Figure 3

Phenotypic variation in gene expression in 13 different environments. The coefficient of variation (CV) of log expression of PptsG-gfp, PmglB-gfp and PrpsM-gfp was plotted against the mean log expression. Expression of the reporters in different environments was compared to data for 1522 E.coli promoters [31] (light blue diamonds) that were measured in the early exponential phase in batch cultures containing arabinose as a sole carbon source. Circles represent measurements in chemostat environments and triangles represent measurements in batch cultures. Different color of triangles and circles represents different reporters: ptsG (green), mglB (blue) and rpsM (red). Power regression (i.e. linear regression on log-transformed data) was fitted to each set of three promoters measured in the same environment. Colors of fitted lines mark different carbon sources in the feed; full lines mark chemostat environments and dashed lines mark batch cultures. Each data point is the average over 2–5 independent replicates (except for data from [31]).