FIG 4.

The hetC gene product is necessary for movement of the inhibitors of differentiation from heterocysts. The wild type (A), ΔhetC (B), ΔpatS (C), ΔhetC ΔpatS (D), ΔhetN (E), and ΔhetC ΔhetN (F) strains harboring pPJAV247, which encodes YFP expressed from the patS promoter to mark heterocysts and HetR(H69Y)-CFP expressed from the copper-inducible petE promoter, were imaged 24 h (A, C, and D) or 48 h (B, E, and F) after the removal of combined nitrogen. From top to bottom: bright field, yellow fluorescence from PpatS-YFP, blue fluorescence from HetR(H69Y)-CFP, and the composite image. Carets indicate heterocysts. Bar, 10 μm.