Fig. 2.

YM causes defects to a subset of Edn1/Ednra-dependent lower jaw skeletal elements. (A-D) Lateral views of 6 dpf embryos treated with DMSO (A,C) or YM (B,D), shown in gross (A,B) or whole-mount skeletal preparations of larvae (C,D). The asterisk in B indicates the absence of an inflated swim bladder (sb). (E-J) Ventral (E-G) or lateral (H-J) views of flat-mounts for the viscerocranium from 6 dpf wild-type larvae treated with DMSO (E,H) or YM (F,I), or an untreated edn1^−/− larvae (G,J). In E,F,H,I, white outlines highlight the symplectic cartilage (sy). In F,I, black arrowheads indicate fusion of the jaw joint (jj), white arrowhead indicates fusion of the hyomandibular joint (hj) and the arrow indicates fusion of the opercle (op) and branchiostegal ray (bsr). In G,J, the white asterisk indicates absence of the ceratohyal (ch). (K) Frequency of defects in six Edn1/Ednra-dependent skeletal elements in larvae treated with YM from 16 to 36 hpf. Absence of structure, hypoplasia or fusion were scored as defects (accounting for sidedness). A total of 28 larvae were examined across two independent experiments. The effect of YM was determined to be statistically significant with a chi-square test (P=0.0001), comparing the number of defects in DMSO-treated larvae (0) to YM-treated larvae. (L) A schematic illustrating the four overlapping time intervals of YM application (gray bars). Numbers within bars represent the percentages of larvae exhibiting at least one defect to a Edn1/Ednra-dependent lower jaw structure. The total number of larvae examined is given in parentheses. Scale bars: 500 μm (A,C); 100 μm (E,H). hm, hyomandibular; Mc, Meckel's cartilage; pq, palatoquadrate; ptp, pterygoid process of the palatoquadrate.