Electrophoretic Studies of Xiphophorin Fishes and Their Melanoma-bearing Hybrids

Abstract

Characteristic electrophoretic profiles of water-soluble muscle proteins were obtained with 9 spp. and sspp. of the genus Xiphophorus using paper electrophoresis. The patterns of hybrids were intermediate, showing characteristics of both parental spp. Both the quantitative and the qualitative differences, which distinguished the various groups, were constant and there was good reproduclbility of patterns. The significance of the chemical individuality of muscle proteins in taxonomy is discussed. A unique tumorous hybrid profile was not obtained; instead, the muscle patterns of tumorous animals resembled those of siblings which lacked the genes that are implicated in atypical pigment cell growth. The severity of hybrid anomalies may be correlated with the degree of biochemical divergence of the parental spp. Electrophoretic analysis of the water-soluble proteins of the spontaneous xiphophorin pigment cell tumors, both the melanomas and amelanotic melanomas, indicated an appreciable negative change and a low cellular protein content.