Culture

For people with tooth decay, drinking a cold beverage can be agony.

"It's a unique kind of pain," says David Clapham, vice president and chief scientific officer of the Howard Hughes Medical Institute (HHMI). "It's just excruciating."

Now, he and an international team of scientists have figured out how teeth sense the cold and pinpointed the molecular and cellular players involved. In both mice and humans, tooth cells called odontoblasts contain cold-sensitive proteins that detect temperature drops, the team reports March 26, 2021, in the journal Science Advances. Signals from these cells can ultimately trigger a jolt of pain to the brain.

The work offers an explanation for how one age-old home remedy eases toothaches. The main ingredient in clove oil, which has been used for centuries in dentistry, contains a chemical that blocks the "cold sensor"protein, says electrophysiologist Katharina Zimmermann, who led the work at Friedrich-Alexander University Erlangen-Nürnberg in Germany.

Developing drugs that target this sensor even more specifically could potentially eliminate tooth sensitivity to cold, Zimmermann says. "Once you have a molecule to target, there is a possibility of treatment."

Mystery channel

Teeth decay when films of bacteria and acid eat away at the enamel, the hard, whitish covering of teeth. As enamel erodes, pits called cavities form. Roughly 2.4 billion people - about a third of the world's population - have untreated cavities in permanent teeth, which can cause intense pain, including extreme cold sensitivity.

No one really knew how teeth sensed the cold, though scientists had proposed one main theory. Tiny canals inside the teeth contain fluid that moves when the temperature changes. Somehow, nerves can sense the direction of this movement, which signals whether a tooth is hot or cold, some researchers have suggested.

"We can't rule this theory out," but there wasn't any direct evidence for it, says Clapham a neurobiologist at HHMI's Janelia Research Campus. Fluid movement in teeth - and tooth biology in general - is difficult to study. Scientists have to cut through the enamel - the hardest substance in the human body - and another tough layer called dentin, all without pulverizing the tooth's soft pulp and the blood vessels and nerves within it. Sometimes, the whole tooth "will just fall to pieces," Zimmermann says.

Zimmerman, Clapham, and their colleagues didn't set out to study teeth. Their work focused primarily on ion channels, pores in cells' membranes that act like molecular gates. After detecting a signal - a chemical message or temperature change, for example - the channels either clamp shut or open wide and let ions flood into the cell. This creates an electrical pulse that zips from cell to cell. It's a rapid way to send information, and crucial in the brain, heart, and other tissues.

About fifteen years ago, when Zimmermann was a postdoc in Clapham's lab, the team discovered that an ion channel called TRPC5 was highly sensitive to the cold. But the team didn't know where in the body TRPC5's cold-sensing ability came into play. It wasn't the skin, they found. Mice that lacked the ion channel could still sense the cold, the team reported in 2011 in the journal Proceedings of the National Academy of Sciences.

After that, "we hit a dead end," Zimmermann says. The team was sitting at lunch one day discussing the problem when the idea finally hit. "David said, 'Well, what other tissues in the body sense the cold?' Zimmermann recalls. The answer was teeth.

The whole tooth

TRPC5 does reside in teeth - and more so in teeth with cavities, study coauthor Jochen Lennerz, a pathologist from Massachusetts General Hospital, discovered after examining specimens from human adults.

A novel experimental set up in mice convinced the researchers that TRPC5 indeed functions as a cold sensor. Instead of cracking a tooth open and solely examining its cells in a dish, Zimmermann's team looked at the whole system: jawbone, teeth, and tooth nerves. The team recorded neural activity as an ice-cold solution touched the tooth. In normal mice, this frigid dip sparked nerve activity, indicating the tooth was sensing the cold. Not so in mice lacking TRPC5 or in teeth treated with a chemical that blocked the ion channel. That was a key clue that the ion channel could detect cold, Zimmermann says. One other ion channel the team studied, TRPA1, also seemed to play a role.

The team traced TRPC5's location to a specific cell type, the odontoblast, that resides between the pulp and the dentin. When someone with a a dentin-exposed tooth bites down on a popsicle, for example, those TRPC5-packed cells pick up on the cold sensation and an "ow!" signal speeds to the brain.

That sharp sensation hasn't been as extensively studied as other areas of science, Clapham says. Tooth pain may not be considered a trendy subject, he says, "but it is important and it affects a lot of people."

Zimmermann points out that the team's journey towards this discovery spanned more than a decade. Figuring out the function of particular molecules and cells is difficult, she says. "And good research can take a long time."

Water scarcity is often understood as a problem for regions experiencing drought, but a new study led by Tufts University researchers finds that not only can localized water shortages impact the global economy, but changes in global demand can have positive and negative ripple effects in river basins across the globe.

In addition to Tufts engineers, the team included experts from the Joint Global Change Research Institute at the Pacific Northwest National Laboratory, and Cornell University.

"We're finding that water scarcity dynamics are more complicated than traditionally acknowledged," said Flannery Dolan, a graduate student at Tufts University and lead author of the study. "Changing water supply due to climate change is only part of the story. Regional water scarcity is also driven by changes in global water demands that are often hard to anticipate."

The study, "Evaluating the economic impact of water scarcity in a changing world," was published March 26 in Nature Communications, and uniquely captures the interdependent effects of global trade, population and technological growth, climate change, and land management decisions on regional river basins' water scarcity and economic capacity to adapt to that scarcity.

The researchers used a computer model to simulate thousands of scenarios that reflect a broad array of potential climate, socioeconomic, and hydrologic (earth water cycles and management) conditions in 235 major river basins to better understand how regional water scarcity can have far-ranging impacts on the global economy. Those effects can include altering global trade and consumption patterns in industries such as agriculture, energy, transportation, and manufacturing.

"We are looking at water scarcity as a globally connected and multi-sector phenomenon," said Jonathan Lamontagne, assistant professor of Civil and Environmental Engineering at Tufts University and corresponding author of the study. "As a result, the study reveals some interesting and sometimes unexpected insights into how local conditions can have reverberations across the globe."

The research found that global trade dynamics and market adaptations to regional water scarcity can result in positive or negative economic outcomes in every regional river basin considered in the study, depending on both water supply (rainfall, snowmelt, and ground water), and demand-side factors like agricultural production, power generation, and municipal use.

For instance, in the lower Colorado River basin, the worst economic outcomes arise from limited groundwater availability and high population growth, but that high population growth can also prove beneficial under some hydrologic conditions. In contrast, the future economic outcomes in the Indus Basin depend largely on global land-use policies that discourage carbon emissions that can, in turn, encourage overuse of groundwater supplies.

"What is happening elsewhere in the world through differences in regional choices related to energy transitions, how land is being managed, as well as different regional water demands and adaptive choices, can shape relative advantages and disadvantages of a region's water intensive economic activities," said Patrick Reed, the Joseph C. Ford Professor of Civil and Environmental Engineering at Cornell.

Restrictions in water availability usually lead to a negative regional economic impact, but the research revealed that some regions can experience a positive economic impact if they hold an advantage over other water basins and become a virtual exporter of water. The Orinoco basin in Venezuela, for example, usually has a reliable supply of water and is often in a relative position that can benefit when other regions are under stress, according to the researchers.

The study also found that small differences in projections for future climate conditions can yield very large differences in the economic outcomes for water scarcity.

"Human activities and market responses can strongly amplify the economic effects of water scarcity, but the conditions that lead to this amplification vary widely from one basin to the next," said Lamontagne.

A river basin can be considered economically robust if it is able to adapt to drought with alternative sources of water or adjust economic activity to limit usage. If a basin is unable to adapt its supply options and if prolonged water scarcity leads to persistent economic decline, then the researchers describe the loss in water basin adaptive capacity as having reached an 'economic tipping point.'

For example, in the Indus region in South Asia, the water supply is under stress due to heavy agricultural use and irrigation leading to unsustainable consumption of groundwater, which places it close to the tipping point.

The conditions that lead to these tipping points are highly variable from basin to basin, depending on a combination of local factors and global conditions. In the Arabian Peninsula, low groundwater availability and pricing of carbon emissions are key factors. In the lower Colorado River basin, a mixture of low groundwater availability, low agricultural productivity, and strong economic demands from the U.S. and Europe lead to tipping points.

"It is noteworthy that the lower Colorado River basin has some of the most uncertain and widely divergent economic outcomes of water scarcity of the basins analyzed in this study," said Reed. "This implies that assumed differences in regional, national and global human activities as well as the intensity of climate change can dramatically amplify the uncertainty in the basin's outcomes."

As climate change makes the physical and economic effects of water scarcity more challenging for policy makers to understand, the researchers hope their work will provide the basis for similar analyses and draw attention to the importance of expanded data collection to improve modeling and decision making.

What The Study Did: Insurance claims were used to assess patterns of telehealth use across surgical specialties before and during the COVID-19 pandemic.

Authors: Grace F.Chao, M.D., M.Sc., of the National Clinician Scholars Program at the University of Michigan and Veterans Affairs Ann Arbor in Michigan, is the corresponding author.

To access the embargoed study: Visit our For The Media website at this link https://media.jamanetwork.com/

(doi:10.1001/jamasurg.2021.0979)

Editor's Note: The article includes conflict of interest and funding/support disclosures. Please see the article for additional information, including other authors, author contributions and affiliations, conflict of interest and financial disclosures, and funding and support.

Scientists have developed a method to use lasers to control the movement of nanodiamonds with fluorescent centers.

Scientists have long been working on improving their ability to use lasers to move small objects without actually touching them. This method of 'optical trapping and manipulation' is already utilized in optics, biological sciences and chemistry. But objects become much more difficult to control once they grow to nanoscale size.

Now, a team of scientists including Hokkaido University's Keiji Sasaki and Osaka Prefecture University and Osaka University's Hajime Ishihara have found a way to move diamond nanoparticles of about 50 nanometres in diameter, using opposing lasers. Their experiments, published in the journal Science Advances, aim to further research into the development of applications in fields like biological imaging and quantum computing.

"We believe our approach can enable a new class of optical force methodologies to investigate the characteristics of advanced nanomaterials and quantum materials and to develop state-of-the-art nanodevices," says Sasaki.

Nanodiamonds have carbon atom lattices that sometimes contain an imperfection in which two neighbouring carbon atoms are replaced with a nitrogen atom and a vacancy (fluorescent center), which affect their quantum mechanical properties; nanoparticles react to light differently depending on their quantum mechanical property. Nanodiamonds with this fluorescent center (resonant nanodiamonds) absorb green light and emit red fluorescence and are being investigated for applications in biological imaging, sensing and single-photon sources. Nanodiamonds without fluorescent centers are non-resonant.

Sasaki and his colleagues soaked an optical nanofiber in solutions of nanodiamonds with and without fluorescent centers. Shining a green laser through one end of the nanofiber trapped a single nanodiamond with fluorescent centres and transported it away from the laser.

The scientists demonstrated that, when a green and a red laser were shone on the nanodiamonds from opposite sides of the optical nanofiber, the movement of resonant and non-resonant nanodiamonds could be independently controlled: For the non-resonant nanodiamonds, the red laser pushes them more strongly than the green laser; however, the resonant ones absorb the red laser light and are hence pushed more strongly by the green laser. Thus, they could be sorted based on their optical properties. Furthermore, the number of fluorescent centers in the resonant nanodiamonds could be quantified by observing their movements under these conditions.

By using this technique to trap and manipulate nanodiamonds, the scientists have demonstrated a proof of concept. Their next step would be to apply it to organic dye-doped nanoparticles, which can be used as nanoprobes in biodetection systems.

Leesburg, VA, March 26, 2021--According to ARRS' American Journal of Roentgenology (AJR), updated United States Preventive Services Task Force (USPSTF) lung cancer screening (LCS) guidelines based solely on age, pack-years, and quit-years perpetuate eligibility disparities among racial and ethnic minorities, although incorporating certain risk prediction models may help reduce such inequalities.

By pulling data from the 2015 National Health Interview Survey (NHIS), Journal of the National Cancer Institute researchers (Landy et al.) were able to "estimate the effects of USPSTF-2020 guidelines on disparities in LCS eligibility for the non-institutionalized civilian US population," wrote Massachusetts General Hospital radiologists Efrén J. Flores and Anand K. Narayan in their AJR critique. In connecting this NHIS dataset to the National Death Index, the original researchers were able to not only estimate eligibility but also model any possible effects of guideline changes on preventable lung cancer deaths.

"However," Flores and Narayan contended, "by modeling the effects of changes instead of measuring actual outcomes, the authors' conclusions that LCS disparities can be nearly eliminated by using alternative eligibility criteria reflects an aspirational goal." In fact, updated criteria must be used alongside outreach efforts to ensure equitable access and appropriate follow-up.

To define eligibility based on individual risk as well as life expectancy, Landy et al. used the Life-Years From Screening-CT (LYFS-CT) model, despite the fact that life expectancy may limit access for minorities who have shorter life expectancies. Moreover, the initial investigators assumed that LCS would reduce lung cancer mortality by 20% for all racial and ethnic groups, even though previous studies have suggested that minorities may experience greater reductions in lung cancer mortality from LCS.

Ultimately, because LYFS-CT may exclude minority patients who could benefit from LCS and underestimate the benefits of LCS, the authors of this AJR article suggested "augmenting LCS eligibility for minority patients using combinations of models"--specifically, the PLCOm2012 model in conjunction with LYFS-CT and USPSTF-2020.

Every year, millions of people around the world are displaced from their homes due to severe weather caused by climate change. According to the International Red Cross and Red Crescent Movement, 10.3 million people were displaced as a result of climate-?related events in the last six months alone - four times the number displaced by war and conflict in the same period. One of the main causes of displacement is flooding. A recent example is the situation in eastern Australia, where tens of thousands of people are having to flee their homes to seek safety from this hundred-?year flood.

An international research team led by the Weather and Climate Risks Group at ETH Zurich has just published a new study aimed at providing a better understanding of future displacement risks due to flooding from rivers overflowing their banks. Their study also evaluates the influence of climate change as well as demographic and socioeconomic factors on these risks.

Population growth greatly increases risk

Using a variety of climate, hydrology and population distribution models, the researchers show that if the population remains stable at its current level, the risk of flood-?related displacement increases by more than 50 percent (relative to 2010 levels) for each degree of global warming.

However, the world's population is growing. Even if this growth continues towards a more sustainable path, the risk of displacement will still increase significantly: assuming that the world meets the Paris Agreement's goal of limiting global warming to a maximum of 2° Celsius, the globally averaged risk is projected to rise by up to 110 percent by the end of this century.

However, under "business as usual" climate-?change conditions and if the gap between rich and poor continues to widen, the risk is projected to increase even more dramatically. For this scenario, the researchers calculated that the risk of displacement due to flooding would be up to 350 percent higher.

Rapid action needed

According to the study's authors, it is not yet too late to address and manage the risk of flood displacement through spatial and urban planning measures and protective infrastructure such as dams. "Our findings highlight the need for rapid action on both climate mitigation and adaptation agendas in order to reduce future risks, especially to vulnerable populations," says Pui Man Kam, lead author of the study and doctoral student in ETH Professor David N. Bresch's group. "Floods often affect the most socio-?economically vulnerable groups, who tend to live in more hazard-?prone areas," she explains.

To conduct their study, the researchers used a global climate-?, hydrology-? and inundation-?modelling chain to quantify the effect of global warming on displacement risk for both current and projected future population distributions. The study has just been published in the journal Environmental Research Letters.

"Because floods are a major driver of displacement and due to the fact that they are influenced by climate change, it is imperative that we have a better understanding of how the risks are changing," Kam says.

Apple flies have fascinated scientists right from the mid-19th century, as they are a captivating example of speciation, the beginning of a new species. Correspondence between Charles Darwin and Benjamin Walsh, who observed the apple flies and hawthorn flies in North America, began the rich history of this scientific question in evolutionary biology. When settlers in North America introduced apple trees to the region, what happened within the hawthorn flies to make them shift to this new host plant in the last 300 years?

Continuing the 160-year-old inquiry into the origins of the apple fly, a team of scientists from around the world has just published their research in the Proceedings of the Royal Society B. The researchers span three continents, from the National Centre for Biological Sciences, the University of Trans-Disciplinary Health Sciences and Technology, the University of Notre Dame, Free University Berlin, and Max Planck Institute for Chemical Ecology. They have been probing the neurological processes which underlie important behavioural changes in the apple fly: preference toward a new host plant and mate choice. These behavioural changes contributed to a rapid shift from hawthorn flies into a derived race of apple-infesting flies.

Hawthorn flies and apple flies are specialist insects, they feed only on a particular fruit, either the hawthorn berries or ripe apples. They also mate on or near the fruit and lay their eggs within it. What is interesting about the apple and hawthorn flies is that each generation emerges with a specific preference for the odour of ripe fruit that they use to locate their host and a strong aversion to the odour of the other fruit. What makes these two races of flies distinct?

Using recordings of electrical activity and imaging the brains of the flies, the team identified that both apple and hawthorn flies use the same brain regions to process odours, but switch the locations of processing. In other words, where apple flies process the main apple odour (butyl hexanoate) is the same location in the brain where hawthorn flies process the major hawthorn odour (3-methyl-1-butanol), and vice versa. Thus, the locations for preference and aversion to fruit odours stay the same, while the odours that are processed there are inverted.

The scientists were able to locate the specific point where this difference emerges. It is at the very first synapse in the olfactory system, called the antennal lobe. "The most surprising part to me was actually seeing olfactory processing be so clearly different between the apple and hawthorn infesting host races. We knew these flies have divergent odour preference behaviours and patterns of genetic differentiation. Now, from this work we know their sensory neurophysiology differs as well,' says Cheyenne Tait, the first author of the study.

It is possible that a simple shift in the processing of important sensory information might be a major contributor to the diverse species we see. "We are seeing the stuff of speciation. The origin of new species is one of the great questions that has piqued the intellectual curiosity of humankind. Resolving the question of speciation is of great scientific importance and the ongoing evolution of apple and hawthorn host races of Rhagoletis is connected to life itself, or the origin of new life forms," says Jeffrey L. Feder, an expert in evolutionary biology and one of the scientists involved in the study.

Through the change in the neurological processing of the fruit odor, a change at a species scale can be triggered. Shannon Olsson explains her fascination with the flies, "What is most remarkable to me is the simplicity of the switch - these flies simply changed their minds along with their species. Such a subtle shift in the processing of important sensory information in the brain could be contributing to the change in behaviour that helps drive their evolution into new species."

This is not simply a question of the past, or the evolutionary history of one species, "This discovery has important implications for how animals such as insects can quickly adapt and change their behaviour to new environments, such as with invasive species, or respond to human-influenced changes in climate or land use," adds Shannon. Many subfields of biology came together for this study to understand more about these two flies. There is more to discover as scientists tackle evolution from new perspectives and with exciting advances in technology that can be used to study these questions.

A new catalyst for the conversion of carbon dioxide (CO2) into chemicals or fuels has been developed by researchers at Ruhr-Universität Bochum and the University of Duisburg-Essen. They optimized already available copper catalysts to improve their selectivity and long-term stability. The results are described by the team led by Dr. Yanfang Song and Professor Wolfgang Schuhmann of the Bochum Center for Electrochemistry with the team led by Professor Corina Andronescu of the Duisburg-Essen Technical Chemistry III group in the journal Angewandte Chemie, published online on 9 February 2021.

Boron makes copper catalyst stable

The climate gas CO2 can be converted into larger carbon compounds that can be used as base chemicals for industry or as fuels. Researchers are pursuing the idea of converting CO2 electrochemically with the help of renewable energies. This would not only create useful products; they would also serve as storage for the renewable energies. Copper has already emerged as a promising catalyst in previous studies, but it must be in the form of a partially positively charged ion - and that is precisely the problem.

Under conventional reaction conditions, copper is rapidly converted from its positively charged form to the neutral state, which is unfavorable for the formation of products with more than two carbon atoms and thus deactivates the catalyst.

The team from Bochum and Duisburg-Essen therefore modified a copper catalyst with boron. The researchers tested different copper-boron ratios and determined the optimal composition to favor the formation of compounds with more than two carbon atoms. They also showed that the boron-copper catalyst can be operated at current densities that would be required on an industrial scale.

Zinc prevents corrosion damage

They implemented the system in the form of a gas diffusion electrode in which a solid catalyst catalyzes the electrochemical reaction between the liquid and gaseous phases. It is important that sufficient CO2 dissolves in the boundary region between the gas and liquid phases. The scientists succeeded in doing this by using a special binder.

Another challenge is to keep the system stable over a long period of time. For example, corrosion of the electrodes must be prevented. To this end, the chemists integrated a so-called sacrificial anode made of zinc into the system. Since zinc is a less noble metal than copper, this is corroded first, while the copper is spared.

"The combination of a selective and active catalyst material in a gas diffusion electrode and the addition of the stabilizing zinc is an important step towards the use of CO2 for the synthesis of base chemicals," sums up Wolfgang Schuhmann.

Current approaches to a common and debilitating knee injury that occurs more frequently for women than men have focused for too long on biology at the expense of understanding social factors, say the authors of a new paper in the British Journal of Sports Medicine (BJSM).

Girls and women are said to be between three to six times more likely to suffer an anterior cruciate ligament (ACL) injury, where one of the key ligaments that helps to stabilise the knee joint is damaged. The devastating injury, which in extreme cases can be career ending for professional sportspeople, commonly occurs during sports that involve sudden changes in direction (e.g. basketball, football / soccer, tennis).

The difference in injury rates for men and women has not changed for two decades, but, say the authors, this might be partly due to how injury prevention and management has been approached to date. Writing in the BJSM they argue that much of the focus still centres on biological and hormonal factors, with little attention paid to how sex-based factors are affected by gender and might influence each other.

They suggest that gendered experiences matter in shaping girls' and women's participation in sport as well as disparities in injury outcomes. They demonstrate how this could play out across the lifecourse with gendered expectations of physical abilities (e.g. 'throw like a girl'), to inequitable access to funding, training, and facilities for women's sport (e.g. disparities in access to weight training).

Finally, they suggest there may be a difference between post-injury rehabilitation for men and women recovering from an ACL injury. They say that these social and environmental factors play a much bigger role in how sports injuries occur than once thought, and urge that much more attention be given to these topics.

Dr Sheree Bekker from the Department for Health at the University of Bath (UK) explains: "We wanted to unpack the biases and assumptions that we were seeing in research into and practice around sports injuries in girls and women. Specifically, we wanted to challenge the increasingly pervasive idea that this is simply a problem for girls/women because they are inherently prone to injury just because of their female biology. Approaching ACL injury prevention and management from a strictly biological view can propagate sexism in sport with detrimental consequences for girls and women."

Dr Joanne Parsons from the University of Manitoba (Canada) adds: "Over 20 years of research focussed on biological traits has failed to decrease the ACL injury rate in girls and women. To make a difference, we need to approach the problem in a different way. The recent challenges that the NCAA women's teams faced with access to adequate training equipment is a perfect example of why we have to include society's influence when talking about injury risk for girls/women."

The NCAA represents the National Collegiate Athletic Association - a non-profit that regulates student athletes from over 1,000 North American institutions whilst also organising athletic programmes reaching nearly 500,000 college student-athletes.

Co-author on the paper Dr Stephanie Coen of the University of Nottingham said: "By extending the focus from individual bodies and biology to the gendered environments contextualising ACL injury, our approach identifies new opportunities to intervene and achieve better outcomes for girls and women, with implications beyond athletes. As childhood and youth physical activity levels influence those in adulthood, the sequelae of ACL injury can be lifelong and particularly concerning for girls and women who already participate in physical activity at lower rates than boys and men. There is a wider health equity issue at stake."

When the brain suffers injury or infection, glial cells surrounding the affected site act to preserve the brain's sensitive nerve cells and prevent excessive damage. A team of researchers from Charité - Universitätsmedizin Berlin have been able to demonstrate the important role played by the reorganization of the structural and membrane elements of glial cells. The researchers' findings, which have been published in Nature Communications*, shed light on a new neuroprotective mechanism which the brain could use to actively control damage following neurological injury or disease.

The nervous system lacks the ability to regenerate nerve cells and is therefore particularly vulnerable to injury. Following brain injury or infection, various cells have to work together in a coordinated manner in order to limit damage and enable recovery. 'Astrocytes', the most common type of glial cell found in the central nervous system, play a key role in the protection of surrounding tissues. They form part of a defense mechanism known as 'reactive astrogliosis', which facilitates scar formation, thereby helping to contain inflammation and control tissue damage. Astrocytes can also ensure the survival of nerve cells located immediately adjacent to a site of tissue injury, thereby preserving the function of neuronal networks. The researchers were able to elucidate a new mechanism which explains what processes happen inside the astrocytes and how these are coordinated.

"We were able to show for the first time that the protein 'drebrin' controls astrogliosis," says study lead Prof. Dr. Britta Eickholt, Director of Charité's Institute of Biochemistry and Molecular Biology. "Astrocytes need drebrin in order to form scars and protect the surrounding tissue." By switching off the production of drebrin inside astrocytes, the researchers were able to study its role in brain injury in an animal model. They used electron microscopy and high-resolution light microscopy to investigate cellular changes in the brain, in addition to undertaking real-time investigations using isolated astrocytes in cell culture. "Loss of drebrin results in the suppression of normal astrocyte activation," explains Prof. Eickholt. She adds: "Instead of engaging in defensive reactions, these astrocytes suffer complete loss of function and abandon their cellular identity." Without protective scar formation, normally harmless injuries will spread, and more and more nerve cells will die.

To enable scar formation, drebrin controls the reorganization of the actin cytoskeleton, an internal scaffold responsible for maintaining astrocyte mechanical stability. By doing so, drebrin also induces the formation of long cylindrical membrane structures known as tubular endosomes, which are used in the uptake, sorting and redistribution of surface receptors and are needed for the defensive measures of astrocytes. Summing up the researchers' findings, Prof. Eickholt says: "Our findings also show how drebrin uses the dynamic and versatile cytoskeleton as well as membrane structures to control astrocyte functions which are fundamental to the defense mechanism against injury." She continues: "In particular, the membrane tubules which are formed during this process have not previously been described in this manner, neither in cultured astrocytes nor in the brain."

"Drebrin's role as a cytoskeletal regulator suggests that it may be a risk factor for severe outcomes in both neurological and other disorders, because loss of the protein can produce similar changes in astrocytes," says Prof. Eickholt. She adds: "It is also possible that individuals with defects in the drebrin gene - comparable to those in the animal model - might remain without symptoms until triggers like cellular stresses, environmental toxins or diseases occur." It is hoped that investigations involving patient samples will elucidate the extent to which drebrin also plays a role in degenerative brain disorders, such as Alzheimer's disease.

What The Study Did: This article discusses possible pathogenic mechanisms of brain dysfunction in patients with COVID-19.

Authors: Maura Boldrini, M.D., Ph.D., of the New York State Psychiatric Institute, Columbia University Irving Medical Center in New York, is the corresponding author.

To access the embargoed study: Visit our For The Media website at this link https://media.jamanetwork.com/

(doi:10.1001/jamapsychiatry.2021.0500)

Editor's Note: The article includes conflict of interest disclosures. Please see the article for additional information, including other authors, author contributions and affiliations, conflict of interest and financial disclosures, and funding and support.

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An elusive whale species in the Southern Ocean could be resilient to near-future ecosystem changes, according to a new study by the universities of Exeter and Copenhagen.

Gray's beaked whales living in the deep oceans of the Southern Hemisphere are rarely seen alive and their ecology has remained a mystery to scientists until now.

The study used genome sequencing of 22 whales washed up on beaches in South Africa, Australia and New Zealand to investigate the history of the population over the past 1.1 million years.

Author of the study Dr Kirsten Thompson, of the University of Exeter, said: "The population approximately doubled about 250 thousand years ago, coinciding with a period of increased Southern Ocean productivity, sea surface temperature and a potential expansion of suitable habitat."

The current population appears to have high levels of genetic diversity and no "genetic structure" (patterns of genetic similarity in geographical areas), suggesting the whales leave their birth groups and move widely throughout their Southern Hemisphere range.

Based on these findings, this perfect match of high genetic diversity, a flexible social system and the rich habitats of Southern Hemisphere mean that Gray's beaked whales could be to be resilient to changing conditions.

"Human activity is causing rapid ecological change in every habitat on Earth, including the deep oceans," said Dr Thompson.

"We need to understand how different species might respond to these changes, but we lack detailed knowledge on many animals, particularly deep-sea whales like Gray's beaked whales."

Observation data on this species is impossible to obtain - they are small (five metres), deep-diving whales that spend most of their time below the surface searching and feeding on squid - whalers nicknamed them "scamperdown whales" due to their elusive behaviour.

The study used both mitochondrial DNA to investigate the history of the population, and partial nuclear genomes to estimate population structure.

"Our findings suggest numbers of Gray's beaked whales have been relatively stable for the last 1.1 million years," Dr Thompson said.

"The Southern Hemisphere's oceans could potentially support a surprisingly large number of Gray's beaked whales. Good news for one species at least.

"We show how genomic tools can help to reveal past history, current status and potential near-future changes in animal populations that are enigmatic, rarely observed and beyond the reach of traditional boat surveys."

A new study analyzes the larval dispersal of nine fish species in the western Mediterranean and identifies three large areas in which there is barely fish exchange, so fish would remain in the same area all their life.

The study, published in the journal Progress in Oceanography, is led by experts of the Faculty of Biology of the University of Barcelona and the Biodiversity Research Institute (IRBio) of the UB, the Blanes Center for Advanced Studies (CEAB-CSIC), the Balearic Islands Coastal Observing and Forecasting System (ICTS - SOCIB), and the Mediterranean Institute for Advanced Studies (IMEDEA, CSIC-UIB).

The three identified areas are the Balearic Sea, the West Algerian Basin, and the Alboran Sea. These marine areas are separated by oceanographic discontinuities that act as barriers, in this case the Ibiza channel and the Almeria-Oran front, two fronts that are hard to cross for fish larvae due to the difficult circulation and exchange of water masses.

These results are relevant for the setting of protecting areas since many of the demersal fish species -those living in seafloors- are sedentary in their adult life and barely move. However, when these are under the larval phase, they move across the currents mainly, a moment when they are more likely to distribute around outside their birth place.

Low Exchange between marine areas

The studied species are the common two-banded sea bream (Diplodus vulgaris), the white seabream (Diplodus sargus), the sheephead bream (Diplodus puntazzo), the dreamfish (Sarpa salpa), the saddle bream (Oblada melanuria), the damselfish (Chromis chromis), the Mediterranean rainbow wrasse (Coris julis), the ocellated wrasse (Symphodus ocellatus) and the East Atlantic peacock wrasse (Symphodus tinca). These species are abundant and present differences at a trophic level, the reproductive seasons and ways and the length of the larval phase (from 7 to 43 days and egg-laying in different seasons).

"Also, there is individualized information of these species on the birth date and larval life length according to a previous study", notes Hèctor Torrado, researcher at CEAB-CSIC and UB-IRBio, and lead author of the study. "This enabled the modelling of the dispersal at an individual level and to infer the potential origin of each individual", he adds.

"Our study shows that the three identified areas present a low exchange of individuals of all species and that should be considered three hydrodynamics units", notes Enrique Macpherson, researcher at CEAB-CSIC and co-author of the study. This information is relevant regarding the marine reserve setting.

Reserves must guarantee connectivity

In order for them to be effective, marine reserves should work as a network that allows an interconnection between them at a populational level. This enables a flux of species and individuals that ensure its efficiency in the conservation of marine ecosystems.

"Therefore, inside every hydrodynamic unit, there can be a good network of interconnected areas but this connection will be weak between units. This information has to be considered when designing a network of protected areas including different areas", notes Marta Pascual, lecturer at the Faculty of Biology and UB-IRBio and co-author of the study.

Most of the fish spend their life in the same oceanographic region where they were born. However, there are some exceptions. For instance, the Balearic Sea features individuals that were born in the same area but some could have arrived from the north, Provençal waters and the Ligurian Sea.

Experts also consider reproductive periods of species as an important factor (egg-laying, hatching period, and the length of the larval period). As the study states, there are seasonal changes in the oceanographic barriers that affect their permeability and as a result, the larval crossing across these barriers. Also, the speed and direction of currents can change over the year, which also affects the larval dispersal and connectivity between areas.

Moreover, there are areas with a higher variation, not only seasonal but also interannual, which can change connectivity between localities at an evolutionary scale.

The dynamics and seasonal variations of water masses can determine the connectivity patterns of these species, experts say. Regarding how much these results of nine species could be extrapolated to other species, scientists say that "in theory, most of coastal fish of western Mediterranean could be extrapolated since we see that the three hydrodynamic units are detected in different species that reproduced in different seasons and with a different larval life length".

"Nevertheless, at a small scale, we observe the importance of the birthdate in the origins of larvae that settle in a place, suggesting that both direction and distance are influenced by the oceanographical variables of the area", conclude the experts.

New study led by the University of Helsinki supports the recognition of new species of South American owls, two of them, Xingu Screech Owl and Alagoas Screech Owl, described for the first time.

In early 2021 two new species of screech owls are being described in a single publication as new to science. A multinational team involving researchers from the University of Helsinki, Brazil, and the USA published a detailed study focusing on the morphological, vocal, and genetic variation in a group of screech owls from the Amazon and Atlantic Forest regions of South America, called the Black-capped / Tawny- bellied Screech Owl complex (Megascops atricapilla - M. watsonii). The term "complex" describes the overall uncertainty in the actual number of species in this group of screech owls, which has varied from one to three over the past decades.

"Not even professional ornithologists who have worked on owls for their entire lives would agree about the actual number of species found in this group, so a study like ours has been awaited for a really long time," says Alex Aleixo, head of the research team responsible for the study, and curator of birds at the Finnish Museum of Natural History in the University of Helsinki, Finland.

The new study published in the scientific journal Zootaxa demonstrated the discovery of six different genetic clusters in the Black-capped / Tawny-bellied Screech Owl complex that are also mutually distinguished by song - a strong indication that they are distinct species.

In contrast, as widely documented in owls, plumage color is variable in the complex, with a single genetic cluster for instance containing five distinct color forms ranging from cinnamon to red. Four out of these six genetic clusters had already been previously recognized as subspecies and given taxonomic names, and the new study support instead their treatment as distinct species. However, two of these clusters had never been recognized or described as unique, and thus had never been given a name. Therefore, the authors described these genetically and vocally diagnosable lineages as new species.

252 specimens, 83 tape-recordings, and 49 genetic samples analyzed

Researchers analyzed altogether, 252 specimens, 83 tape-recordings, and 49 genetic samples from across the range of the Black- capped / Tawny-bellied Screech Owl complex in South America. A significant part of specimens material were collected by the research team itself, mainly by nature tour leader and photographer Sidnei Dantas, who spent a good share of his time in graduate school searching for and tape-recording screech owls in South American rainforests. In addition, natural history collections and their materials collected over the centuries were essential to complete the study ?s unprecedented sampling.

One of these newly described species, the Xingu Screech Owl (Megascops stangiae), has its scientific name in honor of the late Sister Dorothy Mae Stang (1931?2005), an American-born Brazilian member of the Sisters of Notre Dame de Namur, who over 40 years introduced small farmers living in the Amazon to sustainability practices. The common name Xingu Screech Owl refers to the area where the new species is found, between the Tapajo?s and Xingu rivers, where Stang was a very active community leader until her killing.

The second new species described in the new study is the Alagoas Screech Owl (Megascops alagoensis), (Fig. 2), named after the state of Alagoas in Northeastern Brazil, where it was recorded for the first time in February 2001, and where most of the known population remains. This new species is known from only five isolated forest fragments in Alagoas and Pernambuco states.

Deforestation is a threat

Both new species of screech owls described by the new study, and a third one, formerly treated as a subspecies, but validated as a new species for the first time i.e., the Bele?m Screech Owl (Megascops ater),, are threatened by deforestation. The Xingu Screech Owl is endemic to the most severely burned area of the Amazon by the unprecedented 2019 fires and the Alagoas Screech Owl should be regarded as critically endangered given the extensive forest fragmentation in the very small area where it occurs. Finally, the Bele?m Screech Owl is endemic to the most deforested sector of the Amazon forest, with well over 80% of the original forest already cleared.

Every year, 10 million hectares of forest are lost. Among efforts to revive degraded or deforested land is the Bonn Challenge, with a global goal to bring into restoration 350 million hectares by 2030. Yet such efforts neglect the nuanced but critical factor of bringing genetic diversity into restoration efforts for long-term success, which urgently needs to be addressed.

Integrating genetic diversity involves planting tree species with different genetic makeups and varied species adapted to local environments. If species are the same, they will not be able to reproduce or grow new seedlings. Christopher Kettle, an ecologist and geneticist at the Alliance of Bioversity International and the International Center for Tropical Agriculture (CIAT) explained:

"If 1,000 seeds are collected from two neighboring trees and planted in a nursery, those seeds would most likely be highly related. This would greatly reduce the probability that they would reproduce in a forest and produce new seeds. You're basically setting your restoration project up to fail from the start. That's one reason we need genetic diversity as a critical component of restoration projects."

New research in Frontiers in Forests and Global Change shows that investing effort in ensuring genetically diverse seedlings actually has the potential to decrease overall restoration costs by up to 11%. While ambitious goals like the Bonn Challenge have resulted in growing political national and international restoration commitments, planting high-value, fast-growing trees, like teak or eucalyptus, in large numbers can actually lower genetic diversity and undermine restoration efforts.

"There are enormous risks for tropical forests with low genetic diversity," said Kettle. "They will also have low capacity to adapt to the impacts of climate change; less resilience to new pests and pathogens. They will produce less seeds or fruit, with negative impacts on community livelihoods and income-generation. Investing in genetic diversity is the only sensible thing to do economically and ecologically, and it costs less in the long-run."

Danny Nef, an expert researching climate change and socio-economic changes at the Alliance and ETH Zurich, said that investing in genetic diversity is critical despite higher initial costs. "It would result in one third higher seed collection costs, but expected ecological and socioeconomic long-term benefits would far outweigh additional costs. Even without any positive effects on post-maintenance costs, the total cost of the overall project would only increase by around 1%," he said.

"Something that's amazed me while working on this paper is that not a single study I have found has considered genetic diversity in the cost of restoration. The question is why not? It simply doesn't make sense not to invest a little bit more at the start of restoration initiatives from a cost perspective, when you look at the bigger, holistic benefit."

Agricultural economist Elisabetta Gotor added: "We economists tend to measure income-related expenses because they are easiest to assess. But I think it's time for us to push ourselves, to tackle the resilience outcome generated by the conservation of genetics, looking at what materials are being used for example, for a more meaningful and accurate economic outcome from an environmental perspective."

The global benefits of tropical forest restoration may be harder to measure but "the costs of planting seedlings are often felt at one end of the scale by farmers for example, while the overall benefits occurring from restoration in the long-run are at the global scale," Gottor said. "This is why we have to connect the initial cost of investment in better quality seed, with the magnitude of broader benefits that don't necessary have a market value."

The researchers noted that while their evidence is based on a number of conservative assumptions and literature review, their findings show that long-term benefits associated with high genetic diversity are too low not to be considered and far outweigh costs. "This is an urgent call for restoration policies to integrate diversity at the species and genetic level into restoration planning and management," they said.

"We do not consider efficiency in this context to be the planting of as many trees as possible per invested capital, but rather the long-term establishment of a tree population that serves the aim of restoration and thus ensures the sustainability of the invested capital," they said, adding that building capacity among those responsible for implementing restoration efforts is also key to success.