Fig. 4.

Medaka nsh mutants showed rigid hearts with normal heart rhythm. The beating motions of medaka atrium and ventricle were captured with a high-speed camera and were analyzed with the motion vector prediction (MVP) method. (A) Phase-contrast images of medaka embryos of WT (left), nsh mutant (middle) and nsh mutant+MURF1 morpholino (right). The yellow squares in the images indicate the regions of interest (ROI) employed for the motion vector calculation of atrium wall. (B) Typical beating profile of atrium observed for WT (left), nsh mutant (middle) and nsh mutant+MURF1 morpholino (right). Motion velocity (the vertical scale) represents averaged motion vector length in the ROI. In both figures, each large peak followed by a small peak represents a single beat of atrium. Since we obtained the vector lengths simply from the square root of x²+y² (x and y represent the vector components), the systolic and diastolic peaks both had positive values. (C) Maximum velocities observed for systolic and diastolic motions in WT, nsh mutant and nsh mutant+MURF1 morpholino are shown for atrium and ventricle. Systolic and diastolic velocities were decreased in nsh mutants and were partially rescued by MURF1 morpholino, while the heart rate was not changed. Data are represented as means±s.e.m. (n=3).