Comment

Comment by Dr. Krishna Kumari Challa on March 20, 2025 at 9:09am

If helicases are nanomachines, then "ATP," or adenosine trisphosphate, is the fuel. Much like how burning gas drives the pistons of a car engine, burning ATP, the same fuel used to flex your muscles, causes the six pistons of a helicase to unwind DNA.

The study found that as ATP is consumed, it reduces physical constraints that allow the helicase to proceed along the DNA, unwinding more and more of the double strand. Thus, ATP consumption acts as a switch that increases the amount of entropy—or disorder—in the system, freeing the helicase to move along the DNA.
The helicase uses ATP not to pry DNA apart in one motion, but to cycle through conformational changes that progressively destabilize and separate the strands. ATP burning, or hydrolysis, functions like the spring in a mouse trap, snapping the helicase forward and pulling the DNA strands apart.
Among the many discoveries made by the scientists was that two helicases melt the DNA at two sites at the same time to initiate the unwinding. The chemistry of DNA is such that nanomachines move along a single DNA strand in one direction only. By binding at two sites simultaneously, the helicases coordinate so that the winding can happen in both directions with an energy efficiency unique to natural nanomachines.

 Taha Shahid et al, Structural dynamics of DNA unwinding by a replicative helicase, Nature (2025). DOI: 10.1038/s41586-025-08766-w. www.nature.com/articles/s41586-025-08766-w

Part 2

Comment by Dr. Krishna Kumari Challa on March 20, 2025 at 9:07am

Scientists see the first steps of DNA unwinding

For the first time, scientists have witnessed the very moment DNA begins to unravel, revealing a necessary molecular event for DNA to be the molecule that codes all life.

A new study published in Nature, captures the moment DNA begins to unwind, allowing for all the events that follow in DNA replication.

This direct observation sheds light on the fundamental mechanisms that allow cells to faithfully duplicate their genetic material, a cornerstone for growth and reproduction.

Using cryo-electron microscopy and deep learning to observe the helicase Simian Virus 40 Large Tumor Antigen interacting with DNA, the work  provides the most detailed description yet of the very first steps of DNA replication: 15 atomic states that describe how the enzyme helicase forces the unwinding of DNA.

The achievement is not only a milestone in helicase research, but also a milestone in observing the dynamics of any enzyme at atomic resolution.

 For DNA to replicate, the helix must first unwind and break the DNA from a double strand into two single strands.

Upon binding, helicases melt the DNA, breaking the chemical bonds holding the double helix together. They then pull the two strands apart, allowing other enzymes to complete the replication. Without this first step, no DNA can be replicated. In this way, helicases are machines or, because of their size, nanomachines.

Part 1

Comment by Dr. Krishna Kumari Challa on March 19, 2025 at 10:51am

Immediately after the two ancestral populations split, we see a severe bottleneck in one of them—suggesting it shrank to a very small size before slowly growing over a period of one million years.
This population would later contribute about 80% of the genetic material of modern humans, and also seems to have been the ancestral population from which Neanderthals and Denisovans diverged.
However, some of the genes from the population which contributed a minority of our genetic material, particularly those related to brain function and neural processing, may have played a crucial role in human evolution.
The study also found that genes inherited from the second population were often located away from regions of the genome linked to gene functions, suggesting that they may have been less compatible with the majority genetic background. This hints at a process known as purifying selection, where natural selection removes harmful mutations over time.
The fact that we can reconstruct events from hundreds of thousands or millions of years ago just by looking at DNA today is astonishing.

A structured coalescent model reveals deep ancestral structure shared by all modern humans, Nature Genetics (2025). DOI: 10.1038/s41588-025-02117-1

Part 2

Comment by Dr. Krishna Kumari Challa on March 19, 2025 at 10:41am

Genetic study reveals hidden chapter in human evolution

Modern humans descended from not one, but at least two ancestral populations that drifted apart and later reconnected, long before modern humans spread across the globe.

Using advanced analysis based on full genome sequences, researchers  have found evidence that modern humans are the result of a genetic mixing event between two ancient populations that diverged around 1.5 million years ago. About 300,000 years ago, these groups came back together, with one group contributing 80% of the genetic makeup of modern humans and the other contributing 20%.

For the last two decades, the prevailing view in human evolutionary genetics has been that Homo sapiens first appeared in Africa around 200,000 to 300,000 years ago, and descended from a single lineage. However, these latest results, reported in the journal Nature Genetics, suggest a more complex story.

For a long time, it's been assumed that we evolved from a single continuous ancestral lineage, but the exact details of our origins are uncertain. 

This new  research work  shows clear signs that our evolutionary origins are more complex, involving different groups that developed separately for more than a million years, then came back to form the modern human species.

While earlier research has already shown that Neanderthals and Denisovans—two now-extinct human relatives—interbred with Homo sapiens around 50,000 years ago, this new research suggests that long before those interactions—around 300,000 years ago—a much more substantial genetic mixing took place.

Unlike Neanderthal DNA, which makes up roughly 2% of the genome of non-African modern humans, this ancient mixing event contributed as much as 10 times that amount and is found in all modern humans.

The team's method relied on analyzing modern human DNA, rather than extracting genetic material from ancient bones, and enabled them to infer the presence of ancestral populations that may have otherwise left no physical trace. The data used in the study are from the 1000 Genomes Project, a global initiative that sequenced DNA from populations across Africa, Asia, Europe, and the Americas.
The team developed a computational algorithm called cobraa that models how ancient human populations split apart and later merged back together. They tested the algorithm using simulated data and applied it to real human genetic data from the 1000 Genomes Project.

While the researchers were able to identify these two ancestral populations, they also identified some striking changes that happened after the two populations initially broke apart.
Part 1

Comment by Dr. Krishna Kumari Challa on March 19, 2025 at 9:47am

 The mysterious 'red sprite' lightning strikes over the Himalayas

Have you ever heard of—or even seen—red lightning? These are not animated characters but real atmospheric phenomena known as electrical discharges that occur high above thunderstorms. Scientists refer to them as "red sprites," named for their jellyfish-like appearance and vivid red flashes. Now, imagine witnessing these mesmerizing displays over the world's highest mountain range—the Himalayas.

On the night of May 19, 2022, two Chinese astrophotographers, Angel An and Shuchang Dong, captured a spectacular display of over one hundred red sprites over the Himalayas. The observation site, located on the southern Tibetan Plateau near Pumoyongcuo Lake—one of the region's three sacred lakes—revealed a breathtaking celestial event.

Among the phenomena captured were dancing sprites, rare secondary jets, and the first-ever recorded case in Asia of green airglow at the base of the nighttime ionosphere, dubbed "ghost sprites." This extraordinary event attracted global attention and was widely covered by major media outlets.

A recent study published in Advances in Atmospheric Sciences by Professor Gaopeng Lu and his team at the University of Science and Technology of China sheds light on the driving force behind this grand "sprite fireworks"—lightning and thunderstorms.

By analyzing the parent lightning discharges, they discovered that the sprites were triggered by high-peak current positive cloud-to-ground lightning strikes within a massive mesoscale convective system. This suggests that thunderstorms in the Himalayan region have the potential to produce some of the most complex and intense upper-atmospheric electrical discharges on Earth.

Lacking precise timestamps for detailed analysis, the research team developed an innovative method to synchronize video time using satellite trajectories and star field analysis. This innovative approach allowed them to determine the exact occurrence times of the sprites and link them to their parent lightning discharges. One of the anonymous reviewers praised the technique, highlighting its potential as a reliable timing tool for citizen scientists contributing to scientific observations.
The study revealed that the parent lightning discharges occurred within stratiform precipitation regions of a mesoscale convective complex stretching from the Ganges Plain to the southern foothills of the Tibetan Plateau. This event recorded the highest number of sprites during a single thunderstorm in South Asia, suggesting that thunderstorms in this region possess upper-atmospheric discharge capabilities comparable to those in the U.S. Great Plains and offshore European storms.

Moreover, the findings indicate that these storms may generate even more complex discharge structures, potentially influencing atmospheric coupling processes with significant physical and chemical effects.

Hailiang Huang et al, Massive Outbreak of Red Sprites in South Asia Observed from the Tibetan Plateau, Advances in Atmospheric Sciences (2025). DOI: 10.1007/s00376-024-4143-5

Comment by Dr. Krishna Kumari Challa on March 19, 2025 at 9:19am

Antibiotic-resistant bacteria more vulnerable under body-like fluid flow conditions, study finds

Some notoriously difficult-to-treat infections may not be as resistant to antibiotics as has been thought, according to new research using a microfluidic device that more closely duplicates the fluid flow found in the body than standard cultures.

Researchers tested antibiotic agents against Pseudomonas aeruginosa, considered one of the most highly resistant pathogens. They introduced the drugs at varying rates of fluid flow and found that, while the bacteria thrived at no or low fluid flow, the antibiotics killed the bacteria at higher flow rates.

Anytime you take an antibiotic orally or by IV, it's not immediately in the place it is supposed to be. It will get there by flowing in the bloodstream. Other fluids move throughout the body as well: in the lungs, the urinary tract, the digestive tract.

So it is important to know the impact of fluid flow. By using the microfluidic technology, often used in engineering, in a biology setting, the researchers found that fluid flow is very important for antibiotic activity. 

Whether in a biology lab or a clinical lab, the standard way to study pathogenic bacteria is in plates, tubes or wells—settings not representative of the dynamics found in the body. The microfluidic devices the present group used allow for precise control of the rate of fluid flowing.

The researchers tested three different antibiotic agents against which the Pseudomonas was supposedly resistant. They saw a gradient of antibiotic activity that was dependent on the flow rate. At no to low flow, the antibiotics affected only the bacteria at the very start of the fluid track. As the flow rate increased, so did the reach of the antibiotic activity, until the entire culture sample was wiped out at the highest tested flow rates.

The findings highlight how we could do a better job of characterizing antibiotic resistance. If you get an infection, a clinician might take a sample and test it to see which drugs will work against it. But they're testing it without flow. So they may not give you a drug that actually could be effective because their tests don't show how effective the drugs are in flow conditions like in the body.

  When researchers try to develop a new drug, it's the same thing; they might be wrong in interpreting whether the drug is working or not, because the testing conditions aren't like the body.

Next, the research team plans to test other antibiotic-resistant pathogens and other antibiotic drugs in their microfluidic devices. They also hope to more deeply study the mechanisms behind why the antibiotics were more effective in flowing fluid.

That is why I wrote several times that lab conditions will be different from actual conditions. Several factors affect the outcomes and until we test all of them, we cannot say our results are hundred percent correct.

 Alexander M. Shuppara et al, Shear flow patterns antimicrobial gradients across bacterial populations, Science Advances (2025). DOI: 10.1126/sciadv.ads5005

Comment by Dr. Krishna Kumari Challa on March 18, 2025 at 8:46am

Discovery shows how cells use telomeres to avoid cancer

Cancer researchers at Children's Medical Research Institute have discovered an "unexpected mechanism" that our cells use to avoid cancer.

Telomeres are the protective caps at chromosome ends and are involved in aging and cancer. As we age, telomere length naturally decreases. Over the course of a lifetime, telomere shortening instructs aging cells to stop dividing. This normally functions as a critical barrier to stop cancer.

Most people think of telomeres as a passive entity that shorten with cell division; this is a passive fail-safe used during aging.

The new  data shows telomeres are much more active. They can acutely respond to stress and actively open up to turn on a cellular response that looks like aging. They do this to avoid cancer.

This can lead to cell cycle arrest, or death, to prevent these damaged cells with chromosome errors from dividing further. This suggests telomeres have another anti-cancer mechanism that was previously unknown.

Diana Romero-Zamora et al, A CPC-shelterin-BTR axis regulates mitotic telomere deprotection, Nature Communications (2025). DOI: 10.1038/s41467-025-57456-8

Comment by Dr. Krishna Kumari Challa on March 18, 2025 at 7:55am

Kids under eight shouldn't drink slushies, researchers warn

Children under eight should not drink slushy ice drinks containing glycerol, researchers have warned after a string of hospitalizations in the UK and Ireland.

The brightly colored drinks marketed towards children often use glycerol as a sweetener and anti-freezing agent. But high levels can be harmful, especially to children—glycerol intoxication can cause shock, low blood sugar and loss of consciousness.

In a peer-reviewed medical review published in the Archives of Disease in Childhood journal this week, researchers looked into a "recent apparent surge in cases" in the UK and Ireland, and suggested children under eight should avoid the drinks entirely. They studied the medical records of 21 children aged two to seven who needed emergency treatment after drinking slushies.

Most cases took place between 2018 and 2024 and many of the children became acutely ill within an hour, the researchers said. Most of the children lost consciousness and showed signs of high blood acidity and low sugar, while four needed brain scans and one had a seizure.

The children all recovered swiftly, the researchers said.

Food safety agencies in the two countries already advise that children aged four and under should not have slushies containing glycerol.

But the researchers said the age should be raised further.

"Younger children, especially those under eight years of age, should avoid slush ice drinks containing glycerol," they said.

"Clinicians and parents should be alert to the phenomenon, and public health bodies should ensure clear messaging."

The review's authors also said there could be cases where children have suffered less serious illness and not been taken to hospital.

 Glycerol intoxication syndrome in young children, following the consumption of slush ice drinks, Archives of Disease in Childhood (2025). DOI: 10.1136/archdischild-2024-328109

Comment by Dr. Krishna Kumari Challa on March 18, 2025 at 7:03am

Mimicry: Baby birds behaving like caterpillars to escape predators

Even hummingbird chick acts like a caterpillar to survive

Even hummingbird chick acts like a caterpillar to survive

Jay J. Falk et al, Potential caterpillar mimicry in a tropical hummingbird, Ecology (2025). DOI: 10.1002/ecy.70060

Comment by Dr. Krishna Kumari Challa on March 18, 2025 at 6:57am

Slow, silent 'scream' of epithelial cells detected for first time

It has long been thought that only nerve and heart cells use electric impulses to communicate, while epithelial cells—which compose the linings of our skin, organs and body cavities—are mute, serving mostly as protective barriers that can absorb and secrete various substances.

But  researchers  have upended the status quo by showing that epithelial cells do indeed "talk" to each other, albeit with slow electrical signals.

 The discovery, published in the Proceedings of the National Academy of Sciences, could enable new applications for everything from wearable bioelectric sensors to wound healing.

Epithelial cells do things that no one has ever thought to look for. When injured, they 'scream' to their neighbors, slowly, persistently and over surprising distances. It's like a nerve's impulse, but 1,000 times slower. 

The researchers' curiosity-driven approach, blending polymer science and biology, unveiled this hidden cellular signaling.

They used an epithelial-cell-coated chip with 60 precisely placed electrodes to eavesdrop. They grew a single layer of human epithelial cells on the chip, which detected minute electric shifts.

Using a precise laser to produce "sting" patterns of individual cells, they watched as signals rippled outward. They tracked how cells coordinated their response. "It's a slow-motion, excited conversation."

Unlike the swift neurotransmitter bursts of nerve cells, epithelial cells rely on ion flows—of calcium, especially—that produce signals that are far slower than those in nerve cells, but with similar voltages. These signals can be long-lived: The researchers observed cells that "talked" for over five hours across distances nearly 40 times their own length.

They showed that calcium ions are necessary for epithelial conversation, they have yet to test what else might contribute to the conversation. And though the immediate applications of their new discovery remain to be seen, the implications are vast. Wearable sensors, implantable devices and faster wound healing could grow from this .

Granick, Steve, Electric spiking activity in epithelial cells, Proceedings of the National Academy of Sciences (2025). DOI: 10.1073/pnas.2427123122. doi.org/10.1073/pnas.2427123122

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