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WASHINGTON, June 16 (Xinhua) -- Cells in the human body are constantly being exposed to stress from environmental chemicals or errors in routine cellular processes. While stress can cause damage, it can also provide the stimulus for undoing the damage. New research by a team of scientists at the University of Rochester has unveiled an important new mechanism that allows cells to recognize when they are under stress and prime the DNA repair machinery to respond to the threat of damage.Their findings will be published Friday in journal Science. Cells in the human body are constantly being exposed to stress from environmental chemicals or errors in routine cellular processes. While stress can cause damage, it can also provide the stimulus for undoing the damage.The scientists, led by biologists Vera Gorbunova and Andrei Seluanov, focused on the most dangerous type of DNA damage -- double strand breaks. Unrepaired, this type of damage can lead to premature aging and cancer. They studied how oxidative stress affects efficiency of DNA repair. Oxidative stress occurs when the body is unable to neutralize the highly-reactive molecules, which are typically produced during routine cellular activities.The research team found that human cells undergoing oxidative stress synthesized more of a protein called SIRT6. By increasing SIRT6 levels, cells were able to stimulate their ability to repair double strand breaks. When the cells were treated with a drug that inactivated SIRT6, DNA repair came to a halt, thus confirming the role of SIRT6 in DNA repair. Gorbunova notes that the SIRT6 protein is structurally related to another protein, SIR2, which has been shown to extend lifespan in multiple model organisms."SIRT6 also affects DNA repair when there is no oxidative stress," explains Gorbunova. "It's just that the effect is magnified when the cells are challenged with even small amounts of oxidative stress."SIRT6 allows the cells to be economical with their resources, priming the repair enzymes only when there is damage that needs to be repaired. Thus SIRT6 may be a master regulator that coordinates stress and DNA repair activities, according to Gorbunova.

BEIJING, Aug. 27 (Xinhua) -- Heavy rain battered several east China provinces Saturday, destroying homes and farmlands, while drought persisted in some of the country's arid central and southwestern regions.On Friday and Saturday, five counties in Anhui Province were hit by downpour, the provincial meteorological bureau said.It said 23 towns reported over 200 mm of rainfall in the 24 hours from 8 a.m. Friday to 8 a.m. Saturday. In some villages of Huaiyuan County, the precipitation topped 300 mm, about one third of the annual average volume.In Fengtai County alone, 2,048 people were stranded by rain-triggered flood. As of 9 p.m. Saturday, about 800 of them were still waiting for evacuation.Incomplete statistics provided by the provincial government said 280 houses toppled in the rain disaster and another 580 homes were damaged. About 54,800 hectares of cropland was drowned by rain and flood.The direct economic loss was estimated at 240 million yuan (37.6 million U.S. dollars), the provincial government said Saturday night.The provincial weather bureau forecast heavy rain will continue in most parts of Anhui in the coming three days.Heavy rain also wreaked havoc in seven cities and counties of the eastern Shandong Province, causing 230 million yuan of direct economic losses.Torrential rain that lasted more than 24 hours from Friday to Saturday afternoon forced evacuation of nearly 2,000 people in parts of Zaozhuang, Liaocheng and Linyi cities, the provincial civil affairs department said.It said nearly 500 homes toppled and more than 800 others were damaged.China Meteorological Administration has forecast heavy rain in the coming three days in Anhui, Shandong, Liaoning, Jiangxi provinces and parts of the Xinjiang Uygur Autonomous Region in the coming two to three days.Little rain has been predicted, however, for the drought-hit provinces in central and southwestern China, the administration said on its website.While the predicted rainfall for Guizhou, Sichuan, Chongqing, Yunnan, Hunan and Guangxi averages only 2 to 8 mm in four days from Aug. 28 to 31, it said the high temperature in these areas will still hover over 35 degrees Celsius.Affected by the approaching Typhoon Nanmadol, the coastal areas of Guangdong Province will experience high tides Sunday, but the scorching weather will stay next week, the provincial weather bureau said.The high temperature in most parts of the province has topped 35 degrees Celsius.

LOS ANGELES, July 5 (Xinhua) -- NASA's Juno spacecraft is 30 days away before its first launch window opens, the Jet Propulsion Laboratory (JPL) announced on Tuesday."One month from today, our first launch window opens at 11:34 a. m. EDT (8:34 a.m. PDT) and lasts 69 minutes," said Jan Chodas, Juno project manager from NASA's JPL in Pasadena, Los Angeles."Our primary launch period is 22 days long, and so if weather or other issues come up on Aug. 5, we have 21 more days to get Juno flying. Once we get Juno into space, it's a five-year cruise to Jupiter.""The launch window is the length of time allotted every day for an attempt to launch the spacecraft," said Chodas. "The launch period is the period of time in days when everything is in the right place to get your mission off to the right start."For a mission like Juno, getting everything in the right place includes considering the size of the rocket and spacecraft, where our home planet -- and in particular Juno's launch pad -- is pointed at any moment, and its location in space relative to other celestial objects like Juno's final target, Jupiter.Juno is scheduled to launch aboard a United Launch Alliance Atlas V rocket from pad 41-C at the Cape Canaveral Air Force Station, Florida.The solar-powered spacecraft will orbit Jupiter's poles 33 times to find out more about the gas giant's origins, structure, atmosphere and magnetosphere and investigate the existence of a solid planetary core.JPL manages the Juno mission for the principal investigator, Scott Bolton, of Southwest Research Institute in San Antonio.The Juno mission is part of the New Frontiers Program managed at NASA's Marshall Space Flight Center in Huntsville, Alaska. Lockheed Martin Space Systems, Denver, built the spacecraft.

BEIJING, July 26 (Xinhuanet) -- Some forms of medical research involving animals containing human material should be more tightly regulated, a report warned.The warning was issued on Friday by an expert working group from the Academy of Medical Sciences in Britain.The report suggested the ban of the use of animal cells that can produce human sperm or egg cells. "We don't want scientists to cause problems for the future by overstepping the mark of what is publicly acceptable," said Professor Robin Lovell-Badge, a member of the expert working group.The controversy partly originated from a medical research in Britain. Three years ago, the researchers produced human embryos with the nucleus hollowed cow eggs, according to the Associated Press."This is a complex research area and there should be an ongoing dialogue between scientists, regulators and the wider public to address emerging issues." said Martin Bobrow, a professor of medical genetics at the University of Cambridge.

WASHINGTON, July 26 (Xinhua) -- The District of Columbia Department of Health (DOH) in the U.S. announced Tuesday that it has positively identified the West Nile Virus in mosquito samples in the District.This is the first time this summer the West Nile Virus has been identified in the U.S. capital."Residents should take caution as mosquitoes have the potential to transmit West Nile Virus to humans, and it is important for residents to take the necessary steps to avoid contracting the virus," DOH said in a statement.West Nile Virus is mainly an infection of birds, but on occasions an infected mosquito may spread it to humans. The virus is not transmitted directly from birds to humans and the risk of infection is low. In human infections, the virus generally causes no symptoms, or may cause mild flu-like symptoms.Senior citizens and people with weak immune systems are considered high risk for suffering the worst from the disease, officials said."People with a higher risk of infection should wear long- sleeved shirts, long pants, and apply insect repellent with DEET or other mosquito repellents to exposed skin according to manufacturer's directions. For children, they should use a product with DEET concentration of less than 30 percent," DOH said.