Wnt5b–Ryk modulation of Ca²⁺ release. (A) Analyzing Ca²⁺ release in zebrafish blastula/epiboly stage embryos. Ca²⁺ detected by Fura-2 ratiometric dye. Sample ratio images collected at 15-s intervals with time t = 0 s compared with t = 15 s showing examples of Ca²⁺ release events in the EVL (arrowheads) and YSL (arrows). (B–D) Ryk knockdown blocks endogenous Ca²⁺ release. (B) Endogenous Ca²⁺ release in control embryo (Video 1). (C and D) Unilateral injection of Ryk MO reduced endogenous Ca²⁺ activity (C; Video 2); lineage tracer Texas red (TxR) co-mixed with Ryk MO reveals the injected side (D). (E–G) Ryk deficiency blocks Wnt5b-induced Ca²⁺ release. (E) Wnt5b injection activates Ca²⁺ release (Video 3). (F and G) Unilateral injection of Ryk MO suppressed Wnt5b-induced activation (F; Video 4); lineage tracer indicates the injected side (G). Arrows note the YSL.