Verification of DNA affinity microarray results by quantitative RT-PCR. Total RNA of strains SMR5 and MH1 incubated for 30 min under nitrogen starvation was prepared and used as template for reverse transcription and PCR reaction. Specific primers were used for amplification of 100 bp fragments of target genes. (A) The gene msmeg_3084 was used as control; transcription of this housekeeping gene encoding glyceraldehyde-3-phosphate dehydrogenase was not significantly different in wild-type (grey bar) and glnR deletion strain (white bar). (B) Relative fold transcription of 20 target genes in the wild-type SMR5 was calculated (grey bars), while the transcription in the glnR deletion strain was set one (white bars). Relative fold transcription was calculated in normalization to the reference gene msmeg_3084. Genes are sorted according to their msmeg numbers.