Patterns of soluble proteins and multiple forms of dehydrogenases in amphibian development

In the three amphibian species Bombina variegata, Rana temporaria and Triturus alpestris there is a two- to threefold increase in the total content of saline-soluble proteins during development (prior to feeding). Analyses by polyacrylamide gel electrophoresis revealed the appearance of one or two new protein fractions at gastrulation. Protein bands of transitional occurrence were also observed at various developmental stages. In general, during early embryogenesis protein components with relatively low migrating rates in the anodal direction predominate, whereas in the late larvae fractions of higher mobilities are more abundant. The isozymic patterns of four dehydrogenases in both embryonic and adult tissues of the three amphibians have been analysed. Three molecular forms of lactate dehydrogenase (LDH) are present in Bombina and Triturus, and two in Rana. Triturus and Rana have only a single malate dehydrogenase (MDH), whereas Bombina has two with, however, a clear difference in the mobility of the minor band between embryonic and adult stages. The total number of molecular forms of glucose-6-phosphate dehydrogenase (GDH) varies from four in Bombina to two in Rana and Triturus. There are probably four to five isozymes of alcohol dehydrogenase (ADH) of very low activity. Morphogenetic changes of the isozymic patterns include the appearance of one MDH in Bombina and the gradual increases in activities of LDH, GDH and MDH in Rana at gastrulation. After hatching further appearance of ADH isozymes occurs. The new synthesis of one GDH in the late Bombina larvae seems largely associated with the differentiation of heart and fat body. The formation of one MDH in this amphibian is probably delayed until after metamorphosis. A shift in the relative synthesis of isozymes during Bombina development is indicated by the temporary loss of one LDH band at tail-bud formation and after hatching.