Twist is required for myosin II stabilization and supracellular meshwork formation. (A) Twist is required to stabilize apical myosin II fibers after contraction. Time-lapse images of myosin-GFP (green) and membrane-mCherry (purple). Bar, 5 µm. (B) Quantification of apical area (red) and myosin intensity (blue) in individual cells from wild-type and twiRNAi embryos. (C) Twist is required to maintain cortical myosin II after a contraction pulse. Normalized myosin intensity for individual contraction pulses was averaged. Data are means ± SD, which is indicated by the error bars (control: n = 329 pulses, 120 cells, two embryos; twiRNAi: n = 524 pulses, 106 cells, two embryos). (D) Twist is required to stabilize myosin II rings. Time-lapse images of myosin-GFP in embryos treated with arm dsRNA together with either twi or fog/t48 dsRNA. Bar, 5 µm. (E) Myosin-GFP (top and bottom, green) in live control or twiRNAi embryos. Images were segmented using intensity and area thresholds to identify myosin II structures (bottom, red). Bar, 10 µm. (F) Twist is required to form the supracellular actomyosin meshwork. The area of the largest myosin II structure was quantified for each time point in videos of control-injected or twiRNAi embryos.