Basic chromosomal proteins of marine invertebrates—I. Sperm histones of nine sea urchin species

Abstract 1. 1. Histones from the sperm of nine sea urchin species belonging to seven genera of two subclasses were electrophoretically compared with the histones from sea urchin embryos, ovaries and with the calf thymus histones. 2. 2. In spermatozoa, specific subfractions H2B (mol. wt 16300–18600), the number of which varies from one to three for different species have been found. 3. 3. The variability of histones H1 and H2B within a class of sea urchins has been demonstrated. 4. 4. The peculiarities of sea urchin sperm histones are discussed in connection with the subunit organization of chromatin and the structure of histone operon.