Steam energy from the sun: New spongelike structure converts solar energy into steam

A new material structure developed at MIT generates steam by soaking up the sun. The structure — a layer of graphite flakes and an underlying carbon foam — is a porous, insulating material structure that floats on water. When sunlight hits the structure’s surface, it creates a hotspot in the graphite, drawing water up through the material’s pores, where it evaporates as steam. The brighter the light, the more steam is generated.The new material is able to convert 85 percent of incoming solar energy into steam — a significant improvement over recent approaches to solar-powered steam generation. What’s more, the setup loses very little heat in the process, and can produce steam at relatively low solar intensity. This would mean that, if scaled up, the setup would likely not require complex, costly systems to highly concentrate sunlight.Hadi Ghasemi, a postdoc in MIT’s Department of Mechanical Engineering, says the spongelike structure can be made from relatively inexpensive materials — a particular advantage for a variety of compact, steam-powered applications.”Steam is important for desalination, hygiene systems, and sterilization,” says Ghasemi, who led the development of the structure. “Especially in remote areas where the sun is the only source of energy, if you can generate steam with solar energy, it would be very useful.”Ghasemi and mechanical engineering department head Gang Chen, along with five others at MIT, report on the details of the new steam-generating structure in the journal Nature Communications.Cutting the optical concentrationToday, solar-powered steam generation involves vast fields of mirrors or lenses that concentrate incoming sunlight, heating large volumes of liquid to high enough temperatures to produce steam. However, these complex systems can experience significant heat loss, leading to inefficient steam generation.Recently, scientists have explored ways to improve the efficiency of solar-thermal harvesting by developing new solar receivers and by working with nanofluids. The latter approach involves mixing water with nanoparticles that heat up quickly when exposed to sunlight, vaporizing the surrounding water molecules as steam. But initiating this reaction requires very intense solar energy — about 1,000 times that of an average sunny day.By contrast, the MIT approach generates steam at a solar intensity about 10 times that of a sunny day — the lowest optical concentration reported thus far. …

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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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Shifting evolution into reverse promises cheaper, greener way to make new drugs

This alternative approach to creating artificial organic molecules, called bioretrosynthesis, was first proposed four years ago by Brian Bachmann, associate professor of chemistry at Vanderbilt University. Now Bachmann and a team of collaborators report that they have succeeded in using the method to produce the HIV drug didanosine. The proof of concept experiment is described in a paper published online March 23 by the journal Nature Chemical Biology.”These days synthetic chemists can make almost any molecule imaginable in an academic laboratory setting,” said Bachmann. “But they can’t always make them cheaply or in large quantities. Using bioretrosynthesis, it is theoretically possible to make almost any organic molecule out of simple sugars.”Putting natural selection to use in this novel fashion has another potential advantage. “We really need a green alternative to the traditional approach to making chemicals. Bioretrosynthesis offers a method to develop environmentally friendly manufacturing processes because it relies on enzymes — the biological catalysts that make life possible — instead of the high temperatures and pressures, toxic metals, strong acids and bases frequently required by synthetic chemistry,” he said.Normally, both evolution and synthetic chemistry proceed from the simple to the complex. Small molecules are combined and modified to make larger and more complex molecules that perform specific functions. Bioretrosynthesis works in the opposite direction. It starts with the final, desired product and then uses natural selection to produce a series of specialized enzymes that can make the final product out of a chain of chemical reactions that begin with simple, commonly available compounds.Bachmann got the idea of applying natural selection in reverse from the retro-evolution hypothesis proposed in 1945 by the late Caltech geneticist Norman Horowitz. …

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Scientists ‘herd’ cells in new approach to tissue engineering

Sometimes it only takes a quick jolt of electricity to get a swarm of cells moving in the right direction.Researchers at UC Berkeley found that an electrical current can be used to orchestrate the flow of a group of cells, an achievement that could establish the basis for more controlled forms of tissue engineering and for potential applications such as “smart bandages” that use electrical stimulation to help heal wounds.In the experiments, described in a study published this week in the journal Nature Materials, the researchers used single layers of epithelial cells, the type of cells that bind together to form robust sheathes in skin, kidneys, cornea and other organs. They found that by applying an electric current of about five volts per centimeter, they could encourage cells to migrate along the direct current electric field.They were able to make the cells swarm left or right, to diverge or converge and to make collective U-turns. They also created elaborate shapes, such as a triceratops and the UC Berkeley Cal bear mascot, to explore how the population and configuration of cell sheets affect migration.Directing herds vs. individuals”This is the first data showing that direct current fields can be used to deliberately guide migration of a sheet of epithelial cells,” said study lead author Daniel Cohen, who did this work as a student in the UC Berkeley-UC San Francisco Joint Graduate Program in Bioengineering. “There are many natural systems whose properties and behaviors arise from interactions across large numbers of individual parts — sand dunes, flocks of birds, schools of fish, and even the cells in our tissues. Just as a few sheepdogs exert enormous control over the herding behavior of sheep, we might be able to similarly herd biological cells for tissue engineering.”Galvanotaxis — the use of electricity to direct cell movement — had been previously demonstrated for individual cells, but how it influences the collective motion of cells was still unclear.”The ability to govern the movement of a mass of cells has great utility as a scientific tool in tissue engineering,” said study senior author Michel Maharbiz, UC Berkeley associate professor of electrical engineering and computer sciences. “Instead of manipulating one cell at a time, we could develop a few simple design rules that would provide a global cue to control a collection of cells.”The work was borne from a project, led by Maharbiz, to develop electronic nanomaterials for medical use that was funded by the National Science Foundation’s Emerging Frontiers in Research and Innovation program. The researchers collaborated with W. James Nelson, professor of molecular and cellular physiology at Stanford University and one of the world’s top experts in cell-to-cell adhesion. Cohen is now a postdoctoral research fellow in Nelson’s lab.Possible wound healing applicationsWith our bodies full of flowing ions and salt solutions, it is no surprise that electrical signals play a big role in our physiology, from neural transmissions to muscle stimulation.”The electrical phenomenon we are exploring is distinct in that the current produced is providing a cue for cells to migrate,” said Maharbiz.The study authors are exploring the role of bioelectrical signals in the wound healing process, building upon the discovery in 1843 that an injury to the body creates a change in the electrical field at the wound site. …

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Livestock can produce food that is better for people, planet

With one in seven humans undernourished, and with the challenges of population growth and climate change, the need for efficient food production has never been greater. Eight strategies to cut the environmental and economic costs of keeping livestock, such as cows, goats and sheep, while boosting the quantity and quality of the food produced have been outlined by an international team of scientists.The strategies to make ruminant — cud-chewing — livestock a more sustainable part of the food supply, led by academics at the University of Bristol’s School of Veterinary Sciences, are outlined in a Comment piece in Nature this week.The eight strategies include:Feed animals less human food. Livestock consume an estimated one-third or more of the world’s cereal grain, which some advocate would be better used to feed people directly. Some of this could indeed be avoided by capitalising on ruminants’ ability to digest food that humans cannot eat, such as hay, silage and high-fibre crop residues. Raise regionally appropriate animals. Working to boost yields from local breeds makes more sense in the long term than importing poorly adapted breeds that are successful elsewhere. European and North American Holstein dairy cows can produce 30 litres of milk a day. Thousands of these animals have been exported to Asia and Africa in an attempt to alleviate malnutrition. But exposed to hot climates, tropical diseases and sub-optimal housing, the cows produce much less milk, and the costs of feed and husbandry far exceed those of native breeds. Farmers, therefore, should be encouraged to keep and improve livestock adapted to local conditions. …

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In grasslands remade by humans, animals may protect biodiversity: Grazers let in the light, rescue imperiled plants

A comparative study of grasslands on six continents suggests there may be a way to counteract the human-made overdose of fertilizer that threatens to permanently alter the biodiversity of the world’s native prairies.The solution is one that nature devised: let grazing animals crop the excess growth of fast growing grasses that can out-compete native plants in an over-fertilized world. And grazing works in a way that is also natural and simple. The herbivores, or grazing and browsing animals, feed on tall grasses that block sunlight from reaching the ground, making the light available to other plants.That’s the key finding of a five-year study carried out at 40 different sites around the world and scheduled for online publication March 9, 2014 in the journal Nature. More than 50 scientists belonging to the Nutrient Network, a team of scientists studying grasslands worldwide, co-authored the study.”This study has tremendous significance because human activities are changing grasslands everywhere,” said study co-author Daniel S. Gruner, associate professor of entomology at the University of Maryland. “We’re over-fertilizing them, and we’re adding and subtracting herbivores. We have a worldwide experiment going on, but it’s completely uncontrolled.”Gruner, a member of the Nutrient Network (which participants have nicknamed NutNet) since its founding in 2006, helped plan the worldwide study and analyze its results. Elizabeth Borer of the University of Minnesota was the study’s lead author.The U.N. Food and Agricultural Organization estimates that grasslands cover between one-fifth and two-fifths of the planet’s land area and are home to more than one-tenth of humankind. But like all plant communities, grasslands are suffering from too much fertilizer.As humans burn fossil fuels, dose crops with chemical fertilizers, and dispose of manure from livestock, they introduce extra nitrogen and other nutrients into the soil, air and water. …

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Mutations in leukemia gene linked to new childhood growth disorder

Mutations in a gene associated with leukemia cause a newly described condition that affects growth and intellectual development in children, new research reports.A study led by scientists at The Institute of Cancer Research, London, identified mutations in the DNA methyltransferase gene, DNMT3A, in 13 children.All the children were taller than usual for their age, shared similar facial features and had intellectual disabilities. The mutations were not present in their parents, nor in 1,000 controls from the UK population.The new condition has been called ‘DNMT3A overgrowth syndrome’.The research is published today in the journal Nature Genetics and is a part of the Childhood Overgrowth Study, which is funded by the Wellcome Trust, and aims to identify causes of developmental disorders that include increased growth in childhood. The DNMT3A gene is crucial for development because it adds the ‘methylation’ marks to DNA that determine where and when genes are active.Intriguingly, DNMT3A mutations are already known to occur in certain types of leukemia. The mutations that occur in leukemia are different from those in DNMT3A overgrowth syndrome and there is no evidence that children with DNMT3A mutations are at increased risk of cancer.Researchers at The Institute of Cancer Research (ICR), with colleagues at St George’s, University of London, The Royal Marsden NHS Foundation Trust, and genetics centres across Europe and the US, identified the mutations after analysing the genomes of 152 children with overgrowth disorders and their parents.Study leader Professor Nazneen Rahman, Head of Genetics and Epidemiology at The Institute of Cancer Research, London, and Head of Cancer Genetics at The Royal Marsden NHS Foundation Trust, said: “Our findings establish DNMT3A mutations as the cause of a novel human developmental disorder and add to the growing list of genes that appear to have dual, but distinct, roles in human growth disorders and leukemias.”The new discovery is of immediate value to the families in providing a reason for why their child has had problems. Moreover, because the mutations have arisen in the child and have not been inherited from either parent, the risk of another child in the family being similarly affected is very low. This is very welcome news for families.Study co-leader Dr Katrina Tatton-Brown, Clinical Researcher at The Institute of Cancer Research, London, and Consultant Geneticist at St George’s, University of London, said: “Having a diagnosis can make a real difference to families — I recently gave the result back to one of the families in which we identified a DNMT3A mutation and they greatly appreciated having a reason for their daughter’s condition after many years of uncertainty.”Story Source:The above story is based on materials provided by Institute of Cancer Research. Note: Materials may be edited for content and length.

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Study suggests non-uniform climate warming globally

A recent University of Oklahoma study of five decades of satellite data, model simulations and in situ observations suggests the impact of seasonal diurnal or daily warming varies between global regions affecting many ecosystem functions and services, such as food production, carbon sequestration and climate regulation. The effects of non-uniform climate warming on terrestrial ecosystems is a key challenge in carbon cycle research and for those making future predictions.Jianyang Xia, a research associate in the OU College of Arts and Sciences, says the impact of non-uniform warming is just one aspect of climate change. Shifts in precipitation and disturbances, such as wildfires, increases in the frequency of extreme temperature events, large year-to-year shifts in temperature and shifts in regional climate zones can be expected as the climate warms. A complete understanding of the consequences of climate change for carbon cycling on land requires insight into the impact of all these changes on the ecosystem.As this study suggests, the rate of climate warming varies by season and region, and between day and night. A synthesis of air temperature data from across the world reveals a greater rate of warming in winter than in summer in northern and high latitudes, but the inverse is true in some tropical regions.Also, the data show a decline in the daily temperature range over 51 percent of the globe and an increase over only 13 percent, because night-time temperatures in most locations have risen faster than daytime temperatures.From the data analyzed, a number of trends emerged in non-uniform climate warming for ecosystem carbon cycling. Spring warming will enhance ecosystem carbon uptake at high latitudes and diminish the magnitude of seasonal temperature change in these regions. Summer and autumn warming are more likely to reduce ecosystem carbon uptake in tropical ecosystems and amplify the magnitude of seasonal temperature change.The contrasting impacts of day- and night-time warming on plant carbon gain and loss are apparent in many regions. Day warming increases carbon uptake in most areas of tundra and boreal forests but decreases it in most grasslands and deserts. Night warming enhances carbon uptake in arid ecosystems, such as grassland desert but has negative impacts in other regions.Most of the existing temperature-manipulation experiments relied on continuous and uniform warming, so further research is needed to predict the effects of non-uniform climate warming on terrestrial carbon cycling. A paper on this study was accepted for early online publication on February 23, 2014, by Nature Geoscience.Story Source:The above story is based on materials provided by University of Oklahoma. …

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Large mammals were the architects in prehistoric ecosystems

Researchers from Denmark demonstrate in a study that the large grazers and browsers of the past created a mosaic of varied landscapes consisting of closed and semi-closed forests and parkland.The study is published March 3, 2014 in the Proceedings of the National Academy of Sciences.Dung beetles recount the nature of the pastThe biologists behind the new research findings synthesized decades of studies on fossil beetles, focusing on beetles associated with the dung of large animals in the past or with woodlands and trees. Their findings reveal that dung beetles were much more frequent in the previous interglacial period (from 132,000 to 110,000 years ago) compared with the early Holocene (the present interglacial period, before agriculture, from 10,000 to 5,000 years ago).”One of the surprising results is that woodland beetles were much less dominant in the previous interglacial period than in the early Holocene, which shows that temperate ecosystems consisted not just of dense forest as often assumed, but rather a mosaic of forest and parkland,” says postdoctoral fellow Chris Sandom.”Large animals in high numbers were an integral part of nature in prehistoric times. The composition of the beetles in the fossil sites tells us that the proportion and number of the wild large animals declined after the appearance of modern man. As a result of this, the countryside developed into predominantly dense forest that was first cleared when humans began to use the land for agriculture,” explains Professor Jens-Christian Svenning.Bring back the large animals to EuropeIf people want to restore self-managing varied landscapes, they can draw on the knowledge provided by the new study about the composition of natural ecosystems in the past.”An important way to create more self-managing ecosystems with a high level of biodiversity is to make room for large herbivores in the European landscape — and possibly reintroduce animals such as wild cattle, bison and even elephants. They would create and maintain a varied vegetation in temperate ecosystems, and thereby ensure the basis for a high level of biodiversity,” says senior scientist Rasmus Ejrns.The study received financial support from the 15 June Foundation and a grant from the European Research Council. To a large extent, it supports the idea that the rewilding-based approach to nature management should be incorporated to a far greater degree in nature policy in Europe -especially in the case of national parks and other large natural areas.Story Source:The above story is based on materials provided by Aarhus University. Note: Materials may be edited for content and length.

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Protective mutations for type 2 diabetes pinpointed

An international team led by researchers at the Broad Institute and Massachusetts General Hospital (MGH) has identified mutations in a gene that can reduce the risk of developing type 2 diabetes, even in people who have risk factors such as obesity and old age. The results focus the search for developing novel therapeutic strategies for type 2 diabetes; if a drug can be developed that mimics the protective effect of these mutations, it could open up new ways of preventing this devastating disease.Type 2 diabetes affects over 300 million people worldwide and is rising rapidly in prevalence. Lifestyle changes and existing medicines slow the progression of the disease, but many patients are inadequately served by current treatments. The first step to developing a new therapy is discovering and validating a “drug target” — a human protein that, if activated or inhibited, results in prevention and treatment of the disease.The current study breaks new ground in type 2 diabetes research and guides future therapeutic development in this disease. In the new study, researchers describe the genetic analysis of 150,000 patients showing that rare mutations in a gene called SLC30A8 reduce risk of type 2 diabetes by 65 percent. The results were seen in patients from multiple ethnic groups, suggesting that a drug that mimics the effect of these mutations might have broad utility around the globe. The protein encoded by SLC30A8 had previously been shown to play an important role in the insulin-secreting beta cells of the pancreas, and a common variant in that gene was known to slightly influence the risk of type 2 diabetes. However, it was previously unclear whether inhibiting or activating the protein would be the best strategy for reducing disease risk — and how large an effect could be expected.”This work underscores that human genetics is not just a tool for understanding biology: it can also powerfully inform drug discovery by addressing one of the most challenging and important questions — knowing which targets to go after,” said co-senior author David Altshuler, deputy director and chief academic officer at the Broad Institute and a Harvard Medical School professor at Massachusetts General Hospital.The use of human genetics to identify protective mutations holds great potential. Mutations in a gene called CCR5 were found to protect against infection with HIV, the virus that causes AIDS; drugs have been developed that block the CCR5 protein. A similar protective association for heart disease set off a race to discover new cholesterol-lowering drugs when mutations in the gene PCSK9 were found to lower cholesterol levels and heart disease risk. …

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Competition breeds new fish species, study finds

Competition may play an important role during the evolution of new species, but empirical evidence for this is scarce, despite being implicit in Charles Darwin’s work and support from theoretical studies.Dr Martin Genner from Bristol’s School of Biological Sciences and colleagues used population genetics and experimental evidence to demonstrate a role for competition that leads to the differentiation of new species within the highly diverse cichlid fishes of Lake Tanganyika in East Africa.They found that the cichlid fish Telmatochromis temporalis shows two genetically distinct ecomorphs (local varieties of a species whose appearance is determined by its ecological environment), that strongly differ in body size and the habitat in which they live.Dr Genner said: “We found large-sized individuals living along the rocky shoreline of Lake Tanganyika and, in the vicinity of these shores, we found small-sized individuals, roughly half the size of the large ones, that live and breed in accumulations of empty snail shells found on sand.”According to the study, the bigger fish outcompete the smaller ones, driving them away from the preferred rocky habitats and into the neighbouring sand, where the smaller fish find shelter for themselves and their eggs in empty snail shells.”In effect, big and small fish use different habitats; and because of this habitat segregation, fish usually mate with individuals of similar size. There is virtually no genetic exchange between the large- and small-bodied ectomorphs,” Dr Genner commented.Speciation occurs when genetic differences between groups of individuals accumulate over time. In the case of Telmatochromis there are no obvious obstacles to the movement and interaction of individuals. But, the non-random mating between large- and small-bodied fish sets the stage for the evolutionary play.Dr Genner said: “The relevance of our work is that it provides experimental evidence that competition for space drives differential mating in cichlid fish and, in time, leads to the formation of new species. Nature has its ways — from body size differences to the formation of new species. And clearly, size does matters for Telmatochromis and for fish diversity.”Story Source:The above story is based on materials provided by University of Bristol. Note: Materials may be edited for content and length.

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New ideas change your brain cells, research shows

A new University of British Columbia study identifies an important molecular change that occurs in the brain when we learn and remember.Published this month in Nature Neuroscience, the research shows that learning stimulates our brain cells in a manner that causes a small fatty acid to attach to delta-catenin, a protein in the brain. This biochemical modification is essential in producing the changes in brain cell connectivity associated with learning, the study finds.In animal models, the scientists found almost twice the amount of modified delta-catenin in the brain after learning about new environments. While delta-catenin has previously been linked to learning, this study is the first to describe the protein’s role in the molecular mechanism behind memory formation.”More work is needed, but this discovery gives us a much better understanding of the tools our brains use to learn and remember, and provides insight into how these processes become disrupted in neurological diseases,” says co-author Shernaz Bamji, an associate professor in UBC’s Life Sciences Institute.It may also provide an explanation for some mental disabilities, the researchers say. People born without the gene have a severe form of mental retardation called Cri-du-chat syndrome, a rare genetic disorder named for the high-pitched cat-like cry of affected infants. Disruption of the delta-catenin gene has also been observed in some patients with schizophrenia.”Brain activity can change both the structure of this protein, as well as its function,” says Stefano Brigidi, first author of the article and a PhD candidate Bamji’s laboratory. “When we introduced a mutation that blocked the biochemical modification that occurs in healthy subjects, we abolished the structural changes in brain’s cells that are known to be important for memory formation.”Story Source:The above story is based on materials provided by University of British Columbia. Note: Materials may be edited for content and length.

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Nanoparticles target anti-inflammatory drugs where needed

Researchers at the University of Illinois at Chicago have developed a system for precisely delivering anti-inflammatory drugs to immune cells gone out of control, while sparing their well-behaved counterparts. Their findings were published online Feb. 23 in Nature Nanotechnology.The system uses nanoparticles made of tiny bits of protein designed to bind to unique receptors found only on neutrophils, a type of immune cell engaged in detrimental acute and chronic inflammatory responses.In a normal immune response, neutrophils circulating in the blood respond to signals given off by injured or damaged blood vessels and begin to accumulate at the injury, where they engulf bacteria or debris from injured tissue that might cause infection. In chronic inflammation, neutrophils can pile up at the site of injury, sticking to the blood vessel walls and to each other and contributing to tissue damage.Adhesion of neutrophils to blood vessel walls is a major factor in acute lung injury, where it can impair the exchange of gases between the lungs and blood, leading to severe breathing problems. If untreated, the disease has a 50 percent mortality rate in intensive care units.Corticosteroids and non-steroidal anti-inflammatory drugs used to treat inflammatory diseases are “blunt instruments that affect the whole body and carry some significant side effects,” says Asrar B. Malik, the Schweppe Family Distinguished Professor and head of pharmacology in the UIC College of Medicine, who is lead author of the paper.Neutrophils that are stuck to blood vessels or clumped together have unique receptors on their surface that circulating neutrophils lack. Malik and his colleagues designed a nanoparticle to take advantage by embedding it with an anti-inflammatory drug. The nanoparticles bind to the receptors, and the neutrophils internalize the nanoparticle. Once inside, the anti-inflammatory drug works to “unzip” the neutrophil and allow it to re-enter the bloodstream.”The nanoparticle is very much like a Trojan horse,” Malik said. “It binds to a receptor found only on these activated, sticky neutrophils, and the cell automatically engulfs whatever binds there. …

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The parasite that escaped out of Africa: Tracing origins of malaria parasite

An international team of scientists has traced the origin of Plasmodium vivax, the second-worst malaria parasite of humans, to Africa, according to a study published this week in Nature Communications. Until recently, the closest genetic relatives of human P. vivax were found only in Asian macaques, leading researchers to believe that P. vivax originated in Asia.The study, led by researchers from the Perelman School of Medicine at the University of Pennsylvania, found that wild-living apes in central Africa are widely infected with parasites that, genetically, are nearly identical to human P. vivax.This finding overturns the dogma that P. vivax originated in Asia, despite being most prevalent in humans there now, and also solves other vexing questions about P. vivax infection: how a mutation conferring resistance to P. vivax occurs at high frequency in the very region where this parasite seems absent and how travelers returning from regions where almost all humans lack the receptor for P. vivax can be infected with this parasite.Of Ape and Human ParasitesMembers of the labs of Beatrice Hahn, MD, and George Shaw, MD, PhD, both professors of Medicine and Microbiology at Penn, in collaboration with Paul Sharp, PhD, an evolutionary biologist from the University of Edinburgh, and Martine Peeters, PhD, a microbiologist from the Institut de Recherche pour le Dveloppement and the University of Montpellier, tested over 5,000 ape fecal samples from dozens of field stations and sanctuaries in Africa for P. vivax DNA. …

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The ups and downs of early atmospheric oxygen

UC Riverside research team challenges conventional view of a simple two-step rise in early oxygen on Earth; study suggests instead dynamic oxygen concentrations that rose and fell over billions of years.A team of biogeochemists at the University of California, Riverside, give us a nontraditional way of thinking about the earliest accumulation of oxygen in the atmosphere, arguably the most important biological event in Earth history.A general consensus asserts that appreciable oxygen first accumulated in Earth’s atmosphere around 2.3 billion years ago during the so-called Great Oxidation Event (GOE). However, a new picture is emerging: Oxygen production by photosynthetic cyanobacteria may have initiated as early as 3 billion years ago, with oxygen concentrations in the atmosphere potentially rising and falling episodically over many hundreds of millions of years, reflecting the balance between its varying photosynthetic production and its consumption through reaction with reduced compounds such as hydrogen gas.”There is a growing body of data that points to oxygen production and accumulation in the ocean and atmosphere long before the GOE,” said Timothy W. Lyons, a professor of biogeochemistry in the Department of Earth Sciences and the lead author of the comprehensive synthesis of more than a decade’s worth of study within and outside his research group.Lyons and his coauthors, Christopher T. Reinhard and Noah J. Planavsky, both former UCR graduate students, note that once oxygen finally established a strong foothold in the atmosphere starting about 2.3 billion years ago it likely rose to high concentrations, potentially even levels like those seen today. Then, for reasons not well understood, the bottom fell out, oxygen plummeted to a tiny fraction of today’s level, and the ocean remained mostly oxygen free for more than a billion years.The paper appears in Nature on Feb. 19.”This period of extended low oxygen spanning from roughly 2 to less than 1 billion years ago was a time of remarkable chemical stability in the ocean and atmosphere,” Lyons said.His research team envisions a series of interacting processes, or feedbacks, that maintained oxygen at very low levels principally by modulating the availability of life-sustaining nutrients in the ocean and thus oxygen-producing photosynthetic activity.”We suggest that oxygen was much lower than previously thought during this important middle chapter in Earth history, which likely explains the low abundances and diversity of eukaryotic organisms and the absence of animals,” Lyons said.The late Proterozoic — the time period beginning less than a billion years ago following this remarkable chapter of sustained low levels of oxygen — was strikingly different, marked by extreme climatic events manifest in global-scale glaciation, indications of at least intervals of modern-like oxygen abundances, and the emergence and diversification of the earliest animals. Lyons notes that the factors controlling the rise of animals are under close scrutiny, including challenges to the long-held view that a major rise in atmospheric oxygen concentrations triggered the event.”Despite the new ideas about animal origins, we suspect that oxygen played a major if not dominant role in the timing of that rise and, in particular, in the subsequent emergence of complex ecologies for animal life on and within the sediment, predator-prey relationships, and large bodies” said Lyons. “But, again, feedbacks always rule the day. Environmental change drives evolution, and steps in the progression of life change the environment.”No single factor is likely to be the whole story, and there is much more to be written in the tale. …

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Brain signals move paralyzed limbs in new experiment

To help people suffering paralysis from injury, stroke or disease, scientists have invented brain-machine interfaces that record electrical signals of neurons in the brain and translate them to movement. Usually, that means the neural signals direct a device, like a robotic arm.Cornell University researcher Maryam Shanechi, assistant professor of electrical and computer engineering, working with Ziv Williams, assistant professor of neurosurgery at Harvard Medical School, is bringing brain-machine interfaces to the next level: Instead of signals directing a device, she hopes to help paralyzed people move their own limb, just by thinking about it.When paralyzed patients imagine or plan a movement, neurons in the brain’s motor cortical areas still activate even though the communication link between the brain and muscles is broken. By implanting sensors in these brain areas, neural activity can be recorded and translated to the patient’s desired movement using a mathematical transform called the decoder. These interfaces allow patients to generate movements directly with their thoughts.In a paper published online Feb. 18 in Nature Communications, Shanechi, Williams and colleagues describe a cortical-spinal prosthesis that directs “targeted movement” in paralyzed limbs. The research team developed and tested a prosthesis that connects two subjects by enabling one subject to send its recorded neural activity to control limb movements in a different subject that is temporarily sedated. The demonstration is a step forward in making brain-machine interfaces for paralyzed humans to control their own limbs using their brain activity alone.The brain-machine interface is based on a set of real-time decoding algorithms that process neural signals by predicting their targeted movements. In the experiment, one animal acted as the controller of the movement or the “master,” then “decided” which target location to move to, and generated the neural activity that was decoded into this intended movement. The decoded movement was used to directly control the limb of the other animal by electrically stimulating its spinal cord.”The problem here is not only that of decoding the recorded neural activity into the intended movement, but also that of properly stimulating the spinal cord to move the paralyzed limb according to the decoded movement,” Shanechi said.The scientists focused on decoding the target endpoint of the movement as opposed to its detailed kinematics. This allowed them to match the decoded target with a set of spinal stimulation parameters that generated limb movement toward that target. …

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Roots to shoots: Hormone transport in plants deciphered

Plant growth is orchestrated by a spectrum of signals from hormones within a plant. A major group of plant hormones called cytokinins originate in the roots of plants, and their journey to growth areas on the stem and in leaves stimulates plant development. Though these phytohormones have been identified in the past, the molecular mechanism responsible for their transportation within plants was previously poorly understood.Now, a new study from a research team led by biochemist Chang-Jun Liu at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory identifies the protein essential for relocating cytokinins from roots to shoots.The research is reported in the February 11 issue of Nature Communications.Cytokinins stimulate shoot growth and promote branching, expansion and plant height. Regulating these hormones also improves the longevity of flowering plants, tolerance to drought or other environmental stresses, and the efficiency of nitrogen-based fertilizers.Manipulating cytokinin distribution by tailoring the action of the transporter protein could be one way to increase biomass yield and stress tolerance of plants grown for biofuels or agriculture. “This study may open new avenues for modifying various important crops, agriculturally, biotechnologically, and horticulturally, to increase yields and reduce fertilizer requirements, for instance, while improving the exploitation of sustainable bioenergy resources,” Liu said.Using Arabidopsis, a small flowering plant related to mustard and cabbage that serves as a common experimental model, the researchers studied a large family of transport proteins called ATP-binding cassette (ABC) transporters, which act as a kind of inter- or intra-cellular pump moving substances in or out of a plant’s cells or their organelles. While performing gene expression analysis on a set of these ABC transporters, the research team found that one gene — AtABCG14 – is highly expressed in the vascular tissues of roots.To determine its function, they examined mutant plants harboring a disrupted AtABCG14 gene. They found that knocking out this transporter gene resulted in plants with weaker growth, slenderer stems, and shorter primary roots than their wild-type counterparts. These structural changes in the plants are symptoms of cytokinin deficiencies. Essentially, the long-distance transportation of the growth hormones is impaired, which causes alterations in the development of roots and shoots. …

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Managed honeybees linked to new diseases in wild bees, UK study shows

Diseases that are common in managed honeybee colonies are now widespread in the UK’s wild bumblebees, according to research published in Nature. The study suggests that some diseases are being driven into wild bumblebee populations from managed honeybees.Dr Matthias Frst and Professor Mark Brown from Royal Holloway University of London (who worked in collaboration with Dr Dino McMahon and Professor Robert Paxton at Queen’s University Belfast, and Professor Juliet Osborne working at Rothamsted Research and the University of Exeter) say the research provides vital information for beekeepers across the world to ensure honeybee management supports wild bee populations.Dr Frst, from the School of Biological Sciences at Royal Holloway, said: “Wild and managed bees are in decline at national and global scales. Given their central role in pollinating wildflowers and crops, it is essential that we understand what lies behind these declines. Our results suggest that emerging diseases, spread from managed bees, may be an important cause of wild bee decline.”This research assessed common honeybee diseases to determine if they could pass from honeybees to bumblebees. It showed that deformed wing virus (DWV) and the fungal parasite Nosema ceranae — both of which have major negative impacts on honeybee health — can infect worker bumblebees and, in the case of DWV, reduce their lifespan.Honeybees and bumblebees were then collected from 26 sites across the UK and screened for the presence of the parasites. Both parasites were widespread in bumblebees and honeybees across the UK.Dr Frst explained: “One of the novel aspects of our study is that we show that deformed wing virus, which is one of the main causes of honeybee deaths worldwide, is not only broadly present in bumblebees, but is actually replicating inside them. This means that it is acting as a real disease; they are not just carriers.”The researchers also looked at how the diseases spread and studied genetic similarities between DWV in different pollinator populations. Three factors suggest that honeybees are spreading the parasites into wild bumblebees: honeybees have higher background levels of the virus and the fungus than bumblebees; bumblebee infection is predicted by patterns of honeybee infection; and honeybees and bumblebees at the same sites share genetic strains of DWV.”We have known for a long time that parasites are behind declines in honeybees,” said Professor Brown. “What our data show is that these same pathogens are circulating widely across our wild and managed pollinators. Infected honeybees can leave traces of disease, like a fungal spore or virus particle, on the flowers that they visit and these may then infect wild bees.”While recent studies have provided anecdotal reports of the presence of honeybee parasites in other pollinators, this is the first study to determine the epidemiology of these parasites across the landscape. …

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Artificial leaf jumps developmental hurdle

In a recent early online edition of Nature Chemistry, ASU scientists, along with colleagues at Argonne National Laboratory, report advances toward perfecting a functional artificial leaf.Designing an artificial leaf that uses solar energy to convert water cheaply and efficiently into hydrogen and oxygen is one of the goals of BISfuel — the Energy Frontier Research Center, funded by the Department of Energy, in the Department of Chemistry and Biochemistry at Arizona State University.Hydrogen is an important fuel in itself and serves as an indispensible reagent for the production of light hydrocarbon fuels from heavy petroleum feed stocks. Society requires a renewable source of fuel that is widely distributed, abundant, inexpensive and environmentally clean.Society needs cheap hydrogen.”Initially, our artificial leaf did not work very well, and our diagnostic studies on why indicated that a step where a fast chemical reaction had to interact with a slow chemical reaction was not efficient,” said ASU chemistry professor Thomas Moore. “The fast one is the step where light energy is converted to chemical energy, and the slow one is the step where the chemical energy is used to convert water into its elements viz. hydrogen and oxygen.”The researchers took a closer look at how nature had overcome a related problem in the part of the photosynthetic process where water is oxidized to yield oxygen.”We looked in detail and found that nature had used an intermediate step,” said Moore. “This intermediate step involved a relay for electrons in which one half of the relay interacted with the fast step in an optimal way to satisfy it, and the other half of the relay then had time to do the slow step of water oxidation in an efficient way.”They then designed an artificial relay based on the natural one and were rewarded with a major improvement.Seeking to understand what they had achieved, the team then looked in detail at the atomic level to figure out how this might work. They used X-ray crystallography and optical and magnetic resonance spectroscopy techniques to determine the local electromagnetic environment of the electrons and protons participating in the relay, and with the help of theory (proton coupled electron transfer mechanism), identified a unique structural feature of the relay. This was an unusually short bond between a hydrogen atom and a nitrogen atom that facilitates the correct working of the relay.They also found subtle magnetic features of the electronic structure of the artificial relay that mirrored those found in the natural system.Not only has the artificial system been improved, but the team understands better how the natural system works. This will be important as scientists develop the artificial leaf approach to sustainably harnessing the solar energy needed to provide the food, fuel and fiber that human needs are increasingly demanding.ASU chemistry professors involved in this specific project include Thomas Moore, Devens Gust, Ana Moore and Vladimiro Mujica. The department is a unit of the College of Liberal Arts and Sciences. Key collaborators in this work are Oleg Poluektov and Tijana Rajh from Argonne National Laboratory.This work would not have been possible without the participation of many scientists driven by a common goal and coordinated by a program such as the Energy Frontier Research Center to bring the right combination of high-level skills to the research table.The Department of Chemisry and Biocehmistry is an academic unit in ASU’s College of Liberal Arts and Sciences.Story Source:The above story is based on materials provided by Arizona State University College of Liberal Arts and Sciences. …

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Researchers rejuvenate stem cell population from elderly mice, enabling muscle recovery

Researchers at the Stanford University School of Medicine have pinpointed why normal aging is accompanied by a diminished ability to regain strength and mobility after muscle injury: Over time, stem cells within muscle tissues dedicated to repairing damage become less able to generate new muscle fibers and struggle to self-renew.”In the past, it’s been thought that muscle stem cells themselves don’t change with age, and that any loss of function is primarily due to external factors in the cells’ environment,” said Helen Blau, PhD, the Donald and Delia B. Baxter Foundation Professor. “However, when we isolated stem cells from older mice, we found that they exhibit profound changes with age. In fact, two-thirds of the cells are dysfunctional when compared to those from younger mice, and the defect persists even when transplanted into young muscles.”Blau and her colleagues also identified for the first time a process by which the older muscle stem cell populations can be rejuvenated to function like younger cells. “Our findings identify a defect inherent to old muscle stem cells,” she said. “Most exciting is that we also discovered a way to overcome the defect. As a result, we have a new therapeutic target that could one day be used to help elderly human patients repair muscle damage.”Blau, a professor of microbiology and immunology and director of Stanford’s Baxter Laboratory for Stem Cell Biology, is the senior author of a paper describing the research, which will be published online Feb. 16 in Nature Medicine. Postdoctoral scholar Benjamin Cosgrove, PhD, and former postdoctoral scholar Penney Gilbert, PhD, now an assistant professor at the University of Toronto, are the lead authors.The researchers found that many muscle stem cells isolated from mice that were 2 years old, equivalent to about 80 years of human life, exhibited elevated levels of activity in a biological cascade called the p38 MAP kinase pathway. This pathway impedes the proliferation of the stem cells and encourages them to instead become non-stem, muscle progenitor cells. …

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