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Lukmanov RA, Tulej M, Wiesendanger R, Riedo A, Grimaudo V, Ligterink NFW, de Koning C, Neubeck A, Wacey D, Wurz P. Multiwavelength Ablation/Ionization and Mass Spectrometric Analysis of 1.88 Ga Gunflint Chert. ASTROBIOLOGY 2022; 22:369-386. [PMID: 35196459 DOI: 10.1089/ast.2019.2201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The investigation of chemical composition on planetary bodies without significant sample processing is of importance for nearly every mission aimed at robotic exploration. Moreover, it is a necessary tool to achieve the longstanding goal of finding evidence of life beyond Earth, for example, possibly preserved microbial remains within martian sediments. Our Laser Ablation Ionization Mass Spectrometer (LIMS) is a compact time-of-flight mass spectrometer intended to investigate the elemental, isotope, and molecular composition of a wide range of solid samples, including e.g., low bulk density organic remains in microfossils. Here, we present an overview of the instrument and collected chemical spectrometric data at the micrometer level from a Precambrian chert sample (1.88 Ga Gunflint Formation, Ontario, Canada), which is considered to be a martian analogue. Data were collected from two distinct zones-a silicified host area and a carbon-bearing microfossil assemblage zone. We performed these measurements using an ultrafast pulsed laser system (pulse width of ∼180 fs) with multiple wavelengths (infrared [IR]-775 nm, ultraviolet [UV]-387 nm, UV-258 nm) and using a pulsed high voltage on the mass spectrometer to reveal small organic signals. We investigated (1) the chemical composition of the sample and (2) the different laser wavelengths' performance to provide chemical depth profiles in silicified media. Our key findings are as follows: (1) microfossils from the Gunflint chert reveal a distinct chemical composition compared with the host mineralogy (we report the identification of 24 elements in the microfossils); (2) detection of the pristine composition of microfossils and co-occurring fine chemistry (rare earth elements) requires utilization of the depth profiling measurement protocol; and (3) our results show that, for analysis of heterogeneous material from siliciclastic deposits, siliceous sinters, and cherts, the most suitable wavelength for laser ablation/Ionization is UV-258 nm.
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Affiliation(s)
- Rustam A Lukmanov
- Space Research & Planetary Sciences (WP), Physics Institute, University of Bern, Bern, Switzerland
| | - Marek Tulej
- Space Research & Planetary Sciences (WP), Physics Institute, University of Bern, Bern, Switzerland
| | - Reto Wiesendanger
- Space Research & Planetary Sciences (WP), Physics Institute, University of Bern, Bern, Switzerland
| | - Andreas Riedo
- Space Research & Planetary Sciences (WP), Physics Institute, University of Bern, Bern, Switzerland
| | - Valentine Grimaudo
- Space Research & Planetary Sciences (WP), Physics Institute, University of Bern, Bern, Switzerland
| | - Niels F W Ligterink
- Space Research & Planetary Sciences (WP), Physics Institute, University of Bern, Bern, Switzerland
| | - Coenraad de Koning
- Space Research & Planetary Sciences (WP), Physics Institute, University of Bern, Bern, Switzerland
| | - Anna Neubeck
- Department of Earth Sciences, Uppsala University, Uppsala, Sweden
| | - David Wacey
- Centre for Microscopy, Characterization and Analysis, The University of Western Australia, Perth, Australia
| | - Peter Wurz
- Space Research & Planetary Sciences (WP), Physics Institute, University of Bern, Bern, Switzerland
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Strother PK, Brasier MD, Wacey D, Timpe L, Saunders M, Wellman CH. A possible billion-year-old holozoan with differentiated multicellularity. Curr Biol 2021; 31:2658-2665.e2. [PMID: 33852871 DOI: 10.1016/j.cub.2021.03.051] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 12/07/2020] [Accepted: 03/15/2021] [Indexed: 02/05/2023]
Abstract
Sediments of the Torridonian sequence of the Northwest Scottish Highlands contain a wide array of microfossils, documenting life in a non-marine setting a billion years ago (1 Ga).1-4 Phosphate nodules from the Diabaig Formation at Loch Torridon preserve microorganisms with cellular-level fidelity,5,6 allowing for partial reconstruction of the developmental stages of a new organism, Bicellum brasieri gen. et sp. nov. The mature form of Bicellum consists of a solid, spherical ball of tightly packed cells (a stereoblast) of isodiametric cells enclosed in a monolayer of elongated, sausage-shaped cells. However, two populations of naked stereoblasts show mixed cell shapes, which we infer to indicate incipient development of elongated cells that were migrating to the periphery of the cell mass. These simple morphogenetic movements could be explained by differential cell-cell adhesion.7,8 In fact, the basic morphology of Bicellum is topologically similar to that of experimentally produced cell masses that were shown to spontaneously segregate into two distinct domains based on differential cadherin-based cell adhesion.9 The lack of rigid cell walls in the stereoblast renders an algal affinity for Bicellum unlikely: its overall morphology is more consistent with a holozoan origin. Unicellular holozoans are known today to form multicellular stages within complex life cycles,10-13 so the occurrence of such simple levels of transient multicellularity seen here is consistent with a holozoan affinity. Regardless of precise phylogenetic placement, these fossils demonstrate simple cell differentiation and morphogenic processes that are similar to those seen in some metazoans today.
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Affiliation(s)
- Paul K Strother
- Department of Earth & Environmental Sciences, Weston Observatory of Boston College, 381 Concord Road, Weston, MA 02493, USA.
| | - Martin D Brasier
- Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK
| | - David Wacey
- Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, 35 Stirling Highway, Perth, WA 6009, Australia
| | - Leslie Timpe
- Department of Biology, San Francisco State University, San Francisco, CA 94132, USA
| | - Martin Saunders
- Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, 35 Stirling Highway, Perth, WA 6009, Australia
| | - Charles H Wellman
- Department of Animal & Plant Sciences, University of Sheffield, Alfred Denny Building, Western Bank, Sheffield S10 2TN, UK
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