Crenarchaeota

The Crenarchaeota (also known as Crenarchaea or eocytes) are archaea that have been classified as a phylum of the Archaea domain.[1][2][3] Initially, the Crenarchaeota were thought to be sulfur-dependent extremophiles but recent studies have identified characteristic Crenarchaeota environmental rRNA indicating the organisms may be the most abundant archaea in the marine environment.[4] Originally, they were separated from the other archaea based on rRNA sequences; other physiological features, such as lack of histones, have supported this division, although some crenarchaea were found to have histones.[5] Until recently all cultured Crenarchaea had been thermophilic or hyperthermophilic organisms, some of which have the ability to grow at up to 113 °C.[6] These organisms stain Gram negative and are morphologically diverse having rod, cocci, filamentous and oddly shaped cells.[7]

Crenarchaeota
Archaea Sulfolobus infected with specific virus STSV-1.
Scientific classification
Domain:
Archaea
Kingdom:
Proteoarchaeota
Superphylum:
TACK
Phylum:
"Crenarchaeota"
Class
Synonyms
  • Eocyta
  • Eocytes
  • Crenarchaeota Garrity and Holt 2002
  • not Crenarchaeota Cavalier-Smith 2002

Sulfolobus

One of the best characterized members of the Crenarcheota is Sulfolobus solfataricus. This organism was originally isolated from geothermally heated sulfuric springs in Italy, and grows at 80 °C and pH of 2–4.[8] Since its initial characterization by Wolfram Zillig, a pioneer in thermophile and archaean research, similar species in the same genus have been found around the world. Unlike the vast majority of cultured thermophiles, Sulfolobus grows aerobically and chemoorganotrophically (gaining its energy from organic sources such as sugars). These factors allow a much easier growth under laboratory conditions than anaerobic organisms and have led to Sulfolobus becoming a model organism for the study of hyperthermophiles and a large group of diverse viruses that replicate within them.

Marine species

Beginning in 1992, data were published that reported sequences of genes belonging to the Crenarchaea in marine environments.[9],[10] Since then, analysis of the abundant lipids from the membranes of Crenarchaea taken from the open ocean have been used to determine the concentration of these “low temperature Crenarchaea” (See TEX-86). Based on these measurements of their signature lipids, Crenarchaea are thought to be very abundant and one of the main contributors to the fixation of carbon . DNA sequences from Crenarchaea have also been found in soil and freshwater environments, suggesting that this phylum is ubiquitous to most environments.[11]

In 2005, evidence of the first cultured “low temperature Crenarchaea” was published. Named Nitrosopumilus maritimus, it is an ammonia-oxidizing organism isolated from a marine aquarium tank and grown at 28 °C.[12]

Eocyte hypothesis[13]

Eocyte hypothesis

The eocyte hypothesis proposed in the 1980s by James Lake suggests that eukaryotes emerged within the prokaryotic eocytes.[14]

One possible piece of evidence supporting a close relationship between Crenarchaea and eukaryotes is the presence of a homolog of the RNA polymerase subunit Rbp-8 in Crenarchea but not Euryarchaea[15]

See also

References
  1. See the NCBI webpage on Crenarchaeota
  2. C.Michael Hogan. 2010. Archaea. eds. E.Monosson & C.Cleveland, Encyclopedia of Earth. National Council for Science and the Environment, Washington DC.
  3. Data extracted from the "NCBI taxonomy resources". National Center for Biotechnology Information. Retrieved 2007-03-19.
  4. Madigan M; Martinko J, eds. (2005). Brock Biology of Microorganisms (11th ed.). Prentice Hall. ISBN 978-0-13-144329-7.
  5. Cubonova L, Sandman K, Hallam SJ, Delong EF, Reeve JN (2005). "Histones in Crenarchaea". Journal of Bacteriology. 187 (15): 5482–5485. doi:10.1128/JB.187.15.5482-5485.2005. PMC 1196040. PMID 16030242.
  6. Blochl E, Rachel R, Burggraf S, Hafenbradl D, Jannasch HW, Stetter KO (1997). "Pyrolobus fumarii, gen. and sp. nov., represents a novel group of archaea, extending the upper temperature limit for life to 113 °C". Extremophiles. 1 (1): 14–21. doi:10.1007/s007920050010. PMID 9680332. S2CID 29789667.
  7. Garrity GM, Boone DR, eds. (2001). Bergey's Manual of Systematic Bacteriology Volume 1: The Archaea and the Deeply Branching and Phototrophic Bacteria (2nd ed.). Springer. ISBN 978-0-387-98771-2.
  8. Zillig W, Stetter KO, Wunderl S, Schulz W, Priess H, Scholz I (1980). "The Sulfolobus-"Caldariellard" group: Taxonomy on the basis of the structure of DNA-dependent RNA polymerases". Arch. Microbiol. 125 (3): 259–269. doi:10.1007/BF00446886. S2CID 5805400.
  9. Fuhrman JA, McCallum K, Davis AA (1992). "Novel major archaebacterial group from marine plankton". Nature. 356 (6365): 148–9. Bibcode:1992Natur.356..148F. doi:10.1038/356148a0. PMID 1545865. S2CID 4342208.
  10. DeLong EF (1992). "Archaea in coastal marine environments". Proc Natl Acad Sci USA. 89 (12): 5685–9. Bibcode:1992PNAS...89.5685D. doi:10.1073/pnas.89.12.5685. PMC 49357. PMID 1608980.
  11. Barns SM, Delwiche CF, Palmer JD, Pace NR (1996). "Perspectives on archaeal diversity, thermophily and monophyly from environmental rRNA sequences". Proc Natl Acad Sci USA. 93 (17): 9188–93. Bibcode:1996PNAS...93.9188B. doi:10.1073/pnas.93.17.9188. PMC 38617. PMID 8799176.
  12. Könneke M, Bernhard AE, de la Torre JR, Walker CB, Waterbury JB, Stahl DA (2005). "Isolation of an autotrophic ammonia-oxidizing marine archaeon". Nature. 437 (7058): 543–6. Bibcode:2005Natur.437..543K. doi:10.1038/nature03911. PMID 16177789. S2CID 4340386.
  13. Cox, C. J.; Foster, P. G.; Hirt, R. P.; Harris, S. R.; Embley, T. M. (2008). "The archaebacterial origin of eukaryotes". Proc Natl Acad Sci USA. 105 (51): 20356–61. Bibcode:2008PNAS..10520356C. doi:10.1073/pnas.0810647105. PMC 2629343. PMID 19073919.
  14. (UCLA) The origin of the nucleus and the tree of life Archived 2003-02-07 at Archive.today
  15. Kwapisz, M; Beckouët, F; Thuriaux, P (2008). "Early evolution of eukaryotic DNA-dependent RNA polymerases". Trends Genet. 24 (5): 211–5. doi:10.1016/j.tig.2008.02.002. PMID 18384908.

Further reading

Scientific journals

Scientific books

Scientific databases

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