Comment

Comment by Dr. Krishna Kumari Challa on Wednesday

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 on Wednesday

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 on Tuesday

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

Comment by Dr. Krishna Kumari Challa on Tuesday

Switching on a silent gene revives tissue regeneration in mice

Researchers recently discovered that switching on a single dormant gene enables mice to regenerate ear tissue.

Some vertebrates such as salamanders and fish can regenerate complex tissue structures with precision. A lost limb can be regrown, a damaged heart or eye can be repaired. Salamanders are so remarkable at reconstructing damaged tissues that even a spinal cord injury with severed neural motor connectivity can be restored.

Mammals occasionally showcase the ability to regenerate. Deer antlers and goat horns are examples of living tissue regeneration. Mice can regrow fingertips if they are lost. A healthy human liver can experience up to 70% loss of tissue and regrow to near full size within several weeks.

However, for the most part, mammals have seemingly replaced the ancient capacity for tissue regeneration with scarring, a trade-off that increases immediate survival of an injury by closing and sealing the wound.

Ear tissue punch regeneration has previously been studied in specific strains of Murphy Roths Large mice that have the ability to close 2-mm ear punches with scar-free regeneration. They can regenerate cartilage, dermis, epidermis, hair follicles, and even nerves in the ear tissue, and have shown some capacity to repair heart damage as well. Rabbits too have this ability to regenerate holes in ear tissue, suggesting that the capacity may have been shared by a common ancestor.

Rabbits and mice are related species that share a common ancestor around 90 million years ago which had previously diverged from the human primate ancestor around the same time. Millions of years of separate evolution have left the regeneration gene itself intact, but rewired its expression, extinguishing an ancestral regenerative response in most rodents that a few mice and the rabbit lineage still deploy.

Part 1

Comment by Dr. Krishna Kumari Challa on Tuesday

AI is learning to lie, scheme, and threaten its creators

The world's most advanced AI models are exhibiting troubling new behaviors—lying, scheming, and even threatening their creators to achieve their goals.

In one particularly jarring example, under threat of being unplugged, Anthropic's latest creation Claude 4 lashed back by blackmailing an engineer and threatened to reveal an extramarital affair.

Meanwhile, ChatGPT-creator OpenAI's o1 tried to download itself onto external servers and denied it when caught red-handed.

These episodes highlight a sobering reality: more than two years after ChatGPT shook the world, AI researchers still don't fully understand how their own creations work.

Yet the race to deploy increasingly powerful models continues at breakneck speed.

This deceptive behavior appears linked to the emergence of "reasoning" models—AI systems that work through problems step-by-step rather than generating instant responses.

O1 was the first large model where developers saw this kind of behaviour.

These models sometimes simulate "alignment"—appearing to follow instructions while secretly pursuing different objectives.

For now, this deceptive behavior only emerges when researchers deliberately stress-test the models with extreme scenarios.

The concerning behavior goes far beyond typical AI "hallucinations" or simple mistakes.

Users report that models are "lying to them and making up evidence".This is not just hallucinations. There's a very strategic kind of deception.

But current regulations aren't designed for these new problems.

Source: News Agencies

https://techxplore.com/news/2025-06-ai-scheme-threaten-creators.htm...

Comment by Dr. Krishna Kumari Challa on Tuesday

Individual neurons in amygdala and hippocampus encode visual features that help recognize faces

Humans are innately capable of recognizing other people they have seen before. This capability ultimately allows them to build meaningful social connections, develop their sense of identity, better cooperate with others, and identify individuals who could pose a risk to their safety.

Most studies  so far suggest that the identity of others is encoded by neurons in the amygdala and hippocampus, two brain regions known to support the processing of emotions and the encoding of memories, respectively.

Based on evidence collected in the past, researchers have concluded that neurons in these two brain regions respond in specific ways when we meet a person we are acquainted with, irrespective of visual features (i.e., how their face looks).

A recent paper published in Nature Human Behaviour, however, suggests that this might not be the case, and that individual neurons in the amygdala encode and represent facial features, ultimately supporting the identification of others.

Across four experiments (3,581 neurons from 19 neurosurgical patients over 111 sessions), researchers demonstrated a region-based feature code for faces, where neurons encode faces on the basis of shared visual features rather than associations of known concepts, contrary to prevailing views.

Feature neurons encode groups of faces regardless of their identity, broad semantic categories or familiarity; and the coding regions (that is, receptive fields) predict feature neurons' response to new face stimuli.

Together, these results reveal a new class of neurons that bridge perception-driven representation of facial features with mnemonic semantic representations, which may form the basis for declarative memory.

Runnan Cao et al, Feature-based encoding of face identity by single neurons in the human amygdala and hippocampus, Nature Human Behaviour (2025). DOI: 10.1038/s41562-025-02218-1.

Comment by Dr. Krishna Kumari Challa on June 28, 2025 at 1:12pm

This breakthrough paves the way towards programmable gene expression, offering the ability to precisely control gene activity in space and time. The findings not only deepen our understanding of developmental biology but may inform new therapeutic strategies targeting the non-coding genome.
Such approaches could one day enable treatments that selectively adjust gene expression in specific tissues, with implications for diseases caused by gene misregulation.

A dual enhancer-attenuator element ensures transient Cdx2 expression during mouse posterior body formation, Developmental Cell (2025). DOI: 10.1016/j.devcel.2025.06.006. www.cell.com/developmental-cel … 1534-5807(25)00361-2

Part 2

Comment by Dr. Krishna Kumari Challa on June 28, 2025 at 1:11pm

Scientists reveal how diverse cell types are produced in developing embryos

A team of scientists has uncovered a previously unknown mechanism that controls how genes are switched "on" and "off" during embryonic development. Their study sheds light on how diverse cell types are produced in developing embryos.

The research is published in Developmental Cell.

All cells contain the same DNA but must turn specific genes '"on" and "off"—a process known as gene expression—to create different body parts. The cells in your eyes and arms harbor the same genes but "express" them differently to become each body part.
The work focused on the gene Cdx2. The duration of Cdx2 expression helps to determine where and when a cell produces spinal cord progenitors. The researchers wanted to understand what processes control this brief window.

The team discovered a DNA element they termed an "attenuator," which reduces gene expression in a time and cell type-specific manner—unlike enhancers or silencers, other types of DNA elements that broadly switch genes on or off.

By altering this element, they could tune how long or how strongly Cdx2 was expressed, effectively acting like a "genetic dimmer switch." Disrupting the "switch" in mouse embryos also confirmed its essential role in shaping the developing body plan.

Part 1

Comment by Dr. Krishna Kumari Challa on June 28, 2025 at 1:08pm

Plants, food and the environment also have microbiomes. For example, soil microbes help plants grow by cycling nutrients and fermented foods such as yogurt contain beneficial bacteria that support gut health. Environmental microbiomes, such as those in the Arctic permafrost, play vital roles in regulating climate by controlling greenhouse gas emissions.

Microbiomes are being threatened by human activities that disrupt their natural balance, according to research.

 In humans, the overuse of antibiotics, cesarean sections and formula feeding can reduce the diversity of gut microbes, leading to increased risks of allergies, autoimmune diseases and metabolic disorders. In food, the excessive use of preservatives and additives can harm beneficial microbes.

The microbiome is under big threat, a threat that is in many ways analogous to climate change. Human activities are depleting our microbiome, and there's lots of evidence of that.

For plants, unsustainable agricultural practices, such as heavy pesticide use, can destroy soil microbiomes essential for nutrient cycling and plant health. Environmental microbiomes are affected by pollution, climate change and habitat destruction, which can lead to the loss of microbes that regulate greenhouse gas emissions and maintain ecosystem stability.

The idea of the initiative is to support efforts to identify healthy microbes, store them and freeze them before they disappear.

It is a long term project  and maybe 100 years from now, having saved these microbes could prevent a major disaster.

 Safeguarding Earth's microbial heritage for future generations: focus on the Microbiota Vault Initiative, Nature Communications (2025). www.nature.com/articles/s41467-025-61008-5

Part 2

Comment by Dr. Krishna Kumari Challa on June 28, 2025 at 1:08pm

'Microbial Noah's Ark' ramps up to save Earth's invisible life forms

A global effort to create a "microbial Noah's Ark" to preserve the world's diverse collection of healthy microbes before they disappear is now entering an active growth phase.

In a perspective article published in Nature Communications, a team of 25 scientists involved in the formation of the Microbiota Vault Initiative reported their successes and also laid out an ethical framework to ensure equitable collaboration and depositor sovereignty. This set of principles is designed to guide the initiative in its mission to safeguard microbial diversity for future generations.

The announcement, which coincides with World Microbiome Day on June 27, marks a significant step forward in a global effort. Scientists founding the initiative in 2018 were inspired by The Seed Vault within the Arctic Circle in Svalbard, Norway, where seeds collected worldwide are safeguarded to ensure the preservation of genetic diversity in the event of a global crisis.

The Microbiota Vault Initiative represents a proactive effort to protect and preserve the microbial life that is essential for the health of our planet and its inhabitants.

Microbes—tiny living organisms such as bacteria, viruses and fungi—exist everywhere, including in our bodies, where they form communities known as microbiomes. Recent research has highlighted the crucial role of "good microbes" in maintaining human health by aiding digestion, bolstering the immune system and protecting against harmful invaders.

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