Activity of phospholipases A and lysophospholipase in Turkey semen and oviducal fluid

Changes in lipid composition of turkey semen have previously been reported to occur during in vitro storage and may be mediated by endogenous hydrolysis of phospholipids. To investigate the presence of phospholipases able to initiate such degradation, phospholipaseA(2) (PLA(2)) phospholipase A(1) *(PLA(1)), and lysophospholipase (LPLase) activities were measured in turkey spermatozoa and seminal plasma. These enzymes were also measured in the oviductal fluid because they may be involved in the process prior to fertilization in the female. In spermatozoa and seminal plasma, the major PLA(2) was a calcium-dependent and sodium deoxycholate (DOC) stimulated enzyme. However, calcium-independent PLA(2) activities were also detected with different characteristics in spermatozoa (DOC inhibited enzyme) and seminal plasma (DOC stimulated enzyme). Additionally, PLA(1) activity and high LPLase activity were present in spermatozoa and seminal plasma. In vitro storage of semen for 48 h did not affect PLA(2) and LPLase activities. By contrast, PLA(1) was the major phospholipase activity detected in oviductal fluid. A PLA(2) activity stimulated by calcium or DOC and LPLase activity were also detected, but both were low relative to PLA(1). These results showed that turkey semen had several enzymatic activities able to hydrolyze phospholipids. In addition, the phospholipase activities described here in the oviductal fluid could be involved in membrane destabilization prior to fertilization.