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Gamma rays may betray dark matter's presence
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WHY put snakes and people who are afraid of them into a brain scanner? Uri Nili and Yadin Dudai, at the Weizmann Institute in Rehovot, Israel, did it to work out what’s going on in people’s brains when they overcome fear. Their conclusion is that courage does not come by banishing fear completely, but through overcoming it enough to act. “A firefighter having to go into a burning building should display courage, but that firefighter is not fearless,” Dudai says. The researchers examined the brain activity of 39 people with an abnormally strong fear of snakes as they lay in a functional MRI (fMRI) brain scanner. They were given the option either to move a venomless 1.5-metre-long corn snake further away from their heads along a conveyer belt, or to bring it closer. The scans showed that the subgenual anterior cingulate cortex (sgACC), an area linked to emotion, became particularly active when participants brought the snakes closer, but not when they gave in to their fears (Neuron, DOI: 10.1016/j. neuron.2010.06.009). “If you manage to maintain activity in this area at a high level, you will be able to overcome your fear,” says Nili. If, as he suggests, the sgACC blocks natural responses to fear, t could one day be a target in therapies to rid people of phobias.
Natural killer cells are at the root of hair-loss disease AN AUTOIMMUNE condition in which people lose some or all of their hair may result from mistaken attacks on hair follicles by the so-called natural killer white blood cells. The insight comes from a huge study that compared the genomes of more than 1000 individuals with the condition alopecia areata against those of people free of it. Angela Christiano of Columbia University in New York and her colleagues uncovered 18 genes linked with alopecia areata. As might be expected of an
autoimmune disease, where the immune system turns on healthy tissue, all the genes play a role in controlling the growth and multiplication of cells in the immune system. The strongest link was with a gene called ULBP. It codes for a protein that is a powerful activator of natural killer cells, which usually attack viruses and other pathogens. The team also found higher amounts of the protein in hair follicle tissue from people with alopecia areata than in samples
from people free of it, providing additional evidence of its involvement (Nature, DOI: 10.1038/nature09114). The team hope that these discoveries will provide new ways of treating the disease. “This is a major breakthrough,” says Rod Sinclair, a dermatologist at the University of Melbourne in Australia. “After decades of limited progress, this paper heralds a new era of discovery as we pick apart these genes one by one to determine their interplay in the disease.” stephen dalton/nhpa
Scans point to the source of courage
Gamma rays may betray dark matter CLOUDS of dark matter the size of our solar system floating around the Milky Way may betray their presence by emitting gamma rays. Dark matter is thought to make up most of the mass of the universe, but as it does not interact with light, it has never been directly observed. Now computer simulations by Tomoaki Ishiyama of the National Astronomical Observatory in Tokyo, Japan, and colleagues suggest a way to detect it. Their model shows that the Milky Way should be littered with small clumps of dark matter, each about the size of our solar system. These would have been the first structures that formed in the universe. Earlier studies had suggested that the gravity of nearby stars would have ripped apart these primordial clumps, but the new simulations show that this would only happen in the crowded core of galaxies, leaving the clumps in the galactic suburbs intact (arxiv.org/abs/1006.3392). At the centre of such clumps, dark matter particles would be colliding and annihilating, emitting gamma rays. NASA’s Fermi Space Telescope is now looking for such light.
Warm climates boost bird beak size IF THE toco toucan had evolved in chilly Scotland, its impressive bill would have been much more modest. That’s the conclusion of researchers who say heat exchange can be added to diet and mate attraction as key drivers of bird beak size. Last year Glenn Tattersall of Brock University in Ontario, Canada, found the toco toucan loses up to 60 per cent of its body heat through its beak. Now he and Matthew Symonds, at the University of Melbourne, Australia, have compared beak length in 214 bird species with the annual minimum temperature of their native
habitats. “From toucans to parrots to grouse to penguins, species that deal with colder temperatures have smaller bills,” says Symonds. They isolated the importance of temperature by studying only female beak length and comparing species with similar diets living in different climates. Averaged across all species, temperature explained 16 per cent of beak size variation (The American Naturalist, DOI: 10.1086/653666). For gulls and penguins it accounted for 66 per cent and 43 per cent of the variation respectively.
3 July 2010 | NewScientist | 17
justin ouellette/fstop/plainpicture
WHY put snakes and people who are afraid of them into a brain scanner? Uri Nili and Yadin Dudai, at the Weizmann Institute in Rehovot, Israel, did it to work out what’s going on in people’s brains when they overcome fear. Their conclusion is that courage does not come by banishing fear completely, but through overcoming it enough to act. “A firefighter having to go into a burning building should display courage, but that firefighter is not fearless,” Dudai says. The researchers examined the brain activity of 39 people with an abnormally strong fear of snakes as they lay in a functional MRI (fMRI) brain scanner. They were given the option either to move a venomless 1.5-metre-long corn snake further away from their heads along a conveyer belt, or to bring it closer. The scans showed that the subgenual anterior cingulate cortex (sgACC), an area linked to emotion, became particularly active when participants brought the snakes closer, but not when they gave in to their fears (Neuron, DOI: 10.1016/j. neuron.2010.06.009). “If you manage to maintain activity in this area at a high level, you will be able to overcome your fear,” says Nili. If, as he suggests, the sgACC blocks natural responses to fear, t could one day be a target in therapies to rid people of phobias.
Natural killer cells are at the root of hair-loss disease AN AUTOIMMUNE condition in which people lose some or all of their hair may result from mistaken attacks on hair follicles by the so-called natural killer white blood cells. The insight comes from a huge study that compared the genomes of more than 1000 individuals with the condition alopecia areata against those of people free of it. Angela Christiano of Columbia University in New York and her colleagues uncovered 18 genes linked with alopecia areata. As might be expected of an
autoimmune disease, where the immune system turns on healthy tissue, all the genes play a role in controlling the growth and multiplication of cells in the immune system. The strongest link was with a gene called ULBP. It codes for a protein that is a powerful activator of natural killer cells, which usually attack viruses and other pathogens. The team also found higher amounts of the protein in hair follicle tissue from people with alopecia areata than in samples
from people free of it, providing additional evidence of its involvement (Nature, DOI: 10.1038/nature09114). The team hope that these discoveries will provide new ways of treating the disease. “This is a major breakthrough,” says Rod Sinclair, a dermatologist at the University of Melbourne in Australia. “After decades of limited progress, this paper heralds a new era of discovery as we pick apart these genes one by one to determine their interplay in the disease.” stephen dalton/nhpa
Scans point to the source of courage
Gamma rays may betray dark matter CLOUDS of dark matter the size of our solar system floating around the Milky Way may betray their presence by emitting gamma rays. Dark matter is thought to make up most of the mass of the universe, but as it does not interact with light, it has never been directly observed. Now computer simulations by Tomoaki Ishiyama of the National Astronomical Observatory in Tokyo, Japan, and colleagues suggest a way to detect it. Their model shows that the Milky Way should be littered with small clumps of dark matter, each about the size of our solar system. These would have been the first structures that formed in the universe. Earlier studies had suggested that the gravity of nearby stars would have ripped apart these primordial clumps, but the new simulations show that this would only happen in the crowded core of galaxies, leaving the clumps in the galactic suburbs intact (arxiv.org/abs/1006.3392). At the centre of such clumps, dark matter particles would be colliding and annihilating, emitting gamma rays. NASA’s Fermi Space Telescope is now looking for such light.
Warm climates boost bird beak size IF THE toco toucan had evolved in chilly Scotland, its impressive bill would have been much more modest. That’s the conclusion of researchers who say heat exchange can be added to diet and mate attraction as key drivers of bird beak size. Last year Glenn Tattersall of Brock University in Ontario, Canada, found the toco toucan loses up to 60 per cent of its body heat through its beak. Now he and Matthew Symonds, at the University of Melbourne, Australia, have compared beak length in 214 bird species with the annual minimum temperature of their native
habitats. “From toucans to parrots to grouse to penguins, species that deal with colder temperatures have smaller bills,” says Symonds. They isolated the importance of temperature by studying only female beak length and comparing species with similar diets living in different climates. Averaged across all species, temperature explained 16 per cent of beak size variation (The American Naturalist, DOI: 10.1086/653666). For gulls and penguins it accounted for 66 per cent and 43 per cent of the variation respectively.
3 July 2010 | NewScientist | 17