Cell-free translation analysis of messenger RNA in echinoderm and amphibian early development☆☆☆

[摘要] Awheatgermcell-freetranslationsystemhasbeenusedtoanalyzepopulationsofabundantmessengerRNAfromseaurchineggsandembryosandfromamphibianoocytesandovaries.WeshowdirectlythatseaurchineggsandembryoscontaintranslatablemRNAofthreegeneralclasses:poly(A)+mRNA,poly(A)−histonemRNA,andpoly(A)−nonhistonemRNA.Additionally,somehistonesynthesisappearstobepromotedbypoly(A)+RNA.Seaurchineggsseemtocontainahigherproportionofprevalentpoly(A)−nonhistonemRNASthandoembryos.Somedifferencesintheproteinsencodedbypoly(A)+andpoly(A)−RNAsaredetectable.Manycodingsequencesintheeggappeartoberepresentedinbothpoly(A)+andpoly(A)−RNAs,sincethetranslationproductsofthetwoRNAclassesexhibitmanycommonbandswhenrunonone-dimensionalpolyacrylamidegels.However,someofthisoverlapisprobablyduetofortuitouscomigrationofnonidenticalproteins.Distinctstage-specificchangesinthespectraofprevalenttranslatablemRNAsofallthreeclassesoccur,althoughmanymRNAsaredetectablethroughoutearlydevelopment.Particularlystrikingisthepresenceofaneggpoly(A)−mRNA,encodinga70,000–80,000molecularweightprotein,whichisnotdetectedinmorulaorlater-stageembryos.Inamphibian(XenopuslaevisandTriturusviridescens)ovaryRNA,thetranslationassaydetectsthefollowingthreemRNAclasses:poly(A)+nonhistonemRNA,poly(A)−histonemRNA,andpoly(A)+histonemRNA.AmphibianovaryRNAappearentlylacksanabundantpoly(A)−nonhistonemRNAcomponentofthemagnitudedetectableinseaurchineggs.mRNAencodinghistone-likeproteinsisfoundintheveryearliest(smallstage1)oocytesofXenopusaswellasinlaterstageoocytes.DuringoogenesisthereappeartobenostrikingqualitativechangesinthespectraofprevalenttranslatablemRNAswhicharedetectedbythecell-freetranslationassay.

[学科分类] 生物科学（综合）