Analyses of the transcription level of the soxB gene in C. litoralis under various incubation conditions. Cultures were grown in defined marine medium in the dark. The effect of thiosulfate was determined in media containing 2.5 mM L-glutamate as carbon source. The influence of reduced glutathione on soxB expression was determined by replacing this substrate with equimolar amounts of the amino acids L-glutamate, L-serine, and DL-glycine. The upper panel shows the results of a RT-PCR of the rpoZ gene, which was used to normalize mRNA levels in different samples of extracted RNA. The panel below shows results obtained with the same RNA samples after RT-PCR using specific soxB primers.