Mosquitoes can learn to love DEET

Mosquitoes can learn to like DEET, the world’s most powerful insect repellent, according to a new study.

Every summer, millions of people spray themselves with DEET to keep mosquitoes away. But the new research suggests mosquitoes may be able to learn to associate the repellent with food—and even become attracted to it.

The study in the Journal of Experimental Biology, was a collaboration between Clément Vinauger, associate professor at Virginia Tech, and Claudio Lazzari at the University of Tours in France.

“If someone applies DEET and the concentration fades over time, but a mosquito still manages to feed, the insect may begin associating that smell with a reward,” says Vinauger, part of the Department of Biochemistry in the College of Agriculture and Life Sciences.

“That’s a possibility we should take seriously when we think about how repellents are used in the real world.”

The study focused on the yellow fever mosquito, Aedes aegypti, a species that spreads dengue fever, Zika, yellow fever, and chikungunya, which infect tens of millions of people each year.

Researchers trained the mosquitoes using a form of Pavlovian conditioning—the same learning principle behind Ivan Pavlov’s famous experiments in which dogs learned to associate the sound of a bell with food.

Mosquitoes were restrained behind fabric mesh with a bag of warm blood positioned just out of reach. After the mosquitoes began to feed on the blood, researchers introduced the smell of DEET. After repeating the experiment four times, more than 60% of the insects tried to feed when presented with only the smell of DEET.

Next, mosquitoes were given a choice between two human hands—one untreated and one coated with DEET at normal concentrations. Untrained mosquitoes avoided the DEET-treated hand. Trained mosquitoes were drawn to it.

The researchers also found mosquitoes could form the same association when sugar, instead of blood, was used as the reward.

“The common assumption has always been that repellents work because of their chemistry—that DEET simply smells bad to mosquitoes and they flee or that its chemistry prevents mosquitoes from smelling us,” says Vinauger, who is also an affiliate of Fralin Life Sciences Institute’s Center for Emerging, Zoonotic, and Arthropod-borne Pathogens.

“But what we are showing is that the mosquito’s brain can rewrite that response based on experience. What the insect has learned matters just as much as what the chemical does. That, I think, is a paradigm shift.”

The findings do not mean people should stop using DEET, Vinauger says. It’s still one of the most effective repellents available, particularly in regions where mosquito-borne disease is common.

“If you’re in tropical regions where disease risk is real, you should use it,” he says.

But the study suggests timing and concentration may matter more than previously understood.

“Instead of applying a lot at once, you may want to reapply regularly so it’s always active and providing continuous protection,” Vinauger says.

He adds that treated clothing may also present challenges because DEET concentrations in fabric decline over time.

The study builds on years of mosquito learning and behavior research connected to Vinauger’s work. While pursuing his PhD in Lazzari’s lab in France, and later as a postdoctoral researcher at the University of Washington, Vinauger helped pioneer experiments showing mosquitoes can learn and remember odors associated with blood meals and defensive hosts.

At Virginia Tech, Vinauger’s lab studies how mosquitoes use sensory information to find hosts and adapt to changing environments. His team has shown that mosquitoes remember and avoid hosts who swat at them, combine smell and vision to track people with surprising precision, and gravitate toward and away from the smell of certain body soaps.

“Mosquitoes are remarkable at processing information about their environment,” Vinauger says. “What we are trying to understand is not only how they detect us, but how their brains interpret those cues and turn them into behavior.”

As Aedes aegypti expands into new regions and insecticide resistance grows worldwide, Vinauger says understanding mosquito behavior is becoming increasingly important for public health.

“We need to understand how mosquitoes keep outsmarting our control strategies,” Vinauger says. “And that takes understanding how they work—at the molecular level, the neural level, the behavioral level.”

Source: Virginia Tech

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Team finds protein that could help failing hearts recover

Researchers have identified a key protein that may help failing hearts regain function, offering new insight into why some hearts recover while others do not.

The discovery comes from studying patients treated with left ventricular assist devices, or LVADs, which are mechanical pumps that reduce strain on the heart and allow it to rest and recover.

While these devices can stabilize patients with advanced heart failure, only a subset experience meaningful recovery, and the biological reasons have remained unclear.

In a new study in the Journal of the American Heart Association, cardiovascular molecular researcher Junco Warren of Virginia Tech and cardiologist Stavros Drakos of the University of Utah found that a protein called PERM1 is fully restored in patients whose hearts recover after LVAD support. Patients who did not recover showed no such restoration.

The study brought together scientists at Virginia Tech’s Fralin Biomedical Research Institute at VTC and clinical collaborators at the University of Utah, combining molecular research with patient-based cardiac care.

Heart failure affects more than 6 million people in the United States, and predicting recovery remains a major challenge in care.

“This is the first muscle-specific molecular signal linked to recovery in human heart failure,” says Warren, assistant professor at the Fralin Biomedical Research Institute and co-corresponding author.

“We don’t yet know whether PERM1 drives recovery or reflects it, but it gives us a clear window into the biology of how recovery happens.”

The research team analyzed heart tissue from 19 patients, comparing samples collected before and after LVAD implantation. Patients were enrolled through the University of Utah cardiac transplant program, with tissue collected from the left ventricular apex during implantation and later during device removal or transplantation. Patients were categorized as responders or non-responders based on improvements in heart function.

Before treatment, PERM1 levels were reduced in all patients. After LVAD support, levels were restored to near-normal only in those whose hearts recovered, while remaining suppressed in non-responders.

“This study begins to explain why some patients recover heart function with LVAD support while others do not,” says Drakos, professor of cardiology at the University of Utah and co-corresponding author. “Identifying the biological signals behind recovery is essential to improving outcomes for patients with advanced heart failure.”

The findings showed a strong correlation between PERM1 levels and improved cardiac function. PERM1 regulates how heart cells produce and use energy, and recovery was associated with normalization of stress-related metabolic pathways.

Together, the results position PERM1 as both a potential biomarker and a target for future therapies.

“Current therapies help manage heart failure, but they do not repair the heart muscle itself,” says Warren, who is also an assistant professor in Virginia Tech’s human nutrition, foods, and exercise department in the College of Agriculture and Life Sciences.

“Our findings point to a pathway that directly targets cardiomyocytes—the heart muscle cells—and restores both energy production and contractile function, the two core deficits in heart failure.”

Previous work from Warren’s lab showed that increasing PERM1 improves heart function in experimental models. The approach has also been shown to prevent heart failure in preclinical studies and may support recovery in advanced disease, including in patients receiving mechanical heart support.

“Heart failure creates a vicious cycle where energy loss and reduced contraction reinforce each other,” Warren says. “PERM1 appears to act at the center of that cycle.”

While more research is needed to determine whether PERM1 directly causes recovery, the findings provide a step toward new treatment strategies.

To help advance these discoveries toward patient use, Warren and members of her research team have co-founded a company focused on developing PERM1-based gene therapies.

The study was supported by the National Institutes of Health, the American Heart Association, the US Department of Veterans Affairs, the Nora Eccles Treadwell Foundation, and internal funding from the Fralin Biomedical Research Institute.

Source: Virginia Tech

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2020 fire killed Joshua trees, but not fungi

When the Dome Fire tore through the Mojave Desert in 2020, it reduced one million Eastern Joshua trees to blackened skeletons. Scientists expected the underground ecosystem to be equally devastated. Instead, they found it thriving.

That unexpected outcome is detailed in the journal Fire Ecology, and it suggests that the loss of helpful soil fungi is likely not what is preventing Joshua tree recovery after the wildfire.

Joshua trees, like other trees, depend on mycorrhizal fungi that help their roots absorb water and nutrients from the soil. Earlier research shows Eastern Joshua trees in the Mojave’s Cima Dome area are hosts to diverse communities of these fungi, raising questions about whether the fire erased them from the soil, and whether that erasure is hindering the trees’ recovery, or just one part of a larger story.

“We thought the microbes would all be dead when we got there,” says UC Riverside fungal ecologist Sydney Glassman, senior author of the study. “The trees were devastated aboveground, and usually the soil story matches that kind of destruction.”

At first, there were hopes for a recovery. In the days after the lightning-generated, 43,000-acre fire, a majority of the Joshua trees still had some green leaves. After a year, survivorship dropped to 50%. At the three-year mark, only 20% of trees in the burn plots were still alive.

And the appearance of the burn scar changed during the post-fire years in ways that made for a strange landscape. The dead Joshua trees became covered in a fire-loving, bright colored fungus called Neurospora discreta.

The researchers believe much of the delayed reaction to the fire was likely due to compound stresses, including drought.

“The trees were already mortally wounded, then drought and rodents helped finish them off,” says UCR research ecologist and paper coauthor Lynn Sweet.

Wondering if the fire might have caused a similar delayed reaction below ground, the researchers repeatedly sampled both burned and unburned soils from just over two weeks after the fire through three years later. They found no detectable declines in fungal biomass, microbial richness, or the overall abundance of bacteria and fungi. In some cases, mycorrhizal fungal and bacterial diversity increased slightly after the fire.

“The existing community of microbes stayed, and some fire specialists even joined the party,” Glassman says.

While in some cases fires can devastate underground microbial life for years or even decades, the researchers think that in this case it was different because the Joshua trees and the other herbs and shrubs in this Mojave area were spread relatively far apart. This likely limited heat penetration into the soil, sparing much of the underground ecosystem even as the visible landscape transformed.

The study findings carry important implications for restoration efforts, which will likely be arduous. Joshua trees grow slowly, and small desert herbivores often eat seedlings in landscapes where other plant life has burned away.

However, because fungi remained in place, the study suggests that conservation efforts should not require costly soil amendments to replace missing mycorrhizal partners.

“There is no evidence the fungi are limiting regeneration because they didn’t disappear,” Glassman says. ‘If the trees can figure out how to survive, the microbes are there for them.”

Source: UC Riverside

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Depression screening tool works for people with chronic pain

A new study found that a widely used depression screening questionnaire is accurate for people with and without chronic pain,

The finding debunks a common misconception that the screening inflates depression scores for people with chronic pain.

Some clinicians and researchers believed a person with chronic pain might score higher on the eight-item Patient Health Questionnaire, or PHQ-8, because they can’t sleep or experience fatigue, which are symptoms of both pain and depression.

“Could pain symptoms artificially inflate depression screening scores among those with chronic pain? It’s a reasonable question, but it had not yet been definitively answered,” says lead author Jennifer S. De La Rosa, strategy director for the University of Arizona Comprehensive Center for Pain and Addiction and an assistant research professor in the U of A College of Medicine–Tucson’s family and community medicine department.

“Using nationally representative population data, we rigorously evaluated this question and found no evidence to support this long-standing concern.”

The paper appears in the Journal of Affective Disorders.

De La Rosa and her team analyzed data from nearly 32,000 US adults who participated in the 2019 National Health Interview Survey. The team used sophisticated data science techniques to assess measurement invariance—ensuring there was no bias—in the PHQ-8 questionnaire.

When comparing the variance of scores for people with or without chronic pain, the data showed that the screener achieved an excellent level of consistency in both groups.

“Clinicians need to know that a positive depression screening is just as reliable in their patients with chronic pain as patients without chronic pain, and they should not hesitate to offer mental health supports to any patient with unmet mental health needs,” De La Rosa says.

“These conversations require sensitivity to ensure patients feel supported by these conversations rather than stigmatized.

“Right now, there’s a national push underway to address treatment-resistant depression, yet for the vast majority of clinical trials, people with chronic pain are excluded from participating,” De La Rosa adds.

“This study provides robust evidence that there would be no scientific problem with including folks living with chronic pain in depression research to help develop treatments capable of meeting the needs of this uniquely underserved population.”

The research underscored the way chronic pain and depression are intertwined, reinforcing De La Rosa’s previous research, which found that while 1 in 5 people with chronic pain have depression, more than half of those with clinically significant depression symptoms also have chronic pain.

A follow-up paper showed that adults with chronic pain are more likely to experience anxiety and depression than those without chronic pain, yet they access mental health care at lower rates and are less likely to have their mental health needs met in treatment.

“People with chronic pain are, in fact, the most typical patients living with unmet mental health needs, and they are wildly overrepresented among people with treatment resistant depression,” De La Rosa says.

“Many of them want to participate in trials. They can benefit just as much as others from inclusion, and, critically, it will improve the real-world effectiveness of the new therapies being developed.

“Now is the time to meaningfully consider the unmet mental health needs of people with chronic pain and prioritize their outcomes within the mental health research, policy and advocacy landscape,” she adds.

In 2023, approximately 64 million US adults experienced chronic pain, according to the Centers for Disease Control and Prevention.

Additional coauthors are from the University of Arizona, Arizona State University, and Johns Hopkins School of Medicine.

The study received support from the National Institutes of Health.

Source: University of Arizona

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Drought in the southwest is shrinking wildlife habitat

As people in the United States are coping with historic drought conditions, the country’s wildlife is also facing problems because of the extreme aridity.

Herbivores, omnivores, and carnivores in the southwestern US have all seen the extent of their suitable habitat shrink due to drought, according to a new study.

“The take-home message is that the effects of drought are huge and widespread. These results aren’t just from one small study system,” says Kirby Mills, a lead author of the new study in the journal Communications Earth and Environment.

Mills, now with the Institute for Wildlife Studies in California, helped lead the work as a postdoctoral researcher at the University of Michigan Institute for Global Change Biology.

The study analyzed 12 years worth of data collected by GPS collars worn by mule deer, black bears, and cougars—herbivores, omnivores, and carnivores, respectively—in Nevada and Utah (currently, Utah is one of nine states completely covered by some level of drought). During severe drought conditions, each species saw at least a 10% reduction in the area of highly selected, or highly suitable, habitat.

“We found that drought was negatively impacting life across Utah and Nevada statewide for species that have very different ecologies,” Mills says.

“We just looked at these three large mammals, but drought is probably affecting all the wildlife living in this region and could threaten their persistence into the future if droughts get worse.”

The study, which was supported by federal funding from NASA, also showed that, under extreme drought, the number of new fawn mule deer per doe can decline by more than 30%.

“What we’re seeing is that drought is having a major impact not just on habitat suitability, but also on fitness, on the survival of wildlife,” says Martin Leclerc, who co-led the study as a postdoctoral researcher at the UM School for Environment and Sustainability, or SEAS. Leclerc is now an assistant professor at the University of Quebec at Chicoutimi.

In quantifying the impact of drought conditions in the southwest, which are becoming more intense and frequent on a warming planet, the study underscores how entwined climate and conservation are, the authors say.

“The study highlights the growing intersection of climate patterns, including drought and wildfire, with landscape planning and management, natural resource management, vegetation dynamics, wildlife behavior, and management—all of these things that are often looked at separately,” says Neil Carter, associate professor at SEAS and a senior author of the study.

“Now we’re finding that they’re enmeshed so tightly and that demands different management strategies moving forward.”

The team’s analysis included information from more than 3,000 animals across a nearly 200,000-square-mile range between 2010 and 2022, resulting in what Leclerc described as a “painfully massive” amount of data.

The team credited David Stoner, another senior author and associate professor at Utah State University, for knowing where to look and who to contact to collect the data from many separate sources. In bringing all that information together, the researchers could dig into how much area each species inhabited as drought conditions changed over time and space.

“The study really shows the value and importance of long-term datasets, especially for big questions related to climate change,” Leclerc says.

The team’s analysis revealed that, when it came to habitat reduction, the impact of drought amplified from prey to predators. In severe drought, mule deer saw reductions of 10% in their highly selected habitat, compared with 14% for black bears and 18% for cougars.

Initially, the numbers were surprising. As drought conditions kill vegetation, the researchers anticipated that could have had the greatest impact on the herbivorous deer. But the team does have an explanation for how the opposite is true.

“Cougars can’t just go and chomp on whatever they find that’s green like deer can,” Mills says. “That means cougars have to work harder for their food and they’re more limited in their opportunities to find food, so their populations can be more sensitive to perturbations.”

Furthermore, population densities tend to decrease as you move up the food web—for example, the study included more than 2,800 mule deer and 105 cougars. So cougars may not only be more sensitive to the impacts of drought, but impacts on individual cougars are going to be felt more at a community level. While this amplification makes cougars and other predators more vulnerable than one might expect, it could also create new opportunities in conservation.

“People are typically managing deer populations, not deer and cougar simultaneously, so I think there will start to be more conversation and communication around that,” Carter says.

And such broader conversations could benefit wildlife writ large.

“There’s pretty robust planning going on for mitigating human vulnerability to climate change, but we don’t have the same level of planning for mitigating wildlife vulnerability,” Carter says.

“I certainly think there are opportunities to bring those together.”

Source: University of Michigan

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Armadillos inspire new tech to protect soft machines

Researchers have drawn inspiration from armadillos to create a protective structure that responds to external threats by curling into a protective ball to protect electronic devices or other payloads.

The structure is designed to automatically respond when it detects strain and can be tuned to respond to anything from a delicate touch to a significant impact.

“There has been a great deal of growth in the fields of soft robotics and flexible electronics, but those devices are often also fragile,” says Yong Zhu, corresponding author of a paper on the work and a professor of mechanical and aerospace engineering at North Carolina State University.

“Our goal was to develop a solution that allows these fragile technologies to function but protects them when necessary.”

“In its relaxed state, the structure we’ve developed is fairly flexible, but it can be activated to curve into a rigid external structure,” says Jianyu Zhou, first author of the paper and a postdoctoral researcher at NC State.

“We could see this technology being used to protect many types of objects—essentially anything it is capable of curving around.”

The robo-armadillo, which the researchers call the morpho-interlocking protective module (MIPM), consists of three general layers:

1. The outer layer, or exoskeleton, consists of a series of segmented, curved scales which are made from a 3D printed resin.
2. The middle, “sensing and actuation” layer, consists of four parts: a liquid-crystal elastomer (LCE), that contracts when heated; a strain sensor made of elastic polymer embedded with silver nanowires; a layer of kapton tape that expands when heated; and then a thin layer of conductive fabric that serves as a “heater” layer.
3. Lastly, there is an endoskeleton layer that consists of heavy-duty paper folded into a series of ridges, which hold a row of rigid polymer “segmental scales” in place.

When the strain sensor detects a touch or impact it signals a control unit, which then sends power to the heater layer. As the heater layer warms up, it causes the LCE layer to contract and the kapton tape layer to expand, causing the entire structure to curve. The end result is that the MIPM structure curls into a protective circle with the exoskeleton facing out.

“As the layers curve into a circle, the segmental scales in the MIPM’s endoskeleton lock into each other—creating a robust internal ‘skeleton’ that contributes to the sturdiness of the structure,” says Zhou.

In proof-of-concept testing, the researchers found the MIPM works as intended, with the sensor layer detecting increased strain and triggering the transformation into a protective shell. The researchers also found that increasing the number of segmental scales in the endoskeleton significantly improves the structure’s internal rigidity and strength.

“Through mechanics-guided design, we established a trade-off between endoskeleton segmentation and structural lightweighting,” says Zhu. “As an example, 10 segmental scales were capable of withstanding around 10 newtons of force.

“We’ve demonstrated a combination of flexibility and mechanical protection that has a lot of potential, and we welcome collaborations from those who are interested in exploring possible applications,” says Zhu.

“We’re also very interested in pursuing additional opportunities to advance work on flexible yet protective technologies that draw on nature for inspiration.”

The paper appears in the journal Science Advances.

This work was done with support from the National Science Foundation and the Department of Defense.

Source: North Carolina State University

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AI shows how your brain cleans out harmful waste

A new approach combines MRI scans and AI tools to measure fluid flow linked to diseases such as Alzheimer’s.

When a person goes into deep sleep, water-like fluid circulates around the brain, washing away metabolic waste linked to diseases such as Alzheimer’s.

This process, known as the glymphatic system, was first described in 2012 by Maiken Nedergaard—a pioneering neuroscientist and codirector of the University of Rochester’s Center for Translational Neuromedicine.

But questions remain about the system’s mechanics—notably, how quickly the fluid circulates. Studying the circulation within a living brain is difficult without causing irreparable harm to a subject.

“You can put a microscope on a small patch of the brain and watch what’s happening there with a lot of detail, and we’ve worked with that type of data in the past, but it’s only a tiny view of the overall process,” says Professor Douglas Kelley from URochester’s mechanical engineering department.

“If you want to image whole brains, an MRI is a great approach because it gives you a three-dimensional view. But an MRI has serious limitations, too, the biggest of which is that it does not capture the fluid flow velocity, at least not for flows this slow.”

Kelley and his colleagues turned to artificial intelligence for help.

In a new study in Science Advances, they outline how they used physics-informed AI to determine fluid flow velocities from magnetic resonance imaging (MRI) data. Using videos of dye spreading across brain tissue over time, the neural networks the researchers built were able to deduce how fast the fluid flows and how permeable the brain tissue is.

The results showed that there are two main ways that the glymphatic system washes away particles in the brain such as the amyloid beta proteins linked to Alzheimer’s disease—and one of these ways is much faster than the other.

The fast flow of the glymphatic system’s waterlike fluid moves at a few microns per second around the brain’s open regions such as the surface between the skull and the brain, while the slower flow of the waterlike fluid trickles through the brain’s deep tissue at a rate about 50 times slower.

So far, the researchers have been working to get baseline measurements of fluid flow in the brains of animals such as mice to inform the AI tools. In the future, they hope to be able to compare the fluid flow in healthy and sick brains as well as young and old brains, with aspirations to eventually study circulation in humans.

“We’re working hard toward being able to measure the flow of waterlike fluids in and around human brains because then the clinical applications get a lot more important and exciting,” says Kelley.

“We hope to someday be able to see whether an Alzheimer’s patient has poor circulation in their brain or even screen for poor circulation earlier in life to try to stave off Alzheimer’s. Or we could check when somebody has been concussed to see whether the fluid circulation in their brain is disrupted. This study gets us a step closer.”

Additional collaborators on the study are from Brown University, URochester, and University of Copenhagen.

The NIH National Center for Complementary and Integrative Health and the NIH BRAIN Initiative supported this research.

Source: University of Rochester

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