UBC Theses and Dissertations
Electrophoretic and amino acid analysis of amphibian and reptilian histones Huang, Sue-Ying
Small amounts of amphibian and reptilian histones, basic proteins associated with DNA, can be characterized by a combination of electrophoresis and subsequent amino acid analysis of the stained bands. A simple method has been devised for obtaining histones for such analysis from Xenopus laevis, the South African clawed toad. Xenopus somatic histones analyzed both by starch and acrylamide gel electrophoresis show microheterogeneity for the very lysine-rich Hi histones of heart and lung, but no tissue-specificity for this group of basic nuclear proteins. Xenopus embryonic histones prepared by the method of Destrèe et al. (1972) can also be characterized by starch gel electrophoresis. In this procedure, the possibility of contamination of nuclei by yolk platelets and ribosomes is reduced. No change is observed in the starch gel electrophoretic profiles of Xenopus histones throughout early embryogenesis. This confirms the original observation of Destrèe et al. (1973) using polyacrylamide gel electrophoresis. Histones can be extracted from amphibian and reptilian testis cell suspensions and analyzed by starch and polyacrylamide gel electrophoresis. Since only one animal is required in this method, the analysis can be extended to include different species for which many representatives are difficult to obtain. In addition, using Houston's (1971) method of hydrolyzing amidoblack-stained protein bands on polyacrylamide gels for amino acid analysis, one can obtain the chemical composition of testis-specific histones from a number of amphibians and reptiles. Amphibian testis-specific histones show entirely different patterns from each other, while the reptilian histones show remarkable similarity to each other both in their electrophoretic properties and amino acid composition. Although the present survey examines only a limited number of species, the data do point to the reptiles as one place in vertebrate phylogeny where the diversity of testis-specific histones in fish and amphibians gives way to a relative constancy of such proteins.
Item Citations and Data