Haber J E
Rosenstiel Center, Brandeis University, Waltham, MA 02254-9110, USA.
Bioessays. 1995 Jul;17(7):609-20. doi: 10.1002/bies.950170707.
The recombinational repair of chromosomal double-strand breaks (DSBs) is of critical importance to all organisms, who devote considerable genetic resources to ensuring such repair is accomplished. In Saccharomyces cerevisiae, DSB-mediated recombination can be initiated synchronously by the conditional expression of two site-specific endonucleases, HO or I-Scel. DNA undergoing recombination can then be extracted at intervals and analyzed. Recombination initiated by meiotic-specific DSBs can be followed in a similar fashion. This type of 'in vivo biochemistry' has been used to describe several discrete steps in two different homologous recombination pathways: gene conversion and single-strand annealing. The roles of specific proteins during recombination can be established by examining DNA in strains deleted for the corresponding gene. These same approaches are now becoming available for the study of recombination in both higher plants and animals. Physical monitoring can also be used to analyze nonhomologous recombination events, whose mechanisms appear to be conserved from yeast to mammals.
染色体双链断裂（DSB）的重组修复对所有生物体都至关重要，为此生物体投入了大量的遗传资源以确保这种修复得以完成。在酿酒酵母中，DSB介导的重组可通过两种位点特异性核酸内切酶HO或I-SceI的条件性表达同步启动。然后可以间隔提取正在进行重组的DNA并进行分析。减数分裂特异性DSB引发的重组也可以以类似方式进行追踪。这种“体内生物化学”已被用于描述两种不同同源重组途径中的几个离散步骤：基因转换和单链退火。通过检查缺失相应基因的菌株中的DNA，可以确定重组过程中特定蛋白质的作用。现在，这些相同的方法也可用于研究高等植物和动物中的重组。物理监测还可用于分析非同源重组事件，其机制似乎从酵母到哺乳动物都是保守的。
