Activation of Barnea candida (mollusca, pelecypoda) oocytes by sperm or KCl, but not by NH4Cl, requires a calcium influx☆

[摘要] ArtificialactivationofBarneacandidaoocytesbyNH4ClandtheadditionofexcessKClare,respectively,independentanddependentuponexternalCa2+concentration.TheactivatingefficiencyofNH4ClincreaseswhenexternalpHisraisedwhichsuggeststhattheproportionofunionizedpenetratingNH3isthekeyfactorforactivationundertheseconditions.TheexternalCa2+-dependentperiodforKClorsperm-inducedactivationdoesnotexceed3–4min.ThetransmembraneCa2+fluxinhibitorD-600reversiblyinhibitsKCl-orsperm-inducedactivationandtheD-600-sensitiveperiodcloselycorrespondstotheCa2+-dependentperiod.Ca2+ionsalonecanalsotriggeractivationprovidedexternalMg2+concentrationislowered.Finally,adirectdemonstrationispresentedfortheexistenceofaD-600-sensitiveCa2+uptakefollowingKCl-orsperm-inducedactivation,byusingtheradioactivetracer45Ca.ThesignificanceofthatCa2+influxisdiscussedwithrespecttothepossibleinvolvementofanintracellularpHshiftasamainfactorintheactivationoflamellibranchmolluscoocytes.

[学科分类] 生物科学（综合）