Studies on the interactions of sperm with the surface of the sea urchin egg☆

[摘要] WehaveexaminedtherelationshipbetweenspermadhesionandfertilizationinthecrossspeciesinseminationofArbaciapunctulataeggsbyStrongylocentrotuspurpuratussperm.Aspreviouslyreported(Kinseyetal.,1980)theadditionofS.purpuratuseggjellyresultsininductionoftheacrosomereactioninspermandsignificantnumbersofS.purpuratusspermadheretoA.punctulataeggs.However,intheabsenceofS.purpuratuseggjelly,S.purpuratusspermfailtobindtoA.punctulataeggs.Althoughatleast200S.purpuratusspermbindtoanA.punctulataegginthepresenceofS.purpuratusjelly,lessthan8%oftheeggsarefertilized.TheadhesionofS.purpuratusspermmeetsthesamefunctionalcriteriaashomologousA.punctulatasperm-eggadhesion.ElectronmicroscopyshowsthatS.purpuratusspermthathaveundergonetheacrosomereactionadheretoA.punctulataeggsbytheirbindin-coatedacrosomalprocessinamannerthatismorphologicallyidenticaltothatobservedwithhomologousA.punctulatasperm.WehavealsocomparedtheabilityofS.purpuratusandA.punctulataspermtofuseandfertilizewithA.punctulataeggsafterremovalofthevitellinelayer.Usinghighlevelsofspermofeitherspecies,heterologousaswellashomologousfertilizationisreadilydetectable.Undertheseconditions,wherestablebindingisnotdemonstrable,thereisnodifferenceintheabilityofS.purpuratusandA.punctulataspermtofertilizeA.punctulataeggs.TheseobservationssuggestthatthefailureofS.purpuratusspermtofertilizeA.punctulataeggsundernormalconditionsmaybeduetotheirinabilitytopenetratethevitellinelayersothattheycanfusewiththeeggplasmamembrane.Inrelationtothepossiblemechanismofvitellinelayerpenetration,wehavealsoinvestigatedthemodeofactionofchymostatin,aninhibitorofchymotrypsinthathasbeenreportedtoinhibitfertilizationofseaurchineggs(Hoshietal.,1979).Ourfindingssuggestthatthefertilizationinhibitoryactivityofchymostatinisnotrelatedtoitsantichymotrypsinactivity.Rather,itappearsthatthisinhibitionisduetotheinductionofanabnormalacrosomereactioninspermthatprecludesformationoftheacrosomeprocess.

[学科分类] 生物科学（综合）