title: Control of flatfish sperm motility by CO2 and carbonic anhydrase.
abstract: Sperm motility in flatfishes shows unique characteristics. The flagellar movement either in vivo or in permeabilized models is arrested by the presence of 25-100 mM HCO3-, or by gentle perfusion with CO2 gas. To understand the molecular basis of this property, sperm Triton-soluble proteins and flagellar proteins from several species were analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis. An abundant 29-kDa protein was observed only in flatfish species. Partial amino acid sequences identified this protein as a carbonic anhydrase, an enzyme involved in the interconversion of CO2 and HCO3-. 6-ethoxyzolamide, a specific inhibitor of carbonic anhydrase inhibits sperm motility, especially at low pH. In the case of HCO3(-)-arrested sperm, the motility is restored by addition of 6-ethoxyzolamide. Taken together, these results suggest that a novel pH/HCO3(-)-dependent regulatory mechanism mediated by carbonic anhydrase is involved in the motility control in flatfish sperm.
authors.affiliation: Asamushi Marine Biological Station, Graduate School of Science, Tohoku University, Asamushi, Aomori, Japan. inaba@biology.tohoku.ac.jp
authors.forename: Kazuo
authors.initials: K
authors.lastname: Inaba
authors.forename: Catherine
authors.initials: C
authors.lastname: Dréanno
authors.forename: Jacky
authors.initials: J
authors.lastname: Cosson
mesh_terms: D000818:Animals; D001639:Bicarbonates / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism*; D002256:Carbonic Anhydrases / Q000378:metabolism*; D002465:Cell Movement / Q000502:physiology*; D005412:Flatfishes / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008297:Male; D013094:Spermatozoa / Q000378:metabolism*
chemical_list: D001639:Bicarbonates; D002245:Carbon Dioxide; D002256:Carbonic Anhydrases