Fig. 1

rbx1 mutant hearts exhibit a multi-layered myocardial wall phenotype

(A) TALENs targeting the first exon (E1) of rbx1; the bns148 allele has a 13 bp deletion. (B) Genotyping of rbx1^+/+, rbx1^+/− and rbx1^−/− using high resolution melt analysis. (C) Structure of WT Rbx1. (C′) Structure of the predicted mutant Rbx1, which contains 7 amino acids followed by 12 missense codons (red). (D, E′) Lateral views of 96 hpf rbx1^+/+ and rbx1^−/− larvae; mutants exhibit pericardial edema (arrow, E) as well as jaw formation defects (arrowhead, E′). (F–M) Confocal images (mid-sagittal sections) of Tg(myl7:EGFP-Hsa.HRAS) hearts from rbx1 animals at 60 (F–G), 72 (H–I), 80 (J–K) and 96 (L–M) hpf. Magnified views of dashed areas shown in top right corners. (N–Q) Percentage of inner layer CMs relative to the total number of CMs. At 60 (N) and 72 (O) hpf, no significant difference is observed between rbx1^+/? and rbx1^−/− animals. However, at 80 (P) and 96 (Q) hpf, rbx1^−/− larvae exhibit a higher percentage of inner layer CMs. Each dot represents one heart. Data are shown as mean ​± ​SEM. P-values calculated by Student's t-test. V: ventricle, A: atrium; scale bars, 500 ​μm (D–E), 50 ​μm (F–M).