An initiation site for meiotic crossing-over and gene conversion in the mouse
An initiation site for meiotic crossing-over and gene conversion in the mouse
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DOI：
10.1038/ng990
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发表时间：
2002-10-01
期刊：
影响因子：
30.8
通讯作者：
de Massy, B
中科院分区：
文献类型：
--
作者：
Guillon, H;de Massy, B
在减数分裂过程中，同源染色体在第一次减数分裂时的还原分离需要同源染色体之间的互换(交换)(1)。交叉的数量受到严格的控制(在小鼠2中，每个同源基因一到两个)，它们在基因组中的分布并不是随机的--可以识别出‘热’和‘冷’区域(3，4)。我们开发了一种分子分析方法，直接在小鼠生殖细胞中研究这些事件。这一分析是参考通过遗传分析确定的蛋白质体β9型亚单位(Psmb9，以前称为LMP2)热点区域(5，6)而开发的。根据两个观察结果，我们证明这个热点是减数分裂重组的起始点：(I)在210bp的区间内，基因的交换密度最大，在该区域的两侧，基因转换的频率降低；(Ii)在最高的交换密度区域，基因转换频率很高。然后，我们使用这一策略首次对小鼠精子发生中的减数分裂重组进行了时间分析，并证明了交叉事件发生在减数分裂前期的粗线期。
During meiosis, the reductional segregation of homologous chromosomes at the first meiotic division requires reciprocal exchange (crossing over) between homologs(1). The number of crossovers is tightly regulated (one to two per homolog in mice 2), and their distribution in the genome is not random-recombination 'hot' and 'cold' regions can be identified(3,4). We developed a molecular assay to study these events directly in mouse germ cells. This analysis was developed with reference to the proteosome subunit beta type 9 (Psmb9, previously called Lmp2) hot-spot region identified through genetic analysis(5,6). Here we show that this hot spot is an initiation site of meiotic recombination on the basis of two observations: (i) crossover density is maximal in an interval of 210 bp and decreases on both sides of this region; (ii) a high frequency of gene conversion is found in the region of highest crossover density. We then used this strategy to carry out the first temporal analysis of meiotic recombination in mouse spermatogenesis and demonstrate that crossover events occur during the pachytene stage of meiotic prophase.