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Robots perform a dance in a competition in Mudanjiang, northeast China's Heilongjiang Province, July 24, 2011. A nationwide robot competition was kicked off in the city on Sunday, with participants from 50 colleges and universities

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, Sept. 28 (Xinhua) -- China's top economic planner announced Wednesday that it will raise the minimum purchase prices for wheat from farmers in 2012 to boost grain output.The move "aims to protect farmers' enthusiasm to grow grains and further stimulate grain production," the National Development and Reform Commission (NDRC) said in a statement.The minimum purchase price for white wheat in the country's major wheat-producing areas will be increased to 102 yuan (16 U.S. dollars) per 50 kg, up 7 yuan from the 2011 price, said the NDRC.It said the minimum purchase prices for red and mixed wheat will both rise 9 yuan to 102 yuan per 50 kg next year.Wheat is one of China's major grains, which feeds its population of 1.3 billion people mainly with domestically-produced grains.A stable food supply is crucial to China's efforts to check inflation, as food prices account for about a third of the weighting in its consumer price index (CPI) calculation, a main gauge of inflation.China's CPI rose to a 27-month year-on-year high of 6.5 percent in July and weakened slightly to 6.2 percent in August.The country's grain output rose 2.9 percent last year to 546.41 million tonnes, marking the seventh consecutive year of output growth.The Ministry of Agriculture expects the output to reach a record high of 550 million tonnes this year.

来源：资阳报