Table 2.
Effect of a recQ mutation on spontaneous or UV light-induced fromation of λ Spi− phage
| UV dose, J/m2 | Strain | Relevant mutation | Frequency of Spi− phages (10−7) per total λ phages (SE) | Frequency relative to control | Burst size |
|---|---|---|---|---|---|
| Experiment 1 | |||||
| 0 | HI1547* | wild type | 0.053 (0.009) | 1 | 94 |
| 0 | HI2034* | recQ1802 | 0.52 (0.11) | 22 | 47 |
| 25 | HI1547* | wild type | 0.99 (0.04) | 1 | 86 |
| 25 | HI2034* | recQ1802 | 17 (2.5) | 17 | 48 |
| 50 | HI1547* | wild type | 2.2 (0.50) | 1 | 72 |
| 50 | HI2034* | recQ1802 | 21 (2.5) | 9.5 | 35 |
| Experiment 2 | |||||
| 0 | HI1793† | wild type | 0.65 (0.13) | 1 | 7.3 |
| 0 | HI2002† | recQ1802 | 190 (31) | 290 | 3.4 |
| 4 | HI1793† | wild type | 3.2 (0.61) | 1 | 9.3 |
| 4 | HI2002† | recQ1802 | 290 (16) | 91 | 5.2 |
| 8 | HI1793† | wild type | 5.7 (1.1) | 1 | 13 |
| 8 | HI2002† | recQ1802 | 330 (14) | 58 | 5.2 |
E. coli λ cI857 lysogen or its recQ derivative grown to 2 × 108/ml was irradiated with UV light at several doses. The lysogen was induced by incubation at 42°C for 15 min with shaking and then incubated at 37°C for 2 hr. The frequency of λ Spi− phages per total phages was measured as described in Materials and Methods. Numbers are averages of four determinations.
*
Strains carrying λ cI857 prophage at the attB site.
†
Strains carrying λ cI857 prophage at the secondary site in the proB gene.