マガキの生化学的遺伝多型-III

Abstract

Genetic variations have previously been described in the myogen, est erases, tetrazolium oxidase, and leucine arninopeptidases in the Pacific oyster, Crassostrea gigas. Some 900 specimens (35 lots) of the Pacific oyster, sampled from the wild populations off the Pacific and the Japan Sea coasts of Hokkaido, and off Iwate and Akita Prefectures, as well as from the cultured populations from Miyagi and Hiroshima Prefectures, were compared for gene frequencies at the loci noted above. No significant geographical difference was seen in esterases and tetrazolium oxidase. At the leucine aminopeptidase locus, frequencies of the allele Lap5 increased towards the lower latitudes along the Pacific coast, indicating a marked difference between Ryori and Ofunato, Iwate Prefecture. This resulted in a distinction of the arbitrarily named “Hokkaido-northern Tohoku and southern Tohoku groups”. Two dimensional comparisons with the allele M2 (myogen) and Lap5 made possible the distinction of the cultured population in Hiroshima from the two wild populations noted above. Overdominance of the heterozygote 5•7 at the Lap locus was observed both in the wild and cultured populations sampled. Zymograms of the “unidentified specimens” reported before were identical to those of C. nippona SEKI, sampled from Akita Prefecture. Some future studies are suggested towards solutions of problems or questions raised from the discussions of the present study.