Table 1.
Doubling times, number of origins, and cell mass of strains carrying mutated sites growing in minimal media supplemented with succinate.
| Site mutated | Doubling time (min) | Number of origins/cell | Relative cell massa | Origins/cell mass | Aib |
|---|---|---|---|---|---|
| None | 102 | 1.57 | 1.0 | 1.57 | 0.35 (36 min) |
| τ2ADP | 101 | 2.00 | 1.0 | 2.00 | 0.13 (13 min) |
| I1ADP | 102 | 1.81 | 1.0 | 1.81 | 0.18 (18 min) |
| I2ADP | 103 | 1.82 | 1.0 | 1.82 | 0.17 (18 min) |
| C2ADP | 102 | 1.81 | 1.0 | 1.81 | 0.18 (18 min) |
| C3ADP | 102 | 1.84 | 1.0 | 1.84 | 0.18 (18 min) |
| I3ADP | 103 | 1.80 | 1.0 | 1.80 | 0.18 (18 min) |
| τ2/I2ADP | 102 | 2.70 | 1.0 | 2.70 | 0.05 (5 min) |
| τ2/I3ADP | 101 | 2.05 | 1.0 | 2.05 | 0.11 (11 min) |
| I3/C3ADP | 102 | 1.83 | 1.0 | 1.83 | 0.18 (18 min) |
| I2/I3ADP | 102 | 2.00 | 1.0 | 2.00 | 0.13 (13 min) |
aRelative cell mass was measured by flow cytometry, using forward scattered light of mutant strain relative to the wild type strain.
bAi (age at initiation), as a fraction of the cell cycle generation time, was calculated using the formula Ai = -ln(1-F/2)/ln2 where F is the fraction of cells in a population that have not initiated chromosome replication, measured from flow cytometric histograms of cells treated with rifampicin and cephalexin (Figures 2, 3). The calculated Ai was multiplied by the generation time to give age of initiation in minutes.