Lokiarchaeota

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Lokiarchaeota
Candidatus Prometheoarchaeum syntrophicum SEM.jpg
SEM image of Candidatus Prometheoarchaeum syntrophicum
Scientific classification
Domain:
Archaea
Kingdom:
Proteoarchaeota
Superphylum:
Asgard
Phylum:
Lokiarchaeota

Spang et al. 2015
Class:
Lokiarchaeia

corrig. Spang et al. 2015
Order
  • Lokiarchaeales
Synonyms
  • Lokiarchaeia Imachi et al. 2024 (de-ranked)
  • Promethearchaeia Imachi et al. 2024 (de-ranked, applies to Prometheoarchaeum)

Lokiarchaeota is a proposed phylum of the Archaea. [1] The phylum includes all members of the group previously named Deep Sea Archaeal Group, also known as Marine Benthic Group B. Lokiarchaeota is part of the superphylum Asgard containing the phyla: Lokiarchaeota, Thorarchaeota, Odinarchaeota, Heimdallarchaeota, and Helarchaeota. [2] A phylogenetic analysis disclosed a monophyletic grouping of the Lokiarchaeota with the eukaryotes. The analysis revealed several genes with cell membrane-related functions. The presence of such genes support the hypothesis of an archaeal host for the emergence of the eukaryotes; the eocyte-like scenarios.

Contents

Lokiarchaeota was introduced in 2015 after the identification of a candidate genome in a metagenomic analysis of a mid-oceanic sediment sample. This analysis suggests the existence of a genus of unicellular life dubbed Lokiarchaeum. The sample was taken near a hydrothermal vent at a vent field known as Loki's Castle located at the bend between Mohns/Knipovich ridge in the Arctic Ocean. [3]

Discovery

Sediments from a gravity core taken in 2010 in the rift valley on the Knipovich ridge in the Arctic Ocean, near the so-called Loki's Castle hydrothermal vent site, were analysed. Specific sediment horizons, previously shown to contain high abundances of novel archaeal lineages [4] [5] were subjected to metagenomic analysis. Due to the low density of cells in the sediment, the resulting genetic sequence does not come from an isolated cell, as would be the case in conventional analysis, but is rather a combination of genetic fragments. [6] The result was a 92% complete, 1.4 fold-redundant composite genome named Lokiarchaeum. [3]

The metagenomic analysis determined the presence of an organism's genome in the sample. [3] However, the organism itself was not cultured until years later, with a Japanese group first reporting isolation and cultivation of a Lokiarchaeota strain in 2019. [7] Since this initial cultivation of Lokiarchaeota, members of the phylum have been reported in a diverse range of habitats. Advances in both long and short-read technologies for DNA sequencing have also aided in the recovery and identification of Lokiarchaeota from microbial samples. [2]

The Lokiarchaeota phylum was proposed based on phylogenetic analyses using a set of highly conserved protein-coding genes. [3] Through a reference to the hydrothermal vent complex from which the first genome sample originated, the name refers to Loki, the Norse shape-shifting god. [6] The Loki of literature has been described as "a staggeringly complex, confusing, and ambivalent figure who has been the catalyst of countless unresolved scholarly controversies", [8] a coincidental analogy to the role of Lokiarchaeota in debates about the origin of eukaryotes. [3]

Description

Candidatus Prometheoarchaeum syntrophicum. (c) SEM of a dividing cell. Scale bar = 1 mm. (d) Cryo-EM of a single cell. Scale bar = 500 nm. White arrows indicate large membrane vesicles. Candidatus Prometheoarchaeum syntrophicum SEM Cryo.jpg
Candidatus Prometheoarchaeum syntrophicum. (c) SEM of a dividing cell. Scale bar = 1 μm. (d) Cryo-EM of a single cell. Scale bar = 500 nm. White arrows indicate large membrane vesicles.

The Lokiarchaeum composite genome consists of 5,381 protein coding genes. Of these, roughly 32% do not correspond to any known protein, 26% closely resemble archaeal proteins, and 29% correspond to bacterial proteins. This situation is consistent with: (i) proteins from a novel phylum (with few close relatives, or none) being difficult to assign to their correct domain; and (ii) existing research that suggests there has been significant inter-domain gene transfer between bacteria and Archaea.

A small, but significant portion of the proteins (175, 3.3%) that the recovered genes code for are very similar to eukaryotic proteins. These proteins included homologs of cytoskeleton proteins, GTPases, and the oligosaccharyltransferase (OST) protein complex. Homologues for components of the endosomal sorting complex required for transport and the ubiquitin protein modifier system were also identified in Lokiarchaeota genome analysis. [2] Sample contamination is an unlikely explanation for the unusual proteins because the recovered genes were always flanked by prokaryotic genes and no genes of known eukaryotic origin were detected in the metagenome from which the composite genome was extracted. Further, previous phylogenetic analysis suggested the genes in question had their origin at the base of the eukaryotic clades. [3]

In eukaryotes, the function of these shared proteins include cell membrane deformation, cell shape formation, and a dynamic protein cytoskeleton. [3] [9] [10] Eukaryotic protein functions found in Lokiarchaeota also include intracellular transport mechanisms. [11] It is inferred then that Lokiarchaeum may have some of these abilities. [3] Another shared protein, actin, is essential for phagocytosis in eukaryotes. [6] [9] Phagocytosis is the ability to engulf and consume another particle; such ability would facilitate the endosymbiotic origin of mitochondria and chloroplasts, which is a key difference between prokaryotes and eukaryotes. [3] The presence of actin proteins and intracellular transport mechanisms provides evidence for the common ancestry between ancient Lokiarchaeota and eukarya. [11]

Taxonomy

Phylogeny of Lokiarchaeota [12] [13] [14]
Prometheoarchaeaceae

Promethearchaeum syntrophicum Imachi et al. 2024

"Candidatus Harpocratesius repetitus" Wu et al. 2022

"Candidatus Lokiarchaeum ossiferum" Rodrigues-Oliveira et al. 2023

Evolutionary significance

A schematic evolutionary tree of the archaea including Lokiarchaeota and the root of eukaryotes A schematic evolutionary tree of the archaea 2015 final.svg
A schematic evolutionary tree of the archaea including Lokiarchaeota and the root of eukaryotes

A comparative analysis of the Lokiarchaeum genome against known genomes resulted in a phylogenetic tree that showed a monophyletic group composed of the Lokiarchaeota and the eukaryotes, [17] supporting an archaeal host or eocyte-like scenarios for the emergence of the eukaryotes. [18] [19] [20] The repertoire of membrane-related functions of Lokiarchaeum suggests that the common ancestor to the eukaryotes might be an intermediate step between the prokaryotic cells, devoid of subcellular structures, and the eukaryotic cells, which harbor many organelles. [3]

Carl Woese's three-domain system classifies cellular life into three domains: archaea, bacteria, and eukaryotes; the last being characterised by large, highly evolved cells, containing mitochondria, which help the cells produce ATP (adenosine triphosphate, the energy currency of the cell), and a membrane-bound nucleus containing nucleic acids. Protozoa and all multicellular organisms such as animals, fungi, and plants are eukaryotes.

The bacteria and archaea are thought to be the most ancient of lineages, [21] as fossil strata bearing the chemical signature of archaeal lipids have been dated back to 3.8 billion years ago. [22] The eukaryotes include all complex cells and almost all multicellular organisms. They are thought to have evolved between 1.6 and 2.1 billion years ago. [23] While the evolution of eukaryotes is considered to be an event of great evolutionary significance, no intermediate forms or "missing links" had been discovered previously. In this context, the discovery of Lokiarchaeum, with some but not all of the characteristics of eukaryotes, provides evidence on the transition from archaea to eukaryotes. [24] Lokiarchaeota and the eukaryotes probably share a common ancestor, and if so, diverged roughly two billion years ago. Evidence for common ancestry, rather than an evolutionary shift from Lokiarchaeota to eukaryotes, is found in analysis of fold superfamilies (FSFs). Fold super families are evolutionarily defined domains of protein structure. It is estimated that there are around 2500 total FSFs found in nature. [11] Utilization of Venn diagrams allowed researchers to depict distributions of FSFs of those that were shared by Archaea and Eukarya, as well as those unique to their respective kingdoms. The addition of Lokiarchaeum into the Venn groups created from an initial genomic census only added 10 FSFs to Archaea. The addition of Lokiarchaeum also only contributed to a decrease of two FSFs previously unique to Eukarya. There were still 284 FSFs found exclusively in Eukarya. Lokiarchaeota’s limited impact in changing the Venn distribution of FSFs demonstrates the lack of genes that could be traced to a common ancestor with Eukaryotes. Rather, Eukaryotic genes present in bacterial and archaeal organisms are hypothesized to be from horizontal transfer from an early ancestor of modern eukaryotes. [11] This putative ancestor possessed crucial "starter" genes that enabled increased cellular complexity. This common ancestor, or a relative, eventually led to the evolution of eukaryotes. [6]

In 2020, a Japanese research group reported culturing a strain of Lokiarchaeota in the laboratory. [25] [26] [7] This strain, currently named Candidatus Prometheoarchaeum syntrophicum strain MK-D1, was observed in syntrophic association with two hydrogen-consuming microbes: a sulfate-reducing bacteria of the genus Halodesulfovibrio and a methanogen of the genus Methanogenium . The MK-D1 organism produces hydrogen as a metabolic byproduct, which is then consumed by the symbiotic syntrophs. MK-D1 also seems to organize its external membrane into complex structures using genes shared with eukaryotes. While association with alphaproteobacteria (from which mitochondria are thought to descend) was not observed, these features suggest that MK-D1 and its syntrophs may represent an extant example of archaea-bacteria symbiosis similar to that which gave rise to eukaryotes. In 2024, the research group published their description of the cultured strain, proposing the name Promethearchaeum syntrophicum (the genus of which differs from the earlier candidate name by dropping the second "o"). [27]

In 2022, the second cultured example of Lokiarchaeota was reported and the strain was named Candidatus Lokiarchaeum ossiferum. [28]

Physiological traits

Lokiarachaeota is known to have a tetrahydromethanopterin-dependent Wood-Ljundahl pathway. This pathway contains a series of biochemical reactions aiding in inorganic carbon utilization. In Lokiarchaeota, the WLP is thought to be acetogenic, due to lacking the gene methyl-CoM reductase necessary for methanogenesis. [2]

Analysis of Lokiarchaeon genes also showed the expression of protein-encoding open reading frames (ORFs) involving the metabolism of sugars and proteins. However, these metabolic activities vary between subgroups of Lokiarchaeota. While Lokiarchaeota subgroups have similar genetic information, differences in metabolic abilities explain their respective ecological niches. [29]

Two major subgroups of the Lokiarachaeota phylum are Loki-2 and Loki-3. Incubations of these two subgroups from Helgoland mud sediments were analyzed through RNA and DNA stable isotope probing to understand their respective carbon metabolisms. [29] Loki-3 were found to be active in both organic carbon utilization and the degradation of aromatic compounds. The Loki-3 subgroup was not found to utilize proteins or short chain fatty acids, even though genes for amino acid degradation were present in both subgroups. Loki-2 was found to utilize protein, as seen through activity in when proteins were provided in Loki-2 incubations. Due to the greater carbon utilization pathways of Loki-3, the subgroup is found in a more diverse range of marine sediments than Loki-2. [29]

See also

Related Research Articles

<span class="mw-page-title-main">Three-domain system</span> Hypothesis for classification of life

The three-domain system is a taxonomic classification system that groups all cellular life into three domains, namely Archaea, Bacteria and Eukarya, introduced by Carl Woese, Otto Kandler and Mark Wheelis in 1990. The key difference from earlier classifications such as the two-empire system and the five-kingdom classification is the splitting of Archaea from Bacteria as completely different organisms. It has been challenged by the two-domain system that divides organisms into Bacteria and Archaea only, as Eukaryotes are considered a clade of Archaea.

<i>Nanoarchaeum equitans</i> Species of archaeon

Nanoarchaeum equitans is a species of marine archaea that was discovered in 2002 in a hydrothermal vent off the coast of Iceland on the Kolbeinsey Ridge by Karl Stetter. It has been proposed as the first species in a new phylum, and is the only species within the genus Nanoarchaeum. Strains of this microbe were also found on the Sub-polar Mid Oceanic Ridge, and in the Obsidian Pool in Yellowstone National Park. Since it grows in temperatures approaching boiling, at about 80 °C (176 °F), it is considered to be a thermophile. It grows best in environments with a pH of 6, and a salinity concentration of 2%. Nanoarchaeum appears to be an obligate symbiont on the archaeon Ignicoccus; it must be in contact with the host organism to survive. Nanoarchaeum equitans cannot synthesize lipids but obtains them from its host. Its cells are only 400 nm in diameter, making it the smallest known living organism, and the smallest known archaeon.

<span class="mw-page-title-main">Korarchaeota</span> Proposed phylum within the Archaea

The Korarchaeota is a proposed phylum within the Archaea. The name is derived from the Greek noun koros or kore, meaning young man or young woman, and the Greek adjective archaios which means ancient. They are also known as Xenarchaeota. The name is equivalent to Candidatus Korarchaeota, and they go by the name Xenarchaeota or Xenarchaea as well.

The hydrogen hypothesis is a model proposed by William F. Martin and Miklós Müller in 1998 that describes a possible way in which the mitochondrion arose as an endosymbiont within a prokaryotic host in the archaea, giving rise to a symbiotic association of two cells from which the first eukaryotic cell could have arisen (symbiogenesis).

<span class="mw-page-title-main">Last universal common ancestor</span> Most recent common ancestor of all current life on Earth

The last universal common ancestor (LUCA) is the hypothesized common ancestral cell from which the three domains of life, the Bacteria, the Archaea, and the Eukarya originated. The cell had a lipid bilayer; it possessed the genetic code and ribosomes which translated from DNA or RNA to proteins. The LUCA probably existed at latest 3.6 billion years ago, and possibly as early as 4.3 billion years ago or earlier. The nature of this point or stage of divergence remains a topic of research.

Viral eukaryogenesis is the hypothesis that the cell nucleus of eukaryotic life forms evolved from a large DNA virus in a form of endosymbiosis within a methanogenic archaeon or a bacterium. The virus later evolved into the eukaryotic nucleus by acquiring genes from the host genome and eventually usurping its role. The hypothesis was first proposed by Philip Bell in 2001 and was further popularized with the discovery of large, complex DNA viruses that are capable of protein biosynthesis.

<span class="mw-page-title-main">Archaea</span> Domain of organisms

Archaea is a domain of organisms. Traditionally, Archaea only included its prokaryotic members, but this sense has been found to be paraphyletic, as eukaryotes are now known to have evolved from archaea. Even though the domain Archaea includes eukaryotes, the term "archaea" in English still generally refers specifically to prokaryotic members of Archaea. Archaea were initially classified as bacteria, receiving the name archaebacteria, but this term has fallen out of use.

<span class="mw-page-title-main">Nitrososphaerota</span> Phylum of archaea

The Nitrososphaerota are a phylum of the Archaea proposed in 2008 after the genome of Cenarchaeum symbiosum was sequenced and found to differ significantly from other members of the hyperthermophilic phylum Thermoproteota. Three described species in addition to C. symbiosum are Nitrosopumilus maritimus, Nitrososphaera viennensis, and Nitrososphaera gargensis. The phylum was proposed in 2008 based on phylogenetic data, such as the sequences of these organisms' ribosomal RNA genes, and the presence of a form of type I topoisomerase that was previously thought to be unique to the eukaryotes. This assignment was confirmed by further analysis published in 2010 that examined the genomes of the ammonia-oxidizing archaea Nitrosopumilus maritimus and Nitrososphaera gargensis, concluding that these species form a distinct lineage that includes Cenarchaeum symbiosum. The lipid crenarchaeol has been found only in Nitrososphaerota, making it a potential biomarker for the phylum. Most organisms of this lineage thus far identified are chemolithoautotrophic ammonia-oxidizers and may play important roles in biogeochemical cycles, such as the nitrogen cycle and the carbon cycle. Metagenomic sequencing indicates that they constitute ~1% of the sea surface metagenome across many sites.

Evolution of cells refers to the evolutionary origin and subsequent evolutionary development of cells. Cells first emerged at least 3.8 billion years ago approximately 750 million years after Earth was formed.

<span class="mw-page-title-main">Eocyte hypothesis</span> Hypothesis in evolutionary biology

The eocyte hypothesis in evolutionary biology proposes that the eukaryotes originated from a group of prokaryotes called eocytes. After his team at the University of California, Los Angeles discovered eocytes in 1984, James A. Lake formulated the hypothesis as "eocyte tree" that proposed eukaryotes as part of archaea. Lake hypothesised the tree of life as having only two primary branches: prokaryotes, which include Bacteria and Archaea, and karyotes, that comprise Eukaryotes and eocytes. Parts of this early hypothesis were revived in a newer two-domain system of biological classification which named the primary domains as Archaea and Bacteria.

The "Aigarchaeota" are a proposed archaeal phylum of which the main representative is Caldiarchaeum subterraneum. It is not yet clear if this represents a new phylum or a Nitrososphaerota order, since the genome of Caldiarchaeum subterraneum encodes several Nitrososphaerota-like features. The name "Aigarchaeota" comes from the Greek αυγή, avgí, meaning "dawn" or "aurora", for the intermediate features of hyperthermophilic and mesophilic life during the evolution of its lineage.

<span class="mw-page-title-main">Proteoarchaeota</span> Proposed kingdom of archaea

Proteoarchaeota is a proposed archaeal kingdom thought to be closely related and possibly ancestral to the Eukaryotes.

<span class="mw-page-title-main">Parvarchaeota</span> Phylum of archaea

Parvarchaeota is a phylum of archaea belonging to the DPANN archaea. They have been discovered in acid mine drainage waters and later in marine sediments. The cells of these organisms are extremely small consistent with small genomes. Metagenomic techniques allow obtaining genomic sequences from non-cultured organisms, which were applied to determine this phylum.

Nitrososphaera gargensis is a non-pathogenic, small coccus measuring 0.9 ± 0.3 μm in diameter. N. gargensis is observed in small abnormal cocci groupings and uses its archaella to move via chemotaxis. Being an Archaeon, Nitrososphaera gargensis has a cell membrane composed of crenarchaeol, its isomer, and a distinct glycerol dialkyl glycerol tetraether (GDGT), which is significant in identifying ammonia-oxidizing archaea (AOA). The organism plays a role in influencing ocean communities and food production.

"Candidatus Thorarchaeota", or simply Thorarchaeota, is a phylum within the superphylum Asgard archaea. The Asgard superphylum represents the closest prokaryotic relatives of eukaryotes. Since there is such a close relation between the two different domains, it provides further evidence to the two-domain tree of life theory which states that eukaryotes branched from the archaeal domain. Asgard archaea are single cell marine microbes that contain branch like appendages and have genes that are similar to eukarya. The asgard archaea superphylum is composed of Thorarchaeota, Lokiarchaeota, Odinarchaeota, and Heimdallarchaeota. Thorarchaeota were first identified from the sulfate-methane transition zone in tidewater sediments. Thorarcheota are widely distributed in marine and freshwater sediments.

<span class="mw-page-title-main">Asgard (Archaea)</span> Proposed superphylum of Archaea

Asgard or Asgardarchaeota is a proposed superphylum belonging to the domain Archaea that contain eukaryotic signature proteins. It appears that the eukaryotes, the domain that contains the animals, plants, and fungi, emerged within the Asgard, in a branch containing the Heimdallarchaeota. This supports the two-domain system of classification over the three-domain system.

Archaeal initiation factors are proteins that are used during the translation step of protein synthesis in archaea. The principal functions these proteins perform include ribosome RNA/mRNA recognition, delivery of the initiator Met-tRNAiMet, methionine bound tRNAi, to the 40s ribosome, and proofreading of the initiation complex.

<span class="mw-page-title-main">Archaeal virus</span> Type of virus that infects the domain of unicellular, prokaryotic organisms or Archaea

An archaeal virus is a virus that infects and replicates in archaea, a domain of unicellular, prokaryotic organisms. Archaeal viruses, like their hosts, are found worldwide, including in extreme environments inhospitable to most life such as acidic hot springs, highly saline bodies of water, and at the bottom of the ocean. They have been also found in the human body. The first known archaeal virus was described in 1974 and since then, a large diversity of archaeal viruses have been discovered, many possessing unique characteristics not found in other viruses. Little is known about their biological processes, such as how they replicate, but they are believed to have many independent origins, some of which likely predate the last archaeal common ancestor (LACA).

Christa Schleper is a German microbiologist known for her work on the evolution and ecology of Archaea. Schleper is Head of the Department of Functional and Evolutionary Biology at the University of Vienna in Austria.

<span class="mw-page-title-main">Two-domain system</span> Biological classification system

The two-domain system is a biological classification by which all organisms in the tree of life are classified into two domains, Bacteria and Archaea. It emerged from development of knowledge of archaea diversity and challenges the widely accepted three-domain system that classifies life into Bacteria, Archaea, and Eukarya. It was preceded by the eocyte hypothesis of James A. Lake in the 1980s, which was largely superseded by the three-domain system, due to evidence at the time. Better understanding of archaea, especially of their roles in the origin of eukaryotes through symbiogenesis with bacteria, led to the revival of the eocyte hypothesis in the 2000s. The two-domain system became more widely accepted after the discovery of a large group (superphylum) of archaea called Asgard in 2017, which evidence suggests to be the evolutionary root of eukaryotes, thereby making eukaryotes members of the domain Archaea.

References

  1. ↑ Lambert, Jonathan (9 August 2019). "Scientists glimpse oddball microbe that could help explain rise of complex life - 'Lokiarchaea', previously known only from DNA, is isolated and grown in culture". Nature . 572 (7769): 294. Bibcode:2019Natur.572..294L. doi: 10.1038/d41586-019-02430-w . PMID   31409927.
  2. 1 2 3 4 Caceres, Eva F.; Lewis, William H.; Homa, Felix; Martin, Tom; Schramm, Andreas; Kjeldsen, Kasper U.; Ettema, Thijs J. G. (2019-12-18). "Near-complete Lokiarchaeota genomes from complex environmental samples using long and short read metagenomic analyses". bioRxiv: 2019.12.17.879148. doi:10.1101/2019.12.17.879148. S2CID   213982145.
  3. 1 2 3 4 5 6 7 8 9 10 11 Spang, Anja; Saw, Jimmy H.; Jørgensen, Steffen L.; Zaremba-Niedzwiedzka, Katarzyna; Martijn, Joran; Lind, Anders E.; van Eijk, Roel; Schleper, Christa; Guy, Lionel; Ettema, Thijs J. G. (2015). "Complex archaea that bridge the gap between prokaryotes and eukaryotes". Nature. 521 (7551): 173–179. Bibcode:2015Natur.521..173S. doi:10.1038/nature14447. ISSN   0028-0836. PMC   4444528 . PMID   25945739.
  4. ↑ Jørgensen, Steffen Leth; Hannisdal, Bjarte; Lanzen, Anders; Baumberger, Tamara; Flesland, Kristin; Fonseca, Rita; Øvreås, Lise; Steen, Ida H; Thorseth, Ingunn H; Pedersen, Rolf B; Schleper, Christa (September 5, 2012). "Correlating microbial community profiles with geochemical data in highly stratified sediments from the Arctic Mid-Ocean Ridge". PNAS. 109 (42): E2846–55. doi: 10.1073/pnas.1207574109 . PMC   3479504 . PMID   23027979.
  5. ↑ Jørgensen, Steffen Leth; Thorseth, Ingunn H; Pedersen, Rolf B; Baumberger, Tamara; Schleper, Christa (October 4, 2013). "Quantitative and phylogenetic study of the Deep Sea Archaeal Group in sediments of the Arctic mid-ocean spreading ridge". Frontiers in Microbiology. 4: 299. doi: 10.3389/fmicb.2013.00299 . PMC   3790079 . PMID   24109477.
  6. 1 2 3 4 Rincon, Paul (May 6, 2015). "Newly found microbe is close relative of complex life". BBC . Retrieved May 9, 2015.
  7. 1 2 Imachi, Hiroyuki; et al. (15 January 2020). "Isolation of an archaeon at the prokaryote–eukaryote interface". Nature . 577 (7791): 519–525. Bibcode:2020Natur.577..519I. bioRxiv   10.1101/726976 . doi: 10.1038/s41586-019-1916-6 . PMC   7015854 . PMID   31942073.
  8. ↑ von Schnurbein, Stefanie (November 2000). "The Function of Loki in Snorri Sturluson's "Edda"". History of Religions. 40 (2): 109–124. doi:10.1086/463618.
  9. 1 2 Ghoshdastider U, Jiang S, Popp D, Robinson RC (2015). "In search of the primordial actin filament". Proc Natl Acad Sci U S A. 112 (30): 9150–1. doi: 10.1073/pnas.1511568112 . PMC   4522752 . PMID   26178194.
  10. ↑ Khan, Amina (May 6, 2015). "Meet Loki, your closest-known prokaryote relative". LA Times . Retrieved May 9, 2015.
  11. 1 2 3 4 Nasir, Arshan; Kim, Kyung Mo; Caetano-Anollés, Gustavo (2015-08-01). "Lokiarchaeota: eukaryote-like missing links from microbial dark matter?". Trends in Microbiology. 23 (8): 448–450. doi:10.1016/j.tim.2015.06.001. ISSN   0966-842X. PMID   26112912.
  12. ↑ "GTDB release 09-RS220". Genome Taxonomy Database . Retrieved 10 May 2024.
  13. ↑ "ar53_r220.sp_label". Genome Taxonomy Database . Retrieved 10 May 2024.
  14. ↑ "Taxon History". Genome Taxonomy Database . Retrieved 10 May 2024.
  15. ↑ J.P. Euzéby. "Family: Lokiarchaeota, not assigned to family". List of Prokaryotic names with Standing in Nomenclature (LPSN). Retrieved 2023-06-20.
  16. ↑ Sayers; et al. "Candidatus Lokiarchaeota". National Center for Biotechnology Information (NCBI) taxonomy database. Retrieved 2023-06-20.
  17. ↑ Maximillan, Ludwig (27 December 2019). "Evolution: A revelatory relationship". Phys.org . Retrieved 28 December 2019.
  18. ↑ Embley, T. Martin; Martin, William (2006). "Eukaryotic evolution, changes and challenges". Nature . 440 (7084): 623–630. Bibcode:2006Natur.440..623E. doi:10.1038/nature04546. ISSN   0028-0836. PMID   16572163. S2CID   4396543.
  19. ↑ Lake, James A. (1988). "Origin of the eukaryotic nucleus determined by rate-invariant analysis of rRNA sequences". Nature . 331 (6152): 184–186. Bibcode:1988Natur.331..184L. doi:10.1038/331184a0. ISSN   0028-0836. PMID   3340165. S2CID   4368082.
  20. ↑ Guy, Lionel; Ettema, Thijs J.G. (2011). "The archaeal 'TACK' superphylum and the origin of eukaryotes". Trends in Microbiology . 19 (12): 580–587. doi:10.1016/j.tim.2011.09.002. ISSN   0966-842X. PMID   22018741.
  21. ↑ Wang, Minglei; Yafremava, Liudmila S.; Caetano-Anollés, Derek; Mittenthal, Jay E.; Caetano-Anollés, Gustavo (2007). "Reductive evolution of architectural repertoires in proteomes and the birth of the tripartite world". Genome Research . 17 (11): 1572–1585. doi:10.1101/gr.6454307. PMC   2045140 . PMID   17908824.
  22. ↑ Hahn, Jürgen; Haug, Pat (1986). "Traces of Archaebacteria in ancient sediments". Systematic and Applied Microbiology. 7 (Archaebacteria '85 Proceedings): 178–83. doi:10.1016/S0723-2020(86)80002-9.
  23. ↑ Knoll, Andrew H.; Javaux, E. J.; Hewitt, D.; Cohen, P. (29 June 2006). "Eukaryotic organisms in Proterozoic oceans". Philosophical Transactions of the Royal Society B . 361 (1470): 1023–38. doi:10.1098/rstb.2006.1843. PMC   1578724 . PMID   16754612.
  24. ↑ Zimmer, Carl (6 May 2015). "Under the Sea, a Missing Link in the Evolution of Complex Cells". New York Times . Retrieved 8 May 2015.
  25. ↑ Timmer, John (2019-08-07). "We've finally gotten a look at the microbe that might have been our ancestor". Ars Technica. Retrieved 2019-08-08.
  26. ↑ Zimmer, Carl (2020-01-15). "This Strange Microbe May Mark One of Life's Great Leaps". The New York Times . Retrieved 2020-01-15.
  27. ↑ Imachi, Hiroyuki; Nobu, Masaru K.; Kato, Shingo; Takaki, Yoshihiro; Miyazaki, Masayuki; Miyata, Makoto; Ogawara, Miyuki; Saito, Yumi; Sakai, Sanae; Tahara, Yuhei O.; Takano, Yoshinori; Tasumi, Eiji; Uematsu, Katsuyuki; Yoshimura, Toshihiro; Itoh, Takashi; Ohkuma, Moriya; Takai, Ken (5 July 2024). "Promethearchaeum syntrophicum gen. nov., sp. nov., an anaerobic, obligately syntrophic archaeon, the first isolate of the lineage 'Asgard' archaea, and proposal of the new archaeal phylum Promethearchaeota phyl. nov. and kingdom Promethearchaeati regn. nov". International Journal of Systematic and Evolutionary Microbiology. 74 (7). doi:10.1099/ijsem.0.006435.
  28. ↑ Rodrigues-Oliveira, Thiago; Wollweber, Florian; Ponce-Toledo, Rafael I.; Xu, Jingwei; Rittmann, Simon K.-M. R.; Klingl, Andreas; Pilhofer, Martin; Schleper, Christa (January 2023). "Actin cytoskeleton and complex cell architecture in an Asgard archaeon". Nature. 613 (7943): 332–339. doi:10.1038/s41586-022-05550-y. ISSN   1476-4687. PMC   9834061 . PMID   36544020.
  29. 1 2 3 Yin, Xiuran; Cai, Mingwei; Liu, Yang; Zhou, Guowei; Richter-Heitmann, Tim; Aromokeye, David A.; Kulkarni, Ajinkya C.; Nimzyk, Rolf; Cullhed, Henrik; Zhou, Zhichao; Pan, Jie (Mar 2021). "Subgroup level differences of physiological activities in marine Lokiarchaeota". The ISME Journal. 15 (3): 848–861. doi:10.1038/s41396-020-00818-5. ISSN   1751-7370. PMC   8027215 . PMID   33149207.
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