Fig. 4. Mechanistic interpretation of vacuole growth rates and popping-based motility.
A Schematic of the mechanism of vacuole growth consistent with the observation of linear growth, and as captured in the model (Eqs. (1)–(3)). A DNA liquid droplet, with external radius Rd, is embedded with enzymes that continuously generate restriction fragments. The fragments randomly diffuse (as exemplified by the sketched tortuous paths), and exit either into the vacuole or the exterior. Fragments that accumulate in the vacuole generate an osmotic pressure, Π, that swells the vacuole against the Laplace pressure, 2γ/Rv, where Rv is the vacuole radius, and γ is the interfacial tension. B Mechanism of vacuole popping motility. Vacuoles open a pore upon reaching the exterior droplet interface. Hydraulic pressure within the vacuole, similar in magnitude to the osmotic pressure, drives solution outflow through the pore, sending the droplet jetting in the opposite direction.