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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, April 6 (Xinhua) -- U.S. researchers have discovered two genes in which variation affects intake of caffeine, the most widely consumed stimulant in the world, according to a report described Wednesday in the open-access journal PLoS Genetics.A team of investigators from the National Cancer Institute, Harvard School of Public Health, Brigham and Women's Hospital, and the University of North Carolina at Chapel Hill examined genetic variation across the entire genome of more than 47,000 individuals from the U.S.They found the genes -- CYP1A2, which has previously been implicated in the metabolism of caffeine, and AHR, involved in the regulation of CYP1A2, played roles in regulating intake of caffeine. Individuals with the highest-consumption genotype for either gene consumed 40 mg more caffeine than those with the lowest-consumption genotype, equivalent to the amount of one-third cup of caffeinated coffee, or one can of cola.Caffeine is implicated in numerous physiological and medical conditions; it affects sleep patterns, energy levels, mood, and mental and physical performance. The identification of genes that have an impact on daily consumption offers opportunities to better understand these conditions. Further exploration of the identified genetic variants may provide insight into the speed of caffeine metabolism, how long caffeine circulates in the blood, or how strong the physiological effects of consuming a given amount of caffeine are.

NICOSIA, March 8 (Xinhua) -- Cypriot geneticists have reported a non-invasive Down's Syndrome test that could possibly replace the risky amniocentesis procedure now in use.A team of researchers at the Cyprus Institute of Neurology and Genetics reported in Nature Medicine journal that the new test involves only a small quantity of blood taken from the mother's arm, which is analyzed to detect DNA differences between the mother and the fetus.Philippos Patsalis, medical director of the institute, said Tuesday the new method eliminates dangers involved with amniocentesis testing, which involves sampling amniotic fluid by inserting a hollow needle into the mother's uterus.At present, only women belonging to high risk groups, including older women, are tested for Down's Syndrome, which is the most common genetic cause of mental retardation.Patsalis, who led the study, said the new method would be made available to the medical community after clinical tests are concluded world-wide on 1,000 women within two years.

BEIJING, March 11(Xinhuanet)-- People with more fat around their waist, often known as “apple shape”, may not have a greater risk of heart attack than those with fatter bottoms and hips, according to a new study published in Lancet as quotted by media reports Friday.This study funded by the Medical Research Council and British Heart Foundation, reviewed 220,000 individual records from 17 countries and monitored the occurrence of heart attacks or strokes based on body mass index (BMI) versus waist-hip circumference. It found that people with "apple-shaped" obesity were at a higher risk of having heart risks compared to those with general obesity as assessed by their BMI.  This contradicts previous claims that "apple shaped" bodies were three times more likely to suffer heart attacks than those with more generally distributed fat.But experts warn obesity is still bad for the heart, no matter where the fat is, and they argue there is confusion about the best way to measure it. "Regardless of how you measure it, being obese is bad for your heart. This study suggests that measuring your waist is no better than calculating your BMI but it's not time to throw away the tape measure just yet, “Dr Mike Knapton, associate medical director at the British Heart Foundation said."We tend to underestimate our body shape and size, so measuring our waist or checking our BMI are both quick and easy ways we can check our health at home."Besides, he also listed some other heart risk factors that we need to think about too, such as blood pressure, cholesterol, diabetes and smoking.

LOS ANGELES, March 27 (Xinhua) -- Walnuts have a combination of more healthful antioxidants and higher quality antioxidants than any other nut, U.S. researchers have found.Study findings were presented on Sunday at the 241st National Meeting & Exposition of the American Chemical Society (ACS) in Anaheim, Southern California.Nuts contain plenty of high-quality protein that can substitute for meat, vitamins and minerals, dietary fiber, and are dairy- and gluten-free, ACS researchers said in the study.Moreover, nuts contain healthful polyunsaturated and monosaturated fats rather than artery-clogging saturated fat, according to the study.The researchers based their conclusion on analysis of antioxidants in nine different types of nuts: walnuts, almonds, peanuts, pistachios, hazelnuts, Brazil nuts, cashews, macadamias and pecans.They found that walnuts have the highest levels of antioxidants, with plenty of high-quality protein that can substitute for meat, vitamins and minerals, dietary fiber, and are dairy- and gluten-free.The latest study adds more evidence that walnuts are top nuts for heart-healthy antioxidants, the researchers said.Previous studies showed that regular consumption of small amounts of nuts or peanut butter can decrease the risk of heart disease, certain kinds of cancer, gallstones, Type 2 diabetes, and other health problems.But the latest study is the first to compare both the amount and quality of antioxidants found in different nuts."Walnuts rank above peanuts, almonds, pecans, pistachios and other nuts," said Joe Vinson, Ph.D., who led the latest study."A handful of walnuts contains almost twice as much antioxidants as an equivalent amount of any other commonly consumed nut. But unfortunately, people don't eat a lot of them. This study suggests that consumers should eat more walnuts as part of a healthy diet."