Bowel gene linked to a type of autism

ON TOP of dealing with social and learning difficulties, people with autism also run an unusually high risk of bowel disorders. Now a gene variant has been found that may explain this link.

A large proportion of people with autism also have problems such as chronic diarrhoea, constipation or food intolerance. The MET gene, which has been linked to autism, is known to play a role in the repair of damaged gut tissue, so Daniel Campbell of Vanderbilt University in Nashville, Tennessee, thought this gene might be involved.

Sure enough, in 118 families in which at least one child had both autism and gut disorders, his team found that a particular variant of the MET gene was more common in the child with autism than in its parents, suggesting the gene played a role in their autism. By contrast this was not the case in 96 families where the children with autism did not have gut problems, suggesting their autism had a different cause (Pediatrics, DOI: 10.1524/peds.2008-0819).

Knowing the underlying genetic cause of an individual’s autism could eventually lead to better ways of treating the condition.

Jumping genes are great leap forward for stem cells

A ROVING snippet of DNA has been used to make reprogrammed stem cells that are stripped of potentially cancer-causing genes .

The first reprogrammed stem cells – known as induced pluripotent stem cells – were made by Shinya Yamanaka of Kyoto University in Japan. He used viruses to insert four genes into the chromosomes of adult skin cells, reprogramming them into an embryonic state. These iPS cells could turn into any of the body’s tissues, but cells derived from them were not transplantable into

people because viruses can add extra copies of cancer-causing genes to the chromosome.

Now two teams, led by Keisuke Kaji of the University of Edinburgh, UK, and Andras Nagy of the Samuel Lunenfeld Research Institute in Toronto, Canada, have used a piece of DNA called a transposon to deliver the four genes. Unlike viruses, the transposon can often be made to leap out of the genome once it has done its job rather than reinserting, posing less of a cancer risk .

The teams engineered the

AN AFRICAN jumping spider uses its

agility not just to hunt, but also to

steal food from the mouths of ants.

Menemerus spiders have eyes

pointing forwards, sideways and

upwards, allowing them to “see like

a primate and hunt like a lion”, says

Simon Pollard from the University

of Canterbury in Christchurch, New

Zealand. With his colleague Robert

Jackson, Pollard filmed 98 spider-ant

tussles at Lake Victoria in Kenya. In

each case, they saw that when an

ant grabbed a lake fly, a spider

lurking nearby snatched it out of

its jaws (Journal of Arachnology,

DOI: 10.1636/st07-55.1).

The spiders may be using the ants

to sift out fresh prey. The corpses of

lake flies can be trapped by strands of

spider silk, where they dance in the

wind “like macabre puppets” says

Pollard. But as spiders can’t digest

the dried-out corpses, using webs to

catch them may just waste energy .

Eileen Hebets from the University

of Nebraska in Lincoln wonders if the

behaviour is instinctive or learned.

“I want to know if exposure to

another individual foraging in this

way increases the likelihood of

attempting it on one’s own.”

Taking food from the mouths of ants

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transposon piggyBac to contain Yamanaka’s four genes, then added it to mouse and human skin cells. It reprogrammed a small portion of these cells. Then they reactivated the transposon to make it leap out of the chromosomes, and selected for those cells in which it failed to jump back in again (N ature, DOI: 10.1038/nature07863 and DOI: 10.1038/nature07864).

Previously, iPS cells have been made using viruses that don’t insert themselves into the genome , but the engineered piggyBac was more efficient.

The case of the Venetian vampire

A SKELETON exhumed from a grave

in Venice is being claimed as the

first known example of the

“vampires” widely referred to

in contemporary documents.

Matteo Borrini of the University

of Florence in Italy found the

skeleton of a woman with a small

brick in her mouth (see below) while

excavating mass graves of plague

victims from the Middle Ages on

Lazzaretto Nuovo Island in Venice.

At the time the woman died,

many people believed that the

plague was spread by “vampires”

which, rather than drinking people’s

blood, spread disease by chewing

on their shrouds after dying. Grave-

diggers put bricks in the mouths of

suspected vampires to stop them

doing this, Borrini says.

The belief in vampires probably

arose because blood is sometimes

expelled from the mouths of the

dead, causing the shroud to sink

inwards and tear. Borrini, who

presented his findings at a meeting

of the American Academy of

Forensic Sciences in Denver,

Colorado, last week, claims this

might be the first such vampire to

have been forensically examined.

However, Peer Moore-Jansen of

Wichita State University in Kansas

says he has found similar skeletons

in Poland and that while Borrini’s

finding is exciting, “claiming it as

the first vampire is a little ridiculous”.

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7 March 2009 | NewScientist | 15