28 April 2012 | NewScientist | 15

SOME of the genetic changes associated with ageing may be the result of epigenetics – which suggests they could be reversed.

Molecules can attach to DNA, enhancing or preventing gene activation without changing the underlying genetic code. Such epigenetic changes are already suspected as factors in psychiatric disorders, diabetes and cancer.

They may also play a role in

ageing. Jordana Bell of King’s College London and colleagues looked at the DNA of 86 sets of twin sisters aged 32 to 80, and discovered that 490 genes linked with ageing showed signs of epigenetic change through a process called methylation.

“These genes were more likely to be methylated in the older than the younger [sets of] twins,” says Bell, suggesting that the

Gut-microbe swap flips eating habits

EATEN too many pies? Blame the microbes in your gut – they may be influencing how much you eat.

In 2006, biologists found that the types of bacteria in the guts of obese rats differed from those in non-obese rats. To find out more, Mihai Covasa and his colleagues at the French National Institute for Agricultural Research (INRA) in Paris swapped gut bacteria between obesity-prone and obesity-resistant rats.

The obesity-resistant rodents proceeded to eat more and pile on the pounds. They also developed gut hormone levels typical of obesity-prone rodents.

These rats are a good model for human obesity – people, too, are either resistant or vulnerable to the condition. Understanding the gut flora associated with it may offer ways to help control food intake, Covasa said this week at the Experimental Biology 2012 meeting in San Diego, California.

Male bowerbirds grow a garden to attract a mate

WHAT has green fingers but no hands? The bowerbird, if a new study is to be believed. Males appear to cultivate plants around the structures they build to attract a mate.

Male spotted bowerbirds (Ptilonorhynchus maculatus) build structures, or bowers, from twigs before intricately decorating them with objects to attract a female. One of the males’ most desirable decorations is the berry of the Solanum ellipticum plant.

Joah Madden of the University of Exeter, UK, and colleagues studied the distribution of S. ellipticum in an area of Queensland, Australia, inhabited by the birds.

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Epigenetic changes linked with ageing epigenetic changes themselves might contribute to ageing (PLoS Genetics, DOI: 10.1371/journal.pgen.1002629).

The next challenge is to establish when gene methylation occurs. It can be triggered through lifestyle factors such as smoking, and environmental stresses.

It may one day be possible to develop enzymes that can remove the offending molecules from DNA and reverse methylation – and some aspects of ageing.

Although the males didn’t build their bowers in locations with abundant S. ellipticum, a year after construction there were, on average, 40 of the plants near each. Birds with more plants nearby had more berries within their bowers, which Madden has previously found is the best predictor of a male’s mating success. Males may discard shrivelled berries outside their bowers (Current Biology, DOI: 10.1016/j.cub.2012.02.057).

The bowerbirds are thus shaping the distribution of the plants in the area – but is it cultivation? Madden acknowledges the results do not imply that the birds intentionally grow the plants. But he points out that some hypotheses favour similarly unintentional origins for human agriculture, suggesting the bowerbirds’ activities could just about fall under that definition.

THE failure by an Antarctic telescope to spot neutrinos has knocked down a major theory about the origin of high-energy particles known as cosmic rays.

Theorists had thought explosive bursts of gamma rays could be behind the cosmic rays. So the IceCube telescope had been looking for neutrinos that ought to be produced at the same time. Finding no neutrinos is a serious blow because it rules out gamma ray bursts, says principal investigator Francis Halzen at the University of Wisconsin, Madison (Nature, DOI:10.1038/nature11068). So where do the cosmic rays come from? Nobody is sure, but attention will now shift to active galactic nuclei powered by supermassive black holes.

Neutrino no-show spoils ray theory

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