An ultrastructural examination of polyspermy induced by soybean trypsin inhibitor in the sea urchin Arbacia punctulata☆

[摘要] Finestructuralstudieshavebeenconductedtodeterminetheroleofthetrypsinlikeproteinaseduringfertilizationwhichislocalizedwithinthecorticalgranulesofseaurchineggs.Eggsweretreatedwithsoybeantrypsininhibitor(SBTI),inseminated,andpreparedformicroscopicexaminationatvariousintervalsduringfertilization.InthepresenceofSBTIthebreakdownofthecorticalgranulesisdelayedandtheelevationofthevitellinelayerisincomplete.AlthoughallthecorticalgranulesinSBTI-treatedeggsaredehiscedinamannersimilartocontrols,therateatwhichtheirbreakdownispropagatedisreduced.Consequently,dehiscenceofallthecorticalgranulesinSBTI-treatedspecimensrequiresapproximately3mintocomplete,vs.1minforcontrols.Inadditionthefertilizationmembranehasablisteredappearanceowingtoitsattachment,atmultipleloci,tothesurfaceofthezygote.Duringtheearlystagesoffertilizationmanyofthetreatedeggsaremonospermic,laterallarepolyspermic.Supernumeraryspermentertreatedeggs(zygotes)upto10minaftertheinitiationofthecorticalgranulereaction,apparentlyatthosesiteswherethefertilizationmembranehasfailedtoseparatefromthezygote'ssurface.

[学科分类] 生物科学（综合）