Fig. 1.

Cluster analysis (14) of P. aeruginosa genes showing altered expression after growth in the presence of MPM collected from the airways of chronically infected CF patients. Indicated in the first and second columns are genes showing a >5-fold change in expression in M63 medium containing 10% MPM collected from two different CF patients relative to M63 alone (samples 1 and 2, respectively). Genes represented in green are repressed in response to signal(s) present in the MPM samples. Genes in red are activated. The role of the Rhl and Las QS systems in controlling the expression of these MPM-responsive genes was determined by comparing gene expression in a rhlR, lasR double mutant relative to wild type, both in the presence of 10% MPM (sample 1). In the third column, genes represented in green require the QS system for activation in MPM, genes in red require QS for repression in MPM and genes in black are QS-independent (<2-fold change). Black lines indicate genes previously shown to be regulated by the QS system (15, 16). Black dots denote genes specifically regulated by the Rhl QS system as inferred from Schuster and coworker (15).