Culture

Through molecular espionage, a particular receptor (known as AhR) allows its host’s immune response to stay one step ahead of infection; it achieves this by listening in on the inter-cellular transmissions that bacterial pathogens use to collectively coordinate an invasion. The results – shown in human cells, zebrafish and mice – uncover how this counterintelligence operation allows the host to fine-tune physiologically costly immune defenses against Pseudomonas aeruginosa infection, a highly common bacterial pathogen. The findings could pave the way toward new antimicrobial substances tailored to specific pathogens. P. aeruginosa is an omnipresent, exceptionally resilient and highly opportunistic bacterium that causes infectious diseases in a wide variety of plants and animals. In humans, it is responsible for a spectrum of illnesses, including several hospital-acquired infections that can have serious – and sometimes fatal – outcomes, particularly in those with compromised immune systems. However, what makes P. aeruginosa infections so uniquely difficult to treat is the bacterium’s profound antibiotic resistance. Many pathogens use “quorum sensing” (QS), a small molecule cell-to-cell communication mechanism that allows the bacteria to rapidly adapt to changing conditions and coordinate their behavior throughout an infection. While the host sensor AhR is known to recognize QS molecules, their role in monitoring and responding to infection dynamics is poorly understood. Using both in vitro and in vivo models, Pedro Moura-Alves and colleagues demonstrate that P. aeruginosa quorum, expressed during infection, bind to the AhR and distinctly modulates its activity depending on the relative abundance of different QS molecules. According to Moura-Alves et al., this enables the host to sense the size of the bacterial community, monitor infection dynamics and respond accordingly by mobilizing the most appropriate defense mechanism according to the severity of the threat.

Recent and rapid developments in the biosciences continually blur the lines between human beings and other living organisms, while straining the legal definitions of what is or is not human. In a Policy Forum, Bartha Maria Knoppers and Henry Greely propose the use of "substantially human" as a legal boundary to describe living organisms that are human in their characteristics, but not entirely so. It would help courts, scientists and physicians to be flexible in the legal determinations of emerging biotechnologies of the future, they say. While both the law and ethics view living human beings and their constituent parts (e.g. tissues or organs) as being special and different, "bioscientific advancements are quietly nibbling away at the classical legal boundaries that form the bedrock of the normative structures upon which our societies are based," write Knoppers and Greely. Attempts to reclassify the legal boundaries of humans, living humans or human tissues are often threatened by reductionism. For example, some argue that the human genome defines "humans," but according to the authors, there is no single defined "human genome" - each is unique and everchanging with each generation. Similarly, xenotransplantations, human/non-human chimeras, organoids, and revived "dead" tissues blur the lines between that of "human life" and a legally recognized individual. Rather than starting anew and redefining fundamental legal concepts, the authors argue that the traditional approaches should continue to be flexibly applied and that being "substantially human" serves as a good starting point for determining the legal rights and obligations of being "human."

Scientists have discovered remnants of the world's oldest fossil forest in a sandstone quarry in Cairo, New York.

It is believed the extensive network of trees, which would have spread from New York all the way into Pennsylvania and beyond, is around 386 million years old.

This makes the Cairo forest around 2 or 3 million years older than what was thought to be the world's oldest forest at Gilboa, also in New York State and around 40 km away from the Cairo site.

The new findings, which have been published today in the journal Current Biology, have thrown new light on the evolution of trees and the transformative role they played in shaping the world we live in today.

A team led by scientists at Binghamton University, New York State Museum and Cardiff University have mapped over 3,000 square meters of the forest at the abandoned quarry in the foothills of the Catskill Mountains in the Hudson Valley.

Their investigations showed that the forest was home to at least two types of trees: cladoxylopsids, primitive tree-fern-like plants, which lacked flat green leaves, and which also grew in vast numbers at Gilboa; and Archaeopteris, which had a conifer-like woody trunk and frond-like branches which had green flattened leaves.

A single example of a third type of tree was also uncovered, which remained unidentified but could possibly have been a lycopod.

All these trees reproduced using only spores rather than seeds.

The team also reported a 'spectacular' and extensive network of roots which were more than eleven meters in length in some places which belonged to the Archaeopteris trees.

It is these long-lived woody roots, with multiple levels of branching and small, short-lived perpendicular feeder roots, that transformed the interactions of plants and soils and were therefore pivotal to the co-evolution of forests and the atmosphere, the researchers state.

Until this point in time, trees such as the cladoxylopsids only had ribbon-like and mostly unbranched roots which had to be constantly replaced as the plant above ground grew.

They believe the forest was eventually wiped out by a flood due to the presence of many fish fossils that were also visible on the surface of the quarry.

"It is surprising to see plants which were previously thought to have had mutually exclusive habitat preferences growing together on the ancient Catskill delta," said co-author of the study Dr Chris Berry from Cardiff University's School of Earth and Ocean Sciences.

"This would have looked like a fairly open forest with small to moderate sized coniferous-looking trees with individual and clumped tree-fern like plants of possibly smaller size growing between them."

The research team say that the Cairo forest is older than the one at Gilboa because the fossils were lower down in the sequence of rocks that occur in the Catskill mountains.

"In order to really understand how trees began to draw down carbon dioxide from the atmosphere, we need to understand the ecology and habitats of the very earliest forests, and their rooting systems," continued Dr Berry.

"These remarkable findings have allowed us to move away from the generalities of the importance of large plants growing in forests, to the specifics of which plants, in which habitats, in which types of ecology were driving the processes of global change. We have literally been able to drill into the fossil soil between the trees and are now able to investigate geochemical changes to the soil with our colleagues at Sheffield University.

"We are really getting a handle on the transition of the Earth to a forested planet."

What The Study Did: This study (called a systematic review and meta-analysis) combined results from 14 randomized clinical trials to evaluate evidence of an association between acupuncture and acupressure for reducing pain in patients with cancer. Previous studies have had inconsistent findings.

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

Authors: Haibo Zhang, M.D., of Guangdong Provincial Academy of Chinese Medical Sciences in Guangzhou, China, and Charlie Changli Xue, Ph.D., of RMIT University in Melbourne, Australia, were the corresponding authors.

(doi:10.1001/jamaoncol.2019.5233)

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

How successfully a person can fend off the flu depends not only on the virus' notorious ability to change with the season, but also on the strain first encountered during childhood, according to new research published in the open-access journal PLoS Pathogens.

The findings offer an explanation for why some patients fare much worse than others when infected with the same strain of the flu virus. The results also could help inform strategies aimed at curbing the impact from the seasonal flu.

"The last two flu seasons have been more severe than expected," says study co-author Michael Worobey, head of the Department of Ecology and Evolutionary Biology and a member of the BIO5 Institute at the University of Arizona. "In the 2017-18 season, 80,000 people died in the U.S., more than in the swine flu pandemic of 2009. Influenza is a major, major killer - not just in this country, but worldwide."

For decades, scientists and healthcare professionals were vexed by the fact that the same strain of the flu virus affects people to various degrees of severity. Then, in 2016, a team including Worobey and authors of the current study presented a paper in the journal Science showing that past exposure to the flu virus determines an individual's response to subsequent infections, a phenomenon called immunological imprinting.

The discovery helped overturn the prior commonly held belief that previous exposure to a flu virus conferred little or no immunological protection against strains that can jump from animals into humans, such as those causing the so-called swine flu or bird flu. These strains, which have already caused hundreds of spillover cases of severe illness or death in humans, are of global concern because they could gain mutations that allow them not only to readily jump from animal populations to humans, but also spread rapidly from person to person.

In the current study, the researchers set out to investigate whether immunological imprinting could explain people's response to flu strains already circulating in the human population and to what extent it could account for observed discrepancies in how severely the seasonal flu affects different age groups.

The team analyzed health records that the Arizona Department of Health Services routinely obtains from hospitals and private physicians to track flu cases to study how different strains of the flu virus affect people at different ages.

Two subtypes of influenza virus, H3N2 and H1N1, have been responsible for seasonal outbreaks of the flu over the last several decades. H3N2 causes the majority of severe, clinically attended cases in high-risk elderly cohorts and the majority of overall deaths. H1N1 causes fewer deaths overall and skews more toward young and middle-aged adults.

The health record data revealed a pattern: People first exposed to H1N1 during childhood were less likely to end up hospitalized if they encountered H1N1 again later in life than people who were first exposed to H3N2. Conversely, those first exposed to H3N2 enjoyed extra protection against H3N2 later in life.

To understand the discrepancy, the researchers dug into the evolutionary relationships between influenza virus strains. H1N1 and H3N2, it turned out, belong to two separate branches, or groups, on the influenza "family tree." While infection with one does result in the immune system being better prepared to fight a future infection from the other, the protection against future infections is much stronger when exposed to strains from the same group it has battled before.

"In other words, if you were a child and had your first bout of flu in 1955, when the H1N1 but not H3N2 virus was circulating, an infection with H3N2 was much more likely to land you in the hospital than an infection with H1N1 last year, when both strains were circulating," Worobey says.

But the records also revealed another pattern, one that was much more difficult to explain: People whose first childhood exposure was to H2N2, a close cousin of H1N1, did not have a protective advantage when they later encountered H1N1. This seemed strange, as the two subtypes are in the same group, and the researchers' earlier work showed that exposure to one can, in some cases, grant considerable protection against the other.

"Our immune system often struggles to recognize and defend against closely related strains of seasonal flu, even though these are essentially the genetic sisters and brothers of strains that circulated just a few years ago," says lead author Katelyn Gostic, who conducted this research as a doctoral student in the lab of the paper's senior author, James Lloyd-Smith, at the University of California, Los Angeles. "This is perplexing because our research on bird flu shows that deep in our immune memory, we have some ability to recognize and defend against the distantly related, genetic third cousins of the strains we saw as children."

"Clearly, something compromises the immunity to strains that you see secondarily, even if they belong to the same group as your first exposure," Worobey adds. "The second subtype you're exposed to is not able to create an immune response that is as protective and durable as the first."

In other words, our ability to fight off the flu virus is determined not only by the subtypes we have encountered over the course of our lives, but also by the sequence in which we have encountered them.

"Whichever subtype our immune system sees first lays down an imprint that protects us especially well against strains of the same subtype," Worobey says, "but relatively poorly against strains from other subtypes, even though you've encountered those subsequently."

The molecular causes of this effect are currently being studied, according to the researchers.

"Part of your immune system's response to current infection is directed against the strain you first had as a kid, and that investment of fighting the last war appears to compromise your ability to form a fully effective immune response to the invader you encounter later," Worobey says.

The researchers hope that their findings may help predict which age groups might be severely affected during future flu seasons based on the subtype circulating, which in turn may help health officials prepare an adequate response, such as doling out limited vaccines by cohort.

"These findings provide insight into the patterns we see in our flu surveillance and how they might change in the future," says Shane Brady, Deputy State Epidemiologist at the Arizona Department of Health Services in Phoenix. "This highlights the importance of collaboration between public health practitioners and researchers."

The study adds to earlier work by the same group that has made the concept of immunological imprinting a key part of the long-term battle against flu and one of the foundations of the National Institutes of Health's strategic plan to develop a universal flu vaccine.

"We hope that by studying differences in immunity against bird flus, where our immune system shows a natural ability to deploy broadly effective protection, and against seasonal flus, where our immune system seems to have bigger blind spots, we can uncover clues useful to universal influenza vaccine development," Gostic says.

"We need a vaccine that targets the deficits on an individualized level," Worobey says. "Our work has clearly shown that the first virus we had can have a profound long-term effect. The bad side of that is that our immune system seems to be locked into fighting just one half of flu genetic diversity, and we need to find ways of breaking that."

Glutamine could help people with obesity reduce inflammation of fat tissue and reduce fat mass, according to a new study at Karolinska Institutet in Sweden and the University of Oxford in the U.K. The researchers also show how glutamine levels can alter gene expression in several different cell types. However, more research is needed before glutamine supplementation may be recommended as a treatment for obesity. The study is published in the journal Cell Metabolism.

Glutamine is an important amino acid with many key functions such as providing energy and maintaining good intestinal health. It also has anti-inflammatory effects on for example white blood cells and T-cells that are important for the immune system.

In the current study, the researchers examined how the metabolic processes differed in fat tissue collected from the abdomen of 52 obese and 29 non-obese women. They identified glutamine as the amino acid that displayed the largest differences when comparing the two groups. People with obesity had on average lower levels of glutamine in their fat tissue than normal-weight people. Lower glutamine-levels were also associated with larger fat cell size and higher body fat percentage independently of body-mass index (BMI), according to the study.

"Our results suggest that treatment with glutamine could be of value against obesity and insulin resistance," says Mikael Ryden, professor and senior physician at the Department of Medicine in Huddinge, Karolinska Institutet, and the study's corresponding author. "We know, however, that glutamine is also important for cell division and the metabolism of cancer and therefore, more research on possible long-term side effects is needed before glutamine may be recommended as a dietary supplement to help treat obesity and its complications."

The researchers also showed through a combination of animal and cell analyses that glutamine levels influenced the expression of different genes and that low glutamine levels induced an increase in the expression of pro-inflammatory genes in the fat tissue. Obese mice injected with glutamine for two weeks had less fat tissue inflammation than mice who received a control saline solution. Their body fat mass, fat cell volume and blood glucose levels were also reduced. In an analysis of cultured human fat cells, the expression of pro-inflammatory genes and the lipid content were attenuated after incubation with increasing concentrations of glutamine. The largest effect was observed after treatment with 5-20 millimolar (mM) glutamine for 11 days, according to the study.

The researchers also studied in detail what happens inside the fat cell when glutamine levels are altered. They found that glutamine impacts a mechanism called O-GlcNAcylation that can control epigenetic changes, that is changes in gene expression caused by environmental and lifestyle factors rather than by alterations in our underlying DNA sequence. People with obesity had higher levels of O-GlcNAcylation in their fat tissue while mice and human cells treated with glutamine had lower levels of O-GlcNAcylation in the cell nucleus.

"Our study shows that glutamine is anti-inflammatory in the fat tissue by changing the gene expression in several different cell types," says Mikael Ryden. "This means that a lack of glutamine, which may occur during long-term obesity, could lead to epigenetic changes that fuel inflammation in the body."

Further research is needed to fully understand which genes and cellular processes are affected the most, according to the researchers.

How mammals perceive light changes between night and day. Researchers at Aalto University and the University of Helsinki discovered that mice were better at finding a dim light in pitch-darkness in experiments done at night time compared to ones done during the day time. The scientists were surprised to find that this effect had very little to do with any changes in the eye itself, and was instead controlled by how the mice actually searched for light in the dark, and how their brains processed signals at night vs. day. The results are exciting for neuroscientists interested in how animals and humans can see, and biologists interested in how the time of day alters our bodies, including sensory processing.

Many types of animals behave differently during day and night time. While the "body clock" has long been known, its effect on how different parts of the body function still aren't fully understood. For instance, researchers knew that the retina, the part of the eye that detects light, has its own circadian rhythm. The team at Aalto and Helsinki Universities were interested in seeing if the eye's internal clock affected vision, so they modified one of their previous experiments to find out.

'Our research group is able to link if a mouse can find a dim light in the dark to the mouse's underlying retinal nerve signals at the sensitivity limit of vision.' said Professor Petri Ala-Laurila, the research group leader. 'This allowed us to explore how the day/night cycle changes the mouse's visual capability, both down in the neural circuit level and all the way up to behaviour responses at the sensitivity limit of vision'

Finding your way in a pitch-dark maze

Earlier this year, Professor Ala-Laurila's group demonstrated how the eyes of mice detect faint light in near-total darkness. This allowed them to link the mammalian visually-guided behaviour to individual neural impulses, an important world-first for neuroscience. The experiment involved placing a mouse in a maze in total darkness, with a faint light next to the exit of the maze. The mouse is trained to know that the light leads to the way out. They repeated this experiment for this new study, doing some of the tests during the day, and some during the night. They observed that the behaviour change - the mice were better at spotting the light at night than during the day. They were expecting this result, but they also observed that the nerve impulses leaving from the retina themselves did not cause the difference, which was a surprise.

So, if the nerve signals from the eyes aren't changing, how could the mice be seeing better at night? The researchers were able to answer this using their new laboratory set up. A big part of the technique invented by the group at Aalto involves using high-tech night vision cameras and their own deep-learning based software to accurately track how the animals moved, and what they could see. The team observed that during the night time experiments, the mice searched for the light more effectively by scanning the environment for example by turning around more. Once the night group learned this behavioural strategy after searching at night, they were then also able to use it during the day, solving the maze puzzles quicker in day experiments than identical mice who'd never attempted it at night.

'Previously, it had not been possible to measure behaviour as accurately as our group now can, so researchers had to treat mice as having a predefined set of behavioural rules in experiments like this. It's exciting to now show that even in the simplest of tasks - finding a light in the dark - animals can use vastly different behavioural strategies and, what's more, we are able to quantify day/night differences in them.' said Sanna Koskela, a PhD student at Helsinki University and the first author of the paper in Current Biology which published the results.

Internal Clock effects on the eye

The team now hope to further investigate the effects the circadian rhythm has on the eye. Although this specific test doesn't appear to show any signal effects from time of day, it is just one of many visual tasks the eye can perform at low light level, and others may yet still show circadian influence.

'We now have a remarkable opportunity to study sensory performance from the retina to behaviour in dim light, including things like how circadian rhythm controls it. Our next set of experiments will explore how the brain processes weak signals originating from increasing and decreasing light intensities in the retina at different times of day and night. This will help us understand more deeply how mammals see at low light levels.' said Professor Ala-Laurila

With their algorithm for material-property prediction, Dr. Yury Lysogorskiy and Dr. Thomas Hammerschmidt of the Interdisciplinary Centre for Advanced Materials Simulation Icams of Ruhr-Universität Bochum (RUB) won the second place in an international competition on machine learning. The secret of their success was the combination of data analytics with physical models and with properties of the chemical elements that potential materials for solar cells and touchscreens are made of. The algorithm from Bochum, as well as the first-place solution from Yokohama, Japan and the third-place solution from London, Great Britain have been published in the journal NPJ Computational Materials of 18 November 2019.

Crystal-structure prediction for materials

The applied methods were originally developed for the simulation of metallic alloys. For this competition, the researchers adapted the methods for the prediction of the structural stability and the optical properties of transparent conductors. "These materials that are used for example in touchscreens are composed of the chemical elements Aluminium, Gallium, Indium and oxygen," explains Thomas Hammerschmidt. By variation of the chemical composition the material properties can be tuned for the technological application.

Assess general suitability

For the competition that was released by the European Centre of Excellence Nomad and the internet-platform for machine-learning competitions Kaggle, a data set of results from quantum-mechanical calculations was made available. A second set of data was kept secret. The algorithms should be trained on the first set of data to predict the second set as accurately as possible. "This technological competition was about the performance and the comparability of different solution approaches," say Yury Lysogorskiy and Thomas Hammerschmidt.

Approach is transferable

„There is a variety of different approaches to perform specific predictions for certain chemical compositions," the researchers explain. "We were interested how transferable our approach is to different material classes and problem cases". The Bochum solution incorporated results of previous works at Icams, particularly physically motivated descriptors of the local atomic environment of the atoms in the crystal lattice.

Regulatory T cells (Tregs)* prevent excessive immune reactions in healthy people. In the development of autoimmune type 1 diabetes, this protection is not sufficiently effective. Researchers at Helmholtz Zentrum München and LMU Munich have now deciphered a mechanism that impairs Treg differentiation and stability. In the study, when they inhibited the molecule that triggers this mechanism, an increased number of functional Tregs were formed again and autoimmune activation was reduced. This may represent a new molecular target to delay or even prevent the development of type 1 diabetes. The study was carried out within the framework of the German Center for Diabetes Research (DZD), and the results have now been published in Nature Communications.

Type 1 diabetes is the most common metabolic disease in children and adolescents. In this autoimmune disease, the body's own immune cells gradually destroy the insulin-producing beta cells in the pancreas. Normally, regulatory T cells (Tregs) prevent an attack on the body's own cells. However, during the development of type 1 diabetes, this protection is insufficient. The team led by Professor Carolin Daniel is investigating why this is the case. She is research group leader at the Institute of Diabetes Research (IDF) at Helmholtz Zentrum München, scientist in the DZD and professor for immune modulation at Ludwig- Maximilians-Universität in Munich. The researchers have now deciphered a molecular mechanism that during an early phase of type 1 diabetes leads to the formation of decreased numbers of functional Tregs.

Elevated levels of miRNA142-3p contribute to the development and progression of autoimmunity

The microRNA miRNA142-3p plays a decisive role in this process. MicroRNAs can suppress the expression of individual genes. "During the development of autoimmunity in type 1 diabetes, we were able to detect an increased abundance of miRNA142-3p. This leads to a reduced expression of the protein Tet2 in T-helper cells," said first author Martin Scherm. As a consequence, faulty epigenetic changes occur in the Foxp3 gene of the regulatory T cells. A decreased number of these important immune cells are formed, and the Tregs are no longer as stable. "Our research results show a direct link between miRNA142-3p and the impaired function of regulatory T cells, which subsequently contributes to the development and progression of autoimmunity," said last author Carolin Daniel, summarizing the results of the this study.

New target for future intervention strategies

In order to investigate whether the findings could also open up new therapeutic approaches in the future, the scientists specifically blocked the miRNA142-3p molecule. This improved the formation and stability of the regulatory T cells. In the animal model, the autoimmune response to the insulin-producing beta cells also decreased.

"The detailed investigation of the underlying mechanisms led to the identification of promising targets for future intervention strategies. The targeted inhibition of miRNA142-3p could open up new ways to reduce the activity of the immune system against its own insulin-producing cells," said Professor Anette Ziegler, head of the IDF.

The researchers have plans for follow-up studies: In order to further investigate the potential of the targeted inhibition of specific miRNAs, the next step will be to improve the selective and targeted accumulation of the miRNA142-3p inhibitor in the relevant target cells. The researchers are already making plans: In addition, Carolin Daniel's team also wants to identify further genes that are regulated by miRNA142-3p and/or Tet2 and whose dysregulation can contribute to the development and progression of islet autoimmunity.

Melatonin sets the internal clock. Researchers from Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB) in an international team have analyzed data on the impact of light pollution on melatonin formation in humans and vertebrates. They found that even the low light intensities of urban skyglow can suppress melatonin production.

Melatonin synchronizes the day-night-rhythm in animals and humans. It adjusts the circadian clocks of cells, tissues and organs, and regulates other seasonal processes like reproduction. In vertebrates, differences in light levels are detected by photoreceptors for example in the retina. At high light levels, melatonin production is suppressed. In darkness, melatonin is produced.

The sensitivity threshold for humans is 6 lux - street lighting is typically higher

Artificial light at night can disturb the nocturnal melatonin production. Within a literature review of 1900 studies, the researchers identified 72 relevant works that fulfilled their criteria for light pollution. Based on the data, they showed that even very low illuminance levels can suppress melatonin production for some vertebrate classes: in fish the threshold is 0.01 lux, in rodents 0.03 lux and in sensitive humans 6 lux; pure blue light showed much lower thresholds.

For comparison, the illuminance levels at night: On a starry night, the illuminance is 0.001 lux. On a full-moon night it reaches a maximum of 0.3 lux. The skyglow of a city, a form of light pollution, can reach illuminances of up to 0.1 lux, and outdoor lighting on the order of 150 lux.

"Surprisingly, the low light levels of skyglow are sufficient to suppress melatonin production in several vertebrate classes", says first author Dr. Maja Grubisic from IGB Berlin. "Skyglow affects large areas on a world-wide scale, as we know from satellite data", adds her colleague Dr. Andreas Jechow. The light from artificial lighting shines into the night sky, brighter with rain and snow, and is reflected by clouds and particles, which is called skyglow. The scientists unraveled several knowledge gaps: "There are no studies on melatonin and light pollution in reptiles and amphibians and no long term-studies at all. Particularly, the impacts on human health are not fully understood", says IGB researcher Dr. Franz Hoelker, head of the study.

The synchronization of seed production by trees has garnered attention due to its importance in agriculture, forestry and ecosystem management. Acorns shed by oak trees, for example, are an important source of food for wildlife, while crop trees such as citrus and pistachio nuts contribute to both human nutrition and the economy. Both oaks and citrus trees show synchronization of seed production, yet the cycles differ, with oaks showing irregular seed synchronization, while citrus show a distinct two-year cycle, known as alternate bearing. Understanding the timing and mechanisms that contribute to synchronized seeding can be a useful management tool. A team of scientists led by Tokyo University of Agriculture and Technology (TUAT) have developed a method that can be used to model the wide range of synchronization behaviors exhibited by different tree species simply by changing the control parameters.

Their findings were published on October 30, 2019 in Scientific Reports.

For this study, the authors examined period-3 (3-year cycle) synchronization of two spatially distinct populations of Zelkova serrata, a popular ornamental tree native to Japan, Korea, eastern China and Taiwan, that is also used in bonsai.

Self-incompatibility (so-called cross-pollination) in perennial plants is synchronized by the mechanism shown in Fig. 1. In the first autumn, tree A does not bear fruit, and all the others bear fruit. In the following year, the other trees do not flower for a year or few years, taking a rest. Tree A blooms, but because the other trees are not blooming, tree A cannot bear fruit, so tree A carries over enough accumulated resources and blooms the next year with the other trees. The synchronization is completed in the population. This is Isagi's resource budget model (RBM), which is the standard model for masting of perennial plants.

"We found that the two populations of Zelkova serrata 20 kilometers away -- the population in front of Tokyo Metropolitan Government Buildings in the Shinjuku District and the one in Fuchu City -- are completely synchronized in a '3-year cycle'," said Kenshi Sakai, a Professor in the Environmental and Agricultural Engineering Department, TUAT, Japan, and lead author of the study.

"The results indicate that the most famous Li-Yorke theorem 'Period three implies chaos,' which is the foundation of chaos theory, holds true in real-world plant species," said Sakai.

Chaos theory is a sub-discipline of mathematics that focuses on the behavior of complex dynamical systems that are extremely sensitive to initial conditions. Small differences in initial conditions can dramatically influence the outcome of a later state in these dynamical systems. Chaos is found everywhere in nature, yet rather than being randomly chaotic as they appear, these complex non-linear systems are made up of underlying patterns and fractals that are more structured than what they seem. Seemingly chaotic behavior can be analyzed with mathematical models and analytical techniques based on chaos theory, which has widespread applications across a variety of scientific disciplines, including natural and environmental science.

Sometimes two coupled chaotic systems may evolve in synchrony -- a phenomenon known as synchronization of chaos. Phase synchronization occurs when two or more coupled chaotic systems oscillate in a repeated sequence keeping their phase difference, for example two waveforms of the same frequency oscillating to the same phase angles with each cycle. In this case, according to the authors, the observed long-range spatial synchronization implies global pollen coupling occurred over a distance spanning 20 kilometers or more.

"The results also suggest that the mathematics governing the synchronization of Zelkova serrata is completely equivalent to the mathematics of the switching circuit of an AC-DC converter," said Sakai. "In other words, the results imply that common mathematics lurks behind completely different research subjects, such as nonlinear physics and conservation ecology," he explained, adding: "This illustrates the power of chaos theory and synchronization theory in elucidating natural phenomena."

"The method proposed in this study is a further refinement of the method of visualizing the synchronization phenomenon of allergenic pollen nationwide, and has also been shown to be a stable method that can be applied to different plant species. The proposed approach is expected to be a powerful method to understand the mechanisms of synchronization in various perennial plant species," said Sakai. "We are establishing a mathematical model that can uniformly describe various types of synchronization (two-period, three-period, multi-period coexistence, irregular, intermittent) exhibited in perennial trees. It could also be useful to predict the population dynamics of wild animals," he said.

When should we send expeditions to look for meteorites that have impacted Earth?

There is not enough time for more close study of all fireballs observed in the sky. The observation of a bright phenomenon reveals that a meteoroid has entered the atmosphere from space, but does any part of it end up on Earth? Only those with the survived terminal mass will reach the earth, but unfortunately many of them remain undiscovered.

At the same time as we are equipping expensive space missions, we have valuable extraterrestrial specimens arriving on Earth with information about the solar system's objects. University Researcher Maria Gritsevich from the University of Helsinki and the Finnish Geospatial Research Institute compares the situation to the idea that humanity does not bother to empty its letterbox.

In their article published in The Astrophysical Journal, researchers show that the analysis of fireball observations in large datasets can be made much quicker with the help of a neat mathematical formula, the α-β criterion. The researchers applied their modelling on fireball observations recorded in Australia over the past decade. They compared their results to discovered meteorites, and found that all the discovered meteorites could be revealed by using only the observed altitude and the deceleration rate of the body in the model. In other words, their calculated terminal mass was so large that they could be expected to survive all the way to Earth's surface.

- The greatest moment in a space physicist's work is when we can bring something tangible to the lab to be analysed as the result of our calculations, says Maria Gritsevich, which is why she considers the practical application of the approach to interpret meteor observations she presented already in her thesis a great step forward, and she hopes that more meteorites will be consciously discovered in the future than now.

It is a general belief that most likely, slow-moving objects that penetrate deep into the atmosphere will reach the ground. A more exact positioning requires the knowledge of the density of the body, so statistical hypotheses have to be included, and they require computational efficiency. The work may take several days, up to a week, and it is partially carried out by volunteers.

The use of the α-β model already in the entry track solution as a good velocity model, makes also the track solution more accurate.

- Often, we get a preliminary estimate with some approximation of the alpha and beta values in a few hours. Based on these results, we can decide whether to stop the work or whether to continue, says Mathematician Esko Lyytinen, a member of the Finnish Fireball Network, who has participated in the modelling of the location of several well-known meteorites.

Research from the University of Gothenburg shows that we tend to overestimate our personal environmental engagement. In a study with participants from Sweden, the United States, England, and India, most participants were convinced that they acted more environmentally friendly than the average person.

In the study, over 4,000 people responded to how much, and how often, they perform environmentally friendly activities compared to others. For example, buying eco-labelled products, saving household energy, and reducing purchases of plastic bags.

It turned out that the majority of the participants rated themselves as more environmentally friendly than others. Both in comparison to unknown people, and to their friends.

"The results point out our tendency to overestimate our own abilities, which is in line with previous studies where most people consider themselves to be more honest, more creative, and better drivers than others. This study shows that over-optimism, or the "better-than-average" effect, also applies to environmentally friendly behaviours," says environmental psychology researcher Magnus Bergquist.

After analyzing data from different types of environmentally friendly activities, results revealed that the participants were more likely to overestimate their engagement in activities they perform often. Many seemed to draw the faulty conclusion that the activities they perform often, they also perform more often than others.

A consequence of thinking that you are more environmentally friendly than others, is that it can reduce the motivation to act environmentally friendly in the future. The study also showed that when we think we are more environmentally friendly than others, we actually tend to become somewhat less environmentally friendly.

According to Magnus Bergquist, one way of reducing the risk of over-optimism standing in our way for a real environmental commitment, may be trying to have a more realistic view of our own environmental efforts.

"If you think about it logically, the majority cannot be more environmentally friendly than others. One way to change this faulty opinion, is to inform people that others actually behave environmentally friendly, and thereby creating an environmentally friendly norm. Social norms affect us also in this area, we know this from previous studies," says Magnus Bergquist.

Billions of years ago, asteroid collisions resulted in the ejection of fragments hundreds of kilometers across and sharing similar orbits. The resulting groups are known as asteroid families.

Other asteroid groups formed as a result of rotational fission, which happens when a rapidly spinning body reaches critical rotation speed and splits into relatively small fragments only a few kilometers across.

Scientists have always thought about fission clusters as entirely distinct from collisional families. Now, however, a study conducted by researchers affiliated with São Paulo State University (UNESP) at Guaratinguetá, under the aegis of a project supported by São Paulo Research Foundation - FAPESP, has shown that fission clusters may originate from collisional families in some cases.

Researchers at the National Space Research Institute (INPE) and the Federal University of São Paulo (UNIFESP) in Brazil, as well as the University of Côte d'Azur in France, also took part in the study, which is published in the journal Nature Astronomy.

"These discoveries change our understanding of how asteroid families are formed," Valério Carruba, a professor at UNESP and principal investigator for the project, told Agência FAPESP.

"It was always believed that asteroid families resulted from collisions, and that the fragments could evolve via gravitational or non-gravitational mechanisms, remaining roughly the same size. Now we've observed that a collision isn't a one-off event but may trigger the subsequent formation of a cascade of other groups," Carruba said.

The researchers set out to identify possible fission clusters inside asteroid families created by collision, selecting four young asteroid families formed less than 5 million years ago: Jones, Kazuya, 2001 GB11, and Lorre.

Using asteroid family recognition methods based on time-reversal simulation, machine learning clustering algorithms, and high-quality astrometric data (on orbital position and motion) obtained from observations of Solar System objects by Gaia, the European Space Agency (ESA) telescope and astrometry mission, they identified several subclusters inside these four extremely young collisional families.

Their analysis confirmed three secondary or tertiary fission clusters in the Jones family (6.7% of the total population), two in the 2001 GB11 family (6.3%), and two in the Lorre family (27.3%).

They defined secondary clusters as subsets of the larger family created by the primary collision and including the parent body, while tertiary groups are subsets of the primary family created by subsequent collisions and not including the parent body.

The authors of the published study note that detectable fission clusters in secondary and tertiary groups never account for more than 5% of the total population in asteroid families older than 100 million years.

"This is probably linked to the mechanism whereby primary asteroid families are formed," Carruba said.

Momentarily visible

According to Carruba, when asteroid families are formed they include streams of fragments that spin at high speed owing to the collision, or owing to non-gravitational effects such as YORP (the Yarkovsky-O'Keefe-Radzievskii-Paddack effect), a thermal torque due associated with solar radiation.

The fragments eventually cluster into fission groups that are visible only for a time. "After 5 to 10 million years they break up and can no longer be detected by the methods available to us," he explained. "Many fission clusters formed in the past are no longer detectable."

He added that there are no estimates of the rotation period (the time taken to rotate once) of the asteroids in many collision families. "Obtaining rotational data would help us find out which asteroids may be members of fission clusters," he said.

Our domesticated animals - both pets and livestock - hold the key to the spread of viruses among humans and wildlife according to new research involving Swansea University.

However, the study has revealed the patterns of how viruses are shared between humans and wildlife species differs between the two major groups of RNA and DNA viruses.

Dr Konstans Wells, who leads the Biodiversity and Health Ecology research group at Swansea University, said:

"Bats are commonly recognised as host of viruses that may eventually spillover into humans with devastating health effects, but the role of other mammalian groups and especially domestic species for the spread of virus are much less clear."

"Many of the current and future viral threads are linked to viruses that circulate in different animal species, connecting humans and mammal species into a huge network of who shares viruses with whom."

Dr Wells and his colleagues traced the associations between 1,785 virus species and 725 mammalian host species from around the globe, according to published scientific evidence.

The researchers used computer models to identify which mammalian species are the most central links in the networks of how humans and mammals are associated with the same virus species, representing possible pathways of virus spread and spillover. They then computed whether some virus species are less specialised than others, enabling them to spread among a more diverse range of host species and posing higher risk for future disease emergence.

The findings provide strong evidence that beside humans, domestic animals comprise the central links in networks of mammalian host-virus interactions, because they share viruses with many other species and provide the pathways for future virus spread. They also carry the largest proportions of viruses known to be shared by humans and animals.

At the same time, the study found patterns of DNA and RNA virus sharing among different mammalian groups to be rather different. The research suggests that bats and carnivores are most influential in spreading RNA viruses but play only a minor role in spreading DNA viruses among humans and mammalian species. Ungulates (hooved mammals), are of central importance for the spread of both RNA and DNA viruses.

DNA and RNA refer to deoxyribonucleic acid and ribonucleic acid, respectively, the two crucial genetic structures encoding all living organisms. RNA viruses that cause diseases in humans and originate from animals include flu viruses, Ebola virus and the SARS virus.

Dr Wells added: "We found RNA viruses to have high potential to shift across mammalian species with very different life histories and habitats, enabling them to be shared by more host species. This means also more risk for humans in terms of unpredictable emergence of novel infectious diseases."

He said domesticated animals include species from different taxonomic and functional groups of animals and are not particularly distinguished from wildlife, pointing to the fact that frequent virus acquisition and dissemination is the most plausible explanation of why humans and domestic animals intensively share viruses with many wildlife species.

"It's a matter of contact and interaction across borders," he said. "Among the myriad of viruses and other pathogens present in different mammals across the globe, many of those that can jump and exploit novel host species benefit from humans and their companion animals leaving wildlife no longer alone - pathogens that benefit from increasing and novel contact opportunities among host species are the winners of intensifying land use and globalization."

This research follows on from a previous study released earlier this year, which highlighted the need for a better understanding of the way harmful parasites can spread between animals and humans.