Reduced rDNA copy number does not affect "competitive" chromosome pairing in XYY males of Drosophila melanogaster.
The ribosomal DNA (rDNA) arrays are causal agents in X-Y chromosome pairing in meiosis I of Drosophila males. Despite broad variation in X-linked and Y-linked rDNA copy number, polymorphisms in regulatory/spacer sequences between rRNA genes, and variance in copy number of interrupting R1 and R2 retrotransposable elements, there is little evidence that different rDNA arrays affect pairing efficacy. I investigated whether induced rDNA copy number polymorphisms affect chromosome pairing in a "competitive" situation in which complex pairing configurations were possible using males with XYY constitution. Using a common normal X chromosome, one of two different full-length Y chromosomes, and a third chromosome from a series of otherwise-isogenic rDNA deletions, I detected no differences in X-Y or Y-Y pairing or chromosome segregation frequencies that could not be attributed to random variation alone. This work was performed in the context of an undergraduate teaching program at Texas A&M University, and I discuss the pedagogical utility of this and other such experiments.
Department of Biology, Texas A&M University, College Station, Texas 77843-3258.
Keith A
KA
Maggert
D000818:Animals; D023902:Chromosome Pairing; D020090:Chromosome Segregation; D056915:DNA Copy Number Variations; D004275:DNA, Ribosomal; D004331:Drosophila melanogaster / Q000235:genetics*; D008297:Male; D008540:Meiosis; D010641:Phenotype; D011110:Polymorphism, Genetic; D018626:Retroelements / Q000235:genetics; D014960:X Chromosome; D014998:Y Chromosome
D004275:DNA, Ribosomal; D018626:Retroelements
Drosophila; Y chromosome; aneuploidy; male meiotic/meiosis pairing; ribosomal DNA