pH changes associated with meiotic maturation in oocytes of Xenopus laevis☆

[摘要] ThepH-dependentcontroloftherateofproteinsynthesisinthefertilizedseaurchinegghassuggestedthatpHmayhaveanimportantroleincellactivationatfertilization.WelookedforsimilarchangesofintracellularpHduringmeioticmaturationoftheXenopusoocyte.ThebasalpHoftheoocyteisintherange7.4–7.8.Thehighervalueswerefoundmostlyinoocytesfromanimalswithrecenthormonalstimulation,suggestingacorrelationwiththeelevatedmetabolismofsuchoocytes.RegardlessofbasalpH,progesterone-inducedmaturingoocytesalkalizeanaverageof0.18pHunit.Beginningshortlybeforegerminalvesiclebreakdown,intracellularpHthendecreasestoneartheoriginalvalue.Thesameprogramisobservedwhenmaturationisinducedbyaninjectionof“maturationpromotingfactor.”MaturationisdelayedorinhibitedifintracellularpHisdrivenacidic.Itisinducedintheabsenceofprogesteronebytrimethylamine,aweakbasewhichmayactviaanimposedalkalization.However,maturationstilloccurswhennetalkalizationisprevented.Thesedatasuggestthatthealkalizationduringmaturationisaformofmetabolic“insurance”andthattheremaybebothpH-dependentandpH-independentpathwaysformaturation.ThereissomeevidencesuggestingthatpHchangesarerelatedtomovementofotherions.

[学科分类] 生物科学（综合）