Excess FtsA levels stimulate production of smaller cells. (A) Fluorescence micrographs of Rx1 cells expressing PZngfp-ftsA, grown in prewarmed C+Y medium with 0, 0.05, 0.10, and 0.15 mM ZnCl2 at 28°C until the cells reached an OD of ∼0.3. Scale bar, 1 μm. (B) Anti-FtsA immunoblot showing the amounts of native FtsA and GFP-FtsA in uninduced or induced samples. (C) Cell length and width distributions for each induction condition are shown, overlaid onto the distribution profile (in black) from the no-ZnCl2 control culture.