Abstract

Emulsions of condensed droplets (condensates) enriched in proteins and RNA have been identified in virtually all biological processes and include structures such as nucleoli, stress granules, and germ granules. A critical feature of emulsions is that they are unstable and over time small droplets coalesce and grow to form larger droplets (coarsening) until an equilibrium is reached, leading to only two distinct phases. Biological systems have evolved unique solutions to counter coarsening, and most cellular emulsions exhibit unexpected stability, with small liquid droplets persisting for extended periods. We show that P granules, a dynamic yet stable emulsion in germ cells of C. elegans, are coated by nanoscale solid clusters of the protein, MEG -3, which prevents droplet growth by reducing surface tension and inhibiting coalescence.  Here, we will discuss the potential of interfacial clusters in the stabilization and regulation of dynamic cellular emulsions.