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Nature:抑制减数分裂的联会丝蛋白

来源:Nature中文网 2013-10-31 10:32

在减数分裂过程中(此时在染色体被分离到两个子细胞中之前其数量翻倍),同源染色体通过链的交换而在一个“X-结构”或一次交叉中被保持在一起。

交叉是由程序化的双联断裂启动的,而且一个断裂一旦形成,其附近的其他断裂的形成就会通过一个被称为“交叉干涉”的过程被抑制。

Anne Villeneuve及同事发现,“联会丝蛋白”(它们在成对的同源染色体周围形成一个涂层)负责这种干涉。

另外,一个交叉一旦出现,局部染色体结构就会被改变和加长,这些变化也许还有助于抑制进一步的交叉启动。(生物谷Bioon.com)

生物谷推荐的英文摘要

Nature    doi:10.1038/nature12577

Meiotic chromosome structures constrain and respond to designation of crossover sites

Diana E. Libuda,Satoru Uzawa,Barbara J. Meyer& Anne M. Villeneuve

Crossover recombination events between homologous chromosomes are required to form chiasmata, temporary connections between homologues that ensure their proper segregation at meiosis I1. Despite this requirement for crossovers and an excess of the double-strand DNA breaks that are the initiating events for meiotic recombination, most organisms make very few crossovers per chromosome pair2. Moreover, crossovers tend to inhibit the formation of other crossovers nearby on the same chromosome pair, a poorly understood phenomenon known as crossover interference3, 4. Here we show that the synaptonemal complex, a meiosis-specific structure that assembles between aligned homologous chromosomes, both constrains and is altered by crossover recombination events. Using a cytological marker of crossover sites in Caenorhabditis elegans5, we show that partial depletion of the synaptonemal complex central region proteins attenuates crossover interference, increasing crossovers and reducing the effective distance over which interference operates, indicating that synaptonemal complex proteins limit crossovers. Moreover, we show that crossovers are associated with a local 0.4–0.5-micrometre increase in chromosome axis length. We propose that meiotic crossover regulation operates as a self-limiting system in which meiotic chromosome structures establish an environment that promotes crossover formation, which in turn alters chromosome structure to inhibit other crossovers at additional sites.

 

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