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Archive - May 10, 2013

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Confirmation That Justinianic Plague Was Caused by Yersinia pestis

From the several pandemics generally called 'pestilences,' three are historically recognized as due to plague, but only for the third pandemic of the 19th-21st centuries AD were there microbiological evidences that the causing agent was the bacterium Yersinia pestis. "For a long time scholars from different disciplines have intensively discussed about the actual etiological agents of the past pandemics. Only ancient DNA analyses carried out on skeletal remains of plague victims could finally conclude the debate," said Dr. Barbara Bramanti of the Palaeogenetics Group at the Institute of Anthropology at Johannes Gutenberg University Mainz (JGU) in Germany. About two years ago, she headed the international team which demonstrated beyond any doubt that Y. pestis also caused the second pandemic of the 14th-17th centuries including the Black Death, the infamous epidemic that ravaged Europe from 1346-1351. Dr. Bramanti and her Mainz colleague Dr. Stephanie Hänsch have now cooperated with the University of Munich, the German Bundeswehr, and international scholars to solve the debate as to whether Y. pestis also caused the so-called Justinianic Plague of the 6th-8th centuries AD. The results of ancient DNA analyses carried out remains in the early medieval cemetery of Aschheim in Bavaria were published online on May 2, 2103 in PLOS Pathogens. These results confirmed unambiguously that Y. pestis was indeed the causing agent of the first pandemic, in contrast to what has been postulated by other scientists recently. This revolutionary result is supported by the analysis of the genotype of the ancient strain which provides information about the phylogeny and the place of origin of this plague.

DNA Analysis Reveals Hidden Fungal Species

Our ability to assess biological diversity, ecosystem health, ecological interactions, and a wide range of other important processes is largely dependent on accurately recognizing species. However, identifying and describing species is not always a straightforward task. In some cases, a single species may show a high level of morphological variation, while in other cases, multiple morphologically similar species may be hidden under a single species name. Cryptic species, two or more distinct species that are erroneously classified under a single species name, are found in all major groups of living things. As an alternative to traditional morphology-based species delimitation, an international research group, including scientists from Germany, Iran, Spain, and the USA, describes five new species of lichen-forming fungi from what was traditionally considered a single species using differences in DNA sequence data. The authors state that "the effective use of genetic data appears to be essential to appropriately and practically identify natural groups in some phenotypically cryptic lichen-forming fungal lineages." The study was published online on May 9, 2013 in the open access journal MycoKeys. The scientists also provide a reference DNA sequence database for specimen identification using DNA barcoding, making specimen identification more accessible and more reliable at the same time. The application of DNA-based identification can potentially be used as a way for both specialists and nonspecialists alike to recognize species that are otherwise difficult to identify. Lichens are commonly used to monitor ecosystem health and the impact of atmospheric pollution. In addition, some lichens are potentially valuable sources of pharmaceutical products, including antibiotics, antioxidants, etc.

Taiwanese Scientists Develop Ultra-Fast DNA Sequencing Technique

Professor G. Steven Huang from the Department of Materials Science and Engineering and Professor Yu-Shiun Chen from the Department of Biological Science and Technology of National Chiao Tung University (NCTU) in Taiwan have successfully developed a more rapid, precise, and economic technique of singe-molecule DNA sequencing. By combining a protein transistor with biological technologies, they can accelerate the process of DNA sequencing in order to provide a better tool for personalized medicine and genetic research. The research was published online on May 5, 2013 in Nature Nanotechnology. DNA sequencing is a key to unveiling the mystery of life. A gene is formed by a sequence of bases (G, A, T, C) and locates in the double helix of DNA. It is the basic unit that determines the genetic characteristics of a creature. A human genome consists of approximately 3 billion DNA base pairs. Even with current technology, the process of DNA sequencing still takes a significant amount of time. The innovative technique developed by the team from NCTU stands out becuse it can significantly reduce the time of the sequencing process and meanwhile also lower the error rate. With this technique, single DNA molecules can be sequenced by monitoring the electrical conductance of a phi29 DNA polymerase as it incorporates unlabelled nucleotides into a template strand of DNA. The conductance of the polymerase is measured by attaching it to a protein transistor. According to Professor Chen, with this technology, they can overcome the obstacles from which other techniques suffer. This will be the very first time that people can see the entire process of polymerase synthesis without the use of fluorescence and other external aids.