Research news and discovery
In brief– Don’t overdo it
Not seen for 200 years – a polar bear diving for its dinner THE Inuit people of the Arctic have always known about it. But no outsiders have witnessed it for 200 years: a polar bear fishing. Not by scooping the fish out of the water like a brown bear – but by plunging in and swimming. Polar bears live mainly on seals caught on the sea ice, so the shrinking of the Arctic ice pack is a real worry (New Scientist, 6 May 2006, p 10). Now it seems they may have found other sources of food. Last August, researchers based in Iqaluit, Canada, watched an adolescent polar bear swimming in a river estuary packed with charr, a relative of
salmon, that was migrating upstream. It caught about one fish an hour, swimming and peering into the water, then diving. In the two days they saw the bear, it caught three charr and three sculpin, a spiny fish that lives under rocks – which the bear seemed to lose enthusiasm for eating (Polar Biology, DOI: 10.1007/s00300-007-0338-3). The closely related brown bear catches fish very differently, by lunging and splashing in shallow water. As young polar bears learn hunting techniques from their mothers, the team speculates that this fishing technique could be widespread. But while polar bears easily get enough energy from fat, meaty seals to warrant the effort of catching them, it is not clear if this will be true of the fish they catch.
Space mutations boost bug nastiness FOOD-POISONING is bad enough on Earth, but bacteria in space can mutate into super-virulent strains that threaten astronauts’ health. The finding confirms a longstanding suspicion that microbes hitch-hiking on shuttle missions could mutate in unpredictable ways in micro-gravity. Cheryl Nickerson at Arizona State University in Tempe and her colleagues sent salmonella 16 | NewScientist | 29 September 2007
bacteria into space for 12 days on the shuttle Atlantis in September 2006. After their trip, the microbes had altered the way they express 167 genes compared with bacteria that had remained on Earth. Not only that, the team found that the space-mutated salmonella was almost three times as likely to kill mice it infected than was its Earth-bound counterpart (Proceedings of the
National Academy of Sciences, DOI: 10.1073/pnas.0707155104). Nickerson found that a protein called Hfq was responsible for regulating most of the mutated genes. Salmonella strains without Hfq did not show the geneexpression changes, making Hfq a good candidate for further research. “This information can help us design targeted strategies and countermeasures to infectious disease risks to the crew during future missions,” she says.
AVOIDING strenuous exercise in early pregnancy may reduce the risk of miscarriage. Interviews with 92,671 pregnant women in Denmark were analysed by Anne-Marie Nybo Andersen of the University of Southern Denmark in Odense. Those who exercised intensively were three-and-a-half times as likely to miscarry as those who didn’t exercise at all, she found. High-impact sports such as jogging, ball games and racket sports carried the greatest risks, as did exercising for more than 7 hours per week. Swimming did not raise the risk at all. There was no link between any form of exercise and miscarriage after 18 weeks (BJOG, DOI: 10.1111/j.14710528.2007.01496.x). The findings should not discourage women from taking mild to moderate exercise, such as swimming, says John Newnham at the University of Western Australia in Perth.
Race against time to spot bird flu AS THE northern flu season approaches, virologists are again watching to see if H5N1 bird flu will begin to spread between people. Antiviral drugs might help contain it if we act really fast – yet current tests take days. One major bottleneck is that the virus in a sputum sample has to be concentrated before its RNA can be amplified and compared with known H5N1 sequences. Now Jürgen Pipper and colleagues at the Institute of Bioengineering and Nanotechnology in Singapore have used silica particles to bind viral RNA, which can then be concentrated within minutes using a magnet (Nature Medicine, DOI: 10.1038/nm1634). This made the test nearly five times faster and up to 50 times cheaper than existing tests. www.newscientist.com