Effects of protease inhibitors on sperm-related events in sea urchin fertilization☆

[摘要] Evidenceforsperm-borneproteolyticenzymesexposedduringtheacrosomereactioninseaurchinspermhasbeenaccumulating.Toinvestigatethepossiblerole(s)suchenzymeshaveinfertilization,westudiedtheeffectsofseveralproteaseinhibitorsonsperm-relatedevents.Soybeantrypsininhibitor,Nα-p-tosyl-l-lysine,chloromethylketone,phenylmethylsulfonylfluoride,andchymostatinneitherreducedthenumberofacrosomereactionsnorinterferedwithgametebinding.p-Nitrophenyl-p′-guanidinobenzoatecausedspermtofuseintoirregularclumps,renderingthemunabletofertilizeeggs.However,l-1-tosylamide-2-phenylethylchloromethylketone(TPCK),aninhibitorofchymotrypsin,preventedtheacrosomereactioninStrongylocentrotuspurpuratus,S.droebachiensis,andLytechinuspictus.TheeffectsofTPCKonsperminsubsequentstepsoffertilizationwerealsoinvestigated.First,gametebindingassayswereperformedonfixedeggs.ThisprecludedanyeffectsTPCKmighthavehadonegg-derivedsecretions(e.g.,proteases).Bindingofprereactedspermoccurredwithbothfixedandlivingeggs.However,fertilizationoflivingeggsinthepresenceofTPCKwasgreatlyreduced,eventhoughspermhadbeenprereactedwitheggjelly.Vitellinecoatswerethenremovedfromeggsbytrypsintreatment.EggsinTPCKfertilizedanddevelopednormallyaftertheabovetreatment.Theseobservationsareconsistentwiththehypothesisofaspermproteaseparticipatingintheacrosomereactionandthepenetrationoftheeggvitellinecoatintheseaurchin.

[学科分类] 生物科学（综合）