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

摘要

Thematurationofbrittle-star(Amphipholiskochii)oocytes,i.e.,thereinitiationofmeiosisaccompaniedbygerminalvesiclebreakdown(GVBD)andtheacquisitionoffertilizability,wasinducedbyacid(pH3.0)seawatercontaining10mMcAMP.OocytematurationwasalsoinducedbyseawaterofnormalpH(pH8.0)thatcontainedeitheraninhibitorofcyclicnucleotidephosphodiesterase(25mMtheophylline,25mMcaffeine)oranactivatorofadenylatecyclase(100??Mforskolin,0.6??Mcholeratoxin).ExperimentsinwhichtheoocytesweretreatedwithforskolinortheophyllineforvariousperiodsoftimedemonstratedthattherewasapositivecorrelationbetweentheoocytecAMPlevelmeasuredbyradioimmunoassayandtheextentofGVBDinducedineachtreatment:bothincreasedasthetreatmentperiodbecamelongerandaboutathreefoldincreaseincAMPlevelinduced50%GVBD.TheseresultsindicatethatanincreaseincAMPlevelinitiatesmaturationofthebrittle-staroocytes.