Figure 2.

Semi-quantitative RT-PCR analyses showing the impact of FurA overexpression on the transcriptional pattern of several predicted FurA targets. (A) Total RNA from the wild-type strain PCC 7120 (WT) and the furA overexpressing strain AG2770FurA (FurA⁺) were isolated from cells grown in standard BG-11 medium (+Fe²⁺) or iron deprived medium BG-11_-Fe (–Fe²⁺). (B) In the case of candidate targets involved in heterocyst differentiation, RNA was isolated from ammonium-grown cells subjected to nitrogen deficiency under iron-replete conditions (BG-11₀ medium) for the number of hours indicated. Housekeeping gene rnpB was used as control. Determinations for each gene were performed in the early exponential phase of PCR. Expression analyses of genes furA and isiA were included as controls of experimental conditions. All determinations were performed three times with independent biological samples, and the relevant portion of a representative gel is shown for each gene. Relative induction ratios are shown in Supplementary Tables S2 and S3.