Unveiling billion-year old life forms with X-ray vision

An international team of scientists from Brazil, France and Switzerland with financial support from the Serrapilheira Institute and Fapesp, has obtained the most detailed 3D views ever achieved of very ancient traces of life on Earth. The studied microfossils, from the Gunflint Formation, in Canada, are approximately 1.9 billion years old, and are the preserved remains of microorganisms similar to bacteria existing today, but from a period when only microscopic life existed on Earth. Using an advanced imaging method based on synchrotron light, unprecedented details of the shape, composition and preservation of these microfossils was attained. Moreover, in one locality, fossils previously termed “hematite-coated” are revealed to be composed of organic material – invisible in optical microscopy – coated with crystals of the iron oxide maghemite, instead of hematite. This finding challenges our understanding of past life and opens exciting perspectives for the study of even older fossils or future samples returned from Mars.

Maldanis, L., Hickman-Lewis, K., Verezhak, M. et al. Nanoscale 3D quantitative imaging of 1.88 Ga Gunflint microfossils reveals novel insights into taphonomic and biogenic characters. Scientific Reports 10, 8163 (2020). https://doi.org/10.1038/s41598-020-65176-w

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3D observation of microfossils

Metallomics in geological time: trace element biosignatures evidence the influence of ocean chemistry on Earth’s earliest ecosystems

We used a combination of techniques: microbeam particle-induced X-ray emission spectroscopy (PIXE), carbon isotope geochemistry and electron microscopy. This has allowed us to discover trace element signatures of life in 3.33 billion-year-old rocks from South Africa. These signatures support a long-standing hypothesis that biological dependency on trace elements results from the enrichment of these elements in the metal-rich, hydrothermally influenced habitats of early life.

We approached this challenge through the biological concept of the metallome, which refers to the entirety of the inorganic species (metal and metalloid) within a cell. Although the genome and proteome do not survive fossilisation over billions of years, it is probable that metal concentrations within carbonaceous materials could do so, and indeed we found this to be the case in numerous carbon-rich microstructures from the Josefsdal Chert.

We found that a range of elements crucial to anaerobic microbes, including Fe, V, Ni, As and Co, were enriched within carbonaceous material characterised by negative carbon isotope signatures indicating biological origins.

Palaeo-metallome compositions could be used to deduce the metabolic networks of Earth’s earliest ecosystems and, potentially, as a biosignature for the evaluation of organic materials found on Mars.

The article “Metallomics in deep time and the influence of ocean chemistry on the metabolic landscapes of Earth’s earliest ecosystems” released March 18th in Scientific Reports.

Contact: keyron.hickman-lewis@cnrs.fr; frances.westall@cnrs.fr


Conference – Exomars Mission: Life on the Red Planet – September 5th, 2019, Orléans

Conference - Exomars Mission: Life on the Red Planet - September 5th, 2019, Orléans

Given the success of the general public conference of Dr. Michel Viso, of the French Space Agency (CNES), a new presentation will take place

Thursday, September 5, 2019 at 18:00 at the Dupanloup Hotel, rue Dupanloup, 45000 Orléans.

With for the first time in France: Exhibition of the real size model of the robot Rosalind Franklin!

Free admission but limited places!

Conférence soutenue par L’ESA, le CNES, le CNRS (l’OSUC, le CBM, le LPC2E), l’Université d’Orléans, LOIRE&ORLÉANS ÉCO, la Région Centre.