Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA.
Proc Natl Acad Sci U S A. 2010 Apr 20;107(16):7383-8. doi: 10.1073/pnas.1001940107. Epub 2010 Mar 15.
In a previous study, we mapped spontaneous mitotic reciprocal crossovers (RCOs) in a 120-kb interval of chromosome V of Saccharomyces cerevisiae. About three-quarters of the crossovers were associated with gene conversion tracts. About 40% of these conversion tracts had the pattern expected as a consequence of repair of a double-stranded DNA break (DSB) of an unreplicated chromosome. We test this hypothesis by examining the crossovers and gene conversion events induced by gamma irradiation in G1- and G2-arrested diploid yeast cells. The gene conversion patterns of G1-irradiated cells (but not G2-irradiated cells) mimic conversion events associated with spontaneous RCOs, confirming our previous conclusion that many spontaneous crossovers are initiated by a DSB on an unreplicated chromosome.
在之前的一项研究中,我们对酿酒酵母染色体 V 的 120kb 区间内的自发有丝分裂的交互重组(RCO)进行了定位。大约四分之三的重组与基因转换片段有关。这些转换片段中约有 40%的片段呈现出双链 DNA 断裂(DSB)修复的模式,而这种修复是未复制染色体的结果。我们通过检查 G1 和 G2 期被γ射线辐射的二倍体细胞中诱导的重组和基因转换事件来检验这一假说。G1 期辐射的细胞的基因转换模式(而非 G2 期辐射的细胞)与自发 RCO 相关的转换事件相似,这证实了我们之前的结论,即许多自发的重组是由未复制染色体上的 DSB 引发的。