Evidence for biogenic graphite in early Archaean Isua metasedimentary rocks

Ohtomo, Yukiko; Kakegawa, Takeshi; Ishida, Akizumi; Nagase, Toshiro; Rosing, Minik T.

doi:10.1038/ngeo2025

Cited by 154 publications

(92 citation statements)

References 23 publications

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“…3 Now, as it is well known from heterogeneous catalysis, 4 molecular adsorption is the fundamental step towards obtaining desired products from appropriate reactants. In general, the adsorption mechanism is primarily dominated by van der Waals (vdW) interactions between an adsorbed molecule and the surface atoms, which induce small changes in the electronic structure of the adsorbate.…”

Section: Introductionmentioning

confidence: 99%

Energy Barrier Reduction for the Double Proton-Transfer Reaction in Guanine–Cytosine DNA Base Pair on a Gold Surface

et al. 2015

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ABSTRACT. We investigate, by means of first-principles calculations, the impact of a gold surface on the proton-transfer of the guanine-cytosine (GC) DNA base pair. Our calculations employ density functional improvements to correct van der Waals interactions and properly treat a weakly bound GC pair at an Au(111) surface. We adopted the simultaneous double proton-transfer (SDPT) mechanism proposed by Löwdin, which may lead to a spontaneous mutation in the structure of DNA from specific tautomerization involving the base pairs. Our calculated differences in the energetics and kinetics of the SDPT in the GC pair, when in contact with an inert gold surface, indicate a reduction of about 31% in the activation energy barrier of the GC/Au(111) tautomeric equilibrium. This finding gives strong evidence that tautomerism of DNA base pairs, binding to a noble surface, may be indeed relevant for the assessment of a possible point mutation, which could be induced by the presence of gold nanoparticles during DNA replication.

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Section: Introductionmentioning

confidence: 99%

Energy Barrier Reduction for the Double Proton-Transfer Reaction in Guanine–Cytosine DNA Base Pair on a Gold Surface

et al. 2015

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“…High plasma membrane order is a fundamental property shared across the domains of modern life, and it may have been a key factor in the selective fitness of primitive life (2). However, sterols as the primary membraneordering lipid present a conundrum because sterol biosynthesis requires molecular oxygen, but life was present on Earth at least a billion years before cyanobacteria first enriched the atmosphere with oxygen (3,4). Are there lipids that could have promoted membrane ordering before sterol synthesis emerged?…”

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confidence: 99%

Hopanoids as functional analogues of cholesterol in bacterial membranes

Sáenz

Grosser

Bradley

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

207

177

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The functionality of cellular membranes relies on the molecular order imparted by lipids. In eukaryotes, sterols such as cholesterol modulate membrane order, yet they are not typically found in prokaryotes. The structurally similar bacterial hopanoids exhibit similar ordering properties as sterols in vitro, but their exact physiological role in living bacteria is relatively uncharted. We present evidence that hopanoids interact with glycolipids in bacterial outer membranes to form a highly ordered bilayer in a manner analogous to the interaction of sterols with sphingolipids in eukaryotic plasma membranes. Furthermore, multidrug transport is impaired in a hopanoid-deficient mutant of the gram-negative Methylobacterium extorquens, which introduces a link between membrane order and an energy-dependent, membrane-associated function in prokaryotes. Thus, we reveal a convergence in the architecture of bacterial and eukaryotic membranes and implicate the biosynthetic pathways of hopanoids and other order-modulating lipids as potential targets to fight pathogenic multidrug resistance.

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“…RNA molecules are made up of sequences of 4 different nucleotides, the latter of which can be formed through reaction of a nucleobase with a ribose and a reduced phosphorous (P) source [2,3]. The evidence suggests that first life appeared earlier than 3.7 Gyr ago (Ga) [4,5] and thus the RNA world would have developed on a violent early Earth undergoing meteoritic bombardment at a rate of ∼1-1000 ×10 12 kg/yr [6], which is approximately 8-11 orders of magnitude greater than today [7]. At this time, the atmosphere was dominated by volcanic gases, and dry land was scarce as continents were rising out of the global ocean.…”

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confidence: 99%

Origin of the RNA world: The fate of nucleobases in warm little ponds

Pearce

Pudritz

Semenov

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

170

222

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Prior to the origin of simple cellular life, the building blocks of RNA (nucleotides) had to form and polymerize in favourable environments on the early Earth. At this time, meteorites and interplanetary dust particles delivered organics such as nucleobases (the characteristic molecules of nucleotides) to warm little ponds whose wet-dry cycles promoted rapid polymerization. We build a comprehensive numerical model for the evolution of nucleobases in warm little ponds leading to the emergence of the first nucleotides and RNA. We couple Earth's early evolution with complex prebiotic chemistry in these environments. We find that RNA polymers must have emerged very quickly after the deposition of meteorites (< a few years). Their constituent nucleobases were primarily meteoritic in origin and not from interplanetary dust particles. Ponds appeared as continents rose out of the early global ocean but this increasing availability of "targets" for meteorites was offset by declining meteorite bombardment rates. Moreover, the rapid losses of nucleobases to pond seepage during wet periods, and to UV photodissociation during dry periods means that the synthesis of nucleotides and their polymerization into RNA occurred in just one to a few wet-dry cycles. Under these conditions, RNA polymers likely appeared prior to 4.17 billion years ago.Significance: There are currently two competing hypotheses for the site at which an RNA world emerged: hydrothermal vents in the deep ocean and warm little ponds. Because the former lacks wet and dry cycles, which are well known to promote polymerization (in this case, of nucleotides into RNA), we construct a comprehensive model for the origin of RNA in the latter sites. Our model advances the story and timeline of the RNA world by constraining the source of biomolecules, the environmental conditions, the timescales of reaction, and the emergence of first RNA polymers.Keywords: life origins | astrobiology | planetary science | meteoritics | RNA worldOne of the most fundamental questions in science is how life first emerged on the Earth. Given its ubiquity in living cells and its ability to both store genetic information and catalyze its own replication, RNA probably formed the basis of first life [1]. RNA molecules are made up of sequences of 4 different nucleotides, the latter of which can be formed through reaction of a nucleobase with a ribose and a reduced phosphorous (P) source [2,3]. The evidence suggests that first life appeared earlier than 3.7 Gyr ago (Ga) [4,5] and thus the RNA world would have developed on a violent early Earth undergoing meteoritic bombardment at a rate of ∼1-1000 ×10 12 kg/yr [6], which is approximately 8-11 orders of magnitude greater than today [7]. At this time, the atmosphere was dominated by volcanic gases, and dry land was scarce as continents were rising out of the global ocean. [8,9], the answer to these questions are largely unknown.As to the sources of nucleobases, the early Earth's atmosphere was likely dominated by CO 2 , N 2 , SO 2 , and H 2 O [10...

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Evidence for biogenic graphite in early Archaean Isua metasedimentary rocks

Cited by 154 publications

References 23 publications

Energy Barrier Reduction for the Double Proton-Transfer Reaction in Guanine–Cytosine DNA Base Pair on a Gold Surface

Energy Barrier Reduction for the Double Proton-Transfer Reaction in Guanine–Cytosine DNA Base Pair on a Gold Surface

Hopanoids as functional analogues of cholesterol in bacterial membranes

Origin of the RNA world: The fate of nucleobases in warm little ponds

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