Nucleic acid metabolism in oocytes and embryos of Urechis caupo☆
[摘要] ThecontentandsynthesisofnucleicacidswerestudiedinmatureoocytesandembryosoftheechiuroidwormUrechiscaupo.Thematureoocytecontains14mμgoftotalRNA,includingapproximately10moleculesof4SRNAand1moleculeof5SRNAforeachribosome.ThetotalDNAcontentofthetetraploidoocyteis10pg;individualspermcontain1pg.Nucleicacidsynthesiswasstudiedduringthedevelopmentofthefertilizedeggtothe900-celltrochophorelarva.Duringthisperiodthereisa200-foldincreaseinDNAcontent,butnosubstantialchangeineithertotalRNAor4SRNAcontent.NetsynthesisorturnoverofRNAduringthisperiodofembryogenesisinvolveslessthan10%oftheembryo's4SRNAorrRNA.Theratesof4SRNAandrRNAsynthesiswerestudiedinoocytesandduringembryogenesis.Thesynthesisofboth4SRNAandrRNAisreducedsharplyuponfertilization.4SRNAissynthesizedduringcleavage,anditsrateofsynthesispercellremainsconstantthroughthepost-gastrulastage.Incontrast,therateofsynthesisofrRNAincreasesatleast13-foldatlaterstagesofembryogenesisrelativetoearlierstages.Thesynthesisof4SRNAisnotcoordinatewiththatofeitherrRNAor5SRNA.
[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]
