Model of Self Reproducing Vesicles

Abstract

Evolution of molecular assemblies toward a cellular life in prebiotic world is fascinating research filed in soft matter science. So far extensive investigations have been performed to construct molecular model system which expresses similar dynamics as those of a life system using well-defined organic molecules. Especially modeling of a self-reproducing vesicular system is a key concept to understand origin of the cellular life. In typical self-reproducing vesicle systems, membrane precursors are converted into membrane molecules with the help of a catalyst and the membrane molecules induce the formation of daughter vesicles. The self-reproducing vesicle systems have two pathways for the topology transition, the birthing and the budding. In the birthing pathway, new synthesized membrane molecules form daughter vesicles inside a mother vesicle. When the daughter vesicle grows to a certain size, it extrude through the membrane of the mother vesicle to the environment. On the other hand, in the budding pathway, the mother vesicle deforms to pear-like shape and is divided into two independent vesicles. We established a model self-reproducing vesicle system without the membrane molecule synthesis route. The model vesicle composed of cylinder- and inverse-cone-shaped lipids formed inclusion vesicles inside the mother vesicle and the inclusion vesicles were then expelled by a temperature cycling. By changing the vesicle composition, the mother vesicles showed the budding type self-reproduction pathway. A key concept of this system is the coupling of the main-chain transition and the shape of lipids.