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Archive - 2013

March 6th

Study Maps Genetic Network Model of Human Metabolism in Health and Disease

Scientists have produced an instruction manual for the human genome that provides a framework to better understand the relationship between an individual’s genetic make-up and his or her lifestyle. The international team of researchers says their study – published online on March 3, 2013 in Nature Biotechnology – provides the best model yet to explain why individuals react differently to environmental factors such as diet or medication. “This research is the second important stage of our understanding of the human genome,” said study author Professor Pedro Mendes, from The University of Manchester’s School of Computer Science. “If the sequencing of the human genome provided us with a list of the biological parts, then our study explains how these parts operate within different individuals. The results provide a framework that will lead to a better understanding of how an individual’s lifestyle, such as diet, or a particular drug they may require is likely to affect them according to their specific genetic characteristics. The model takes us an important step closer to what is termed ‘personalized medicine,’ where treatments are tailored according to the patient’s genetic information.” The research, which involved scientists from Manchester, Cambridge, Edinburgh, Reykjavik, San Diego, Berlin, and other locations, mapped 65 different human cell types and half of the 2,600 enzymes that are known drug targets in order to produce the network model. Co-author Dr. Douglas Kell, Chief Executive of the Biotechnology and Biological Sciences Research Council (BBSRC) and Professor of Bioanalytical Science at the Manchester Institute of Biotechnology, said, "To understand the behaviour of a system, one must have a model of it.

March 5th

Ancient DNA Solves Mystery of the Enigmatic Falkland Islands Wolf

University of Adelaide researchers in Australia have found the answer to one of natural history's most intriguing puzzles – the origins of the now extinct Falkland Islands wolf and how it came to be the only land-based mammal on the isolated islands – 460 km from the nearest land, Argentina. Previous theories have suggested the wolf somehow rafted on ice or vegetation, crossed via a now-submerged land bridge, or was even semi-domesticated and transported by early South American humans. The 320-year-old mystery was first recorded by early British explorers in 1690 and raised again by Charles Darwin following his encounter with the famously tame species on his Beagle voyage in 1834. Researchers from the University's Australian Centre for Ancient DNA (ACAD) extracted tiny pieces of tissue from the skull of a specimen collected personally by Darwin. They also used samples from a previously unknown specimen, which was recently re-discovered as a stuffed exhibit in the attic of the Otago Museum in New Zealand. The findings were published online on March 5, 2013 in Nature Communications and concluded that, unlike what had been suggested by earlier theories, the Falkland Islands wolf (Dusicyon australis) only became isolated about 16,000 years ago around the peak of the last glacial period. "Previous studies used ancient DNA from museum specimens to suggest that the Falkland Islands wolf diverged genetically from its closest living relative, the South American maned wolf (Chrysocyon brachyurus) around seven million years ago. As a result, they estimated that the wolf colonized the islands about 330,000 years ago by unknown means," says Associate Professor Jeremy Austin, Deputy Director of ACAD and co-lead author with Dr. Julien Soubrier.

3.5 Million-Year-Old Fossil of Extinct Giant Camel Found in Arctic

A research team led by the Canadian Museum of Nature has identified the first evidence for an extinct giant camel in Canada's High Arctic. The discovery is based on 30 fossil fragments of a leg bone found on Ellesmere Island, Nunavut, part of the Canadian Arctic Archipelago, and represents the most northerly record for early camels, whose ancestors are known to have originated in North America some 45 million years ago. The fossils were collected over three summer field seasons (2006, 2008, and 2010) and are about three and a half million years old, dating from the mid-Pliocene Epoch. Other fossil finds at the site suggest this High Arctic camel lived in a boreal-type forest environment, during a global warm phase on the planet. The research, by Natalia Rybczynski, Ph.D., and co-authors including John Gosse, Ph.D. (at Dalhousie University, Halifax, Nova Scotia), and Mike Buckley, Ph.D. (at the University of Manchester, UK), was described online on March 5, 2013 in an open-access article in Nature Communications. "This is an important discovery because it provides the first evidence of camels living in the High Arctic region," explains Dr. Rybczynski, a vertebrate palaeontologist with the Canadian Museum of Nature, who has led numerous field expeditions in Canada's Arctic. "It extends the previous range of camels in North America northward by about 1200 km, and suggests that the lineage that gave rise to modern camels may have been originally adapted to living in an Arctic forest environment." The camel bones were collected from a steep slope at the Fyles Leaf Bed site, a sandy deposit near Strathcona Fiord on Ellesmere Island. Fossils of leaves, wood, and other plant material have been found at this site, but the camel is the first mammal recovered.

March 4th

Mysterious Disease and Queen Rejection Key Factors in Honey Bee Colony Deaths

A new long-term study of honey bee health has found that a little-understood disease that study authors are calling “idiopathic brood disease syndrome” (IBDS), which kills off bee larvae, is the largest risk factor for predicting the death of a bee colony. “Historically, we’ve seen symptoms similar to IBDS associated with viruses spread by large-scale infestations of parasitic mites,” says Dr. David Tarpy, an associate professor of entomology at North Carolina State University and co-author of a paper describing the study. “But now we’re seeing these symptoms – a high percentage of larvae deaths – in colonies that have relatively few of these mites. That suggests that IBDS is present even in colonies with low mite loads, which is not what we expected.” The study was conducted by researchers from NC State, the University of Maryland, Pennsylvania State University, and the U.S. Department of Agriculture (USDA). The study evaluated the health of 80 commercial colonies of honey bees (Apis mellifera) in the eastern United States on an almost monthly basis over the course of 10 months – which is a full working “season” for commercial bee colonies. The goal of the study was to track changes in bee colony health and, for those colonies that died off, to determine what factors earlier in the year may have contributed to colony death. Fifty-six percent of the colonies died during the study. “We found that colonies affected by IBDS had a risk factor of 3.2,” says Dr. Dennis van Englesdorp of the University of Maryland, who was lead author on the paper. That means that colonies with IBDS were 3.2 times more likely to die than the other colonies over the course of the study. While the study found that IBDS was the greatest risk factor, a close runner-up was the occurrence of a so-called “queen event.” Honey bee colonies have only one queen.

Why Cats Lack a Sweet Tooth

Do cats prefer sardines or sweets? The American Chemical Society (ACS), the world's largest scientific society, today released a new Bytesize Science video that explains why cats, unlike humans and other mammals, are indifferent to sweet flavors. Produced by the ACS Office of Public Affairs, the video is available at www.BytesizeScience.com. The video was filmed at the Monell Chemical Senses Center, an institute dedicated to research on taste, smell, and other senses. Prior to becoming Monell's Director, Gary Beauchamp, Ph.D., studied the sweet taste receptor genes of cats in the late 1970s. At the Philadelphia Zoo, he gave lions, tigers, cheetahs, and housecats two different types of water — sugar water and regular water. The cats showed no preference to the sugar water, suggesting a physiological difference between them and other mammals, such as humans, monkeys, and dogs. The video explains how scientists from the Monell Chemical Senses Center later uncovered the cause behind the cat's missing sweet tooth. In place of a functional sweet taste receptor gene, they discovered that cats have a pseudogene, or a broken gene, that makes them unable to detect sweet tastes. [Press release] [Monell video]

March 3rd

First "Functional HIV Cure" Described in an Infant

A team of researchers from Johns Hopkins Children’s Center, the University of Mississippi Medical Center, and the University of Massachusetts Medical School have described the first case of a so-called “functional cure” in an HIV-infected infant. The finding, the investigators say, may help pave the way to eliminating HIV infection in children. A report on the case was presented on March 3, 2013 at the 20th Conference on Retroviruses and Opportunistic Infections (CROI) in Atlanta. Johns Hopkins Children’s Center virologist Deborah Persaud, M.D., lead author on the report, and University of Massachusetts Medical School immunologist Katherine Luzuriaga, M.D., headed a team of laboratory investigators. Pediatric HIV specialist Hannah Gay, M.D., associate professor of pediatrics at the University of Mississippi Medical Center provided treatment to the baby. The infant described in the report underwent remission of HIV infection after receiving antiretroviral therapy (ART) within 30 hours of birth. The investigators say the prompt administration of antiviral treatment likely led to this infant’s cure by halting the formation of hard-to-treat viral reservoirs — dormant cells responsible for reigniting the infection in most HIV patients within weeks of stopping therapy. “Prompt antiviral therapy in newborns that begins within days of exposure may help infants clear the virus and achieve long-term remission without lifelong treatment by preventing such viral hideouts from forming in the first place,” Dr. Persaud says. The researchers say they believe this is precisely what happened in the child described in the report.

Seven Loci Newly Associated with Age-Related Macular Degeneration (AMD)

An international group of researchers has discovered seven regions of the human genome—called loci—that are newly associated with increased risk of age-related macular degeneration (AMD), a leading cause of blindness. The AMD Gene Consortium, a network of international investigators representing 18 research groups, also confirmed 12 AMD-associated loci identified in previous studies. The new study, which was published online on March 3, 2013 in Nature Genetics and represents the most comprehensive genome-wide analysis of genetic variations associated with AMD, was supported by the National Eye Institute (NEI), a part of the National Institutes of Health. Lindsay A. Farrer, Ph.D., chief of the biomedical genetics section and professor at Boston University Schools of Medicine (BUSM) and Public Health (BUSPH), is a co-lead author of the study. "This compelling analysis by the AMD Gene Consortium demonstrates the enormous value of effective collaboration," said NEI Director Paul A. Sieving, M.D., Ph.D. "Combining data from multiple studies, this international effort provides insight into the molecular basis of AMD, which will help researchers search for causes of the disease and will inform future development of new diagnostic and treatment strategies." Since the 2005 discovery that certain variations in the gene for complement factor H—a component of the immune system—are associated with major risk for AMD, research groups around the world have conducted genome-wide association studies to identify other loci that affect AMD risk. These studies were made possible by tools developed through the Human Genome Project, which mapped human genes, and related projects, such the International HapMap Project, which identified common patterns of genetic variation within the human genome.

March 1st

Prenatal Viral Infection in Mother and Stress in Puberty Combine to Influence Schizophrenia

The interplay between an infection during pregnancy and stress in puberty plays a key role in the development of schizophrenia, as behaviourists from ETH Zurich demonstrate in a mouse model. Approximately one per cent of the population suffers from schizophrenia, a serious mental disorder that usually does not develop until adulthood and is incurable. Psychiatrists and neuroscientsist have long suspected that adverse enviromental factors may play an important role in the development of schizophrenia. Prenatal infections such as toxoplasmosis or influenza, psychological, stress or family history have all come into question as risk factors. Nevertheless, until now, researchers have been unable to identify the interplay of the individual factors linked to this serious mental disease. However, a research group headed by Dr. Urs Meyer, a senior scientist at the Laboratory of Physiology & Behaviour at ETH Zurich, has now made a breakthrough: for the first time, they were able to find clear evidence that the combination of two environmental factors contributes significantly to the development of schizophrenia-relevant brain changes and at which stages in a person's life they need to come into play for the disorder to break out. The researchers developed a special mouse model, with which they were able to simulate the processes in humans virtually in fast forward. The study has been published in the March 1, 2013 issue of Science. The first negative environmental influence that favours schizophrenia is a viral infection of the mother during the first half of the pregnancy. If a child with such a prenatal infectious history is also exposed to major stress during puberty, the probability that he or she will suffer from schizophrenia later increases markedly.

Parkinson’s Disease: Parkin Protein Protects from Neuronal Cell Death

Researchers at Ludwig Maxmilians University (LMU)-Munich have identify a novel signal transduction pathway, which activates the parkin gene and prevents stress-induced neuronal cell death. The results were published online on February 28, 2013 in Molecular Cell. Parkinson's disease is the most common movement disorder and the second most common neurodegenerative disease after Alzheimer's disease. It is characterized by the loss of dopamin-producing neurons in the substantia nigra, a region in the midbrain, which is implicated in motor control. The typical clinical signs include resting tremor, muscle rigidity, slowness of movements, and impaired balance. In about 10% of cases Parkinson's disease is caused by mutations in specific genes: one of which is called parkin. “Parkinson-associated genes are particularly interesting for researchers, since insights into the function and dysfunction of these genes allow conclusions on the pathomechanisms underlying Parkinson's disease,” says Dr. Konstanze Winklhofer of the Adolf Butenandt Institute at the LMU Munich, who is also affiliated with the German Center for Neurodegenerative Diseases (DZNE). Dr. Winklhofer and her colleagues had previously observed that parkin can protect neurons from cell death under various stress conditions. In the course of this project, it became obvious that a loss of parkin function impairs the activity and integrity of mitochondria, which serve as the cellular power stations. In their latest publication, Dr. Winklhofer and coworkers uncovered the molecular mechanism that accounts for parkin’s neuroprotective action. “We discovered a novel signaling pathway that is responsible for the neuroprotective activity of parkin,” Dr. Winklhofer reports.

Previously Unknown Mechanism Proposed for How Ordered Structures Arise in Cell Membranes

An explanation has been proposed for the way in which ordered structures arise in cell membranes. Scientists from the Max Planck Institute of Colloids and Interfaces in Potsdam, Germany, have discovered how complex compounds of sugar and lipids – known as glycolipids – order themselves in cell membranes into rafts, namely small, highly organized domains. The arrangement of glycolipids on the surface of plant and animal cell membranes regulates numerous cellular processes. If errors occur in this process, diseases like paroxysmal nocturnal hemoglobinuria (PNH) and bovine spongiform encephalopathy (BSE) can arise. The results were originally published in the Angewandte Chemie International Edition on December 14, 2012. Lipids, i.e. fats and fat-like substances, arise all over the human body. They are the body’s most important energy storage system and are crucial structural components of cell membranes. Compounds formed from complex sugar components and fats are known as glycolipids. These are vital communicators found in the membranes of every human cell, and constantly exchange information about the type and state of the cell. Numerous metabolic processes depend on glycolipids and their recognition. Even the immune system identifies and combats many pathogens using certain sugar structures located on the surfaces of the pathogen cells. Glycosylphosphatidylinositols (GPIs) belong to the group of natural glycolipids. They are found on the surface of plant and animal cell membranes, where they appear either as free molecules or as membrane anchors for various proteins. The arrangement in clusters and their preference for denser and, in part, highly-organized micro-domains in the membrane are seen as essential for the effective functioning of a cell.