Génétique biochimique de populations de Crassostrea gigas en France (côte atlantique) et au Japon (Miyagi)

By means of starch gel electrophoresis, the genetic variations of 16 natural or cultured Crassostrca gigas populations from the French Atlantic coasts werc cornparcd with one from Miyagi (Japan). In the 17 populations examined, allele frequencies of the 13 loci analysed showed 4 monomorphic loci for the same allele in French populations and only 3 for the Japanese population. Two particular alleles were detected exclusively in the Japanese population (Aat-190 and aGpd-IlL2). Nevertheless, the frequency of the most common allele for each locus was the same in France and in Japan. The genetic variation criteria (proportion of polymorphie loci, heterozygosities, mean number of alleles per locus), which were rehtively high, were of the samc order of magnitude in Japan and in France, including a population hatched in captivity. The genetic identity criteria show a very high similarity between the populations from Japan and France. Within the latter, multivariate analysis revcaled four cstuarine populations with characteristic genotypes. Keyrrords : Genetic polymorphism, Crassostrea gigas.