Involvement of cAMP in initiating maturation of the brittle-star Amphipholis kochii oocytes: induction of oocyte maturation by inhibitors of cyclic nucleotide phosphodiesterase and activators of adenylate cyclase.
The maturation of brittle-star (Amphipholis kochii) oocytes, i.e., the reinitiation of meiosis accompanied by germinal vesicle breakdown (GVBD) and the acquisition of fertilizability, was induced by acid (pH 3.0) seawater containing 10 mM cAMP. Oocyte maturation was also induced by seawater of normal pH (pH 8.0) that contained either an inhibitor of cyclic nucleotide phosphodiesterase (25 mM theophylline, 25 mM caffeine) or an activator of adenylate cyclase (100 microM forskolin, 0.6 microM cholera toxin). Experiments in which the oocytes were treated with forskolin or theophylline for various periods of time demonstrated that there was a positive correlation between the oocyte cAMP level measured by radioimmunoassay and the extent of GVBD induced in each treatment: both increased as the treatment period became longer and about a threefold increase in cAMP level induced 50% GVBD. These results indicate that an increase in cAMP level initiates maturation of the brittle-star oocytes.
Yamashita
M
M
Zoological Institute, Faculty of Science, Hokkaido University, Sapporo, Japan.
D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D002147:Calmodulin / Q000037:antagonists & inhibitors*; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D006863:Hydrogen-Ion Concentration; D009865:Oocytes / Q000254:growth & development*; D011863:Radioimmunoassay; D013215:Starfish; D013806:Theophylline / Q000494:pharmacology
D002147:Calmodulin; D005576:Colforsin; D002110:Caffeine; D013806:Theophylline; D000242:Cyclic AMP; D000262:Adenylyl Cyclases