Hif-1α is required for neural crest migration. (A–Q) Xenopus (A–H) and zebrafish (I–Q) embryos were injected with antisense MOs as indicated in the figure, and the expression of the neural crest markers Snail2 (A–H) or crestin (I–M) was analyzed. Asterisks show the injected side. (A–D) No effect of ATGMOhif-1α on neural crest induction. (E–H) Strong effect of ATGMOhif-1α on neural crest migration. (I–J′) Dorsal (I and J) or lateral (I′ and J′) view of zebrafish embryos. (J) Note that in ATGMOhif-1α–injected embryos, neural crests are present around to the dorsal midline. (L) Percentage of embryos with the described phenotype. (M) The number of neural crest streams was counted by analyzing the expression of crestin for each treatment. (K, K′, and M) Note that the number of streams is reduced with the ATGMOhif-1α but rescued by the coinjection of Hif-1α mRNA. (N–Q) Analysis of cartilage development in zebrafish embryos. The bars in D, H, L, M, and Q histograms represent the standard deviations of three independent experiments, with ∼40 embryos used in each case. som, somite.