TABLE 3

Random spore analysis of two-point crosses

		Type III cross (low)^c		Type IV cross (high)^c
Mutations^a	Distance^b (bp)	ppm^d	Density^e	ppm^d	Density^e	Quotient^f
13 × 1	72	620	8.6	880	12.3	0.70
13 × 5	147	960	6.5	2,200	14.8	0.44
13 × 14	261	2100	7.9	4,600	17.5	0.45
13 × 9	371	6900	18.5	7,900	21.2	0.87
13 × 2	481	6800	14.1	9,500	19.8	0.71
13 × 10	605	8600	14.2	12,000	20.2	0.71
1 × 5	75	540	7.1	670	9.0	0.80
1 × 14	189	1700	8.9	2,300	12.0	0.74
1 × 9	299	5500	18.3	5,100	17.1	1.07
1 × 2	409	5000	12.2	5,800	14.3	0.86
1 × 10	533	5700	10.8	9,400	17.7	0.61
5 × 14	114	950	8.3	1,100	10.1	0.83
5 × 9	224	3700	16.6	3,500	15.8	1.05
5 × 2	334	4800	14.3	4,100	12.4	1.16
5 × 10	458	6000	13.2	5,900	12.8	1.03
14 × 9	110	1100	9.9	1,400	12.8	0.78
14 × 2	220	1600	7.3	2,000	9.3	0.79
14 × 10	344	2400	6.9	4,000	11.6	0.59
9 × 2	110	930	8.4	1,100	10.2	0.83
9 × 10	234	1900	8.2	2,400	10.3	0.80
2 × 10	124	480	3.9	750	6.0	0.64

↵^a The mutation stated first is the one closer to the 5′ end of the gene.
↵^b The distance between the mutation sites in base pairs.
↵^c In type III crosses, the mutation closer to the 5′ end is in the h⁻ strain; in type IV crosses, it is in the h⁺ strain.
↵^d Prototrophic recombinants per million spores (one experiment per cross).
↵^e Prototrophs per million divided by base pairs (distance between mutations).
↵^f Prototrophs per million of the type III cross divided by ppm of the type IV cross.