Studies on the ribosomal RNA cistrons in interspecific Drosophila hybrids: I. Nucleolar dominance☆
[摘要] InterspecifichybridsbetweenDrosophilamelanogasterandDrosophilasimulanswereexaminedforpatternsofsecondaryconstrictionformationatthenucleolus-organizerregions.InneuroblasttissuetakenfromF1interspecifichybrids,anucleolarconstrictionwasnormallyabsentfromtheD.simulansXchromosome,whileasecondaryconstrictionwasalwaysassociatedwiththeD.melanogastersexchromosome,regardlessoftheoriginofmaternaleggcytoplasm.WhenhybridslackingaD.melanogastersexchromosomewereconstructed,however,theresultingXOmaleswereviableanddisplayedaconstrictionattheD.simulansnucleolusorganizer.TheseresultssuggestapreferentialtranscriptionofribosomalDNAfromtheD.melanogastergenomewhennucleolusorganizersfrombothspeciesarepresentinconjunction,aphenomenontermednucleolardominance.Inaddition,rDNAredundancyinregularinterspecificF1progenywasmonitoredbyRNA-DNAhybridization.Parentalvaluesconformedtopreviouslyreportedmeasurements,buthybridrDNAvalueswerenonadditivewithrespecttotheparentalcontributions.HybridfemalespossessedrDNAlevelsapproximately73genesinexcessofpredictedvalues.SinceF1hybridprogenypresumablyinheritwild-typelevelsofrDNA,thisdisproportionateincreasemayrepresentaresponsetoafunctional,ratherthanaphysical,deficiency.
[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]
