Lactate dehydrogenase isozymes in the genus Xenopus: analyses of complex isozyme patterns

1. Previous work showed that seven out of 13 Xenopus species and subspecies possess a simple pattern of 5 LDH isozymes as it is common to most vertebrates. 2. The remaining six species with more complicated patterns are further analyzed in the present paper. 3. X. l. laevis, X. vestitus and X. wittei are characterized by the appearance of an anodal "sixth band". Two explanations are given. 4. A comparison of organs in X. borealis reveals the bands additional to the five banded pattern as secondary isozymes. 5. The five bands in the A4 region in X. ruwenzoriensis, combinations of A subunits in nature as demonstrated by treatment with antibodies against the purified A4 homopolymer, must be considered as being the result of a duplicated A. locus. 6. The same is possibly true for the closely spaced cathodal bands in X. fraseri. 7. The occurrence of only few expressed duplicated loci among the genus Xenpus indicates progressed diploidization within this genus.