Time-lapse fluorescence microscopy. GFP–MreB filaments are highly dynamic and generally move away from mid-cell, whereas GFP–Mbl filaments move towards mid-cell. Frames are taken every 10 s, and all cells are equally scaled. (A,B,D) Cells expressing GFP–MreB, (A,B) exponentially growing cells, (C) single growing cell expressing GFP–Mbl and (D) fixed cell. White lines in (A) indicate two MreB bundles migrating in parallel towards the cell pole, and a white arrowhead indicates MreB filament visually making a full turn around the inner membrane periphery. White line in (C) indicates Mbl bundle migrating around the cell diameter, from cell pole towards mid-cell. Note that GFP–MreB filaments do not change in fixed cells in (D). Scale bar, 2 μm.