TABLE 3.

Therad50S allele is temperature sensitive for viable spore formation and mimics a putativerad32nuclease mutation at the restrictive temperature

	Genotypea			Relative viable spore yieldb (% of wild type)
Sporulation series	rad50	rad32	rec12c	25°	34°
I	+	+	+	100	100
II	+	+	117	16 ± 5	10 ± 3.1
III	S	+	+	23 ± 9.5	0.035 ± 0.013
IV	S	+	117	15 ± 3.2	5.6 ± 0.3
V	+	D65N	+	0.12 ± 0.095	0.011 ± 0.008
VI	+	D65N	117	70 ± 27	6.2 ± 0.83

^aDiploid strains were homozygous for the alleles shown.

^bCultures were sporulated on supplemented EMM2 plates. The results are from three independent experiments. The number of viable spores from each experiment was divided by the corresponding number of viable diploid cells deposited on the sporulation plate; the mean (±SEM) for each series was determined and expressed relative to the value of the wild type at each temperature. Wild-type values were 1.3 ± 0.55 (25°) and 6.8 ± 2.5 (34°).

^cThe rec12-117 allele results in the G202E substitution (data not shown) and appears to be null (Lin and Smith 1994).