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DOSING livestock with antibiotics can be bad for farmers’ health. A strain of MRSA that causes skin infections and sepsis in farm workers evolved its resistance to antibiotics inside farm animals.

The ST398 strain of MRSA first appeared in 2003 and is prevalent in US livestock. Humans who pick it up from animals can become dangerously ill, but it cannot yet spread from human to human.

A team led by Paul Keim of the Translational Genomics Research Institute in Phoenix, Arizona, sequenced the genomes of 88 closely related strains of Staphylococcus aureus, the bug that can become MRSA. Their findings suggest that

ST398 was originally a harmless strain living in humans, which migrated into livestock where it acquired antibiotic resistance (mBio, in press).

Superbug’s source For some time microbiologists have been concerned that giving large amounts of antibiotics to livestock can promote antibiotic resistance. Keim’s study provides a powerful example, says Ross Fitzgerald of the University of Edinburgh, UK.

Earlier this year the US Food and Drug Administration announced new restrictions on using preventive antibiotics in livestock, but the rules cover a small subset of drugs constituting just 0.2 per cent of antibiotics used on farms. As a result they are not expected to do much good.

Invasive ultrasoundWOMEN seeking abortions in Virginia may soon have to undergo an invasive ultrasound scan first – a move supposedly designed to inform the women but which some claim aims to stigmatise them instead.

If a new senate bill is passed in Virginia this week, ultrasound would be performed in order to “more accurately determine gestation age”. The women would then be offered the chance to see the image “to make an informed choice”.

To get a clear image of the fetus in early pregnancy, ultrasound scans tend to be performed trans-vaginally – a procedure that involves inserting a probe into the vagina.

Tracy Weitz at the University of California in San Francisco agrees that it is “critical to assess gestational age before an abortion”, but says that the bill assumes women don’t know what they’re doing. “Women are not choosing abortions because they do not know what is in their uterus but because of the conditions of their lives,” she says.

Secret mindJOHN NASH’S mind is even more exquisite than we thought. The Nobel laureate, famous for both his work in game theory and his schizophrenia – as portrayed in the book and film A Beautiful Mind – had ideas about cryptography and complexity decades before their time.

The revelations come in recently declassified letters exchanged between the US National Security Agency and Nash in 1955. In them,

–Look for life underground–

–Also keen on P vs NP–

Atacama’s buried oasisIT’S the driest desert in the world, but Chile’s Atacama is far from lifeless. An oasis of microbes has been found 2 metres below its surface using an instrument that could one day hunt for life on Mars.

Victor Parro of the Centre for Astrobiology in Madrid, Spain, and colleagues discovered the thriving community of bacteria, archaea, DNA, and other molecules associated with life. “This is a kind of oasis in the Atacama,” Parro says. The microbes, along with similar life forms found in the top 30 centimetres of the surface, survive thanks to thin films of water that form on salt crystals in the soil (Astrobiology, DOI: 10.1089/ast.2011.0654).

The water may have been pulled from the atmosphere, or from

subsurface aquifers. “For these microbes, the most important thing is to get some water,” Parro says.

The discovery was made using an instrument called SOLID (Signs of Life Detector), which searches for molecules associated with life – such as sugars and DNA – with the help of 300 antibodies that bind to the molecules. When the antibody finds its target molecule it grabs hold of it and a special camera photographs the linked pair. Pregnancy tests, which look for a hormone associated with the early stages of pregnancy, use a similar strategy.

An instrument that would use the technique to hunt for fossilised life may fly on the European Space Agency’s ExoMars rover mission in 2018.

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“The bug was harmless until it migrated to livestock where it acquired antibiotic resistance”

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25 February 2012 | NewScientist | 5

he describes an encryption technique based on an idea that underlies modern cryptography, but wasn’t developed publicly until the mid-1970s. He also distinguishes between functions that run in polynomial time and in exponential time. This distinction is related to a major and still-unsolved problem in computing known as P versus NP: a proof will win a $1 million prize.

“This is not a letter that you would have expected to have been written in the ’50s,” says Lance Fortnow, a complexity theorist at Northwestern University in Evanston, Illinois.

Fat-fighting drugTHE makers of an appetite-sapping drug will this week take a second bite at the cherry of regulatory approval.

Two years ago the US Food and Drug Administration rejected Qnexa because it raises risks of heart complications and possible damage to fetuses in pregnant women. Vivus of Mountain View, California, which makes the drug, argues that given the current obesity epidemic, the risks are outweighed by the benefits. It adds that Qnexa eases the effects of diabetes and high blood pressure.

In a background brief to the panel that will, by 17 April, decide Qnexa’s fate, FDA researchers direct the panellists to focus on whether the risks are manageable.

The only treatment that matches the weight loss seen with Qnexa is stomach-stapling surgery, which carries significant risks and cannot realistically be offered to the vast numbers of people who are obese, says Nick Finer of University College London.

Carel Le Roux of Imperial College London urges approval of Qnexa, but only for use in obese people who already have other complications, such as diabetes. “It won’t make them thin or happy, but it could make them healthier,” he says.

A frack assessmentDON’T blame fracking for the environmental problems associated with getting gas out of shale. That’s the message of a new report from the Energy Institute at the University of Texas at Austin.

The US is experiencing a shale gas boom driven by fracking, or hydraulic fracturing, in which water, sand and chemical additives are injected into bedrock at high pressure to release trapped methane.

Other nations are keen to follow suit, and lead author Charles “Chip” Groat hopes the report

will help regulators worldwide separate “fact from fiction”.

Reviewing existing studies, Groat’s team found no evidence that fracking contaminates groundwater. However, this doesn’t mean that shale gas

extraction is benign. The report notes that surface spills of the chemicals used to frack, for instance, have broken environmental regulations.

“Groat’s team found no evidence that fracking contaminates groundwater”

BAD year for Canada’s tar sands. The US rejected the Keystone XL pipeline that would have carried fuel south, and now the European Union is poised to label tar bitumen more polluting than other forms of oil. That would rule out selling it to Europe.

The EU’s Fuel Quality Directive will cut the greenhouse gas emissions generated by transport fuel – from production to use – by 6 per cent by the end of 2020. Suppliers will have to label fuels according to their total greenhouse-gas footprint, and current footprints will have to shrink.

The emissions from extracting and processing tar sands are larger than for regular oil (Environmental Research Letters, DOI: 10.1088/ 1748-9326/4/1/ 014005). The EU

proposes labelling them as producing 22 per cent more emissions overall than conventional oil. Its fuel quality commission will vote on that proposal on 23 February, before the European Parliament makes the final decision.

Tar sands are dirty, but there’s not enough to cause a climate calamity, says Neil Swart at the University of Victoria in British Columbia, Canada. Canada has the largest reserve of economically viable tar sands – 170 billion barrels – and burning it all would raise global temperatures by just 0.03 °C (Nature Climate Change, DOI: 10.1038/nclimate1421).

Regardless, “any means countries can take to wean themselves off fossil fuels should be encouraged”, says Swart. He supports the EU plan.

Canada’s tar sands not shifting

–Now where’s the market?–

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Lethal gas saves livesBreathing in tiny amounts of carbon monoxide helps prevent miscarriage in mice. This could have potential to prevent miscarriage in humans, but researchers warn that exact timing and dosage of the treatment are crucial to avoid harm to the fetus (Medical Gas Research, DOI: 10.1186/2045-9912-2-4).

Rash with cashReckless gambling may result from low levels of noradrenaline, say researchers who scanned the brains of 19 volunteers as they placed bets. Those with the fewest noradrenaline transporters and therefore most noradrenaline were most cautious about losing money, and least rash with their cash (Molecular Psychiatry, DOI: 10.1038/mp.2012.7).

Infectious increaseInfectious diseases may be declining in most developed countries but New Zealand bucks the trend. Hospital admissions there as a result of infectious diseases have increased by 51 per cent over the past two decades. Increasing household overcrowding in some sections of the population may partly explain the disparity (The Lancet, DOI: 10.1016/s0140-6736(11)61780-7).

Space junk sweeperA small Swiss satellite could grab a dead compatriot and drag it to a fiery death in the atmosphere as early as 2016. Scientists at the Swiss Space Center hope the $11 million CleanSpace One satellite will be the first of a fleet of “janitor” probes.

Jumbo footprintsHerds of elephants roamed the Arabian peninsula at least 7 million years ago. The fossilised footprints of a 13-strong herd have been found in the United Arab Emirates, suggesting the ancestors of modern elephants had already evolved the complex social structures seen today (Biology Letters, DOI: 10.1098/rsbl.2011.1185).

For daily news stories, visit newscientist.com/news

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