Fig. 4.

RhoA promotes chiral counterrotating actomyosin flow via CYK-1/Formin activation. (A–D) (Top) Time-averaged flow fields overlaid on a still image of cortical NMY-2::GFP of (A) a wild-type embryo on RNAi control (L4440), (B) an ect-2(gf) mutant on RNAi control (L4440), (C) ect-2(gf); mlc-4(RNAi), and (D) ect-2(gf); cyk-1(RNAi). Mean velocity vectors are color coded for their angle with the anteroposterior axis. (Scale bar, 10 $\mathrm{\mu }$m.) Velocity scale arrow, 20 $\mathrm{\mu }$m/min. (Bottom) Mean x velocity (gray) and y velocity (red) in 18 bins along the anteroposterior axis. Dashed lines in the plots in B–D display the mean x- and y-velocity profiles in wild type. Error bars, SEM. n indicates the number of embryos. (E–G) Mean speed (E), chiral velocity $v_c$ (F), and chiral ratio $c_r$ (G) per embryo. Data points represent individual embryos. Blue stripe and area represent the mean with 95$\%$ confidence interval. Significance testing: Only conditions that are not significantly different are indicated in the diagrams (n.s., P $>$ 0.05, Wilcoxon rank sum test). The flow hyperchirality (red background in all panels) of ect-2(gf) is rescued in ect-2(gf); cyk-1(RNAi) (green background in all panels), but not in ect-2(gf); mlc-4(RNAi) (red background in all panels).