Fig. 3

Differential expression of Smyhc genes in craniofacial muscles. (A) Lateral and ventral views of the dorsal group of craniofacial muscles at 96 hpf with slow troponin C (stnnC), smyhc1 (1 to 249 bp), smyhc2 (1 to 324 bp) or smyhc3 (1 to 129 bp) in situ hybridisation (see Fig. 1A,D,E,G for gross location of these muscles). The lap and do lack smyhc1 expression while smyhc3 expression is restricted to the lap. (B) Ventral views showing ventral craniofacial muscles at 96 hpf with slow troponin C (stnnC), smyhc1 (1 to 249 bp), smyhc2 (1 to 324 bp) or smyhc3 (1 to 129 bp) in situ hybridisation. The ima, sh, iob and posterior tv lack smyhc1 expression. (C) Lateral and ventral views of the dorsal group of craniofacial muscles at 96 hpf showing colocalisation of slow MyHC S58 antigen with smyhc2 (1 to 324 bp) in situ hybridisation and, in the ao and lo, with smyhc1:gfp. (D) Ventral view at 96 hpf showing colocalisation of smyhc1:gfp and smyhc2 (1 to 324 bp) in situ hybridisation with slow MyHC S58 antigen. In the am, some fibres express smyhc2 and S58 antigen but not smyhc1:gfp (blue arrows). Some fibres express S58 antigen but neither smyhc2 nor smyhc1:gfp (white arrows). The extraocular muscles have zones of S58 antigen-expressing fibres that co-express smyhc1:gfp and zones that do not (pink arrows). (E) Ventral view at 96 hpf showing expression of slow troponin C in situ hybridisation (stnnC) in all slow MyHC S58 antigen-expressing fibres. Scale bars: 25 μm. Abbreviations: abh, abductor hyoideus; am, adductor mandibulae; ao, adductor operculi; do, dilator operculi; hh, hyohyoidus; ih, interhyoideus; ima, intermandibularis anterior; imp, intermandibularis posterior; io, inferior oblique; iob, inferior obliquus; ir, inferior rectus, lap, levator arcus palatini; lo, levatator operculi; sh, sternohyoideus; tv, transversus ventralis.