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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.

SAN FRANCISCO, Sept. 27 (Xinhua) -- Apple on Tuesday announced an invitation-only special event featuring iPhone on Oct. 4, 2011.With a simple headline reading "Let's talk iPhone," the invitation said that there will be an "executive presentation at 10 a.m.." This could be the first big product introduction by the newly installed Chief Executive Officer Tim Cook after he took over the reins of Apple from Steve Jobs in August.The event, which will be held at Apple campus in Cupertino, California, has long been reported to be the introduction of iPhone 5, the next generation iPhone.According to U.S. media reports, the iPhone 5 is expected to have revamped hardware design with a larger screen, a higher resolution camera and a faster dual-core A5 chip on which the iPad 2 runs. Apple is also reported to release a low-cost and contract- free iPhone model bundled with its cloud computing service iCloud.

WASHINGTON, July 10 (Xinhua) -- U.S. space shuttle Atlantis docked with the International Space Station on Sunday morning after nearly two days of flight.Commander Christopher Ferguson guided space shuttle Atlantis to a docking with the station at 11:07 a.m. EDT (1507 GMT) when the two spacecrafts were flying 240 miles up over east of New Zealand, according to NASA.This was the 12th and final time Atlantis docked to the space station. It was the 46th shuttle docking to a space station, nine to the Russian Mir station and 37 to the International Space Station.The space shuttle Atlantis is seen with part of the structure of the International Space Station in the foreground and the earth in the background as it approaches the station for docking in this still image from NASA TV July 10, 2011. The shuttle and station crews will open hatches and hold the traditional welcome ceremony at about 1:19 p.m. EDT (1719 GMT). The combined crew of 10 will begin more than a week of docked operations, transferring vital supplies and equipment to sustain station operations once the shuttles are retired.Atlantis lifted off on Friday morning from Kennedy Space Center in Florida, on the 135th and final flight in NASA's shuttle program.It is the 33rd voyage for Atlantis. Its return to the earth later this month will mark the end of the 30-year shuttle program.

JAKARTA, Sept. 21 (Xinhua) -- Comprehensive efforts are needed to save coral reefs as their living compound is prone to environmental damage, an Indonesian expert told Xinhua in an exclusive interview on Tuesday.Nurul Dhewani Mirah Sjafrie, coordinator of Coral Reef Information and Training Center (CRITC) for western Indonesia at the Indonesian Science Institute, the government think-tank institution, said that currently only more than five percent of coral reefs in Indonesia are in "excellent condition.""Based on monitoring of the thousands of observation stations we have, the rest are in damage, bad and moderate condition," Sjafrie said in her office.She said that it is not impossible to increase the number as long as all people are aware of the importance to save coral reefs."People should be aware that coral reefs live in sea with warm enough temperature of 18-25 Celsius degree with certain level of brightness, among others. If the requirements are fulfilled, we can see coral reef growing safely," said Sjafrie.She also said it needs upstream-to-downstream arrangement to support the efforts."For example, in western Indonesia, we have many big rivers. If illegal logging practice keeps continuing, it will cause sedimentation in the sea. It means there is a decreasing quality. So, coral reef salvation is not only conducted in ocean," Sjafrie said.She also expressed concern that many people dump garbage in rivers."They throw their garbage in plastic bags. For plastic only, it takes 100 years to be completely decomposed. Let's say 10-15 percent of our people do the malpractice everyday, you can imagine how many garbage entering the sea," she said.Sjafrie said that the key to guard coral reef sustainability is in human habit."Coral reef destruction could be caused by nature such as tsunami, earthquake, crown torn (Acanthaster plancii) that consumes coral reefs. But the biggest factor is human with their destructive fishing using bombs," she said.According to Sjafrie, people do the practice with three causes, namely ignorance, needs and greed.She added that efforts have been conducted by the government, private sector and non governmental organizations (NGOs) to save coral reefs."We have a program called the CORMAP of Coral Reef Rehabilitation and Management Program. The government uses instrument of National Program of People Empowerment while NGOs do their part. If we could combine the actions, we could reach the same goal," she said.She added that the government train people to be productive by providing skills and in the same time, her organization and NGOs socialize and campaign the importance of coral reefs."When people have better jobs and activities and they are equipped with the awareness, they will do positive thing and stop destroying the sea," Sjafrie said.

SAN FRANCISCO, June 13 (Xinhua) -- Social networking giant Facebook will likely go public in the first quarter of 2012 with a valuation that could top 100 billion U.S. dollars, U.S. media reported on Monday.In a report, CNBC quoted people familiar with the matter as saying that Facebook could submit filing to register its securities with the U.S. Securities and Exchange Commission (SEC) as early as October or November this year.People who are on Wall Street and track this information told the business news television channel that they think the Facebook initial public offering (IPO), if and when it happens could value the company of more than 100 billion dollars.A factor in the company's IPO timing is the SEC's requirement that companies must disclose financial information if they have more than 500 private investors."The company has until the end of April 2012 to disclose their financials, but they may just want to get ahead of that by doing a formal initial public offering, I'm told. And that could happen in the first quarter of the year," said CNBC Wall Street reporter Kate Kelly.Facebook is also facing internal pressure as employees have not been permitted to sell their private shares on the secondary market since last spring. An IPO would make it easier for employees to monetize their shares, said Kelly, citing sources.Facebook shares have been traded in private markets such as Sharepost.com, which puts the social networking company's valuation at 85 billion dollars.Meanwhile, latest data show that Facebook is losing users last month in the United States, Canada and several European countries, indicating that the company could have hit the limits of expansion in its mature markets.