Global gene expression response of DS17690 and DS50661 strains to the presence and absence of PAA. Total RNA was obtained from P. chrysogenum strains DS17690 and DS50661, grown in the presence and absence of phenylacetic acid (PAA) in independent glucose-limited chemostat cultures at D = 0.03 h-1 and hybridized to Affymetrix GeneChip® microarrays. A: Pie chart of overall transcript differences of the DS50661 and DS17690 strains grown in the absence and presence of PAA. B: Results of the pairwise comparisons of the two strains and the two conditions. Red arrows indicate genes with a higher transcript level in the respective pairwise comparison, green arrows indicate genes with a lower transcript level.