On the diversity of sperm histones in the vertebrates. I. Changes in basic proteins during spermiogenesis in the newt Notophthalmus viridescens.

Sperm histones display great variability in contrast to the conservation of most classes of somatic histones. To study this paradox, this series of papers examines the variation of histone patterns in the testis and sperm of vertebrates, particularly amphibians and reptiles, and attempts to relate such variation to genetically based sex determination as hypothesized by Bloch [Genetics Supplement 61, 93 (1969)]. In the present study we have investigated spermiogenesis in the newt Notophthalmus viridescens viridescens. Cytochemical experiments indicate that the basic nuclear proteins undergo progressive shifts from somatic type histone leads to very arginine-rich "stable protamine" in the later spermatids leads to protamine in the mature sperm. Electrophoresis of Notophthalmus histones extracted from chromatin reveals that the pattern of testes specific basic proteins in the urodele is distinct from the pattern of testicular proteins in the anurans Bufo americanus and Xenopus laevis. Species within the class Amphibia therefore exhibit considerable diversification in their type of basic sperm proteins.