Relation of cytoplasmic alkalinization to microvillar elongation and microfilament formation in the sea urchin egg☆

[摘要] ExperimentshavebeencarriedouttotesttheproposalthatthepHincreaseatfertilizationinseaurchineggspromotesmicrovillarelongation.Resultspresentedhereinshowthatmicrovillarelongationandmicrofilamentformationoccurredwhenseaurchineggswereincubatedinsodium-freeseawatercontainingthecalciumionophoreA23187,atreatmentwhichinitiatesactivation,i.e.,inducesatransientincreaseinintracellularfreecalcium,butpreventssubsequentcytoplasmicalkalinization.Withinelongatedmicrovilliandcorticesoftheseeggs,microfilamentswerearrangedinaloosemeshwork.However,ifthepHoftheeggcytoplasmwasincreasedexperimentally,microfilamentbundlesappearedwithinindividualmicrovilli.Thesefindingssuggestthat:(1)microvillarelongationandmicrofilamentformationintheseaurchineggatfertilizationmayoccurwhencytoplasmicalkalinizationisinhibited,and(2)formationofthemicrovillusbundleofmicrofilamentsateggactivationispHsensitive.Additionally,ifthecytoplasmicpHofunfertilizedeggswasexperimentallyelevatedbyNH4Cl,microvillifailedtoelongate.ThesedataindicatethatelevationofintracellularpHbythismethodisnotsufficienttoinducemicrovillarelongation.

[学科分类] 生物科学（综合）