Figure 5.

Effect of cell growth rate on the strength of the adaptive response. (A) Schematic shows replication of the circular E. coli chromosome during slow (blue) and fast (yellow) cell growth. DNA replication initiates at oriC and proceeds bidirectional toward ter. For fast growth, initiation occurs before completion of the previous replication round. The ada gene is located close to ter, so the gene copy number does not increase at faster growth. (B) Example time traces show the size of a cell growing in minimal medium plus glycerol at 75 min per generation (blue) or in minimal medium plus glucose at 42 min per generation (yellow). Division times are indicated by vertical lines. (C) Single-cell time traces of Ada expression from time-lapse microscopy with 100 μM MMS treatment for cells growing in glycerol (blue) or glucose (yellow) medium, respectively. Vertical lines indicate times when MMS was removed. (D) Simulation of the experiment in (B) is shown. Single-cell traces of total Ada for slow (blue) and fast (yellow) growth with 100 μM MMS treatment are shown. To see this figure in color, go online.