(A–D) WT mib1 RNA injection triggers Ryk internalization in 20/21 embryos (B) but has no effect on Vangl2 localization (D, n = 23). (E–G) Mib1 morpholino injection reduces the number of Ryk endosomes that are present upon injection of Ryk-GFP RNA. Increasing the dose of Ryk-GFP RNA restores endosome number in mib1 morphants but not in embryos coinjected with Mib1ΔRF123. (H–J) The number of Ryk endosomes that are present upon injection of Ryk-GFP RNA (12 pg) is reduced in mib1 null mutants. mib1 morphant data from panel E are shown again for comparison. (K) Ryk-GFP RNA (12 pg) rescues axis extension in mib1 morphants but not in embryos coinjected with Mib1ΔRF123. (L) Similarly Ryk-GFP injection rescues axis extension in mib1tf91 mutants. (M) Ryk morpholino injection aggravates mib1 morphant axis extension phenotypes. (A–D,F,G,H,I) dorsal views of 90% epiboly stage embryos, anterior up, scalebars 10 µm. (K,L,M) Lateral views of bud stage embryos, anterior up, scalebars 200 µm. In (E,J) each data point represents the mean number of endosomes for 20 cells from a single embryo. For comparison J again includes the mib1 morphant from panel E. Bars represent mean values ± SEM. In (K,L,M) boxes represent mean values ± SD. See Figure 3—source data 1 for complete statistical information.
