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Comment by Dr. Krishna Kumari Challa 19 hours ago

How Salmonella overcomes host resistance

 The microbial species living in our gastrointestinal tract — the gut microbiota — help protect us against invading pathogens. One way they exert this “colonization resistance” is by producing antimicrobial products, such as the fatty acid propionate. The gut microbiota benefits the host by limiting enteric pathogen expansion (colonization resistance), partially via the production of inhibitory metabolites. Propionate, a short-chain fatty acid produced by microbiota members, is proposed to mediate colonization resistance against Salmonella enterica serovar Typhimurium (S. Tm).

Propionate is used in agricultural animals to limit infection by varieties of Salmonella bacteria, which cause food poisoning in humans.

Now, however, researchers have demonstrated that Salmonella can turn the tables and use propionate for its own purposes. The researchers showed in animal models that in the presence of inflammation, Salmonella changes its metabolism and uses propionate as a source of energy. They demonstrated that propionate metabolism supports expansion of Salmonella in the inflamed gut.

The findings, published in Cell Reports, show that in addition to promoting colonization resistance, propionate can fuel Salmonella growth, changing the understanding of propionate’s role and complicating its use as an antimicrobial treatment.

https://pubmed.ncbi.nlm.nih.gov/34986344/

https://researchnews.cc/news/11098/Salmonella-overcomes-host-resist...

Comment by Dr. Krishna Kumari Challa 19 hours ago

Tiger Shark Migrations Altered by Climate Change

Comment by Dr. Krishna Kumari Challa yesterday

Your gut senses the difference between real sugar and artificial sweetener

 Your taste buds may or may not be able to tell real sugar from a sugar substitute like Splenda, but there are cells in your intestines that can and do distinguish between the two sweet solutions. And they can communicate the difference to your brain in milliseconds.

Not long after the sweet taste receptor was identified in the mouths of mice 20 years ago, scientists attempted to knock those taste buds out. But they were surprised to find that mice could still somehow discern and prefer natural sugar to artificial sweetener, even without a sense of taste.

The answer to this riddle lies much further down in the digestive tract, at the upper end of the gut just after the stomach, according to research.

The researchers have  identified the cells that make us eat sugar, and they are in the gut. The sensing cells are in the upper reaches of the gut. 

Having discovered a gut cell called the neuropod cell, researchers have been pursuing this cell’s critical role as a connection between what’s inside the gut and its influence in the brain. The gut talks directly to the brain, changing our eating behaviour. And in the long run, these findings may lead to entirely new ways to treat diseases.

Originally termed enteroendrocrine cells because of their ability to secrete hormones, specialized neuropod cells can communicate with neurons via rapid synaptic connections and are distributed throughout the lining of the upper gut. In addition to producing relatively slow-acting hormone signals, the  researchers have shown that these cells also produce fast-acting neurotransmitter signals that reach the vagus nerve and then the brain within milliseconds.

 These latest findings further show that neuropods are sensory cells of the nervous system just like taste buds in the tongue or the retinal cone cells in the eye that help us see colors. They sense traces of sugar versus sweetener and then they release different neurotransmitters that go into different cells in the vagus nerve, and ultimately, the animal knows ‘this is sugar’ or ‘this is sweetener.’”

Using lab-grown organoids from mouse and human cells to represent the small intestine and duodenum (upper gut), the researchers showed in a small experiment that real sugar stimulated individual neuropod cells to release glutamate as a neurotransmitter. Artificial sugar triggered the release of a different neurotransmitter, ATP.

Using a technique called optogenetics, the scientists were then able to turn the neuropod cells on and off in the gut of a living mouse to show whether the animal’s preference for real sugar was being driven by signals from the gut.

Sugar has both taste and nutritive value and the gut is able to identify both.
Many people struggle with sugar cravings, and now we have a better understanding of how the gut senses sugars (and why artificial sweeteners don’t curb those cravings).

1. Kelly L. Buchanan, Laura E. Rupprecht, M. Maya Kaelberer, Atharva Sahasrabudhe, Marguerita E. Klein, Jorge A. Villalobos, Winston W. Liu, Annabelle Yang, Justin Gelman, Seongjun Park, Polina Anikeeva, Diego V. Bohórquez. The preference for sugar over sweetener depends on a gut sensor cell. Nature Neuroscience, 2022; DOI: 10.1038/s41593-021-00982-7

https://researchnews.cc/news/11088/Your-gut-senses-the-difference-b...

Comment by Dr. Krishna Kumari Challa on Saturday

ResearchNews Videos

Temperature Record 101: How We Know What We Know about Climate Change

Comment by Dr. Krishna Kumari Challa on Saturday

Being in space destroys more red blood cells

A world-first study has revealed how space travel can cause lower red blood cell counts, known as space anemia. Analysis of 14 astronauts showed their bodies destroyed 54 percent more red blood cells in space than they normally would on Earth, according to a study published in Nature Medicine.

Space anemia has consistently been reported when astronauts returned to Earth since the first space missions, but we didn't know why. This study shows that upon arriving in space, more red blood cells are destroyed, and this continues for the entire duration of the astronaut's mission.

Before this study, space anemia was thought to be a quick adaptation to fluids shifting into the astronaut's upper body when they first arrived in space. Astronauts lose 10 percent of the liquid in their blood vessels this way. It was thought astronauts rapidly destroyed 10 percent of their red blood cells to restore the balance, and that red blood cell control was back to normal after 10 days in space.

Now it was found that  the red blood cell destruction was a primary effect of being in space, not just caused by fluid shifts. They demonstrated this by directly measuring red blood cell destruction in 14 astronauts during their six-month space missions.

On Earth, our bodies create and destroy 2 million red blood cells every second. The researchers found that astronauts were destroying 54 percent more red blood cells during the six months they were in space, or 3 million every second. These results were the same for both female and male astronauts.

This discovery was made thanks to techniques and methods researchers developed to accurately measure red blood cell destruction. These methods were then adapted to collect samples aboard the International Space Station. They were able to precisely measure the tiny amounts of carbon monoxide in the breath samples from astronauts. One molecule of carbon monoxide is produced every time one molecule of heme, the deep-red pigment in red blood cells, is destroyed.

Trudel, G et al, Hemolysis contributes to anemia during long-duration space flight. Nat Med (2022). doi.org/10.1038/s41591-021-01637-7

https://phys.org/news/2022-01-space-red-blood-cells.html?utm_source...

Comment by Dr. Krishna Kumari Challa on Saturday

Copper-based chemicals may be contributing to ozone depletion

Copper released into the environment from fungicides, brake pads, antifouling paints on boats and other sources may be contributing significantly to stratospheric ozone depletion, according to a new study .

In a paper appearing this week in the journal Nature Communications, UC Berkeley geochemists show that copper in soil and seawater acts as a catalyst to turn organic matter into both methyl bromide and methyl chloride, two potent halocarbon compounds that destroy ozone. Sunlight worsens the situation, producing about 10 times the amount of these methyl halides.

The findings answer, at least in part, a long-standing mystery about the origin of much of the methyl bromide and methyl chloride in the stratosphere. Since the worldwide ban on chlorofluorocarbon (CFC) refrigerants and brominated halons used in fire extinguishers starting in 1989, these methyl halides have become the new dominant sources of ozone-depleting bromine and chlorine in the stratosphere. As the long-lived CFCs and halons slowly disappear from the atmosphere, the role of methyl halides increases.

Yi Jiao et al, Application of copper(II)-based chemicals induces CH3Br and CH3Cl emissions from soil and seawater, Nature Communications (2022). DOI: 10.1038/s41467-021-27779-3

https://phys.org/news/2022-01-copper-based-chemicals-contributing-o...

Comment by Dr. Krishna Kumari Challa on Saturday

Strong evidence shows Sixth Mass Extinction of global biodiversity in progress

The history of life on Earth has been marked five times by events of mass biodiversity extinction caused by extreme natural phenomena. Today, many experts warn that a Sixth Mass Extinction crisis is underway, this time entirely caused by human activities.

A comprehensive assessment of evidence of this ongoing extinction event was published recently in the journal Biological Reviews by biologists .

Drastically increased rates of species extinctions and declining abundances of many animal and plant populations are well documented, yet some deny that these phenomena amount to mass extinction. This denial is based on a biased view of the crisis which focuses on mammals and birds and ignores invertebrates, which of course constitute the great majority of biodiversity.

By extrapolating from estimates obtained for land snails and slugs, biologists estimated that since the year 1500, Earth could already have lost between 7.5 and 13% of the two million known species on Earth—a staggering 150,000 to 260,000 species.

Including invertebrates was key to confirming that we are indeed witnessing the onset of the Sixth Mass Extinction in Earth's history.

The situation is not the same everywhere, however. Although marine species face significant threats, there is no evidence that the crisis is affecting the oceans to the same extent as the land. On land, island species, such as those of the Hawaiian Islands, are much more affected than continental species. And the rate of extinction of plants seems lower than that of terrestrial animals.

To fight the crisis, various conservation initiatives have been successful for certain charismatic animals. But these initiatives cannot target all species, and they cannot reverse the overall trend of species extinction. Nonetheless, it is essential to continue such efforts, to continue to cultivate a wonder for nature, and to document biodiversity before it disappears.

Robert H. Cowie et al, The Sixth Mass Extinction: fact, fiction or speculation?, Biological Reviews (2022). DOI: 10.1111/brv.12816

https://phys.org/news/2022-01-strong-evidence-sixth-mass-extinction...

Comment by Dr. Krishna Kumari Challa on Friday

A mysterious new way of producing oxygen
Researchers have discovered that some microbes that live in the deep sea produce oxygen in a way never seen before. The surprising species, Nitrosopumilus maritimus, uses a common method to generate energy: the oxidation of ammonia to nitrite. But when researchers sealed the microbes in airtight containers, without light or oxygen, they were still somehow able to produce O2. The findings could have implications for everything from detecting the signs of life to determining how bacteria might adapt to a drop in ocean oxygen caused by climate change.

This has only been found previously in NC10 bacteria, which break up nitric oxide into nitrogen and oxygen and use the oxygen to oxidise methane. However, the NC10 bacteria are not known to release oxygen. https://www.chemistryworld.com/news/single-celled-marine-organism-f...

Comment by Dr. Krishna Kumari Challa on Friday

How to image atoms

Comment by Dr. Krishna Kumari Challa on Friday

Some birds sing the same song for hundreds of thousands of years

Many of the birds that awaken us each morning learn their melodious songs the same way that humans learn a dialect—from parents and neighbours.

But to most biologists, learning songs through mimicry is an uncertain and error-prone process, resulting in slow but inevitable change in song over the years.

A new study by biologists , however, documents songs in East African sunbirds that have remained nearly unchanged for more than 500,000 years, and perhaps for as long as 1 million years, making the songs nearly indistinguishable from those of relatives from which they've long been separated.

The amazingly static nature of their songs may be due to a lack of change in these birds' environments, which are stable mountain forests—so-called sky islands—isolated from other sky island populations of the same or similar species for tens of thousands to millions of years. The coloration of the birds' feathers has changed little, as well, making their plumage nearly indistinguishable from each other, even though some are separate, but closely related, species.

Jay P. McEntee et al, Punctuated evolution in the learned songs of African sunbirds, Proceedings of the Royal Society B: Biological Sciences (2021). DOI: 10.1098/rspb.2021.2062

https://phys.org/news/2022-01-birds-song-hundreds-thousands-years.h...

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