Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Recently it has become clear that exposure to xenobiotics may result in various forms of cell death; not only passive cell deaths like necrosis, or programmed cell deaths such as apoptosis, but also regulated necrosis, autophagy, senescence, or mitotic catastrophe. Complex cell signaling networks influence the processing of cell death. Furthermore, recent research has revealed early complex molecular interactions between organelles prior to the final triggering of cell death. The plasma membrane may play an important role in the early cell death signaling events. Regarding this latter aspect, drugs and environmental pollutants have been reported to affect plasma membrane characteristics which may further affect cell fate. Changes in membrane fluidity or in composition and function of specialized membrane microdomains (plasma membrane remodeling) have been proven to be involved in the regulation of many important physiological signaling pathways, including cell death. Furthermore, it has been suggested that a crosstalk between chemical-induced cellular membrane effects and other organelles may be of vital importance to explain the final outcome of chemical exposure. Here, we review the effects of plasma membrane remodeling on cell survival and cell death; we describe how the cell signaling pathways activated by changes in plasma membrane characteristics may influence cell fate. Since plasma membrane function plays an important role in the regulation of a number of cellular responses, it has been implicated in the development or progress of several diseases. A better knowledge of the effects of various chemicals on plasma membrane remodeling may be important for understanding the pathogenesis of major diseases, and may assist in developing new therapeutic strategies.
ISSN: 0300-483X

inserm-00818916
http://www.hal.inserm.fr/inserm-00818916
DOI : 10.1016/j.tox.2012.12.014
PUBMED : 23287390

Éditeur(s) : Université de Nantes
Résumé : The reproductive cycle of Megathura crenulata was documented and quantification of oocyte lipid reserves with lipo-specific stains was explored in both this species and in Crassostrea gigas. The necessity of providing food to female broodstock C. gigas in spring was re-evaluated, because subsequent larval and post-larval rearing performance was not affected by broodstock starvation during conditioning. Developmental study of the organs responsible of particle processing in C. gigas allowed the identification of critical stages related to the ontogenesis of each organ, as well as a better understanding of the evolution of these organs, highly-modified in the Ostreidae. Ciliary type identification and mucocyte mapping from post-larval to adult stage showed that the heterorhabdic specialization precedes the anatomic formation of gill plicae specific to this condition.
Le cycle reproducteur de Megathura crenulata a été documenté et la quantification des réserves ovocytaires par des colorants lipospécifiques a été tentée, sans résultats concluants pour cette espèce, ni pour Crassostrea gigas. L'intérêt d'une alimentation des géniteurs femelles C. gigas au printemps est re-évalué, car la performance ultérieure des élevages larvaires et post-larvaires n'a pas été affectée par le jeûne imposé lors du conditionnement. L'étude du développement des organes impliqués dans le traitement des particules chez C. gigas a permis d'identifier des stades critiques associés à l'ontogenèse de chaque organe, ainsi qu'une meilleure compréhension de l'évolution de ces organes si particuliers chez les Ostreidae. L'examen des types ciliaires et la cartographie des mucocytes de la post-larve à l'adulte ont montré que la spécialisation hétérorhabdique précède même la formation anatomique des plis branchiaux caractéristiques de cette condition.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/2005/these-1371.pdf
http://archimer.ifremer.fr/doc/00000/1371/

Résumé : Les poissons herbivores jouent un rôle écologique majeur face au phénomène de « coral-algal phase-shift », qui sévit depuis le début des années 80 dans les récifs coralliens de la Caraïbe. Dans cette étude, les habitudes alimentaires des principales espèces de poissons herbivores ont été étudiées afin de comprendre comment ces espèces utilisent et se partagent les ressources trophiques en milieu récifal et dans les herbiers. Les niches trophiques de ces espèces ont été décrites par deux méthodes complémentaires: les analyses des contenus des tractus digestifs et les analyses des isotopes stables du carbone C3C/ 12C) et de l'azoteCSN/ '4N). La qualité nutritionnelle des sources alimentaires a été évaluée par leurs concentrations de macronutriments (protéines, lipides, glucides solubles et insolubles) afin d'expliquer en partie le choix des ressources par les herbivores. Parmi les 14 espèces de poissons étudiées, appartenant aux familles des Pomacentridae, des Acanthuridae et des Scaridae, huit types de niches trophiques ont été décrits, indiquant une diversité fonctionnelle de ces espèces. Les niches trophiques décrites sont occupées par une ou plusieurs espèces, indépendamment de leur morphologie et de leurs affinités taxinomiques. Les résultats de cette étude suggèrent une complémentarité entre ces espèces, en terme d'utilisation des ressources, et soulèvent la question de leur conservation afin de préserver leur rôle écologique dans les écosystèmes côtiers de la Caraïbe.
Herbivorous fishes play a major ecological role against the « coral-algal phase-shift » phenomenon in the coral reefs of the Caribbean. In this study, the feeding patterns of the most important species of herbivorous fishes have been studied to understand how these species use and share the trophic resources on reefs and seagrass beds . Trophic niches of these species have been described by two complementary methods: the analyses oftheir digestive contents and the analyses of stable isotopes of carbon C3C/ J2C) and nitrogen (lsN/14N). The nutritional quality of the sources has been evaluated by their concentrations of macronutrients (proteins, lipids, soluble and insoluble carbohydrates) to explain partially the choice of resources by herbivorous fishes . Among the 14 studied species of herbivorous fishes (Pomacentridae, Acanthuridae and Scaridae), eight types of trophic niches have been described, indicating a functional diversity of these species . The trophic niches are occupied by one or several species, independently oftheir morphology or their taxonomie affinities. The results of this study suggest a complementarity among these species and raise the question of their conservation to preserve their ecological role on marine ecosystems of the Caribbean.

http://www.theses.fr/2013AGUY0597/document

Résumé : This report is presented by Chantal Cahu for obtaining accreditation to supervise research. Since 1981, her research activity has addressed the study of reproducers' nutrition and the young stages of development of marine organisms belonging to two different branch lines, crustaceans and fish. This work, performed in a base-lined research body, IFREMER, is placed within a more general programme of aquaculture development. Indeed, whatever species are at issue, the development of aquaculture in France, as at the global level, is based on the production of juveniles in hatcheries. My work has therefore more precisely the goal of acquiring knowledge about the nutritional needs, mechanisms of digestion and the development of these animals in order to improve the production of prawn post-larvae and fish alevin in the hatchery. This work took place in three main periods that appear in this report: - The study of reproducers' nutrition and its influence on the quality of the Penaeid prawn's eggs and larvae. My work has focused mainly on the effect of lipids and vitamins on the development of eggs and larvae. - The study of the ontogenesis of the digestive functions and the nutritional needs of sea fish larvae, with bass as the model. The goal was to determine the specific nutritional needs of the young stages by studying the implementation and regulation of pancreatic and intestinal digestive enzymes. - The study of the regulation of certain developmental genes by means of nutrients, so as to understand how these nutrients behave during ontogenesis, particularly during development of the skeleton.
Ce mémoire est présentée par Chantal Cahu pour pour l'obtention d'une habilitation a diriger des recherches. Depuis 1981, son activité de recherche concerne l'étude de la nutrition des reproducteurs et des jeunes stades de développement d'organismes marins appartenant à deux embranchements différents, les crustacés et les poissons. Ce travail réalisé dans un organisme de recherche finalisée, l'Ifremer, se situe dans un programme plus général de développement de l'aquaculture. En effet, quelles que soient les espèces en jeu, le développement de l'aquaculture en France comme au niveau mondial repose sur la production de juvéniles en écloserie. Mon travail a donc plus précisément pour objectif l'acquisition de connaissances sur les besoins nutritionnels, les mécanismes de digestion et le développement des ces animaux afin d'améliorer la production de post-larves de crevettes et d'alevins de poissons en écloserie. Ce travail s'est déroulé en trois grandes périodes qui apparaissent dans ce mémoire : - L'étude de la nutrition des reproducteurs et son influence sur la qualité des oeufs et des larves de crevettes Pénéides. Mon travail a essentiellement porté sur l'effet des lipides et des vitamines sur le développement des oeufs et des larves. - L'étude de l'ontogenèse des fonctions digestives et les besoins nutritionnels des larves de poissons marins, avec le bar comme modèle. Le but était de déterminer les besoins nutritionnels spécifiques des jeunes stades, en étudiant la mise en place et la régulation des enzymes digestives pancréatiques et intestinales. - L'étude de la régulation de certains gènes du développement par les nutriments, de façon à comprendre comment ces nutriments agissent lors de l'ontogenèse, notamment lors du développement du squelette.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/2006/rapport-2086.pdf
http://archimer.ifremer.fr/doc/00000/2086/

Éditeur(s) : HAL CCSD Microbiology Society
Résumé : International audience
An actinobacterial strain, designated ViU22(T), was isolated from a natural uranium-rich soil and was studied using a polyphasic approach. Cells formed orange-pigmented colonies, were rod-shaped, Gram-positive (non-staining method), non-motile and non-spore-forming. This organism grew in 0-4.5 % (w/v) NaCl and at 15-37 °C, with optimal growth occurring in 0.5 % (w/v) NaCl and at 30 °C. Comparative 16S rRNA gene sequence analysis revealed that the strain ViU22(T) belonged to the genus Microbacterium. It exhibited highest 16S rRNA gene sequence similarity with the type strains of Microbacterium testaceum (98.14 %) and Microbacterium binotii (98.02 %). The DNA-DNA relatedness of strains ViU22(T) with the most closely related type strains Microbacterium testaceum and Microbacterium binotii DSM 19164(T) was 20.10 % (± 0.70) and 28.05 % (± 0.35), respectively. Strain ViU22(T) possessed a type B2β peptidoglycan with partial substitution of glutamic acid by 3-hydroxy glutamic acid. The major menaquinones were MK-11 and MK-12. Major polar lipids detected in the strain ViU22(T) were diphosphatidylglycerol, phosphatidylglycerol, an unknown phospholipid and unknown glycolipids. The predominant fatty acids were anteiso-C15 : 0, anteiso-C17 : 0 and iso-C16 : 0, a pattern reported for other Microbacterium species. The major cell-wall sugars were galactose, xylose and mannose and the DNA G+C content was 71 mol%. Together, the DNA-DNA hybridization results and the differentiating phenotypic characteristics, showed that strain ViU22(T) should be classified as the type strain of a novel species within the genus Microbacterium, for which the name Microbacterium lemovicicum sp. nov. is proposed. The type strain is ViU22(T) ( = ATCC BAA-2396(T) = CCUG 62198(T) = DSM 25044(T)).
ISSN: 1466-5026

hal-01561095
https://hal-amu.archives-ouvertes.fr/hal-01561095
PUBMED : 23264499
DOI : 10.1099/ijs.0.048454-0

Éditeur(s) : Elsevier Science Bv
Résumé : There has been growing interest in the development of mud crab aquaculture in New Caledonia. However, for this to become established at a commercial level, a cost-effective formulated feed based on internationally-available ingredients needs to be developed. We have evaluated the optimal dietary protein content for juvenile crabs, Scylla serrata (Forskål, 1775), using a series of diets with a protein content ranging from 27 to 49% and soy protein concentrate (SPC) as the main protein source. For this purpose, 54 individually housed crabs were allocated to five dietary treatments (n = 10 or 11). The crabs were fed ad libitum, for 81 days with the allocated diets. The apparent digestibilities of dry mater, crude protein and energy were high (96.2-97.3%), irrespective of the diet. The voluntary feed intake (VFI) of crabs widely varied from 46 to 220 g kg- 1of fresh initial body weight per week (iBW week- 1) whatever the diet. However, SPC intake and protein intake increased significantly with dietary protein content up to the diet with 40% crude protein, but did not increase further with diets containing 44% and 49% crude protein. The cumulative molts were strongly affected by the VFI levels or energy intake and also, to a lesser extent, by the levels of SPC or protein in diets. Two phases in tissue gain were observed after ecdysis: an initial deposition phase lasting around 30 days followed by a plateau which lasted until the next molt. The daily tissue growth was 16.5% of dry body weight (dry BW) one day after ecdysis and dramatically decreased to 3.6% of dry BW over the first 10 days, then decreased more slowly to the minimum value of 1.3% of dry BW over the next 70 days. During the course of experiment, the best growth (tissue growth and molt frequency) and the best feed efficiency (FCR, PER, retention of proteins and lipids) were obtained with crabs fed on the diet with 40% crude protein. This result was confirmed by a bioenergetic study which showed significantly higher allocation of the energy intake for growth (RE) of crabs fed on diet 40% crude protein. Finally, under our experimental conditions, 1 kg of juvenile crabs required 6.5 ± 1.1 g of protein per day. This level was obtained with the diet SPC-42 that contained 40% of protein of which almost three quarters were derived from SPC. Two hypotheses are proposed to explain the negative effect of high level of SPC or protein on growth and feed efficiency for crabs fed on in diets containing 52% and 60% SPC.
Aquaculture (0044-8486) (Elsevier Science Bv), 2014-10 , Vol. 434 , P. 499-509

Droits : 2014 Elsevier B.V. All rights reserved.
http://archimer.ifremer.fr/doc/00211/32196/30630.pdf
http://archimer.ifremer.fr/doc/00211/32196/

Éditeur(s) : HAL CCSD Springer Verlag (Germany) Springer Verlag
Résumé : International audience
Apoptosis has emerged as a fundamental process important in tissue homeostasis, immune response, and during development. CD95 (also known as Fas), a member of the tumor necrosis factor receptor (TNF-R) superfamily, has been initially cloned as a death receptor. Its cognate ligand, CD95L, is mainly found at the plasma membrane of activated T-lymphocytes and natural killer cells where it contributes to the elimination of transformed and infected cells. According to its implication in the immune homeostasis and immune surveillance, and since several malignant cells of various histological origins exhibit loss-of-function mutations, which cause resistance towards the CD95-mediated apoptotic signal, CD95 has been classified as a tumor suppressor gene. Nevertheless, this assumption has been recently challenged, as in certain pathophysiological contexts, CD95 engagement transmits non-apoptotic signals that promote inflammation, carcinogenesis or liver/peripheral nerve regeneration. The focus of this review is to discuss these apparent contradictions of the known function(s) of CD95.
ISSN: 1420-682X

hal-00682466
https://hal.archives-ouvertes.fr/hal-00682466
DOI : 10.1007/s00018-011-0866-4
PUBMED : 22042271

Éditeur(s) : HAL CCSD Nature Publishing Group
Résumé : International audience
Epithelial-to-mesenchymal transition (EMT) promotes cell motility, which is important for the metastasis of malignant cells, and blocks CD95-mediated apoptotic signaling triggered by immune cells and chemotherapeutic regimens. CD95L, the cognate ligand of CD95, can be cleaved by metalloproteases and released as a soluble molecule (cl-CD95L). Unlike transmembrane CD95L, cl-CD95L does not induce apoptosis but triggers cell motility. Electron paramagnetic resonance was used to show that EMT and cl-CD95L treatment both led to augmentation of plasma membrane fluidity that was instrumental in inducing cell migration. Compaction of the plasma membrane is modulated, among other factors, by the ratio of certain lipids such as sphingolipids in the membrane. An integrative analysis of gene expression in NCI tumor cell lines revealed that expression of ceramide synthase-6 (CerS6) decreased during EMT. Furthermore, pharmacological and genetic approaches established that modulation of CerS6 expression/activity in cancer cells altered the level of C16-ceramide, which in turn influenced plasma membrane fluidity and cell motility. Therefore, this study identifies CerS6 as a novel EMT-regulated gene that has a pivotal role in the regulation of cell migration.Oncogene advance online publication, 17 March 2014; doi:10.1038/onc.2014.55.
ISSN: 0950-9232

hal-01063558
https://hal.archives-ouvertes.fr/hal-01063558
https://hal.archives-ouvertes.fr/hal-01063558/file/Down-regulation%20of%20ceramide_accepted.pdf
DOI : 10.1038/onc.2014.55
PUBMED : 24632610

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 Histochemical Society
Résumé : International audience
The galectin-4 protein is mostly expressed in the digestive tract and is associated with lipid raft stabilization, protein apical trafficking, wound healing, and inflammation. While most mammalian species, including humans, have a single Lgals4 gene, some mice have two paralogues: Lgals4 and Lgals6. So far, their significant similarities have hindered the analysis of their respective expression and function. We took advantage of two antibodies that discriminate between the galectin-4 and galectin-6 proteins to document their patterns of expression in the normal and the dextran sodium sulfate (DSS)-damaged digestive tract in the mouse. In the normal digestive tract, their pattern of expression from tongue to colon is quite similar, which suggests functional redundancy. However, the presence of galectin-4, but not galectin-6, in the lamina propria of the DSS-damaged colon, its association with luminal colonic bacteria, and differences in subcellular localization of these proteins suggest that they also have distinct roles in the normal and the damaged mouse digestive tract. Our results provide a rare example of ancestral and derived functions evolving after tandem gene duplication.
ISSN: 0022-1554

hal-01544764
https://hal.archives-ouvertes.fr/hal-01544764
DOI : 10.1369/0022155413478612

Éditeur(s) : Actes de colloques Ifremer, Tahiti, French Polynesia, 20 Feb - 4 Mar 1989, n°9, chap. 17, pp.171-181
Résumé : Symptoms recalling a nutritional pathology and more precisely a process of lipid peroxydation were observed during the last years in seabass Dicentrarchus labrax and other fishes cultured in tropical marine condition, Ocyurus chrysurus and Lutjanus analis . They included dark coloration, skin ulceration, lethargy, anorexy, emaciation. Histological examinations showed hepatic fatty degenerative lesions, pancreatitis, muscular degeneration and retinal atrophy. Additional vitamins E and C in the food suppressed that pathological symptoms. The previously evoked clinical or histological signs were not achieved in spite of an increase of the level of hepatic, muscular or blood malondialdehyde and of the conjugated dienes of the perivisceral fat. In the same time, hepatic and muscular tocopherol decreased. These experiments also showed the feasibility and the interest of different analyses in the characterization of such a pathology: hemolysis test and activity of enzymes such as erythrocytic catalase or superoxyde dismutase and plasma glutathione peroxydase. Another nutritional disease is worth describing again, the Granulomatous Hypertyrosinaemia. It was essentially investigated in turbot Scophtalmus maximus but other fish species such as sea bream Chrysophris aurata are often affected.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/1989/acte-1501.pdf
http://archimer.ifremer.fr/doc/00000/1501/