title: Ribosomal DNA and Stellate gene copy number variation on the Y chromosome of Drosophila melanogaster.
abstract: Multigene families on the Y chromosome face an unusual array of evolutionary forces. Both ribosomal DNA and Stellate, the two families examined here, have multiple copies of similar sequences on the X and Y chromosomes. Although the rate of sequence divergence on the Y chromosome depends on rates of mutation, gene conversion and exchange with the X chromosome, as well as purifying selection, the regulation of gene copy number may also depend on other pleiotropic functions, such as maintenance of chromosome pairing. Gene copy numbers were estimated for a series of 34 Y chromosome replacement lines using densitometric measurements of slot blots of genomic DNA from adult Drosophila melanogaster. Scans of autoradiographs of the same blots probed with the cloned alcohol dehydrogenase gene, a single copy gene, served as internal standards. Copy numbers span a 6-fold range for ribosomal DNA and a 3-fold range for Stellate DNA. Despite this magnitude of variation, there was no association between copy number and segregation variation of the sex chromosomes.
authors.affiliation: Department of Biology, Pennsylvania State University, University Park 16802.
authors.forename: E M
authors.initials: EM
authors.lastname: Lyckegaard
authors.forename: A G
authors.initials: AG
authors.lastname: Clark
mesh_terms: D000426:Alcohol Dehydrogenase / Q000235:genetics; D000818:Animals; D015342:DNA Probes; D004275:DNA, Ribosomal / Q000235:genetics*; D004331:Drosophila melanogaster / Q000235:genetics*; D014644:Genetic Variation; D005810:Multigene Family; D009693:Nucleic Acid Hybridization; D014998:Y Chromosome
chemical_list: D015342:DNA Probes; D004275:DNA, Ribosomal; D000426:Alcohol Dehydrogenase