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Comment by Dr. Krishna Kumari Challa on February 7, 2023 at 11:35am

Bacteria use dogma-defying DNA packaging

Some bacteria have a bizarre way of packaging chromosomes and regulating gene expression: they use proteins that weren’t thought to exist in bacteria at all. Researchers report that proteins called histones seem to coat regions of the bacterial chro... in two species. This is a marked difference from histones’ function in eukaryotes (which includes animals, plants and fungi), in which the proteins form a spool for DNA to wind around. The researchers surveyed thousands of bacterial genomes and found histone-like proteins in about 2%. For now, it’s unclear what the histones might be doing, and how their unusual mode of action might help the bacteria to survive.

https://www.biorxiv.org/content/10.1101/2023.01.26.525422v1?utm_sou...

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Driving culture gives us ‘car brain’

People seem to be more likely to excuse the negative effects of driving — such as pollution and accidents — than those in other areas of life. In a survey of 2,157 drivers and non-drivers in the United Kingdom, roughly half were asked to rate a statement about cars. The others were given an almost identical sentence about another issue. For example, 75% agreed that people shouldn’t smoke in highly populated areas where others have to breathe in the fumes — but only 17% agreed that people shouldn’t drive in highly populated areas. The researchers suggest that this ‘motonormativity’ inhibits our ability to think objectively about how we use cars.

https://psyarxiv.com/egnmj/

Comment by Dr. Krishna Kumari Challa on February 7, 2023 at 11:13am

Global study shows influences of climate change on terrestrial ecosystems

In a study published in Nature Geoscience, plant ecologistshave shown how global climate change is impacting the Earth's terrestrial ecosystems. Changes in vegetation activity could in most cases be explained by temperature and soil moisture changes, while changes in solar radiation and atmospheric CO₂ levels seldom played a dominant role.

In some of the ecosystems studied, years of increased vegetation activity have been followed by decreases. Such trend reversals raise the question of whether terrestrial ecosystems will continue to make large contributions to the sequestration of atmospheric carbon.

Researchers 

 linked global remote sensing data from the past 40 years to a novel dynamic model of plant growth. This model allows the identification of the climate factors involved in global climate change that are driving vegetation change.

These factors include air temperature, soil temperature, soil moisture, solar radiation, and atmospheric CO₂ levels. The method allows, for the first time, the attribution of measured changes in vegetation activity to individual climate factors.

Steven I. Higgins et al, Shifts in vegetation activity of terrestrial ecosystems attributable to climate trends, Nature Geoscience (2023). DOI: 10.1038/s41561-022-01114-x

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Comment by Dr. Krishna Kumari Challa on February 7, 2023 at 11:04am

Why icicles are rippled

When you look at these icicles carefully, you may notice that they show a characteristic pattern of ripples—always around one centimeter wide. What causes these ripples? Using an icicle machine of their own design, physicists and chemists investigated this question, and discovered that salt plays an important part in the formation process of the ripples.

 It was discovered that the flow of liquid water caused the ripples to appear. Using pure water, the layer of salty liquid water around the icicle was absent, and the formation process looked more like a dripping candle. When saltier water was used, the icicle was surrounded by a thin film of liquid, salty water, and the flow of that water created the regular ripples. The more salt the water contained, the stronger the process, causing thicker ripples to eventually form.

In nature, water always contains a small concentration of salt. This explains the beautiful structures we find on our gutters and car bumpers in the morning—rippled by a thin layer of slightly salty water that was at work throughout the night.

 Menno Demmenie et al, Growth and Form of Rippled Icicles, Physical Review Applied (2023). DOI: 10.1103/PhysRevApplied.19.024005

Comment by Dr. Krishna Kumari Challa on February 7, 2023 at 9:23am

Scientists detect molten rock layer hidden under Earth's tectonic plates

Scientists have discovered a new layer of partly molten rock under the Earth's crust that might help settle a long-standing debate about how tectonic plates move.

Researchers had previously identified patches of melt at a similar depth. But a new study  revealed for the first time the layer's global extent and its part in plate tectonics.

The molten layer is located about 100 miles from the surface and is part of the asthenosphere, which sits under the Earth's tectonic plates in the upper mantle. The asthenosphere is important for plate tectonics because it forms a relatively soft boundary that lets tectonic plates move through the mantle.

The reasons why it is soft, however, are not well understood. Scientists previously thought that molten rocks might be a factor. But this study shows that melt, in fact, does not appear to notably influence the flow of mantle rocks.

The convection of heat and rock in the mantle are the prevailing influence on the motion of the plates. Although the Earth's interior is largely solid, over long periods of time, rocks can shift and flow like honey.

Showing that the melt layer has no influence on plate tectonics means one less tricky variable for computer models of the Earth.

Junlin Hua, Asthenospheric low-velocity zone consistent with globally prevalent partial melting, Nature Geoscience (2023). DOI: 10.1038/s41561-022-01116-9. www.nature.com/articles/s41561-022-01116-9

Comment by Dr. Krishna Kumari Challa on February 6, 2023 at 11:55am

In the new study, teh researchers delved further into this activation failure, which occurs in the lymph nodes, which filter fluids that drain from nearby tissues. The lymph nodes are where “killer T cells” encounter dendritic cells, which present antigens (tumor proteins) and help to activate the T cells.

To explore why some killer T cells fail to be properly activated, researchers studied mice that had tumors implanted either in the lungs or in the flank. All of the tumors were genetically identical.

The researchers found that T cells in lymph nodes that drain from the lung tumors did encounter dendritic cells and recognize the tumor antigens displayed by those cells. However, these T cells failed to become fully activated, as a result of inhibition by another population of T cells called regulatory T cells.

These regulatory T cells became strongly activated in lymph nodes that drain from the lungs, but not in lymph nodes near tumors located in the flank, the researchers found. Regulatory T cells are normally responsible for making sure that the immune system doesn’t attack the body’s own cells. However, the researchers found that these T cells also interfere with dendritic cells’ ability to activate killer T cells that target lung tumors.

The researchers also discovered how these regulatory T cells suppress dendritic cells: by removing stimulatory proteins from the surface of dendritic cells, which prevents them from being able to turn on killer-T-cell activity.

Further studies revealed that the activation of regulatory T cells is driven by high levels of interferon gamma in the lymph nodes that drain from the lungs. This signaling molecule is produced in response to the presence of commensal bacterial — bacteria that normally live in the lungs without causing infection.

The researchers have not yet identified the types of bacteria that induce this response or the cells that produce the interferon gamma, but they showed that when they treated mice with an antibody that blocks interferon gamma, they could restore killer T cells’ activity.

Interferon gamma has a variety of effects on immune signaling, and blocking it can dampen the overall immune response against a tumor, so using it to stimulate killer T cells would not be a good strategy to use in patients.

Researchers are now exploring other ways to help stimulate the killer T cell response, such as inhibiting the regulatory T cells that suppress the killer-T-cell response or blocking the signals from the commensal bacteria, once the researchers identify them.

Maria Zagorulya, Leon Yim, et al. Tissue-specific abundance of interferon-gamma drives regulatory T cells to restrain DC1-mediated priming of cytotoxic T cells against lung cancer. Immunity. DOI: 10.1016/j.immuni.2023.01.010

Part 2

Comment by Dr. Krishna Kumari Challa on February 6, 2023 at 11:52am

Why lung cancer doesn't respond well to immunotherapy

Immunotherapy — drug treatment that stimulates the immune system to attack tumors — works well against some types of cancer, but it has shown mixed success against lung cancer.

A new study helps to shed light on why the immune system mounts such a lackluster response to lung cancer, even after treatment with immunotherapy drugs. In a study of mice, the researchers found that bacteria naturally found in the lungs help to create an environment that suppresses T-cell activation in the lymph nodes near the lungs.

The researchers did not find that kind of immune-suppressive environment in lymph nodes near tumours growing near the skin of mice. They hope that their findings could help lead to the development of new ways to rev up the immune response to lung tumours.

There is a functional difference between the T-cell responses that are mounted in the different lymph nodes. Researchers are hoping to identify a way to counteract that suppressive response, so that they can reactivate the lung-tumor-targeting T cells.
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For many years, scientists have known that cancer cells can send out immunosuppressive signals, which leads to a phenomenon known as T-cell exhaustion. The goal of cancer immunotherapy is to rejuvenate those T cells so they can begin attacking tumors again.

One type of drug commonly used for immunotherapy involves checkpoint inhibitors, which remove the brakes on exhausted T cells and help reactivate them. This approach has worked well with cancers such as melanoma, but not as well with lung cancer.

Recent research work has offered one possible explanation for this: Researchers found that some T cells stop working even before they reach a tumor, because of a failure to become activated early in their development. In a 2021 paper, they identified populations of dysfunctional T cells that can be distinguished from normal T cells by a pattern of gene expression that prevents them from attacking cancer cells when they enter a tumor.

“Despite the fact that these T cells are proliferating, and they’re infiltrating the tumor, they were never licensed to kill”.
Part 1

Comment by Dr. Krishna Kumari Challa on February 6, 2023 at 11:43am

Genes decide the willow warbler's migration routes

Since antiquity, humans have been fascinated by birds’ intercontinental migratory journeys. A new study shows that two areas in their genome decide whether a willow warbler flies across the Iberian Peninsula to western Africa, or across the Balkans to eastern and southern Africa.

Researchers have long known that the behaviour that causes songbirds to migrate in a specific direction towards a remote winter location is something they are born with. The recent study aims to further understanding of the genetics behind this behaviour. With the help of modern technology, and 20 years of research into the genetics of songbirds and their migration routes, the researchers managed to identify which parts of the genome that determine the songbirds’ routes.

“The songbirds’ direction of travel is determined by two areas in the genome. Genes from the southern subspecies take the bird towards the southwest, across the Iberian peninsula to their wintering grounds in western Africa. Genes belonging to the northern subspecies instead lead the willow warblers towards the southeast, over the Balkans, to locations in eastern and southern Africa, according to the study.

Researchers have previously assumed that interbreeding between subspecies that move in different directions would result in offspring that migrate in a direction in between these two. For willow warblers, this would mean a route straight over the Mediterranean and the Sahara, with probable higher mortality than if they flew west or east of that route. Instead, researchers discovered that crosses between northern and southern willow warblers usually migrate like one or other of the subspecies. The price of interbreeding, then, is lower than researchers previously thought. 

Researchers are surprised that such complex behaviour as variations in migratory patterns can to such a large extent be explained by just two genetic areas.

Knowledge of the willow warbler’s behaviour also helps us to understand how different species’ spectacular migratory patterns have developed through evolution. Climate change means that many species are being forced to alter their routes when the habitats they are adapted to change. The more we know about the genetics of migration, the better understanding we will gain of the birds’ capacity to adapt their migration patterns in response to climate change.

Kristaps Sokolovskis et al, Migration direction in a songbird explained by two loci, Nature Communications (2023). DOI: 10.1038/s41467-023-35788-7

Comment by Dr. Krishna Kumari Challa on February 6, 2023 at 9:26am

Will revitalizing old blood slow aging?

Young blood has a rejuvenating effect when infused into older bodies, according to recent research: Aging hearts beat stronger, muscles become stronger, and thinking becomes sharper.

Many scientists are looking for the elements of young blood that can be captured or replicated and put into a pill. But what if the best way to get the benefits of young blood is to simply rejuvenate the system that makes blood?

An aging blood system, because it's a vector for a lot of proteins, cytokines, and cells, has a lot of bad consequences for the organism. A 70-year-old with a 40-year-old blood system could have a longer healthspan, if not a longer lifespan. Rejuvenating an older person's blood may now be within reach, based on recent findings according to a paper published in Nature Cell Biology.

According to new research ,  an anti-inflammatory drug, already approved for use in rheumatoid arthritis, can turn back time in mice and reverse some of the effects of age on the hematopoietic system. These results indicate that such strategies hold promise for maintaining healthier blood production in the elderly.

The researchers only identified the drug after a comprehensive investigation of the stem cells that create all blood cells and the niches where they reside in the center of the bones.

All blood cells in the body are created by a small number of stem cells that reside in bone marrow. Over time, these hematopoietic stem cells start to change: They produce fewer red blood cells (leading to anemia) and fewer immune cells (which raises the risk of infection and impedes vaccination efforts), and they have trouble maintaining the integrity of their genomes (which can lead to blood cancers).

The researchers first tried to rejuvenate old hematopoietic stem cells, in mice, with exercise or calorie-restricting diet, both generally thought to slow the aging process. Neither worked. Transplanting old stem cells into young bone marrow also failed. Even young blood had no effect on rejuvenating old blood stem cells.

They then took a closer look at the stem cells' environment, the bone marrow. Blood stem cells live in a niche; they thought what happens in this specialized local environment could be a big part of the problem. 

With new techniques developed  that enable detailed investigation of the bone marrow milieu, the researchers found that the aging niche is deteriorating and overwhelmed with inflammation, leading to dysfunction in the blood stem cells. One inflammatory signal released from the damaged bone marrow niche, IL-1B, was critical in driving these aging features, and blocking it with the drug anakinra remarkably returned the blood stem cells to a younger, healthier state. Even more youthful effects on both the niche and the blood system occurred when IL-1B was prevented from exerting its inflammatory effects throughout the animal's life.

The researchers are now trying to learn if the same processes are active in humans and if rejuvenating the stem cell niche earlier in life, in middle age, would be a more effective strategy. Meanwhile, "treating elderly patients with anti-inflammatory drugs blocking IL-1B function should help with maintaining healthier blood production".

Carl A. Mitchell et al, Stromal niche inflammation mediated by IL-1 signalling is a targetable driver of haematopoietic ageing, Nature Cell Biology (2023). DOI: 10.1038/s41556-022-01053-0

Comment by Dr. Krishna Kumari Challa on February 4, 2023 at 12:54pm

Bird flu detected in mammals but risk to humans low: experts

Experts have warned that the recent detection of bird flu in mammals including foxes, otters, minks, seals and even grizzly bears is concerning but emphasized that the virus would have to significantly mutate to spread between humans.

It is rare that bird flu jumps over into mammals—and rarer still that humans catch the potentially deadly virus.

However two recent larger scale infections have raised concerns that bird flu has the potential to spread between mammals.

One was an outbreak of H5N1 with the PB2 mutation at a Spanish farm in October that led to the culling of more than 50,000 minks.

Transmission between the minks has not been confirmed, with further research ongoing.

The mass death of some 2,500 endangered seals found along Russia's Caspian Sea coast last month has also raised concern.

But it was always concerning when a flu virus enters mammals "because they're often the mixing point of influenza viruses, or they create an environment where mutations can occur and then can become adapted in humans".

If H5N1 did mutate into a strain that could circulate among humans, the current seasonal flu vaccine could be fairly easily updated to include it.

Over the last two decades, there have been 868 confirmed H5N1 cases in humans with 457 deaths, according to the World Health Organization. There were four confirmed cases and one death last year.

Last month, Ecuador reported South America's first case of the A(H5) bird flu virus in a human—a nine-year-old girl who was in contact with backyard poultry.

The experts called for continued surveillance of avian influenza in wild birds, poultry and mammals, in order for humans to limit their exposure.

source: AFP

Comment by Dr. Krishna Kumari Challa on February 4, 2023 at 12:48pm

Rocket industry could undo decades of work to save the ozone layer

The ozone layer is on track to heal within four decades, according to a recent UN report, but this progress could be undone by an upsurge in rocket launches expected during the same period.

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Rates of hatching failure in birds almost twice as high as previous...

Hatching failure rates in birds are almost twice as high as experts previously estimated, according to the largest ever study of its kind by researchers 

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How long does COVID immunity last?

How quickly does immunity from vaccination, infection with SARS-CoV-2, or a combination of the two, wane? Studies from Portugal, Israel, Sweden and Qatar have offered clues, but the real answer is: it’s complicated. ‘Hybrid’ immunity gained from vaccination and infection provides some protection against reinfection for around eight months, longer than immunity acquired from a booster alone. But the emergence of new variants makes it hard to determine the role of immune evasion. One study suggests that immunity against reinfection could last up to three years — if the virus does not mutate. The data make it difficult to predict when new surges of infections might occur — or when to schedule booster shots.

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Using muon detectors to remotely create a 3D image of the inside of...

A team of physicists affiliated with several institutions in France has developed a way to use muon detectors to create 3D images of difficult-to-access objects, such as a reactor inside a nuclear plant. The research is published in the journal Science Advances.

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