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Comment by Dr. Krishna Kumari Challa on Monday

Africa's forests have switched from absorbing to emitting carbon, new study finds

Africa's forests have shifted from absorbing to emitting carbon since 2010, primarily due to deforestation and degradation in tropical rainforests. Annual biomass losses of about 106 billion kg have not been offset by gains elsewhere. This transition threatens global climate targets, highlighting the urgent need for stronger forest protection and restoration efforts

Loss of tropical moist broadleaf forest has turned Africa's forests from a carbon sink into a source, Scientific Reports (2025). DOI: 10.1038/s41598-025-27462-3

Comment by Dr. Krishna Kumari Challa on Monday

New universal law predicts how most objects shatter

When a plate drops or a glass smashes, you're annoyed by the mess. But for some physicists, the broken pieces are a source of fascination: Why does everything break into such a huge variety of sizes? Now researchers  have come up with a simple, elegant law for how objects shatter, whether they are brittle solids, liquid drops, or exploding bubbles. 

Scientists have long suspected that there was something universal about fragmentation. If you count how many fragments fall into each size range and make a graph of that distribution, it would have the same shape regardless of the object that shattered. 

Their starting point was the massive chaos of a shattering event. In the majority of cases, the most likely outcome would always be the messiest and most irregular one, a principle he called maximal randomness. This is nature choosing the path of least resistance. 

However, because it is generally known that chaos must obey physical limits, they introduced a conservation law that they had previously discovered. This law acts as an invisible rule that ensures the overall scale of the fragments (how many large pieces and how many small pieces) cannot change randomly as the object breaks. To come up with his universal fragmentation law, they combined both maximal randomness and the conservation law. 

A kinematic constraint applied to a maximal randomness principle infers both the power law shape of the fragment size distribution and the value of its dimensionality-dependent exponent," they wrote in their paper published in the journal Physical Review Letters. 

By linking these two principles, they were able to mathematically predict the universal size pattern of the fragments. They showed that the law perfectly matched large amounts of fragmentation data collected over decades from a variety of objects, including brittle solids and liquids. And they tested it in an original experiment by crushing single sugar cubes and correctly predicted the specific size pattern based on the cube's three-dimensional shape.

However, this universal law doesn't explain every breakage. The rule works best when an object shatters randomly, such as when a glass tumbler suddenly hits the floor. But it doesn't work well if the material is too soft, like some plastics, or if the breakup is too orderly, such as when surface tension causes a stream of water to break into droplets of the same size.

Emmanuel Villermaux, Fragmentation: Principles versus Mechanisms, Physical Review Letters (2025). DOI: 10.1103/r7xz-5d9c

Comment by Dr. Krishna Kumari Challa on Monday

Air pollution may reduce health benefits of exercise

Long-term exposure to toxic air can substantially weaken the health benefits of regular exercise, suggests a new study by an international team of researchers.

The study, published in the journal BMC Medicine, analyzed data from more than 1.5 million adults tracked for more than a decade in countries including the U.K., Taiwan, China, Denmark and the United States.

The team found that the protective effect of regular exercise on people's risk of dying over a specific period—from any cause and from cancer and heart disease specifically—appeared to be reduced, but not eliminated, for those who lived in high pollution areas.

The researchers looked at levels of fine particulate matter—tiny particles known as PM_2.5 with a diameter of less than 2.5 micrometers across. These particles are so small they can get stuck in the lungs and enter the bloodstream. 

The health benefits of exercise significantly weakened, the team found, where the yearly average level of PM_2.5 was 25 micrograms per cubic meter (μg/m³) or higher. Nearly half (46%) of the world's population live in areas exceeding this threshold. 

In their section on limitations, the authors noted that the study was mostly conducted in high-income countries, so the findings might not apply to low-income countries where fine particle pollution is higher, often exceeding 50 μg/m³. Other limitations included a lack of data on indoor air quality as well as participants' diets. 

BMC Medicine (2025). DOI: 10.1186/s12916-025-04496-y

Comment by Dr. Krishna Kumari Challa on Monday

The research team was also able to demonstrate that mild inflammatory processes in the gut associated with aging further reinforce this mechanism. Inflammatory signals alter iron distribution in the cell and put strain on the metabolism. At the same time, Wnt signaling also weakens—a signaling pathway that is important for keeping stem cells active and functional.

This combination of iron deficiency, inflammation, and Wnt signaling loss acts as an "accelerator" of epigenetic drift. As a result, the aging process in the intestine can begin earlier and spread faster than previously thought.

Despite the complexity of the mechanism, the study also provides encouraging results. The researchers succeeded in slowing down or partially reversing epigenetic drift in organoid cultures—miniature intestinal models grown from intestinal stem cells—by restoring iron import or specifically activating the Wnt signaling pathway. 

Anna Krepelova et al, Iron homeostasis and cell clonality drive cancer-associated intestinal DNA methylation drift in aging, Nature Aging (2025). DOI: 10.1038/s43587-025-01021-x

Part2

Comment by Dr. Krishna Kumari Challa on Monday

Why important genes 'go quiet' as we get older

The human gut renews itself faster than any other tissue: every few days, new cells are created from specialized stem cells. However, as we get older, epigenetic changes build up in these stem cells. These are chemical markers on the DNA that act like switches, determining which genes remain active. 

The study, recently published in Nature Aging, was conducted by an international team and it shows that changes in the gut do not occur randomly. Rather, a specific pattern develops over the course of aging, which the researchers refer to as ACCA (Aging- and Colon Cancer-Associated) drift. Researchers observed an epigenetic pattern that becomes increasingly apparent with age.

  Genes that maintain the balance in healthy tissue are particularly affected, including those that control the renewal of the intestinal epithelium via the Wnt signalling pathway.  The changes described as "drifting" can be detected not only in the aging gut, but also in almost all colon cancer samples examined. This suggests that the aging of stem cells creates an environment that promotes the development of cancer. 

The fact that the drift is not evenly distributed throughout the intestine is particularly noteworthy. Each intestinal crypt—a small, tubular section of the intestinal mucosa—originates from a single stem cell. When this stem cell undergoes epigenetic changes, the entire crypt takes on these changes.   Over time, more and more areas with an older epigenetic profile develop in the tissue. Through the natural process of crypt division, these regions continuously enlarge and can continue to grow over many years. 

This explains why the intestines of older people contain a veritable patchwork of crypts that have remained young and others that have aged significantly, and why certain regions are particularly susceptible to producing more degenerated cells, which promotes cancer growth. 

But why does this drift occur? Researchers have shown that older intestinal cells absorb less iron but release more iron at the same time. This reduces the amount of available iron (II) in the cell nucleus, which serves as a cofactor for the TET (ten-eleven translocation) enzymes. These enzymes normally protect from the excess DNA methylations, but if the cell doesn't have enough iron, they can't do their job properly. Excess DNA methylations are no longer broken down.

When there's not enough iron in the cells, faulty markings remain on the DNA. And the cells lose their ability to remove these markings. This has a kind of domino effect: as the TET activity decreases, more and more DNA methylations accumulate, and important genes are switched off; they "fall silent." This can further accelerate epigenetic drift.

Part1

Comment by Dr. Krishna Kumari Challa on Monday

Phototherapy could reverse antibiotic resistance

Antimicrobial resistance is a growing global problem, linked to 4.7 million deaths in 2021, a figure that's set to nearly double by 2050. A large proportion of infections are caused by "Gram-negative" bacteria like E. coli which have tough cell walls that block the entry of drugs, meaning fewer treatment options are available. 

Many new antibiotics are improved versions of previous drugs, attacking bacteria in a similar way. But making different antibiotics from scratch is challenging and time-consuming. It's clear we need new strategies, and researchers think innovative chemistry could hold the answer. 

In their study published in the Journal of the American Chemical Society, they focused on an enzyme only found in drug-resistant bacteria, NDM-1, which breaks down commonly used 'beta-lactam' antibiotics like penicillin. 

They  designed a chemical tool, 'Ru1,' composed of a light-activated ruthenium metal complex attached to an organic molecule, or 'ligand,' that binds to NDM-1.

The metal complex is exposed to blue light, causing it to produce molecules called reactive oxygen species that cause damage to NDM-1. 

Through a series of experiments in purified proteins, the team showed that Ru1 damages NDM1's active site, blocking its ability to destroy antibiotics—and it does so a hundred times better in the light. As soon as the light is switched off, Ru1 can no longer cause damage and can be used again. 

The next step was to test if Ru1 works in live E. coli. Although Ru1 did partially inactivate NDM-1 in the live bacteria in the dark, it was thirty times more effective in the light, showing their targeted approach works .

Finally, the researchers showed that Ru1 can effectively sensitize E. coli to an antibiotic called meropenem.  At the maximum concentration tested, Ru1 increased the activity of meropenem by 53 times. Importantly, it didn't show any toxicity to human cells.

  Lars Stevens-Cullinane et al, Light-Activated Metal-Dependent Protein Degradation: A Heterobifunctional Ruthenium(II) Photosensitizer Targeting New Delhi Metallo-β-lactamase 1, Journal of the American Chemical Society (2025). DOI: 10.1021/jacs.5c12405

Comment by Dr. Krishna Kumari Challa on Monday

"If stool sticks around too long in the gut, microbes use up all of the available dietary fiber, which they ferment into beneficial short-chain fatty acids," says Johannes Johnson-Martinez, a bioengineer at ISB.

"After that, the ecosystem switches to fermentation of proteins, which produces several toxins that can make their way into the bloodstream."

Sure enough, some of these byproducts were found in these patients' blood samples. Particularly enriched was a metabolite called indoxyl-sulfate, a known product of protein fermentation that can damage the kidneys.

The team suggests the finding is potential evidence of a causal link between bowel movement frequency and overall health.

There is some hope that people can change their habits and, as a result, their health. Recent research suggests your gut microbiome can shift a lot faster than you might think.

For instance, a 2025 study from Germany, yet to undergo peer review, tracked inactive adults who began resistance training twice or three times a week. Those who gained the most strength showed changes in the makeup of their gut bacteria in just eight weeks.

These kinds of changes might help some people move out of the constipation or diarrhea categories and into a healthier bowel-movement range.

Those in the Goldilocks zone of pooping reported eating more fiber, drinking more water, and exercising more often. Their stool samples also showed high levels of bacteria associated with fermenting fiber.

A clinical trial published in 2025 by US researchers found that people with a lot of methane-producing microbes in their guts are especially efficient at turning dietary fiber into short-chain fatty acids.

This suggests that both the amount of fiber and the specific mix of microbes in an individual's gut are important, which explains why two people eating the same diet can experience different health outcomes.

Of course, everybody's found themselves at one extreme or the other at some point in their lives, after catching a stomach bug or eating too much cheese. But this study was looking at people's everyday routine, and reveals how our own version of 'normal' could hint at health issues we weren't aware of.

The research was published in the journal Cell Reports Medicine.

Part2

Comment by Dr. Krishna Kumari Challa on Monday

Your daily poop count is important

"How often do you poop?" might sound like a very personal question, but your answer could reveal quite a lot about your overall health.

A study published in July 2024 investigated how often 1,425 people went number two, and compared those stats to their demographic, genetic, and health data.

The healthiest participants reported pooping once or twice a day – a 'Goldilocks zone' of bowel movement frequency.

Pooping too often or too rarely were both associated with different underlying health issues, the team led by researchers at the Institute for Systems Biology (ISB) found.
This study shows how bowel movement frequency can influence all body systems, and how aberrant bowel movement frequency may be an important risk factor in the development of chronic diseases .
"These insights could inform strategies for managing bowel movement frequency, even in healthy populations, to optimize health and wellness

The team looked for possible associations between bowel movement frequency and these health markers, as well as other factors like their age and sex.

In general, those who reported less frequent bowel movements tended to be women, younger, and with a lower body mass index (BMI). But even accounting for these factors, people with constipation or diarrhea showed clear links to underlying health issues.

Bacteria usually found in the upper gastrointestinal tract were more common in stool samples from participants with diarrhea. Their blood samples, meanwhile, showed biomarkers associated with liver damage.

Stool samples from people with less frequent bowel movements had higher levels of bacteria associated with protein fermentation. This is a known hazard from constipation.

Part1

Comment by Dr. Krishna Kumari Challa on Monday

This Protein Reawakens Aging Brain Cells in Mice, Study Shows

A discovery by researchers from the Baylor College of Medicine in the US could lead to treatments that clear the troublesome aggregations of protein thought to play a key role in Alzheimer's disease.

Using mice bred to have a condition similar to the neurodegenerative disorder, the team found that elevated levels of a protein called Sox9  triggered specialized brain cells to go into clean-up overdrive, 'vacuuming' up plaques with increased efficiency.

In behavioral and memory tests, the treated mice also performed better, suggesting that the intervention can help protect the brain and reverse cognitive decline – a process that typically occurs in  Alzheimer's   disease as neurons are damaged and destroyed.

https://www.nature.com/articles/s41593-025-02115-w

Comment by Dr. Krishna Kumari Challa on Sunday

Microplastics pose human health risk in more ways than one

Microplastics in aquatic environments are colonized by pathogenic and antimicrobial-resistant bacteria, with polystyrene and nurdles posing higher risks due to their capacity to adsorb antibiotics and promote biofilm formation. Over 100 unique antimicrobial resistance gene (ARG) sequences were identified on microplastics, exceeding those on natural or inert substrates. These findings highlight microplastics as vectors for the spread of pathogens and ARGs, raising concerns for environmental and human health.

Emily M. Stevenson et al, Sewers to Seas: exploring pathogens and antimicrobial resistance on microplastics from hospital wastewater to marine environments, Environment International (2025). DOI: 10.1016/j.envint.2025.109944

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