Fig. 4

Results from stable transgenic lines are consistent with those from transient assays. A, C, E, G, I: Transgenic fish expressing GFP under the control of the V-1.9∼+0.3k fragment. B, D, F, H, J: Transgenic fish expressing GFP under the control of the V-0.5∼+0.3k fragment. GFP expression begins around the 21-somite stage (A, B). The Tg(V-1.9k:egfp) transgenic line expresses GFP only in the ventricle as well as in both embryonic (C, E, G) and adult stages (I), while the Tg(V-0.5k:egfp) line expresses GFP in the whole heart (D, F, H, J). Tg(V-1.9k:egfp) has an early onset and drives strong GFP expression in the extraocular muscles, pharyngeal muscles, and other muscle types (G; Supp. Fig. S3C, F), while Tg(V-0.5k:egfp) has a late onset and drives weak GFP expression in these muscles types (H; Supp. Fig. S3H). V, ventricle; A, atrium; E, extraocular muscles; P, pharyngeal muscles; BA, bulbus arteriosus. A,B: Dorsal view, anterior to the top. C,D: Head on view. E-H: Ventral view, anterior to the top. I,J: Dissected adult heart.