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wtf_nature
Arsenic & Old Lakes
A paper just released by Science, and covered in a NASA press release, is causing something of a kerfluffle in the blogosphere. It's about a newly-discovered strain of bacteria that, as far as its discoverers can tell, is substituting arsenic compounds for the phosphates that all previously known lifeforms depend on.
Alas, however, these arsenate lifeforms were not found on Uranus.
( Sorry )
Anyway, the germ in question is strain GFAJ-1 of the Halomonadaceae, found by Dr. Felise Wolfe-Simon and her colleagues as part of ongoing research into the extremophile bacteria and archeans of Mono Lake in California. Not a pleasant home for most lifeforms, given the high salinity and alarmingly high alkalinity and levels of arsenic. Extremophiles are constantly surprising us by getting along nicely in places, and on diets, that were previously considered impossible for life - see here, for example, of a deep earth bacterium that exploits uranium to make fuel. Perhaps imagine normal lifeforms in the roles of King Arthur and his knights, and the extremophiles as the French taunters, and you might have a good idea of the kind of mockery extremophiles make of established biology.
Phosphorus is one of the 6 elements previously considered essential for life, at least in all the species we knew about up till now. Arsenic is adjacent to phosphorus on the periodic table, and behaves similarly. But not similarly enough, since once organisms try to use it to make biochemicals such as adenosine triphosphate - the power supply for all known cells - the whole kit and kaboodle falls apart. Hence, of course, arsenic's notorious lethality in sufficient doses ( just ask Napoleon. Oh, you can't, he's dead. I rest my case ). Not a good choice for food colouring ( too late ). Phosphates also form part of the backbone of DNA. Pretty damn important stuff.
But GFAJ-1, when grown on a high-arsenic diet as deficient in phosphorus as could be provided, not only chugged along reproducing anyway, but is as far as the current results indicate, is incorporating the arsenate compounds into their own DNA, and happily switching back to phosphate again just as readily.
This is going to be a story worth watching, and I look forward to Dr. Wolfe-Simon's further research.
Alas, however, these arsenate lifeforms were not found on Uranus.
( Sorry )
Anyway, the germ in question is strain GFAJ-1 of the Halomonadaceae, found by Dr. Felise Wolfe-Simon and her colleagues as part of ongoing research into the extremophile bacteria and archeans of Mono Lake in California. Not a pleasant home for most lifeforms, given the high salinity and alarmingly high alkalinity and levels of arsenic. Extremophiles are constantly surprising us by getting along nicely in places, and on diets, that were previously considered impossible for life - see here, for example, of a deep earth bacterium that exploits uranium to make fuel. Perhaps imagine normal lifeforms in the roles of King Arthur and his knights, and the extremophiles as the French taunters, and you might have a good idea of the kind of mockery extremophiles make of established biology.
Phosphorus is one of the 6 elements previously considered essential for life, at least in all the species we knew about up till now. Arsenic is adjacent to phosphorus on the periodic table, and behaves similarly. But not similarly enough, since once organisms try to use it to make biochemicals such as adenosine triphosphate - the power supply for all known cells - the whole kit and kaboodle falls apart. Hence, of course, arsenic's notorious lethality in sufficient doses ( just ask Napoleon. Oh, you can't, he's dead. I rest my case ). Not a good choice for food colouring ( too late ). Phosphates also form part of the backbone of DNA. Pretty damn important stuff.
But GFAJ-1, when grown on a high-arsenic diet as deficient in phosphorus as could be provided, not only chugged along reproducing anyway, but is as far as the current results indicate, is incorporating the arsenate compounds into their own DNA, and happily switching back to phosphate again just as readily.
This is going to be a story worth watching, and I look forward to Dr. Wolfe-Simon's further research.