Archean Molecular Fossils and the Early Rise of Eukaryotes

Brocks, Jochen J.; Logan, Graham A.; Buick, Roger; Summons, Roger E.

doi:10.1126/science.285.5430.1033

Cited by 1,114 publications

(591 citation statements)

References 27 publications

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“…It can be argued that the sudden appearance of carbonate platforms at about 2.9 Ga is connected to the evolutionary advancement of life and the appearance of cyanobacteria at that time. Although the occurrence of cyanobacterial biomarkers in rocks as old as 2.8 Ga (Brocks et al, 1999(Brocks et al, , 2003 has been recently questioned Rasmussen et al, 2008) independent investigation confirm such findings (Eigenbrode et al, 2008). Thus, cyanobacterial calcification is plausible at that time and was probably the most important rockforming process of biomineralization (Altermann, 2002.…”

Section: Discussionsupporting

confidence: 61%

“…Earlier multiple descriptions of coccoid microfossils including Eoentophysalis, from a similar stratigraphic level of the Campbellrand Subgroup (Altermann and Schopf, 1995) and from the age-equivalent Chuniespoort Group (Transvaal Supergroup, Transvaal preservational basin; Lanier, 1986) support our findings and interpretation. Further support can be derived from the report of cyanobacterial molecular fossils (steranes and related products of carbon maturation) in Archean shales of similar age, but from Australia (Brocks et al, 1999;Eigenbrode et al, 2008).…”

Section: Discussionmentioning

confidence: 99%

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Mass occurrence of benthic coccoid cyanobacteria and their role in the production of Neoarchean carbonates of South Africa

Kaźmierczak

Altermann

Kremer

et al. 2009

Precambrian Research

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a b s t r a c tThe sparse Archean fossil record is based almost entirely on carbonaceous remnants of microorganisms cellularly preserved due to their early post-mortem silicification. Hitherto as an exception, sedimentary carbonate rocks from the Neoarchean Nauga Formation of South Africa contain calcified microbial mats composed of microbiota closely resembling modern benthic colonial cyanobacteria (Chroococcales and Pleurocapsales). Their remains, visible under the scanning electron microscope (SEM) after etching of polished rock samples, comprise capsular envelopes, mucilage sheaths, and groups of cells mineralized by calcium carbonate with an admixture of Al-K-Mg-Fe silicates. The capsular organization of the mucilaginous sheaths surrounding individual cells and cell clusters forming colonies and the mode of mineralization are the characteristic common features of the Neoarchean microbiota described and their modern analogues. The new findings indicate massive production of calcium carbonates by benthic coccoid cyanobacteria in the Neoarchean, and offer a solution to the problem of the origin of Archean carbonate platforms, stromatolites and microbial reefs.

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Section: Discussionsupporting

confidence: 61%

Section: Discussionmentioning

confidence: 99%

Mass occurrence of benthic coccoid cyanobacteria and their role in the production of Neoarchean carbonates of South Africa

Kaźmierczak

Altermann

Kremer

et al. 2009

Precambrian Research

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“…These data are consistent with molecular dating analyses that place the last common ancestor of eukaryotes at between 1.9 and 1.7 billion years ago 76 . An earlier origin for eukaryotes had been suggested on the basis of the presence of sterane biomarkers in 2.7-billion-year-old rocks 77 , but these were subsequently shown to be contaminants from younger rocks 78,79 . An early origin for Archaea has been inferred on the basis of the presence of biological methane, today produced only by methanogenic Euryarchaeota, in rocks that are 3.5 billion years old 80 .…”

Section: The Origin Of Eukaryotes In Light Of Other Datamentioning

confidence: 99%

An archaeal origin of eukaryotes supports only two primary domains of life

Williams

Foster

Cox

et al. 2013

Nature

441

367

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The discovery of the Archaea and the proposal of the three-domains 'universal' tree, based on ribosomal RNA and core genes mainly involved in protein translation, catalysed new ideas for cellular evolution and eukaryotic origins. However, accumulating evidence suggests that the three-domains tree may be incorrect: evolutionary trees made using newer methods place eukaryotic core genes within the Archaea, supporting hypotheses in which an archaeon participated in eukaryotic origins by founding the host lineage for the mitochondrial endosymbiont. These results provide support for only two primary domains of life-Archaea and Bacteria-because eukaryotes arose through partnership between them.S ince their discovery by Carl Woese and his co-workers in 1977, the Archaea have figured prominently in hypotheses for eukaryotic origins 1,2 . Although similar to Bacteria in terms of cell structure, molecular phylogenies for ribosomal RNA and a small core of genes, that mainly have essential roles in protein translation 3 , suggested that the Archaea were more closely related to the eukaryotic nuclear lineage; that is, to the host cell that acquired the mitochondrion 4 . The idea that Archaea and eukaryotes are more closely related to each other than either is to Bacteria depends on analyses suggesting that the root of the tree should be placed on the bacterial stem, or within the Bacteria 5-12 , implying that the prokaryotes-cells that lack a nucleus-are a paraphyletic group 13 . The main question now debated is whether core components of the eukaryotic nuclear lineage descend from a common ancestor shared with Archaea, as in the three-domains tree 14 (Fig. 1), which is also often called the 'universal tree' or 'tree of life' 15-17 , or from within the Archaea, as proposed by archaeal-host hypotheses for eukaryotic origins 2 . The archaeal-host scenario with the greatest phylogenetic support is the eocyte hypothesis 18 , which proposes a sister-group relationship between eukaryotes and the eocytes (or Crenarchaeota 14 ), one of the major archaeal divisions (Fig. 1). However, the three-domains-eocyte debate remains controversial because different phylogenetic methods have delivered different results, often from the same data 19 . This disagreement is due, at least in part, to the difficulties associated with resolving ancient divergences in phylogenetic trees. Challenges of reconstructing ancient relationshipsA major issue in reconstructing ancient relationships is the strength and quality of historical signal remaining after the millions of years since the divergence of Archaea and eukaryotes. The earliest fossils identified as eukaryotic appeared by about 1.8 billion years ago 20 ; over this enormous span of time, the accumulation of multiple substitutions in DNA and protein sequences might have erased any signal that would allow the relationship between archaeal and eukaryotic core genes to be established 21 . However, more recent simulations and empirical studies suggest that there are reasons to be cautiously optimistic ...

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“…Concerns about contamination, and doubts about reports of steroidal hydrocarbons in the 2.7 billion year-old Fortescue Group sediments of the Pilbara Craton (Brocks et al, 1999), were initially raised in 2003(Brocks et al, 2003. These potential problems became increasingly difficult to dismiss when new and improved types of geochemical analyses were devised and applied.…”

mentioning

confidence: 99%

Paleoproterozoic sterol biosynthesis and the rise of oxygen

Gold

Caron

Fournier

et al. 2017

Nature

Self Cite

102

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The Record of Precambrian Steroidal HydrocarbonsThe record of sterane and triterpane hydrocarbon biomarkers in Archean and Proterozoic sedimentary rocks has come under extremely thorough scrutiny in recent times. Concerns about contamination, and doubts about reports of steroidal hydrocarbons in the 2.7 billion year-old Fortescue Group sediments of the Pilbara Craton (Brocks et al., 1999), were initially raised in 2003(Brocks et al., 2003. These potential problems became increasingly difficult to dismiss when new and improved types of geochemical analyses were devised and applied. For example, Brocks and colleagues showed that a selection of rock and sediment samples from a range of localities were ubiquitously contaminated with petroleum-and plastic-derived organic compounds . Analyses of thin slices of sediment core showed that spatial distributions of hydrocarbons could be used to distinguish indigenous hydrocarbons from surface contaminants in Archean shales (Brocks, 2011). In another example, the carbon isotopic data values of in situ and insoluble kerogen and pyrobitumen in rock formations that had previously yielded biomarkers were discrepant from those of the extractable hydrocarbons, meaning that the latter could not be indigenous (Rasmussen et al., 2008).

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Archean Molecular Fossils and the Early Rise of Eukaryotes

Cited by 1,114 publications

References 27 publications

Mass occurrence of benthic coccoid cyanobacteria and their role in the production of Neoarchean carbonates of South Africa

Mass occurrence of benthic coccoid cyanobacteria and their role in the production of Neoarchean carbonates of South Africa

An archaeal origin of eukaryotes supports only two primary domains of life

Paleoproterozoic sterol biosynthesis and the rise of oxygen

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