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Comment by Dr. Krishna Kumari Challa on March 28, 2024 at 7:28am

During the week required to complete the inflammatory process, the mouse memory-encoding neurons were found to have changed in various ways, including becoming more resistant to new or similar environmental stimuli.

This is noteworthy because we're constantly flooded by information, and the neurons that encode memories need to preserve the information they've already acquired and not be 'distracted' by new inputs.

Importantly, the researchers found that blocking the TLR9 inflammatory pathway in hippocampal neurons not only prevented mice from forming long-term memories but also caused profound genomic instability, i.e., a high frequency of DNA damage in these neurons.

Genomic instability is considered a hallmark of accelerated aging as well as cancer and psychiatric and neurodegenerative disorders such as Alzheimer's.

Drugs that inhibit the TLR9 pathway have been proposed for relieving the symptoms of long COVID. But caution needs to be shown because fully inhibiting the TLR9 pathway may pose significant health risks, say the researchers. 

 Jelena Radulovic, Formation of memory assemblies through the DNA-sensing TLR9 pathway, Nature (2024). DOI: 10.1038/s41586-024-07220-7. www.nature.com/articles/s41586-024-07220-7

Part 3

Comment by Dr. Krishna Kumari Challa on March 28, 2024 at 7:26am

Triggering inflammation to make memories

Further analysis showed that DNA fragments, along with other molecules resulting from the DNA damage, were released from the nucleus, after which the neurons' TLR9 inflammatory pathway was activated; this pathway in turn stimulated DNA repair complexes to form at an unusual location: the centrosomes.

These organelles are present in the cytoplasm of most animal cells and are essential for coordinating cell division. But in neurons—which don't divide—the stimulated centrosomes participated in cycles of DNA repair that appeared to organize individual neurons into memory assemblies.

Cell division and the immune response have been highly conserved in animal life over millions of years, enabling life to continue while providing protection from foreign pathogens.

It seems likely that over the course of evolution, hippocampal neurons have adopted this immune-based memory mechanism by combining the immune response's DNA-sensing TLR9 pathway with a DNA repair centrosome function to form memories without progressing to cell division.

Part 2

Comment by Dr. Krishna Kumari Challa on March 28, 2024 at 7:24am

Making long-term memories requires DNA damage, researchers discover

Just as you can't make an omelet without breaking eggs, scientists at Albert Einstein College of Medicine have found that you can't make long-term memories without DNA damage and brain inflammation. Their surprising findings were published in the journal Nature in a paper titled "Formation of memory assemblies through the DNA sensing TLR9 pathway."

Inflammation of brain neurons is usually considered to be a bad thing, since it can lead to neurological problems such as Alzheimer's and Parkinson's disease. But these new findings suggest that inflammation in certain neurons in the brain's hippocampal region is essential for making long-lasting memories.

The hippocampus has long been known as the brain's memory center.  Researchers found that a stimulus sets off a cycle of DNA damage and repair within certain hippocampal neurons that leads to stable memory assemblies—clusters of brain cells that represent our past experiences.

The researchers discovered this memory-forming mechanism by giving mice brief, mild shocks sufficient to form a memory of the shock event (episodic memory). They then analyzed neurons in the hippocampal region and found that genes participating in an important inflammatory signaling pathway had been activated.

Researchers observed strong activation of genes involved in the Toll-Like Receptor 9 (TLR9) pathway. This inflammatory pathway is best known for triggering immune responses by detecting small fragments of pathogen DNA. So at first scientists assumed the TLR9 pathway was activated because the mice had an infection. But looking more closely, they found, to their surprise, that TLR9 was activated only in clusters of hippocampal cells that showed DNA damage.

Brain activity routinely induces small breaks in DNA that are repaired within minutes. But in this population of hippocampal neurons, the DNA damage appeared to be more substantial and sustained.

Part 1

Comment by Dr. Krishna Kumari Challa on March 28, 2024 at 7:16am

Light is an oscillating or moving, electromagnetic wave that allows us to see objects. Sometimes, light oscillates in a preferred orientation, and we call it "polarized." Although polarized light surrounds us, to human eyes it is indistinguishable from "normal" light.

In the plasma around these black holes, particles whirling around magnetic field lines impart a polarization pattern perpendicular to the field. This allows astronomers to see in increasingly vivid detail what's happening in black hole regions and map their magnetic field lines.

By imaging polarized light from hot glowing gas near black holes, researchers are directly inferring the structure and strength of the magnetic fields that thread the flow of gas and matter that the black hole feeds on and ejects. Polarized light teaches us a lot more about the astrophysics, the properties of the gas, and mechanisms that take place as a black hole feeds.

Scientists are excited to have images of both supermassive black holes in polarized light because these images and the data that come with them provide new ways to compare and contrast black holes of different sizes and masses. As technology improves, the images are likely to reveal even more secrets of black holes and their similarities or differences.

 "M87* and Sgr A* are different in a few important ways: M87* is much bigger, and it's pulling in matter from its surroundings at a much faster rate. So, we might have expected that the magnetic fields also look very different. But in this case, they turned out to be quite similar, which may mean that this structure is common to all black holes.

A better understanding of the magnetic fields near black holes helps us answer several open questions—from how jets are formed and launched to what powers the bright flares we see in infrared and X-ray light. 

Issaoun, S. et al, First Sagittarius A* Event Horizon Telescope Results. VII. Polarization of the Ring, The Astrophysical Journal Letters (2024), DOI: 10.3847/2041-8213/ad2df0

Ricarte A. et al, "First Sagittarius A* Event Horizon Telescope Results. VIII. Physical Interpretation of the Polarized Ring," The Astrophysical Journal Letters (2024), DOI: 10.3847/2041-8213/ad2df1

Part 2

Comment by Dr. Krishna Kumari Challa on March 28, 2024 at 7:13am

Astronomers unveil strong magnetic fields spiraling at the edge of Milky Way's central black hole

A new image from the Event Horizon Telescope (EHT) collaboration—which includes scientists from the Center for Astrophysics | Harvard & Smithsonian (CfA)— has uncovered strong and organized magnetic fields spiraling from the edge of the supermassive black hole Sagittarius A* (Sgr A*).

Seen in polarized light for the first time, this new view of the monster lurking at the heart of the Milky Way galaxy has revealed a magnetic field structure strikingly similar to that of the black hole at the center of the M87 galaxy, suggesting that strong magnetic fields may be common to all black holes. This similarity also hints toward a hidden jet in Sgr A*.

The results were published in The Astrophysical Journal Letters.

Scientists unveiled the first image of Sgr A*—which is approximately 27,000 light-years away from Earth—in 2022, revealing that while the Milky Way's supermassive black hole is more than a thousand times smaller and less massive than M87's, it looks remarkably similar.

So scientists decided to check whether they are similar in all the  ways possible.

Part 1

Comment by Dr. Krishna Kumari Challa on March 27, 2024 at 10:49am

symbolic gesture in birds

Japanese tits (Parus minor) flutter their wings to invite their mate to enter the nest first. Scientists who observed eight breeding pairs of wild tits noticed that when one of the birds sat in front of the next box and fluttered its wings, the other would go in first. It’s the first documented evidence of birds using a symbolic gesture: one that has a specific meaning (like waving ‘goodbye’) but isn’t simply pointing at an object of interest. “It implies that birds have a level of understanding of symbolism that probably a lot of people wouldn’t have given them credit for before.

Comment by Dr. Krishna Kumari Challa on March 27, 2024 at 10:48am

Weird electron behaviour thrills physicists

Two teams have observed that electrons, which usually have a charge of –1, can behave as if they had fractional charges (such as –⅔) — and do so without being nudged by an external magnetic field. It’s the first time this ‘fractional quantum anomalous Hall effect’ has been observed experimentally, and physicists are scratching their heads over exactly how it works. It’s a fundamental discovery that might also someday have practical applications: fractionally charged particles are a key requirement for a certain type of quantum computer. 

Comment by Dr. Krishna Kumari Challa on March 27, 2024 at 9:45am

How can we cool our cities

Light roofs, light roads and better tree cover would make a real difference.

 If your street has established large trees, you will experience less than half the number of days with extreme heat compared on residents on treeless streets. If you live in a leafy street, your home is also worth more.

Blacktop roads are a surprisingly large source of heat. In summer, they can get up to 75°C. Research shows reflective sealants can cut the temperatures up to 13°C. Some councils have experimented with lighter roads, but to date, uptake has been minimal.

Cool roofs markedly reduce how much energy you need to cool a house. When used at scale, they lower the air temperatures of entire suburbs.

The simplest way to get a cool roof is to choose one with as light a color as possible. There are also high-tech options able to reflect even more heat.

Soon, we'll see even higher performance options available in the form of daytime radiative coolers—exceptional cooling materials able to reflect still more heat away from your house and cut glare.

Until we choose to change, homeowners and whole communities will keep paying dearly for the luxury of a dark roof through power bill pain and sweltering suburbs.

https://theconversation.com/if-youve-got-a-dark-roof-youre-spending...

Part 2

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Comment by Dr. Krishna Kumari Challa on March 27, 2024 at 9:43am

If you've got a dark roof, you're spending almost $700 extra a year to keep your house cool

A dark roof means you'll pay considerably more to keep your house cool in summer.When suburbs are full of dark colored roofs, the whole area heats up. And up. And up. This is part of the urban heat island effect.

Light coloured roofs or Cool roofs have many benefits. They slash how much heat gets into your house from the sun, keep the air surrounding your home cooler, boost your aircon efficiency, and make your solar panels work more efficiently.

At present, the world's cities account for 75% of all energy-related carbon dioxide emissions. It's vitally important we understand what makes cities hotter or cooler.

Brick, concrete, tarmac and tiles can store more heat than grass and tree-covered earth can, and release it slowly over time. This keeps the air warmer, even overnight.

Built-up areas also block wind, which cuts cooling. Then there's transport, manufacturing and air-conditioning, all of which increase heat.

The main way people had to keep cool was through how they designed their homes. In hot countries, buildings are often painted white, as well as having small windows and thick stone walls.

Part 1

Comment by Dr. Krishna Kumari Challa on March 27, 2024 at 9:35am

Dust storms may spread bacteria and fungi around the world

When allergy season hits, many blame their reactions on the local flora in the spring. However, African Saharan-Sahelian dust plumes, large enough to register on weather radar, travel around the globe every summer, bringing their own form of air pollution.

Researchers  have furthered previous research to identify microorganisms that might have hitched a ride in the du.... 

We all get allergies and potentially other more severe health effects when we breathe in dust, and it's not fully known as to what causes those allergies. Some people may think it is just the sand or clay minerals in the dust. Others think it is the metals or organics in the dust, and then some think it's the bacteria and fungi.

This research, published in the journal Environmental Science & Technology, is the first to study the association of bacteria and fungi with North American–Saharan dust storms.

Scientists noted that dust events can vary annually, with different elemental compositions each year.

 Microbiota was detected by extracting DNA from filters. Meticulous sequencing techniques detected bacterial genomes from 117 families and fungal genomes from 164 families. The technique did not show whether the microbes were alive, but it did detect several pathogenic bacteria and fungi, many of which are listed in the World Health Organization's global priority list of human pathogens.

It doesn't tell us if they are going to be able to infect us and make us sick. But at least the DNA of several pathogenic bacteria and fungi were identified in the African dust.

The biodiversity of bacteria and fungi was strongly correlated to a few elements, most notably calcium. The study showed that calcium and zirconium are important for explaining bacterial and fungal beta diversity, the ratio between regional and local species diversity.

A similar caveat was found in biota detections. Over 2,000 different organic groups were detected. 

Sourav Das et al, Respirable Metals, Bacteria, and Fungi during a Saharan–Sahelian Dust Event in Houston, Texas, Environmental Science & Technology (2023). DOI: 10.1021/acs.est.3c04158

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