Experts in ancient DNA from McMaster University (Canada) have teamed up with genome researchers from Penn State University (USA) for the investigation of permafrost bone samples from Siberia. The project also involved paleontologists from the American Museum of Natural History (USA) and researchers from Russia, the United Kingdom, France, and Germany. The researchers report on the first genomic sequences from a woolly mammoth will be published on 22 December 2005 by the journal Science on the Science Express website. This majestic mammal roamed grassy plains of the Northern Hemisphere until it became extinct about 10,000 years ago. The scientific breakthrough allows for the first time comparion of this ancient species with todays populations of African and Indian elephants, not just at the level of mitochondrial sequences, but also encompassing information from the nuclear genome.
Analyzing organellar DNA from mitochondria has been the only method of studying ancient DNA in the past, as it is more tractable due to its 1000-fold higher copy number per cell. However, the mitochondrial genome codes for only a tiny fraction of an organisms genetic information -- 0.0006 percent in the case of a mammal. In contrast, most hereditary information is organized on chromosomes located in the cells nucleus (nuclear DNA). A mammoth was chosen for study in part because of its close evolutionary relationship to the African elephant, whose nuclear DNA sequence has been made publicly available by the Broad Institute in Cambridge, Massachusetts (USA). Using comparisons with elephant DNA, the researchers identified 13 million base pairs as being nuclear DNA from the mammoth, which they showed to be 98.5 percent identical to nuclear DNA from an African elephant.
The project became possible through the discovery of exceptionally well preserved remains of a mammoth skeleton in the permafrost soil of northern Siberia, in combination with a novel high-throughput sequencing technique that could cope with the heavily fragmented DNA retrieved from the organisms mandible, its jaws. The bone material used in this study is approximately 28,000 years old, as was shown by beta-carbon dating analysis. This was a surprising finding, as it demonstrated that the analyzed material was frozen for more than 10,000 years before the maximum of the last ice age. The research team used a computational approach to demonstrate that an unprecedented 50 perecent of the bone DNA was indeed mammoth DNA, while the remaining genetic material was shown to belong to microorganisms living the tundra soil.
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The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
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