Russians Find "New Bacteria" In Lake Vostok 147
tverbeek writes "Russian scientists believe they have found a new type of bacteria in the sub-glacial Lake Vostok. From the article: 'The samples obtained from the underground lake in May 2012 contained a bacteria which bore no resemblance to existing types, said Sergei Bulat of the genetics laboratory at the Saint Petersburg Institute of Nuclear Physics.
"After putting aside all possible elements of contamination, DNA was found that did not coincide with any of the well-known types in the global database," he said. "We are calling this life form unclassified and unidentified," he added.'"
Re:in soviet russia we bacteria you (Score:4, Informative)
I think you meant to say, "In Soviet Russia, bacteria finds you!"
Re:"life form unclassified" (Score:5, Informative)
Re:Hope this doesn't go the way of arsenic life (Score:5, Informative)
Re:"life form unclassified" (Score:5, Informative)
Based on circumstantial evidence (another species found nearby), the bacterium is a thermophile that depends on geothermal heat for warmth. Because of the way thermophiles evolve, it is pretty much certain that the proteins in this species are non-functional at colder temperatures; the samples collected were either dead or in a deep state of antifreeze-clogged hibernation.
It's also 700 million years (or more!) behind on immune defences, which means it's vulnerable to everything from the toxins that all plants constantly secret all the time to the macrophages in our blood. The immune game is a Red Queen scenario [wikipedia.org]—either a pathogen is at the forefront of innovation, or it's susceptible to the most basic form of detection.
The only environment this could possibly intrude upon is one comparable to its own—maybe a heat vent in another frozen lake. Even if it wasn't a thermophile, it would be dead meat on the surface because of bacteriophages (viruses). To add insult to injury, as far as we know this bacterium has no competitors and is not part of a community, making it highly unlikely that it has any competition or any defences.
Gene retention is like lactose tolerance—if you don't use it, you'll lose it. For animals, this typically takes a few thousand years. For bacteria it happens much more quickly. They're very simple organisms, and they're very good at adapting, but only if they've had time to adjust to their new setting. In this case, every single one of its (probably several thousand) genes has spent millions of years being fine-tuned for the most boring environment possible. It has absolutely no hope.
Re:uh-oh. (Score:5, Informative)
More like Nuclear Chemistry if you ask me. Where else is the Chromosomal DNA found?
Thank God I, Mr. Pedantic, got here just in time, to ruin your joke with unsolicited facts: bacteria do not have a cell nucleus.
Re:"life form unclassified" (Score:4, Informative)
If you scrutinize the article, Sergei Bulat is quoted as saying the organism has less than 86% "DNA similarity" to other species. Taken at face value, this means that the entire genome of the bacterium is less than 86% similar, which (a) requires isolating it first and months of work, and (b) would not be impressive at all, since Escherichia coli genomes have much higher variety.
He then goes on to say that 90% is the threshold beyond which a species is considered completely unknown. This is an appropriate figure to give when discussing the evolution of one particular gene called the 16S ribosomal RNA, which is very important to cellular function and changes very slowly. It's also a standard test to use in the analysis of bacterial communities, and one of the core tools in metagenomics, because it's very unique to species and hence an excellent fingerprint. If you need citations to back up this claim, I can give you oceans of them. This is my actual day job.
So how divergent is 100 – 86 = 14%? This article [pnas.org] references a standard 1% every 50 million years. 14 * 50 = 700 million years. This figure is quite possibly too low in this case, since evolution has a non-linear effect on sequences—eventually mutations flip multiple times, and so large numbers of changes get masked. This rate of change can be sped to 2% every 50 million years if the environment is exceptionally rich and predator-free, like inside certain cells in insects—but that's largely because the host cell is available to a degree to provide nutrients, so proper ribosomal function isn't as important.
This doesn't mean necessarily that this species has been completely isolated the whole time, just that we haven't found any surviving links. If it previously existed in a cave system, for example, that entire community could have been wiped out when Antarctica froze, leaving behind only a stub of organisms that were sheltered by the heat (and food chain) emanating from the thermal vent. Cave ecosystems often contain numerous species that have adapted so tightly to their niche that they are unable to survive outside.
That being said, this expedition has already made crap up for publicity stunts [guardian.co.uk]. As this hasn't been published in any journals yet and was instead released to the press first, it's entirely possible that no such species exists. Nevertheless, the claim of 14% divergence will be interpreted by other experts as more than half a billion years.