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Archive - Nov 11, 2012

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Schizophrenia Genetic Networks Identified; Connection to Autism Found

Although schizophrenia is highly genetic in origin, the genes involved in the disorder have been difficult to identify. In the past few years, researchers have implicated several genes, but it is unclear how they act to produce the disorder. A new study by researchers at Columbia University Medical Center identifies affected gene networks and provides insight into the molecular causes of the disease. The paper was published November 11, 2012 in the online edition of the journal Nature Neuroscience. Using an unbiased collection of hundreds of mutations associated with schizophrenia, the Columbia researchers applied a sophisticated computational approach to uncover hidden relationships among seemingly unrelated genes. The analysis revealed that many of the genes mutated in schizophrenia are organized into two main networks, which take part in a few key processes, including axon guidance, synapse function, neuron mobility, and chromosomal modification. The study also uncovered an intriguing connection between schizophrenia and autism. "If we hadn't known that these were two different diseases, and had put all the mutations into a single analysis, it would have come up with very similar networks," said the study's senior author, Dennis Vitkup, Ph.D., associate professor in the Department of Biomedical Informatics, the Center for Computational Biology and Bioinformatics, and the Columbia Initiative in Systems Biology at Columbia University Medical Center. "It shows how closely the autism and schizophrenia genetic networks are intertwined," he added. Although it will take time to translate the findings into practical treatments, the study provides insight into the molecular causes of schizophrenia.

Mutations in Genes That Modify DNA Packaging Result in Facioscapulohumeral Muscular Dystrophy (FSHD)

A recent finding by medical geneticists sheds new light on how facioscapulohumeral muscular dystrophy develops and how it might be treated. More commonly known as FSHD, the devastating disease affects both men and women. FSHD is usually an inherited genetic disorder, yet sometimes appears spontaneously via new mutations in individuals with no family history of the condition. "People with the condition experience progressive muscle weakness and about 1 in 5 require wheelchair assistance by age 40," said Dr. Daniel G. Miller, University of Washington (UW) associate professor of pediatrics in the Division of Genetic Medicine. Dr. Miller and his worldwide collaborators study the molecular events leading to symptoms of FSHD in the hopes of designing therapies to prevent the emergence of symptoms or reduce their severity. In the November 11, 2012 online issue of Nature Genetics, Dr. Miller and Dr. Silvere M. van der Maarel of Leiden University in The Netherlands, along with an international team, report their latest findings on the role of epigenetic modifications in causing the disease. In Seattle, Dr. Stephen Tapscott of the Fred Hutchinson Cancer Research Center was also a major contributor to the project. He is a UW professor of neurology and a researcher at the UW Center for Human Development and Disability. Epigenetics refers to mechanisms that influence how the genome is regulated and how, where, and when genes act -- all without altering the underlying DNA sequence. The flexibility of DNA packaging – its wrapping, which can be tightened and loosened, and its chemical tags – is one of the epigenetic forces on the genome. This packaging is called the chromatin structure and is one way specialized cells such as those in our muscles allow groups of genes to be shut off, or be available for expression.

Age-Related Wet Macular Degeneration Treatment Effective Even with Macular Traction Problems

The primary treatment for wet macular degeneration, a chronic eye condition that causes vision loss, is effective even if patients have macular traction problems, a Mayo Clinic study shows. The findings were presented November 11, 2012 at the annual meeting of the American Academy of Ophthalmology in Chicago. Due to the aging population, an increasing number of patients are being treated for age-related macular degeneration (AMD), an eye condition in which abnormal blood vessels develop and leak into the eye. When patients develop wet AMD, they receive injections of anti-vascular endothelial growth factor medication (VEGF). VEGF prompts growth of new blood vessels in the body. In the case of AMD, however, such new growth is unwanted and may cause bleeding in the retina. It has not been clear whether this treatment would also serve patients experiencing other symptoms, such as vitreomacular interface disease (VMID), in which there is traction or contact between the retina and the vitreous matter in the eye. Mayo researchers retrospectively studied 178 patients, of whom 18 percent had VMID over an average of 2.5 years. Findings showed that while eyes with some kind of macular traction required more injections, they still showed improvement (best corrected visual acuity) to similar eyes without VMID. "This finding is significant," says senior author Sophie J. Bakri, M.D., "because it showed that patients with VMID are not necessarily treatment resistant for AMD." She also says it may help physicians not give up on treating such patients, and understand the need for more doses of medication for those with VMID. Researchers say more study is needed, including a prospective clinical trial. Co-authors include Amy Green-Simms, M.D., and Blake Fechtel and Zubin Agarwal, M.P.H., all of the Mayo Clinic.

Texas Cotton Getting a Genetic “Tune-Up”

Can you imagine trying to build a competitive race car with old parts? Chances are, the entry would not fare well at the Indy 500. Very much the same thing might be said about today's crops, according to a Texas A&M AgriLife Research scientist. "Contemporary crops such as Texas cotton are like finely tuned racing machines — they need high quality parts to perform optimally," said Dr. David Stelly, AgriLife Research cotton geneticist in College Station. "And they constantly need new ones to replace ones that are no longer functional, as well as those that are still effective, but no longer at the cutting edge of competition." Dr. Stelly said his role in the AgriLife Research cotton breeding program is to infuse new genes and gene combinations into the genetics and breeding research arena, "so that we can utilize natural genetic resources to help meet the many challenges breeding programs face." Transferring genes into a cultivated crop from a wild species “is like swimming upstream, one is fighting all sorts of biological and genetic barriers," he said. For years, he and his long-time research assistant, Dwaine Raska, have been transferring the alien genes by a special breeding process called "chromosome substitution." "Using chromosome substitution, we can target one pair of cultivated cotton chromosomes at a time, and replace it with the corresponding pair of chromosomes from a wild species chosen as the donor. On average, each substitution replaces about 2,000 cotton genes with donor genes," Dr. Stelly said. Having already developed chromosome substitution lines for many chromosomes from three donor species, Dr. Stelly is working in collaboration with a former graduate student, Dr. Sukumar Saha, now with the U.S.

Scent Markings May Be Used to Stop Endangered African Wild Dogs from Wandering into Extinction

Throughout history, and all over the world, people have killed wild carnivores to protect their livestock. Now, a relentless expansion of human activities that brings people and their livestock into ever larger areas of former wildlife habitat is rapidly escalating both the threats to carnivore populations and the impact of carnivores on rural people’s liveliehoods. In southern Africa a radically new way to reduce conflict between people and wild carnivores is being developed by the BioBoundary Project of the Botswana Predator Conservation Trust (BPCT, http://www.bpctrust.org/). With funding from the Paul G. Allen Family Foundation, the BioBoundary Project is using the protection of endangered African wild dogs as a test case of whether wild carnivores can be kept away from livestock by artifical scent-mark boundaries between protected wildlife areas and livestock areas. African wild dogs (Lycaon pictus) are intensely social super-predators. They live in packs with huge home ranges that extend beyond the boundaries of even the largest of protected areas. When wild dogs cross these boundaries into landscapes that are dominated by humans and livestock they run a gauntlet of shooting, snaring, and poisoning; in most wild dog populations, more dogs are killed by people than by anything else. African wild dogs used to range across 39 sub-Saharan countries but now their numbers have dwindled to fewer than 6,000 and only two populations are large enough to be self-sustaining in the long term. Each African wild dog pack stakes out its territory by soaking patches of soil with the urine of the pack’s alpha pair.