Natural occurrence of entomopathogenic nematodes (Rhabditida : Steinernematidae and Heterorhabditidae) in Guadeloupe islands

Des prospections ont été réalisées sur 538 sites en Guadeloupe (Grande Terre, Basse Terre) et dans ses dépendances (Marie-Galante, La Désirade, Petite Terre, Les Saintes, Saint-Barthélémy, Saint-Martin) pour rechercher des nématodes entomopathogènes par la technique du piège à insecte (#FGalleria mellonella$). Sur 35 sites positifs (6$ (97%) et l'un d'eux un #Steinernema$(3$ (88%) et #H. bacteriophora$(12$ appartient sans doute à une nouvelle espèce en cours d'étude. Les nématodes ont été isolés en zone côtière (91,4%), en zone tropicale de basse (5,7%) et de moyenne altitude (2,9%). Aucun nématode n'a été trouvé en zone montagneuse. (Résumé d'auteur

Lipopolysaccharide Diversity Evolving in Helicobacter pylori Communities through Genetic Modifications in Fucosyltransferases

Helicobacter pylori persistently colonizes the gastric mucosa of half the human population. It is one of the most genetically diverse bacterial organisms and subvariants are continuously emerging within an H. pylori population. In this study we characterized a number of single-colony isolates from H. pylori communities in various environmental settings, namely persistent human gastric infection, in vitro bacterial subcultures on agar medium, and experimental in vivo infection in mice. The lipopolysaccharide (LPS) O-antigen chain revealed considerable phenotypic diversity between individual cells in the studied bacterial communities, as demonstrated by size variable O-antigen chains and different levels of Lewis glycosylation. Absence of high-molecular-weight O-antigen chains was notable in a number of experimentally passaged isolates in vitro and in vivo. This phenotype was not evident in bacteria obtained from a human gastric biopsy, where all cells expressed high-molecular-weight O-antigen chains, which thus may be the preferred phenotype for H. pylori colonizing human gastric mucosa. Genotypic variability was monitored in the two genes encoding α1,3-fucosyltransferases, futA and futB, that are involved in Lewis antigen expression. Genetic modifications that could be attributable to recombination events within and between the two genes were commonly detected and created a diversity, which together with phase variation, contributed to divergent LPS expression. Our data suggest that the surrounding environment imposes a selective pressure on H. pylori to express certain LPS phenotypes. Thus, the milieu in a host will select for bacterial variants with particular characteristics that facilitate adaptation and survival in the gastric mucosa of that individual, and will shape the bacterial community structure

MODIFICATION EXPÉRIMENTALE DE L'APPARITION ET DE L'ÉVOLUTION DE LA PROPHASE MÉIOTIQUE DANS L'OVAIRE D'EMBRYON DE BREBIS

International audienc

MIGRATORY PHASE OF GERM CELLS AND SEXUAL DIFFERENTIATION OF THE GONAD IN SHEEP EMBRYO

International audienc

RÉGULATION DES SAISONS SEXUELLES CHEZ DES BREBIS DE RACES DIFFÉRENTES AU MOYEN DE DIVERS RYTHMES LUMINEUX

International audienc

Influence of dietary intake and weight variation on LH release after a gonadotrophin-releasing hormone (GnRH) injection during the post-partum period of the nursing cow

International audienc

Évolution des cellules germinales femelles au cours de la prophase méiotique chez le rat : critères de reconnaissances cytoplasmique et nucléaire des différents stades en histologie fine

International audienc