How Brain Cells Compensate For Damage From A Stroke? (Neuroscience)

New results challenge the current model of how the brain can reorganize in the aftermath of stroke damage

A study from UCLA neurologists challenges the idea that the brain recruits existing neurons to take over for those that are lost from stroke. It shows that in mice, undamaged neurons do not change their function after a stroke to compensate for damaged ones.

A stroke occurs when the blood supply to a certain part of the brain is interrupted, such as by a blood clot. Brain cells in that area become damaged and can no longer function.

A person who is having a stroke may temporarily lose the ability to speak, walk, or move their arms. Few patients recover fully and most are left with some disability, but the majority exhibit some degree of spontaneous recovery during the first few weeks after the stroke.

Doctors and scientists don’t fully understand how this happens, because the brain does not grow new cells to replace the ones damaged by the stroke. Neurologists have generally assumed that the brain instead recruits existing neurons to take over for those that are lost.

Now, new results from neurologists William Zeiger and Carlos Portera-Cailliau from the David Geffen School of Medicine at UCLA challenge that idea. In their paper, published June 25 in the journal Nature Communications, they show that in mice, undamaged neurons do not change their function after a stroke to compensate for damaged ones.

Neurologists have been “mapping” the brain since the mid-1800s, when the French physician Paul Broca realized that patients who sustained damage to a certain part of the frontal lobe lost the ability to speak. Over the years, scientists have created increasingly detailed maps of which brain regions control various functions. Still, the resolution of the map has been limited by the precision of the tools available to study the living brain.

Studies in animals and humans that recorded activity across different brain regions have found that activity patterns change after a stroke, suggesting that the damaged brain can “re-map” functions from one area to another. In the last few years, innovative new tools have enabled researchers to start looking at individual neuron activation in real-time. By using a technique called two-photon fluorescence microscopy that causes neurons to light up when they are activated, researchers can observe which neurons in the animal brain are called upon during certain activities and determine if neurons that survived a stroke can assume the function of those that were lost.

“We thought, now that we have this tool where we can record the activity of neurons in the brain, we could directly test this question,” says Zeiger. By learning the functions of individual neurons, then causing a targeted stroke, the researchers could use the new technique to observe how the neighboring neurons responded.

Mice gather information about their environment primarily through their whiskers, and each whisker transmits sensory signals to a specific group of neurons. By destroying the neurons coded to a specific whisker, the researchers could look at whether neurons for a different whisker took over for their lost neighbors.

Think of a departmental office, says Portera-Cailliau. “Imagine that several admin staff in human resources for the Department of Neurology suddenly quit their jobs one day. Instantly, the department would suffer their absence, but would try to make up for it.” The department might do this by asking HR employees from other departments to do some of the missing employees’ work on top of their own.

That’s what the re-mapping hypothesis predicts would happen in the brain. “If the hypothesis were true, we would see cells that survived the stroke start to respond to that whisker that had the stroke,” Zeiger says. “What we found was that that didn’t happen.”

Adjacent to the main column of neurons that respond to a given whisker are neurons called “surround-responsive” cells. These are located in the column for one whisker, but they react to the stimulation of a neighboring whisker. Using the office analogy, these neurons would be like employees that work on HR but happen to have their desks in a different physical office.

Logically, then, the team thought that the surround-responsive neurons would be good candidates to take over when the primary responding neurons were destroyed by the stroke. “If the HR office suddenly shut down, you might think more people in these other offices would start doing human resource jobs,” Portera-Cailliau says. Yet not only did these other neurons fail to step up, the activity of the surround-responsive neurons themselves decreased after the stroke.

“That was pretty strong evidence against this remapping hypothesis,” Zeiger says. “It did not seem like there was bulk recruitment to take over the function which had been lost to stroke.”

More studies will be needed to gain a full understanding of what happens in the human brain after a stroke, including why spontaneous recovery happens. Zeiger says that future studies could also explore various ways to induce the surviving cells to compensate for the lost neurons.

“I think it gives the field more of a direction,” Zeiger says. “Rather than assuming the brain can remap on its own, now we know that to achieve full recovery, we’re going to need a way to get cells to do things they are not already doing.”


Reference: Zeiger, W.A., Marosi, M., Saggi, S. et al. Barrel cortex plasticity after photothrombotic stroke involves potentiating responses of pre-existing circuits but not functional remapping to new circuits. Nat Commun 12, 3972 (2021). https://doi.org/10.1038/s41467-021-24211-8


Provided by UCLA Health

Biologists Determined the Structure of A Bacterial Protein Complex Critical For Tuberculosis Infection (Biology)

EMBL Hamburg’s Wilmanns and Kosinski groups have determined the detailed structure of a bacterial protein complex critical for tuberculosis infection

Tuberculosis is one of the top ten causes of death worldwide, infecting about one-quarter of the world’s population. Although it is treatable, the rise of multidrug-resistant tuberculosis poses a major threat to global health security, and has been declared by the World Health Organization as a global health emergency. Reduced access to diagnosis and treatment during the COVID-19 pandemic is expected to dramatically increase the number of tuberculosis infections. This will set global efforts to tackle the disease back several years.

Tuberculosis is caused by infection with Mycobacterium tuberculosis: a bacterium that infects human lungs and other organs by using complex molecular machineries. These include protein complexes known as type VII secretion systems, which enable M. tuberculosis to release molecules into its host, which disarm and ultimately kill the infected human cell. Five such secretion systems, labelled ESX-1 to ESX-5, are found among M. tuberculosis and other closely related mycobacteria, many of which are pathogenic. Without them, the bacteria are unable to infect human cells.

The Wilmanns group at EMBL Hamburg has been using high-resolution structural biology to study mycobacterial proteins for the last two decades. The molecular understanding of the bacterial machinery used to infect cells resulted in collaborations with industry to develop new drugs against tuberculosis. In their most recent study, they determined the molecular structure of the secretion system ESX-5 to a high level of detail. They saw that the core of ESX-5 is built of 30 protein units, which form a dynamic membrane pore to allow secretion of proteins that enable the bacterium to survive and multiply inside human cells. Knowledge of the ESX-5 structure at high-resolution is essential to target specific sites with small-molecule drugs.

“Our new structure of the ESX-5 secretion complex provides deep insight into a major sluice gate that separates the inner of these bacteria from the outer host environment. Opening this gate allow the pathogen to spit out its deadly weapons to infect humans to develop tuberculosis. We can use this structure as a toolbox with literally thousands of potential drug targets. This will open an entirely new field of studies on tuberculosis,” says Matthias Wilmanns, who leads the study. Kate Beckham, who developed an innovative way to isolate ESX-5, adds: “The central pore we saw in ESX-5 could serve as a new drug target. Blocking it could prevent infection with pathogenic mycobacteria.”

The study could also help scientists to develop new vaccines for tuberculosis. The widely used Bacillus Calmette–Guérin (BCG) vaccine, which has its 100th anniversary this year, is based on a strain of mycobacterium that has lost its ability to cause disease because of a defect in the ESX-1 system. However, as BCG vaccination offers insufficient protection and is most effective in young infants only, alternative vaccines are urgently needed. Due to its close structural and functional relation with ESX-1, targeting the ESX-5 secretion system might spur the development of new vaccines that could complement or replace those currently used.

Determining the molecular structure of ESX-5 was particularly challenging because of its large size and complexity. No single structural biology method can provide the full picture. In this case, the key to success was using integrative structural biology, in which data obtained using different methods – cryo-electron microscopy, X-ray crystallography, mass spectrometry and computational methods – were used jointly to create a coherent model.

“Eighteen months ago, solving this structure looked like mission: impossible,” says Matthias Wilmanns. “We managed to put the puzzle pieces together because each team member contributed unique expertise. To solve the complete structure, we collaborated with Jan Kosinski’s group at EMBL Hamburg and the Centre for Structural Systems Biology, which provided necessary expertise in integrative structural biology. We also received great help from our colleagues at EMBL Heidelberg, who performed cryo-electron microscopy experiments.”

This study illustrates some of EMBL’s approaches to life science research in its forthcoming scientific programme, Molecules to Ecosystems 2022–2026. As part of this programme, EMBL will take an interdisciplinary approach to understanding the molecular basis of life in the context of environmental changes. This will provide translational potential to support advances in human and planetary health.

EMBL’s approach, including this study, is aligned with the collaborative efforts of other research groups and institutions from Northern Germany working together at the Centre for Structural Systems Biology.

Featured image: The mycobacterial ESX-5 secretion system is located in the bacterial inner membrane and consists of six units, which assemble into a symmetrical structure with a pore at the centre. Credit: Isabel Romero Calvo/EMBL


Source article(s)


Provided by EMBL

Test Distinguishes SARS-CoV-2 From Other Coronaviruses with 100% Accuracy (Medicine)

Platform could also predict COVID-19 case severity and immunity against variants

Biomedical engineers at Duke University have demonstrated a tablet-sized device that can reliably detect multiple COVID-19 antibodies and biomarkers simultaneously.

Initial results show the test can distinguish between antibodies produced in response to SARS-CoV-2 and four other coronaviruses with 100% accuracy.

The researchers are now working to see if the easy-to-use, energy-independent, point-of-care device can be used to predict the severity of a COVID-19 infection or a person’s immunity against variants of the virus.

Having also recently shown the same “D4 assay” platform can detect Ebola infections a day earlier than the gold standard polymerase chain reaction (PCR) test, the researchers say the results show how flexible the technology can be to adapt to other current or future diseases.

The results appear online on June 25 in Science Advances.

“The D4 assay took six years to develop, but when the WHO declared the outbreak a pandemic, we began working to compress all of that work into a few months so we could explore how the test could be used as a public health tool,” said Ashutosh Chilkoti, the Alan L. Kaganov Distinguished Professor and Chair of Biomedical Engineering at Duke. “Our test is designed to be both adaptable and truly point-of-care, and this is clearly a scenario when a portable, fast and cost-effective diagnostic would be most useful.”

This point-of-care device uses the physics of fluids to draw a few drops of blood and biomedical lubricant through its components to test for COVID-19 antibodies and biomarkers without the need of any electricity. © Jake Heggestad

The technology hinges on a polymer brush coating that acts as a sort of non-stick coating to stop anything but the desired biomarkers from attaching to the test slide when wet. The high effectiveness of this non-stick shield makes the D4 assay incredibly sensitive to even low levels of its targets. The approach allows researchers to print different molecular traps on different areas of the slide to catch multiple biomarkers at once.

The current iteration of the platform also features tiny patterned tunnels that use the physics of liquids to draw samples through the channels without needing any electricity. With just a drop of blood and a drop of biomolecular lubricant, the test runs autonomously in a matter of minutes and can be read with a detector roughly the size of a very thick iPad.

“The detector is battery powered and the test doesn’t require any power at all, so you can throw the whole thing into a backpack and truly test at the point-of-care with minimal resources,” said Jason Liu, a PhD student working in the Chilkoti lab who designed and built the detector.

In the current study, the researchers tested the D4 assay’s ability to detect and quantify antibodies produced against three parts of the COVID-19 virus — a subunit of the spike protein, a binding domain within the spike protein that grabs on to cells, and the nucleocapsid protein that packages the virus’s RNA. The test was able to spot the antibodies in all of the 31 patients tested with severe cases of COVID-19 after two weeks. It also reported zero false-positives in 41 samples taken from healthy people before the pandemic started as well as 18 samples taken from individuals infected with four other widely circulating coronaviruses.

With the pandemic on the downswing in the United States and hundreds of other COVID-19 antibody tests in development, the researchers don’t believe this particular test is likely to be deployed in large numbers. But they say that the platform’s proven accuracy and flexibility make it a prime candidate for developing into other types of tests or for use in future outbreaks.

For example, the platform could potentially be able to test whether or not people have immunity to the various strains of COVID-19 that continue to emerge.

“There’s lots of questions from people about whether or not they’re protected from new variants of COVID-19, and our test could answer some of those,” said Jake Heggestad, a PhD student working in the Chilkoti lab who developed the chip for the test. “We believe that our platform should be able to distinguish between whether people have antibodies that can neutralize emerging variants of concern or if those antibodies aren’t going to be protective against new variants.”

The researchers are also working to develop the platform into a test for multiple prognostic markers of COVID-19 that together could indicate whether or not a patient is likely to have a severe case of the disease.

“We’re platform builders, so we’re working to show ways this technology can be easily modified to do different things,” said David Kinnamon, a graduate student who developed the liquid handling system for the test. “We’re showing this single platform can work as a diagnostic, assess immune response after infection and predict disease outcome, potentially all at the same time. I don’t know of many tests that can do that.”

“And it can do all of this on a platform that is super user-friendly and transportable,” said Heggestad. “It’s one thing to do all of this in a centralized facility like Duke, but it’s another to be able to do large-scale testing and get good, sensitive results in remote locations around the world.”

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This research was supported by the National Science Foundation (CBET2029361), the National Cancer Institute (P30-CA014236, R01-CA248491, UH3-CA211232), the Department of Defense (W81XWH-16-C-0219), Defense Academy of the United Kingdom (ACC6010469), and the Combat Casualty Care Research Program (W81XWH-17-2-0045).

Featured image: The D4 assay is read by this battery-powered, tablet-sized scope, allowing the whole thing to be thrown into a backpack and be used at the point-of-care with minimal resources. © Jake Heggestad


Reference: “Multiplexed, Quantitative Serological Profiling of COVID-19 from Blood by a Point-Of-Care Test,” Jacob T. Heggestad, David S. Kinnamon, Lyra B. Olson, Jason Liu, Garrett Kelly, Simone A. Wall, Solomon Oshabaheebwa, Zachary Quinn, Cassio M. Fontes, Daniel Y. Joh, Angus M. Hucknall, Carl Pieper, Jack G. Anderson, Ibtehaj A. Naqvi, Lingye Chen, Loretta G. Que, Thomas Oguin III, Smita K. Nair, Bruce A. Sullenger, Christopher W. Woods, Thomas W. Burke, Gregory D. Sempowski, Bryan D. Kraft, Ashutosh Chilkoti. Science Advances, June 25, 2021. DOI: sciadv.abg4901


Provided by Duke University

Longest Known SARS-CoV-2 Infection of Nearly 300 Days Successfully Treated With New Therapy (Medicine)

An immunocompromised individual with the longest known PCR confirmed case of SARS-CoV-2 infection, lasting more than 290 days, has been successfully treated with two investigational monoclonal antibodies (laboratory engineered antibodies). Clinicians and researchers from the University of Bristol and North Bristol NHS Trust (NBT) worked closely to assess and treat the infection and want to highlight the urgent need for improved access to treatments for such people with persistent SARS-CoV-2 infection.

The team were able to finally treat the individual successfully with a mixture of two monoclonal antibodies, casirivimab and imdevimab, supplied on a compassionate use basis by Regeneron. Importantly, the researchers found, and have reported in a paper published on the preprint server medRxiv.org, that the virus evolved during the infection, acquiring mutations that are present in SARS-CoV-2 variants of concern (VOCs). 

The study shows the success of a specific treatment regime however, it is not yet clinically approved for use in the UK.  The case demonstrates that there may be potential treatments for immunocompromised individuals with persistent SARS-CoV-2 infection and these need more investigation.  The findings also raise the urgent need to conduct trials of, and improve access to regimes capable of eradicating the virus from continually infected people.

Dr Andrew Davidson, a virologist in Bristol’s School of Cellular and Molecular Medicine, a member of the ‘G2P-UK’ National Virology Consortium and co-author on the paper, said: “There are increasing reports of immunocompromised people who are repeatedly infected with SARS-CoV-2 for longer than six months. As the virus can evolve in this group, and develop mutations that are present in emerging VOCs, it is key that we monitor the evolution of the virus in these individuals and effective treatment options are available to eliminate the virus.”

Dr Ed Moran, Consultant in Infectious Diseases at NBT and co-author on the paper, added: “It is wonderful that we were able to help this individual. Whilst such cases are rare there will be a number of people across the country in similar situations. The small numbers make it difficult to perform trials of experimental therapies. However, it is important that we find a way to access and develop treatment regimens for these individuals both for the wellbeing of the individual and to protect public health.”

The preprint paper describes an immunocompromised individual with persistent SARS-CoV-2 infection, who regularly tested positive for SARS-CoV-2 and viral viability was confirmed six months after they were initially diagnosed.  The virus did not clear in the individual after being treated with a 15-day course of Remdesivir, 213 days after their first positive PCR test.  On day 265, the individual was treated with two monoclonal antibodies, casirivimab and imdevimab.  The individual’s health improved dramatically, and the virus was not detected in PCR tests 45 days after the combined treatment.

Next generation sequencing showed the spike protein had acquired two deletions (ΔH69/ΔV70) before the combined treatment.  Theses deletions are present in the B.1.1.7 (Alpha) VOC and have been associated with virus mutations after treatment of another immunocompromised person with convalescent plasma. The study’s data confirms the significance of this deletion in immunocompromised individuals and shows it can develop independently of passive antibody transfer, suggesting the deletion may be an enabling mutation.

The paper suggests immune-deficient people are vulnerable to chronic persistent SARS-CoV-2 infection. Whilst being diagnosed with SARS-CoV-2 may not result in acute illness needing hospitalisation, it could lead to fatigue, malaise and breathing difficulties. This could lead to an infection control risk, with people infected with SARS-CoV-2 developing new mutations.

The research team plan to further characterise the immune response in the individual under investigation to establish whether any of the mutations that evolved in the virus occurred in response to host immune pressure.  The researchers are also working closely with other persistently infected immunocompromised individuals and hope to analyse the virus in these individuals with a view to developing better treatment options.

The study was funded by the Southmead Hospital CharityUK Research and Innovation (UKRI), Medical Research Council and the United States Food and Drug Administration (FDA).  Immunological work was funded by the University’s Elizabeth Blackwell Institute and the research was also supported by Bristol’s Alumni and Friends.

Preprint paper

Chronic SARS-CoV-2 infection and viral evolution in a hypogammaglobulinaemic individual’ by Maia Kavanagh Williamson, Fergus Hamilton, Rachel Milligan, David A. Matthews, Ed Moran, Andrew D. Davidson et al in medRxiv

Please note this is a preprint, it is a preliminary piece of research that has not yet been through peer review and has not been published in a scientific journal – so this is early data.

Further information

The patient, Dave Smith
Dave Smith was first diagnosed with COVID-19 towards the end of March 2020 and remained positive until early March 2021.  During that time, he had over 40 positive PCR tests and seven hospital admissions, and his weight dropped to 64kg (around ten stone) from 120 kg (over 18 stone).

He was finally successfully treated with a mixture of two monoclonal antibodies, casirivimab and imdevimab, supplied on a compassionate use basis by Regeneron.

Dave said: “This treatment has changed my life immeasurable and probably saved the NHS thousands of pounds in hospital admissions.”

He is improving a little each day and looks forward to getting back to a near normal pre-COVID life in the not-too-distant future.

COVID-19 research outputs
A full list of University of Bristol research outputs relating to the COVID-19 pandemic is available online.


Provided by University of Bristol

New Research Brings Age Of 65M-Year-Old Meteorite Impact Into Sharper Focus (Planetary Science)

New research into one of the most volatile periods in Earth’s geological history has narrowed down the precise age of a meteorite impact in the Ukraine around 65 million years ago, ruling out the chance that it contributed to the extinction of the dinosaurs but offering new insight into the planet’s climate history.

A team of geologists, led by researchers from the University of Glasgow, applied state-of-the-art dating techniques to samples of melted rock created during the fiery landing of a giant meteorite in Ukraine’s Kivorohad Oblast region.

The explosive collision formed a 15-mile-wide basin known as the Boltysh impact crater, which over time filled with water and formed a lake.

Previous analysis of samples from the Boltysh crater, undertaken decades ago, suggested that the meteorite may have struck the Earth between two and five thousand years before the Chicxulub meteorite impact in Mexico’s Yucatán Peninsula. 

The Chicxulub impact is widely believed to have caused the mass extinction event which made non-avian dinosaurs extinct, and the climate event which created the geological signature known as the Cretaceous–Paleogene boundary. However, questions still remained over whether the Boltysh impact might have occurred close enough in time to have had an effect on both.

The new analysis, led by researchers from the University of Glasgow, suggests that, in fact, the impact happened around 650,000 years after the Chicxulub event.

The results, published today (Friday 18 June) in the journal Science Advances, provide further support for the Chicxulub extinction theory. The findings could also help us better understand how our atmosphere has responded to climate change in the past.

To determine the date of the Boltysh impact more precisely than ever before, the researchers selected four samples from two rock cores taken from the Boltysh crater, containing rocks generated during the impact event and lake sediments which accumulated over time after the crater was formed. They determined the age of the samples using the argon-argon dating facility run by Professor Darren Mark at the Scottish Universities Environmental Research Centre in East Kilbride. 

A picture of fragments of a sediment core taken from the Boltysh impact crater in the Ukraine
A picture of fragments of a sediment core taken from the Boltysh impact crater in the Ukraine © University of Glasgow

Argon-argon dating measures the radioactive decay of potassium to argon. The level of decay acts as a ‘rock clock’, which ticks down over geological time and allows researchers today to determine when the rocks were created during the Boltysh impact event.

Dr Annemarie Pickersgill, research associate in meteorite impacts at the University of Glasgow’s School of Geographical and Earth Sciences, led the research. Dr Pickersgill said: “Thanks to the efforts of researchers around the world, argon-argon dating has become increasingly accurate over the last few years. That gives us a much sharper lens to examine the details of events like the Boltysh impact, and be able to determine with much more confidence exactly when they happened.

“Our analysis suggests that the impact occurred very close to 65.39 million years ago. That puts it firmly after the Chicxulub impact and the formation of the Cretaceous-Paleogene boundary, evidence for which is found in geological records around the world.

“Instead, the results allow us to place the Boltysh impact more accurately in our timeline of what happened to the Earth in the period after this mass extinction event, and better understand our deep geological history.”

In the paper, the researchers draw links for the first time between their new dating of the Boltysh impact and evidence for a known ‘hyperthermal’ event found in the Earth’s sediment record – a period of extreme global heating scientists call the lower C29N hyperthermal.

At that time in Earth’s history, volcanoes in India known as the Deccan Traps were releasing vast amounts of greenhouse gases into the atmosphere, accelerating a period of global climate change. Evidence of the Deccan Traps’ contribution to climate change has been found in sediment records around the world.

Dr Pickersgill added: “Paleoclimatology aims to help us understand and adapt to today’s changing climate by studying how our atmosphere responded to environmental stresses in the past.

“Being able to link the Boltysh lake sediments to the lower C29N hyperthermal is another piece of the jigsaw which will form a clearer picture of how our planet has responded to climate change in the past.”

The team’s paper, titled ‘The Boltysh impact structure: An early Danian impact event during recovery from the K-Pg mass extinction’, is published in Science Advances. Researchers from the Universities of Glasgow, St Andrews, Leeds, and Aberdeen, contributed to the paper. The research was supported by funding from the National Environment Research Council (NERC) and the Leverhulme Trust.

With support from the Leverhulme Trust, Dr Pickersgill will continue to study the effects of impact craters on Earth’s history.

Featured image: Dr. Annemarie Pickersgill of the University of Glasgow and co – author Prof. Simon Kelley with the Boltysh rock core discussing climate implications of a medium sized impact . © University of Glasgow


Provided by University of Glasgow

Triple Endosymbiosis Discovered (Biology)

The intracellular sulfur-purple bacterium “Candidatus Thiodictyon intracellulare” has lost the ability to oxidize sulfur and now supplies an eyelash animal with energy from photosynthesis / YouTube video available

A research team led by Dr. Sebastian Hess from the Institute of Zoology at the University of Cologne has discovered a very rare and puzzling triple endosymbiosis, which consists of an eyelash animal, a green alga and a previously unknown purple bacterium. As the researchers found out through genome analyzes of the pink-green ciliate, the bacteria involved belongs to the so-called sulfur-purple bacteria (family Chromatiaceae ), but has given up the otherwise typical oxidation of sulfur compounds. The genome of the purple bacterium is greatly reduced and suggests that the bacterium is now mainly in the service of carbon fixation and is no longer viable on its own. The new bacterial species “Candidatus Thiodictyon intracellulare” represents a remarkable exception among the previously known sulfur purple bacteria . The article“ A microbial eukaryote with a unique combination of purple bacteria and green algae as endosymbionts ”in the renowned journal Science Advances presents this new discovery and explains how the oxygen-sensitive purple bacterium lives together with green algae and ciliate animals.

The pink-green ciliate Pseudoblepharisma tenue lives in the low-oxygen sediments of the Simmelried, a moor system near Konstanz on Lake Constance. For a number of years now, with Dr. Hess hobby microscopist Dr. Martin Kreutz the occurrence of this unusual way of life. Since the eyelash animal cannot be reproduced in the laboratory to this day, a decision was made between Dr. Kreutz and the Cologne researchers developed a lively collaboration. The fresh sediment was always sent to Cologne by post. There, single cells of Pseudoblepharisma tenue were isolated from the samples and subjected to microscopic and genetic analyzes.

The study’s first author, Dr. Sergio Muñoz-Gómez was able to reconstruct the individual genomes of the three symbiotic partners and demonstrated the massive physiological reduction in purple bacteria. “An interesting picture emerges from the different perspectives, from observations of nature to the gene repertoire of the symbiotic partners. The symbiosis has created a hybrid creature that has never existed before: a mobile and voracious ciliate animal, which at the same time uses light energy in the deeper, oxygen-poor layers of the water ”, say the researchers. “The algae seem to play a subordinate role. Instead, the innovation comes from the oxygen-avoiding purple sulfur bacteria. “

Youtube video:

Featured image credit: Sebastian Hess


For publication:
https://advances.sciencemag.org/content/7/24/eabg4102


Provided by University of Cologne

Up to One in Six People With Covid-19 Report Long Covid Symptoms (Medicine)

One in six (17%) middle-aged people who report being infected by SARS-CoV-2 also report long Covid symptoms, while this falls to one in 13 (7.8%) among younger adults who reported having Covid-19, according to a new study led by UCL and King’s College London researchers.

The preliminary findings, part of the UKRI-NIHR funded multi-institution Convalescence study and submitted to the preprint server medRxiv, also found that women were 50% more likely to report long Covid than men, and that the risk for long Covid symptoms increases with age, is linked to poorer pre-pandemic mental and physical health and is associated with a previous diagnosis of asthma. Non-white ethnic minority groups had lower odds of reporting long COVID (about 70% less likely).

Using a stricter definition of long Covid as impacting routine daily activities, the researchers found that it affected 1.2% of 20-year-olds who had Covid-19, but 4.8% of people in middle age.

The researchers analysed anonymised data from 1.2 million primary health records across the UK together with 10 population-based cohort studies with 45,096 participants. Using existing cohort studies, whose participants are surveyed regularly, allowed the research team to include cases not reported to the GP and to look at people’s health before the pandemic.

Professor Nishi Chaturvedi (MRC Unit for Lifelong Health and Ageing at UCL), who leads the ongoing Convalescence study, said: “Getting consistent findings from this combination of many different studies gives us greater confidence that our findings are robust, which is critical given that we know so little about long Covid.”

Dr Claire Steves of King’s College London, senior author of the paper, said: “Knowing which factors increase the risk of long Covid is an important first step in understanding how best to prevent and treat this condition.”

First author Dr Dylan Williams (MRC Unit for Lifelong Health & Ageing at UCL) said: “Amassing this body of evidence would usually take many months or years to assemble but we achieved this more quickly through massive, constant collaboration by researchers at many different institutions.

“Our findings hint at the mechanisms behind long Covid. Next we need to identify the predispositions that might explain, for example, why women or individuals with asthma appear to be at higher risk. Could a liability to suffer from autoimmunity or allergies play a role? Establishing concrete research avenues to go down will eventually lead to benefits for people with long Covid.”

First author Dr Ellen Thompson, of King’s College London, said: “It’s really important to identify risk factors in the population so we can prepare and devise prevention strategies, protecting people at increased risk of poor outcomes from COVID-19.”

The study forms part of the larger Covid-19 Longitudinal Health and Wellbeing National Core Study, which is investigating the health, social and economic impacts of the Covid-19 pandemic by combining rich pre-Covid data collected from participants of numerous national research studies with national anonymised electronic health records. 

The researchers investigated if the risks of developing long-term Covid symptoms differed by several pre-pandemic socioeconomic and health characteristics. Coordinated analyses of the longitudinal studies and health records data showed consistently that female sex and increasing age (up to 70 years) were associated with increased odds of long Covid.

Pre-existing adverse mental health was associated with a 50% increase in the odds of reporting long Covid, while asthma was the only specific prior medical condition consistently associated with greater risk of developing lasting Covid-19 symptoms (a 32% increase). Participants were identified as having pre-existing adverse mental health if they had been diagnosed with one of a number of conditions such as depression and bipolar disorder, or their responses to questionnaires indicated they had a mental health condition before the pandemic.

Analysis was conducted on 6,899 individuals self-reporting Covid-19 from 45,096 surveyed adult participants of ongoing longitudinal studies in the UK, and on 3,327 cases assigned a long Covid code in primary care electronic health records out of 1,199,812 adults diagnosed with acute Covid-19. Long Covid, identified as Post-Covid-19 syndrome in the study, is defined as symptoms persisting for longer than 12 weeks after the initial infection.

The research team included researchers at the Universities of Bristol, Edinburgh, Glasgow, Oxford, as well as the London School of Hygiene & Tropical Medicine, and the Bradford Royal Infirmary.

Dr Fiona Glen, programme director for the NICE Centre for Guidelines, said: “There is still much we do not know about the long-term effects of Covid-19. We continue to monitor and assess the latest evidence on the long-term effects allowing us to continuously update our guideline recommendations. We welcome this new research which will ensure we have a better understanding of how to manage the care and treatment of patients with prolonged symptoms of Covid-19.”

Links

Image

  • Credit: Edward Jenner on Pexels

Provided by UCL

WSU Tri‑Cities Student Engineering Team Creates Solar Water Purifier (Engineering)

A Washington State University Tri-Cities student mechanical engineering team created a working prototype of a solar water purifier that they hope will one-day be used in developing countries where access to clean water is scarce.

The project was led by recent engineering graduates Mitch Blocher, Daniel Lara, Alex Andres, Sergio Alvarado and Zachary Garcia under the advisement of their instructor, Steve Jordan, who also sponsored the project. The group created the project as part of their senior design capstone engineering course.

“The foundation to this project is based on a similar senior project from the past in which a group was tasked with developing a solar milk pasteurizer,” Andres said. “When our advisor came up with the idea of taking this solar milk pasteurizer and implementing it into a solar water purification system, his first thought was to make it portable and user-friendly enough to send out to third world countries without access to purified water.”

The system uses a solar reflector, positioning system, pumping system, electronics and a heat exchanger to regulate heat, pump water through the system and purify the water out of a standard bucket or other water container. The system, they said, had to be relatively simple, as the parts needed to be locally sourced and able to be fixed in developing countries.

“First, recognizing that the design of this system revolved around a well-thought-out control system, breaking down the complex processes into a simpler, high-level subsystem based on their tasks greatly helped,” Blocher said. “From there, each sub-system could be designed because we knew what function each system, sensor and part needed to perform, as well as how it interfaced with other components.”

Blocher said their final design had to meet specific portability and weight criteria, in an effort to ensure it was portable. He said when fully assembled, the system stands six-feet tall and nearly four-feet in width, but it can be broken down small enough to fit in a backpack, where it weighs 20 pounds.

Lara said one of the most challenging parts of the project was the COVID-19 pandemic and the limitations that it presented. He said trying to pull together their project in a remote environment, which still required physical assembly, proved difficult, but they made it work.

Andres said availability of materials and components amid the pandemic also proved challenging.

“That being said, WSU Tri-Cities gave us as much opportunity as permitted to supplies and resources” he said. “Our advisor was also very cooperative and dedicated to getting us all we needed to accomplish our design.”

Lara said it feels humbling to know that they were able to contribute a new design that is easy to manufacture and even easier to transport in an effort to provide a commodity, which is growing scarcer and scarcer each year.

“It feels gratifying to know that we were able to design a functioning prototype to show people that it is indeed possible to build a system such as this when there are few options available on the market,” he said.

“Engineering is all about innovation,” Andres said. “It has truly been a privilege to not only come up with a solution to a worldwide crisis, but to do so working side-by-side with other brilliant engineering students, advisors and faculty has been even more rewarding. It is truly a moment that I believe will stick with every one of us for the rest of our lives.”

The team hopes that future engineering teams will take the project and advance particular components so that they can one-day send it overseas for implementation in the developing world.

Featured image: Engineering students Mitch Blocher (right) and Zack Garcia set-up the the solar water purifier they designed and built as part of their senior design class this spring. © WSU


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Physicists Uncover Secrets of World’s Thinnest Superconductor (Physics)

First experimental evidence of spin excitations in an atomically thin material helps answer 30-year-old questions, could lead to better medical diagnostics and more.

Physicists from across three continents report the first experimental evidence to explain the unusual electronic behavior behind the world’s thinnest superconductor, a material with myriad applications because it conducts electricity extremely efficiently. In this case, the superconductor is only an atomic layer thick.

The work, led by an MIT professor and a physicist at Brookhaven National Laboratory, was possible thanks to new instrumentation available at only a few facilities in the world. The resulting data could help guide the development of better superconductors. These in turn could transform the fields of medical diagnostics, quantum computing, and energy transport, which all use superconductors.

The subject of the work belongs to an exciting class of superconductors that become superconducting at temperatures an order of magnitude higher than their conventional counterparts, making them easier to use in applications. Conventional superconductors only work at temperatures around 10 kelvins, or -442 degrees Fahrenheit.

These so-called high-temperature superconductors, however, are still not fully understood. “Their microscopic excitations and dynamics are essential to understanding superconductivity, yet after 30 years of research, many questions are still very much open,” says Riccardo Comin, the Class of 1947 Career Development Assistant Professor of Physics at MIT. The new work, which was reported recently in Nature Communications, helps answer those questions.

Comin’s colleagues on the work include Jonathan Pelliciari, a former MIT postdoc who is now an assistant physicist at Brookhaven National Laboratory and lead author of this study. Other authors are Seher Karakuzu and Thomas A. Maier of Oak Ridge National Laboratory; Qi Song, Tianlun Yu, Xiaoyang Chen, Rui Peng, Qisi Wang, Jun Zhao, and Donglai Feng of Fudan University; Riccardo Arpaia, Matteo Rossi, and Giacomo Ghiringhelli of Politecnico di Milano (Arpaia is also affiliated with Chalmers University of Technology); Abhishek Nag, Jiemin Li, Mirian García-Fernández, Andrew C. Walters, and Ke-Jin Zhou of Diamond Light Source in the United Kingdom; and Steven Johnston of the University of Tennessee at Knoxville.

World’s thinnest superconductor

In 2015 scientists discovered a new kind of high-temperature superconductor: a sheet of iron selenide only one atomic layer thick capable of superconducting at 65 K. In contrast, bulk samples of the same material superconduct at a much lower temperature (8 K). The discovery “sparked an investigative flurry to decode the secrets of the world’s thinnest superconductor,” says Comin, who is also affiliated with MIT’s Materials Research Laboratory.

In a regular metal, electrons behave much like individual people dancing in a room. In a superconducting metal, the electrons move in pairs, like couples at a dance. “And all these pairs are moving in unison, as if they were part of a quantum choreography, ultimately leading to a kind of electronic superfluid,” says Comin.

But what is the interaction, or “glue,” that holds these pairs of electrons together? Scientists have known for a long time that in conventional superconductors, that glue is derived from the motion of atoms within a material. “If you look at a solid sitting on a table, it doesn’t appear to be doing anything,” Comin says. However, “a lot is happening at the nanoscale. Inside that material, electrons are flying by in all possible directions and the atoms are rattling; they’re vibrating.” In conventional superconductors, the electrons use the energy stored in that atomic motion to pair up.

The glue behind electrons’ pairing in high-temperature superconductors is different. Scientists have hypothesized that this glue is related to a property of electrons called spin (another, more familiar property of electrons is their charge). The spin can be thought of as an elementary magnet, says Pelliciari. The idea is that in a high-temperature superconductor, electrons can pick up some of the energy from these spins, known as spin excitations. And that energy is the glue they use to pair up.

Until now, most physicists thought that it would be impossible to detect or measure spin excitations in a material only an atomic layer thick. That is the remarkable achievement of the work reported in Nature Communications. Not only did the physicists detect spin excitations, but, among other things, they also showed that the spin dynamics in the ultra-thin sample were dramatically different from those in the bulk sample. Specifically, the energy of the fluctuating spins in the ultra-thin sample was much higher — by a factor of four or five — than the energy of the spins in the bulk sample.

“This is the first experimental evidence of the presence of spin excitations in an atomically thin material,” says Pelliciari.

State-of-the art equipment

Historically, neutron scattering has been used to study magnetism. Since spin is the fundamental property of magnetism, neutron scattering would appear to be a good experimental probe. “The problem is that neutron scattering doesn’t work on a material that is only one atomic layer thick,” says Pelliciari.

Enter resonant inelastic X-ray scattering (RIXS), a new experimental technique that Pelliciari helped pioneer.

He and Comin discussed the potential for using RIXS to study the spin dynamics of the new ultra-thin superconductor, but Comin was initially skeptical. “I thought, ‘Yes, it would be great if we could do this, but experimentally it’s going to be next-to-impossible,’” Comin remembers. “I thought it was a true moonshot.” As a result, “when Johnny collected the very first results, it was mind-blowing for me. I’d kept my expectations low, so when I saw the data, I jumped on my chair.”

Only a few facilities in the world have advanced RIXS instruments. One, located at Diamond Light Source (UK) and led by Zhou, is where the team conducted their experiment. Another one, which was still being built at the time of the experiment, is at Brookhaven National Laboratory. Pelliciari is now part of the team running the RIXS facility, known as the Beamline SIX, at the National Synchrotron Light Source II located at Brookhaven Lab.

“The impact of this work is two-fold,” says Thorsten Schmitt, head of the Spectroscopy of Novel Materials Group at the Paul Scherrer Institut in Switzerland, who was not involved in the work. “On the experimental side, it is an impressive demonstration of the sensitivity of RIXS to the spin excitations in a superconducting material only an atomic layer thick. Furthermore, the [resulting data] are expected to contribute to the understanding of the enhancement of the superconducting transition temperature in such thin superconductors.” In other words, the work could lead to even better superconductors.

Valentina Bisogni, lead scientist for the Beamline SIX who was not involved in this study, says, “the understanding of unconventional superconductivity is one of the main challenges faced by scientists today. The recent discovery of high-temperature superconductivity in a monolayer-thin film of iron selenide renewed the interest into the iron selenide system, as it provides a new route to investigate the mechanisms enabling high-temperature superconductivity.

“In this context, the work of Pelliciari et al. presents an enlightening, comparative study of bulk iron selenide and monolayer-thin iron seleniderevealing a dramatic reconfiguration of the spin excitations,” Bisogni says.

This research was supported by the U.S. Air Force Office of Scientific Research, the MIT-POLIMI Program (Progetto Rocca), the Swiss National Science Foundation, the U.S. Department of Energy (DOE), the U.S. Office of Naval Research, the Fondazione CARIPLO and Regione Lombardia, the Swedish Research Council, the Alfred P. Sloan Foundation, and the National Natural Science Foundation of China.

This research used resources of the National Synchrotron Light Source II, a DOE Office of Science user facility located at DOE’s Brookhaven Lab.

Featured image: Former MIT postdoc Jonathan Pelliciari, now an assistant physicist at Brookhaven National Laboratory, holds onto part of the resonant inelastic X-ray scattering (RIXS) instrument at BNL. Pelliciari is lead author of a study that used RIXS to uncover secrets of the world’s thinnest superconductor. Credits: Photo courtesy of Brookhaven National Laboratory.


Reference: Pelliciari, J., Karakuzu, S., Song, Q. et al. Evolution of spin excitations from bulk to monolayer FeSe. Nat Commun 12, 3122 (2021). https://doi.org/10.1038/s41467-021-23317-3


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