Fig. 5-S2

(A) Bright-field images of ppl explants from wt and MZfz7a/b mutant embryos either injected with Opto-Fz7 and 9-cis-retinal and kept in dark (red light for imaging, control 1), or injected with Rhodopsin and 9-cis-retinal and exposed to light (control 2), or injected with 9-cis-retinal and kept in light (control 3). Scale bar, 40 μm. (B) Fraction of ppl cells at the edge of the explants shown in (A) displaying lamellipodia-like protrusions after 4 hrs in culture, compared to MZfz7a/b and wt explants without Opto-Fz7 as shown in Figure 3B. N = 5 (Opto-Fz7, dark), 9 (Rhodopsin), 7 (9-cis-retinal), n.s., non significant (Mann-Whitney test). (C) Animal (upper panels) and lateral (lower panels) views of the notochord (nc) and prechordal plate (ppl) in MZfz7a/b mutant embryos injected either with rhodopsin mRNA together with 9-cis-retinal or with 9-cis-retinal only at the end of gastrulation (bud stage, 10 hpf) labeled by in situ hybridization for hgg (ppl), ntl (nc), and papc (paraxial mesoderm). Embryos were either exposed to light or kept in the dark. Scale bar, 250 μm. (D,E) Length-to-width ratio of the ppl (D) and distance between the anterior end of the nc and the posterior end of the ppl (E) in MZfz7a/b mutant embryos injected either with rhodopsin mRNA together with 9-cis-retinal or with 9-cis-retinal only, either exposed to light (sky blue) or kept in the dark (black). Untreated MZfz7a/b mutant (purple) embryos were included as controls. Error bars, standard deviations. N = 15 (MZfz7a/b), 15 (cis-retinal, light), 17 (cis-retinal, dark), 30 (Rhodopsin, light), 31 (Rhodopsin, dark), **p<0.01, and n.s., non significant (ANOVA followed by Tukey’s multiple comparison test).