Instability at fragile site FS2 stimulates LOH by mitotic recombination and chromosome loss.

aAll diploids result from mating a MS71-derived haploid with a YJM789-derived haploid. Each haploid is isogenic with its parent strain, except for changes introduced by transformation (described in Table S1). MS71 is a LEU2 derivative of AMY125 (MATα ade5-1 leu2-3 trp1-289 ura3-52 his7-2) [64]. YJM789 is a derivative of a clinical yeast isolate (MATa ura3 gal2 ho::hisG) [42]. All diploids except AMC324 and AMC331 are homozygous GAL-POL1.bThe frequency of reciprocal crossovers was calculated as 2*(number of crossover events/total colonies).cOnly BIR events that result from a break on the chromosome containing the SUP4-o allele can be detected as a red/light pink sectored colony. Therefore, in Y332, Y382, AMC324, and AMC331, we report BIR resulting from breaks on the MS71-derived chromosome III. In AMC310, we report BIR resulting from breaks on the YJM789-derived chromosome III.dOnly loss of the chromosome containing the SUP4-o allele can be detected as a red/light pink sectored colony. Therefore, in Y332, Y382, AMC324, and AMC331, we report loss of the MS71-derived chromosome III. In AMC310, we report loss of the YJM789-derived chromosome III.eThe number in parenthesis is the 95% confidence interval. The number in brackets is the fold change from Y332 in high galactose. No local gene conversion at the SUP4-o locus was observed in any strain; therefore this category is not included in the table.