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Comment by Dr. Krishna Kumari Challa on April 15, 2025 at 11:03am

Modified antibody fragment blocks fertilization, paving way for nonhormonal contraceptive

Current methods of contraception rely on hormones, which can cause side effects such as mood changes, headaches or increased risk of blood clots. Blocking fertilization on the surface of the egg has been proposed as an alternative, but antibodies were deemed unsuitable due to possible immune responses triggered by their Fc region.

A new study  shows how a small antibody fragment can block fertilization by targeting a key protein on the surface of the egg. This discovery brings a nonhormonal contraceptive one step closer to reality. The study has been published in the Proceedings of the National Academy of Sciences.

In the study, the researchers describe how a modified antibody fragment can block fertilization by targeting the protein ZP2 on the surface of the egg. 

This small antibody fragment can block fertilization by targeting ZP2, a key protein in the outer layer of the egg that is involved in both sperm binding and blocking polyspermy.

The researchers have used X-ray crystallography to map the interaction between the antibody IE-3, which is known to prevent fertilization in mice, and ZP2 at the atomic level. A modified, smaller version of the antibody (scFV) was found to be equally effective, blocking fertilization in 100% of IVF tests with mouse eggs. Because it lacks the immune-triggering Fc region of the full antibody, scFV minimizes potential side effects.

Elisa Dioguardi et al, Structural basis of ZP2-targeted female nonhormonal contraception, Proceedings of the National Academy of Sciences (2025). DOI: 10.1073/pnas.2426057122

Comment by Dr. Krishna Kumari Challa on April 15, 2025 at 9:58am

Radiation from CT scans could account for 5% of all cancer cases a year, study suggests

CT can save lives, but its potential harms are often overlooked. CTs expose patients to ionizing radiation—a carcinogen—and it's long been known that the technology carries a higher risk of cancer.

Radiation from CT scans may account for 5% of all cancers annually, according to a new study  that cautions against overusing and overdosing CTs.

The danger is greatest for infants, followed by children and adolescents. But adults are also at risk, since they are the most likely to get scans.

Nearly 103,000 cancers are predicted to result from the 93 million CTs that were performed in 2023 alone. This is three to four times more than previous assessments, the researchers say.

The researchers said some CT scans are unlikely to help patients and are overused, such as those for upper respiratory infections or for headaches without concerning signs or symptoms. They said patients could lower their risk by getting fewer of these scans, or by getting lower-dose scans.

There is currently unacceptable variation in the doses used for CT, with some patients receiving excessive doses. 

JAMA Internal Medicine (2025). jamanetwork.com/journals/jamai … ainternmed.2025.0505

Comment by Dr. Krishna Kumari Challa on April 15, 2025 at 9:51am

Drug pollution in water

The drugs we take, from anxiety medications to antibiotics, don't simply vanish after leaving our bodies. Many are not fully removed by wastewater treatment systems and end up in rivers, lakes, and streams, where they can linger and affect wildlife in unexpected ways.

The new  findings suggest that even tiny traces of drugs in the environment can alter animal behavior in ways that may shape their survival and success in the wild.

A recent global survey of the world's rivers found drugs were contaminating waterways on every continent—even Antarctica. These substances enter aquatic ecosystems not only through our everyday use, as active compounds pass through our bodies and into sewage systems, but also due to improper disposal and industrial effluents.

To date, almost 1,000 different active pharmaceutical substances have been detected in environments worldwide.

Particularly worrying is the fact that the biological targets of many of these drugs, such as receptors in the human brain, are also present in a wide variety of other species. That means animals in the wild can also be affected.

In fact, research over the last several decades has demonstrated that pharmaceutical pollutants can disrupt a wide range of traits in animals, including their physiology, development, and reproduction.

https://www.science.org/doi/10.1126/science.adp7174

Comment by Dr. Krishna Kumari Challa on April 15, 2025 at 9:44am

An alternative to artificial fertilizers: Small peptides enhance symbiosis between plants and fungi

Industrial farming practices often deplete the soil of important nutrients and minerals, leaving farmers to rely on artificial fertilizers to support plant growth. In fact, fertilizer use has more than quadrupled since the 1960s, but this comes with serious consequences. Fertilizer production consumes massive amounts of energy, and its use pollutes the water, air, and land.

Plant biologists  are now proposing a new solution to help kick this unsustainable fertilizer habit. 

In a new study, the researchers identified a key molecule produced by plant roots, a small peptide called CLE16, that encourages plants and beneficial soil fungi to interact with each other. They say boosting this symbiotic relationship, in which the fungi provide mineral nutrients to the plants through CLE16 supplementation, could be a more natural and sustainable way to encourage crop growth without the use of harmful artificial fertilizers.

The findings are published in the Proceedings of the National Academy of Sciences.

By restoring the natural symbiosis between plant roots and fungi, we could help crops get the nutrients they need without the use of harmful fertilizers.

In this mutually beneficial relationship, soil-borne arbuscular mycorrhizal fungi supply plants with water and phosphorus, which the plants accept in exchange for carbon molecules. These exchanges occur by specialized symbiotic fungal tendrils, called arbuscules, burying themselves into plant root cells.

Around 80% of plants can trade resources with fungi in this way. However, the traits that support this symbiosis have been weakened over centuries of agricultural plant breeding that prioritized creating crops with the biggest yields.

Scientists say new crop varieties could be bred to strengthen these traits again—an opportunity they intend to explore through the Institute's Harnessing Plants Initiative.

 Müller, Lena Maria, A plant CLE peptide and its fungal mimic promote arbuscular mycorrhizal symbiosis via CRN-mediated ROS suppression, Proceedings of the National Academy of Sciences (2025). DOI: 10.1073/pnas.2422215122

Comment by Dr. Krishna Kumari Challa on April 15, 2025 at 9:06am

Half of the universe's hydrogen gas, long unaccounted for, has been found

Astronomers tallying up all the normal matter—stars, galaxies and gas—in the universe today have come up embarrassingly short of the total matter produced in the Big Bang 13.6 billion years ago. In fact, more than half of normal matter—half of the 15% of the universe's matter that is not dark matter—cannot be accounted for in the glowing stars and gas we see.

New measurements, however, seem to have found this missing matter in the form of very diffuse and invisible ionized hydrogen gas, which forms a halo around galaxies and is more puffed out and extensive than astronomers thought.

The findings not only relieve a conflict between astronomical observations and the best, proven model of the evolution of the universe since the Big Bang, they also suggest that the massive black holes at the centers of galaxies are more active than previously thought, fountaining gas much farther from the galactic center than expected—about five times farther, the team found.

The new  measurements are certainly consistent with finding all of the gas. 

The results of the study, co-authored by 75 scientists from institutions around the world, have been presented at recent scientific meetings, posted as a preprint on arXiv and are undergoing peer review at the journal Physical Review Letters.

While the still mysterious dark matter makes up the bulk—about 84%—of matter in the universe, the remainder is normal matter. Only about 7% of normal matter is in the form of stars, while the rest is in the form of invisible hydrogen gas—most of it ionized—in galaxies and the filaments that connect galaxies in a kind of cosmic network.

The ionized gas and associated electrons strung out in this filament network are referred to as the warm-hot intergalactic medium, which is too cold and too diffuse to be seen with the usual techniques at astronomers' disposal, and therefore has remained elusive until now.

In the new paper, the researchers estimated the distribution of ionized hydrogen around galaxies by stacking images of approximately 7 million galaxies—all within about 8 billion light-years of Earth—and measuring the slight dimming or brightening of the cosmic microwave background caused by a scattering of the radiation by electrons in the ionized gas, the so-called kinematic Sunyaev-Zel'dovich effect.

B. Hadzhiyska et al, Evidence for large baryonic feedback at low and intermediate redshifts from kinematic Sunyaev-Zel'dovich observations with ACT and DESI photometric galaxies, arXiv (2024). DOI: 10.48550/arxiv.2407.07152

Comment by Dr. Krishna Kumari Challa on April 15, 2025 at 8:58am

Scientists uncover why carbon-rich meteorites rarely reach Earth

An international team of researchers may have answered one of space science's long-running questions—and it could change our understanding of how life began. Carbon-rich asteroids are abundant in space yet make up less than 5% of meteorites found on Earth.

Published in Nature Astronomy, researchers analyzed close to 8,500 meteoroids and meteorite impacts, using data from 19 fireball observation networks across 39 countries—making it the most comprehensive study of its kind. The paper is titled "Perihelion history and atmospheric survival as primary drivers of Earth's meteorite record."

The team discovered Earth's atmosphere and the sun act like giant filters, destroying fragile, carbon-rich (carbonaceous) meteoroids before they reach the ground.

Scientists have long suspected that weak, carbonaceous material doesn't survive atmospheric entry. What this research shows is many of these meteoroids don't even make it that far: they break apart from being heated repeatedly as they pass close to the sun. The ones that do survive getting cooked in space are more likely to also make it through Earth's atmosphere.

The study also found meteoroids created by tidal disruptions—when asteroids break apart from close encounters with planets—are especially fragile and almost never survive atmospheric entry.

Carbonaceous meteorites are particularly important because they contain water and organic molecules—key ingredients linked to the origin of life on Earth. Carbon-rich meteorites are some of the most chemically primitive materials we can study—they contain water, organic molecules and even amino acids.

However, scientists have so few of them in their meteorite collections that they risk having an incomplete picture of what's actually out there in space and how the building blocks of life arrived on Earth.

Understanding what gets filtered out and why is key to reconstructing our solar system's history and the conditions that made life possible.

 Patrick M. Shober et al, Perihelion history and atmospheric survival as primary drivers of the Earth's meteorite record, Nature Astronomy (2025). DOI: 10.1038/s41550-025-02526-6

Comment by Dr. Krishna Kumari Challa on April 15, 2025 at 8:42am

Besides harming health, high levels of surface ozone reduce photosynthesis by damaging photosystems, CO₂ fixation and pigments. This leads to a reduction in carbon assimilation that results in the decline of crop yields.

According to the ozone study, India's rice yield loss due to ozone pollution rose from 7.39 million tons to 11.46 million tons between 2005 and 2020, costing around US$2.92 billion and impacting food security.

Even if precursor emissions remain at the current level, climate change alone could contribute to the increase in surface ozone in the highly polluted regions of South Asia by 2050 with the Indo-Gangetic Plains, one of the most fertile regions in the region, likely to face significant crop yield losses.

Much of the surface ozone generated is taken care of by nature, such as the monsoon rains. Dealing with the reported increase in ozone levels is best done by reducing the precursors—nitrogen oxides, methane and PM_2.5.

G.S. Gopikrishnan et al, Exposure to surface ozone and its associated health effects and economic burden in India, Global Transitions (2025). DOI: 10.1016/j.glt.2025.03.002

Footnotes:

1. Estimating the effect of annual PM2-5 exposure on mortality in India: a difference-in-differences approach, The Lancet Planetary Health (2024). DOI: 10.1016/S2542-5196(24)00248-1. www.thelancet.com/journals/lan … (24)00248-1/fulltext

Part 2

Comment by Dr. Krishna Kumari Challa on April 15, 2025 at 8:38am

'Ozone-climate penalty' adds to India's air pollution

India's cities are already ranked among the world's most polluted, based on concentrations of fine particulate matter in the air. Now new research indicates they are battling rising levels of another life-threatening pollutant—surface ozone.

A study published in the journal Global Transitions says deaths from ozone in India exceeded 50,000 in 2022 and caused losses of around US$16.8 billion—about 1.5 times the government's total health spending that year.

Surface ozone is a toxic gas that not only affects public health but also impacts ecosystems and climate due to the greenhouse effect.

Ozone, a variant of oxygen, occurs at ground level as well as in the upper atmosphere. Formed naturally, the ozone in the stratosphere helps filter out harmful ultraviolet rays that are a part of the sun's radiation. However, surface ozone, also called ground-level ozone, is generated by interactions between pollutants. For example, nitrogen oxides found in vehicular exhaust can react with volatile organic compounds released by industrial activity and waste dumps to produce ozone. Surface ozone is the primary component of smog and can have negative effects on human health and the environment.

Short-term exposure to ozone increases the risk of death from heart disease, stroke, hypertension and respiratory issues, while long-term exposure may decrease lung capacity, induce oxidative stress, suppress immune response and cause lung inflammation.

Climate change, rising temperatures and altered weather patterns can raise surface ozone in a phenomenon described by experts as the "ozone-climate penalty". Factors that affect ozone generation include solar radiation, humidity, precipitation and the presence of precursors—substances that lead to the formation of a pollutant through a chemical reaction—such as methane, nitrogen oxides and volatile organic compounds.

Ozone pollution increases during the hot summer months and declines during the monsoon period from June to September as heavy rains wash out the pollutants, and reduced solar radiation limits photochemical reactions.

Critically, human exposure to fine particulate matter—known as PM_2.5—may worsen the health effects of ozone. 

PM_2.5 refers to particles smaller than 2.5 microns, which can enter the bloodstream through the lungs.

According to the 2024 World Air Quality Report, 11 of the world's 20 cities carrying the highest burden of PM_2.5 are in India.

A study (1) published in The Lancet Planetary Health found that the whole of the population of India lives in areas where PM_2.5 levels exceed WHO guidelines.

Part 1

Comment by Dr. Krishna Kumari Challa on April 13, 2025 at 2:10pm

Venom characteristics of a deadly snake depends on climate .... and can be predicted from local climate

Local climate can be used to predict the venom characteristics of a deadly snake that is widespread in India, helping clinicians to provide targeted therapies for snake bite victims, according to a study published in PLOS Neglected Tropical Diseases

Russell's viper (Daboia russelii) is found across the Indian subcontinent and is responsible for over 40% of snake bite-related deaths in India each year. Its venom is extremely variable, and snake bites cause different symptoms in different regions of India.

The toxic effects of snake venom are caused by the concentrations of different enzymes, which can be influenced by many factors, including prey availability and climate. However, the factors driving variation in Russell's viper venom are unknown.

To investigate, researchers analyzed venom samples from 115 snakes collected in 34 locations across India. They tested the activity of venom toxins, including enzymes that break down proteins, phospholipids and amino acids.

Next, they used historical climate data to understand the relationship between venom composition and the local climate where the snakes were caught. They found that temperature and rainfall partly explained regional variation in snake venom composition.

Protease activity showed the closest relationship to climate variables, whereas the activity of amino acid oxidases was unaffected by climate. Snakes in drier regions of India tended to have higher protease activity.

The researchers used this data to create a map of expected venom types across Russell's viper's range in India, which could be used to predict the clinical symptoms of snake bites in different regions.

The venom maps developed in this study could help clinicians select the most appropriate treatment for patients with snake bites, or to develop targeted therapies such as toxin-specific antibodies, the researchers say.

PLOS Neglected Tropical Diseases (2025). DOI: 10.1371/journal.pntd.0012949

Comment by Dr. Krishna Kumari Challa on April 12, 2025 at 3:41pm

Researchers identify simple rules for folding the genome

An international team of researchers have identified rules that tell cells how to fold DNA into the tightly packed, iconic X-shaped chromosomes formed during mitosis that help ensure the accurate passing of genetic information between cells during cell division.

Published in the journal Science, these findings illuminate basic biological functions underlying mitosis on a micrometer scale. Understanding how the cells accomplish this critical task may provide important new insights into inheritance and DNA stability and repair, as well as genetic mutations that lead to human diseases such as cancer.

 Kumiko Samejima et al, Rules of engagement for condensins and cohesins guide mitotic chromosome formation, Science (2025). DOI: 10.1126/science.adq1709

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