FIGURE 2.

Induced contractility in the AS promotes dorsal closure. (A) Experimental scheme of optochemically (CaLM, Ca²⁺ uncaging by UV illumination) induced contraction of AS cells at the elliptical stage in Drosophila embryos. The target cells of UV illumination are blue, where the cell contractility is triggered optochemically. (B) Images from a time-lapse recording of an embryo expressing E-CadGFP after optochemically induced contraction in target AS cells. Target cells are highlighted in yellow. Image at 0 min is the first frame of a time-lapse recording after UV-laser illumination. The bottom panel shows images’ overlay at 2.5 and 5 min (green) with the image at 0 min (red). White arrow lines indicate the leading-edge displacements. (C) Time courses of the cross-sectional area of the target cells over 5 min after UV-laser illumination. Cell areas were normalized to their initial size at 0 min. Five independent experiments from five embryos, N = 15 target cells from five embryos, and three target cells from each embryo. (D) Quantification of the leading-edge displacement dorsally over 5 min after UV-laser illumination. The leading edge far away from the optochemically induced contracting AS cells in the same embryo was used as control. Five independent experiments from five embryos, two-way ANOVA, Sidak’s multiple comparison test, ****p < 0.0001. Curves represent the mean (bold line) with SD (ribbon band) in panels (C,D).