Comment

Comment by Dr. Krishna Kumari Challa on September 19, 2025 at 7:09am

Jaguar swims over a kilometer, showing dams are not absolute barriers to large carnivores

Scientists in Brazil recently recorded evidence that a jaguar visited an isolated island in the reservoir area of the Serra da Mesa Hydroelectric Power Dam in northern Goiás State. The same jaguar had been identified on the mainland, 2.48 km away from the island, back in 2020. Both instances were recorded by camera-trap stations, three on the mainland and one on the island, which were set up for an exploratory jaguar survey. The specific jaguar's identity was confirmed by spot-pattern analysis.

After analyzing possible aquatic trajectories for the jaguar, the researchers found that it had two possible paths. Either the jaguar swam the direct 2.48 km to the island, or used a stepping-stone-like islet, taking a 1.06 km swim, followed by a 1.27 km swim to get to the island.

Previous records indicated a maximum swimming distance of around 200 meters for jaguars. Given the possible paths here, this jaguar had to swim a minimum of 1.27 km, possibly more, shattering previous records. This impressive feat is documented in a new bioRxiv preprint, in which the researchers involved also discuss a newly proposed aquatic-cost scale for assessing the ecological connectivity between landmasses.

It was previously thought that reservoirs, like Serra da Mesa, acted as absolute barriers for large carnivores due to prior instances of predator collapse on islands further than a kilometer away from the mainland. Yet, genetic studies across the Amazon River indicated only partial segregation, suggesting occasional crossings.

The study authors explain, "These rare events suggest that, under favorable conditions (e.g., warm water, low currents, presence of stepping-stone islands), large felids may occasionally exploit aquatic corridors that appear to be initially insurmountable."

The research team proposes a new ordinal aquatic-cost scale for modeling connectivity between landmasses, described by low/medium/high cost ranking for water crossings. Low cost was defined as less than 300 m; medium as 300–1,000 m with stepping-stones; and high as greater than 1,000 m of open water. This scale is meant to help inform future hydropower impact assessments and corridor planning for jaguar conservation.

Leandro Silveira et al, Kilometre-scale jaguar swimming reveals permeable hydropower barriers: implications for conservation in the Cerrado hotspot, bioRxiv (2025). DOI: 10.1101/2025.09.05.674446

Comment by Dr. Krishna Kumari Challa on September 19, 2025 at 7:02am

Who are vulnerable to health disinformation?

Individuals who like to think critically are better at identifying false information online, while those with conservative political affiliations struggle more with detecting fake medical information on social media, according to a PLOS One study.

Researchers analyzed responses from 508  participants who reviewed 10 different social media posts that covered diverse health topics with both honest and disinforming claims, with 60% of them falling under the second category.

After viewing the videos and making their honesty judgments, participants were asked to record their responses through online surveys, selecting up to eight reasons from a predefined list. These reasons included the reliability of the source, whether claims were supported by evidence or based on opinion, and the presence or absence of credentials.

Overall, people detected health disinformation with 66% accuracy. This performance is troubling, especially with the world living through an infodemic, a flood of online information where fact and fiction mix freely. Finding trustworthy health guidance online has become increasingly difficult, owing to black box–like social media algorithms that amplify accurate and misleading posts alike.

The COVID-19 pandemic made quite evident the dangers of health disinformation spreading online. Misleading health advice in digital spaces is not just a matter of debate anymore, it is a pressing public health concern with serious real-world consequences.

Previous studies have shown that political leanings can be an indicator of how a person fares at spotting false information online. More recent research, however, highlights a personality trait known as need for cognition—the tendency to seek out and enjoy analytical thinking—as an even stronger predictor.

The results indicated that those with a high need for cognition were significantly better at identifying false information. At the same time, political leanings influenced how certain posts were perceived, particularly on polarizing topics such as COVID-19 vaccines and FDA warnings about drugs like ivermectin and hydroxychloroquine.

The researchers note that the nature of the current infodemic calls for deeper investigation into how disinformation on health issues affects people's everyday lives.

Joey F. George, Political affiliation or need for cognition? It depends on the post: Comparing key factors related to detecting health disinformation in the U.S., PLOS One (2025). DOI: 10.1371/journal.pone.0315259

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Comment by Dr. Krishna Kumari Challa on September 18, 2025 at 11:11am

Scientists discover proteins that initiate cellular immunity in bone marrow

Researchers have shown how a critical pathway is fundamental to the immune system.

Establishing cellular immunity depends on the thymus, a lymph gland located in front of the heart. This gland produces and exports T cells, a workhorse white blood cell, out to the rest of the body, using the building blocks of stem cells from the bone marrow. But it has remained a riddle how T cell fate is initiated.

The new paper shows that two protein "transcription factors" called Tcf1 and Lef1 are critical modulators that direct bone marrow stem cells to the T cell path in the thymus.

By carefully removing these proteins via in vivo and ex vivo models, the team of scientists revealed a foundational event in the immune system, which represents essentially the very origin of a functional cellular immune competence.

This discovery illustrates a whole new understanding of T cell formation, and could lead to a wide range of novel approaches in treating immune deficiencies, autoimmune diseases, and optimizing immunotherapies in the ongoing fight against cancer.

"These findings reveal that Tcf1 and Lef1 act much earlier than previously recognized, extending beyond their roles in promoting T-cell lineage specification and commitment at later stages in the thymus," the authors write, adding that the "downstream" Notch signaling pathway is corrupted without these two assisting proteins.

 Xin Zhao et al, Single-cell multiomics identifies Tcf1 and Lef1 as key initiators of early thymic progenitor fate, Science Immunology (2025). DOI: 10.1126/sciimmunol.adq8970

Comment by Dr. Krishna Kumari Challa on September 18, 2025 at 10:33am

The study also revealed that participants who experienced breakthrough infections had lower levels of IgA(S) antibodies in their blood several weeks after vaccination. These antibodies protect the nose and throat and are our first line of defense against respiratory viruses.

Importantly, the researchers found a strong correlation between blood IgA(S) levels and nasal IgA(S) levels, suggesting that blood tests can reliably indicate the strength of immune protection in airways. As a result, measuring blood IgA(S) levels after vaccination may help identify individuals at higher risk for breakthrough infection, especially among vulnerable groups.
The researchers emphasize the importance of identifying the underlying biological mechanisms responsible for the rapid decline in antibody levels in order to develop more effective vaccination strategies.
Previous research points to factors such as age, genetic variation, vaccine-specific characteristics, and environmental influences, including sleep habits, stress levels, and medications being taken at the same time.
Identifying the rapid-decliner pattern is especially important—it helps explain why some people may need boosters sooner than others.

This could potentially contribute to better, more personalized vaccination strategies.

 Longitudinal antibody titers measured after COVID-19 mRNA vaccination can identify individuals at risk for subsequent infection, Science Translational Medicine (2025). DOI: 10.1126/scitranslmed.adv4214

Part 2

Comment by Dr. Krishna Kumari Challa on September 18, 2025 at 10:31am

COVID-19 vaccine responses show four patterns, with 'rapid-decliners' at higher infection risk

Two health care workers get COVID-19 vaccinations on the same day. Both show strong antibody responses initially, but six months later one stays healthy while the other contracts the virus. A new study published in Science Translational Medicine could help explain this difference.

Researchers tracked individuals' antibody levels after vaccinations and identified four distinct patterns of immune response after the first booster vaccination. Notably, people in the group that started with the highest antibody levels but experienced a faster decline were infected earlier. People with lower blood levels of IgA(S) antibodies, which protect the nose and throat, were also at higher risk. The findings suggest that monitoring how antibody levels change over time could assist in identifying individuals at greater risk of infection.

The research team measured antibody levels in 2,526 people over 18 months to see how vaccine responses changed between the first vaccination and later booster shots. They developed a mathematical classification system for COVID-19 vaccine responses using long-term tracking and AI-based computer analysis, becoming the first to systematically identify and characterize the "rapid-decliner" group.

The researchers found that immune responses fell into four clear patterns: Some people maintained high antibody levels over time (durable responders), others started with strong levels but lost them quickly (rapid-decliners), a third group produced few antibodies that also declined rapidly (vulnerable responders), and the rest fell in between (intermediate responders).

A breakthrough or subsequent infection refers to infections that occur after vaccination because the virus overcomes the immune protection that vaccines provide. The researchers found that people whose antibodies declined faster, either because they started low or dropped quickly (vulnerable responders and rapid-decliners), were slightly more likely to get breakthrough infections earlier.

After booster vaccinations, 29% of participants fell into the durable responder category, 28% were vulnerable responders, and 19% were rapid-decliners. The remaining participants showed intermediate patterns. The differences in breakthrough infection rates between groups were modest—5.2% for durable responders and 6% for vulnerable and rapid-decliners.

Part 1

Comment by Dr. Krishna Kumari Challa on September 18, 2025 at 10:24am

How an essential vitamin B-derived nutrient concentrates in mitochondria

There's a molecule that our body makes from vitamin B₅ that is critical for all of the metabolic processes essential for human life. And when something goes wrong in that molecule's production, it affects nearly every organ system in our body and causes a number of diseases.

Researchers have discovered that up to 95% of this molecule—called essential cofactor coenzyme A (CoA)—is located inside mitochondria, organelles that supply cellular energy and regulate cellular metabolism. But what has not been clear is how CoA gets there.

Reporting in Nature Metabolism, researchers have now uncovered that CoA is trafficked into mitochondria and have identified the mechanisms responsible.

This information, the researchers say, is important for future considerations about when and where to target treatments for diseases in which CoA is implicated.

The researchers were able to identify 33 different CoA conjugates in whole cells as well as 23 CoA conjugates in mitochondria.

The question then was whether the CoA conjugates in the mitochondria were made there or brought in from elsewhere.

In additional experiments, the researchers discovered that the enzyme required to make CoA largely exists outside of mitochondria. Further, when they made cells that lacked the molecular transporters that can move CoA around, mitochondria had far less CoA.

These findings strongly support the idea that CoA is being imported into mitochondria, and these transporters are required for that to happen.

This study advances the fundamental understanding of CoA and how it gets to where it needs to be in order to perform its essential functions. That, in turn, sheds light on how disruptions of this process might contribute to illness.

For instance, mutations in the genes that produce CoA transporters are associated with diseases such as encephalomyopathy, a disorder that can include neurodevelopmental delay, epilepsy, and decreased muscle tone. Mutations in the enzymes that produce CoA have been implicated in neurodegeneration.

In the context of brain disorders, such as neurodegeneration and psychiatric disorders, there's an emerging idea that dysregulated mitochondrial metabolism is a contributor.

Ran Liu et al, Cellular pan-chain acyl-CoA profiling reveals SLC25A42/SLC25A16 in mitochondrial CoA import and metabolism, Nature Metabolism (2025). DOI: 10.1038/s42255-025-01358-y

Comment by Dr. Krishna Kumari Challa on September 18, 2025 at 10:02am

Research has also recently revealed that lithornithids may have had a bony organ on the tip of their beaks which made them excel at foraging for insects.

But what about the second condition—a lack of predators?

Researchers suspect that paleognath ancestors likely started evolving towards flightlessness after dinosaurs went extinct around 65 million years ago.

With all the major predators gone, ground-feeding birds would have been free to become flightless, which would have saved them a lot of energy.

The small mammals that survived the event that wiped out the dinosaurs would have taken some time to evolve into predators.

This would have given flightless birds "time to adapt by becoming swift runners" like the emu, ostrich and rhea—or even "becoming themselves dangerous and intimidating, like the cassowary.

Quantitative analysis of stem-palaeognath flight capabilities sheds light on ratite dispersal and flight loss, Biology Letters (2025). DOI: 10.1098/rsbl.2025.0320. royalsocietypublishing.org/doi … .1098/rsbl.2025.0320

Part 2

Comment by Dr. Krishna Kumari Challa on September 18, 2025 at 9:59am

Ostrich and emu ancestor could fly, scientists discover

How did the ostrich cross the ocean?

We have long been puzzled by how the family of birds that includes African ostriches, Australian emus and cassowaries, New Zealand kiwis and South American rheas spread across the world—given that none of them can fly.

However, a study published this week may have found the answer to this mystery: the family's oldest-known ancestors were able to take wing.

The only currently living member of this bird family—which is called paleognaths—capable of flight is the tinamous in Central and South America. But even then, the shy birds can only fly over short distances when they need to escape danger or clear obstacles.

Researchers analyzed the specimen of a lithornithid, the oldest paleognath group for which fossils have been discovered. They lived during the Paleogene period 66–23 million years ago.

The fossil of the bird Lithornis promiscuus was first found in the US state of Wyoming, but had been sitting in the Smithsonian museum's collection.

Because bird bones tend to be delicate, they are often crushed during the process of fossilization, but this one was not. 

Crucially for this study, it retained its original shape. This allowed the researchers to scan the animal's breastbone, which is where the muscles that enable flight would have been attached.

They determined that Lithornis promiscuus was able to fly—either by continuously beating its wings or alternating between flapping and gliding.

But  why did these birds give up the power of flight?

Birds tend to evolve flightlessness when two important conditions are met: they have to be able to obtain all their food on the ground, and there cannot be any predators to threaten them.

Part 1

Comment by Dr. Krishna Kumari Challa on September 18, 2025 at 9:50am

Coral reefs set to stop growing as climate warms

Most coral reefs will soon stop growing and may begin to erode—and almost all will do so if global warming hits 2°C, according to a new study in the western Atlantic. 

The study, published in the journal Nature, projects that more than 70% of the region's reefs will stop growing by 2040—and over 99% will do so by 2100 if warming reaches 2°C or more above pre-industrial levels. The paper is titled "Reduced Atlantic reef growth past 2°C warming amplifies sea-level impacts."

Climate change—along with other issues such as coral disease and deteriorating water quality—reduces overall reef growth by killing corals and impacting colony growth rates, the study concludes.

 Chris Perry, Reduced Atlantic reef growth past 2°C warming amplifies sea-level impacts, Nature (2025). DOI: 10.1038/s41586-025-09439-4. www.nature.com/articles/s41586-025-09439-4

Comment by Dr. Krishna Kumari Challa on September 18, 2025 at 9:37am

Some small asteroids can abruptly explode

Some asteroids are more dangerous than others, according to a report published in Nature Astronomy by an international team of researchers.

The team had presented their findings of an investigation into the impact of small asteroid 2023 CX1 over France in February 2023. This new paper revealed that small asteroids can explode on atmospheric entry.

The researchers confirmed the existence of a new population of asteroids linked to L-type chondrites, capable of fragmenting abruptly in the atmosphere and releasing almost all their energy at once. 

Such asteroids must be accounted for in planetary defense strategies, as they pose an increased risk to populated areas, they say.

Auriane Egal et al, Catastrophic disruption of asteroid 2023 CX1 and implications for planetary defence, Nature Astronomy (2025). DOI: 10.1038/s41550-025-02659-8.

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