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Comment by Dr. Krishna Kumari Challa on February 15, 2025 at 11:20am

Inconsistent reporting by companies leads to underestimation of methane's climate impact, study finds

Companies around the world are underestimating their total greenhouse gas footprints because of inconsistent accounting standards for methane emissions, finds a new study by researchers.

 The new study, published in Nature Communications, found that methane emissions are being underreported by at least the equivalent of between 170 million and 3.3 billion tons of carbon over a decade, depending on the metric used in calculating the shortfall.

This means that each year, on average, companies around the world have potentially underestimated their carbon footprint by as much in total as the annual carbon emissions of the UK in 2022. This represents a significant methane emissions gap that could cost between $1.6 billion (£1.3 billion) and $40 billion (£32 billion) to fix.

The cumulative emission gap the researchers have documented in this work shows how important it is to standardize the reporting of methane emissions. Methane is a potent greenhouse gas and the first step towards properly addressing its effect on climate is to make sure that it's accounted for properly.

Adopting a global standard is in principle easy for companies as it essentially only requires the adjustment of a few conversion factors when calculating their greenhouse gas footprint. However, it requires global coordination as companies are currently often subject to fragmented regulations.

Methane is a potent greenhouse gas that contributes to global warming at levels comparable to carbon dioxide. Though methane is emitted in much smaller quantities than carbon dioxide, it's more efficient at trapping heat in the atmosphere. However, methane is also short-lived in the atmosphere, with a half-life of only about 10 years versus 120 years for carbon dioxide.

How much total heat a greenhouse gas traps is called its Global Warming Potential (GWP) and measured in CO₂ equivalent units, or the amount of carbon dioxide gas that would cause the same amount of warming. Because of methane's short lifespan, the conversion to CO₂ is not straightforward and debate persists about how best to represent it in terms of carbon dioxide.

If methane's impact is calculated over 20 years (GWP-20), it's about 80 times more potent than carbon dioxide because that's the timeframe before most of it has dissipated. However, gauged over 100 years (GWP-100) more of the methane has broken down so it's only about 28 times as potent.

For companies estimating and reporting their greenhouse gas footprint, this lack of harmonization can cause confusion and inaccuracies, as there's no legally binding guidance or consensus for which standard to use.

The authors note that even with their suggested corrections, total methane emissions are still being underestimated, as their calculations only focused on emissions directly produced by the companies they analyzed. Other downstream emissions, such as that which come from sold products, were not included, and are likely significant contributors as well, particularly in the energy sector.

Simone Cenci et al, Lack of harmonisation of greenhouse gases reporting standards and the methane emissions gap, Nature Communications (2025). DOI: 10.1038/s41467-025-56845-3

Comment by Dr. Krishna Kumari Challa on February 15, 2025 at 11:04am

How Earth got its ice caps

The cool conditions which have allowed ice caps to form on Earth are rare events in the planet's history and require many complex processes working at once, according to new research.

A team of scientists investigated why Earth has existed in what is known as a "greenhouse" state without ice caps for much of its history, and why the conditions we are living in now are so rare.

They found that Earth's current ice-covered state is not typical for the planet's history and was only achieved through a strange  coincidence.

Many ideas have previously been proposed to explain the known cold intervals in Earth's history. These include decreased CO₂ emissions from volcanoes, or increased carbon storage by forests, or the reaction of CO₂ with certain types of rocks.

The researchers undertook the first ever combined test of all of these cooling processes in a new type of long-term 3D model of the Earth.

 

This type of "Earth Evolution Model" has only recently been made possible through advances in computing.

They concluded that no single process could drive these cold climates, and that the cooling in fact required the combined effects of several processes at once. The results of their study were published 14 February 2025 in Science Advances.

The reason we live on an Earth with ice caps—rather than an ice-free planet—is due to a coincidental combination of very low rates of global volcanism, and highly dispersed continents with big mountains, which allow for lots of global rainfall and therefore amplify reactions that remove carbon from the atmosphere.

The important implication here is that the Earth's natural climate regulation mechanism appears to favor a warm and high-CO₂ world with no ice caps, not the partially glaciated and low-CO₂ world we have today.

This general tendency towards a warm climate has helped prevent devastating 'snowball Earth' global glaciations, which have only occurred very rarely and have therefore helped life to continue to prosper.

There is an important message, which is that we should not expect the Earth to always return to a cold state as it was in the pre-industrial age.

Earth's current ice-covered state is not typical for the planet's history, but our current global society relies on it. We should do everything we can to preserve it, and we should be careful with assumptions that cold climates will return if we drive excessive warming before stopping emissions. Over its long history, the Earth likes it hot, but our human society does not, say the researchers.

Andrew Merdith, Phanerozoic icehouse climates as the result of multiple solid-Earth cooling mechanisms, Science Advances (2025). DOI: 10.1126/sciadv.adm9798. www.science.org/doi/10.1126/sciadv.adm9798

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

Dangerous bacteria lurk in hospital sink drains, despite rigorous cleaning, study reveals

We hope to be cured when we stay in hospital. But too often, we acquire new infections there. Such "health-care-associated infections" (HAI) are a growing problem worldwide, taking up an estimated 6% of global hospital budgets.

Patients with lowered immune defenses, and in some hospitals, poor adherence to hygiene protocols, allow HAIs to thrive. Furthermore, antibiotics are widely used in hospitals, which tends to select for hardy, resistant strains of bacteria. When such resistance genes lie on mobile genetic elements, they can even jump between bacterial species, potentially leading to novel diseases.

Researchers now have shown that hospital sink drains host bacterial populations that change over time, despite impeccable cleaning protocols.

 These results highlight that controlling bacterial growth in drains, and preventing colonization by new strains of such hard-to-disinfect niches, is likely a global problem.

Sinks and their drains are routinely cleaned with bleach, as well as disinfected with chemicals and pressurized steam every fortnight, or every month in non-patient areas. Once a year, drainpipes are hyperchlorinated at low temperature.

Despite this, the authors of this study identified a total of 67 different species from the drains. The diversity in most drains went up and down over time with no clear pattern—seasonal or otherwise. The greatest diversity occurred in general medicine and intensive care, while the fewest isolates were found in the microbiology laboratory.

Dominant across wards were six Stenotrophomonas species as well as Pseudomonas aeruginosa, a pathogen known to cause ventilator-associated pneumonia and sepsis, and characterized by the WHO as one of the greatest threats to humans in terms of antibiotic resistance. At least 16 other Pseudomonas species were also found at various times and in various wards.

Other notorious hospital-associated pathogens found repeatedly were Klebsiella pneumoniae, Acinetobacter johnsonii and Acinetobacter ursingii , Enterobacter mori and Enterobacter quasiroggenkampii  and Staphylococcus aureus .

The bacteria the researchers found may originate from many sources, from patients, medical personnel, and even the environment surrounding the hospital. Once established in sink drains, they can spread outwards, posing significant risks to immunocompromised patients above all.

 Yearlong analysis of bacterial diversity in hospital sink drains: culturomics, antibiotic resistance and implications for infection control, Frontiers in Microbiology (2025). DOI: 10.3389/fmicb.2024.1501170

Comment by Dr. Krishna Kumari Challa on February 15, 2025 at 8:48am

Maternal acetaminophen (paracetamol) use may alter placental gene expression, raising ADHD risk in children

Maternal acetaminophen exposure during pregnancy is associated with a higher likelihood of childhood attention deficit hyperactivity disorder (ADHD), according to a new study.

Researchers analyzed plasma biomarkers of acetaminophen (APAP) exposure in a cohort of 307 African American mother-child pairs. Detection of APAP in second-trimester maternal blood samples correlated with increased odds of ADHD diagnosis in children by age 8–10.

Acetaminophen (also called paracetamol) is widely used during pregnancy, with an estimated 41–70% of pregnant individuals in the United States, Europe, and Asia reporting its use. Despite its classification as a low-risk medication by regulatory agencies such as the U.S. Food and Drug Administration and the European Medicines Agency, accumulating evidence suggests a potential link between prenatal APAP exposure and adverse neurodevelopmental outcomes, including ADHD and autism spectrum disorder.

Researchers utilized untargeted metabolomics to identify APAP metabolites in second-trimester maternal plasma samples and examined their relationship with childhood ADHD diagnoses and placental gene expression.

APAP metabolites were detected in 20.2% of maternal plasma samples. Children whose mothers had APAP biomarkers present in their plasma had a 3.15 times higher likelihood of an ADHD diagnosis (95% confidence interval: 1.20 to 8.29) compared with those without detected exposure.

The association was stronger among females than males, with female children of APAP-exposed mothers showing a 6.16 times higher likelihood of ADHD (95% confidence interval: 1.58 to 24.05), while the association was weaker and nonsignificant in males.

Placental gene expression analysis of a subset of 174 participants indicated sex-specific transcriptional changes. In females, APAP exposure was associated with upregulation of immune-related pathways, including increased expression of immunoglobulin heavy constant gamma 1 (IGHG1).

Increased IGHG1 expression was statistically linked to ADHD diagnoses, with mediation analysis suggesting that APAP's effect on ADHD was partly mediated through this gene's placental expression.

Oxidative phosphorylation pathways were downregulated in both sexes, a pattern previously associated with neurodevelopmental impairment.

Findings align with prior epidemiological studies and experimental animal research linking prenatal APAP exposure to neurodevelopmental disruptions. The current study eliminated the bias concerns raised in previous studies where APAP use was self-reported by using objective biomarker measurements.

 Brennan H. Baker et al, Associations of maternal blood biomarkers of prenatal APAP exposure with placental gene expression and child attention deficit hyperactivity disorder, Nature Mental Health (2025). DOI: 10.1038/s44220-025-00387-6

Comment by Dr. Krishna Kumari Challa on February 14, 2025 at 10:25am

Air inside your home may be more polluted than outside due to everyday chemical products

When you walk through a flower garden, the crisp, fresh scent is one of the first things you notice.

But bringing that flower scent or other aromas indoors with the help of chemical products—yes, air fresheners, wax melts, floor cleaners, deodorants and others—rapidly fills the air with nanoscale particles that are small enough to get deep into your lungs, researchers have found over a series of studies.

These nanoparticles form when fragrances interact with ozone, which enters buildings through ventilation systems, triggering chemical transformations that create new airborne pollutants.

A forest is a pristine environment, but if you're using cleaning and aromatherapy products full of chemically manufactured scents to recreate a forest in your home, you're actually creating a tremendous amount of indoor air pollution that you shouldn't be breathing in.

Nanoparticles just a few nanometers in size can penetrate deep into the respiratory system and spread to other organs.

To understand how airborne particles form indoors, you need to measure the smallest nanoparticles—down to a single nanometer. At this scale, we can observe the earliest stages of new particle formation, where fragrances react with ozone to form tiny molecular clusters. These clusters then rapidly evolve, growing and transforming in the air around us.

Even though it's yet to be determined how breathing in volatile chemicals from these products impacts your health, the two have repeatedly found that when fragrances are released indoors, they quickly react with ozone to form nanoparticles. These newly formed nanoparticles are particularly concerning because they can reach very high concentrations, potentially posing risks to respiratory health.

Essential oil diffusers, disinfectants, air fresheners and other scented sprays also generate a significant number of nanoscale particles.

But it's not just scented products contributing to indoor nanoparticle pollution: A study by researchers  found that cooking on a gas stove also emits nanoparticles in large quantities.

Just 1 kilogram of cooking fuel emits 10 quadrillion particles smaller than 3 nanometers, which matches or exceeds what's emitted from cars with internal combustion engines. At that rate, you might be inhaling 10–100 times more of these sub-3 nanometer particles from cooking on a gas stove indoors than you would from car exhaust while standing on a busy street.

Still, scented chemical products match or surpass gas stoves and car engines in the generation of nanoparticles smaller than 3 nanometers, called nanocluster aerosol. Between 100 billion and 10 trillion of these particles could deposit in your respiratory system within just 20 minutes of exposure to scented products.

 Satya S. Patra et al, Flame-Free Candles Are Not Pollution-Free: Scented Wax Melts as a Significant Source of Atmospheric Nanoparticles, Environmental Science & Technology Letters (2025). DOI: 10.1021/acs.estlett.4c00986

Comment by Dr. Krishna Kumari Challa on February 14, 2025 at 9:42am

Active matter: Scientists create three-dimensional 'synthetic worms'

Researchers have made a breakthrough in the development of "life-like" synthetic materials which are able to move by themselves like worms.

Scientists have been investigating a new class of materials called "active matter," which could be used for various applications from drug delivery to self-healing materials.

Compared to inanimate matter—the sort of motionless materials we come across in our lives every day, such as plastic and wood—active matter can show fascinating life-like behavior.

These materials are made of elements which are driven out of equilibrium by internal energy sources, allowing them to move independently.

Researchers carried out the experiment using special micron-sized (one millionth of a meter) particles called Janus colloids, which were suspended in a liquid mixture.

The team then made the material active by applying a strong electric field and observed the effects using a special kind of microscope which takes three-dimensional images.

When the electric field was turned on, the scattered colloid particles would merge together to form worm-like structures—which creates a fully three-dimensional synthetic active matter system.

The researchers  found the formation of fascinating new structures—self-driven active filaments that are reminiscent of living worms. They were then able to develop a theoretical frame work which enabled us to predict and control the motion of the synthetic worms solely based on their lengths.

 Xichen Chao et al, Traveling Strings of Active Dipolar Colloids, Physical Review Letters (2025). DOI: 10.1103/PhysRevLett.134.018302

Comment by Dr. Krishna Kumari Challa on February 14, 2025 at 9:36am

Birds have developed complex brains independently from mammals, studies reveal

Two studies published in the latest issue of Science have revealed that birds, reptiles, and mammals have developed complex brain circuits independently, despite sharing a common ancestor. These findings challenge the traditional view of brain evolution and demonstrate that, while comparable brain functions exist among these groups, embryonic formation mechanisms and cell types have followed divergent evolutionary trajectories.

The pallium is the brain region where the neocortex forms in mammals, the part responsible for cognitive and complex functions that most distinguishes humans from other species. The pallium has traditionally been considered a comparable structure among mammals, birds, and reptiles, varying only in complexity levels. It was assumed that this region housed similar neuronal types, with equivalent circuits for sensory and cognitive processing.

Previous studies had identified the presence of shared excitatory and inhibitory neurons as well as general connectivity patterns suggesting a similar evolutionary path in these vertebrate species.

However, the new studies reveal that, although the general functions of the pallium are equivalent among these groups, its developmental mechanisms and the molecular identity of its neurons have diverged substantially throughout evolution.

Eneritz Rueda-Alaña et al, Evolutionary convergence of sensory circuits in the pallium of amniotes, Science (2025). DOI: 10.1126/science.adp3411. www.science.org/doi/10.1126/science.adp3411

Zaremba B et al. Developmental origins and evolution of pallial cell types and structures in birds. Science (2025). DOI: 10.1126/science.adp5182. www.science.org/doi/10.1126/science.adp5182

Comment by Dr. Krishna Kumari Challa on February 14, 2025 at 9:29am

The research team found almost 30 different guardian candidates and decided to pursue one of them further: PROX1 (Prospero homeobox protein 1).

Studies on the liver cancer model showed that the team had hit the mark.
It turned out that PROX1 is a very influential guard in liver cells. If it is missing, the liver cells change their phenotype. And conversely, the versatility of tumor cells can be reduced by experimentally inducing an increase in the activity of the guard.
PROX1 was able to override the influence of such strong cancer drivers and suppress the formation of tumors despite their presence.
The researchers also found something else: the PROX1 guardian must be constantly active around the clock to fulfill its function. This is different from many other gene switches, which, like a toggle switch, only need to be activated briefly.

Lim B et al, Active repression of cell fate plasticity by PROX1 safeguards hepatocyte identity and prevents liver tumourigenesis. Nature Genetics (2025). DOI: 10.1038/s41588-025-02081-w

Part 2

Comment by Dr. Krishna Kumari Challa on February 14, 2025 at 9:27am

Guardian molecule keeps cells on track

A guardian molecule ensures that liver cells do not lose their identity. This has been discovered by researchers. 

The research is published in Nature Genetics.

The discovery is of great interest for cancer medicine because a change of identity of cells has come into focus as a fundamental principle of carcinogenesis for several years. The researchers were able to show that the newly discovered sentinel is so powerful that it can slow down highly potent cancer drivers and cause malignant liver tumors to regress in mice.

As a rule, the identity of cells is determined during embryonic development. They differentiate into nerve cells or liver cells, for example, and their fate is sealed. Only stem cells retain the ability to develop in different directions. However, once cells have differentiated, they usually stay on course.

Cancer cells are different. They have the amazing ability to reactivate embryonic programs and thus change their identity—their phenotype. This ability is referred to as—unwanted or abnormal—plasticity.

It enables tumor cells to break away from the cell network and migrate through the body. Once they have arrived in the target organ, the cells differentiate again, become sedentary again and form metastases at this site.

It is not so long ago that the importance of plasticity as a fundamental phenomenon in cancer was recognized.

The researchers' goal is to reduce the plasticity of cancer cells and thus prevent the development and spread of malignant tumors. To do this, they first need to understand how cell plasticity is regulated.

In principle, almost all cells in the body have an identical genome. But how is it possible then that such different and highly specialized cell types as nerve cells or liver cells arise?

This is only possible because cells have a sophisticated control network.

These ensure that only certain genes are switched on, depending on the cell type, while others are permanently silenced. Master regulators play a central role in this process. They switch on genes that influence specialized cells to change their identity and even acquire stem cell properties.

However, little is known about the antagonists—the control instances that prevent unwanted (re)transformation of differentiated cells by switching off certain genes.

The researchers used a computer program to search for gene switches that could potentially serve as guardians.

Part 1

Comment by Dr. Krishna Kumari Challa on February 14, 2025 at 8:46am

Can organisms help others around even after their death?

Bacteria evolved to help neighboring cells after death, new research reveals

Darwin's theory of natural selection provides an explanation for why organisms develop traits that help them survive and reproduce. Because of this, death is often seen as a failure rather than a process shaped by evolution.

When organisms die, their molecules need to be broken down for reuse by other living things. Such recycling of nutrients is necessary for new life to grow.

Researchers have shown that a type of E. coli bacteria produces an enzyme which breaks the contents of their cells down into nutrients after death. The dead bacteria are therefore offering a banquet of nutrients to the cells that were their neighbours when they were living.

The study has been published in Nature Communications.

We typically think of death being the end, that after something dies it just falls apart, rots and becomes a passive target as it is scavenged for nutrients.

But what this new work has demonstrated is that death is not the end of the programmed biological processes that occur in an organism.

Those processes continue after death, and they have evolved to do so.

"That is a fundamental rethink about how we view the death of an organism."

The researchers  realized they had stumbled across a potentially new area of biology; processes that have evolved to function after death.

One problem remained; the researchers couldn't work out how an enzyme that functions after death could have evolved.

"Typically, we think of evolution acting on living organisms not dead ones.

"The solution is that neighboring cells which gain nutrients from the dead cells are likely to be clonally related to the dead cell.

Consequently, the dead cell is giving nutrients to its relatives, analogous to how animals will often help feed younger members of their family group.

The finding demonstrates that processes after death, like processes during life, can be biologically programmed and subject to evolution. Biomolecules that regulate processes after death might be exploited in the future as novel targets for bacterial disease or as candidates to enhance bacterial growth in biotechnology.

Bacteria encode post-mortem protein catabolism that enables altruistic nutrient recycling, Nature Communications (2025). DOI: 10.1038/s41467-025-56761-6

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