Papers by Michael Russell
European Journal of Mineralogy, 1992
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Earth-Science Reviews, 1985
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Electrochemical Science Advances, 2022
The second law of thermodynamics leaves no doubt that life on planet Earth and its inherent subst... more The second law of thermodynamics leaves no doubt that life on planet Earth and its inherent substantial decrease in entropy is fundamentally based on mechanisms converting environmental free energy into the spatial and temporal order of metabolic processes. This argument holds for present life as much as it does for its very beginnings some 4 billion years ago. In this contribution, we try to strip down free energy conversion in extant life (known as “bioenergetics” to the biologists) to its basic principles with the aim to potentially retrodict the nature of the pre‐biotic precursor which drove life into existence. We demonstrate that these basic principles are deeply rooted in aqueous electrochemistry and strongly rely on inorganic redox compounds. The question of life's emergence, generally considered to fall into the realm of organic chemistry, should therefore rather be recognized as an electrochemical problem and its ultimate elucidation will need to strongly implicate the...
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Space Science Reviews, 2019
The aim of this article is to provide the reader with an overview of the different possible scena... more The aim of this article is to provide the reader with an overview of the different possible scenarios for the emergence of life, to critically assess them and, according to the conclusions we reach, to analyze whether similar processes could have been conducive to independent origins of life on the several icy moons of the Solar System. Instead of directly proposing a concrete and unequivocal cradle of life on Earth, we focus on describing the different requirements that are arguably needed for the transition between non-life to life. We approach this topic from geological, biological, and chemical perspectives with the aim of providing answers in an integrative manner. We reflect upon the most prominent origins hypotheses and assess whether they match the aforementioned abiogenic requirements. Based on the conclusions extracted, we address whether the conditions for abiogenesis are/were met in any of the oceanic icy moons.
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Philosophical Transactions of the Royal Society B: Biological Sciences, 2007
A model for the origin of biochemistry at an alkaline hydrothermal vent has been developed that f... more A model for the origin of biochemistry at an alkaline hydrothermal vent has been developed that focuses on the acetyl-CoA (Wood–Ljungdahl) pathway of CO2fixation and central intermediary metabolism leading to the synthesis of the constituents of purines and pyrimidines. The idea that acetogenesis and methanogenesis were the ancestral forms of energy metabolism among the first free-living eubacteria and archaebacteria, respectively, stands in the foreground. The synthesis of formyl pterins, which are essential intermediates of the Wood–Ljungdahl pathway and purine biosynthesis, is found to confront early metabolic systems with steep bioenergetic demands that would appear to link some, but not all, steps of CO2reduction to geochemical processes in or on the Earth's crust. Inorganically catalysed prebiotic analogues of the core biochemical reactions involved in pterin-dependent methyl synthesis of the modern acetyl-CoA pathway are considered. The following compounds appear as proba...
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Bulletin of the AAS, 2021
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Science Advances, 2021
Oldest microfossils with methane-based metabolism in a subsurface environment expand the frontier... more Oldest microfossils with methane-based metabolism in a subsurface environment expand the frontiers of early Earth habitability.
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Nature Astronomy, 2019
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Astrobiology, Jan 19, 2018
Recent measurements of methane (CH) by the Mars Science Laboratory (MSL) now confront us with rob... more Recent measurements of methane (CH) by the Mars Science Laboratory (MSL) now confront us with robust data that demand interpretation. Thus far, the MSL data have revealed a baseline level of CH (∼0.4 parts per billion by volume [ppbv]), with seasonal variations, as well as greatly enhanced spikes of CH with peak abundances of ∼7 ppbv. What do these CH revelations with drastically different abundances and temporal signatures represent in terms of interior geochemical processes, or is martian CH a biosignature? Discerning how CH generation occurs on Mars may shed light on the potential habitability of Mars. There is no evidence of life on the surface of Mars today, but microbes might reside beneath the surface. In this case, the carbon flux represented by CH would serve as a link between a putative subterranean biosphere on Mars and what we can measure above the surface. Alternatively, CH records modern geochemical activity. Here we ask the fundamental question: how active is Mars, ge...
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Life, 2020
Life cannot emerge on a planet or moon without the appropriate electrochemical disequilibria and ... more Life cannot emerge on a planet or moon without the appropriate electrochemical disequilibria and the minerals that mediate energy-dissipative processes. Here, it is argued that four minerals, olivine ([Mg>Fe]2SiO4), bridgmanite ([Mg,Fe]SiO3), serpentine ([Mg,Fe,]2-3Si2O5[OH)]4), and pyrrhotite (Fe(1−x)S), are an essential requirement in planetary bodies to produce such disequilibria and, thereby, life. Yet only two minerals, fougerite ([Fe2+6xFe3+6(x−1)O12H2(7−3x)]2+·[(CO2−)·3H2O]2−) and mackinawite (Fe[Ni]S), are vital—comprising precipitate membranes—as initial “free energy” conductors and converters of such disequilibria, i.e., as the initiators of a CO2-reducing metabolism. The fact that wet and rocky bodies in the solar system much smaller than Earth or Venus do not reach the internal pressure (≥23 GPa) requirements in their mantles sufficient for producing bridgmanite and, therefore, are too reduced to stabilize and emit CO2—the staple of life—may explain the apparent absen...
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Tectonophysics, 1983
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Scottish Journal of Geology, 1995
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Nature, 1988
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Economic Geology, 2000
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Metals, Microbes, and Minerals - The Biogeochemical Side of Life, 2021
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Planetary water-rock interfaces generate free energy in the form of redox, pH, and thermal gradie... more Planetary water-rock interfaces generate free energy in the form of redox, pH, and thermal gradients. These disequilibria are particularly focused in hydrothermal systems where reducing, heated vent fluid feeds back into the more oxidizing ocean. The sediments and chimneys precipitated in alkaline hydrothermal vents on the early Earth would have contained reactive iron minerals such as iron (-nickel) sulfides and iron oxyhydroxides (including green rust). These minerals could have promoted carbon fixation and amino acid synthesis, as well as further organic synthesis, and concentrated the products, along with phosphate species, through adand ab-sorption. We have developed methods for investigating the effects of geochemical gradients on important prebiotic reactions in these systems, including the formation of simulated hydrothermal precipitates in a gradient (mimicking the electronic / protonic gradients that would be generated across hydrothermal chimney walls) [1]. We have also b...
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Applied Clay Science, 2020
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Interface Focus, 2019
In the 1930s, Lars Onsager published his famous ‘reciprocal relations’ describing free energy con... more In the 1930s, Lars Onsager published his famous ‘reciprocal relations’ describing free energy conversion processes. Importantly, these relations were derived on the assumption that the fluxes of the processes involved in the conversion were proportional to the forces (free energy gradients) driving them. For chemical reactions, however, this condition holds only for systems operating close to equilibrium—indeed very close; nominally requiring driving forces to be smaller than k B T . Fairly soon thereafter, however, it was quite inexplicably observed that in at least some biological conversions both the reciprocal relations and linear flux–force dependency appeared to be obeyed no matter how far from equilibrium the system was being driven. No successful explanation of how this ‘paradoxical’ behaviour could occur has emerged and it has remained a mystery. We here argue, however, that this anomalous behaviour is simply a gift of water, of its viscosity in particular; a gift, moreover...
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Papers by Michael Russell