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  (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 ).