Comment

Comment by Dr. Krishna Kumari Challa on December 24, 2025 at 8:31am

The global fish trade is spreading 'forever chemicals' around the world

Eating fish may well be good for you, but it carries a hidden risk of exposure to so-called "forever chemicals." A new study published in the journal Science has revealed that the global seafood trade is acting as a massive delivery system for per- and polyfluoroalkyl substances (PFAS), industrial pollutants that persist in the environment for decades.

These forever chemicals are used in many products, from nonstick cookware and cosmetics to food packaging and firefighting foams. They are extremely resistant to breaking down in the environment and have been linked to a variety of serious illnesses such as cancer and liver disease.

PFAS can travel long distances around the planet in the air and through water. Once they wash into the ocean, they are absorbed by tiny organisms at the bottom of the food chain, such as plankton and algae. Because these chemicals do not break down, they accumulate in their bodies, and when small fish eat them, the toxic substances pass up the food chain. Large predatory fish, the kind that end up on our dinner plates, eat these smaller marine creatures, and as a result, the chemical concentrations build up in their tissues and organs.

In their paper, the researchers set out to map how these chemicals move once they are inside the fish. They built a computer model covering 212 different species to track how toxins accumulate up the food chain and then validated this with lab tests on fish from numerous countries. Then the team combined this data with global trade records to see how the fish and PFAS travel from one country to another.

One of the most significant findings was that the international fish trade acts like a global conveyor belt, redistributing PFAS from contaminated regions to consumers thousands of miles away.
Before this study, it was generally assumed that forever chemicals were a local problem. If your country's rivers and seas were clean, then so were the fish. However, a nation with clean water can still be exposed to high levels of PFAS through the seafood it imports from other parts of the world. For example, researchers found that Italians buy only 11% of their fish from Sweden, yet this accounts for more than 35% of their PFAS exposure.

Given that this problem doesn't respect borders, researchers argue that a unified global strategy is needed to protect public health.

Wenhui Qiu et al, Risks of per- and polyfluoroalkyl substance exposure through marine fish consumption, Science (2025). DOI: 10.1126/science.adr0351

Jennifer Sun et al, Reevaluating PFAS exposure risks from marine fish, Science (2025). DOI: 10.1126/science.aed7431

Comment by Dr. Krishna Kumari Challa on December 24, 2025 at 8:10am

Brain chemistry can reactivate or suppress dormant HIV

Human immunodeficiency virus (HIV) infections are still fairly common and an estimated 40 million people worldwide are currently living with this condition. The HIV virus attacks the body's immune system and thus makes those who contract it more vulnerable to a wide range of infections.

While there is still no known cure for HIV, there are now various treatment options that allow affected patients to live long and healthy lives. When treated with antiretroviral therapy (ART), the virus is known to remain in a latent state, essentially 'hiding' inside cells and forming a reservoir of dormant virus. If the medication is stopped, however, the virus can be re-awoken, causing severe immune deficiencies again.

Researchers have recently been investigating how the brain, particularly tiny molecules and protein-carrying packages released by cells, influence the persistence of HIV. In a new paper, published in Molecular Psychiatry, they presented new findings that shed new light on molecular mechanisms that can either re-ignite or suppress latent HIV.

In their experiments the researchers found that ECs collected from the brains of SIV-infected but untreated macaques strongly re-activated latent virus reservoirs increasing the activity of viral genes, the production of proteins and causing the virus to spread between cells. Interestingly, however, particles extracted from the brains of infected macaques who were treated with cannabinoids were found to suppress the re-activation of the virus.

"Cannabinoids have been shown to inhibit neuroinflammation," said the authors of the research paper. They showed that cannabinoids exert similar anti-inflammatory effects via EVs and in the current study on ECs, we report that ECs isolated from brains (basal ganglia) of rhesus monkeys have this anti-inflammatory effect and that cannabinoids modulate the cargos of the ECs, with resultant effects on latent HIV reservoirs.

Overall, the findings gathered by these researchers suggest that the brain's chemistry, particularly ECs, do play a key role in the reactivation or suppression of dormant HIV. In the future, their work could pave the way for the development of new drugs and therapeutic interventions aimed at better managing, or perhaps even curing, HIV infections.

Wasifa Naushad et al, Extracellular condensates (ECs) are endogenous modulators of HIV transcription and latency reactivation, Molecular Psychiatry (2025). DOI: 10.1038/s41380-025-03354-w.

Comment by Dr. Krishna Kumari Challa on December 24, 2025 at 8:04am

The team's findings will need to be validated in humans before they can be reliably translated into psychiatric and medical insight. In the future, however, they could potentially help to identify promising pathways for the treatment of depression in patients diagnosed with BD, which are designed to alter their gut microbiota.

Anying Tang et al, Gut microbiota modulates synaptic plasticity, connectivity, and dopamine transmission in the VTA-mPFC pathway in bipolar depression, Molecular Psychiatry (2025). DOI: 10.1038/s41380-025-03398-y.

Part 2

Comment by Dr. Krishna Kumari Challa on December 24, 2025 at 8:04am

Gut bacteria may play role in bipolar depression by directly influencing brain connectivity

Bipolar disorder (BD) is a psychiatric disorder characterized by extreme mood changes. Individuals diagnosed with BD typically alternate between periods of high energy, euphoria, irritability and/or impulsivity (i.e., manic episodes) and others marked by feelings of sadness, low energy, and hopelessness (i.e., depression).

While there are now several medications that can help patients to manage the disorder and stabilize their mood, many of these drugs have side effects and dosages often need to be periodically adjusted. Recent studies suggest that the bacteria and microorganisms living in the digestive system, also known as gut microbiota, play a key role in mental health and might also contribute to some symptoms of BD.

Researchers  recently carried out a study investigating the possible connection between gut microbiota and the depressive episodes experienced by people diagnosed with BD. Their findings, published in Molecular Psychiatry, suggest that the microorganisms in the digestive system can directly influence connections between specific brain regions known to be affected by BD depression.

Adequate evidence has shown that gut microbial dysbiosis is an emerging disease phenotype of BD and is closely related to clinical symptoms of this intractable disease, wrote the researchers in their paper.

To explore the link between gut microbiota and BD depression, the researchers collected gut bacteria from individuals diagnosed with BD who were going through a depressive phase. They then transplanted these bacteria into the digestive system of healthy mice.

They found that bipolar depression-like mice presented with a decrease in the density of dendrite spines in medial prefrontal neurons, and translation post-synapse as a key contributor to the changes in synaptic plasticity.

In addition, analysis of synaptic connectivity in the mPFC revealed that compared to control mice, fewer connections were observed between ventral tegmental area and mPFC glutamate neurons and dopamine response was decreased in BD mice.

Notably, the researchers found that after they received the microbiota taken from individuals who were experiencing BD depression, the mice also started exhibiting depression-like behaviors. In addition, neurons in two brain regions known to be implicated in mood regulation, namely the ventral tegmental area (VTA) and the medial prefrontal cortex (mPFC), appeared to be less connected with each other.

The team also observed disruptions in the production of proteins and reduced dopamine signaling. Dopamine signaling (i.e., the release of dopamine) is essential for maintaining motivation and emotional regulation.

The results of this study confirm that microorganisms and bacteria in the gut can influence the connections between neurons in different brain regions. These altered connections could in turn have an impact on motivation, mood regulation and the processing of emotions.

Part1

Comment by Dr. Krishna Kumari Challa on December 23, 2025 at 9:40am

Whale, dolphin strandings show widespread disease, trauma
Analysis of 272 cetacean strandings in the Pacific Islands from 2006 to 2024 found that over 65% involved disease or human-caused trauma. Disease accounted for 62% of cases, with infectious agents like morbillivirus and brucella affecting multiple species. Human-related trauma, including vessel strikes and debris ingestion, contributed to 29% of strandings.

From land-borne pathogens to high-speed vessel strikes, Pacific whales and dolphins are caught in a "perfect storm" where human-caused trauma and infectious diseases were found in more than 65% of investigated strandings.

A study spanning nearly two decades by  researchers provides insights into the threats whales and dolphins face in the Pacific Islands.

Based on 272 stranding investigations of 20 cetacean species between 2006 and 2024, the study provides foundational data to better manage and conserve Hawaiʻi's whales and dolphins. The findings are published in the journal Diseases of Aquatic Organisms.

Over 18 years, scientists examined more than three-quarters of the stranded whales and dolphins to understand why they died. Most cases (62%) were linked to diseases, and about half of those animals were in poor body condition due to long-term illness.
Infectious agents proved to be a significant threat, affecting 11 different species, including striped dolphins and Longman's beaked whales. Two of the most concerning pathogens were morbillivirus and brucella, which can cause serious brain and lung problems in marine mammals.

Toxoplasmosis—a parasite that infects warm-blooded animals and spreads through cat feces across the environment—was responsible for the deaths of two spinner dolphins and one bottlenose dolphin.

The study revealed that 29% of all strandings were linked to anthropogenic (human-caused) trauma. Vessel strikes were a significant risk, resulting in fatal vertebral and skull fractures for seven individuals, including two pygmy sperm whales, two humpback whale calves, a goose-beaked whale, a spinner dolphin and a striped dolphin.

Interactions with marine debris and fisheries were confirmed as fatal in multiple cases, including a sperm whale that died from plastic and fishery debris blocking its stomach and a bottlenose dolphin that died after a fishhook tore into it.

Kristi West et al, Pacific Islands cetaceans: a review of strandings from 2006-2024, Diseases of Aquatic Organisms (2025). DOI: 10.3354/dao03877

Comment by Dr. Krishna Kumari Challa on December 23, 2025 at 9:34am

Comment by Dr. Krishna Kumari Challa on December 23, 2025 at 9:32am

Some mammals can hit pause on a pregnancy—understanding how that happens could help us treat cancer
Embryonic diapause allows some mammals to pause development by activating a molecular brake that suppresses differentiation pathways, maintaining stem cell pluripotency during metabolic stress. This mechanism involves the displacement of Capicua, enabling genes that inhibit the MAP kinase pathway. The findings suggest similar dormancy programs may underlie long-term survival in immune, stem, and cancer cells.

Tuo Zhang et al, Transcriptional derepression of negative regulators of MAP kinase supports maintenance of diapause ES cells in the pluripotent state, Genes & Development (2025). DOI: 10.1101/gad.353143.125

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Comment by Dr. Krishna Kumari Challa on December 23, 2025 at 9:30am

The postcanine dental crown area analysis of the Dmanisi hominin fossils... supports the hypothesis of distinct species coexisting temporally at the site (Homo caucasi and Homo georgicus). This possibility challenges the prevailing model of Homo erectus migration out of Africa..." commented the researchers in their paper.

While the research lends weight to the idea that two species left Africa at roughly the same time, more specimens may be needed before a consensus is reached.

Victor Nery et al, Testing the taxonomy of Dmanisi hominin fossils through dental crown area, PLOS One (2025). DOI: 10.1371/journal.pone.0336484

Part 2

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Comment by Dr. Krishna Kumari Challa on December 23, 2025 at 9:29am

Two ancient human species came out of Africa together, not one, suggests new study

The textbook version of the "Out of Africa" hypothesis holds that the first human species to leave the continent around 1.8 million years ago was Homo erectus. But in recent years, a debate has emerged suggesting it wasn't a single species, but several. New research published in the journal PLOS One now hopes to settle the matter once and for all.

The debate centers on the Dmanisi fossils, five skulls found in the Republic of Georgia between 1999 and 2005, which belong to some of the oldest humans ever found outside Africa. The problem is that they don't look alike. Some are larger than others, particularly Skull 5, which has a tiny braincase but a massive, protruding face. Some researchers explain this as a difference in sexes within the same species, while others argue that it represents two distinct species living together.

To provide much-needed clarity, researchers studied the teeth of three Dmanisi specimens. The reason is that, generally, skulls are not always the best species identifiers because bone is fragile and can be warped and crushed. Dentition is far more useful because enamel is the hardest biological substance produced by humans, and everything from the shape and size of individual teeth can be used to identify a species.

The team focused on the surface area (dental crown) of the back teeth (premolars and molars) of the Dmanisi specimens that had sufficient dental remains for analysis. They compared these to a database of 122 other fossil specimens, including Australopithecus and several other Homo species. Then, using a statistical sorting tool, they analyzed 583 teeth to create a biological map and determine whether the Dmanisi fossils belonged to a single family or to other branches of our family tree.

The map revealed that these ancient remains were not from a single group. Skull 5, with its large jaw, was grouped with Australopiths, a more primitive ape-like ancestor. The other two specimens were more human-like. Because of this, the study authors support using the names Homo georgicus for Skull 5 and Homo caucasi for the human-like group.
To ensure the differences weren't just between males and females, the team compared the fossils with those of great apes. In some animals, like gorillas, males are much larger than females but still have the same basic teeth. The differences between the Dmanisi teeth were so great that male-female differences within the same group couldn't explain them.
Part 1

Comment by Dr. Krishna Kumari Challa on December 23, 2025 at 8:43am

Scientists chart over 140,000 DNA loops to map human chromosomes in the nucleus
Over 140,000 DNA looping interactions were mapped in human embryonic stem cells and fibroblasts, providing a detailed 3D organization of chromosomes within the nucleus. Computational models now predict genome folding from DNA sequence alone, clarifying how chromatin loops influence gene regulation and how genetic variations may alter genome structure and function.

Job Dekker et al, An integrated view of the structure and function of the human 4D nucleome, Nature (2025). DOI: 10.1038/s41586-025-09890-3

Elzo de Wit, Systematic maps reveal how human chromosomes are organized, Nature (2025). DOI: 10.1038/d41586-025-03808-9

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