Fig. 2. Increasing molecular crowding promotes synDrop nucleation but inhibits growth.
a, Averaged number of droplets per cell (hog1Δ S. cerevisiae) for one hour after synDrop induction with GA for control and two osmotic compression conditions. Error bars are standard error of mean (SEM). b, Total intensities of droplets normalized to the averaged value of control cells at 0 min. Data are mean ± SEM. c, Averaged number of droplets per cell and d, normalized droplet total intensity over one hour comparing control (DMSO) and decreased molecular crowding (Rapamycin, RAPA) conditions, as well as RAPA treatment with recovered molecular crowding (RAPA + 700 mM sorbitol). Data are mean ± SEM e, Median diffusivity of droplets at different time points post-induction in the same conditions as a & b. Error bars are SEM. f, Density plot of droplet diffusivity versus total intensity at all time points post-induction. (g-i), synDrops formed in mammalian HeLa cells after 1–2 hours of induction comparing control to osmotic compression conditions (100 mM or 150 mM sorbitol). g, Representative images, scale bar 10 μm. h, Phase diagram of synDrop formation as a function of BFP and GFP total intensities. i, Histogram of droplet GFP total intensities. (j-n), Analyses of MD simulations using HOOMD-blue comparing conditions with 0%, 35% and 50% volume fractions of crowder: j, Graph theory analyses (left) of cluster formation at early and later times with corresponding simulation renderings (right). k, Number of molecules within the largest cluster over time from five replicate simulations, denoted by different colors. l, Averaged cluster size (number of molecules) over time from five replicate simulations. The dashed line represents the power law fit for the initial 0.5 s, exponent denoted as α. Error bars are standard deviation (SD) of the averaged values of the five repeats. m, Cluster diffusivity versus cluster size (number of molecules) on the log-log scale. The black data points represent the mean of averaged values from five repeats, and the error bars correspond to the SD among these averaged values. The dashed black line represents the linear fit on the log-log scale and the fitted slope is labeled as the exponent. n, Effective dissociation constants (Kd) of a simplified monovalent system as a function of crowder volume fraction. Error bars are SD from five repeats.