In brief– Research news and discovery

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THE odour of disease makes pregnant mice boost their babies’ immunity. It is the first proof that social or environmental cues detected by a pregnant mother can alter traits in its babies .

Female mice are attuned to the odour of male mice as it helps them pick a mate. Olivia Curno of the University of Nottingham, UK, and her team housed pregnant mice next to male mice infected

with a parasite. A partition meant the females could smell the males but not come into contact to catch the disease .

Offspring of these mice exposed to the parasite after birth cleared the infection up to five days sooner than those of control mice (Proceedings of the Royal Society B, DOI: 10.1098/rspb.2008.1612). They were also less aggressive. The team found that mothers exposed

to infected mice had levels of the stress hormone corticosterone twice as high as normal.

Curno thinks the pregant mice respond to a subtle odour given off by sick animals. The hormone spike could then warn the fetus of disease, and prompt it to invest heavily in its immune system.

This also explains why pups of control mice tended to be stronger . “If there’s no disease, it’s worth putting everything into fighting, but if there’s disease it’s better to invest in immunity,” says Curno.

Whiff of disease bolsters immunity

SPENDING time in zero gravity could hinder human growth – if we are anything like newts, that is.

Eduardo Almeida of NASA’s Ames Research Center in Mountain View, California, and his team cut the tails off 16 newts (Pleurodeles waltl) before sending them into space. While the tails did regrow, as they do on Earth, they were less than half as long as normal.

“This is important evidence that regeneration does not occur at a normal rate in space,” says Almeida, who presented the results at the American Society for Cell Biology meeting in San Francisco last month .

He believes gravity activates signals that tell cells to divide . As humans may suffer if it is absent, this needs to be resolved before considering life in space, he says.

Newts stunted by trip in space

MANY species’ sperm make a beeline to fertilise an egg – but not that of sea urchins, and now we know why.

Sea urchin eggs release an attractant chemical to lure sperm towards them, but currents in the water disperse the signal. Ben Friedrich and Frank Jülicher of the Max Planck Institute for the Physics of Complex Systems in Dresden, Germany, used models to show that a helical swim pattern allows the sperm to sample its chemical surroundings in a way that enables it to take the motion of the water into account (New Journal of Physics, DOI: 10.1088/1367-2630/10/12/123025).

Once the chemical is detected, the sperm follow the concentration gradient to the egg. They may have to make more than one turn before reaching the correct trajectory: “What matters in the end is the averaged direction after several circular turns,” Friedrich says.

Spiralling sperm

“MOUNTAIN waves” in the atmosphere above Antarctica create rare clouds that are helping destroy the ozone layer.

Over the last two decades, chlorofluorocarbons (CFCs) released by human activity have opened a hole in the ozone layer over Antarctica. Key chemical reactions that lead to ozone depletion happen on the surface of rare polar stratospheric clouds (PSCs), which form high up in the atmosphere. Here, sunlight breaks down the CFCs into products that react to produce chlorine, which in turn decomposes ozone. “The question was: how are these

clouds generated?” says Lars Hoffmann of the Jülich Research Centre in Germany.

Steve Eckermann of the US Naval Research Laboratory in Washington DC, along with Hoffmann and colleagues, used satellite infrared data to study atmospheric temperatures above the Antarctic Peninsula. They found pockets of high and low temperature air in the stratosphere, and these only occurred above mountains. The colder pockets fell below -78 °C, which is cold enough for PSCs to form.

This implicates so-called mountain waves, which are created when an airstream flows over high relief. The waves churn up the air high in the atmosphere and appear to create the temperature variations (Geophysical Research Letters, DOI: 10.1029/2008GL036629).

Icy peaks power perfect wave for cloud-surfing ozone eaters

12 | NewScientist | 3 January 2009 www.newscientist.com