Table 3 Synthetic-lethal interactions between ida5-1 and lat mutations
Cross (mt− × mt+)Tetrads analyzed4:03:12:2Number of tetrads tested by allele-specific PCRa
WT × WT5050000
WT × ida5-13633210
ida5-1 × WT2524010
ida5-1 × lat1-549132863 PD, 4 T
ida5-1 × lat2-151b264214 PD, 4 NPD
lat2-2 × ida5-18b4134 PD, 1 T, 3 NPD
ida5-1 × lat3-1601628164 PD, 4 NPD
ida5-1 × nap1-118b9634 PD, 2 T, 2 NPD
nap1-2 × ida5-115b5283 PD, 1 T, 4 NPD
nap1-3 × ida5-144b169190
  • a Classified initially on the presumption (based on the apparent synthetic lethality) that parental ditype (PD), tetratype (T), and nonparental ditype (NPD) tetrads were 4 live:0 dead, 3 live:1 dead, and 2 live:2 dead, respectively. In the indicated numbers of presumed T and NPD tetrads, all viable segregants were analyzed by allele-specific PCR; in the indicated numbers of presumed PD tetrads, either the two LatS (predicted IDA5 lat or IDA5 nap1-1) or the two LatR (predicted ida5-1 LAT or ida5-1 NAP1) segregants were analyzed by allele-specific PCR. All genotypes were consistent with the hypothesis of synthetic lethality between ida5-1 and the nap1 or other lat mutation as well as with the initial designation of tetrads as PD, T, or NPD. See Figure 9 for representative data.

  • b The high percentages of ditype tetrads indicate that IDA5, LAT2, and NAP1 are all located near their respective centromeres, a conclusion confirmed by obtaining high ditype percentages also in crosses of lat2 by nap1 and of either lat2 or nap1 by a paromomycin-resistance cassette that had fortuitously integrated near the chromosome VI centromere (data not shown).