Comment

Comment by Dr. Krishna Kumari Challa on March 29, 2025 at 11:02am

They found that population, environment, and language all significantly contribute to the variation in hearing across human groups, but it wasn't clear whether this was due to the whole body being affected by the environment or due to long-term adaptations to varying soundscapes, noise levels, or exposure to pollution.

The researchers suggest that people living in forests could have higher sensitivity because they've adapted to soundscapes with lots of non-human sounds, where vigilance is essential for survival. Or it could be due to being exposed to lower levels of pollution.

People living at higher altitudes may have reduced sensitivity due to a number of reasons, including the impact of lower atmospheric pressure on measurements, potential sound reduction in high altitude environments, or physiological adaptations to lower oxygen levels.

The team also found a difference between urban and rural populations, with those living in cities having a shift towards higher frequencies, possibly due to filtering out low-frequency traffic noise.

Patricia Balaresque et al, Sex and environment shape cochlear sensitivity in human populations worldwide, Scientific Reports (2025). DOI: 10.1038/s41598-025-92763-6

Part 2

Comment by Dr. Krishna Kumari Challa on March 29, 2025 at 11:01am

Women can hear better than men: Researchers find amplitude more influenced by sex than age

Scientists have found that sex is the leading factor explaining differences in hearing sensitivity, with women having significantly more sensitive hearing than men.

Hearing problems are on the rise worldwide, and while hearing sensitivity is well known to decrease with age, little research has been done on the other biological and environmental factors that influence them, such as sex, ear side, language, ethnicity, and local environment.

So researchers conducted hearing tests for 450 individuals across 13 global populations—Equador, England, Gabon, South Africa, and Uzbekistan. These populations were selected to capture a wide range of ecological and cultural contexts, including underrepresented rural and non-European groups.

They investigated the sensitivity of the cochlea in the ear, looking at how it transmitted brain signals in response to different amplitudes and frequencies of sound by measuring so-called Transient-Evoked Otoacoustic Emissions (TEOAE).

It's already well known that people generally have better hearing in their right ear, compared with their left, and that hearing usually declines with age. However, the researchers were surprised by their results on the effects of sex and the environment.

Their findings, published in the journal Scientific Reports, show that hearing amplitude is more influenced by sex than age, with women showing an average of two decibels more sensitive hearing than men across all the populations studied.

The second most significant influence was the environment, which not only affected the response to volume but also the range of frequencies of sound perceived. People living in forest areas had the highest hearing sensitivity and those living at high altitudes had the lowest.

Part 1

Comment by Dr. Krishna Kumari Challa on March 29, 2025 at 10:40am

The phenomenon that organisms survive in dormancy over very long periods of time and can therefore potentially recolonize habitats under suitable conditions is also known from other studies—for example for plant seeds or small crustaceans, some of which remain viable for several centuries, even millennia.

However, the successful resurrection of a dormant stage after such a long time, as in the case of S. marinoi, has rarely been documented. At around 7000 years old, the tiny cells of this diatom are among the oldest organisms to have been successfully revived from an intact dormant stage. From aquatic sediments, no older such cases are known to date.

Sarah Bolius et al, Resurrection of a diatom after 7000 years from anoxic Baltic Sea sediment, The ISME Journal (2025). DOI: 10.1093/ismejo/wrae252

Part 3

Comment by Dr. Krishna Kumari Challa on March 29, 2025 at 10:39am

The researchers examined sediment cores taken from 240 meters water depth in the Eastern Gotland Deep during an expedition with the research vessel Elisabeth Mann Borgese in 2021.

In favorable nutrient and light conditions, viable algae could be awakened from dormancy from nine sediment samples and individual strains were isolated. The samples were taken from different sediment layers that represent a time span of around 7,000 years and thus the main climate phases of the Baltic Sea.
The diatom species Skeletonema marinoi was the only phytoplankton species that was revived from all samples. It is very common in the Baltic Sea and typically occurs during the spring bloom. The oldest sample with viable cells of this species was dated to an age of 6,871 ± 140 years.

"It is remarkable that the resurrected algae have not only survived 'just so,' but apparently have not lost any of their 'fitness,' i. e. their biological performance ability. They grow, divide and photosynthesize like their modern descendants.
The measurement of photosynthetic performance also showed that even the oldest algae isolates can still actively produce oxygen—with average values of 184 micromoles of oxygen per milligram of chlorophyll per hour. These are also values that are comparable to those of current representatives of this species.
The researchers also analyzed the genetic profiles of the resurrected algae using microsatellite analysis—a method in which certain short DNA segments are compared. The result: The samples from sediment layers of different ages formed distinctive genetic groups.

Firstly, this ruled out the possibility that cross contamination could have occurred during the cultivation of the strains from sediment layers of different ages. Secondly, this proves that successive populations of S. marinoi in the Baltic Sea have changed genetically over the millennia.
Part 2

Comment by Dr. Krishna Kumari Challa on March 29, 2025 at 10:36am

After 7,000 years without light and oxygen in Baltic Sea mud, researchers bring prehistoric algae back to life

A research team was able to revive dormant stages of algae that sank to the bottom of the Baltic Sea almost 7,000 years ago. Despite thousands of years of inactivity in the sediment without light and oxygen, the investigated diatom species regained full viability.

The study, published in The ISME Journal, was carried out as part of a collaborative research project PHYTOARK, which aims at a better understanding of the Baltic Sea's future by means of paleoecological investigations of the Baltic Sea's past.

Many organisms, from bacteria to mammals, can go into a kind of "sleep mode," known as dormancy, in order to survive periods of unfavorable environmental conditions.

They switch to a state of reduced metabolic activity and often form special dormancy stages with robust protective structures and internally stored energy reserves. This also applies to phytoplankton, microscopically small plants that live in the water and photosynthesize. Their dormant stages sink to the bottom of water bodies, where they are covered by sediment over time and preserved under anoxic conditions.

Such deposits are like a time capsule containing valuable information about past ecosystems and the inhabiting biological communities, their population development and genetic changes.

In this new study,  researchers analyzed specifically for viable phytoplankton dormant cells from the past. 

This approach bears the rather unusual name of 'resurrection ecology': Dormant stages that can be clearly assigned to specific periods of Baltic Sea history due to the clear stratification of the Baltic Sea sediment are to be brought back to life under favorable conditions, then they are genetically and physiologically characterized and compared with present-day phytoplankton population.

By analyzing other sediment components, so-called proxies, it will also be possible to draw conclusions about past salinity, oxygen and temperature conditions.

By combining all this information, they aim to better understand how and why Baltic Sea phytoplankton has adapted genetically and functionally to environmental changes.

Part 1

Comment by Dr. Krishna Kumari Challa on March 29, 2025 at 10:08am

Following injury in organoids, stem-like cells migrated into the damaged area and produced new retinal cells. Gene activity during the repair process matched patterns observed during natural fetal development.
In a mouse model of inherited retinal degeneration, transplanted cells remained viable for up to 24 weeks. Donor cells integrated into the host retina, developed into mature retinal types, and formed connections with neighboring cells. Treated animals exhibited improved retinal structure and stronger visual responses compared to controls.
Human retinal stem-like cells demonstrated the capacity to regenerate tissue and restore visual function across both fetal tissue and retinal organoid models. In both injury models and transplant experiments, the cells demonstrated the ability to restore retinal structure and contribute to visual function.
Post-transplantation, the cells remained viable for at least 24 weeks, differentiated into photoreceptors, ganglion cells, and bipolar cells, and formed functional synapses with host tissue. Treated mice demonstrated improved retinal morphology and performance in visual function assays across multiple time points. No intraocular tumors were observed following transplantation.

Compared to previously studied retinal progenitor cells, this population showed broader differentiation capacity and longer-term viability. Transplanted cells contributed to retinal structure and restored visual function in mice, without adverse effects.

Results suggest that retinal organoids may serve as a source of human stem-like cells for future research and therapeutic development. Further studies will be needed to assess safety, immune compatibility, and effectiveness in models that more closely resemble human disease.

Hui Liu et al, Identification and characterization of human retinal stem cells capable of retinal regeneration, Science Translational Medicine (2025). DOI: 10.1126/scitranslmed.adp6864

Part 2

Comment by Dr. Krishna Kumari Challa on March 29, 2025 at 10:04am

Human retinal stem-like cells with potential to repair vision loss discovered

Researchers  have identified a population of human neural retinal stem-like cells able to regenerate retinal tissue and support visual recovery.

Vision loss caused by retinal degeneration affects millions worldwide. Conditions such as retinitis pigmentosa and age-related macular degeneration involve the irreversible loss of light-sensitive neural cells in the retina. While current treatments may slow progression, they do not replace damaged tissue.

For decades, scientists have explored whether stem cells could be used to regenerate the retina, but the existence of true retinal stem cells in humans has remained uncertain. In fish and amphibians, the outer edge of the retina houses stem cells that regenerate tissue continuously. Whether a comparable system exists in the human eye has been debated for more than two decades.

In the study, "Identification and characterization of human retinal stem cells capable of retinal regeneration," published in Science Translational Medicine, researchers used single-cell and spatial transcriptomic methods to investigate the presence and identity of retinal stem-like cells in humans.

Researchers examined human fetal retinal tissue from four donors at 21 weeks of gestation, using spatial transcriptomics and single-nucleus sequencing to identify and localize cell types in the retina.

Researchers analyzed gene expression and chromatin accessibility to detect populations with stem cell–like properties. Additional samples from donors between 16 and 22 weeks of gestation were used to confirm the location of these cells in the peripheral retina.

A distinct population of neural retinal stem-like cells was identified in the peripheral retina of human fetal tissue. Located in the ciliary marginal zone, these cells showed molecular features consistent with self-renewal and the ability to differentiate into all major retinal cell types. Similar cells appeared in the same anatomical region of retinal organoids, with overlapping gene expression profiles.

Part 1

Comment by Dr. Krishna Kumari Challa on March 28, 2025 at 1:07pm

An Easy Way to Remove Microplastics From Your Drinking Water

Comment by Dr. Krishna Kumari Challa on March 28, 2025 at 9:10am

Unlike traditional microscopes that use light or lenses, DNA microscopy creates images by calculating interactions among molecules, providing a new way to visualize genetic material in 3D.

First, short DNA sequence tags called unique molecular identifiers (UMIs) are added to cells. They attach to DNA and RNA molecules and begin making copies of themselves. This starts a chemical reaction that creates new sequences, called unique event identifiers (UEIs), that are unique to each pairing.
It's these pairings that help create the spatial map of where each genetic molecule is located. UMI pairs that are close together interact more frequently and generate more UEIs than those that are farther apart.

Once the DNA and RNA are sequenced, a computational model reconstructs their original locations by analyzing the physical links between UMI-tags, creating a spatial map of gene expression.
DNA microscopy doesn't rely on prior knowledge of the genome or shape of a specimen, so it could be useful for understanding genetic expression in unique, unknown contexts. Tumors generate countless new genetic mutations, for example, so the tool would be able to map out the tumor microenvironment and where it interacts with the immune system.

 Spatial-transcriptomic imaging of an intact organism using volumetric DNA microscopy, Nature Biotechnology (2025). DOI: 10.1038/s41587-025-02613-z

Part 2

Comment by Dr. Krishna Kumari Challa on March 28, 2025 at 9:08am

DNA microscope creates 3D images of organisms from the inside out

Standard genetic sequencing approaches can tell you a lot about the genetic makeup and activity in a sample, like a piece of tissue or drop of blood. But they don't tell you where specific genetic sequences were located inside that sample, or their relationship to other genes and molecules.

Researchers  are now developing a new technology that overcomes these challenges. By tagging each DNA or RNA molecule and allowing neighboring tags to interact, the technique constructs a molecular network that encodes their relative positions, creating a spatial map of genetic material.

This technique, called volumetric DNA microscopy, creates a 3D image of an entire organism from the inside out, giving scientists an unprecedented view of genetic sequences and where they are located, down to individual cells. 

The researchers have spent more than 12 years developing DNA microscopy.

In a paper published in Nature Biotechnology the researchers used the technology to create a complete DNA image of a zebrafish embryo, a common model organism for studying development and neurobiology.

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