Portin P
Department of Biology, University of Turku, Finland.
Genetica. 1992;85(2):139-45. doi: 10.1007/BF00120320.
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.
在十个不同的杂交组合中，研究了黑腹果蝇雌性减数分裂过程中Y染色体的异源分离和X染色体的二次不分离现象，这些杂交组合的母本中存在不同的大常染色体易位/倒位或易位/易位系统组合。结果表明，Y染色体总是与可能的异源配对伙伴中最短的那个分离。这可能是由于所谓“分配性分离”的大小依赖性机制，或者是由于染色体元件越短，在卵母细胞核中移动就越容易。X染色体的二次不分离现象似乎随着Y染色体拥有的常染色体配对伙伴越多而越低，这表明常染色体与X染色体在与Y染色体配对方面存在有效竞争。另一种解释是，由于染色体间对重组的影响，不同实验中X染色体的交叉互换情况有所不同。
