1
In brief – Research news and discovery USUALLY the body’s best friend, white blood cells sometimes trigger autoimmune disease by mistakenly attacking their own tissue. Now the master cells that stop this happening have been identified, paving the way for new treatments for diseases such as rheumatoid arthritis. Mouse experiments confirm what immunologists have long suspected: the immune system is team at the University of Washington in Seattle which conducted the experiments. “Now we know they’re vital.” Rudensky engineered the mice so that their regulatory T-cells would be destroyed when they were injected with a toxin. The outcome was fast and fatal. Left to their own devices, ordinary T-cells ran amok, destroying the mice’s internal organs within a month. Regulatory T-cells probably do the same job in humans, says Rudensky. kept in check by regulatory T-cells, which patrol the body and stop ordinary T-cells going berserk. Without the regulators, ordinary T-cells attack the body’s own organs (Nature Immunology, DOI: 10.1038/ni1428). “The extent to which regulatory T-cells normally suppress autoimmunity was unknown before our study,” says Alexander Rudensky, head of the Master cells rule the enemy within IT COULD be the perfect Christmas gift for physics geeks: a table-top particle accelerator. Injecting laser beams into a plasma can create huge electric fields that accelerate the plasma’s electrons to high energies over relatively short distances. Till now, the energy of the electron beams has been hard to control, but a team led by Victor Malka at the Institute of Technology in Palaiseau, France, has solved the problem by using intersecting beams from two carefully tuned lasers. At the point where they cross, the beams create a stable wave in the plasma, which in turn accelerates electrons to precise energies (Nature, vol 444, p 737). The technique could be used to generate medical X-rays in table- top devices. It might also mean that the accelerators used by theoretical physicists need not be quite as big as they are now. “This is really the dream for accelerator physics,” says Malka. Dream accelerator EVER since H5N1 bird flu spread across Eurasia last year, battle has raged between those who blame it all on migrating wild birds and others who reckon it’s the poultry. In fact it was both. Marm Kilpatrick of the Consortium for Conservation Medicine in New York and colleagues analysed how the virus travelled by comparing H5N1 gene sequences against volumes of bird trade and migration. They found that the poultry trade explains the virus’s spread in Asia but migration explains it in Europe (Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.0609227103). The analysis suggests that H5N1 could invade the Americas by various routes – meaning the US should be testing different birds. Chicks and wild ducks dunnit IF THERE were a silver lining to the massive cloud of pollutants hanging over India, it would be that this brown haze is doing farmers a favour by counteracting global warming. In fact it does more harm than good, and getting rid of it would probably increase the rice harvest. Between October and May, a 3-kilometre-thick brown haze sits over much of south Asia and the northern Indian Ocean. Caused mostly by urban emissions and wood fires, this dirty cloud cools the region by reflecting sunlight back into space. Unfortunately it also reduces evaporation, leading to a reduction in monsoon rainfall. When Jeffery Vincent of the University of California, San Diego, and his colleagues combined data on India’s rice harvests with a climate model they found that the harvests would be up to 10.6 per cent higher if the brown haze wasn’t there, and 14.4 per cent higher if the detrimental effects of global warming were removed too (Proceedings of the National Academy of Sciences, DOI: 10.1073/ pnas.0609584104). Cleaning up the brown haze will have a positive effect, says Vincent. “Any negative impacts of intensified warming on rice harvests would be outweighed by the positive impacts of greater rainfall due to a lessening of the brown cloud’s drying effect.” REUTERS 20 | NewScientist | 9 December 2006 www.newscientist.com Dirty cloud over India is no help to region’s rice farmers
