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Archive - Sep 23, 2011

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Aborigine Genome Sequence Suggests Direct Descent from First Human Explorers

In an exciting development, an international team of researchers has, for the first time, pieced together the human genome from an Aboriginal Australian. The results, published online on September 22, 2011, in the international journal Science, suggest a re-interpretation of the prehistory of our species. By sequencing the genome, the researchers demonstrate that Aboriginal Australians descend directly from an early human expansion into Asia that took place some 70,000 years ago, at least 24,000 years before the population movements that gave rise to present-day Europeans and Asians. The results imply that modern-day Aboriginal Australians are, in fact, the direct descendents of the first people who arrived in Australia as early as 50,000 years ago. The study derived from a lock of hair donated to a British anthropologist by an Aboriginal man from the Goldfields region of Western Australia in the early 20th century. One hundred years later, researchers have isolated DNA from this same hair, using it to explore the genetics of the first Australians and to provide insights into how humans first dispersed across the globe. The genome, shown to have no genetic input from modern European Australians, reveals that the ancestors of the Aboriginal man separated from the ancestors of other human populations some 64-75 thousand years ago. Aboriginal Australians therefore descend directly from the earliest modern explorers, people who migrated into Asia before finally reaching Australia about 50,000 years ago. In showing this, the study establishes Aboriginal Australians as the population with the longest association with the land on which they live today. This research is presented with the full endorsement of the Goldfields Land and Sea Council, the organization that represents the Aboriginal traditional owners for the region.

DNA Study Suggests Asia Was Settled in Multiple Waves of Migration

An international team of researchers studying DNA patterns from modern and archaic humans has uncovered new clues about the movement and intermixing of populations more than 40,000 years ago in Asia. Using state-of-the-art genome analysis methods, scientists from Harvard Medical School and the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, have found that Denisovans—a recently identified group of archaic humans whose DNA was extracted last year from a finger bone excavated in Siberia—contributed DNA, not just to present-day New Guineans, but also to aboriginal Australian and Philippine populations. The study demonstrates that contrary to the findings of the largest previous genetic studies, modern humans settled Asia in more than one migration. According to Dr. David Reich, a professor of genetics at Harvard Medical School, "Denisova DNA is like a medical imaging dye that traces a person's blood vessels. It is so recognizable that you can detect even a little bit of it in one individual. In a similar way, we were able to trace Denisova DNA in the migrations of people. This shows the power of sequencing ancient DNA as a tool for understanding human history." The patterns the researchers found can only be explained by at least two waves of human migration: the first giving rise to the aboriginal populations that currently live in Southeast Asia and Oceania, and later migrations giving rise to relatives of East Asians, who now are the primary population of Southeast Asia. The study also provides new insights about where the ancient Denisovans lived. According to Dr. Mark Stoneking, a professor at the Max Planck Institute who is senior author of the paper, Denisovans must have inhabited an extraordinarily large ecological and geographic range, from Siberia to tropical Southeast Asia.

Insulin Master Switch Discovered—May Signal Hope for Reversing Type 2 Diabetes

Australian scientists have discovered that a single gene controls a very complex process, apparently forming the crucial link between eating a high-fat diet and developing diabetes. Compounds are already being developed for blocking the gene – known as Id1 – as it has known adverse effects in cancer. This drug development work would very much shorten the path from discovery to prospective treatment in the case of diabetes. Type 2 diabetes occurs when the body becomes less able to produce and use insulin, a hormone essential for maintaining normal metabolism of food. The disorder is associated with a high-sugar, high-fat diet combined with lack of exercise. Insulin is produced in the pancreas by highly specialized “beta cells,” and then carried around our bodies in the bloodstream, helping cells metabolize food. While cells in our bodies contain the same DNA, different cells express different genes, depending on the cell’s function. Beta cells predominantly express genes that help them secrete insulin. When diabetes develops, the gene expression pattern in a beta cell changes, ultimately making the cell incapable of doing its job. Ph.D. scholar Mia Akerfeldt and Dr. Ross Laybutt from Sydney’s Garvan Institute of Medical Research have found that Id1 appears to be the master regulator of other genes in a beta cell, and it is “switched on” when people consume a high-fat diet. This finding was reported online on September 22, 2011, in the journal Diabetes. “We’re saying that Id1 is the molecular link between environmental factors, such as high-fat diet, and beta cell dysfunction,” said Dr Laybutt. “Not only does the presence of Id1 appear to initiate all the other gene expression changes that take place in dysfunctional beta cells, its absence completely protects the beta cell.

New Treatment for Leishmaniasis, a Deadly Parasitic Disease

East Africa is fighting the worst kala azar outbreak in a decade. Kala azar is another name given to visceral leishmaniasis (VL), a parasitic disease endemic in around 70 countries worldwide. South Sudan has the second highest number of cases after India. The disease is spread through the bite of a sandfly and is fatal without treatment. Approximately half a million people are infected with the disease and 50,000-60,000 die every year as a result of the infection. Patients suffer from irregular bouts of fever, substantial weight loss, swelling of the spleen and liver, and anemia. Collaboration across the East Africa region through the Leishmaniasis East Africa Platform (LEAP) has resulted in the development of a new combination therapy (SSG&PM) which is cheaper and nearly halves the length of treatment from a 30-day course of injections to 17 days. East African endemic countries are taking the necessary regulatory measures to use it in their programmes, but experts warn that without international funding or interest in supporting governments in the roll out, too few patients will benefit. “The poorest of the poor, in the most remote villages are the ones who are wasting away from kala azar and who could benefit the most from a shorter more affordable treatment,” said Dr. Monique Wasunna, Assistant Director, KEMRI, and Head, DNDi Africa. “Neglected diseases and patients mean that even when there are new treatments and hope, they are too far from the headlines and donor priorities to get support to governments.