Fig. 4

Translational inhibition by tbx5 morpholino. (A-K) Live embryos; (A,C,F,I) wild-type embryos; (B,D,G) embryos injected with 12.4 ng tbx5 morpholino (tbx5-MO); (E,H,J,K) embryos injected with 1.7 ng tbx5-MO. (A,B) Injection of 12.4 ng of tbx5-MO phenocopies heart stretching and pericardial edema of hst mutant embryos, and (C,D) eliminates bud formation at 48 hfp. (E) Injection of 1.7 ng of tbx5-MO delays the onset of bud formation to shortly before 48 hpf. (F,G) 12.4 ng tbx5-MO continues to inhibit bud formation at 3 dpf. (H) Buds of 1.7 ng-injected embryos grow slowly. (I-K) 6 dpf embryos. (I) Wild-type buds elongate to a growing fin. (J,K) 1.7 ng-injected embryos in which the initial buds develop into shorter up-turned fins. (J) Some embryos develop only one bud and hence one fin. (A-E) Lateral views; (F-K) dorsal views. a, atrium; v, ventricle; arrowheads, developing pectoral fin buds; brackets, regions where fin bud failed to develop.