Membrane enclosed intracellular compartments have been exclusively associated with the eukaryotes, represented by the highly compartmentalized last eukaryotic common ancestor. Recent evidence showing the presence of membranous compartments with specific functions in archaea and bacteria makes it conceivable that the last universal common ancestor and its hypothetical precursor, the protocell, may have exhibited compartmentalization. To the authors’ knowledge, there are no experimental studies yet that have tested this hypothesis. They report on an autonomous subcompartmentalization mechanism for protocells which results in the transformation of initial subcompartments to daughter protocells. The process is solely determined by the fundamental materials properties and interfacial events, and does not require biological machinery or chemical energy supply. In the light of the authors’ findings, it is proposed that similar events may have taken place under early Earth conditions, leading to the development of compartmentalized cells and potentially, primitive division.

to assemble astonishing pieces of a complicated puzzle, and realized that further advancement requires input from multiple branches of science, not just biology as the primary life science. Detailed hypotheses have been established about the different scenarios of the emergence of life, including the "RNA world," [1] the "lipid world," [2] "replicator first," [3] "metabolism first," [4][5][6] and others. Although the origin of life is still surrounded by many open questions, our understanding of chemical, physicochemical, and biochemical processes possibly involved in the ancient events preceding Darwinian evolution has seen much progress. We have come a long way from Leduc's physicochemical, inorganic matter-centered view on the beginning of the evolution, yet the matter of the transition from nonliving to living matter still remains largely unsolved, and one of the great scientific problems of our time.The phylogenetic tree of different living domains reflects that life has evolved from simple to more complex structures, i.e., from single-to multicellular organisms. The oldest fossil evidence dating back 3.5 Gy (billion years) comes from stromatolites, [7][8][9][10] microorganismal residues in sedimentary rocks. [11] There appears to be a gap of knowledge regarding the period of evolution between the first primitive hypothetical cells and the fossilized ancient bacteria, which can be considered as an already advanced form of life. [12] It is highly likely that intermediate primitive cell precursors preceded the single-cell organisms. The hypothetical prebiotic structures that were the stepping stone to first self-sustaining living cells are commonly termed "protocells." The possibility of a strong link between the formation of protocells and the origin of life can today be reasonably assumed.One cannot easily proceed in the context of the evolution of cell-based organisms without briefly illuminating the concept of life as we know it on our planet. Over time, different requirements have been proposed for an entity to be considered alive. According to Tibor Ganti's chemoton model, [13] a protocell contains three autocatalytic subsystems: a membrane subsystem that keeps the components together and intact, a metabolic subsystem that captures energy and material resources, and an information subsystem that processes and transfers heritable information to progeny. To be considered alive, these subsystems must be unified and function co-operatively for the survival and evolution of the supersystem. Pohorille and Deamer suggested a modified set of 7 criteria related to the chemoton. [14] At about the same time, Oro defined the requirements by 10 characteristic features. [15] Despite their differences, these descriptions align well with NASA's broader definition of life: "a self-sustaining chemical system capable of Darwinian evolution."The origin of life is still one of humankind's great mysteries. At the transition between nonliving and living matter, protocells, initially featureless aggregates of abiotic matter, ga...

In this study, we have systematically investigated the formation of molecular phospholipid films on a variety of solid substrates fabricated from typical surface engineering materials and the fluidic properties of the lipid membranes formed on these substrates. The surface materials comprise of borosilicate glass, mica, SiO2, Al (native oxide), Al2O3, TiO2, ITO, SiC, Au, Teflon AF, SU-8, and graphene. We deposited the lipid films from small unilamellar vesicles (SUVs) by means of an open-space microfluidic device, observed the formation and development of the films by laser scanning confocal microscopy, and evaluated the mode and degree of coverage, fluidity, and integrity. In addition to previously established mechanisms of lipid membrane–surface interaction upon bulk addition of SUVs on solid supports, we observed nontrivial lipid adhesion phenomena, including reverse rolling of spreading bilayers, spontaneous nucleation and growth of multilamellar vesicles, and the formation of intact circular patches of double lipid bilayer membranes. Our findings allow for accurate prediction of membrane–surface interactions in microfabricated devices and experimental environments where model membranes are used as functional biomimetic coatings.

No abstract

Membrane enclosed intracellular compartments have been exclusively associated with the eukaryotes, represented by the highly compartmentalized last eukaryotic common ancestor. Recent evidence showing the presence of membranous compartments with specific functions in archaea and bacteria makes it conceivable that the last universal common ancestor and its hypothetical precursor, the protocell, could have exhibited compartmentalization. To our knowledge, there are no experimental studies yet that have tested this hypothesis. We report on an autonomous subcompartmentalization mechanism for protocells which results in the transformation of initial subcompartments to daughter protocells. The process is solely determined by the fundamental materials properties and interfacial events, and do not require biological machinery or chemical energy supply. In the light of our findings, we propose that similar events could have taken place under early Earth conditions, leading to the development of compartmentalized cells and potentially, primitive division.The origin of the eukaryotic cell is closely associated with the development of subcompartments, which create specific micro-environments to spatially or temporally regulate biochemical reactions, simultaneously. Until recently, cellular compartmentalization was associated solely with eukaryotic systems. Recent evidence shows that membrane-enclosed compartments also exist in other domains of life, such as in Archaea and Bacteria 1,2 . Archaea, for example, have acidocalcisomes, the membrane enclosed electron-dense granular organelles rich in calcium and phosphate, which is crucial for osmoregulation and calcium homeostasis 3 . In Cyanobacteria, membrane-bound thylakoids 4 , have been identified as compartments in which the light-dependent reactions of photosynthesis take place.Despite the differences between eukaryotic and prokaryotic compartments in terms of structural and functional complexity, the presence of membranous compartments in Procaryota 1 establishes a possibility of compartments having existed in protocells, and being evolutionarily conserved. There is essentially no experimental material, however, on how compartments could have consistently emerged from membranes in a prebiotic environment lacking membrane-shaping and -stabilizing proteins.Membrane-less laboratory models of cytoplasmic suborganization have been developed inside synthetic cells, i.e. giant unilamellar vesicles 5 . These models require moderately elaborate chemical systems. A few examples of the utilized materials and mechanisms to induce compartment formation involve thermo-responsive hydrogels 6 , pH driven protein (human serum albumin) localization 7 or a poly(ethylene glycol)-dextran aqueous two-phase system 8 . One study which report on the membrane-based multi-vesiculation inside amphiphilic compartments, has employed protein-ligand couples to induce this behavior, i.e. biotin-avidin conjugates 9 . Membrane-enveloped subcompartment formation in biological systems is therefore considered t...