Northern analysis of genes showing decreased transcription upon illumination. Strains were grown on Mandels Andreotti minimal medium with 1% (w/v) glycerol as carbon source for 24 h in darkness (DD) and harvested after the indicated time (DL) of illumination (1800 lux, 25 μmol photons m-2s-1). A representative hybridization with 18S rRNA for every set of Northerns is given below the respective series. Transcript abundance is given below the blots and was measured for wild-type QM9414 (Q) and env1PAS- by densitometry to verify up-regulation until 60 min of illumination, related to 18S rRNA and normalized to the dark control of the wild-type strain (QM9414, 24 h, DD). If no transcript was detected in QM9414 in darkness, the values represent signal strength above background.