Energy metabolism of spermatozoa of the sea urchin Glyptocidaris crenularis.

Energy metabolism in spermatozoa of the sea urchin Glyptocidaris crenularis was examined. The spermatozoa contained not only several kinds of phospholipids and cholesterol but also triacylglycerides (TG). Following dilution of the dry sperm in sea water, the TG content decreased rapidly. Other lipids, however, remained at constant levels, except for an increase in the level of free fatty acid. Oil red-O staining of spermatozoa showed that TG was principally located in part of the sperm midpiece. Also, high lipase activity was demonstrated in the spermatozoa. In both intact cells and a cell-free system, 14C-labeled fatty acids were oxidized to 14CO2. It is thus concluded that G. crenularis spermatozoa use TG as a substrate for energy metabolism.