Extended Data Fig. 9: Distribution of stresses under the skin, under the primordium, and in the absence of the primordium.
From: Rear traction forces drive adherent tissue migration in vivo
a, Images of LamC1-sfGFP (left) and basal skin cell membranes (middle) from Supplementary Video 9. The LamC1-sfGFP intensity is pseudo-colored as a heat map. The area outlined by a dotted line was analyzed using Embryogram to calculate the traction stresses (right) pseudo-colored as temperature map (right). The arrowhead indicates a spot of transient accumulation of LamC1-sfGFP. Images are maximum-projected z-stacks. Scale bar = 5 μm. b, Quiver plots of the BM displacement at 0 min in the XY- and XZ-planes. The XZ-plane quiver plot shows a subset of the vector field outlined by the orange rectangle. The magnitude of the vectors was increased by a factor of 3 for visualization purposes. Scale bar = 5 μm. c, Image of cell membrane at −1 min with arrows indicating the direction of movement from time point −1 min to 0 min as determined by PIV. Vector magnitudes are magnified three-times. Scale bar = 5 μm. d, Quantification of traction stresses. Traction stresses at the three vertices closest to a given wrinkle were averaged. Individual data points are shown. Individiual data points are indicated. **: p=0.0027 (−1 min vs. 0 min), p=0.0043 (0 min vs. 2 min) and n.s.: p=0.1479 (0 min vs. 1 min), p=0.7341 (−1 min vs. 2 min) (two-tailed paired t-test). n = number of measured cells, N = number of embryos, n was used for statistical analysis. e, Quantification of LamC1-sfGFP accumulation during BM wrinkling. Intensity profiles were obtained from a line plot across the BM wrinkle at 0 min indicated by the arrowhead in a, and from line plots at the same location of the images at the time points −1 min and 1 min. Intensities were normalized to the mean intensities at time point −1 min. Mean and SD are shown. n = number of measurements, N = number of embryos. f, Deformation of the BM before, during, and after primordium (magenta) migration. Images are from Supplementary Video 8. The white arrow indicates the direction of migration. Scale bar = 5 μm. g, Quantification of the displacement of bleached marks (yellow circles 1–4 in f) relative to control bleached marks (cyan circles in f). h, Quiver plot of the stresses in the direction of primordium migration. The magnitude of the stress vectors is color-coded. i, Distribution of the tensile and shear stresses around the migrating primordium outlined by a dotted line. The value of each unique component of the stress tensor is colored as a temperature map. The X and Y direction are indicated. The Z direction is orthogonal to the image plane. j, Experimental design of the stress analysis with blocked primordium migration. k, Images of a heat-shocked control embryo at 0 min and 80 min of Supplementary Video 8. The dotted line indicates the region used for the analysis. Images are maximum-projected z-stacks. Scale bar = 50 μm. l, Quiver plot of the displacement vectors shown along the Z, Y and X axes. The magnitude of the displacement vectors is color coded. Scale bar = 10 μm. m, Quiver plot of the displacement vectors projected in the XY-plane. The magnitude of the vectors was increased twofold. Scale bar = 10 μm. n, Distribution of the traction stress magnitudes color-coded using a temperature map. Scale bar = 10 μm. o, Quiver plot of the stresses in the direction of horizontal myoseptum. The magnitude of the stress vectors is color-coded. Scale bar = 10 μm. (l–o) Data correspond to the at the 80 min time point of Supplementary Video 10.
