Daily Archives: 13 Feb 2021

Medicine

Antibodies to Common Cold Coronaviruses Do Not Protect Against SARS-CoV-2 (Medicine)

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Antibodies that react to both ordinary coronaviruses and SARS-CoV-2 are common in the population but don’t neutralize the COVID-19-causing virus

Past exposure to seasonal coronaviruses (CoVs), which cause the common cold, does not result in the production of antibodies that protect against the novel coronavirus SARS-CoV-2, according to a study led by Scott Hensley, PhD, an associate professor of Microbiology at the Perelman School of Medicine at the University of Pennsylvania.

Prior studies have suggested that recent exposure to seasonal CoVs protects against SARS-CoV-2, the virus that causes COVID-19. However, research from Hensley’s team, published in Cell, suggests that if there is such protection, it does not come from antibodies.

“We found that many people possessed antibodies that could bind to SARS-CoV-2 before the pandemic, but these antibodies could not prevent infections,” Hensley said. “Although antibodies from prior coronavirus infections cannot prevent SARS-CoV-2 infections, it is possible that pre-existing memory B cells and T cells could potentially provide some level of protection or at least reduce the disease severity of COVID-19. Studies need to be completed to test that hypothesis.”

The researchers examined blood samples banked before the pandemic from hundreds of people. They found that more than 20 percent of these pre-pandemic samples carried “cross reactive” anti-CoV antibodies that could bind not only to ordinary cold-causing CoVs but also to key sites on SARS-CoV-2. However, these cross-reactive antibodies could not neutralize the infectivity of SARS-CoV-2, and were not associated with better outcomes in people who later went on to get COVID-19.

The scientists also found from blood testing in different groups that both children and adults on average tend to have similar levels of cross-reactive anti-CoV antibodies — implying that these antibodies are not the factor that confers protection against severe COVID-19 among most children.

The COVID-19 pandemic, after more than a year of global spread, has resulted in more than 100 million reported infections, of which more than two million have been fatal. Although some risk factors, such as age, are clear enough, scientists still don’t fully understand why some people become deathly sick with COVID-19 while others escape with mild illness or even no symptoms.

Antibodies have been considered one possible explanation. Ordinary seasonal coronaviruses, of the type that cause colds, have long circulated in the human population. An obvious hypothesis is that some of the antibodies elicited by these common infections cross-react with the novel coronavirus SARS-CoV-2, providing some measure of protection, at least against severe COVID-19 illness.

In one set of analyses that Hensley and colleagues conducted, they examined blood samples collected from 263 children at the Children’s Hospital of Philadelphia, and from 168 adults at the Penn Medicine Biobank. The samples had been taken in 2017, more than two years before the SARS-CoV-2 pandemic started.

The researchers found that most of the 431 samples contained antibodies to ordinary, seasonal CoVs. Some samples, about 20 percent, contained anti-CoV antibodies that were “cross reactive” with SARS-CoV-2, binding tightly to sites on its outer spike protein and/or its nucleocapsid protein — the two coronavirus proteins that are most accessible to the immune system of infected hosts.

Hensley and colleagues separately analyzed blood samples banked before the pandemic from 251 people who later went on to test positive for SARS-CoV-2, and a control group of 251 people — matched for age and other relevant characteristics — who did not test positive for the novel coronavirus. Again, they found that greater than 20 percent of the pre-pandemic samples contained anti-CoV antibodies that could cross-react with the SARS-CoV-2 spike and/or nucleocapsid proteins. Yet similar proportions of the infected and uninfected groups had these cross-reactive antibodies, implying that they provided no protection against SARS-CoV-2 infection. Moreover, in the group that later went on to be infected with SARS-CoV-2, levels of cross-reactive anti-CoV antibodies in their pre-pandemic blood samples did not correlate with measures of COVID-19 severity such as the need for hospitalization or ICU care.

In a third set of tests, the researchers analyzed blood samples from 27 hospitalized COVID-19 patients, and found that levels of these cross-reactive anti-CoV antibodies were strongly boosted during the course of COVID-19 illness.

The researchers recommend that larger studies be done to definitively resolve the question of whether pre-existing anti-CoV antibodies can protect against SARS-CoV-2 viruses. They also suggest that further studies examine other types of immune response, such as the T cell response, to see if these provide a measure of cross-reactive protection following seasonal CoV infection.

In the meantime, though, they say their results suggest that the shared sites where some antibodies bind both to seasonal coronaviruses and to SARS-CoV-2 are generally not vulnerable sites where SARS-CoV-2 can be neutralized.

The co-first authors of the study were Elizabeth Anderson, Eileen Goodwin, and Anurag Verma. The study was a collaboration including not only Hensley’s laboratory but also the Penn Medicine laboratories of Paul Bates PhD, a professor of Microbiology, Michael Betts, PhD, a professor of Microbiology, Sara Cherry PhD, a professor of Pathology and Laboratory Medicine, Alex Huang, MD, an instructor of Hematology-Oncology, Nuala Meyer, MD, MS, an associate professor of Pulmonary and Critical Care Medicine, Daniel Rader MD, the Seymour Gray Professor of Molecular Medicine and chair of the Department of Genetics, and E. John Wherry, PhD, chair of Systems Pharmacology and Translational Therapeutics and director of the Penn Institute of Immunology.

Funding was provided by the National Institutes of Health and philanthropic support from Philadelphia 76ers star player Joel Embiid and managing partners Josh Harris and David Blitzer, and Philadelphia Eagles owner Jeffrey Lurie.

Reference: Elizabeth M. Anderson, Eileen C. Goodwin, Anurag Verma, Paul Bates et al., “Seasonal human coronavirus antibodies are boosted upon SARS-CoV-2 infection but not associated with protection”, Cell, 2021. DOI: https://doi.org/10.1016/j.cell.2021.02.010

Provided by Penn Medicine

Neuroscience

The Scarred Villain: Study Explores Neurocognitive Basis of Bias Against People Who Look Different (Neuroscience)

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Brain Responses and Attitudes Reflect the “Anomalous is Bad” Stereotype, Penn Medicine Research Shows

The “scarred villain” is one of the oldest tropes in film and literature, from Scar in “The Lion King” to Star Wars’ Darth Vader and the Joker in “The Dark Knight.” The trope is likely rooted in a long-evolved human bias against facial anomalies — atypical features such as growths, swelling, facial paralysis, and scars. A new brain-and-behavior study from researchers in the Perelman School of Medicine at the University of Pennsylvania illuminates this bias on multiple levels.

The researchers, whose findings were published this week in the Annals of the New York Academy of Sciences, used surveys, social simulations, and functional MRI (fMRI) studies to study hundreds of participants’ responses and attitudes towards attractive, average, and anomalous faces. The findings clarify how the “anomalous-is-bad” stereotype manifests, and implicate a brain region called the amygdala as one of the likely mediators of this stereotype.

“Understanding the psychology of the ‘anomalous-is-bad’ stereotype can help, for example, in the design of interventions to educate the public about the social burdens shouldered by people who look different,” said lead author Clifford Workman, PhD, a postdoctoral researcher in the Penn Center for Neuroaesthetics. The center is led by Anjan Chatterjee, MD, a professor of Neurology at Penn Medicine, who was senior author of the study.

Bias against people with facial disfigurements has been demonstrated in various prior studies. Researchers broadly assume that this bias reflects ancient adaptive traits which evolved to promote healthy mate selection, for example, and to steer us clear of people who have potentially communicable diseases. Regardless the cause, for many people, their facial anomalies render them unjust targets of discrimination.

In their study, Workman and colleagues investigated how this bias manifests at different levels, from expressed attitudes towards faces, to actual behavior during simulated social interactions, and even down to brain responses when viewing faces.

In one part of the study, the researchers showed a set of faces that were either average-looking, attractive, or anomalous to 403 participants from an online panel, and asked them to rate the depicted people on various measures. The researchers found that, compared to more attractive faces, participants considered anomalous faces less trustworthy, less content, and more anxious, on average. The anomalous faces also made the participants feel less happy. Participants also acknowledged harboring “explicit bias” reflected in negative expectations about people with anomalous faces as a group.

In the other part of the study, Workman and colleagues examined moral attitudes and dispositions, the behavior during simulated social interaction, and fMRI-measured brain responses, for 27 participants who viewed similar sets of faces.

Here again there was some evidence of the anomalous-is-bad habit of thinking, though it was not clear that this translated into mistreatment of people with anomalous faces. For example, in a simulated donation game measuring pro-sociality — the willingness to be positive and helpful towards another — the participants were not significantly less pro-social towards anomalous-looking people. However, participants in the highest tier of socioeconomic status, compared to the others, were significantly less pro-social towards anomalous-looking people.

On fMRI scans, brain regions called the amygdala and the fusiform gyri showed significant neural responses specifically to anomalous faces. Activity in a portion of the left amygdala, which correlated with less pro-sociality towards anomalous faces, also seemed related to participants’ beliefs about justice in the world and their degree of empathic concern.

“We hypothesize that the left amygdala integrates face perception with moral emotions and social values to guide behavior, such that weaker emotional empathy, and a stronger belief that the world is just, both facilitate dehumanizing people with facial anomalies,” Chatterjee said.

Analyzing such responses is inherently challenging, because they involve a mix of subjective perceptions, such as the “visual salience,” or relative importance, of a face, and the “emotional arousal” elicited by seeing the face. To inform future research, as part of the study, the team used the fMRI data to clarify which brain regions are associated with these distinct aspects of the experience of seeing faces.

Additional co-authors included Stacey Humphries, Franziska Hartung, Geoffrey Aguirre, and Joseph Kable.

The research was supported by the Penn Center for Human Appearance and the National Institute of Dental & Craniofacial Research of the National Institutes of Health (F32DE029407).

Featured image: Anjan Chatterjee and Clifford Workman © Penn Medicine

Reference: Workman, C.I., Humphries, S., Hartung, F., Aguirre, G.K., Kable, J.W. and Chatterjee, A. (2021), Morality is in the eye of the beholder: the neurocognitive basis of the “anomalous‐is‐bad” stereotype. Ann. N.Y. Acad. Sci.. https://doi.org/10.1111/nyas.14575

Provided by Penn Medicine

Medicine

Unlocking the Mystery Behind Skeletal Aging (Medicine)

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By identifying the underlying factors leading to bone loss and osteoporosis, UCLA dentist-scientists hope to pave the way to new treatments

Researchers from the UCLA School of Dentistry have identified the role a critical enzyme plays in skeletal aging and bone loss, putting them one step closer to understanding the complex biological mechanisms that lead to osteoporosis, the bone disease that afflicts some 200 million people worldwide.

The findings from their study in mice, published online today in the journal Cell Stem Cell, could hold an important key to developing more effective treatments for osteoporosis and improving the lives of an aging population, they say.

Cells in the bone marrow known as mesenchymal stem cells serve as the building blocks of the body’s skeletal tissues, but whether these stem cells ultimately develop into bone or fat tissues is controlled in part by what are known as epigenetic factors — molecules that regulate genes, silencing some and activating others.

The UCLA researchers, led by distinguished professor Dr. Cun-Yu Wang, chair of oral biology at the dentistry school, demonstrated that when the epigenetic factor KDM4B is absent from mesenchymal stem cells, these cells are far more likely to differentiate into fat cells than bone cells, resulting in an unhealthy imbalance that exacerbates skeletal aging and leads to brittle bones and fractures over time.

“We know that bone loss comes with age, but the mechanisms behind extreme cases such as osteoporosis have, up until recently, been very vague,” said Dr. Wang, the study’s corresponding author and the Dr. No-Hee Park Professor of Dentistry at UCLA. “In this study, we built on more than seven years of research managed by my postdoctoral scholar and lead author Dr. Peng Deng in the hope that we can eventually prevent skeletal aging and osteoporosis.”

While scientists have long understood the cellular pathway involved in bone tissue formation, the role of epigenetic factors has been murkier. Previous research by Wang, Deng and others had identified that the enzyme KDM4B plays an important epigenetic role in bone formation, but they were unsure of how its absence might affect the processes of bone formation and bone loss.

To test this, the research team created a mouse model in which KDM4B was absent or removed in several different scenarios. They found that the removal of the enzyme pushed mesenchymal stem cells to create more fat instead of bone tissue, leading to bone loss over time, which mimics skeletal aging.

In one important scenario, the scientists examined stem cell senescence, or deterioration and exhaustion — the natural process by which mesenchymal stem cells stop rejuvenating or creating more of themselves over time. The team unexpectedly found that senescence, which leads to natural skeletal aging, was characterized by a loss of KDM4B.

A loss of the epigenic factor KDM4B promotes the accumulation fat cells in the bone marrow (pictured here) of aging mice, researchers found. © Peng Deng/UCLA School of Dentistry

In addition to age, other environmental factors are thought to reduce bone quality and exacerbate bone loss, including a high-fat diet. The team demonstrated that a loss of KDM4B significantly promoted bone loss and the accumulation of marrow fat in mice placed on a high-fat diet.

Finally, the team showed that parathyroid hormone, an anabolic drug approved by the U.S. Food and Drug Administration for the treatment of aging-related bone loss, helps to maintain the pool of mesenchymal stem cells in aging mice in a KDM4B-dependent manner.

The results not only confirm the critical role KDM4B plays in mesenchymal stem cell fate decision, skeletal aging and osteoporosis, but they show that the loss of KDM4B exacerbates bone loss under a number of conditions and, surprisingly, that KDM4B controls the ability of mesenchymal stem cells to self-renew. This study is the first in vivo research to demonstrate that the loss of an epigenetic factor promotes adult stem cell deterioration and exhaustion in skeletal aging.

The findings, the researchers say, hold promise for the eventual development of strategies to reverse bone-fat imbalance, as well as for new prevention and treatment methods that address skeletal aging and osteoporosis by rejuvenating adult stem cells.

“The work of Dr. Wang, his lab members and collaborators provides new molecular insight into the changes associated with skeletal aging,” said Dr. Paul Krebsbach, dean of the UCLA School of Dentistry. “These findings are an important step towards what may lead to more effective treatment for the millions of people who suffer from bone loss and osteoporosis.”

The work was supported by grants from the National Institute of Dental and Craniofacial Research (part of the National Institutes of Health), the UCLA Clinical and Translational Science Institute and the Hsien Family Foundation charitable funds.

Dr. Wang is also a member of the UCLA Jonsson Comprehensive Cancer Center, the UCLA Samueli School of Engineering and Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at UCLA.

Additional authors include Dr. Peng Deng, Quan Yuan, Yingduan Cheng, Jiong Li, Zhenqing Liu, Yan Liu, Mari Ekimyan Salvo and Ye Li, all of the Laboratory of Molecular Signaling at the UCLA School of Dentistry; Trent Su of the UCLA Department of Biological Chemistry; Jing Wang, Weiguang Wang, Guoping Fan and Karen Lyons of the David Geffen School of Medicine at UCLA; and Dr. Bo Yu of the division of constitutive and regenerative science at the UCLA School of Dentistry.

Featured image: Epigenetic factors like the enzyme KDM4B play a major role in the aging-related bone loss that leads to brittle bones and fractures, researchers say. © UCLA Health

Reference: Peng Deng, Quan Yuan, Yingduan Cheng et al., “Loss of KDM4B exacerbates bone-fat imbalance and mesenchymal stromal cell exhaustion in skeletal aging”, Cell Stem Cell, 2021. DOI: https://doi.org/10.1016/j.stem.2021.01.010

Provided by UCLA Health

Astronomy

Indian Astronomers Detect Huge Optical Flare In One Of The Oldest Astronomic Objects (Astronomy)

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Indian Astronomers have reported one of the strongest flares from a feeding supermassive black hole or blazar called BL Lacertae. Analysis of the flare from this blazar, one of the oldest astronomical objects, can help trace the mass of the black hole and the source of this emission. Such analysis can provide a lead to probe into mysteries and trace events at different stages of evolution of the Universe.

Blazars or feeding supermassive black holes in the heart of distant galaxies receive a lot of attention from the astronomical community because of their complicated emission mechanism. They emitjets ofcharged particles traveling nearly at the speed of light and are one of the most luminous and energetic objects in the Universe.

BL Lacertae blazar is 10 million light-years away and is among the 50 most prominent blazars that can be observed with the help of a relatively small telescope. It was among the 3 to 4 blazars that was predicted to be experiencing flares by the Whole Earth Blazar Telescope (WEBT), an international consortium of astronomers.  

A team of astronomers led by Dr. Alok Chandra Gupta from Aryabhatta Research Institute of Observational Sciences (ARIES), an autonomous institute of the Department of Science & Technology, Government of India who had been following the blazar since October 2020 as part of an international observational campaign detected the exceptionally high flare on January 16, 2021, with the help of Sampurnanand Telescope (ST) and 1.3m Devasthal Fast Optical Telescopes located in Nainital.

The data collected from the flare observed will help calculation of the black hole mass, size of emission region, and mechanism of the emission from one of the oldest astronomical objects known, hence opening a door to the origin and evolution of the Universe.

The luminosity of BL Lac observed on 27 October 2020 (left panel of figure) was around 2.95 * 1012 Lʘ and after 80 days, i.e., 16 January 2021 (right panel of figure) was ~ 7.25 * 1012 Lʘ,i.e., ~ 250% increase in the luminosity which is equivalent to more than 4 trillion Lʘ  (here  Lʘ  = luminosity of the Sun). © Ministry of Science and Technology, India.

The link to Astronomical Telegram #14343 with the announcement of blazar BL Lacertae’s luminosity record: http://www.astronomerstelegram.org/?read=14343.

For more details, Dr. Alok Chandra Gupta (Scientist-F) (+91-7895966668, alok@aries.res.in ) can be contacted.

Provided by Press Information Bureau

Nature

Human Borders Threaten Wildlife As Climate Changes (Nature)

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Human-made borders like the USA-Mexico border wall could make it difficult for almost 700 mammal species to adapt to climate change.

Our scientists have identified 32,000km of borders fortified with fences and walls that could potentially stop large numbers of animals from reaching more suitable environments.

Ecologically damaging

Borders between the USA and Mexico, China and Russia and India and Myanmar could be the most ecologically damaging.

The USA-Mexico border wall alone could obstruct the movement of 122 mammal species displaced by climate change including the Mexican wolf, jaguar and jaguarundi.

Mammals that could be obstructed by human-made borders across the world include leopards, tigers, the critically endangered Saiga antelope, and cheetah.

Suitable habitats

According to our researchers, a third of mammals and birds will need to find suitable habitats in other countries by 2070 due to climate change.

This movement is most likely to happen between the Amazon rainforest and tropical Andes, around the Himalayas, and in parts of Central and Eastern Africa.

Our researchers are calling for more cross-border conservation initiatives and habitat corridors to reduce the problem.

COP 26

As well as political borders, our researchers also looked at likely impacts of ongoing climate change on species within countries.

They found that biodiversity loss is likely to be most severe in countries that are less responsible for the emissions that are driving climate change.

They are urging world leaders to reduce the risk to biodiversity by committing to ambitious reductions in greenhouse gases when they meet at the UN Climate Change Conference (COP 26) in Glasgow this November.

Featured image: Border barriers, such as this along the USA-Mexico border, present an obstacle for many species whose ranges are shifting under climate change. © Durham University

Find out more

Reference: Mark A. Titley, Stuart H. M. Butchart, Victoria R. Jones, Mark J. Whittingham, Stephen G. Willis, “Global inequities and political borders challenge nature conservation under climate change”, Proceedings of the National Academy of Sciences Feb 2021, 118 (7) e2011204118; DOI: 10.1073/pnas.2011204118

Provided by Durham University

Astronomy, Quantum Mechanics

What Are The Effects Of “Extra Matter” and Scalar Field On A Wormhole? (Cosmology)

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Summary:

○ Ewha Womans University researcher Sung-Won Kim described the effects of extra matter and scalar field on the stability and geometry of wormhole in his 1999 paper.

○ There are two effects of extra matter fields on the Lorentzian traversable wormhole. The “primary effect” says that the extra matter can afford to be a part of source or whole source of the wormhole when the wormhole is being formed. Thus the matter does not affect the stability of wormhole and the wormhole is still safe.

○ The “auxiliary effect” is that the extra matter plays the role of the additional matter to the stably-existed wormhole by the other exotic matter. This additional matter will change the geometry of wormhole enough to prevent from forming the wormhole by backreaction.

One of the most important issues in making a practically usable Lorentzian wormhole is just the traversability. If it is traversable, there is a good usability, such as short-cut space travels, the time machine, and inspection of the interior of a black hole.

To make a Lorentzian wormhole traversable, one has conventionally used an exotic matter which violates the well-known energy conditions. For instance, a wormhole in an inflating cosmological model still requires exotic matter to be traversable and to maintain its shape. It is known that the vacuum energy of the inflating wormhole does not change the sign of the exoticity function. A traversable wormhole in the Friedmann-Robertson-Walker(FRW) cosmological model, however, does not necessarily require exotic matter at very early times. The result means that there was an exotic period in the early Universe.

The problem about maintaining a wormhole by other fields relating with the exotic property has also been of interest to us. There are two ways to generalize or modify the Lorentzian traversable wormhole space-time. (From now on the “wormhole” will be simply used in the sense “Lorentzian traversable wormhole”, unless there is a confusion.) One way is generalization of the wormhole in an alternative theory, for example, Brans-Dicke theory, Einstein-Cartan theory, etc. The other is the generalization by adding the extra matter.

In the case of the latter generalization, the added matter will play two kinds of roles in affecting the wormhole spacetime. The first role of such matter (e.g.,scalar fields, charge, spin, etc.) is the “primary effect”, which means that the added matter is a partial or total source of the wormhole. The matter gets involved in the constructing stage of the wormhole.

The wormhole is then safe under the addition of matter, which is a part of the sources for wormhole constructing. This means that if this added extra matter field has exotic properties, it shares exoticity with other matter, or, if the latter is not exotic, the added matter will monopolize the exotic property. In this case the wormhole cannot exist without this extra matter. Its example is the case of the wormhole solution with a scalar fields.

The second role is the “auxiliary effect”. In this effect, the added matter is not a source, but causes an extra effect on an existing wormhole. Therefore, it is not involved on the wormhole construction stage but affects it afterwards. Since this matter makes extra geometry, the wormhole is not safe when this effect dominates the exotic constructing matter. This is back reaction to the wormhole from an additional field.

What Kim found is that a self-consistent solution for a worm-hole with a classical, minimally-coupled, massless scalar field. He also found the back reaction of the scalar field on the wormhole spacetime, to see the stabilities of the wormhole. The result is that the scalar field effect can break the wormhole structure when the field and the variation of the field is large.

He obtained similar consequences in charged wormhole case, in which there is the interaction term in geometry, even though no interaction term in matter. It is natural that the addition of the nonexotic matter will break wormhole if the “auxiliary effect” is large.

In this paper, he neglected the interaction between the extra field and the original matter. If the interaction exists and it is large, it can change the whole geometry drastically. But, if it is very small, it does not change the main structure of the wormhole.

Reference: Sung-Won Kim, “Backreaction to wormhole by classical scalar field: Will classical scalar field destroy wormhole?”, Astronomical Journal, pp. 1-9, 1999. https://arxiv.org/abs/gr-qc/9911099

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Nature

Generating Electricity: The Price of Carbon Certificates Must Increase (Nature)

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Economist at FAU has calculated which strategy is most effective for reducing CO2 emissions

Energy market researchers at FAU, the Vienna University of Economics and Business in Austria and the University of Applied Sciences of the Grisons, Switzerland, have been investigating which methods are most effective for reducing the carbon dioxide emissions created when generating electricity. They have come to the conclusion that increasing the price of carbon credits is currently considerably more effective than subsidising renewable energy from wind and solar power. The results of the study have now been published in the Journal of Environmental Economics and Management, one of the leading journals for environmental economics.

Germany aims to cut its greenhouse gas emissions by 55% by 2030, and by 2050, it hopes to be largely greenhouse gas neutral. To achieve these ambitious goals, the Federal Government is mainly using subsidies for regenerative energy sources, above all for wind and solar power. Germany uses the European Union Emissions Trading System (EU ETS) for pricing emissions, where the price for carbon certificates was significantly less than 10 euros per tonne of CO2 for several years. Even though Germany has increased the price of CO2 for heating oil and fuels to 25 euros per tonne at the beginning of the year, this does not apply to electricity generation.

Britain is following a different approach from Germany

Image: FAU

‘Less than 10 euros per tonne of carbon dioxide is simply not enough to significantly reduce emissions,’ says economist Prof. Dr. Mario Liebensteiner, Professorship of Energy Markets and Energy Systems Analysis at the School of Business, Economics and Society at FAU. In collaboration with Prof. Dr. Klaus Gugler from the Vienna University of Economics and Business and Dr. Adhurim Haxhimusa from the University of Applied Sciences of the Grisons, Prof. Liebensteiner has investigated which control instruments are most effective for cutting greenhouse gas emissions during electricity production by using Germany and Great Britain as an example. ‘Both countries are pursuing different strategies,’ says Liebensteiner. ‘Whilst Germany is offering significant subsidies for renewable energy sources, Britain has introduced a CO2 tax for the electricity market. This means that the effective price of CO2 has been increased to over 35 euros per tonne.’

Which of these measures is most effective? For their comparison, the researchers evaluated data from both countries from the last few years: daily CO2 emissions from the electricity sector, CO2 prices, electricity fed into the grid from renewable energy sources and other variables such as the demand for electricity, the price of coal and gas, and seasonal effects. The results were clear. While Germany only achieved a moderate reduction in emissions in the electricity sector, Great Britain has cut its emissions by 55 percent after introducing the tax on electricity in 2013.

Gas is replacing coal

Image: FAU

The researchers say that this difference is caused by two central aspects. On the one hand, subsidies for renewable energies are not achieving the desired effect. When prices for CO2 are low, wind and solar power initially replace only the relatively ‘clean’ gas power stations, while ‘dirty’ coal, and mainly very dirty brown coal, can retain their share of the market to a significant extent. Electricity produced using coal is only pushed out of the market when a very high amount of renewable energy is fed into the grid. On the other hand, as is the case in Great Britain, higher taxation of carbon dioxide emissions leads to coal increasingly being replaced by gas as an energy source. ‘Gas emits about half as much CO2 as coal when producing electricity,’ explains Mario Liebensteiner. ‘A moderately high price for CO2 makes coal unprofitable and we see a drop in emissions.’

A sample calculation: What can you achieve with a billion euros?

Image: FAU

The model is very well suited for calculating the costs of approaches to climate policy. The economists calculated the extent to which governments can cut emissions with one billion euros. ‘In Germany, you can save around 20 million tonnes of CO2 due to the low carbon certificate price of eight euros per tonne,’ explains Liebensteiner. ‘If the money is invested in feed-in tariffs for wind or solar power, CO2 emissions can only be reduced by five million or one million tonnes respectively.’ The effect would be far greater in Britain. At a moderately high price of 36 euros per tonne, it would be possible to cut CO2 emissions by 33 million tonnes with one billion euros and around 18.5 million tonnes using current feed-in tariffs for wind power.

Market-based incentives require technologies to bridge the gap

According to the researchers, the decisive advantage of the British strategy is that a CO2 price produces market-based incentives and does not dictate which technology is used. This allows relatively clean gas to push coal, which is considerably more problematic, off the market to a significant extent. In contrast, considerable subsidies for renewable energies combined with a low price for CO2 leads to gas being pushed off the market first, while coal power stations remain in operation. ‘Our results demonstrate that even a moderately high price for CO2 can help to reduce large amounts of CO2 quickly and cheaply if gas power stations are available to bridge the gap,’ says Liebensteiner. ‘We ought to bear in mind, however, that gas is also a fossil fuel and should be replaced by alternative sources in the long term, of course.’

Further information

Klaus Gugler, Adhurim Haxhimusa, Mario Liebensteiner, “Effectiveness of climate policies: Carbon pricing vs. subsidizing renewables”, Journal of Environmental Economics and Management, Volume 106, 2021, 102405,
ISSN 0095-0696,
https://doi.org/10.1016/j.jeem.2020.102405 https://www.sciencedirect.com/science/article/pii/S0095069620301285

Provided by FAU

Planetary Science

SwRI Scientist Proposes A New Timeline For Mars Terrains (Planetary Science)

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A Southwest Research Institute scientist has updated Mars chronology models to find that terrains shaped by ancient water activity on the planet’s surface may be hundreds of millions of years older than previously thought. This new chronology for Mars, based on the latest dynamical models for the formation and evolution of the solar system, is particularly significant as the days count down until NASA’s Mars 2020 Perseverance rover lands on the Red Planet on February 18, 2021.

Unlike on Earth, where terrains are commonly dated using natural radioactivity of rocks, scientists have largely constrained the chronology of Mars by counting impact craters on its surface. 

“The idea behind crater dating is not rocket science; the more craters, the older the surface,” says SwRI’s Dr. Simone Marchi, who published a paper about these findings in The Astronomical Journal. “But the devil is in the details. Craters form when asteroids and comets strike the surface. The rate of these cosmic crashes over the eons is uncertain, hampering our ability to convert crater numbers to terrain ages. I took a fresh look at this and built on recent developments in the way we understand the earliest evolution of the solar system.”

Scientists have used radiometric ages of precious lunar rocks brought back by the Apollo missions to calibrate a lunar crater chronology. This lunar chronology is then extrapolated to Mars, and this is where things get tangled with the earliest evolution of the solar system. Our understanding of the time evolution of lunar and Martian impact rates has greatly improved in recent years. The present model improves upon how the critical Moon-to-Mars extrapolations are done.

“For this paper, I looked particularly at the Jezero Crater because that is the landing site for the Mars 2020 Perseverance rover,” Marchi said. “These surfaces could have formed over 3 billion years ago, as much as 500 million years older than previously thought. NASA plans to have Perseverance gather and package surface samples that can be collected by a future mission for return to Earth for radiometric dating. That could provide vital ground-truth data to better calibrate our chronology models.”

The Jezero Crater on Mars, the landing site for NASA’s Mars 2020 mission, shows evidence of water-carved channels and transported sediments. Colors highlight the distribution of clays and carbonates. An SwRI scientist updated Mars chronology models and predicted that these surfaces could have formed more than 3 billion years ago, hundreds of millions of years earlier than previously thought. Courtesy of NASA/JPL-Caltech/MSSS/JHU-APL 

Jezero Crater has a diameter of about 30 miles located within the 750-mile-wide Isidis Basin, created by an earlier impact. The latter cut a wide portion of the Borealis Basin’s rim, perhaps the largest and oldest impact basin on Mars. This coincidence of nested craters is of particular interest as samples from these terrains may return information about the timing of these consecutive impacts.

Furthermore, Jezero Crater hosts clay-rich terrains and a fluvial delta, indications that the crater once hosted a lake. This makes the Jezero Crater an ideal place to fulfill the Mars 2020 mission’s science goal of studying a potentially habitable environment that may still preserve signs of past life. As such, understanding the timeline of these surfaces is particularly important.

The new model also provides a revised age for Isidis Basin, now estimated to be 4-4.2 billion years old, providing an upper limit for the formation of Jezero Crater and water activity at this location on Mars.

The new paper “A new Martian crater chronology: Implications for Jezero crater” appears in The Astronomical Journal.

Featured image: An SwRI scientist used a new model to estimate Mars’ bombardment history. This new model indicated that some of the most prominent terrains associated with ancient water activity may be hundreds of millions of years older than previously thought, important data as NASA’s Perseverance rover prepares to land in one of these sites. The image shows a computer simulation indicating a hypothetical evolution for an early Mars heavily battered by cosmic impacts. Jezero Crater is expected to have formed near the tail end of this vigorous, early bombardment. © Courtesy of Southwest Research Institute 

Provided by Southwest Research Institute

Biology

How Bacteria Sleep through Antibiotic Attacks? (Biology)

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Bacteria can survive antibiotic treatment even without antibiotic resistance by slowing down their metabolism and going into a type of deep sleep. A research team reveals the changes bacteria undergo to reach this “persister” state. Annelies Zinkernagel, an infectiologist at UZH, is main author of the publication in the scientific journal PNAS.

Resistant bacteria evade the effects of antibiotics by becoming less susceptible, for example by breaking the drugs down. But some bacteria have another survival strategy: they withstand treatment by going into a sleep-like state that enables them to tolerate antibiotics. Once therapy is complete, the bacteria wake up and re-establish the infection. This “persister” state can result in recurrent and difficult-to-treat infections.

A research team from several swiss universities has now gained new insights into this bacterial strategy that could lead to new and effective treatments. Last author of the publication in the journal PNAS* is Annelies Zinkernagel, Professor of infectious diseases at the University of Zurich and University Hospital Zurich.

The research team worked with the bacterium Staphylococcus aureus, which is found on the skin of many people and often causes invasive and difficult-to-treat infections. The researchers took bacteria from an infected patient and cultivated them in Petri dishes. Certain bacterial colonies turned out to be smaller than others. “This tells us that the sample contains persistent bacteria,” says Annelies Zinkernagel. “Unlike other bacteria, persistent bacteria must first ‘awaken’, leading to delayed growth in the nutrient medium.”

Detection and analysis of persistent bacteria in a patient sample are particularly interesting because most of the previous studies on persistent bacteria used bacteria that were cultivated over a prolonged period of time in the laboratory and not taken directly from a patient.

Annelies Zinkernagel was able to show that bacteria can slow down their metabolism under certain situations. (Image: Nicolas Zonvi)

To determine the conditions under which bacteria become persistent, the researchers carried out various stress tests. Stress factors include the presence of human immune cells, antibiotics or an acidic environment, as occurs with abscesses. The researchers discovered that the more extreme the stress conditions, the higher the percentage of persistent bacteria.

Slowed metabolism

Using bacteria recently isolated from patients, the researchers also analysed how persistence mechanisms work. To do this, they looked at the entire set of bacterial proteins, known as the proteome. Their analysis showed that comprehensive molecular reprogramming had taken place and slowed metabolism down in persisters.

However, it did not come to a complete standstill, but the bacteria rather entered a kind of deep sleep. In this way, the bacteria increased their chances of survival in a hostile environment. The researchers also observed that as soon as the environment becomes more hospitable, the persistent bacteria reverse these changes and again become infectious.

“The idea that bacteria do not halt their metabolism but slow it down and change it is not entirely new. However, it is still controversial,” says Zinkernagel. “Our study confirms this idea with great precision.” The current study looked primarily at persistent bacteria. “Previous experiments were based on mixed populations, and the results may thus have been biased by the other bacteria, which are usually in the majority.”

New treatments on the horizon

A better understanding of these mechanisms will contribute to developing new treatments against persistent bacteria. The researchers also showed that vitamin A derivatives that target the cell membrane exhibit promising potential for combating less metabolically active bacteria. Alternatively, says Zinkernagel, “if we succeed in reactivating the growth of these bacteria, they would probably no longer be able to evade the antibiotics.”

The fight against persistent bacteria is also important in the fight against resistance, because recurrent infections must be treated with antibiotics over an extended period. This constant exposure increases the risk of developing antibiotic resistance. The research work was supported by the Swiss National Science Foundation and the clinical research priority programme CRPP – BacVivo – Precision medicine for bacterial infections as well as by the Uniscentia Foundation.

Featured image: Stained staphylococci, imaged through a scanning electron microscope. The bacteria colonise the skin and are usually harmless, but they can also cause serious infections. (Image: istock/Dr Microbe)

Reference: M. Huemer, S.M. Shambat et. al: Molecular reprogramming and phenotype switching in Staphylococcus aureus lead to high antibiotic persistence and affect therapy success. PNAS (2021)

Provided by University of Zurich