère d'éosinophilie sont les plus adaptés pour un schéma de sélection puisqu'ils possèdent une héritabillté moyenne et représentent le mieux la résistance. De plus, ils ne semblent pas en opposition avec le poids, principal critère de production. Le déterminisme génétique de la résistance aux strongles gastro-intestinaux a été étudié et a permis de mettre en évidence l'existence d'un gène majeur pour la résistance chez la population de chèvre créole. De plus, la primo-détection de qtl a permis d'identifier 13 régions du génome ayant un effet sur les critères de résistance. Les mécanismes responsables de la résistance aux strongles gastro-intestinaux ont également été à l'étude. L'ensemble des résultats met en évidence le rôle des éosinophiles dans la mise en place de la résistance aux strongles gastro-intestinaux. L'activité des immunogobulines e semblent dirigés vers les larves l3 d'haemonchus contortus et suggère la mise en place d'une réaction protectrice. Chez la chèvre créole. Ces deux mécanismes semblent donc jouer un rôle important dans la mise en place de la résistance aux strongles gastro-intestinaux
The two main objectives of this work are to propose tools for the selection of resistant animals to gastrointestinal nematodes and advance knowledge on mechanisms of resistance of creole goats. this work has analysed the genetic variability of resistance to digestive parasitism in order to determine which criteria best describes the resistance and can be use for selection. the overall results suggest that the egg excretion and the eosinophilia are the criteria most suitable for a breeding scheme because they have moderate heritability estimates and best represent the resistance. moreover, they do not seem in conflict with the weight, the main criterion of production. the genetic determinism of resistance to gastrointestinal parasites has been studied and has highlighted the existence of a major gene for resistance in creole goats. in addition, the primodetection of qtl identified 13 genomic regions that affect the resistance. the mechanisms behind the resistance to gastrointestinal parasites were also studied and first hypothesis regarding the involvment of the immune response in resistance have been made in goats. the overall results highlighted the role of eosinophils in the development of resistance to gastrointestinal nematodes. the activity of immunoglobulin e seems directed toward l3 larvae of haemonchus contortus and may be imply in the establishment of a protective response agasint nematode parasites. in creole goats, these two mechanisms seem to play an important role in the development of resistance to gastrointestinal nematode infections

http://www.theses.fr/2011AGUY0407/document

Éditeur(s) : Springer
Résumé : The transforming growth factor (TGF)-beta superfamily is a group of important growth factors involved in multiple processes such as differentiation, cell proliferation, apoptosis and cellular growth. In the Pacific oyster Crassostrea gigas, the oyster gonadal (og) TGF-beta gene was recently characterized through genome-wide expression profiling of oyster lines selected to be resistant or susceptible to summer mortality. Og TGF-beta appeared specifically expressed in the gonad to reach a maximum when gonads are fully mature, which singularly contrasts with the pleiotropic roles commonly ascribed to most TGF-beta family members. The function of og TGF-beta protein in oysters is unknown, and defining its role remains challenging. In this study, we develop a rapid bacterial production system to obtain recombinant og TGF-beta protein, and we demonstrate that og TGF-beta is processed by furin to a mature form of the protein. This mature form can be detected in vivo in the gonad. Functional inhibition of mature og TGF-beta in the gonad was conducted by inactivation of the protein using injection of antibodies. We show that inhibition of og TGF-beta function tends to reduce gonadic area. We conclude that mature og TGF-beta probably functions as an activator of germ cells development in oyster.
Marine Biotechnology (1436-2228) (Springer), 2011-10 , Vol. 13 , N. 5 , P. 971-980

Droits : Springer Science+Business Media, LLC 2011
http://archimer.ifremer.fr/doc/00042/15371/13438.pdf
DOI:10.1007/s10126-010-9361-4
http://archimer.ifremer.fr/doc/00042/15371/

Éditeur(s) : HAL CCSD Frontiers Media
Résumé : International audience
The early 2000s marked the end of the Golden age of the antibiotics and the beginning of the awareness on the potential threat to human health due to the dissemination of antimicrobial resistance. As a base-line study, we investigated the antimicrobial susceptibility of 99 strains of non-O1/non-O139 Vibrio cholerae isolated fromwastewater and shellfish in 2000/2001 within La Rance estuary (Brittany, France). All isolates were susceptible to amoxicillin-clavulanic acid, cefotaxime, imipenem, chloramphenicol, nalidixic acid, ciprofloxacin, norfloxacin, amikacin, gentamicin, tetracycline, doxycycline, trimethoprim-sulfamethoxazole, and erythromycin. The only resistances were to streptomycin, sulfonamides and ampicillin: 54.6% of the isolates had acquired resistance to at least one antimicrobial agent among them and only six isolates from cockles were multidrug resistant. On the basis of the distribution of a limited selection of resistance associated genes, our study shows that V. cholerae can constitute an environmental reservoir for these genes. However, none of our isolates harbored integron. This result casts doubt on the capacity of non-O1/non-O139 V. cholerae to acquire resistance-associated genes in such context, and on its potential role of indicator of the dissemination of antimicrobial resistance in the aquatic environment.
ISSN: 1664-302X

hal-01616065
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01616065
DOI : 10.3389/fmicb.2017.01637
PUBMED : 28955305

Éditeur(s) : HAL CCSD American Physiological Society
Résumé : Full text: http://jn.physiology.org/content/88/3/1475
International audience
The contribution of voltage-gated calcium channels (VGCC) to the development of cultured embryonic cockroach brain neurons was assessed using pharmacological agents. VGCC currents were recorded using the patch-clamp technique and were found to be blocked dose-dependently by micromolar concentrations of mibefradil. The activation and inactivation properties of the calcium channels enable a sizeable calcium current to flow at rest (about -30 and -20 mV in high-potassium culture media). As expected, the cytoplasmic-free calcium concentration was found to rise when the extracellular potassium concentration was raised from 3 to 15 and 30 mM. The effects of VGCC blockers and calcium chelators were different in fresh and in mature cultures in which the neurons were connected to each other to form a defined network. In fresh cultures, the two non-selective VGCC blockers (verapamil and mibefradil) induced a dose-dependent cell death that was proportional to their blocking effect on I(Ba). This effect could not be prevented by addition of fetal calf serum to the culture medium. A similar effect was obtained using intra- or extracellular calcium chelating agents (10 microM BAPTA-AM or 10 mM EGTA). Quite unexpectedly, blockade of the P/Q-like (omega-Aga WA-sensitive) component of the calcium current by 500 nM of omega-AgaTx IVA had no lethal effect, suggesting that the corresponding channels are not involved in the survival mechanism. As expected from their lack of effect on I(Ba), isradipine, nifedipine, and omega-CgTx GVIA did not induce cell death. When the neurons started growing neurites, their sensitivity to calcium channel blockade by mibefradil decreased, indicating a correlation between neurite outgrowth and resistance to calcium depletion. In mature cultures, the neurons became resistant to mibefradil, verapamil, and BAPTA-AM. However, these agents, as well as omega-AgaTx IVA, had a significant inhibitory effect on the increase in diameter of the connectives that linked adjacent clusters of neurons. This effect has been shown to result, in the case of mibefradil, from an inhibition of neurite outgrowth characterized by a significant reduction of the number of primary neurites and secondary branchings but not to a significant modification of the diameter of individual neurites. These results support the view that, as in vertebrates, calcium influx through VGCC plays an important role in survival and neurite outgrowth of cultured embryonic insect neurons. The differential contribution of the P/Q-like and R-like (omega-Aga WA-sensitive) calcium channels in these processes is discussed.
ISSN: 0022-3077

hal-00982287
https://hal.archives-ouvertes.fr/hal-00982287
DOI : 10.1152/jn.00749.2001
PUBMED : 12205168

Éditeur(s) : HAL CCSD American Physical Society
Résumé : International audience
We investigate a class of granular materials characterized by the possibility of interlocking between the particles. The interlocking is modeled by its effect through rolling resistance depending on relative rotation and normal force at the contact points and involving a single parameter analogous to the sliding friction coefficient. The model, which is introduced in the framework of the contact dynamics, method, is applied to simulate the simple shear of a large granular sample. We present a detailed analysis regarding the influence of rolling and sliding friction parameters on the macroscopic response in terms of shear strength, fabric properties, and force transmission. Interestingly, two distinct regimes can be distinguished in which the steady-state shear strength is controlled by either rolling resistance or sliding friction. The relative contributions of rolling and sliding contacts to the shear strength are consistent with the same two regimes. Interlocking strongly affects the force network by enhancing the arching effect and thus increasing the relative importance of weak contact forces and torques, which is reflected in a decreasing power-law probability distribution of the contact forces and torques below the mean. Due to the combined effect of friction and interlocking, the force-carrying backbone takes an increasingly columnar aspect involving a low fraction of particles. Our data suggest that the nature of the weak contact network is strongly affected by the formation of these columns of particles which do not need to be propped laterally. In particular, in the limit of high rolling resistance and sliding friction, the role of the weak network of contacts is no longer to prop the force chains, but, like the strong contact network, to actively sustain the deviatoric load imposed on the system.
ISSN: 1539-3755

hal-00412020
https://hal.archives-ouvertes.fr/hal-00412020
DOI : 10.1103/PhysRevE.78.021301

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
Climatic changes result in an increased in mean temperature and in a higher incidence of extreme weather events such as heat and cold waves. For ectotherms, such as insect parasitoids, the ability to remain active under extreme climatic conditions is a significant key to fitness. The body size of individuals, and in particular their surface to volume ratio, may play a role in their resistance to thermal conditions. The thermal tolerances are investigated of two closely-related sympatric parasitoid species [Aphidius avenae Haliday and Aphidius rhopalosiphi De Stefani-Perez (Hymenoptera: Aphidiinae)] that have a similar ecology but differ in body size and phenologies. The critical thermal limits of individuals are assessed in both sexes of each parasitoid species and the influence of surface-volume ratios on their thermal tolerances. Aphidius avenae is less resistant to low temperatures and more resistant to high temperatures than A. rhopalosiphi. The lower surface to volume ratio of A. avenae individuals may help them to remain active in summer when experiencing heat waves. However, body size is not the sole factor that plays a role in differences of thermal tolerance between species and body size may not be an adaptation to extreme temperatures but rather a by-product of developmental regulation. Closely related sympatric species from the same ecological guild can have different thermal tolerances that may allow them to occur within the same habitat. The present study also highlights the importance of clearly defining how to measure critical thermal limits to determine the thermal tolerance of a species.
ISSN: 0307-6962

hal-00589094
https://hal.archives-ouvertes.fr/hal-00589094
DOI : 10.1111/j.1365-3032.2010.00758.x

Éditeur(s) : HAL CCSD American Physical Society
Résumé : International audience
Using contact dynamics simulations, we compare the effect of rolling resistance at the contacts in granular systems composed of disks with the effect of angularity in granular systems composed of regular polygonal particles. In simple shear conditions, we consider four aspects of the mechanical behavior of these systems in the steady state: shear strength, solid fraction, force and fabric anisotropies, and probability distribution of contact forces. Our main finding is that, based on the energy dissipation associated with relative rotation between two particles in contact, the effect of rolling resistance can explicitly be identified with that of the number of sides in a regular polygonal particle. This finding supports the use of rolling resistance as a shape parameter accounting for particle angularity and shows unambiguously that one of the main influencing factors behind the mechanical behavior of granular systems composed of noncircular particles is the partial hindrance of rotations as a result of angular particle shape.
ISSN: 1539-3755

hal-00594891
https://hal.archives-ouvertes.fr/hal-00594891
https://hal.archives-ouvertes.fr/hal-00594891/document
https://hal.archives-ouvertes.fr/hal-00594891/file/Estrada2010ReSubmitV2.pdf
ARXIV : 1105.4418

Éditeur(s) : Gauthier-Villars
Résumé : The tropical alga Caulerpa taxifolia (Vahl) C. Agardh has been displayed over the last fifteen years in tropical aquaria at the Oceanographic Museum, Monaco. Its accidental introduction into the natural environment dates from 1984. It developed first in the sea immediately below the museum, and resisted winter temperatures of 11 to 13-degrees-C. Gradually the population spread over all types of substrate, including rock, sand and mud, and over a wide range of depth, 3 to 35 m, on this relatively exposed site. In summer 1990 we became aware of its presence both to the east and to the west of Monaco. To the east, it now occurs on the whole of the eastern side of Cap Martin (3 km from Monaco) and is spreading over the west face. To the west we have observed it 150 km from Monaco near Toulon. In those sites which it colonized three years ago, its coverage now reaches 100 % over extensive areas in depths between 5 and 25 m. Areas supporting stands of Cymodocea nodosa and Posidonia oceanica are covered by fronds of C. taxifolia, which measure up to 45 cm in length. The development characteristics of the species in the Mediterranean, such as population density and frond length, are different from those in its native tropical areas. The rapid spreading of this alga is probably due both to sexual reproduction and to efficient vegetative reproduction. At the rate of spreading observed at present, further rapid extension of its range is to be feared. Moreover, wherever it becomes established, it considerably modifies the vegetal communities in the infralittoral zone. This species, like most of those in the genus Caulerpa, contains the toxin, caulerpenyn, which may play a role against other organisms such as grazers, epiphytes and competitors. This alga will be eaten only by certain animals such as the Mediterranean bream or saupe, Sarpa salpa. The toxin accumulated by fish which eat Caulerpa can render them unsuitable for human consumption, as their ingestion produces symptoms similar to those of Ciguatera poisoning. Never has a species so potentially harmful to the marine population been introduced into the Mediterranean. This biological pollution raises the major international problem of direct discharge of water having passed through aquaria or mariculture installations containing exotic species. As importing exotic marine species becomes technically easier, the lack of regulation risks further similar accidents concerning not only algae, but also metazoa and micro-organisms.
Oceanologica Acta (0399-1784) (Gauthier-Villars), 1991 , Vol. 14 , N. 4 , P. 415-426

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00101/21268/18879.pdf
http://archimer.ifremer.fr/doc/00101/21268/

Éditeur(s) : The 11th Pacific Science Inter-Congress : Pacific Countries and their Ocean: Facing Local and Global Changes. March 2 - 6, 2009 Tahiti, French Polynesia
Résumé : New Caledonian shrimp farming feasibility studies started in the mid-seventies. Today ca. 2000 tons of Litopenaeus stylirostris, introduced in 1978, are semi-intensively produced each year. Since fifteen years, production has been impacted by two seasonal vibriosis, the “Summer” syndrome caused by Vibrio nigripulchritudo in relation to pond bottom and water column quality, and the “Winter Syndrome” caused by Vibrio penaeicida in relation to drastic temperature drops . With the ambition of elucidating processes possibly leading to mortality outbreaks in ponds, Ifremer has been conducting a research program since 2003 under the DESANS project (2003-2006) and the present DEDUCTION project, equally funded by the South and North Provinces and by the Government of New Caledonia. This program has been designed in a multidisciplinary approach integrating the suspected multifactorial origin of shrimp mortalities. Environment quality in ponds (either sediment or water column) plays a major role in the shrimp ecophysiological status, influencing sensitivity to pathogens . DEDUCTION focuses on a better knowledge of phytoplankton composition and biogeochemical fluxes at the sediment-water interface in ponds. Impact of farm discharges is also investigated. In addition, a more fundamental work is conducted to understand the pathogenicity mechanisms of these two Vibrio species but also to prevent the occurrence of viral infections through a RNA interference approach. Markers of the ecophysiological status of broodstock, larvae, post-larvae and reared animals, such as enzymes testifying from an oxidative stress, are developed. Gain of performance (resistance to pathogens and growth) were obtained on hybrids of the New Caledonian and introduced Hawaiian strains. Finally the database Stylog is exploited in view of discriminating “good” from “bad” rearings on the basis of relevant indicators.
Les études de faisabilité de l'aquaculture de crevettes ont débuté en Nouvelle-Calédonie dans les années soixante dix. Aujourd'hui environ 2000 tonnes de Litopenaeus stylirostris, introduite en 1978, sont produites chaque année de façon semi-intensive. Depuis quinze ans la production a été impactée par deux vibrioses : le syndrome d'été provoqué par Vibrio nigripulchritudo en relation avec la qualité de la tranche d'eau et des fonds de bassins et le syndrome d'hiver provoqué par Vibrio penaeicida en relation avec des chutes rapides de température. Dans le but d'élucider les processus entrainant des mortalités dans les élevages, Ifremer a conduit un programme de recherche depuis 2003 dans le cadre du projet DESANS (2003-2006) puis du présent projet DEDUCTION co-financé par les provinces Nord et Sud et le Gouvernement de la Nouvelle-Calédonie. Ce programme se construit dans une démarche multidisciplinaire intégrant les origines supposées multifactorielles des mortalités de crevettes. La qualité environnementale dans les bassins (les fonds et la colonne d'eau) joue un rôle majeur dans l'état physiologique des animaux, influençant leur sensibilité aux pathogènes. DEDUCTION se focalise sur une meilleure compréhension de la composition phytoplanctonique et des flux bio-géochimiques à l'interface eau/sédiment dans les bassins.L'impact des rejets des fermes est également étudié. En outre, un travail plus fondamental est conduit pour connaître les mécanismes de pathogénicité de ces deux espèces de Vibrio mais aussi pour prévenir les occurences d'infections virales par des approches ARN Interférence. Des marqueurs de l'état physiologique des oeufs, larves, post-larves et animaux en élevage, tels que les enzymes du stress oxydant sont utilisés.Les gains de performance (résistance aux pathogènes et croissance) sont obtenus sur des hybrides issus du croisement de la souche locale avec une souche hawaienne. Finalement la base de données STYLOG est exploitée dans le but de distinguer les bonnes des mauvaises pratiques sur la base d'indicateurs fiables.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00143/25438/23591.pdf
http://archimer.ifremer.fr/doc/00143/25438/

Éditeur(s) : HAL CCSD
Résumé : Land-use changes have deep consequences on species diversity, community structure and ecosystem functioning. Consequently, many works have tried to understand the effects of such changes on the diversity and functional properties of organisms. It has been demonstrated that species traits are oftenly more important than the identity of species per se in order to account understand the ecological roles of species. Besides, while the majority of assessments about land-use change effects on ecosystem functioning have focused on primary producers, the contribution of other organisms is essential to maintain the functioning and resilience of ecosystems.Ants are interesting organisms to track land-use changes due to their abundance, ubiquity and ecological dominance. Ants are present in most of terrestrial biomes and participate in several ecosystem processes through their consumption of food resources. They are also easy to sample and standard methods exist to provide accurate comparisons between studies. While a number of studies have demonstrated abrupt changes in ant species composition along environmental gradients, only a reduced number of such studies have tried to understand how ant community changes affect ecosystem processes. Moreover, the traits responsible for the stability of ant communities in response to land-use changes are little known. It is therefore necessary to develop a methodology that enables a proper identification of ant participation to different ecosystem processes and their contribution to ecosystems’ resistance and resilience.In this thesis I aim to bring some light about i) how land-use changes affect ant community structure? ii) what traits are responsible of the ecological success of a species or it’s extinction from a given environment? iii) how changes in the species or trait composition affect the participation intensity of ants in different ecosystem processes ?
Les perturbations d’origine anthropique sont à l’origine de l’érosion de la biodiversité avec des conséquences sur la structure des communautés et pour le fonctionnement des écosystèmes. La vitesse de ces changements a stimulé de nombreuses recherches portant sur les effets de ces modifications sur la biodiversité des organismes et leurs propriétés fonctionnelles. En effet il a été montré que les traits des espèces sont plus importants que leur identité elle-même pour tenir compte de leurs rôles écologiques. Même si la majorité de ces travaux ont étudié la réponse des producteurs primaires sur les écosystèmes terrestres, la contribution d’autres organismes est toutefois essentielle pour maintenir un fonctionnement et une résilience des écosystèmes corrects.Les fourmis sont des organismes cibles intéressants pour étudier de telles modifications du fait de leur abondance et de leur dominance écologique. En effet elles ont une distribution cosmopolite et participent à de nombreuses fonctions dans l’écosystème terrestre. Elles sont également faciles à étudier et des méthodes d’échantillonnage standard existent. Bien que de nombreuses recherches aient démontré des modifications dans la composition spécifique des fourmis dans des gradients environnementaux, un nombre réduit d’entre elles ont étudié la contribution de ces organismes sur le fonctionnement des écosystèmes. De plus, les traits responsables de la stabilité des communautés de fourmis en réponse à ces modifications sont encore peu connus. Il est donc nécessaire de développer une méthodologie capable d‘identifier la participation des fourmis dans des processus écosystémiques permettant également de quantifier leur activité afin de comprendre comment ces organismes agissent sur les capacités de résistance et résilience des écosystèmes.Ainsi, cette thèse vise mettre en lumière i) en quoi la simplification des habitats liée aux activités humaines a des répercussions sur les communautés de fourmis, ii) quels sont les traits responsables du succès écologique d’une espèce ou de son déclin au sein d’un environnement donné, et iii) comment ces variations en composition spécifique impactent l’intensité de participation des fourmis aux processus écosystémiques.
https://hal.archives-ouvertes.fr/tel-01389102

NNT : 2016YANE0004
tel-01389102
https://hal.archives-ouvertes.fr/tel-01389102
https://hal.archives-ouvertes.fr/tel-01389102v2/document
https://hal.archives-ouvertes.fr/tel-01389102/file/these.pdf

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Implication of immune processes in bipolar disorder (BD) has recently gained increasing attention. Tolerogenic molecules, among which HLA-G plays a prominent role, mediate the modulation of such processes. The HLA-G locus is characterized by a high number of polymorphisms including a functionally relevant 14 base pair (bp) insertion/deletion (Ins/Del) allele affecting the HLA-G expression. Here, we analyzed the distribution of this polymorphism in 561 BD patients and 161 healthy and found that the HLA-G 14bp Ins/Ins genotype was significantly more prevalent in healthy controls than in patients (corrected p; pc=0.032) and that the prevalence of such protective genotype is lower among patients born during the winter season as compared to those born in other periods (pc=0.006). Possible mechanisms between low HLA G expression and resistance to infections as well as potential relationships between infections in early life and susceptibility to BD are discussed.
ISSN: 0198-8859

inserm-00864639
http://www.hal.inserm.fr/inserm-00864639
http://www.hal.inserm.fr/inserm-00864639/document
http://www.hal.inserm.fr/inserm-00864639/file/HLA-G_and_BD_manuscript_-1.pdf
DOI : 10.1016/j.humimm.2012.11.032

Éditeur(s) : HAL CCSD
Résumé : The spectrin-based skeleton is an essential scaffold underlying different lipid bilayers in all animal cells. Spectrins (Sp), as giant extended flexible heterotetramers (αβ)2, constitute the filaments of this network, the nodes of which are cross-linked by actin filaments. The functions of the Sp-based skeleton, which are well defined in red blood cells (required for shape, resistance to shear stress and deformability) are less well understood in non-erythroid cells.The non-erythroid Sp might participate in the establishment and/or the maintenance of specialized membrane subdomains by accumulating integral membrane proteins (such as ionic channels, ionic pumps, receptors and cell adhesion molecules) as revealed by loss of the main non-erythroid β-Sp. However the effect of non-erythroid α-Sp are less well established. In mammals, α-Sp are encoded by two genes: one for αI-Sp mainly expressed in mature erythrocyte, the second one for αII-Sp which is expressed in all nucleated cells.In the pursuit of αII-Sp functions, we have checked the effect of αII-Sp knock down by siRNA melanoma human cell line. Our data revealed that spectrin depletion is associated with i) an arrest of cell cycle at G1 state ii) a loss of cell adhesion in spite of increase in some integrins iii) some modifications of actin organisation.
Le squelette dépendant de la spectrine, localisé sous la bicouche lipidique, est un échafaudage essentiel de toutes les cellules animales. La Spectrine (Sp), structure géante, robuste mais flexible d'hétéro tétramères (αβ)2, constitue les filaments de ce réseau, dont chaque nœud interagit avec des filaments d'actine. Les fonctions du squelette de Sp, qui sont bien définies dans le globule rouge (rôle dans sa forme, dans sa résistance aux forces de cisaillement et dans sa déformabilité) sont moins bien connues dans les cellules non-érythroïdes. La Sp non-érythroïde pourrait participer à l'établissement et/ou au maintien de sous-domaines membranaires spécialisés dans l'accumulation de protéines de membrane (telles que les canaux ioniques, les pompes ioniques, les récepteurs et les molécules d'adhérence) comme nous le font penser les invalidations de la Sp-β non-érythroïde. Cependant le rôle de la Sp-α non-érythroïde est moins bien établi. Chez les mammifères, la Sp-α est codée par deux gènes: un pour Sp-αI, principalement exprimée dans l'érythrocyte mature, le second pour Sp-αII qui est exprimée dans toutes les cellules nucléées. Pour étudier les fonctions de la Sp-αII, nous avons utilisé une approche de SiRNA sur des cellules de mélanome humain. Nos données montrent que la diminution de Sp-αII est associée à I) un arrêt en G1 du cycle cellulaire II) une perte d'adhérence des cellules malgré l'augmentation de quelques intégrines III) des modifications dans l'organisation du réseau d'actine.
https://tel.archives-ouvertes.fr/tel-00377569

Droits : info:eu-repo/semantics/OpenAccess
tel-00377569
https://tel.archives-ouvertes.fr/tel-00377569
https://tel.archives-ouvertes.fr/tel-00377569/document
https://tel.archives-ouvertes.fr/tel-00377569/file/these_210409_entiere.pdf
https://tel.archives-ouvertes.fr/tel-00377569/file/II-Spectrin_Is_Critical_for_Cell_Adhesion_and_Cell_Cycle.PDF

Éditeur(s) : HAL CCSD IOS Press
Résumé : International audience
Vascular function has been found to be impaired in patients with sickle cell disease (SCD). The present study investigated the determinants of systemic vascular resistance in two main SCD syndromes in children: sickle cell anemia (SCA) and sickle cell-hemoglobin C disease (SCC). Nitric oxide metabolites (NOx), hematological, hemorheological, and hemodynamical parameters were investigated in 61 children with SCA and 49 children with SCC. While mean arterial pressure was not different between SCA and SCC children, systemic vascular resistance (SVR) was greater in SCC children. Although SVR and blood viscosity (ηb) were not correlated in SCC children, the increase of ηb (+18%) in SCC children compared to SCA children results in a greater mean SVR in this former group. SVR was positively correlated with ηb, hemoglobin (Hb) level and RBC deformability, and negatively with NOx level in SCA children. Multivariate linear regression model showed that both NOx and Hb levels were independently associated with SVR in SCA children. In SCC children, only NOx level was associated with SVR. In conclusion, vascular function of SCC children seems to better cope with higher ηb compared to SCA children. Since the occurrence of vaso-occlusive like complications are less frequent in SCC than in SCA children, this finding suggests a pathophysiological link between the vascular function alteration and these clinical manifestations. In addition, our results suggested that nitric oxide metabolism plays a key role in the regulation of SVR, both in SCA and SCC.
ISSN: 1386-0291

inserm-00849031
http://www.hal.inserm.fr/inserm-00849031
http://www.hal.inserm.fr/inserm-00849031/document
http://www.hal.inserm.fr/inserm-00849031/file/2013_Lamarre_-_Relationships_between_SVR_BR_and_NO_in_children_with_sickle_cell_anemia_or_sickle_cell-hemoglobin_C_disease.pdf
DOI : 10.3233/CH-121661

Éditeur(s) : Elsevier
Résumé : Shrimp farming is a small but growing industry in New Caledonia. Since 1993, "Syndrome 93" has been affecting New Caledonian shrimp farming industry every cold season, causing severe epizootic mortalities in grow-out ponds and significant losses. Highly pathogenic strains of Vibrio penaeicida are considered the etiological agent of the disease in Litopenaeus stylirostris. On one hand, studies demonstrated that healthy shrimp may carry V penaeicida for weeks with a high overall prevalence, regardless of any seasonal pattern or temperature conditions. On the other hand, larvae are free of V penaeicida and are also resistant to experimental infection. V penaeicida is frequently detected in incoming water pumped from the bays, which was shown, by a molecular typing study, to be the infectious source. This particular epidemiological pattern highlights the major role of the factors that trigger and aggravate the disease in grow-out ponds, where shrimp populations carry the pathogen all year round. In order to gain a better understanding of "Syndrome 93" epidemiology, quantification of V penaeicida both in shrimp and the shrimp farm ecosystem is necessary. This article describes the steps in the successful development of a real-time PCR quantification assay of V penaeicida in shrimp haemolymph, seawater (from ponds or bays) and sediment pore water, including the choice of an accurate extraction technique. The entire detection method; including sample processing, DNA extraction and real-time PCR amplification, can be completed within 4 h. (c) 2006 Elsevier B.V All rights reserved.
Journal of Microbiological Methods (0167-7012) (Elsevier), 2006-10 , Vol. 67 , N. 1 , P. 27-35

Droits : 2006 Elsevier
http://archimer.ifremer.fr/doc/2006/publication-1903.pdf
DOI:10.1016/j.mimet.2006.02.013
http://archimer.ifremer.fr/doc/00000/1903/