National Geographicによれば、イングランドおよびウェールズの廃坑から鉛や亜鉛や砒素や銅を食べるミミズが見つかった:
[Heavy Metal-Eating "Superworms" Unearthed in U.K. > (2008/10/08) on National Geographic]

These hardcore heavy metal fans, unearthed at disused mining sites in England and Wales, devour lead, zinc, arsenic, and copper.


The earthworms excrete a slightly different version of the metals, making them easier for plants to suck up. Harvesting the plants would leave cleaner soil behind.


"These worms seem to be able to tolerate incredibly high concentrations of heavy metals, and the metals seem to be driving their evolution," said lead researcher Mark Hodson of the University of Reading in England.
"If you took an earthworm from the back of your garden and put it in these soils, it would die," Hodson said.
DNA analysis of lead-tolerant worms living at Cwmystwyth, Wales, show they belong to a newly evolved species that has yet to be named, he said.
Two other superworms, including an arsenic-munching population from southwest England, are also likely new to science, Hodson said.
"It's a good bet they are also different species, but we haven't categorically proved that," he said.

この研究のリーダーであるイングランドのUniversity of ReadingのMark Hodsonは次のようの述べた。「これらのミミズは信じられないくらい高濃度の重金属に耐えおり、その重金属が進化を推進しているようだ。もし、あなたの裏庭のミミズをとって、こららの土地へ持っていけば、すぐに死ぬだろう。
Hodson's team's investigation used x-rays to zap worms with intense light, allowing them to track metal particles a thousand times smaller than a grain of salt.


The findings suggest the arsenic-tolerant population produces a special protein that "wraps up the metal and keeps it inert and safe so it doesn't interact with the earthworms," Hodson said.
The lead-eating Welsh worms likewise use a protein to render the metal harmless inside their bodies, he added.
The toxicity of the metal particles once they have passed through the worms isn't yet known, since the protective protein wrappings will degrade over time, the study authors noted.

Peter Kille of the School of Biosciences at Cardiff University in Wales has also been tracking the metal-eating worms.

WalesのCardiff Universityの生物科学科のPeter Killeは重金属を食べるミミズを追いかけている。

And the superworms are perfect subjects for studying evolution in action, Kille added.
"What's really interesting is that each patch of high metal creates a unique evolutionary event," he said. The worms either develop new ways of dealing with the metals or find solutions similar to other populations.
"Each time it happens it's a localized event, and it allows us to study the processes of evolution that create the adaptation," he said.


なお、Peter Killeによれば、重金属を食べるミミズから排出された重金属塩を植物が吸収し、この植物を刈り取ることで汚染土壌の浄化をはかるのは工業的には効率が悪いらしい:
He said previous studies show it takes earthworms many years to improve polluted soils. While the new superworms should prove a useful tool, even they can't compete with industrial cleanup processes that take one to two years.


==>忘却からの帰還: ナイロンを食べるバクテリアは進化の証拠ではない by Dembski (2006/02/01)


posted by Kumicit at 2008/10/10 09:37 | Comment(0) | TrackBack(0) | News | このブログの読者になる | 更新情報をチェックする



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