Changes of uridine permeability during the maturation of tunicate eggs
[摘要] ThetimecourseofuridineuptakebyeggsandembryosofthetunicateAscidiacallosawasstudiedusing5-minpulsesof[3H]uridineatintervalsfromtheunfertilizedeggtothe16-cellembryo.Theunfertilizedeggispermeabletouridine,but5minafterfertilizationuptakebeginstodrop,reachingaminimumof30%oftheunfertilizedrateabout30minafterfertilization.At45minafterfertilization,permeabilitybeginstoincrease,reachingaplateauabout3hrafterfertilizationatthetwo-cellstage.Theinitialdecreaseinpermeabilityoccursatfirstpolarbodyproduction;theincreaseat45miniscoincidentwiththeformationofthesecondpolarbody.Substrateconcentrationexperimentsupto200μMshowstrictconcentrationdependenceforuridineuptake.Theinhibitorsp-chloromercuribenzoate(PCMB),dinitrophenol(DNP),andthymidinehavelittle,ifanyeffectonpermeability.Cold(−1°C)andNa+-freeseawaterinhibituptake60%duringallthreedevelopmentalstages.Thechangesinpermeabilitymaybeindicativeoftemporaryreorganizationoftheplasmamembraneduringthefertilization-initiatedcompletionofmeiosis.
[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]
