Fig. 5: Modulation of the network connectivity and F-actin length alter the cluster positioning.

The connectivity and F-actin length of actomyosin networks in the bulk space were modulated by adding actin-associated proteins. Error bars displayed in the wave period and velocity represent standard deviations from the mean periods and mean velocity averaged over three successive wave periods and waves, respectively. Cyan circles in the DC-ratio show the control data. Cyan circles and curves in the Edge-probability show the control data and the model fitting, respectively. (Top) Addition of the actin crosslinker, α-actinin (250 nM). The wave period T and initial contraction velocity v (inset) were fitted by T = 1.8 × 10−3Ddroplet + 45 (R2 < 0.01) and v = 1.9 × 10−2Ddroplet − 1.1 (R2 = 0.76), respectively (n = 25) (Supplementary Movie 15). Cluster diameter was fitted by Dcluster = 0.31Ddroplet (n = 175, R2 = 0.91). Edge-positioned probability was fitted by Eq. (2) using L = 6.1 μm and τ = 0.09 s. Transition diameter Dc = 115 μm. (Middle) Addition of the actin severing protein, gelsolin (300 nM). The wave period T and initial contraction velocity v were fitted by T = 1.5 × 10−2Ddroplet + 38 (R2 = 0.04) and v = 1.9 × 10−2Ddroplet − 1.4 (R2 = 0.81), respectively (n = 27) (Supplementary Movie 16). The cluster diameter was fitted by Dcluster = 0.29Ddroplet (n = 269, R2 = 0.89). Edge-positioned probability was fitted by Eq. (2) using L = 4.3 μm and τ = 0.46 s. Transition diameter Dc = 60 μm. (Bottom) Addition of actin polymerization activator, mDia2 (30 nM). The wave period T and initial contraction velocity v were fitted by T = 2.7 × 10−2Ddroplet + 34 (R2 = 0.26) and v = 2.4 × 10−2Ddroplet − 3.1 (R2 = 0.83), respectively (n = 27) (Supplementary Movie 17). The cluster diameter was fitted by Dcluster = 0.31Ddroplet (n = 224, R2 = 0.96). Edge-positioned probability was fitted by Eq. (2) using L = 10 μm and τ = 0.46 s. Transition diameter Dc = 138 μm. We confirmed that addition of actin-associated proteins had little influence on the cluster size distribution compared to the control experiments (Fig. 1h). Kolmogorov–Smirnov test was applied to the scatter plots of DC-ratio between Ddroplet = 50 µm – 150 µm (around the transition point in the control experiment). The distributions were significantly different from the control in all conditions (p < 0.01). We performed two independent experiments.