Fig. 1.

Analysis of developmental expression of four genes encoding Ser/Thr kinases. Each strain contains a plasmid carrying the upstream intergenic region of the indicated locus fused to a promoterless gfp reporter gene. Photomicrographs are of filaments of the indicated reporter strains grown on nitrate (N+; top panels) or induced for 24 h on combined-nitrogen free medium (N−; bottom panels). For each sample, the top panel shows a DIC image and the bottom panel shows the corresponding GFP fluorescence image. Photomicroscopy settings were the same for all strains, but increased brightness and contrast were applied to fluorescence images of strains AMC1560 and AMC1563 to more clearly show GFP reporter expression in different cells. Locus alr3732 is the pknE gene. Heterocysts are indicated by arrowheads. Bar, 10 μm.