Figure 1.—

Centromere-proximal crossovers are associated with disomy. (A) Configuration of markers in strains used for the detection and analysis of chromosome III disomy and associated recombination events. (B) Map distances in five intervals from four-spore viable tetrads (converted to random spore data) are compared to map distances found in disomic spores derived from wild type and sgs1-Δ795 (materials and methods). Intervals where map distances in disomic spores are significantly different from map distances in tetrads are indicated by asterisks (*, P < 0.05; **, P ≪ 0.001). (C) Configuration of markers in the strain used to measure COs associated with gene conversion. (D) The frequency of crossing over associated with gene conversion is shown for monosomic Ura⁺ recombinants and for mating-competent Ura⁺ disomes. The results from monosomes and disomes are significantly different (P < 0.0001 using chi-square analysis).