Plasmalogen in ram semen, and its role in sperm metabolism

Abstract

Lipid consisting largely of plasmalogen has been extracted from ram semen and analyzed for its content of fatty aldehyde, acyl ester and phosphorus. In freshly collected ram semen the bulk of plasmalogen was in the spermatozoa at a concentration of about 1-2 g/100 g of sperm fresh weight, a value which exceeds those encountered in other animal tissues. Sperm-damaging procedures such as freezing and extensive washing caused a loss of plasmalogen from the spermatozoa into the surrounding medium. In ram spermatozoa treated with snake venom the content of acyl ester decreased without a corresponding diminution in lipid and P fatty aldehyde. The action of the venom appears to depend on an enzymic conversion of plasmalogen into lysoplasmalogen. Aerobic incubation of washed ram spermatozoa caused a reduction in the acyl ester but not in the fatty aldehyde or lipid P content. A decrease in the content of acyl-ester bonds occurred also during anaerobic incubation. This indicates that fatty acids are set free during sperm incubation, in the presence as well as in the absence of O2. Measurement of the respiratory quotient of a washed sperm suspension gave a value of 0.71, suggesting the participation of fatty acids in the aerobic endogenous metabolism. Plasmalogen was also found in the sperm, seminal plasma and accessory secretions of animal species other than ram.