Fig. 5

Ectopic expression of wild-type Tbx20 rescues whz mutant embryos.

(A, B) Lateral view of whz mutant embryos control-injected with KCl (A) and wild-type zebrafish tbx20 mRNA (B), respectively. (C) Ectopic expression of wild-type zebrafish tbx20 mRNA can rescue the heart phenotype of 73% of homozygous whz mutant embryos, whereas injection of KCl has no effect. (D, E) Dissected whz hearts injected with KCl (D) and wild-type tbx20 mRNA (E) are stained against MEF-2 (red) after incorporation of 5-ethynyl-2'-deoxyuridine (EdU; green) to visualize cardiomyocyte proliferation. (F) whz mutant hearts injected with wild-type tbx20 mRNA show significantly increased numbers of ventricular cardiomyocytes at 72 hpf (E) compared to control-injected whz mutants (D) (whz+tbx20 mRNA: 142.5±10 SD, whz + KCl: 87.82±10 SD, n = 10; p = 0.0001). (G) Ventricular cardiomyocyte proliferation in whz mutant embryos injected with tbx20 mRNA is significantly enhanced compared to control injected mutants at 72 hpf (whz+tbx20 mRNA: 7±3% SD, whz+KCl: 1±2% SD, n = 10; p = 0.0001).