Increased expression of genes involved in iron acquisition of M. catarrhalis due to cold shock. A, increased mRNA levels of M. catarrhalis tbpB following to cold shock. Strain O35E, grown to midlogarithmic phase, was exposed for 1 h and 3 h to 26°C or 37°C. RNA was analyzed by quantitative real-time reverse-transcription PCR to determine the amount of tbpB and 16S rRNA transcripts. The graph shows one of three representative experiments done in triplicate. Data are presented as means ± 1 standard deviation. *, P< 0.05 for 26°C versus 37°C (one-way analysis of variance). B, C and D, increased mRNA levels of M. catarrhalis tbpB, tbpA, lbpB and lbpA due to cold shock. M. catarrhalis strain O35E and clinical isolates 300 and 415, grown to midlogarithmic phase either in BHI medium or in medium containing 30 μM desferioxamine (Desferal®), were exposed to 26°C or 37°C. RNA was analyzed by semi-quantitative reverse-transcription PCR. PCR products were analyzed on 1.5% agarose gels, stained with ethidium bromide and subsequently visualized. To confirm equal loading, PCR for 16S rRNA was performed in parallel. Ctrl indicates control reactions with no cDNA templates.