Figure 6.

Less interhomolog DSB repair occurs at the ade6-3101 hotspot than at the ade6-3049 hotspot, and crossover DNA is strongly reduced.Diploid strains heterozygous for bub1-243 (L) and vtc4-1104 (R), flanking ade6 were used to distinguish intersister (IS) and interhomolog (IH) Holliday junctions (HJs) in (A) and crossover DNA in (B) (53). (A) mus81Δ strains were induced for meiosis and harvested at 5 h. DNA was digested with PmlI and ScaI and analyzed as in Figure 5 using a probe near the middle of ade6. IS HJs (black arrows) and IH HJs (white arrows) were quantified from three (ade6-3049) or six (ade6-3101 mug20-231) blots from two independent inductions; data are IS L/P1, IS R/P2, and IH/[(P1 + P2)/2], each as % ± SEM, where P1 and P2 are parental DNAs 1 and 2, respectively. The IS to IH ratio of HJs is indicated. (B) Strains with the indicated homozygous ade6 alleles were induced for meiosis and harvested at 5 hr; DNA was analyzed as in (A), except electrophoresis was in only one dimension. ade6-3057 is a non-hotspot control (Figure 1). R1 and R2 are reciprocal recombinant fragments. The fraction of crossover fragment, 2 × R2/(P1 + P2) because R1 can also arise from a partial restriction digestion, is based on three to five blots from two independent meiotic inductions; error bars indicate the SEM.