Nanobe
A nanobe (
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
The smallest are just 20 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.[5]
They are similar to the structures found in
Nanobes are similar in size to
Claims
- It is a living organism (contains DNA or some analogue, and reproduces).
- Has a fungi.
- Nanobes are about 20 nm in diameter, which may be too small to contain the basic elements for an organism to exist (DNA, ribosomes, etc.), suggesting that if they grow and reproduce they would need to do so in an unconventional way.
- The ALH84001, discovered in 1984 in the Antarctic, contained similar tubular structures which some astrobiologists suggested could be evidence of life at an earlier time on Mars.[8]
Responses
A review in Microbes and Environments[9] 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.[3] He argues that the conspicuous lack of 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
Sizes of micro-organisms and infectious agents Agent Description Size
(nm)Pithovirus largest known virus 1,500 nm Pandoravirus one of the largest known viruses 1,000 nm Nanoarchaeumsmallest known archaeum 400 nm Mycoplasma smallest known bacterium 300 nm Nanobacteriaformer proposed class of lifeforms smaller than bacteria < 200 nm Parvovirussmallest known viruses 18–28 nm Nanobes hypothetical lifeforms smaller than viruses ≈20 nm Prion smallest known infectious agent (protein) ≈10 nm
See also
References
- ^ "nanobe". Lexico U.S. English Dictionary. Oxford University Press. Archived from the original on 31 July 2019.
- S2CID 29030837.
- ^ .
- ^ "Nanobes: About Philippa Uwins and the discovery team". microscopy-uk.org.uk.
- Carlton College.
- ^ Dunn, Marcia (13 January 2022). "Study nixes Mars life in meteorite found in Antarctica". apnews.com. Associated Press. Retrieved 13 January 2022.
- S2CID 245933224.
- PMID 11541665.
- . Retrieved 23 June 2008.
External links
- Color photo of a nanobe colony. microscopy-uk.org.uk (photo).
- "Definition of nanobe". microscopy-uk.org.uk.
- "Introduction to nanobes". microscopy-uk.org.uk.
- "Nanobe images and links". microscopy-uk.org.uk.
- "Interview of Philippa Uwins" (transcript). 7.30 Report. Australian Broadcasting Corporation.
- Workshop. Size Limits of Very Small Microorganisms. U.S. National Academies of Sciences.
- Hogan, Jenny (22 May 2004). "Nanobes: A new form of life?". Astrobiology Magazine.
- Broad, William J. (18 January 2000). "Scientists find smallest form of life, if it lives". The New York Times.
- "How small can life be?". nai.nasa.gov. NAI news. National Aeronautics and Space Administration. Archived from the original on 14 June 2009. via "NAI news". Astrobiology.