Fig. 7. Induced DSB repair and sister chromatid exchange in the absence of Eme1. (A) Upper panel: schematic representation of the generation of a functional GFP gene by HR-mediated gene conversion. Transient I-SceI expression induces a DSB in a stably integrated construct bearing two non-functional GFP genes in tandem. HR- mediated gene conversion without crossing-over replaces the I-SceI with the BcgI site, and also restores GFP expression. Lower panel: quantification of GFP⁺ cells following I-SceI-induced DSB repair. Wild-type, Eme1^+/– and Eme1^–/– ES clones were analyzed by FACS to detect the proportion of GFP⁺ cells, indicative of successful gene conversion at the non-functional GFP locus. Wild-type, Eme1^+/– and Eme1^–/– ES clones showed no difference in the number of GFP⁺ cells, indicating equivalent HR-mediated gene conversion following an induced DSB. (B) Increased MMC-induced SCE in the absence of Eme1. The frequency of spontaneous SCE was similar between wild-type and Eme1^–/– ES cells. However, a 2-fold increase of MMC- induced SCE was observed in Eme1-deficient ES cells by comparison with wild-type cells. The number of metaphases analyzed is given in parentheses above the corresponding histogram.