Apparent overdominance of enzyme specific activity in two marine bivalves

摘要

Electrophoretic examination of a natural population sample of 332 mussels (Mytilus trossulus) revealed ten active allozyme alleles for the octopine dehydrogenase (Odh) locus and a statistically significant (P0.05) deficiency of heterozygous genotypes.In vitrospecific activity for leucine aminopeptidase (E.C. 3.4.-.-) was determined for 89 oysters representing 19 differentLap-2genotypes.Lap-2heterozygotes had an average specific activity that was 56 greater than that of homozygous genotypes, a significant (P<0.0001) difference. Possible explanations for the apparent overdominance in enzyme specific activity and the deficiency of heterozygotes include null alleles, molecular imprinting and aneuploidy.