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Comment by Dr. Krishna Kumari Challa on May 2, 2025 at 3:01pm

Re-writing textbooks: New insights into cell division

Scientists  have changed our understanding of how cells in living organisms divide, which could revise what students are taught at school. In a study published this week in Science, the researchers challenge conventional wisdom taught in schools for over 100 years.

Students are currently taught that during cell division, a parent cell will become spherical before splitting into two daughter cells of equal size and shape. However, the study reveals that cell rounding is not a universal feature of cell division and is not how it often works in the body.

Dividing cells, the researchers show, often don't round up into sphere-like shapes. This lack of rounding breaks the symmetry of division to generate two daughter cells that differ from each other in both size and function, known as asymmetric division.

Asymmetric divisions are an important way that the different types of cells in the body are generated, to make different tissues and organs. Until now, asymmetric cell division has predominantly only been associated with highly specialized cells, known as stem cells.

The scientists found that it is the shape of a parent cell before it even divides that can determine if they will round or not in division and determines how symmetric—or not—its daughter cells will be. Cells that are shorter and wider in shape tend to round up and divide into two cells which are similar to each other. However, cells that are longer and thinner don't round up and divide asymmetrically, so that one daughter is different from the other.

Part 1

Comment by Dr. Krishna Kumari Challa on May 2, 2025 at 2:48pm

Size and chemical makeup determine which ancient animals fossilize

Why do some ancient animals become fossils while others disappear without a trace? A new study  published in Nature Communications, reveals that part of the answer lies in the body itself. The research shows that an animal's size and chemical makeup can play an important role in determining whether it's preserved for millions of years—or lost to time.

Fossils are more than just bones; some of the most remarkable finds include traces of soft tissues like muscles, guts, and even brains. These rare fossils offer vivid glimpses into the past, but scientists have long puzzled over why such preservation happens only for certain animals and organs but not others.

To dig into this mystery, a team of scientists turned to the lab. They conducted state-of-the-art decay experiments, allowing a range of animals including shrimps, snails, starfish, and planarians (worms) to decompose under precisely controlled conditions.

As the bodies broke down, the researchers used micro-sensors to monitor the surrounding chemical environment, particularly the balance between oxygen-rich (oxidizing) and oxygen-poor (reducing) conditions.

The results were striking. The researchers discovered that larger animals and those with a higher protein content tend to create reducing (oxygen-poor) conditions more rapidly. These conditions are crucial for fossilization because they slow down decay and trigger chemical reactions such as mineralization or tissue replacement by more durable minerals.

This means that, in nature, two animals buried side by side could have vastly different fates as fossils, simply because of differences in size or body chemistry. One might vanish entirely, while the other could be immortalized in stone.

According to this study, animals such as large arthropods are more likely to be preserved than small planarians or other aquatic worms. This could explain why fossil communities dating from the Cambrian and Ordovician periods (around 500 million years ago) are dominated by arthropods.

These findings not only help explain the patchy nature of the fossil record but also offer valuable insight into the chemical processes that shape what ancient life we can reconstruct today. Pinpointing the factors that drive soft-tissue fossilization brings us closer to understanding how exceptional fossils form—and why we only see fragments of the past.

 Nora Corthésy et al, Taxon-specific redox conditions control fossilisation pathways, Nature Communications (2025). DOI: 10.1038/s41467-025-59372-3

Comment by Dr. Krishna Kumari Challa on May 2, 2025 at 2:30pm

Skin wounds in humans found to heal nearly three times slower than those in other primates

A team of evolutionary scientists, dermatologists and wildlife specialists has found that human skin wounds take nearly three times as long to heal as they do in other primates. In their study, published in the journal Proceedings of the Royal Society B: Biological Sciences, the group conducted experiments involving skin healing speed in humans and several other primates.

Prior research  suggest that other animals recover from skin wounds faster than humans. In this new effort, the research team sought to measure such differences.

The experiments involved comparing skin wounds in humans—courtesy of volunteers at a hospital undergoing skin tumor removal—and several primates. Wound healing pace in chimpanzees was measured by studying chimps housed at a sanctuary who endured skin wounds periodically due to fighting between males.

In looking at the data, the researchers found that all the test subjects healed at nearly the same rate—0.62 millimeters of new skin growth a day—except for humans, who healed at an average of 0.25 millimeters per day. The researchers also tested mice and rats and found their healing rates were similar to those of non-human primates.

The research team suggests the reason for the difference lies in humans having lost their fur. They note that hair follicle stem cells can grow skin cells when needed. Humans have replaced most of their hair follicles with sweat glands, which also have stem cells that can grow into skin cells, but do so far less efficiently.

As humans lost their fur, the researchers note, they replaced them with sweat glands to prevent overheating. The trade-off was obviously worth it, or humans would be covered in fur today. They also note that the expanding brain may have helped along the way, providing humans with the ability to treat skin wounds in ways other animals cannot.

Akiko Matsumoto-Oda et al, Inter-species differences in wound-healing rate: a comparative study involving primates and rodents, Proceedings of the Royal Society B: Biological Sciences (2025). DOI: 10.1098/rspb.2025.0233

Comment by Dr. Krishna Kumari Challa on May 1, 2025 at 10:21am

When looking at the likelihood of having a fatal or a serious injury, as compared to a slight injury, the likelihood increased by around a quarter (odds 24% higher in adults and 28% higher in children) for those hit by an SUV or LTV. These effects were all similar for both pedestrians and cyclists.

Previous research indicates that a key mechanism for this increased risk is likely to be the taller and blunter profile of the front end of SUVs and LTVs. A taller front end means that a pedestrian or cyclist is struck higher up on their body (e.g. the pelvis not the knees for an adult, or the head not the pelvis for a child).

A taller and blunter front end also means that the pedestrian or cyclist is more likely to be thrown forward onto the road, at which point the striking vehicle may hit them a second time or roll over their body.
If all SUVs were replaced with passenger cars, the number of pedestrians and cyclists killed in car crashes would decrease, say the researchers.

 Do sports utility vehicles (SUVs) and light truck vehicles (LTVs) cause more severe injuries to pedestrians and cyclists than passenger cars in the case of a crash? A systematic review and meta-analysis, Injury Prevention (2025). DOI: 10.1136/ip-2024-045613

Part 2

Comment by Dr. Krishna Kumari Challa on May 1, 2025 at 10:20am

SUVs pose greater risk of death or serious injury to pedestrians and cyclists, study shows

The likelihood of a pedestrian or cyclist being fatally injured is 44% higher if they are hit by a sports utility vehicle (SUV) or light truck vehicle (LTV) compared with smaller passenger cars, new research shows. For children there is an even larger effect, with a child hit by an SUV or LTV being 82% more likely to be killed than a child hit by a passenger car.

Researchers gathered real-world collision data from over 680,000 collisions from the last 35 years.

They compared the severity of injuries suffered by pedestrians or cyclists struck by SUVs or LTVs with the injuries of pedestrians or cyclists struck by passenger cars. LTVs are a category of vehicle that covers SUVs, small vans and pick-up trucks – the researchers found similar increases in risk when they looked at SUVs only.

The research is published in Injury Prevention.

SUVs and LTVs are typically taller, wider and heavier than traditional passenger cars, such as sedans or hatchbacks.

Multiple cities worldwide have recently introduced, or are currently considering, policies that discourage the use of these large vehicles.

In the study, the authors found that in the case of a crash, pedestrians or cyclists struck by an SUV or LTV suffered more severe injuries than those hit by a passenger car. The odds of fatal injury increased by 44% for people of all ages struck by an SUV, compared with those hit by a passenger car. Among children, the odds of fatal injury increased by 82%, and among children under the age of 10 it increased by 130%.

Part 1

Comment by Dr. Krishna Kumari Challa on May 1, 2025 at 8:02am

To explain what they observed, the researchers developed a first-order theoretical model showing how mechanical stresses build up unevenly on either side of the droplet—a difference that helps explain the asymmetric cracking patterns they saw.

These findings have real-world implications. In forensic science, for example, investigators use bloodstain pattern analysis—or BPA—to reconstruct events at crime scenes. Their results suggest that both the tilt of the surface and the size of the droplet can significantly alter the resulting patterns. Ignoring these factors could lead to misinterpretations, potentially affecting how such evidence is read and understood.

Bibek Kumar et al, Asymmetric Deposits and Crack Formation during Desiccation of a Blood Droplet on an Inclined Surface, Langmuir (2025). DOI: 10.1021/acs.langmuir.4c03767

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Comment by Dr. Krishna Kumari Challa on May 1, 2025 at 8:01am

Blood droplets on inclined surfaces reveal new cracking patterns

Drying droplets have fascinated scientists for decades. From water to coffee to paint, these everyday fluids leave behind intricate patterns as they evaporate. But blood is far more complex—a colloidal suspension packed with red blood cells, plasma proteins, salts, and countless biomolecules.

As blood dries, it leaves behind a complex microstructural pattern—cracks, rings, and folds—each shaped by the interplay of its cellular components, proteins, and evaporation dynamics. These features form a kind of physical fingerprint, quietly recording the complex interplay of physics that unfolded during the desiccation of the droplet.

Researchers explored how blood droplets dry by varying both their size—from tiny 1-microliter drops to larger 10-microliter ones—and the angle of the surface, from completely horizontal to a steep 70° incline. Using an optical microscope, a high-speed camera, and a surface profiler, they tracked how the droplets dried, shrank and cracked.

 On flat surfaces, blood droplets dried predictably, forming familiar coffee-ring-like deposits surrounded by networks of radial and azimuthal cracks. But as the researchers increased the tilt, gravity pulled the red blood cells downhill, while surface tension tried to hold them up. This resulted in asymmetric deposits and stretched patterns—a kind of biological landslide frozen in time.

Cracking patterns were different on the advancing (downhill) and receding (uphill) sides. On the advancing side, where the dried blood mass accumulated more, the cracks were thicker and more widely spaced. On the receding side, where the deposit thinned out, the cracks were finer. Larger droplets (10 microliter) exaggerated the asymmetry even more, with gravity playing a bigger role as the droplets grew heavier—leaving behind a long, thin "tail" of blood that dried and showed scattered dried red blood cells.

Part 1

Comment by Dr. Krishna Kumari Challa on April 30, 2025 at 9:05am

Scientists develop silk microneedles to deliver nutrients and chemicals to plants

When farmers apply pesticides to their crops, 30 to 50% of the chemicals end up in the air or soil instead of on the plants. Now, a team of researchers has developed a much more precise way to deliver substances to plants: tiny needles made of silk.

In a study published in Nature Nanotechnology, the researchers developed a way to produce large amounts of these hollow silk microneedles. They used them to inject agrochemicals and nutrients into plants, and to monitor their health.

In demonstrations, the team used the technique to give plants iron to treat a disease known as chlorosis, and to add vitamin B12 to tomato plants to make them more nutritious. The researchers also showed the microneedles could be used to monitor the quality of fluids flowing into plants and to detect when the surrounding soil contained heavy metals.

Overall, the researchers think the microneedles could serve as a new kind of plant interface for real-time health monitoring and biofortification.

Yunteng Cao et al, Nanofabrication of silk microneedles for high-throughput micronutrient delivery and continuous sap monitoring in plants, Nature Nanotechnology (2025). DOI: 10.1038/s41565-025-01923-2

Comment by Dr. Krishna Kumari Challa on April 30, 2025 at 9:00am

Heart disease deaths worldwide linked to chemical widely used in plastics

Daily exposure to certain chemicals used to make plastic household items could be linked to more than 365,000 global deaths from heart disease in 2018 alone, a new analysis of population surveys shows.

While the chemicals, called phthalates, are in widespread use globally, Africa, South Asia, and the Middle East populations bore a much larger share of the death toll than others—about half the total.

For decades, experts have connected health problems to exposure to certain phthalates found in cosmetics, detergents, solvents, plastic pipes, bug repellents, and other products. When these chemicals break down into microscopic particles and are ingested, studies have linked them to an increased risk of conditions ranging from obesity and diabetes to fertility issues and cancer.

 The current study focused on a kind of phthalate called di-2-ethylhexyl phthalate (DEHP), which is used to make food containers, medical equipment, and other plastic softer and more flexible. Exposure has been shown in other studies to prompt an overactive immune response (inflammation) in the heart's arteries, which, over time, is associated with an increased risk of heart attack or stroke.

In their new analysis, the authors estimated that DEHP exposure contributed to 368,764 deaths, or more than 10% of all global mortality from heart disease in 2018 among men and women aged 55 through 64. A report on the findings is published in the journal eBioMedicine.

"By highlighting the connection between phthalates and a leading cause of death across the world, our findings add to the vast body of evidence that these chemicals present a tremendous danger to human health," said study  authors.

According to the authors, the resulting economic burden from the deaths identified in their study was estimated to be around $510 billion and may have reached as high as $3.74 trillion.

In a past study from 2021, the research team tied phthalates to more than 50,000 premature deaths each year, mostly from heart disease.

 Phthalate exposure from plastics and cardiovascular disease: global estimates of attributable mortality and years life lost, eBioMedicine (2025). DOI: 10.1016/j.ebiom.2025.105730

Comment by Dr. Krishna Kumari Challa on April 30, 2025 at 8:49am

Most of the elements we know and love today weren't always around. Hydrogen, helium and a dash of lithium were formed in the Big Bang, but almost everything else has been manufactured by stars in their lives, or during their violent deaths. While scientists thoroughly understand where and how the lighter elements are made, the production locations of many of the heaviest neutron-rich elements—those heavier than iron—remain incomplete.

These elements, which include uranium and strontium, are produced in a set of nuclear reactions known as the rapid neutron-capture process, or r-process. This process requires an excess of free neutrons—something that can be found only in extreme environments. Astronomers thus expected that the extreme environments created by supernovae or neutron star mergers were the most promising potential r-process sites.

It wasn't until 2017 that astronomers were able to confirm an r-process site when they observed the collision of two neutron stars. These stars are the collapsed remnants of former stellar giants and are made of a soup of neutrons so dense that a single tablespoon would weigh more than 1 billion tons. The 2017 observations showed that the cataclysmic collision of two of these stars creates the neutron-rich environment needed for the formation of r-process elements.
However, astronomers realized that these rare collisions alone can't account for all the r-process-produced elements we see today. Some suspected that magnetars, which are highly magnetized neutron stars, could also be a source.

Researchers  calculated in 2024 that giant flares could eject material from a magnetar's crust into space, where r-process elements could form.

It's pretty incredible to think that some of the heavy elements all around us, like the precious metals in our phones and computers, are produced in these crazy extreme environments

The group's calculations show that these giant flares create unstable, heavy radioactive nuclei, which decay into stable elements such as gold. As the radioactive elements decay, they emit a glow of light, in addition to minting new elements. The group also calculated in 2024 that the glow from the radioactive decays would be visible as a burst of gamma rays, a form of highly energized light. When they discussed their findings with observational gamma-ray astronomers, the group learned that, in fact, one such signal had been seen decades earlier that had never been explained. Since there's little overlap between the study of magnetar activity and heavy-element synthesis science, no one had previously proposed element production as a cause of the signal.

In the new paper, the astronomers used the observations of the 2004 event to estimate that the flare produced 2 million billion billion kilograms of heavy elements (roughly equivalent to Mars' mass). From this, they estimate that one to 10% of all r-process elements in our galaxy today were created in these giant flares. The remainder could be from neutron star mergers, but with only one magnetar giant flare and one merger ever documented, it's hard to know exact percentages—or if that's even the whole story.

Anirudh Patel et al, Direct Evidence for r-process Nucleosynthesis in Delayed MeV Emission from the SGR 1806–20 Magnetar Giant Flare, The Astrophysical Journal Letters (2025). DOI: 10.3847/2041-8213/adc9b0

Part 2

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