title: The location of highly repetitious DNA in the somatic chromosomes of Drosophila melanogaster.
abstract: In situ hybridization of Drosophila melanogaster somatic chromosomes has been used to demonstrate the near exact correspondence between the location of highly repetitious DNA and classically defined constitutive heterochromatin. The Y chromosome, in particular, is heavily labeled even by cRNA transcribed from female (XX) DNA templates (i.e., DNA from female Drosophila with 2 Xs and 2 sets of autosomes). This observation confirmes earlier reports that the Y chromosome contains repeated DNA sequences that are shared by other chromosomes. In grain counting experiments the Y chromosome shows significantly heavier label than any other chromosome when hybridized with cRNA from XY DNA templates (i.e., DNA from male Drosophila with 1 X and 1 Y plus 2 sets of autosomes). However, the preferential labeling of the Y is abolished if the cRNA is derived from XX DNA. We interpret these results as indicating the presence of a class of Y chromosome specific repeated DNA in D. melanogaster. The relative inefficiency of the X chromosome in binding cRNA from XY and XYY DNA templates, coupled with its ability to bind XX derived cRNA, may also indicate the presence of an X chromosome specific repeated DNA.
mesh_terms: D000818:Animals; D001483:Base Sequence; D004247:DNA / Q000235:genetics* / Q000378:metabolism; D004331:Drosophila melanogaster / Q000235:genetics*; D005260:Female; D006570:Heterochromatin; D008297:Male; D009693:Nucleic Acid Hybridization; D012313:RNA / Q000235:genetics; D012730:Sex Chromosomes; D014960:X Chromosome; D014998:Y Chromosome
chemical_list: D006570:Heterochromatin; D012313:RNA; D004247:DNA