Autonomous Development of Compositional Diversity in Self-Spreading Flat Protocells

An experimental pathway to the spontaneous generation of compositionally diverse synthetic protocells is presented. The pathway is initiated by flat giant unilamellar vesicles (FGUVs) that originate from compositionally different multilamellar lipid reservoirs and undergo spontaneous spreading across solid surfaces. On contact, the spreading FGUVs merge to produce a concentration gradient in membrane lipids across the fusion interface. Subsequent reconstruction through a series of shape transformations produces a network of nanotube-connected lipid vesicles that inherit different ratios of the membrane constituents derived from the bilayers of the parent FGUVs. The fusion process leads to the engulfment of small FGUVs by larger FGUVs, mimicking predator-prey behavior in which the observable characteristics of the prey are lost but the constituents are carried by the predator FGUV to the next generation of lipid vesicles. We speculate that our results could provide a feasible pathway to autonomous protocell diversification in origin of life theories and highlight the possible role of solid surfaces in the development of diversity and rudimentary speciation of natural protocells on the early Earth. We present a feasible pathway leading to a rudimentary type of protocell diversity and speciation based on the fusion of flat giant unilamellar lipid vesicles on solid surfaces. image