Jessop Lea, Allers Thorsten, Lichten Michael
Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, USA.
Genetics. 2005 Mar;169(3):1353-67. doi: 10.1534/genetics.104.036509. Epub 2005 Jan 16.
To study the mechanism of meiotic recombination in Saccharomyces cerevisiae, we examined recombination in an interval where the majority of events are initiated at a single hotspot for DNA double-strand breaks (DSBs), with little or no expected contribution by outside initiation events. This interval contained infrequently corrected palindromic markers 300 bp to the left and 600 bp to the right of the DSB hotspot. Conversion of single markers occurred frequently, while conversion of both markers occurred rarely, and many of the tetrads in which both markers converted were the products of multiple events. These data indicate that most meiotic recombination intermediates are asymmetrically positioned around the initiating DSB, with a short (<300 bp) tract of heteroduplex DNA (hDNA) to one side and hDNA on the other side frequently extending 600 bp or more. One consequence of this asymmetry is the preferential concentration of crossovers in the vicinity of the initiating DSB.
为了研究酿酒酵母减数分裂重组的机制，我们在一个区间内检测了重组情况，在该区间内，大多数事件是在DNA双链断裂（DSB）的单个热点处起始的，外部起始事件的预期贡献很少或没有。这个区间在DSB热点左侧300 bp和右侧600 bp处包含校正频率较低的回文标记。单个标记的转换频繁发生，而两个标记的转换很少发生，并且两个标记都发生转换的许多四分体是多个事件的产物。这些数据表明，大多数减数分裂重组中间体围绕起始DSB不对称定位，一侧有短（<300 bp）的异源双链DNA（hDNA）片段，另一侧的hDNA经常延伸600 bp或更长。这种不对称的一个结果是交叉在起始DSB附近优先集中。
