Drosophila ribosomal RNA genes function as an X-Y pairing site during male meiosis.
McKee BD, Karpen GH.
Department of Biology, University of Wisconsin, Eau Claire 54701.
In Drosophila melanogaster males, the sex chromosomes pair during meiosis in the centric X heterochromatin and at the base of the short arm of the Y (YS), in the vicinity of the nucleolus organizers. X chromosomes deficient for the pairing region segregate randomly from the Y. In this report we show that a single ribosomal RNA (rRNA) gene stimulates X-Y pairing and disjunction when inserted onto a heterochromatically deficient X chromosome by P element-mediated transformation. We also show that insert-containing X chromosomes pair at the site of insertion, that autosomal rDNA inserts do not affect X-Y pairing or disjunction, and that the strength of an X pairing site is proportional to the dose of ectopic rRNA genes. These results demonstrate that rRNA genes can promote X-Y pairing and disjunction and imply that the nucleolus organizers function as X-Y pairing sites in wild-type Drosophila males.
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PMID: 2156630 [PubMed - indexed for MEDLINE]