title: Molecular characterization of ribosomal genes on the Ybb- chromosome of Drosophila melanogaster.
abstract: The question of whether the Ybb- chromosome contains ribosomal genes has been examined by using Southern blot analysis and comparing rDNA hybridization patterns for X/X and X/Ybb- DNA. The results demonstrate that the Ybb- chromosome contains sequences that hybridize to an rDNA probe under stringent conditions. Differential hybridization of some of these sequences with DNAs corresponding to different regions of a complete ribosomal gene repeat provides evidence that some of the genes on the Ybb- chromosome are type 2 repeats. Because data obtained by other workers suggest that type 2 repeats are transcribed only to low levels, these repeats may be classed as "nonfunctional". A further finding is that the ribosomal genes on the Ybb- chromosome do not undergo multiple rounds of DNA replication during polytenization of X/Ybb- cells.
mesh_terms: D000818:Animals; D002874:Chromosome Mapping; D004247:DNA / Q000032:analysis; D004331:Drosophila melanogaster / Q000235:genetics*; D005796:Genes; D008297:Male; D009693:Nucleic Acid Hybridization; D012335:RNA, Ribosomal / Q000235:genetics*; D012730:Sex Chromosomes / Q000648:ultrastructure*; D014998:Y Chromosome / Q000648:ultrastructure*
chemical_list: D012335:RNA, Ribosomal; D004247:DNA