Figure 7
Localization of FtsZ in strain CSL109 depleted of ZipN. (a) BG11-grown filaments of strains PCC 7120 (WT) and CSL109 (PND-zipN) were incubated during 2 days under culture conditions in BG110 plus ammonium medium and then prepared for immunofluorescence with anti-Anabaena FtsZ-protein antibodies and visualized by fluorescence microscopy. Merged bright-field and immunofluorescence images are shown. White arrows point to apparent midcell FtsZ rings, and yellow arrow to an aberrant filament-like structure. Magnification was the same for both micrographs. (b) Genomic structure of the ftsZ genomic region in strain PCC 7120 (WT, native region) and in the strains CSS85 and CSS86, expressing an FtsZ protein C-terminally fused to mut2-GFP in the PCC 7120 and the CSL109 background, respectively. NmR represents a Nm-resistance genetic determinant included in the plasmid inserted in the chromosome (grey trace) (see Materials and Methods for details) (upper part of the figure). Representative filaments of strains CSS85 and CSS86 incubated for 2 days in BG110 plus ammonium medium were visualized by confocal microscopy. Merged images of cyanobacterial autofluorescence (red) and GFP fluorescence (green) are shown in the lower part of the figure. White arrows point to midcell FtsZ rings. Some aberrant filament-like structures parallel (yellow arrows) or perpendicular (blue arrows) to the longer cell axis are also indicated. Demographic representations of the distribution of GFP fluorescence with regard to midcell over 276 cells of CSS85 and 324 cells of CSS86 are also shown.
