New images reveal global air quality trends

The global concentrations of one of the main air pollutants known to affect human health have been graphically illustrated for the first time by a team of scientists.

The Air Quality Stripes which were created by the University of Leeds, the University of Edinburgh, North Carolina State University, and the UK Met Office, starkly contrast the significant improvements in air quality across much of Europe with the alarming deterioration in parts of Africa and Central Asia.

The project's findings highlight both the successes and ongoing challenges in tackling air pollution worldwide.

Dr Kirsty Pringle from EPCC at the University of Edinburgh and co-director of the project, said: "Air pollution is often called the 'invisible killer', but these images make the invisible visible, showing the changes in particulate matter pollution over the decades."

Dr Jim McQuaid, an Associate Professor of Atmospheric Composition in the Leeds' School of Earth and Environment who worked on the Air Quality Stripes project with Dr Pringle, said: "The bottom line is that air pollution is one of the world's leading risk factors for death, it is thought to contribute to one in ten deaths globally.

"Our Air Quality Stripes show the huge range in trends and concentrations around the world. The stripes demonstrate that there is still more work to be done to reduce people's exposure to poor air quality, and in some places a great deal more!"

Inspired by the world-famous climate warming stripes image, the researchers created their own illustration to plot the changing trends in outdoor concentrations of what is known as particulate matter air pollution, a mix of tiny liquid or solid particles such as dust, dirt, soot, or smoke, which are found throughout the atmosphere.

Dr Steven Turnock, a senior scientist from the UK Met Office who provided the data for the Air Quality Stripes project, said: "Presenting this scientific data as Air Quality stripes really brings into focus the stark contrast in air quality trends and people's exposure to poor air quality depending on where they live."

There are stripes for the capital city of every nation worldwide with two additional cities for China, India, and the United States. The research team also included their own cities of Leeds, Edinburgh, and Exeter.

The lightest blue stripes meet the World Health Organisation Air Quality Guidelines which were introduced in 2021, with all other colours exceeding the guideline values.

Data from computer simulations and satellite observations were combined to estimate the changing concentrations of particulate matter since the beginning of the industrial revolution, with the colour palette for the stripes devised by an artist who analysed over 200 online images of "air pollution" to identify the dominant colour palettes.

Key Findings:

• Europe's Air Quality Gains: The images show substantial reductions in particulate matter levels across most of Europe (predominantly Western Europe). Stricter air quality regulations and technological advancements have successfully reduced particulate matter concentrations in most European cities (e.g. London, Brussels, Berlin).
• Worsening Conditions in Central Asia and parts of Africa: The visualisations reveal a concerning rise in particulate matter pollution in many cities in central Asia and Africa (e.g. Islamabad, Delhi, Nairobi). Rapid urbanisation, industrial growth, and limited regulatory frameworks are contributing to this troubling trend, which poses significant health risks to local populations.
• Global Disparities: The images highlight the stark disparities in air quality progress between different regions, emphasising the need for targeted international efforts to address the growing air pollution crisis in the most affected areas.
• The influence of natural sources was particularly notable in some locations, these sources include desert dust and wildfires, proximity to the coast was often quite noticeable with locations such as Jakarta having lower levels than might be expected.

A cocktail of pollutants

Particulate matter, or PM2.5, have a diameter less than a 30th of the width of a human hair and can penetrate deep into our lungs easily. The smallest particles cross into the bloodstream and affect our health, and some have even been detected in the blood of unborn children.

They can come from natural sources such as volcanoes and deserts but are also produced by human activities such as industry, cars, agriculture, domestic burning, and fires arising from climate change.

PM2.5 has been linked to a very wide range of health issues ranging from breathing problems like asthma, to reduced lung health, increased likelihood of developing cancer and heart disease, and an increased risk of developing many diseases including diabetes, Alzheimer's, and Parkinson's.

The World Health Organisation recommends that the annual average concentration of PM2.5 should not exceed a concentration of 5 micrograms per cubic meter air (5 ug/m³). This new guideline is a concentration which is generally classed as very good air quality. It is important to remember that there is NO safe level of PM2.5 recognised by medical science. At present, 99% of the world's population live with concentrations above this value, with the highest PM2.5 levels typically found in low- and middle-income countries.

TheAQ stripes use an annual average to take account of the ups and downs due to changes in weather patterns throughout the year, and to make comparison between locations simpler. However the researchers point out that even short-term exposure to very high levels can quickly have acute health effects requiring medical treatment.

Dr McQuaid added: "We created these to try to illustrate the complex data that computer models generate, into something that is much easier to understand.

"Strangely, one of the major headaches for us was the colour scheme. We finally went for blue to black, representing nice clean blue skies, through to black for extremely high levels of pollution.

"In the end we contacted a colleague in the US (Douglas Hamilton) and he worked with one of his team to create a colour scheme using an internet search of images tagged as 'air pollution' and they came up with what we finally went with. It was very similar to what we already had, but great to get external validation.

"To me it's all about that lightbulb moment when someone understands it; that sudden 'oh yeah now I get it!' I wanted it to be simple enough that non-experts could look at it and be able to understand it without having done science since leaving school. "

Dr Pringle added: "The images show that it is possible to reduce air pollution; the air in many cities in Europe is much cleaner now than it was 100 years ago, and this is improving our health. We really hope similar improvements can be achieved across the globe."

The Air Quality Stripes follow in the footsteps of the Climate Warming Stripes which were created by Professor Ed Hawkins at the National Centre for Atmospheric Science and University of Reading in 2018 and have since become very widely used as a visual representation of the Earth's warming climate.

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'Genomic time machine' reveals secrets of our DNA

The human genome, an intricate tapestry of genetic information for life, has proven to be a treasure trove of strange features. Among them are segments of DNA that can "jump around" and move within the genome, known as "transposable elements" (TEs).

As they change their position within the genome, TEs can potentially cause mutations and alter the cell's genetic profile, but also are master orchestrators of our genome's organization and expression.

For example, TEs contribute to regulatory elements, transcription factor binding sites, and the creation of chimeric transcripts -- genetic sequences created when segments from two different genes or parts of the genome join together to form a new, hybrid RNA molecule.

Matching their functional importance, TEs have been recognized to account for half of the human DNA.

However, as they move and age, TEs pick up changes that mask their original form.

Over time, TEs "degenerate" and become less recognizable, making it difficult for scientists to identify and track them in our genetic blueprint.

In a new study, researchers in the group of Didier Trono at EPFL have found a way to improve the detection of TEs in the human genome by using reconstructed ancestral genomes from various species, which allowed them to identify previously undetectable degenerate TEs in the human genome.

The study is published in Cell Genomics.

The scientists used a database of reconstructed ancestral genomes from different kinds of species, like a genomic "time machine." By comparing the human genome with the reconstructed ancestral genomes, they could identify TEs in the latter that, over millions of years, have become degenerate (worn out) in humans.

This comparison allowed them to detect ("annotate") TEs that might have been missed in previous studies that used data only from the human genome.

Using this approach, the scientists uncovered a larger number of TEs than previously known, adding significantly to the share of our DNA that is contributed by TEs.

Furthermore, they could demonstrate that these newly unearthed TE sequences played all the same regulatory roles as their more recent, already identified relatives.

Read more at Science Daily

Climate-driven extreme heat may make parts of Earth too hot for humans

If global temperatures increase by 1 degree Celsius (C) or more than current levels, each year billions of people will be exposed to heat and humidity so extreme they will be unable to naturally cool themselves, according to interdisciplinary research from the Penn State College of Health and Human Development, Purdue University College of Sciences and Purdue Institute for a Sustainable Future.

Results from a new article published today (Oct. 9) in Proceedings of the National Academy of Sciences indicated that warming of the planet beyond 1.5 C above preindustrial levels will be increasingly devastating for human health across the planet.

Humans can only withstand certain combinations of heat and humidity before their bodies begin to experience heat-related health problems, such as heat stroke or heart attack. As climate change pushes temperatures higher around the world, billions of people could be pushed beyond these limits.

Since the start of the industrial revolution, when humans began to burn fossil fuels in machines and factories, temperatures around the world have increased by about 1 C, or 1.8 degrees Fahrenheit (F). In 2015, 196 nations signed the Paris Agreement which aims to limit worldwide temperature increases to 1.5 C above pre-industrial levels.

The researcher team modeled global temperature increases ranging between 1.5 C and 4 C -- considered the worst-case scenario where warming would begin to accelerate -- to identify areas of the planet where warming would lead to heat and humidity levels that exceed human limits.

"To understand how complex, real-world problems like climate change will affect human health, you need expertise both about the planet and the human body," said co-author W. Larry Kenney, professor of physiology and kinesiology, the Marie Underhill Noll Chair in Human Performance at Penn State and co-author of the new study. "I am not a climate scientist, and my collaborators are not physiologists. Collaboration is the only way to understand the complex ways that the environment will affect people's lives and begin to develop solutions to the problems that we all must face together."

A threat to billions

The ambient wet-bulb temperature limit for young, healthy people is about 31 C, which is equal to 87.8 F at 100% humidity, according to work published last year by Penn State researchers. However, in addition to temperature and humidity, the specific threshold for any individual at a specific moment also depends on their exertion level and other environmental factors, including wind speed and solar radiation. In human history, temperatures and humidity that exceed human limits have been recorded only a limited number of times -- and only for a few hours at a time -- in the Middle East and Southeast Asia, according to the researchers.

Results of the study indicate that if global temperatures increase by 2 C above pre-industrial levels, the 2.2 billion residents of Pakistan and India's Indus River Valley, the one billion people living in eastern China and the 800 million residents of sub-Saharan Africa will annually experience many hours of heat that surpass human tolerance.

These regions would primarily experience high-humidity heatwaves. Heatwaves with higher humidity can be more dangerous because the air cannot absorb excess moisture, which limits sweat evaporates from human bodies and moisture from some infrastructure, like evaporative coolers. Troublingly, researchers said, these regions are also in lower-to-middle income nations, so many of the affected people may not have access to air conditioning or any effective way to mitigate the negative health effects of the heat.

If warming of the planet continues to 3 C above pre-industrial levels, the researchers concluded, heat and humidity levels that surpass human tolerance would begin to affect the Eastern Seaboard and the middle of the United States -- from Florida to New York and from Houston to Chicago. South America and Australia would also experience extreme heat at that level of warming.

At current levels of heating, the researchers said, the United States will experience more heatwaves, but these heatwaves are not predicted to surpass human limits as often as in other regions of the world. Still, the researchers cautioned that these types of models often do not account for the worst, most unusual weather events.

"Models like these are good at predicting trends, but they do not predict specific events like the 2021 heatwave in Oregon that killed more than 700 people or London reaching 40 C last summer," said lead author Daniel Vecellio, a bioclimatologist who completed a postdoctoral fellowship at Penn State with Kenney. "And remember, heat levels then were all below the limits of human tolerance that we identified. So, even though the United States will escape some of the worst direct effects of this warming, we will see deadly and unbearable heat more often. And -- if temperatures continue to rise -- we will live in a world where crops are failing and millions or billions of people are trying to migrate because their native regions are uninhabitable."

Understanding human limits and future warming

Over the last several years, Kenney and his collaborators have conducted 462 separate experiments to document the combined levels of heat, humidity and physical exertion that humans can tolerate before their bodies can no longer maintain a stable core temperature.

"As people get warmer, they sweat, and more blood is pumped to their skin so that they can maintain their core temperatures by losing heat to the environment," Kenney said. "At certain levels of heat and humidity, these adjustments are no longer sufficient, and body core temperature begins to rise. This is not an immediate threat, but it does require some form of relief. If people do not find a way to cool down within hours, it can lead to heat exhaustion, heat stroke and strain on the cardiovascular system that can lead to heart attacks in vulnerable people."

In 2022, Kenney, Vecellio and their collaborators demonstrated that the limits of heat and humidity people can withstand are lower than were previously theorized.

"The data collected by Kenney's team at Penn State provided much needed empirical evidence about the human body's ability to tolerate heat. Those studies were the foundation of these new predictions about where climate change will create conditions that humans cannot tolerate for long," said co-author Matthew Huber, professor of earth, atmospheric and planetary sciences at Purdue University.

When this work was published, Huber, who had already begun work on mapping the impacts of climate change, contacted Vecellio about a potential collaboration. Huber had previously published widely cited work proposing a theoretical limit of humans' heat and humidity limits.

The researchers, along with Huber's graduate student, Qinqin Kong, decided to explore how people would be affected in different regions of the world if the planet warmed by between 1.5 C and 4 C. The researchers said that 3 C is the best estimate of how much the planet will warm by 2100 if no action is taken.

"Around the world, official strategies for adapting to the weather focus on temperature only," Kong said. "But this research shows that humid heat is going to be a much bigger threat than dry heat. Governments and policymakers need to re-evaluate the effectiveness of heat-mitigation strategies to invest in programs that will address the greatest dangers people will face."

Staying safe in the heat

Regardless of how much the planet warms, the researchers said that people should always be concerned about extreme heat and humidity -- even when they remain below the identified human limits. In preliminary studies of older populations, Kenney found that older adults experience heat stress and the associated health consequences at lower heat and humidity levels than young people.

"Heat is already the weather phenomenon that kills the most people in the United States," Vecellio, now a postdoctoral researcher at George Mason University's Virginia Climate Center, said. "People should care for themselves and their neighbors -- especially the elderly and sick -- when heatwaves hit."

The data used in this study examined the body's core temperatures, but the researchers said that during heatwaves, people experience health problems from other causes as well. For example, Kenney said that most of the 739 people who died during Chicago's 1995 heatwave were over 65 and experienced a combination of high body temperature and cardiovascular problems, leading to heart attacks and other cardiovascular causes of death.

Looking to the future

To stop temperatures from increasing, the researchers cite decades of research indicating that humans must reduce the emission of greenhouse gases, especially the carbon dioxide emitted by burning fossil fuels. If changes are not made, middle-income and low-income countries will suffer the most, Vecellio said.

As one example, the researchers pointed to Al Hudaydah, Yemen, a port city of more than 700,000 people on the Red Sea. Results of the study indicated that if the planet warms by 4 C, this city can expect more than 300 days when temperatures exceed the limits of human tolerance every year, making it almost uninhabitable.

"The worst heat stress will occur in regions that are not wealthy and that are expected to experience rapid population growth in the coming decades," Huber said. "This is true despite the fact that these nations generate far fewer greenhouse gas emissions than wealthy nations. As a result, billions of poor people will suffer, and many could die. But wealthy nations will suffer from this heat as well, and in this interconnected world, everyone can expect to be negatively affected in some way."

Read more at Science Daily

'Time-traveling' pathogens in melting permafrost pose likely risk to environment

Ancient pathogens that escape from melting permafrost have real potential to damage microbial communities and might potentially threaten human health, according to a new study by Giovanni Strona of the European Commission Joint Research Centre and colleagues, published July 27 in the open-access journal PLOS Computational Biology.

The idea that "time-traveling" pathogens trapped in ice or hidden in remote laboratory facilities could break free to cause catastrophic outbreaks has inspired generations of novelists and screenwriters. While melting glaciers and permafrost are giving many types of dormant microbes the opportunity to re-emerge, the potential threats to human health and the environment posed by these microbes have been difficult to estimate.

In a new study, Strona's team quantified the ecological risks posed by these microbes using computer simulations. The researchers performed artificial evolution experiments where digital virus-like pathogens from the past invade communities of bacteria-like hosts. They compared the effects of invading pathogens on the diversity of host bacteria to diversity in control communities where no invasion occurred.

The team found that in their simulations, the ancient invading pathogens could often survive and evolve in the modern community, and about 3 percent became dominant. While most of the dominant invaders had little effect on the composition of the larger community, about 1 percent of the invaders yielded unpredictable results. Some caused up to one third of the host species to die out, while others increased diversity by up to 12 percent compared to the control simulations.

Read more at Science Daily

New research reveals the impact of different species and their traits on human wellbeing

New research has revealed for the first time that well-functioning ecosystems are crucial to human health and wellbeing, with human-biodiversity interactions delivering wellbeing gains equating to substantial healthcare cost-savings, when scaled-up across populations.

The University of Kent-led study, which is part of the European Research Council-funded project 'Relating Subjective Wellbeing to Biodiversity' (RELATE), set out to understand which components of nature and biodiversity played a particular role in human wellbeing.

The team, which was led by Kent's Professor Zoe Davies, analysed the effects of species' traits, based on people's feedback following a series of workshops, to identify those that generate different types of wellbeing e.g., physical, emotional, cognitive, social, spiritual, and 'global', the latter being akin to 'whole-person health'.

The team found that, in general, the vast majority of species and traits are beneficial to human wellbeing. They also discovered that each species may support multiple traits, potentially with different impacts. For example, the colours of brambles (black, pink, red) are linked to multiple positive physical, emotional and social wellbeing types, but their prickly texture generated negative emotional wellbeing. The numerous traits from across an ecological community can elicit a multitude of wellbeing responses, illustrating the true complexity of how people relate to biodiversity.

Professor Davies, a biodiversity conservationist at Kent's Durrell Institute of Conservation and Ecology (DICE), said: 'While we know that spending time in natural environments can improve our health and wellbeing, we still need to know more about which species, or traits of species (such as colours, sounds, smells, textures and behaviours), deliver these benefits -- and how people's relationships with biodiversity are both contextually and culturally specific. Understanding how people experience biodiversity is therefore key to successfully managing biodiversity to facilitate human wellbeing.'

Study co-author, Professor Martin Dallimer, from the School of Earth and Environment, University of Leeds, said: 'For the first time, through analysing people's own words and reflections, we are able to explicitly link that feeling of wellbeing with species and their traits. How people respond to biodiversity is hugely varied and if we want people's wellbeing to benefit from spending time in nature, then it is essential to make sure we are maintaining and restoring high quality biodiverse spaces for wildlife and for people. Our aim is that these findings really drive home how important biodiversity is in underpinning wellbeing benefits, particularly to healthcare and public sectors who include 'spending time in nature' as an element of mental health and wellbeing.'

Read more at Science Daily

Global wetlands losses overestimated despite high losses in many regions

Sometime this spring or summer, the Supreme Court is expected to issue a case ruling that will legally define whether federal protections should be extended to wetlands outside of navigable waters. The justices might consider reading a new Stanford-led study that finds, although wetlands remain threatened in many parts of the world -- including the U.S., which accounts for more losses than any other country -- global losses of wetlands have likely been overestimated. Published Feb. 8 in Nature, the study's findings could help better explain the causes and impacts of wetland loss, enabling more informed plans to protect or restore ecosystems crucial for human health and livelihoods.

"Despite the good news that our results might imply, it remains urgent to halt and reverse the conversion and degradation of wetlands," said study lead author Etienne Fluet-Chouinard, a postdoctoral associate in Stanford's Department of Earth System Science at the time of the research. "The geographic disparities in losses are critical to consider because the forgone local benefits from drained wetlands cannot be replaced by wetlands elsewhere."

Rethinking wetlands

Now understood to be vital sources of water purification, groundwater recharge, and carbon storage, wetlands were long seen as unproductive areas teeming with disease-bearing insects and good only for draining to grow crops or harvest peat for fuel and fertilizer. Unrelenting drainage for conversion to human land uses, such as farmland and urban areas, in addition to alteration by fires and groundwater extraction, has made wetlands among the world's most threatened ecosystems in the world.

Accurately estimating the extent, distribution, and timing of wetland loss is key to understanding their role in natural processes and the impact of wetland drainage on the water and carbon cycles. A lack of historical data has hindered the effort, forcing scientists to make estimates based on incomplete collections of regional data on wetland loss.

"Wetlands purify our water, prevent flooding, and are biodiversity superheroes," said study co-author Rob Jackson, the Michelle and Kevin Douglas Provostial Professor of Energy and Environment in the Stanford Doerr School of Sustainability. "We need the best data possible to save what we have and know what we've lost."

A second chance

In a first-of-its-kind historical reconstruction, the researchers combed through thousands of records of wetland drainage and land-use changes in 154 countries, mapping the distribution of drained and converted wetlands onto maps of present-day wetlands to get a picture of what the original wetland area might have looked like in 1700.

They found that the area of wetland ecosystems has declined 21-35% since 1700 due to human intervention. That's far less than the 50-87% losses estimated by previous studies. Still, the authors estimate that at least 1.3 million square miles of wetlands have been lost globally -- an area about the size of Alaska, Texas, California, Montana, New Mexico, and Arizona combined.

"These new results allow us to better quantify changes in wetlands' sequestration of carbon from the atmosphere and emission of methane, another powerful greenhouse gas," said study co-author Avni Malhotra, a Stanford postdoctoral researcher at the time of the research.

The low estimate is likely the result of the study's focus beyond regions with historically high wetland losses, and its avoidance of large extrapolations -- characteristics of many previous estimates. The researchers note their estimate of losses is likely conservative because they constrained their analysis to available data, which is scarce for the years before 1850.

Despite what may seem to be good news, the researchers emphasize that wetland losses have been dramatically high in some regions, such as the U.S., which is estimated to have lost 40% of its wetlands since 1700 and accounts for more than 15% of all global losses during the study's time period. Although wetland conversion and degradation have slowed globally, it continues apace in some regions, such as Indonesia, where farmers and corporations continue to clear large swaths of land for oil palm plantations and other agricultural uses.

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Unveiling the mysteries of senescent cells and their effect on aging and human health

Multiple researchers at the Jackson Laboratory are taking part in an ambitious research program spanning several top research institutions to study senescent cells. Senescent cells stop dividing in response to stressors and seemingly have a role to play in human health and the aging process. Recent research with mice suggests that clearing senescent cells delays the onset of age-related dysfunction and disease as well as all-cause mortality.

Could therapies that remove senescent cells -- called senotherapeutics -- also improve the health of humans as we age? Answering this question and more has the potential to significantly advance human health, and the National Institutes of Health (NIH) has launched an extensive research initiative for this very purpose.

The SenNet Consortium, a collaboration of institutions from throughout the United States, was initially launched in 2021 with centers established to gather and analyze human data. The researchers will collect and analyze 18 tissues from healthy humans across lifespan to discern the full scope of senescent cells and how they may contribute to the aging process. The work of the SenNet Consortium was recently presented in a paper published in Nature Aging.

Along with colleagues from Mayo Clinic, University of Texas Health Science center at San Antonio, and UConn Health, JAX Professor Paul Robson, Ph.D. is taking part in the mapping of four human tissue types (kidney, adipose, pancreas, and placenta) within the KAPP-Sen Tissue Mapping Center. The Robson Lab also leads the Biological Analysis Core, and the Data Analysis Core of KAPP-Sen TMC is led by JAX Associate Professor Duygu Ucar, Ph.D., and JAX Professor Jeff Chuang, Ph.D.

SenNet has also grown over the past year to add mouse-focused investigators, and JAX was designated as a Tissue Mapping Center (TMC) for SenNet in August 2022, supported by a four-year, $10.7 million grant from the National Institute on Aging. JAX-Sen is led by Professor and Maxine Groffsky Endowed Chair Nadia Rosenthal, Ph.D., FMedSci with co-principal investigators Robson, JAX Associate Professor Ron Korstanje, Ph.D., and UConn Health's Ming Xu, Ph.D. Associate Professor Sheng Li and Principal Computational Scientist Matt Mahoney lead the Data Analysis Core of the JAX-Sen TMC.

JAX is poised to make substantial contributions to SenNet by profiling senescent cells in kidney, placenta, pancreas, and heart, all tissues that are relevant to chronic diseases of aging. The team will draw upon its genetically diverse mouse resources, including Diversity Outbred mouse populations, to model a range of molecular senescence traits, as well as inbred mice specifically engineered to help visualize senescent cell subsets.

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Calorie restriction trial reveals key factors in extending human health

Decades of research has shown that limits on calorie intake by flies, worms, and mice can enhance life span in laboratory conditions. But whether such calorie restriction can do the same for humans remains unclear. Now a new study led by Yale researchers confirms the health benefits of moderate calorie restrictions in humans -- and identifies a key protein that could be harnessed to extend health in humans.

The findings were published Feb. 10 in Science.

The research was based on results from the Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy (CALERIE) clinical trial, the first controlled study of calorie restriction in healthy humans. For the trial, researchers first established baseline calorie intake among more than 200 study participants. The researchers then asked a share of those participants to reduce their calorie intake by 14% while the rest continued to eat as usual, and analyzed the long-term health effects of calorie restriction over the next two years.

The overall aim of the clinical trial was to see if calorie restriction is as beneficial for humans as it is for lab animals, said Vishwa Deep Dixit, the Waldemar Von Zedtwitz Professor of Pathology, Immunobiology, and Comparative Medicine, and senior author of the study. And if it is, he said, researchers wanted to better understand what calorie restriction does to the body specifically that leads to improved health.

Since previous research has shown that calorie restriction in mice can increase infections, Dixit also wanted to determine how calorie restriction might be linked to inflammation and the immune response.

"Because we know that chronic low-grade inflammation in humans is a major trigger of many chronic diseases and, therefore, has a negative effect on life span," said Dixit, who is also director of the Yale Center for Research on Aging. "Here we're asking: What is calorie restriction doing to the immune and metabolic systems and if it is indeed beneficial, how can we harness the endogenous pathways that mimic its effects in humans?"

Dixit and his team started by analyzing the thymus, a gland that sits above the heart and produces T cells, a type of white blood cell and an essential part of the immune system. The thymus ages at a faster rate than other organs. By the time healthy adults reach the age of 40, said Dixit, 70% of the thymus is already fatty and nonfunctional. And as it ages, the thymus produces fewer T cells. "As we get older, we begin to feel the absence of new T cells because the ones we have left aren't great at fighting new pathogens," said Dixit. "That's one of the reasons why elderly people are at greater risk for illness."

For the study, the research team used magnetic resonance imaging (MRI) to determine if there were functional differences between the thymus glands of those who were restricting calories and those who were not. They found that the thymus glands in participants with limited calorie intake had less fat and greater functional volume after two years of calorie restriction, meaning they were producing more T cells than they were at the start of the study. But participants who weren't restricting their calories had no change in functional volume.

"The fact that this organ can be rejuvenated is, in my view, stunning because there is very little evidence of that happening in humans," said Dixit. "That this is even possible is very exciting."

With such a dramatic effect on the thymus, Dixit and his colleagues expected to also find effects on the immune cells that the thymus was producing, changes that might underlie the overall benefits of calorie restriction. But when they sequenced the genes in those cells, they found there were no changes in gene expression after two years of calorie restriction.

This observation required the researchers to take a closer look, which revealed a surprising finding: "It turns out that the action was really in the tissue microenvironment not the blood T cells," Dixit said.

Dixit and his team had studied adipose tissue, or body fat, of participants undergoing calorie restriction at three time points: at the beginning of the study, after one year, and after two. Body fat is very important, Dixit said, because it hosts a robust immune system. There are several types of immune cells in fat, and when they are aberrantly activated, they become a source of inflammation, he explained.

"We found remarkable changes in the gene expression of adipose tissue after one year that were sustained through year two," said Dixit. "This revealed some genes that were implicated in extending life in animals but also unique calorie restriction-mimicking targets that may improve metabolic and anti-inflammatory response in humans."

Recognizing this, the researchers then set out to see if any of the genes they identified in their analysis might be driving some of the beneficial effects of calorie restriction. They honed in on the gene for PLA2G7 -- or group VII A platelet activating factor acetylhydrolase -- which was one of the genes significantly inhibited following calorie restriction. PLA2G7 is a protein produced by immune cells known as macrophages.

This change in PLA2G7 gene expression observed in participants who were limiting their calorie intake suggested the protein might be linked to the effects of calorie restriction. To better understand if PLA2G7 caused some of the effects observed with calorie restriction, the researchers also tracked what happened when the protein was reduced in mice in a laboratory experiment.

"We found that reducing PLA2G7 in mice yielded benefits that were similar to what we saw with calorie restriction in humans," said Olga Spadaro, a former research scientist at the Yale School of Medicine and lead author of the study. Specifically, the thymus glands of these mice were functional for a longer time, the mice were protected from diet-induced weight gain, and they were protected from age-related inflammation.

These effects occurred because PLA2G7 targets a specific mechanism of inflammation called the NLRP3 inflammasome, researchers said. Lowering PLA2G7 protected aged mice from inflammation.

"These findings demonstrate that PLA2G7 is one of the drivers of the effects of calorie restriction," said Dixit. "Identifying these drivers helps us understand how the metabolic system and the immune system talk to each other, which can point us to potential targets that can improve immune function, reduce inflammation, and potentially even enhance healthy lifespan."

For instance, it might be possible to manipulate PLA2G7 and get the benefits of calorie restriction without having to actually restrict calories, which can be harmful for some people, he said.

Read more at Science Daily

Reusable plastic bottles release hundreds of chemicals

Researchers at the University of Copenhagen have found several hundred different chemical substances in tap water stored in reusable plastic bottles. Several of these substances are potentially harmful to human health. There is a need for better regulation and manufacturing standards for manufacturers, according to the chemists behind the study.

Have you ever experienced the strange taste of water after it has been in a reusable plastic bottle for a while? It appears that there is a solid, yet worrying reason for this.

Two chemists from the University of Copenhagen have studied which chemical substances are released into liquids by popular types of soft plastic reusable bottles. The results were quite a surprise.

"We were taken aback by the large amount of chemical substances we found in water after 24 hours in the bottles. There were hundreds of substances in the water -- including substances never before found in plastic, as well as substances that are potentially harmful to health. After a dishwasher cycle, there were several thousand," says Jan H. Christensen, Professor of Environmental Analytical Chemistry at the University of Copenhagen's Department of Plant and Environmental Sciences.

Endocrine disruptors and insecticide

Professor Christensen and fellow researcher Selina Tisler detected more than 400 different substances from the bottle plastic and over 3,500 substances derived from dishwasher soap. A large portion of these are unknown substances that the researchers have yet to identify. But even of the identified chemicals, the toxicity of at least 70 % remains unknown.

Photo-initiators are among the toxic substances in the water which worry the researchers. These are known to have potentially harmful effects on health in organisms, such as being endocrine disruptors and carcinogens. Furthermore, the researchers found a variety of plastic softeners, antioxidants and release agents used in the manufacture of the plastic, as well as Diethyltoluamide (DEET), commonly known as the active substance in mosquito spray.

Machine washing adds more substances into the bottled water

In their experiments, the researchers mimicked the ways in which many people typically use plastic drinks bottles. People often drink water that has been kept in bottles for several hours. The researchers left ordinary tap water in both new and used drinking bottles for 24 hours, both before and after machine washing, as well as after the bottles had been in the dishwasher and rinsed thoroughly in tap water.

"What is released most after machine washing are the soap substances from the surface. Most of the chemicals that come from the water bottle itself remain after machine washing and extra rinsing. The most toxic substances that we identified actually came after the bottle had been in the dishwasher -- presumably because washing wears down the plastic and thereby increases leaching," explains postdoctoral researcher and first author Selina Tisler of the Department of Plant and Environmental Sciences.

In new reusable bottles, close to 500 different substances remained in the water after an additional rinse. Over 100 of these substances came from the plastic itself.

She emphasizes that they have yet to conclude whether the water in the bottles is harmful to health, as they currently have only an estimate of the concentrations of the substances and toxicological assessments have yet to be completed.

'Just because these substances are in the water, doesn't mean that the water is toxic and affects us humans. But the problem is, is that we just don't know. And in principle, it isn't all that great to be drinking soap residues or other chemicals," says Selina Tisler.

"From now on, I'll use a glass bottle."

"We care so much about low levels of pesticides in our drinking water. But when we pour water into a container to drink from, we unflinchingly add hundreds or thousands of substances to the water ourselves. Although we cannot yet say whether the substances in the reusable bottles affect our health, I'll be using a glass or quality stainless steel bottle in the future," says Jan H. Christensen.

The researchers suspect that bottle manufacturers only add a small proportion of the substances found intentionally. The majority have inadvertently occurred either during the production process or during use, where substances may have been converted from other substances. This includes the presence of the mosquito repellent DEET, where the researchers hypothesize that as one of the plastic softeners degrades, it is converted into DEET.

"But even of the known substances that manufacturers deliberately add, only a tiny fraction of the toxicity has been studied. So, as a consumer, you don't know if any of the others have a detrimental effect on your health," says Selina Tisler.

Too little knowledge, too leniently regulated

According to the researchers, the results reflect a lack of both knowledge and regulation:

"The study exemplifies how little knowledge there is about the chemicals emitted from the products that our food and drink come in contact with. And, it is a general problem that measurement regulations during production are very lenient. Fortunately, both in Denmark and internationally, we are looking into how to better regulate this area," says Jan H. Christensen.

In the meantime, Selina Tisler hopes that companies take responsibility on their own accord:

"Hopefully, companies that put their names on reusable plastic bottles will be more careful about the products they purchase from suppliers and perhaps place greater demands on suppliers to investigate the substances found in what they manufacture," Tisler concludes.

The study results are published in the scientific journal Journal of Hazardous Materials.

Brief summary of experiment

Three different types of drinking bottles were tested, all of which are found in Danish stores. Two of the bottles are made of biodegradable plastic, according to the manufacturer. Both new and heavily used bottles were used. The bottles were tested both before and after machine washing, and after five extra rinses in tap water.

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New 'vertical map' of airborne microorganisms indicates how global warming will impact global ecosystems

In a landmark study of airborne microorganisms from ground level up to 3,500 metres, scientists from the Singapore Centre for Environmental Life Sciences Engineering (SCELSE) at Nanyang Technological University, Singapore (NTU Singapore) have found that bacteria and fungi populate the planet's lower atmosphere in very specific ways and if changed, may negatively impact human health and food supply.

Using a combination of a 200-metre meteorological tower and a research aircraft that circled at different heights from 300 metres to 3,500 metres to gather the necessary measurements, the researchers found that temperature was the single most important factor influencing the composition of airborne microbial communities.

As the temperature of the air changes, the species found and the ratio of bacteria to fungi change significantly. These findings suggest that the currently observed increase in global temperature will have an impact on the atmospheric microbial ecosystem, as well as planetary terrestrial and aquatic ecosystems.

The study was published today in the peer-reviewed journal Proceedings of the National Academy of Sciences (PNAS) by a team of interdisciplinary scientists led by NTU Professor Stephan Schuster, Research Director (Meta-'omics & Microbiomes) at SCELSE.

Atmospheric microorganisms, collectively known as the air microbiome, consist of bacteria and fungi, and largely remain suspended in air once they are blown off the planet's surface.

Only a fraction of these microorganisms find their way back down to the surface, when they are washed down by rain droplets or fall back down together with larger particles such as sand grains or dust.

"Our research generated a comprehensive 'vertical map' of airborne microorganisms in the planet's atmosphere," said Prof Schuster, the study's corresponding author.

"We found that the composition of the air microbiome in our atmosphere is determined by the temperature. As global air temperatures are rising due to climate change, this could lead to very significant changes in the air microbiome with serious consequences for people and the planet."

"If the composition of the air microbiome changes globally, it may affect human health, exacerbating respiratory syndromes in susceptible patients, or it could affect the yield of agricultural crops, which then threatens our food security. Natural processes that have worked for thousands of years such as carbon cycling of this planet may also be changed."

"With our latest research paper, we are a step closer to showing that air has its own microbial ecosystem, much like those on land and in the sea. We expect that changes in the air microbiome will also have knock-on effects on terrestrial and aquatic ecosystems," adds Prof Schuster.

The vertical map of microorganisms also provides a starting point for future ecological surveys and the necessary measures not only for the protection of global environments, but also for agricultural production sites, which may be negatively impacted by changes to the airborne microbial communities.

With the new dataset as a baseline, scientists can also model and predict the changes in the air microbiome if temperatures were to rise by two degrees or more, said the research team.

Key discoveries

To measure the air microbiome high above the ground, the team used a specialised research aircraft from the Technische Universität Braunschweig, Germany, to collect synchronised measurements of meteorological parameters and airborne biomass samples up to a height of 3,500 metres.

The research team on the aircraft coordinated the sampling times with a team stationed at the 200-metre-high meteorological tower at the Karlsruhe Institute of Technology (KIT) in Karlsruhe, Germany.

A total of 480 vertical air samples were collected from Germany, which were brought back to Singapore to be analysed. The team was surprised to find that the composition of microorganisms above 1,000 metre was stable, independent of day or night. These air layers act as a "sink in the sky," where bacteria accumulate in higher numbers than at the ground. The team identified over 10,000 different species of airborne microbes from the samples taken above 1,000 metres.

This was very different from the air samples that were taken below 300 metres, which were shown to follow the 24-hour day and night cycle (called the diel cycle), where the air composition changes from bacteria and some fungi dominating during the day, to wood-rotting fungi dominating in the night.

The discovery of the diel cycle of airborne microorganisms was first published in PNAS in 2019[1][1], when the same research team studied the tropical air in Singapore using air samples taken at various levels of a 50-storey high-rise residential building named Pinnacle@Duxton.

In its latest study, the team also reported that atmospheric turbulence -- wind and weather -- is the primary driver of microbial aerosol dynamics, which determines how microorganisms in the air are distributed.

Driven by the day/night temperature changes, air masses become layered (stratified) at night and mixed during the day, resulting in the stratification of the air microbiome across different heights of the lower part of atmosphere.

"For the first time, meteorological and biological data of the atmosphere were measured in unison, allowing us to develop a comprehensive hypothesis about the effects of atmospheric turbulence on the dispersal of microorganisms in the lower atmosphere," said Prof Schuster.

Researchers further noticed that higher air layers contained an up-to-20-times higher concentration of radio-tolerant bacteria, which are known to withstand ionising radiation, desiccation, UV radiation, or oxidising agents. Of these bacteria, one species known as Deinococcus radiodurans is known to withstand a 1,000-fold higher radiation dose than the human body.

The team hypothesised that the ionising rays from sun and space had contributed to the development of radioactive tolerance in these bacteria at greater height, whereas bacteria on the ground have not been exposed to such levels of radiation.

Sampling for airborne life on Mars?

Based on their experiments, the researchers comment that their air sampling technologies could in principle, be used for investigating the atmosphere of neighbouring planets, such as Mars.

By tapping on the knowledge that microorganisms will aggregate in a planet's atmosphere, it could provide an alternative to the current method of sampling, which is done by a robotic vehicle drilling and collecting soil samples.

For instance, a robot with an air sampler could collect microorganisms from the atmosphere by trapping them in an air filter, and sending the filter back to earth, in a potential future Mars sample-return mission.

The air microbiome study is one of SCLESE's flagship research projects together with its research into terrestrial and aquatic ecosystems. The project was carried out over eight years, and has resulted in more than 40 papers, culminating with these results. The air microbiome research was supported by a Singapore Ministry of Education Tier 3 grant, SCELSE, and NTU.

Sustainability, climate change and the environment are key research pillars for NTU Singapore and are part of its Sustainability Manifesto launched last year. The University will continue fundamental and applied research to develop sustainable solutions that can mitigate the effects of natural disasters and climate change, and to meet the demand for food with alternative food sources.

Over the last two years during the pandemic, Prof Schuster and his team have pivoted to use their air sampling technology to detect and analyse the SARS-COV-2 virus from indoor air, a technique that demonstrated greater sensitivity than surface swab tests.

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Air pollution from wildfires, rising heat affected 68% of US West in one day

Large wildfires and severe heat events are happening more often at the same time, worsening air pollution across the western United States, a study led by Washington State University researchers has found. In 2020, more than 68% of the western U.S. -- representing about 43 million people -- were affected in one day by the resulting harmful-levels of air pollution, the highest number in 20 years.

The study, published in Science Advances, found that such widespread air pollution events are not only increasing in frequency but also persisting longer and affecting a larger geographic extent across the region. They have become so bad that they have reversed many gains of the Clean Air Act. The conditions that create these episodes are also expected to continue to increase, along with their threats to human health.

"We have seen an increasing trend in the past 20 years of days when high-levels of both particulate matter and ozone are occurring simultaneously," said lead author Dmitri Kalashnikov, a WSU doctoral student. "This is tied to two things: more wildfires and increases in the types of weather patterns that cause both wildfires and hot weather."

When wildfires and extreme heat occur at the same time, they magnify air pollution: wildfire smoke increases fine particulate matter in the air and the heat combines the smoke and other pollutants to create more ground-level ozone. While in the stratosphere ozone is protective, ozone that forms at the ground level has long been recognized as harmful to human health. It's a major component of smog, and reducing it was a major goal of clean air policies in the twentieth century. Simultaneous exposure of millions of people to high levels of both pollutants, ground-level ozone and particulate matter, poses a substantial public health burden.

Weather patterns called high-pressure ridging, more commonly known as heat domes, occur when an area of high-pressure air lingers over a region trapping warm stagnant air and its pollutants on the ground. These conditions typically lead to higher levels of harmful ground-level ozone during summer months. Particulate matter affecting air quality used to be more common in the winter in the western United States, but wildfires have flipped that dynamic, bringing the dangers of both particulate matter and ground-level ozone together at the same time in the summer.

For this study, the researchers tracked air quality by using all available monitoring station data from 2001-2020 from across the western states as well as parts of Canada. They combined this data with wildfire information derived from NASA satellites along with ERA5 weather data produced by the European Center for Medium-Range Weather Forecasts.

The co-occurring events were defined as days that registered in both the top 10% in particulate matter levels and top 10% in ozone. The researchers found that annual population exposure to these extreme combined episodes is increasing by approximately 25 millionperson-days a year- a figure that counts the number of people affected as well as the number of days they were impacted by the air pollution.

"From every indication we have, the hotter, drier conditions projected for this region are likely to increase wildfire activity and contribute to more widespread, severe heat, which means we can expect to see these conditions happen more often in the future," said co-author Deepti Singh, a WSU assistant professor. "Preparing for these events is really important. We need to think about who is exposed, what capacity there is to minimize that exposure, and how we can protect the most vulnerable people."

These events could potentially be mitigated by taking measures to slow the temperature rise caused by climate change as well as better managing wildfires, such as through prescribed burns. Aside from those efforts, Kalashnikov and Singh suggested treating these air pollution events like a severe snowstorm or heatwave by making sure people have shelters with air quality filters where they can go to get out of polluted air. They also recommended adopting policies that minimize workplace exposure for people who typically work outside.

The size of the simultaneous air pollution events will make it difficult for many people to avoid their impacts, Singh said.

"If there's such a large region that's being affected by this air pollution, it really limits where people can go to escape those conditions," she said. "You could travel a hundred miles and still not find air quality that is any better."

Read more at Science Daily

Illuminating dark matter in human DNA

Researchers at University of California San Diego have produced a single-cell chromatin atlas for the human genome. Chromatin is a complex of DNA and protein found in eukaryotic cells; regions of chromatin at key gene regulatory elements appear in open configurations within certain cell nuclei. Precisely delineating these accessible chromatin regions in cells of different human tissue types would be a major step toward understanding the role of gene regulatory elements (non-coding DNA) in human health or disease.

The findings are published online in the November 12, 2021, issue of Cell.

For scientists, the human genome, popularly called the "book of life," is mostly unwritten. Or at least unread. While science has famously put an (approximate) number to all of the protein-coding genes required to build a human being, approximately 20,000+, that estimation does not really begin to explain how exactly the construction process works or, in the case of disease, it might go awry.

"The human genome was sequenced 20 years ago, but interpreting the meaning of this book of life continues to be challenging," said Bing Ren, PhD, director of the Center for Epigenomics, professor of cellular and molecular medicine at UC San Diego School of Medicine and a member of the Ludwig Institute for Cancer Research at UC San Diego.

"A major reason is that the majority of the human DNA sequence, more than 98 percent, is non-protein-coding, and we do not yet have a genetic code book to unlock the information embedded in these sequences."

Put another way, it's a bit like knowing chapter titles but with the rest of the pages still blank.

Efforts to fill in the blanks are broadly captured in an ongoing international effort called the Encyclopedia of DNA Elements (ENCODE), and include the work of Ren and colleagues. In particular, they have investigated the role and function of chromatin, a complex of DNA and proteins that form chromosomes within the nuclei of eukaryotic cells.

DNA carries the cell's genetic instructions. The major proteins in chromatin, called histones, help tightly package the DNA in a compact form that fits within the cell nucleus. (There are roughly six feet of DNA tucked into each cell nucleus and approximately 10 billion miles in each human body.) Changes in how chromatin bundles up DNA are associated with DNA replication and gene expression.

After working with mice, Ren and collaborators turned their attention to a single-cell atlas of chromatin in the human genome.

They applied assays to more than 600,000 human cells sampled from 30 adult human tissue types from multiple donors, then integrated that information with similar data from 15 fetal tissue types to reveal the status of chromatin at approximately 1.2 million candidate cis-regulatory elements in 222 distinct cell types.

"One of the initial challenges was identifying the best experimental conditions for such a diverse set of sample types, particularly given each tissue's unique makeup and sensitivity to homogenization," said study co-author Sebastian Preissl, PhD, associate director for Single Cell Genomics at UC San Diego Center for Epigenomics, a collaborative research center that carried out the assays.

Cis-regulatory elements are regions of non-coding DNA that regulate transcription (copying a segment of DNA into RNA) of neighboring genes. Transcription is the essential process that converts genetic information into action.

"Studies in the last decade have established that sequence variations in non-coding DNA are a key driver in multi-genic traits and diseases in human populations, such as diabetes, Alzheimer's' disease and autoimmune diseases," said study co-author Kyle J. Gaulton, PhD, assistant professor in the Department of Pediatrics at UC San Diego School of Medicine.

"A new paradigm that helps explain how these noncoding variants contribute to diseases posits that these sequence alterations disrupt function of transcriptional regulatory elements and lead to dysregulation of gene expression in disease-relevant cell types, such as neurons, immune cells or epithelial cells," said co-first author Kai Zhang, PhD, a postdoctoral fellow in the Department of Cellular and Molecular Medicine. "A major barrier to unlocking the function of noncoding risk variants, however, is the lack of cell-type-specific maps of transcriptional regulatory elements in the human genome."

Ren said the new findings identify disease-trait-relevant cell types for 240 multi-genic traits and diseases, and annotate the risk of noncoding variants.

"We believe that this resource will greatly facilitate the study of mechanism across a broad spectrum of human diseases for many years to come."

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Giant leap taken in fighting antibiotic resistance

Scientists may have made a giant leap in fighting the biggest threat to human health by using supercomputing to keep pace with the impressive ability of diseases to evolve.

A new study by an international team, co-led by Dr Gerhard Koenig from the University of Portsmouth, tackled the problem of antibiotic resistance by redesigning existing antibiotics to overcome bacterial resistance mechanisms.

About 700,000 people are estimated to die every year because of antibiotic resistant bacteria, and that number is expected to rise to millions.

Without effective antibiotics, life expectancy is predicted to drop by 20 years.

The race has been on for many years to develop new antibiotics to fight disease faster than a disease can evolve.

Computers have been used in drug design for decades, but this is the first study to use a multi-pronged computer-guided strategy to make a new antibiotic from an existing one which bacteria have outwitted.

The research is published in PNAS.

Dr Koenig, a computational chemist and first author on the paper, said: "Antibiotics are one of the pillars of modern medicine and antibiotic resistance is one of the biggest threats to human health. There's an urgent need to develop new ways of fighting ever-evolving bacteria.

"Developing a new antibiotic usually involves finding a new target that is essential for the survival of a wide range of different bacteria. This is extremely difficult, and only very few new classes of antibiotics have been developed in recent times.

"We have taken a simpler approach by starting from an existing antibiotic, which is ineffective against new resistant strains, and modifying it so it's now able to overcome resistance mechanisms."

The team has shown that their best drug candidate, which is yet to undergo clinical trials, is up to 56 times more active for the tested bacterial strains than two antibiotics on the World Health Organisation's (WHO) list of essential medicines, erythromycin and clarithromycin.

Dr Koenig said: "Not only is our best candidate more effective against the tested targets, but it also shows activity against the three top ranked bacteria from the WHO priority list where the tested existing antibiotics don't work.

"It's only a matter of time until bacteria develop counterstrategies against our counterstrategies and become resistant to the new antibiotic, so we will have to keep on studying bacterial resistance mechanisms and develop new derivatives accordingly."

The hope of this new work lies in showing that the resistance mechanisms of bacteria can be addressed in a systematic way, allowing science to continually fight back with a computational evolution of new antibiotics.

Dr Koenig said: "Our computers are becoming faster with every year. So, there is some hope that we will be able to turn the tide.

"If computers can beat the world champion in chess, I don't see why they should not also be able to defeat bacteria."

The international team, including Nobel Prize laureate Ada Yonath, carried out the research at the Max-Planck-Institut für Kohlenforschung, the Weizmann Institute, and the universities of Duisburg-Essen, Bochum and Queensland.

They developed a strategy to simulate many aspects of a redesigned antibiotic at the same time, including how soluble it is, how effective it is at entering into the bacteria, and how efficient it is at blocking their protein production.

The computational work outlined in the research was done in a matter of weeks on one of the top supercomputers in Europe, but it took the international team several years to verify experimentally that their approach was indeed correct.

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