Comment

Comment by Dr. Krishna Kumari Challa on August 1, 2023 at 11:54am

When electrons slowly vanish during cooling: Researchers observe an effect unique to the quantum world

Many substances change their properties when they are cooled below a certain critical temperature. Such a phase transition occurs, for example, when water freezes. However, in certain metals there are phase transitions that do not exist in the macrocosm. They arise because of the special laws of quantum mechanics that apply in the realm of nature's smallest building blocks.

It is thought that the concept of electrons as carriers of quantized electric charge no longer applies near these exotic phase transitions. Researchers have now found a way to prove this directly. Their findings allow new insights into the exotic world of quantum physics. The publication has now been released in the journal Nature Physics.

If you cool water below zero degrees Celsius, it solidifies into ice. In the process, it abruptly changes its properties. As ice, for example, it has a much lower density than in a liquid state—which is why icebergs float. In physics, this is referred to as a phase transition. But there are also phase transitions in which characteristic features of a substance change gradually. If, for example, an iron magnet is heated up to 760 degrees Celsius, it loses its attraction to other pieces of metal—it is then no longer ferromagnetic, but paramagnetic. However, this does not happen abruptly, but continuously: The iron atoms behave like tiny magnets.At low temperatures, they are oriented parallel to each other. When heated, they fluctuate more and more around this rest position until they are completely randomly aligned, and the material loses its magnetism completely. So while the metal is being heated, it can be both somewhat ferromagnetic and somewhat paramagnetic.

The phase transition thus takes place gradually, so to speak, until finally all the iron is paramagnetic. Along the way, the transition slows down more and more. This behavior is characteristic of all continuous phase transitions. Physicists call it 'critical slowing down'. The reason is that with continuous transitions, the two phases get energetically closer and closer together.

Part 1

Comment by Dr. Krishna Kumari Challa on August 1, 2023 at 10:29am

New study links brain waves directly to memory

Neurons produce rhythmic patterns of electrical activity in the brain. One of the unsettled questions in the field of neuroscience is what primarily drives these rhythmic signals, called oscillations. Researchers have found that simply remembering events can trigger them, even more so than when people are experiencing the actual event.

The researchers, whose findings are published in the journal Neuron, specifically focused on what are known as theta oscillations, which emerge in the brain's hippocampus region during activities like exploration, navigation and sleep. The hippocampus plays a crucial role in the brain's ability to remember the past. Prior to this study, it was thought that the external environment played a more important role in driving theta oscillations. But this new study found that memory generated in the brain is the main driver of theta activity.

They found that theta oscillations in humans are more prevalent when someone is just remembering things, compared to experiencing events directly.

The results of the study could have implications for treating patients with brain damage and cognitive impairments, including patients who have experienced seizures, stroke and Parkinson's disease. Memory could be used to create stimulations from within the brain and drive theta oscillations, which could potentially lead to improvements in memory over time.

Sarah E. Seger et al, Memory-related processing is the primary driver of human hippocampal theta oscillations, Neuron (2023). DOI: 10.1016/j.neuron.2023.06.015

Comment by Dr. Krishna Kumari Challa on July 31, 2023 at 6:28am

Some might suggest that the nerve cells are activated by fear. Most people are familiar with the phenomenon of "freezing" caused by extreme fear. But that is not the case.

Researchers  have compared this type of motor arrest to motor arrest or freezing caused by fear, and they are not identical. They are very sure that the movement arrest observe here is not related to fear. Instead, they think  it has something to do with attention or alertness, which is seen in certain situations.

The researchers think it is an expression of a focused attention. However, they stress that the study has not revealed if this is indeed the case. It is something that requires more research to demonstrate.

The new study may be able to help us understand some of the mechanisms of Parkinson's disease.

Motor arrest or slow movement is one of the cardinal symptoms of Parkinson's disease. Scientists speculate that these special nerve cells in PPN are over-activated in Parkinson's disease. That would inhibit movement. Therefore, the study, which primarily has focused on the fundamental mechanisms that control movement in the nervous system, may eventually help us to understand the cause of some of the motor symptoms in Parkinson's disease.

Among other things, the researchers used optogenetics to stimulate the nerve cells in the brainstem.

In short, optogenetics is a biological technique that involves genetically modifying specific brain cells to make them more sensitive to light. This means that the cells can be activated by a flash of light.

In the study, the researchers were able to stimulate the specific group of nerve cells  in mice and thus determine the motor function of these cells.

 Haizea Goñi-Erro et al, Pedunculopontine Chx10+ neurons control global motor arrest in mice, Nature Neuroscience (2023). DOI: 10.1038/s41593-023-01396-3

Part 2

Comment by Dr. Krishna Kumari Challa on July 31, 2023 at 6:25am

Nerve cells in the brain can halt all movement in the body—even breathing

When a hunting dog picks up the scent of a deer, it sometimes freezes. On the spot. The same thing can happen to people who need to concentrate on a challenging task.

Now researchers have made a discovery that adds to our knowledge of what happens in the brain when we suddenly stop moving. They have found a group of nerve cells in the midbrain which, when stimulated, stop all movement. Not just walking; all forms of motor activity. They even make the mice stop breathing or breathe more slowly, and the heart rate slow down.

There are various ways to stop movement. What is so special about these nerve cells is that once activated they cause the the movement to be paused or freeze. Just like setting a film on pause. The actors movement suddenly stop on the spot.

When the researchers ended activating the nerve cells, the mice would start the movement exactly where it stopped. Just like when pressing "play" again.

This 'pause-and-play pattern' is very unique; it is unlike anything we have seen before. It does not resemble other forms of movement or motor arrest we or other researchers have studied. There, the movement does not necessarily start where it stopped, but may start over with a new pattern.

The nerve cells stimulated by the researchers are found in the midbrain in an area called the pedunculopontine nucleus (PPN), and they differ from other nerve cells there by expressing a specific molecular marker called Chx10. The PPN is common to all vertebrates including humans. So even though the study was performed in mice, the researchers expect the phenomenon to apply to humans too.

Part 1

Comment by Dr. Krishna Kumari Challa on July 30, 2023 at 1:44pm

Twinkle twinkle little star
What if you can 'listen' to that twinkle?
Wouldn’t that be wonderful?
Yes, you can, now!
Science makes it possible

Imagine the melodies of distant worlds!
Click on the video below to listen to the twinkle of a star

And clap like a child

 

Comment by Dr. Krishna Kumari Challa on July 30, 2023 at 11:43am

Who are scientists on whom experiments were performed?

Here is the story of a Doctor Who Jammed a Catheter Into His Heart to help humanity…

Werner Theodor Otto Forßmann : (29 August 1904 – 1 June 1979) was a German researcher and physician from Germany who shared the 1956 Nobel Prize in Medicine (with Andre Frederic Cournand and Dickinson W. Richards) for developing a procedure that allowed cardiac catheterization. In 1929, he put himself under local anesthesia and inserted a catheter into a vein of his arm. Not knowing if the catheter might pierce a vein, he put his life at risk. Forssmann was nevertheless successful; he safely passed the catheter into his heart.

Comment by Dr. Krishna Kumari Challa on July 29, 2023 at 8:14am

The result is that the mitochondria send two chemical signals to the cell when protein misfolding stress occurs: They release reactive oxygen compounds and block the import of protein precursors, which are produced in the cell and are only folded into their functional shape inside the mitochondrion, causing these precursors to accumulate in the cell. Among other things, the reactive oxygen compounds lead to chemical changes in a protein called DNAJA1. Normally, DNAJA1 supports a specific chaperone (folding assistant) in the cell, which molds the cell's newly formed proteins into the correct shape.

As a consequence of the chemical change, DNAJA1 now increasingly forces itself on the folding assistant HSP70 as its helper. HSP70 then takes special care of the misfolded protein precursors that accumulate around the mitochondrion because of the blocked protein import. By doing so, HSP70 reduces its interaction with its regular partner HSF1. HSF1 is now released and can migrate into the cell nucleus, where it can trigger the anti-stress mechanism for the mitochondrion.

It was very exciting to discover how the two mitochondrial stress signals are combined into one signal in the cell, which then triggers the cell's response to mitochondrial stress. Moreover, in this complex process, which is essentially driven by tiny local changes in concentration, the stress signaling pathways of the cell and the mitochondrion dovetail very elegantly with each other—like the cogs in a clockwork.

F. X. Reymond Sutandy et al, A cytosolic surveillance mechanism activates the mitochondrial UPR, Nature (2023). DOI: 10.1038/s41586-023-06142-0

Part 2

**

Comment by Dr. Krishna Kumari Challa on July 29, 2023 at 8:13am

Researchers discover how mitochondria call for help when under stress

As life propagated across Earth in the form of the widest variety of single-celled organisms, sometime between 3.5 and 1 billion years ago one such organism managed an evolutionary coup: Instead of devouring and digesting bacteria, it encapsulated its prey and used it as a source of energy. As a host cell, it offered protection and nutrition in return.

This is referred to as the endosymbiotic theory, according to which that one single-celled organism was the primordial mother of all higher cells, out of which all animals, fungi and plants developed. Over the course of billions of years, the encapsulated bacterium became the cell's powerhouse, the mitochondrion, which supplies it with the cellular energy currency ATP.

It lost a large part of its genetic material—its DNA—and exchanged smaller DNA segments with the mother cell. However, now as in the past, mitochondria divide independently of the cell and possess some genes of their own.

How closely the cell and the mitochondrion work together in human cells today is what some researchers are investigating. They have now discovered how the mitochondrion calls for help from the cell when it is under stress. Triggers for such stress can be infections, inflammatory diseases or genetic disorders, for example, but also nutrient deficiencies or cell toxins. The study has been published in the journal Nature.

A certain type of mitochondrial stress is caused by misfolded proteins that are not quickly degraded and accumulate in the mitochondrion. The consequences for both the mitochondrion and the cell are dramatic: Misfolded proteins can, for example, disrupt energy production or lead to the formation of larger amounts of reactive oxygen compounds, which attack the mitochondrial DNA and generate further misfolded proteins. In addition, misfolded proteins can destabilize the mitochondrial membranes, releasing signal substances from the mitochondrion that activate apoptosis, the cell's self-destruction program. The mitochondrion responds to the stress by producing more chaperones (folding assistants) to fold the proteins in order to reduce the misfolding, as well as protein shredding units that degrade the misfolded proteins. Until now, how cells trigger this protective mechanism was unknown.

The researchers artificially triggered misfolding stress in the mitochondria of cultured human cells and analyzed the result. What makes it difficult to unravel such signaling processes is that an incredibly large number take place simultaneously and at high speed in the cell.

The research team therefore availed itself of methods (transcriptome analyses) that can be used to measure over time to what extent genes are transcribed. In addition, the researchers observed, among other things, which proteins bind to each other at which point in time, at which intervals the concentrations of intracellular substances change, and what effects there are when individual proteins are systematically deactivated.

Part 1

Comment by Dr. Krishna Kumari Challa on July 29, 2023 at 8:03am

Microorganisms ward off parasites: Potential new function of CRISPR-Cas system discovered

Microorganisms use the CRISPR-Cas system to fight viral attacks. In genetic engineering, the microbial immune system is used for the targeted modification of the genetic make-up. A research team has now discovered another function of this specialized genomic sequence: archaea—microorganisms that are often very similar to bacteria in appearance—also use them to fight parasites. 

They analyzed the genetic material of microbes in the Earth's deep crust. More than 70% of the Earth's microorganisms are housed in the deep biosphere. If we want to understand diversity on our planet, it is worth taking a look into the deep.

The microbiologists have analyzed the water that a geyser in the U.S. spits to the surface from the depths, as well as samples from the Horonobe underground laboratory in Japan. The research team focused on archaea, which live in the ecosystem as hosts and parasites. The tiny microbes are highly similar to bacteria in cell size but have substantially different physiological properties. The result of their genomic analysis provided new insights: there were conspicuously few parasites in the vicinity of the hosts, and the hosts showed genetic resistance to the parasites. The researchers discovered the reason for this in the genetic scissors in the genome of the microorganisms.

In the course of evolution, the archaea have incorporated the parasitic DNA. If a parasite with the same DNA now attacks the organism, the foreign genetic material is probably recognized by the CRISPR system and presumably decomposed.

In order to rule out the possibility that they have only come across isolated cases, the researchers have extended the analysis to more than 7,000 genomes and observed the phenomenon very frequently.

Sarah P. Esser et al, A predicted CRISPR-mediated symbiosis between uncultivated archaea, Nature Microbiology (2023). DOI: 10.1038/s41564-023-01439-2

Comment by Dr. Krishna Kumari Challa on July 29, 2023 at 7:57am

How a gut microbe causes flies to live fast and die young

Researchers have uncovered how one species of gut bacteria causes fruit flies to perish early. This discovery illuminates the complex interactions between the microbes in our guts and our health.

The human gut is home to somewhere between 200 and 1,000 species of bacteria. The vast majority of these species are beneficial, converting food into useful compounds that the human body cannot make by itself. But some bacterial species have a negative impact on health.

The sheer number of bacterial species in the human gut makes it extremely challenging to untangle their individual effects on our health. Researchers find it much simpler to look at the gut microbiome of fruit flies since they only have about two to five bacterial species in their guts.

In a previous study, researchers have found that one of these species, Acetobacter persici, accelerated aging in flies, causing them to die early. A. persici has a drastic impact on fly lifespan, curtailing it by about 20%–30%.

Now, by feeding flies with a diet of dead A. persici, scientists have discovered the connection between A. persici and shortened fly lifespans.

To their surprise, the researchers found that the shortened lifespan is not due to a compound produced by A. persici. Rather, a component in the bacterium's cell wall triggers a receptor in the fly's gut, which stimulates the immune system, boosting the production of antimicrobial compounds and activating intestinal stem cells. It's this enhanced immunity that causes the flies to die young. In an intriguing twist, the team discovered that these effects also boost a fly's resistance to infection by a harmful bacterium that can kill flies. It thus provides flies with a short-term advantage in exchange for an early death—a tradeoff that the researchers dubbed a "live fast, die young" lifestyle.

This increased resistance to infection explains why the vast majority of flies in the wild have A. persici or other Acetobacter species in their guts. It's better to have a strong resistance to stressors such as infection rather than to live to a ripe old age.

The finding raises the possibility that "postbiotics"—food and drinks that contain dead gut microbes (rather than prebiotics containing live ones)—with health benefits could be developed.

The team now aims to determine the genes involved in the immune signaling that leads to shorter lifespans. They also want to see if the same mechanism occurs in other animals such as mice and humans.

Taro Onuma et al, Recognition of commensal bacterial peptidoglycans defines Drosophila gut homeostasis and lifespan, PLOS Genetics (2023). DOI: 10.1371/journal.pgen.1010709

• ‹ Previous
• 1
• …
• 356
• 357
• 358
• 359
• 360
• …
• 1084
• Next ›
• Page