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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.

LOS ANGELES, June 4 (Xinhua) -- Pregnant women who eat high-fat diet may be more likely to have a higher rate of stillbirth, a new study suggests.Researchers at Oregon Health & Science University (OHSH) came to the conclusion after observing 24 pregnant Japanese macaques that ate either a diet comprising 32 percent calories from fat or a control diet with 14 percent fat calories for at least four years.The researchers found the monkeys that ate a high-fat diet experienced a significant decrease in blood flow from the uterus to the placenta, a reduction of 38 percent to 56 percent, and a rise in placental inflammation.This was the case regardless of whether the monkeys were obese or slender. The risk of stillbirth was further compounded, however, when the monkeys were obese with hyper-insulinemia, or pre-diabetes.A large order of McDonald's french fries are shown May 22, 2008. McDonald's has switched to cooking oils free of trans fats in all of its restaurants in the United States and Canada, Chief Executive Jim Skinner said on may 23Eating a high-fat diet decreases blood flow from the mother to the placenta, the temporary organ that nourishes the unborn fetus, thus raising the risk of stillbirth, the researchers explained.Because the placental structure of the Japanese macaque is very similar to that in humans, cause and effect can be better established, the researchers said.Additional studies are needed to determine exactly how a high- fat diet decreases placental blood flow, the researchers noted.This is the first study to explain exactly how a fatty diet contributes to stillbirth, the researchers said in the study appearing in the June edition of the journal Endocrinology.The researchers hope their work will inform expectant moms and their physicians about the inherent dangers of a high-calorie, high- fat diet."This study demonstrates that maternal diet during pregnancy has a profound influence on both placental and fetal development," said Antonio Frias, M.D., principal investigator and assistant professor of obstetrics and gynecology (perinatology/maternal-fetal medicine) in the OHSU School of Medicine."The high-calorie, high-fat diet common in our society has negative effects on placental function and may be a significant contributor to adverse pregnancy outcomes, such as stillbirth."Previous studies have shown that nearly all adverse outcomes during pregnancy -- abnormal fetal growth, preeclampsia, preterm labor and stillbirth -- are in some way associated with an abnormally developed, or damaged, placenta, the temporary organ that nourishes the unborn fetus.In addition, maternal obesity has been associated with placental inflammation and dysfunction and an increased risk of stillbirth.Taking these findings into account, the researchers hypothesized that eating a diet high in fat during pregnancy also may increase the risk of placental inflammation and the risk of stillbirth.The researchers said they plan to conduct further studies on the impact of dietary changes and diet supplementation on improving outcomes in both monkeys and humans.

BEIJING, Sept. 14 (Xinhuanet) -- Scientists had discovered the fossils of a new species of ancient carnivorous fish, National Geographic reported Monday.The newly-found ancient fish, "Laccognathus embryi", is a 1.8-meter-long predator, which was "waiting to lunge out to grab whatever was in front of it," said study co-author Ted Daeschler, a vertebrate zoologist at the Academy of Natural Sciences in Philadelphia, the U.S..It had a jaw filled with sharp teeth that were 1.5 inches long, the Journal of Vertebrate Paleontology described.The fish lived in the Devonian period, 415 to 360 million years ago, which "was a fish-eats-fish kind of world," Daeschler said. "There was a real arms race going. If you didn't have good armor on your body, you were very vulnerable.""It's not just finding the animal - it's also placing the animal in its evolutionary crucible," Daeschler added.Its closest living relative is the lungfish which can survive in the drought, scientists said.Scientists hope the finding can help in their study on the revolution of fishes as well as other species.

KUBUQI (Inner Mongolia), July 10 (Xinhuanet) -- Amos Nadai, ambassador of Israel to China, spoke highly of the desertification control efforts in the Kubuqi desert of China during an exclusive interview with Xinhuanet here Saturday. "It's a huge area, which is more than half of my country," Nadai said, "I see a lot of planting and it's very beautiful." Nadai was here for the 2011 Kubuqi International Desert Forum held in the Kubuqi Desert, Inner Mongolia of China. As a small country with half of its land being desert, Israel has to work very hard in desertification control and has accumulated a great deal of experience. However, Nadai praised China's efforts in learning new technologies applied in the Kubuqi desert. He said that China takes this very seriously and has developed really rapidly. "They are doing the right thing; they bring here every two years the best experts from all over the world, and they listened carefully," he said. Nadai said that he saw the way people here fight against desertification, develop tourism, boost the use of clean energy, and he was very impressed. That's why Israel is happy to cooperate with China in this field, Nadai said. He also introduced a long-term project that Israel has been working together with China in Xinjiang, which Israel introduces methods to the local farmers that can grow the same amount of crop by using 50 percent less of water. "The local people have learned everything that we can offer them and they can do it alone now," Nadai said. The ambassador, who was awarded the Honorary Citizenship of Chengdu City, the capital of Sichuan Province, Wednesday, said: "I am very very excited for that honor."