EFFECTS OF ENZYMATIC AND NONENZYMATIC PROTEINS ON ARBACIA SPERMATOZOA: REACTIVATION OF AGED SPERM AND THE INDUCTION OF POLYSPERMY

¹ Marine Biological Laboratory, Woods Hole, MA 02543

Arbacia sperm become inactive after dilution in sea water. We have shown that any of six proteins reactivated the aged sperm as judged by their fertilizing capacity or their motility. In suspensions of inactive sperm in which the mean fertilizing capacity was less than 3%, brief incubation with any of the proteins at 0.5 mg/ml stimulated fertilizing capacity to 70-90%. Reactivation by the proteins was detected at concentrations lower than 2 µg/ml. All six of the proteins also stimulated motility of aged sperm by 30-70%.

The normal block to polyspermy may involve inactivation of sperm by substances released from the eggs during the fertilization reaction. All six proteins tested on inactive sperm were also shown to induce polyspermy in mixtures of eggs and fresh sperm. Whereas in control mixtures with polyspermic cleavage of 1% of eggs, proteins at 2 mg/ml induced 5-50% polyspermic cleavage, and induction of polyspermy was detected at 5 µg/ml.

The six proteins showing activity included enzymes and also the relatively inert gelatin. The concentration dependence was upon weight/volume and not molarity. Though the mode of action is unclear, it must be rather nonspecific, and is certainly not dependent on enzymatic activity. The same mode of action is likely for activation of aged sperm and induction of polyspermy.