title: Physiological inducers of the acrosome reaction.
abstract: This article reviews recent studies on physiological inducers of the acrosome reaction in starfish. Upon encountering the jelly coat of eggs, starfish sperm undergo the acrosome reaction in response to a cooperation of three jelly components: a sulfated glycoprotein named acrosome reaction-inducing substance (ARIS), a group of steroidal saponins named Co-ARIS, and an oligopeptide presumably having an activity to increase the intracellular pH of sperm. ARIS induces the acrosome reaction in high Ca2+ or high pH sea water. In normal sea water, both ARIS and Co-ARIS are required for the induction. In addition to ARIS and Co-ARIS, a third jelly component, the oligopeptide, is necessary to mimic the full capacity of the jelly coat to induce the acrosome reaction. ARIS and Co-ARIS cooperatively increase the intracellular Ca2+ by stimulating Ca2+ channels, while the oligopeptide increases the intracellular pH by stimulating Na+/H+ exchange systems. When sperm meet the eggs, both changes are simultaneously achieved in them and thus they undergo the acrosome reaction.
authors.affiliation: Department of Life Science, Tokyo Institute of Technology, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Hoshi
authors.forename: T
authors.initials: T
authors.lastname: Matsui
authors.forename: I
authors.initials: I
authors.lastname: Nishiyama
authors.forename: T
authors.initials: T
authors.lastname: Amano
authors.forename: Y
authors.initials: Y
authors.lastname: Okita
mesh_terms: D000177:Acrosome / Q000378:metabolism / Q000502:physiology*; D000818:Animals; D005260:Female; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism*; D009865:Oocytes / Q000378:metabolism / Q000502:physiology; D013084:Sperm-Ovum Interactions / Q000187:drug effects*; D013094:Spermatozoa / Q000502:physiology*; D013215:Starfish / Q000502:physiology*
chemical_list: D008562:Membrane Glycoproteins