Fig. 2

Moz and Hox2 genes function in CNC to control second-segment skeletal identity. (A-D,H,L,P,T) Facial skeletons from 4 dpf larvae. (A) Wild type. (B) moz^- control side of H. (C) hox2-MO animal (control side of D). (D) hox2-MO animal unilaterally rescued with wild-type CNC. (E,I) Schematics showing unilateral transplantation of wild-type CNC precursors (red) into moz^- hosts. fli1:GFP labels all CNC green. Wild-type CNC (red) populate the second segment (2) at 32 hpf (F,J) and by 4 dpf (G,H,K,L) form largely normal Hm, Sy, Ch, Op and Br skeletal elements in 8/10 moz^- hosts. Inset in F is a digital longitudinal section through the white line and shows co-localization of the transplant lineage tracer and the fli1:GFP. Lateral is up. In I-L, a hybrid skeleton was observed. In this example, M'-like (black line in L) and Ch cartilages were fused together, with M' consisting of moz^- host CNC (white lines in J and K), and Hm, Sy and Ch cartilages and Op osteocytes consisting entirely of wild-type donor CNC. (M) Schematic of transplantation of moz^- CNC (red and green) into wild-type hosts. Both donor and host are fli1:GFP⁺. (N) moz^- CNC (red) populate the second segment (2) at 36 hpf. (O,P) At 4 dpf, partial PQ'-like (^*) and M'-like (arrow) cartilages consist of moz^- donor CNC (white arrow), and a Sy-like element (arrowheads) forms primarily from wild-type host CNC. In 9/10 cases, moz^- CNC precursors formed jaw-like cartilages in a wild-type host. (Q) Schematic of transplantation of moz^-; fli1:GFP CNC (red and green) into b1092 hosts (note that hosts are fli1:GFP^-). moz^- CNC populate the first two segments (1,2) at 32 hpf (R) and by 4 dpf form moz^--like M' and Pq' cartilages (S,T) in 6/9 moz⁺ hosts. Scale bars: 50 µm.