Extended Data Fig. 5: Defect mediated tensile stress and its association with hole formation.
From: Mechanical stress driven by rigidity sensing governs epithelial stability
(a, b) Averaged isotropic stress, averaged stress xy (a’, b’) and averaged stress yy (a”, b”) around +1/2 defects on soft (2.3 kPa) gels (a, a’, a”) (n = 2924 defects) and stiff (30 kPa) gels (b, b’, b”) (n = 3632 defects) from 2 independent experiments. (c, c’) Averaged isotropic stress around -1/2 defects on (c) soft (2.3 kPa) gels (n = 2810 defects) and (c’) stiff (30 kPa) gels (n = 3716 defects) from 2 independent experiments. White dots indicate the location of the defect core. (d) Number of holes per mm2 that are triggered by each defect type in the preceding frame in comparison to regions where defects do not lead to hole formation (n = 20 circles from 4 independent experiments; two-tailed unpaired t-test, *P+ 1/2_-1/2 = 0.0210, ***P-1/2_none = 0.0004, ***P+ 1/2_none = 0.0004). Solid line represents mean and error bars represent standard deviation. (e) Averaged peak isotropic stress around a region of 25.6×25.6 µm obtained from a random defect that does not lead to a hole site and defects that lead to hole formation (n-1/2 random no-hole and hole = 16, n + 1/2 random and hole = 17; two-tailed unpaired t-test, *P-1/2random_-1/2hole = 0.0399, **P+ 1/2random_+1/2hole = 0.0052) from 3 independent experiments. While a region around the defect core was averaged for -1/2 defects, for +1/2 defects, stresses were averaged in the tail region of the defect. Solid line represents the mean and error bars represent the standard deviation. As shown in (e’) a region around the defect centre was averaged for -1/2 defects, while for +1/2 defects, stresses were averaged in the tail region of the defect. Peak areal averaged stress within a time frame of 20-40 minutes prior to hole formation was obtained as shown in (e”). Error bars represent standard deviation. (f) Box plot distribution of the average tensile stress around defect that led to cell division or stretching-related hole formation (ncell_div = 19, nstretching = 13; n.s.= not significant) from 4 independent experiments. Solid lines represent the mean and the error bars represent the standard deviation. Horizontal black line denotes the zero value. (g) Percentage of + /- 1/2 linked division and stretched cell linked hole formation on 2.3 kPa gels from 4 independent experiments. Error bars represent standard deviation. (h-h’) Scatter plot in the location of the nearest cell division (with the cell separation detected in the next frame) to (h) a + 1/2 defect and (h’) a + 1/2 defect. The spatial pattern displays no bias towards a particular region of space, as in the case of a random distribution of points. Red and blue cores represent the defect location and orientation. (i) Cumulative distribution of distances of cell divisions to their nearest defect, showing non-significant differences between experiments (solid blue curve) and random (Poisson) distributions (dashed green curve). Relatively minor differences arise at large distances (100-150 μm).
