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Comment by Dr. Krishna Kumari Challa on December 14, 2025 at 8:37am

Gut bacteria's hidden toxin acts as DNA glue, fueling colorectal cancer risk

Colibactin is a powerful toxin produced by Escherichia coli and other bacteria living in the human gut. This highly unstable bacterial product causes mutations in DNA that have been linked to colorectal cancer. Because it breaks down quickly, isolating and studying it has been difficult, but now scientists  have discovered exactly how colibactin attacks DNA.

Using advanced tools such as mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy, the team studied the toxin at the atomic level, as reported in a paper published in the journal Science. The scientists overcame colibactin's instability by growing toxin-producing bacteria directly next to strands of DNA in the lab. Consequently, colibactin attacked the genetic material almost as soon as it was made. 

The study authors discovered that the toxin doesn't target genetic material at random. It homes in on DNA sequences with high quantities of adenine and thymine bases. The way it damages DNA is by creating a bridge-like connection, called an interstrand cross-link (ICL), between the two strands of the DNA helix. In effect, the toxin acts like glue, binding the two strands together. This damage is permanent and prevents the cell from correctly reading or copying its DNA, which ultimately results in genetic errors that can lead to cancer.

The researchers also revealed that the damage occurs at the same place, in the minor groove. This is the narrow, shallow groove that is formed where the DNA's backbones are closest together. And the reason is the toxin has an unstable, positively charged core that is attracted to the negatively charged, AT-rich minor groove. So they fit together like a lock and key.

The research is a significant advance in our understanding of the direct link between gut microflora and cancer risk. The discovery that colibactin binds to DNA at a specific site explains the characteristic DNA mutations doctors observe in colorectal cancer patients. 

Now that scientists know the structure of the ICL bridge and the mechanism of attack, it can help them develop diagnostic tools to screen people at higher risk and design therapeutics to neutralize the unstable core. It could even inform new ways to reduce cancer risk through dietary changes or treatments that reduce the number of colibactin-producing bacteria in the gut. 

Erik S. Carlson et al, The specificity and structure of DNA cross-linking by the gut bacterial genotoxin colibactin, Science (2025). DOI: 10.1126/science.ady3571

Orlando D. Schärer, Molecular basis of DNA cross-linking by bacteria, Science (2025). DOI: 10.1126/science.aec9205

Comment by Dr. Krishna Kumari Challa on December 14, 2025 at 8:36am

Abdominal obesity and muscle loss increase the risk of death by 83% after age 50, study finds

A study by researchers concluded that the combination of abdominal fat and muscle loss increases the risk of death by 83%, compared to people without these conditions.

This combination is so dangerous that it identifies an even greater problem: sarcopenic obesity. This condition is characterized by loss of muscle mass while gaining fat throughout the body. It is a difficult condition to diagnose, and it is related to loss of autonomy and a worsening quality of life in older adults. It is also known as frailty syndrome and is associated with an increased risk of falls and other comorbidities.

Valdete Regina Guandalini et al, Can simple measures from clinical practice serve as a proxy for sarcopenic obesity and identify mortality risk?, Aging Clinical and Experimental Research (2024). DOI: 10.1007/s40520-024-02866-9

Comment by Dr. Krishna Kumari Challa on December 14, 2025 at 8:36am

Fat tissue around the heart may contribute to greater heart injury after a heart attack 

Greater epicardial adipose tissue (EAT) volume, measured by cardiovascular imaging, is independently associated with larger myocardial infarct size and greater area at risk after myocardial infarction, though not with reduced left ventricular ejection fraction. Non-invasive EAT quantification may enhance cardiovascular risk assessment beyond traditional factors.

Epicardial adipose tissue (EAT) is the layer of fat between the myocardium and the lining of the heart, directly surrounding the coronary arteries. Under certain pathological conditions, EAT releases inflammatory mediators leading to myocardial infiltration and constrictive effects. Over time, adverse remodeling of the myocardium can occur.

Researchers have now shown that patients with increased EAT volume exhibited greater acute myocardial injury following MI.

https://www.escardio.org/The-ESC/Press-Office/Press-releases/fat-ti...

Comment by Dr. Krishna Kumari Challa on December 14, 2025 at 8:36am

'Self-activation' is part of the success strategy of parasitic weeds 

Certain parasitic weeds can autonomously activate their feeding organs (haustoria) before encountering a host by producing and releasing specific substances from their seeds. This early self-activation enables rapid and effective host attachment, contributing to their persistence and difficulty of control in agriculture. The process is influenced by compounds from both host and non-host seeds, and targeting these early signaling pathways may offer new weed management strategies.

Guillaume Brun et al, Seed metabolites headstart haustoriogenesis and potentiate aggressiveness of parasitic weeds, Science Advances (2025). DOI: 10.1126/sciadv.aea1449

Comment by Dr. Krishna Kumari Challa on December 14, 2025 at 8:33am

ATI2341 also protected mice from several other types of neutrophil-induced tissue damage but, crucially, did not impair the animals' ability to fend off bacterial and fungal infections.

Aroca-Crevillén et al. A circadian checkpoint relocates neutrophils to minimize injury, Journal of Experimental Medicine (2025). DOI: 10.1084/jem.20250240

Part2

Comment by Dr. Krishna Kumari Challa on December 14, 2025 at 8:32am

Switching immune cells to 'night mode' could limit damage after a heart attack

Researchers have identified a way to suppress the daily fluctuations in the activity of key immune cells known as neutrophils.

The study, published in the Journal of Experimental Medicine (JEM), suggests that inhibiting these fluctuations could prevent neutrophils from causing excessive tissue damage during daylight hours, a phenomenon that may underlie the fact that heart attacks in the early morning are more damaging than heart attacks suffered at night.

Neutrophils provide the first line of defense against microbial infections and tissue injury. However, their efforts to promote inflammation and kill injured or infected cells can result in the death of nearby healthy cells. In fact, neutrophils have an internal clock that makes them more active and prone to cause tissue damage during the daytime.

This could help explain the long-standing observation that heart attacks in the early morning have more severe consequences than heart attacks at night, because excessive neutrophil activity contributes significantly to the size of myocardial infarcts and long-term reductions in cardiac function.

So scientists realized that targeting the neutrophil clock could provide a simple and effective means to blunt the toxic activity of these cells during myocardial infarctions, without compromising antimicrobial defense.

They performed a series of experiments to confirm that, like in humans, mice suffer greater cardiac tissue damage after a heart attack in the early morning, and that this is due to enhanced neutrophil activity at this time of the day.

Treating mice with a drug that inhabits the neutrophil clock reduced the amount of myocardial tissue damage after a heart attack and helped to preserve heart function over the following days and weeks.

The drug, known as ATI2341, targets a receptor protein on the surface of neutrophils and switches the cells into a less active mode usually only seen at night.

In their active, daytime mode, neutrophils accumulate around the edge of the initial wound caused by a heart attack, where they are poised to damage neighboring healthy cardiac tissue and extend the size of the injury. In night mode, however, neutrophils accumulate in the center of the initial wound, well away from the surrounding, healthy tissue.

Part 1

Comment by Dr. Krishna Kumari Challa on December 1, 2025 at 8:22am

Reprogrammed Human Stomach Organoids Secrete Insulin

Transplanting human gastric organoids engineered to release insulin in diabetic mice reduced hyperglycemia, offering a therapeutic avenue for type 1 diabetes.

An estimated 9.5 million people all over the world live with type 1 diabetes, wherein the beta cells in their pancreas cannot produce enough insulin to keep blood glucose in check. In the long run, elevated glucose can damage organs such as the kidneys, heart, and eyes. Over the past few decades, scientists have been studying how to generate functional insulin-secreting cells which could be transplanted into patients.

Now, researchers engineered human stomach organoids to secrete insulin. Transplanting these into diabetic mice reduced hyperglycemia. Their findings, published today in Stem Cell Reports, could help develop technologies to engineer a person’s own insulin-secreting cells for diabetes treatment.

Lu J, et al. Modeling in vivo induction of gastric insulin-secreting cells using.... Stem Cell Rep. 2025. 

Comment by Dr. Krishna Kumari Challa on December 1, 2025 at 8:22am

Scientists recruit bed bugs as crime scene sleuths

Tropical bed bugs can retain human DNA for up to 45 days after feeding, enabling recovery of phenotypic traits such as gender, eye, hair, and skin color using STR and SNP markers. Their limited mobility and tendency to remain hidden make them valuable forensic tools at crime scenes, though their usefulness is restricted to recent events within a 45-day window.

Comment by Dr. Krishna Kumari Challa on December 1, 2025 at 8:21am

Virus battles drug-resistant infections

Jumbo bacteriophages, viruses that infect bacteria, possess unique shielded compartments protecting their genetic material and can evade bacterial immune defenses. Advances in imaging have revealed these features, suggesting that engineered jumbo phages could offer effective therapies against drug-resistant bacterial infections, addressing a growing global health threat.

Thomas G. Laughlin et al, Architecture and self-assembly of the jumbo bacteriophage nuclear shell, Nature (2022). DOI: 10.1038/s41586-022-05013-4

Comment by Dr. Krishna Kumari Challa on December 1, 2025 at 8:20am

How to turn water into wine using Raisins

Sun-dried raisins submerged in water can reliably ferment into wine due to a high abundance of Saccharomyces cerevisiae on their surfaces, unlike fresh grapes. Successful fermentation was observed only with sun-dried raisins, yielding higher ethanol concentrations and a dominance of alcohol-producing yeasts. Oil-coated commercial raisins do not support this process.

https://phys.org/news/2025-11-wine-raisins.html?utm_source=nwletter...

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