Figure 2

Experimental setup. Transcript profiles, of four E. coli strains (wild type, fis mutant, hns mutant and fis/hns double mutant) are compared under low (↓σ _density ) and high superhelical density (↑σ _density ), leading to four sets of differential expressed genes. The shading of the schematically depicted data sets on the right-hand side (black, dark gray, gray and white) will be used throughout the article.