Figure 2. Formation of IDs resulting from SSA between IRs of Ty1.

Repair of DSBs in yeast diploids was examined by PFGE. A. Formation of inverted dimers (inv dim) in rad51Δ diploids (AM960) containing intact FS2. DNA was prepared for PFGE 0, 1, 6, 8, 10,12 and 14 hours after induction of DSBs at MATa in AM960. Southern blots were probed with ADE1, which hybridizes with its normal locus on chromosome (Chr) I and to ADE1 insertions on Chr III (Fig. 1A). Cf represents the chromosome fragment resulting from cleavage by HO. An additional Cf band observed one hour after addition of galactose corresponds to the processed (partially single-stranded) form of the cut fragment (VanHulle and Malkova, unpublished observation). B, C, D. Formation of inv dims is defective in strains containing disruptions of FS2. An experiment similar to the one described in A, but with fewer time points, was conducted in strains isogenic to AM960, but with deletion of one or both Ty1 elements of FS2 on the MATa-containing Chr III. E. Formation of inv dims is normal in rad54Δ diploids. An experiment similar to the one described in A was performed in strains isogenic to AM960 but RAD51 rad54Δ All strains shown in A, B, C, D, and E are isogenic to each other and contain two copies of Chr I that are different in size from each other. The varied pattern of Chr I during PFGE analysis is the result of different running conditions. F. The amount of inv dim in AM960 and AM993 strains formed at the 14-hour time point calculated as the percentage of the amount of initial (unbroken) Chr III.