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Scientists claim controversial results of comets observations are consistent

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Astrophysicists from Far Eastern Federal University (FEFU) joined the international research team for explaining the difference in the results of observation of the comet 41P/ Tuttle – Giacobini – Kresak. Researchers believe that data obtained by three independent teams are complementary and its complex analysis helps to unravel the mystery of dust chemical composition of comet 41P and other conundrums of the Universe. A related article appears in Astronomy & Astrophysics.

The activity of comets is more complex than it appeared to be, one of the research outcomes says. The chemical composition of a cometary coma (gas-dusty environment of the nucleus) is able to change very rapidly, literally during the day. That is because of the Sun affects the nucleus of a comet approaching.

Researchers all over the Globe try to get data on the chemical composition of comets via analyses of the light refracted by its dust particles. However, the information about the color spectrum of comets differs every time, depending on different observation epochs and different phase angles (angle Earth-comet-Sun).

The present research paper postulates the controversial data sets obtained due to different sets of photometric filters and areas (apertures) of research are steady.

“At least three groups of researchers who observed comet 41P in 2017 came up with different results. The comet color ranged from red to blue. We have explained in detail why this happened”, Anton Kochergin says”, one of the authors of the study, a young scientist at FEFU. “Usually, the final color is normalized by taking into account the different bandwidths of the photometric filters applied. However, in many studies, the color of celestial bodies is interpreted independently of a particular set of photometric filters. We show that this is not valid for all cases. The reason the comet color differs is exactly sets of various photometric filters. In addition, the choice of the size of the calculation area, i.e. aperture, is of great importance. This is a certain radius around the cometary coma in the pictures from observatories, which scientists define as an area of research. Having decided on the aperture, they analyze only the signal inside this field”.

The choice of the aperture determines which processes and results are included in the analysis. For example, a gas from a diatomic carbon molecule (C2): there are parent molecules (called CHON particles in the literature), which become a source of C2 upon photodissociation. This dissociation occurs at a certain distance from the comet’s nucleus, which in turn depends on the comet’s distance from the Sun. With the right aperture chosen, one can exclude most of the signals that C2 molecules give focusing on analyses of the dust component of the coma.

Dr. Kochergin emphasized that the opposite data about the color of the comet, collected by different groups using different sets of photometric filters, only benefits the researchers. It is impossible to give a thorough description of the color (the color is directly related to the chemical composition of the dust of a cometary coma), and the chemical composition after just one observation. It is necessary to observe and determine the characteristics in dynamics. The more measurements made, the more accurate the conclusions are.

“In practice, this allows us to probe into the microphysical properties of cometary dust, and the processes run in a cometary coma. With such information, we will shed light on the evolutionary processes of the Solar system. Many scientific groups around the world are working inside this fundamental area”, explains Anton Kochergin.

Scientists were able to model the results of color measurements of comet 41P, receives almost simultaneously via different photometric filters in different locations. Although the blue color was gained in one case and the red in the other, the researchers found that both results were consistent with the actual behavior of cometary dust particles in coma 41P. One can copy these results via simulating light scattering by dust particles of the pyroxene mineral. Pyroxene is a silicate material that is part of the lunar soil and was also delivered from the asteroid Itokawa and discovered in the comet 81P / Wild 2. Pyroxenes are a part of cometary matter and are well studied in laboratories.

Researchers to further cooperate in observing celestial bodies from different Earth locations. The routine helps to catch up with the object under investigation in case of adverse weather conditions at the location of one of the observatories. This also brings additional data in the case of different sets of filters applied by different teams. In the observation schedule of the international collaborators, all comets and asteroids their gear is capable of tracing.

The present results became possible due to the collaboration of scientists from Astronomical Observatory, Taras Shevchenko National University of Kyiv, Humanitas College, Kyung Hee University (South Korea), Space Science Institute (USA), Astronomical Institute of the Slovak Academy of Sciences, Main Astronomical Observatory of National Academy of Sciences, School of Natural Sciences, Far Eastern Federal University, Ussuriysk Observatory of the Institute of Applied Astronomy of the Russian Academy of Sciences.

Previously, FEFU astrophysicists teamed up with Russian and foreign colleagues to observe the ATLAS comet, which disintegrated when approaching the Sun. They brought up a conclusion that carbon found in the nucleus of the comet would help to determine the age of comets in the Solar system.

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Source: https://bioengineer.org/scientists-claim-controversial-results-of-comets-observations-are-consistent/

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Highly specific synaptic plasticity in addiction

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Philadelphia, January 26, 2021 – Addiction, or substance use disorder (SUD), is a complex neurological condition that includes drug-seeking behavior among other cognitive, emotional and behavioral features. Synaptic plasticity, or changes in the way neurons communicate with one another, drives these addictive behaviors. These lasting brain changes are at the crux of why addiction is so hard to treat.

A new study in Biological Psychiatry, published by Elsevier, now shows that players in the extracellular environment – not just at neuronal interfaces – contribute to addiction plasticity. Neurons in a brain area called the nucleus accumbens are known to undergo addiction-related plasticity. Specifically, changes at synapses of medium spiny neurons (MSN), which sense the neurotransmitter dopamine, have been associated with drug-seeking and extinction behaviors.

Previous research had shown that plasticity at MSNs expressing the D1-type of dopamine receptor is linked to drug-seeking, whereas extinction of drug-seeking involves plasticity at MSNs containing the D2-type dopamine receptor. Now, research led by Peter Kalivas, PhD, and Vivian Chioma, PhD, shows that distinct enzymes working at D1- and D2-type MSNs underlie drug-seeking and extinction behaviors.

The researchers trained rats to self-administer heroin by pushing a lever for 10 days, followed by a 10-day withdrawal period. They then carefully examined the rats’ brains under a microscope to detect enzymatic activity around the MSN synapses.

The study focused on the activity of extracellular enzymes called metalloproteinases (MMP). MMPs break down proteins that constitute the extracellular matrix around nerve cells. This matrix of proteins supports synaptic connections, but it also constrains the remodeling of synaptic connections in response to experience. Therefore, MMP activity directly impacts cells’ ability to manifest neuroplastic changes.

To assess activity of the MMPs, the researchers used a technique called in vivo zymography, in which the rats’ brains were injected with a fluorescent dye encapsulated in a protective gelatin coat at various points during the drug-training regimen. Once broken open by MMP enzymes, the dye becomes visible, allowing the investigators to observe cells’ morphology as well as the enzymes’ activity around specific cell types and sub-cellular locations.

“We found that drug cues increased MMP activity on one cell type in the nucleus accumbens,” said Dr. Kalivas, referring to D1-type MSNs, “and they decreased activity on another cell type,” the D2-type MSNs. “By showing this cellular specificity of MMP activation and inactivation by cues, we have identified novel molecules that may be potential targets for drug development in treating drug addiction,” he added.

“This paper highlights the exquisite selectivity of addiction-related neuroplasticity,” said John Krystal, MD, Editor of Biological Psychiatry. “In this study, cues associated with heroin delivery activated MMPs near dopamine D1 receptor-containing MSNs in the nucleus accumbens, promoting plasticity in key cells implicated in addiction. Rather than reducing this addiction-related effect on plasticity, extinction training instead increased MMP activity close to neighboring dopamine D2 receptor-containing MSNs – cells implicated in protection against addiction.”

Importantly, the researchers also saw MMP activity associated with cells adjacent to the MSNs called astrocytes, a type of glial cell. The astrocytes, the extracellular matrix, and the two neurons forming a synapse are all part of what is termed the tetrapartite, or four-part, synaptic complex.

“Our work investigating cell-type specific synaptic neuroadaptations in the nucleus accumbens provides evidence of novel advances in our understanding of tetrapartite synaptic activity during heroin seeking,” said Dr. Chioma. “This research demonstrates how integration of components of the tetrapartite synapse regulate specific addiction phenotypes.”

Dr. Krystal added, “This finding suggests that recovery from addiction is not simply a reversal of addiction-related changes in the brain, but rather it also involves the laying down of new anti-addiction changes that protect against substance use.”

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Notes for editors

The article is “Heroin Seeking and Extinction from Seeking Activate Matrix Metalloproteinases at Synapses on Distinct Subpopulations of Accumbens Cells,” by Vivian Chioma, Anna Kruyer, Ana-Clara Bobadilla, Ariana Angelis, Zachary Ellison, Ritchy Hodebourg, Michael Scofield, Peter Kalivas (https://doi.org/10.1016/j.biopsych.2020.12.004). It appears as an Article in Press in Biological Psychiatry, published by Elsevier.

Copies of this paper are available to credentialed journalists upon request; please contact Rhiannon Bugno at [email protected]”>[email protected] or +1 254 522 9700. Journalists wishing to interview the authors may contact Peter Kalivas at kaliv[email protected]”>[email protected] or +11 843-991-2627.

The authors’ affiliations and disclosures of financial and conflicts of interests are available in the article.

John H. Krystal, MD, is Chairman of the Department of Psychiatry at the Yale University School of Medicine, Chief of Psychiatry at Yale-New Haven Hospital, and a research psychiatrist at the VA Connecticut Healthcare System. His disclosures of financial and conflicts of interests are available here.

About Biological Psychiatry

Biological Psychiatry is the official journal of the Society of Biological Psychiatry, whose purpose is to promote excellence in scientific research and education in fields that investigate the nature, causes, mechanisms and treatments of disorders of thought, emotion, or behavior. In accord with this mission, this peer-reviewed, rapid-publication, international journal publishes both basic and clinical contributions from all disciplines and research areas relevant to the pathophysiology and treatment of major psychiatric disorders.

The journal publishes novel results of original research which represent an important new lead or significant impact on the field, particularly those addressing genetic and environmental risk factors, neural circuitry and neurochemistry, and important new therapeutic approaches. Reviews and commentaries that focus on topics of current research and interest are also encouraged.

Biological Psychiatry is one of the most selective and highly cited journals in the field of psychiatric neuroscience. It is ranked 7th out of 155 Psychiatry titles and 12th out of 271 Neurosciences titles in the Journal Citations Reports® published by Clarivate Analytics. The 2019 Impact Factor score for Biological Psychiatry is 12.095. http://www.sobp.org/journal

About Elsevier

As a global leader in information and analytics, Elsevier helps researchers and healthcare professionals advance science and improve health outcomes for the benefit of society. We do this by facilitating insights and critical decision-making for customers across the global research and health ecosystems.

In everything we publish, we uphold the highest standards of quality and integrity. We bring that same rigor to our information analytics solutions for researchers, health professionals, institutions and funders.

Elsevier employs 8,100 people worldwide. We have supported the work of our research and health partners for more than 140 years. Growing from our roots in publishing, we offer knowledge and valuable analytics that help our users make breakthroughs and drive societal progress. Digital solutions such as ScienceDirect, Scopus, SciVal, ClinicalKey and Sherpath support strategic research management, R&D performance, clinical decision support, and health education. Researchers and healthcare professionals rely on our 2,500+ digitized journals, including The Lancet and Cell, our 40,000 eBook titles; and our iconic reference works, such as Gray’s Anatomy. With the Elsevier Foundation and our external Inclusion & Diversity Advisory Board, we work in partnership with diverse stakeholders to advance inclusion and diversity in science, research and healthcare in developing countries and around the world.

Elsevier is part of RELX, a global provider of information-based analytics and decision tools for professional and business customers. http://www.elsevier.com

Media contact

Rhiannon Bugno, Editorial Office

Biological Psychiatry

+1 254 522 9700

[email protected]”>[email protected]

https://www.elsevier.com/about/press-releases/research-and-journals/highly-specific-synaptic-plasticity-in-addiction

Source: https://bioengineer.org/highly-specific-synaptic-plasticity-in-addiction/

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Breakthrough design at UBCO vastly improves mechanical heart valve

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New research coming out of UBC’s Okanagan campus may take the current ‘gold standard’ for heart valves to a new level of reliability.

A team of researchers at UBCO’s Heart Valve Performance Lab (HVPL) has developed a way to improve overall blood flow through the valves, so the design of mechanical heart valves will more closely match the real thing.

“Despite more than 40 years of research, we are still chasing the goal of creating mechanical heart valves that perform consistently and seamlessly inside the human body,” explains Dr. Hadi Mohammadi, an associate professor at the School of Engineering and lead researcher for the HVPL. “The way blood travels through the body is very unique to a person’s physiology, so a ‘one-size fits all’ valve has always been a real challenge.”

Mohammadi, along with doctoral student Arpin Bhullar, has developed an innovative mechanical bileaflet that enables the mechanical heart valve to function just like the real thing. A bileaflet valve–two semicircular leaflets that pivot on hinges–is a mechanical gateway that allows consistent blood-flow and ensures the flow is in one direction.

While developed decades ago and used regularly to improve a patient’s blood flow, artificial valves have never been perfect, says Mohammadi. With existing versions of bileaflets, there is a small risk of blood clots or even a backflow of blood.

The design of the bileaflet is crucial for maintaining blood flow in order to eliminate risk to the patient. Mohammadi believes he’s found a way to fix the problem, by adding a slight twist to the design.

“Our findings show our apex heart valve maintains consistent flow as a result of its breakthrough design–specifically the valve’s curvature which mitigates clotting.”

The initial design was confirmed by Dr. Guy Fradet, head of Kelowna General Hospital’s cardiothoracic surgery program. Mohammadi says it takes decades for innovations in mechanical heart valves before they are used on humans, but he is confident his novel leaflet-shaped valve is the way of the future.

“The work we’re doing has resulted in the design of a valve which may serve as the foundation for the next generation of bileaflet mechanical heart valves,” he says. “Our research, with computer simulation and in-vitro studies, helped evaluate the performance of the proposed valve and also compare it to the industry gold standard.”

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The findings, published in the Journal of Medical Engineering and Technology, suggest additional experimentation is still needed to confirm the valve’s effectiveness. The researchers are now in the process of developing 3D-printed, carbon and aluminum prototypes of the valve for further testing. The research is funded by the Natural Sciences and Engineering Research Council of Canada.

https://news.ok.ubc.ca/2021/01/26/breakthrough-design-at-ubco-vastly-improves-mechanical-heart-valve

Source: https://bioengineer.org/breakthrough-design-at-ubco-vastly-improves-mechanical-heart-valve/

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Nuclear war could trigger big El Niño and decrease seafood

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A nuclear war could trigger an unprecedented El Niño-like warming episode in the equatorial Pacific Ocean, slashing algal populations by 40 percent and likely lowering the fish catch, according to a Rutgers-led study.

The research, published in the journal Communications Earth & Environment, shows that turning to the oceans for food if land-based farming fails after a nuclear war is unlikely to be a successful strategy – at least in the equatorial Pacific.

“In our computer simulations, we see a 40 percent reduction in phytoplankton (algae) biomass in the equatorial Pacific, which would likely have downstream effects on larger marine organisms that people eat,” said lead author Joshua Coupe, a post-doctoral research associate in the Department of Environmental Sciences in the School of Environmental and Biological Sciences at Rutgers University-New Brunswick. “Previous research has shown that global cooling following a nuclear war could lead to crop failure on land, and our study shows we probably can’t rely on seafood to help feed people, at least in that area of the world.”

Scientists studied climate change in six nuclear war scenarios, focusing on the equatorial Pacific Ocean. The scenarios include a major conflict between the United States and Russia and five smaller wars between India and Pakistan. Such wars could ignite enormous fires that inject millions of tons of soot (black carbon) into the upper atmosphere, blocking sunlight and disrupting Earth’s climate.

With an Earth system model to simulate the six scenarios, the scientists showed that a large-scale nuclear war could trigger an unprecedented El Niño-like event lasting up to seven years. The El Niño-Southern Oscillation is the largest naturally occurring phenomenon that affects Pacific Ocean circulation, alternating between warm El Niño and cold La Niña events and profoundly influencing marine productivity and fisheries.

During a “nuclear Niño,” scientists found that precipitation over the Maritime Continent (the area between the Indian and Pacific oceans and surrounding seas) and equatorial Africa would be shut down, largely because of a cooler climate.

More importantly, a nuclear Niño would shut down upwelling of deeper, colder waters along the equator in the Pacific Ocean, reducing the upward movement of nutrients that phytoplankton – the base of the marine food web – need to survive. Moreover, the diminished sunlight after a nuclear war would drastically reduce photosynthesis, stressing and potentially killing many phytoplankton.

“Turning to the sea for food after a nuclear war that dramatically reduces crop production on land seems like it would be a good idea,” said co-author Alan Robock, a Distinguished Professor in the Department of Environmental Sciences at Rutgers-New Brunswick. “But that would not be a reliable source of the protein we need, and we must prevent nuclear conflict if we want to safeguard our food and Earth’s environment.”

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Scientists at the University of California, Santa Barbara; University of Colorado, Boulder; Australian Antarctic Partnership Program; University of Texas, Rio Grande Valley; and National Center for Atmospheric Research contributed to the study.

https://www.rutgers.edu/news/nuclear-war-could-trigger-big-el-nino-and-decrease-seafood

Source: https://bioengineer.org/nuclear-war-could-trigger-big-el-nino-and-decrease-seafood/

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Regulating the ribosomal RNA production line

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Cryo-electron microscopy study allows researchers to visualize structural changes in an E. coli enzyme synthesizing ribosomal RNA that shift it between turbo- and slow-modes depending on the bacteria’s growth rate

The enzyme that makes RNA from a DNA template is altered to slow the production of ribosomal RNA (rRNA), the most abundant type of RNA within cells, when resources are scarce and the bacteria Escherichia coli needs to slow its growth. Researchers used cryo-electron microscopy (cryo-EM) to capture the structures of the RNA polymerase while in complex with DNA and showed how its activity is changed in response to poor-growth conditions. A paper describing the research led by Penn State scientists appears January 22, 2020 in the journal Nature Communications.

“RNA polymerase is an enzyme that produces a variety of RNAs using information encoded in DNA,” said Katsuhiko Murakami, professor of biochemistry and molecular biology at Penn State and the leader of the research team. “This is one of the key steps in the central dogma of molecular biology: transferring genetic information from DNA to RNA, which in turn often codes for protein. It’s required for life and the process is basically shared from bacteria to humans. We are interested in understanding how the structure of RNA polymerase is changed for modulating its activity and function, but it’s been difficult to capture using traditional methods like X-ray crystallography, which requires crystallizing a sample to determine its structure.”

RNA polymerase functions by binding to specific DNA sequences called “promoters” found near the beginning of genes that are going to be made into RNA. To understand the structure and function of the polymerase during this interaction, researchers need to capture the polymerase while it is bound to the promoter DNA, but the interaction can be very unstable at some promoters. Crystallography can only capture RNA polymerase bound to a promoter if the complex is very stable, but for ribosomal RNA promoters this interaction tends to be unstable so that the polymerase can quickly escape to begin making the RNA. To see these interactions the researchers turned to cryo-EM, a method that allows them to visualize the structure of macromolecules in solution.

“When you talk about RNA, most people think about messenger RNA (mRNA), which is the template for making proteins,” said Murakami. “But the most abundant type of RNA in cells doesn’t actually code for protein. Ribosomal RNA is the major structural component of the ribosome, which is the cellular machinery that builds proteins using messenger RNAs as templates. Ribosomal RNA synthesis accounts for up to 70 percent of total RNA synthesis in E. coli cells.”

When a cell divides, which E. coli can do every twenty minutes in nutrient-rich growth conditions, it needs to provide the two resulting daughter cells with enough ribosomes to function, so it is continually making ribosomal RNAs.

“If you do some back-of-the-envelope calculations, an E. coli cell needs to make around 70,000 ribosomes every 20 minutes,” said Murakami. “This means RNA polymerase starts ribosomal RNA synthesis every 1.7 seconds from each ribosomal RNA promoter. So, the polymerase has to bind the ribosomal RNA promoter transiently in order to quickly move onto the ribosomal RNA synthesis step. This is not an ideal for a crystallographic approach, but in a cryo-EM study, we could capture this interaction and, in fact, see different several stages of the interaction in a single sample.”

The researchers were able to determine the three-dimensional structures of the RNA polymerase-promoter complex at two different stages. One when the DNA was still “closed,” before the two strands of the DNA molecule are separated allowing access to the template strand (they refer to this as a closed complex), and one when the DNA was “open” (called an open complex) and primed for RNA synthesis to begin.

“We found a large conformational change in part of the polymerase called the ? (sigma) factor when it binds to promoter DNA, which has never been observed before” said Murakami. “This change opens a gate that allows the DNA to enter a cleft in the polymerase and form the open complex quickly.”

When E. coli needs to slow its growth due to limited resources, two molecules–a global transcription regulator called DksA and a bacterial signaling molecule called ppGpp, bind directly with the polymerase to reduce production of ribosomal RNA. The research team investigated how the binding of these two factors alters the conformation of the polymerase and affects its activity in a promoter-specific manner.

“DksA and ppGpp binding to the polymerase alters its conformation, which prevents the opening of a gate and therefor the polymerase has to follow an alternative pathway to form the open complex,” said Murakami. “This is not an ideal pathway for the ribosomal RNA promoter and thus slow its activity. It’s exciting to see these conformational changes to the polymerase that have direct functional consequences. We couldn’t do this without the cryo-EM, so I’m very thankful to have access to this technology here at Penn State for optimizing experimental conditions for preparing cryo-EM specimens before sending them to the National Cryo-EM Facility at NCI/NIH for high-resolution data collections. We are going to be able to continue to analyze cellular components and complexes that were previously inaccessible.”

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In addition to Murakami, the research team includes Yeonoh Shin and M. Zuhaib Qayyum at Penn State and Danil Pupov, Daria Esyunina, and Andrey Kulbachinskiy at the Russian Academy of Sciences. The research was funded by the U.S. National Institutes of Health, the Russian Science Foundation, and the Russian Foundation for Basic Research. Additional support was provided by the National Cancer Institute’s National Cryo-EM Facility at the Frederick National Laboratory for Cancer Research.

Source: https://bioengineer.org/regulating-the-ribosomal-rna-production-line/

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