Sperm basic nuclear proteins in the bivalve mollusc mesodesma donacium: characterization and comparison with histone-like and protamine-like proteins of other molluscs

Abstract

1. 1. The sperm nuclei of the marine bivalve mollusc Mesodesma donacium contain four somatic-type histones (H2A, H2B, H3 and H4), one sperm histone H1-like and a sperm-specific protein, named by us M1. 2. 2. The histone H1-like is soluble in 5% perchloric acid and rich in lysine (32.8%). 3. 3. The sperm-specific protein (M1) presents a high content of lysine (27.9%) and a low content of arginine (5.5%) in comparison to the related proteins of the other bivalves. It has a clear trypsin-resistant core. 4. 4. We compared our results with previous data on bivalve sperm protein.