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Science Frontiers ONLINE No. 123: May-Jun 1999 |
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Nanobes
Get used to this term! Of course you know about microbes. Well, nanobes are also life forms but so much smaller than microbes that they deserve the prefix "nano" (for 10-9) rather than "micro" (for 10-6).
The smallest recognized bacteria, Myco plasma, lack cell walls and fall in the size range 150-200 nanometers. Nanobes are much smaller: 20-150 nanometers. But are nanobes really alive?
A drill core recently extracted from a stratum of sandstone 3 kilometers deep off the coast of Western Australia was found to be infected with miniscule filamentous structures. P. Uwins and her colleagues at the University of Queensland believe these structures ("nanobes") are alive. They appear to grow and have cell walls. But skeptics assert that some lifeless chemical structures also grow. Others suspect contamination of the sample as it was raised to the surface and handled.
Published photos of the nanobes look very much like the structures in the Martian meteorite ALH84001, which are claimed to be fossilized extraterrestrial bacteria. (SF#116)
(Dayton, Leigh; "Tiny Wonders," New Scientist, p. 13, March 27, 1999.)
Comment. R.L. Folk claims that so-called "nannobacteria" (100-400 nanometers) are ubiquitous on the earth. Few biologists believe that life forms can be this small, and they opt for lifeless mineral structures instead. (SF#110)
Do nanobes = nannobacteria? We don't know, but wish everyone would spell this prefix the same way!