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Mothers get heart risk off their chest
NASA/JPL/SPACE SCIENCE INSTITUTE
SANDBLASTING is the key to a sparkling complexion – at least for Saturn’s moons. Astronomers first observed Saturn’s moons in detail in 2005 using the Hubble Space Telescope, during a rare perfect alignment of the sun, Earth and Saturn. They found that some of the moons, such as Tethys, shown below, are dazzlingly white, but no one could explain why they have such reflective surfaces. Now Anne Verbiscer at the University of Virginia, Charlottesville, and her colleagues have an answer. They believe that one of the moons, the icy Enceladus, has been giving its neighbours a makeover by spewing ice crystals into space. The micrometre-sized particles, thought to be ejected by geysers at Enceladus’s poles, bombard the other moons at speeds of several kilometres per second, coating them with ice (Science, vol 315, p 815). “They churn up the surface and create this fluffy layer,” says Verbiscer. “Any light hitting them then gets reflected right back.” The geysers are believed to originate from subsurface reservoirs of liquid water, which has led other astronomers to speculate that Enceladus might harbour life. If so, microbes may have hitched a ride on the flying ice to other hospitable moons, such as Titan, says Joe Burns, an astronomer at Cornell University in Ithaca, New York, who was not involved in Verbiscer’s study.
www.newscientist.com
What if rogue proteins aren’t to blame for vCJD… VIRUSES, not prions, may be at the root of diseases such as scrapie, BSE and vCJD. The widely accepted theory of what causes these so-called “transmissible spongiform encephalopathies” (TSEs), such as mad cow disease, is that deformed proteins called prions corrupt other brain proteins, eventually clogging and destroying brain cells. But this theory has never been proved completely. Laura Manuelidis of Yale University has insisted for years that virus-like particles observed
in TSE-infected brains may be the culprits, but since such brains are degenerating, the particles have been dismissed as general debris. However, when Manuelidis studied the particles in cultures of neural cells infected with two particular strains of scrapie and CJD, she found they contained particles that had clustered in regular arrays, as viruses do in cells – and no apparent prions (Proceedings of the National Academy of Sciences, vol 104, p 1965). Cells with more particles were better at infecting other cell
cultures, while boosting prions did not appear to increase their infectiousness or particle numbers. Agents that disrupt viruses stopped the cells infecting other cultures. However, leading prion researcher Adriano Aguzzi of the University Hospital of Zurich in Switzerland says Manuelidis won’t prove her case without isolating the proposed virus and showing it causes TSE. She should also test other strains for these particles and see if her infected cultures cause TSE in animals, he says. EBBY MAY/STONE
Moons reveal their makeover secret
The hills are alive with methane THE mysterious origin of undersea hills may have been explained. It’s all down to trapped wind. The low hills under the Arctic Ocean, which can grow up to 40 metres tall and several hundred metres across, have been a puzzle ever since their discovery in the 1940s. To investigate, William Ussler from the Monterey Bay Aquarium Research Institute in California and his colleagues mapped the sea floor of the Beaufort Sea shelf, off the north coast of Canada. They found that methane was being released from the hilltops. The team believe that when melting ice sheets flooded the shelves at the end of the last ice age 10,000 years ago, it warmed a frozen mixture of methane and seawater in the sediment. This decomposed, releasing methane gas that bubbled under the sea floor, pushing the sediment up and creating the hills (Geophysical Research Letters, DOI: 10.1029/2006GL027977). This is worrying, as methane is a greenhouse gas. “If warming continues there may be a substantial addition of methane to the atmosphere,” warns Ussler.
Mothers get heart risk off their chest BREASTFEEDING is well known to boost an infant’s health, and now it seems it may be good for the mother as well. In a study of 96,648 nurses who gave birth between 1986 and 2002, those who had spend at least two years of their lives breastfeeding were 19 per cent less likely to suffer a heart attack than those who hadn’t breastfed at all. The difference was independent of any of the usual risk factors for heart disease, such as family history, diet or exercise levels. One possible explanation, says study leader Alison Steube of Harvard Medical School, is that nursing a
newborn may help a mother’s metabolism switch from pregnancy mode back to normal. “Pregnancy is associated with a number of things that you normally wouldn’t want to happen to your body,” Steube says, including storing more fat and having higher than normal levels of fatty acids circulating in the blood. By breastfeeding, mothers can convert those energy reserves into nutrition for their infants. “Breastfeeding isn’t just good for babies, it’s good for mothers, too,” says Steube, who presented her findings at a meeting of the Society for Maternal-Fetal Medicine in San Francisco last week. She recommends that mothers breastfeed for three months to a year after giving birth.
17 February 2007 | NewScientist | 17
SANDBLASTING is the key to a sparkling complexion – at least for Saturn’s moons. Astronomers first observed Saturn’s moons in detail in 2005 using the Hubble Space Telescope, during a rare perfect alignment of the sun, Earth and Saturn. They found that some of the moons, such as Tethys, shown below, are dazzlingly white, but no one could explain why they have such reflective surfaces. Now Anne Verbiscer at the University of Virginia, Charlottesville, and her colleagues have an answer. They believe that one of the moons, the icy Enceladus, has been giving its neighbours a makeover by spewing ice crystals into space. The micrometre-sized particles, thought to be ejected by geysers at Enceladus’s poles, bombard the other moons at speeds of several kilometres per second, coating them with ice (Science, vol 315, p 815). “They churn up the surface and create this fluffy layer,” says Verbiscer. “Any light hitting them then gets reflected right back.” The geysers are believed to originate from subsurface reservoirs of liquid water, which has led other astronomers to speculate that Enceladus might harbour life. If so, microbes may have hitched a ride on the flying ice to other hospitable moons, such as Titan, says Joe Burns, an astronomer at Cornell University in Ithaca, New York, who was not involved in Verbiscer’s study.
www.newscientist.com
What if rogue proteins aren’t to blame for vCJD… VIRUSES, not prions, may be at the root of diseases such as scrapie, BSE and vCJD. The widely accepted theory of what causes these so-called “transmissible spongiform encephalopathies” (TSEs), such as mad cow disease, is that deformed proteins called prions corrupt other brain proteins, eventually clogging and destroying brain cells. But this theory has never been proved completely. Laura Manuelidis of Yale University has insisted for years that virus-like particles observed
in TSE-infected brains may be the culprits, but since such brains are degenerating, the particles have been dismissed as general debris. However, when Manuelidis studied the particles in cultures of neural cells infected with two particular strains of scrapie and CJD, she found they contained particles that had clustered in regular arrays, as viruses do in cells – and no apparent prions (Proceedings of the National Academy of Sciences, vol 104, p 1965). Cells with more particles were better at infecting other cell
cultures, while boosting prions did not appear to increase their infectiousness or particle numbers. Agents that disrupt viruses stopped the cells infecting other cultures. However, leading prion researcher Adriano Aguzzi of the University Hospital of Zurich in Switzerland says Manuelidis won’t prove her case without isolating the proposed virus and showing it causes TSE. She should also test other strains for these particles and see if her infected cultures cause TSE in animals, he says. EBBY MAY/STONE
Moons reveal their makeover secret
The hills are alive with methane THE mysterious origin of undersea hills may have been explained. It’s all down to trapped wind. The low hills under the Arctic Ocean, which can grow up to 40 metres tall and several hundred metres across, have been a puzzle ever since their discovery in the 1940s. To investigate, William Ussler from the Monterey Bay Aquarium Research Institute in California and his colleagues mapped the sea floor of the Beaufort Sea shelf, off the north coast of Canada. They found that methane was being released from the hilltops. The team believe that when melting ice sheets flooded the shelves at the end of the last ice age 10,000 years ago, it warmed a frozen mixture of methane and seawater in the sediment. This decomposed, releasing methane gas that bubbled under the sea floor, pushing the sediment up and creating the hills (Geophysical Research Letters, DOI: 10.1029/2006GL027977). This is worrying, as methane is a greenhouse gas. “If warming continues there may be a substantial addition of methane to the atmosphere,” warns Ussler.
Mothers get heart risk off their chest BREASTFEEDING is well known to boost an infant’s health, and now it seems it may be good for the mother as well. In a study of 96,648 nurses who gave birth between 1986 and 2002, those who had spend at least two years of their lives breastfeeding were 19 per cent less likely to suffer a heart attack than those who hadn’t breastfed at all. The difference was independent of any of the usual risk factors for heart disease, such as family history, diet or exercise levels. One possible explanation, says study leader Alison Steube of Harvard Medical School, is that nursing a
newborn may help a mother’s metabolism switch from pregnancy mode back to normal. “Pregnancy is associated with a number of things that you normally wouldn’t want to happen to your body,” Steube says, including storing more fat and having higher than normal levels of fatty acids circulating in the blood. By breastfeeding, mothers can convert those energy reserves into nutrition for their infants. “Breastfeeding isn’t just good for babies, it’s good for mothers, too,” says Steube, who presented her findings at a meeting of the Society for Maternal-Fetal Medicine in San Francisco last week. She recommends that mothers breastfeed for three months to a year after giving birth.
17 February 2007 | NewScientist | 17