12 May 2012 | NewScientist | 17

Insects thrive on Pacific plastic patch

FOR many marine animals, tiny pieces of plastic are a big problem. But for one marine insect, they are a handy place to lay eggs.

Vast amounts of plastic have been dumped into the ocean over the last few decades. Bottles and bags are obvious, but the majority is made up of fragments less than 5 millimetres across. Much of this “microplastic” ends up in the Great Pacific Garbage Patch.

To find out how the Garbage Patch affects local ecosystems, Miriam Goldstein and colleagues at the Scripps Institution of Oceanography in La Jolla, California, monitored the Pacific pelagic water strider (Halobates sericeus). Between 1972 and 2010 the amount of microplastic in the Garbage Patch increased by two orders of magnitude. Over the same period, the water striders became significantly more abundant. They lay their eggs on hard surfaces, so the microplastics came in handy, says the team (Biology Letters, DOI: 10.1098/rsbl.2012.0298).

The plastic is effectively creating a new habitat, says Richard Thompson of Plymouth University, UK, and there will be knock-on effects.

Hard of hearing, dull of fingers… it’s all in the genesDULL fingers? Blame your genes. It has just been discovered that sensitivity to touch is heritable, and apparently linked to hearing as well.

Gary Lewin and colleagues at the Max Delbrück Center for Molecular Medicine in Berlin, Germany, measured touch in 100 healthy pairs of fraternal and identical twins. They tested finger sensitivity in two ways: by response to a high-frequency vibration and the ability to identify the orientation of very fine grating.

Lewin’s team found that up to 50 per cent of the variation in sensitivity to touch was genetically determined. Audio tests also showed that those with good hearing were more likely to have sensitive touch. The link between the two is logical, as both touch and hearing rely on sensory cells that detect mechanical forces.

Next the researchers studied touch sensitivity in students with congenital deafness. They found that 1 in 5 also had impaired touch, indicating that some genes causing deafness may also dull

THERE can be smoke without fire. Sharp rings of dust around stars aren’t always carved by planets but can form on their own – bad news for those who use the structures to guide them to stars that host planets.

The discs of dust and gas debris surrounding stars (blue area in photo above) sometimes produce sharply defined or elongated rings. These were assumed to be the calling cards of unseen planets, carved by the bodies as they travel through the disc.

Now Wladimir Lyra at NASA’s Jet Propulsion Laboratory in Pasadena, California, and Marc Kuchner

at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, have shown that interactions between dust and gas alone can account for the rings.

Dust concentrates in regions of high-pressure gas. As the star heats the dust, it in turn causes the gas to heat up and expand, creating higher pressure which then concentrates more dust. Lyra and Kuchner simulated this feedback process and, with no planets in their model, created several types of structure, including elongated rings and clumps (arxiv.org/abs/1204.6322).

Ring headache for planet hunters

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the sense of touch. When they looked at a subset of individuals who were deaf and blind due to Usher syndrome, they found that mutations in a single gene, USH2A, caused both the disease and reduced sensitivity to touch (PLoS Biology, DOI: 10.1371/journal.pbio.1001318).

The next step is to try to identify more genes that affect our sense of touch. “There are many more genes than just the one we found,” says Lewin, adding that finding them “will hopefully show us more about the biology of touch”.

Molecular balls keep breasts soft

HERE’S a question you don’t hear in the breastfeeding debate: why doesn’t milk turn breasts to bone?

Charles Darwin suggested that lactation evolved through natural selection, starting when the ancestors of mammals gained a nutritional advantage from lapping up sweat-like secretions from glands under their mothers’ skin.

But milk contains 100 times the calcium of a gland secretion, and 1000 times the concentration of protein. Such an increase in calcium should cause calcification of the secretory gland, and the proteins in milk fibres should form toxic plaques.

To find out what was going on, Carl Holt at the University of Glasgow, UK, and John Carver from the University of Adelaide, Australia, built 3D models of the interaction between ions and proteins in biological fluids.

They found that caseins, nutritional proteins in milk, help to prevent calcium build-up by capturing calcium phosphate and squirrelling it away inside molecular aggregates called micelles (Journal of Evolutionary Biology, DOI: 10.1111/j.1420-9101.2012.02509.x).

Holt and Carver say that the concentration of these spherical micelles in milk may have increased over evolutionary time, producing a progressively more nutritious fluid.

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