Table 2.

Requirement for Mts1 and Mts2 in M26 hotspot but not basal meiotic recombination

Line	Relevant genotypes*		ade6 alleles crossed and Ade+ recombinant frequency (×104)†		Hotspot ratio‡	Hotspot ratio vs. wild-type basal§
	mts1/mts1	mts2/mts2	M375 × M210	M26 × M210
1	+/+	+/+	4.4  ±  0.6	83  ±  7.6	19	19
2	+/−	+/+	5.6  ±  1.6	45  ±  9.5	8.0	10
3	−/−	+/+	5.3  ±  1.4	5.4  ±  0.0	1.0	1.2
4	+/+	+/−	7.6  ±  0.1	27  ±  0.4	3.6	6.1
5	+/+	−/−	5.3  ±  0.6	4.9  ±  0.8	0.9	1.1
6	−/−	−/−	5.7  ±  1.1	7.0  ±  1.1	1.2	1.6

^*The (+) indicates mts1⁺ or mts2⁺, the (−) indicates deleted mts1 (mts1-D15∷ura4⁺) or deleted mts2 (mts2-D1∷his3⁺). In addition to the listed mts1, mts2, and ade6 alleles, all strains had the genotype leu1-32 ura4-D18 his3-D1 (Table 1). 

^†See Fig. 1 for positions of ade6 alleles. Standard genetic crosses (5, 14, 28) were conducted, and spores were plated on supplemented NBA minimal medium containing adenine (100 μg/ml) to determine the total viable spore titer (T) and on NBA medium lacking adenine to determine the ade6⁺ recombinant titer (R). The recombinant frequency in each experiment is R/T. Each cross was done with two pairs of strains bearing alleles in opposite configurations relative to the mating type alleles. No significant differences were observed, and the data were combined. Data are the mean ± SD of recombinant frequencies from 2 to 4 experiments. 

^‡Ratio of recombinant frequency from the M26 × M210 (hotspot) cross relative to that from the M375 × M210 (basal recombination) cross. 

^§Ratio of recombinant frequency from the M26 × M210 (hotspot) cross relative to that from the M375 × M210 (basal recombination) cross in wild type (mts1⁺ mts2⁺).