Fig. 2

miR-196 overexpression inhibits pectoral fin initiation. (A, C) Pectoral fin buds are readily detectable at 28 hpf and 48 hpf in normally developing uninjected control animals, but embryos overexpressing miR-196 (B, D) showed no evidence of a pectoral fin bud. Arrowheads mark the edges of pectoral fin buds. (E, F, H, I) Uninjected controls or miR-196 mismatch injected controls showed normal pectoral fins by 5 and 45 days post-fertilization (dpf), but larvae overexpressing miR-196 had not recovered pectoral fins by 5 dpf and became paraplegic adults (G, J, arrows point to missing pectoral fins). Pelvic fins were normal in fish with pectoral fin defects (J). (K–N) Dissected pectoral fins of 5 dpf larvae stained with Alcian blue for cartilage and Alizarin red for bone showed skeletal defects ranging from absence of the endochondral disc and scapulocoracoid (L, 42.3%, 234 total fins) to missing the endochondral disc but having part of scapulocoracoid (M, just 6%) to normal (N, 51.7%,). Abbreviations: cl, cleithrum; ed, endochondral disc; ov, otic vesicle; pf, pectoral fin or bud; pv, pelvic fin; sco, scapulocoracoid.