Fig. 8
Expression of heterocyst differentiation regulator genes during nitrogen step-down. Expression of ntcA (a) and hetR (b) in wild-type (WT) and Δcse after nitrogen step-down. Cultures were grown in BG11 medium in 3% CO2 and then refreshed in BG110 medium lacking any source of combined nitrogen for a nitrogen step-down. RNA samples were taken at the timepoints indicated. Gene expression values were normalised to the reference gene rpoA and the timepoint 0 h values. Error bars indicate the standard deviation of mean values from three biological replicates (n = 3). Significant differences between WT and Δcse gene expression are indicated with asterisks (t-test P < 0.05)