Implantable Device Can Monitor And Treat Heart Disease (Medicine)

Pacemakers and other implantable cardiac devices used to monitor and treat arrhythmias and other heart problems have generally had one of two drawbacks – they are made with rigid materials that can’t move to accommodate a beating heart, or they are made from soft materials that can collect only a limited amount of information.

Cunjiang Yu, Bill D. Cook Associate Professor of Mechanical Engineering at the University of Houston, led a group of researchers that developed a cardiac patch made from fully rubbery electronics that can be placed directly on the heart to collect electrophysiological activity, temperature, heartbeat and other indicators, all at the same time. ©University of Houston

Researchers led by a mechanical engineer from the University of Houston have reported in Nature Electronics a patch made from fully rubbery electronics that can be placed directly on the heart to collect electrophysiological activity, temperature, heartbeat and other indicators, all at the same time.

Cunjiang Yu, Bill D. Cook Associate Professor of Mechanical Engineering at UH and corresponding author for the paper, said the device marks the first time bioelectronics have been developed based on fully rubbery electronic materials that are compatible with heart tissue, allowing the device to solve the limitations of previous cardiac implants, which are mainly made out of rigid electronic materials.

“For people who have heart arrhythmia or a heart attack, you need to quickly identify the problem,” Yu said. “This device can do that.” Yu is also a principle investigator with the Texas Center for Superconductivity at UH.

In addition to the ability to simultaneously collect information from multiple locations on the heart – a characteristic known as spatiotemporal mapping – the device can harvest energy from the heart beating, allowing it to perform without an external power source. That allows it to not just track data for diagnostics and monitoring but to also offer therapeutic benefits such as electrical pacing and thermal ablation, the researchers reported.

Yu is a leader in the development of fully rubbery electronics with sensing and other biological capabilities, including for use in robotic hands, skins and other devices. The epicardial bioelectronics patch builds upon that with a material with mechanical properties that mimic cardiac tissue, allowing for a closer interface and reducing the risk that the implant could damage the heart muscle.

“Unlike bioelectronics primarily based on rigid materials with mechanical structures that are stretchable on the macroscopic level, constructing bioelectronics out of materials with moduli matching those of the biological tissues suggests a promising route towards next-generational bioelectronics and biosensors that do not have a hard-soft interface for the heart and other organs,” the researchers wrote. “Our rubbery epicardial patch is capable of multiplexed ECG mapping, strain and temperature sensing, electrical pacing, thermal ablation and energy harvesting functions.”

References: Sim, K., Ershad, F., Zhang, Y. et al. An epicardial bioelectronic patch made from soft rubbery materials and capable of spatiotemporal mapping of electrophysiological activity. Nat Electron (2020). https://doi.org/10.1038/s41928-020-00493-6 link: https://www.nature.com/articles/s41928-020-00493-6

Provided by University Of Houston

Mars Plays Shepherd To Our Moon’s Long-lost Twin, AOP Scientists Find (Planetary Science)

An international team of planetary scientists led by astronomers at AOP have found an asteroid trailing behind Mars with a composition very similar to the Moon’s. The asteroid could be an ancient piece of debris, dating back to the gigantic impacts that formed the Moon and the other rocky planets in our solar system like Mars and the Earth. The research, which was published in the journal Icarus (https://www.sciencedirect.com/science/article/pii/S0019103520303602), also has implications for finding such primordial objects associated with our own planet.

Trojans are a class of asteroid that follows the planets in their orbits as a flock of sheep might follow a shepherd, trapped within gravitational “safe havens” 60 degrees in front of, and behind, the planet (Figure 1). They are of great interest to scientists as they represent leftover material from the formation and early evolution of the solar system. Several thousands of those Trojans exist along the orbit of the giant planet Jupiter. Closer to the Sun, astronomers have so far discovered only a handful of Trojans of Mars, the planet next door to Earth.

Depiction of the planet Mars and its retinue of Trojans circling around the L4 and L5 Lagrange points. The dashed curve traces the planet’s orbit. At L5, asteroid 101429 is represented by the blue point, the asteroid Eureka and its family are represented in red and amber respectively. ©AOP

A team including scientists from Italy, Bulgaria and the US and led by the Armagh Observatory and Planetarium (AOP) in Northern Ireland has been studying the Trojans of Mars to understand what they tell us about the early history of the inner worlds of our solar system – the so-called terrestrial planets – but also to inform searches for Trojans of the Earth. Ironically, it is much easier to find Trojans of Mars than for our own planet because these Earth Trojans, if they exist, sit always close to the Sun in the sky where it is difficult to point a telescope. An Earth Trojan, named 2010 TK7, was found a decade ago by NASA’s WISE space telescope, but computer modelling showed it is a temporary visitor from the belt of asteroids between Mars and Jupiter rather than a relic planetesimal from the Earth’s formation.

To find out the composition of the Mars Trojans, the team used X-SHOOTER, a spectrograph mounted on the European Southern Observatory 8-m Very Large Telescope (VLT) in Chile. X-SHOOTER looks at how the surface of the asteroid reflects sunlight of different colours – its reflectance spectrum. By performing a spectral comparison with other solar system bodies with known composition, a process called taxonomy, the team hoped to determine if this asteroid is made by material similar to the rocky planets like the Earth, or if it is a piece of carbon- and water-rich matter typical of the outer solar system beyond Jupiter.

One on the Trojans the team looked at was asteroid (101429) 1998 VF31. Existing colour data on the object suggested a composition similar to a common class of meteorites called ordinary chondrites. The light-collecting power of the VLT allowed to gather higher-quality data on this asteroid than ever before. By combining these new measurements with data obtained previously at NASA’s Infrared Telescope Facility in Hawaii, the team then tried to classify 101429. They found that the spectrum did not match well with any particular type of meteorite or asteroid and, as a result, expanded their analysis to include spectra from other types of surfaces.

To their surprise, they found (Figure 2) that the best spectral match was not with other small bodies but with our nearest neighbour, the Moon. As Dr Galin Borisov, a PDRA at AOP who was deeply involved in the spectral analysis explains: “Many of the spectra we have for asteroids are not very different from the Moon but when you look closely there are important differences, for example the shape and depth of broad spectral absorptions at wavelengths of 1 and 2 microns. However, the spectrum of this particular asteroid seems to be almost a dead-ringer for parts of the Moon where there is exposed bedrock such as crater interiors and mountains”.

Reflectance spectrum of asteroid 101429 from data obtained at the European Southern Observatory Very Large Telescope in Chile and the NASA Infrared Telescope Facility in Hawaii. This is plotted against a spectrum of an area around Littrow crater near the Apollo 17 landing site on the Moon obtained from the Mauna Kea Observatory in Hawaii. ©AOP

Where could such an unusual object have come from? One possibility is that 101429 is just another asteroid, similar perhaps to ordinary chondrite meteorites, that acquired its lunar-like appearance through aeons of exposure to solar radiation, a process called space weathering.

Alternatively, the asteroid may look like the Moon because it does come from the Moon. Dr Apostolos Christou, AOP astronomer and lead author of the paper explains: “The early solar system was very different from the place we see today. The space between the newly-formed planets was full of debris and collisions were commonplace. Large asteroids – we call these planetesimals – were constantly hitting the Moon and the other planets. A shard from such a collision could have reached the orbit of Mars when the planet was still forming and was trapped in its Trojan clouds.”

A third, and perhaps more likely scenario is that the object came from Mars itself. As Dr Christou points out, “The shape of the 101429 spectrum tells us that it is rich in pyroxene, a mineral found in the outer layer or crust of planet-sized bodies. Mars, like the Moon and the Earth, was pummeled by impacts early in its history, one of these was responsible for the gigantic Borealis basin, a crater as wide as the planet itself. Such a colossal impact could easily have sent 101429 on its way to the planet’s L5 Lagrangian point.” Indeed, a Mars origin was proposed a few years ago for 101429’s Trojan siblings, a cluster of Trojans collectively known as the Eureka family (Figure 1). These asteroids also have an unusual composition but, whereas 101429 is pyroxene-rich these Eureka family asteroids are mostly olivine, a mineral found deep in a planetary mantle.

101429 and its brethren also have something to teach us about  finding the Earth Trojans, if they exist. Previous work by the team had shown that solar radiation causes debris, in the form of boulder- or city-block-sized chunks, from these asteroids to slowly leak out of the Trojan clouds of Mars. If the Earth Trojans are anything like Mars’s, the same mechanism would act as a source of small near-Earth asteroids that will stand out because of their uncommon composition.

Finding these objects might turn out to be a job for the Vera C. Rubin Observatory, poised to begin the most ambitious survey of the solar system to-date. Rubin is expected to discover roughly ten times as many asteroids as currently known and, along with the GAIA satellite already surveying the sky from the L2 Earth-Sun Lagrange point, may offer us the best near-term prospects for tracking down the debris of Earth’s Trojan companions.

The paper describing the research is freely accessible at https://arxiv.org/abs/2010.10947

Provided by Armagh Planet Observatory

Astronomers See Gigantic Collisions Of Galaxy Clusters In Young Universe (Astronomy)

An international team of researchers led by Leiden University (the Netherlands) has mapped nine gigantic collisions of galaxy clusters. The collisions took place seven billion years ago and could be observed because they accelerate particles to high speeds. It is the first time that collisions of such distant clusters have been studied. The researchers publish their findings in the journal Nature Astronomy on Monday evening 2 November.

Image of a distant cluster of galaxies (PSZ2 G091.83+26.11) at 7 billion light years from Earth. The most yellowish-white spots are complete galaxies, some spots are foreground stars. The X-rays (blue) stem from gas of about 10 million to 100 million degrees hot. The radio waves (red) originate from particles that have been accelerated to almost the speed of light. Credit: PanSTARRS/NASA/ Chandra/LOFAR

Galaxy clusters are the largest structures in the Universe. They can consist of thousands of galaxies, each with billions of stars. When such clusters merge, the electrons between them are accelerated to almost the speed of light. The accelerated particles emit radio waves when they come into contact with magnetic fields in the clusters.

Until now, telescopes were not powerful enough to receive radio waves from distant colliding clusters. But thanks to the Dutch-European network of linked LOFAR antennas and an ‘exposure time’ of eight hours per cluster, the researchers were able to collect detailed data from distant clusters for the first time.

The data show, among other things, that the radio emission from distant colliding clusters is brighter than previously expected. According to prevailing theories, cluster radio emission originates from electrons that are accelerated by the turbulent motions. Research leader Gabriella Di Gennaro, Ph.D. candidate at Leiden University (the Netherlands) adds, “We therefore think that the turbulence and vortices caused by the collisions are strong enough to accelerate particles also in a young Universe.”

Furthermore, the magnetic fields in the distant clusters turned out to be about as strong as in previously investigated nearby clusters. According to co-author and magnetic field expert Gianfranco Brunetti (INAF-Bologna, Italy), this was unexpected: “We do not yet know how these magnetic fields can be so strong in a still young Universe, yet our study provides important constraints on their origin. We expect that future observations of distant clusters will provide more insight.”

References: Di Gennaro, G., van Weeren, R.J., Brunetti, G. et al. Fast magnetic field amplification in distant galaxy clusters. Nat Astron (2020). https://doi.org/10.1038/s41550-020-01244-5 link: http://www.nature.com/articles/s41550-020-01244-5

Provided by Netherlands Research School for Astronomy

New Study Into A Rare Type Of Cancer In Abdomen Lining Shows Possible Immunotherapy Treatment (Medicine)

A new study from the University of Birmingham has found that 50% of patients with a rare type of cancer that has spread into the lining of their abdomen may be suitable for immunotherapy treatment.

For around 1% of bowel cancer patients, their cancer spreads to the lining of their abdomen (peritoneal cavity) – known as colorectal peritoneal metastasis (CPM). © University of Birmingham

Unfortunately for around 1% of bowel cancer patients, their cancer spreads to the lining of their abdomen (peritoneal cavity) – known as colorectal peritoneal metastasis (CPM).

This type of spread in bowel cancer patients carries a very poor prognosis and so most patients do not survive beyond 12 months from diagnosis.

Patients with CPM have a limited survival rate with the best available treatments.

Conventional chemotherapy is ineffective, and current treatment consists of extensive surgery which does not always work.

This first of its kind study funded by Good Hope Hospital Charity, found that understanding the tumour biology may identify which patients with bowel cancer are at risk of developing CPM.

Results published in Scientific Reports show that by identifying the specific tumour biology of this groups of patients, they carry a specific mutation that makes them sensitive to immunotherapy.

Lead author, Professor Andrew Beggs from the University of Birmingham’s Institute of Cancer and Genomic Sciences, said: “We have found that approximately 50% of patients with CPM have a type of genetic change, called hypermutation. This means they may be sensitive to immunotherapy as this type of treatment has good results in other patient groups with hypermutations.

“We also found potential sensitivity to a drug called a Porcupine inhibitor, based on another genetic marker identified in these patients.

“This is the first study of its kind in the world for patients with CPM, and our results have shown this could provide a potentially curative option for patients given the responses we have seen to immunotherapy in other cancers.”

Researchers will now look to set up an international clinical trial to examine the use of immunotherapy for patients with CPM.

References: Hallam, S., Stockton, J., Bryer, C. et al. The transition from primary colorectal cancer to isolated peritoneal malignancy is associated with an increased tumour mutational burden. Sci Rep 10, 18900 (2020). https://doi.org/10.1038/s41598-020-75844-6 link: https://www.nature.com/articles/s41598-020-75844-6

Provided by University of Birmingham

New Mineral Discovered In Moon Meteorite (Planetary Science)

Donwilhelmsite is important for understanding the inner structure of the earth.

A team of European researchers discovered a new high-pressure mineral in the lunar meteorite Oued Awlitis 001, named donwilhelmsite [CaAl4Si2O11]. The team around Jörg Fritz from the Zentrum für Rieskrater und Impaktforschung Nördlingen, Germany and colleagues at the German Research Centre for Geoscience GFZ in Potsdam, Museum für Naturkunde Berlin, Natural History Museum Vienna, Institute of Physics of the Czech Academy of Science, Natural History Museum Oslo, University of Manchester, and Deutsches Zentrum für Luft und Raumfahrt Berlin published their findings in the scientific journal “American Mineralogist”.

Scanning electron microscope image of the new mineral, Donwilhelmsite, in the lunar meteorite Oued Awlitis 001. © Museum für Naturkunde Berlin, Ansgar Greshake.

Besides the about 382 kilograms of rocks and soils collected by the Apollo and Luna missions, lunar meteorites allow valuable insights into the formation of the Moon. They are ejected by impacts onto the lunar surface and subsequently delivered to Earth.

Some of these meteorites experienced particularly high temperatures and pressures. The extreme physical conditions often led to shock melting of microscopic areas within these meteorites. These shocked areas are of great relevance as they mirror pressure and temperature regimes similar to those prevailing in the Earth’s mantle. Therefore, the microscopic shock melt areas are natural crucibles hosting minerals that are otherwise naturally inaccessible at the Earth’s surface. Minerals like wadsleyite, ringwoodite, and bridgmanite, constitute large parts of the Earth’s mantle. Theses crystals were synthesized in high-pressure laboratory experiments. As natural minerals they were first described and named based on their occurrences in meteorites.

Fragments of the lunar meteorite Oued Awlitis 001 acquired by the NHM Vienna and used for the scientific analyses. The largest specimen is on display at the NHM Vienna. © NHM Vienna, Ludovic Ferrière.

The new mineral donwilhelmsite is the first high-pressure mineral found in meteorites with application for subducted terrestrial sediments. It is mainly composed of calcium, aluminum, silicon, and oxygen atoms. Donwilhelmsite was discovered within shock melt zones of the lunar meteorite Oued Awlitis 001 found in 2014 in the Western Sahara. This meteorite is compositionally similar to rocks comprising the Earth’s continents. Eroded sediments from these continents are transported by wind and rivers to the oceans, and subducted into the Earth’s mantle as part of the dense oceanic crust. While being dragged deeper into the Earth mantle the pressure and temperature increases, and the minerals transform into denser mineral phases. The newly discovered mineral donwilhelmsite forms in 460 to 700 kilometre depth. In the terrestrial rock cycle, donwilhelmsite is therefore an important agent for transporting crustal sediments through the transition zone separating the upper and lower Earth’s mantle.

Electron diffraction pattern from one direction and the crystal structure model of donwilhelmsite. © Institute of Physics of the Czech Academy of Science, Mariana Klementova.

This pan-European collaboration was essential to obtain the lunar meteorite, recognize the new mineral, understand its scientific relevance, and to determine the crystal structure of the tiny, the thousands part of a millimeter thick, mineral crystal with high accuracy. “At the GFZ, we used transmission electron microscopy to investigate microstructural aspects of the samples,” says Richard Wirth from the section “Interface Geochemistry”. “Our investigations and the crystal structure analyses of the colleagues from the Czech Republic once again underline the importance of transmission electron microscopy in the geosciences”.

The new mineral was named in honor of the lunar geologist Don E. Wilhelms, an American scientist involved in landing site selection and data analyses of the Apollo space missions that brought to Earth the first rock samples from the Moon. Part of the meteorite Oued Awlitis 001, acquired by crowdfunding initiative „Help us to get the Moon!”, is on display at the Natural History Museum Vienna.

References: Fritz, J., Greshake, A., Klementova, M., Wirth, R., Palatinus L. L. , Trønnes, R. G., Assis Fernandes, V., Böttger, U., Ferrière, L, 2020. American Mineralogist. Donwilhelmsite, [CaAl4Si2O11], a new lunar high-pressure Ca-Al-silicate with relevance for subducted terrestrial sediments. DOI: 10.2138/am-2020-7393 https://pubs.geoscienceworld.org/msa/ammin/article-abstract/105/11/1704/592180/Donwilhelmsite-CaAl4Si2O11-a-new-lunar-high?redirectedFrom=fulltext

Provided by GFZ, Pottsdam

Plant Viruses Hijack The Defence System Of Plants, But There Might Be A Way To Strike Back (Botany)

Many diseases caused by common plant viruses reduce the crops of important food plants. In the worst case, potato viruses, among others, can destroy as much as 80% of crops on infected fields.

Plants are not entirely defenceless against viruses, although they lack an immune system like the one found in humans. For plant cells, the primary defence mechanism against viral infections is gene silencing. By utilising the mechanism, plant cells identify the foreign genetic material originating in the virus and cut it up into small pieces.

“In turn, these bits of the genome guide plant cell proteins to identify and destroy viral genomes. As a result, the production of viral proteins ends, which is interpreted as ‘silencing’ of the viral genes. A successful defensive response prevents the virus from spreading in the plant,” says Docent Kristiina Mäkinen from the Faculty of Agriculture and Forestry, University of Helsinki.

Viruses can hijack the plant’s defence system

At the same time, viruses too have means with which to resist and subvert the host plant’s defence mechanisms. A research group specialised in plant virology, led by Mäkinen, investigates the interaction between potato virus A and host plant proteins. Mäkinen and her group find one viral protein particularly interesting, as it is directed against the plant’s defence system.

“This protein is able to not only block gene silencing, but also to harness the factors involved in the process to serve both its viral replication and the formation of new viral particles. In other words, the virus forces, as it were, the plant’s defence system to go against its intended purpose, in favour of the pathogen.”

Genes play a part in resistance – Modern plant breeding techniques needed

Studies on plants that are naturally resistant to viruses have shown that their resistance is often based on mutations in the plant’s genome that block interaction between viral and plant proteins. To employ these mutations in plant breeding, University Researcher Maija Pollari considers it necessary to start utilising modern plant breeding techniques.

“For instance, the CRISPR/Cas9 technique, which was just awarded the Nobel Prize in Chemistry, makes it possible to target anti-viral mutations in a precise location in the plant genome. This is a great stride forward compared to traditional plant breeding, which relies on the use of mutagenic chemicals and radioactive radiation,” Pollari adds.

The interactions between plant and viral proteins discovered by Kristiina Mäkinen’s research group offer new targets for breeding resistance against the potato virus in host plants. The researchers’ aim is to identify a component in the plant proteins through which they come into contact with viral proteins.

“When proteins are modified so that the interaction is blocked, the plant’s gene silencing mechanism may regain the upper hand over the virus. Strains resistant to viruses used in cultivation reduce losses caused by viral diseases and, consequently, improve yields. Furthermore, it’s likely that the chemical burden of the environment is alleviated, as the amount of chemicals used in preventing aphids is reduced,” notes Kristiina Mäkinen.

References: Pollari M, De S, Wang A, Mäkinen K (2020) The potyviral silencing suppressor HCPro recruits and employs host ARGONAUTE1 in pro-viral functions. PLoS Pathog 16(10): e1008965. doi:10.1371/journal.ppat.1008965 link: https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1008965

Provided by University Of Helsinki

Model Of Multicellular Evolution Overturns Classic Theory (Biology)

Physicists and biologists challenge a prevailing evolutionary theory that single-celled organisms can only evolve to become multicellular life forms if doing so increases their overall productivity.

Cells can evolve specialised functions under a much broader range of conditions than previously thought, according to a study published today in eLife.

The findings, originally posted on bioRxiv*, provide new insight about natural selection, and help us understand how and why common multicellular life has evolved so many times on Earth.

Life on Earth has been transformed by the evolution of multicellular life forms. Multicellularity allowed organisms to develop specialised cells to carry out certain functions, such as being nerve cells, skin cells or muscle cells. It has long been assumed that this specialisation of cells will only occur when there are benefits. For example, if by specialising, cells can invest in two products A and B, then evolution will only favour specialisation if the total output of both A and B is greater than that produced by a generalist cell. However, to date, there is little evidence to support this concept.

“Rather than each cell producing what it needs, specialised cells need to be able to trade with each other. Previous work suggests that this only happens as long as the overall group’s productivity keeps increasing,” explains lead author David Yanni, PhD student at Georgia Institute of Technology, Atlanta, US. “Understanding the evolution of cell-to-cell trade requires us to know the extent of social interactions between cells, and this is dictated by the structure of the networks between them.”

To study this further, the team used network theory to develop a mathematical model that allowed them to explore how different cell network characteristics affect the evolution of specialisation. They separated out two key measurements of cell group fitness – viability (the cells’ ability to survive) and fecundity (the cells’ ability to reproduce). This is similar to how multicellular organisms divide labour in real life – germ cells carry out reproduction and somatic cells work to ensure the organism survives.

In the model, cells can share some of the outputs of their investment in viability with other cells, but they cannot share outputs of efforts in reproduction. So, within a multicellular group, each cell’s viability is the return on its own investment and that of others in the group, and gives an indication of the group’s fitness.

By studying how the different network structures affected the group fitness, the team came to a surprising conclusion: they found that cell specialisation can be favoured even if this reduces the group’s total productivity. In order to specialise, cells in the network must be sparsely connected, and they cannot share all the products of their labour equally. These match the conditions that are common in the early evolution of multicellular organisms – where cells naturally share viability and reproduction tasks differently, often to the detriment of other cells in the group.

“Our results suggest that the evolution of complex multicellularity, indicated by the evolution of specialised cells, is simpler than previously thought, but only if a few certain criteria are met,” concludes senior author Peter Yunker, Assistant Professor at Georgia Institute of Technology, Atlanta, US. “This contrasts directly to the prevailing view that increasing returns are required for natural selection to favour increased specialisation.”

References: David Yanni, Shane Jacobeen, Pedro Márquez-Zacarías, Joshua S Weitz, William C. Ratcliff, Peter J. Yunker, “Topological constraints in early multicellularity favor reproductive division of labor”, bioRxiv 842849; doi: https://doi.org/10.1101/842849 link: https://www.biorxiv.org/content/10.1101/842849v1

Provided by ELIFE

RUDN University Chemists Developed New Magnetic And Luminescent Lanthanide-siloxane-based Compounds (Chemistry)

A team of chemists from RUDN University synthesized new organosilicon compounds containing terbium and europium ions. These complexes have an unusual cage-like crystal structure that contains four metal ions. The team was the first to study the magnetic and photophysical properties of such compounds and to observe their magnetic phase transition and luminescence properties. The results of the work were published in Chemistry – A European Journal.

A team of chemists from RUDN University synthesized new organosilicon compounds containing terbium and europium ions. These complexes have an unusual cage-like crystal structure that contains four metal ions. The team was the first to study the magnetic and photophysical properties of such compounds and to observe their magnetic phase transition and luminescence properties. ©RUDN University.

Cakelike Metal-containing silsesquioxanes (CLMSs) are complex organo-inorganic compounds that contain carbon, silicon, and metal atoms bound with each other. Chemists are interested in CLMSs because their molecules can form various cagelike structures and extended 3D derivatives. Different molecular structures and metal atoms give silsesquioxanes special physical properties, for example, making them promising catalysts for important organic synthesis reactions. A team of chemists from RUDN University obtained four new metal-containing silsesquioxanes and studied their luminescence and magnetic properties.

Complexes obtained by the team are based on the lanthanide metals, namely, terbium and europium. Lanthanide compounds are known for their unusual magnetic and optical properties: the former make them an excellent source for the production of contrast agents for medical applications, and the latter – materials for electroluminescent devices. However, until this work, these properties had never been studied in detail for lanthanide-containing cage silsesquioxanes. Compounds obtained by the team have an unusual structure that has never been observed before, with prism-shaped cage including central core with four lanthanide atoms. This central layer is coordinated by two cyclic silsesquioxane fragments, solvent molecules, and organic (phosphorus- or nitrogen-containing) cations. Notably, terbium compounds synthesized by the team were the first-ever silsesquioxanes to contain this metal.

“Until recently, only two types of lanthanide CLMSs had been known and had undergone X-ray diffraction study. The first type was cubane siloxane compounds – cube-shaped structures with a lanthanide atom in each corner. The second was the so-called sandwiches: two siloxane fragments with a layer of lanthanide ions and alkaline metals laying between them. Both types were only considered as unusual structural types and/or catalytic system models, and their optical and magnetic properties were largely understudied,” said Dr. Alexey Bilyachenko, a Deputy Head of the Joint Institute for Chemical Research at RUDN University.

To obtain new compounds, the team developed a two-step reaction. First, a reactive substance (sodium phenylsiloxanolate) was synthesized. Second, the so-called self-assembly reaction took place: sodium phenylsiloxanolate (in the presence of organic cations) formed a regular structure due to coordination to lanthanide ions. X-ray diffraction analysis allowed to establish the structure of the products and identified fourmembered siloxane cycles in their structures. Previously, such cycles have only been observed in titanium- and cobalt-based CLMSs.

Magnetic properties of lanthanide-based silsesquioxanes were investigated for the first time. The terbium-based compound demonstrated the magnetic spin flip effect (i.e. the switch from antiferromagnetic behaviour into a ferromagnetic one).

To study the optical properties of the substances, the team subjected them to photoexcitation under the influence of UV or visible blue light. The compounds demonstrated characteristic luminescence: europium-containing substances provided red emission, while terbium-containing ones provided a green one. Therefore, these compounds turned out to be the first CLMSs with magnetic and luminescent properties studied in detail.

References: http://dx.doi.org/10.1002/chem.202003351

Provided by RUDN University

The Birth Of A Bacterial tRNA Gene (Biology)

The Microbial Evolutionary Dynamics Group at the Max Planck Institute for Evolutionary Biology in Plön has directly observed the birth of a tRNA gene, using experimental evolution of bacterial populations in the laboratory.

Schematic of a tRNA molecule. The anticodon matches codons (in genetic information) to amino acids (that make up proteins). © Max planck institute.

Translation is the process by which genetic information is converted into proteins, the workhorses of the cell. Small molecules called transfer RNAs (“tRNAs”) play a crucial role in translation; they are the adapter molecules that match codons (the building blocks of genetic information) with amino acids (the building blocks of proteins). Organisms carry many types of tRNAs, each encoded by one or more genes (the “tRNA gene set”).

Broadly speaking, the function of the tRNA gene set – to translate 61 types of codons into 20 different kinds of amino acids – is conserved across organisms. Nevertheless, tRNA gene set composition can vary considerably between organisms. How and why these differences arise has been a question of long-standing interest among scientists.

Evolution of a bacterial tRNA set in the lab

The deletion of one tRNA gene (red X) is compensated by duplication of another tRNA gene (green). ©Max planck Institute.

Jenna Gallie (Research Group Leader at the Max Planck Institute for Evolutionary Biology) and her team have investigated how the tRNA gene set of the bacterium Pseudomonas fluorescens can evolve, using a combination of mathematical modelling and lab-based experiments. “We started by removing one type of tRNA from the bacterium’s genome, resulting in a bacterial strain that grows slowly. We gave this slow-growing strain the opportunity to improve its growth during a real-time evolution experiment. We saw the strain improve repeatedly and rapidly. The improvement was due to the duplication of large chunks of bacterial genetic information, with each duplication containing a compensatory tRNA gene. Ultimately, the elimination of one tRNA type was compensated by an increase in the amount of a second, different tRNA type.” Jenna Gallie said. The duplicated tRNA type can compensate because it is able to perform, at a lower rate, the codon-amino acid matching function of the eliminated tRNA type.

The first direct observation of tRNA gene duplication

Comparisons of tRNA genes in related genomes have previously provided evidence for the duplication of some tRNA genes throughout evolutionary history. The experiments described here provide direct, empirical evidence that tRNA gene sets can evolve through duplication events.

References: Ayan, G.; Park, H.J.; Gallie, J.
The birth of a bacterial tRNA gene by large-scale, tandem duplication events
eLife 2020;9:e57947 https://elifesciences.org/articles/57947

Provided by Max Planck Gesellschaft