Fig. 2

Cooperative activity of Hhip and Patched is required for restricted expression of myod in adaxial cells. (A–B) ptc1 is expressed in adaxial cells at bud stage in a control embryo (A) and is reduced by overexpression of hhip (B, arrow; 17/28 injected embryos). (C–F) In contrast, overexpression of hhip does not affect expression of wnt11, a marker of notochord, (C–D; 9/9 injected embryos) or dmrt2, a marker of paraxial mesoderm and somites (E–F, 13/14 injected embryos). (G–H) Overexpression of hhip inhibits myod expression. (G) myod is detected in adaxial cells and somites in a control embryo at the 8-somite stage. (H) myod expression is strongly reduced in a hhip mRNA-injected embryo (arrow, 25/46 injected embryos). (I–K) ptc1 expression is increased in a hhip-MO-injected embryo (I, arrow; 7/9 injected embryos). hhip-MO does not affect expression of wnt11 (J, 5/6 injected embryos) or dmrt2 (K, 11/11 injected embryos). (L–O) Reduction of Hhip and Ptc results in spread of myod expression laterally in the paraxial mesoderm. (L) Expression of myod in a control embryo. (M) Expression of myod is slightly upregulated in cells adjacent to adaxial cells in a hhip-MO-injected embryo (arrow, 23/93 injected embryos). (N) Injection of ptc-MO has a stronger effect than injection of hhip-MO (arrow, 21/27 injected embryos). (O) Reduction of both Hhip and Ptc causes a significant increase in myod expression in paraxial mesoderm (arrow, 27/27 injected embryos). Dorsal views, bud stage (A–D, I–J, L–O) and 8-somite stage (E–H, K), anterior towards the top. Scale bar: 200 μm.