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Archive - Feb 27, 2015

MGH-Harvard Study Demonstrates the Neuronal Basis of Cooperative Social Interactions; Results May Lead to Targeted Treatment of Autism Spectrum Disorders (ASDs) and Other Social Behavioral Maladies

Social interactions rely on the ability to anticipate others' intentions and actions, and the identificantion of neurons that reflect another individual's so-called "state of mind" has been a long-sought goal in neuroscience. A study published online on February 26, 2015 in Cell reveals that a newly discovered set of neurons in a frontal brain region called the anterior cingulate is used in primates to predict whether or not an opponent will cooperate in a strategic decision-making task, providing information about the inherently unobservable and unknown decisions of others. By shedding light on the neuronal basis of cooperative interactions, the study paves the way for the targeted treatment of social behavioral disorders such as autism spectrum disorders. The Cell article is titled “Neuronal Prediction of Opponent's Behavior During Cooperative Social Interchange in Primates." "Many conflicts or adversarial interactions arise from an inability to accurately read another's intentions or hidden state of mind," says lead author Keren Haroush, M.D., a postdoctoral fellow at the Massachusetts General Hospital (MGH)-Harvard Medical School (HMS) Center for Nervous System Repair. "Therefore, understanding where and how these computations are performed within the brain may help us better understand how such complex social interactions occur." Previous studies had shown that brain cells called mirror neurons reflect the known and observable actions of one’s self and others. But these neurons do not represent another's imminent decisions or intentions. While neurons that predict another's intended actions have been widely hypothesized and are a cornerstone of many theories on social behavior, their existence had never before been demonstrated.

New Drug Effective Against MDR Tuberculosis, Also Shows Signs of Anti-HIV Activity

Researchers at the University of Georgia (UGA) have developed a new small molecule drug that may serve as a treatment for multi-drug resistant (MDR) tuberculosis, a form of the disease that cannot be cured with conventional therapies. The scientists describe their findings in an article available online and scheduled to be published in the March 15, 2015 issue of Bioorganic and Medicinal Chemistry Letters. The article is titled “A Novel Molecule with Notable Activity Against Multi-Drug Resistant Tuberculosis.” Nine million people contracted tuberculosis in 2013, and 1.5 million died from the disease, according to the World Health Organization (WHO). While standard anti-TB drugs can cure most people of Mycobacterium tuberculosis infection, improper use of antibiotics has led to new strains of the bacterium that are resistant to the two most powerful medications, isoniazid and rifampicin. "Multi-drug resistant TB is spreading rapidly in many parts of the world," said Dr. Vasu Nair (photo), Georgia Research Alliance Eminent Scholar in Drug Discovery in the University of Georgia (UGA) College of Pharmacy and lead author of the paper. "There is a tremendous need for new therapies, and we think our laboratory has developed a strong candidate that disrupts fundamental steps in the bacterium's reproduction process." Just as in other living organisms, the genetic information contained in M. tuberculosis undergoes a complex process known as transcription in which the bacterial enzyme, DNA-dependent RNA polymerase, or RNAP, produces TB RNA. This molecule is involved in processes that produce critical bacterial proteins that the organism needs to survive. The compound that Dr. Nair and his colleagues developed works by binding to magnesium and specific amino acids found within the bacterium, interrupting the production of RNA.

Wyoming’s Big Horn Basin Reveals Fossil Evidence of New Species of Tropical Turtle; Finding Offers Clues to Modern Perils Facing Turtle Migration in Response to Climate Change

Tropical turtle fossils discovered in Wyoming by University of Florida (UF) scientists reveal that when the earth got warmer, prehistoric turtles headed north. But if today's turtles try the same technique to cope with warming habitats, they might run into trouble. While the fossil turtle and its kin could move northward with higher temperatures, human pressures and habitat loss could prevent a similar modern-day migration, and lead to the extinction of some modern species. The newly discovered genus and species, Gomphochelys nanus, provides a clue to how animals might respond to future climate change, said Dr. Jason Bourque, a paleontologist at the Florida Museum of Natural History at UF and the lead author of the study, which was published online on February 20, 2015 in the Journal of Vertebrate Paleontology. The wayfaring turtle was among the species that researchers believe migrated 500-600 miles north 56 million years ago, during a temperature peak known as the Paleocene-Eocene Thermal Maximum. Lasting approximately 200,000 years, this temperature peak resulted in significant movement and diversification of plants and animals. "We knew that some plants and lizards migrated north when the climate warmed, but this is the first evidence that turtles did the same," Dr. Bourque said. "If global warming continues on its current track, some turtles could once again migrate northward, while others would need to adapt to warmer temperatures or go extinct." The newly identified turtle is an ancestor of the endangered Central American river turtle and other warm-adapted turtles in Belize, Guatemala, and southern Mexico. These modern turtles, however, could face significant roadblocks on a journey north, because much of the natural habitat of these species is in jeopardy, said co-author Dr.

Genetic Underpinnings of Motion Sickness

23andMe, Inc., a leading personal genetics company, has announced the publication of the first-ever genome-wide association study of motion sickness. Published online on February 17, 2015 in the prestigious Human Molecular Genetics journal, this study is the first to identify genetic variants associated with motion sickness, a condition that affects roughly one in three people around the world. The title of this report is “Genetic Variants Associated with Motion Sickness Point to Roles for Inner Ear Development, Neurological Processes, and Glucose Homeostasis.” Motion sickness has been shown to have high heritability, meaning genetics accounts for a large part of why some people are more prone to motion sickness than others. Estimates indicate that up to 70 percent of the variation in risk for motion sickness is due to genetics. "Until now there's been a poor understanding of the genetics of motion sickness, despite it being a fairly common condition," said 23andMe scientist Dr. Bethann Hromatka, lead author of the study. "With the help of 23andMe customers, we've been able to uncover some of the underlying genetics of this condition. These findings could help provide clues about the causes of motion sickness and other related conditions, and how to treat them, which is very exciting." The new study, which involved the consented participation of more than 80,000 23andMe customers, found 35 genetic factors associated with motion sickness at a genome-wide significant level. Many of these factors, referred to as single-nucleotide polymorphisms (SNPs), are in or near genes involved in balance, and in eye, ear, and cranial development (e.g., PVRL3, TSHZ1, MUTED, HOXB3, HOXD3 genes). Other SNPs may affect motion sickness through nearby genes with roles in the nervous system, glucose homeostasis, or hypoxia.

In the Genetic Comfort Zone--“Canalization” Buffers Developing Organisms Against Effects of Mutations and Envirnmental Stress; “Decanalization” (Departure from Genetic Comfort Zone) May Contribute to Variety of Complex Diseases in Humans

The information encoded in the DNA of an organism is not sufficient to determine the expression pattern of genes. This fact was known even before the discovery of epigenetics, which refers to external modifications to the DNA that turn genes "on" or "off." These modifications do not change the DNA sequence, but instead, they affect how genes are expressed. Another, less known mechanism called “canalization” (http://en.wikipedia.org/wiki/Canalisation_%28genetics%29) keeps organisms robust despite genetic mutations and environmental stressors. If an organism experiences environmental or genetic perturbations during its development, such as extreme living conditions or genetic mutations, canalization acts as a way of buffering these disturbances. The organism remains stable and can continue to develop without recognizable changes. The article, entitled “Temperature Stress Mediates Decanalization and Dominance of Gene Expression in Drosophila melanogaster,” was published on February 26, 2015 in the open-access journal PLOS Genetics. Dr. Christian Schlötterer, at the Institute of Population Genetics, The University of Veterinary Medicine, Vienna, in Austria, together with colleagues, studied the mechanism of canalization in fruit flies. The researchers subjected two genetically distinct strains of fruit flies, Oregon and Samarkand, to different temperatures (13°C, 18°C, 23°C, and 29°C). Subsequently, the scientists analyzed the variation in gene expression in response to the different temperatures. The results revealed a homogeneous pattern of gene expression among the two strains at 18°C. No matter whether the flies were from the Oregon or to the Samarkand strain, their gene expression was almost indistinguishable.