Genetic evidence that nonhomologous disjunction and meiotic drive are properties of wild-type Drosophila melanogaster male meiosis
Genetic evidence that nonhomologous disjunction and meiotic drive are properties of wild-type Drosophila melanogaster male meiosis
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DOI：
10.1534/genetics.104.036806
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发表时间：
2006-01-01
期刊：
影响因子：
3.3
通讯作者：
Robbins, LG
中科院分区：
文献类型：
--
作者：
Boschi, M;Belloni, M;Robbins, LG
我们在四种基因型中跟踪了性别和第二染色体的分离，以及这些染色体对精子功能的影响：野生型雄性，y连锁晶体位点缺陷的雄性，X染色体异色缺陷（删除所有X配对位点）的雄性，以及两种缺陷的雄性。这两种突变情况都会引起染色体行为异常，但分离缺陷是完全不同的。X异染色质的缺乏与配对位点的缺乏一致，主要破坏X- y分离，对主要常染色体行为具有决定性的二级影响。删除晶体，与推迟染色质凝聚问题的细胞学图像一致，同时破坏性别和常染色体分离。然而，即使突变诱导的不分离具有非常不同的机制，甚至更重要的是，即使在野生型中，也存在强大而相似的减数分裂驱动。当分离被明显不同的机制破坏时，减数分裂驱动的存在支持了这样一种观点，即驱动是细胞对减数分裂问题的正常反应，而不是特定突变体的直接影响。最令人惊讶的是，在野生型和缺乏晶体的男性中，Y染色体几乎100%地从一对未分离的第二染色体移动到相反的极。然而，当X异染色质被删除时，这种非同源相互作用就不存在了。性染色体和第二染色体的非同源分离可能是反褶积显微镜观察到的染色体区隔化的遗传结果，当X异染色质被删除时，Y-2分离的缺失表明XY配对本身，或以前未被识别的异染色质功能，是染色体宏观结构组织的先决条件。
We have followed sex and second chromosome disjunction, and the effects of these chromosomes on sperm function, in four genotypes: wild-type males, males deficient for the Y-linked crystal locus, males with an X chromosome heterochromatic deficiency that deletes all X-Ypairing sites, and males with both deficiencies. Both mutant situations provoke chromosome misbehavior, but the disjunctional defects are quite different. Deficiency of the X heterochromatin, consonant with the lack of pairing sites, mostly disrupts X-Y disjunction with a decidedly second-level effect on major autosome behavior. Deleting crystal, consonant with the cytological Picture of postpairing chromatin-condensation problems, disrupts sex and autosome disjunction equally. Even when the mutant-induced nondisjunction has very different mechanics, however, and even more importantly, even in the wild type, there is strong, and similar, meiotic drive. The presence of meiotic drive when disjunction is disrupted by distinctly different mechanisms supports the notion that drive is a normal cellular response to meiotic problems rather than a direct effect of particular mutants. Most Surprisingly, in both wild-type and crystal-deficient males the Y chromosome moves to the opposite pole from a pair of nondisjoined second chromosomes nearly 100% of the time. This non-homologous interaction is, however, absent when the X heterochromatin is deleted. The nonhomologous disjunction of the sex and second chromosomes may be the genetic consequence of the chromosomal compartmentalization seen by deconvolution microscopy, and the absence of Y-2 disjunction when the X heterochromatin is deleted suggests that XY pairing itself, or a previously unrecognized heterochromatic function, is prerequisite to this macrostructural organization of the chromosomes.