Comment

Comment by Dr. Krishna Kumari Challa yesterday

World's oldest host-associated bacterial DNA found

An international team led by researchers at the Center for Paleogenetics, has uncovered microbial DNA preserved in woolly and steppe mammoth remains dating back more than one million years. The analyses reveal some of the world's oldest microbial DNA ever recovered, as well as the identification of bacteria that possibly caused disease in mammoths. The findings are published in Cell.

Researchers analyzed microbial DNA from 483 mammoth specimens, of which 440 were sequenced for the first time. Among them was a steppe mammoth that lived about 1.1 million years ago. Using advanced genomic and bioinformatic techniques, the team distinguished microbes that once lived alongside the mammoths from those that invaded their remains after death.

 Ancient Host-Associated Microbes obtained from Mammoth Remains, Cell (2025). DOI: 10.1016/j.cell.2025.08.003. www.cell.com/cell/fulltext/S0092-8674(25)00917-1

Comment by Dr. Krishna Kumari Challa yesterday

8,000 years of human activities have caused wild animals to shrink and domestic animals to grow

Humans have caused wild animals to shrink and domestic animals to grow, according to a new study. 

Researchers studied tens of thousands of animal bones from Mediterranean France covering the last 8,000 years to see how the size of both types of animals has changed over time.

Scientists already know that human choices, such as selective breeding, influence the size of domestic animals, and that environmental factors also impact the size of both. However, little is known about how these two forces have influenced the size of wild and domestic animals over such a prolonged period. This latest research, published in the Proceedings of the National Academy of Sciences , fills a major gap in our knowledge.

The scientists analyzed more than 225,000 bones from 311 archaeological sites in Mediterranean France. They took thousands of measurements of things like the length, width, and depth of bones and teeth from wild animals, such as foxes, rabbits and deer, as well as domestic ones, including goats, cattle, pigs, sheep and chickens.

But the researchers didn't just focus on the bones. They also collected data on the climate, the types of plants growing in the area, the number of people living there and what they used the land for. And then, with some sophisticated statistical modeling, they were able to track key trends and drivers behind the change in animal size.

The research team's findings reveal that for around 7,000 years, wild and domestic animals evolved along similar paths, growing and shrinking together in sync with their shared environment and human activity. However, all that changed around 1,000 years ago. Their body sizes began to diverge dramatically, especially during the Middle Ages.

Domestic animals started to get much bigger as they were being actively bred for more meat and milk. At the same time, wild animals began to shrink in size as a direct result of human pressures, such as hunting and habitat loss. In other words, human activities replaced environmental factors as the main force shaping animal evolution.

 Mureau, Cyprien et al, 8,000 years of wild and domestic animal body size data reveal long-term synchrony and recent divergence due to intensified human impact, Proceedings of the National Academy of Sciences (2025). DOI: 10.1073/pnas.2503428122. www.pnas.org/cgi/doi/10.1073/pnas.2503428122

Comment by Dr. Krishna Kumari Challa on Tuesday

Hyperactive blood platelets linked to heart attacks despite standard drug therapy

Scientists  have discovered a particularly active subgroup of blood platelets that may cause heart attacks in people with coronary heart disease despite drug therapy. This discovery may open up new prospects for customized therapies. The research results are published in the European Heart Journal and were presented on August 31 at Europe's largest cardiology congress.

Despite modern medication, many people with coronary heart disease continue to suffer heart attacks. A research team  has now found a possible explanation for this and has also provided a very promising therapeutic approach.

Their work focused on so-called "reticulated platelets": particularly young, RNA-rich and reactive thrombocytes that play a central role in the formation of blood clots in patients with coronary heart disease.

The researchers were able to comprehensively characterize the biological mechanisms of these cells for the first time. This allows us to explain why these platelets remain overactive in many patients even under optimal therapy. The reason is that these young platelets have a particularly large number of activating signaling pathways that make them more sensitive and reactive than mature platelets.

The results come from a multidimensional, using various methods, analysis of the blood of over 90 patients with coronary heart disease. Among other things, the researchers found signaling pathways that can be used to specifically inhibit the activity of such blood cells, in particular two target structures called GPVI and PI3K. Initial laboratory experiments confirmed that inhibiting these signaling pathways can reduce platelet hyperactivity.

 Kilian Kirmes et al, Reticulated platelets in coronary artery disease: a multidimensional approach unveils prothrombotic signalling and novel therapeutic targets, European Heart Journal (2025). DOI: 10.1093/eurheartj/ehaf694

Comment by Dr. Krishna Kumari Challa on Tuesday

The reason why there are high levels of neutrophils in the meninges is unclear. One explanation could be that they are recruited by microglia, a type of immune cell unique to the brain.

Another possible explanation is that chronic stress may cause microhemorrhages, tiny leaks in brain blood vessels, and that neutrophils—the body's 'first responders'—arrive to fix the damage and prevent any further damage. These neutrophils then become more rigid, possibly getting stuck in brain capillaries and causing further inflammation in the brain.

These new findings show that these 'first responder' immune cells leave the skull bone marrow and travel to the brain, where they can influence mood and behavior.

Stacey L. Kigar et al, Chronic social defeat stress induces meningeal neutrophilia via type I interferon signaling in male mice, Nature Communications (2025). DOI: 10.1038/s41467-025-62840-5

Part 2

Comment by Dr. Krishna Kumari Challa on Tuesday

Depression linked to presence of immune cells in the brain's protective layer

Immune cells released from bone marrow in the skull in response to chronic stress and adversity could play a key role in symptoms of depression and anxiety, say researchers.

The discovery—found in a study in mice—sheds light on the role that inflammation can play in mood disorders and could help in the search for new treatments, in particular for those individuals for whom current treatments are ineffective.

Around 1 billion people will be diagnosed with a mood disorder such as depression or anxiety at some point in their life. While there may be many underlying causes, chronic inflammation—when the body's immune system stays active for a long time, even when there is no infection or injury to fight—has been linked to depression. This suggests that the immune system may play an important role in the development of mood disorders.

Previous studies have highlighted how high levels of an immune cell known as a neutrophil, a type of white blood cell, are linked to the severity of depression. But how neutrophils contribute to symptoms of depression is currently unclear.

In research published in Nature Communications, a team of scientists  tested the hypothesis that chronic stress can lead to the release of neutrophils from bone marrow in the skull. These cells then collect in the meninges—membranes that cover and protect your brain and spinal cord—and contribute to symptoms of depression.

As it is not possible to test this hypothesis in humans, the team used mice exposed to chronic social stress. In this experiment, an 'intruder' mouse is introduced into the home cage of an aggressive resident mouse. The two have brief daily physical interactions and can otherwise see, smell, and hear each other.

The researchers found that prolonged exposure to this stressful environment led to a noticeable increase in levels of neutrophils in the meninges, and that this was linked to signs of depressive behavior in the mice. Even after the stress ended, the neutrophils lasted longer in the meninges than they did in the blood.

Analysis confirmed the researchers' hypothesis that the meningeal neutrophils—which appeared subtly different from those found in the blood—originated in the skull.

Further analysis suggested that long-term stress triggered a type of immune system 'alarm warning' known as type I interferon signaling in the neutrophils. Blocking this pathway—in effect, switching off the alarm—reduced the number of neutrophils in the meninges and improved behavior in the depressed mice.

Further analysis suggested that long-term stress triggered a type of immune system 'alarm warning' known as type I interferon signaling in the neutrophils. Blocking this pathway—in effect, switching off the alarm—reduced the number of neutrophils in the meninges and improved behavior in the depressed mice.

--

Part 1

Comment by Dr. Krishna Kumari Challa on Tuesday

In a second study, the working group also identified the changes in the brain that are associated with criminal behavior in frontotemporal dementia. This study was published in Human Brain Mapping.

Persons exhibiting criminal behavior showed larger atrophy in the temporal lobe, indicating that criminal behavior might be caused by so-called disinhibition, i.e., the loss of normal restraints or inhibitions, leading to a reduced ability to regulate one's behavior, impulses, and emotions.

Disinhibition can manifest as acting impulsively, without thinking through the consequences, and behaving in ways that are inappropriate for the situation.

One has to prevent a further stigmatization of persons with dementia. Of note, most offenses committed were minor, such as indecent behavior, traffic violations, theft, damage to property, but also physical violence or aggression occurred

Hence, sensitivity for this topic as possible early signs of dementia and earliest diagnosis and treatment are of the uttermost importance. Besides early diagnosis and treatment of persons affected, one has to discuss adaptations of the legal system, such as increasing awareness of offenses due to those diseases, and taking into account diseases in respective penalties and in jails, say the researchers.

 Matthias L. Schroeter et al, Criminal minds in dementia: A systematic review and quantitative meta-analysis, Translational Psychiatry (2025). DOI: 10.1038/s41398-025-03523-z

Karsten Mueller et al, Criminal Behavior in Frontotemporal Dementia: A Multimodal MRI Study, Human Brain Mapping (2025). DOI: 10.1002/hbm.70308

Part 2

Comment by Dr. Krishna Kumari Challa on Tuesday

Criminal behavior in patients with dementia

Don't blame the criminals for everything they do. 

A suspected perpetrator who can barely remember his name, several traffic violations committed by a woman in her mid-fifties who is completely unreasonable and doesn't understand her behavior—should such cases be brought before a court? And how does the state deal with people who commit acts of violence without meaning to?

Those questions come to mind if one hears those examples from everyday clinical praxis with persons suffering from dementia. Neurodegenerative diseases might affect several functions of the brain, ranging from memory in Alzheimer's disease to behavior, such as in behavioral variant frontotemporal dementia, and to sensorimotor function in Parkinson's disease.

One of the most interesting consequences of these alterations is the fact that persons affected by these diseases might develop criminal risk behavior like harassment, traffic violation, theft or even behavior causing harm to other people or animals, even as the first disease sign.

If persons violate social or legal norms due to changes in behavior, personality and cognition, these incidents may have a substantial impact on this person's family and social surroundings and may lead to prosecution.

Researchers  investigated this problem in a broad meta-analysis that included 14 studies with 236,360 persons from different countries (U.S.A., Sweden and Finland, Germany and Japan). The work is published in the journal Translational Psychiatry.

Their systematic literature review revealed that criminal risk behavior prevalence is more frequent in early disease course than in the general population, but declines thereafter below population levels. Therefore, criminal behavior committed for the first time at mid-age could be an indicator of incident dementia, requiring earliest diagnosis and therapy.

The team shows that the prevalence of criminal risk behaviors was highest in behavioral variant frontotemporal dementia (>50%), followed by semantic variant primary progressive aphasia (40%), but rather low in vascular dementia and Huntington's disease (15%), Alzheimer's disease (10%), and lowest in Parkinsonian syndromes (<10%).

Criminal risk behavior in frontotemporal dementia is most likely caused by the neurodegenerative disease itself. Most of the patients showed criminal risk behavior for the first time in their life and had no previous records of criminal activity.

The prevalence seems to be more frequent in frontotemporal dementia and Alzheimer's disease in early disease course than in the general population before diagnosis, presumably in pre-stages, such as mild behavioral or cognitive impairment, but declines thereafter, finally leading to lower prevalence in dementia after diagnosis if compared with the general population.

The researchers also found that criminal risk behaviour is more frequent in men than in women in dementia. After diagnosis, men showed four times more criminal risk behaviour than women in frontotemporal dementia and seven times more in Alzheimer's disease.

Part 1

Comment by Dr. Krishna Kumari Challa on Tuesday

Neuroscientists show for first time that precise timing of nerve signals determines how brain processes information

It has long been known that the brain preferentially processes information that we focus our attention on—a classic example is the so-called cocktail party effect.

In an environment full of voices, music, and background noise, the brain manages to concentrate on a single voice. The other noises are not objectively quieter, but are perceived less strongly at that moment.

The brain focuses its processing on the information that is currently relevant—in this case, the voice of the conversation partner—while other signals are received but not forwarded and processed to the same extent.

Neuroscientists provided the first causal evidence of how the brain transmits and processes relevant information. The work is published in the journal Nature Communications.

Whether a signal is processed further in the brain depends crucially on whether it arrives at the right moment—during a short phase of increased receptivity of the nerve cells. 

Nerve cells do not work continuously, but in rapid cycles. They are particularly active and receptive for a few milliseconds, followed by a window of lower activity and excitability. This cycle repeats itself approximately every 10 to 20 milliseconds. Only when a signal arrived shortly before the peak of this active phase did it change the behaviour of the neurons.

This temporal coordination is the fundamental mechanism of information processing. Attention makes targeted use of this phenomenon by aligning the timing of the nerve cells so that relevant signals arrive precisely in this time window, while others are excluded.

 Eric Drebitz et al, Gamma-band synchronization between neurons in the visual cortex is causal for effective information processing and behavior, Nature Communications (2025). DOI: 10.1038/s41467-025-62732-8

Comment by Dr. Krishna Kumari Challa on Tuesday

Scientists find that ice generates electricity when bent

A new study  reveals that ice is a flexoelectric material, meaning it can produce electricity when unevenly deformed. Published in Nature Physics, this discovery could have major technological implications while also shedding light on natural phenomena such as lightning.

Frozen water is one of the most abundant substances on Earth. It is found in glaciers, on mountain peaks and in polar ice caps. Although it is a well-known material, studying its properties continues to yield fascinating results.

An international study has shown for the first time that ordinary ice is a flexoelectric material.

In other words, it can generate electricity when subjected to mechanical deformation. This discovery could have significant implications for the development of future technological devices and help to explain natural phenomena such as the formation of lightning in thunderstorms.

The study represents a significant step forward in our understanding of the electromechanical properties of ice.

The scientists  discovered that ice generates  electric charge in response to mechanical stress at all temperatures. In addition, they identified a thin 'ferroelectric' layer at the surface at temperatures below -113ºC (160K).

This means that the ice surface can develop a natural electric polarization, which can be reversed when an external electric field is applied—similar to how the poles of a magnet can be flipped. The surface ferroelectricity is a cool discovery in its own right, as it means that ice may have not just one way to generate electricity, but two: ferroelectricity at very low temperatures, and flexoelectricity at higher temperatures all the way to 0 °C.

This property places ice on a par with electroceramic materials such as titanium dioxide, which are currently used in advanced technologies like sensors and capacitors.

One of the most surprising aspects of this discovery is its connection to nature. The results of the study suggest that the flexoelectricity of ice could play a role in the electrification of clouds during thunderstorms, and therefore in the origin of lightning.

It is known that lightning forms when an electric potential builds up in clouds due to collisions between ice particles, which become electrically charged. This potential is then released as a lightning strike. However, the mechanism by which ice particles become electrically charged has remained unclear, since ice is not piezoelectric—it cannot generate charge simply by being compressed during a collision.

However, the study shows that ice can become electrically charged when it is subjected to inhomogeneous deformations, i.e. when it bends or deforms irregularly.

X. Wen et al, Flexoelectricity and surface ferroelectricity of water ice, Nature Physics (2025). DOI: 10.1038/s41567-025-02995-6

Comment by Dr. Krishna Kumari Challa on Tuesday

Why male embryos grow faster

Researchers have uncovered the genetic triggers that cause male and female bovine embryos to develop differently, as early as seven to eight days after fertilization. The breakthrough in basic science has implications for human health—such as drug development and in vitro fertilization—and for bovine health and dairy industry sustainability.

Scientists have known since the 1990s that male embryos of multiple mammalian species, including humans, grow faster than female embryos, but until now, the underlying reasons were unclear.

In a paper, published in Cell & Bioscience,  scientists grew bovine embryos in petri dishes, then analyzed their genetic sex and RNA sequencing, which shows how genes are being expressed.

They discovered significant sex differences in gene regulation: male embryos prioritized genes associated with energy metabolism, causing them to grow faster than their female counterparts. Female embryos emphasized genes associated with sex differentiation, gonad development and inflammatory pathways that are important for future development.

Understanding these fundamental sex differences at the genomic and molecular levels is critically important to improving in vitro fertilization (IVF) success in humans and cows, and in developing treatments that will work for both men and women.

Meihong Shi et al, Sex-biased transcriptome in in vitro produced bovine early embryos, Cell & Bioscience (2025). DOI: 10.1186/s13578-025-01459-x

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