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Comment by Dr. Krishna Kumari Challa on August 25, 2023 at 11:00am

Study shows that astrocytes in the cortex modulate the dominant behavior of male mice

The social behavior of animals has been the key focus of extensive neuroscience and biomedical studies, as it is often aligned with behaviors observed in humans. Better understanding these behaviors and the neural processes underpinning them could ultimately also have implications for the treatment of different psychiatric disorders that affect how humans socialize with others.

Researchers recently conducted a study specifically exploring male dominance behavior among male mice. These behaviours naturally lead to the formation of social hierarchies among groups of mice, with some males accessing more food and water than others. 

A recent paper, published in Nature Neuroscience, highlights the role of astrocytes in the outer layer of the brain (i.e., the cortex), in modulating the dominance behavior of male mice. In addition, it sheds some light on the specific neural processes through which astrocytes modulate these behaviours.

The results gathered by the researchers hint at the involvement of communication between dmPFC astrocytes and neurons in the dominant behaviour of male mice. 

This work implies that astrocytes also play critical role in computing and processing high-order brain functions. It also suggests that such intercellular interplay may decipher the etiology of many psychiatric disorders.

 Kyungchul Noh et al, Cortical astrocytes modulate dominance behavior in male mice by regulating synaptic excitatory and inhibitory balance, Nature Neuroscience (2023). DOI: 10.1038/s41593-023-01406-4

Nguyen T. Phi et al, Control of social hierarchy beyond neurons, Nature Neuroscience (2023). DOI: 10.1038/s41593-023-01392-7

Comment by Dr. Krishna Kumari Challa on August 25, 2023 at 9:59am

Scientists discover a previously unknown way cells break down proteins

Short-lived proteins control gene expression in cells to carry out a number of vital tasks, from helping the brain form connections to helping the body mount an immune defense. These proteins are made in the nucleus and are quickly destroyed once they've done their job.

Despite their importance, the process by which these proteins get broken down and removed from cells once they are no longer needed has eluded scientists for decades—until now.

It is well established that cells can break down proteins by tagging them with a small molecule called ubiquitin. The tag tells the proteasome that the proteins are no longer needed, and it destroys them. 

However, sometimes the proteasome breaks down proteins without the help of ubiquitin tags, leading researchers to suspect that there was another, ubiquitin-independent mechanism of protein degradation.

Researchers now  identified a protein called midnolin that plays a key role in degrading many short-lived nuclear proteins. The study shows that midnolin does so by directly grabbing the proteins and pulling them into the cellular waste-disposal system, called the proteasome, where they are destroyed.

Because the proteins broken down by this process modulate genes with important functions related to the brain, the immune system, and development, scientists may eventually be able to target the process as a way of controlling protein levels to alter these functions and correct any dysfunction.

Xin Gu et al, The midnolin-proteasome pathway catches proteins for ubiquitination-independent degradation, Science (2023). DOI: 10.1126/science.adh5021.

Comment by Dr. Krishna Kumari Challa on August 24, 2023 at 1:08pm

Spectroscopy, Explained

Comment by Dr. Krishna Kumari Challa on August 24, 2023 at 1:00pm

Evidence of carbonic acid found in interstellar space for the first time

An international team of astrophysicists, astronomers and chemists has found evidence of carbonic acid (HOCOOH) in interstellar space, marking the first time it has been detected in such a setting. In their paper published in The Astrophysical Journal, the group describes their discovery, where it was found, and what it might mean for research into the origins of life.

Prior research has led to the discovery of acetic and formic acid in interstellar space; both are carboxylic acids, as is carbonic acid. All three are believed to be building blocks of life. Finding them in such distant places gives credence to theories that suggest that they were delivered to Earth via comets or meteorites. In this new effort, the researchers were studying the molecular cloud G+0.693-0.027 near the center of the Milky Way when they found evidence of HOCOOH.

Carboxylic acids have a carbon atom and are doubly bonded to an oxygen atom. They are also singly bonded to a hydroxyl group. Carbonic acid is formed here on Earth when CO2 mixes and dissolves in water. It produces the acidic effect in soft drinks. It is also responsible for the increasing acidity of the oceans due to increased amounts of atmospheric CO2. The research team notes that carbonic acid has been observed on several of Jupiter's moons, on comets and on Mercury and Mars—but this is the first time it has been detected in interstellar space. They also note that the presence of carbonic acid in an interstellar molecular cloud suggests a high degree of complexity in the interstellar medium, which means it may also harbor amino-acid-related compounds.

They also found an upper limit to the abundance of HOCOOH with respect to diatomic hydrogen in the molecular cloud, which they suggest hints at the possibility that carbonic acid may be abundant in interstellar space. They note that one of the reasons carbonic acid has not been spotted in interstellar space until now, despite its apparent abundance, is that it is undetectable by radio astronomical observations.

 Miguel Sanz-Novo et al, Discovery of the Elusive Carbonic Acid (HOCOOH) in Space, The Astrophysical Journal (2023). DOI: 10.3847/1538-4357/ace523

Comment by Dr. Krishna Kumari Challa on August 24, 2023 at 12:55pm

How a cup of water can unlock the secrets of our universe

Researchers have made a discovery that could change our understanding of the universe. In their study published in Science Advances, they reveal, for the first time, that there is a range in which fundamental constants can vary, allowing for the viscosity needed for life processes to occur within and between living cells. This is an important piece of the puzzle in determining where these constants come from and how they impact life as we know it.

In 2020, the same scientists found that the viscosity  of liquids is determined by fundamental physical constants, setting a limit on how runny a liquid can be. Now this result is taken into the realm of life sciences.

Fundamental physical constants shape the fabric of the universe we live in. Physical constants are quantities with a value that is generally believed to be both universal in nature and to remain unchanged over time—for example the mass of the electron. They govern nuclear reactions and can lead to the formation of molecular structures essential to life, but their origin is unknown. This research might bring scientists one step closer to determining where these constants come from.

Understanding how water flows in a cup turns out to be closely related to the grand challenge to figure out fundamental constants. Life processes in and between living cells require motion and it is viscosity that sets the properties of this motion. If fundamental constants change, viscosity would change too impacting life as we know it. For example, if water was as viscous as tar life would not exist in its current form or not exist at all. This applies beyond water, so all life forms using the liquid state to function would be affected.

Any change in fundamental constants including an increase or decrease would be equally bad news for flow and for liquid-based life. We expect the window to be quite narrow: for example, viscosity of our blood would become too thick or too thin for body functioning with only a few percent change of some fundamental constants such as the Planck constant or electron charge.

Surprisingly, the fundamental constants were thought to be tuned billions of years ago to produce heavy nuclei in stars and back then life as we know it today didn't exist. There was no need for these constants to be fine-tuned at that point to also enable cellular life billions of years later, and yet these constants turn out to be bio-friendly to flow in and between living cells. An accompanying conjecture is that multiple tunings may have been involved and this then suggests a similarity to biological evolution where traits were acquired independently. Through evolutionary mechanisms, fundamental constants may be the result of nature arriving at sustainable physical structures. It remains to be seen how the principles of evolution can be helpful to understand the origin of fundamental constants.

Kostya Trachenko, Constraints on fundamental physical constants from bio-friendly viscosity and diffusion, Science Advances (2023). DOI: 10.1126/sciadv.adh9024. www.science.org/doi/10.1126/sciadv.adh9024

Comment by Dr. Krishna Kumari Challa on August 24, 2023 at 12:49pm

First complete sequence of a human Y chromosome

For decades, the Y chromosome—one of the two human sex chromosomes—has been notoriously challenging for the genomics community to sequence due to the complexity of its structure.

Now, this elusive area of the genome has been fully sequenced, a feat that finally completes the set of end-to-end human chromosomes and adds 30 million new bases to the human genome reference, mostly from challenging-to-sequence satellite DNA. These bases reveal 41 additional protein-coding genes, and provide crucial insight for those studying important questions related to reproduction, evolution, and population change.

The complete, annotated Y chromosome reference is available for use on the UCSC Genome Browser and can be accessed via Github.

When scientists and clinicians study an individual's genome, they compare the individuals' DNA to that of a standard reference to determine where there is variation. Until now, the Y chromosome portion of the human genome has contained large gaps which made it difficult to understand variation and associated disease.

The structure of the Y chromosome has been challenging to decode because some of the DNA is organized in palindromes—long sequences that are the same forward and backward—spanning up to more than a million base pairs. Moreover, a very large part of the Y chromosome that was missing from the previous version of the Y reference is satellite DNA—large, highly repetitive regions of non-protein-coding DNA. On the Y chromosome, two satellites are interlinked with each other, further complicating the sequencing process.

The researchers were able to achieve a gapless read of the Y chromosome due to advances in long-read sequencing technology and new, innovative computational assembly methods that could deal with the repetitive sequences and transform the raw data from sequencing into a usable resource.

These new method assemblies allowed the team to tackle some of the particularly challenging aspects of the Y chromosome, such as pinpointing precisely where an inversion occurs in a palindromic sequence—a technique that can be used to find other inversions. The methods established in the paper will allow scientists to complete more end-to-end reads of human Y chromosomes to get a better understanding of how this genetic material affects the diverse human population.

The complete Y chromosome reference will allow scientists to better study a myriad of features about this part of the human genome in a way that has never before been possible.

The complete sequence of a human Y chromosome, Nature (2023). DOI: 10.1038/s41586-023-06457-y. www.nature.com/articles/s41586-023-06425-6. On bioRxiv: DOI: 10.1101/2022.12.01.518724

Comment by Dr. Krishna Kumari Challa on August 23, 2023 at 11:48am

Caffeine in Your Blood May Affect Body Fat And Diabetes Risk, Study Finds

The levels of caffeine in your blood could affect the amount of body fat you carry, a factor that in turn could determine your risk of developing type 2 diabetes and cardiovascular diseases. Those are the findings of a recent study that used genetic markers to establish a more definitive link between caffeine levels, BMI, and type 2 diabetes risk. The researchers suggest that calorie-free caffeinated drinks could be explored as a potential means of helping reduce body fat levels. Genetically predicted higher plasma caffeine concentrations were associated with lower BMI and whole body fat mass. Furthermore, genetically predicted higher plasma caffeine concentrations were associated with a lower risk of type 2 diabetes. Approximately half of the effect of caffeine on type 2 diabetes liability was estimated to be mediated through BMI reduction. In general, those with variations affecting the genes – namely CYP1A2 and a gene that regulates it, called AHR – tend to break caffeine down more slowly, allowing it to remain in the blood longer. Yet they also tend to drink less caffeine in general.

https://bmjmedicine.bmj.com/content/2/1/e000335

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Comment by Dr. Krishna Kumari Challa on August 23, 2023 at 10:48am

Teens Who Smoke Show Reduced Brain Matter, Scientists Discover

Neurological imaging reveals people more inclined to begin smoking as teenagers tend to have reduced gray matter in two important brain regions, indicating they may play a significant role in inhibition and addiction.

An international team of researchers compared MRI brain scans from over 800 people, collected from the UK, Germany, France and Ireland across different time points. These volunteers also answered questionnaires on personality traits. The researchers then compared those who began smoking by age 14 with non-smokers and repeated this again with the same patients at ages 19 and 23. The images revealed those who took up smoking from the age of 14 had comparitively less gray matter in the left ventromedial prefrontal cortex; a part of the brain involved in emotional regulation, decision-making, and self-control. Scans taken five years later revealed the opposite part of this same brain region (on the right) was also reduced in the smoker group compared to non-smokers. This side of the ventromedial prefrontal cortex has also been linked to pleasure. The ventromedial prefrontal cortex is a key region for dopamine, the brain's pleasure chemical. As well as a role in rewarding experiences, dopamine has long been believed to affect self-control.

https://www.nature.com/articles/s41467-023-40079-2

Comment by Dr. Krishna Kumari Challa on August 22, 2023 at 11:49am

Silica particles found in food and makeup could be chemically reactive, study finds

New research has revealed that the mineral silica, a common food additive and popular cosmetics ingredient, is not a chemically inert substance, as has long been supposed.

As described in a new study, researchers placed commercially available silica particles in a water solution with biomolecules containing compounds called thiols. These thiol-containing biomolecules are widespread in nature and in the human body, for instance, in the form of glutathione, a key antioxidant found in most cells. When exposed to silica, the thiol biomolecules underwent redox chemical reactions. These reactions, in which electrons are lost, could degrade or alter the molecules' function, potentially posing health risks. For instance, low levels of glutathione can lead to increased oxidative stress in the body that can damage all manner of cellular components, from membranes to DNA.

The findings highlight the need for further research into the reactivity of silica, especially given its extensive usage in everyday products.

Silica—another name for compounds of silicon and oxygen—is a colorless, odorless, tasteless material. While silica occurs naturally in foods including leafy greens, manufacturers often add tiny, sand-like particles of silica as an anticaking agent to soups and coffee creamers, for instance. 

For cosmetics, including skin care products, silica serves as a bulking or absorbing agent, or as an abrasive in scrubs. In health care, silica particles have also found significant use in the delivery of drugs and for medical imaging purposes. For those applications, silica particles are manufactured to have tiny holes, or pores, into which pharmaceuticals and other substances can be slotted.

For the study, the  researchers purchased commercially available, pure silica particles, sold as a dry powder.

Yangjie Li et al, Silica particles convert thiol-containing molecules to disulfides, Proceedings of the National Academy of Sciences (2023). DOI: 10.1073/pnas.2304735120

Comment by Dr. Krishna Kumari Challa on August 22, 2023 at 9:55am

The eye tracking data confirmed that items with more competitors were looked at the longest, which led to the memory advantage for those items later on. These findings show that the bilingual cognitive system is highly interactive and can impact other cognitive components such as recognition memory.

Other studies also show enhanced memory processing in bilinguals relative to monolinguals in categorization tasks that require suppressing distracting information. This could certainly indicate that bilinguals are more efficient at multi-tasking and more able to focus on the task at hand, especially when the task requires ignoring irrelevant information (think trying to work in a noisy café).

The picture that emerges is one where bilingualism is a cognitive tool that enhances basic cognitive functions, such as memory and categorization. Bilingual hangman is a tougher game, but one that, ultimately, pays off.

Now  what about multilinguals like me?

Matias Fernandez-Duque et al, Speakers of different languages remember visual scenes differently, Science Advances (2023). DOI: 10.1126/sciadv.adh0064

Part 2

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