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Comment by Dr. Krishna Kumari Challa on September 18, 2024 at 11:59am

By mapping for the first time the sites at which DNA replication starts in liver cells that regenerate after ablation, the scientists discovered that these are always located in non-coding regions. It was also observed that replication initiation was much more efficient in young mice than in old mice.

"These non-coding regions are not subject to regular error checking and therefore accumulate damage over time. After removal of the liver in young mice there is still little damage and DNA replication is possible. On the contrary, when the experiment is carried out in old mice, the excessive number of errors accumulated over time triggers an alarm system that prevents DNA replication.

This block of DNA replication prevents cells from proliferating, leading to degradation of cell functions and tissue senescence.

These observations could help explain why slowly proliferating tissues, such as the liver, age faster than rapidly proliferating tissues, such as the intestine. In cells that have remained dormant for long periods, too many cryptic DNA lesions have accumulated in the non-coding regions, which contain the origins of replication, and prevent replication from being triggered. In rapidly proliferating tissues, on the other hand, little damage accumulates thanks to frequent cell renewal, and the origins of replication retain their efficiency.

 In vivo DNA replication dynamics unveil aging-dependent replication stress, Cell (2024). DOI: 10.1016/j.cell.2024.08.034. www.cell.com/cell/fulltext/S0092-8674(24)00963-2

Part 2

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Comment by Dr. Krishna Kumari Challa on September 18, 2024 at 11:58am

Why some organs age faster than others: Scientists discover hidden mutations in non-coding DNA

The accumulation of mutations in DNA is often mentioned as an explanation for the aging process, but it remains just one hypothesis among many. A team of researchers has identified a mechanism that explains why certain organs, such as the liver, age more rapidly than others.

The mechanism reveals that damages to non-coding DNA, which are often hidden, accumulate more in slowly proliferating tissues, such as those of the liver or kidneys. Unlike in organs that regenerate frequently, these damages remain undetected for a long time and prevent cell division. These results, published in the journal Cell, open new avenues for understanding cellular aging and potentially slowing it down.

Our organs and tissues do not all age at the same rate. Aging, marked by an increase in senescent cells—cells that are unable to divide and have lost their functions—affects the liver or kidneys more rapidly than the skin or intestine.

The mechanisms that contribute to this process are the subject of much debate within the scientific community. While it is widely accepted that damage to the genetic material (DNA), which accumulates with age, is at the root of aging, the link between the two phenomena remains unclear.

DNA molecules contain coding regions—the genes that code for proteins—and non-coding regions that are involved in the mechanisms that regulate or organize the genome. Constantly damaged by external and internal factors, the cell has DNA repair systems that prevent the accumulation of errors.

Errors located in the coding regions are detected when genes are transcribed, i.e. when they are activated. Errors in non-coding regions are detected during cell renewal, which requires the creation of a new copy of the genome each time, via the process of DNA replication. However, cell renewal does not occur with the same frequency depending on the type of tissue or organ.

Tissues and organs that are in constant contact with the outside environment, such as the skin or intestine, renew their cells (and therefore replicate their DNA) more often—once or twice a week—than internal organs, such as the liver or kidneys, whose cells proliferate only a few times per year.

Part 1

Comment by Dr. Krishna Kumari Challa on September 18, 2024 at 11:36am

Considering their findings, the researchers suggested that there is an "aging cost" that comes with maintaining resistance to stress on a population level. Besides shedding light on a potentially ancient mechanism of aging, the factors that contribute to bacterial aging could be investigated as new antibiotic targets.

Additionally, some human diseases are also perpetuated through cellular stress states, and understanding how these work on a molecular level could lead to the development of new treatments.

Time waits for no one, not even bacteria—and that's a good thing. Far from immortal beings beyond the reaches of aging, bacteria are an interesting system in which to study the molecular mechanisms that contribute to age-related decline.

Their rapid and robust growth means we can observe many generations in a relatively short experiment and test the effects of all kinds of environmental and genetic factors on the complex process of aging.

Source:  American Society for Microbiology
Part 3
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Comment by Dr. Krishna Kumari Challa on September 18, 2024 at 11:35am

Asymmetric division does damage control
Using mathematical models and data from the 2005 study, other scientists later showed that asymmetry is important for the whole population, as it elevates the population's fitness by maintaining variance. Variance is what natural selection acts upon, and more variation in a population generally equates with a better chance of survival in changeable conditions.

This study was important for reconciling previously conflicting views about bacterial aging and showing how important aging can be on an evolutionary level.

But how does asymmetric division help to keep populations fit? Part of the answer lies in protein aggregation, a contributor to aging in both bacteria and eukaryotic cells. Protein aggregation is implicated in many age-related diseases in humans, including Alzheimer's and Parkinson's, as these aggregates can be toxic and cause cells to die.
Proteins also aggregate in E. coli, as researchers showed using fluorescent molecules that attach to aggregates, but are cleverly dealt with to minimize damage. As a feature of asymmetric division, older cells accumulate proteins to segregate the age-related damage, keeping their offspring looking "younger," molecularly speaking.
Stress ages bacteria and humans alike
Stress is another factor that is thought to contribute to aging in humans, and a 2024 paper suggests that the same is true for our bacterial companion, E. coli. Like any kind of cells, E. coli cells accumulate mutations throughout their lifetimes.
Some of these mutations may be nonlethal but still negatively impact the cell's fitness, for example, causing an important protein to lose its function. Such deleterious loss-of-function mutations can kickstart a stress state inside the cell that ultimately helps it to survive the mutation.

The researchers analyzed the effects of over 60 different nonlethal loss-of-function mutations in E. coli, focusing on mutants with non-functional ATP synthases, large protein complexes that allow cells to generate energy in the form of ATP.

These mutants were found to increase their metabolic activity to compensate for the mutation, which comes at a cost—they grow slower, and some enter a purgatory-like, "postreplicative" state faster than non-mutants, especially if their surroundings are nutrient-poor.
Part 2

Comment by Dr. Krishna Kumari Challa on September 18, 2024 at 11:34am

How bacteria age

Any organism that lives, grows and reproduces must also age. People often think of aging in the physical sense—gray hair, slowed movements and wrinkles—but aging fundamentally occurs on a molecular level, inside of cells.

As organisms age, their cells accumulate damage that impairs functioning. Molecular damage is implicated in many age-related conditions in humans and is equally relevant for single-celled organisms. While they may not "look" their age, bacteria feel the passage of time too.

Bacteria differ from us in many ways, including in their modes of growth and reproduction. Unlike humans and other animals, single-celled organisms, such as bacteria and some fungi, can undergo a process called binary fission to reproduce, meaning that they duplicate their DNA and then split in two. Replication via binary fission can be very fast—the fastest-growing bacterium we know of can divide in less than 10 minutes.

Considering our very different ways of life, it might seem difficult to apply the concept of aging to bacteria. Indeed, it was long thought that bacteria and other organisms that reproduce via binary fission do not age at all. This was because binary fission was thought to be a symmetrical division, producing a parent and offspring identical in age, thus leading to what scientists call 'functional immortality' for the population.

On the other hand, asymmetric division, whereby the parent is older than the offspring, was thought to be required for an organism to be able to age at all.

Evidence against the accepted immortality paradigm first came in 2005, when scientists showed that Escherichia coli actually exhibits differences between "old" and "new" in parent and offspring cells, respectively. By following dividing cells with a microscope, the researchers could show that the older cells' growth rate and offspring production decline over time, and that they die more frequently than their younger offspring cells. Thus, despite looking the same, the cells undergo divisions that leave them functionally asymmetric, causing cells to age over time.

Part 1

Comment by Dr. Krishna Kumari Challa on September 18, 2024 at 11:22am

Over 3,600 food packaging chemicals found in human bodies

More than 3,600 chemicals used in food packaging or preparation have been detected in human bodies, some of which are hazardous to health, while little is known about others, a study said this week.

Around 100 of these chemicals are considered to be of "high concern" to human health.

Some of these chemicals are relatively well-studied and have already been found in human bodies, such as PFAS "forever chemicals" and bisphenol A—both of which are the target of bans.

But little is known about the health effects of others.

The researchers had previously catalogued around 14,000 food contact chemicals (FCCs), which are capable of "migrating" into food from packaging made of plastic, paper, glass, metal or other materials.

They can also come from other parts of the food-making process, such as from conveyer belts or kitchen utensils.

The researchers then searched for these chemicals in existing biomonitoring databases, which track chemicals in human samples.

The team was expecting to find a few hundred FCCs. Instead, they were surprised to find 3,601—a quarter of all the known FCCs.

However, this study could not show that all these chemicals necessarily ended up in bodies from food packaging, as "other exposure sources are possible".

Among the "high concern" chemicals were numerous PFAS, also known as forever chemicals, which have been detected in many parts of the human body in recent years and linked to a range of health problems.

Also detected was bisphenol A, a hormone-disrupting chemical used to make plastics that has already been banned from baby bottles in many countries.

Another hormone-disrupting chemical was phthalates, which has been linked to infertility.

Less is known about oligomers, which are also byproducts of plastic production.

When it comes to toxicology, an old saying is that "the dose makes the poison".

A limitation of the study was that it could not say whether there were particularly high concentrations of any of the chemicals.

Experts warned that  these chemicals can interact with each other, pointing to a single sample that had up to 30 different PFAS.

They recommended that people reduce their contact time with packaging—and to avoid heating up food in the packaging it came in.

This work is to raise awareness that the way we package our food is... going in a direction which is not good for the environment and human health.

Evidence for widespread human exposure to food contact chemicals, Journal of Exposure Science & Environmental Epidemiology (2024). DOI: 10.1038/s41370-024-00718-2

Comment by Dr. Krishna Kumari Challa on September 18, 2024 at 11:08am

Quantum sensing offers an exciting opportunity to probe the world around us in new ways, and holds promise to measure quantities such as magnetic and electric fields or temperature in ways which classical systems could not.
By showing that we can optically detect quantum coherence in molecules at room temperature, this work provides a proof-of-principle that the key properties needed for room-temperature quantum sensing can be achieved in a system which can be chemically synthesized.

Adrian Mena et al, Room-Temperature Optically Detected Coherent Control of Molecular Spins, Physical Review Letters (2024). DOI: 10.1103/PhysRevLett.133.120801

part 2

Comment by Dr. Krishna Kumari Challa on September 18, 2024 at 11:06am

Quantum tech breakthrough could enable precision sensing at room temperature

A breakthrough in quantum technology research could help realize a new generation of precise quantum sensors that can operate at room temperature.

The research—carried out by an international team of researchers shows how the quantum states of molecules can be controlled and sensitively detected under ambient conditions.

The findings could help unlock a new class of quantum sensors which could be used to probe biological systems, novel materials, or electronic devices by measuring magnetic fields with high sensitivity and spatial resolution.

Enabled by using molecules as the quantum sensor, future devices which build on the team's research could measure magnetic fields down to nanometer-length scales in a way which is convenient to deploy.

In a paper, titled "Room-temperature optically detected coherent control of molecular s..." published in the journal Physical Review Letters, the researchers show how they could manipulate a specific quantum property known as 'spin' in organic molecules and measure it with visible light, all at room temperature.

The team used lasers to align the spins of electrons in the molecules, which can be thought of as tiny quantum-mechanical magnets. Using carefully-directed pulses of microwave radiation, they could control these spin states into desired quantum states. They could then measure the state of the spins using the amount of visible light emitted from the molecules from a second laser pulse, which varies according to the quantum state of the spins.

In their proof-of-principle demonstration, the team used an organic molecule called pentacene incorporated in two forms of a material called para-terphenyl, both in crystals and a thin film, which could open new applications in future devices.

The team showed that they could optically detect the quantum coherence—the timescale over which quantum states live—of the molecules for up to a microsecond at room temperature, much longer than the time needed to manipulate the states.

The longer quantum states can be maintained, the more information future sensors could collect about their interactions with the properties they are measuring.

part1 

Comment by Dr. Krishna Kumari Challa on September 17, 2024 at 11:47am

Kleptoparasitism is spreading avian flu

Most seabirds take fish, squid, or other prey from the first few metres of seawater. Scavenging is common.

But there are other tactics. Frigatebirds, skuas, and gulls rely on the success of other seabirds. These large, strong birds chase, harry, and attack their targets until they regurgitate or drop the prey they’ve just caught. They’re the pirates of the seabird world, stealing hard-earned meals from other species. This behaviour is known as kleptoparasitism, from the Ancient Greek word kléptēs, thief.

The strategy is brutal, effective, and a core behaviour for these important seabirds. But as new research shows, it comes with major risks for the thieves. The new strain of avian flu is killing birds by their millions – and researchers found that kleptoparasitism could spread the virus very easily.

https://conbio.onlinelibrary.wiley.com/doi/full/10.1111/conl.13052

Comment by Dr. Krishna Kumari Challa on September 17, 2024 at 10:01am

Scientists mix sky's splendid hues to reset circadian clocks

Like sunrise, colours rest circadian rhythms

Those mesmerizing blue and orange hues in the sky at the start and end of a sunny day might have an essential role in setting humans' internal clocks.

In new research , a novel LED light that emits alternating wavelengths of orange and blue outpaced two other light devices in advancing melatonin levels in a small group of study participants.

Published in the Journal of Biological Rhythms, the finding appears to establish a new benchmark in humans' ability to influence their circadian rhythms, and reflects an effective new approach to counteract seasonal affective disorder (SAD).

Alexandra Neitz et al, Toward an Indoor Lighting Solution for Social Jet Lag, Journal of Biological Rhythms (2024). DOI: 10.1177/07487304241262918

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