SPERM PENETRATION OF THE VITELLINE ENVELOPE OF SICYONIA-INGENTIS EGGSIS MEDIATED BY TRYPSIN-LIKE LYSIN OF ACROSOMAL VESICLE ORIGIN

The sperm of the decapod crustacean Sicyonia ingentis are nonmotile, u nistellate cells. At spawning, mated females release both stored sperm and eggs. The sperm bind, via the tip of their anterior appendage, to the egg's vitelline envelope (VE), rapidly undergo acrosomal exocytos is, and penetrate the VE. In the present study we used protease inhibi tors to show that sperm penetration of the VE is due to the activity o f a sperm trypsin-like protease(s). Sperm extracts contained several p roteases when examined using gelatin-substrate SDS-PAGE, with two majo r bands of relative molecular weight 46 kD and 30 kD. Using fluorescen t peptidyl-MCA substrates, sperm extract showed trypsin-like and amino peptidase-like activities, but no chymotrypsin-like activity. Sperm ex tracts were found to degrade isolated VEs. Using soybean trypsin inhib itor and anti-inhibitor antibodies, protease was localized at the ligh t and electron microscope levels to the acrosome remnants of reacted s perm.