Variations in Respiratory Enzymes of Embryos in the Loach Fishes

Abstract

1. Activities of catalase and of succinic dehydrogenase in unfertilized eggs and in embryos of four kinds of loach fishes and those of hybrids derived from the crosses between these fishes were measured.2. The activities per embryo as well as per unit volume of eggs of catalase were greater in embryos of the larger kind and less in those of the smaller kind. The allometry exponent b among the four kinds of embryos in the activity against the egg volume was 1.50.3. The activity of succinic dehydrogenase per unit volume of eggs in unfertilized eggs was alike with each other among the four kinds of fishes but that of embryos was greater in embryos of the smaller kind than in those of the larger kind. The exponent b in the allometry of the activity against the egg volume of unfertilized eggs among the four was 1.04, and that of embryos 0.64.4. The activities of catalase in the hybrid embryos did not differ from those of the maternal control. While the activities per unit volume of eggs of succinic dehydrogenase in the hybrid embryos differed from those of the maternal control as well as those of the paternal control, being intermediate between those in embryos of the parental fishes.5. The relationship among egg size, respiratory rates, activities of these enzymes and temperature adaptation in the loach fishes were discussed.