Fig. 2. Sister cells can divide in different planes.

a Model of cells undergoing division showing the previous (blue line), current (red line) and next (green D shape) division planes. Left image: if cells divide in three consecutive orthogonal planes then sister cells will inevitably divide in the same plane, perpendicular to the previous and current division planes. Right image: if the future division plane is not the same in both sister cells, then the orthogonal geometry of division is not respected in at least one of the sister cells, as exemplified by the left hemisphere where the next division will occur in a plane that is perpendicular to the current plane of division (in red) but not to the previous one (in blue). b Top panel: top view of 3D rendering of a Z-stack of images of COL EzrA-sGFP cells. Left panel shows the top view and right panel shows the view after rotating the 3D reconstruction to a perspective where division planes become perpendicular to the viewing plane, appearing as a cross. Scale bar, 1 µm. Bottom panel: model of the divisome of two sister cells, illustrating their orientation before and after rotation. Grey arrow indicates point of view after rotation. A full field of view can be accessed in https://figshare.com/s/907e54dd2d24e7c5dd05. c, d Histograms of angles formed by divisomes of sister cells showing that two sister cells very often select different planes of division. Measurements were performed using Z-stacks of images obtained from c COL strains expressing FtsZ^55-56GFP (n = 131), EzrA-GFP (n = 100) or GFP-FtsK (n = 76) and d COL (n = 100), JE2 (n = 70) and NCTC (n = 87) strains expressing EzrA-GFP and analysed using automated software (see Methods). Two to four biological replicates were imaged for each strain. Quantifications were done from a single experiment for each strain. Source data are provided as a Source data file.