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Comment by Dr. Krishna Kumari Challa on February 4, 2025 at 11:29am

Scientists find more microplastics in human brains than in kidneys and livers—and levels are rising

Tiny plastic particles may accumulate at higher levels in the human brain than in the kidney and liver, with greater concentrations detected in postmortem samples from 2024 than in those from 2016, suggests a paper published in Nature Medicine. Although the potential implications for human health remain unclear, these findings may highlight a consequence of rising global concentrations of environmental plastics.

The amount of environmental plastic nano- and microparticles, which range in size from as small as 1 nanometer (one billionth of a meter) up to 500 micrometers (one millionth of a meter) in diameter, has increased exponentially over the past 50 years. However, whether they are harmful or toxic to humans is unclear. Most previous studies used visual microscopic spectroscopy methods to identify particulates in human tissues, but this is often limited to particulates larger than 5 micrometers.

Researchers now  used novel methods to analyze the distribution of micro- and nanoparticles in samples of liver, kidney, and brain tissues from human bodies that underwent autopsy in 2016 and 2024. A total of 52 brain specimens (28 in 2016 and 24 in 2024) were analyzed.

The team detected these particles in all of the samples and found similar concentrations in the samples of liver and kidney tissues obtained in 2016. However, brain samples taken from that time, all derived from the frontal cortex region, contained substantially higher concentrations of plastic particles than the liver and kidney tissues.

They  also found that liver and brain samples from 2024 had significantly higher concentrations of plastic micro- and nanoparticles than those from 2016. They compared these findings with those of brain tissue samples from earlier time frames (1997–2013) and noted that there were higher concentrations of plastic particles in the more recent tissue samples. They also found a higher concentration of micro- and nanoplastic particles in brains from 12 individuals with a documented dementia diagnosis than in those without.

The authors note that the findings identify an association but do not establish a causal link between plastic particles and health effects.

Alexander J. Nihart et al, Bioaccumulation of microplastics in decedent human brains, Nature Medicine (2025). DOI: 10.1038/s41591-024-03453-1

Comment by Dr. Krishna Kumari Challa on February 4, 2025 at 9:57am

How the hippocampus coordinates memory encoding and retrieval

A team of scientists has unveiled how the hippocampus orchestrates multiple memory processes, including encoding new information, forming memories, and retrieving them. The study is published in Nature Communications.

 By applying advanced dimensionality reduction techniques to fMRI data, the researchers demonstrated the hippocampus's critical role in coordinating these processes.

The human brain processes and integrates diverse information simultaneously to form memories. For example, while watching a movie, the brain integrates multiple pieces of information, such as identifying the characters and understanding the evolution of their relationships, to later recall the storyline.

The team hypothesized that the hippocampus coordinates these processes by aligning low-dimensional subspaces of neural activity, which represent different memory functions.

And their results showed that -
Aligned subspaces for the two types of novelty, suggesting that the hippocampus integrates diverse forms of novel information.
Alignment between novelty and memory formation subspaces, with participants showing better memory performance when these alignments were stronger.
Distinct alignment patterns for retrieval, where the subspace for memory retrieval aligned with memory formation but not with novelty, suggesting process-specific coordination by the hippocampus.

This work expands our understanding of memory by uncovering the hippocampus's coordinating role and the neural dynamics supporting it.

 Dasom Kwon et al, Coordinated representations for naturalistic memory encoding and retrieval in hippocampal neural subspaces, Nature Communications (2025). DOI: 10.1038/s41467-025-55833-x

Comment by Dr. Krishna Kumari Challa on February 4, 2025 at 9:44am

Out of four microRNAs located on the X chromosome, the researchers homed in on miR-871. This microRNA reduces the amount of sarcalumenin or SRL, a protein, produced in the heart. SRL helps the heart cells recharge and reset after each muscle contraction and keeps the heart "in rhythm." MiR-888, the human equivalent of miR-871, similarly regulates SRL levels in the human heart.

Researchers confirmed their findings by manipulating the levels of miR-871. They used genetic techniques to inhibit the production of miR-871 in female mice. This intervention increased SRL levels and improved the heart's ability to recharge between beats. Consequently, the hearts of the female mice began to resemble the beating pattern and functionality of male hearts.
Researchers may use this information to develop therapies that modify human microRNA levels to treat heart diseases. MicroRNA-based therapies are already being explored for other conditions.

James I. Emerson et al, X-Chromosome–Linked miRNAs Regulate Sex Differences in Cardiac Physiology, Circulation Research (2024). DOI: 10.1161/CIRCRESAHA.124.325447

Part 2

Comment by Dr. Krishna Kumari Challa on February 4, 2025 at 9:43am

Heart health differences in men and women: Tiny RNA molecules play key role, study finds

There are notable differences between men and women in their susceptibility to many human diseases, including cardiovascular disease. For example, women typically have smaller hearts that pump faster, while men have larger hearts that pump more blood with each heartbeat.

Researchers have been making massive efforts to understand what, in the underlying biology, predisposes people to sex-specific cardiovascular disease.

They recently made a large stride in the field, uncovering one of the molecular reasons behind sex disparities in heart disease.

They discovered that a microRNA called miR-871—one of the smallest RNAs found in cells—plays a significant role in the physiological and pathological differences observed between men's and women's hearts. Their findings were published in Circulation Research.

The findings demonstrate that miRNAs on the X chromosome can directly control male-female differences in the heart. The findings also show that male-female differences in biology can be established after a gene is turned on.

MicroRNAs are small, single-stranded nucleic acids that play a crucial role in regulating gene expression, effectively turning genes down to fine-tune protein production in the body. Although these tasks may seem minor, they significantly influence most bodily functions, from the cellular development of organs to the rhythmic beating of our hearts.

Part 1

Comment by Dr. Krishna Kumari Challa on February 4, 2025 at 9:18am

Many animals and plants are losing their genetic diversity, making them more vulnerable

Two-thirds of animal and plant populations are declining in genetic diversity, which makes it harder to adapt to environmental changes, according to research published this week.

Long before a species goes extinct, the population becomes smaller and more fragmented, shrinking the number of potential mates and therefore genetic mixing. This leaves a species more vulnerable to future threats such as disease.

A surprising trend was that we saw genetic diversity declining even among many species that aren't considered at risk. 

Researchers examined data for 628 species studied between 1985 and 2019. The greatest losses in genetic variation were seen in birds and mammals.

Findings were published in the journal Nature.

When a species has different genetic solutions, it's better able to deal with changes. 

If a new disease spreads through a population or climate change alters summer rainfall, some individuals will fare better than others, in part because of their genes. Higher genetic diversity also means there's a greater chance of a species' survival.

Conservation efforts to connect isolated populations—basically expanding the dating pool for a particular species—can help maintain or even restore genetic diversity.

Isolated populations suffer. The solution is to reconnect them, stress the biologists.

Catherine Grueber, Global meta-analysis shows action is needed to halt genetic diversity loss, Nature (2025). DOI: 10.1038/s41586-024-08458-x. www.nature.com/articles/s41586-024-08458-x

Comment by Dr. Krishna Kumari Challa on February 4, 2025 at 9:11am

Octopuses have some of the oldest known sex chromosomes, study finds

The octopus just revealed another one of its secrets: what determines its sex.

Researchers have identified a sex chromosome in the California two-spot octopus. This chromosome has likely been around for 480 million years, since before octopuses split apart from the nautilus on the evolutionary tree. That makes it one of the oldest known animal sex chromosomes.

The finding also is evidence that octopuses and other cephalopods, a class of sea animals that includes squid and nautiluses, do use chromosomes to determine their sex, answering a longstanding mystery.

The researchers  described the findings Feb. 3 in the journal Current Biology.

In humans and most mammals, sex is determined largely by chromosomes. But "there's a tremendous amount of diversity" in how animals determine their sex.

In turtles, for instance, sex is determined by the temperature at which the eggs are incubated. Some fish have a gene that determines sex, but not a whole chromosome. Even in humans, the X/Y sex chromosome system isn't as clear-cut as it might look on paper; gene mutations or inheriting extra sex chromosomes can lead to development that doesn't neatly fit in a male/female binary.

When  researchers recently sequenced the DNA of a female California two-spot octopus, they found something unexpected: a chromosome with only half the amount of genetic material. It looked different from all the others, and it hadn't been found in male octopuses whose DNA was previously sequenced.

This particular chromosome had half the amount of sequencing data, which indicated there was only one copy.

To confirm, the researchers sorted through other octopus genomic data previously collected by other researchers.

They found another example of the half-sized chromosome in another species of octopus. They also found it in squid, which diverged evolutionarily from octopuses somewhere between 248 and 455 million years ago. And after more digging, they also found evidence for the chromosome in the nautilus, a mollusk that split apart from the octopus approximately 480 million years ago.

The fact that these species share this unique chromosome suggests that it's been around in some form for a very long time.

This indicates that their common ancestor had this similar sex determination system.

That's somewhat unusual for sex chromosomes. Because they directly impact reproductive capabilities, they're subject to a lot of selective pressure and so tend to undergo rapid evolutionary change. But cephalopods seem to have found what works and have stuck with it.

Other ancient sex chromosomes have been discovered in plant groups like mosses and liverworts, which were some of the first plants to evolve. And insect sex chromosomes might be 450 million years old, but they've also changed a lot over time.

Cephalopod Sex Determination and its Ancient Evolutionary Origin, Current Biology (2025). DOI: 10.1016/j.cub.2025.01.005. www.cell.com/current-biology/f … 0960-9822(25)00005-3

Comment by Dr. Krishna Kumari Challa on February 3, 2025 at 1:49pm

Catching the culprits: DNA 'fingerprints' of drug-makers can be linked to capsules and packaging

DNA profiling technologies are rapidly advancing, creating the potential to identify individuals involved in making, packing and transporting illegal capsules by analyzing the exterior of the illicit drugs and the plastic bag in which they are carried.

Experiments carried out by Flinders University forensic science experts have found that DNA accumulates in different areas, depending on an individual's involvement in the process, which could aid identification of people involved in the drug-making and trade.

The work is published in the journal Forensic Science International: Genetics.

The study also found DNA from the surface of capsules can be transferred to the inner surface of ziplock bags (ZLBs) commonly used in transportation.

This small-scale study indicates that capsule packers deposit less DNA than capsule makers who spend more time handling drug casing, and those that make the capsules can leave enough DNA for a complete profile with as little as 30 seconds of contact.

Furthermore, the DNA yield on these commonly used plastic bags is higher when handled by several people compared with little-to-no contact.

"Generating informative DNA profiles from the inside surface of the ziplock bag could be more useful than the outer side, as could be testing of other 'protected' areas of the bag such as the zip or inner edge of the seal.

Illicit substances frequently distributed in secure ziplock bags can be seized by police and tested by forensic investigators.

Strong DNA profiles 're generated for the individual who made the capsules and for the individual responsible for packing the ziplock bag.

Madison Nolan et al, Illicit drug distribution: Evaluation of DNA transfer between ziplock bags and capsules, Forensic Science International: Genetics (2024). DOI: 10.1016/j.fsigen.2024.103182

Comment by Dr. Krishna Kumari Challa on February 3, 2025 at 1:37pm

Scientists create 'molecular trap' to remove pollutants from water

Scientists have developed a new material that could help reduce water pollution caused by harmful chemicals, such as from leftover medicines and hygiene products, that end up in rivers and lakes.

Water pollution is one of the growing challenges of modern life. Many everyday items, from medications to cosmetics, leave behind residues that don't fully break down after use. These pollutants often find their way into water systems, where they disrupt ecosystems and cause harm to plants, animals and humans.

The research, published in the journal Cell Reports Physical Science, describes a new method using a molecular  structure called a metal-organic cage (MOC). These tiny cages act like traps designed to catch and hold harmful molecules commonly found in our water supplies.

The cages are made up of metal ions  connected by organic molecules forming a hollow pyramid-like structure. These hollow spaces at the center of these structures are where the MOCs trap specific molecules, like pollutants or gases.

The new structure incorporates chemical groups called sulfonates to make it compatible with water, allowing it to function in real-world water systems, like rivers or wastewater.

It uses a natural effect called hydrophobic binding, where contaminant molecules preferentially "stick" to the inside of the cage rather than staying in the water. This allows the material to selectively capture and hold pollutants, even in challenging water environments.

Jack D. Wright et al, Encapsulation of Hydrophobic Pollutants within a Large Water-Soluble [Fe₄L₆]^4- Cage, Cell Reports Physical Science (2025). DOI: 10.1016/j.xcrp.2025.102404

Comment by Dr. Krishna Kumari Challa on February 3, 2025 at 12:01pm

Why the first stars couldn't grow forever

Star formation in the early universe was a vigorous process that created gigantic stars. Called Population III stars, these giants were massive, extremely luminous stars that lived short lives, many of which ended when they exploded as primordial supernovae.

But even these early stars faced growth limitations.

Stellar feedback plays a role in modern star formation. As young stars grow, they emit powerful radiation that can disperse nearby gas they need to keep growing. This is called protostellar radiative feedback, and it takes place in addition to the restrictive effect their magnetic fields have on their growth.

However, new research shows that the growth of Pop III stars was limited by their magnetic fields.

The research is titled "Magnetic fields limit the mass of Population III stars even before the onset of protostellar radiation feedback"

The paper is published on the arXiv preprint server.

Piyush Sharda et al, Magnetic fields limit the mass of Population III stars even before the onset of protostellar radiation feedback, arXiv (2025). DOI: 10.48550/arxiv.2501.12734

Comment by Dr. Krishna Kumari Challa on February 3, 2025 at 11:58am

Microplastics found in the brains of mice within hours of consumption

A team of environmental biologists  has found that it takes microplastics consumed by mice just a few hours to make their way to their brains.

In their paper published in the journal Science Advances, the group describes experiments they conducted with lab mice consuming water tainted with different sized microplastics, and what they learned by doing so.

Prior research has shown that microplastics have made their way into the environment to such an extent that they have made their way into the bodies of nearly everyone on Earth (*). It is still not known what harm consumption of such materials causes, but most in the medical field believe they are likely causing damage that is blamed on other sources. Still, many in the field suggest that there is enough evidence of possible health problems associated with microplastics that action should be taken globally to address their impact.

In this new effort, the research team sought to learn more about the medical impact of a mammal consuming different sizes of microplastics. The experiments consisted of feeding test mice water with different sized bits of fluorescent plastic in it, from micro to nano. They then tracked the progress of the plastic bits to see where they wound up in the bodies of the mice.

Knowing that the plastic would make its way from the digestive tract into the bloodstream, the researchers used two-photon microscopy to capture imagery of it inside blood vessels. Also, suspecting that the tiniest bits would make it into their brains, the team installed tiny windows in their skulls, allowing them to track the movement of the plastic in their brains.

In studying the imagery they created, the researchers were able to watch as the plastics made their way around the mice's bodies, eventually reaching their brains. They also noted that the plastic bits tended to get backed up, like cars in a traffic jam at different points. In taking a closer look at some of the backups in the brain, the researchers found that the plastic bits had been captured by immune cells, which led to even more backups.

Wondering if the plastic in their brains was causing any impairment, the researchers tested several of the mice and found that many of them experienced memory loss, reductions in motor skills and lower endurance.

*  Richard C. Thompson, Twenty years of microplastics pollution research—what have we learned?, Science (2024). DOI: 10.1126/science.adl2746. www.science.org/doi/10.1126/science.adl2746

Haipeng Huang et al, Microplastics in the bloodstream can induce cerebral thrombosis by causing cell obstruction and lead to neurobehavioral abnormalities, Science Advances (2025). DOI: 10.1126/sciadv.adr8243

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