Category: Science News

{Weakening communication between two parts of the brain in mice reduced their fear levels}

Erasing unwanted memories is still the stuff of science fiction, but Weizmann Institute scientists have now managed to erase one type of memory in mice. In a study reported in Nature Neuroscience, they succeeded in shutting down a neuronal mechanism by which memories of fear are formed in the mouse brain. After the procedure, the mice resumed their earlier fearless behavior, “forgetting” they had previously been frightened.

This research may one day help extinguish traumatic memories in humans — for example, in people with post-traumatic stress disorder, or PTSD. “The brain is good at creating new memories when these are associated with strong emotional experiences, such as intense pleasure or fear,” says team leader Dr. Ofer Yizhar. “That’s why it’s easier to remember things you care about, be they good or bad; but it’s also the reason that memories of traumatic experiences are often extremely long-lasting, predisposing people to PTSD.”

In the study, postdoctoral fellows Dr. Oded Klavir (now an investigator at the University of Haifa) and Dr. Matthias Prigge, both from Yizhar’s lab in the Neurobiology Department, together with departmental colleague Prof. Rony Paz and graduate student Ayelet Sarel, examined the communication between two brain regions: the amygdala and the prefrontal cortex. The amygdala plays a central role in controlling emotions, whereas the prefrontal cortex is mostly responsible for cognitive functions and storing long-term memories. Previous studies had suggested that the interactions between these two brain regions contribute to the formation and storage of aversive memories, and that these interactions are compromised in PTSD; but the exact mechanisms behind these processes were unknown.

In the new study, the researchers first used a genetically-engineered virus to mark those amygdala neurons that communicate with the prefrontal cortex. Next, using another virus, they inserted a gene encoding a light-sensitive protein into these neurons. When they shone a light on the brain, only the neurons containing the light-sensitive proteins became activated. These manipulations, belonging to optogenetics — a technique extensively studied in Yizhar’s lab — enabled the researchers to activate only those amygdala neurons that interact with the cortex, and then to map out the cortical neurons that receive input from these light-sensitive neurons.

Once they had achieved this precise control over the cellular interactions in the brain, they turned to exploring behavior: Mice that are less fearful are more likely to venture farther than others. They found that when the mice were exposed to fear-inducing stimuli, a powerful line of communication was activated between the amygdala and the cortex. The mice whose brains displayed such communication were more likely to retain a memory of the fear, acting frightened every time they heard the sound that had previously been accompanied by the fear-inducing stimuli. Finally, to clarify how this line of communication contributes to the formation and stability of memory, the scientists developed an innovative optogenetic technique for weakening the connection between the amygdala and the cortex, using a series of repeated light pulses. Indeed, once the connection was weakened, the mice no longer displayed fear upon hearing the sound. Evidently, “tuning down” the input from the amygdala to the cortex had destabilized or perhaps even destroyed their memory of fear.

Says Yizhar: “Our research has focused on a fundamental question in neuroscience: How does the brain integrate emotion into memory? But one day our findings may help develop better therapies targeting the connections between the amygdala and the prefrontal cortex, in order to alleviate the symptoms of fear and anxiety disorders.”

Source:Science Daily

{Birds show an amazing diversity in plumage colour and patterning. But what are the genetic mechanisms creating such patterns? In a new study published today in PLOS Genetics, Swedish and French researchers report that two independent mutations are required to explain the development of the sex-linked barring pattern in chicken. Both mutations affect the function of CDKN2A, a tumour suppressor gene associated with melanoma in humans.}

Research in pigmentation biology has made major advances the last 20 years in identifying genes controlling variation in pigmentation in mammals and birds. However, the most challenging question is still how colour patterns are genetically controlled. Birds are outstanding as regards the diversity and complexity in colour patterning. The study published today has revealed the genetic basis for the striped feather characteristic of sex-linked barring. One example of this fascinating plumage colour is the French breed Coucou de Rennes. The name refers to the fact that this plumage colour resembles the barring patterns present in the common cuckoo (Cuculus canorus). The sex-linked barring locus is on the Z chromosome. (In chickens as well as in other birds the male has chromosomes ZZ while females have ZW).

“Our data show that sex-linked barring is caused by two independent mutations that act together. One is a regulatory mutation that increases the expression of CDKN2A. The other changes the protein sequence and makes the protein less functionally active. We are sure that both mutations contribute to the sex-linked barring pattern because we have also studied chicken that only carry the regulatory mutation and they show a very pale plumage with only weak dark stripes. Thus, this represents an evolutionary process in which the regulatory mutation occurred first followed by the mutation affecting the protein structure. The combined effect of the two mutations causes an even more appealing phenotype for the human eye,” says Leif Andersson, Uppsala University, Swedish University of Agricultural Sciences and Texas A&M University, who led the study.

“The most important reason for the extensive colour variation among our domestic animals is that we appreciate this diversity, as long as the mutations underlying the variation are not causing health issues for the animals,” says Leif Andersson.

The study illustrates how useful domestic animals are as models for evolutionary processes in nature. Leif Andersson argues that a similar evolution of gene variants comprising multiple genetic changes affecting the function of a single gene is the rule rather than the exception in natural populations.

CDKN2A is a well-studied tumour suppressor gene that takes part in the regulation of cell division and cell survival. Mutations that inactivate CDKN2A are the most common explanation for familiar forms of melanomas in humans. (However, the great majority of melanoma cases are not associated with a strong genetic risk factor.)

“The gene variant underlying sex-linked barring has an opposite effect compared with the mutations causing melanoma in humans. Sex-linked barring is associated with a gene variant that makes CDKN2A more active leading to a cyclic deficit of pigment cells causing the white stripes during the development of an individual feather. It appears that pigment cells are particularly susceptible to changes in the function of CDKN2A as inactivating mutations in humans are associated with melanoma but rarely other cancer forms and activating mutations cause sex-linked barring in chickens but no other side effects are known,” says Doreen Schwochow Thalmann, PhD student and first author of the paper.

“It is fascinating that a large proportion of chickens used for egg and meat production around the world carry these mutations in a tumour suppressor gene. An example of such a breed is White Leghorn which is one of the most prominent breeds used for egg production, but sex-linked barring is not apparent in these breeds because they also carry the dominant white colour that eliminates all pigment production and masks the effect of sex-linked barring,” says Leif Andersson.

Source:Science Daily

{When we visit a friend or go to the beach, our brain stores a short-term memory of the experience in a part of the brain called the hippocampus. Those memories are later “consolidated” — that is, transferred to another part of the brain for longer-term storage.}

A new MIT study of the neural circuits that underlie this process reveals, for the first time, that memories are actually formed simultaneously in the hippocampus and the long-term storage location in the brain’s cortex. However, the long-term memories remain “silent” for about two weeks before reaching a mature state.

“This and other findings in this paper provide a comprehensive circuit mechanism for consolidation of memory,” says Susumu Tonegawa, the Picower Professor of Biology and Neuroscience, the director of the RIKEN-MIT Center for Neural Circuit Genetics at the Picower Institute for Learning and Memory, and the study’s senior author.

The findings, which appear in Science on April 6, may force some revision of the dominant models of how memory consolidation occurs, the researchers say.

The paper’s lead authors are research scientist Takashi Kitamura, postdoc Sachie Ogawa, and graduate student Dheeraj Roy. Other authors are postdocs Teruhiro Okuyama and Mark Morrissey, technical associate Lillian Smith, and former postdoc Roger Redondo.

Long-term storage

Beginning in the 1950s, studies of the famous amnesiac patient Henry Molaison, then known only as Patient H.M., revealed that the hippocampus is essential for forming new long-term memories. Molaison, whose hippocampus was damaged during an operation meant to help control his epileptic seizures, was no longer able to store new memories after the operation. However, he could still access some memories that had been formed before the surgery.

This suggested that long-term episodic memories (memories of specific events) are stored outside the hippocampus. Scientists believe these memories are stored in the neocortex, the part of the brain also responsible for cognitive functions such as attention and planning.

Neuroscientists have developed two major models to describe how memories are transferred from short- to long-term memory. The earliest, known as the standard model, proposes that short-term memories are initially formed and stored in the hippocampus only, before being gradually transferred to long-term storage in the neocortex and disappearing from the hippocampus.

A more recent model, the multiple trace model, suggests that traces of episodic memories remain in the hippocampus. These traces may store details of the memory, while the more general outlines are stored in the neocortex.

Until recently, there has been no good way to test these theories. Most previous studies of memory were based on analyzing how damage to certain brain areas affects memories. However, in 2012, Tonegawa’s lab developed a way to label cells called engram cells, which contain specific memories. This allows the researchers to trace the circuits involved in memory storage and retrieval. They can also artificially reactivate memories by using optogenetics, a technique that allows them to turn target cells on or off using light.

In the new Science study, the researchers used this approach to label memory cells in mice during a fear-conditioning event — that is, a mild electric shock delivered when the mouse is in a particular chamber. Then, they could use light to artificially reactivate these memory cells at different times and see if that reactivation provoked a behavioral response from the mice (freezing in place). The researchers could also determine which memory cells were active when the mice were placed in the chamber where the fear conditioning occurred, prompting them to naturally recall the memory.

The researchers labeled memory cells in three parts of the brain: the hippocampus, the prefrontal cortex, and the basolateral amygdala, which stores memories’ emotional associations.

Just one day after the fear-conditioning event, the researchers found that memories of the event were being stored in engram cells in both the hippocampus and the prefrontal cortex. However, the engram cells in the prefrontal cortex were “silent” — they could stimulate freezing behavior when artificially activated by light, but they did not fire during natural memory recall.

“Already the prefrontal cortex contained the specific memory information,” Kitamura says. “This is contrary to the standard theory of memory consolidation, which says that you gradually transfer the memories. The memory is already there.”

Over the next two weeks, the silent memory cells in the prefrontal cortex gradually matured, as reflected by changes in their anatomy and physiological activity, until the cells became necessary for the animals to naturally recall the event. By the end of the same period, the hippocampal engram cells became silent and were no longer needed for natural recall. However, traces of the memory remained: Reactivating those cells with light still prompted the animals to freeze.

In the basolateral amygdala, once memories were formed, the engram cells remained unchanged throughout the course of the experiment. Those cells, which are necessary to evoke the emotions linked with particular memories, communicate with engram cells in both the hippocampus and the prefrontal cortex.

Theory revision

The findings suggest that traditional theories of consolidation may not be accurate, because memories are formed rapidly and simultaneously in the prefrontal cortex and the hippocampus on the day of training.

“They’re formed in parallel but then they go different ways from there. The prefrontal cortex becomes stronger and the hippocampus becomes weaker,” Morrissey says.

Further studies are needed to determine whether memories fade completely from hippocampal cells or if some traces remain. Right now, the researchers can only monitor engram cells for about two weeks, but they are working on adapting their technology to work for a longer period.

Kitamura says he believes that some trace of memory may stay in the hippocampus indefinitely, storing details that are retrieved only occasionally. “To discriminate two similar episodes, this silent engram may reactivate and people can retrieve the detailed episodic memory, even at very remote time points,” he says.

The researchers also plan to further investigate how the prefrontal cortex engram maturation process occurs. This study already showed that communication between the prefrontal cortex and the hippocampus is critical, because blocking the circuit connecting those two regions prevented the cortical memory cells from maturing properly.

Source:Science Daily

{The Eastern Region Police Commander (RPC), Assistant Commissioner of Police (ACP) Dismas Rutaganira met with hundreds of residents of Kabare Sector in Kayonza District and urged them to take a lead in fighting drug trafficking.}

He said that “ownership” is a great tool in identifying, reporting and arresting drug dealers.

The RPC was speaking on April 5, shortly after he led over 100 police officers in an agricultural exercise to spray plantations against leaf diseases and fungicides.

The event was also attended by the mayor of Kayonza, Jean Claude Murenzi.

ACP Rutaganira advised residents to avoid drugs saying that, “It is a trap against success… there is no happiness but consequences.”

The RPC advised youth in the area that; “don’t forget you are the future leaders of this country. If you reject drugs and help report the traffickers, you are contributing to building a safer country.”

He said hat much as efforts were put in place to fight drug trafficking, there is still need for relentless and concerted the efforts to break chains of supply and ultimately prevent consumption.

He outlined effects of drug consumption saying, “such substances can have enormous health effects, such as brain damage, besides behavioural problems.”

“These are consequences to the consumer but the effects can go as far as affecting families, communities and the country. This is why we should collectively fight the consumption of these substances,” said ACP Rutaganira.

Though police recorded success in working with local communities towards curbing drug abuse and trafficking, police have also initiated operations to crackdown such criminal activities that have yielded results.

Source:Police

{Humans are able to interpret the behaviour of others by attributing mental states to them (and to themselves). By adopting the perspectives of other persons, they can assume their emotions, needs and intentions and react accordingly. In the animal kingdom, the ability to attribute mental states (Theory of Mind) is a highly contentious issue. Cognitive biologists from the Messerli Research Institute of the University of Veterinary Medicine Vienna could prove with a new test procedure that dogs are not only able to identify whether a human has an eye on a food source and, therefore, knows where the food has been hidden. They can also apply this knowledge in order to correctly interpret cues by humans and find food they cannot see themselves. This perspective taking ability is an important component of social intelligence. It helps dogs to cope with the human environment. The results have been published in the journal Animal Cognition.}

The so-called Theory of Mind describes the ability in humans to understand mental states in conspecifics such as emotions, intentions, knowledge, beliefs and desires. This ability develops in humans within the first four or five years of life while it is usually denied in animals. Indications that animals can understand mental states or even states of knowledge of others have only been found in apes and corvids so far. Dogs have been tested several times, but the results were poor and contradictory.

With a new experimental approach, cognitive biologists from the Messerli Research Institute could now provide solid evidence for dogs being able to adopt our perspective. By adopting the position of a human and following their gaze, dogs understand what the human could see and, consequently, know. This ability to ascribe knowledge is only a component of a full-blown Theory of Mind, but an important one.

Identifying the right informant

The so-called Guesser-Knower paradigm is a standard test in research into the attribution of knowledge to others. This experiment involves two persons: a “Knower” who hides food, invisibly for the dog, in one of several food containers or knows where somebody else has hided it, and a “Guesser.” The Guesser has either not been in the room or covered her eyes during the hiding of the food. A non-transparent wall blocks the animals’ view of the food being hidden. After that, the two humans become informants by pointing to different food containers.

The Knower always points to the baited container and the Guesser to another one. All containers smell of food. “To get the food, the dogs have to understand who knows the hiding place (Knower) and who does not and can, therefore, only guess (Guesser). They must identify the informant they can rely on if they have to decide for one food container,” said principal investigator Ludwig Huber. In approximately 70 per cent of the cases the dogs chose the container indicated by the Knower – and thus were able to successfully accomplish the test. This result was independent of the position of the food container, the person acting as the Knower and where the Guesser was looking.

Dogs can adopt human perspectives

The only aim of this test series, however, was to independently confirm a study carried out in New Zealand. Clear evidence of dogs being able to adopt our perspective and take advantage of it was provided in a new test developed by the team, the so-called “Guesser looking away” test.

In this new experiment, a third person in the middle hides the food. This person does not give cues later on. The potential informants were kneeing left and right of this hider and looked to the same side and slightly down. Thus, one of the two persons looked towards the baiter, the other person looked away. “This means that the tested dogs, in order to get the food, had to judge who is the Knower by adopting the informants’ perspectives and following their gazes,” explained Huber. Even in this test, which is very difficult for the animals, approximately 70 per cent of the trials had been mastered.

Adopting the human perspective leads to invisible food

Being able to adopt the perspective of a human does, however, not require the ability to understand intentions or wishes. “But the study showed that dogs can find out what humans or conspecifics can or cannot see,” explained Huber. “By adopting the positions of humans and following their gazes geometrically, they find out what humans see and, therefore, know – and consequently whom they can trust or not.”

In similar experiments, chimpanzees and few bird species such as scrub jays and ravens were able to understand the state of knowledge and also the intentions of conspecifics and modify their own behaviour accordingly. For dogs, there have only been specualtions and vague indications so far. But dogs understand our behaviour very well, for example our degree of attention. They can learn from directly visible cues such as gestures or gazes. Thus, they are able to find food even if their view of it has been blocked. “The ability to interpret our behaviour and anticipate our intentions, which has obviously developed through a combination of domestication and individual experience, seems to have supported the ability to adopt our perspective,” said Huber. “It still remains unclear which cognitive mechanisms contribute to this ability. But it helps dogs to find their way in our world very well.”

Source:Science Daily

{Restorative, sedative-free slumber can ward off mental and physical ailments, suggests research}

As we grow old, our nights are frequently plagued by bouts of wakefulness, bathroom trips and other nuisances as we lose our ability to generate the deep, restorative slumber we enjoyed in youth.

But does that mean older people just need less sleep?

Not according to UC Berkeley researchers, who argue in an article published April 5 in the journal Neuron that the unmet sleep needs of the elderly elevate their risk of memory loss and a wide range of mental and physical disorders.

“Nearly every disease killing us in later life has a causal link to lack of sleep,” said the article’s senior author, Matthew Walker, a UC Berkeley professor of psychology and neuroscience. “We’ve done a good job of extending life span, but a poor job of extending our health span. We now see sleep, and improving sleep, as a new pathway for helping remedy that.”

Unlike more cosmetic markers of aging, such as wrinkles and gray hair, sleep deterioration has been linked to such conditions as Alzheimer’s disease, heart disease, obesity, diabetes and stroke, he said.

Though older people are less likely than younger cohorts to notice and/or report mental fogginess and other symptoms of sleep deprivation, numerous brain studies reveal how poor sleep leaves them cognitively worse off.

Moreover, the shift from deep, consolidated sleep in youth to fitful, dissatisfying sleep can start as early as one’s 30s, paving the way for sleep-related cognitive and physical ailments in middle age.

And, while the pharmaceutical industry is raking in billions by catering to insomniacs, Walker warns that the pills designed to help us doze off are a poor substitute for the natural sleep cycles that the brain needs in order to function well.

“Don’t be fooled into thinking sedation is real sleep. It’s not,” he said.

For their review of sleep research, Walker and fellow researchers Bryce Mander and Joseph Winer cite studies, including some of their own, that show the aging brain has trouble generating the kind of slow brain waves that promote deep curative sleep, as well as the neurochemicals that help us switch stably from sleep to wakefulness.

“The parts of the brain deteriorating earliest are the same regions that give us deep sleep,” said article lead author Mander, a postdoctoral researcher in Walker’s Sleep and Neuroimaging Laboratory at UC Berkeley.

Aging typically brings on a decline in deep non-rapid eye movement (NREM) or “slow wave sleep,” and the characteristic brain waves associated with it, including both slow waves and faster bursts of brain waves known as “sleep spindles.”

Youthful, healthy slow waves and spindles help transfer memories and information from the hippocampus, which provides the brain’s short-term storage, to the prefrontal cortex, which consolidates the information, acting as the brain’s long-term storage.

“Sadly, both these types of sleep brain waves diminish markedly as we grow old, and we are now discovering that this sleep decline is related to memory decline in later life,” said Winer, a doctoral student in Walker’s lab.

Another deficiency in later life is the inability to regulate neurochemicals that stabilize our sleep and help us transition from sleep to waking states. These neurochemicals include galanin, which promotes sleep, and orexin, which promotes wakefulness. A disruption to the sleep-wake rhythm commonly leaves older adults fatigued during the day but frustratingly restless at night, Mander said.

Of course, not everyone is vulnerable to sleep changes in later life: “Just as some people age more successfully than others, some people sleep better than others as they get older, and that’s another line of research we’ll be exploring,” Mander said.

Meanwhile, non-pharmaceutical interventions are being explored to boost the quality of sleep, such as electrical stimulation to amplify brain waves during sleep and acoustic tones that act like a metronome to slow brain rhythms.

However, promoting alternatives to prescription and over-the-counter sleep aids is sure to be challenging.

“The American College of Physicians has acknowledged that sleeping pills should not be the first-line kneejerk response to sleep problems,” Walker said. “Sleeping pills sedate the brain, rather than help it sleep naturally. We must find better treatments for restoring healthy sleep in older adults, and that is now one of our dedicated research missions.”

Also important to consider in changing the culture of sleep is the question of quantity versus quality.

“Previously, the conversation has focused on how many hours you need to sleep,” Mander said. “However, you can sleep for a sufficient number of hours, but not obtain the right quality of sleep. We also need to appreciate the importance of sleep quality.

“Indeed, we need both quantity and quality,” Walker said.

Source:Science Daily

{Research shows having a dog early in life may alter gut bacteria in immune-boosting ways}

If you need a reason to become a dog lover, how about their ability to help protect kids from allergies and obesity?

A new University of Alberta study showed that babies from families with pets — 70 per cent of which were dogs — showed higher levels of two types of microbes associated with lower risks of allergic disease and obesity.

But don’t rush out to adopt a furry friend just yet.

“There’s definitely a critical window of time when gut immunity and microbes co-develop, and when disruptions to the process result in changes to gut immunity,” said Anita Kozyrskyj, a U of A pediatric epidemiologist and one of the world’s leading researchers on gut microbes — microorganisms or bacteria that live in the digestive tracts of humans and animals.

The latest findings from Kozyrskyj and her team’s work on fecal samples collected from infants registered in the Canadian Healthy Infant Longitudinal Development study build on two decades of research that show children who grow up with dogs have lower rates of asthma.

The theory is that exposure to dirt and bacteria early in life — for example, in a dog’s fur and on its paws — can create early immunity, though researchers aren’t sure whether the effect occurs from bacteria on the furry friends or from human transfer by touching the pets, said Kozyrskyj.

Her team of 12, including study co-author and U of A post-doctoral fellow Hein Min Tun, take the science one step closer to understanding the connection by identifying that exposure to pets in the womb or up to three months after birth increases the abundance of two bacteria, Ruminococcus and Oscillospira, which have been linked with reduced childhood allergies and obesity, respectively.

“The abundance of these two bacteria were increased twofold when there was a pet in the house,” said Kozyrskyj, adding that the pet exposure was shown to affect the gut microbiome indirectly — from dog to mother to unborn baby — during pregnancy as well as during the first three months of the baby’s life. In other words, even if the dog had been given away for adoption just before the woman gave birth, the healthy microbiome exchange could still take place.

The study also showed that the immunity-boosting exchange occurred even in three birth scenarios known for reducing immunity, as shown in Kozyrskyj’s previous work: C-section versus vaginal delivery, antibiotics during birth and lack of breastfeeding.

What’s more, Kozyrskyj’s study suggested that the presence of pets in the house reduced the likelihood of the transmission of vaginal GBS (group B Strep) during birth, which causes pneumonia in newborns and is prevented by giving mothers antibiotics during delivery.

It’s far too early to predict how this finding will play out in the future, but Kozyrskyj doesn’t rule out the concept of a “dog in a pill” as a preventive tool for allergies and obesity.

“It’s not far-fetched that the pharmaceutical industry will try to create a supplement of these microbiomes, much like was done with probiotics,” she said.

Source:Science Daily

{Pudgy roundworms storing a particular type of fat live longer than their more svelte counterparts, according to a study by researchers at the Stanford University School of Medicine.
}

This fatty buildup, and the subsequent increase in the worms’ life span, can be stimulated simply by feeding the animals monounsaturated fatty acids like those found in olive oil. Because many species share similar patterns of fat metabolism, it’s possible that the findings could extend to other animals, including humans, the researchers believe.

The finding suggests that accumulating a specific type of fat can actually be beneficial. It came as a surprise to the researchers because severe caloric restriction has also been shown to extend the life span of many animals.

“We have known for some time that metabolic changes can affect life span, but we expected the long-lived animals in our study would be thinner,” said Anne Brunet, PhD, professor of genetics. “Instead, they turned out to be fatter. This was quite a surprise.”

Brunet, who is also an associate director of Stanford’s Paul F. Glenn Center for the Biology of Aging, is the senior author of the study, which will be published online April 5 in Nature. Graduate student Shuo Han is the lead author.

Exploring epigenetics

The researchers began their study as a way to explore epigenetics, a process by which organisms modulate their gene expression in response to environmental cues without changing the underlying sequence of their DNA. In this case, the researchers were looking at how epigenetic protein complexes, which add or remove chemical tags on the cell’s DNA packaging machinery, might interact with metabolic changes in a roundworm to affect its life span.

“It’s well-known that epigenetic protein complexes and metabolic pathways both affect life span in many animals,” said Brunet, who also holds the Michele and Timothy Barakett Endowed Professorship. “But until now we didn’t know why, or whether these two processes were linked in some way.”

Han and Brunet set out to examine the effect of blocking the activity of a complex of proteins called COMPASS on the metabolism of laboratory roundworms. Roundworms are a popular animal model for longevity studies because of their relatively short life span and ease of care. Together, the COMPASS proteins add chemical tags called methyl groups to a component of a cell’s DNA packaging machinery called a histone. The presence or absence of this tag affects whether the DNA remains wound up tightly like thread on a spool, or unfurls to allow its genes to be expressed.

Reducing the number of methyl tags on the histone keeps the DNA inaccessible, and researchers in Brunet’s lab had previously shown that worms lacking COMPASS activity lived about 30 percent longer than their peers. Han wanted to know why.

“We thought that this epigenetic modification caused by COMPASS might mimic dietary restriction,” Brunet said. “So we began looking at the metabolism and fat content of the worms lacking COMPASS activity.”

Han noted that the worms lacking a functional COMPASS complex not only lived longer than their peers, but they also accumulated fats in their guts. Closer inspection with an analytical technique called gas chromatography coupled with mass spectrometry showed that the fat was primarily a specific class called monounsaturated fatty acids — the same kind of fat that’s found in olive oil, nuts and avocados.

“This was exciting, but understanding why this was happening took some time,” said Brunet. That’s because COMPASS acts primarily in germline tissue, which makes the eggs and sperm. But the fat Han observed was accumulating in the intestine.

{{Inhibiting COMPASS}}

Han found that inhibiting COMPASS activity in the germline somehow caused a specific increase in the expression of enzymes that convert polyunsaturated fats into monounsaturated fats in the animals’ guts. Although the method of communication between the germline and intestinal tissue is still under investigation, the finding was intriguing. Humans with diets rich in monounsaturated fats have been shown to have a reduced risk for heart disease and diabetes, and some studies have shown that centenarians store more monounsaturated fat than non-centenarians.

“We wanted to know whether this accumulation of monounsaturated fats was important to life span,” Brunet said, “so we fed both monounsaturated and polyunsaturated fats directly to the worms. We found that the monounsaturated fats accumulated in the worms’ guts and increased their life span even when COMPASS was not mutated. In contrast, polyunsaturated fats did not have the same effect.”

The researchers are now working to understand how the monounsaturated fatty acid accumulation might work to extend life span. Some possibilities include the ready availability of quick energy in the stored fat, or the fact that the fat may provide an accessible source of lipid-based signaling molecules to facilitate communication between cells or tissues. Alternatively, the monounsaturated fats may help preserve the fluidity of the lipid membranes that enclose and protect cells.

Source:Science Daily

{The gentle burbling of a brook, or the sound of the wind in the trees can physically change our mind and bodily systems, helping us to relax. New research explains how, for the first time.}

Researchers at Brighton and Sussex Medical School (BSMS) found that playing ‘natural sounds’ affected the bodily systems that control the flight-or-fright and rest-digest autonomic nervous systems, with associated effects in the resting activity of the brain. While naturalistic sounds and ‘green’ environments have frequently been linked with promoting relaxation and wellbeing, until now there has been no scientific consensus as to how these effects come about. The study has been published in Scientific Reports.

The lead author, Dr Cassandra Gould van Praag said, “We are all familiar with the feeling of relaxation and ‘switching-off’ which comes from a walk in the countryside, and now we have evidence from the brain and the body which helps us understand this effect. This has been an exciting collaboration between artists and scientists, and it has produced results which may have a real-world impact, particularly for people who are experiencing high levels of stress.”

In collaboration with audio visual artist Mark Ware, the team at BSMS conducted an experiment where participants listened to sounds recorded from natural and artificial environments, while their brain activity was measured in an MRI scanner, and their autonomic nervous system activity was monitored via minute changes in heart rate. The team found that activity in the default mode network of the brain (a collection of areas which are active when we are resting) was different depending on the sounds playing in the background:

When listening to natural sounds, the brain connectivity reflected an outward-directed focus of attention; when listening to artificial sounds, the brain connectivity reflected an inward-directed focus of attention, similar to states observed in anxiety, post-traumatic stress disorder and depression. There was also an increase in rest-digest nervous system activity (associated with relaxation of the body) when listening to natural compared with artificial sounds, and better performance in an external attentional monitoring task.

Interestingly, the amount of change in nervous system activity was dependant on the participants’ baseline state: Individuals who showed evidence of the greatest stress before starting the experiment showed the greatest bodily relaxation when listening to natural sounds, while those who were already relaxed in the brain scanner environment showed a slight increase in stress when listening to natural compared with artificial sounds.

The study of environmental exposure effects is of growing interest in physical and mental health settings, and greatly influences issues of public health and town planning. This research is first to present an integrated behavioural, physiological and brain exploration of this topic.

Artist Mark Ware commented, “Art-science collaborations can be problematic, often due to a lack of shared knowledge and language (scientific and artistic), but the team at BSMS has generously sought common ground, which has resulted in this exciting and successful outcome. We have plans to continue collaborating and I am keen to explore how the results of this work might be applied to the creation and understanding of time-based art (installations, multimedia performance, and film) for the benefit of people in terms of wellbeing and health.”

Source:Science Daily

{Research reveals vicious cycle of climate change, cattle diet and rising methane}

Scientists at the Royal Botanic Gardens, Kew, Scotland’s Rural College (SRUC) and the Senckenberg Biodiversity and Climate Research Centre, Frankfurt have published a paper revealing an important discovery surrounding plants used to feed livestock; that plants growing in warmer conditions are tougher and have lower nutritional value to grazing livestock, potentially inhibiting milk and meat yields and raising the amount of methane released by the animals. Higher amounts of methane are produced when plants are tougher to digest — an effect of a warmer environment. Methane is a potent greenhouse gas, around 25 times better at trapping heat than carbon dioxide. More than 95% of the methane produced by cows comes from their breath through eructation (belching) as they “chew the cud.”

Dr Mark Lee, a research fellow in Natural Capital & Plant Health at the Royal Botanic Gardens, Kew who led the research says; “The vicious cycle we are seeing now is that ruminant livestock such as cattle produce methane which warms our planet. This warmer environment alters plants so they are tougher to digest, and so each mouthful spends more time in the animals’ stomach, producing more methane, further warming the planet, and the cycle continues. We need to make changes to livestock diets to make them more environmentally sustainable.”

There are several reasons why rising temperatures may make plants tougher for grazing livestock to digest. Plants have adaptations to prevent heat damage, they can flower earlier, have thicker leaves or in some cases, tougher plants can invade into new areas replacing more nutritious species — all of which makes grazing more difficult. This is a pressing concern, because climate change is likely to make plants tougher for grazing cattle, increasing the amount of methane that the animals breathe out into the atmosphere.

The researchers mapped the regions where methane produced by cattle will increase to the greatest extent as the result of reductions in plant nutritional quality. Methane production is generally expected to increase all around the world, with hotspots identified in North America, Central and Eastern Europe, and Asia, where the effects of climate change may be the most severe. Many of these regions are where livestock farming is growing most rapidly. For example, meat production has increased annually by around 3.4% across Asia, compared with a more modest 1% increase across Europe.

“Now is the time to act, because the demand for meat-rich diets is increasing around the world. Our research has shown that cultivating more nutritious plants may help us to combat the challenges of warmer temperatures. We are undertaking work at Kew to identify the native forage plants that are associated with high meat and milk production and less methane, attempting to increase their presence on the grazing landscape. We are also developing our models to identify regions where livestock are going to be exposed to reductions in forage quality with greater precision. It is going to be important to put plans in place to help those countries exposed to the most severe challenges from climate change to adapt to a changing world” said Dr Mark Lee.

Global meat production has increased rapidly in recent years to meet demand, from 71 million tonnes in 1961 to 318 million tonnes in 2014, a 78% increase in 53 years (FAOSTAT, 2016). Grazing lands have expanded to support this production, particularly across Asia and South America, and now cover 35 million km2; 30% of Earth’s ice-free surface. However, livestock are valuable. They are worth in excess of $1.4 trillion to the global economy and livestock farming sustains or employs 1.3 billion people around the world (Thornton, 2010). The upward trend in livestock production and associated GHG emissions are projected to continue in the future and global stocks of cattle, goats and sheep are expected to reach 6.3 billion by 2050 (Steinfeld et al. 2006). If these rises are to continue then the researchers say that it will be necessary to limit the growth of livestock farming in the most rapidly warming regions, if significant losses in livestock production efficiency and increases in methane emissions are to be avoided.

Regions in light grey are currently unsuitable for ruminant livestock, and regions beyond the range of the dataset are shaded dark grey.

Source:Science Daily