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Origins of Life and Evolution of the Biosphere

Israel Muñoz-Velasco, Carlos García-Ferris, Ricardo Hernandez-Morales, Antonio Lazcano, Juli Peretó, Arturo Becerra
Of the six known autotrophic pathways, the Wood-Ljungdahl pathway (WL) is the only one present in both the acetate producing Bacteria (homoacetogens) and the methane producing Archaea (hydrogenotrophic methanogens), and it has been suggested that WL is one of the oldest metabolic pathways. However, only the so-called carbonyl branch is shared by Archaea and Bacteria, while the methyl branch is different, both in the number of reactions and enzymes, which are not homologous among them. In this work we show that some parts of the methyl branch of archaeal Wood-Ljungdahl pathway (MBWL) are present in bacteria as well as in non-methanogen archaea, although the tangled evolutionary history of MBWL cannot be traced back to the Last Common Ancestor...
January 5, 2019: Origins of Life and Evolution of the Biosphere
Peter R Bahn
No abstract text is available yet for this article.
January 5, 2019: Origins of Life and Evolution of the Biosphere
Hannes Lukas Pleyer, Henry Strasdeit, Stefan Fox
In previous experiments that simulated conditions on primordial volcanic islands, we demonstrated the abiotic formation of hydrophobic porphyrins. The present study focused on the question whether such porphyrins can be metalated by prebiotically plausible metal ion sources. We used water-insoluble octaethylporphyrin (H2 oep) as a model compound. Experiments were conducted in a nitrogen atmosphere under cyclic wet-dry conditions in order to simulate the fluctuating environment in prebiotic rock pools. Wetting-drying proved to be a crucial factor...
December 13, 2018: Origins of Life and Evolution of the Biosphere
Alan W Schwartz
Plans for the publication of Abstracts from the meeting have been cancelled. However, manuscripts for full papers will still be considered for publication in OLEB.
September 12, 2018: Origins of Life and Evolution of the Biosphere
Alan W Schwartz
No abstract text is available yet for this article.
September 2018: Origins of Life and Evolution of the Biosphere
Peter R Bahn
No abstract text is available yet for this article.
September 2018: Origins of Life and Evolution of the Biosphere
Izabela Sibilska, Yu Feng, Lingjun Li, John Yin
The biochemical activation of amino acids by adenosine triphosphate (ATP) drives the synthesis of proteins that are essential for all life. On the early Earth, before the emergence of cellular life, the chemical condensation of amino acids to form prebiotic peptides or proteins may have been activated by inorganic polyphosphates, such as tri metaphosphate (TP). Plausible volcanic and other potential sources of TP are known, and TP readily activates amino acids for peptide synthesis. But de novo peptide synthesis also depends on pH, temperature, and processes of solvent drying, which together define a varied range of potential activating conditions...
September 2018: Origins of Life and Evolution of the Biosphere
Hope L Juntunen, Lucas J Leinen, Briann K Pitts, Samantha M O'Hanlon, Bethany P Theiling, Laura M Barge, Patrick Videau, Michael O Gaylor
Carbonaceous meteorites contributed polycyclic aromatic hydrocarbons (PAHs) to the organic inventory of the primordial Earth where they may have reacted on catalytic clay mineral surfaces to produce quinones capable of functioning as redox species in emergent biomolecular systems. To address the feasibility of this hypothesis, we assessed the kinetics of anthracene (1) conversion to 9,10-anthraquinone (2) in the presence of montmorillonite clay (MONT) over the temperature range 25 to 250 °C. Apparent rates of conversion were concentration independent and displayed a sigmoidal relationship with temperature, and conversion efficiencies ranged from 0...
September 2018: Origins of Life and Evolution of the Biosphere
Zewei Li, Runhe Lyu, John Tower
Several models for the origin of life involve molecules that are capable of self-replication, such as self-replicating polymers composed of RNA or DNA or amino acids. Here we consider a hypothetical replicator (AB) composed of two subunits, A and B. Programs written in Python and C programming languages were used to model AB replicator abundance as a function of cycles of replication (iterations), under specified hypothetical conditions. Two non-exclusive models describe how a reduced stability for B relative to A can have an advantage for replicator activity and/or evolution by generating free A subunits...
September 2018: Origins of Life and Evolution of the Biosphere
Marie-Paule Bassez
An alternative hypothesis for the origin of the banded iron formations and the synthesis of prebiotic molecules is presented here. I show the importance of considering water near its supercritical point and at alkaline pH. It is based on the chemical equation for the anoxic oxidation of ferrous iron into ferric iron at high-subcritical conditions of water and high pH, that I extract from E-pH diagrams drawn for corrosion purposes (Geophysical Research Abstracts Vol 15, EGU2013-22 Bassez 2013, Orig Life Evol Biosph 45(1):5-13, Bassez 2015, Procedia Earth Planet Sci 17, 492-495, Bassez 2017a, Orig Life Evol Biosph 47:453-480, Bassez 2017b)...
September 2018: Origins of Life and Evolution of the Biosphere
Alejandro Frank, Tom Froese
It is widely agreed that the standard genetic code must have been preceded by a simpler code that encoded fewer amino acids. How this simpler code could have expanded into the standard genetic code is not well understood because most changes to the code are costly. Taking inspiration from the recently synthesized six-letter code, we propose a novel hypothesis: the initial genetic code consisted of only two letters, G and C, and then expanded the number of available codons via the introduction of an additional pair of letters, A and U...
June 2018: Origins of Life and Evolution of the Biosphere
Jay G Forsythe, Sloane L English, Rachel E Simoneaux, Arthur L Weber
A one-pot method was developed for the preparation of a series of β-alanine standards of moderate size (2 to ≥12 residues) for studies concerning the prebiotic origins of peptides. The one-pot synthesis involved two sequential reactions: (1) dry-down self-condensation of β-alanine methyl ester, yielding β-alanine peptide methyl ester oligomers, and (2) subsequent hydrolysis of β-alanine peptide methyl ester oligomers, producing a series of β-alanine peptide standards. These standards were then spiked into a model prebiotic product mixture to confirm by HPLC the formation of β-alanine peptides under plausible reaction conditions...
June 2018: Origins of Life and Evolution of the Biosphere
Marko Vitas, Andrej Dobovišek
The origin of translation is critical for understanding the evolution of life, including the origins of life. The canonical genetic code is one of the most dominant aspects of life on this planet, while the origin of heredity is one of the key evolutionary transitions in living world. Why the translation apparatus evolved is one of the enduring mysteries of molecular biology. Assuming the hypothesis, that during the emergence of life evolution had to first involve autocatalytic systems which only subsequently acquired the capacity of genetic heredity, we propose and discuss possible mechanisms, basic aspects of the emergence and subsequent molecular evolution of translation and ribosomes, as well as enzymes as we know them today...
June 2018: Origins of Life and Evolution of the Biosphere
Wanyun Shu, Yongfei Yu, Su Chen, Xia Yan, Yan Liu, Yufen Zhao
The Ser-His dipeptide is the shortest active peptide. This dipeptide not only hydrolyzes proteins and DNA but also catalyzes the formation of peptides and phosphodiester bonds. As a potential candidate for the prototype of modern hydrolase, Ser-His has attracted increasing attention. To explore if Ser-His could be obtained efficiently in the prebiotic condition, we investigated the reactions of N-DIPP-Ser with His or other amino acids in an aqueous system. We observed that N-DIPP-Ser incubated with His can form Ser-His more efficiently than with other amino acids...
June 2018: Origins of Life and Evolution of the Biosphere
Alexandra Whicher, Eloi Camprubi, Silvana Pinna, Barry Herschy, Nick Lane
Metabolism is primed through the formation of thioesters via acetyl CoA and the phosphorylation of substrates by ATP. Prebiotic equivalents such as methyl thioacetate and acetyl phosphate have been proposed to catalyse analogous reactions at the origin of life, but their propensity to hydrolyse challenges this view. Here we show that acetyl phosphate (AcP) can be synthesised in water within minutes from thioacetate (but not methyl thioacetate) under ambient conditions. AcP is stable over hours, depending on temperature, pH and cation content, giving it an ideal poise between stability and reactivity...
June 2018: Origins of Life and Evolution of the Biosphere
Saúl A Villafañe-Barajas, João Paulo T Baú, María Colín-García, Alicia Negrón-Mendoza, Alejandro Heredia-Barbero, Teresa Pi-Puig, Dimas A M Zaia
Any proposed model of Earth's primitive environments requires a combination of geochemical variables. Many experiments are prepared in aqueous solutions and in the presence of minerals. However, most sorption experiments are performed in distilled water, and just a few in seawater analogues, mostly inconsistent with a representative primitive ocean model. Therefore, it is necessary to perform experiments that consider the composition and concentration of dissolved salts in the early ocean to understand how these variables could have affected the absorption of organic molecules into minerals...
June 2018: Origins of Life and Evolution of the Biosphere
Miryam Palacios-Pérez, Fernando Andrade-Díaz, Marco V José
Herein we outline a plausible proteome, encoded by assuming a primeval RNY genetic code. We unveil the primeval phenotype by using only the RNA genotype; it means that we recovered the most ancestral proteome, mostly made of the 8 amino acids encoded by RNY triplets. By looking at those fragments, it is noticeable that they are positioned, not at catalytic sites, but in the cofactor binding sites. It implies that the stabilization of a molecule appeared long before its catalytic activity, and therefore the Ur-proteome comprised a set of proteins modules that corresponded to Cofactor Stabilizing Binding Sites (CSBSs), which we call the primitive bindome...
June 2018: Origins of Life and Evolution of the Biosphere
Konstantin K Konstantinov, Alisa F Konstantinova
Chiral symmetry breaking in complex chemical systems with a large number of amino acids and a large number of similar reactions was considered. It was shown that effective averaging over similar reaction channels may result in very weak effective enantioselectivity of forward reactions, which does not allow most of the known models to result in chiral symmetry breaking during formation of life on Earth. Models with simple and catalytic synthesis of a single amino acid, formation of peptides up to length five, and sedimentation of insoluble pair of substances were considered...
March 2018: Origins of Life and Evolution of the Biosphere
Gabriel S Zamudio, Marco V José
In this work, we explicitly consider the evolution of the Standard Genetic Code (SGC) by assuming two evolutionary stages, to wit, the primeval RNY code and two intermediate codes in between. We used network theory and graph theory to measure the connectivity of each phenotypic graph. The connectivity values are compared to the values of the codes under different randomization scenarios. An error-correcting optimal code is one in which the algebraic connectivity is minimized. We show that the SGC is optimal in regard to its robustness and error-tolerance when compared to all random codes under different assumptions...
March 2018: Origins of Life and Evolution of the Biosphere
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