Figure 3

alr3758 promoter- gfp was upregulated in heterocysts. A. Map of full length and truncated promoter regions upstream of alr3758 that were used to drive GFP reporter expression. Black bar indicates HetR binding site. B. Images show Anabaena cells carrying the reporter construct at 0 h for both the WT and ΔhetR mutant, and at 21 h for the WT after nitrogen deprivation in the DIC (top), TRITC/autofluorescence (middle), and GFP (bottom) channels. There was very low to no expression in the WT and ΔhetR backgrounds at 0 h. In the WT background at 21 hours after nitrogen deprivation, heterocysts showed an increase in fluorescence. Heterocysts are marked with a blue arrowhead.