[The mutation units of loci coding for lactate dehydrogenase and their directed changes in the phylogenetic progression of vertebrate animals].

Comparison of the electrophoretic mobility of various alleles of Ldh-A and B loci within and between species demonstrated a decreased range of variation from fish to anuran amphibians and from anurans to mammals. Fish and mammals feature incompatible ranges of this variation, usually having a mobility range above and below the first zone of Ldh-A and B loci heterodimers, respectively. Amphibians feature both types of variation. Such a quality difference in allelic variation may result from scaling down the amino acid changes from mutation of intragenic regions in fish to single amino acid substitutions in mammals.