FtsZ localization in WT, Δ<i>divIVA</i>, Δ<i>gpsB</i> and Δ<i>divIVA</i>Δ<i>gpsB</i> cells.

<p>(A) FtsZ localization in WT, Δ<i>divIVA</i>, Δ<i>gpsB</i> and Δ<i>divIVA</i>Δ<i>gpsB</i> cells. Phase contrast (left), GFP fluorescent signal (middle) and overlays (right) between phase contrast (red) and GFP (green) images are shown. Arrows show helical organization of FtsZ. Scale bar, 5 µm. See also the unprocessed image of FtsZ localization in Δ<i>gpsB</i> cells in <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1004275#pgen.1004275.s005" target="_blank">Figure S5</a> showing that the FtsZ fluorescent signal is detected in all cells. (B) Immunofluorescence staining of fixed WT and Δ<i>gpsB</i> cells using anti-FtsZ polyclonal antibodies. DNA was counterstained with DAPI. Merged pictures show (upper panels) the overlay of FtsZ (red) and phase contrast images, and (lower panels) the overlay of FtsZ (red) and DAPI (blue). Higher magnifications of Δ<i>gpsB</i> cells highlighted with a white square are shown in the right row. Arrows show helical organization of FtsZ. Scale bar, 5 µm. (C) Fluorescence time-lapse microscopy of Δ<i>gpsB</i> cells producing FtsZ-GFP and grown in C+H medium at 30°C. Overlays between phase contrast (gray) and GFP (green) are shown. Stills are from Movie S2. Scale bar, 2 µm. Blue arrows point to cells in which the Z-ring helix-stretches until cell death. Red arrowheads point to helical structures of FtsZ. FtsZ-GFP is the only source of FtsZ in cells. <i>ftsZ-gfp</i> substitutes the native <i>ftsZ</i> gene at its chromosomal locus.