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No blue light, please, I’m tired: Light color determines sleepiness versus arousal in mice

Light affects sleep. A study in mice published in Open Access journal PLOS Biology shows that the actual color of light matters; blue light keeps mice awake longer while green light puts them to sleep easily. An accompanying Primer provides accessible context information and discusses open questions and potential implications for “designing the lighting of the future.”

Light shining into our eyes not only mediates vision but also has critical non-image-forming functions such as the regulation of circadian rhythm, which affects sleep and other physiological processes. As humans, light generally keeps us awake, and dark makes us sleepy. For mice, which are mostly nocturnal, light is a sleep-inducer. Previous studies in mice and humans have shown that non-image-forming light perception occurs in specific photosensitive cells in the eye and involves a light sensor called melanopsin. Mice without melanopsin show a delay in their response to fall asleep when exposed to light, pointing to a critical role for melanopsin in sleep regulation.

Stuart Peirson and Russell Foster, both from Oxford University, UK, alongside colleagues from Oxford and elsewhere, investigated this further by studying sleep induction in mice exposed to colored light, i.e., light of different wave lengths. Based on the physical properties of melanopsin, which is most sensitive to blue light, the researchers predicted that blue light would be the most potent sleep inducer.

To their surprise, that was not the case. Green light, it turns out, puts mice to sleep quickly, whereas blue light actually seems to stimulate the mice, though they did fall asleep eventually. Mice lacking melanopsin were oblivious to light color, demonstrating that the protein is directing the differential response.

Both green and blue light elevated levels of the stress hormone corticosterone in the blood of exposed mice compared with mice kept in the dark, the researchers found. Corticosterone levels in response to blue light, however, were higher than levels in mice exposed to green light. When the researchers gave the mice drugs that block the effects of corticosterone, they were able to mitigate the effects of blue light; drugged mice exposed to blue light went to sleep faster than control mice that had received placebos.

Citing previous results that exposure to blue light — a predominant component of light emitted by computer and smart-phone screens — promotes arousal and wakefulness in humans as well, the researchers suggest that “despite the differences between nocturnal and diurnal species, light may play a similar alerting role in mice as has been shown in humans.” Overall, they say their work “shows the extent to which light affects our physiology and has important implications for the design and use of artificial light sources.”

In the accompanying Primer, Patrice Bourgin, from the University of Strasbourg, France, and Jeffrey Hubbard from the University of Lausanne, Switzerland, say the study “reveals that the role of color [in controlling sleep and alertness] is far more important and complex than previously thought, and is a key parameter to take into account.” The study’s results, they say, “call for a greater understanding of melanopsin-based phototransduction and tell us that color wavelength is another aspect of environmental illumination that we should consider, in addition to photon density, duration of exposure and time of day, as we move forward in designing the lighting of the future, aiming to improve human health and well-being.”

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/08/160815185816.htm Original web page at Science Daily

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* Pre-Hispanic Mexican civilization may have bred and managed rabbits and hares

Humans living in the pre-Hispanic Mexican city of Teotihuacan may have bred rabbits and hares for food, fur and bone tools, according to a study published August 17, 2016 in the open-access journal PLOS ONE by Andrew Somerville from the University of California San Diego, US, and colleagues.

Human-animal relationships often involve herbivore husbandry and have been key in the development of complex human societies across the globe. However, fewer large mammals suitable for husbandry were available in Mesoamerica. The authors of the present study looked for evidence of small animal husbandry in the pre-Hispanic city of Teotihuacan, which existed northeast of what is now Mexico City from A.D. 1-600. The authors performed stable carbon and oxygen isotope analysis of 134 rabbit and hare bone specimens from the ancient city and 13 modern wild specimens from central Mexico to compare their potential diets and ecology.

Compared to modern wild specimens, the authors found that Teotihuacan rabbit and hare specimens had carbon isotope values indicating higher levels of human-farmed crops, such as maize, in their diet. The specimens with the greatest difference in isotope values came from a Teotihuacan complex that contained traces of animal butchering and a rabbit sculpture.

While the ancient rabbits and hares included in this study could have consumed at least some farmed crops through raiding of fields or wild plants, the authors suggest their findings indicate that Teotihuacan residents may have provisioned, managed, or bred rabbits and hares for food, fur, and bone tools, which could be new evidence of small mammal husbandry in Mesoamerica.

“Because no large mammals such as goats, cows, or horses were available for domestication in pre-Hispanic Mexico, many assume that Native Americans did not have as intensive human-animal relationships as did societies of the Old World,” said Andrew Somerville. “Our results suggest that citizens of the ancient city of Teotihuacan engaged in relationships with smaller and more diverse fauna, such as rabbits and jackrabbits, and that these may have been just as important as relationships with larger animals.”

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/08/160817142539.htm  Original web page at Science Daily

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* How norovirus gets inside cells: New clues

Norovirus is the most common viral cause of diarrhea worldwide, but scientists still know little about how it infects people and causes disease because the virus grows poorly in the lab. The discovery, in mice, provides new ways to study a virus notoriously hard to work with and may lead to treatments or a vaccine.

Researchers at Washington University School of Medicine in St. Louis have identified the protein that norovirus — shown here in a colored transmission electron micrograph — uses to invade cells. Norovirus is the most common viral cause of diarrhea worldwide, but scientists still know little about how it infects people and causes disease because the virus grows poorly in the lab. The discovery, in mice, provides new ways to study a virus notoriously hard to work with and may lead to treatments or a vaccine.

Now, researchers at Washington University School of Medicine in St. Louis have identified the protein that norovirus uses to invade cells. The discovery, in mice, provides new ways to study a virus notoriously hard to work with and may lead to treatments or a vaccine.

“Our inability to grow the virus in the lab has limited our ability to develop anti-viral agents. If you can’t get the virus to multiply in human cells, how are you going to find compounds that inhibit multiplication?” said Herbert “Skip” Virgin, MD, PhD, the Mallinckrodt Professor and Chair of the Department of Pathology and Immunology and the study’s senior author. “This discovery provides a good basis for our mouse model, which we can then use to understand noroviral pathogenesis and search for treatments in people.” The research is published August 18 in Science.

Norovirus is infamous for causing outbreaks of diarrhea, vomiting and stomach cramps on cruise ships, in military barracks and in other environments where people live in close quarters. For most people, infection leads to an uncomfortable day or two punctuated with frequent trips to the bathroom, but in vulnerable populations such as cancer patients and older people, the disease can be long-lasting and sometimes deadly.

There are many noroviruses, but each is restricted to infecting just one animal species. Human norovirus will not infect any of the species typically used in biomedical research, such as mice, rats or rabbits. Human norovirus won’t grow even in human cells in petri dishes.

“Since human norovirus won’t grow in human cell lines or laboratory animals, you can’t test a drug, you can’t test a vaccine,” Virgin said. “You’d have to do those kinds of studies in people, but it would be better if we can first conduct tests in animal models.”

When mouse norovirus was discovered in 2003, it seemed like a great opportunity to make a mouse model of norovirus infection. The genomes of mouse and human norovirus are very similar, and the viruses even look alike under the electron microscope. Nobody could ever be sure, however, that how mouse norovirus acts in mice is relevant to how human norovirus acts in humans.

Virgin and postdoctoral researchers Craig Wilen, MD, PhD, and Robert Orchard, PhD, thought that if they could identify the reason that mouse norovirus infects only mice and human norovirus infects only humans, they could improve their model of norovirus infection.

The researchers used a genetic tool known as CRISPR-Cas9 to identify mouse genes that are important for mouse noroviral infection. They found that when a gene called CD300lf was knocked down by CRISPR-Cas9, norovirus could not infect the cells. CD300lf codes for a protein on the surface of mouse cells, and the researchers believe the virus latches on to it to get inside the cell.

Furthermore, when the researchers expressed mouse CD300lf protein on the surface of human cells, mouse norovirus was able to infect the human cells and multiply. “Mouse norovirus grew just fine in human cells,” Virgin said. “This tells us that the species restriction is due to the ability to get inside the cells in the first place. Once inside the cells, most likely all the other mechanisms are conserved between human and mouse noroviruses, since the viruses are so similar.”

The researchers also found that mouse norovirus requires a second molecule, or cofactor, to infect cells; CD300lf by itself isn’t enough. But they were unable to nail down the molecule’s identity.

“At this point we know more about what it isn’t than what it is,” said Orchard, a co-lead author on the study. “Every week there’s a new favorite hypothesis. It’s probably a small molecule found in the blood, not a protein.”

It is unusual for a virus to require a cofactor for infection. Their discovery suggests that the lack of a necessary cofactor may be why scientists have had a difficult time growing human norovirus in the lab.

The researchers are working on ways to use human cells with the mouse CD300lf protein to study noroviral infection. One possibility is to use the system to screen drugs to block viral multiplication. Such drugs could be administered prophylactically to people around the epicenter of an outbreak, or as a treatment for immunocompromised individuals.

The discovery of the mouse receptor for norovirus also could lead to a better understanding of how the virus causes disease.

“We still don’t even know if the virus infects epithelial cells or immune cells, and that matters if you want to develop a vaccine,” said Wilen, a co-lead author on the study. “We have developed a knockout mouse that lacks CD300lf, and we are using it to identify the cell types involved. We’re hoping that a better understanding of the pathogenesis will lead to better ways to treat or prevent this very common disease.”

https://www.sciencedaily.com/ Science Daily

https://www.sciencedaily.com/releases/2016/08/160818150000.htm Original web page at Science Daily

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Novel compounds arrested epilepsy development in mice

A team led by Nicolas Bazan, MD, PhD, Boyd Professor and Director of LSU Health New Orleans’ Neuroscience Center of Excellence, has developed neuroprotective compounds that may prevent the development of epilepsy. The findings will be published online in Scientific Reports, a Nature journal, on July 22, 2016.

In this study in an experimental model of epilepsy in mice, the compounds prevented seizures and their damaging effects on dendritic spines, specialized structures that allow brain cells to communicate. In epilepsy, these structures are damaged and rewire incorrectly, creating brain circuits that are hyper-connected and prone to seizures, an important example of pathological plasticity.

“In the current study, preservation of dendritic spines and subsequent protection from seizures, were observed up to 100 days post-treatment, suggesting the process of epilepsy development has been arrested,” notes Dr. Nicolas Bazan, Director of the LSU Health New Orleans Neuroscience Center of Excellence.

Dr. Bazan and Professor Julio Alvarez-Builla Gomez, a medicinal chemist from the University of Alcala in Spain, discovered and patented the LAU compounds, named for the inventors in Louisiana and the Spanish university. A number of LAU compounds were studied in this research, which blocked a neuroinflammatory signaling receptor, protecting dendritic spines and lessening seizure susceptibility and onset, as well as hyper-excitability.

According to the National Institutes of Health, the epilepsies are a spectrum of brain disorders ranging from severe, life-threatening and disabling, to ones that are much more benign. In epilepsy, the normal pattern of neuronal activity becomes disturbed, causing strange sensations, emotions, and behavior or sometimes convulsions, muscle spasms, and loss of consciousness. It is not uncommon for people with epilepsy, especially children, to develop behavioral and emotional problems in conjunction with seizures. Issues may also arise as a result of the stigma attached to having epilepsy, which can lead to embarrassment and frustration or bullying, teasing, or avoidance in school and other social settings. For many people with epilepsy, the risk of seizures restricts their independence (some states refuse drivers licenses to people with epilepsy) and recreational activities. Epilepsy can be a life-threatening condition. Some people with epilepsy are at special risk for abnormally prolonged seizures or sudden unexplained death in epilepsy. There is currently no cure.

The research was supported by the National Institute of General Medical Sciences of the National Institutes of Health. “Future clinical studies would evaluate the potential application of the compounds that we have developed and/or the mechanisms that we have discovered that are targeted by these compounds in the development of epilepsy,” concludes Dr. Bazan. “Most of the anti-epileptic drugs currently available treat the symptom – seizures- not the disease itself. Understanding the potential therapeutic usefulness of compounds that may interrupt the development process may pave the way for disease-modifying treatments for patients at risk for epilepsy.”

The research is part of an ongoing effort in Dr. Bazan laboratory to understand the critical role of brain plasticity which underlies many aspects of health and disease, from developmental disorders like dyslexia to aging, retinal degeneration, neurotrauma (concussions, TBI), stroke, Parkinson’s and Alzheimer’s disease.

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/07/160722092930.htm Original web page at Science Daily

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* First public collection of bacteria from the intestine of mice

Mouse models are extensively used in pharmaceutical and medical research, and it is known that the communities of microbes in their intestine can have a significant impact on the research output. However, there is still insufficient information available about many bacteria inhabiting the intestine of mice. For the first time, a collection of cultured bacterial strains provides comprehensive information on the mouse gut microbiota: Scientists at the Technical University of Munich were able to isolate, characterize, and archive a hundred strains, including 15 hitherto unknown taxa.

They are microscopically small and live both on humans and animals. They can help with recovery from an illness or literally make you sick: Billions of micro-organisms, most of which are found in the intestines, as well as on the skin and other regions of the body, living in symbiosis with the host. These tiny beings are of central importance, and experts refer to them as intestinal microbiota or the microbiome. Decoding its characteristics and obtaining a better understanding of it is what scientists at the Central Institute for Nutrition and Food Research (ZIEL) at the Technical University of Munich (TUM) are working on.

76 cultured bacterial species from the mouse microbiome identified and archived

One key to obtaining information about the interactions between gut bacteria and their host are mouse models. However only a handful of mouse intestinal bacteria have been made publicly available and fully characterized so far. This is a highly limiting factor for research, because it complicates the annotation of data obtained by molecular techniques, and because it has been shown that gut microbiomes are to some extent specific to their host, and researchers have been using strains of other origin in mouse models. Dr. habil. Thomas Clavel from ZIEL and colleagues describe a new resource in “Nature Microbiology” which, for the first time, contains a hundred cultured bacterial strains from the mouse gut microbiome. For this study, 1500 cultures were examined, and 76 different species were identified and archived.

“The goal of our work was to take a big initial step towards decoding the cultured fraction of gut bacterial communities in mice. There is still a lot left to do. We will be making our work available to scientists around the world and hope that others will also help to find the pieces to complete the puzzle,” said Clavel, who has been researching various bacteria in gut microbiomes at the TU Munich for ten years. Although the mouse gut microbiome presents a number of similarities with the human microbiome, the work showed that around 20 percent of the strains in the collection prefer colonizing the intestines of mice.

In order to better understand colonization processes in the intestine, bacteria first need to be identified and characterized in detail. “Because mouse models are indispensable for preclinical studies, the resource now made available shall contribute to a better understanding of microbe-host interactions and to a higher degree of standardization,” said Clavel.

For the first time, the researchers were able to characterize new bacteria with important functional properties: For example Flintibacter butyricum produces the short-chain fatty acid butyrate from both sugars and proteins — a rare property in the realm of intestinal bacteria. Butyrate is a main product of fermentation in the intestine, and has been shown to have anti-inflammatory and positive effects against metabolic diseases in numerous studies.

“We still have a lot of gaps in our knowledge about gut microbiomes, but with the publicly available database of cultured mouse gut bacteria and their genetic material, we are now a little closer to our goal,” Thomas Clavel from the TUM stated enthusiastically.

https://www.sciencedaily.com/ Science Daily

https://www.sciencedaily.com/releases/2016/08/160812103715.htm Original web page at Science Daily

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* Brain’s chemical signals seen in real time

Neuroscientists have invented a way to watch the ebb and flow of the brain’s chemical messengers in real time. They were able to see the surge of neurotransmitters as mice were conditioned — similarly to Pavlov’s famous dogs — to salivate in response to a sound.

The study, presented at the American Chemical Society’s meeting in Philadelphia, Pennyslvania, on 22 August, uses a technique that could help to disentangle the complex language of neurotransmitters. Ultimately, it could lead to a better understanding of brain circuitry.

The brain’s electrical surges are easy to track. But detecting the chemicals that drive this activity — the neurotransmitters that travel between brain cells and lead them to fire — is much harder. “There’s a hidden signalling network in the brain, and we need tools to uncover it,” says Michael Strano, a chemical engineer at the Massachusetts Institute of Technology in Cambridge.

In many parts of the brain, neurotransmitters can exist at undetectably low levels. Typically, researchers monitor them by sucking fluid out from between neurons and analysing the contents in the lab. But that technique cannot measure activity in real time. Another option is to insert a metal probe into the space between neurons to measure how neurotransmitters react chemically when they touch metal. But the probe is unable to distinguish between structurally similar molecules, such as dopamine, which is involved in pleasure and reward, and noradrenaline which is involved in alertness.

Enter neuroscientist Paul Slesinger of the Icahn School of Medicine at Mount Sinai in New York City and neurophysicist David Kleinfeld of the University of California, San Diego. In May, they reported a method for making genetically modified human cells that produce artificial receptors for neurotransmitters. These receptors are also linked to fluorescent molecules so that when a particular neurotransmitter binds to its receptor, the cell lights up.

The researchers injected these cells, known as CNiFERs (cell-based neurotransmitter fluorescent engineered reporters) into the brains of 13 mice. Then, they cut a window into each mouse’s skull to expose its brain and put a transparent cover over the hole so that they could watch the cells light up in real time through a microscope.

Over the course of five days, the researchers trained the mice by playing a sound before giving them a sugar treat. The mice soon learned to salivate in anticipation as soon as they heard the sound. Each day, the researchers recorded light from the animals’ brains, enabling them to determine the exact moment at which neurotransmitters were released. For the first time, they could see a surge of dopamine — the pleasure molecule that drives salivation — after the sound that occurred more rapidly as the association became stronger.

Noradrenaline, a molecule involved in alertness, is also thought to surge in this type of learning, but researchers have never been able to distinguish it from dopamine in real time. But by engineering CNiFERs specific to each neurotransmitter, Slesinger and Kleinfeld showed, also for the first time, that the noradrenaline spike occured at variable times following the tone and did not change with training. This suggests that the neurotransmitter could be responding to some other factor or behavioural reaction.

The ability to use separate CNiFERs for the two neurotransmitters might eventually reveal whether noradrenalin has a role in learning and addiction, and whether drugs that target it are likely to change behaviour.

Strano says that the technique is an improvement on current methods because it quantifies neurotransmitters directly instead of calculating them through their effects. “It’s one of the purest tests you can do,” he says.

But he worries that genetically modified cells might not act the same way as natural cells. His lab is working on a set of nanotubes that cross the blood–brain barrier and emit light when they encounter a neurotransmitter in the brain.

But Lin Tian, a neuroscientist at the University of California, Davis, thinks that the technique is of limited use. The CNiFERs show whether the total amount of a molecule such as dopamine is increasing or decreasing, but they do not reveal which neuron is sending or receiving the signal — making it hard to map tangled brain circuits.

Instead, Tian and her colleagues are modifying bacterial proteins so that they bind neurotransmitters and emit light. This technique is precise enough to detect the signalling molecule glutamate in a single gap between two neurons, thus revealing the exact cells involved.

Tian says that CNiFERs might be more useful for amino-acid-based neuropeptides, such as orexin, which is involved in sleep and drug-seeking behaviours. These larger molecules are more difficult to detect with chemical techniques. Slesinger says that he and his collaborators are working on CNiFERs for this and other neuropeptides.

All of the researchers are trying to expand the repertoire of neurotransmitters that can be detected. Kleinfeld says that CNiFERS are unlikely to be used in humans any time soon because implanting cells into the brain could be dangerous. But they might be used to detect whether drugs are working in mice, and they are sensitive enough to reveal, perhaps, more subtle ways in which the brain malfunctions.

Nature doi:10.1038/nature.2016.20458

http://www.nature.com/news/index.html  Nature

http://www.nature.com/news/brain-s-chemical-signals-seen-in-real-time-1.20458 Original web at Nature

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Antibiotics weaken Alzheimer’s disease progression through changes in the gut microbiome

Long-term treatment with broad spectrum antibiotics decreased levels of amyloid plaques, a hallmark of Alzheimer’s disease, and activated inflammatory microglial cells in the brains of mice in a new study by neuroscientists from the University of Chicago.

The study, published July 21, 2016, in Scientific Reports, also showed significant changes in the gut microbiome after antibiotic treatment, suggesting the composition and diversity of bacteria in the gut play an important role in regulating immune system activity that impacts progression of Alzheimer’s disease.

“We’re exploring very new territory in how the gut influences brain health,” said Sangram Sisodia, PhD, Thomas Reynolds Sr. Family Professor of Neurosciences at the University of Chicago and senior author of the study. “This is an area that people who work with neurodegenerative diseases are going to be increasingly interested in, because it could have an influence down the road on treatments.”

Two of the key features of Alzheimer’s disease are the development of amyloidosis, accumulation of amyloid-ß (Aß) peptides in the brain, and inflammation of the microglia, brain cells that perform immune system functions in the central nervous system. Buildup of Aß into plaques plays a central role in the onset of Alzheimer’s, while the severity of neuro-inflammation is believed to influence the rate of cognitive decline from the disease.

For this study, Sisodia and his team administered high doses of broad-spectrum antibiotics to mice over five to six months. At the end of this period, genetic analysis of gut bacteria from the antibiotic-treated mice showed that while the total mass of microbes present was roughly the same as in controls, the diversity of the community changed dramatically. The antibiotic-treated mice also showed more than a two-fold decrease in Aß plaques compared to controls, and a significant elevation in the inflammatory state of microglia in the brain. Levels of important signaling chemicals circulating in the blood were also elevated in the treated mice.

While the mechanisms linking these changes is unclear, the study points to the potential in further research on the gut microbiome’s influence on the brain and nervous system.

“We don’t propose that a long-term course of antibiotics is going to be a treatment — that’s just absurd for a whole number of reasons,” said Myles Minter, PhD, a postdoctoral scholar in the Department of Neurobiology at UChicago and lead author of the study. “But what this study does is allow us to explore further, now that we’re clearly changing the gut microbial population and have new bugs that are more prevalent in mice with altered amyloid deposition after antibiotics.”

The study is the result of one the first collaborations from the Microbiome Center, a joint effort by the University of Chicago, the Marine Biological Laboratory and Argonne National Laboratory to support scientists at all three institutions who are developing new applications and tools to understand and harness the capabilities of microbial systems across different fields. Sisodia, Minter and their team worked with Eugene B. Chang, Martin Boyer Professor of Medicine at UChicago, and Vanessa Leone, PhD, a postdoctoral scholar in Chang’s lab, to analyze the gut microbes of the mice in this study.

Minter said the collaboration was enabling, and highlighted the cross-disciplinary thinking necessary to tackle a seemingly intractable disease like Alzheimer’s. “Once you put ideas together from different fields that have largely long been believed to be segregated from one another, the possibilities are really amazing,” he said.

Sisodia cautioned that while the current study opens new possibilities for understanding the role of the gut microbiome in Alzheimer’s disease, it’s just a beginning step.

“There’s probably not going to be a cure for Alzheimer’s disease for several generations, because we know there are changes occurring in the brain and central nervous system 15 to 20 years before clinical onset,” he said. “We have to find ways to intervene when a patient starts showing clinical signs, and if we learn how changes in gut bacteria affect onset or progression, or how the molecules they produce interact with the nervous system, we could use that to create a new kind of personalized medicine.”

https://www.sciencedaily.com/ Science Daily

https://www.sciencedaily.com/releases/2016/07/160721072559.htm  Original web page at Science Daily

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* Common colon cancer tumor type blocked in mice

A new scientific study has identified why colorectal cancer cells depend on a specific nutrient, and a way to starve them of it. Over one million men and women are living with colorectal cancer in the United States. The National Cancer Institute estimates 4.5% of all men and women will be diagnosed with the cancer during their lifetime, making it the third most common non-skin cancer.

In the study published online in Nature Communications, researchers showed how certain colorectal cancer cells reprogram their metabolism using glutamine, a non-essential amino acid. Many cancer cells rely on glutamine to survive. How they become so dependent on the molecule is hotly debated in the field.

Researchers studied a subset of colorectal cancer cells containing a genetic mutation called PIK3CA. This mutation is located in a gene critical for cell division and movement, and is found in approximately one third of all colorectal cancers. The mutation is also the most commonly identified genetic mutation across all cancers, making the results of the study universally appealing.

Researchers were interested in determining whether or not the common PIK3CA mutation contributes to changes in cancer cell metabolism, such as how nutrients like glutamine are processed. Normally, glutamine is broken down by cancer cells into several other molecules with the help of specific enzymes. This complicated system helps produce adenosine triphosphate, the energy currency of all cells, and other molecules critical for colorectal cancer cell growth.

The researchers found that colorectal cells with the PIK3CA mutation broke down significantly more glutamine than cells without the mutation. The researchers identified several enzymes involved in the process that are more active in the mutant cancer cells than in other cell types, explaining the increased need for glutamine. These enzymes become overactive in the mutant cancer cells due to a cascade of signals led by the protein encoded by mutant PIK3CA gene. This finding represents a novel and important link between the common PIK3CA mutation and altered glutamine metabolism in cancer cells.

Zhenghe John Wang, PhD, professor of genetics and genome sciences and co-leader of the Cancer Genetics Program at Case Western Reserve University School of Medicine helped lead the study. “In layman’s terms, we discovered that colon cancers with PIK3CA oncogenic mutations are addicted to glutamine, a particular nutrient for cancer cells. We also demonstrated that these cancers can be starved to death by depriving glutamine with drugs.”

When the researchers lowered the amount of glutamine available to mutant cancer cells growing in laboratory dishes, the cancer cells died. This discovery led the team to investigate the effects of blocking glutamine availability in mice with colorectal cancer tumors containing the common PIK3CA mutation. Wang and colleagues found that exposing these mice to a compound that blocks glutamine metabolism consistently suppressed tumor growth. They did not observe the same effect on tumors without the mutation. Together, these results provide a promising new therapeutic avenue to suppress growth of colorectal tumors with the PIK3CA mutation. The researchers have filed a patent application based on the unique mechanism of tumor suppression they have identified and the work is available for licensing.

“This study provides the basis for a colon cancer treatment clinical trial that will be started in the summer at the University Hospitals Seidman Cancer Center,” according to Neal Meropol, MD, Dr. Lester E. Coleman, Jr. Professor of Cancer Research and Therapeutics, chief of the division of hematology and oncology, and principal investigator for the trial. The phase I/II study will test the effects of a glutamine metabolism inhibitor in patients with advanced colorectal tumors.

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/07/160720215322.htm  Original web page at Science Daily

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Seeing structure that allows brain cells to communicate

For more than a century, neuroscientists have known that nerve cells talk to one another across the small gaps between them, a process known as synaptic transmission (synapses are the connections between neurons). Information is carried from one cell to the other by neurotransmitters such as glutamate, dopamine, and serotonin, which activate receptors on the receiving neuron to convey excitatory or inhibitory messages.

But beyond this basic outline, the details of how this crucial aspect of brain function occurs have remained elusive. Now, new research by scientists at the University of Maryland School of Medicine (UM SOM) has for the first time elucidated details about the architecture of this process. The paper was published today in the journal Nature.

Synapses are very complicated molecular machines. They are also tiny: only a few millionths of an inch across. They have to be incredibly small, since we need a lot of them; the brain has around 100 trillion of them, and each is individually and precisely tuned to convey stronger or weaker signals between cells.

To visualize features on this sub-microscopic scale, the researchers turned to an innovative technology known as single-molecule imaging, which can locate and track the movement of individual protein molecules within the confines of a single synapse, even in living cells. Using this approach, the scientists identified an unexpected and precise pattern in the process of neurotransmission. The researchers looked at cultured rat synapses, which in terms of overall structure are very similar to human synapses.

“We are seeing things that have never been seen before. This is a totally new area of investigation,” said Thomas Blanpied, PhD, Associate Professor in the Department of Physiology, and leader of the group that performed the work. “For many years, we’ve had a list of the many types of molecules that are found at synapses, but that didn’t get us very far in understanding how these molecules fit together, or how the process really works structurally. Now by using single-molecule imaging to map where many of the key proteins are, we have finally been able to reveal the core architectural structure of the synapse.”

In the paper, Blanpied describes an unexpected aspect to this architecture that may explain why synapses are so efficient, but also susceptible to disruption during disease: at each synapse, key proteins are organized very precisely across the gap between cells. “The neurons do a better job than we ever imagined of positioning the release of neurotransmitter molecules near their receptors,” Blanpied says. “The proteins in the two different neurons are aligned with incredible precision, almost forming a column stretching between the two cells.” This proximity optimizes the power of the transmission, and also suggests new ways that this transmission can be modified.

Understanding this architecture will help clarify how communication within the brain works, or, in the case of psychiatric or neurological disease, how it fails to work. Blanpied is also focusing on the activity of “adhesion molecules,” which stretch from one cell to the other and may be important pieces of the “nano-column.” He suspects that if adhesion molecules are not placed correctly at the synapse, synapse architecture will be disrupted, and neurotransmitters

won’t be able to do their jobs. Blanpied hypothesizes that in at least some disorders, the issue may be that even though the brain has the right amount of neurotransmitter, the synapses don’t transmit these molecules efficiently.

Blanpied says that this improved comprehension of synaptic architecture could lead to a better understanding of brain diseases such as depression, schizophrenia and Alzheimer’s disease, and perhaps suggest new ideas for treatments.

Blanpied and his colleagues will next explore whether the synaptic architecture changes in certain disorders: they will begin by looking at a synapses in a mouse model of the pathology in schizophrenia.

https://www.sciencedaily.com/  Science Dail

https://www.sciencedaily.com/releases/2016/07/160727140303.htm  Original web page at Science Daily

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Why brain neurons in Parkinson’s disease stop benefiting from levodopa

Though the drug levodopa can dramatically improve Parkinson’s disease symptoms, within five years one-half of the patients using L-DOPA develop an irreversible condition — involuntary repetitive, rapid and jerky movements. This abnormal motor behavior appears only while taking L-DOPA, and it stops if the drug is stopped. However, if L-DOPA is taken again, even many months later, it quickly re-emerges.

In research to prevent this side effect and extend the usefulness of L-DOPA — which is the most effective drug treatment for Parkinson’s disease — University of Alabama at Birmingham researchers have uncovered an essential mechanism of this long-term memory for L-DOPA-induced-dyskinesia, or LID.

They report a widespread reorganization of DNA methylation — a process in which the function of DNA is modified — in brain cells caused by L-DOPA. They also found that treatments that increase or decrease DNA methylation can alter dyskinesia symptoms in an animal model.

Thus, modification of DNA methylation may be a novel therapeutic target to prevent or reverse LID behavior.

“L-DOPA is a very valuable treatment for Parkinson’s, but in many patients its use is limited by dyskinesia,” said David Standaert, M.D., Ph.D., the John N. Whitaker Professor and chair of the Department of Neurology at UAB. “Better means of preventing or reversing LID could greatly extend the use of L-DOPA without inducing intolerable side effects. The treatments we have used here, methionine supplementation or RG-108, are not practical for human use; but they point to the opportunity to develop methylation-based epigenetic therapeutics in Parkinson’s disease.”

The research by David Figge, Karen Eskow Jaunarajs, Ph.D., and corresponding author David Standaert, Center for Neurodegeneration and Experimental Therapeutics, UAB Department of Neurology, was recently published in The Journal of Neuroscience.

Although studies of LID in animal models have shown changes in gene expression and cell signaling, a key unanswered question still remained: Why is the neural sensitization seen in LID persistent when delivery of L-DOPA is transient?

The UAB researchers suspected DNA methylation changes — the attachment of a methyl group onto nucleotides in DNA — because methylation is known to stably alter gene expression in cells as they grow and differentiate. Furthermore, methylation changes in neurons have been shown to be involved during the formation of place memory and the development of addictive behavior after cocaine use.

In general, increased DNA methylation has a silencing effect on nearby gene expression, while removal of the methyl groups enhances gene expression.

Figge and colleagues found that:

L-DOPA treatment of parkinsonian rodents enhanced the expression of two DNA demethylases.

Cells in the dorsal striatum in the LID model showed extensive, location-specific changes in DNA methylation, mostly seen as demethylation.The changes in DNA methylation were near many genes with established functional importance in LID.

Modulating global DNA methylation — either by injecting methionine to increase methylation or applying RG-108, an inhibitor of methylation, to the striatum — modified the dyskinetic behavior of LID, down or up, respectively.

“Together,” the researchers wrote, “these findings demonstrate that L-DOPA induces widespread changes to striatal DNA methylation and that these modifications are required for the development and maintenance of LID.”

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/07/160728143608.htm  Original web page at Science Daily

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Why is cocaine so addictive? Study using animal model provides clues

Scientists at Wake Forest Baptist Medical Center are one step closer to understanding what causes cocaine to be so addictive. The research findings are published in the current issue of the Journal of Neuroscience.

Cocaine addiction is a debilitating neurological disorder that affects more than 700,000 people in the United States alone, according to the Substance Abuse and Mental Health Services Administration. With repeated use, tolerance may develop, meaning more of the drug is required to achieve the same euphoric effect. Cocaine addiction can be characterized by repeated attempts at abstinence that often end in relapse.

“Scientists have known for years that cocaine affects the dopamine system and dopamine transporters, so we designed our study to gain a better understanding of how tolerance to cocaine develops via the dopamine transporters,” said Sara R. Jones, Ph.D., professor of physiology and pharmacology at Wake Forest Baptist and lead author of the study.

“Currently there isn’t any effective treatment available for cocaine addiction so understanding the underlying mechanism is essential for targeting potential new treatments.”

Using an animal model, the research team replicated cocaine addiction by allowing rats to self-administer as much cocaine as they wanted (up to 40 doses) during a six-hour period. Six-hour-a-day access is long enough to cause escalation of intake and tip animals over from having controlled intake to more uncontrolled, binge-like behavior, Jones said.

Following the five-day experiment, the animals were not allowed cocaine for 14 or 60 days. After the periods of abstinence, the researchers looked at the animals’ dopamine transporters and they appeared normal, just like those in the control animals that had only received saline.

However, a single self-administered infusion of cocaine at the end of abstinence, even after 60 days, fully reinstated tolerance to cocaine’s effects in the animals that had binged. In the control animals that had never received cocaine, a single dose did not have the same effect.

These data demonstrate that cocaine leaves a long-lasting imprint on the dopamine system that is activated by re-exposure to cocaine, Jones said. This ‘priming effect,’ which may be permanent, may contribute to the severity of relapse episodes in cocaine addicts.

“Even after 60 days of abstinence, which is roughly equivalent to four years in humans, it only took a single dose of cocaine to put the rats back to square one with regard to its’ dopamine system and tolerance levels, and increased the likelihood of binging again,” Jones said. “It’s that terrible cycle of addiction.”

Jones added that hope is on the horizon through preclinical trials that are testing several amphetamine-like drugs for effectiveness in treating cocaine addiction.

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/08/160801163906.htm Original web page at Science Daily

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Overeating in obese mice linked to altered brain responses to food cues

Obese mice are much more likely than lean mice to overeat in the presence of environmental cues, a behavior that could be related to changes in the brain, finds a new study by a Michigan State University neuroscientist. The study is to be presented this week at the Society for the Study of Ingestive Behavior, the foremost society for research into all aspects of eating and drinking behavior.

The findings offer clues in Alexander Johnson’s quest to unpack the interconnected mechanisms of overeating and obesity. Obesity is an epidemic domestically — more than a third of Americans are considered to be obese — and a growing health problem in other parts of the world.

“In today’s society we are bombarded with signals to eat, from fast-food commercials to the smell of barbecue and burgers, and this likely drives overeating behaviors,” said Johnson, Assistant Professor of Psychology at Michigan State University. “Our study suggests both a psychological and neurobiological account for why obese individuals may be particularly vulnerable to these signals.”

The study involved two groups of mice — one group that was fed a high-calorie diet until they became obese and a second group that was fed a regular lab chow diet so they stayed lean. Johnson then trained the mice with different auditory cues. Whenever they heard one cue, such as a tone, the mice received sugar reward; with a second cue, such as a white noise, they received no reward.

The mice were then given access to their assigned maintenance diet for three days so they were satiated (i.e., not hungry) for the final test phase of the study. In that test, the sugar solution was available to the mice at all times, to see what would trigger them to start eating. When no cue was given, and when the white-noise cue was given (which previously offered no reward), the lean mice and obese mice ate roughly the same amount. When the rewarding tone cue was given, however, the obese mice ate significantly more of the sugar solution compared to the lean mice.

“From a psychological perspective, this tells us that the obese mice are more vulnerable to the effects of environmental triggers on evoking overeating behavior,” Johnson said. “Looking at it through a human lens, this suggests that obese individuals may be more sensitive to overeating food in the presence of say, the McDonald’s Golden Arches.”

Johnson also examined the mice’s lateral hypothalamus, which is known as a key brain area in appetite and feeding behavior. Using a procedure called immunofluorescence to label neurons in this area of the brain, he found that neurons releasing a certain hormone- Melanin-Concentrating Hormone, or MCH — were more abundant in obese mice. But importantly, these MCH-releasing neurons were more active when the obese mice encountered the environmental reminders of sugar.

“In other words, if you become obese this leads to increases in MCH expression, which may make you more sensitive to this form of overeating,” Johnson said.

The novel findings, he added, start to paint a picture of the relationship between brain-behavior mechanisms that may underlie learned overeating in obese individuals.

“This could be one of perhaps many reasons why obese people may have the urge to eat more when presented with food cues.”

https://www.sciencedaily.com/ Science Daily

https://www.sciencedaily.com/releases/2016/07/160712092351.htm  Original web page at Science Daily

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* Bright light accelerates ageing in mice

Eliane Lucassen works the night shift at Leiden University Medical Center in the Netherlands, beginning her day at 6 p.m. Yet her own research has shown that this schedule might cause her health problems. “It’s funny,” the medical resident says. “Here I am, spreading around that it’s actually unhealthy. But it needs to be done.”

Lucassen and Johanna Meijer, a neuroscientist at Leiden, report today in Current Biology that a constant barrage of bright light prematurely ages mice, playing havoc with their circadian clocks and causing a cascade of health problems.

Mice exposed to constant light experienced bone-density loss, skeletal-muscle weakness and inflammation; restoring their health was as simple as turning the lights off. The findings are preliminary, but they suggest that people living in cities flooded with artificial light may face similar health risks.

“We came to know that smoking was bad, or that sugar is bad, but light was never an issue,” says Meijer. “Light and darkness matter.”

Many previous studies have hinted at a connection between artificial light exposure and health problems in animals and people. Epidemiological analyses have found that shift workers have an increased risk of breast cancer, metabolic syndrome4 and osteoporosis. People exposed to bright light at night are more likely to have cardiovascular disease and often don’t get enough sleep.

Yet drawing a direct link between light exposure and poor health has been difficult. Meijer’s group explored this relationship in mice by implanting electrodes in the part of the animals’ brains that controls their body clocks, to measure the activity of neurons there. The scientists then housed the mice in brightly lit cages for 24 weeks.

The animals had bedding to make nests, could move freely and were able to close their eyes when they slept. But sleeping mice couldn’t avoid the light entirely, and still got about one-seventh of the light exposure that they did while awake. Overall, the animals were exposed to more light than they would get in a typical light–dark cycle.

In response, the mice’s neuronal activity patterns shifted, leaving cells in the brain’s pacemaker region pulsing irregularly. This loss of synchronization mirrors what happens in ageing brains.

The mice also adopted a 25.5-hour day, lost bone density and had weaker muscles, as measured by how strongly they could grip with their forelimbs. After the researchers restored darkness, the mice’s neurons returned to their normal rhythms and the animals reverted to a 24-hour day.

The analysis takes an innovative approach to studying circadian biology in mice, says Richard Stevens, an epidemiologist at the University of Connecticut School of Medicine in Farmington who studies the effect of light on cancer. But he says that the findings may not apply to people. The bright lights foisted on the mice were more dramatic than the light–dark cycles that people would experience in real life, even in extreme situations.

“The next experiment ought to be something like 12 hours of light, 6 hours of dim light and 6 hours of dark. That would be the kind of exposure that humans would have,” Stevens says.

And disruption of the biological clock alone might not cause the health effects reported in the study, says Steven Lockley, a neuroscientist at Harvard Medical School in Boston, Massachusetts. Poor sleep and light itself can each affect health, so an altered circadian clock may not be to blame.

But Meijer says the study should be a warning to people who work in intensive-care facilities or long-term care facilities, and to shift workers — such as her former student, Lucassen.

An atlas of artificial light pollution released in June showed that two-thirds of the world’s population is exposed to light at night. Also last month, the American Medical Association’s Council on Science and Public Health called for a reduction in bright artificial light, citing evidence that it may increase a person’s risk of developing cancer, diabetes and cardiovascular disease.

Meijer now plans to examine how light affects the immune system, and she wants to repeat her neuron-monitoring study with grass rats, which are active during the day (unlike standard lab mice). She remains fascinated by the circadian system.

“There is no other region of the brain we know so much about,” Meijer says. “It has been a beautiful model for neuroscience research. But only in the last five to seven years have we realized it is also essential for health.”

Nature doi:10.1038/nature.2016.20263

http://www.nature.com/news/index.html  Nature

http://www.nature.com/news/bright-light-accelerates-ageing-in-mice-1.20263  Original web page at Nature

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Ridiculously cute mouse lemurs hold key to Madagascar’s past

“For a long time, scientists weren’t sure how or why Madagascar’s biogeography changed in very recent geological time, specifically at the key period around when humans arrived on the island a few thousand years ago. It has been proposed they heavily impacted the Central Highland forests,” says Steve Goodman, MacArthur Field Biologist at The Field Museum in Chicago, who co-authored the study and has been studying Malagasy animals for thirty years. “This study shows the landscape was changing thousands of years before humans arrived.”

So scientists wanted to learn about the history of Madagascar’s landscape — why study mouse lemurs? The tiny primates are the perfect combination of fast-breeding, hardy, and unique to the island. “They reach reproductive maturity within a year, and that means that a lot of generations are produced very quickly,” explains Goodman. “That enables us to see evolution at work faster than we would in an animal that took, say, five years to first reproduce.” The lemurs, which are found only on Madagascar, live across much of the island, even forested areas that have been damaged by humans. That means that for scientists studying how the island changed over time, mouse lemurs are a jackpot. “The mouse lemurs are forest dependent — as the forest changes, they change. By studying how mouse lemurs evolved in different areas of the island, we’re able to glimpse how the island itself changed and learn whether those changes were caused by humans,” says Goodman.

By analyzing DNA from five different mouse lemur species, the scientists were able to tell when the different kinds of lemurs branched out from each other. “We were able to characterize tens of thousands of changes in the genomes of mouse lemurs that are now isolated and form separate species. By analyzing these DNA changes, we were able to understand when the species diverged from each other, and by inference, identify the ecological forces that might have driven them apart,” says Anne Yoder, Director of the Duke University Lemur Center and lead author on the paper.

“When we analyzed the mouse lemurs’ DNA, we were able to see genetic similarities between lemur species that are closely related but today live far apart from each other. That suggests that their ancestors were able to disperse across forested habitat that no longer exists — portions of the Central Highlands that formed the bridge between the eastern and western parts of the island today,” explains Goodman. Instead, the scientists believe, Madagascar was covered by a patchwork of forests, enabling the mouse lemurs to slowly disperse over tens of thousands of years between different areas. Then, once those bridges did not exist anymore, the populations became isolated.

The DNA analysis allowed the scientists to infer the timeline for the habitat changes of the Central Highlands — it happened thousands of years before humans arrived on the island. “At least at first, the changes to this region of the island were almost certainly the result of natural climate change over the past approximately 50,000 years,” says Goodman.

The study also indicates that the former forested areas of the Central Highlands may have been an important zone of ecological transition between the extremes of eastern humid forests and western dry forests. This has important implications for understanding how the mid-section of the island served as a zone of dispersal for animals, such as mouse lemurs and many others. “We’ve learned that it’s probably incorrect to talk about Madagascar’s humid east and dry west like they’re two completely separate habitats,” says Goodman. “The eastern and western parts of the island are just different extremes on the continuum.”

“Madagascar is one of the top conservation priorities in the world,” says Goodman. “All of the native land mammals on Madagascar occur nowhere else in the world. This study is important because it sheds light upon the long-term life history of Madagascar, before human colonization. It helps us understand change.”

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/07/160718160927.htm Original web page at Science Daily

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Protein found to bolster growth of damaged muscle tissue

Johns Hopkins University biologists have found that a protein that plays a key role in the lives of stem cells can bolster the growth of damaged muscle tissue, a step that could potentially contribute to treatments for muscle degeneration caused by old age and diseases such as muscular dystrophy.

The results, published online by the journal Nature Medicine, show that a particular type of protein called integrin is present on the stem cell surface and used by stem cells to interact with, or “sense” their surroundings. How stem cells sense their surroundings, also known as the stem cell “niche,” affects how they live and last for regeneration. The presence of the protein β1-integrin was shown to help promote the transformation of those undifferentiated stem cells into muscle after the tissue has degraded, and improve regenerated muscle fiber growth as much as 50 percent.

While the presence of β1-integrin in adult stem cells is apparent, “its role in these cells has not been examined,” especially its influence on the biochemical signals promoting stem cell growth, wrote the three authors, Chen-Ming Fan, an adjunct biology professor; Michelle Rozo, who completed her doctorate in biology at Johns Hopkins this year; and doctoral student Liangji Li.

The experiment shows that β1-integrin — one of 28 types of integrin — maintains a link between the stem cell and its environment, and interacts biochemically with a growth factor called fibroblast growth factor [FGF] to promote stem cell growth and restoration after muscle tissue injury. Aged stem cells do not respond to FGF, and the results also show that β1-integrin restores aged stem cell’s ability to respond to FGF to grow and improve muscle regeneration.

By tracking an array of proteins inside the stem cells, the researchers tested the effects of removing β1-integrin from the stem cell. This is based on the understanding that the activities of stem cells — undifferentiated cells that can become specialized — are dependent on their environment and supported by the proteins found there.

“If we take out β1-integrin, all these other (proteins) are gone,” said Fan, the study’s senior author and a staff member at the Carnegie Institution for Science in Washington and Baltimore.

Why that is the case is not clear, but the experiment showed that without β1-integrin, stem cells could not sustain growth after muscle tissue injury.

By examining β1-integrin molecules and the array of proteins that they used to track stem cell activity in aged muscles, the authors found that all of these proteins looked like they had been removed from aged stem cells. They injected an antibody to boost β1-integrin function into aged muscles to test whether this treatment would enhance muscle regeneration. Measurements of muscle fiber growth with and without boosting the function of β1-integrin showed that the protein led to as much as 50-percent more regeneration in cases of injury in aged mice.

When the same β1-integrin function-boosting strategy was applied to mice with muscular dystrophy, the muscle was able to increase strength by about 35 percent.

Fan said the team’s research will next try to determine what is happening inside the stem cells as they react with their immediate environment, as a step to understanding more about the interaction of the two. That, in turn, could help refine the application of integrin as a therapy for muscular dystrophy and other diseases, and for age-related muscle degeneration.

“We provide here a proof-of-principle study that may be broadly applicable to muscle diseases that involve SC (stem cell) niche dysfunction,” the authors wrote. “But further refinement is needed for this method to become a viable treatment.”

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/07/160719131341.htm Original web page at Science Daily

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Copper-induced misfolding of prion proteins

Iowa State University researchers have described with single-molecule precision how copper ions cause prion proteins to misfold and seed the misfolding and clumping of nearby prion proteins.

The researchers also found the copper-induced misfolding and clumping is associated with inflammation and damage to nerve cells in brain tissue from a mouse model.

Prions are abnormal, pathogenic agents that are transmissible and induce abnormal folding of a specific type of protein called prion proteins, according to the Centers for Disease Control and Prevention. Prion proteins are mostly found in the brain. The abnormal folding of prion proteins leads to brain damage and symptoms of neurodegenerative disease. A similar cycle of neuronal protein misfolding and clumping is observed in other neurodegenerative disorders, including Parkinson’s and Alzheimer’s diseases.

“Our study establishes a direct link, at the molecular level, between copper exposure and prion protein neurotoxicity,” the researchers wrote in a summary of the paper.

The findings were published today in the journal Science Advances. The corresponding author is Sanjeevi Sivasankar, an Iowa State University associate professor of physics and astronomy; the first author is Chi-Fu Yen, an Iowa State doctoral student in electrical and computer engineering. Co-authors are Anumantha Kanthasamy, an Iowa State Clarence Hartley Covault Distinguished Professor in Veterinary Medicine, chair of biomedical sciences and director of the Iowa Center for Advanced Neurotoxicology; and Dilshan Harischandra, an Iowa State doctoral student in biomedical sciences.

Grants from the National Institute of Environmental Health Sciences at the National Institutes of Health supported the project, including one from the Virtual Consortium for Transdisciplinary Environmental Research.

Although this study determined that copper-induced misfolding and clumping of prion proteins is associated with the degeneration of nerve tissues, Sivasankar cautioned that the study does not directly address the infectivity of prion diseases.

“There are different strains of misfolded prion proteins and not all of them are pathogenic,” Sivasankar said. “Although we do not show that the strains generated in our experiments are infectious, we do prove that copper ions trigger misfolding of prion proteins which causes toxicity in nerve cells.”

The Sivasankar and Kanthasamy research groups plan to perform additional studies to determine if the copper-induced misfolding causes disease.

Integrating approaches Sivasankar also noted that a unique aspect of this project was the integration of biophysical and neurotoxicological research approaches. He said the combination has the potential to transform studies of the molecular basis for neurodegenerative diseases.

A fluorescence-based technique that identified misfolded prion proteins with single-molecule sensitivity and determined the role of metal ions in misfolding. The researchers used this technique to show that misfolding begins when copper ions bind to the unstructured tail of the prion protein. A single-molecule atomic force microscopy assay that measured the efficiency of prion protein clumping. The researchers used this technique to show that misfolded prion proteins stick together nearly 900 times more efficiently than properly folded proteins.

The Kanthasamy and Sivasankar research groups worked together on a real-time, quaking-induced conversion assay to demonstrate that misfolded prion proteins serve as seeds that trigger the misfolding and clumping of nearby prion proteins. Kanthasamy’s research group also used its expertise in neurotoxicology to show the copper-induced, misfolded prion proteins damage nerve cells in slices of brain tissue from mice.

Taken together, the results identify the biophysical conditions and mechanisms for copper-induced prion protein misfolding, clumping and neurotoxicity, the researchers wrote.

“This was a very comprehensive study,” Sivasankar said. “We took it from single molecules all the way to tissues.”

And, although the study doesn’t address the infectious nature of prion diseases, Kanthasamy said it is still important: “This study has major implications to our understanding the role of metals in protein misfolding diseases including prion, Alzheimer’s and Parkinson’s diseases.”

https://www.sciencedaily.com/ Science Daily

https://www.sciencedaily.com/releases/2016/07/160701183556.htm Original web page at Science Daily

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Gene-therapy trials must proceed with caution

Jesse Gelsinger was 18 and healthy when he died in 1999 during a gene-therapy experiment. He had a condition called ornithine transcarbamylase deficiency (OTC), but it was under control through a combination of diet and medication. Like others with the disorder, Gelsinger lacked a functional enzyme involved in breaking down ammonia, a waste product of protein metabolism that becomes toxic when its levels become too high. The gene therapy that he received used a viral vector to introduce a normal gene for the enzyme.

Gene therapy remains an obvious route to treat OTC. Simply adding the missing gene has been shown to repair metabolism in mice. But the memory of what happened to Gelsinger has slowed progress in gene therapy for any condition.

That memory was firmly on the agenda at a meeting of the US National Institutes of Health’s Recombinant DNA Advisory Committee (RAC) last week. The RAC evaluates proposals to use modified DNA in human trials, and presenting to it were Cary Harding, a medical geneticist at Oregon Health and Science University in Portland, and Sam Wadsworth, chief scientific officer at Dimension Therapeutics in Cambridge, Massachusetts. The duo were proposing the first new trial of gene therapy for OTC.

Harding and the researchers at Dimension argue that the technology and our understanding of physiology have advanced enough since 1999 to try it again in people. Gelsinger died after his body overreacted to the vector used to introduce the OTC gene. Dimension’s therapy uses a different viral vector, called AAV8, which has been tested numerous times in people with other conditions, with few adverse effects.

Such assurances were not enough for the RAC, and particularly not for its bioethicists and historians. Dawn Wooley, a virologist at Wright State University in Dayton, Ohio, pointed out that an RAC panel raised concerns about Gelsinger’s trial in 1995, but decided to let the test go ahead. “We can’t let it happen again, we cannot,” she says.

Perhaps the greatest indication of how Gelsinger’s death haunts the RAC came when one member suggested that the researchers explain in the consent form to be sent to prospective participants that someone had died in a similar study and attracted media attention.

There are some scientific reasons to be careful. AAV8 can cause mild liver toxicity in healthy people, and the steroids used to treat that could lead to complications in people with OTC. With so little known about these effects, the RAC members suggested that the researchers lower the dose to one that is more likely to be safe, even if it is potentially not effective.

After some discussion, the RAC voted unanimously to approve the trial. However, that came with a long list of conditions, including that the treatment first be tested in a second animal species. The researchers disagree with most of the conditions, believing that more expensive animal trials will add nothing. They feel that they are being held to a different standard from most trials.

Dimension still plans to submit an application to the US Food and Drug Administration (FDA) later this year to start a clinical trial. It is unclear how heavily the RAC’s recommendations weigh into FDA decisions, but Wadsworth says that the company will conduct its trials overseas if necessary. “These patients have been waiting a long time,” he says.

He is right. Therapies can be tested in non-human animals only for so long — at some point, volunteers such as Gelsinger must step forward. Yet the echoes of a trial done 17 years ago cannot be easily silenced. In fact, Gelsinger’s name came up several times at the RAC meeting. Researchers from the University of Pennsylvania in Philadelphia had even mentioned him earlier that morning, when proposing the first human trial of CRISPR gene-editing technology as a treatment for cancer. The RAC approved that proposal, but its implication was clear: take care. Avoidable failures could stymie CRISPR research for decades. History must not repeat itself.

Nature 534, 590 (30 June 2016) doi:10.1038/534590a

http://www.nature.com/news/index.html  Nature

http://www.nature.com/news/gene-therapy-trials-must-proceed-with-caution-1.20186 Original web page at Nature

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Natural metabolite can suppress inflammation

An international research team has revealed a substance produced in humans that can suppress the pro-inflammatory activity of macrophages — specific immune cells. The substance known as itaconate is released in large quantities by macrophages themselves and according to the scientists, acts as an antioxidant and anti-inflammatory agent. These properties make itaconate promising for the treatment of such pathologies as cardiac ischemia, metabolic disorders and autoimmune diseases which may be associated with excessive inflammation or oxidative stress. An international group of scientists from US, Canada, Germany and Russia has revealed a substance produced in humans that can suppress the pro-inflammatory activity of macrophages — specific cells of immune system. The substance known as itaconate is released in large quantities by macrophages themselves, but until now its role remained poorly studied. Now scientists have found evidence that itaconate acts as an antioxidant and anti-inflammatory agent. These properties make itaconate promising for the treatment of pathologies caused by excessive inflammation or oxidative stress. Such conditions may be associated with cardiac ischemia, metabolic disorders and perhaps autoimmune diseases. The findings were published in Cell Metabolism.

The work, which united scientists from Washington University in St. Louis, ITMO University, McGill University and Max Planck Institute of Immunobiology and Epigenetics, was based on the study of macrophages — immune system cells in charge of fighting pathogens. An important feature of macrophages is their ability to switch between different states depending on the concentration of various substances in the body. In total, there are three such states: M0 — neutral, M1 — pro-inflammatory and M2 anti-inflammatory.

M1 macrophages are the first who arrive to fight the infection. As they begin to swallow viruses and bacteria, an intense inflammatory process kicks in. This process may adversely affect the entire organism if the macrophages become overly diligent. Inflammation consumes energy resources of the organism and can lead to numerous complications or even death. That is why in order to mitigate the negative consequences of immune response, it is important to understand how we can reduce the excessive proinflammatory effect of macrophages.

An in-depth study of macrophage metabolism during their transition from inactive to proinflammatory state helped researchers identify the substance that could suppress macrophage-related inflammations. Describing the working mechanism of this substance called itaconate became possible due to a complex map of metabolic pathways in macrophages that was developed by the group.

Itaconate is produced by macrophages when they switch from M0 inactive state to M1 pro-inflammatory state. If the concentration of this substance increases to defined limit, macrophage activation falls. “Itaconate sets the bar controlling M1 macrophage formation,” says Alexey Sergushichev, one of the authors of the paper and PhD student at ITMO University. “Without this substance, the inflammation would increase more than required. In the future, with the help of itaconate, it will be possible to artificially manipulate the transition of macrophages from M0 to M1, meaning the possibility of restraining inflammations. The influence of itaconate on macrophages is a delicate mechanism that can ensure high selectivity of the immune system regulation.”

Prior to the study, guesswork with respect to the function and origin of itaconate generated a lot of speculations. But the new study shows that itaconate plays the role of immune regulator. To understand how itaconate reduces the activity of immune cells, the researchers examined the so-called Krebs cycle, or tricarboxylic acid cycle and cellular respiration (processes of producing of vital substances and energy from the oxidation of glucose in cells). Having done so, the scientists identified two “bottlenecks” that can be influenced to reverse the reaction and send it another way.

The Krebs cycle is preceded by signal transmission between cells through oxygen-sensitive pathways. Itaconate blocks the enzyme called Sdh (succinate dehydrogenase), which not only ensures the functioning of the tricarboxylic acid cycle but also links the cycle to cellular respiration and signaling pathways.

Thus, itaconate acts on both functions of the Sdh enzyme, adjusting the cells’ Krebs cycle and respiration. When the enzyme is blocked in macrophages, both processes become interrupted, and this impairs the cells’ activation. “Noteworthy, itaconate acts as an anti-oxidant and anti-inflammatory agent,” says Vicky Lampropoulou, the lead author of the paper and researcher at the laboratory of Maxim Artyomov at Washington University in St. Louis. “At the same time, itaconate is naturally produced by mammalian immune cells. These features make it attractive for use in adjuvant therapy for numerous diseases, in which excessive inflammation and oxidative stress associate with pathology, like heart ischemia, metabolic disorders and perhaps even autoimmunity.”

The researchers have already demonstrated that they can use itaconate to reach the desired effect in living organisms. Experiments with mice have shown that the substance reduces damage after heart attack, acting by the same mechanism of locking the Sdh enzyme. However, according to the scientists, more work is needed to successfully apply the method to humans.

https://www.sciencedaily.com/ Science Daily

https://www.sciencedaily.com/releases/2016/06/160630155359.htm  Original web page at Science Daily

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The relentless dynamism of the adult brain

Scientists from the Institut Pasteur and the CNRS were able to make real-time observations over a period of several months that reveal how new adult-born neurons are formed and evolve in the olfactory bulb of mice. They made the surprising discovery that there is constant structural plasticity in the connections established by these new neurons with the circuits into which they are recruited. The scientists showed that this neuronal dynamism can enable optimal processing of sensory information by the olfactory bulb. These findings are to be published in the journal Neuron on June 30, 2016.

Although most neurons are generated during embryogenesis, some regions of the brain, such as the olfactory bulb in rodents and the hippocampus in humans, are capable of constantly regenerating their neurons in adulthood. Scientists first conclusively discovered these new adult neurons around 15 years ago, but their function remained a mystery, mainly because they are inaccessible in living animals.

In an article published in the journal Neuron, scientists from a unit at the Institut Pasteur directed by CNRS scientist Pierre-Marie Lledo provide further evidence of the highly dynamic nature of the changes observed at the neuronal level in adult brains. The scientists spent several months observing the development of neurons formed in adulthood in the olfactory bulbs of mice. This gave them the unique opportunity to see the formation, stabilization and elimination of connections between neurons in real time.

They revealed that in the olfactory bulb, where new neurons are continuously formed, the connections between these new neurons and neighboring cells are significantly rearranged throughout their lifetime. All these neurons are constantly reorganizing the billions of “synaptic” contacts they establish among themselves. The scientists were surprised by this observation. “We expected to see the synapses gradually stabilizing, as happens during brain development. But astonishingly, these synapses proved to be highly dynamic throughout the life of the new neurons. Also, these dynamics were reflected in the principal neurons, their primary synaptic partner,” explained first author, Kurt Sailor, from the Institut Pasteur.

To observe the ongoing formation of neuronal circuits, the scientists marked the new neurons with a green fluorescent protein (GFP), to allow imaging of the dynamic changes with microscopy. These experiments were carried out over a period of several months to follow the entire life cycle of the new neurons. In the first three weeks of their life, these new neurons extended their cellular projections, known as dendrites, to form several ramifications, which subsequently became very stable. They next observed the neuronal spines, the structure where synapses form, and demonstrated that 20% of the synapses between new and pre-existing neurons were changed on a daily basis — a phenomenon that was also observed in their synaptic partners, the principal olfactory bulb neurons. Using computer-based models, the authors showed that these dynamics enabled the synaptic network to adjust efficiently and reliably to ongoing sensory changes in the environment.

“Our findings suggest that the plasticity of this constantly regenerating region of the brain occurs with continuous physical formation and elimination of synaptic connections. This structural plasticity reveals a unique dynamic mechanism that is vital for the regeneration and integration of new neurons within the adult brain circuit,” concluded the scientists. More generally, this study suggests a universal plasticity mechanism in brain regions that are closely associated with memory and learning.

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https://www.sciencedaily.com/releases/2016/07/160701120520.htm Original web page at Science Daily

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New anti-cancer strategy mobilizes both innate and adaptive immune response

Scientists have developed a new vaccine that involves injecting cells that have been modified so that they can stimulate both an innate immune response and the more specific adaptive response, which allows the body to keep memories and attack new tumor cells as they form.

Though a variety of immunotherapy-based strategies are being used against cancer, they are often hindered by the inability of the immune response to enter the immunosuppressive tumor microenvironment and to effectively mount a response to cancer cells. Now, scientists from the RIKEN Center for Integrative Medical Sciences have developed a new vaccine that involves injecting cells that have been modified so that they can stimulate both an innate immune response and the more specific adaptive response, which allows the body to keep memories and attack new tumor cells as they form. In the study published in Cancer Research, they found that the vaccine made it possible for killer CD8+T-cells–important players in the immune response against cancer–to enter the tumor microenvironment and target cancerous cells.

According to Shin-ichiro Fujii, leader of the Laboratory for Immunotherapy, who led the study, “Cancer cells have different sensitivities to the innate or adaptive response, so it important to target both in order to eradicate it. We have developed a special type of modified cell, called aAVC, which we found can do this.”

The aAVC cells are not taken from the subject’s own body but are foreign cells. The cells are modified by adding a natural killer t-cell ligand, which permits them to stimulate natural killer T-cells, along with an antigen associated with a cancer. The group found that when these cells are activated, they in turn promote the maturation of dendritic cells, which act as coordinators of the innate and acquired response. Dendritic cells are key because they allow the activation of immune memory, where the body remembers and responds to a threat even years later.

To find whether it worked in actual bodies, they conducted experiments in mice with a virulent form of melanoma that also expresses a model antigen called OVA. Tests in mice showed, moreover, that aggressive tumors could be shrunken by vaccinating the animals with aAVC cells that were programmed to display OVA antigen. Following the treatment, the tumors in the treated animals were smaller and necrotic in the interior–a sign that the tumor was being attacked by the killer CD8+T-cells.

Fujii continues, “We were interesting in finding a mechanism, and were able to understand that the aAVC treatment led to the development of blood vessels in the tumors that expressed a pair of important adhesion molecules, ICAM-1 and VCAM-1, that are not normally expressed in tumors. This allowed the killer CD8+T cells to penetrate into the tumor.”

They also found that in animals that had undergone the treatment, cancer cells injected even a year later were eliminated. “This indicates,” says Fujii, “that we have successfully created an immune memory that remembers the tumor and attacks it even later.”

Looking to the future, Fujii says, “Our therapy with aAVC is promising because typical immunotherapies have to be tailor-made with the patient’s own cells. In our case we use foreign cells, so they can be made with a stable quality. Because we found that our treatment can lead to the maturation of dendritic cells, immunotherapy can move to local treatment to more systemic treatment based on immune memory.”

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https://www.sciencedaily.com/releases/2016/07/160701093935.htm Original web page at Science Daily

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* New technique helps link complex mouse behaviors to genes that influence them

Mice are one of the most commonly used laboratory organisms, widely used to study everything from autism to infectious diseases. Yet genomic studies in mice have lagged behind those in humans.

“Genome-wide association studies — matching genes to diseases and other traits — have been a big deal in human genetics for the past decade,” said Abraham Palmer, PhD, professor of psychiatry at University of California San Diego School of Medicine. “But progress hasn’t been so great in animal genetics. That’s because researchers have mostly been using crosses between inbred strains, making it impossible to pinpoint specific genomic regions or individual genes associated with a trait. In addition, we didn’t previously have good ways of genotyping animals in a cost-efficient way.”

Now, in a study published July 4, 2016 in Nature Genetics, Palmer’s team used 1,200 outbred mice, which are more similar to a natural population, to test a new cost-effective technique to search for specific genes linked with 66 different physical and behavioral traits.

“This is a system that could be used to discover genes associated with any complex trait a researcher is interested in, in any animal model,” Palmer said. “We can look at any trait and rapidly develop hypotheses about specific genes. It’s like genome-wide association studies in humans, but less expensive. And we can look at certain traits that we can’t in humans.”

Previously, only large regions of a chromosome could be associated with a particular mouse trait or behavior. Palmer’s method takes advantage of the superior mixing that is present in an outbred population to help drill down to specific genes using two steps: genotype-by-sequencing, which sequences about one percent of the mouse genome; and RNA sequencing, which identifies only genes turned “on” in a particular tissue, such as the brain.

With this approach, the researchers found numerous associations between genes and the traits they are associated with. For example, they report that the mouse gene Azi2 is associated with the effects methamphetamines have on body movements, and that mouse gene Zmynd11 is associated with anxiety-like behavior. The findings may be clinically relevant, as humans have analogous genes, Palmer said.

Next, the team will engineer mice that specifically lack these genes to determine if the associations are truly causal and to better understand the underlying mechanisms.

“This study has been extremely gratifying since this is the first time these two genes have been identified as playing roles in psychological conditions,” Palmer said. “And now we can think about targeting these genes or the proteins they encode with novel therapeutics.”

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https://www.sciencedaily.com/releases/2016/07/160704145736.htm  Original web page at Science Daily

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A sense of direction in the brain: Seeing the inner compass

A team of neuroscientists led by Dr. Andrea Burgalossi of the Tübingen Werner Reichardt Centre for Integrative Neuroscience (CIN) at the University of Tübingen has taken an important step towards understanding the ‘inner compass’. Investigating so-called head direction cells (HD cells) in the rodent brain, they were able to find evidence of networks that had been purely theoretical for more than a decade: HD cells are directly linked with different types of brain structures that control navigation. Most intriguingly, they forward information to areas known to contain grid cells — a cell type considered very important in keeping track of one’s position in one’s surroundings, much like a GPS system.

“It was extremely exciting to actually see these cells and their connections under the microscope for the first time,” says Dr. Burgalossi. “They had been a scientific ghost for such a long time.” The cells whose discovery so elates the Tübingen neuroscientist are called HD cells. Their existence was stipulated in the early 1990s, including their function: HD cells recognise the head’s current angle and facing, a simple yet essential part of recognising one’s place in space, and thus of navigation.

But until now, HD cells and their connections with other brain areas had not been identified and observed. The Tübingen researchers were the first to successfully identify them in rats’ brains and observe them microscopically. The researchers found their target by inserting hair-thin glass electrodes into the presubiculum, a brain area that had been previously shown to contain HD cells. These electrodes detected the small electrical impulses in the cell they were attached to, generated whenever the rat was facing a particular direction. The presubiculum consists of several layers, which contain different types of neurons. Not all of them are HD cells. “HD cells have a specific morphology and are predominantly found in layer 3 of the presubiculum. We found no HD cells in layer 2, where the neurons also look different,” Burgalossi explains, “now we have proven that there is a strong relationship between structure and function.” This structure-function relationship can be considered the holy grail of neuroscience, as it allows researchers to not only say ‘this part of the brain does that’, but also lets them gain insights into how the individual neurons do their job.

Moreover, the researchers’ work provides the first piece of evidence that could explain how HD cells forward information from the presubiculum to other brain areas concerned with navigation. In the brain, networks are formed by axons, long and extremely thin appendages that allow neurons to connect to each other. Axons are the ‘wiring’ that makes up the brain’s ‘circuitry’. They can grow to several millimeters in length even in the tiny brains of rodents, while being only about one micrometer in diameter. These dimensions are also the reason why it is so hard to collect direct evidence of network connections between brain structures. Identifying individual neurons under the microscope is done by injecting dyes into the cell body. But neurons are so thin and their axons can be so long that this is no guarantee one actually gets to see one: “The difficult part of our job is often the labeling procedures” says Burgalossi. “Only if you can efficiently fill a HD cell with dye will you be able to find out which specific neuron — among the many different types in the brain — you have before you, and discover where it projects.”

The team found that HD cells in the presubiculum feed information into the medial entorhinal cortex (MEC), a brain area attracting much attention in neuroscience: this is where the fabled ‘grid cells’ are located, a recently discovered type of neuron that got its name from the way its activity forms a very regular ‘grid-map’ of the environment. The discovery of grid cells earned the Norwegian scientist couple Edvard and May-Britt Moser the Nobel Prize in Physiology or Medicine in 2014. The Tübingen neuroscientists’ new results provide the first anatomical evidence of how the entorhinal grid cell area might be functionally connected to the rest of the brain’s navigational apparatus, in particular with HD cells. Neuroscience is one step closer to understanding the inner compass now.

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https://www.sciencedaily.com/releases/2016/07/160706092801.htm  Original web page at Science Daily

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* Imaging study in mice sheds light on how the brain draws a map to a destination

Columbia scientists have uncovered a key feature of the brain’s GPS that helps a mouse find what it is seeking. The study enabled scientists to define the precise duties of cells in a particular region of the hippocampus, the brain’s learning and memory center. The research also advances a long-standing quest in the field of neuroscience: tracing the pathway that information takes while traveling through the brain.

The authors announced these findings in the journal Neuron. “In this study, our goal was to simulate what our brains do as we walk aimlessly down the street, versus how our brains behave when looking for a specific address,” said Attila Losonczy, MD, PhD, a principal investigator at Columbia’s Mortimer B. Zuckerman Mind Brain Behavior Institute, associate professor of neuroscience at Columbia University Medical Center (CUMC) and the paper’s senior author. “By using the powerful two-photon microscope, we were able to observe the activity of individual cells in the mouse hippocampus, and then link that activity to a specific behavior — in this case, navigation — a technological feat that would have been impossible just a few years ago.”

The hippocampus can be divided into distinct areas that form an interconnected circuit through which memory-related information is processed. For this study, Dr. Losonczy and his team focused on the hippocampus’ main output node, area CA1, which was discovered by scientists to encode one’s location — work that was awarded the 2014 Nobel Prize.

“We’ve known that CA1 can be divided into two distinct sublayers of cells: the deep and superficial sublayers,” said Nathan Danielson, a doctoral candidate in neuroscience at CUMC and the paper’s first author. “Scientists have wondered whether this division was an indication that these two sublayers actually served different purposes in learning and memory. But no one had tested it, so we decided to look.”

To study these cells, the researchers placed mice on treadmills that had distinct colors, textures and smells while a two-photon microscope monitored the cellular activity in the CA1. The mice then performed two tasks.

In the first, mice ran on a treadmill while experiencing different sights and sounds, some familiar and others new. In the second, mice were given the task of finding a water reward placed at a specific, unmarked location along the treadmill. The team repeated these experiments over the course of several sessions and monitored how each of the sublayers responded to the different types of learning.

When the mice performed the first task, cells in the superficial sublayer of CA1 appeared to create an internal map that remained largely unchanged from session to session. By contrast, cells in the deep sublayer formed an internal map that was far more dynamic — in effect redrawing a different version of the map during each session.

During the second task, however, when the mice needed to learn the location of the hidden reward, the maps in the deep sublayer were significantly more stable, and less dynamic, than in the first task. The scientists also found that deep-sublayer activity was closely linked to the animal’s ability to find the reward. This distinction between the sublayers, the authors argue, could signify two different processes important for navigation.

“If you’re walking down the street looking for something specific — say, your favorite restaurant — your brain first needs a map of the neighborhood in general,” said Danielson. But to find that particular restaurant, he continued, the brain also assigns importance, or salience, to that specific location.

“In a sense, it’s the brain’s way of marking a location on a map with a giant X,” Danielson said. “So as you look for that restaurant, you need both the map and the X. Our findings suggest that, in the brain, these distinct types of information could be conveyed by the CA1’s distinct sublayers.”

“And if one month later you wanted to visit somewhere new, the deep sublayer would update the map, effectively marking the spot of the new location, while the underlying map of the neighborhood, created by the superficial sublayer, would remain relatively unchanged,” added Dr. Losonczy.

For Dr. Losonczy, this study speaks to the ingenious way that the brain’s underlying architecture allows it to accomplish a specific type of navigation.

“It’s astounding that the ability to navigate to a desired location, an enormously complex feat, can be represented so precisely in the structure of the hippocampus,” he said. “And it’s even more astounding that we can now witness it happening in real time.”

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/07/160707131127.htm Original web page at Science Daily

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Pituitary tissue grown from human stem cells releases hormones in rats

Researchers have successfully used human stem cells to generate functional pituitary tissue that secretes hormones important for the body’s stress response as well as for its growth and reproductive functions. When transplanted into rats with hypopituitarism–a disease linked to dwarfism and premature aging in humans–the lab-grown pituitary cells promoted normal hormone release. The study, which lays the foundation for future preclinical work, appears June 14 in Stem Cell Reports, a publication of the International Society for Stem Cell Researchers.

“The current treatment options for patients suffering from hypopituitarism, a dysfunction of the pituitary gland, are far from optimal,” says first study author Bastian Zimmer of the Sloan Kettering Institute for Cancer Research. “Cell replacement could offer a more permanent therapeutic option with pluripotent stem cell-derived hormone-producing cells that functionally integrate and respond to positive and negative feedback from the body. Achieving such a long-term goal may lead to a potential cure, not only a treatment, for those patients.”

The pituitary gland is the master regulator of hormone production in the body, releasing hormones that play a key role in bone and tissue growth, metabolism, reproductive functions, and the stress response. Hypopituitarism can be caused by tumors, genetic defects, brain trauma, immune and infectious diseases, or radiation therapy. The consequences of pituitary dysfunction are wide ranging and particularly serious in children, who can suffer severe learning disabilities, growth and skeletal problems, as well as effects on puberty and sexual function.

Currently, patients with hypopituitarism must take expensive, lifelong hormone replacement therapies that poorly mimic the body’s complex patterns of hormone secretion that fluctuates with circadian rhythms and responds to feedback from other organs. By contrast, cell replacement therapies hold promise for permanently restoring natural patterns of hormone secretion while avoiding the need for costly, lifelong treatments.

Recently, scientists developed a procedure for generating pituitary cells from human pluripotent stem cells–an unlimited cell source for regenerative medicine–using organoid cultures that mimic the 3D organization of the developing pituitary gland. However, this approach is inefficient and complicated, relies on ill-defined cellular signals, lacks reproducibility, and is not scalable or suitable for clinical-grade cell manufacturing.

To address these limitations, Zimmer and senior study author Lorenz Studer of the Sloan Kettering Institute for Cancer Research developed a simple, efficient, and robust stem cell-based strategy for reliably producing a large number of diverse, functional pituitary cell types suitable for therapeutic use. Instead of mimicking the complex 3D organization of the developing pituitary gland, this approach relies on the precisely timed exposure of human pluripotent stem cells to a few specific cellular signals that are known to play an important role during embryonic development.

Exposure to these proteins triggered the stem cells to turn into different types of functional pituitary cells that released hormones important for bone and tissue growth (i.e., growth hormone), the stress response (i.e., adrenocorticotropic hormone), and reproductive functions (i.e., prolactin, follicle-stimulating hormone, and luteinizing hormone). Moreover, these stem cell-derived cells released different amounts of hormone in response to known feedback signals generated by other organs in the body.

To test the therapeutic potential of this approach, the researchers transplanted the stem cell-derived pituitary cells under the skin of rats whose pituitary gland had been surgical removed. The cell grafts not only secreted adrenocorticotropic hormone, prolactin, and follicle-stimulating hormone, but they also triggered appropriate hormonal responses in the kidneys.

The researchers were also able to control the relative composition of different hormonal cell types simply by exposing human pluripotent stem cells to different ratios of two proteins: fibroblast growth factor 8 and bone morphogenetic protein 2. This finding suggests their approach could be tailored to generate specific cell types for patients with different types of hypopituitarism. “For the broad application of stem cell-derived pituitary cells in the future, cell replacement therapy may need to be customized to the specific needs of a given patient population,” Zimmer says.

In future studies, the researchers plan to further improve the protocol to generate pure populations of various hormone-releasing cell types, enabling the production of grafts that are tailored to the needs of individual patients. They will also test this approach on more clinically relevant animal models that have pituitary damage caused by radiation therapy and receive grafts in or near the pituitary gland rather than under the skin. This research could have important implications for cancer survivors, given that hypopituitarism is one of the main causes of poor quality of life after brain radiation therapy.

“Our findings represent a first step in treating hypopituitarism, but that does not mean the disease will be cured permanently within the near future,” Zimmer says. “However, our work illustrates the promise of human pluripotent stem cells as it presents a direct path toward realizing the promise of regenerative medicine for certain hormonal disorders.”

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https://www.sciencedaily.com/releases/2016/06/160614133606.htm Original web page at Science Daily

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Low levels of BPA exposure may be considered safe, but new research suggests otherwise

In the report, researchers from Yale show that the genome is permanently altered in the uterus of mice that had been exposed to BPA during their fetal development. These changes were found to mainly affect genes that are regulated by estrogen and are implicated in the formation of estrogen-related diseases such as infertility, endometriosis, endometrial cancer, osteoporosis, prostate cancer, neurodegenerative disease, obesity and breast cancer.

“Our study demonstrates that fetal exposure to BPA leads to a detrimental change in the adult uterine response to estrogens,” said Hugh S. Taylor, M.D., a senior researcher involved in the work and Chief of Obstetrics and Gynecology at Yale-New Haven Children’s Hospital at the Yale School of Medicine in New Haven, Connecticut. “Our study confirms that BPA is an active compound and can negatively impact fetal development and confirms that steps should be taken to reduce maternal consumption of BPA during gestation.”

To make this discovery, Taylor and colleagues used two groups of pregnant mice. One group was exposed to human ranges of BPA by intraperitoneal infusion and the other group was not. The researchers then analyzed the genetic and epigenetic profile of the uterus in the female offspring before sexual maturation and examined how the uterine genes responded to estrogen in each of these groups. They found that even though changes to the uterus may not be present at birth or in early post-natal life, changes become apparent after sexual maturity. The study demonstrated a direct change in the estrogen responses of almost 1,000 genes after fetal BPA exposure.

“This study reaches into the antecedent fetal exposure axis and reveals a striking, delayed onset of uterine gene expression effects in the offspring,” said Thoru Pederson, Ph.D., Editor-in-Chief of The FASEB Journal. “To the extent that these findings could be envisioned to translate to the human, we have in this study a very important body of information.”

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https://www.sciencedaily.com/releases/2016/06/160617113613.htm Original web page at Science Daily

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New view of brain development: Striking differences between adult and newborn mouse brain

Findings reveal mismatch between neuronal activity and blood flow in the brains of newborn mice, shedding new light on how the growing brain feeds itself.

Columbia scientists have found that spikes in the activity of neurons in young mice do not spur corresponding boosts in blood flow — a discovery that stands in stark contrast to the adult mouse brain. This new study raises questions about how the growing human brain meets its energy needs, as well as how best to track brain development with functional magnetic resonance imaging, or fMRI, which relies on blood-flow changes to map neuronal activity in the brain. The research could also provide critical new insights for improving care for infants.

“In the adult brain, neuronal activity triggers a localized boost in blood flow. This relationship between neuronal activity and blood flow has long been assumed to be present from birth, but our findings in mice suggest the opposite: that instead it develops over time,” said Elizabeth Hillman, PhD, a principal investigator at Columbia’s Mortimer B. Zuckerman Mind Brain Behavior Institute, associate professor of biomedical engineering and radiology at Columbia’s Fu Foundation School of Engineering and Applied Science and the paper’s senior author. Our study further suggests that this process is an essential part of building a healthy brain and could represent an unexplored factor in brain disorders that emerge in early childhood.”

Today’s study was motivated by previous fMRI studies in humans that reported vastly different responses in the brains of babies compared to the brains of adults.

“No one knew how to interpret blood-flow responses in the developing brain,” said Mariel Kozberg MD, PhD, a recent Columbia neurobiology graduate in Dr. Hillman’s lab and the paper’s first author. In this study, we needed to find out what was different between adult and newborn brains. Were the differences in neural activity itself, or did they lie in the relationship between this activity and local blood flow changes?”

To answer this question, Drs. Hillman and Kozberg developed a new imaging technique that simultaneously recorded neuronal activity and blood flow in the brains of mice of different ages (from newborn up to adult), tracking how the brain responded when they stimulated each animal’s hind paw.

“When we started to get data we were amazed by what we could see,” said Dr. Kozberg. First, the team’s innovative imaging methods revealed that, for the youngest mice, stimulating the hind paw caused a strong neuronal response, but this response was localized to one region. Then, as the animals got older, the neuronal response began to spread. By 10 days of age, stimulating the right paw first sparked activity on the left side of the brain before traveling to the right side, corresponding to the development of connections between the two hemispheres.

“We realized we were actually watching cells form connections with each other throughout the brain: the development of neural networks,” added Dr. Hillman, who is also a member of the Kavli Institute for Brain Science at Columbia.

The researchers’ second finding was even more startling. In the youngest mice, neuronal activity did not trigger an increase in blood flow, as occurs in the adult mouse brain. But as the animals matured, and their neural networks became more established, the brain’s blood-flow response gradually got stronger over time until the animal reached adulthood.

“It was like the brain was gradually learning to feed itself,” said Dr. Hillman, who notes that this finding makes a lot of sense. “It is hardly surprising that blood vessels — and the machinery linking them to brain activity — would mature in step with the development of neural activity itself.”

However, these results raised a worrying question. The job of blood vessels is to deliver oxygen-rich blood to the brain. So, can the newborn brain truly function and grow without subsequent increases in blood flow? To find out, Drs. Kozberg and Hillman used another optical imaging technique, called flavoprotein imaging, which measures how the newborn brain used oxygen.

“In the youngest animals, we confirmed that neurons were indeed consuming oxygen, but without a rush of fresh blood, they seemed to run out of fuel,” said Dr. Kozberg. “We further found that the neural activity actually caused localized drops in oxygen levels, known as hypoxias.”

Drs. Hillman and Kozberg propose several explanations for this surprising result. “Newborns make an incredible transition from being inside the womb to breathing air in the delivery room,” noted Dr. Hillman. “To survive those first few hours, the newborn brain must be well prepared to withstand enormous fluctuations in the availability of oxygen.”

Because the hypoxias seen in young mice appear to be part of the normal development process, the authors propose that it may in fact serve an important purpose.

“We know that a lack of oxygen can trigger the growth of blood vessels,” said Dr. Kozberg. “So in this case, neural activity in the newborn brain might actually be guiding blood vessels to grow in the right places.”

Moving forward, the team is preparing to compare their results in mice to the human brain. Dr. Hillman is working with researchers at Columbia’s Department of Psychiatry to analyze hundreds of fMRI scans previously collected from newborns, as well as from children of different ages.

“If we can find the same signatures of neurovascular development in human infants, we could turn fMRI into an even more powerful tool. For example, using it to better understand, detect and track the origins of developmental disorders in the newborn brain,” she said.

Dr. Hillman’s team is also eager to continue studying oxygen metabolism in newborns. Preterm infants exposed to high oxygen levels can suffer from retinopathy, a condition in which blood vessels in the eyes grow incorrectly. She hypothesizes that excessive oxygen could lead to the same disruptions to blood-vessel growth in the brain itself.

Added Dr. Hillman, “If we can learn more about the unique metabolic state of the developing brain, we might be able to improve treatment strategies for premature infants, while also gaining a deeper understanding of normal and abnormal brain development overall.”

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/06/160621193102.htm Original web page at Science Daily

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Itchy inflammation of mosquito bites helps viruses replicate

Mosquito bite sites are not just itchy, irritating nuisances — they also make viral infections spread by the insects far worse, new research has found.

The study, led by the University of Leeds, found that inflammation where the insect has bitten not only helps a virus such as Zika or dengue establish an infection in the body more quickly, but that it also helps it to spread around the body, increasing the likelihood of severe illness.

“Mosquito bites are not just annoying — they are key for how these viruses spread around your body and cause disease,” said Dr Clive McKimmie, a research fellow at the School of Medicine and senior author of the study.

“We now want to look at whether medications such as anti-inflammatory creams can stop the virus establishing an infection if used quickly enough after the bite inflammation appears.”

In the new research, published in the journal Immunity, the investigators used mouse models to study the bites of the Aedes aegypti mosquito, the species that spreads infections such as Zika, dengue and Chikungunya.

When a mosquito bites, it injects saliva into the skin. The saliva triggers an immune response in which white blood cells called neutrophils and myeloid cells rush to the site.

But instead of helping, some of these cells get infected and inadvertently replicate the virus, the researchers found.

The team injected viruses into the skin of the mice with or without the presence of a mosquito bite at the injection site and compared the reaction.

In the absence of mosquito bites and their accompanying inflammation, the viruses failed to replicate well, whereas the presence of a bite resulted in a high virus level in the skin.

“This was a big surprise we didn’t expect,” said Dr McKimmie, whose team worked alongside colleagues at the University of Glasgow. “These viruses are not known for infecting immune cells.

“And sure enough, when we stopped these immune cells coming in, the bite did not enhance the infection anymore.”

Despite the enormous disease burden of mosquito-borne viral infections — they are responsible for hundreds of millions of cases across the world — there are few specific therapies or vaccines.

“This research could be the first step in repurposing commonly available anti-inflammatory drugs to treat bite inflammation before any symptoms set in,” said Dr McKimmie, whose study was funded by the Medical Research Council.

“We think creams might act as an effective way to stop these viruses before they can cause disease.” He added that if it is proven to be effective, this approach could work against a multitude of other viruses. “Nobody expected Zika, and before that nobody expected Chikungunya,” he said.

“There are estimated to be hundreds of other mosquito-borne viruses out there and it’s hard to predict what’s going to start the next outbreak.”

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https://www.sciencedaily.com/releases/2016/06/160621132526.htm  Original web page at Science Daily

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Compound shown to reduce brain damage caused by anaesthesia in early study

An experimental drug prevented learning deficits in young mice exposed repeatedly to anaesthesia, according to a study led by researchers from NYU Langone Medical Center and published June 22 in Science Translational Medicine.

The study results may have implications for children who must have several surgeries, and so are exposed repeatedly to general anaesthesia. Past studies have linked such exposure to a higher incidence of learning disabilities, attention deficits and hyperactivity.

Specifically, the research team found that the experimental drug CX456, part of the AMPAkine class in clinical trials for several neurological conditions, counters for the dampening effect of anaesthesia on nerve signaling. The treatment bolstered nerve cell activity as well as learning ability in mice recovering from repeated exposure to general anaesthesia.

“Each year, in the United States alone, more than a million children under age four undergo surgical procedures that require anaesthesia, and the numbers are growing,” says the study’s senior investigator Guang Yang, PhD, assistant professor of anaesthesiology at NYU Langone. “There are currently no effective treatments to combat potential toxicity linked to repeated anaesthesia, and we would like to change that.”

Yang’s group took advantage of genetically engineered young mice that have protein markers which glow in response to changes in nerve function. Researchers then used advanced microscopy to visualize activity in their brains, comparing nerve signaling activity in those exposed to anaesthesia to those who were not.

The research team found that anaesthesia exposure resulted in a prolonged reduction of signal transmission among nerve cells following anaesthesia. They also observed that CX456 treatment enhances this transmission, along with learning and memory in mice exposed to anesthesia.

The team studied the anaesthetic ketamine, which blocks NMDA (N-methyl-D-aspartate) receptor proteins that enable charged particles like calcium to flow into nerve cells, like electric switches that trigger and shape messages. In contrast, CX546 increases nerve cell activity and calcium influx into nerve cells by enhancing the activity of proteins called AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) receptors.

“We were able to counter anaesthesia-induced deficits in the formation of connections between nerve cells and related learning problems,” says Yang. “This work is an important proof-of-principle study, and opens the door to a new direction for preventing long-term neurocognitive deficits.”

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/06/160622144816.htm  Original web page at Science

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Precise control of brain circuit alters mood

Pacemaker circuit keeps emotional centers working together. By combining super-fine electrodes and tiny amounts of a very specific drug, Duke University researchers have singled out a circuit in mouse brains and taken control of it to dial an animal’s mood up and down.

Stress-susceptible animals that behaved as if they were depressed or anxious were restored to relatively normal behavior by tweaking the system, according to a study appearing in the July 20 issue of Neuron.

“If you ‘turn the volume up’ on animals that hadn’t experienced stress, they start normal and then they have a problem,” said lead researcher Kafui Dzirasa, an assistant professor of psychiatry and behavioral sciences, and neurobiology. “But in the animals that had experienced stress and didn’t do well with it, you had to turn their volume up to get them back to normal. It looked like stress had turned the volume down.”

The circuit the team identified and altered is a connection the prefrontal cortex uses to keep time for the limbic system, which governs emotions and basic drives. To regulate mood, the prefrontal cortex acts as a pacemaker to coordinate the actions of the amygdala, which governs stress responses, and the ventral tegmental area, which plays a role in the brain’s reward circuitry.

“These subcortical circuits are the key regulators of our emotional life,” said Helen Mayberg, a professor of psychiatry, neurology and radiology at Emory University who was not involved in this research. “What’s great about this paper is that they use different approaches to see a circuit that’s relevant to a lot of disorders,” said Mayberg, who has been pioneering deep-brain stimulation of very specific sites in the human prefrontal cortex to treat mood disorders.

The emerging picture from this study and others is of a brain built of multi-part circuits that respond in concert and regulate one another. Specificity in understanding these circuits is going to be key to resolving different disorders, Dzirasa said.

“The prefrontal cortex is not just a blob of cells,” Mayberg said. “These findings give insight into which cells go to which area and allow researchers to kind of choreograph their actions.”

Dzirasa is an M.D. just finishing his residency in psychiatry and a Ph.D. neuroscientist with an engineering background. Postdoctoral researcher and first author Rainbo Hultman is a biochemist.

In addition to overcoming the challenges of understanding each other, they asked, “Could we go from a protein, to a signaling activity, to a cell, to a circuit, to this big activity that happens across the whole brain, to actual behavior?” Hultman said.

“Illness can happen at any one of these levels,” said Dzirasa, who is also a member of the Duke Institute for Brain Sciences.

The team started by precisely placing arrays of 32 electrodes in four brain areas of the mice. Then they recorded brain activity as these mice were subjected to a stressful situation called chronic social defeat. This allowed them to see activity between the prefrontal cortex and three areas of the limbic system that are implicated in major depression.

To interpret the complicated data coming from the electrodes, the neuroscientists then turned to Duke colleagues David Dunson of statistical science and Lawrence Carin of electrical engineering, who specialize in statistical analysis of noisy data to find important patterns. Using machine learning algorithms, they identified which parts of the data seemed to be the timing control signal between the prefrontal cortex and the amygdala and zeroed in on the individual neurons involved in that circuit.

“They came back with, ‘It’s this clock signature here that is responsible for which mice become susceptible to stress and which become resilient,'” Dzirasa said.

Hultman then turned to engineered molecules called DREADD developed by University of North Carolina at Chapel Hill pharmacologist Bryan Roth. These Designer Receptors Exclusively Activated by Designer Drug are very specific signal receptors that can be incorporated into the neural circuit’s control spots in very tiny amounts (0.5 microliter). A drug that attaches only to that DREADD is then administered to give the researchers control over the circuit.

This new combination of electronics and drugs to intervene in an individual brain circuit might be used to create mouse models of other mood disorders for other studies, Dzirasa said. But Emory’s Mayberg cautions that a mouse brain is not a human brain and to assess anything like “mood” in a mouse, one can only infer from its behaviors. “It’s hard to do, even in a human,” she said.

https://www.sciencedaily.com/ Science Daily

https://www.sciencedaily.com/releases/2016/06/160623122942.htm  Original web page at Science Daily

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Aging monkeys become more selective regarding their social circle

As people get older, they become choosier about how they spend their time and with whom they spend it. Now, researchers reporting in the Cell Press journal Current Biology on June 23 find, based on a series of experimental and behavioral studies, that similar changes take place in Barbary macaques. The findings offer an evolutionary perspective on why aging humans behave as they do, according to the researchers.

“An important psychological theory suggests that humans become more socially selective when they know that their remaining life time is limited, such as in old age,” says Laura Almeling of the German Primate Center in Göttingen, Germany. “We assume that monkeys are not aware of their own limited future time. Therefore, if they show similar motivational changes in old age, their selectivity cannot be attributed to their knowledge about a limited future time. Instead, we should entertain the possibility that similar physiological changes in aging monkeys and humans contribute to increased selectivity.”

The researchers investigated Barbary macaques’ selectivity regarding their interest in the nonsocial and social environment in a large sample of more than 100 monkeys of different ages kept in the enclosure “La Forêt des Singes” in Rocamadour.

To assess monkeys’ curiosity to explore new things, the researchers presented them with novel objects such as animal toys, a cube filled with colorful plastic pieces in a viscose liquid, and an opaque tube closed with soft tissue at both ends and baited with a food reward. By early adulthood, the monkeys had lost interest in the novel objects. Only the tube containing food held interest for all but the oldest monkeys.

To study their social interests, the researchers showed the monkeys photographs of newborn monkeys, “friends” and “non-friends” and played recorded screams of “friends” and “non-friends.” They also observed how often and how long monkeys interacted with each other. They found that the aging monkeys maintained a keen interest in other monkeys, especially when the other monkey was a socially important individual. Older females continued to make vocalizations in response to interactions of group members in their vicinity, such as infant handlings or conflicts. However, older females engaged in fewer social interactions, although other group members continued to invest in relationships with them.

“With increasing age, the monkeys became more selective in their social interactions,” Almeling says. “They had fewer ‘friends’ and invested less in social interactions. Interestingly, however, they were still interested in what was going on in their social world.”

“Older females continued to respond particularly strongly to hearing a scream for help from their best friend,” Almeling adds. “Older males still looked preferentially at pictures of the newborns,” she says, noting that Barbary macaque males use infants as status symbols.

Overall, the studies suggest that, just like humans, monkeys become more selective as they age: they select social over non-social information, and they are more selective regarding their social interactions. However, the reduced social behavior is not due to a general loss of interest in others. “Changes in social behavior in monkeys and humans may occur in the absence of a limited time perspective and are most likely deeply rooted in primate evolution,” concludes Alexandra Freund from the University of Zurich, who was also involved in the study.

Julia Fischer, principal investigator of the study, suggests that “older monkeys might spend less time socializing because they find social interactions increasingly stressful and therefore avoid them.” She says they will explore these issues and changes in the monkeys’ cognitive performance in future studies.

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/06/160623122938.htm  Original web page at Science Daily