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Fig. 6 Hh signaling induces zebrafish nkx6.1 expression. (A) 18 hpf wild-type expression of nkx6.1. (B) Dramatic dorsal expansion of nkx6.1 in an 18 hpf embryo ectopically expressing shh (shh OE, 87% of injected animals, n=283). (C) 12 hpf wild-type expression of nkx6.1. (D) 12 hpf syu mutant with reduced nkx6.1 expression. (E) 12 hpf syu mutant injected with ehh and twhh MOs. nkx6.1 expression is largely absent (28% of injected clutch from syu heterozygous parents, n=120). (F) Wild-type expression of nkx6.1 in spinal cord at 24 hpf. (G) 24 hpf syu mutant has wild-type levels of nkx6.1 expression in spinal cord. (H) Few nkx6.1-positive cells remain in a 24 hpf smu mutant spinal cord. (I) 24 hpf syu mutant injected with ehh and twhh MOs has no nkx6.1 expression in spinal cord (21% of injected clutch from syu heterozygous parents, n=128). C-D dorsal views; all others are lateral. Rostral to left in all images. Scale bar: 50 μm for A,B; 100 μm for C-E; 25 μm for F-I.