Figure 4. E-Cadherin, F-actin and pMyosin localization and myosin dynamics before and during gastrulation movements.
(A and B) Transverse cryosections of stage 3 (A) and stage X (B) embryos stained with Phalloidin (A and B), pMyosin (A’ and B’) and E-Cadherin (A” and B”) antibodies. (A”’ and B”’) show the merged pictures.
(C-J) Confocal ortho-slices of stage 3 (C-F) and stage X (G-J) whole mount embryos stained with Phalloidin, pMyosin and E-Cadherin antibodies. Arrows point at F-actin and pMyosin accumulation, asterisks show free-contact cell interfaces, arrowheads point at basal E-Cadherin junctions.
(K) Left panel: time series of a GFP-Myosin electroporated cell showing localization at the cortex and at the cytokinetic furrow in a stage 3 embryo. Right panel: Example of images used for GFP-Myosin (heatmap color code) FRAP experiments, showing the region used for FRAP (arrowhead) of epithelial cells in stage X and 3 embryos.
(L) Left panel: FRAP curves of cortical GFP-Myosin in stage X (red) and stage3 (blue) embryos, errors bars indicate SEM, n= 30 and 61 for stage X and stage 3, respectively. Right panel: Common plot of mobile fraction for all FRAP experiments done at stage X and 3; associated average numbers of the mobile fraction of each fitted curve and statistical significance between the two stages obtained by a Mann Whitney t test, p-value < 10-5(****).
Scale bar is 10μm. See also Figure S2, S3 and S4.