Fig. 1. The kbp^st23 mutation disrupts axonal development. (A,B) Lateral views of PLLn axons in live embryos bearing the Tg(HuC:kaede) transgene at 28 hpf. Axons of the wild type (A) have advanced further posterior than those in the kbp^st23 mutant (B). The images show the segment of the nerve corresponding to about somites 6-12. Anterior is towards the left and dorsal towards the top. (C,D) Lateral views of spinal cord axons in live embryos bearing the Tg(HuC:kaede) transgene at 30 hpf. The arrowheads indicate the posterior-most axons in the ventral spinal cord tract in the wild type (C) and the kbp^st23 mutant (D). The images show the segment of the spinal cord corresponding to about somites 14-20. Anterior is towards the left and dorsal towards the top. (E,F) Lateral views of embryos at 72 hpf showing neurons labeled with anti-HuC/D in the spinal cord (SC) and enteric nervous system (ENS) of a wild-type (E) and kbp^st23 mutant (F). There are no discernable differences in neuronal organization between kbp^st23 mutants and siblings. (G,H) Lateral views of live larvae at 6 dpf show no obvious morphological differences between wild-type (G) and kbp^st23 mutant (H) larvae. The genotypes of all specimens were determined after photography (see Materials and methods).