Comparison of sperm lipid components among four species of sea-urchin based on echinoid phylogeny

Analyses were made of lipids extracted from the spermatozoa of the sea-urchins, Diadema setosum, Arbacia lixula, Paracentrotus lividus and Clypeaster japonicus which belong to the order Diadematoida, Arbacioida, Echinoida and Clypeasteroida, respectively. Diadema setosum and A. lixula spermatozoa contained several kinds of phospholipids (phosphatidylcholine, phosphatidylserine, phosphatidylethanolamine and caldiolipin), cholesterol and triglyceride. In addition to similar phospholipids, cholesterol and triglyceride, cholesterol-ester was also detected in C. japonicus spermatozoa. In contrast, lipids of P. lividus spermatozoa comprised phospholipids and cholesterol. In these species, the fatty acid composition of phosphatidylcholine, phosphatidylethanolamine and cardiolipin was of the unsaturated type for the most part, while phosphatidylserine and triglyceride, except in the case of P. lividus, comprised, to a considerable degree, saturated fatty acid.