New brain pathways for understanding type 2 diabetes and obesity uncovered

Researchers at UT Southwestern Medical Center have identified neural pathways that increase understanding of how the brain regulates body weight, energy expenditure, and blood glucose levels — a discovery that can lead to new therapies for treating Type 2 diabetes and obesity.The study, published in Nature Neuroscience, found that melanocortin 4 receptors (MC4Rs) expressed by neurons that control the autonomic nervous system are key in regulating glucose metabolism and energy expenditure, said senior author Dr. Joel Elmquist, Director of the Division of Hypothalamic Research, and Professor of Internal Medicine, Pharmacology, and Psychiatry.”A number of previous studies have demonstrated that MC4Rs are key regulators of energy expenditure and glucose homeostasis, but the key neurons required to regulate these responses were unclear,” said Dr. Elmquist, who holds the Carl H. Westcott Distinguished Chair in Medical Research, and the Maclin Family Distinguished Professorship in Medical Science, in Honor of Dr. Roy A. Brinkley. “In the current study, we found that expression of these receptors by neurons that control the sympathetic nervous system, seem to be key regulators of metabolism. In particular, these cells regulate blood glucose levels and the ability of white fat to become ‘brown or beige’ fat.”Using mouse models, the team of researchers, including co-first authors Dr. Eric Berglund, Assistant Professor in the Advanced Imaging Research Center and Pharmacology, and Dr. Tiemin Liu, a postdoctoral research fellow in Internal Medicine, deleted MC4Rs in neurons controlling the sympathetic nervous system. …

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Bacteria on the skin: Our invisible companions influence how quickly wounds heel

A new study suggests microbes living on our skin influence how quickly wounds heal. The findings could lead to new treatments for chronic wounds, which affect 1 in 20 elderly people.We spend our lives covered head-to-toe in a thin veneer of bacteria. But despite a growing appreciation for the valuable roles our resident microbes play in the digestive tract, little is known about the bacteria that reside in and on our skin. A new study suggests the interplay between our cells and these skin-dwelling microbes could influence how wounds heal.”This study gives us a much better understanding of the types of bacterial species that are found in skin wounds, how our cells might respond to the bacteria and how that interaction can affect healing,” said Matthew Hardman, Ph.D., a senior research fellow at The University of Manchester Healing Foundation Centre who led the project. “It’s our hope that these insights could help lead to better treatments to promote wound healing that are based on sound biology.”Chronic wounds — cuts or lesions that just never seem to heal — are a significant health problem, particularly among elderly people. An estimated 1 in 20 elderly people live with a chronic wound, which often results from diabetes, poor blood circulation or being confined to bed or a wheelchair.”These wounds can literally persist for years, and we simply have no good treatments to help a chronic wound heal,” said Hardman, who added that doctors currently have no reliable way to tell whether a wound will heal or persist. “There’s a definite need for better ways to both predict how a wound is going to heal and develop new treatments to promote healing.”The trillions of bacteria that live on and in our bodies have attracted a great deal of scientific interest in recent years. Findings from studies of microbes in the gut have made it clear that although some bacteria cause disease, many other bacteria are highly beneficial for our health.In their recent study, Hardman and his colleagues compared the skin bacteria from people with chronic wounds that did or did not heal. The results showed markedly different bacterial communities, suggesting there may be a bacterial “signature” of a wound that refuses to heal.”Our data clearly support the idea that one could swab a wound, profile the bacteria that are there and then be able to tell whether the wound is likely to heal quickly or persist, which could impact treatment decisions,” said Hardman.The team also conducted a series of studies in mice to shed light on the reasons why some wounds heal while others do not. They found that mice lacking a single gene had a different array of skin microbiota — including more harmful bacteria — and healed much more slowly than mice with a normal copy of the gene.The gene, which has been linked to Chrohn’s disease, is known to help cells recognize and respond to bacteria. …

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Self-healing engineered muscle grown in the laboratory

Biomedical engineers have grown living skeletal muscle that looks a lot like the real thing. It contracts powerfully and rapidly, integrates into mice quickly, and for the first time, demonstrates the ability to heal itself both inside the laboratory and inside an animal.The study conducted at Duke University tested the bioengineered muscle by literally watching it through a window on the back of living mouse. The novel technique allowed for real-time monitoring of the muscle’s integration and maturation inside a living, walking animal.Both the lab-grown muscle and experimental techniques are important steps toward growing viable muscle for studying diseases and treating injuries, said Nenad Bursac, associate professor of biomedical engineering at Duke.The results appear the week of March 25 in the Proceedings of the National Academy of Sciences Early Edition.”The muscle we have made represents an important advance for the field,” Bursac said. “It’s the first time engineered muscle has been created that contracts as strongly as native neonatal skeletal muscle.”Through years of perfecting their techniques, a team led by Bursac and graduate student Mark Juhas discovered that preparing better muscle requires two things — well-developed contractile muscle fibers and a pool of muscle stem cells, known as satellite cells.Every muscle has satellite cells on reserve, ready to activate upon injury and begin the regeneration process. The key to the team’s success was successfully creating the microenvironments — called niches — where these stem cells await their call to duty.”Simply implanting satellite cells or less-developed muscle doesn’t work as well,” said Juhas. “The well-developed muscle we made provides niches for satellite cells to live in, and, when needed, to restore the robust musculature and its function.”To put their muscle to the test, the engineers ran it through a gauntlet of trials in the laboratory. By stimulating it with electric pulses, they measured its contractile strength, showing that it was more than 10 times stronger than any previous engineered muscles. They damaged it with a toxin found in snake venom to prove that the satellite cells could activate, multiply and successfully heal the injured muscle fibers.Then they moved it out of a dish and into a mouse.With the help of Greg Palmer, an assistant professor of radiation oncology in the Duke University School of Medicine, the team inserted their lab-grown muscle into a small chamber placed on the backs of live mice. The chamber was then covered by a glass panel. Every two days for two weeks, Juhas imaged the implanted muscles through the window to check on their progress.By genetically modifying the muscle fibers to produce fluorescent flashes during calcium spikes — which cause muscle to contract — the researchers could watch the flashes become brighter as the muscle grew stronger.”We could see and measure in real time how blood vessels grew into the implanted muscle fibers, maturing toward equaling the strength of its native counterpart,” said Juhas.The engineers are now beginning work to see if their biomimetic muscle can be used to repair actual muscle injuries and disease.”Can it vascularize, innervate and repair the damaged muscle’s function?” asked Bursac. …

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Earth’s dynamic interior: Multiple compositional components of Earth’s deep mantle carried up to surface

Seeking to better understand the composition of the lowermost part of Earth’s mantle, located nearly 2,900 kilometers (1,800 miles) below the surface, a team of Arizona State University researchers has developed new simulations that depict the dynamics of deep Earth. A paper published March 30 in Nature Geoscience reports the team’s findings, which could be used to explain the complex geochemistry of lava from hotspots such as Hawaii.Mantle convection is the driving force behind continental drift and causes earthquakes and volcanoes on the surface. Through mantle convection, material from the lowermost part of Earth’s mantle could be carried up to the surface, which offers insight into the composition of the deep Earth. Earth’s core is very hot (~4000 K) and rocks at the core mantle boundary are heated and expand to have a lower density. These hot rocks (also called mantle plumes) could migrate to the surface because of buoyancy.Observations, modeling and predictions have indicated that the deepest mantle is compositionally complex and continuously churning and changing.”The complex chemical signatures of hotspot basalts provide evidence that the composition of the lowermost part of Earth’s mantle is different from other parts. The main question driving this research is how mantle plumes and different compositional components in Earth’s mantle interact with each other, and how that interaction leads to the complex chemistry of hotspot basalts. The answer to this question is very important for us to understand the nature of mantle convection,” explains lead author Mingming Li, who is pursuing his Ph.D. in geological sciences.”Obviously, we cannot go inside of Earth to see what is happening there. However, the process of mantle convection should comply with fundamental physics laws, such as conservation of mass, momentum and energy. What we have done is to simulate the process of mantle convection by solving the equations which controls the process of mantle convection,” says Li.It has long been suggested that Earth’s mantle contains several different compositional reservoirs, including an ancient more-primitive reservoir at the lowermost mantle, recycled oceanic crust and depleted background mantle. …

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‘Best practices’ nutrition measurement for researchers

At first glance, measuring what the common fruit fly eats might seem like a trivial matter, but it is absolutely critical when it comes to conducting studies of aging, health, metabolism and disease. How researchers measure consumption can make all the difference in the accuracy of a study’s conclusions.Scientists from the Florida campus of The Scripps Research Institute (TSRI) have developed what amounts to a best practices guide to the most accurate way of measuring fruit fly food consumption that could lead to more informed research and better decisions about directions in further studies.”While our study isn’t the final technical reference on measuring fly food consumption, it will help guide researchers to think more carefully about nutrition and nutrient intake in their own studies,” said TSRI Assistant Professor William Ja, who led the study, which was published online ahead of print on March 30, 2014 by the journal Nature Methods.Researchers, Ja said, generally haven’t given sufficient thought to feeding and nutrient intake when it comes to measuring fruit fly behavior, metabolism and health.”If you’re making a huge effort to change an animal’s diet and trying to draw conclusions about what nutrition and nutrients do to animal health and lifespan,” he said, “then one of the most fundamental parameters is accurately measuring food intake.”TSRI Research Associate Sonali Deshpande, a first author of the study with graduate student Ariadna Amador and former TSRI Research Associate Gil Carvalho, underlined the importance of using the best measurement methods. “Drug studies, in particular, where compounds are added to fly food, are difficult to interpret without proper measurement of food and drug intake,” she said.In the study, the team determined that radioisotope labeling food is the most sensitive and consistently accurate feeding method now available — levels of accumulated isotope are later measured in the animals. This method’s main limitation appears to be underestimation of consumption due to excretion.For the most accurate measurement, the study suggested pairing radioisotope labeling with a more low-tech approach, such as the capillary feeder (CAFE). The CAFE assay, introduced by Ja in 2007, is similar to a water dispenser used for pet hamsters, but on a smaller scale.”In a significant number of studies, we found that researchers appeared indifferent to the impact feeding might have on the experiment,” Ja said. “This doesn’t seem like good science to me. Can you imagine doing a mouse experiment, saying that you watched mice for four hours and saw no difference in feeding, then make conclusions about total caloric intake over days or longer?”Story Source:The above story is based on materials provided by Scripps Research Institute. Note: Materials may be edited for content and length.

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Chronic stress in early life causes anxiety, aggression in adulthood, neurobiologists find

In recent years, behavioral neuroscientists have debated the meaning and significance of a plethora of independently conducted experiments seeking to establish the impact of chronic, early-life stress upon behavior — both at the time that stress is experienced, and upon the same individuals later in life, during adulthood.These experiments, typically conducted in rodents, have on the one hand clearly indicated a link between certain kinds of early stress and dysfunction in the neuroendocrine system, particularly in the so-called HPA axis (hypothalamic-pituitary-adrenal), which regulates the endocrine glands and stress hormones including corticotropin and glucocorticoid.Yet the evidence is by no means unequivocal. Stress studies in rodents have also clearly identified a native capacity, stronger in some individuals than others, and seemingly weak or absent in still others, to bounce back from chronic early-life stress. Some rodents subjected to early life stress have no apparent behavioral consequences in adulthood — they are disposed neither to anxiety nor depression, the classic pathologies understood to be induced by stress in certain individuals.Today, a research team led by Associate Professor Grigori Enikolopov of Cold Spring Harbor Laboratory (CSHL) reports online in the journal PLoS One the results of experiments designed to assess the impacts of social stress upon adolescent mice, both at the time they are experienced and during adulthood. Involving many different kinds of stress tests and means of measuring their impacts, the research indicates that a “hostile environment in adolescence disturbs psychoemotional state and social behaviors of animals in adult life,” the team says.The tests began with 1-month-old male mice — the equivalent, in human terms of adolescents — each placed for 2 weeks in a cage shared with an aggressive adult male. The animals were separated by a transparent perforated partition, but the young males were exposed daily to short attacks by the adult males. This kind of chronic activity produces what neurobiologists call social-defeat stress in the young mice. These mice were then studied in a range of behavioral tests.”The tests assessed levels of anxiety, depression, and capacity to socialize and communicate with an unfamiliar partner,” explains Enikolopov. These experiments showed that in young mice chronic social defeat induced high levels of anxiety helplessness, diminished social interaction, and diminished ability to communicate with other young animals. Stressed mice also had less new nerve-cell growth (neurogenesis) in a portion of the hippocampus known to be affected in depression: the subgranular zone of the dentate gyrus.Another group of young mice was also exposed to social stress, but was then placed for several weeks in an unstressful environment. Following this “rest” period, these mice, now old enough to be considered adults, were tested in the same manner as the other cohort.In this second, now-adult group, most of the behaviors impacted by social defeat returned to normal, as did neurogenesis, which retuned to a level seen in healthy controls. …

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Tumor suppressor gene linked to stem cells, cancer biologists report

Just as archeologists try to decipher ancient tablets to discern their meaning, UT Southwestern Medical Center cancer biologists are working to decode the purpose of an ancient gene considered one of the most important in cancer research.The p53 gene appears to be involved in signaling other cells instrumental in stopping tumor development. But the p53 gene predates cancer, so scientists are uncertain what its original function is.In trying to unravel the mystery, Dr. John Abrams, Professor of Cell Biology at UT Southwestern, and his team made a crucial new discovery — tying the p53 gene to stem cells. Specifically, his lab found that when cellular damage is present, the gene is hyperactive in stem cells, but not in other cells. The findings suggest p53’s tumor suppression ability may have evolved from its more ancient ability to regulate stem cell growth.”The discovery was that only the stem cells light up. None of the others do. The exciting implication is that we are able to understand the function of p53 in stem cells,” said Dr. Abrams, Chair of the Genetics and Development program in UT Southwestern’s Graduate School of Biomedical Sciences. “We may, in fact, have some important answers for how p53 suppresses tumors.”The findings appear online in the journal eLife, a joint initiative of the Howard Hughes Medical Institute, the Max Planck Society, and the Wellcome Trust.p53 is one of the hardest working and most effective allies in the fight against cancer, said Dr. Abrams. …

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Biological testing tool, ScanDrop, tests in fraction of time and cost of industry standard

Northeastern University professor of pharmaceutical sciences, Tania Konry, has developed a single instrument that can conduct a wide range of biological scans in a fraction of the time and cost of industry standard equipment. That’s because it uses considerably less material and ultra-sensitive detection methods to do the same thing.Currently, researchers face enormous time constraints and financial hurdles from having to run these analyses on a regular basis. Hundreds of dollars and 24 hours are what’s required to scan biological materials for important biomarkers that signal diseases such as diabetes or cancer. And suppose you wanted to monitor live cancer cells. For that you’d have to use an entirely different method. It takes just as long but requires a whole other set of expensive top-end instrumentation. Want to look at bacteria instead? Be prepared to wait a few days for it to grow before you can get a meaningful result.Konry’s creation, ScanDrop, is a portable instrument no bigger than a shoebox that has the capacity to detect a variety of biological specimen. For that reason it will benefit a wide range of users beyond the medical community, including environmental monitoring and basic scientific research.The instrument acts as a miniature science lab, of sorts. It contains a tiny chip, made of polymer or glass, that is connected to equally tiny tubes. …

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Cereal flake size influences calorie intake

People eat more breakfast cereal, by weight, when flake size is reduced, according to Penn State researchers, who showed that when flakes are reduced by crushing, people pour a smaller volume of cereal into their bowls, but still take a greater amount by weight and calories.”People have a really hard time judging appropriate portions,” said Barbara Rolls, professor of nutritional sciences and Helen A. Guthrie Chair in Nutrition. “On top of that you have these huge variations in volume that are due to the physical characteristics of foods, such as the size of individual pieces, aeration and how things pile up in a bowl. That adds another dimension to the difficulty of knowing how much to take and eat.”According to Rolls, national dietary guidelines define recommended amounts of most food groups in terms of measures of volume such as cups.”This can be a problem because, for most foods, the recommended amounts have not been adjusted for variations in physical properties that affect volume, such as aeration, cooking, and the size and shape of individual pieces.” Rolls said. “The food weight and energy required to fill a given volume can vary, and this variation in the energy content of recommended amounts could be a challenge to the maintenance of energy balance.”The researchers tested the influence of food volume on calorie intake by systematically reducing the flake size of a breakfast cereal with a rolling pin so that the cereal was more compact and the same weight filled a smaller volume. In a crossover design, the team recruited 41 adults to eat cereal for breakfast once a week for four weeks. The cereal was either standard wheat flakes or the same cereal crushed to reduce the volume to 80 percent, 60 percent or 40 percent of the standard. The researchers provided a constant weight of cereal in an opaque container and participants poured the amount they wanted into a bowl, added fat-free milk and non-calorie sweetener as desired and consumed as much as they wanted.The researchers reported their results in the current issue of the Journal of the Academy of Nutrition and Dietetics.The research showed that as flake size was reduced, subjects poured a smaller volume of cereal, but still took a significantly greater amount by weight and energy content. Despite these differences, subjects estimated that they had taken a similar number of calories of all versions of the cereal. They ate most of the cereal they took, so as flake size was reduced, breakfast energy intake increased.”When faced with decreasing volumes of cereal, the people took less cereal,” Rolls said. …

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Million suns shed light on fossilized plant

Scientists have used one of the brightest lights in the Universe to expose the biochemical structure of a 50 million-year-old fossil plant to stunning visual effect.The team of palaeontologists, geochemists and physicists investigated the chemistry of exceptionally preserved fossil leaves from the Eocene-aged ‘Green River Formation’ of the western United States by bombarding the fossils with X-rays brighter than a million suns produced by synchrotron particle accelerators.Researchers from Britain’s University of Manchester and Diamond Light Source and the Stanford Synchrotron Radiation Lightsource in the US have published their findings, along with amazing images, in Metallomics; one of the images is featured on the cover of the latest edition of the Royal Society of Chemistry journal.Lead author Dr Nicholas Edwards, a postdoctoral researcher at The University of Manchester, said: “The synchrotron has already shown its potential in teasing new information from fossils, in particular our group’s previous work on pigmentation in fossil animals. With this study, we wanted to use the same techniques to see whether we could extract a similar level of biochemical information from a completely different part of the tree of life.”To do this we needed to test the chemistry of the fossil plants to see if the fossil material was derived directly from the living organisms or degraded and replaced by the fossilisation process.”We know that plant chemistry can be preserved over hundreds of millions of years — this preserved chemistry powers our society today in the form of fossil fuels. However, this is just the ‘combustible’ part; until now no one has completed this type of study of the other biochemical components of fossil plants, such as metals.”By combining the unique capabilities of two synchrotron facilities, the team were able to produce detailed images of where the various elements of the periodic table were located within both living and fossil leaves, as well as being able to show how these elements were combined with other elements.The work shows that the distribution of copper, zinc and nickel in the fossil leaves was almost identical to that in modern leaves. Each element was concentrated in distinct biological structures, such as the veins and the edges of the leaves, and the way these trace elements and sulphur were attached to other elements was very similar to that seen in modern leaves and plant matter in soils.Co-author Professor Roy Wogelius, from Manchester’s School of Earth, Atmospheric and Environmental Sciences, said: “This type of chemical mapping and the ability to determine the atomic arrangement of biologically important elements, such as copper and sulphur, can only be accomplished by using a synchrotron particle accelerator.”In one beautiful specimen, the leaf has been partially eaten by prehistoric caterpillars — just as modern caterpillars feed — and their feeding tubes are preserved on the leaf. The chemistry of these fossil tubes remarkably still matches that of the leaf on which the caterpillars fed.”The data from a suite of other techniques has led the team to conclude that the chemistry of the fossil leaves is not wholly sourced from the surrounding environment, as has previously been suggested, but represents that of the living leaves. Another modern-day connection suggests a way in which these specimens are so beautifully preserved over millions of years.Manchester palaeontologist and co-author Dr Phil Manning said: “We think that copper may have aided preservation by acting as a ‘natural’ biocide, slowing down the usual microbial breakdown that would destroy delicate leaf tissues. This property of copper is used today in the same wood preservatives that you paint on your garden fence before winter approaches.”Story Source:The above story is based on materials provided by Manchester University. Note: Materials may be edited for content and length.

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Sensing gravity with acid: Scientists discover role for protons in neurotransmission

While probing how organisms sense gravity and acceleration, scientists at the Marine Biological Laboratory (MBL) and the University of Utah uncovered evidence that acid (proton concentration) plays a key role in communication between neurons. The surprising discovery is reported this week in the Proceedings of the National Academy of Sciences.The team, led by the late MBL senior scientist Stephen M. Highstein, discovered that sensory cells in the inner ear continuously transmit information on orientation of the head relative to gravity and low-frequency motion to the brain using protons as the key means of synaptic signal transmission. (The synapse is the structure that allows one neuron to communicate with another by passing a chemical or electrical signal between them.)”This addresses how we sense gravity and other low-frequency inertial stimuli, like acceleration of an automobile or roll of an airplane,” says co-author Richard Rabbitt, a professor at University of Utah and adjunct faculty member in the MBL’s Program in Sensory Physiology and Behavior. “These are very long-lasting signals requiring a a synapse that does not fatigue or lose sensitivity over time. Use of protons to acidify the space between cells and transmit information from one cell to another could explain how the inner ear is able to sense tonic signals, such as gravity, in a robust and energy efficient way.”The team found that this novel mode of neurotransmission between the sensory cells (type 1 vestibular hair cells) and their target afferent neurons (calyx nerve terminals), which send signals to the brain, is continuous or nonquantal. This nonquantal transmission is unusual and, for low-frequency stimuli like gravity, is more energy efficient than traditional synapses in which chemical neurotransmitters are packaged in vesicles and released quantally.The calyx nerve terminal has a ball-in-socket shape that envelopes the sensory hair cell and helps to capture protons exiting the cell. “The inner-ear vestibular system is the only place where this particular type of synapse is present,” Rabbitt says. “But the fact that protons are playing a key role here suggests they are likely to act as important signaling molecules in other synapses as well.”Previously, Erik Jorgensen of University of Utah (who recently received a Lillie Research Innovation Award from the MBL and the University of Chicago) and colleagues discovered that protons act as signaling molecules between muscle cells in the worm C. elegans and play an important role in muscle contraction. …

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Gene silencing instructions acquired through ‘molecular memory’ tags on chromatin

Scientists at Indiana University have unlocked one of the mysteries of modern genetics: how acquired traits can be passed between generations in a process called epigenetic inheritance. The new work finds that cells don’t know to silence some genes based on information hardwired into their DNA sequences, but recognize heritable chemical marks that are added to the genes. These chemical tags serve as a form of molecular memory, allowing cells to recognize the genes and remember to silence them again in each new generation.The discovery made by a 12-member all-Indiana University team of scientists led by IU biologist and biochemist Craig Pikaard provides important new insight into how plant cells know to silence a genetic locus — that specific place on a chromosome where a gene is located — in every successive generation.Rather than rely on intrinsic, DNA sequence-based information, the cells instead must recall the need to silence specific loci by relying on chemical marks displayed on the complex of DNA and proteins called chromatin. Addition, or removal, of one-carbon (methyl) or two-carbon (acetyl) chemical tags are ways of modifying chromatin that can impart additional, epigenetic (literally, “above genetic”) information to a locus beyond the genetic information encoded in the DNA.The ability to perpetuate chromatin marks serves as a form of epigenetic memory that confers what Pikaard calls silent locus identity, a pre-established state that is needed for the cell to deliver to the loci the machinery that actually accomplishes silencing in a multi-step process known as RNA-directed DNA methylation (RdDM). RdDM involves short-interfering RNAs (siRNA), tiny RNA molecules that are 24 nucleotides long and that guide the addition of methyl groups to matching DNA strands, ultimately rendering the genes inactive.”Importantly, this work shows that silent locus identity is required for, but separable from, actual gene silencing,” Pikaard said. “We’ve found that epigenetic inheritance is a two-step process, with the heritable specification of silent locus identity occurring before actual silencing of the locus can occur.”Scientists are interested in epigenetic inheritance because it’s a process by which heritable modifications occur in gene function without changes in the base sequence of an organism’s DNA being required. Disease states such as cancer, which occur sporadically during an individual’s lifetime, are increasingly recognized as having an epigenetic basis. Pikaard said the new work not only sheds important new light on the mechanisms responsible for epigenetic inheritance, a topic of broad interest in the fields of genetics and chromosome biology, but it also helps explain the basis for the recruitment of two plant-specific gene silencing enzymes — the RNA polymerases Pol IV and Pol V — first identified by Pikaard in 1999.Specifically, the researchers tested and identified the relationship between histone deacetylase 6 (HDA6), an enzyme that removes acetyl groups from histones, and the CG DNA sequence maintenance methyltransferase, MET1, and discovered that their partnership in maintenance methylation can explain the perpetuation of epigenetic memory that accounts for silent locus identity.”Collectively, our results show that silent locus identity is perpetuated from generation to generation through the actions of HDA6 and MET1,” Pikaard said. “These activities are not sufficient to silence the loci but maintain a chromatin state that is required for Pol IV recruitment, siRNA biogenesis and RdDM, which is what ultimately silences the loci.” When the team removed the RdDM pathway in Pol IV and Pol V mutant strains of the model plant Arabidopsis thaliana (rockcress), all gene silencing was lost, but silent locus identity remained. They then removed the HDA6 and MET1-dependent process that specifies silent locus identity and, importantly, the epigenetic memory required for silent locus identity was lost and unable to be regained.Story Source:The above story is based on materials provided by Indiana University. …

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Braking system for immune responses

For the first time, researchers have identified a receptor on human cells that specifically recognizes crystals. It is found on immune cells and binds uric acid crystals, which trigger gout but also control immune responses. The team, led by researchers from Technische Universitt Mnchen (TUM)’s Klinikum rechts der Isar hospital have published their findings in the Immunity journal.The surface of immune system cells is home to a number of receptors which are able to detect pathogens. As soon as these receptors are activated, inflammation occurs and the body’s defense mechanisms kick in. Immune cells also have receptors that regulate or even suppress immunological responses to prevent damage to individual cells.There are other immune receptors that recognize endogenous substances that are released when tissue damage or cell death occurs. As such, the organism can defend itself even in cases where the damage caused by the pathogen, but not the pathogen itself, is detected.With the discovery of the surface molecule Clec12a from the family of C-type lectin receptors, the team led by Prof. Jrgen Ruland of Klinikum rechts der Isar have found the first known immune receptor for uric acid crystals. Uric acid is a break-down product of nucleic acids like DNA in response to cell damage. Whenever a large number of cells die, for example when a tumor is being medically treated or during an infection, the uric acid becomes more concentrated and the molecules crystallize.Immune responses have to be regulatedUric acid crystals also form when tissue is damaged and they boost the immune response. However, Clec12a limits the immune response instead of increasing it. …

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Radiation damage at the root of Chernobyl’s ecosystems

Radiological damage to microbes near the site of the Chernobyl disaster has slowed the decomposition of fallen leaves and other plant matter in the area, according to a study just published in the journal Oecologia. The resulting buildup of dry, loose detritus is a wildfire hazard that poses the threat of spreading radioactivity from the Chernobyl area.Tim Mousseau, a professor of biology and co-director of the Chernobyl and Fukushima Research Initiatives at the University of South Carolina, has done extensive research in the contaminated area surrounding the Chernobyl nuclear facility, which exploded and released large quantities of radioactive compounds in the Ukraine region of the Soviet Union in 1986. He and frequent collaborator Anders Mller of Universit Paris-Sud noticed something unusual in the course of their work in the Red Forest, the most contaminated part of the Chernobyl Exclusion Zone.”We were stepping over all these dead trees on the ground that had been killed by the initial blast,” Mousseau said. “Some 15 or 20 years later, these tree trunks were in pretty good shape. If a tree had fallen in my backyard, it would be sawdust in 10 years or so.”They set out to assess the rate at which plant material decomposed as a function of background radiation, placing hundreds of samples of uncontaminated leaf litter (pine needles and oak, maple and birch leaves) in mesh bags throughout the area. The locations were chosen to cover a range of radiation doses, and the samples were retrieved after nine months outdoors.A statistical analysis of the weight loss of each leaf litter sample after those nine months showed that higher background radiation was associated with less weight loss. The response was proportional to radiation dose, and in the most contaminated regions, the leaf loss was 40 percent less than in control regions in Ukraine with normal background radiation levels.They also measured the thickness of the forest floor in the same areas where samples were placed. They found that it was thicker in places with higher background radiation.The team concluded that the bacteria and fungi that decompose plant matter in healthy ecosystems are hindered by radioactive contamination. They showed a smaller effect for small invertebrates, such as termites, that also contribute to decomposition of plant biomass.According to Mousseau, slower decomposition is likely to indirectly slow plant growth, too, given that the products of decomposition are nutrients for new plants. The team recently reported diminished tree growth near Chernobyl, which he says likely results both from direct radiation effects and indirect effects such as reduced nutrient supply.”It’s another facet of the impacts of low-dose-rate radioactive contaminants on the broader ecosystem,” Mousseau says. …

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Ants plant tomorrow’s rainforest

Tropical montane rain forests are highly threatened and their remnants are often surrounded by deforested landscapes. For the regeneration of these degraded areas, seed dispersal of forest trees plays a crucial role but is still poorly understood. Most tree species are dispersed by birds and mammals, but also by ants. A study published today in the Journal of Ecology by a team from the LOEWE Biodiversity and Climate Research Centre and the University of Halle-Wittenberg demonstrates the importance of this hitherto neglected ecosystem function for the restoration of montane rain forests. Ants promote the regeneration of these forests by dispersing seeds to safe sites for tree establishment.The Yungas, a region on the eastern slopes of the Bolivian Andes near La Paz, are marked by elongated valleys with relicts of the original mountain rain forest. Due to land-use practices like slash-and-burn agriculture and the extension of coca plantations, the forests are highly fragmented. The forest relicts are surrounded by an open, largely degraded cultural landscape. In this context, the team conducted experiments to find out to what extent ants contribute to the dispersal of a widespread, primarily bird-dispersed tree (Clusia trochiformis) and tested whether this ecosystem function may contribute to the restoration of deforested areas.The red, lipid-rich aril, a fleshy pulp surrounding the seeds of Clusia, is highly attractive to many animals. Birds are the primary dispersers. They feed on the nutritious part of the fruits, the fleshy aril, and defecate the seeds. …

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U.S. headache sufferers get $1 billion worth of brain scans each year

One in eight visits to a a doctor for a headache or migraine end up with the patient going for a brain scan, at a total cost of about $1 billion a year, a new University of Michigan Medical School study finds.And many of those MRI and CT scans — and costs — are probably unnecessary, given the very low odds that serious issues lurk in the patients’ brains.In fact, several national guidelines for doctors specifically discourage scanning the brains of patients who complain of headache and migraine. But the new study shows the rate of brain scans for headache has risen, not fallen, since guidelines for doctors came out. This may mean that patient demand for scans drives much of the cost.The researchers suggest that better education of the public, and insurance plan designs that ask patients to pay part of the cost based on the likely value of the scan for them, may be needed to reduce unnecessary use and spending.The research, published in JAMA Internal Medicine by a team from the U-M Department of Neurology, uses national data on headache-related doctor visits and neuroimaging scans by people over age 18, and calculates estimated total costs across multiple years.In all, 51.1 million headache-related patient visits occurred between 2007 and 2010 — nearly half of them related to migraine. The vast majority were by people under the age of 65, and more than three-quarters of the patients were women. In those same four years, 12.4 percent of these visits resulted in a brain MRI or CT.The researchers estimated the total cost of the four years’ worth of scans at $3.9 billion, based on typical Medicare payments to doctors for imaging.”This is a conservative cost estimate based on what Medicare would pay for these tests. CTs and MRIs are commonly ordered for headache and migraine, and increasing over time, despite the fact that there are rare circumstances where imaging should be used,” says Brian Callaghan, M.D., M.S., the U-M neurologist who led the team performing the study.”Lots of guidelines say we shouldn’t do this — including ones from neurology and radiology groups — but yet we still do it a lot. This is a source of tremendous cost in health care without a lot of evidence to justify the cost,” he notes.A billion dollars’ worth of reassurance?Doctors might order a CT or MRI scan for a headache or migraine to put patients’ minds at ease about fears that a malignant brain tumor, aneurysm, arteriovenous malformation or other issue might be causing their symptoms.And even if the patient doesn’t meet the conditions that guidelines say can benefit most from brain imaging — for instance, someone with an abnormal neurological exam or a known cancer — doctors might order a scan at a patient’s request to protect themselves legally.But past research shows that only 1 percent to 3 percent of scans of patients with repeated headaches find that a growth or blood vessel problem in the brain is to blame. And many of the issues that scans spot turn out not to pose a serious threat — or may not require treatment right away.”There’s solid research showing that the number of times you find serious issues on these scans in headache patients is about the same as that for a randomly chosen group of non-headache patients,” he says. “And a lot of the things we find on such scans aren’t necessarily something we will do something about.”Callaghan notes that the current study, based on data from the Centers for Disease Control & Prevention’s National Ambulatory Care Medical Survey, couldn’t detect which scans met guidelines and which didn’t.But the fact that 14.7 percent of people who saw a doctor for headache or migraine in 2010 went on to have a brain scan would not be expected if guidelines were being followed, he says. The team is working on further research into the appropriateness of the scans ordered for patients.He also notes that the $1 billion a year estimate doesn’t include other costs, including follow-up tests and any treatment that might be ordered if a scan finds something. …

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Harnessing everyday motion to power mobile devices

Imagine powering your cell phone by simply walking around your office or rubbing it with the palm of your hand. Rather than plugging it into the wall, you become the power source. Researchers at the 247th National Meeting & Exposition of the American Chemical Society (ACS) presented these commercial possibilities and a unique vision for green energy.The meeting, attended by thousands of scientists, features more than 10,000 reports on new advances in science and other topics. It is being held at the Dallas Convention Center and area hotels through Thursday.Zhong Lin Wang, Ph.D., and his team, including graduate student Long Lin who presented the work, have set out to transform the way we look at mechanical energy. Conventional energy sources have so far relied on century-old science that requires scattered, costly power plants and a grid to distribute electricity far and wide.”Today, coal, natural gas and nuclear power plants all use turbine-engine driven, electromagnetic-induction generators,” Wang explained. “For a hundred years, this has been the only way to convert mechanical energy into electricity.”But a couple of years ago, Wang’s team at the Georgia Institute of Technology was working on a miniature generator based on an energy phenomenon called the piezoelectric effect, which is electricity resulting from pressure. But to their surprise, it produced more power than expected. They investigated what caused the spike and discovered that two polymer surfaces in the device had rubbed together, producing what’s called a triboelectric effect — essentially what most of us know as static electricity.Building on that fortuitous discovery, Wang then developed the first triboelectric nanogenerator, or “TENG.” He paired two sheets of different materials together — one donates electrons, and the other accepts them. When the sheets touch, electrons flow from one to the other. When the sheets are separated, a voltage develops between them.Since his lab’s first publication on TENG in 2012, they have since boosted the power output density by a factor of 100,000, with the output power density reaching 300 Watts per square meter. …

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Characterization of stink bug saliva proteins opens door to controlling pests

Brown marmorated stink bugs cause millions of dollars in crop losses across the United States because of the damage their saliva does to plant tissues. Researchers at Penn State have developed methods to extract the insect saliva and identify the major protein components, which could lead to new pest control approaches.”Until now, essentially nothing was known about the composition of stink bug saliva, which is surprising given the importance of these insects as pests and the fact that their saliva is the primary cause of feeding injury to plants and crop losses,” said Gary Felton, professor and head of the Department of Entomology. “Other than using synthetic pesticides, there have been few alternative approaches to controlling these pests. By identifying the major protein components of saliva, it now may be possible to target the specific factors in saliva that are essential for their feeding and, therefore, design new approaches for controlling stink bugs.”The team reported its results in PLOS ONE.According to Felton, stink bugs produce two types of saliva that are required for successful feeding. Watery saliva helps stink bugs to digest their food. Sheath saliva surrounds stink bugs’ mouthparts and hardens to prevent spillage of sap during feeding. The hardened “sheath” remains attached to the plant when the insect is finished feeding.”Unlike a chewing insect, which causes damage by removing plant tissue, stink bugs pierce plant tissue and suck nutrients from the plant,” said Michelle Peiffer, research support assistant. “During this process, stink bugs also deposit saliva onto the plant. The interaction between this saliva and the plant is what causes the cosmetic and physiological changes that make crops unmarketable.”To extract the two types of saliva from brown marmorated stink bugs, Felton and Peiffer first collected adult bugs from homes and fields in central Pennsylvania and maintained them in their laboratory.The researchers chilled the insects on ice. As the insects returned to room temperature, their watery saliva was secreted from the tips of their beaks. …

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Plasma plumes help shield Earth from damaging solar storms

Earth’s magnetic field, or magnetosphere, stretches from the planet’s core out into space, where it meets the solar wind, a stream of charged particles emitted by the sun. For the most part, the magnetosphere acts as a shield to protect Earth from this high-energy solar activity.But when this field comes into contact with the sun’s magnetic field — a process called “magnetic reconnection” — powerful electrical currents from the sun can stream into Earth’s atmosphere, whipping up geomagnetic storms and space weather phenomena that can affect high-altitude aircraft, as well as astronauts on the International Space Station.Now scientists at MIT and NASA have identified a process in Earth’s magnetosphere that reinforces its shielding effect, keeping incoming solar energy at bay.By combining observations from the ground and in space, the team observed a plume of low-energy plasma particles that essentially hitches a ride along magnetic field lines — streaming from Earth’s lower atmosphere up to the point, tens of thousands of kilometers above the surface, where the planet’s magnetic field connects with that of the sun. In this region, which the scientists call the “merging point,” the presence of cold, dense plasma slows magnetic reconnection, blunting the sun’s effects on Earth.”The Earth’s magnetic field protects life on the surface from the full impact of these solar outbursts,” says John Foster, associate director of MIT’s Haystack Observatory. “Reconnection strips away some of our magnetic shield and lets energy leak in, giving us large, violent storms. These plasmas get pulled into space and slow down the reconnection process, so the impact of the sun on the Earth is less violent.”Foster and his colleagues publish their results in this week’s issue of Science. The team includes Philip Erickson, principal research scientist at Haystack Observatory, as well as Brian Walsh and David Sibeck at NASA’s Goddard Space Flight Center.Mapping Earth’s magnetic shieldFor more than a decade, scientists at Haystack Observatory have studied plasma plume phenomena using a ground-based technique called GPS-TEC, in which scientists analyze radio signals transmitted from GPS satellites to more than 1,000 receivers on the ground. Large space-weather events, such as geomagnetic storms, can alter the incoming radio waves — a distortion that scientists can use to determine the concentration of plasma particles in the upper atmosphere. Using this data, they can produce two-dimensional global maps of atmospheric phenomena, such as plasma plumes.These ground-based observations have helped shed light on key characteristics of these plumes, such as how often they occur, and what makes some plumes stronger than others. But as Foster notes, this two-dimensional mapping technique gives an estimate only of what space weather might look like in the low-altitude regions of the magnetosphere. To get a more precise, three-dimensional picture of the entire magnetosphere would require observations directly from space.Toward this end, Foster approached Walsh with data showing a plasma plume emanating from Earth’s surface, and extending up into the lower layers of the magnetosphere, during a moderate solar storm in January 2013. …

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For older drivers one drink may be one too many, study finds

You may have only had one glass of wine with dinner, but if you’re 55 or older, that single serving may hit you hard enough to make you a dangerous driver. So, baby boomers, what you suspected is true: you can’t party like you used to.Sara Jo Nixon, a professor in the departments of psychiatry and psychology at the University of Florida and doctoral candidate Alfredo Sklar tested how drinking legally non-intoxicating levels of alcohol affect the driving skills of two age groups: 36 people ages 25 to 35 and 36 people ages 55 to 70. They found that although neither age group imbibed enough alcohol to put them over the legal driving limit, a blood alcohol level of 0.08, just one drink can affect the driving abilities of older drivers.Based on the study findings published in the journal Psychopharmacology in February, the researchers say it could be time to reassess legal blood alcohol levels for all drivers.”These simulations have been used a lot in looking at older adults, and they have been used at looking how alcohol affects the driving of younger adults, but no one’s ever looked at the combination of aging drivers and alcohol,” Sklar said.The study is the latest in a body of work by Nixon and her team that looks at how even moderate doses of alcohol affect aging adults.At the beginning of the study, both groups completed a driving task completely sober. The task took the drivers down a simulated winding 3-mile stretch of country road. The drivers stared straight ahead at a large computer monitor. Two computer monitors flanked the first, mimicking the side windows of a car and what the drivers would see in their peripheral vision. A stereo system played driving sounds. A console included a steering wheel and brake and gas pedals. Occasionally, the drivers would encounter an oncoming car, but they did not encounter other distractions.”There wasn’t even a cow,” said Nixon, who also is co-vice chair and chief of the division of addiction research in the department of psychiatry in the UF College of Medicine and UF’s Evelyn F. and William L. …

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