Intracellular calcium release at fertilization in the sea urchin egg☆
[摘要] FertilizationorionophoreactivationofLytechinuspictuseggscanbemonitoredafterinjectionwiththeCa-sensitivephotoproteinaequorintoestimatecalciumreleaseduringactivation.Weestimatethepeakcalciumtransienttoreachconcentrationsof2.5–4.5μMfreecalcium45–60secafteractivationandtolast23Ì„min,assumingequalCa2+releasethroughoutthecytoplasm.Calciumisreleasedfromanintracellularstore,sincesimilarresponsesareobtainedduringfertilizationatawiderangeofexternalcalciumconcentrationsorinzerocalciumseawaterinionophoreactivations.Inanotherefforttoestimatefreecalciumatfertilization,weisolatedeggcortices,addedbackcalciumquantitatively,andfixedforobservationwithascanningelectronmicroscope.Inthisway,wedeterminedthatthethresholdfordischargeofthecorticalgranulesisbetween9and18μMCa2+.Therefore,thethresholdfortheinvitrocorticalreactionisaboutfivetimestheamountoffreecalcium,assumingequaldistributionintheegg.Thisresultsuggeststhattransientcalciumreleaseisconfinedtotheinnersubsurfaceoftheegg.
[发布日期] [发布机构]
[效力级别] [学科分类] 生物科学（综合）
[关键词] [时效性]
