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CANBERRA, Aug. 17 (Xinhua) -- Australian scientist on Wednesday said his international research team has discovered the trick on how butterfly learn to change its wing pattern to avoid being eaten by birds.The Amazonian butterfly, Heliconius numata, has learnt to carry out a single genetic switch to alter its wing pattern so it appears to be another bad-tasting butterfly that birds will avoid.Dr. Siu Fai (Ronald) Lee from the Department of Genetics and Bio21 Institute at Australia's University of Melbourne was part of the international research team, which was led by scientists at Centre National de la Recherche Scientifique (CNRS) and the University of Exeter in United Kingdom.Dr. Lee said the historical mystery had puzzled researchers for decades."Charles Darwin was puzzled by how butterflies evolved such similar patterns of warning coloration," Dr. Siu Fai (Ronald) Lee from the Department of Genetics and Bio21 Institute at the University of Melbourne told Western Australia Today."We have now solved this mystery, identifying the region of chromosome responsible for changing wing pattern."He said the research team identified a genetic switch known as a supergene, which allowed the butterfly to morph into several different forms, allowing one species to mimic another."It is amazing that by changing just one small region of the chromosomes, the butterfly is able to fool its predators by mimicking a range of different butterflies that taste bad," he said."The butterflies rearrange this supergene DNA like a small pack of cards, and the result is new wing patterns. It means that butterflies look completely different but have the same DNA."There are other butterflies doing similar tricks, but this is the most elegant one."I was just fascinated by how elegant they were."He said the discovery proves that small chromosomal changes can preserve successful gene combinations, and thus help a species to adapt.The findings of the study are published on August 14 in the international journal Nature.

LOS ANGELES, July 22 (Xinhua) -- Two teams of astronomers have discovered the largest and farthest reservoir of water ever detected in the universe, NASA's Jet Propulsion Laboratory (JPL) said on Friday.The water, equivalent to 140 trillion times all the water in the world's ocean, surrounds a huge, feeding black hole, called a quasar, more than 12 billion light-years away, according to JPL in Pasadena, California."The environment around this quasar is very unique in that it's producing this huge mass of water," said Matt Bradford, a scientist at JPL. "It's another demonstration that water is pervasive throughout the universe, even at the very earliest times. "This artist's concept illustrates a quasar, or feeding black hole, similar to APM 08279+5255, where astronomers discovered huge amounts of water vapor. Gas and dust likely form a torus around the central black hole, with clouds of charged gas above and below. X-rays emerge from the very central region, while thermal infrared radiation is emitted by dust throughout most of the torus. While this figure shows the quasar's torus approximately edge-on, the torus around APM 08279+5255 is likely positioned face-on from our point of view.A quasar is powered by an enormous black hole that steadily consumes a surrounding disk of gas and dust. As it eats, the quasar spews out huge amounts of energy. Both groups of astronomers studied a particular quasar called APM 08279+5255, which harbors a black hole 20 billion times more massive than the sun and produces as much energy as a thousand trillion suns.Astronomers expected water vapor to be present even in the early, distant universe, but had not detected it this far away before. There's water vapor in the Milky Way, although the total amount is 4,000 times less than in the quasar, because most of the Milky Way's water is frozen in ice. Water vapor is an important trace gas that reveals the nature of the quasar. In this particular quasar, the water vapor is distributed around the black hole in a gaseous region spanning hundreds of light-years in size (a light-year is about six trillion miles).Its presence indicates that the quasar is bathing the gas in X- rays and infrared radiation, and that the gas is unusually warm and dense by astronomical standards, JPL said.Although the gas is at a chilly minus 63 degrees Fahrenheit ( minus 53 degrees Celsius) and is 300 trillion times less dense than Earth's atmosphere, it's still five times hotter and 10 to 100 times denser than what's typical in galaxies like the Milky Way, said JPL.Measurements of the water vapor and of other molecules, such as carbon monoxide, suggest there is enough gas to feed the black hole until it grows to about six times its size, JPL said.Whether this will happen is not clear, the astronomers say, since some of the gas may end up condensing into stars or might be ejected from the quasar.Bradford's team made their observations starting in 2008, using an instrument called "Z-Spec" at the California Institute of Technology's (Caltech's) Submillimeter Observatory, a 33-foot (10- meter) telescope near the summit of Mauna Kea in Hawaii. Follow-up observations were made with the Combined Array for Research in Millimeter-Wave Astronomy (CARMA), an array of radio dishes in the Inyo Mountains of Southern California.The second group, led by Dariusz Lis, senior research associate in physics at Caltech and deputy director of the Caltech Submillimeter Observatory, used the Plateau de Bure Interferometer in the French Alps to find water. In 2010, Lis's team serendipitously detected water in APM 8279+5255, observing one spectral signature.Bradford's team was able to get more information about the water, including its enormous mass, because they detected several spectral signatures of the water, according to JPL.

WASHINGTON, June 6 (Xinhua) -- A new University of Missouri study shows that the exposure to the controversial chemical Bisphenol A (BPA) through diet has been underestimated by previous lab tests.The findings were published on Monday in Environmental Health Perspectives.In the study, researchers compared BPA concentrations in mice that were given a steady diet supplemented with BPA throughout the day, compared to the more common lab method of single exposure, and found an increased absorption and accumulation of BPA in the blood of the mice.The authors continuously exposed the mice to BPA through their feed, which is considered the primary route of exposure to this chemical in animals and humans. In previous studies examining the effects of BPA, mice were exposed to BPA only through a one-time administration.Following the exposure through the diet, a significantly greater increase in the active form of BPA, which is the greatest threat as it is the form that can bind to sex steroid receptors and exert adverse effects, was absorbed and accumulated in the animals."People are primarily and unknowingly exposed to BPA through the diet because of the various plastic and paper containers used to store our food are formulated with BPA," said Cheryl Rosenfeld, associate professor in biomedical sciences and corresponding lead author. "We know that the active form of BPA binds to our steroid receptors, meaning it can affect estrogen, thyroid and testosterone function. It might also cause genetic mutations. Thus, this chemical can hinder our ability to reproduce and possibly cause behavioral abnormalities that we are just beginning to understand."The study notes that more than eight billion pounds of BPA are produced every year, and more than 90 percent of people in the United States have measurable amounts of BPA in their bodies."When BPA is taken through the food, the active form may remain in the body for a longer period of time than when it is provided through a single treatment, which does not reflect the continuous exposure that occurs in animal and human populations," said Rosenfeld. "We need to study this further to determine where the ingested BPA becomes concentrated and subsequently released back into the bloodstream to be distributed throughout the body."

BEIJING, Sept. 2 (Xinhuanet) -- Firefighters who worked in the wreckage of the World Trade Center in 2001 were 19 percent more likely to develop cancer than those who were not there, according to a study.The study, published Thursday in the British medical journal The Lancet, surveyed cancer occurrence in nearly 10,000 male firefighters in the seven years after Sept. 11, 2001. (There were too few women to create a meaningful sample size.)The 9/11 attacks occurred on Tuesday, Sept. 11, 2001. As a result, the World Trade Center collapsed, and nearly 3,000 Americans killed. Among the 2,753 victims killed in the World Trade Center were 343 firefighters.There were 263 cancer cases in the exposed population, showing a cancer rate 19 percent higher than that of the group not exposed.The study indicated that cancers like melanoma, non-Hodgkin’s lymphoma, thyroid and prostate cancer occurred more frequently among exposed firefighters than in the general population. But occurrences of lung cancer did not increase.The findings “provide information that there may be a significant cancer risk for these people”, said Dr. James Melius, the administrator of the New York State Laborers’ Health and Safety Trust Fund and one of the peer reviewers of the study.But the results were far from conclusive. “This is not an epidemic,” said Dr. David J. Prezant, a lead researcher and the chief medical officer for the New York Fire Department.

XI'AN, Sept. 18 (Xinhua) -- At least 12 people were killed and 22 others missing over the weekend in rain-triggered landslides in northwestern Shaanxi Province, local officials said.As of 5:30 p.m. Sunday, rescuers had retrieved 10 bodies from beneath the rocks and mud in Baqiao District of the provincial capital of Xi'an, while another five were injured, said Zhu Zhisheng, vice mayor of Xi'an, who was at the site.Another 22 people remained missing, Zhu said, adding the injured were hospitalized and in stable condition.The landslide around 2 p.m. Saturday unleashed about 100,000 cubic meters of rock and mud down the mountain, engulfing a brick factory and destroying part of a nearby ceramics factory in the suburban district of Xi'an.Rescuers found four bodies on Saturday night and six others were retrieved on Sunday.More than 700 police, firefighters and local residents joined the rescue which went on Sunday night.However, the rescue was hampered by three ensuing slides between 10 a.m. and 11 a.m. Sunday as heavy rains continued slashing the city.About 10,000 cubic meters of newly-triggered rock and mud roared down to the site, forcing rescuers to suspend searching temporarily.Heavy downpours in the province also caused havoc in other areas.A heavy rainfall on Saturday night triggered a landslide that buried a residential house in the suburban district of Jintai in Baoji City, some 175 km to the west of Xi'an.Two people were dug out but later died after they were rushed to a nearby hospital, the municipal government of Baoji said in a statement Sunday.The downpours also brought a landslide in the same district early Sunday morning. Three people were saved and sent to a local hospital, according to the statement.The three wounded were in stable condition, doctors at the hospital said.