Partner choice in heterologous chromosome segregation of the Y chromosome in competitive situations in the oocyte of Drosophila melanogaster.
Heterologous segregation of the Y chromosome and secondary non-disjunction of the X chromosomes in female meiosis of Drosophila melanogaster was investigated in ten different crosses where different constellations of translocation/inversion or translocation/translocation systems of the large autosomes were present in the female parent. It appeared that the Y chromosome always segregates from the shortest of the possible heterologous pairing partners. This may be due to size-dependent mechanism of so-called 'distributive disjunction' or to the possibility that the shorter the chromosome element is, the more easily it moves in the nucleus of the oocyte. Secondary non-disjunction of the X chromosomes appeared to be lower the more possible autosomal pairing partners the Y chromosome had, suggesting that the autosomes effectively compete with the X chromosomes for pairing with the Y chromosome. An alternative explanation is that, due to interchromosomal effect on recombination, crossing over in the X chromosomes was different in different experiments.
Portin
P
P
Department of Biology, University of Turku, Finland.
D000818:Animals; D007446:Chromosome Inversion; D003434:Crossing Over, Genetic; D004331:Drosophila melanogaster / Q000235:genetics*; D005260:Female; D005799:Genes, Dominant; D008297:Male; D008540:Meiosis; D009630:Nondisjunction, Genetic; D010063:Ovum; D014178:Translocation, Genetic; D014960:X Chromosome; D014998:Y Chromosome