16 | NewScientist | 28 April 2012

Clues to aspirin’s anti-cancer powers

ASPIRIN seems to help keep cancer away. A new study may go some way to explain why.

To investigate the drug’s unexpected side effects, Grahame Hardie at the University of Dundee, UK, applied salicylate – produced by the breakdown of aspirin – to cultured human kidney cells. He found that the drug activated AMPK, an enzyme involved in cell growth and metabolism that has been shown to play a role in cancer.

Salicylate, found in willow bark, has been used as a medicine for thousands of years. “This is an ancient herbal remedy which has probably always been part of the human diet,” says Hardie. “But we’re still finding out how it works.”

Co-author Greg Steinberg of McMaster University in Hamilton, Ontario, Canada, tested high doses of salicylate on mice. Those mice engineered to lack AMPK did not experience the same metabolic effects from salicylate as mice with AMPK (Science, DOI: 10.1126/science.1215327).

The next step will be to conduct studies in mice to see whether AMPK is important in mediating an anti-cancer effect.

Move over graphene, silicene is the new kid on the blockAFTER only a few years basking in the limelight, wonder material graphene has a competitor in the shape of silicene. For the first time, silicon has been turned into a sheet just one atom thick. Silicene is thought to have similar electronic properties to graphene but ought to be more compatible with silicon-based electronic devices.

Patrick Vogt of Berlin’s Technical University in Germany, and colleagues at Aix-Marseille University in France created silicene by condensing silicon vapour onto a silver plate to form

a single layer of atoms. They then measured the optical, chemical and electronic properties of the layer, showing it closely matched those predicted by theory (Physical Review Letters, DOI: 10.1103/PhysRevLett.108.155501).

Silicene may turn out to be a better bet than graphene for smaller and cheaper electronic devices because it can be integrated more easily into silicon chip production lines.

In 2010, another Aix-Marseille group led by Bernard Aufray attempted create silicene using

BLOODSUCKERS they may be, but who’s to say they can’t be useful too? Leeches store blood from their most recent meal for months, betraying the identity of their prey to those who care to look – which could help find and count endangered species.

Tom Gilbert of the University of Copenhagen in Denmark fed goat blood to leeches in the lab, and found that some of the goat DNA stuck around for more than four months (Current Biology, DOI: 10.1016/j.cub.2012.02.058). Next, his team collected 25 leeches from a remote tropical forest in Vietnam which

is rich in rare but shy species. Four leeches yielded DNA from

a rare striped rabbit, one from a rare muntjac, six from a rare badger and three from a rare goat. The team says the rabbit’s presence in the sampled area has been suspected since 1996 but 2000 nights of camera surveillance couldn’t confirm it. The badger and goat DNA is the first confirmation that they live in the area.

Gilbert says that at $5 to $10 per sample, the method is cheaper than alternatives. And as a bonus, leeches do not need to be sought out. “They look for you,” says Gilbert.

Leeches help in hunt for rare species

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a similar approach but failed to present convincing evidence that it was present. Michel Houssa of the Catholic University of Leuven (KUL) in Belgium, who was not involved in the new work, says: “In my opinion, this is the first compelling evidence that silicene can be grown on silver.”

He says an important challenge now will be to grow silicene on insulating substrates to learn more about its electrical properties and understand how they can be exploited to build future electronic devices.

Methane leaks out as Arctic ice cracks

AS ARCTIC sea ice breaks apart, huge amounts of methane could be released into the atmosphere from the cold waters beneath – leading to even faster Arctic warming.

Eric Kort of the Jet Propulsion Laboratory in Pasadena, California, and his colleagues flew over the Arctic Ocean in 2009 and 2010 as part of a project to systematically map greenhouse gas levels. They found patches of methane in remote regions, far from known methane sources such as melting permafrost (Nature Geoscience, DOI: 10.1038/ngeo1452).

The methane may have been made by marine bacteria trying to survive in waters that don’t have many nutrients in the form of nitrates.

Kort detected methane above cracks in the sea ice and above places where the ice had broken up. This could be because methane only escapes from agitated water, says Ellen Damm of the Alfred Wegener Institute for Polar and Marine Research in Bremerhaven, Germany. This agitation is most likely to occur when autumn sets in and ice crystals start forming in the water, creating turbulence.

It is too early to say how significant this effect will be on climate warming, says Euan Nisbet, an earth scientist at Royal Holloway, University of London.

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