Hunting for the roots of Alzheimer’s and stringing nanoparticles

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New Alzheimer’s disease gene found

An international collaboration involving local genetics researchers has identified a new gene that increases the risk of Alzheimer’s disease in the elderly.

Working with researchers in Toronto, New York, and other locations, Lindsay Farrer and colleagues at Boston University helped define two variants of the SORLA gene that are more common in people with Alzheimer’s disease.

Previous studies in cell cultures have shown that lower levels of the SORLA protein are associated with the increased production of toxic amyloid proteins, which are presumed to cause the brain damage and memory loss seen in Alzheimer’s patients.

To investigate whether changes in SORLA protein production actually contribute to the disease in Alzheimer’s patients, the researchers analyzed the DNA of nearly 6,000 people, some with the disease and others without, from different ethnic groups around the world. They looked for single nucleotide changes in certain genes, including the SORLA gene.

While they didn’t find a telltale mutation that caused the disease, they did find that several of the gene variants produced lower levels of the SORLA protein in blood cells. If that holds true in the brain, it suggests that one function of SORLA may be to protect cells against amyloid build-up.

The researchers caution that their test subjects came from a limited number of carefully selected families, so the results will need to be replicated in the general population.

The report was published online in Nature Genetics. Pat McCaffrey

Getting a grip on nanospheres

Coating nanoparticles with molecular “hair” is a quick and easy way to make them bind together in a controlled way, a new MIT study in Science shows.

Nanotechnology holds promise for creating materials customized at the atomic level, its supporters say. But to join nanoparticles together, researchers need a way to link them directly in a more controlled fashion. Current methods use enzymes and antibodies to connect nanoparticles in a somewhat haphazard way.

A new, simpler method comes from Francesco Stellacci and colleagues at MIT, who coated gold nanospheres with two kinds of molecular “hair”: one containing a nine-carbon chain, the other a stubby benzene ring.

These molecules automatically arranged themselves into alternating rows, but at the poles, one or two individual hairs stuck out, making them more reactive.

(Credit: Science)

Stellaci’s team exploited this property by attaching chemical handles to these hairs at either pole. Then, using a simple reaction, the researchers were able to join the nanospheres end to end, like pearls on a string, creating long chains.

They were also able to make woven sheets of these nanospheres. Stellacci hopes this kind of controlled linkage between nanoparticles will be useful in creating materials with tailor-made properties, such as filters with small, precisely sized holes. Mason Inman