29 August 2009 | NewScientist | 7

Faulty mtDNA inherited from the mother can cause incurable diseases such as MELAS syndrome.

Mitalipov transferred chromosomes, but not the mtDNA, from the eggs of female monkeys into chromosome-free donor eggs that retained their own mtDNA. The team then fertilised the eggs using standard IVF (Nature, DOI: 10.1038/nature08368). “I believe it can be replicated in people very quickly,” he says.

However, gene therapy of this kind that introduces heritable changes could make regulators nervous about human trials.

Moon dance

AN INDIAN and a US space probe have performed a delicate dance in lunar orbit, a manoeuvre designed to detect water on the moon.

“It’s a unique experiment that can only be conducted by two spacecraft in orbit at the same time,” says NASA’s Jason Crusan in Washington DC.

The first evidence of lunar water came in 1994, from radar signals sent by the NASA moon probe Clementine, bounced off the moon and picked up by the probe and receivers on Earth. The reflections hinted that there might be water ice on the surface, but solid proof requires closer listening posts. So on 20 August NASA’s Lunar Reconnaissance Orbiter (LRO) and India’s Chandrayaan-1 came within a few dozen kilometres of each other, thanks to tight coordination between NASA and the Indian Space Research Organisation.

Then Chandrayaan-1 fired its radar at a crater near the moon’s north pole, and both spacecraft listened to the echoes. The results are still being analysed, but the partners will probably not perform this measurement again: the LRO will soon settle into a lower orbit than Chandrayaan-1 to begin its main observing task.

Imaging risks

X-RAYS and CT scans expose a minority of Americans to radiation levels comparable to working in a nuclear power plant. Are such scans worth it?

Reza Fazel of Emory University in Atlanta, Georgia, and colleagues looked at health insurance records for over 650,000 people who had at least one imaging procedure in a three-year period. Most received low doses of radiation, but around 2 per cent got doses equal to or above the suggested yearly exposure for someone working in a nuclear power plant (The New

England Journal of Medicine, vol 361, p 849). Fazel says further studies are needed to work out if such medical scans benefit or damage health overall.

Commenting on the research, radiologist James Thrall at

Harvard Medical School points to a recent study reporting that medical imaging accounted for a one-year rise in life expectancy in the US between 1991 and 2004.

“Some patients got doses above the suggested levels for someone working in a nuclear power plant”

FARMERS wreck forests, right?

You would be hard-pressed to find

anyone who disagreed, but it turns

out the number of trees on farms

around the world has been seriously

underestimated.

In fact, a study by the World

Agroforestry Centre (WAC) in Nairobi,

Kenya, shows that often, the more

intensive the farming, the more trees

farmers plant – for fruit, medicines,

fodder crops, windbreaks and fuel.

The research, presented at the

World Congress of Agroforestry in

Nairobi this week, uses satellite

images to show that almost half of the

22 million square kilometres of farmed

land worldwide has at least 10 per

cent tree cover, most of it previously

unmapped. About 7 per cent of

land classified as agricultural had

more than 50 per cent tree cover.

Even densely populated

regions like south-east Asia

typically have tree cover on more

than a third of farmland, says study

author Robert Zomer. “Pioneer

farmers remove trees from the

landscape, but as intensive systems

develop, there is an increase in

planting useful trees,” he says.

“Farmers are protecting and

planting trees, but planners have

been slow to recognise this,” says

WAC director Dennis Garrity. The

group wants farmers to be able to

claim carbon credits for increasing

forest cover.

Trees find friends in farmers

–Farm with sylvan charm–

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Engineers for EarthGeoengineering could contribute

to a million-job green engineering

sector in the UK by 2050, says the

British Institution of Mechanical

Engineers. It says that the British

government should set aside

£10 million for research into the field

and should start building artificial

trees to suck carbon dioxide out of

the atmosphere.

Hippy habits die hardForty years after the festival

that gave them their name, the

“Woodstock generation” continue to

make a mark on US health statistics.

The Substance Abuse and Mental

Health Services Administration

reports that, in 2007, 9.4 per cent of

people aged 50 to 59 said they had

used illicit drugs in the previous year,

up from 5.1 per cent in 2002. In

people of all other ages, rates of drug

use are constant or decreasing.

Tiger hitPoachers have broken into Taman

Rimba Zoo on Sumatra in Indonesia

and slaughtered a rare Sumatran

tiger for its body parts. The tiger,

part of a conservation project run by

the Zoological Society of London,

was killed on Saturday morning after

being drugged.

Space club growsSouth Korea joined the league of

spacefaring nations on 25 August

when its first rocket carrying a

satellite blasted into space. The

Earth-observation satellite,

however, appears not to have

reached its intended altitude.

Counting cancer’s costCancer doesn’t just take a

human toll, it also creates a financial

burden. The Lance Armstrong

Foundation, based in Austin,

Texas, estimates that there will be

12.9 million new cancer cases

across the globe this year, which

will cost the world $305 billion.

It predicts there will be 16.8 million

new cancer cases in 2020.

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