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Studies on sperm histones in amphibia and chondrichthyes Bols, Niels Christian


The basic protein composition of sperm, as well as the change in basic proteins during spermiogenesis, has been studied in a number of organisms, using both cytochemical and biochemical techniques. The sperm of the seven anurans studied are divided on cytochemical criteria into three of the five classes proposed by Bloch (1969). Rana palustris and R. pretiosa are of the Rana type. Xenopus laevis, Hyla versicolor, and H. regilla are of the Mytilus type while Bufo americanus and B. boreas appear to be of the Salmon type. Electrophoresis of testicular histones from representatives of these three types reveals significant differences. Testis specific components are absent in R. pipiens. In laevis, three testis specific bands, migrating between salmon protamine and the somatic histones, are present. A testis specific band migrating close to salmon protamine is found in B. americanus. The basic protein changes during spermiogenesis in the eastern red spotted newt, Diemictylus viridescens, resemble the transitions described in the snail, Helix aspera, (Bloch and Hew 1960a), the squid, Loligo opalescens (Bloch 1962) and Pleurodeles waltii (Picheral 1970). The early stages of spermiogenesis contain somatic type histones which in later spermatids are replaced by the Mouse/grasshopper type of protein. In turn, these proteins are replaced by the Salmon type of protein in the spermatozoa. Electrophoresis of testicular histones of the newt supports the cytochemical events outlined. Two testis specific bands are found. Spermiogenesis in three cartilaginous fish (dogfish, skate and ratfish) is characterized by unusual changes in basic proteins. Early spermatids contain somatic type histones. However, late spermatids contain the Salmon type of sperm histone while spermatozoa contain the Mouse/grasshopper type. Electrophoresis of testicular histones indicates that protamines are present in elasmobranch testes. However, a Mouse/grasshopper type of protein is not revealed.

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