Fig. 2

Identified ECR3‐D2 is a heart‐specific enhancer. A, Heart‐related TF distribution in the 127‐bp sequence. The bold gray DNA sequence indicates TF binding sites, and to avoid overlap, the Gata4 binding sequence is marked in red. B, Structure of the ECR3‐D2 plasmid. ECR3‐D2 is a 42‐bp DNA fragment located inside the 127‐bp length of ECR3. The ECR3‐D2 sequence was then cloned into the enhancer‐activity‐detecting construct. C, ECR3‐D2 drives GFP expression in the heart. Photos were taken with the GFP channel in the lateral position at 24 hpf and 48hpf and supine position at 72 hpf and 96 hpf. The images below show an enlarged view of the above embryos. Red curve: outline of the heart; A, atrium; and V, ventricle. Scale bars = 100 μm in all panels. D, Dual luciferase results. The ECR3‐D2‐luciferase vector was transfected into HEK293 cells, and the transfection efficiency was controlled by co‐transfection with a Renilla reporter construct. The p value of the difference between ECR3 and ECR3‐D2 is 0.0118, and the P value of the difference between ECR3‐D2 and E1b is lower than 0.0001