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WASHINGTON, May 2 (Xinhua) -- Rice originated in China, a team of U.S. genome researchers has concluded in a study tracing back thousands of years of evolutionary history through large-scale gene re-sequencing.Their findings, which appear Monday in the latest issue of the Proceedings of the National Academy of Sciences (PNAS), indicate that domesticated rice may have first appeared as far back as approximately 9,000 years ago in the Yangtze Valley of China. Previous research suggested domesticated rice may have two points of origin -- India as well as China.Asian rice, Oryza sativa, is one of world's oldest crop species. It is also a very diverse crop, with tens of thousands of varieties known throughout the world. Two major subspecies of rice -- japonica and indica -- represent most of the world's varieties. Sushi rice, for example, is a type of japonica, while most of the long-grain rice in risottos are indica.Because rice is so diverse, its origins have been the subject of scientific debate. One theory -- a single-origin model -- suggests that indica and japonica were domesticated once from the wild rice O. rufipogon.Another -- a multiple-origin model -- proposes that these two major rice types were domesticated separately and in different parts of Asia. The multiple-origin model has gained currency in recent years as biologists have observed significant genetic differences between indica and japonica, and several studies examining the evolutionary relationships among rice varieties supported more than domestication in both India and China.In the PNAS study, the researchers re-assessed the evolutionary history, or phylogeny, of domesticated rice using previously published datasets, some of which have been used to argue that indica and japonica rice have separate origins. Using more modern computer algorithms, however, the researchers concluded these two species have the same origin because they have a closer genetic relationship to each other than to any wild rice species found in either India or China.In addition, the study's authors examined the phylogeny of domesticated rice by re-sequencing 630 gene fragments on selected chromosomes from a diverse set of wild and domesticated rice varieties. Using new modeling techniques, which had previously been used to look at genomic data in human evolution, their results showed that the gene sequence data was more consistent with a single origin of rice.In the study, the investigators also used a "molecular clock" of rice genes to see when rice evolved. Depending on how the researchers calibrated their clock, they pinpointed the origin of rice at possibly 8,200 years ago, while japonica and indica split apart from each other about 3,900 years ago. The study's authors pointed out that these molecular dates were consistent with archaeological studies.Archaeologists have uncovered evidence in the last decade for rice domestication in the Yangtze Valley beginning approximately 8, 000 to 9,000 years ago while domestication of rice in the India's Ganges region was around about 4,000 years ago."As rice was brought in from China to India by traders and migrant farmers, it likely hybridized extensively with local wild rice," explained New York University biologist Michael Purugganan, one of the study's co-authors. "So domesticated rice that we may have once thought originated in India actually has its beginnings in China."

BEIJING, Feb. 22 (Xinhua) -- Chinese Foreign Minster Yang Jiechi and his Austrian counterpart Michael Spindelegger held talks here on Tuesday, pledging to enhance bilateral ties through deeper cooperation.Yang hailed the remarkable development of bilateral ties since the two countries established diplomatic relations 40 years ago.He said both sides should see the 40th anniversary as a new starting point for maintaining traditional friendship, deepening political mutual trust, expanding cooperation and enhancing cultural exchanges, to strive for greater development of bilateral ties.He stressed that China appreciates the Austrian government's adherence to the one-China policy.For his part, Spindelegger said the Austrian side attaches great importance to developing ties with China and he hoped both sides will strengthen cooperation in various fields in a more pragmatic way.The two also exchanged views on some international and regional issues of common concern.

You can think of NASA's Discovery program as a sort of outer-space American Idol: every few years the agency invites scientists to propose unmanned planetary missions. The projects have to address some sort of fundamental science question, and (this is the tough part) they have to be relatively cheap to pull off — say, half a billion dollars or so. Then the proposals go through a grueling competition before judges who aren't as nasty as Simon Cowell but who are every bit as tough. The one left standing at the end gets the equivalent of a recording contract: NASA supplies the funding and the launch vehicle, and away the winner goes — to orbit Mercury, as the Messenger spacecraft is doing right now; or to rendezvous with a couple of asteroids, as the Dawn mission will start doing this July; or to smash into a comet on purpose, a feat achieved by Deep Impact in 2005, a mission not to be confused with the movie of the same name. Now it's time for the next contenders. NASA has just announced that the first round of the latest Discovery competition is over, with three entries out of 28 moving on to the finals. They are, in increasing distance from Earth: the Geophysical Monitoring Station (GEMS) lander, which would use seismometers to study the interior of Mars; the Comet Hopper, which would do just that, leaping from place to place across the surface of Comet 46P/Wirtanen to see how different parts of the tumbling body react to heating by the sun; and the Titan Mare Explorer (TiME), which would plop into a sea of liquid hydrocarbons on Saturn's moon Titan — the first oceangoing vessel ever to set sail on another world. If you had to come up with a theme that ties all three missions together, it would be "origins." The Titan explorer, for example, will be studying a place that — in a crude way, at least — resembles the early planet Earth at a time when life arose here. Titan, with a thick atmosphere and a bizarro-world form of weather featuring toxic winds and hydrocarbon rain, is home to a mix of complex chemistry, complete with organic molecules. The oceans provide a medium in which the molecules can move around and interact with each other. It's even conceivable, though clearly a long shot, that some form of microscopic life already exists on this frigid moon. The Mars lander, by contrast, would visit a place where the seas — plain water in this case — vanished long ago. But the mission of GEMS goes far deeper than that. By analyzing Marsquakes on the Red Planet, GEMS will try to get a handle on what the interior of Mars is like. Scientists don't currently know whether the planet's core is liquid, like Earth's, or solid, or some mushy consistency in between. It all depends on how efficiently Mars has cooled since it formed 4.5 billion years ago, and that depends in turn on the planet's internal structure. "That's the mission," says Bruce Banerdt, of NASA's Jet Propulsion Laboratory, the lead scientist for GEMS. "We want to understand how Mars was built." Along with sensitive seismographic equipment, GEMS will drill down about 20 ft. (6 m) with a thermometer-equipped probe, trying to figure out how quickly the temperature rises with depth. "That will let us extrapolate all the way down to the center," Banerdt says, "which will tell us how fast Mars is cooling."

BEIJING, Jan. 26 (Xinhua) -- China's civil affairs ministers visited survivors of last year's 7.1-magnitude Yushu earthquake and Zhouqu mudslide prior to China's lunar new year.Dou Yupei, vice minister of Civil Affairs, led a team to Yushu in northwest China's Qinghai Province to visit quake survivors and local cadres beginning on Sunday.Dou told Xinhua that quake survivors in Yushu now had access to food, clothing, safe drinking water, shelters and medical services, and the reconstruction of quake-damaged houses was well underway.Further, the ministry has distributed 45,000 cotton-padded tents to Yushu to house survivors during the extremely cold winter on the Qinghai-Tibet plateau.So far, 160,000 tents have been set up to assure that all survivors have a roof overhead, according to the ministry's statement issued Wednesday.Yushu was jolted by a 7.1-magnitude earthquake on April 14, leaving 2,200 people dead and 220,000 local residents affected.Another vice minister, Sun Shaocheng, visited survivors from a massive mudslide that left 1,700 people dead or missing in Zhouqu, Gansu province.To provide warm shelters to survivors, the Zhouqu county government invested three million yuan (455,000 U.S. Dollars) in renovating vacant school buildings or installing facilities in newly-built apartments.All survivors who previously had taken shelter in make-shift tents were relocated to these buildings before Oct. 13, according to the ministry's statement.

LOS ANGELES, May 5 (Xinhua) -- NASA has selected three planetary missions from which it will pick one potential mission to look at Mars' interior for the first time, NASA's Jet Propulsion Laboratory (JPL) announced on Thursday.The Mars mission, to be launched in 2016, would be led by JPL, according to the announcement.The other two missions would study an extraterrestrial sea on one of Saturn's moons; or study in unprecedented detail the surface of a comet's nucleus, said JPL in Pasadena, Los Angeles.The selected investigations could reveal much about the formation of our solar system and its dynamic processes, JPL said.Each mission will receive three million dollars to conduct its mission's concept phase or preliminary design studies and analyses, JPL said in a news release.After another detailed review in 2012 of the concept studies, NASA will select one to continue development efforts leading up to launch. The selected mission will be cost-capped at 425 million dollars, not including launch vehicle funding, according to JPL.NASA's Discovery Program requested proposals for spaceflight investigations in June 2010. A panel of NASA and other scientists and engineers reviewed 28 submissions."NASA continues to do extraordinary science that is re-writing textbooks," said NASA Administrator Charles Bolden. "Missions like these hold great promise to vastly increase our knowledge, extend our reach into the solar system and inspire future generations of explorers."

来源：资阳报