FIG 2.

Transcription of hetN but not patS is delayed in a ΔhetC mutant. Bright-field (left panel) and fluorescence (right panel) micrographs for detection of transcription from the patS (A and B) or hetN (C and D) promoters via fusions to gfp present in pAM1951 or pSMC126, respectively, in the wild type (A and C) and a ΔhetC mutant (B and D). Following growth on ammonia, cultures were analyzed at 9 h (A and B), 18 h (C), and 40 h (D) after the removal of combined nitrogen. Carets indicate (pro)heterocysts. Bar, 10 μm.