View source for Nanobe

{{Short description|Rock and sediment microstructure}}{{use dmy dates|date=July 2023}}
[[File:ALH84001 structures.jpg|thumb|upright=1.5| Structures found in the [[Allan Hills 84001|ALH84001 meteorite]] are similar to the structures found in nanobes]]
{{distinguish|Nanobacteria|Ultramicrobacteria}}

A '''nanobe''' ({{IPAc-en|ˈ|n|æ|n|oʊ|b|,_|ˈ|n|eɪ|n|oʊ|b}})<ref>{{cite dictionary |title=nanobe |dictionary=[[Lexico]] U.S. English Dictionary |publisher=[[Oxford University Press]] |url=http://www.lexico.com/en/definition/nanobe |url-status=dead |archive-url=https://web.archive.org/web/20190731214907/https://www.lexico.com/en/definition/nanobe |archive-date=July 31, 2019}}</ref> is a tiny filamental [[structure]] first found in some [[Rock (geology)|rocks]] and [[sediment]]s.  Some scientists [[Hypothesis|hypothesize]] that nanobes are the smallest form of [[life]], {{sfrac|1| 10 }} the size of the [[Mycoplasma|smallest known bacteria]].<ref name=Nanjundiah2000>{{cite journal | last = Nanjundiah | first =  V. | year = 2000 | title = The smallest form of life yet? | journal = Journal of Biosciences | volume = 25 | issue = 1 | pages = 9–10 | url = http://eprints.iisc.ernet.in/archive/00001799/01/25smallest25(1)-9to10mar2000.pdf | doi = 10.1007/BF02985175 | pmid = 10824192 | s2cid = 29030837 }}</ref>

No conclusive evidence exists that these structures are, or are not, living organisms, so their classification is controversial.

The 1996 discovery of nanobes was published in 1998<ref name=nanobepaper1998>{{cite journal |author1=Uwins, Philippa J.R. |display-authors=etal |year=1998 |title=Novel nano-organisms from Australian sandstones |journal=[[American Mineralogist]] | volume=83 |issue=11-12 |pages=1541–1550, Part&nbsp;2 |doi=10.2138/am-1998-11-1242
|bibcode=1998AmMin..83.1541U |url=http://www.microscopy-uk.org.uk/nanobes/nanobes.pdf }}</ref> by Uwins ''et al.'',<ref>{{cite news |title=Nanobes: About Philippa Uwins and the discovery team |website=microscopy-uk.org.uk |url=http://www.microscopy-uk.org.uk/nanobes/nanophil.html }}</ref> from the [[University of Queensland]], [[Australia]]. They were found growing from rock samples (both full-diameter and sidewall cores) of [[Jurassic]] and [[Triassic]] sandstones, originally retrieved from an unspecified number of [[oil exploration]] wells off Australia's west coast. Depths of retrieval were between {{convert|3400|m|mi|1}} and {{convert|5100|m|mi|1}} below the sea bed. While Uwins ''et al.''<ref name=nanobepaper1998/> present assertions against it, they do not exclude the possibility that the nanobes are from a surface contaminant, not from the rock units cited.

The smallest are just 20 [[Nanometre|nanometers]] in diameter. Some researchers believe that these structures are [[crystal]] growths, but the staining of these structures with dyes that bind to [[DNA]] might indicate that they are living organisms.<ref>{{cite web |title=Nanobacteria and nanobes – Are they alive? |website=Carlton.edu |series=Science Education Resource Center |publisher=[[Carlton College]] |place=Northfield, MN  |url=http://serc.carleton.edu/microbelife/topics/nanobes/index.html}}</ref>

They are similar to the structures found in [[ALH84001]], a [[Mars meteorite]] found in the [[Antarctica|Antarctic]]. A 2022 study concluded that ALH84001 did not contain Martian life; the discovered organic molecules were found to be associated with abiotic processes (ie, "serpentinization and carbonation reactions that occurred during the aqueous alteration of basalt rock by hydrothermal fluids") produced on the very early Mars four billion years ago instead.<ref>{{cite news |last=Dunn |first=Marcia |date=13 January 2022 |title=Study nixes Mars life in meteorite found in Antarctica |agency=[[Associated Press]] |website=apnews.com |url=https://apnews.com/article/space-exploration-science-business-planets-mars-33dc55ce0ebced0b65322b03ae06feda |access-date=13 January 2022}}</ref><ref name=SCI-20220113>{{cite journal |author=Steele, A. |display-authors=et al. |title=Organic synthesis associated with serpentinization and carbonation on early Mars |date=13 January 2022 |journal=[[Science (journal)|Science]] |volume=375 |issue=6577 |pages=172–177 |doi=10.1126/science.abg7905 |pmid=35025630 |bibcode=2022Sci...375..172S |s2cid=245933224 <!-- redundant: same as doi --- |url=https://www.science.org/doi/epdf/10.1126/science.abg7905 |access-date=15 January 2022 --> }}</ref>

Nanobes are similar in size to [[nanobacteria]], which are also structures that had been proposed to be extremely small living organisms. However, these two should not be confused: Nanobacteria were thought to be cellular organisms, while nanobes are hypothesized (by some) to be a previously unknown form of life or [[protocell]]s.{{Citation needed|date=March 2014}}

== Claims ==
* It is a living organism (contains [[DNA]] or some analogue, and reproduces).
* Has a [[Morphology (biology)|morphology]] similar to [[Actinomycetes]] and [[fungi]].
* Nanobes are about 20 [[Nanometre|nm]] in diameter, which may be too small to contain the basic elements for an organism to exist (DNA, [[ribosome]]s, etc.), suggesting that if they grow and reproduce they would need to do so in an unconventional way.
* The [[Martian meteorite]] [[ALH84001]], discovered in 1984 in the [[Antarctic]], contained similar tubular structures which some [[astrobiology|astrobiologists]] suggested could be evidence of life at an earlier time on [[Mars]].<ref>{{cite journal |author=McSween, H. Y. |title=Evidence for life in a martian meteorite? |journal=GSA Today |volume=7 |issue=7 |pages=1–7 |year=1997 |pmid=11541665}}</ref>

==Responses==
A review in ''Microbes and Environments''<ref name=Velimirov2001>{{cite journal | author = Velimirov, B. | year = 2001 | title = Nanobacteria, Ultramicrobacteria and Starvation Forms: A Search for the Smallest Metabolizing Bacterium | journal = Microbes and Environments | volume = 16 | issue = 2 | pages = 67–77 | doi = 10.1264/jsme2.2001.67 | doi-access = free | url = https://www.jstage.jst.go.jp/article/jsme2/16/2/16_2_67/_pdf | access-date = 2008-06-23 }}</ref> of the various ultra-small forms of proposed life states that the main criticism of nanobes is that they appear too small to contain the biochemical machinery needed to sustain life. The review also states that there is no evidence that nanobes are organisms in themselves and not fragments of larger organisms.

Tony Taylor was one of the authors of the original nanobe paper.<ref name=nanobepaper1998/> He argues that the conspicuous lack of [[Phosphorus#Biological_role|phosphorus]] in the X-ray spectroscopy data and the failure to find DNA using various DNA amplification techniques demonstrates that nanobes do not have any DNA or [[RNA]]. He also argues that they may have a completely different mechanism for heredity, which would account for many of their unusual chemical and physical properties.

== Size scale context ==
::{|
 |+ {{big|'''Sizes of micro-organisms and infectious agents'''}}
 ! Agent  !!  Description  !! Size<br/>([[nanometer|nm]])
 |-
 | [[Megaklothovirus horridgei]] || largest known [[virus]] ||align=right| 3,900&nbsp;nm 
 |-
 | [[Pandoravirus]]&nbsp; || one of the largest known [[virus]]es ||align=right| 1,000&nbsp;nm 
 |-
 | [[Nanoarchaeum]]&nbsp; || smallest known [[archaea|archaeum]] ||align=right| &nbsp;400&nbsp;nm 
 |-
 | [[Mycoplasma]] || smallest known [[bacteria|bacterium]] ||align=right| 300&nbsp;nm 
 |-
 | [[Nanobacteria]] || former proposed class of lifeforms smaller than bacteria ||align=right| {{nobr|< 200 nm}} 
 |-
 | [[Parvovirus]] || smallest known [[virus]]es ||align=right| 18–28&nbsp;nm 
 |-
 | '''Nanobes''' || hypothetical lifeforms smaller than viruses ||align=right| ≈20&nbsp;nm 
 |-
 | [[Prion]] || smallest known infectious agent ([[protein]]) ||align=right| ≈10&nbsp;nm 
 |}

== See also ==
* [[Smallest organisms]]
* [[Protocell]]

== References ==
{{reflist|25em}}

== External links ==
* {{cite AV media |title=Color photo of a nanobe colony |medium=photo |website=microscopy-uk.org.uk |url=http://www.microscopy-uk.org.uk/nanobes/nano35000y.jpg}}
* {{cite web |title=Definition of nanobe |website=microscopy-uk.org.uk |url=http://www.daviddarling.info/encyclopedia/N/nanobe.html}}
* {{cite web |title=Introduction to nanobes |website=microscopy-uk.org.uk |url=http://www.microscopy-uk.org.uk/index.html?http://www.microscopy-uk.org.uk/nanobes/nanobes.html}}<!---should probably be incorporated in article and deleted under [[WP:EL]]-->
* {{cite web |title=Nanobe images and links |website=microscopy-uk.org.uk |url=http://www.microscopy-uk.org.uk/index.html?http://www.microscopy-uk.org.uk/nanobes/nanoimages.html}}
* {{cite web |title=Interview of Philippa Uwins |type=transcript |series=7.30 Report |publisher=[[Australian Broadcasting Corporation]] |url=http://www.abc.net.au/7.30/stories/s26212.htm}}
* {{cite conference |conference=Size Limits of Very Small Microorganisms |title=Workshop |publisher=U.S. [[National Academies of Sciences]] |url=http://www7.nationalacademies.org/ssb/nanomenu.html |access-date=17 October 2008 |archive-date=18 March 2009 |archive-url=https://web.archive.org/web/20090318074659/http://www7.nationalacademies.org/ssb/nanomenu.html |url-status=dead }}
* {{cite news |first=Jenny |last=Hogan |date=22 May 2004 |title=Nanobes: A new form of life? |magazine=Astrobiology Magazine  |url=http://www.astrobio.net/news/article983.html}}
* {{cite news |author=Broad, William J. |date=January 18, 2000 |title=Scientists find smallest form of life, if it lives |newspaper=[[The New York Times]] |url=https://www.nytimes.com/2000/01/18/science/scientists-find-smallest-form-of-life-if-it-lives.html?sec=&spon=&pagewanted=1 }}
* {{cite news |title=How small can life be? |website=nai.nasa.gov |series=NAI news |publisher=[[National Aeronautics and Space Administration]] |url=http://nai.nasa.gov/news_stories/news_print.cfm?ID=137 |url-status=dead <!-- presumed --> |archive-url=https://web.archive.org/web/20090614004824/http://nai.nasa.gov/news_stories/news_print.cfm?ID=137 |archive-date=2009-06-14}} via {{cite web |title=NAI news |department=Astrobiology |url=http://astrobiology.nasa.gov/nai/}}

{{Self-replicating organic structures}}
{{Organisms et al.}}

[[Category:Microbiology]]
[[Category:Hypothetical life forms]]