TABLE 3.
Lac+ mutation rate determinations from fixed-time (43-h) colony counts
| dinB allelea and expt | No. of cultures | Mutation rate (no. of mutations/ cell/generation)b | Mean mutation rate (±SEM) (no. of mutations/cell/ generation) |
|---|---|---|---|
| dinB+ | |||
| 1 | 40 | 3.9 × 10−9 | 4.6 (±1) × 10−9 |
| 2 | 30 | 3.3 × 10−9 | |
| 3 | 40 | 6.7 × 10−9 | |
| dinB10 | |||
| 1 | 40 | 1.6 × 10−9 | 2.4 (±0.9) × 10−9 |
| 2 | 28 | 1.3 × 10−9 | |
| 3 | 40 | 4.2 × 10−9 | |
| Δ(dinB-yafN)::kan | |||
| 1 | 40 | 1.2 × 10−9 | 1.8 (±0.7) × 10−9 |
| 2 | 40 | 1.1 × 10−9 | |
| 3 | 40 | 3.1 × 10−9 |
a
The strains assayed were SMR4562, SMR5830, and SMR6111 (Table 1).
b
Determinations of mutation rates were performed by fluctuation tests as described in the text for Table 2, except that the colony counts from which mutation rates were calculated were all taken at a fixed time of 43 h of incubation after plating. Mutation rates were calculated by the method of the median (14).