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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.

BERLIN, June 17 (Xinhua) -- German authority said on Friday first case of human spreading deadly E. coli is detected, as death toll increases to 39 worldwide.A woman working in a kitchen of a catering company was infected by E. coli from sprouts, though she didn't fall ill immediately, said Harald Kehlborn, a spokesman for the consumer protection ministry of German state Hesse.Then she spread E. coli unconsciously to another 20 people through the food she prepared, said Kehlborn.The woman later developed serious complication of hemolytic- uremic syndrome (HUS), which causes failure of kidney and nervous system.According to the data of the Robert Koch Institute, Germany's national disease control centre, the number of people who are infected has reached 3,408 in Germany and 798 people have fallen into HUS, while the infection speed is slowing down.

NEW YORK, Aug. 19 (Xinhua) -- U.S. crude oil price edged down on Friday, ending the week with a 3.65-percent loss, the fourth straight drop in the week.With absence of major macro-economic news, crude prices on Friday mainly followed the dollar's steps. As the dollar dipped to its historic low against the Japanese yen while dropping also against the euro, oil rallied for most of the trading session.But in the last trading hour, crude turned negative because the dollar bounced back from low and the U.S. stocks turned to red. The dollar index, tracking the greenback's performance against a basket of currencies, fell 0.4 percent.Crude prices fell sharply on Thursday as fears of a double-dip recession triggered sell-off of riskier assets. WTI dropped nearly 6 percent. On Friday, the markets seemed to start calming down. But for the week, it still posted a fall of 3.65 percent.Light, sweet crude for September delivery fell moderately 12 cents, or 0.15 percent to settle at 82.26 dollars a barrel on the New York Mercantile Exchange after trading from 79.17 to 83.55 dollars.But in London, Brent crude for October delivery gained 1.63 dollars, or 1.52 percent to close at 108.62 dollars a barrel. For this week, it gained 59 cents, or 0.55 percent.

SAN FRANCISCO, Sept. 2 (Xinhua) -- A late-season potato blight has been detected on farms in Alaska, only the fourth time the disease appear in the U.S. state since 1995, local media reported on Friday.The disease was found this week in the fields of potato producers in cities of Delta Junction and Palmer, according to the Fairbanks Daily News-Miner, Alaska's second largest daily newspaper.Farmers in both fields are working to prevent the spread of the blight, a fungus-like disease that can kill plants in the field or cause potatoes to rot in storage, the newspaper reported.Growers have been asked to kill all affected plants within 100 feet, and plant samples from both sites will be examined to identify what type of late blight is involved.Experts said that blight can be controlled through the use of fungicides, but the cool, damp weather this summer in the areas has created an ideal environment for the disease to spread.Although Alaska's potato crop is tiny compared to other U.S. states, it has been viewed as a possible global source of seed potatoes in recent years because it is largely free of disease.A local university has explored partnerships with Chinese growers to export certified seed potatoes, noted the Fairbanks Daily News-Miner report.

SAN FRANCISCO, Aug. 22 (Xinhua) -- Hewlett-Packard (HP) on Monday unveiled a new business desktop computer, days after the world's largest personal computer (PC) maker announced its plan to sell its PC business.The company said the new model, HP Compaq 8200 Elite All-in-One Business Desktop, is the industry's first all-in-one PC that integrates Intel's second-generation Core vPro technology, which can deliver up to 40 percent better performance, 15 percent faster hard drive access and reduced downtime via remote information technology management."Another industry first in our Elite desktop family demonstrates our commitment to engineering excellence and underscores our global leadership in secure, enterprise computing, " Jeff Groudan, HP's director of commercial desktop marketing, said in a statement.HP said the new computer is available now in the United States. It starts at the price of 999 U.S. dollars, and comes with a standard three-year warranty.Last Thursday the company announced that it is considering a full or partial separation of its PC business through a spin-off or other transactions, a process that HP estimates may take about 12 to 18 months.

来源：资阳报