Despite intensive scientific analyses, this centaur head remains a mystery

At the National Museum in Copenhagen, Denmark, there is a marble head that was once part of the ancient Greek Parthenon temple on the Acropolis in Athens. The head originally belonged to a centaur figure and was part of a scene depicting the Greek mythological Lapiths' battle against the centaurs (mythical creatures that were half-horse, half-human).

For reasons that have yet to be explained, parts of the centaur head are coated with a thin brown film, as are several other marble fragments from the Parthenon.

The mysterious brown film was first examined by the British Museum in 1830.

Back then, attempts were made to determine if the color originated from ancient paint, but it was eventually concluded that it might be a result of a chemical reaction between the marble and the air, or that the marble contained iron particles that had migrated to the surface, coloring it brown.

Oxalic acid, algae and fungi

"There have been many attempts to explain the peculiar brown film. In 1851, German chemist, Justus von Liebig, performed the first actual scientific investigation and determined that the brown film contained oxalates -- salts of oxalic acid. This has been confirmed by later analyses, but the origin of the oxalates has remained a mystery," says Professor emeritus Kaare Lund Rasmussen, an expert in chemical analyses of historical and archaeological artifacts, Department of Physics, Chemistry and Pharmacy, University of Southern Denmark.

Along with University of Southern Denmark colleagues Frank Kjeldsen and Vladimir Gorshkov from the Department of Biochemistry and Molecular Biology, Bodil Bundgaard Rasmussen, former head of the Antiquities Collection at the National Museum of Denmark, Thomas Delbey from Cranfield University in England, and Ilaria Bonaduce from the University of Pisa, Italy, he has published a scientific article describing the results of their investigations into the brown-colored centaur head from the National Museum.

The article is published in Heritage Science, and you can find it here.

"We especially wanted to examine whether the brown film could have been formed by some biological organism, such as lichen, bacteria, algae, or fungi. This theory had been suggested before, but no specific organism had been identified. The same goes for the theory that it could be remnants of applied paint -- perhaps to protect or tone the marble surface," says Kaare Lund Rasmussen.

For their investigations, the research team was allowed to take five small samples from the back of the centaur head.

These samples underwent various analyses in SDU's laboratories, including protein analysis and so-called Laser Ablation Inductively Coupled Plasma Mass Spectrometry.

"We found no traces of biological matter in the brown layers -- only from our own fingerprints and perhaps a bird egg that broke on the marble in ancient times. This doesn't prove that there never was a biological substance, but it significantly reduces the probability, making the theory of a biological organism less probable now," says Kaare Lund Rasmussen.

Similarly, it is now less probably that the marble surface was painted or preserved, according to the researchers, who also specifically searched for traces of paint.

Ancient paints were typically based on natural products such as eggs, milk, and bones, and no traces of such ingredients were found in the brown stain alone.

The mystery remains

Through their investigations, the research team also discovered that the brown film consists of two separate layers.

These two layers are approximately equally thick, around 50 micrometers each, and they differ in terms of trace element composition.

However, both layers contain a mixture of the oxalate minerals weddellite and whewellite.

The fact that there are two distinct layers argues against the theory that they were created by the migration of material, such as iron particles, from the interior of the marble.

It also contradicts the theory that they resulted from a reaction with the air.

Air pollution is also unlikely for another reason; the centaur head has been indoors in Copenhagen since before the modern industrialization began in the 18th century.

In fact, this makes the heads at the National Museum particularly valuable compared to the marble pieces on the Acropolis, of which some have only recently been brought indoors.

"As there are two different brown layers with different chemical compositions, it is likely that they have different origins. This could suggest that someone applied paint or a conservation treatment, but since we haven't found traces of such substances, the brown color remains a mystery," concludes Kaare Lund Rasmussen.

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Reducing their natural signals: How sneaky germs hide from ants

Not only humans are social, ants are too. Group members are taking care of sick ones by providing collective hygiene measures. This presents germs with a task. They must circumvent the immunity of an individual ant and avoid the group's healthcare. A new study now published in Nature Ecology & Evolution reveals that germs develop a sneaky way to escape the ant colony's defense systems by reducing their detection cues.

Pathogens are disease-causing organisms. By natural selection, they develop evading mechanisms to outsmart the host's immune system and to get the upper hand. One way to support the immune system and fight back is medical intervention. However, this can lead to unwanted adaptions of pathogens as seen in antibiotic-resistant bacteria. Another strategy is social intervention. Some social groups like ants are trying to fight infection with "social immunity," the collective hygiene and health care measures to avoid spreading throughout the community. If and how pathogens can respond to this kind of group behavior, is still unknown.

The latest study by Professor Sylvia Cremer and her research team at the Institute of Science and Technology Austria (ISTA) shows the extraordinary effects of these kinds of host-parasite interactions. Together, with chemical ecologists at the University of Würzburg in Germany, the scientists took a close look at social ants, to see how pathogenic fungi respond to their hosts' social care intervention during infection. The results reveal that fungi reduce their chemical detection signals to outplay social immunity. The study is published today in Nature Ecology & Evolution.

More spores but less grooming

"Fungi infect the ants from the body surface and grow inside, but nestmates groom off many of the spores before they can even cause internal infection," explains Barbara Milutinović, one of the lead authors, former postdoc in the Cremer Group and now Marie Curie Sklodowska Fellow at Ruđer Bošković Institute in Croatia. The scientists set up an experiment where Argentine ants (Linepithemahumile) were infected with pathogenic Metarhizium fungi either in the absence or presence of caregiving colony members. "We found that the fungi fundamentally changed in response to the ant workers' caregiving," Milutinović continues. Over ten infection cycles, fungi which experienced grooming nestmate ants boosted their spore production compared to fungi accompanied by only individual ants. "Producing more spores will help the fungus counteract the spore-removal by helping nestmates. Yet, we were surprised to see that the ants showed less grooming against the spores," Sylvia Cremer adds. "This suggests, that the spores have become more difficult to detect by the ants."

Fungi lose their typical chemical profile

To check why ant workers had difficulties sensing fungi and to analyze possible fungal detection cues, the scientists teamed up with a chemical ecologist from the University of Würzburg. Local Professor Thomas Schmitt explains: "The fungi, that adapted to social hosts were perceived less strongly, due to a strong reduction of a fungi-specific compound called ergosterol." Ergosterol is an essential membrane compound, that all fungi have. By exposing the ants to pure fungal ergosterol or the slightly different non-fungal vertebrate equivalent, the researchers showed, that only the fungal compound induced intense grooming. Milutinović summarizes: "This demonstrates that fungal pathogens react to the presence of caregiving ants by reducing their characteristic fungal signals. They are no longer recognized as a disease threat and can escape the social immunity of the colony."

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Genome studies uncover a new branch in fungal evolution

About 600 seemingly disparate fungi that never quite found a fit along the fungal family tree have been shown to have a common ancestor, according to a University of Alberta-led research team that used genome sequencing to give these peculiar creatures their own classification home.

"They don't have any particular feature that you can see with the naked eye where you can say they belong to the same group. But when you go to the genome, suddenly this emerges," says Toby Spribille, principal investigator on the project and associate professor in the Department of Biological Sciences.

"I like to think of these as the platypus and echidna of the fungal world."

Spribille, Canada Research Chair in Symbiosis, is referring to Australia's famed Linnaean classification system-defying monotremes -- which produce milk and have nipples, but lay eggs -- that were the source of debate as to whether they were even real.

"Though nobody thought our fungi were fake, it's similar because they all look totally different."

Using DNA-based dating techniques, the team found that this new class of fungi, called Lichinomycetes, descended from a single origin 300 million years ago, or 240 million years before the extinction of dinosaurs.

David Díaz-Escandón, who performed the research as part of his PhD thesis, explains that these "oddball" fungi were previously sprinkled across seven different classes -- a high-level grouping that in animals would be equivalent to the groups called mammals or reptiles.

Working with a team of researchers from seven countries to get material from the fungi, he sequenced 30 genomes and found that all classes but one descended from a single origin.

"They were classified, but they were classified into such different parts of the fungal side of the tree of life that people never suspected they were related to each other," says Díaz-Escandón.

These fungi include forms as varied as earth tongues -- eerie tongue-shaped fungi that shoot up vertically out of the ground -- beetle gut microbes, and a fungus found in tree sap in northern Alberta. They also include some unusual lichens that survive in extreme habitats such as South America's Atacama Desert, the driest non-polar desert in the world.

"What is really fascinating is that despite these fungi looking so different, they have a lot in common at the level of their genomes," says Spribille. "Nobody saw this coming."

Based on their genomes, which are small compared with those of other fungi, the team predicts that this group of fungi depend on other organisms for life.

"Their small genomes mean this class of fungi have lost much of their ability to integrate some complex carbohydrates," said Spribille. "When we go back to look at each of these fungi, suddenly we see all of them are in a kind of symbiosis."

He notes the new research will be important to the broader study of fungal evolution, specifically how fungi inherit important biotechnological features such as enzymes that break down plant matter.

The new group also could be a source of new information about past fungal extinctions.

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Insects harbor over a thousand genes from microbes, which help them survive

Hundreds of millions of years ago, microbes and plants might have given insects an evolutionary advantage by passing genes to them through horizontal gene transfer. In a study published in the journal Cell on July 18, researchers report that more than 1,400 genes across 218 insect species, including butterflies and moths, that originated from bacteria, viruses, fungi, and plants. The study argues that these genes might have been essential for insect evolution by allowing them to develop beneficial traits in mating behavior, nutrition, growth, and adaptation to environmental changes.

Horizontal gene transfer (HGT) is fairly common between microbes. For example, bacteria use this mechanism to transmit antibiotic-resistance genes between species, but scientists more recently have been systematically looking at the phenomenon between insects and microbes or plants.

"Previous studies have shown that HGT may have contributed to insect biodiversity, but nobody knew how large a role it plays in this process," says senior author Xing-Xing Shen, an evolutionary biologist at Zhejiang University in Hangzhou, China. "Since there are a lot of high-quality insect genomes available for our analysis, I thought that now is a good time to systematically investigate how prevalent HGT is in insects."

Shen's team at Zhejiang University started this project in collaboration with Antonis Rokas, an evolutionary biologist at Vanderbilt University by gathering 218 high-quality insect genome samples representing 11 of 19 species-rich orders of insects. With the data, they were able to draw an evolutionary tree, identify out-of-place genes that are more commonly found in non-animal genomes, and examine what factors contribute to the fate of HGT in insects.

"There were HGT events everywhere we looked," says Shen. "However, we don't know whether these transfers of genes are beneficial to the insects, or even the functions for most of these genes," says Shen. He enlisted help from another expert -- Jianhua Huang, who studies insect gene functions at Zhejiang University.

"Shen walked into my office with a list of more than 1,400 genes, and we had to decide where to start," Huang says. The team decided to validate the function of the most prevalent foreign gene without known functions in insects: LOC105383139.

"This gene was horizontally introduced into nearly all moths and butterflies from a donor in the bacterial genus Listeria," they report in the study, meaning this gene has persisted in the genome since the time of moths' and butterflies' common ancestor more than 300 million years ago.

They decided to delete this ancient gene from diamondback moths, a pest affecting broccoli and cabbage, and observe what kind of functions it has. "Surprisingly, we saw those moths lacking this gene cannot produce many viable eggs," Huang says. "Then, we found that the gene influences the male courtship behavior."

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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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The Hitchhiker’s guide to the soil

The interaction of fungi and bacteria in the transport of viruses in the soil ecosystem has been examined by a UFZ research team in a study recently published in the journal of the International Society for Microbial Ecology (ISME Journal). The scientists showed a novel mechanism of viral transport by bacterial shuttles traveling along fungal hyphae. Bacteria thereby benefit from taking along viruses on the conquest of new habitats.

There are up to one billion viruses in just one gram of soil. However, little is known about their influence on the nutrient and carbon cycle in the soil ecosystem. Soils can sometimes be inhospitable places. Dry zones and air-filled soil pores are almost impossible obstacles for bacteria and viruses. In order for them to move around -- for example, to get to a place with better conditions -- they need water. But the situation is not completely hopeless. Because there is an excellently developed infrastructure in the soil: the fungal network. Fungi are always in search of water and nutrients. To do this, they form hyphae, long, thin threads that run through the soil as a widely branched network. Fungi are thus able to bridge dry and nutrient-poor zones.

In an earlier study, UFZ researchers showed that soil bacteria use the mucus-covered fungal hyphae in order to move around on them and thus reach new food sources. In their current study, the research team led by environmental microbiologist Dr. Lukas Y. Wick has now been able to identify another beneficiary of the underground fungal network. "Phages, i.e. viruses that have bacteria as their sole target, also travel this fungal highway," says Wick. "Not independently but rather by hitching a ride with bacteria. Physical forces cause the viruses to adhere to the surface of bacteria -- much like mussels adhere to the hull of a ship." In this way, viruses hitch a ride through the soil -- until they arrive at a place that is better suited for them. But what exactly is a good place for soil-dwelling viruses?

"Wherever the host bacteria of the viruses are found," says Wick. "Not every phage can infect every bacterium," says Wick. "Because of a kind of lock-and-key principle, phages can smuggle their genetic material only into their respective host bacteria." If this succeeds, the bacterium is reprogrammed to produce new phages. The bacterial cell then bursts, thereby releasing the phages of the next generation. These can then once again infect new host bacteria. "The phages are highly efficient at this. This obviously also gives the shuttle bacteria a real advantage," says Wick. "We were able to show that soil bacteria with phages attached to them were able to spread far better in their new location than bacteria without this viral baggage."

It is well known from macro-ecology that migratory species can cause problems for the established residents of a habitat. Also that invasive species can bring pathogens that increasingly contribute to the displacement of native species. The UFZ research group therefore interpreted their data using MAFIA (MAecological Framework of Invasive Aliens), a well-known model of invasion ecology. "With our fungus-bacteria-phage system, we were able to detect the same invasion patterns on a micro-scale as we did in the macro-ecological system," says Wick. "And because our microbial laboratory model can be quickly and easily sampled and modified, it could be used as a model system to answer various questions and hypotheses in invasion ecology -- such as the transport of pests or pathogens."

For their studies, the research team recreated a micro-attack of bacteria and phages in the laboratory. For this purpose, two zones with culture medium were used. These were connected to each other only via fungal hyphae. "In Zone A, we used typical soil bacteria as shuttles as well as phages that cannot harm this bacterial species," explains Xin You, first author of the study and PhD student at the UFZ Department of Environmental Microbiology. "Zone B was colonised with a phage-specific host bacterium." In different experimental approaches, the research team had the shuttle bacteria travel along the fungal hyphae highway with and without viral baggage. "The result was clear: the bacteria-phage duo had a clear advantage in the invasion of Zone B," says You. "The shuttle bacteria benefited from the power of the phages, which effectively disabled their host bacteria and thus also eliminated food competition for the invading bacteria."

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Fungal outbreak in marine mammals began on land

In the early 2000s, a fungus infected hundreds of animals and people in British Columbia and Washington State. Scientists found that the disease also killed porpoises and dolphins in the Salish Sea-perhaps affecting cetaceans even earlier than people.

A study published today in Diseases of Aquatic Organisms explores how human-caused changes on land can affect aquatic animals, specifically in the case of the fungal pathogen, Cryptococcus gattii. Led by the University of California, Davis, a team of scientists from Canada and the Pacific Northwest pieced together the history of the fungal outbreak in marine mammals. They assembled and analyzed data collected over decades by veterinarians, microbiologists, marine mammal biologists, and marine mammal stranding responders.

C. gattii can cause lung and brain disease. It lives in soil and in tree dwellings and is acquired by breathing in fungal spores. It is not considered contagious between individuals. Typically found in tropical and subtropical forests paralleling the distribution of eucalyptus trees, C. gattii was likely translocated to the Pacific Northwest in the early 1900's, although the exact mechanisms are unknown.

Beginning in 1999 on Vancouver Island, humans, domestic animals, and terrestrial wildlife became infected with C. gattii, progressively affecting individuals living on mainland British Columbia, Washington, Oregon, and California. The researchers found that 42 dolphins and porpoises in the Salish Sea also died from the fungal pathogen, including harbor porpoises, Dall's porpoises, and Pacific white-side dolphins.

Construction, deforestation, and other activities that disturb soil can aerosolize C. gattii spores, causing infection in people and animals that live near the disturbed sites and breathe in the spores.

"As we change the environment in unprecedented ways, we could see more diseases that affect people and wildlife," said lead author Sarah Teman, a research assistant at the SeaDoc Society, a program of the Karen C. Drayer Wildlife Health Center at the UC Davis School of Veterinary Medicine.

The marine mammals that died from C. gattii were found near terrestrial hotspots, suggesting that the spores settled on the surface of the sea, where the porpoises and dolphins inhaled them when they surfaced to breathe.

Researchers also found evidence that the first probable case of C. gattii in the Pacific Northwest could have occurred in a Dall's porpoise in 1997 -- two years before the identification of the first human case in the region in 1999.

"Often we study marine mammals because they play important roles in the ecosystem, and they are cool," said Joe Gaydos, UC Davis wildlife veterinarian at SeaDoc Society and co-investigator. "Too often we forget that they can also alert us to diseases that affect humans."

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Secret garden: Drug-resistant pathogen strains meet and evolve on plant bulbs

Just when we thought it was safe to go to the local garden center, researchers from Japan have discovered that fungicide-resistant strains of a nasty pathogen have been getting up to no good among the tulip bulbs.

In a study published in August in Environmental Microbiology researchers from the University of Tsukuba and Chiba University have revealed that plant bulbs harboring a potentially lethal pathogen also make the perfect lab for evolving fungicide-resistant strains.

The risk associated with fungal infections is increasing, with occurrences of pulmonary aspergillosis (PA), a deadly fungal infection caused by the human pathogen Aspergillus fumigatus, rising globally. Of particular concern are influenza-related PA and COVID-19-related PA, the case numbers of which are growing quickly. Azoles -- a class of antifungal compounds often used as antifungal drugs to treat aspergillosis -- are also widely used as agricultural fungicides. Azole-resistant strains of A. fumigatus are spreading in the environment, potentially promoted by agricultural azole use. Azole resistance is a factor known to affect the treatment of PA, and there is concern that this problem is only worsening.

"Understanding how the genetic variation linked with azole resistance in A. fumigatus strains is distributed and enriched in the environment is necessary for suppressing resistant strains," says senior author of the study Daisuke Hagiwara. "In this study, we set out to do this by investigating the genetics of those strains."

Previously, the research team found several azole-resistant A. fumigatus strains attached to imported plant bulbs for sale in Japanese gardening shops. In this study, they investigated eight strains of azole-resistant A. fumigatus isolated from a single tulip bulb bought in Japan. The researchers used genome sequencing and comparative analysis, and compared the strains for sensitivity to agricultural and medical azoles, in addition to other classes of fungicides. The results indicated that there had previously been genetic recombination between the strains, and that some of them exhibited tolerance to other fungicide classes.

"Our results show that plant bulbs provide not just a vehicle for this pathogen, but also an ideal niche for its strains to encounter each other, and to evolve their resistance to drugs," says Hagiwara.

This study fills gaps in the knowledge of azole-resistant A. fumigatus, providing important information on the genetics behind an urgent global One Health challenge. The research team's findings will inform a deeper understanding of drug-resistant fungi and help with the development of future solutions to this problem.

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Climate warming can influence fungal communities on oak leaves across the growing season

Climate warming plays a larger role than plant genes in influencing the number and identity of fungal species on oak leaves, especially in autumn. Recently published in the journal New Phytologist, this research by ecologists sheds light on how warming and tree genes affect the dynamics of fungal communities across the season.

"One of our major findings was that elevated temperature decreased the number of fungal species and changed their community composition, especially in the late season" says Maria Faticov, a researcher at the Department of Ecology, Environment and Plant Sciences (DEEP) at Stockholm University.

Plants host thousands of microscopic organisms and leaves are no exception. Leaves harbour a large diversity of microorganisms including fungi, bacteria and, less frequently, archaea. Fungi are among the most diverse groups of microorganisms living on leaves. Some of these microscopic fungi cause disease, others can promote plant growth and defend leaves against biotic and abiotic stresses, and still others play an important role in leaf senescence and decomposition.

Climate is one of the main factors influencing fungal development, either directly or indirectly, by triggering plant defences.

"From earlier studies, we know that the number of fungal species and their abundance change as leaves age and the season progresses from spring to autumn. What we do not know is what role climate warming and plant genetic variation play in shaping fungal communities across the growing season" says Ayco Tack, associate professor at the Department of Ecology, Environment and Plant Sciences, Stockholm University.

To answer this question, researchers took on a challenging project -- they built 6 identical cages in a field to the north of Stockholm, each cage the size of a small living room. Scientists put 132 young oak trees into the cages that represented 5 different genotypes. Half of the cages were heated from May to October using ceramic heaters. The remaining ones were left as control and did not have heaters in them. The temperature in the heated cages was increased by ca 2°C to mimic the global temperature increase predicted by scientists to occur by the end of the century. Researchers collected leaves in the early, middle and late growing season and used DNA sequencing to find out which fungi had colonised the leaves. This way they could compare the changes in fungal community structure between the control and warming treatment and also among oak genotypes.

"We observed that fungal community composition drastically changed from spring to autumn, with yeasts increasing in relative abundance and fungal pathogens decreasing. Interestingly, while experimental warming had a major impact on the fungal community, oak genotype explained only a minor part of the variation in the number of fungal species and their composition" says Maria Faticov.

These findings suggest that warming is one of the most important environmental factors shaping fungal community development during the growing season and emphasizes how profound the effects of ongoing climate change may be to plant health and ecosystem functioning.

Researchers did not link the observed change in fungal community structure under warming with plant health and ecosystem functioning. More detailed long-term experiments are needed to predict how changes in the fungal community under climate warming will influence the plants they live on and their surrounding environment.

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Superficial relationship: Enzymes protect the skin by ignoring microbes and viruses

The human body is constantly exposed to various environmental actors, from viruses to bacteria to fungi, but most of these microbial organisms provoke little or no response from our skin, which is charged with monitoring and protecting from external dangers.

Until now, researchers weren't quite sure how that happened -- and why our skin wasn't constantly alarmed and inflamed.

In a study published May 21, 2021 in Science Immunology, scientists at University of California San Diego School of Medicine identify and describe two enzymes responsible for protecting our skin and body's overall health from countless potential microbial intruders. These enzymes, called histone deacetylases (HDACs), inhibit the body's inflammatory response in the skin.

"We have figured out why we tolerate certain microbes living on our skin, while the same bacteria would make us very sick if exposed elsewhere in the body," said Richard Gallo, MD, PhD, Ima Gigli Distinguished Professor of Dermatology and chair of the Department of Dermatology at UC San Diego School of Medicine. "In our research, we identified enzymes that act on the chromosome of specific skin cells that provide immune tolerance by the skin.

"Without these enzymes telling our cells to ignore certain bacteria, we'd have a constant rash on our skin."

Gallo and colleagues say the potential mechanism for how the environment can interact and alter cell function is through epigenetic control of gene expression. Within the skin cells, proteins called toll-like receptors (TLRs) allow the cells to sense their surroundings and potential dangers.

In most organs, TLRs act as a warning system that triggers an inflammatory response to threats. But in skin cells, the two identified HDAC enzymes, HDAC8 and HDAC9, inhibit the inflammatory response.

"This is one of the first demonstrations of how the microbiome can interact with epigenetic factors in the skin and modulate the skin's behavior through the inflammatory response," said George Sen, PhD, associate professor of dermatology and cellular and molecular medicine at UC San Diego School of Medicine. "Whatever environment we're facing can change a person's specific response to it. Since this epigenetic change is reversible, unlike alterations to our DNA, we can potentially control our skin inflammatory response through targeting of these enzymes."

The research was initially conducted in mouse models in which HDAC8 and HDAC9 had been genetically knocked out. As a result, the mice's skin could not tolerate microbial or viral exposures, resulting in a heightened immune reaction. The team then reproduced the findings with human cells in a culture dish.

Gallo said the work could change how doctors treat certain types of skin inflammation or other dermatologic conditions.

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Scientists identify two new species of fungi in retreating Arctic glacier

Two new species of fungi isolated from sediments and soil in the Canadian Arctic (A)micrographic image of Vishniacozyma ellesmerensis (B) colonies of V. ellesmerensis (C) micrographic image of Mrakia hoshinonis (D) colonies of M. hoshinonis.

Two new species of fungi have made an appearance in a rapidly melting glacier on Ellesmere Island in the Canadian Arctic, just west of Greenland. A collaborative team of researchers from Japan's National Institute of Polar Research, The Graduate University for Advanced Studies in Tokyo, Japan, and Laval University in Québec, Canada made the discovery.

The scientists published their results on DATE in two separate papers, one for each new species, in the International Journal of Systematic and Evolutionary Microbiology.

"The knowledge of fungi inhabiting the Arctic is still fragmentary. We set out to survey the fungal diversity in the Canadian High Arctic," said Masaharu Tsuji, a project researcher at the National Institute of Polar Research in Japan and first author on both papers. "We found two new fungal species in the same investigation on Ellesmere Island."

One species is the 10th to join the genus Mrakia, with the proposed name M. hoshinonis, in honor of Tamotsu Hoshino, a senior researcher at the National Institute of Advanced Science and Technology in Japan. Hoshino has made significant contributions to the study of fungi in polar regions. The other species is the 12th to join the genus Vishniacozyma, with the proposed name V. ellesmerensis as a nod to the island where it was found. Both species are types of yeast that are well-adapted to the cold and can even grow below 0°C.

The samples of fungi were collected from the unofficially named Walker Glacier. The designation comes from Paul T. Walker, who installed the datum pole that measures the glacier's growth and shrinkage, in 1959. At the time of sample collection in 2016, measurements showed that the glacier was receding at a rate two-and-a-half times faster than its retreat over the previous 50 years.

"Climate-related effects have been observed in this region over the last 20 years," Tsuji said. "Soon, some of the glaciers may completely melt and disappear."

Only about five percent of fungi species have been discovered, but their function across ecological climates is well understood -- from the tropics to the Arctic, fungi decompose dead organic material. Each species operates a little differently, but their general role is to reintroduce nutrients from dead plant material back into the ecosystem. If the glaciers melt, the fungi lose their habitat. The results could have catastrophic knock-on effects throughout the ecosystem, according to Tsuji, although more research is needed to understand exactly how the changing climate is influencing fungi beyond destroying their habitat.

Next, Tsuji and his team plan to survey the fungi in Ward Hunt Lake, the northern most lake in the world. It is on Ward Hunt Island, just off the northern coast of Ellesmere Island, and less than 500 miles from the North Pole.

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