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Comment by Dr. Krishna Kumari Challa on Thursday

Genes influence the microbes in our mouths to shape dental health

No matter how much they brush their teeth, some people still get more cavities than others, in part because of differences in genetics and the make-up of the microbes in their mouths. A new study has found human genetic factors that influence the oral microbiome and may increase risk of cavities and tooth loss in some people.

The abundance of many bacterial species in our mouths is strongly influenced by human genetics. We know that the microbial environment in one person's mouth is going to be quite different from another person's mouth due to many factors, but genetics is a pretty strong one.
Human genetic variation significantly influences the composition of the oral microbiome, affecting susceptibility to cavities and tooth loss. Specific genes, such as AMY1 and FUT2, are linked to changes in the abundance of numerous oral bacterial species. These genome-to-genome interactions shape oral health outcomes, with AMY1 copy number correlating with increased risk of tooth decay and denture use.

The study, led by scientists at the Broad Institute and Mass General Brigham, found a surprisingly large effect of human genetics on the abundance of microbes in the mouth. The researchers discovered genome-to-genome interactions between human DNA and the DNA of the oral microbiome. For example, they found that a human gene, AMY1, was strongly linked to the composition of the oral microbial community, and even to denture use, suggesting that the relationship between this gene and the bacteria in the mouth plays a role in oral health.

The paper, published in Nature, is an analysis of the largest collection of oral microbiome profiles to date.

To find human-microbiota associations, the team analyzed whole-genome sequences from saliva-derived DNA from more than 12,500 individuals. Typically, the microbial DNA in human samples is tossed aside, but the team found a new purpose for the bacterial data sequenced together with each human genome. They measured the abundances of 439 common microbial species, and found 11 regions of the human genome associated with differences in the levels of dozens of species of bacteria in the mouth.

They also found that the same 11 human loci influence natural selection on dozens of different bacterial genes, so it seems like there's a lot of interaction between human genetics and the oral microbiome,

Notably, the scientists found the strongest relationship between a genetic variant that breaks the FUT2 gene—which has previously been linked to gut microbiome composition—and the levels of 58 oral bacterial species.

Nolan Kamitaki, Human and bacterial genetic variation shape oral microbiomes and health, Nature (2026). DOI: 10.1038/s41586-025-10037-7. www.nature.com/articles/s41586-025-10037-7

Comment by Dr. Krishna Kumari Challa on Thursday

What causes chronic pain? New study identifies key culprit in the brain

About one in four adults have chronic pain and nearly one in 10 people say chronic pain interferes with their daily life and work.

Those with nerve-related pain often suffer from a condition called allodynia, an extreme sensitivity in which even light touch hurts.

Acute and chronic pain work differently. Acute pain serves as a temporary warning sign, initiated when an injured tissue—like a stubbed toe—sends a signal to the spinal cord and onward to the brain's pain center. Chronic pain is more like a false alarm, in which pain signals persist in the brain for weeks, months or years after the initial tissue injury has healed.

Earlier work suggested that the CGIC—a sugar-cube-sized cluster of cells hidden deep within the folds of a portion of the human brain called the insula—plays an important role in allodynia. Human studies have also shown that chronic pain patients have an overactive CGIC.

A neural circuit hidden in an understudied region of the brain plays a critical role in turning temporary pain into pain that can last months or years, according to new  research.

The animal study, published in The Journal of Neuroscience, found that silencing this pathway, known as the caudal granular insular cortex (CGIC), can prevent or halt chronic pain.

The researchers discovered that while the CGIC plays a minimal role in processing acute pain, it plays a vital role in making pain persist.

According to the study, the CGIC signals the brain's pain processing center, or somatosensory cortex, which in turn tells the spinal cord to keep the pain going.

When the team turned off cells within this pathway immediately after injury, the rat's pain from injury was short-lived. In animals already experiencing chronic allodynia, disabling this pathway made the pain cease.

Now that scientists have access to tools that allow you to manipulate the brain, not based just on a general region but on specific sub-populations of cells, the quest for new treatments is moving much faster.

Jayson B. Ball et al, Caudal Granular Insular Cortex to Somatosensory Cortex I: A critical pathway for the transition of acute to chronic pain, The Journal of Neuroscience (2025). DOI: 10.1523/jneurosci.1306-25.2025

Comment by Dr. Krishna Kumari Challa on Thursday

No more jet lag! Scientists discover oral compound that helps 'reset' the body clock forward

A  research team has discovered a new compound that can advance the body's internal clock—offering hope for faster recovery from jet lag and better adaptation to night-shift work. The compound, called Mic-628, specifically activates the transcription of a clock gene named Period1 (Per1). When given orally to mice, it advanced their body clocks and activity rhythms, regardless of dosing time.

Mathematical modeling revealed that the compound's stable and unidirectional phase-advancing effect is mediated by a negative auto-regulatory feedback of the PER1 protein itself.

Adapting to eastward travel, such as west-to-east transmeridian flights, or to night-shift work requires advancing the internal clock, a process that normally takes longer and is physiologically harder than delaying it.

Existing methods, such as light therapy or melatonin, are heavily constrained by timing and often yield inconsistent results. Mic-628's consistent phase-advance effect, regardless of when it is administered, represents a new pharmacological strategy for resetting the circadian clock.

The findings, published in the journal Proceedings of the National Academy of Sciences, suggest a new approach to controlling circadian rhythms through drug action rather than light exposure.

The researchers plan to investigate the safety and efficacy of Mic-628 in further animal and human studies. Because it reproducibly advances the body clock through a well-defined molecular mechanism, Mic-628 may serve as a prototype "smart drug" for managing jet lag, shift work-related sleep problems, and other circadian misalignment disorders.

Yoshifumi Takahata et al, A Period1 inducer specifically advances circadian clock in mice, Proceedings of the National Academy of Sciences (2026). DOI: 10.1073/pnas.2509943123

Comment by Dr. Krishna Kumari Challa on Thursday

Scientists grow specialized nerve cells that degenerate in ALS and are damaged in spinal cord injury
A method has been developed to direct cortical progenitor cells, specifically SOX6+/NG2+ cells, to differentiate into corticospinal-like neurons in vitro. These lab-grown neurons exhibit key molecular and functional features of native corticospinal neurons, which are affected in ALS and spinal cord injury, providing a foundation for future disease modelling and regenerative research.

Directed differentiation of functional corticospinal-like neurons from endogenous SOX6+/NG2+ cortical progenitors, eLife (2026). DOI: 10.7554/eLife.100340.3

Comment by Dr. Krishna Kumari Challa on Thursday

Fast-growing trees are taking over the forests of the future and putting biodiversity, climate resilience under pressure
Forests are increasingly dominated by fast-growing tree species, while slow-growing, specialized species face heightened risk of extinction, especially in tropical and subtropical regions. This shift leads to reduced biodiversity, ecosystem homogenization, and diminished climate resilience, as fast-growing trees are less stable and store less carbon long-term. Human activities are the main drivers of these changes.

Guo, WY., et al. Global functional shifts in trees driven by alien naturalization and native extinction, Nature Plants (2026). DOI: 10.1038/s41477-025-02207-2

Comment by Dr. Krishna Kumari Challa on Thursday

Environmental trade-offs of biodegradable plastics revealed
Replacing conventional plastics with biodegradable alternatives could reduce ecotoxicity by up to 34% and global waste accumulation by up to 65% by 2050, provided proper waste management systems like industrial composting are in place. Without such infrastructure, greenhouse gas emissions could double. Biodegradable plastics also increase water use, highlighting the need for improved disposal systems and labeling.

Zhengyin Piao et al, The role of biodegradable plastics in the global plastic future, Nature Reviews Clean Technology (2026). DOI: 10.1038/s44359-025-00142-1

Comment by Dr. Krishna Kumari Challa on Thursday

Which countries are paying the highest price for particulate air pollution?

Polluted air causes an estimated 7 million deaths worldwide each year, according to the World Health Organization. Much of the mortality comes from PM_2.5, particulate pollution smaller than 2.5 micrometers in diameter that can enter the lungs and bloodstream and cause respiratory and cardiovascular problems. In addition to particles emitted directly into the atmosphere, ammonia (NH₃), nitrogen oxides (NO_X), and sulfur dioxide (SO₂), which are emitted by factories, ships, cars, and power plants, are all precursors that can contribute to the formation of PM_2.5. The effects of particulate pollution are not evenly distributed, however.

The largest mortality reductions came from China and India, where cutting emissions would save 184,000 and 124,000 lives, respectively, each year. The largest cost savings were found in China, followed by Europe and North America. Health benefits also varied by type of emissions and sector. NH₃ causes more issues in China, whereas NO_X is relatively more harmful in Europe than in other places.

The authors note that caution is warranted when comparing results across similar studies, in part because the link between pollutant concentrations and health outcomes is not always linear and in part because different regions may have different methodologies when accounting for emissions by sector. Also, their study focuses only on PM_2.5-related mortality and does not consider other pollutants, such as ozone. Overall, they suggest their work offers a meaningful reference for comparing the effects of different pollutant mitigation strategies in the Northern Hemisphere.

Y. B. Oztaner et al, Source Attribution of PM_2.5Health Benefits Over Northern Hemisphere Using Adjoint of Hemispheric CMAQ, GeoHealth (2026). DOI: 10.1029/2025gh001533

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Comment by Dr. Krishna Kumari Challa on Thursday

Microplastics found in a third of surveyed fish off the coasts of remote Pacific Islands
Microplastics were detected in about one-third of coastal fish from Pacific Island Countries and Territories, with Fiji showing contamination in nearly 75% of sampled fish—well above the global average. Reef and bottom-dwelling species, especially those feeding on invertebrates, had higher contamination rates. The findings highlight vulnerabilities in remote regions and underscore the need for stronger global plastic regulations.

Dehm J, et al. Considering ecological traits of fishes to understand microplastic ingestion across Pacific coastal fisheries, PLOS One (2026). DOI: 10.1371/journal.pone.0339852

Comment by Dr. Krishna Kumari Challa on Thursday

Neuron position found less crucial for brain connectivity than once thought

The human brain contains billions of connected neurons that collectively support different mental functions, including the processing of sensory information, the encoding of memories, attention processes, and decision-making. For a long time, neuroscientists have assumed the position of specific neurons in the brain plays a key role in the brain's connectivity and proper functioning.

Researchers recently gathered evidence that contradicts this long-standing assumption, showing misplaced neurons can still retain their "identity," connect with other neurons and support the processing of sensory information.

Their paper, published in Nature Neuroscience, could reshape the present understanding of developmental disorders and other conditions linked to the rearrangement of neurons or cortical malformations.

When they were conducting experiments focusing on brain malformations known as cortical heterotopias, the researchers were surprised to discover that alterations in the brain's structural organization did not appear to alter neurons or prevent them from connecting with other neurons.

This inspired them to widen the scope of their investigation, to determine if the position of neurons contributes to the brain's connectivity and function.

Contrary to their original expectations, the researchers observed that the rearrangement of neurons does not impair the brain's connectivity and functions. This finding could have important implications for the understanding and treatment of developmental disorders linked to brain malformations.

Contrary to their original expectations, the researchers observed that the rearrangement of neurons does not impair the brain's connectivity and functions. This finding could have important implications for the understanding and treatment of developmental disorders linked to brain malformations.

This shows that spatial organization is not critical for neuronal identity acquisition and maturation.

Sergi Roig-Puiggros et al, Position-independent emergence of neocortical neuron molecular identity, connectivity and function, Nature Neuroscience (2025). DOI: 10.1038/s41593-025-02142-7.

Comment by Dr. Krishna Kumari Challa on January 28, 2026 at 1:52pm

Scientists once thought the brain couldn't be changed. Now we know different
The adult brain retains the capacity for neuroplasticity, allowing structural and functional changes in response to experience, learning, and injury. This adaptability is shaped by factors such as practice, physical exercise, sleep, and stress, but operates within biological limits. Neuroplasticity is experience-dependent, value-neutral, and persists throughout life, though meaningful change requires sustained effort.

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