Jean-Louis Nicolas

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Eleven Vibrio isolates invading the hemolymph of live and moribund oysters (Crassostrea gigas) collected in the field and from a hatchery in France, were characterized by a polyphasic approach. Phylogenetic analysis of 16S rRNA, gyrB and toxR genes indicated high homogeneity between these strains and the Vibrio aestuarianus type strain (ATCC35048(T)), and(More)
French mollusc production is based mainly on the Pacific cupped oyster, Crassostrea gigas. Since 1991, annual mass mortality of juveniles has been reported during summer months. These recurring episodes concern professionals who fear that like Portugese oyster, C. angulata, C. gigas could in turn disappear following one of these epizooties. Previously,(More)
Vibrio aestuarianus strain 01/32 was previously shown to be pathogenic to Crassostrea gigas juveniles. To investigate virulence mechanisms of this pathogen, we studied the toxicity to oysters of its extracellular products (ECPs). ECPs displayed lethality to animals, with a LD(50) value of 3.3 microg/g body weight. To determine the oyster cellular immune(More)
[Budapest], [Limoges] RÉSUMÉ.-Soit a (n) la somme des diviseurs de n. On dit que n est superabondant si, pour tout m < n, on a a (m)lm < a (n)/n. Si l'on appelle Q (X) le nombre de nombres superabondants inférieurs à X, on démontre que, pour tout c < 5/48, Q (X) > (log X) r +` pour X > Xo (c). On donne également quelques résultats et conjectures sur des(More)
BACKGROUND Bacterial infections are common in bivalve larvae and can lead to significant mortality, notably in hatcheries. Numerous studies have identified the pathogenic bacteria involved in such mortalities, but physiological changes associated with pathogen exposure at larval stage are still poorly understood. In the present study, we used an integrative(More)