Extended Data Fig. 4: Analysis of centrosome positioning and shape symmetry.
From: Self-generated gradients steer collective migration on viscoelastic collagen networks
a. Single z-slice and 3D projection of a cell cluster on a collagen network with pericentrin staining. Scale bar: 20μm. Right: Rendering of the 3D segmented nuclei (multicolor), cluster (gray) and paired centrosomes (red). Black arrows: centrosome orientation with respect to paired nucleus. Representative example from n=7 clusters, N=1 independent experiment. b. Shape asymmetry quantification. A center line (dotted black line) is drawn along the cluster length passing through the center of mass and parallel with the migration direction. At every pixel along the contour (red dot, for example), the distance x from the center of mass projected onto the center line is determined. The shape asymmetry index is calculated for each time frame as the sum of x3 over all contour points. Lower panel: histogram of the shape asymmetry from n=34 cells, N=5 independent experiments. c. Aspect ratio quantification. Using the Hull convex of the contour (blue dotted line) to minimize shape irregularities, the major axis x1 (dotted black line) is taken as the cluster diameter along the migration direction and passing through the center of mass (black dot). The minor axis x2 (dotted red line) is taken as the cluster diameter perpendicular to the migration direction and passing through the contour center of mass. The aspect ratio is x1/x2. Lower panel: histogram of the aspect ratio from n=34 clusters, N=5 independent experiments.
