The predominance of heterozygotes found in wild goldfish of lake Erie at the gene locus for sorbitol dehydrogenase

Abstract

Sorbitol dehydrogenase (SDH) found in liver, kidney, and gonads of the goldfish (Carassius auratus) appears to be specified by a single autosomally inherited gene locus and, when subjected to electrophoresis, SDH behaves as a tetramer in that a homozygote gives a single band, while a heterozygote shows five bands of SDH. In a population of the wild goldfish inhabiting Lake Erie, two alleles which specify electrophoretic variants S^A and S^B coexist in nearly equal frequency, and there appears to be a slight excess of heterozygotes. Sixty-seven of the 109 wild goldfish were S^A/S^B heterozygotes. In the domesticated goldfish, on the other hand, an allele for the S^B variant appears to be a very rare allele. Only one of the 100 domesticated goldfish studied here and none of the 100 domesticated goldfish studied in Germany was an S^A/S^B heterozygote.