Accumulation of mitochondrial DNA during oogenesis in Xenopus laevis☆

[摘要] ThemitochondrialDNA(mtDNA)contentofXenopuslaevisoocytesatvariousstagesofoogenesishasbeendeterminedbymolecularhybridizationwith3H-labeledcomplementaryRNA(cRNA).Theprevitellogenicoocytelessthan250μmindiameter(stage1)contains0.95±0.47ngofmtDNA.AccumulationofmtDNAproceedsuntilstage4(500–750μmdiameteroocyte),bywhichtimeasteady-statelevelof4.28±0.40ng/oocyteisattained.Usingthehybridizationassay,thestage6(full-grown)Xenopusoocytecontains4.51±0.69ngofmtDNA,comparedtothepreviouslyreportedvalueof3.8ngdeterminedbydirectmeasurementontheunfertilizedegg.Thereappearstobeareasonablecorrelation,therefore,betweentheterminationofmtDNAaccumulationandthedispersalofthejuxtanuclear,mitochondrialaggregate(Balbianibody)attheonsetofvitellogenesisinXenopus.Itisconcludedthattheenormouscomplementofoocytemitochondriaisaccumulatedwellbeforetheendofoocytegrowthandismaintainedataconstantlevelduringtheremainderofoogenesis,throughmaturation,fertilization,andonintoearlydevelopment.

[学科分类] 生物科学（综合）