title: Evolution of the ribosomal DNA spacers of Drosophila melanogaster: different patterns of variation on X and Y chromosomes.
abstract: Length variation of the ribosomal gene spacers of Drosophila melanogaster was studied. Analysis of 47 X chromosomal and 47 Y chromosomal linked rDNA arrays collected from five continents indicates that the arrays on the two chromosomes differ qualitatively. The Y-linked arrays from around the world share little or no similarity for either their overall length or the organization of their spacers. Most of the X-linked arrays do, however, share a major length spacer of 5.1 kb. In addition, those X-linked arrays that have a major 5.1-kb band have similar spacer organization as demonstrated by genomic DNA digestions with several restriction enzymes. These data strongly support the hypothesis that spacer length patterns on only X-linked genes are maintained primarily by natural selection.
mesh_terms: D000818:Animals; D004262:DNA Restriction Enzymes; D004275:DNA, Ribosomal / Q000235:genetics*; D004331:Drosophila melanogaster / Q000235:genetics*; D005260:Female; D008040:Genetic Linkage; D008297:Male; D014960:X Chromosome; D014998:Y Chromosome
chemical_list: D004275:DNA, Ribosomal; D004262:DNA Restriction Enzymes