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Comment by Dr. Krishna Kumari Challa on September 19, 2025 at 9:30am

Grue jay? Rare hybrid bird identified 

Biologists who have reported discovering a bird that's the natural result of a green jay and a blue jay's mating, say it may be among the first examples of a hybrid animal that exists because of recent changing patterns in the climate. The two different parent species are separated by 7 million years of evolution, and their ranges didn't overlap as recently as a few decades ago.

They  think it's the first observed vertebrate that's hybridized as a result of two species both expanding their ranges due, at least in part, to climate change.

Past vertebrate hybrids have resulted from human activity, like the introduction of invasive species, or the recent expansion of one species' range into another's—think polar bears and grizzlies—but this case appears to have occurred when shifts in weather patterns spurred the expansion of both parent species.

Hybridization is probably way more common in the natural world than researchers know about because there's just so much inability to report these things happening.

The researchers did not opt to name the hybrid bird, but other naturally occurring hybrids have received nicknames like "grolar bear" for the polar bear-grizzly hybrid, "coywolf" for a creature that's part coyote and part wolf and "narluga" for an animal with both narwhal and beluga whale parents.

Brian R. Stokes et al, An Intergeneric Hybrid Between Historically Isolated Temperate and Tropical Jays Following Recent Range Expansion, Ecology and Evolution (2025). DOI: 10.1002/ece3.72148

Comment by Dr. Krishna Kumari Challa on September 19, 2025 at 9:16am

The researchers further found that sex-specific genes often occur in "modules" that are regulated together. Evolution therefore alters sex differences not by changing single genes, but by rearranging whole networks. The driving force here is sexual selection—the ongoing evolutionary conflict between the interests of males and females. This conflict can never be fully resolved, as every adaptation creates new contrasts.

When applied to human tissues, the method reveals a clear pattern: markedly fewer sex-specific genes than in mice, and even stronger overlaps between men and women. In our species, differences are therefore weaker, further undermining the idea of a strict binary classification.

The study concludes that while the sexual organs show a clear binary pattern, most other tissues display a continuum of sex-specific gene activity—a dynamic spectrum that varies both between species and between individuals.

Sex is therefore not rigid and clear-cut, but shaped by evolution, overlaps and individual differences. Instead of classifying the body strictly as male or female based on molecular features, it should be understood as a complex mosaic.

Chen Xie et al, Fast evolutionary turnover and overlapping variances of sex-biased gene expression patterns defy a simple binary sex classification of somatic tissues, eLife (2025). DOI: 10.7554/elife.99602.4

Part 2

Comment by Dr. Krishna Kumari Challa on September 19, 2025 at 9:16am

Our body organs cannot simply be classified as male or female

Biological sex is usually described in simple binary terms: male or female. This works well for germ cells (sperm versus eggs), but for other body organs it is of little help.

A new study shows that our organs form a mosaic of sex-specific characteristics—far removed from the strict division into male and female.

The research shows that in many organs, sex-specific patterns overlap strongly. Only testes and ovaries are clearly distinguishable. All other organs show mosaic-like combinations of male and female characteristics.

Sex-specific genes stand out most strongly in the sexual organs. But in other organs the picture is more complex. In mice, the kidney and liver show large differences, while in humans it is adipose tissue. By contrast, the brain shows only minimal differences in both species—consistent with previous studies of human brain structure.

To capture this diversity, the researchers developed a Sex-Bias Index (SBI). This index summarizes the activity of all male- and female-specific genes in an organ into a single value. While the index shows a clear separation in the sexual organs, in other organs the values are often so close that men and women cannot be distinguished reliably.

For example, a man's heart may be more "female-like" than that of some women. Even within an individual, organs can differ—the heart more female, the liver more male. This results in a mosaic of sex characteristics that contradicts the idea of a clear-cut binary.

The study, published in eLife, also shows that sex-specific gene activity in organs evolves very rapidly—much faster than genes active in both sexes equally. Even between mouse species that diverged less than 2 million years ago, the majority of genes have lost or even switched their sex-specific role.

As a result, when comparing humans and mice, only very few genes retain conserved sex-specific activity. This also means that mouse models are of very limited use when applied to sex-specific medicine in humans.

Part 1

Comment by Dr. Krishna Kumari Challa on September 19, 2025 at 7:13am

Carbon credits have little to no effect on making companies greener, study reveals

Many companies across the world use carbon credits as part of their climate strategies to offset emissions. A carbon credit is a certificate that represents the reduction, avoidance or removal of one ton of carbon dioxide from the atmosphere. While organizations claim these credits help them reduce their environmental impact, there is debate about whether companies that buy credits decarbonize faster. However, an in-depth study of 89 multinationals, published in Nature Communications, reveals that companies that purchase credits do not decarbonize any quicker than those that do not.

Voluntary emission offsetting is not associated with positive corporate environmental performance. Therefore, it is not a reliable alternative to regulatory measures, such as compliance carbon pricing, wrote the researchers in their paper.

Researchers examined over 400 sustainability reports and self-reported environmental data from multinational companies working in the oil and gas, automotive and airline industries. These were firms that bought and used roughly a quarter of all carbon credits that were available in 2022.
They then compared how much these companies reduced their emissions between 2018 and 2023 and how ambitious their climate goals were with the amount of carbon credits they purchased. To make sure the company data was accurate, the researchers checked it against major carbon credit agencies.

The study found that, on average, companies spend about 1% of their capital spending on carbon credits, which means they account for a small share of the overall budget. The research also highlights a problem where carbon offsets can compete with internal decarbonization.

For some large-scale off-setters buying large amounts of carbon credits can divert funds from internal projects that would directly cut their emissions. Other companies use carbon credits to meet their goals because it is cheaper and easier than making internal structural changes.

The researchers suggest a way forward, namely a shift away from voluntary carbon offsetting to regulatory measures, such as carbon compliance. This is a government-mandated system where companies must pay for the carbon they emit. The main goal here is to create a financial incentive for companies to reduce their carbon emissions.

Niklas Stolz et al, The negligible role of carbon offsetting in corporate climate strategies, Nature Communications (2025). DOI: 10.1038/s41467-025-62970-w

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

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