1
|
Ross D, Deamer D. Template-Directed Replication and Chiral Resolution during Wet-Dry Cycling in Hydrothermal Pools. Life (Basel) 2023; 13:1749. [PMID: 37629605 PMCID: PMC10456050 DOI: 10.3390/life13081749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 08/01/2023] [Accepted: 08/03/2023] [Indexed: 08/27/2023] Open
Abstract
The commonly supposed template-based format for RNA self-replication requires both duplex assembly and disassembly. This requisite binary provision presents a challenge to the development of a serviceable self-replication model since chemical reactions are thermochemically unidirectional. We submit that a solution to this problem lies in volcanic landmasses that engage in continuous cycles of wetting and drying and thus uniquely provide the twofold state required for self-replication. Moreover, they offer conditions that initiate chain branching, and thus furnish a path to autocatalytic self-replication. The foundations of this dual thermochemical landscape arise from the broad differences in the properties of the bulk water phase on the one hand, and the air/water interfacial regions that emerge in the evaporative stages on the other. With this reaction system as a basis and employing recognized thermochemical and kinetic parameters, we present simulations displaying the spontaneous and autocatalyzed conversion of racemic and unactivated RNA monomers to necessarily homochiral duplex structures over characteristic periods of years.
Collapse
Affiliation(s)
- David Ross
- SRI International, Menlo Park, CA 94025, USA
| | - David Deamer
- Department of Biomolecular Engineering, University of California, Santa Cruz, CA 95064, USA
| |
Collapse
|
2
|
Abstract
The roots of biological homochirality remain unknown despite decades of study. A commonly proposed path includes an initial small enantiomeric excess that was amplified over time, but a satisfactory source of the excess and a plausible amplification process have yet to be described. We propose here a route to oligonucleotide homochirality from unactivated racemic sources based upon the facts that duplex structures are inherently homochiral and their synthesis from strands of complementary string nucleotide subunits is both uncommonly rapid and exergonic. Simulations employing available kinetic and thermochemical data in an iterated sequence of three equilibria in dry/wet cycles running from unactivated and racemic RNA monomers through oligonucleotides to duplex structures have shown that the exceptional association rate distorts the otherwise simple equilibrium string and overcomes the severe kinetic and stoichiometric barriers to the pairing of the statistically scant homochiral fractions. The simulations reveal widespread deracemization and the full conversion of racemic monomers to populations of L- and D-duplexes in a succession of growth in which the initially formed duplexes are replaced over time with increasingly larger descendants. This claim is open to experimental testing.
Collapse
Affiliation(s)
- David Ross
- Retired, formerly SRI International, Menlo Park, California, USA
| | - David Deamer
- Department of Biomolecular Engineering, University of California, Santa Cruz, California, USA
| |
Collapse
|
3
|
'Whole Organism', Systems Biology, and Top-Down Criteria for Evaluating Scenarios for the Origin of Life. Life (Basel) 2021; 11:life11070690. [PMID: 34357062 PMCID: PMC8306273 DOI: 10.3390/life11070690] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 07/12/2021] [Accepted: 07/13/2021] [Indexed: 12/22/2022] Open
Abstract
While most advances in the study of the origin of life on Earth (OoLoE) are piecemeal, tested against the laws of chemistry and physics, ultimately the goal is to develop an overall scenario for life's origin(s). However, the dimensionality of non-equilibrium chemical systems, from the range of possible boundary conditions and chemical interactions, renders the application of chemical and physical laws difficult. Here we outline a set of simple criteria for evaluating OoLoE scenarios. These include the need for containment, steady energy and material flows, and structured spatial heterogeneity from the outset. The Principle of Continuity, the fact that all life today was derived from first life, suggests favoring scenarios with fewer non-analog (not seen in life today) to analog (seen in life today) transitions in the inferred first biochemical pathways. Top-down data also indicate that a complex metabolism predated ribozymes and enzymes, and that full cellular autonomy and motility occurred post-LUCA. Using these criteria, we find the alkaline hydrothermal vent microchamber complex scenario with a late evolving exploitation of the natural occurring pH (or Na+ gradient) by ATP synthase the most compelling. However, there are as yet so many unknowns, we also advocate for the continued development of as many plausible scenarios as possible.
Collapse
|
4
|
Russell MJ. The "Water Problem"( sic), the Illusory Pond and Life's Submarine Emergence-A Review. Life (Basel) 2021; 11:429. [PMID: 34068713 PMCID: PMC8151828 DOI: 10.3390/life11050429] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 04/30/2021] [Accepted: 05/01/2021] [Indexed: 01/10/2023] Open
Abstract
The assumption that there was a "water problem" at the emergence of life-that the Hadean Ocean was simply too wet and salty for life to have emerged in it-is here subjected to geological and experimental reality checks. The "warm little pond" that would take the place of the submarine alkaline vent theory (AVT), as recently extolled in the journal Nature, flies in the face of decades of geological, microbiological and evolutionary research and reasoning. To the present author, the evidence refuting the warm little pond scheme is overwhelming given the facts that (i) the early Earth was a water world, (ii) its all-enveloping ocean was never less than 4 km deep, (iii) there were no figurative "Icelands" or "Hawaiis", nor even an "Ontong Java" then because (iv) the solidifying magma ocean beneath was still too mushy to support such salient loadings on the oceanic crust. In place of the supposed warm little pond, we offer a well-protected mineral mound precipitated at a submarine alkaline vent as life's womb: in place of lipid membranes, we suggest peptides; we replace poisonous cyanide with ammonium and hydrazine; instead of deleterious radiation we have the appropriate life-giving redox and pH disequilibria; and in place of messy chemistry we offer the potential for life's emergence from the simplest of geochemically available molecules and ions focused at a submarine alkaline vent in the Hadean-specifically within the nano-confined flexible and redox active interlayer walls of the mixed-valent double layer oxyhydroxide mineral, fougerite/green rust comprising much of that mound.
Collapse
Affiliation(s)
- Michael J Russell
- Dipartimento di Chimica, Università degli Studi di Torino, via P. Giuria 7, 10125 Turin, Italy
| |
Collapse
|
5
|
Longo A, Damer B. Factoring Origin of Life Hypotheses into the Search for Life in the Solar System and Beyond. Life (Basel) 2020; 10:E52. [PMID: 32349245 PMCID: PMC7281141 DOI: 10.3390/life10050052] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 04/14/2020] [Accepted: 04/22/2020] [Indexed: 01/13/2023] Open
Abstract
Two widely-cited alternative hypotheses propose geological localities and biochemical mechanisms for life's origins. The first states that chemical energy available in submarine hydrothermal vents supported the formation of organic compounds and initiated primitive metabolic pathways which became incorporated in the earliest cells; the second proposes that protocells self-assembled from exogenous and geothermally-delivered monomers in freshwater hot springs. These alternative hypotheses are relevant to the fossil record of early life on Earth, and can be factored into the search for life elsewhere in the Solar System. This review summarizes the evidence supporting and challenging these hypotheses, and considers their implications for the search for life on various habitable worlds. It will discuss the relative probability that life could have emerged in environments on early Mars, on the icy moons of Jupiter and Saturn, and also the degree to which prebiotic chemistry could have advanced on Titan. These environments will be compared to ancient and modern terrestrial analogs to assess their habitability and biopreservation potential. Origins of life approaches can guide the biosignature detection strategies of the next generation of planetary science missions, which could in turn advance one or both of the leading alternative abiogenesis hypotheses.
Collapse
Affiliation(s)
- Alex Longo
- National Aeronautics and Space Administration Headquarters, Washington, DC 20546, USA
- Department of Geology, The University of North Carolina, Chapel Hill, NC 27599, USA
| | - Bruce Damer
- Department of Biomolecular Engineering, University of California, Santa Cruz, CA 95064, USA or
- Digital Space Research, Boulder Creek, CA 95006, USA
| |
Collapse
|
6
|
Damer B, Deamer D. The Hot Spring Hypothesis for an Origin of Life. ASTROBIOLOGY 2020; 20:429-452. [PMID: 31841362 PMCID: PMC7133448 DOI: 10.1089/ast.2019.2045] [Citation(s) in RCA: 178] [Impact Index Per Article: 44.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Accepted: 10/23/2019] [Indexed: 05/05/2023]
Abstract
We present a testable hypothesis related to an origin of life on land in which fluctuating volcanic hot spring pools play a central role. The hypothesis is based on experimental evidence that lipid-encapsulated polymers can be synthesized by cycles of hydration and dehydration to form protocells. Drawing on metaphors from the bootstrapping of a simple computer operating system, we show how protocells cycling through wet, dry, and moist phases will subject polymers to combinatorial selection and draw structural and catalytic functions out of initially random sequences, including structural stabilization, pore formation, and primitive metabolic activity. We propose that protocells aggregating into a hydrogel in the intermediate moist phase of wet-dry cycles represent a primitive progenote system. Progenote populations can undergo selection and distribution, construct niches in new environments, and enable a sharing network effect that can collectively evolve them into the first microbial communities. Laboratory and field experiments testing the first steps of the scenario are summarized. The scenario is then placed in a geological setting on the early Earth to suggest a plausible pathway from life's origin in chemically optimal freshwater hot spring pools to the emergence of microbial communities tolerant to more extreme conditions in dilute lakes and salty conditions in marine environments. A continuity is observed for biogenesis beginning with simple protocell aggregates, through the transitional form of the progenote, to robust microbial mats that leave the fossil imprints of stromatolites so representative in the rock record. A roadmap to future testing of the hypothesis is presented. We compare the oceanic vent with land-based pool scenarios for an origin of life and explore their implications for subsequent evolution to multicellular life such as plants. We conclude by utilizing the hypothesis to posit where life might also have emerged in habitats such as Mars or Saturn's icy moon Enceladus. "To postulate one fortuitously catalyzed reaction, perhaps catalyzed by a metal ion, might be reasonable, but to postulate a suite of them is to appeal to magic." -Leslie Orgel.
Collapse
Affiliation(s)
- Bruce Damer
- Department of Biomolecular Engineering, University of California, Santa Cruz, California
| | - David Deamer
- Department of Biomolecular Engineering, University of California, Santa Cruz, California
| |
Collapse
|
7
|
Preiner M, Asche S, Becker S, Betts HC, Boniface A, Camprubi E, Chandru K, Erastova V, Garg SG, Khawaja N, Kostyrka G, Machné R, Moggioli G, Muchowska KB, Neukirchen S, Peter B, Pichlhöfer E, Radványi Á, Rossetto D, Salditt A, Schmelling NM, Sousa FL, Tria FDK, Vörös D, Xavier JC. The Future of Origin of Life Research: Bridging Decades-Old Divisions. Life (Basel) 2020; 10:E20. [PMID: 32110893 PMCID: PMC7151616 DOI: 10.3390/life10030020] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 02/19/2020] [Accepted: 02/21/2020] [Indexed: 12/12/2022] Open
Abstract
Research on the origin of life is highly heterogeneous. After a peculiar historical development, it still includes strongly opposed views which potentially hinder progress. In the 1st Interdisciplinary Origin of Life Meeting, early-career researchers gathered to explore the commonalities between theories and approaches, critical divergence points, and expectations for the future. We find that even though classical approaches and theories-e.g. bottom-up and top-down, RNA world vs. metabolism-first-have been prevalent in origin of life research, they are ceasing to be mutually exclusive and they can and should feed integrating approaches. Here we focus on pressing questions and recent developments that bridge the classical disciplines and approaches, and highlight expectations for future endeavours in origin of life research.
Collapse
Affiliation(s)
- Martina Preiner
- Institute of Molecular Evolution, University of Düsseldorf, 40225 Düsseldorf, Germany; (S.G.G.); (F.D.K.T.)
| | - Silke Asche
- School of Chemistry, University of Glasgow, Glasgow G128QQ, UK;
| | - Sidney Becker
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK;
| | - Holly C. Betts
- School of Earth Sciences, University of Bristol, Bristol BS8 1RL, UK;
| | - Adrien Boniface
- Environmental Microbial Genomics, Laboratoire Ampère, Ecole Centrale de Lyon, Université de Lyon, 69130 Ecully, France;
| | - Eloi Camprubi
- Origins Center, Department of Earth Sciences, Utrecht University, 3584 CB Utrecht, The Netherlands;
| | - Kuhan Chandru
- Space Science Center (ANGKASA), Institute of Climate Change, Level 3, Research Complex, National University of Malaysia, UKM Bangi 43600, Selangor, Malaysia;
- Department of Physical Chemistry, University of Chemistry and Technology, Prague, Technicka 5, 16628 Prague 6–Dejvice, Czech Republic
| | - Valentina Erastova
- UK Centre for Astrobiology, School of Chemistry, University of Edinburgh, Edinburgh EH9 3FJ, UK;
| | - Sriram G. Garg
- Institute of Molecular Evolution, University of Düsseldorf, 40225 Düsseldorf, Germany; (S.G.G.); (F.D.K.T.)
| | - Nozair Khawaja
- Institut für Geologische Wissenschaften, Freie Universität Berlin, 12249 Berlin, Germany;
| | | | - Rainer Machné
- Institute of Synthetic Microbiology, University of Düsseldorf, 40225 Düsseldorf, Germany; (R.M.); (N.M.S.)
- Quantitative and Theoretical Biology, University of Düsseldorf, 40225 Düsseldorf, Germany
| | - Giacomo Moggioli
- School of Biological and Chemical Sciences, Queen Mary University of London, London E1 4DQ, UK;
| | - Kamila B. Muchowska
- Université de Strasbourg, CNRS, ISIS, 8 allée Gaspard Monge, 67000 Strasbourg, France;
| | - Sinje Neukirchen
- Archaea Biology and Ecogenomics Division, University of Vienna, 1090 Vienna, Austria; (S.N.); (E.P.); (F.L.S.)
| | - Benedikt Peter
- Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany;
| | - Edith Pichlhöfer
- Archaea Biology and Ecogenomics Division, University of Vienna, 1090 Vienna, Austria; (S.N.); (E.P.); (F.L.S.)
| | - Ádám Radványi
- Department of Plant Systematics, Ecology and Theoretical Biology, Eötvös Loránd University, Pázmány Péter sétány 1/C, 1117 Budapest, Hungary (D.V.)
- Institute of Evolution, MTA Centre for Ecological Research, Klebelsberg Kuno u. 3., H-8237 Tihany, Hungary
| | - Daniele Rossetto
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, 38123 Trento, Italy;
| | - Annalena Salditt
- Systems Biophysics, Physics Department, Ludwig-Maximilians-Universität München, 80799 Munich, Germany;
| | - Nicolas M. Schmelling
- Institute of Synthetic Microbiology, University of Düsseldorf, 40225 Düsseldorf, Germany; (R.M.); (N.M.S.)
- Cluster of Excellence on Plant Sciences (CEPLAS), University of Cologne, 50674 Cologne, Germany
| | - Filipa L. Sousa
- Archaea Biology and Ecogenomics Division, University of Vienna, 1090 Vienna, Austria; (S.N.); (E.P.); (F.L.S.)
| | - Fernando D. K. Tria
- Institute of Molecular Evolution, University of Düsseldorf, 40225 Düsseldorf, Germany; (S.G.G.); (F.D.K.T.)
| | - Dániel Vörös
- Department of Plant Systematics, Ecology and Theoretical Biology, Eötvös Loránd University, Pázmány Péter sétány 1/C, 1117 Budapest, Hungary (D.V.)
- Institute of Evolution, MTA Centre for Ecological Research, Klebelsberg Kuno u. 3., H-8237 Tihany, Hungary
| | - Joana C. Xavier
- Institute of Molecular Evolution, University of Düsseldorf, 40225 Düsseldorf, Germany; (S.G.G.); (F.D.K.T.)
| |
Collapse
|