FIGURE 2: Regulation of expression of btuB1 and btuB2. (A) Model of the genomic plasmid insertion to generate AFS-I-PbtuB1 and AFS-I-PbtuB2. White triangle marks the position of the predicted promoter start. (B) Genomic DNA isolated from wild-type Anabaena, AFS-I-PbtuB1 and AFS-I-PbtuB2 was used for PCR with gene-specific (lane 1) or a plasmid- and a gene-specific primer pair (lane 2) as indicated in the model on top. (C) Wild-type Anabaena, AFS-I-PbtuB1 (blue) and AFS-I-PbtuB2 (orange) were grown in YBG11 medium without cobalt for seven (first bar) or ten days (second bar). After seven days the culture was transferred for growth for three days in YBG11 medium with 5 µM CoCl₂ (++Co, third bar). The ratio of the GFP fluorescence of the mutant strain and the background in wild-type Anabaena is shown. (D) gDNA (lane 1) and cDNA (lane 2 and 3) of Anabaena grown for 14 days in YBG11 medium without cobalt and subsequently grown for seven days in YBG11 without cobalt (lane 1 and 2), but with 5 µM cobalamin (+Cbl, lane 3) media was analyzed by PCR using oligonucleotides for the indicated genes. In (C) the average of three independent experiments is shown; error bars indicate standard deviations and the letters indicate the ranks based on statistical analysis performed using ANOVA (p<0.05).