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Figure 4
(A) Total tracks (Ventral View) obtained from a time-lapse movie of cardiac looping in an oug mutant. Each track is colour-coded and is assigned an ID number. (B) Track displacement vectors for each trace drawn in (A). (C) Track displacement vectors to be analyzed are selected, categorized by visual inspection and colour-labeled accordingly. (D) Detail of the track displacement vectors on the superior cardiac side and (E) on the inferior cardiac side. (F), (G) Lateral views of the selected tracks reveal no major displacement along the Z-axis. (H) Cumulative rotation angle for the ventricle (shades of red) and atrium (shades of blue) in oug hearts. Compare with Figure 2F; the chambers do not show separation. With the outflow of the heart as viewpoint, positive values represent anti-clockwise rotation and negative values represent clockwise rotation. (I) Comparison of the average angular velocity for each replicate per 1.5 hr time window displayed by the chambers analyzed in (H). Horizontal bars: mean values. (J–L) Twisting of the heart tube during cardiac looping. (J) Plot of the twisting angle (as defined in the main text and in Appendix 1- Supplementary Methods) in time. The looping defect in oug is due to a reduced twisting of the heart tube. Solid lines: Mean; shaded area: standard deviation. (K) Average twisting angle for the sample hearts 9 hr after the start of the timelapse (37 hpf). Horizontal bars: mean values. (L) The twisting velocity in 1.5 hr windows in the wt samples is significantly higher than in oug. Horizontal bars: mean values. Scale bars: (A–C): 100 µm.
Cardiac looping is defective in oug mutants due to absence of asymmetric rotation of the cardiac chambers.