title: Store-operated calcium channel regulates the chemotactic behavior of ascidian sperm.
abstract: The sperm-activating and -attracting factor released from the eggs of the ascidians Ciona intestinalis and Ciona savignyi requires extracellular Ca(2+) for activating sperm motility and eliciting chemotactic behavior of the activated sperm toward the egg. Here, we show that modulators of the store-operated Ca(2+) channel, SK&F96365, Ni(2+), 2-aminoethoxydiphenylborane, and thapsigargin inhibit the chemotactic behavior of the ascidian sperm; on the other hand, blockers of voltage-dependent Ca(2+) channels did not inhibit the chemotaxis, even though they inhibited the sperm activation operated by voltage-dependent Ca(2+) channels. The blockers of store-operated Ca(2+) channels also inhibited the asymmetrical flagellar beating and turning movements of the ascidian sperm, which are typical signs of sperm chemotaxis. Depletion of internal Ca(2+) stores by thapsigargin induced capacitative Ca(2+) entry into the sperm, which was blocked by SK&F96365. These results suggest that the intracellular Ca(2+) concentration increase through the store-operated Ca(2+) channels induces asymmetrical flagellar movements to establish the chemotactic behavior of the sperm.
authors.affiliation: Misaki Marine Biological Station, Graduate School of Science, University of Tokyo, Miura, Kanagawa 238-0225, Japan. myoshida@ims.u-tokyo.ac.jp
authors.forename: Manabu
authors.initials: M
authors.lastname: Yoshida
authors.forename: Makiko
authors.initials: M
authors.lastname: Ishikawa
authors.forename: Hiroko
authors.initials: H
authors.lastname: Izumi
authors.forename: Rosaria
authors.initials: R
authors.lastname: De Santis
authors.forename: Masaaki
authors.initials: M
authors.lastname: Morisawa
mesh_terms: D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D015220:Calcium Channels / Q000502:physiology*; D020013:Calcium Signaling / Q000502:physiology; D002633:Chemotaxis / Q000502:physiology*; D002938:Ciona intestinalis / Q000502:physiology*; D008297:Male; D009532:Nickel / Q000494:pharmacology; D009543:Nifedipine / Q000494:pharmacology; D013081:Sperm Motility / Q000187:drug effects / Q000502:physiology*; D013094:Spermatozoa / Q000187:drug effects / Q000502:physiology*; D014561:Urochordata / Q000502:physiology*
chemical_list: D002121:Calcium Channel Blockers; D015220:Calcium Channels; D009532:Nickel; D009543:Nifedipine