title: Contribution of different Ca²⁺ channels to the acrosome reaction-mediated initiation of sperm motility in the newt Cynops pyrrhogaster.
abstract: Initiation of sperm motility in urodeles, which is induced by a sperm motility-initiating substance (SMIS) in the sequestered granules on the surface of egg jelly, is mediated by the acrosome reaction (AR), which is triggered by an AR-inducing substance (ARIS) on a sheet-like structure. Details of the unique process of the interaction between egg jelly and sperm in these species is still unclear. The current study showed the fine structure of egg jelly in the newt Cynops pyrrhogaster, a urodele species, revealing that its outer surface was covered by a sheet-like structure of approximately 0.29 μm in thickness. Granules of approximately 2 μm in diameter with small particles of approximately 54 nm were attached to its surface and distributed inhomogeneously just beneath the sheet-like structure. Emission spectrometry revealed that the Ca2+ concentration was maintained at a high level compared with that of the blood plasma and the vas deferens fluid, suggesting that egg jelly is a reliable source of Ca2+ for the sperm-egg interaction. Blockers of the T-type voltage-dependent Ca2+ channel (VDCC), but not the L-type VDCC, inhibited both AR and initiation of sperm motility. Conversely, Ni+, which affects the α1 H subunit of T-type VDCC, only inhibited the initiation of sperm motility. These data suggest that, in response to ARIS and SMIS, sequential gating of distinct Ca2+ channels occurs in the AR, followed by the initiation of sperm motility on the surface of the egg jelly in C. pyrrhogaster at fertilization.
authors.affiliation: Institute of Arts and Sciences,Yamagata University,1-4-12 Kojirakawa,Yamagata 990-8560,Japan.
authors.forename: Eriko
authors.initials: E
authors.lastname: Takayama-Watanabe
authors.affiliation: Department of Biology,Faculty of Science,Yamagata University,1-4-12 Kojirakawa,Yamagata 990-8560,Japan.
authors.forename: Hiroto
authors.initials: H
authors.lastname: Ochiai
authors.affiliation: Department of Biology,Faculty of Science,Yamagata University,1-4-12 Kojirakawa,Yamagata 990-8560,Japan.
authors.forename: Shunpei
authors.initials: S
authors.lastname: Tanino
authors.affiliation: Department of Biology,Faculty of Science,Yamagata University,1-4-12 Kojirakawa,Yamagata 990-8560,Japan.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Watanabe
mesh_terms: D020101:Acrosome Reaction / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000378:metabolism*; D020746:Calcium Channels, L-Type / Q000378:metabolism; D020747:Calcium Channels, T-Type / Q000378:metabolism; D005260:Female; D008297:Male; D008855:Microscopy, Electron, Scanning; D010063:Ovum / Q000648:ultrastructure; D012455:Salamandridae; D013081:Sperm Motility / Q000187:drug effects / Q000502:physiology*; D013084:Sperm-Ovum Interactions
chemical_list: D002121:Calcium Channel Blockers; D015220:Calcium Channels; D020746:Calcium Channels, L-Type; D020747:Calcium Channels, T-Type
keywords: Urodele