Table 1 Gene conversion and other events causing LOH in mitosis as a result of instability at fragile site FS2
StrainaDescriptionTreatmentReplication stress levelTotal colonies screenedTotal sectored coloniesFrequency of mitotic events causing LOH (× 10−5)
All LOH eventsCrossoverbGene conversioncBIRdChr losse
Control diploid #1 (Y722)Native POL1; isogenic with Y657No galn = 27,445n = 726 (20–60) [1]f0 (0–10) [1]4 (0–10) [1]0 (0–10) [1]22 (10–50) [1]
Experimental diploid #1 (Y657)GAL-POL1, SUP4-o near FS2High gal+n = 41,472n = 86207 (170–260) [8]24 (10–40) [5]41 (20–60) [10]77 (60–110) [15]65 (50–100) [3]
Experimental diploid #1 (Y657)GAL-POL1, SUP4-o near FS2No gal+++n = 10,896gn = 2602395 (2120–2690) [92]18 (10–70) [4]174 (110–270) [44]1019 (850–1230) [204]1184 (990–1400) [54]
Control diploid #2 (AMC358)Native POL1; isogenic with AMC355No galn = 43,591n = 12 (0–10) [0.1]0002 (0–10) [0.1]
Experimental diploid #2 (AMC355)GAL-POL1, ADE2 near FS2No gal+++n = 12,416n = 3392730 (2470–3040) [105]97 (70–190) [19]153 (100–240) [38]1442 (1240–1650) [288]1039 (880–1230) [47]
  • ― indicates no replication stress, + indicates a low level of replication stress, and +++ indicates high levels of replication stress. Chr, chromosome; gal, galactose.

  • a All diploids result from mating a MS71-derived haploid (Kokoska et al. 2000) with a YJM789-derived haploid (Wei et al. 2007). Each haploid is isogenic with its parent strain, except for changes introduced by transformation (described in Table S1 and Table S2).

  • b The frequency of RCOs was calculated as 2 × (number of crossover events ÷ total colonies). All of the crossovers that we observed were associated with gene conversion.

  • c Only gene-conversion events unassociated with crossover are reported here.

  • d Only BIR events that result from a break on the chromosome containing the SUP4-o allele or ADE2 allele can be detected as a red/light pink or red/white sectored colony. Therefore, the BIR reported here results from breaks on the MS71-derived chromosome III homolog.

  • e Only loss of the chromosome containing the SUP4-o allele or ADE2 allele can be detected as a red/light pink or red/white sectored colony. Therefore, the loss here is of the MS71-derived chromosome III homolog.

  • f The number in parenthesis is the 95% C.I. The number in square brackets is fold change from Y722 in no galactose.

  • g In the low galactose treatment of Y647, 10,896 colonies were fully analyzed for crossovers, BIR, and chromosome loss. An additional 28,083 colonies were screened only to identify and collect additional gene conversion and crossover events and are not included in this frequency calculation.