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Comment by Dr. Krishna Kumari Challa 11 hours ago

Does the cold really 'seep into your bones?'
Bones themselves do not directly sense cold, as they lack temperature-sensitive receptors found in skin. However, nerves in the periosteum, the bone’s outer layer, can detect temperature changes and mechanical strain, potentially causing pain. Prolonged cold exposure may reduce bone density and thickness. Cold also stiffens joints, tendons, and ligaments, and low vitamin D in winter increases pain sensitivity.

https://theconversation.com/does-the-cold-really-seep-into-your-bon...

Comment by Dr. Krishna Kumari Challa 11 hours ago

In bright outdoor light, the pupil constricts to protect the eye while still allowing ample light to reach the retina. When people focus on close objects indoors, such as phones, tablets, or books, the pupil can also constrict, not because of brightness, but to sharpen the image. In dim lighting, this combination may significantly reduce retinal illumination
According to this mechanism, myopia develops when poor retinal illumination fails to generate robust retinal activity because the light sources are too dim and pupil constriction is too excessive at short viewing distances. Conversely, myopia does not develop when the eye is exposed to bright light and the pupil constriction is regulated by image brightness instead of viewing distance.

The new study demonstrates that negative lenses reduce retinal illumination by constricting the pupil through a process known as accommodation (i.e., an accommodative increase in the lens power of the eye when focusing on images at short distances). Such pupil constriction becomes stronger when accommodation is increased by shortening viewing distance or wearing excessively-strong negative lenses.

Moreover, pupil constriction becomes even stronger when lens accommodation is sustained for prolonged periods of time (e.g., tens of minutes), and even stronger when the eye becomes myopic. The study also demonstrates additional myopia disruptions of eye turning with accommodation and eye-blink efficacy at constricting the pupil.
If proven correct, the mechanism proposed could lead to a paradigm shift in our understanding of myopia progression and control. According to this mechanism, myopia can be controlled by exposing the eye to safe bright light levels under limited accommodative pupil constriction.

Accommodative pupil constriction can be limited by reducing accommodation strength with lenses (multifocal or contrast-reduction), blocking directly the muscles driving pupil constriction (atropine drops), or by simply spending time outdoors without engaging accommodation (looking at far distances).

Perhaps most importantly, the new mechanism predicts that any approach to myopia control will fail if the eye is exposed to excessive accommodation indoors under low light for prolonged periods of time.

Human accommodative visuomotor function is driven by contrast through ON and OFF pathways and is enhanced in myopia, Cell Reports (2026). DOI: 10.1016/j.celrep.2026.116938. www.cell.com/cell-reports/full … 2211-1247(26)00016-1

Part 2

Comment by Dr. Krishna Kumari Challa 11 hours ago

Myopia is driven by how we use our eyes indoors, new research suggests

For years, rising rates of myopia—or nearsightedness—have been widely attributed to increased screen time, especially among children and young adults. But new research by scientists suggests the story may be more complicated—and more human.

In a new study published in Cell Reports, researchers propose that myopia may be driven less by screens themselves and more by a common indoor visual habit: prolonged close-up focus in low-light environments, which limits how much light reaches the retina.

Myopia (nearsightedness) is a visual disease that blurs vision at far distance and is becoming a world epidemic, affecting nearly 50% of young adults in the United States and Europe and close to 90% in parts of East Asia. While genetics play an important role, rapid increases over just a few generations suggest environmental factors are also critical.

The findings suggest that a common underlying factor may be how much light reaches the retina during sustained near work—particularly indoors.

Myopia progression is linked to prolonged near work in dim indoor lighting, which reduces retinal illumination due to excessive pupil constriction. This mechanism may unify how various factors—such as time outdoors, lens use, and atropine—affect myopia. Effective control likely requires bright light exposure and limiting accommodative pupil constriction during near tasks.

The disease can be induced in animal models with visual deprivation or negative lenses, and the two induction processes are thought to involve different neuronal mechanisms.

Clinicians also control myopia progression with a variety of approaches that are thought to engage multiple mechanisms (multifocal lenses, ophthalmic atropine, contrast-reduction, promoting time outdoors, and others). Scientists at the State University of New York (SUNY) College of Optometry propose a unifying neuronal mechanism in their article to explain all current approaches to myopia induction and control.

The research offers a new hypothesis that could help explain a long-standing puzzle in vision science—why so many seemingly different factors, from near work and dim indoor lighting to treatments like atropine drops, multifocal lenses, and time spent outdoors, all appear to influence myopia progression.

Part 1

Comment by Dr. Krishna Kumari Challa 12 hours ago

 Rescuing Antibiotics?

Comment by Dr. Krishna Kumari Challa 12 hours ago

Not all humans are 'super-scary' to wildlife, animal behaviour study suggests
Humans have climbed to the top of the food chain by skillfully hunting, trapping, and fishing for other animals at scales that far exceed other predators, altering how the animals behave and earning the tag of a "super-predator." But a new study led by the Center for Ecological Sciences, Indian Institute of Science (IISc), suggests that there is a bit more nuance to this idea. While animals clearly respond with fear to humans who hunt or kill, they are far less consistent in how they react to non-lethal human presence.

Zoos and eco-tourist spots? YES!

Wild animals show strong fear responses to lethal human activities like hunting, becoming more vigilant and reducing foraging, but react less consistently to non-lethal human presence. Human structures can sometimes decrease animal vigilance by providing perceived refuges. These behavioural changes influence survival, reproduction, and ecosystem dynamics, highlighting the need for nuanced conservation strategies.
A comprehensive meta-analysis, published in Ecology Letters, analyzes three decades of research on how wild animals change their behavior in response to different types of human interactions. The study examined behavioural shifts in foraging, vigilance, and movement across species and ecosystems to look into whether humans are always super-scary.

"The short answer is: no, not always"
Researchers found strong evidence that lethal humans such as hunters and fishers are indeed perceived as threatening. Animals in areas exposed to lethal humans tend to be more vigilant and spend less time foraging. In contrast, responses to non-lethal humans such as tourists or researchers are weaker and more variable.
The study's findings broadly support the "risk allocation hypothesis," which suggests that animals adjust their behaviour based on how intense and predictable a threat is. When danger is high and consistent, animals stay cautious. When risk is low or predictable, they can afford to relax.
Beyond individual behaviour, the researchers point to a bigger picture. Changes in fear and behaviour can cascade through ecosystems, altering grazing, predation, and ecological balance.

Shawn Dsouza et al, Are Human Super‐Predators Always Super‐Scary? A Meta‐Analysis of Wild Animal Behavioural Responses to Human Interactions, Ecology Letters (2025). DOI: 10.1111/ele.70287

Comment by Dr. Krishna Kumari Challa 12 hours ago

There is a real benefit to having a fuller picture of natural selection, particularly in medicine and agriculture. The role that widespread antibiotic use plays in shaping a bacterial arms race is a well-known example.

Another example involves chickens. In one famous study, the agricultural scientist William Muir focused on selecting for egg productivity of hens housed in battery cages. In one experiment, he selected the most productive hen within each cage to breed the next generation of hens (within-group selection). The result? A hyper-aggressive strain of hens that achieved their productivity at the expense of others, resulting in a decline in productivity at the cage level.

In a parallel experiment, Muir selected the most productive cages and used all the hens within the cages to breed the next generation of hens (group-level selection). The result? A docile strain of hens that didn't interfere with each other and achieved a 160% increase in productivity at the cage level in five generations. Based on this and other experiments, group-level selection has become standard practice in animal and plant breeding.

We can also apply the theory to ourselves, keeping Muir's chicken experiments in mind: Are we creating situations that reward competitive or even selfish behaviors? Consider a classroom that grades students on how many questions they ask, penalizing those who are quiet or slow to raise their hands. In that case, the class has selected for rapid responders rather than innovators or deep thinkers

Abundant empirical evidence of multilevel selection revealed by a bibliometric review, Frontiers in Ecology and Evolution (2026). doi.org/10.3389/fevo.2026.1752597

Part 3

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Comment by Dr. Krishna Kumari Challa 12 hours ago

Imagine that there are two human tribes. In one, members are solely focused on their individual success. In the other, members are willing to sacrifice themselves for the good of the whole; however, this altruism may cost them time and resources that they could expend on their own children and personal survival.

Which tribe is more likely to survive a crisis, such as an attack from another group? The second.
Paradoxically, the willingness for an individual to sacrifice for the group can lead to better survival outcomes. That doesn't mean that everyone in a group will become self-sacrificing, but that groups with self-sacrificing individuals may have a survival advantage.
To take a broader view, individuals not only live in communities but are communities. We are composed of trillions of cells, which comprise our tissues and organs, along with the bacteria in our microbiome and the viruses that afflict us. We live in families, neighborhoods, and countries, as well as ecosystems that bring us into contact with other species.

Every single one of these systems can change over time in response to stimuli, shifting and adapting in response to one another. Groupings can also influence individual success; consider, for example, the case of a family struggling with systemic poverty, or the impact of a troubled neighborhood on the individuals within it.Cancer is another interesting example, as are viral illnesses. On one hand, cancer cells no longer cooperate with the rest of the body, subverting the communal good for their individual benefit. But the situation isn't so cut-and-dry.

"In some cases, cancer cells act as a cooperative group in their own right; the ways they spread are strategic. You can also get competition between diseases for host resources
But what happens within a host is not the whole story; the host's environment is critical, too. If a communicable disease exists in a host population with frequent and predictable contacts, rapid growth with damage to a host may evolve, because this will not stop the host from passing it on.

However, such diseases would soon die out in populations of more isolated individuals; in the second scenario, more benign versions would have the advantage, because longer surviving hosts would give the host—and its virus or bacteria—time to find another host. Thus, selection within hosts may favor disease organisms that reproduce faster, but selection between the groups of disease organisms defined by each host may be in the exact opposite direction.
Multilevel selection complicates the picture because you have to consider all the places where selection could be occurring, and it's possible that selection on one level is headed in a different direction than selection on another level
Part 2

Comment by Dr. Krishna Kumari Challa 12 hours ago

Beyond 'survival' of fittest: Evolution works in teams
Natural selection operates at multiple levels of biological organization, not just at the individual level. Empirical evidence from diverse species demonstrates that traits can be favoured or suppressed through both individual and group-level selection, sometimes in opposing directions. Recognizing multilevel selection provides a more comprehensive understanding of evolutionary processes and has practical implications in fields such as medicine and agriculture.
The common view of natural selection is based solely on the individual: A trait allows an organism to out-compete its rivals and is thus passed down to its offspring. To suggest otherwise can provoke the ire of certain segments of the scientific community.
But a bibliometric review of 280 scientific studies shows that natural selection can occur on multiple levels of biological organization simultaneously, and not just in social species.
The idea of looking at selection at multiple levels is to measure whether a trait is adaptive for individuals within a group. And does the frequency or existence of that trait within a group change the way the group functions in comparison with other groups?
The studies examined by the researchers spanned more than a century, covering everything from viruses to human beings. All attempted to account for multilevel selection (MLS), which provides a broader view of natural selection than individual benefit.
Why does multilevel selection remain controversial? Scientific culture. Since the 1960s, key scientists have observed that claims of group benefits weren't subject to rigorous measurement and shouldn't be taken seriously. Some scientists openly banned discussion of group selection in their classrooms, calling it naïve; others claimed that it was exceedingly rare or another term for kin selection.
If you measure the average increase in the frequency of a trait over generations and then say it's favoured by natural selection, you're not wrong
But what's the mechanism for the slow increase in that trait over here and the rapid increase over there?
If you had looked at different levels, you might see that group competition is more important in one place, or cooperation within groups in another.
Part 1

Comment by Dr. Krishna Kumari Challa 17 hours ago

SC65A.3 is the first Psychrobacter strain for which resistance to certain antibiotics—including trimethoprim, clindamycin, and metronidazole—was found. Those antibiotics are used to treat UTIs, infections of lungs, skin, or blood, and the reproductive system. SC65A.3's resistance profile suggests that strains capable of surviving in cold environments could act as reservoirs of resistance genes, which are specific DNA sequences that help them survive exposure to drugs.
Bacterial strains like the one examined here hold both a threat and a promise. "If melting ice releases these microbes, these genes could spread to modern bacteria, adding to the global challenge of antibiotic resistance.
On the other hand, they produce unique enzymes and antimicrobial compounds that could inspire new antibiotics, industrial enzymes, and other biotechnological innovations.
In the Psychrobacter SC65A.3 genome, the researchers found almost 600 genes with unknown functions, suggesting a yet untapped source for discovering novel biological mechanisms. Analysis of the genome also revealed 11 genes that are potentially able to kill or stop the growth of other bacteria, fungi, and viruses.
These ancient bacteria are essential for science and medicine.

First genome sequence and functional profiling of a Psychrobacter SC65A.3 preserved in 5,000-year-old cave ice: frominsights into ancient resistome, to antimicrobial potential and enzymatic activities, Frontiers in Microbiology (2026). DOI: 10.3389/fmicb.2025.1713017

Part 2

Comment by Dr. Krishna Kumari Challa 17 hours ago

The Universe throws surprises at us all the time!

Bacterial strain from 5,000-year-old cave ice shows resistance against 10 modern antibiotics

Bacteria have evolved to adapt to all of Earth's most extreme conditions, from scorching heat to temperatures well below zero. Ice caves are just one of the environments hosting a variety of microorganisms that represent a source of genetic diversity that has not yet been studied extensively. Now, researchers tested antibiotic resistance profiles of a bacterial strain that until recently was hidden in a 5,000-year-old layer of ice of an underground ice cave—and found it could be an opportunity for developing new strategies to prevent the rise of antibiotic resistance and study how resistance naturally evolves and spreads. They reported their discovery in Frontiers in Microbiology.

The Psychrobacter SC65A.3 bacterial strain isolated from Scarisoara Ice Cave, despite its ancient origin, shows resistance to multiple modern antibiotics and carries over 100 resistance-related genes. But it can also inhibit the growth of several major antibiotic-resistant 'superbugs' and showed important enzymatic activities with important biotechnological potential.

Psychrobacter SC65A.3 is a strain of the genus Psychrobacter, which are bacteria adapted to cold environments. Some species can cause infections in humans or animals. Psychrobacter bacteria have biotechnological potential, but the antibiotic resistance profiles of these bacteria are largely unknown.

Studying microbes such as Psychrobacter SC65A.3 retrieved from millennia-old cave ice deposits reveals how antibiotic resistance evolved naturally in the environment, "long before modern antibiotics were ever used".

The team drilled a 25-meter ice core from the area of the cave known as the Great Hall, representing a 13,000-year timeline. To avoid contamination, the ice fragments taken from the core were placed in sterile bags and kept frozen on their way back to the lab. There, the researchers isolated various bacterial strains and sequenced their genome to determine which genes allow the strain to survive in low temperatures and which confer antimicrobial resistance and activity.

They tested for resistance of the SC65A strain against 28 antibiotics from 10 classes that are routinely used to or reserved for treating bacterial infections, including antibiotics that have previously been identified to possess resistance genes or mutations that give them the ability to resist drug effects. This way, they could test whether predicted mechanisms translated into measurable resistance.

The 10 antibiotics they found resistance to are widely used in oral and injectable therapies used to treat a range of serious bacterial infections in clinical practice.

Diseases such as tuberculosis, colitis, and UTIs can be treated with some of the antibiotics that the researchers found resistance to, including rifampicin, vancomycin, and ciprofloxacin.

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