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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."

WASHINGTON, May 11 (Xinhua) -- Johns Hopkins University researchers have demonstrated that human liver cells derived from adult cells coaxed into an embryonic state can engraft and begin regenerating liver tissue in mice with chronic liver damage.The work, published Wednesday in the journal Science Translational Medicine, suggests that liver cells derived from so- called "induced-pluripotent stem cells (iPSCs)" could one day be used as an alternative to liver transplant in patients with serious liver diseases, bypassing long waiting lists for organs and concerns about immune system rejection of donated tissue."Our findings provide a foundation for producing functional liver cells for patients who suffer liver diseases and are in need of transplantation," says Yoon-Young Jang, assistant professor of oncology at the Johns Hopkins Kimmel Cancer Center. "iPSC-derived liver cells not only can be generated in large amounts, but also can be tailored to each patient, preventing immune-rejection problems associated with liver transplants from unmatched donors or embryonic stem cells." A microsopic view shows human embryonic stem cells in various stages of differentiation into liver cells in this photo taken at Stanford University and released by the California Institute for Regenerative Medicine, March 9, 2009iPSCs are made from adult cells that have been genetically reprogrammed to revert to an embryonic stem cell-like state, with the ability to transform into different cell types. Human iPSCs can be generated from various tissues, including skin, blood and liver cells.Although the liver can regenerate in the body, end-stage liver failure caused by diseases like cirrhosis and cancers eventually destroy the liver's regenerative ability, Jang says. Currently, the only option for those patients is to receive a liver organ or liver cell transplant, a supply problem given the severe shortage of donor liver tissue for transplantation. In addition, mature liver cells and adult liver stem cells are difficult to isolate or grow in the laboratory, she says. By contrast, iPSCs can be made from a tiny amount of many kinds of tissue; and the embryonic stem- like iPSCs can grow in laboratory cultures indefinitely.For the study, Jang and colleagues generated human iPSCs from a variety of adult human cells, including liver cells, fibroblasts ( connective tissue cells), bone marrow stem cells and skin cells. They found that though the iPSCs overall were molecularly similar to each other and to embryonic stem cells, they retained a distinct molecular "signature" inherited from the cell of origin.

BEIJING, Feb. 28 (Xinhua) -- Construction began on China's first low-speed maglev line Monday in Beijing, a project that will make China only the second country with a low-speed maglev line after Japan.The project marked China's ability to industrialize low-speed maglev technologies, said Chang Wensen, father of China's maglev technology and professor at the National University of Defense Technology.The 10-kilometer line runs from Shimenying Station in west Beijing's Mentougou District to Pingguoyuan Station in the Shijingshan District.The line, a section of Line S1 on the Beijing subway network, is expected to be completed in 2013 with a designed speed of 100 to 120 km per hour.China's research of maglev technologies was started in the 1980s by a team led by Chang Wensen. A 204-meter test line in central China's Hunan Province and a 1.5-km test line in north China's Hebei Province were built jointly by Beijing Maglev Technology Development Co., Ltd. and National University of Defense Technology.The intensity of the magnetic field had been tested as safe, according to a test report of Institute of Electrical Engineering, Chinese Academy of Sciences.The cost of the low-speed maglev line was estimated at 300 million yuan (4.6 million U.S. dollars) per kilometer, slightly more than light rail, but cheaper than the subway, which cost more than 600 million yuan a kilometer, said Li Jie, director of technology research center of National University of Defense Technology.The technology was also under consideration for Line 8 of the subway network in Shenzhen, in south China's Guangdong Province, said Liu Zhiming, board chairman of Beijing Maglev Technology Development Co., Ltd.."If Shenzhen adopts the technology, Line 8 will be China's second low-speed maglev line," he said.The world's first low-speed maglev line, at 8.9 km long, was completed in Japan in March 2005.Maglev, short for magnetic levitation, technology uses a large number of magnets to lift and propel a vehicle, making it faster, quieter and smoother than conventional wheeled transport systems.High-speed maglev vehicles can reach speeds of 450 km per hour and are usually used in long distance transportation, while low-speed maglev lines are usually used in short distance transportation.Construction also began on another seven lines on the Beijing subway network Monday.With an investment of 82 billion yuan (12 billion U.S. dollars), the eight lines will total 113.7 km in length and are expected to open from 2013 to 2015.Beijing has 16 lines under construction.

BEIJING, Feb. 1 (Xinhua) -- Two Air China passenger planes carrying 457 Chinese citizens stranded in Egypt are due to arrive in Beijing early morning on Wednesday.The planes took off from the Cairo International Airport respectively at 11:16 and 15:32 local time (0916 and 1332 GMT) on Tuesday.The Civil Aviation Administration of China (CAAC), the nation's aviation authority, said Tuesday it was doing its best to organize flights to Egypt to bring home Chinese tourists stranded in the North African nation.China has arranged six flights to fly stranded Chinese nationals home, the CAAC said in a statement posted on its website.

BEIJING, Feb. 8 (Xinhua) -- China respects the results of south Sudan referendum, which was announced Monday, Chinese Foreign Ministry spokesman Hong Lei said Tuesday.Hong made the remarks in a statement concerning China's view on the results of the referendum."China respects the choice of Sudan people and appreciates the unremitting efforts of both the north and the south to promote the peace process between the two sides," Hong Lei said."China hopes the two sides will continue to resolve controversial issues through dialogue and consultation in line with the principle of mutual understanding and mutual accommodation," Hong said."China expects full implementation of the Comprehensive Peace Agreement(CPA) as well as long peace and stability in Sudan."The referendum, conducted from Jan. 9 to 15, was a major condition of the CPA, which ended a two-decade civil war between the two sides.The South Sudan Referendum Commission Monday announced the final results of the referendum saying that 98.83 percent of the voters had voted for separation.