Experimental evidence for a genetic basis to differences in aneuploidy in the Pacific oyster (Crassostrea gigas)

Aneuploidy has been previously reported in wild and cultivated Pacific oyst ers, Crassostrea gigas, and has been shown to be negatively correlated with growth. This is especially important since high variability of growth rate is one of the major problems in the aquacultural production of this specie s. The existence of a genetic basis for the observed differences in aneuplo idy was first investigated through the comparative study of six full-sib fa milies. with mean individual weights ranging from 0.59 to 1.49 g. The slowe st growing family was found to have the highest level of aneuploidy. Signif icant differences in aneuploidy were also found among families when individ uals with the same growth rate were sampled. This supports the hypothesis o f the existence of a genetic basis for the control of aneuploidy level, Add itionally, the possible inheritance of the level of aneuploidy was studied in four full-sib progenies originating from crosses within and between two different populations with contrasting levels of aneuploidy. The limited nu mber of parental oysters (N = 6) in which the scoring of aneuploidy was pos sible did not allow demonstration of the inheritance of the level of aneupl oidy. However, a genetic difference in aneuploidy could be attributed to th e origin of the parental populations. As in the first experiment, significa nt differences in aneuploidy were observed between progenies when sampling individuals of the same weight. Thus, the results of our study of full-sib progenies of C. gigas lend support to the hypothesis of a genetic basis for the level of aneuploidy. (C) 2001 Ifremer/CNRS/Inra/TRD/Cemagref/Editions scientifiques et medicales Elsevier SAS.