The RNA World: molecular cooperation at the origins of life (original) (raw)

• Crick, F. H. C. The origin of the genetic code. J. Mol. Biol. 38, 367–379 (1968).
  Article CAS PubMed Google Scholar
• Orgel, L. E. Evolution of the genetic apparatus. J. Mol. Biol. 38, 381–393 (1968).
  Article CAS PubMed Google Scholar
• White, H. B. Coenzymes as fossils of an earlier metabolic state. J. Mol. Evol. 7, 101–104 (1976).
  Article CAS PubMed Google Scholar
• Kruger, K. et al. Self-splicing RNA: autoexcisionand autocyclization of the ribosomal RNA interveningsequence of Tetrahymena. Cell 31, 147–157 (1982).
  Article CAS PubMed Google Scholar
• Guerrier-Takada, C. et al. The RNA moiety of ribonuclease P is thecatalytic subunit of the enzyme. Cell 35, 849–857 (1983).
  Article CAS PubMed Google Scholar
• Nissan, P., Hansen, J., Ban, N., Moore, P. B. & Steitz, T. A. The structural basis of ribosome activity in peptide bond synthesis. Science 289, 920–930 (2000).
  Article Google Scholar
• Mills, D. R., Peterson, R. L. & Spiegelman, S. An extracellular darwinian evolution experiment with a self-duplicating nucleic acid molecule. Proc. Natl Acad. Sci. USA 58, 217–224 (1967).
  Article CAS PubMed PubMed Central Google Scholar
• Joyce, G. F. Forty years of in vitro evolution. Angew. Chem. Int. Ed. 46, 6420–6436 (2007). This review covers most of the test-tube evolutionary studies since the classic experiments by Spiegleman.
  Article CAS Google Scholar
• Biebricher, C. K. & Orgel, L. E. An RNA that multiplies indefinitely with DNA-dependent RNA polymerase: selection from a random copolymer. Proc. Natl Acad. Sci. USA 70, 934–938 (1973).
  Article CAS PubMed PubMed Central Google Scholar
• Biebricher, C. K., Eigen, M, & Gardiner, W. C. Kinetics of RNA replication: competition and selection among self-replicating RNA species. Biochemistry 24, 6550–6560 (1985).
  Article CAS PubMed Google Scholar
• Robertson, D. L. & Joyce, G. F. Selection in vitro of an RNA enzyme that specifically cleaves singlestranded DNA. Nature 344, 467–468 (1990).
  Article CAS PubMed Google Scholar
• Beaudry, A. A. & Joyce, G. F. Directed evolution of an RNA enzyme. Science 257, 635–641 (1992).
  Article CAS PubMed Google Scholar
• Tuerk, C. & Gold, L. Systematic evolution of ligands by exponential enrichment: RNA ligands to bacteriophage T4 DNA polymerase. Science 249, 505–510 (1990).
  Article CAS PubMed Google Scholar
• Ellington, A. D. & Szostak, J. W. In vitro selection of RNA molecules that bind specific ligands. Nature 346, 818–822 (1990).
  Article CAS PubMed Google Scholar
• Chen, X., Li, N. & Ellington, A. D. Ribozyme catalysis of metabolism in the RNA world. Chem. Biodivers. 4, 633–655 (2007).
  Article CAS PubMed Google Scholar
• Mandal, R. & Breaker, R. R. Gene regulation byriboswitches. Nature Rev. Mol. Cell. Biol. 5, 451–463 (2004).
  Article CAS Google Scholar
• Lincoln, T. A. & Joyce, G. F. Self-sustained replication of an RNA enzyme. Science 323, 1229–1232 (2009).
  Article CAS PubMed PubMed Central Google Scholar
• Johnston, W. K., Unrau, P. J., Lawrence, M. S., Glasner, M. E. & Bartel, D. P. RNA-catalyzed RNA polymerization: accurate and general RNA-templated primer extension. Science 292, 1319–1325 (2001). This study is the first laboratory demonstration of RNA-catalysed RNA polymerization on a template (that is, the first hint that an RNA replicase might be possible).
  Article CAS PubMed Google Scholar
• Zaher, H. S. & Unrau, P. J. Selection of an improved RNA polymerase ribozyme with superior extension and fidelity. RNA 13, 1017–1026 (2007).
  Article CAS PubMed PubMed Central Google Scholar
• Cheng, L. K. L. & Unrau, P. J. Closing the circle: replicating RNA with RNA. Cold Spring Harb. Perspect. Biol. 2, a002204 (2010).
  Article CAS PubMed PubMed Central Google Scholar
• Shapiro, R. Origins: A Skeptic's Guide to the Creation of Life on Earth (Bantam New Age, 1987).
  Google Scholar
• Shapiro, R. A simpler origin of life. Sci. Am. 296, 46–53 (2007).
  Article PubMed Google Scholar
• Neveu, M., Kim, H. J. & Benner, S. A. The “strong” RNA world hypothesis: fifty years old. Astrobiology 13, 391–403 (2013).
  Article PubMed Google Scholar
• Joyce, G. F., Schwartz, A. W., Miller, S. L. & Orgel, L. E. The case for an ancestral genetic system involving simple analogues of the nucleotides. Proc. Natl Acad. Sci. USA 84, 4398–4402 (1987).
  Article CAS PubMed PubMed Central Google Scholar
• Joyce, G. F. The rise and fall of the RNA world. New Biol. 3, 399–407 (1991). This often overlooked paper lists many of the pros and cons of the RNA World hypothesis before experimental data emerged in the 1990s.
  CAS PubMed Google Scholar
• Joyce, G. F. The antiquity of RNA-based evolution. Nature 418, 214–221 (2002).
  Article CAS PubMed Google Scholar
• Benner, S. A., Kim, H.J. & Carrigan, M. A. Asphalt, water, and the prebiotic synthesis of ribose, ribonucleotides, and RNA. Acc. Chem. Res. 45, 2025–2034 (2012). This paper outlines the discontinuous synthesis model of RNA synthesis, underscoring the fact that RNA need not, and probably was not, made all at once in a single environment.
  Article CAS PubMed Google Scholar
• Ricardo, A., Carrigan, M. A., Olcott, A. & Benner, S. A. Borate minerals stabilize ribose. Science 303, 196 (2004).
  Article CAS PubMed Google Scholar
• Vázquez-Mayagoitia, A. et al. On the stabilization of ribose by silicate minerals. Astrobiology 11, 115–121 (2011).
  Article CAS PubMed Google Scholar
• Anastasi, C. et al. RNA: prebiotic product, or biotic invention? Chem. Biodivers. 4, 721–739 (2007).
  Article CAS PubMed Google Scholar
• Powner, M. W., Gerland, B. & Sutherland, J. D. Synthesis of activated pyrimidine ribonucleotides in prebiotically plausible conditions. Nature 459, 239–242 (2009). This soon-to-be-classic paper shows how activated nucleotides can be made under abiotic conditions using the 'three-fer' of phosphate buffer.
  Article CAS PubMed Google Scholar
• Pasek, M. A., Harnmeijer, J. P., Buick, R., Gull, M. & Atlas, Z. Evidence for reactive reduced phosphorus species in the early Archaen ocean. Proc. Natl Acad. Sci. USA 110, 10089–10094 (2013).
  Article CAS PubMed PubMed Central Google Scholar
• Ritson, D. & Sutherland, J. D. Prebiotic synthesis of simple sugars by photoredox systems chemistry. Nature Chem. 4, 895–899 (2012).
  Article CAS Google Scholar
• Bowler, F. R. et al. Prebiotically plausible oligoribonucleotide ligation facilitated by chemoselective acetylation. Nature Chem. 5, 383–389 (2013).
  Article CAS Google Scholar
• Wächtershäuser, G. Before enzymes and templates: theory of surface metabolism. Microbiol. Rev. 52, 452–484 (1988).
  PubMed PubMed Central Google Scholar
• Orgel, L. E. Did template-directed nucleation precede molecular replication? Orig. Life Evol. Biosph. 17, 27–34 (1986).
  Article CAS PubMed Google Scholar
• Ferris, J. P. Mineral catalysis and prebiotic synthesis: montmorillonite-catalyzed formation of RNA. Elements 1, 145–149 (2005).
  Article CAS Google Scholar
• Monnard, P.-A., Kanavarioti, A. & Deamer, D. W. Eutectic phase polymerization of activated ribonucleotide mixtures yields quasi-equimolar incorporation of purine and pyrimidine nucleobases. J. Am. Chem. Soc. 125, 13734–13740 (2003).
  Article CAS PubMed Google Scholar
• Monnard, P.-A. & Szostak, J. W. Metal-ion catalyzed polymerization in the eutectic phase in water–ice: a possible approach to template-directed RNA polymerization. J. Inorg. Biochem. 102, 1104–1111 (2008).
  Article CAS PubMed Google Scholar
• Cafferty, B. J. et al. Efficient self-assembly in water of long noncovalent polymers by nucleobases analogs. J. Am. Chem. Soc. 135, 2447–2450 (2013). This paper reveals how there are far more RNA self-assembly mechanisms in an aqueous environment than previously appreciated.
  Article CAS PubMed Google Scholar
• Kuruvilla, E., Schuster, G. B. & Hud, N. V. Enhanced nonenzymatic ligation of homopurine miniduplexes: support for greater base stacking in a pre-RNA world. ChemBioChem 14, 45–48 (2013).
  Article CAS PubMed Google Scholar
• Hud, N. V., Cafferty, B. J., Krishnamurthy, R. & Williams, L. D. The origin of RNA and “my grandfather's axe”. Chem. Biol. 20, 466–474 (2013).
  Article CAS PubMed Google Scholar
• Wu, T. & Orgel, L. E. Nonenzymatic template-directed synthesis on oligodeoxycytidylate sequences in hairpin oligonucleotides. J. Am. Chem. Soc. 114, 317–322 (1992).
  Article CAS PubMed Google Scholar
• Hill, A. R. Jr., Wu, T. & Orgel, L. E. The limits of template-directed synthesis with nucleoside-5′-phosphoro(2-methyl)imidazolides. Origins Life Evol. Biosph. 23, 285–290 (1993).
  Article CAS Google Scholar
• Deck, C., Jauker, M. & Richert, C. Efficient enzyme-free copying of all four nucleobases templated by immobilized RNA. Nature Chem. 3, 603–608 (2011).
  Article CAS Google Scholar
• Lehman, N. & Hayden, E. J. Template-directed RNA polymerization: the taming of the milieu. ChemBioChem 12, 2727–2728 (2011).
  Article CAS PubMed Google Scholar
• Moulton, V. et al. RNA folding argues against a hot-start origin of life. J. Mol. Evol. 51, 416–421 (2000).
  Article CAS PubMed Google Scholar
• Vlassov, A. V., Johnston, B. H., Landweber, L. F. & Kazakov, S. A. Ligation activity of fragmented ribozymes in frozen solution: implications for the RNA world. Nucleic Acids Res. 25, 2966–2974 (2004).
  Article CAS Google Scholar
• Wochner, A., Attwater, J., Coulson, A. & Holliger, P. Ribozyme-catalyzed transcription of an active ribozyme. Science 332, 209–212 (2011).
  Article CAS PubMed Google Scholar
• Attwater, J., Wochner, A. & Holliger, P. In-ice evolution of RNA polymerase ribozyme activity. Nature Chem. 5, 1011–1018 (2013). This study demonstrated polymerization by an artificial RNA replicase beyond 200 nucleotides, which is the longest achieved so far.
  Article CAS Google Scholar
• Lehman, N. Cold-hearted RNA heats up life. Nature Chem. 5, 987–989 (2011).
  Article CAS Google Scholar
• Huang, W. & Ferris, J. P. One-step, regioselective synthesis of up to 50-mers of RNA oligomers by montmorillonite catalysis. J. Am. Chem. Soc. 128, 8914–8919 (2006).
  Article CAS PubMed Google Scholar
• Kauffman, S. A. The Origins of Order: Self-Organization and Selection in Evolution (Oxford Univ. Press, 1993).
  Google Scholar
• Hordijk, W. & Steel, M. Detecting autocatalytic, self-containing sets in chemical reaction systems. J. Theor. Biol. 227, 451–461 (2004).
  Article CAS PubMed Google Scholar
• Hordijk, W. & Steel, M. A formal model of autocatalytic sets emerging in a RNA replicator system. J. Syst. Chem. 4, 3 (2013).
  Article CAS Google Scholar
• Smith, J. I., Steel, M. & Hordijk, W. Autocatalytic sets in a partitioned chemical network. J. Syst. Chem. 5, 2 (2014).
  Article PubMed PubMed Central CAS Google Scholar
• Hayden, E. J. & Lehman, N. Self-assembly of a group I intron from inactive oligonucleotide fragments. Chem. Biol. 13, 909–918 (2006).
  Article CAS PubMed Google Scholar
• Hayden, E. J., von Kiedrowski, G. & Lehman, N. Systems chemistry on ribozyme self-construction: Evidence for anabolic autocatalysis in a recombination network. Angew. Chem. Int. Ed. 47, 8424–8428 (2008).
  Article CAS Google Scholar
• Burton, A. S. & Lehman, N. Enhancing the prebiotic relevance of a set of covalently self-assembling, autorecombining RNAs through in vitro selection. J. Mol. Evol. 70, 233–241 (2010).
  Article CAS PubMed Google Scholar
• Vaidya, N. et al. Spontaneous network formation among cooperative RNA replicators. Nature 491, 72–77 (2012).
  Article CAS PubMed Google Scholar
• Vaidya, N., Walker, S. I. & Lehman, N. Recycling of informational units leads to selection of replicators in a prebiotic soup. Chem. Biol. 20, 241–252 (2013).
  Article CAS PubMed Google Scholar
• Levy, M. & Ellington, A. D. The descent of polymerization. Nature Struct. Biol. 8, 580–582 (2001).
  Article CAS PubMed Google Scholar
• Maynard Smith, J. & Szathmary, E. The Major Transitions in Evolution (Oxford University Press,1995).
  Google Scholar
• Hammerstein, P. Genetic and Cultural Evolution of Cooperation (MIT Press, 2003).
  Book Google Scholar
• Nowak, M. A. Five rules for the evolution of cooperation. Science 314, 1560–1563 (2006). This paper outlines the various modes of cooperation that could be operative in biological scenarios, setting the stage for considering chemical cooperation mechanisms.
  Article CAS PubMed PubMed Central Google Scholar
• Boerlijst, M. C. & Hogeweg, P. Spiral wave structure in prebiotic evolution: hypercycles stable against parasites. Physica. D 48, 17–28 (1991).
  Article Google Scholar
• Sardanyes, J. & Solé, R. V. Bifurcations and phase transitions in spatially extended two-member hypercycles. J. Theor. Biol. 243, 468–482 (2006).
  Article CAS PubMed Google Scholar
• Sardanyes, J. & Solé, R. V. Spatiotemporal dynamics in simple asymmetric hypercycles under weak parasitic coupling. Physica. D 231, 116–129 (2007).
  Article Google Scholar
• McCaskill, J. S., Füchslin, R. M. & Altmeyer, S. The stochastic evolution of catalysts in spatially resolved molecular systems. Biol. Chem. 382, 1343–1363 (2001).
  Article CAS PubMed Google Scholar
• Konnyu, B., Czaran, T. & Szathmáry, E. Prebiotic replicase evolution in a surface-bound metabolic system: parasites as a source of adaptive evolution. BMC Evol. Biol. 8, 267 (2008).
  Article PubMed PubMed Central CAS Google Scholar
• Branciamore, S., Gallori, E., Szathmáry, E. & Czaran, T. The origin of life: chemical evolution of a metabolic system in a mineral honeycomb? J. Mol. Evol. 69, 485–469 (2009).
  Article CAS Google Scholar
• Brogioli, D. Marginally stable chemical systems as precursors for life. Phys. Rev. Lett. 105, 058102 (2010).
  Article CAS PubMed Google Scholar
• Szabo, P., Scheuring, I., Czaran, T. & Szathmáry, E. In silico simulations reveal that replicators with limited dispersal evolve towards higher efficiency and fidelity. Nature 420, 340–343 (2002).
  Article CAS PubMed Google Scholar
• Eigen, M. & Schuster, P. The hypercycle: a principle of natural self-organization. Part B: the abstract hypercycle. Naturwissenschaften 65, 7–41 (1978).
  Article Google Scholar
• Eigen, M., McCaskill, J. & Schuster, P. Molecular quasi-species. J. Phys. Chem. 92, 6881–6891 (1988).
  Article CAS Google Scholar
• Takeuchi, N. & Hogeweg, P. Evolutionary dynamics of RNA-like replicator systems: a bioinformatic approach to the origin of life. Phys. Life Rev. 9, 219–263 (2012). This paper brings together a wide range of theories and models of RNA evolution and clearly explains the issues from evolutionary theory.
  Article PubMed PubMed Central Google Scholar
• Takeuchi, N. & Hogeweg, P. The role of complex formation and deleterious mutations for the stability of RNA-like replicator systems. J. Mol. Evol. 65, 668–686 (2007).
  Article CAS PubMed Google Scholar
• Wu, M. & Higgs, P. G. The origin of life is a spatially localized stochastic transition. Biol. Direct 7, 42 (2012).
  Article CAS PubMed PubMed Central Google Scholar
• Higgs, P. G. & Wu, M. The importance of stochastic transitions for the origin of life. Orig. Life Evol. Biosph. 42, 453–457 (2012).
  Article CAS PubMed Google Scholar
• Takeuchi, N. & Hogeweg, P. Evolution of complexity in RNA-like replicator systems. Biol. Direct 3, 11 (2008).
  Article PubMed PubMed Central CAS Google Scholar
• Takeuchi, N. Salazar, L., Poole, A. M. & Hogeweg, P. The evolution of strand preference in simulated RNA replicators with strand displacement: implications for the origin of transcription. Biol. Direct. 3, 33 (2008).
  Article PubMed PubMed Central CAS Google Scholar
• Shay, J. A., Huynh, C. & Higgs, P. G. The origin and spread of a cooperative replicase in a prebiotic chemical system. J. Theor. Biol. http://dx.doi.org/10.1016/j.jtbi.2014.09.019 (2014).
• Szathmáry, E. & Demeter, L. Group selection of early replicators and the origin of life. J. Theor. Biol. 128, 463–483 (1987). This early classic paper sparked considerations of how spatial aggregation might have been important in the RNA World, and it led to the concepts of molecular cooperation outlined here.
  Article PubMed Google Scholar
• Szathmáry, E., Sandos, M. & Fernando, C. Evolutionary potential and requirements for minimal protocells. Top. Curr. Chem. 259, 167–211 (2005).
  Article CAS Google Scholar
• Takeuchi, N. & Hogeweg, P. Multilevel selection in models of prebiotic evolution II: a direct comparison of compartmentalization and spatial self-organization. PLoS Comput. Biol. 5, e1000542 (2009).
  Article PubMed PubMed Central CAS Google Scholar
• Konnyu, B. & Czaran, T. The evolution of enzyme specificity in the metabolic replicator model of prebiotic evolution. PLoS ONE 6, e20931 (2011).
  Article CAS PubMed PubMed Central Google Scholar
• Doudna, J. A., Couture, S. & Szostak, J. W. A multi-subunit ribozyme that is a catalyst of and template for complemtary strand RNA synthesis. Science 251, 1605–1608 (1991).
  Article CAS PubMed Google Scholar
• Ferris, J. P. Montmorillonite catalysis of 30–50 mer oligonucleotides: laboratory demonstration of potential steps in the origin of the RNA world. Orig. Life Evol. Biosph. 32, 311–332 (2002).
  Article CAS PubMed Google Scholar
• Lawless, J. G. & Yuen, G. U. Quantification of monocarboxylic acids in the Murchison carbonaceous meteorite. Nature 282, 396–398 (1979).
  Article CAS Google Scholar
• Deamer, D. W. The first living systems: a bioenergetics perspective. Microbiol. Mol. Biol. Rev. 61, 239–261 (1997).
  CAS PubMed PubMed Central Google Scholar
• Szostak, J. W., Bartel, D. P. & Luisi, P. L. Synthesizing life. Nature 409, 387–390 (2001).
  Article CAS PubMed Google Scholar
• Solé, R. V., Munteanu, A., Rodriguez-Caso, C. & Macía, J. Synthetic protocell biology: from reproduction to computation. Phil. Trans. Roy. Soc. B. 362, 1727–1739 (2007).
  Article CAS Google Scholar
• Chen, I. A, Roberts R. W, & Szostak J. W. The emergence of competition between model protocells. Science 305, 1474–1476 (2004). This paper nicely shows how chemical conflicts can be solved, or exacerbated, in cell-like structures.
  Article CAS PubMed PubMed Central Google Scholar
• Adamala, K. & Szostak, J. W. Competition between model protocells driven by an encapsulated catalyst. Nature Chem. 5, 495–501 (2013).
  Article CAS Google Scholar
• Strulson, C. A., Molden, R. C., Keating, C. D. & Bevilacqua, P. C. RNA catalysis through compartmentalization. Nature Chem. 4, 941–946 (2012).
  Article CAS Google Scholar
• Adamala, K. & Szostak, J. W. Nonenzymatic template-directed RNA synthesis inside model protocells. Science 342, 1098–1100 (2013).
  Article CAS PubMed PubMed Central Google Scholar
• Bansho, Y. et al. Importance of parasite RNA species repression for prolonged translation-coupled RNA self-replication. Chem. Biol. 19, 478–487 (2012).
  Article CAS PubMed Google Scholar
• Lehman, N. Evolution finds shelter in small spaces. Chem. Biol. 19, 439–440 (2012).
  Article CAS PubMed Google Scholar
• Ichihashi, N. et al. Darwinian evolution in a translation-coupled RNA replication system within a cell-like compartment. Nature Commun. 4, 2494 (2013).
  Article CAS Google Scholar
• von Kiedrowski, G., Otto, S. & Herdewijn, P. Welcome home, systems chemists! J. Syst. Chem. 1, 1 (2010).
  Article Google Scholar
• Eschenmoser, A. Chemical etiology of nucleic acid structure. Science 284, 2118–2124 (1999).
  Article CAS PubMed Google Scholar
• Malyshev, D. A. et al. Solution structure, mechanism of replication, and optimization of an unnatural base pair. Chem. Eur. J. 16, 12650–12659 (2010).
  Article CAS PubMed Google Scholar
• Yang, Z., Chen, F., Alvarado, J. B. & Benner, S. A. Amplification, mutation, and sequencing of a six-letter synthetic genetic system. J. Am. Chem. Soc. 133, 15105–15112 (2011).
  Article CAS PubMed PubMed Central Google Scholar
• Kim, E.-K. & Switzer, C. Polymerase recognition of a Watson–Crick-like metal-mediated base pair: purine-2,6-dicarboxylate·copper(II)·pyridine. ChemBioChem 14, 2403–2407 (2013).
  Article CAS PubMed Google Scholar
• Ebert, M. O., Mang, C., Krishnamurthy, R., Eschenmoser, A. & Jaun, B. The structure of a TNA–TNA complex in solution: NMR study of the octamer duplex derived from α-(l-threofuranosyl-)3′-2′-CGAATTCG. J. Am. Chem. Soc. 130, 15105–15115 (2008).
  Article PubMed Google Scholar
• Yang, Y.-W., Zhang, S., McCullum, E. O. & Chaput, J. C. Experimental evidence that GNA and TNA were not sequential polymers in the prebiotic evolution of RNA. J. Mol. Evol. 65, 289–295 (2007).
  Article CAS PubMed Google Scholar
• Yu, H., Zhang, S. & Chaput, J. C. Darwinian evolution of an alternative genetic system provides support for TNA as an RNA progenitor. Nature Chem. 10, 183–187 (2012).
  Article CAS Google Scholar
• Pinheiro, V. B. et al. Synthetic genetic polymers capable of heredy and evolution. Science 336, 341–344 (2012).
  Article CAS PubMed PubMed Central Google Scholar
• Schlosser, K. & Li, Y. Biologically inspired synthetic enzymes made from. DNA. Chem. Biol. 16, 315–322 (2009).
  Google Scholar
• Silverman, S. K. DNA as a versatile chemical component for catalysis, encoding, and stereocontrol. Angew. Chem. Int. Ed. 49, 7180–7201 (2010).
  Article CAS Google Scholar
• Lazcano, A., Guerrero, R., Margulis, L. & Oro, J. The evolutionary transition from RNA to DNA in early cells. J. Mol. Evol. 27, 283–290 (1988).
  Article CAS PubMed Google Scholar
• Burton, A. S. & Lehman, N. DNA before proteins? Recent discoveries in nucleic acid catalysis strengthen the case. Astrobiology. 9, 125–130 (2009).
  Article CAS PubMed Google Scholar
• Ohtsuki, H. & Nowak, M. A. Prelife catalysts and replicators. Proc. Roy. Soc. B 276, 3783–3790 (2009).
  Article Google Scholar
• Manapat, M. L., Chen, I. A. & Nowak, M. A. The basic reproductive ratio of life. J. Theor. Biol. 263, 317–327 (2010).
  Article PubMed Google Scholar
• Chen, I. A. & Nowak. M. A. From prelife to life: how chemical kinetics become evolutionary dynamics. Acc. Chem. Res. 45, 2088–2096 (2012).
  Article CAS PubMed PubMed Central Google Scholar
• Wu, M. & Higgs, P. G. Origin of self-replicating biopolymers: autocatalytic feedback can jump-start the RNA world. J. Mol. Evol. 69, 541–554 (2009).
  Article CAS PubMed Google Scholar
• Wu, M. & Higgs, P. Comparison of the roles of momoner synthesis, polymerization, and recombination in the origin of autocatalytic sets of biopolymers. Astrobiology 11, 895–906 (2011).
  Article CAS PubMed Google Scholar
• Ma, W., Yu, C., Zhang, W. & Hu, J. A simple template-dependent ligase ribozyme as the RNA replicase emerging first in the RNA World. Astrobiology 10, 437–447 (2010).
  Article CAS PubMed Google Scholar
• Ma, W., Yu, C., Zhang, W. & Hu, J. Nucleotide synthetase ribozymes may have emerged first in the RNA World. RNA 13, 2012–2019 (2007).
  Article CAS PubMed PubMed Central Google Scholar
• Ma, W., Yu, C. & Zhang, W. Monte Carlo simulation of early molecular evolution in the RNA World. Biosystems 90, 28–39 (2007).
  Article CAS PubMed Google Scholar