Fig. 5. Expression analysis of the mylc-MSTN^pro transgene in F₁ transgenic embryos by in situ hybridization. The expression of the transgene was visualized by in situ hybridization with a probe that could hybridize with transcripts of both the endogenous myostatin gene and the prodomain transgene. (A,C,E,G-I) Expression of Myostatin prodomain transcripts in transgenic fish embryos of line 33. Strong expression of Myostatin prodomain was found in transgenic fish embryos. (B,D,F,J) In situ results of non-transgenic zebrafish embryos using the same probe. All embryos were analyzed at 24 h.p.f. except G (16 h.p.f.). (H-J) Cross sections showing the fast muscle-specific expression of the transgene directed by the rat mylc promoter. Note the absence of staining in the slow muscle pioneer region at the myoseptum region of the somite (arrow). Scale bars, 500 µm (A-D); 200 µm (E,F); 150 µm (G-J).