On the diversity of sperm histones in the vertebrates. III. Electrophoretic variability of testis‐specific histone patterns in Anura contrasts with relative constancy in Squamata

A starch gel electrophoretic survey of testis‐specific histones in frogs, snakes and lizards reveals a multiple banded pattern in most of these vertebrates whether the proteins are extracted from the testis cell suspension of a single animal or from chromatin pooled from the testes of several animals. Hence, the multiple banded pattern is probably typical for each individual in a particular species. When such testis‐specific histones of Anura are compared with those of Squamata, a notable difference emerges. Thus, the principal Xenopus, Bufo and Rana testicular proteins show entirely different patterns from each other upon starch gel electrophoresis while in Squamata, each of the species examined shows a similar 2‐banded pattern in the protamine region of the electrophoretogram. In the anurans Xenopus and Scaphiopus , the testis‐specific histone patterns are different even amongst several congeneric species. Although the present survey examines only a limited number of species, the electrophoretic data do point to the order Squamata as one place in vertebrate phylogeny where the diversity of testis‐specific histones in fish and amphibians appears to give way to a relative constancy of such proteins in reptiles. Such an evolutionary trend may be consistent with a modified version of Bloch's ('69) hypothesis that relates sperm histone variability to genetically based sex determination.