Comment

Comment by Dr. Krishna Kumari Challa 1 hour ago

Psilocybin rewires brain circuits to boost fear extinction and behavioural flexibility in mice

Psilocybin, a psychedelic compound contained in some varieties of mushrooms, has recently been found to be promising for the treatment of some neuropsychiatric disorders, including depression, some anxiety disorders and post-traumatic stress disorder(PTSD). Some studies suggest that the consumption of this compound may be particularly advantageous for individuals who struggle to adapt their behavior in helpful ways when facing unexpected events or changes in their environment.

While a growing pool of research has been assessing the therapeutic benefits of psilocybin  the neural mechanisms through which it promotes long-lasting psychological changes remain poorly understood. If it does prompt greater behavioral flexibility in individuals diagnosed with some psychiatric disorders, the processes through which it does so are not yet clear.

Researchers  recently carried out a new study on mice, which was aimed at better understanding how psilocybin could increase adaptability and potentially ease symptoms of anxiety disorders or PTSD. Their findings, published in Nature Neuroscience, suggest that the compound prompts the reorganization of neural circuits in the retrosplenial cortex , a part of the brain located in the posterior region of the cerebral cortex (i.e., the outermost layer of the mammalian brain).

Researchers, in their experiments,   found that a single dose of psilocybin altered cortical ensemble turnover and oppositely modulated fear- and extinction-active neurons. Suppression of fear-active neurons and recruitment of extinction-active neurons predicted psilocybin-enhanced fear extinction.

These results suggested that psilocybin enhances behavioral flexibility by recruiting new neuronal populations and suppressing fear-active populations in the retrosplenial cortex.

Sophie A. Rogers et al, Psilocybin-enhanced fear extinction linked to bidirectional modulation of cortical ensembles, Nature Neuroscience (2025). DOI: 10.1038/s41593-025-01964-9.

Comment by Dr. Krishna Kumari Challa 21 hours ago

Next, to test mitochondrial transfer from neurons to cancer cells, the team engineered neurons to express mitochondria tagged with fluorescent markers with a novel tracking system called MitoTRACER. The system allowed researchers to monitor cancer cells after mitochondrial transfer, enabling detailed tracing of their fate during disease progression.

Direct mitochondrial transfer was observed via tunneling nanotubes, initiated by neurons towards the cancer cells. Rho-zero cancer cells regained oxidative phosphorylation and uridine-independent growth after acquiring neuronal mitochondria, confirming functional rescue.

MitoTRACER revealed that recipient cancer cells displayed enhanced respiration, higher ATP, improved redox balance, and greater resistance to oxidative and mechanical stress.

In animal models, these labeled recipient cells were significantly enriched in metastases, especially in the brain and liver, indicating that neuronal mitochondria confer a selective advantage during dissemination.

Together, these two experimental arms show that nerves both sustain tumor energetics broadly and act as direct donors of functional mitochondria, a dual mechanism that promotes cancer survival and spread.
Denervation experiments established that disrupting nerve input deprives cancer cells of essential bioenergetic capacity, reducing their invasiveness. Cancer cells that had received neuronal mitochondria more readily survived metastatic stressors such as oxidative damage and mechanical shear forces, common hurdles faced during cancer dissemination.

Gregory Hoover et al, Nerve-to-cancer transfer of mitochondria during cancer metastasis, Nature (2025). DOI: 10.1038/s41586-025-09176-8

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Comment by Dr. Krishna Kumari Challa 21 hours ago

Neurons duped into delivering mitochondria to cancer cells found fueling tumor spread

Researchers report that neurons can transfer mitochondria directly to cancer cells, enhancing their metastatic potential.

Oncologists have long suspected that tumors thrive partly by enlisting help from surrounding nerves. Pathologists studying cancer tissues have observed that tumors nestled among dense networks of nerves often grow faster and spread farther. Previous rodent and human studies demonstrated that cutting off this neural input slowed cancer growth.

Intercellular mitochondrial transfer is a recognized cellular rescue attempt where healthy donor cells revive compromised recipients by donating functional mitochondria. 

In the study, "Nerve-to-cancer transfer of mitochondria during cancer metastasis," published in Nature, researchers employed murine breast cancer models and advanced lineage-tracing reporters to test whether neurons confer metabolic assets to tumor cells via mitochondrial transfer.

Researchers performed chemical denervation by injecting botulinum neurotoxin A (BoNT/A) around breast tumors in mice. Denervation refers to the deliberate interruption of nerve supply to a tumor to chemically disable local nerve function.

The team then compared these denervated tumors to saline-injected controls using transcriptomic profiling, histopathology, and measurements of mitochondrial content.

Denervated tumors showed a marked reduction in mitochondrial load, downregulation of metabolic gene pathways (notably the tricarboxylic acid cycle), and significantly lower incidence of invasive lesions (from 55% in controls to 12% in denervated mice). These findings demonstrate that nerve inputs actively sustain tumor bioenergetics and promote progression.

part 1

Comment by Dr. Krishna Kumari Challa 21 hours ago

This research provides a novel twist on prior studies of the effects of high-altitude living. Prior studies have mostly focused on adaptation by gaining new functions or traits to cope with harsh environments, while this study shows that animals can also lose certain abilities. These understudied mechanisms of maladaptation and trait loss may have future implications for evolutionary biology and medicine.

 Allie M. Graham et al, Convergent reduction of olfactory genes and olfactory bulb size in mammalian species at altitude, Current Biology (2025). DOI: 10.1016/j.cub.2025.05.061

Part 2

Comment by Dr. Krishna Kumari Challa 21 hours ago

Animals living at higher elevations found to have decreased sense of smell

A recent study published in Current Biology has found that animals living at elevations of 1,000 meters and higher have a reduction in genes related to smell and a smaller olfactory bulb than similar low-altitude species.

The researchers screened the genomes of 27 different species of animals living in high-altitude environments, as well as their low-altitude relatives. A wide range of mammal types was studied, including monkeys, goats, llamas and guinea pigs. Both domesticated and wild mammals were included.

Scientists found a 23% reduction in genes related to smell and an average of an 18% size reduction of the olfactory bulb, a kind of smell processing center located in the brain. These evolutionary changes appear to be specific to smell. No changes were found in the genes related to pheromone and taste detection.

Environmental differences at high altitudes include thinner, drier and colder air, which can lead to difficulties in breathing, increased nasal congestion and hypoxia—low levels of oxygen in the body. These conditions also make it harder for scent molecules to travel—meaning there are fewer available scents for animals to detect in the air.

Although the exact mechanism is still unclear, the reduced sense of smell may be related to the reduction of available scents and to nasal inflammation, which causes additional difficulties in picking up scents. Over time, these issues may have led to mountain-dwelling animals evolving a worse sense of smell, but possibly compensating with better  other senses.

The study also compared the genomes of human communities at high and low altitudes. Researchers studied the genomes of Tibetans, who were estimated to have established their mountain-dwelling communities at altitudes above 3,000 meters sometime between 9,000 and 30,000 years ago. These were compared with the genomes of the low-altitude Han Chinese populations.

Interestingly, no olfactory changes were found in human populations. Researchers posit that this may be due to the continued mixing of lowland and highland populations, or because there may not have been enough generations for the genetic changes to occur yet.

Part 1

Comment by Dr. Krishna Kumari Challa 22 hours ago

Biases shape how people mentally represent social ties in their community, families, relatives and social networks, study suggests.

Throughout the course of their lives, humans are known to build social ties with various other individuals in their community. Past neuroscience and psychology studies suggest that as humans form bonds with others, they also mentally represent them in their minds, creating internal maps that outline the relationships between different members of their community.

Researchers carried out a study aimed at better understanding how people mentally represent social networks, using data collected from residents of 82 villages.

Their findings, published in Nature Human Behaviour, uncovered some biases in people's mental representation of connections between others, especially between people who belong to the same family and close community groups.

People not only form social networks, they construct mental maps of them. 

The results of the analyses carried suggest that people's mental representations of the connections between people around them are flawed. Specifically, they found that people often overestimate the closeness of other people's connections, especially family ties.

Many individuals believed that family members spent more time with each other than they did, while friendships and non-family ties appeared to be more accurately represented in their internal "maps." Moreover, people's judgements about others' social ties appeared to be more accurate when these others shared their same religion or had similar levels of wealth. Interestingly, the researchers also found that middle-aged, well-educated and well-connected people internally represented the connections between others more accurately.

Overall, people inflate the number of connections in their networks and exhibit varying accuracy and bias, with implications for how people affect and are affected by the social world.

The findings gathered by this team of researchers shed new light on how people internally map ties within their community and on the biases that can reduce the accuracy of their mental representations. 

Eric Feltham et al, Cognitive representations of social networks in isolated villages, Nature Human Behaviour (2025). DOI: 10.1038/s41562-025-02221-6.

Comment by Dr. Krishna Kumari Challa 22 hours ago

Certain species of microbe found in the human gut can absorb PFAS

PFAS (perfluoroalkyl and polyfluoroalkyl substances) can't be avoided in the modern world. These man-made chemicals are in many everyday items, including waterproof clothing, non-stick pans, lipsticks and food packaging, used for their resistance to heat, water, oil and grease. But because they take thousands of years to break down, they are accumulating in large quantities in the environment—and in our bodies.

There are over 4,700 PFAS chemicals in widespread use. Some get cleared out of the body in our urine in a matter of days, but others with a longer molecular structure can hang around in the body for years.

PFAS have been linked with a range of health issues including decreased fertility, developmental delays in children, and a higher risk of certain cancers and cardiovascular diseases.

Scientists  have identified a family of bacterial species, found naturally in the human gut, that absorb various PFAS molecules from their surroundings. When nine of these bacterial species were introduced into the guts of mice to 'humanize' the mouse microbiome, the bacteria rapidly accumulated PFAS eaten by the mice, which were then excreted in feces.

Certain species of human gut bacteria have a remarkably high capacity to soak up PFAS from their environment at a range of concentrations, and store these in clumps inside their cells. Due to aggregation of PFAS in these clumps, the bacteria themselves seem protected from the toxic effects.

The researchers also found that as the mice were exposed to increasing levels of PFAS, the microbes worked harder, consistently removing the same percentage of the toxic chemicals. Within minutes of exposure, the bacterial species tested soaked up between 25% and 74% of the PFAS.

The results are the first evidence that our gut microbiome could play a helpful role in removing toxic PFAS chemicals from our body—although this has not yet been directly tested in humans.

The researchers plan to use their discovery to create probiotic dietary supplements that boost the levels of these helpful microbes in our gut, to protect against the toxic effects of PFAS.

The results are published in the journal Nature Microbiology.

 Human gut bacteria bioaccumulate per- and polyfluoroalkyl substances, Nature Microbiology (2025). DOI: 10.1038/s41564-025-02032-5

Comment by Dr. Krishna Kumari Challa 23 hours ago

Analysis of the tumor microenvironment revealed no differences in immune cell populations between groups. In a cohort of patients with colorectal cancer, higher serum concentrations of primary bile acids correlated with shorter time to metastasis. This pinpointed dramatic alterations in bile acid circulation following RYGB surgery as the likely key factor inhibiting tumor progression and metastasis.

Further exploration revealed that gut microbiome alterations or immune system changes were not involved in this observed anticancer effect, leaving a reduced-primary/ elevated-secondary bile-acid profile as the only distinguishable change.
Researchers think that this altered bile acid metabolism of increased secondary bile acid and decreased primary bile acid contributes to reduced tumor growth and metastasis, although the precise mechanisms are still unknown.

Claudia Lässle et al, Metabolic surgery reduces CRC disease progression through circulating bile acid diversion, Science Translational Medicine (2025). DOI: 10.1126/scitranslmed.ads9705

Elizabeth R. M. Zunica et al, Bile diversion underlies Roux-en-Y antitumor benefits, Science Translational Medicine (2025). DOI: 10.1126/scitranslmed.adx3814

Part 2

Comment by Dr. Krishna Kumari Challa 23 hours ago

Rerouted bile acid thwarts tumor spread in colorectal cancer mouse model

Research  has found that bile acid diversion in Roux-en-Y gastric bypass (RYGB) reduces colorectal tumor growth and metastasis independent of weight loss, potentially reshaping future cancer treatment approaches.

More than 2 billion adults worldwide are now overweight or obese, a condition marked by chronic low-grade inflammation and metabolic disruption that can promote tumor growth, increasing the risk of developing at least 15 types of cancer.

Previous research has focused on how losing weight with RYGB reshapes cancer outcomes, leaving unanswered questions about biological mechanisms behind RYGB's anticancer correlation.

In the study, "Metabolic surgery reduces CRC disease progression through circulating bile acid diversion," published in Science Translational Medicine, researchers developed a combined mouse model of obesity and colorectal cancer to determine whether bile acid diversion after gastric bypass surgery reduces tumorigenesis and metastasis independent of weight loss.

In the experiments conducted by researchers, mice that underwent Roux-en-Y gastric bypass developed primary colorectal tumors that were significantly smaller and exhibited almost no liver metastases compared with sham-operated controls. Even when researchers extended tumor development periods to allow increased tumor size, metastases remained disproportionately low in RYGB mice, suggesting that metabolic changes, rather than weight loss alone, drive this anticancer effect.

When bile acid diversion was achieved by cholecysto-intestinal shunt alone, similar suppression of tumor growth and metastasis occurred. Circulating bile acids in gastric bypass animals shifted toward reduced primary bile acids and elevated secondary bile acids, a pattern absent in diet-restricted controls.

Fecal microbiome composition remained largely unchanged after bile diversion, and transplantation of microbiota from treated mice into high-fat diet recipients did not confer anticancer effects.

Part 1

Comment by Dr. Krishna Kumari Challa yesterday

In the study, "Reactivation of mammalian regeneration by turning on an evolutionarily disabled genetic switch," published in Science, researchers conducted comparative genomic analyses of regenerative mammals, rabbits, goats, and African spiny mice, and nonregenerative mice and rats.

Analyzing ear pinna injury recovery in these mammals, researchers used single-cell RNA sequencing, spatial transcriptomic profiling, bulk RNA sequencing, ChIP-seq, ATAC-seq, and Micro-C to identify gene activity differences in wound-induced fibroblasts, specialized cells crucial to tissue regeneration.
Genetic analysis identified regulatory elements required for regeneration after injury that have become inactive in nonregenerative species. Reactivation of this genetic switch induced regeneration of damaged structures, and skipping the genetic mechanism by supplying the retinoic acid worked even better.

Weifeng Lin et al, Reactivation of mammalian regeneration by turning on an evolutionarily disabled genetic switch, Science (2025). DOI: 10.1126/science.adp0176

Part 2

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