Studies on the ribosomal RNA cistrons in interspecific Drosophila hybrids

摘要: Abstract Interspecific hybrids between Drosophila melanogaster and simulans were examined for patterns of secondary constriction formation at the nucleolus-organizer regions. In neuroblast tissue taken from F 1 interspecific hybrids, a nucleolar was normally absent D. X chromosome, while always associated with sex regardless origin maternal egg cytoplasm. When lacking chromosome constructed, however, resulting XO males viable displayed nucleolus organizer. These results suggest preferential transcription ribosomal DNA genome when organizers both species are present in conjunction, phenomenon termed dominance. addition, rDNA redundancy regular progeny monitored by RNA-DNA hybridization. Parental values conformed to previously reported measurements, but hybrid nonadditive respect parental contributions. Hybrid females possessed levels approximately 73 genes excess predicted values. Since presumably inherit wild-type rDNA, this disproportionate increase may represent response functional, rather than physical, deficiency.