Defects in Myo-II pulsing disrupt the integrity of the supracellular actomyosin meshwork. (A and B) Mean apical area (A) and normalized mean cellular Myo-II intensity (B) for representative sqh1 germline clone embryos expressing the indicated phosphomutants (n = 50 sqh-TS cells; n = 49 sqh-TA cells, and n = 50 sqh-AE cells). Shaded area is ±SD. (C) Box-and-whisker plot of cell constriction rates for multiple sqh1 germline clone embryos expressing the indicated phosphomutants (n = 102 sqh-TS cells, two embryos; n = 169 sqh-AE cells, three embryos; and n = 189 sqh-TA cells, three embryos). (D and E) Mean apical area (D) and normalized mean cellular Myo-II intensity (E) for representative embryos expressing the indicated shRNA (n = 78 control-shRNA cells; n = 31 MBS-shRNA cells). Apical area of cells in MBS-shRNA knockdown embryos were more heterogenous and larger than that of ctl-shRNA embryos; however, they undergo apical constriction. Shaded area is ±SD. (F) Box-and-whisker plot of constriction rates for multiple embryos expressing the indicated shRNA (n = 104 control-shRNA cells, two embryos; n = 78 MBS-shRNA cells, three embryos). (G–L) Myo-II phosphomutants and MBS knockdown cause separation of Myo-II networks between cells. Time-lapse images are of representative cells from sqh1 germline clone embryos with the indicated phosphomutants or from embryos expressing the indicated shRNA. Arrowheads indicate contraction of an intact supracellular Myo-II meshwork in control embryos (G and K) or instances of intercellular Myo-II network separation in mutants or knockdowns (H–J and L). Bars, 10 µm. Box-and-whisker plots display the median (central line), 25th and 75th percentiles (box edges), the most extreme data points not considered outliers (whiskers), and outliers (plotted individually). **, P < 0.01; n.s., not significant.
