Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
The scleractinian coral Pocillopora damicornis type β is known to present a mixed reproduction mode: through sexual reproduction, new genotypes are created, while asexual reproduction insures their propagation. In order to investigate the relative proportion of each reproduction mode in P. damicornis type β populations from Reunion Island, Indian Ocean, clonal propagation along the west coast was assessed through four sampling sites with increasing geographical distance between sites. Coral colonies were sampled either exhaustively, randomly or haphazardly within each site, and genotypic diversity was assessed using 13 microsatellite loci over a total of 510 P. damicornis type β determined a posteriori from their mtDNA haplotype (a 840 bp sequenced fragment of the Open Reading Frame). Overall, 47% of all the sampled colonies presented the same multi-locus genotype (MLG), a superclone, suggesting that asexual propagation is extremely important in Reunion Island. Within each site, numerous MLGs were shared by several colonies, suggesting local clonal propagation through fragmentation. Moreover, some of these MLGs were found to be shared among several sites located 40 km apart. While asexual reproduction by fragmentation seems unlikely over long distances, our results suggest a production of parthenogenetic larvae. Despite shared MLGs, two differentiated clusters were enclosed among populations of the west coast of Reunion Island, revealing the necessity to set up appropriate managing strategies at a local scale.
ISSN: 1932-6203

hal-01450078
http://hal.univ-reunion.fr/hal-01450078
DOI : 10.1371/journal.pone.0169692

Éditeur(s) : HAL CCSD Wiley
Résumé :  
Drier periods from the late Pleistocene and early Holocene have been hypothesized to have caused the disappearance of various rainforest species over large geographical areas in South America and restricted the extant populations to mesic sites. Subsequent improvement in climatic conditions has been associated with recolonization. Changes in population size associated with these extinction-recolonization events should have affected genetic diversity within species. However, these historical hypotheses and their genetic consequences have rarely been tested in South America. Here, we examine the diversity of the chloroplast and nuclear genomes in a Neotropical rainforest tree species, Vouacapoua americana (Leguminosae, Caesalpinioideae) in French Guiana. The chloroplast diversity was analyzed using a polymerase chain reaction-restriction fragment length polymorphism method (six pairs of primers) in 29 populations distributed over most of French Guiana, and a subset of 17 populations was also analyzed at nine polymorphic microsatellite loci. To determine whether this species has experienced extinction-recolonization, we sampled populations in areas supposedly not or only slightly affected by climatic changes, where the populations would not have experienced frequent extinction, and in areas that appear to have been recently recolonized. In the putatively recolonized areas, we found patches of several thousands of hectares homogeneous for chloroplast variation that can be interpreted as the effect of recolonization processes from several geographical origins. In addition, we observed that, for both chloroplast and nuclear genomes, the populations in newly recolonized areas exhibited a significantly smaller allelic richness than others. Controlling for geographic distance, we also detected a significant correlation between chloroplast and nuclear population differentiation. This result indicates a cytonuclear disequilibrium that can be interpreted as a historical signal of a genetic divergence between fragmented populations. In conclusion, the spatial genetic structure of contemporary V. americana populations shows evidence that this species has experienced large extinction-recolonization events, which were possibly caused by past climatic change.
ISSN: 0014-3820

hal-01032194
https://hal.archives-ouvertes.fr/hal-01032194
DOI : 10.1111/j.0014-3820.2003.tb01517.x

Éditeur(s) : Actes Journées Conchylicoles, Ifremer Nantes, 3-4 avril 2001
Résumé : Mangrove oysters include various species that are also present on different coasts. In the southern part of the Atlantic Ocean, Crassostrea rhizophorae has been observed along the southern coast of America and Crassostrea gasar along the western coast of Africa. Fifteen populations of these oysters were sampled from these two geographic areas. Their polymorphism was studied on the 16S mitochondrial fragment both by par sequencing and RFLP analysis. Some samples' caryotype were also analysed. Two haplotypes were identified: C. gasar was found in Africa, but also for the first time in South America, whereas C. rhizophorae was only found on the coasts of South America.
Les huîtres de mangrove englobent plusieurs espèces qui sont présentes sur différentes côtes. Dans la partie sud de l'Océan Atlantique, Crassostrea rhizophorae a été décrite le long des côtes sud américaines et Crassostrea gasar le long des côtes ouest africaines. Quinze populations de ces huîtres ont été échantillonnées dans ces deux zones géographiques. Leur polymorphisme a été étudié sur le fragment mitochondrial 16S par séquençage et analyse en RFLP, le caryotype de certains échantillons a aussi été examiné. Deux haplotypes ont été identifiés: le type C. gasar a été trouvé en Afrique, mais aussi pour la première fois en Amérique du Sud, alors que le type C. rhizophorae a été rencontré seulement sur les côtes d'Amérique du Sud.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/2001/acte-3278.pdf
http://archimer.ifremer.fr/doc/00000/3278/

Éditeur(s) : Universite Montpellier II
Résumé : Since 1980, the expansion of a green macro-alga: Valonia aegagropila (C Agardh) is observed in Salses-Leucate lagoon (France). It is currently distributed in the north of the lagoon with important biomasses (40 gDW/m²) eroding the cover of Zostera noltii. The free form of the alga can be transported with the surface or bottom currents depending on seasons. It multiplies mainly by vegetative reproduction. There are few studies on the ecophysiological capacities of V. aegagropila. This work tries to answer why (physiological adaptation) and how (mechanical process of transport) the alga invaded the lagoon, with an approach including observations, experiments in controlled environment and biological and hydrodynamic models. The growth capacities depend on temperature and light intensities, the nutrients absorption rates and internal nitrogen and phosphorus internal quotas were measured and modelled using a Droop model based on internal quota. Vertically transport was studied with laboratory experiments and measurements of biomass transport were made into the lagoon. The biological model (growth, vertical transport, mortality) was coupled to the MARS 3D hydrodynamic model with a meshgrid of 160m. The results show an adaptation of the alga to low availability of phosphorus and an annual growth of biomass controlled by the availability of nutrient during winter. The alga seems to occupy the whole zones where growth is optimal and the risk of invasion of the southern part of the lagoon is limited. This work opens on research prospects on an ecological model (confronting physiological capacities and competition of V. aegagropila, Zostera noltii, green algae and primary production), new physiological experiments, ecological observations and potential valorisation of V. aegagropila.
Depuis 1980, est observée dans l'étang de Salses-Leucate l'expansion d'une macro-algue verte : Valonia aegagropila (C. Agardh). En 2004, elle était présente sur la presque totalité de la moitié nord de la lagune avec des biomasses importantes (jusqu'à 600 gPS/m²). L'algue envahit et érode également la couverture d'herbiers garant de la biodiversité, de la productivité et de la stabilité de l'écosystème. V. aegagropila se reproduit essentiellement de manière végétative (fragmentation des thalles) et possède la particularité de retenir de l'oxygène de la photosynthèse dans sa structure sphérique. Cet oxygène piégé lui donne la possibilité de mouvement sur la verticale et d'être transportée dans le domaine par les courants. Les conditions physico-chimiques de l'étang présentent de fortes variations saisonnières en salinité, en température et en turbidité, ainsi que des apports nutritifs faibles : la production primaire est principalement limitée par le phosphore. Il existe malheureusement peu d'informations sur V. aegagropila ainsi que trop peu de connaissances sur son écophysiologie. Elle semble vivre dans des milieux plutôt oligotrophe dans des régions tropicales à sub-tropicales. Ce travail basé sur une approche d'observations de terrain, d'expérimentations en milieu contrôlé (en laboratoire) et de modélisation des processus, a permis d'une part d'explorer les capacités adaptatives physiologiques de V. aegagropila aux conditions environnementales de l'étang et d'autre part de mettre à jour les modes de fonctionnement de la dynamique spatio-temporelle de la population. Les capacités de croissance ont été mesurées sur un large spectre de température et de lumière. Les capacités d'absorption des sels nutritifs dans l'eau et les facultés de l'algue à stocker l'azote et le phosphore dans ses tissus ont également été étudiées. D'autre part, un modèle de dynamique des populations a été conceptualisé puis développé. Les processus pris en compte dans ce modèle sont la croissance de l'algue (modèle à quota interne), la flottabilité de l'algue et la mortalité par surdensité. Ces processus ont été paramétrés en majeure partie par des expérimentations réalisées en laboratoire. Ce modèle 0D a par la suite était couplé au modèle hydrodynamique MARS3D (modèle Ifremer) mis en place sur la lagune de Salses-Leucate, utilisant deux grilles de calcul (160m ou de 80m de résolution). Les simulations réalisées permettent d'appréhender les capacités spatio-temporelles de la croissance de l'algue dans l'étang, le turnover annuel de la biomasse totale et les attracteurs de biomasse du système sous différents évènements météorologiques. Ces résultats sont comparés avec les répartitions cartographiques de la population observées in situ en 1999 et 2004 et des flux de biomasses mesurés au cours d'observations de terrain entre juin 2003 et septembre 2004. L'ensemble des résultats montre d'une part une adaptation de l'algue à évoluer dans un milieu pauvre en phosphore et d'autre part une croissance annuelle de la biomasse totale qui est principalement contrôlée par les apports hivernaux en sels nutritifs dans la lagune. Les résultats des simulations montrent également que V. aegagropila semble occuper à présent la majeure partie des zones favorables à sa croissance. Il est également montré que si sa capacité de mouvement peut favoriser la dispersion d'individus dans la lagune et accélérer la croissance de la population pour de faibles biomasses initiales, cette même capacité de mouvement joue plutôt un rôle de régulation de la population lorsque la biomasse totale devient importante. On peut penser que le risque de colonisation de l'herbier à zostère de la partie sud de la lagune (bassin de Salses) est limité. Ce travail ouvre enfin des perspectives de recherche sur l'amélioration du modèle de dynamique des populations de l'espèce, sur de nouvelles expérimentations à réaliser ou encore sur la surveillance écologique du milieu. Des propositions sont faites pour concevoir un modèle écologique confrontant les capacités physiologiques des macrophytes (algues vertes, Valonia et zostères) afin d'apréhender les phénomènes de compétitions et les modes de fonctionnement du réseau trophique de la lagune de Salses- Leucate. Des pistes sur la valorisation de la matière algale de V. aegagropila sont enfin proposées.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/2006/these-2453.pdf
http://archimer.ifremer.fr/doc/00000/2453/

Éditeur(s) : HAL CCSD Springer Verlag/EDP Sciences
Résumé : No efficient method is available to compare multi-locus estimates of diversity while taking into account inter-locus and inter-population stochastic variance. The advent of genome scan approaches makes the development of such tests absolutely necessary. We developed a method to compare genome-wide diversity estimates while taking into account-and factoring out-variation in census size and making use of inter-locus variance to assess significance of differences in diversity levels. An approach based on rarefaction with bootstrap re-sampling (RaBoT) was implemented into a test of multi-locus comparison of diversity coded in R. The properties of the test were studied by applying it to simulated populations with varying diversity levels and varying differences in diversity levels. The test was then applied to empirical data from disturbed and undisturbed populations of Virola michelii (Myristicaceae) genotyped at 693 amplified fragment length polymorphism (AFLP) markers. RaBoT was found to be rather conservative, with large numbers of false negatives when the diversity in the compared populations was similar, and false positives mostly associated to comparisons of populations with extremely high levels of diversity. When applied to empirical data, RaBoT detected higher genetic diversity in a post-disturbance than in an undisturbed population and lower genetic diversity in a seedling than in the corresponding adult population, but it also revealed differences in diversity between subgroups within the disturbed and undisturbed plots. RaBoT is a sensitive method to compare multi-locus levels of diversity that can be applied both at the genotype level for dominant markers (e.g. AFLP) and at the allele level for biallelic codominant markers (e.g. single-nucleotide polymorphisms).
ISSN: 1286-4560

hal-01032413
https://hal.archives-ouvertes.fr/hal-01032413
DOI : 10.1007/s13595-013-0302-z

Éditeur(s) : HAL CCSD
Résumé : Background and objectives.[br/] Dairy propionibacteria are isolated from various ecological niches, including soil, grass, silage, rumen, raw milk and dairy plants, showing great adaptability and robustness. Used as ripening starters in Swiss type cheeses, these food grade bacteria are described as nutraceutical producers and they release into the external medium short chain fatty acids (SCFA), folic acid, cobalamin and the bifidogenic 1,4- dihydroxy-2-naphthoic acid (DHNA). These compounds are known to play a pivotal role in the modulation of intestinal physiology through diet. Considering the pro-apoptotic potential of some of these metabolites, we investigated the potential of dairy products fermented by the main species, Propionibacterium freudenreichii, to prevent colon carcinogenesis. Methods.[br/] We developed a new fermented milk. Taking advantage of milk fractions, high and stable populations of P. freudenreichii were obtained in this product. It was tested in vitro on gastric HGT-1 and colic HT-29 cells with respect to the typical hallmarks of apoptosis. In vivo, the fermented milk was evaluated in piglets with respect to general health parameters and in human microbiota-associated rats, treated or not with dimethylhydrazine (DMH), with respect to intestinal proliferation and apoptosis. Results. Fermented milk induced cell death in both gastric and colon cancer cells. Cellular and molecular characterization of cells dying in response to SCFA treatment revealed cell cycle arrest, drop in intracellular ATP, depolarization of mitochondria, translocation of key apoptosis proteins, processing of caspases and fragmentation of the nucleus. Interestingly, the new fermented milk was shown to potentiate the cytotoxic effect of molecules used in cancer chemotherapy. In accordance, it modulated expression of key apoptotic proteins. In vivo, the fermented milk was evaluated in piglets. Daily oral gavage led to high colic P. freudenreichii populations, to modulation of the intestinal microbiota and modulation of intestinal cytokines. Promotion of piglets’ growth also revealed general probiotic effects of fermented milk. Considering that propionibacteria were metabolically active in the intestine, we further investigated their impact on colon carcinogenesis (induced by dimethylhydrazine, DMH) in human microbiota-associated rats. Consumption of selected strains of propionibacteria resulted in enhanced apoptotic depletion of DMH damaged epithelial cells, yet had no effect on neither proliferation nor apoptosis in healthy rats. Conclusions and perspectives.[br/] These results open new perspectives in the field of colon cancer cells prevention and/or treatment. The synergy with pro-apoptotic chemotherapy molecules suggests that such a fermented product may be proposed as a food supplement to enhance the effects of anticancer treatments.
colloque international « Nutrition and Cancer : Hot topics from biology to public health issues »
Paris, France

hal-01190452
https://hal.archives-ouvertes.fr/hal-01190452
PRODINRA : 201853

Éditeur(s) : HAL CCSD Wiley
Résumé : The extent of gene dispersal is a fundamental factor of the population and evolutionary dynamics of tropical tree species, but directly monitoring seed and pollen movement is a difficult task. However, indirect estimates of historical gene dispersal can be obtained from the fine-scale spatial genetic structure of populations at drift-dispersal equilibrium. Using an approach that is based on the slope of the regression of pairwise kinship coefficients on spatial distance and estimates of the effective population density, we compare indirect gene dispersal estimates of sympatric populations of 10 tropical tree species. We re-analysed 26 data sets consisting of mapped allozyme, SSR (simple sequence repeat), RAPD (random amplified polymorphic DNA) or AFLP (amplified fragment length polymorphism) genotypes from two rainforest sites in French Guiana. Gene dispersal estimates were obtained for at least one marker in each species, although the estimation procedure failed under insufficient marker polymorphism, limited sample size, or inappropriate sampling area. Estimates generally suffered low precision and were affected by assumptions regarding the effective population density. Averaging estimates over data sets, the extent of gene dispersal ranged from 150 m to 1200 m according to species. Smaller gene dispersal estimates were obtained in species with heavy diaspores, which are presumably not well dispersed, and in populations with high local adult density. We suggest that limited seed dispersal could indirectly limit effective pollen dispersal by creating higher local tree densities, thereby increasing the positive correlation between pollen and seed dispersal distances. We discuss the potential and limitations of our indirect estimation procedure and suggest guidelines for future studies
ISSN: 0962-1083

hal-01031603
https://hal.archives-ouvertes.fr/hal-01031603
DOI : 10.1111/j.1365-294X.2005.02785.x

Éditeur(s) : HAL CCSD
Résumé : Food-grade dairy propionibacteria release beneficial short chain fatty acids (SCFAs), folic acid and cobalamin. They induce apoptosis via the mitochondrial death pathway. We investigated their synergy with drugs used in gastric and colorectal cancer.Fermented milk containing propionibacteria and SCFAS acetate and propionate, as well as its cell-free supernatant, induced apoptosis in gastric HGT-1 and colic HT-29. Characterization of cells revealed apoptosis induction evidenced by chromatin condensation, DNA laddering, emergence of a subG1 population, phosphatidylserine exposure at the plasma membrane outer leaflet and cytochrome c release. Interestingly, the fermented milk was shown to potentiate the cytotoxic effect of molecules used in cancer chemotherapy, camptothecin and TRAIL (TNF Related Apoptosis Inducing Ligand).These results open new perspectives in the field of colon cancer cells prevention and/or treatment. Such a fermented product, or the propionibacterium alone, may be proposed as a food supplement to enhance the effects of anticancer treatments.
Les bactéries propioniques laitières produisent des acides gras volatils (AGV), acide folique et cobalamine, composés bénéfiques. Elles induisent l’apoptose via la voie mitochondriale. Nous avons recherché leur synergie avec des drogues utilisées dans le cancer gastrique ou colique.Un lait fermenté contenant des bactéries propioniques et les AGVs propionate et acétate a induit l’apoptose de cellules gastriques HGT-1 et coliques HT-29. L’étude des cellules a révélé l’induction de l’apoptose : condensation de la chromatine, fragmentation de l’ADN, l’émergence d’une population subG1, l’externalisation des phosphatidylserines et le relargage du cytochrome c. De manière intéressante, le lait fermenté a potentialisé les effets cytotoxiques de molécules utilisées en chimiothérapie, camptothécine et TRAIL (TNF Related Apoptosis Inducing Ligand).Ces résultats ouvrent de nouvelles perspectives dans le domaine du traitement ou de la prévention des cancers digestifs. Un tel produit fermenté, ou les propionibactéries seules, pourrait être proposé comme supplément alimentaire pour augmenter l’efficacité de traitements anti-cancéreux.
5. Colloque Intenational Molécules & Ingrédients Santé
Quimper, France

hal-01204307
https://hal.archives-ouvertes.fr/hal-01204307
PRODINRA : 261444

Éditeur(s) : HAL CCSD Elsevier
Résumé : Over-exploitation and fragmentation are serious problems for tropical forests. Most sustainable forest management practices avoid clear-cuts and apply selective logging systems focused on a few commercial species. We applied a simulation model to estimate the impact of such selective logging scenarios on the genetic diversity and demography of four tropical tree species from French Guiana. The simulations used data on genetic and demographic composition, growth, phenology and pollen and seed dispersal obtained for Dicorynia guianensis, Sextonia rubra, Symphonia globulifera and Vouacapoua americana at the experimental site in Paracou. Whereas Symphonia globulifera serves as a model for a species with low logging pressure, the other three species represent the most exploited tree species in French Guiana. In simulations with moderate logging, typical for French Guiana, with large cutting diameter (>60 cm diameter) and long cutting cycles (65 years), the two species V. americana and Sextonia rubra were not able to recover their initial stock at the end of the rotation period, with a large decrease in the number of individuals and in basal area. Under a more intensive logging system (cutting diameter >45 cm diameter, cutting cycles of 30 years) that is common practice in the Brazilian Amazon, only Symphonia globulifera showed no negative impact. Generally, the differences between the genetic parameters in the control scenarios without logging and the logging scenarios were surprisingly small. The main reasons for this were the overlapping of generations and the effective dispersal ability of gene vectors in all species, which guarantee relative homogeneity of the genetic structure in different age classes. Nevertheless, decreasing the population size by logging reduced the number of genotypes and caused higher genetic distances between the original population and the population at the end of the logging cycles. Sensitivity analysis showed that genetic changes in the logging scenarios were principally determined by the growth, densities and cutting diameter of each species, and only to a very small extent by the reproductive system including factors such as pollen and seed dispersal and flowering phenology
ISSN: 0006-3207

hal-01032050
https://hal.archives-ouvertes.fr/hal-01032050
DOI : 10.1016/j.biocon.2006.02.014

Éditeur(s) : Université de Bretagne Occidentale
Résumé : Several small pelagic fish species contribute remarkably to world catch. Their populations are, however, characterized by large biomass fluctuations strongly affecting fisheries. The fishing gears and methods used to capture small pelagics have evolved to exploit the highly developed shoaling behavior of these species. Hence, faced to modern fishing this gregarious behavior becomes a disadvantage for fish. Fish behavior may be affected by environmental conditions and by fishing, at the same time that behavior impacts fishing. In this study, we seek to characterize the aggregative systems of small pelagic fishes inhabiting the Bay of Biscay by analyzing "acoustic images", defined as the group of echoes (planktonic layers, shoals, isolated targets) detected on a transect section of a given length. We analyzed the species composition, the spatial distribution and the evolution over time of acoustic images. We also studied the hydrological conditions of the bay, as well as the small pelagics French fishery in order to look for correlations between hydrology, commercial catch and fish aggregation patterns observed by acoustics. We observed the same species or group of species forming different types of aggregation according to habitat. Conversely, the same type of aggregation, associated with a particular habitat, can be produced by different species. The most notorious change observed during the studied period relates to small clupeoids aggregations in the vicinity of the Gironde estuary, whose structure evolved toward a greater fragmentation of shoals (a large number of small size detections) since 2000. Concerning commercial catches, pelagic trawlers fishing in pairs mainly seek for anchovy in the coastal areas, single pelagic trawlers capture mackerel and horse mackerel in deeper waters while purse seiners target mostly sardine near their fishing ports. Because of the coarse spatial resolution of commercial fishing data and the effect of the application of an international fisheries agreement limiting the fishing activity of French pelagic trawlers during spring, only small correlations between captures and types of aggregation were observed.
La participation des petits poissons pélagiques dans les captures est remarquable. Leurs populations sont cependant caractérisées par des importantes fluctuations de biomasse, impactant fortement les pêcheries. Les méthodes et appareils de pêche utilisés pour capturer ces espèces ont évolué dans le sens d'exploiter le comportement grégaire très développé des petits pélagiques. Cette tendance à former de bancs devient alors désavantageuse pour le poisson face à la pêche moderne. Les conditions environnementales et la pêche peuvent affecter le comportement du poisson, en même temps que ce dernier est susceptible d'affecter l'activité halieutique. Le but de cette étude est de caractériser les systèmes agrégatifs des petits poissons pélagiques dans le golfe de Gascogne en étudiant des « images acoustiques », définies comme l'ensemble des échos (couches planctoniques, bancs, cibles isolées) détectés sur une section de radiale de longueur donnée. Nous analysons leur composition en espèces ainsi que leur distribution spatiale et leur évolution au cours du temps. Nous étudions aussi les conditions hydrologiques du golfe, ainsi que la pêcherie française de ces espèces afin de chercher des corrélations entre l'hydrologie, la capture commerciale et les types d'agrégations observés par acoustique. Nous avons observé qu'une espèce est capable de former des agrégations différentes en fonction de l'habitat, et inversement, le même type d'agrégation, associé à un habitat particulier, peut être produit par des espèces différentes. Le changement observé le plus évident concerne les agrégations de petits clupéiformes, dont la structure a évolué vers une plus grande fragmentation des détections (des petits bancs plus nombreux) depuis 2000. Par rapport à la pêche des professionnels, les chalutiers pélagiques en boeufs recherchent en priorité l'anchois dans la zone côtière, les pélagiques simples capturent le chinchard et le maquereau au large et les senneurs recherchent principalement la sardine à proximité des ports de pêche. À cause de la résolution spatiale trop sommaire des données de pêche et l'effet de l'application des accords internationaux limitant l'activité des chalutiers pélagiques au printemps, nous n'avons observé que peu des corrélations entre les captures et les types d'agrégation établis à partir de données issues des campagnes scientifiques.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/2008/these-6083.pdf
http://archimer.ifremer.fr/doc/00000/6083/

Éditeur(s) : Inter-Research
Résumé : The marine environment is of special interest for studying hybridization between closely related taxa because of the high dispersal potential of planktonic larvae, such as those of most bivalve species. The oysters Crassostrea angulata and C. gigas are known to be very close genetically and entirely inter-fertile under controlled conditions. However, hybridization in the wild had not been investigated, mainly due to the lack of nuclear diagnostic markers. In the present paper, we first estimated genetic differentiation between these 2 closely related taxa using 8 microsatellite markers. Interestingly, 5 markers displayed significant differences of allele size between taxa. The subsequent sequencing of alleles of one of these microsatellites showed several mutational events, which suggested null alleles and homoplasy. The presence of 1 insertion/deletion event in its 5' flanking sequence enabled us to design a new bi-allelic ('C' and 'NC') nuclear PCR-restriction fragment length polymorphism (-RFLP) marker (CG44R). This, together with a mitochondrial DNA marker, was used to analyze populations of C. angulata and C. gigas. The CG44R allele frequencies were very different between C. angulata (f[C] = 0.91) and C. gigas (f[NC] = 0.92) populations. This analysis also provided evidence for hybridization between C. angulata and C. gigas in a wild Portuguese population where the 2 taxa are in contact due to recent transportation of C. gigas stocks for aquacultural production. Our results represent the first indication of hybridization between these 2 taxa in the natural environment, and contribute to knowledge of the evolutionary history of the Crassostrea genus.
Marine Ecology Progress Series (0171-8630) (Inter-Research), 2004 , Vol. 272 , P. 141-152

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/2004/publication-3355.pdf
http://archimer.ifremer.fr/doc/00000/3355/

Éditeur(s) : HAL CCSD
Résumé : International audience
The host-parasite genera Proformica-Rossomyrmex present four pairs of species with a very wide range of distribution from China to Southeastern Spain, from huge extended plains to the top of high mountains. Here we review (1) the published data on these pairs in comparison to other slave-makers; (2) the different dispersal ability in hosts and parasites inferred from genetics (chance of migration conditions the evolutionary potential of the species); (3) the evolutionary potential of host and parasite determining the coevolutionary process in each host-parasite system that we treat to define using cuticular chemical data. We find a lower evolutionary potential in parasites than in hosts in fragmented populations, where selective pressures give advantage to a limited female parasite migration due to uncertainty of locating a host nest. A similar evolutionary potential is detected for hosts and parasites when the finding of host nests is likely (i.e., in continuous and extended populations). Moreover, some level of local adaptation at CHC profiles between host and parasite exists independently of the kind of geographic distribution and the ability of dispersal of the different populations. Similarity at CHC profiles appears to be a trait imposed by natural selection for the interaction between hosts and slave-makers.
Psyche

hal-01322574
https://hal.archives-ouvertes.fr/hal-01322574
DOI : 10.1155/2013/541804

Éditeur(s) : Université de Tours
Résumé : L 'huître creuse japonaise Crassostrea gigas et portugaise C. angulata ont été respectivement décrites par Thunberg (1793) et Lamarck (1819). Mais les similitudes morphologiques et l 'homogénéité des fréquences allozymiques entre populations ont conduit de nombreux auteurs à proposer l'existence d'une seule et mênle espèce. L'analyse récente d'un gène mitochondrial a pennis de déterminer l'origine asiatique de C. angulata, soulignant l'intérêt de l'étude de la différenciation génétique et phénotypique entre les deux taxons. La notion biologique d'espèce a tout d'abord été examinée. Des croisements de 1ère et 2ème génération ont montré la viabilité et fertilité des hybrides. L'analyse de la compétition spennatique par marqueurs microsatellites ne montre pas d'isolement reproductif, mênle partiel et le séquençage du fragment ITS 1 confirme la forte proximité génétique des deux taxons. Les patrons de différenciation génétique observés par marqueurs microsatellites et mitochondriaux apparaissent sitnilaires. L'origine asiatique de C. angulata est donc confinnée. Le fort niveau de polymorphisme des marqueurs microsatellites explique partiellement les plus faibles valeurs observées de différenciation. Une bimodalité des tailles d'allèles microsatellites entre taxons a pennis le développement d'un nouveau marqueur nucléaire, mettant en évidence des phénomènes d'hybridation naturelle dans la zone du sud de l'Europe où l'activité ostréicole met aujourd'hui les 2 taxons en contact. L'étude de caractères phénotypiques a été réalisée en milieu naturel et contrôlé sur des descendances d'écloserie. Les résultats montrent une meilleure croissance de C. gigas et une période de reproduction plus longue chez C. angulata. Des mesures physiologiques montrent un plus fort taux de respiration du naissain C. gigas, ainsi qu'un temps de filtration supérieur chez les adultes. La différence de croissance entre taxons pourraient donc être expliquée par le temps de filtration et l'effort de reproduction.

Droits : Université de Tours, The author
http://archimer.ifremer.fr/doc/00034/14564/11867.pdf
http://archimer.ifremer.fr/doc/00034/14564/

Éditeur(s) : HAL CCSD Wiley
Résumé :  
The chloroplast genome has been widely used to describe genetic diversity in plant species. Its maternal inheritance in numerous angiosperm species and low mutation rate are suitable characters when inferring historical events such as possible recolonization routes. Here we have studied chloroplast DNA variation using PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism) with seven pairs of primers and four restriction enzymes in 14 populations of Vouacapoua americana (Caesalpiniaceae) a neotropical tree sampled throughout French Guiana. Population diversity (Hs), total gene diversity (Ht) and differentiation among populations (GST) were estimated using Nei's method as 0.09, 0.87 and 0.89, respectively. This is consistent with the limited gene flow associated with synzoochory in this species. The genetic structure observed in the north of French Guiana suggests that historical events such as contractions and recent recolonizations have had a large impact on the distribution of genetic diversity in this species.
ISSN: 0962-1083

hal-01032176
https://hal.archives-ouvertes.fr/hal-01032176
DOI : 10.1046/j.1365-294x.2000.01027.x

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Ecological signs of Earth's biosphere forewarn an alarming trajectory towards a global mass-extinction. Assessing species performance and susceptibilities to decline is essential to comprehend and reverse this trend. Yet it is challenging, given difficulties associated with quantifying individual and population processes that are variable across time, space, and life-stages. We describe a new approach to estimating and comparing species performances that combines empirical data, a novel theoretical consideration of population dynamics, and modern statistics. Our approach allows for a more realistic continuous representation of individual performances along development stages while taking into account non-linearity, and natural variability as captured by spatio-temporally replicated observations. We illustrate its application in a coral meta-assemblage composed of populations of the three major reef-building taxa Acropora, Pocillopora, Porites. Using a unique set of highly replicated observations of individual coral dynamics under various environmental conditions, we show how taxa differ in their investment in recruitment and size-specific aptitude for growth and survival, notably through different use of clonal shrinkage, fragmentation, fission, and fusion processes. Our results reveal contrasting life-history trade-offs among taxa which, along with differing patterns of density-dependent recruitment, modulate species responses to decline. These differences in coral life history traits reflect opposing life-strategies, imply regulation at differing life-stages, and explain divergence in species trajectories. Our findings indicate a high potential for resilience in Pocillopora and Porites populations, thanks respectively to a sustained recruitment that promotes demographic elasticity through replacement of individuals, and a steady resistance to mortality which confers persistence through lingering of individuals. Resilience in Acropora appears more arbitrary, given high susceptibility to perturbations and dependency of recruitment on presence of established local populations. We identify management actions that can complement Acropora's life history and benefit recovery of its populations following mortality events. Our regression-modelling approach to quantifying and comparing species performances in different population processes is applicable to all taxa, as illustrated even those with complex clonal life histories, and can be implemented at wide spatio-temporal and taxonomic coverage. It can promote more accurate representation of species dynamics in both descriptive and predictive modelling approaches. The semi-parametric contrast curve method we develop facilitates comparing response variables along continuous explicative metrics while accounting for multiple sources of complexity in empirical data. It should widely benefit investigations in ecology and quantitative science.
ISSN: 1476-945X

hal-01212337
https://hal-univ-perp.archives-ouvertes.fr/hal-01212337
DOI : 10.1016/j.ecocom.2015.07.003

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
Despite the impact of soil millipedes on litter fragmentation in tropical forests, there have been few studies dealing with factors determining their habitat preference in these ecosystems. In a natural secondary dry forest of Guadeloupe on Leptosol, two complementary studies were carried out in order to test the hypothesis that litter N-content strongly influences millipede distribution. Millipede abundance and species richness were described in the field under two tree species, Bursera simaruba and Pisonia subcordata, and were related to the chemical characteristics of their foliage. In addition, a laboratory experiment was done in order to assess millipede feeding preferences regarding the chemical characteristics of leaves from various species. Millipede abundance and species richness were significantly higher under P. subcordata than under B. simaruba, probably due to the higher N content of P. subcordata leaves. Moreover, millipedes fed preferentially on N-rich leaves. The present study confirms that there was a close correlation between the preferred food, its chemical composition and the local distribution of millipede populations.
ISSN: 0178-2762

hal-00495211
https://hal.archives-ouvertes.fr/hal-00495211
https://hal.archives-ouvertes.fr/hal-00495211/document
https://hal.archives-ouvertes.fr/hal-00495211/file/BFSO-D-08-00133-1.pdf
DOI : 10.1007/s00374-008-0321-3

Éditeur(s) : Université des Antilles Études caribéennes
Résumé : The term social entrepreneurship is not new but during the past decade its interests have increased rapidly around the world while its field is still young and fragmented (Gawell, 2013). We believe that in one way or the other, the main objective of social entrepreneurship is to solve social, economic and environmental problems for sustainable development goals. One of the development challenges is the fact that Haiti has 0.47 as Human Development Index (HDI) figuring 168th among 187 countries with 58.6 % of the population living under the poverty line and 24.6% under the extreme poverty line with less than 1$UD per day (PNUD & MCI, 2014). Despite the fact that Haiti has a unique know-how that is passed down for generations in the area of craft, small industry and in the processing of products, social entrepreneurship has not taken its roots as it should have. Importantly, to get where they are today, it is undeniable that developed nations leaned the strengths of their development on human capital to produce physical/material capital. Most often, the human capital is utilized to produce strong public policies which enable the economic growth. The value of using human capital as a pillar for economic growth proved itself for Asian nations with an annual economic growth of 6.9% between 1980 and 1990 against 1.5% for Latin America (Gener, 2005). Thus, in this paper, we looked at the Emergence of Social Entrepreneurship for economic growth in Haiti.
 L'entrepreneuriat social n'est pas nouveau, mais au cours de la dernière décennie, l’intérêt pour ce terme a rapidement augmenté dans le monde alors que son champ est encore jeune et fragmenté (Gawell, 2013). Nous pensons que d'une manière ou d'une autre, l'objectif principal de l'entrepreneuriat social est de résoudre les problèmes sociaux, économiques et environnementaux en vue d'atteindre les objectifs de développement durable. La mission ou les activités d'une organisation sont soit entièrement philanthropiques soit uniquement commerciales. L'un des défis du développement est le fait que l’indice de développement humain (IDH) d’Haïti est de 0,47, le pays figure au 168e (parmi 187 pays). 58,6% de la population vit sous le seuil de pauvreté et 24,6% sous le seuil de pauvreté extrême avec moins de 1 USD par jour (PNUD et MCI, 2014). Malgré le fait qu’Haïti possède un savoir-faire unique transmis depuis des générations dans le domaine de l'artisanat, de la petite industrie et de la transformation des produits, l'entrepreneuriat social n'a pas pris ses racines comme il se doit. Il est important de noter que pour arriver là où ils sont aujourd'hui, il est indéniable que les pays développés ont soutenu le développement du capital humain pour produire du capital physique / matériel. Le plus souvent, le capital humain est utilisé pour produire des politiques publiques solides qui permettent la croissance économique. La valeur de l'utilisation du capital humain comme pilier de la croissance économique a été prouvée pour les pays asiatiques avec une croissance économique annuelle de 6,9% entre 1980 et 1990 contre 1,5% pour l'Amérique latine (Gener, 2005). Ainsi, dans cet article, nous examinons l'émergence de l'entrepreneuriat social pour la croissance économique en Haïti.
Haïti

Droits : info:eu-repo/semantics/openAccess
urn:doi:10.4000/etudescaribeennes.10406
http://journals.openedition.org/etudescaribeennes/10406

Éditeur(s) : HAL CCSD Oxford University Press (OUP)
Résumé : International audience
The distribution of the lagoon cockle Cerastoderma glaucum is strongly fragmented and usually restricted to isolated, shallow and nontidal lagoons. A high level of genetic structuring was found among the European populations of this species based on mtDNA (COI) sequences, as well as allozymic and microsatellite markers. However, the strengths and geographic locations of the major divisions differed among markers. In the present study we characterized the diversity of a new, potentially universal exon-primed intron-crossing marker, i34, for 17 C. glaucum populations. Allele frequency data at the i34 locus were informative and relevant with respect to geography. Multivariate analyses of new data together with previously published microsatellites confirmed the divergent character of the Ionian Sea and the Aegean-Ponto-Caspian populations, but also revealed the existence of a genetic cline from the Bay of Biscay to the Baltic Sea. Some noncongruent patterns among loci were detected, which may reflect either differential introgression along the genome at the hypothetical contact zone, or selective sweeps. This strong genetic differentiation, and the occurrence of private alleles, may hint at the presence of cryptic species within C. glaucum.
ISSN: 0260-1230

hal-01444646
https://hal.archives-ouvertes.fr/hal-01444646
DOI : 10.1093/mollus/eyw019

Éditeur(s) : Wiley-blackwell
Résumé : In bird species that have a high movement capacity, dispersal may connect subpopulations over vast geographical regions, with important consequences for the design of conservation management strategies. Here we used a molecular approach to infer the patterns and rates of dispersal among eight Mediterranean subpopulations of the endangered Bonelli's Eagle, based on 245 individuals screened at 17 microsatellite loci. There was moderate genetic differentiation between subpopulations sampled in the western (Iberia and Morocco) and eastern (Cyprus) Mediterranean, whereas differentiation among subpopulations in the former region was weak to moderate and followed a pattern of isolation by distance. Within the western Mediterranean, the small, peripheral and ecologically unique population of southwest Portugal had the lowest genetic diversity and the highest differentiation. The remaining subpopulations formed two loose clusters, one including Morocco and southwest and eastern Spain, and the other northeast Portugal and western and central Spain. Few recent migrants were detected, and they originated primarily from adjacent subpopulations. Our findings suggest that western Mediterranean Bonelli's Eagles may have a large-scale metapopulation structure, with subpopulations connected to some extent by distance-dependent dispersal, probably influenced by natal philopatry and the geographical configuration of subpopulations. The combination of marked ecological and genetic divergence suggests that the peripheral subpopulation of southwest Portugal may be regarded as a distinct management unit.
Ibis (0019-1019) (Wiley-blackwell), 2013-07 , Vol. 155 , N. 3 , P. 485-498

Droits : 2013 British Ornithologists’ Union
http://archimer.ifremer.fr/doc/00148/25924/24018.pdf
DOI:10.1111/ibi.12065
http://archimer.ifremer.fr/doc/00148/25924/

Éditeur(s) : HAL CCSD
Résumé : Food-grade dairy propionibacteria are nutraceutical producers. They release short chain fatty acids (SCFAs), folic acid and cobalamin, which play a role in intestinal physiology. SCFAs induce apoptosis via the mitochondrial death pathway. We investigated the potential of dairy propionibacteria-fermented products to synergize with drugs used in gastric and colorectal cancer.Fermented milk contained high and viable populations of propionibacteria. This product, as well as its cell-free supernatant, were tested in vitro on gastric HGT-1 and colic HT-29 cells with respect to apoptosis and synergy with known anti-cancer molecules, camptothecin and the human cytokine TRAIL (TNF Related Apoptosis Inducing Ligand). Viability was monitored and apoptosis quantified by Hoescht staining, ROS production, mitochondrial membrane potential perturbation and caspases activity assay. A transcriptomic study on genome-wide microarray was performed in collaboration with the company Miltenyi.Fermented milk induced cell death in both gastric and colon cancer cells. Characterization of cells revealed cell cycle arrest, drop in intracellular ATP, depolarization of mitochondria, translocation of key apoptosis proteins, processing of caspases and fragmentation of the nucleus. Interestingly, the fermented milk was shown to potentiate the cytotoxic effect of molecules used in cancer chemotherapy, camptothecin and TRAIL. The observed synergistic pro-apoptotic effect between TRAIL and propionibacterial SCFAs depended on death receptors and on caspases, was more lethal on cancer cells than on normal human intestinal epithelial cells (HIEC), and was inhibited by Bcl-2 expression. Transcriptomics revealed that propionibacterial metabolites boosted TRAIL-induced modulation of gene expression in human colon cancer cells.These results open new perspectives in the field of colon cancer cells prevention and/or treatment. The synergy with pro-apoptotic chemotherapy molecules suggests that such a fermented product, or the propionibacterium alone, may be proposed as a food supplement to enhance the effects of anticancer treatments.
The 2nd International conference on Cell Death In Cancer (CDIC)
La Baule, France

hal-01209622
https://hal.archives-ouvertes.fr/hal-01209622
PRODINRA : 261291