Hif-1α is required cell autonomously for neural crest migration. (A–H) Frames of a time-lapse video (Video 1) of zebrafish embryos Tg(sox10:mRFP). Leader cells are shown pseudocolored in red for embryos injected with a control MO (A–C) or an ATGMOhif-1α (E–G). (D and H) Centered tracks of leader cells. (I and J) Analysis of cell directionality and velocity of leader cells under indicated conditions. Errors bars represent standard deviation of three independent experiments, with a minimal of 20 embryos in each case. ***, P < 0.005. (K–O) Xenopus graft experiments. (K) FDX/MOs were injected into the ectoderm of blastula embryos. At early neurula stages (St), the injected neural crest was grafted into noninjected embryos, and neural crest migration was analyzed in vivo. (L and N) Normal neural crest migration (n = 10, 80% migration). Arrows show migrating neural crest. (M and O) Inhibition of neural crest migration after ATGMOhif-1α injection (n = 10, 20% migration). (P) Western blot of whole neurula Xenopus embryos, under the indicated conditions. (Q) Western blot of cephalic Xenopus regions enriched in neural crest cells versus tail of young tadpoles that contain very few neural crest cells.