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Comment by Dr. Krishna Kumari Challa on September 19, 2024 at 8:25am

"Scuba-diving'' lizards use bubble to breathe underwater and avoid predators

Presenting the world's smallest (and scrappiest) scuba diver: A species of semi-aquatic lizard produces a special bubble over its nostrils to breathe underwater and avoid predators, according to new research.

Water anoles is a type of semi-aquatic lizard found in the tropical forests of southern Costa Rica.

They can stay underwater for a really long time. We also know that they're pulling oxygen from this bubble of air.

“Scuba diving” lizard can stay underwater for 16 to 20 minutes

Lizard skin is hydrophobic. Typically, that allows air to stick very tightly to the skin and permits this bubble to form. But when you cover the skin with an emollient, air no longer sticks to the skin surface, so the bubbles can't form.

This is really significant because this is the first experiment that truly shows the adaptive significance of bubbles. Rebreathing bubbles allows lizards to stay underwater longer.

Part 1

Comment by Dr. Krishna Kumari Challa on September 19, 2024 at 8:06am

Ocean waves grow way beyond known limits, new research finds

Scientists have discovered that ocean waves may become far more extreme and complex than previously imagined.

The new study, published in Nature recently, reveals that under specific conditions, where waves meet each other from different directions, waves can reach heights four times steeper than what was once thought possible.

It has often been assumed that waves are two-dimensional and understanding of wave breaking to-date has been based on these assumptions. Yet in the ocean, waves can travel in many directions and rarely fit this simplified model.

This new research  reveals that three-dimensional waves, which have more complex, multidirectional movements, can be twice as steep before breaking compared to conventional two-dimensional waves, and even more surprisingly, continue to grow even steeper even after breaking has occurred.

The findings could have implications for how offshore structures are designed, weather forecasting and climate modeling, while also affecting our fundamental understanding of several ocean processes.

 Mark McAllister, Three-dimensional wave breaking, Nature (2024). DOI: 10.1038/s41586-024-07886-z. www.nature.com/articles/s41586-024-07886-z

Comment by Dr. Krishna Kumari Challa on September 19, 2024 at 7:11am

Metals in the body from pollutants associated with progression of harmful plaque buildup in the arteries

Metal exposure from environmental pollution is associated with increased buildup of calcium in the coronary arteries at a level that is comparable to traditional risk factors like smoking and diabetes, according to a study.

The findings support the fact that metals in the body are associated with the progression of plaque buildup in the arteries and potentially provide a new strategy for managing and preventing atherosclerosis. The results are published in the Journal of the American College of Cardiology.

These findings highlight the importance of considering metal exposure as a significant risk factor for atherosclerosis and cardiovascular disease

Atherosclerosis is a condition where the arteries become narrowed and hardened due to a buildup of plaque, which can restrict blood flow and cause clots to form. It's an underlying cause of heart attacks, strokes and peripheral artery disease (PAD), the most common forms of cardiovascular disease (CVD). Atherosclerosis causes coronary artery calcium (CAC), which can be measured non-invasively over time to predict future cardiac events.

Widespread cadmium, tungsten, uranium, cobalt, copper, and zinc pollution occurs from agricultural and industrial uses such as fertilizers, batteries, oil production, welding, mining, and nuclear energy production. Tobacco smoke is the main source of cadmium exposure.

Results provided evidence that metal exposure may be associated with atherosclerosis over 10 years by increasing coronary calcification.

Urinary Metal Levels and Coronary Artery Calcification: Longitudinal Evidence in the Multi-Ethnic Study of Atherosclerosis, Journal of the American College of Cardiology (2024). DOI: 10.1016/j.jacc.2024.07.020

Comment by Dr. Krishna Kumari Challa on September 19, 2024 at 7:06am

When a small body (like an asteroid) passes close to a large body (like a planet), it gets stretched by gravity. If it gets close enough (inside a distance called the Roche limit), the small body will break apart into lots of tiny pieces and a small number of bigger pieces.

All those fragments will be jostled around and gradually evolved into a debris ring orbiting the equator of the larger body. Over time, the material in the ring will fall down to the larger body, where the larger pieces will form impact craters. These craters will be located close to the equator.

So if Earth destroyed and captured a passing asteroid around 466 million years ago, it would explain the anomalous locations of the impact craters, the meteorite debris in sedimentary rocks, craters and tsunamis, and the meteorites' relatively brief exposure to space radiation.
Back then, the continents were in different positions due to continental drift. Much of North America, Europe and Australia were close to the equator, whereas Africa and South America were at higher southern latitudes.

The ring would have been around the equator. And since Earth's axis is tilted relative to its orbit around the sun, the ring would have shaded parts of Earth's surface.

This shading in turn might have caused global cooling, as less sunlight reached the planet's surface.

This brings us to another interesting puzzle. Around 465 million years ago, our planet began cooling dramatically. By 445 million years ago it was in the Hirnantian Ice Age, the coldest period in the past half a billion years.

Was a ring shading Earth responsible for this extreme cooling? The next step in our scientific sleuthing is to make mathematical models of how asteroids break up and disperse, and how the resulting ring evolves over time. This will set the scene for climate modeling that explores how much cooling could be imposed by such a ring.

 Andrew G. Tomkins et al, Evidence suggesting that earth had a ring in the Ordovician, Earth and Planetary Science Letters (2024). DOI: 10.1016/j.epsl.2024.118991

Part 3

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Comment by Dr. Krishna Kumari Challa on September 19, 2024 at 7:04am

Using models of how Earth's tectonic plates moved in the past, researchers mapped out where all these craters were when they first formed. We found all of the craters are on continents that were close to the equator in this period, and none are in places that were closer to the poles.
They measured how much of Earth's land surface suitable for preserving a crater was near the equator at that time. Only about 30% of the suitable land was close to the equator, with 70% at higher latitudes.
Under normal circumstances, asteroids hitting Earth can hit at any latitude, at random, as we see in craters on the moon, Mars and Mercury.

So it's extremely unlikely that all 21 craters from this period would form close to the equator if they were unrelated to one another. We would expect to see many other craters at higher latitudes as well.

The researchers think the best explanation for all this evidence is that a large asteroid broke up during a close encounter with Earth. Over several tens of millions of years, the asteroid's debris rained down onto Earth, creating the pattern of craters, sediments and tsunamis described above.
You may know that Saturn isn't the only planet with rings. Jupiter, Neptune and Uranus have less obvious rings, too. Some scientists have even suggested that Phobos and Deimos, the small moons of Mars, may be remnants of an ancient ring.

So we know a lot about how rings form. Here's how it works.
Part 2

Comment by Dr. Krishna Kumari Challa on September 19, 2024 at 7:01am

Earth may once have had a ring like Saturn

The rings of Saturn are among the most famous and spectacular features in the solar system. Earth may once have had something similar, say researchers.

The existence of such a ring, forming around 466 million years ago and persisting for a few tens of millions of years, could explain several puzzles in our planet's past.

Around 466 million years ago, a lot of meteorites started hitting Earth. We know this because many impact craters formed in a geologically brief period.
In the same period we also find deposits of limestone across Europe, Russia and China containing very high levels of debris from a certain type of meteorite. The meteorite debris in these sedimentary rocks show signs that they were exposed to space radiation for much less time than we see in meteorites that fall today.

Many tsunamis also occurred at this time, as can be seen from other unusual jumbled up sedimentary rocks.

We think all these features are likely related to one another. But what links them together?
Part 1

Comment by Dr. Krishna Kumari Challa on September 19, 2024 at 6:58am

Why petting your cat leads to static electricity

Anyone who has ever pet a cat or shuffled their feet across the carpet knows that rubbing objects together generates static electricity. 

Scientists  have  uncovered the mechanics at play now. 

When an object slides, the front and back parts of that object experience different forces, researchers found. This difference in forces causes different electrical charges to build up on the front and back parts of the object. And the difference in electrical charges creates a current, leading to a light zap.

The study was published in the journal Nano Letters.

The  answer is surprisingly simple. Just having different deformations—and therefore different charges—at the front and back of something sliding leads to current.

Karl P. Olson et al, What Puts the "Tribo" in Triboelectricity?, Nano Letters (2024). DOI: 10.1021/acs.nanolett.4c03656

Comment by Dr. Krishna Kumari Challa on September 18, 2024 at 12:02pm

Surprising sounds could cause riskier decision-making

When you make a decision, certain neurons in your brain emit short bursts of the neurotransmitter dopamine. A new  study shows that when other factors wholly unrelated to the decision at hand—such as an unexpected sound—trigger these dopamine bursts it can lead to riskier decision-making.

The findings demonstrate how sounds around us may affect our choices and could also help researchers better understand dopamine systems in the brain and how they contribute to conditions like schizophrenia and depression.

Gloria W. Feng et al, Surprising sounds influence risky decision making, Nature Communications (2024). DOI: 10.1038/s41467-024-51729-4

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Comment by Dr. Krishna Kumari Challa on September 18, 2024 at 11:59am

By mapping for the first time the sites at which DNA replication starts in liver cells that regenerate after ablation, the scientists discovered that these are always located in non-coding regions. It was also observed that replication initiation was much more efficient in young mice than in old mice.

"These non-coding regions are not subject to regular error checking and therefore accumulate damage over time. After removal of the liver in young mice there is still little damage and DNA replication is possible. On the contrary, when the experiment is carried out in old mice, the excessive number of errors accumulated over time triggers an alarm system that prevents DNA replication.

This block of DNA replication prevents cells from proliferating, leading to degradation of cell functions and tissue senescence.

These observations could help explain why slowly proliferating tissues, such as the liver, age faster than rapidly proliferating tissues, such as the intestine. In cells that have remained dormant for long periods, too many cryptic DNA lesions have accumulated in the non-coding regions, which contain the origins of replication, and prevent replication from being triggered. In rapidly proliferating tissues, on the other hand, little damage accumulates thanks to frequent cell renewal, and the origins of replication retain their efficiency.

 In vivo DNA replication dynamics unveil aging-dependent replication stress, Cell (2024). DOI: 10.1016/j.cell.2024.08.034. www.cell.com/cell/fulltext/S0092-8674(24)00963-2

Part 2

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Comment by Dr. Krishna Kumari Challa on September 18, 2024 at 11:58am

Why some organs age faster than others: Scientists discover hidden mutations in non-coding DNA

The accumulation of mutations in DNA is often mentioned as an explanation for the aging process, but it remains just one hypothesis among many. A team of researchers has identified a mechanism that explains why certain organs, such as the liver, age more rapidly than others.

The mechanism reveals that damages to non-coding DNA, which are often hidden, accumulate more in slowly proliferating tissues, such as those of the liver or kidneys. Unlike in organs that regenerate frequently, these damages remain undetected for a long time and prevent cell division. These results, published in the journal Cell, open new avenues for understanding cellular aging and potentially slowing it down.

Our organs and tissues do not all age at the same rate. Aging, marked by an increase in senescent cells—cells that are unable to divide and have lost their functions—affects the liver or kidneys more rapidly than the skin or intestine.

The mechanisms that contribute to this process are the subject of much debate within the scientific community. While it is widely accepted that damage to the genetic material (DNA), which accumulates with age, is at the root of aging, the link between the two phenomena remains unclear.

DNA molecules contain coding regions—the genes that code for proteins—and non-coding regions that are involved in the mechanisms that regulate or organize the genome. Constantly damaged by external and internal factors, the cell has DNA repair systems that prevent the accumulation of errors.

Errors located in the coding regions are detected when genes are transcribed, i.e. when they are activated. Errors in non-coding regions are detected during cell renewal, which requires the creation of a new copy of the genome each time, via the process of DNA replication. However, cell renewal does not occur with the same frequency depending on the type of tissue or organ.

Tissues and organs that are in constant contact with the outside environment, such as the skin or intestine, renew their cells (and therefore replicate their DNA) more often—once or twice a week—than internal organs, such as the liver or kidneys, whose cells proliferate only a few times per year.

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