Fig. 8. Nkx6.1 is required for zebrafish secondary motoneuron formation. (A) Nkx6.1 protein in 24 hpf wild-type spinal cord. (B) nkx6.1 MO-injected embryo has no detectable protein in spinal cord at 24 hpf. (C) Wild-type and (D) MO-injected 12 hpf embryos have the same pattern of isl1-positive PMNs. RBs are out of focus on each side of PMNs. (E) At 48 hpf, ventral spinal cord is full of Neurolin-positive SMNs. (F) MO-injected embryo has few remaining SMNs (75% of injected animals, n=565). The brightly-stained cuboidal cells are floorplate. (G) GABA antibody labels KA and VeLD interneurons in ventral spinal cord at 24 hpf. (H) In MO-injected embryos there is a dramatic increase in GABA-positive VeLD interneurons (n=21). Rostral to left in all images. A,B,E-H lateral views. C,D dorsal views Scale bar: 50 µm for A-D; 33 µm for E-H.