FIGURE 3: Expression of btuB1, btuB2 and btuC in btuB loss-of-function mutants. (A) Model of the strategy for genomic plasmid insertion to generate AFS-I-btuB1 and AFS-I-btuB2. (B) Genomic DNA isolated from wild-type Anabaena and mutant strains AFS-I-btuB1 and AFS-I-btuB2 was used for PCR with gene-specific primers (lane 1), a gene-specific primer and a plasmid-specific 3' (lane 2) or 5' primer (lane 3). (C) The cDNA of the indicated strains grown in the absence of cobalt for 14 days and subsequently in the presence or absence of cobalt (+Co, green; -Co, magenta) for seven days was analyzed by qPCR and values were normalized to the expression level of rnpB. 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).