Egg jelly components responsible for histone degradation and acrosome reaction in the starfish, Asterina pectinifera

In the starfish, Asterina pectinifera, egg jelly induces the degradation of sperm histones as well as the acrosome reaction. We have isolated histone degradation-inducing components from the egg jelly. The histone degradation and the acrosome reaction are induced by a co-operative action of ARIS, which is an extremely large, sulfated glycoprotein with diffusible substance(s) in the jelly. Co-ARIS I, a steroidal saponin of the jelly, is effective to induce both reactions in the presence of ARIS.