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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. 1 (Xinhua) -- Senior Chinese official Zhou Yongkang Tuesday called on law enforcement personnel to take more preventive measures against crime and accidents during the Lunar New Year holiday.Zhou, a Standing Committee member of the Political Bureau of the Communist Party of China (CPC) Central Committee, visited community security personnel, a district court, and police patrolling downtown Beijing Tuesday.He also visited a police station that is responsible for keeping public order in the area surrounding the central leadership compound of Zhongnanhai.During his visits, Zhou, who also heads the Commission for Political and Legal Affairs of the CPC Central Committee, said China was seeing the travel peak for the Spring Festival and some regions were suffering icy weather and lingering drought.He asked the police to take effective measures in traffic control and fire-fighting work, and maintain social order during the holiday season.He commended the practice of deploying special police to patrol the surrounding areas of the Tiananmen Square in central Beijing, saying it could deter crime and enable quick responses to emergencies.During his visit to the district court, Zhou warned there were still "many social conflicts."He asked local courts to solve social conflicts more effectively, promote innovative social management and law enforcement in a just and clean manner.The Spring Festival, or Chinese lunar New Year, is the most important festival for Chinese. It falls on Feb. 3 this year.

SINGAPORE, April 21 (Xinhua) -- Singapore's first locally-built satellite has been officially launched from a space center in India after a four-year delay, Singapore media reported on Thursday.The 105 kg fridge-size X-Sat was one of three riding on Isro's Polar Satellite Launch Vehicle (PSLV-C16) from the Satish Dhawan Space Center in India on Wednesday. It will be used to take photographs to measure soil erosion and environmental changes on earth, local daily Straits Times said.The launch at 12:42 p.m. on Wednesday was the 18th successful lift-off since the maiden flight of PSLV in 1994.The satellite was designed and built by Singapore's Nanyang Technological University and Singapore's defense research body DSO National Laboratories.Now in orbit, the satellite is establishing communication contact with the ground control in Nanyang Technological University, a process that is likely to take up to a week.The launch capped more than nine years of hard work by scientists and engineers. It also makes Singapore one of the first countries in Southeast Asia to have its own satellite in space. Previous satellite launched by Singapore involved construction efforts by foreign companies.

CARACAS, March 30 (Xinhua) -- The number of confirmed cases of the A/H1N1 influenza in Venezuela has risen to 482 this year, Health Minister Eugenia Sader said on Wednesday.According to the latest report, the state of Merida in southeastern Venezuela has 189 A/H1N1 influenza cases, the biggest number ever reported, which was followed by the Capital District of Caracas with 112 cases. The other 181 cases were confirmed in 17 of 24 Venezuelan states.The first case for this year was reported in Merida earlier this month.Sader said that the Venezuelan government was trying to prevent the spread of the disease. Some 3 million people have been vaccinated against the virus.Three patients infected with the A/H1N1 influenza virus have died in the country this year, according to Sader.The A/H1N1 influenza can cause deadly pneumonia if it is not treated early.

来源：资阳报