Release of acid and changes in light-scattering properties following fertilization of Urechis caupo eggs☆

[摘要] Thereleaseofafertilizationacid,monitoredbymeasuringthepHofeggsuspensions,beginswithin10secofinseminationofUrechiscaupoeggs.Thisis4minbeforethevitellinelayerbeginstoelevateandisapparentlyunrelatedtothatprocess.Theeggsoftwomolluscs,MytiluscalifornianusandAcmaeaincessa,donotformafertilizationacid.TheacidofUrechiseggsisnotaccompaniedbyreleaseof“fertilization”carbohydrate,sulfate,oranonvolatileweakacidintotheseawater.Thelight-scatteringpropertiesofUrechiseggschangeduringthefirst10minafterinsemination.Adecreaseinlightscatteringbeginsby10secandiscompleteby1min(PhaseI).Thisisfollowedbyafurtherdecrease(3–6min,PhaseII)andanincrease(6–10min,PhaseIII).Instrikingcontrasttoanovertlysimilarsituationinseaurchineggs(fertilizationacidandcoincidentlight-scatteringdecrease),thereleaseofacidandtheinitiallight-scatteringchangearenottheresultofcorticalgranuledischarge,andtheacid,atleast,isnotrelatedtothechangesinshapeorsurfaceareawhichtheeggsundergo.Theprocessesunderlyingtheserapideventsarenotyetknown.

[学科分类] 生物科学（综合）