Cellular remains in a ~3.42-billion-year-old subseafloor hydrothermal environment

Cavalazzi, Barbara; Lemelle, Laurence; Simionovici, Alexandre; Cady, Sherry L.; Russell, Michael J.; Bailo, Elena; Canteri, R.; Enrico, Emanuele; Manceau, Alain; Maris, Assimo; Salomé, Murielle; Thomassot, Émilie; Bouden, Nordine; Tucoulou, R.; Hofmann, Axel

doi:10.1126/sciadv.abf3963

Cited by 44 publications

(31 citation statements)

References 87 publications

(112 reference statements)

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“…In this study, we investigated the photostability likelihood of CA using DFT and its time-dependent variant (TD-DFT). The earliest time that life forms first appeared on Earth was around 4 billion years ago [15][16][17] and a recent study estimated the pH to be 6.6 [18] around that time. Therefore, we focus solely on the tri-keto tautomer of CA in this investigation because the pK a of CA is 6.9 [9].…”

Section: Introductionmentioning

confidence: 99%

On the Photostability of Cyanuric Acid and Its Candidature as a Prebiotic Nucleobase

2022

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Cyanuric acid is a triazine derivative that has been identified from reactions performed under prebiotic conditions and has been proposed as a prospective precursor of ancestral RNA. For cyanuric acid to have played a key role during the prebiotic era, it would have needed to survive the harsh electromagnetic radiation conditions reaching the Earth’s surface during prebiotic times (≥200 nm). Therefore, the photostability of cyanuric acid would have been crucial for its accumulation during the prebiotic era. To evaluate the putative photostability of cyanuric acid in water, in this contribution, we employed density functional theory (DFT) and its time-dependent variant (TD-DFT) including implicit and explicit solvent effects. The calculations predict that cyanuric acid has an absorption maximum at ca. 160 nm (7.73 eV), with the lowest-energy absorption band extending to ca. 200 nm in an aqueous solution and exhibiting negligible absorption at longer wavelengths. Excitation of cyanuric acid at 160 nm or longer wavelengths leads to the population of S5,6 singlet states, which have ππ* character and large oscillator strengths (0.8). The population reaching the S5,6 states is expected to internally convert to the S1,2 states in an ultrafast time scale. The S1,2 states, which have nπ* character, are predicted to access a conical intersection with the ground state in a nearly barrierless fashion (ca. ≤ 0.13 eV), thus efficiently returning the population to the ground state. Furthermore, based on calculated spin–orbit coupling elements of ca. 6 to 8 cm−1, the calculations predict that intersystem crossing to the triplet manifold should play a minor role in the electronic relaxation of cyanuric acid. We have also calculated the vertical ionization energy of cyanuric acid at 8.2 eV, which predicts that direct one-photon ionization of cyanuric acid should occur at ca. 150 nm. Collectively, the quantum-chemical calculations predict that cyanuric acid would have been highly photostable under the solar radiation conditions reaching the Earth’s surface during the prebiotic era in an aqueous solution. Of relevance to the chemical origin of life and RNA-first theories, these observations lend support to the idea that cyanuric acid could have accumulated in large quantities during the prebiotic era and thus strengthens its candidature as a relevant prebiotic nucleobase.

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Section: Introductionmentioning

confidence: 99%

On the Photostability of Cyanuric Acid and Its Candidature as a Prebiotic Nucleobase

2022

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“…2 ) or the extraction of ultrathin rock sections using a focused ion beam ( e.g. , Cavalazzi, 2007 ; Schiffbauer and Xiao, 2009 ; Cavalazzi et al, 2021 ), isotope geochemistry requiring the identification and isolation of individual mineral phases or fabric elements ( e.g., Valley et al, 1994 ; van den Boorn et al, 2010 ; Lowe et al, 2020 ), high-resolution tomography requiring minimally invasive sample preparation ( e.g., Hickman-Lewis et al, 2016b , 2019; Maldanis et al, 2020 ), and organic geochemistry requiring the solvent extraction of organic aliquots ( e.g., Duda et al, 2018 ).…”

Section: Discussionmentioning

confidence: 99%

“…Correlative microanalysis, that is, the systematic acquisition of spatially colocated, mutually corroborative data, has emerged as a compelling approach in the evaluation of the biogenicity, metabolic networks, and taphonomy of microbial biosignatures in deep time (Brasier et al, 2015 ; Hickman-Lewis et al, 2019 ; Wacey et al, 2019; Cavalazzi et al, 2021 ) and is expected to be an essential strategy in the search for life on Mars. WATSON, SHERLOC, and PIXL can correlatively study mineralogical, molecular, and elemental distributions and concentrations in rock targets on Mars; these detections can be ascribed to specific phases and textures, and this can be considered a planetary science equivalent of terrestrial correlative microanalysis.…”

Section: Introductionmentioning

confidence: 99%

In Situ Identification of Paleoarchean Biosignatures Using Colocated Perseverance Rover Analyses: Perspectives for In Situ Mars Science and Sample Return

et al. 2022

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The NASA Mars 2020 Perseverance rover is currently exploring Jezero crater, a Noachian–Hesperian locality that once hosted a delta–lake system with high habitability and biosignature preservation potential. Perseverance conducts detailed appraisals of rock targets using a synergistic payload capable of geological characterization from kilometer to micron scales. The highest-resolution textural and chemical information will be provided by correlated WATSON (imaging), SHERLOC (deep-UV Raman and fluorescence spectroscopy), and PIXL (X-ray lithochemistry) analyses, enabling the distributions of organic and mineral phases within rock targets to be comprehensively established. Herein, we analyze Paleoarchean microbial mats from the ∼3.42 Ga Buck Reef Chert (Barberton greenstone belt, South Africa)—considered astrobiological analogues for a putative ancient martian biosphere—following a WATSON–SHERLOC–PIXL protocol identical to that conducted by Perseverance on Mars during all sampling activities. Correlating deep-UV Raman and fluorescence spectroscopic mapping with X-ray elemental mapping, we show that the Perseverance payload has the capability to detect thermally and texturally mature organic materials of biogenic origin and can highlight organic–mineral interrelationships and elemental colocation at fine spatial scales. We also show that the Perseverance protocol obtains very similar results to high-performance laboratory imaging, Raman spectroscopy, and μXRF instruments. This is encouraging for the prospect of detecting microscale organic-bearing textural biosignatures on Mars using the correlative micro-analytical approach enabled by WATSON, SHERLOC, and PIXL; indeed, laminated, organic-bearing samples such as those studied herein are considered plausible analogues of biosignatures from a potential Noachian–Hesperian biosphere. Were similar materials discovered at Jezero crater, they would offer opportunities to reconstruct aspects of the early martian carbon cycle and search for potential fossilized traces of life in ancient paleoenvironments. Such samples should be prioritized for caching and eventual return to Earth.

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“…Luca (a baby Pseudomonas, only 300 years old): Granny, please tell me a story! Granny (783 451 years old; Oehler et al, 2017;Moger-Reischer and Lennon, 2019;Vuillemin et al, 2020;Cavalazzi et al, 2021; Luca: Well, Mummy told me that, a while ago, some microbes used light and stuff called organic matter, instead of hydrogen, to grow and that this allowed them to live together in unbelievable numbers, not like us in communities of around about 200 cells.…”

Section: Special Issue Articlementioning

confidence: 99%

The darkest microbiome—a post‐human biosphere

Timmis

Hallsworth

2021

Microbial Biotechnology

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Summary Microbial technology is exceptional among human activities and endeavours in its range of applications that benefit humanity, even exceeding those of chemistry. What is more, microbial technologists are among the most creative scientists, and the scope of the field continuously expands as new ideas and applications emerge. Notwithstanding this diversity of applications, given the dire predictions for the fate of the surface biosphere as a result of current trajectories of global warming, the future of microbial biotechnology research must have a single purpose, namely to help secure the future of life on Earth. Everything else will, by comparison, be irrelevant. Crucially, microbes themselves play pivotal roles in climate (Cavicchioli et al., Nature Revs Microbiol 17: 569–586, 2019). To enable realization of their full potential in humanity’s effort to survive, development of new and transformative global warming‐relevant technologies must become the lynchpin of microbial biotechnology research and development. As a consequence, microbial biotechnologists must consider constraining their usual degree of freedom, and re‐orienting their focus towards planetary‐biosphere exigences. And they must actively seek alliances and synergies with others to get the job done as fast as humanly possible; they need to enthusiastically embrace and join the global effort, subordinating where necessary individual aspirations to the common good (the amazing speed with which new COVID‐19 diagnostics and vaccines were developed and implemented demonstrates what is possible given creativity, singleness of purpose and funding). In terms of priorities, some will be obvious, others less so, with some only becoming revealed after dedicated effort yields new insights/opens new vistas. We therefore refrain from developing a priority list here. Rather, we consider what is likely to happen to the Earth’s biosphere if we (and the rest of humanity) fail to rescue it. We do so with the aim of galvanizing the formulation and implementation of strategic and financial science policy decisions that will maximally stimulate the development of relevant new microbial technologies, and maximally exploit available technologies, to repair existing environmental damage and mitigate against future deterioration.

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Cellular remains in a ~3.42-billion-year-old subseafloor hydrothermal environment

Cited by 44 publications

References 87 publications

On the Photostability of Cyanuric Acid and Its Candidature as a Prebiotic Nucleobase

On the Photostability of Cyanuric Acid and Its Candidature as a Prebiotic Nucleobase

In Situ Identification of Paleoarchean Biosignatures Using Colocated Perseverance Rover Analyses: Perspectives for In Situ Mars Science and Sample Return

The darkest microbiome—a post‐human biosphere

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