Fungus-like mycelial fossils in 2.4-billion-year-old vesicular basalt

Bengtson, Stefan; Rasmussen, Birger; Ivarsson, Magnus; Muhling, Janet R.; Broman, Curt; Marone, Federica; Stampanoni, Marco; Bekker, Andrey

doi:10.1038/s41559-017-0141

Cited by 110 publications

(125 citation statements)

References 67 publications

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“…The origin of eukaryotes is one of the central transitions in the history of life; without eukaryotes there would be no complex multicellular life. The fossil evidence of eukaryotic cells dates back to 1.6‐1.8 billion years, , and even older findings have been suggested up to the time of the oxygen revolution 2.4 billion years ago. There still exists unknown questions in the origin of eukaryotes.…”

Section: Introductionmentioning

confidence: 99%

Eukaryote specific folds: Part of the whole

Kauko

Lehto

2018

Proteins

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The origin of eukaryotes is one of the central transitions in the history of life; without eukaryotes there would be no complex multicellular life. The most accepted scenarios suggest the endosymbiosis of a mitochondrial ancestor with a complex archaeon, even though the details regarding the host and the triggering factors are still being discussed. Accordingly, phylogenetic analyses have demonstrated archaeal affiliations with key informational systems, while metabolic genes are often related to bacteria, mostly to the mitochondrial ancestor. Despite of this, there exists a large number of protein families and folds found only in eukaryotes. In this study, we have analyzed structural superfamilies and folds that probably appeared during eukaryogenesis. These folds typically represent relatively small binding domains of larger multidomain proteins. They are commonly involved in biological processes that are particularly complex in eukaryotes, such as signaling, trafficking/cytoskeleton, ubiquitination, transcription and RNA processing, but according to recent studies, these processes also have prokaryotic roots. Thus the folds originating from an eukaryotic stem seem to represent accessory parts that have contributed in the expansion of several prokaryotic processes to a new level of complexity. This might have taken place as a co-evolutionary process where increasing complexity and fold innovations have supported each other.

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Section: Introductionmentioning

confidence: 99%

Eukaryote specific folds: Part of the whole

Kauko

Lehto

2018

Proteins

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“…The oldest plausible candidate fossils from the subsurface are simple pyritic filaments of Archean age from a marine volcanogenic sulfide deposit in Western Australia; these contain carbon‐ and nitrogen‐rich domains likely to be organic residues and so are probably biogenic, but their origination depth is unclear . To our knowledge, there are no other plausible candidate deep biosphere fossils from the Archean (see Brasier et al for discussion of some famous vein‐hosted pseudofossils of this age), and only one from the whole of the Proterozoic Eon, a stretch of ≈2 billion years, i.e., about 40% of Earth's history . Compared with the diversity of the modern deep biosphere, the putative fossil record described to date is also extremely impoverished.…”

Section: Major Challenges For Subsurface Palaeobiologymentioning

confidence: 93%

“…Septation is evident in a few examples . Branching is common but not ubiquitous; anastomosis is less common, but occasionally results in complex mycelium‐like networks interconnected by anastomosis . Discrete swellings may rarely be found along the length of the filaments or, more typically, at their tips; otherwise, filaments are usually of constant thickness along their length and tapering is rare.…”

Section: The Fossil Record Of Deep Life: Reports To Datementioning

confidence: 99%

“…However, the probable fungal affinity of most of these candidate fossils arguably undermines their value as “search images” for Mars‐centered astrobiology. Fungi are a complex (eukaryotic) form of life that appeared relatively late in Earth history . Organisms sustained by lithoautotrophic metabolic strategies plausible for hypothetical life on Mars (e.g., methanogenesis; nitrate‐dependent iron oxidation) are abundant in Earth's deep biosphere, but it has not been demonstrated that any of the candidate fossils from the deep biosphere represent such organisms, although some rather unusual examples might conceivably do so .…”

Section: Major Challenges For Subsurface Palaeobiologymentioning

confidence: 99%

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A New Frontier for Palaeobiology: Earth's Vast Deep Biosphere

McMahon

Ivarsson

2019

BioEssays

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Diverse micro‐organisms populate a global deep biosphere hosted by rocks and sediments beneath land and sea, containing more biomass than any other biome except forests. This paper reviews an emerging palaeobiological archive of these dark habitats: microfossils preserved in ancient pores and fractures in the crust. This archive, seemingly dominated by mineralized filaments (although rods and coccoids are also reported), is presently far too sparsely sampled and poorly understood to reveal trends in the abundance, distribution, or diversity of deep life through time. New research is called for to establish the nature and extent of the fossil record of Earth's deep biosphere by combining systematic exploration, rigorous microanalysis, and experimental studies of both microbial preservation and the formation of abiotic pseudofossils within the crust. It is concluded that the fossil record of Earth's largest microbial habitat may still have much to tell us about the history of life, the evolution of biogeochemical cycles, and the search for life on Mars.

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“…In this case, the information of shape/arrangement of microstructures and element distributions on fossils can be extracted by ESEM so that to provide paleogeographic environmental data of stratigraphic formation for determining geological age and stratigraphic correlation. Many studies about fossils based on ESEM have hence made significant contributions to cultural heritage conservation . For example, McPherron et al observed the fossilized bones under ESEM and found unambiguous stone‐tool cut marks for flesh removal and percussion marks for marrow access.…”

Section: Recent Applicationsmentioning

confidence: 99%

Applications of ESEM on Materials Science: Recent Updates and a Look Forward

et al. 2019

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The microscopic understanding of materials relies on the development of microscopy. Historically, the technological evolution from optical microscopes to electron microscopes has directly stimulated many discoveries of new physical and chemical fundamentals as well as advanced materials. Scanning electron microscopy (SEM) is, undoubtedly, the most widely used tool for microscopic characterization in modern materials science. Especially, the incorporation of a gas pressure around the sample area of conventional SEM, i.e., the environmental scanning electron microscope (ESEM), has opened new possibilities in observing samples in their natural states, leading to unprecedented chances for studying the details of biological, organic, and hydrated samples. What is more, in recent years, in situ ESEM studies concerning materials change and chemical reactions have played a more important role in the field of materials science. Herein, the recent applications of ESEM in materials science are comprehensively reviewed, in terms of common static observations for various materials and in situ investigations of dynamic processes in controlled experimental environments. Moreover, the problems concerning state‐of‐the‐art ESEM experiments are discussed, as well as possible solutions. Looking forward, the rapid developments on instrumentation and fundamental science of ESEM can bring a clear vision of materials in the near future.

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Fungus-like mycelial fossils in 2.4-billion-year-old vesicular basalt

Cited by 110 publications

References 67 publications

Eukaryote specific folds: Part of the whole

Eukaryote specific folds: Part of the whole

A New Frontier for Palaeobiology: Earth's Vast Deep Biosphere

Applications of ESEM on Materials Science: Recent Updates and a Look Forward

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