Non-equilibrium conditions must have been crucial for the assembly of the first informational polymers of early life, by supporting their formation and continuous enrichment in a long-lasting environment. Here, we explore how gas bubbles in water subjected to a thermal gradient, a likely scenario within crustal mafic rocks on the early Earth, drive a complex, continuous enrichment of prebiotic molecules. RNA precursors, monomers, active ribozymes, oligonucleotides and lipids are shown to (1) cycle between dry and wet states, enabling the central step of RNA phosphorylation, (2) accumulate at the gas–water interface to drastically increase ribozymatic activity, (3) condense into hydrogels, (4) form pure crystals and (5) encapsulate into protecting vesicle aggregates that subsequently undergo fission. These effects occur within less than 30 min. The findings unite, in one location, the physical conditions that were crucial for the chemical emergence of biopolymers. They suggest that heated microbubbles could have hosted the first cycles of molecular evolution.
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The data supporting the findings of this study are available within the paper and its Supplementary Information. Additional information and files are available from the corresponding author upon reasonable request. X-ray crystallographic data were also deposited at the Cambridge Crystallographic Data Centre (CCDC) under CCDC deposition no. 1847429.
The complete details of both simulations are documented in the html report and mph simulation files in the Supplementary Information.
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The authors thank L. Keil for help with data analysis. Financial support from the Simons Foundation (318881 to M.W.P. and 327125 to D.B.), the German Research Foundation (DFG) through CRC/SFB 235 Project P07 and SFB 1032 Project A04, DFG Grant BR2152/3-1 and the US–German Fulbright Program is acknowledged. H.M. is supported by the MaxSynBio consortium, which is jointly funded by the Federal Ministry of Education and Research of Germany and the Max Planck Society. H.M. and K.L.V. are supported by the Volkswagen Initiative ‘Life?—A Fresh Scientific Approach to the Basic Principles of Life’. A.K. is supported by a DFG fellowship through the Graduate School of Quantitative Biosciences Munich.
The authors declare no competing interests.
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The Supplementary Information file contains additional experimental methods as well as all supplementary figures and tables and a brief description of all supplementary videos.
Supplementary Video 1 shows the accumulation of a 132mer ssDNA strand in a 20 °C temperature difference at the contact line over time. In addition, the motion of 200 nm FAM-labelled polysterene beads tracking the flow profile of the chamber is shown.
Supplementary Video 2 shows the accumulation of the Hammerhead ribozyme at the interface.
Supplementary Video 3 shows the formation of a DNA hydrogel at the gas–water interface by self-complementary DNA. Also shown is the simultaneous accumulation of self-complementary RNA and non-complementary RNA.
In Supplementary Video 4, 100 nm oleic acid vesicles were accumulated together with a 72mer DNA at the interface.
Supplementary Video 5 shows a small bubble in a 150 µm-thick chamber filled with RAO.
Supplementary Video 6 shows the accumulation inside a bubble at a temperature gradient of 20 °C.
The Simulation File contains both the upright (Cartesian) as well as horizontally aligned (cylindrical) Comsol simulation files.
Crystallographic cif file for d-ribofuranosyl aminooxazoline; CCDC reference 1847429.
Structure factors file for d-ribofuranosyl aminooxazoline; CCDC reference 1847429.
Structure factors file for d-ribofuranosyl aminooxazoline; CCDC reference 1847429.