Genetic Disposition Protects Immune System From Aging (Biology)

A genetic disposition that plays a role in the development of the heart in the embryo also appears to play a key role in the human immune system. This is shown by a recent study led by the University of Bonn (Germany). When the gene is not active enough, the immune defense system undergoes characteristic changes, causing it to lose its effectiveness. Doctors speak of an aging immune system, as a similar effect can often be observed in older people. In the medium term, the results may contribute to reduce these age-related losses. The study is published in the journal Nature Immunology.

The image shows cells in which Creld1 was labeled with a yellow dye to show their localization in the cell. ©Lorenzo Bonaguro.

The gene with the cryptic abbreviation CRELD1 has so far been a mystery to science. It was known to play an important role in the development of the heart in the embryo. However, CRELD1 remains active after birth: Studies show that it is regularly produced in practically all cells of the body. For what purpose, however, was previously completely unknown.

The Bonn researchers used a novel approach to answer this question. Nowadays, scientific studies with human participants often include so-called transcriptome analyses. By these means, one can determine which genes are active to what extent in the respective test subjects. Researchers are also increasingly making the data they obtain available to colleagues, who can then use it to work on completely different matters. “And this is exactly what we did in our study,” says Dr. Anna Aschenbrenner from the LIMES Institute at the University of Bonn and member of the ImmunoSensation² Cluster of Excellence.

Aschenbrenner is doing her habilitation in the Genomics and Immunoregulation team of Prof. Dr. Joachim Schultze. Together with her colleagues, she combined transcriptome data from three different studies. “This provided us with information on the activity of the genetic material, including the CRELD1 gene, of a total of 4,500 test subjects,” she explains. “In addition, the data for these participants also included information on certain immunological parameters, such as the number of different immune cells in their blood.”

CRELD1 is less active in some people

The researchers discovered a surprising correlation when analyzing this information: The 4,500 analyzed test subjects included some in whom the CRELD1 gene was significantly less active for some reason. Interestingly, the blood of these donors was found to contain only very few of the so-called T cells. These cells play an important role in fighting infections; some of them detect virus-infected cells and kill them before they can infect other cells.

The researchers further investigated this relationship in mouse experiments. The results showed that the genetic loss of the Creld1 gene was indeed the cause for the loss of T cells. T cells lacking the Creld1 gene largely lose their ability to propagate and die earlier. “We see similar changes in people with an ‘aged’ immune system,” Aschenbrenner stresses. This phenomenon, also called immunosenescence, is mainly observed in older people. Those affected are much more susceptible to infections, as currently discussed in the context of COVID-19, but possibly also to age-related diseases such as cancer or Alzheimer’s. It is known that the activity of numerous genes in the blood is altered in a characteristic way, which experts also refer to as an immunological aging signature. “We found precisely this signature among participants with low CRELD1 activity,” says Aschenbrenner.

Centenarians with a young immune system

Surprisingly, some people’s immune system ages much faster than others. For instance, there are centenarians who, immunologically speaking, are several decades younger. With others, the power of the body’s own disease defense system already diminishes significantly in the middle of life. The researchers now hope that CRELD1 will provide them with a key to better understand the causes of immunological aging. “The long-term goal is to slow down or halt this process,” explains Aschenbrenner. “This could perhaps significantly reduce the risk of illness in seniors.”

References : Lorenzo Bonaguro?, Maren Köhne, Lisa Schmidleithner, Jonas Schulte-Schrepping?, Stefanie Warnat-Herresthal, Arik Horne, Paul Kern?, Patrick Günther?, Rob ter Horst, Martin Jaeger, Souad Rahmouni, Michel Georges?, Christine S. Falk, Yang Li, Elvira Mass, Marc Beyer?, Leo A. B. Joosten?, Mihai G. Netea?, Thomas Ulas?, Joachim L. Schultze?and Anna C. Aschenbrenner?: CRELD1 modulates homeostasis of the immune system in mice and humans. Nature Immunology; DOI: 10.1038/s41590-020-00811-2 link: https://www.nature.com/articles/s41590-020-00811-2

Provided by University of Bonn

Yin and Yang: Two Signaling Molecules Control Growth And Behavior In Bacteria (Biology)

Bacteria are considered to be true experts in survival. Their rapid adaptive response to changing environmental conditions is based, among other things, on two competing signaling molecules. As the “Yin and Yang” of metabolic control they decide on the lifestyle of bacteria, as reported by researchers from the University of Basel. The new findings also play a role in the context of bacterial infections.

Two competing signaling molecules control Caulobacter lifestyle. Pink: Swarmer cell with high ppGpp level; blue: sessile form with high c-di-GMP level. ©University of Basel, Biozentrum.

Whether they are pathogens, deep-sea microbes or soil-dwelling organisms, in order to survive, microorganisms must be able to adapt rapidly to diverse changes in their environment, including nutrient depletion. Bacteria owe their extraordinary ability to quickly adjust to adverse living conditions to small signaling molecules.

Scientists headed by Professor Urs Jenal and Professor Tilman Schirmer from the Biozentrum, University of Basel, have now discovered that bacteria use two chemically related signaling molecules to adapt their lifestyle to the prevailing living conditions. The researchers present their results in the latest issue of “Nature Microbiology”. Like Yin and Yang, the two molecules embody two forces that control bacterial growth and metabolism reciprocally.

Bacterium with two different lifestyles

The researchers investigated the antagonistic nature of the two signaling molecules ppGpp and c-di-GMP in the cell using Caulobacter crescentus as a model organism. This bacterium can slip into two different roles: It can be found in a free-swimming form that is unable divide and in a surface-attached, reproductive state.

Both the lifestyle and the environmental conditions are reflected in the concentration of the two signaling molecules. This information is detected by a protein that binds both signaling molecules and acts a molecular switch, controlling growth, metabolism and lifestyle of the bacterium.

Signaling molecules determine bacterial way of life

The signaling molecules ppGpp und c-di-GMP compete for binding to the master switch. “In swarming bacteria with high levels of ppGpp, the protein is switched on; it is active,” explains Urs Jenal. “In this state, glucose consumption is in full swing. Simultaneously, the resulting harmful oxygen radicals are efficiently neutralized.” This ensures, that metabolic reactions adapt to the high energy demand of the motile swimmer cells and cell damage is averted.

Under favorable living conditions, providing sufficient nutrients, the level of c-di-GMP increases constantly, forcing the swimmer to develop into a sessile form. “In this case, c-di-GMP displaces ppGpp from the protein’s binding pocket, it changes its structure and turns itself off,” says Jenal. “This redirects metabolic reactions allowing bacteria to settle, grow and reproduce. The production of building blocks for the cell is boosted along with adhesive substances for surface attachment.”

Important role also in pathogens

With the molecular master switch, the scientists have discovered the link between two large regulatory networks, which until now have been thought to operate independently. Although Caulobacter is a harmless environmental bacterium, the newly uncovered “Yin and Yang” mechanism could also play an important role in pathogens.

This may prove to be of key importance: Both ppGpp and c-di-GMP influence bacterial virulence and persistence as well as antibiotic resistance in different ways, thus influencing the course of many infections.

References : http://dx.doi.org/10.1038/s41564-020-00809-4

Provided by University of Basel

Study Finds Evidence Of Neurobiological Mechanism For Hallucinations And Delusions (Neuroscience)

A new study from researchers at Columbia University Vagelos College of Physicians and Surgeons has found evidence of a potential neurobiological mechanism for hallucinations and delusions that fits within the hierarchical model of psychosis and can explain their clinical presentation.

The study was published in eLife.

Columbia researchers Kenneth Wengler, PhD, a Postdoctoral Research Fellow and Guillermo Horga, MD, PhD, Florence Irving Associate Professor of Psychiatry, investigated the neurobiological mechanisms of two symptoms of schizophrenia: hallucinations and delusions. These two symptoms form the syndrome of psychosis, an immensely disabling psychiatric condition where patients lose their ability for reality testing.

“Typically, patients with more severe hallucinations also have more severe delusions, and these two symptoms respond similarly to antipsychotic medications. But this is not always the case; some patients have very prominent hallucinations but less severe delusions and vice versa,” says Wengler. “This suggests that these symptoms may share a common neurobiological mechanism while simultaneously depending on symptom-specific pathways.”

Some experts in the field believe that a hierarchical perceptual-inference model can explain the mechanisms behind psychosis. Wengler explains, “In its simplest form, the hierarchical model has two levels to the hierarchy: low and high. The low level makes inferences about basic features of stimuli and the high level makes inferences about their causes. An intuitive example of this is inferring the weather. In this scenario, you must decide if you are going to take an umbrella with you when you leave the house. The stimulus in this scenario is what you see when you look out the window; let’s say it’s cloudy. The context in this scenario is what you expect the weather to be like on a given day in the city you are in; let’s say you are in Seattle. Although it is not currently raining, because it’s cloudy and you are in a city where it often rains, you may decide to take an umbrella with you. The hierarchical model of psychosis frames hallucinations as resulting from dysfunction at the lower levels of the hierarchy and delusions as resulting from dysfunction at the higher levels of the hierarchy. Critically, these levels of inference are distinct but interconnected, so a dysfunction at one level would likely propagate upwards or downwards to other levels, therefore explaining why these symptoms tend to co-occur.”

To investigate the neurobiological mechanisms of hallucinations and delusions within the framework of the hierarchical model, the researchers used functional magnetic resonance imaging to measure intrinsic neural timescales throughout the brain. These neural timescales reflect how long information is integrated in a given brain region. Most importantly, these neural timescales are organized hierarchically, making it a fitting measure to test the hierarchical model of psychosis.

The researchers collected data from 127 patients with schizophrenia from various online databases and determined how an individual’s neural timescales related to their hallucination and delusion severities together. They found that neural timescales in the lower levels of the hierarchy tended to be longer in patients with more severe hallucinations, while neural timescales in the higher levels tended to be longer in patients with more severe delusions. These results provide the first direct evidence of a potential neurobiological mechanism for hallucinations and delusions that fits within the hierarchical model of psychosis and can explain their clinical presentation. The common neurobiological mechanism for both symptoms could result in increased neural timescales, but the symptom-specific pathways are the level of the hierarchy at which the neural timescales are increased. “Our findings open the door for the development of treatments to target specific symptoms of psychosis depending on an individual subject’s symptom profile, in line with the current push for individualized medicine,” says Horga.

References: Kenneth Wengler , Andrew T Goldberg, George Chahine, Guillermo Horga, “Distinct hierarchical alterations of intrinsic neural timescales account for different manifestations of psychosis”, Neuroscience, 2020. DOI: 10.7554/eLife.56151 link: https://elifesciences.org/articles/56151

Provided by Columbia University Irving Medical Center

Europa Glows: Radiation Does A Bright Number On Jupiter’s moon (Planetary Science)

As the icy, ocean-filled moon Europa orbits Jupiter, it withstands a relentless pummeling of radiation. Jupiter zaps Europa’s surface night and day with electrons and other particles, bathing it in high-energy radiation. But as these particles pound the moon’s surface, they may also be doing something otherworldly: making Europa glow in the dark.

This illustration of Jupiter’s moon Europa shows how the icy surface may glow on its nightside, the side facing away from the Sun. Variations in the glow and the color of the glow itself could reveal information about the composition of ice on Europa’s surface. Credit: NASA/JPL-Caltech

New research from scientists at NASA’s Jet Propulsion Laboratory in Southern California details for the first time what the glow would look like, and what it could reveal about the composition of ice on Europa’s surface. Different salty compounds react differently to the radiation and emit their own unique glimmer. To the naked eye, this glow would look sometimes slightly green, sometimes slightly blue or white and with varying degrees of brightness, depending on what material it is.

Scientists use a spectrometer to separate the light into wavelengths and connect the distinct “signatures,” or spectra, to different compositions of ice. Most observations using a spectrometer on a moon like Europa are taken using reflected sunlight on the moon’s dayside, but these new results illuminate what Europa would look like in the dark.

“We were able to predict that this nightside ice glow could provide additional information on Europa’s surface composition. How that composition varies could give us clues about whether Europa harbors conditions suitable for life,” said JPL’s Murthy Gudipati, lead author of the work published Nov. 9 in Nature Astronomy.

That’s because Europa holds a massive, global interior ocean that could percolate to the surface through the moon’s thick crust of ice. By analyzing the surface, scientists can learn more about what lies beneath.

Shining a Light

Scientists have inferred from prior observations that Europa’s surface could be made of a mix of ice and commonly known salts on Earth, such as magnesium sulfate (Epsom salt) and sodium chloride (table salt). The new research shows that incorporating those salts into water ice under Europa-like conditions and blasting it with radiation produces a glow.

That much was not a surprise. It’s easy to imagine an irradiated surface glowing. Scientists know the shine is caused by energetic electrons penetrating the surface, energizing the molecules underneath. When those molecules relax, they release energy as visible light.

“But we never imagined that we would see what we ended up seeing,” said JPL’s Bryana Henderson, who co-authored the research. “When we tried new ice compositions, the glow looked different. And we all just stared at it for a while and then said, ‘This is new, right? This is definitely a different glow?’ So we pointed a spectrometer at it, and each type of ice had a different spectrum.”

To study a laboratory mockup of Europa’s surface, the JPL team built a unique instrument called Ice Chamber for Europa’s High-Energy Electron and Radiation Environment Testing (ICE-HEART). They took ICE-HEART to a high-energy electron beam facility in Gaithersburg, Maryland, and started the experiments with an entirely different study in mind: to see how organic material under Europa ice would react to blasts of radiation.

They didn’t expect to see variations in the glow itself tied to different ice compositions. It was—as the authors called it—serendipity.

“Seeing the sodium chloride brine with a significantly lower level of glow was the ‘aha’ moment that changed the course of the research,” said Fred Bateman, co-author of the paper. He helped conduct the experiment and delivered radiation beams to the ice samples at the Medical Industrial Radiation Facility at the National Institute of Standards and Technology in Maryland.

A moon that’s visible in a dark sky may not seem unusual; we see our own Moon because it reflects sunlight. But Europa’s glow is caused by an entirely different mechanism, the scientists said. Imagine a moon that glows continuously, even on its nightside—the side facing away from the Sun.

“If Europa weren’t under this radiation, it would look the way our moon looks to us—dark on the shadowed side,” Gudipati said. “But because it’s bombarded by the radiation from Jupiter, it glows in the dark.”

Set to launch in the mid-2020s, NASA’s upcoming flagship mission Europa Clipper will observe the moon’s surface in multiple flybys while orbiting Jupiter. Mission scientists are reviewing the authors’ findings to evaluate if a glow would be detectable by the spacecraft’s science instruments. It’s possible that information gathered by the spacecraft could be matched with the measurements in the new research to identify the salty components on the moon’s surface or narrow down what they might be.

“It’s not often that you’re in a lab and say, ‘We might find this when we get there,'” Gudipati said. “Usually it’s the other way around—you go there and find something and try to explain it in the lab. But our prediction goes back to a simple observation, and that’s what science is about.”

Missions such as Europa Clipper help contribute to the field of astrobiology, the interdisciplinary research on the variables and conditions of distant worlds that could harbor life as we know it. While Europa Clipper is not a life-detection mission, it will conduct detailed reconnaissance of Europa and investigate whether the icy moon, with its subsurface ocean, has the capability to support life. Understanding Europa’s habitability will help scientists better understand how life developed on Earth and the potential for finding life beyond our planet.

References: Gudipati, M.S., Henderson, B.L. & Bateman, F.B. Laboratory predictions for the night-side surface ice glow of Europa. Nat Astron (2020). https://doi.org/10.1038/s41550-020-01248-1 link: https://www.nature.com/articles/s41550-020-01248-1

Provided by NASA

Maunakea Telescopes Confirm First Brown Dwarf Discovered By Radio Observations (Planetary Science)

A collaboration between the LOw Frequency ARray (LOFAR) radio telescope in Europe, the Gemini North telescope, and the NASA InfraRed Telescope Facility (IRTF), both on Maunakea in Hawai’i, has led to the first direct discovery of a cold brown dwarf from its radio wavelength emission. Along with paving the way for future brown dwarf discoveries, this result is an important step towards applying radio astronomy to the exciting field of exoplanets.

Artist’s impression of the cold brown dwarf BDR J1750+3809. The blue loops depict the magnetic field lines. Charged particles moving along these lines emit radio waves that LOFAR detected. Some particles eventually reach the poles and generate aurorae similar to the northern lights on Earth. ©ASTRON/Danielle Futselaar

For the first time, astronomers have used observations from the LOFAR radio telescope, the NASA IRTF, operated by the University of Hawai’i, and the international Gemini Observatory, a Program of NSF’s NOIRLab, to discover and characterize a cold brown dwarf. The object, designated BDR J1750+3809, is the first substellar object to be discovered through radio observations — until now, brown dwarfs have been uncovered in large infrared and optical surveys. Directly discovering these objects with sensitive radio telescopes such as LOFAR is a significant breakthrough because it demonstrates that astronomers can detect objects that are too cold and faint to be found in existing infrared surveys — maybe even large free-floating exoplanets.

“In this discovery, Gemini was particularly important because it identified the object as a brown dwarf and also gave us an indication of the temperature of the object,” explained lead author Harish Vedantham of ASTRON, the Netherlands Institute for Radio Astronomy. “The Gemini observations told us that the object was cold enough for methane to form in its atmosphere — showing us that the object is a close cousin of Solar System planets like Jupiter.”

Brown dwarfs are substellar objects straddling the boundary between the largest planets and the smallest stars [1]. Occasionally dubbed failed stars, brown dwarfs lack the mass to trigger hydrogen fusion in their cores, instead glowing at infrared wavelengths with leftover heat from their formation. While they lack the fusion reactions that keep our Sun shining, brown dwarfs can emit light at radio wavelengths. The underlying process powering this radio emission is familiar, as it occurs in the largest planet in the Solar System. Jupiter’s powerful magnetic field accelerates charged particles such as electrons, which in turn produces radiation — in this case, radio waves [2] and aurorae.

The fact that brown dwarfs are radio emitters allowed the international collaboration of astronomers behind this result to develop a novel observing strategy. Radio emissions have previously been detected from only a handful of cold brown dwarfs — and they have been known and cataloged by infrared surveys before being observed with radio telescopes. The team decided to flip this strategy, using a sensitive radio telescope to discover cold, faint sources and then perform follow-up infrared observations with a large telescope like the 8-meter Gemini North telescope to categorize them.

“We asked ourselves, ‘Why point our radio telescope at cataloged brown dwarfs?’,” said Vedantham. “Let’s just make a large image of the sky and discover these objects directly in the radio.”

An infrared image of the cold brown dwarf BDR J1750+3809 taken with Gemini North’s acquisition camera for the Gemini Near-Infrared Spectrograph (GNIRS) and Gemini’s Near InfraRed Imager and spectrograph (NIRI). The image is a color composite showing the infrared filters in chromatic order, which is why the brown dwarf appears blue. The image is a color composite showing the infrared filters in chromatic order, which is why the brown dwarf appears blue. ©International Gemini Observatory/NOIRLab/NSF/AURA/H. Vedantham/UKIRT Hemisphere Survey

Having found a variety of tell-tale radio signatures in their observations, the team had to distinguish potentially interesting sources from background galaxies. To do so, they searched for a special form of light that was circularly polarized [3] — a feature of light from stars, planets, and brown dwarfs, but not from background galaxies. Having found a circularly polarized radio source, the team then turned to telescopes including Gemini North and the NASA IRTF to provide the measurements required to identify their discovery.

Gemini North is equipped with a variety of infrared instruments, one of which is usually kept ready to observe when an interesting astronomical opportunity arises. In the case of BDR J1750+3809, Gemini’s mainstay infrared imager, the Near InfraRed Imager and spectrograph (NIRI) , was not available — so Gemini astronomers took the unusual step of using the acquisition camera for the Gemini Near-Infrared Spectrograph (GNIRS) instead. Thanks to the careful work and foresight of Gemini staff, this camera provided deep, sharp, and accurate imaging at several infrared wavelengths.

“These observations really highlight the versatility of Gemini, and in particular the little-used ‘keyhole’ imaging capability of Gemini’s GNIRS spectrograph,” commented Gemini Observatory and University of Edinburgh astronomer Trent Dupuy — a co-author of the research paper. The Gemini North observations were obtained via Director’s Discretionary Time, which is reserved for programs needing small amounts of observing time with potentially high-impact results.

“This observation showcases both the flexibility and the power of the Gemini Observatories,” said Martin Still of the National Science Foundation (NSF). “This was an opportunity where Gemini’s design and operations enabled an innovative idea to develop into a significant discovery.”

As well as being an exciting result in its own right, the discovery of BDR J1750+3809 could provide a tantalizing glimpse into a future when astronomers can measure the properties of exoplanets’ magnetic fields. Cold brown dwarfs are the closest things to exoplanets that astronomers can currently detect with radio telescopes, and this discovery could be used to test theories predicting the magnetic field strength of exoplanets. Magnetic fields are an important factor in determining atmospheric properties and long term evolution of exoplanets.

“Our ultimate goal is to understand magnetism in exoplanets and how it impacts their ability to host life,” concluded Vedantham. “Because magnetic phenomena of cold brown dwarfs are so similar to what is seen in Solar System planets, we expect our work to provide vital data to test theoretical models that predict the magnetic fields of exoplanets.”

Credit:
Images and videos:
International Gemini Observatory/NOIRLab/NSF/AURA/Lomberg J, J. Chu/J. Pollard, E. Mastroianni, LOFAR / ASTRON, S. Brunier/Digitized Sky Survey 2.

Music:
Stellardrone – Airglow (https://stellardrone.bandcamp.com/)

References : H. K. Vedantham, J. R. Callingham, T. W. Shimwell, T. Dupuy, William M. J. Best, Michael C. Liu, Zhoujian Zhang, K. De, L. Lamy, P. Zarka, H. J. A. Rottgering, A. Shulevski, “Direct radio discovery of a cold brown dwarf”, ArXiv, 2020. https://arxiv.org/abs/2010.01915

Provided by AURA

Environmental Factors Affect The Distribution Of Iberian Spiders (Biology)

Southern small-leaved oak forests are the habitats with a higher level of spider endemism in the Iberian Peninsula, according to an article published in the journal Biodiversity and Conservation. The study analyses the factors that affect biodiversity patterns of spider communities in the national park network of Spain, and explains the role of the environmental factors in the distribution of the biodiversity of this faunistic group in the peninsular territory.

The study led by the UB and IBRio reveals how environmental factors affect the distribution of biodiversity of spiders in the peninsular territory. ©Jagoba Malumbres-Olarte, University of the Azores (Portugal)

The study is led by Professor Miquel Arnedo, from the Faculty of Biology and the Biodiversity Research Institute (IRBio) of the University of Barcelona, and it counts on the participation of the experts Luis Carlos Crespo, Marc Domènec and Carles Ribera (UB-IRBio), Jagoba Malumbres-Olarte and Pedro Cardoso, from the University of the Azores (Portugal), and Jordi Moya-Laraño, from the Experimental Station of Arid Zones in Almeria (EEZA-CSIC).

Iberian spiders: how are they distributed throughout the peninsular territory?

There are many doubts on the biology and ecology of Iberian spider communities, a group with a fundamental role in natural ecosystems. There might be more than 1,400 species in the peninsular territory, which has a great climate diversity and natural habitat. In some cases, there are species with a limited distribution -regional or local endemism- and this would explain the observed changes among the communities of different areas.

The new study focuses on the study of spider communities in the national parks of Aigüestortes i Estany de Sant Maurici, Ordesa y Monte Perdido, Picos de Europa, Monfragüe, Cabañeros and Sierra Nevada. In particular, they studied the spider communities -a total of 20,552 specimens from 375 species- in different types of oak trees (Quercus spp), widely distributed around the peninsula, such as those that include the sessile oak (Quercus petraea), the Valencian oak (Quercus faginea) and the Pyrinean oak (Quercus pyrenaica).

“The results reveal that Valencian oak forests (Q. faginea) are those with a higher number of spider species, probably due to the combined effects of the physical structure of the habitat and climate conditions”, notes Professor Miquel Arnedo, from the Department of Evolutionary Biology, Ecology and Environmental Sciences.

The study also confirms the previous studies that point to a decrease of species in southern forest ecosystems, which is caused by the reduction of connectivity of ecosystems with the rest of the continent.

“However, we suggest that these changes in the number of species could be the result of complex interactions between the geographical position, habitat and local climate. This would make it possible, for instance, for us to find spider communities in the Cabañeros National Park (Castilla – La Mancha) with a higher number of species than in Picos de Europa (Asturias)”, notes Arnedo.

Climate, geography and endemism of Iberian spiders

Another relevant contribution of the study is the identification of a pattern that relates the increase of the level of endemism in the spider communities with the rise of temperatures and decrease of annual precipitation, which are typical from the Mediterranean climate.

“Spider communities in Mediterranean areas seem to be more endemic -when we consider distributions of all species in each community- and have a higher number of exclusively Iberian species”, notes the expert Jagoba Malumbres-Olarte, first signatory of the article. Other groups of spiders show a higher level of endemism depending on certain ecological features, according to the authors.

“In this case, we saw that those spiders that spread more frequently through the air using silk, known as ballooning, show a more extensive geographical distribution and therefore, are less endemic. For instance, this would be the case of some species from the Lindyphiidae family”.

Spiders, indicators of environmental quality

Despite the ecological value of spiders, these arthropods have been rarely used as bioindicators. This study sheds light in this field of ecology studies, and suggests that the presence and abundance of spider families with high levels of endemism -for instance, Oonopidae, Dysderidae, Zodariidae and Sparassidae families- could be used by researchers as indicators of the singularities and ecological qualities of some natural areas.

“In the studied communities, these families are those with a higher level of endemism. If we consider the difficulty when identifying certain Iberian species and the likelihood to find undescribed species, the option of using spider families -instead of species- could ease the use of spiders as ecological and conservation indicators”, authors say.

Improving biodiversity conservation strategies

The lack of many experts able to identify and describe spider species and the great diversity of this group are factors that make it difficult for researchers to study the ecology of Iberian spider communities, and by extension, many others. Expanding the knowledge on the biodiversity of the peninsular spider fauna requires the promotion of monitoring programs and a regular control of temporary changes in the communities.

In this context, the published article in the journal Biodiversity and Conservation brings new information to improve the conservation and management of national parks and protected areas in general. It reveals new data on the number and composition of species in the communities in the national parks, information that enables having a reference for future monitoring plans. Also, it identifies the most relevant groups depending on their endemic levels (that is, those with potentially high values for conservation).

“Our study also states that different habitats within the same area or park could have a differential value regarding conservation and scientific interest, and consequently, they could be an object of several levels of prioritization in conservation actions”, conclude the researchers.

References: Malumbres-Olarte, J., Crespo, L.C., Domènech, M. et al. How Iberian are we? Mediterranean climate determines structure and endemicity of spider communities in Iberian oak forests. Biodivers Conserv (2020). https://doi.org/10.1007/s10531-020-02058-7 https://link.springer.com/article/10.1007/s10531-020-02058-7

Provided by University of Barcelona

Researchers Discover Bacterial DNA’s Recipe For Success (Biology)

A single criterion predicts whether a genetic package such as antibiotic resistance will thrive in a given environment.

Biomedical engineers at Duke University have developed a new way of modeling how potentially beneficial packages of DNA called plasmids can circulate and accumulate through a complex environment that includes many bacterial species. The work has also allowed the team to develop a new factor dubbed the “persistence potential” that, once measured and computed, can predict whether or not a plasmid will continue to thrive in a given population or gradually fade into oblivion.

The list of equations required to model three plasmids being swapped in one bacterial species using the old method (left) versus the new, simplified model’s equations (right). ©Teng Wang, Duke University.

The researchers hope that their new model will lay the groundwork for others to better model and predict how important traits such as antibiotic resistance in pathogens or metabolic abilities in bacteria bred to clean environmental pollution will spread and grow in a given environment.

The results appear online on November 4 in the journal Nature Communications.

In addition to the Darwinian process of handing down genes important for survival from parents to offspring, bacteria also engage in a process called horizontal gene transfer. Bacteria are constantly sharing genetic recipes for new abilities across species by swapping different packages of genetic material called plasmids with one another.

“In an examination of just a single bottle of seawater, there were 160 bacterial species swapping 180 different plasmids,” said Lingchong You, professor of biomedical engineering at Duke. “Even in a single bottle of water, using current methods to model plasmid mobility would far exceed the collective computing power of the entire world. We’ve developed a system that simplifies the model while maintaining its ability to accurately predict the eventual results.”

The potential of any one of these genetic packages to become common throughout a given population or environment, however, is far from certain. It depends on a wide range of variables, such as how quickly the packages are shared, how long the bacteria survive, how beneficial the new DNA is, what the trade-offs are for those benefits and much more.

Being able to predict the fate of such a genetic package could help many fields — perhaps most notably the spread of antibiotic resistance and how to combat it. But the models required to do so in a lifelike scenario are too complicated to solve.

“The most complex system we’ve ever been able to model mathematically is three species of bacteria sharing three plasmids,” said You. “And even then, we had to use a computer program just to generate the equations, because otherwise we’d get too confused with the number of terms that were needed.”

In the new study, You and his graduate student, Teng Wang, created a new framework that greatly reduces the complexity of the model as more species and plasmids are added. In the traditional approach, each population is divided into multiple subpopulations based on which plasmids they’re carrying. But in the new system, these subpopulations are instead averaged into a single one. This drastically cuts down on the number of variables, which increases in a linear fashion as new bacteria and plasmids are added rather than exponentially.

This new approach enabled the researchers to derive a single governing criterion that allows the prediction of whether or not a plasmid will persist in a given population. It’s based on five important variables: the cost to the bacteria of having the new DNA, how often the DNA is lost, how quickly the population is diluted by the flux through the population, how quickly the DNA is swapped between bacteria, and how fast the population as a whole is growing.

With measurements for these variables in hand, researchers can calculate the population’s “plasmid persistence.” If that number is greater than one, the genetic package will survive and spread, with higher numbers leading to greater abundance. If less than one, it will fade away into oblivion.

“Even though the model is simplified, we’ve found that it’s reasonably accurate under certain constraints,” said Wang. “As long as the new DNA doesn’t place too great of a burden on the bacteria, our new framework will succeed.”

You and Wang tested their new modeling approach by engineering a handful of different synthetic communities, each with different strains of bacteria and genetic packages for swapping. After running the experiments, they found that the results fit quite well within the expectations of their theoretical framework. And to go the extra mile, the researchers also took data from 13 previously published papers and ran their numbers as well. Those results also supported their new model.

“The plasmid persistence criterion gives us the hope of using it to guide new applications,” said You. “It could help researchers engineer a microbiome by controlling the genetic flow to achieve a certain function. Or it can give us guidance on what factors we can control to eliminate or suppress certain plasmids from bacterial populations, such as those responsible for antibiotic resistance.”

References: “The Persistence Potential of Transferable Plasmids,” Teng Wang & Lingchong You. Nature Communications, Nov. 9, 2020. DOI: 10.1038/s41467-020-19368-7 link: http://dx.doi.org/10.1038/s41467-020-19368-7

Provided by Duke University

Infection By Parasites Disturbs Flight Behaviour In Shoals Of Fish (Biology)

In order to escape predators, many fish – including insects, fish and birds – have developed strategies for rapidly transmitting information on threats to others of their species. This information is transmitted within a group of hundreds, or even thousands, of individuals in (escape) waves. This collective response is also, in the case of fish, known as shoal behaviour. Special parasites can, however, manipulate such a survival strategy. Researchers at the University of Münster have discovered that infected individual fish disturb the transmission of flight behaviour and, as a result, increase not only their own risk of being eaten, but also that of other – non-infected – members of the group. The results of the study have been published in the journal Proceedings of the Royal Society.

Infection by parasites disturbs flight behaviour in shoals of fish. ©WWU/Jörn Scharsack

Background and methodology

In order to study social responsiveness in fish, the researchers used the tapeworm Schistocephalus solidus as a parasite. The three-spined stickleback Gasterosteus aculeatus – an important model in ecological and evolutionary parasitology – was used as an intermediate host. The parasite ensures that the fish is less prone to be scared and more courageous and, as a result, increases its risk-taking behaviour. This poses the threat that the stickleback will very probably fall prey to the final host of the parasite, a fish-eating bird. In aquariums the scientists simulated a bird strike on shoals of sticklebacks. “When the shoal consisted only of healthy – in other words, non-infected – sticklebacks, the escape wave continued quickly through the entire shoal after the bird strike, even though the sticklebacks at the back were only able to see the response of their conspecifics and not the bird strike itself”, explains Nicolle Demandt from the Institute of Evolution and Biodiversity at the University of Münster and lead author of the study. “When we placed infected sticklebacks in the middle of the shoal, the escape wave came to a virtual halt and it only got through to the fish at the back to a limited extent.”

Although the manipulation of behaviour on the part of parasites is widespread in the animal kingdom, many studies carried out so far have only concentrated on the infected animals themselves and on the manipulation of their behaviour. “Ours is the first experimental study which shows how individuals whose behaviour has been manipulated by parasites can influence the transmission of information and, as a result, collective flight responses – in other words, shoal behaviour,” explains Prof. Joachim Kurtz, in whose laboratory the study was carried out. The researchers examined the connection between parasitic infection and flight depth, as well as the time the fish spent in the danger zone before and after the bird strike.

Sticklebacks with a high parasitic infection displayed a tendency to take flight to not such a deep level and they remained in the danger zone for a longer period of time than did sticklebacks with less parasitic infection. “The result indicates that the loss of energy might play a role in the extent to which behaviour is manipulated,” explains Dr. Jörn Scharsack, who led the study. “Parasites remove energy from their hosts, which leads for example to a reduction in fat reserves and a higher food requirement. Infected fish should therefore invest less energy in flight response and return more quickly to looking for food.”

As sticklebacks are found in very different aquatic systems – e.g. clear lakes, turbid rivers and sea environments – transferring the results of the study to the fishes’ natural habitats depends on the local surroundings. In clear waters, the results can indeed be transferred to the natural habitat as the fish use their eyes to react to the signals from other sticklebacks taking flight. In more turbid surroundings, however, the fish can rely more on other senses. For example, by means of their lateral line organs they can feel even the smallest changes in pressure caused by the movements made by their neighbours in the shoal. Other factors influencing the transfer of the laboratory study to a natural environment are the size of the shoal, the number of infected individuals and the extent of their parasitic infection.

Should it be a general phenomenon that infected individuals have an influence on the collective responses of the entire group, this might be of wide-ranging significance for the animal kingdom – even including a possible influence of parasites on human group behaviour, say the researchers.

References: Nicolle Demandt, Marit Praetz, Ralf H. J. M. Kurvers, Jens Krause, Joachim Kurtz and Jörn P. Scharsack (2020). Parasite infection disrupts escape behaviours in fish shoals. Proceedings of the Royal Society. DOI: 10.1098/rspb.2020.1158 link: https://royalsocietypublishing.org/doi/10.1098/rspb.2020.1158

Provided by University of Munster

RUDN University Soil Scientist: Deforestation Affects The Bacterial Composition Of the Soil (Botany)

A soil scientist from RUDN University studied the effect of forest conversion on the properties of the soil: its acidity, carbon and nitrogen resources, bacterial composition, and the activity of microorganisms. The study can help improve the methods of soil cultivation after deforestation, namely, select the best fertilizers, prevent erosion, slow down nutrient depletion, and balance the composition of the bacterial community. The results of the study were published in the Forest Ecology and Management journal.

A soil scientist from RUDN University studied the effect of forest conversion on the properties of the soil: its acidity, carbon and nitrogen resources, bacterial composition, and the activity of microorganisms. The study can help improve the methods of soil cultivation after deforestation, namely, select the best fertilizers, prevent erosion, slow down nutrient depletion, and balance the composition of the bacterial community. ©RUDN University

The demand for crop farming products grows constantly, and to satisfy it, more and more forests are converted into plantations. In these converted areas sustainable and diverse ecosystems are replaced with monocultures (crop species). Such changes in land utilization affect both the chemical content of the soil and its biological composition, that is, the structure of its microbial community. Until recently, studies had focused on either the former or the latter aspect of this process. A soil scientist from RUDN University was the first to conduct a comprehensive study and to find out how deforestation and changes in chemical factors caused by it affect the bacterial composition of the soil.

“The diversity of soil microorganisms doesn’t necessarily reduce as a result of forest conversion. However, bacterial communities undergo massive transformations. The bacteria that used to dominate in forest soils can almost disappear after deforestation and planting of crops. The key factors in this process are soil acidity and carbon and nitrogen resources,” says Yakov Kuzyakov, a Ph.D. in Biology, and the Head of the Center for Mathematical Modeling and Design of Sustainable Ecosystems at RUDN University.

His team compared soil samples taken from a forest and four plantations in Hunan Province in South-Eastern China. Five years before that the whole territory had been covered with a pristine forest. The scientists measured the acidity of the soil, as well as the levels of carbon and nitrogen in it. All these indicators are associated both with soil fertility and bacterial activity. Microorganisms play a role in the circulation of soil carbon and also ‘fix’ nitrogen, making it accessible for plants. It turned out that soil acidity reduces after deforestation, and the levels of organic nitrogen and carbon drop by 83%. According to the team, this may be due to the reduction of vegetative cover and soil erosion. However, to the team’s surprise, bacterial diversity in plantation soils turned out to be 6.8% higher than in forest soils.

The scientists believe this might be due to the fertilization of plantations. Fertilizers contain a lot of nutrients, thus increasing microbial diversity. Moreover, cultivated soil is enriched in carbon and other substances that also support intensive bacterial growth. Reduced acidity might be another factor to promote microbial and especially bacterial diversity. Different bacteria turned out to dominate in forest and plantation soils. For example, deforestation created perfect conditions for photosynthesizing bacteria. They transform sunlight into energy, which is a much more difficult task in shady forests.

“We found out that changes in the bacterial composition of the soil are mainly due to soil acidity and the levels of organic carbon and nitrogen. Therefore, efficient soil management methods should be developed for monoculture plantations to improve fertilization, prevent soil erosion, slow down the depletion of nutrients, and support microbial activity after deforestation,” added Yakov Kuzyakov.

References: http://dx.doi.org/10.1016/j.foreco.2020.118473

Provided by RUDN University