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Fig. 5 Osmotic gradients and tissue contractility promote fissuring (A) (Top) Tailfin over time from a 3-dpf larva lacerated in E3 (hypotonic medium) and expressing mCherry in basal cells: (TgBAC(ΔNp63:Gal4); Tg(UAS:mCherry)). Wound occurred 1–2 min earlier. (Bottom) Insets shown below the time-lapse series. (B) Larva wounded as in (A) in E3 supplemented with 270 mM sorbitol (isotonic medium). (C) Larva wounded as in (A) in E3 supplemented with 50 μM para-nitro blebbistatin. (A)–(C) are maximum-intensity Z projections from spinning disk confocal images. (D) Kymograph indicating the fissure index over time at a given distance from the wound, averaged from larvae wounded in hypotonic E3 (n = 30) or E3 supplemented with 270 mM sorbitol (n = 11), 50 μM para-nitro blebbistatin (n = 13), or 0.1% DMSO as a vehicle control for blebbistatin (n = 9). The fissure index was analyzed as described in STAR Methods and Figure 1. Data from larvae used in Figure 1F were incorporated into the average hypotonic fissure kymograph shown here (top left). (E) Quantified fissure dynamics for larvae that scored positively for fissure formation. Each dot is an individual larva (n ≥ 9). Thick and thin bars indicate the mean ± 1 standard deviation for that condition. According to one-way ANOVA followed by Tukey’s test, vehicle control is not significantly different from hypotonic (n.s., p > 0.05) and blebbistatin is significantly different from the vehicle control (p = 0.0010). Hypotonic data from Figure 1G is also plotted here for comparison. See also Videos S5 and S6.