Geographic variation of human gut microbes tied to obesity

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People living in cold, northern latitudes have bacteria in their guts that may predispose them to obesity, according to a new study by researchers at the University of California, Berkeley, and the University of Arizona, Tucson.The researchers’ analysis of the gut microbes of more than a thousand people from around the world showed that those living in northern latitudes had more gut bacteria that have been linked to obesity than did people living farther south.The meta-analysis of six earlier studies was published this month in the online journal Biology Letters by UC Berkeley graduate student Taichi Suzuki and evolutionary biology professor Michael Worobey of the University of Arizona.”People think obesity is a bad thing, but maybe in the past getting more fat and more energy from the diet might have been important to survival in cold places. Our gut microbes today might be influenced by our ancestors,” said Suzuki, noting that one theory is that obesity-linked bacteria are better at extracting energy from food. “This suggests that what we call ‘healthy microbiota’ may differ in different geographic regions.”"This observation is pretty cool, but it is not clear why we are seeing the relationship we do with latitude,” Worobey said. “There is something amazing and weird going on with microbiomes.”To Worobey, the results are fascinating from an evolutionary biology perspective. “Maybe changes to your gut community of bacteria are important for allowing populations to adapt to different environmental conditions in lots of animals, including humans,” he said.Body size increases with latitudeSuzuki proposed the study while rotating through Worobey’s lab during his first year as a graduate student at the University of Arizona. Studies of gut microbes have become a hot research area among scientists because the proportion of different types of bacteria and Archaea in the gut seems to be correlated with diseases ranging from diabetes and obesity to cancer. In particular, the group of bacteria called Firmicutes seems to dominate in the intestines of obese people — and obese mice — while a group called Bacteroidetes dominates in slimmer people and mice.Suzuki reasoned that, since animals and humans in the north tend to be larger in size — an observation called Bergmann’s rule — then perhaps their gut microbiota would contain a greater proportion of Firmicutes than Bacteriodetes. While at the University of Arizona, and since moving to UC Berkeley, Suzuki has been studying how rodents adapt to living at different latitudes.”It was almost as a lark,” Woroby said. “Taichi thought that if Firmicutes and Bacteroidetes are linked to obesity, why not look at large scale trends in humans. When he came back with results that really showed there was something to it, it was quite a surprise.”Suzuki used data published in six previous studies, totaling 1,020 people from 23 populations in Africa, Europe, North and South America and Asia. …


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Mixed genes: Interactive world map of human genetic history reveals likely genetic impacts of historical events

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When individuals from different groups interbreed, their offspring’s DNA becomes a mixture of the DNA from each admixing group. Pieces of this DNA are then passed along through subsequent generations, carrying on all the way to the present day. Researchers from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, Oxford University and University College London (UCL) have now produced a global map detailing the genetic histories of 95 different populations across the world, spanning the last four millennia.The interactive world map that is accessible via the internet, details the histories of genetic mixing between each of the 95 populations across Europe, Africa, Asia and South America. It shows likely genetic impacts of historical events including European colonialism, the Mongol Empire, the Arab slave trade and European traders near the Silk Road mixing with people in China.The study, published this week in Science, is the first to simultaneously identify, date and characterise genetic mixing between populations. To do this, the researchers developed sophisticated statistical methods to analyse the DNA of 1490 individuals in 95 populations around the world. “DNA really has the power to tell stories and uncover details of humanity’s past,” said Simon Myers of Oxford University’s Department of Statistics and Wellcome Trust Centre for Human Genetics, co-senior author of the study. “Because our approach uses only genetic data, it provides information independent from other sources. Many of our genetic observations match historical events, and we also see evidence of previously unrecorded genetic mixing. For example, the DNA of the Tu people in modern China suggests that in around 1200CE, Europeans similar to modern Greeks mixed with an otherwise Chinese-like population. Plausibly, the source of this European-like DNA might be merchants travelling the nearby Silk Road.”The powerful technique, christened ‘Globetrotter’, provides insight into past events such as the genetic legacy of the Mongol Empire. …


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Oil composition boost makes hemp a cooking contender

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Scientists at the University of York today report the development of hemp plants with a dramatically increased content of oleic acid. The new oil profile results in an attractive cooking oil that is similar to olive oil in terms of fatty acid content having a much longer shelf life as well as greater heat tolerance and potentially more industrial applications.Researchers in the Centre for Novel Agricultural Products (CNAP) in the Department of Biology at York say that high oleic acid varieties are a major step towards developing hemp as a commercially attractive break crop for cereal farmers. The research is published in Plant Biotechnology Journal.Using fast-track molecular plant breeding, the scientists selected hemp plants lacking the active form of an enzyme involved in making polyunsaturated fatty acids. These plants made less poly-unsaturated fatty acids and instead accumulated higher levels of the mono-unsaturated oleic acid. The research team used conventional plant breeding techniques to develop the plants into a “High Oleic Hemp” line and higher oleic acid content was demonstrated in a Yorkshire field trial.Oil from the new line was almost 80 per cent oleic acid, compared with typical values of less than 10 per cent in the standard hemp line. This high mono-unsaturated/low poly-unsaturated fatty acid profile increases the oil’s thermal stability and oil from the new line was shown to have around five times the stability of standard hemp oil. This not only makes the oil more valuable as a cooking oil but also increases its usefulness for high temperature industrial processes.As oilseed rape faces declining yields and increasing attacks from pest and disease, UK farming needs another break crop to ensure the sustainability of its agriculture and maintain cereal yields. An improved hemp crop, yielding high quality oil would provide an excellent alternative. Hemp is a low-input crop and is also dual-purpose, with the straw being used as a fibre (for bedding, composites and textiles), for biomass and as a source of high value waxes and secondary metabolites.Professor Ian Graham, from CNAP, said: “The new line represents a major improvement in hemp as an oil crop. Similar developments in soybean and oilseed rape have opened up new markets for these crops, due to the perceived healthiness and increased stability of their oil.”In 2014 field trials of the new High Oleic Hemp are being rolled out across Europe in order to establish agronomic performance and yield under a range of environmental conditions in advance of launching a commercial crop.Story Source:The above story is based on materials provided by University of York. …


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