18 February 2012 | NewScientist | 17

WHAT good fortune: a drug used to treat cancer can also reverse an Alzheimer’s-like disease in mice, taking just 72 hours to work.

Alzheimer’s is associated with deposits of beta-amyloid peptides in the brain, causing neurons to die and leading to memory loss.

Paige Cramer at the Case Western Reserve University School of Medicine in Cleveland, Ohio, reckoned it might be

possible to prevent the build-up of plaques with bexarotene, an anti-cancer drug.

In a healthy brain, a substance called apolipoprotein E (ApoE) helps clear beta-amyloid deposits. ApoE is activated in part by a cellular receptor called RXR; bexarotene enhances RXR action.

When Cramer gave bexarotene to mice with Alzheimer’s-like damage, more than half of the

How salty towers build themselves

CORAL-like formations of salt sometimes sprout up on walls, damaging frescoes and other artwork, and now researchers know why.

Experiments and simulations by Marc Prat at the University of Toulouse in France and colleagues show how salty water evaporating from the pores in these materials leaves behind patches of salt crystals that grow into towers rather than a uniform film.

The towers are themselves porous and suck in more salty water. As they grow, water evaporating from their sides inhibits evaporation from surrounding areas, preventing crystal growth around the towers (Physical Review Letters, DOI: 10.1103/physrevlett.108.054502).

The work suggests that maintaining the right distribution of humidity over delicate frescoes may prevent such structures from forming.

Call me sponge-mouth again and I’ll bite you

WHAT do a snake’s mouth and a sponge have in common? Capillary action. Some species may use skin folds in their lower jaw like a sponge, to soak up water and ferry it into their gut.

In 1993, researchers found that boa constrictors sucked water in through a tiny hole in their mouths as if they were drinking through a straw. But David Cundall of Lehigh University in Bethlehem, Pennsylvania, found no evidence of suction when he placed pressure sensors inside the mouths of three other species, Agkistrodon piscivorus, Heterodon platirhinos and

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Alzheimer’s symptoms reversed in mice beta-amyloid plaques cleared from the brain within 72 hours. There was also a rapid reversal in cognitive deficits (Science, DOI: 10.1126/science.1217697).

Cramer hopes to begin phase 1 clinical trials of bexarotene in the next few months. However, other researchers remain cautious. “The drug development world is littered with drugs that seemed to work on transgenic mice, but didn’t work on people,” says Derek Hill of University College London.

Pantherophis spiloides (Journal of Experimental Zoology, DOI: 10.1002/jez.1710).

Instead, Cundall thinks that skin creases in their lower jaw, which expand when the snakes swallow large prey, help them drink. Their tongues, he notes, are too small to lap up water, and are covered in a sheath that would prevent this even if they were larger. And snakes can’t tip their heads back to scoop in water like humans do.

Instead, he says, the skin folds work like tiny tubes in a sponge, drawing water into the mouth through capillary action. Muscle action then squeezes the water down into the snake’s gut. Kurt Schwenk at the University of Connecticut in Storrs is convinced. “How animals drink is surprisingly complicated. I think they’ve pretty much nailed it in snakes.”

STRESS or diet may suppress growth of the brain’s cerebellum in the womb. Researchers claim this could later contribute to schizophrenia, as people with the mental illness sometimes have abnormally small cerebellums.

When Ruth Pidsley of King’s College London and colleagues analysed DNA from post-mortem brains, they found that altered methylation in a key gene that drives growth was correlated with cerebellar weight (Epigenetics, DOI: 10.4161/epi.7.2.18910).

Such changes in methylation can occur in response to stress and diet. Since exposure to stress in the womb is already linked to schizophrenia, Pidsley has begun testing how these different factors may contribute to mental illness.

Genes, cerebellums and schizophrenia

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