United News of Bangladesh

Scientists have discovered three previously unknown types of Helicobacter bacteria in pygmy sperm whales, offering new clues about the health of one of the ocean's most mysterious marine mammals. Pygmy sperm whales (Kogia breviceps) are among the least studied whale species because they spend most of their lives far offshore, travel in small groups and dive deep to hunt squid and fish. As they are rarely seen in the wild, much of what scientists know about them comes from whales that wash ashore. Researchers from Florida Atlantic University's Harbor Branch Oceanographic Institute and partner institutions reviewed more than two decades of whale stranding records and preserved tissue samples. Their findings, published in the Journal of Wildlife Diseases, identified three previously undocumented Helicobacter genotypes, named Kogia Helicobacter 1, 2 and 3. The discovery is the first confirmed evidence of these bacteria in pygmy sperm whales and could help scientists better understand the role bacterial infections play in the health of marine mammals. "Helicobacter bacteria are known to cause stomach-related illnesses in humans and other animals, including chronic inflammation, ulcers and even stomach cancer," said lead researcher Annie Page. "Finding new strains in a deep-diving whale species is an important scientific discovery." New bacteria identified Between 1999 and 2020, researchers examined 59 stranded pygmy sperm whales, conducting post-mortem examinations on about 80% of them. Four whales were found to have spiral-shaped bacteria in their stomach tissue. Further laboratory testing and DNA analysis confirmed that the bacteria belonged to three previously unknown Helicobacter genotypes. According to researcher Wendy Marks, two of the newly identified bacteria are genetically similar to Helicobacter species previously found in dolphins, porpoises and humans. The third belongs to a more distinct genetic group, suggesting that many unknown bacteria may still exist in the ocean. Signs of stomach disease All four whales carrying the bacteria also showed signs of digestive system disease, including stomach inflammation, ulcers, tissue scarring and parasitic worm infections. One whale also had inflammation in its intestine. Although researchers did not conclude that the bacteria caused the whales' deaths, they said the repeated presence of stomach damage suggests the infection may contribute to long-term health problems. Helicobacter bacteria were first identified in marine mammals in 2000 and have since been found in several whale and dolphin species. Infections have been linked to stomach ulcers, inflammation, reduced appetite and other digestive disorders. More research needed Scientists say it remains unclear how common these newly discovered bacteria are among pygmy sperm whales or how much they affect the animals' health. Because the species is rarely observed in the wild, further studies will be needed to determine whether the bacteria contribute to illness, strandings or broader population declines. Researchers said the discovery also highlights the importance of long-term marine mammal stranding programmes, which provide valuable opportunities to study species that are otherwise difficult to observe. The study involved scientists from Florida Atlantic University, the University of Florida, Colorado State University and Marine Mammal Pathology Services. Source: Science Daily

Scientists have identified the rare type of meteorite that is believed to have struck Earth 66 million years ago, triggering the mass extinction that wiped out about 75 percent of all species, including all non-avian dinosaurs. According to a new study published in Science Advances, the impactor was most likely a rare carbon-rich meteorite known as a CO chondrite, based on an analysis of nickel isotopes preserved in material left behind after the Cretaceous-Paleogene impact. The international research team included scientists from the University of British Columbia (UBC), as well as research institutions in Paris, Brussels and Vienna. Researchers said CO chondrites differ significantly from the meteorites commonly found on Earth because they contain much lower amounts of volatile elements such as carbon, zinc, water and especially sulfur. "CO chondrites are very different from the meteorites typically displayed in museums," said Dr. Philippe Claeys, a visiting professor at UBC and one of the study's researchers. The findings suggest that sulfur carried by the meteorite itself was probably not the main cause of the global environmental disaster that followed the impact. Instead, scientists believe vast amounts of fine dust and debris blasted into the atmosphere played the biggest role by blocking sunlight and disrupting Earth's climate. To identify the impactor, researchers conducted highly precise measurements of nickel isotopes in samples collected from a thin layer of clay found around the world. This layer was formed after the asteroid struck Earth and marks the boundary between the Cretaceous and Paleogene periods. Scientists said the work was particularly challenging because nearly the entire meteorite vaporized upon impact, leaving behind only tiny traces of its original material. Despite the limited evidence, the unique nickel isotope signature allowed researchers to identify the impactor as a rare CO chondrite. The meteorite's exact origin remains uncertain. Researchers believe it may have come either from the outer regions of the solar system or from the outer part of the asteroid belt near Jupiter. Carbonaceous chondrites make up only about five percent of meteorites recovered on Earth, while CO chondrites represent only a small fraction of that already rare group. They are considered among the oldest and most primitive materials formed during the early history of the solar system. "Being struck by such a rare object highlights just how unfortunate the dinosaurs were," Claeys said. Scientists estimate the asteroid measured between 10 and 15 kilometres in diameter and hit Earth at a speed of around 64,000 kilometres per hour. The impact created the massive Chicxulub crater, which is now buried beneath Mexico's Yucatán Peninsula. Researchers say the collision triggered global environmental changes that led to one of the most devastating mass extinctions in Earth's history. Source: Science Daily

Scientists have proposed a new explanation for what fuels the Yellowstone supervolcano, challenging the long-held belief that it is fed by a deep plume of molten rock rising from Earth’s interior. A new study published in the journal ‘Science’ suggests that Yellowstone’s magma is instead supplied by a broad underground flow of hot rock, described as a “mantle wind,” moving through the upper mantle beneath North America. Supervolcanoes are capable of producing the largest volcanic eruptions on Earth, releasing more than 1,000 cubic kilometres of magma, rock and ash. Such eruptions can have far-reaching effects on global climate, ecosystems and human societies, making it important for scientists to understand how these massive volcanic systems develop. Researchers from the Institute of Geology and Geophysics of the Chinese Academy of Sciences created a detailed three-dimensional model of western North America to study how the Earth's outer shell, known as the lithosphere, and the underlying mantle interact. Their findings suggest that the hot material feeding Yellowstone comes from the shallow asthenosphere, a softer layer beneath the lithosphere, rather than from a deep mantle plume. The study also challenges the traditional idea that supervolcanoes contain huge, long-lasting chambers of liquid magma beneath the surface. Instead, researchers say the magma is spread through vast regions of partially molten rock called "magma mush" systems. These thick, semi-solid zones extend across large sections of the lithosphere and may only produce smaller liquid-rich magma pockets shortly before an eruption. Yellowstone, located in the western United States, has experienced two supereruptions over the past 2.1 million years, making it one of the world’s best-studied supervolcanoes. Previous research had identified a large magma mush system beneath Yellowstone, but the source of the magma and the forces shaping it remained uncertain. According to the new model, the underground mantle wind was created by the long-term movement of the ancient Farallon Plate, whose remnants still lie deep beneath central and eastern North America. As this hot mantle material flows eastward beneath the continent, it is forced downward under the thick lithosphere. The resulting stretching causes pressure to drop, allowing rock to melt and form magma. The researchers also found that opposing forces beneath Yellowstone gradually pull apart the continental lithosphere, creating a southwest-sloping pathway that allows magma to rise and evolve over time. They say the model closely matches existing geological and geophysical observations from the Yellowstone region. The researchers believe their findings provide one of the clearest explanations yet of how giant magma systems develop beneath supervolcanoes. The study also offers a possible mechanism for maintaining the long-lived magma mush systems believed to exist beneath many of the world's supervolcanoes.

Scientists have identified a brain mechanism that links deep sleep with growth hormone release, helping explain how quality sleep supports muscle growth, fat metabolism and brain function. Researchers at the University of California, Berkeley, say the discovery sheds new light on why poor sleep can affect physical health and may eventually help develop treatments for sleep-related metabolic and neurological disorders. Deep sleep, particularly the non-REM stage, plays a crucial role in repairing the body, strengthening muscles, supporting bone growth and regulating fat storage. It is also important for normal growth during adolescence. Growth hormone, which is released mainly during sleep, is central to these processes. However, scientists have long been uncertain about exactly how sleep controls the hormone's release. In a study published in the journal ‘Cell’, researchers mapped brain circuits involved in growth hormone regulation and discovered a feedback system that helps maintain a balance between sleep and hormone production. “People know that growth hormone release is tightly related to sleep,” said lead author Xinlu Ding. “We are providing a basic circuit to work on in the future to develop different treatments.” The study found that specialised cells in the hypothalamus, a region deep within the brain, control growth hormone through two key chemical signals. One stimulates hormone release while the other suppresses it, allowing the body to regulate hormone levels throughout different stages of sleep. Researchers also found that once growth hormone is released, it activates another brain region called the locus coeruleus, which is involved in alertness, attention and thinking ability. According to the study, hormone levels rise differently during REM and non-REM sleep, helping maintain healthy body functions. The team also discovered a feedback loop in which growth hormone gradually promotes wakefulness as sleep continues. However, excessive activity in the same brain region can trigger sleepiness, creating a balance between sleep and alertness. “This balance is essential for growth, repair and metabolic health,” said study co-author Daniel Silverman. Scientists say the findings could have implications for conditions linked to poor sleep, including obesity, diabetes, heart disease, Parkinson’s disease and Alzheimer’s disease. Researchers also noted that growth hormone may benefit cognitive performance by supporting alertness and mental focus after waking up. “Growth hormone not only helps you build your muscle and bones and reduce your fat tissue, but may also have cognitive benefits,” Ding said. The study was conducted by researchers from UC Berkeley and Stanford University and was supported by the Howard Hughes Medical Institute and other research grants. Source: Science Daily

Researchers have discovered that a very small change at the atomic level can significantly alter how a metal behaves, opening new possibilities for advanced electronics and materials design. A team at the University of Minnesota Twin Cities found that carefully controlling the interaction between two materials at their interface can dramatically change the electronic properties of a metal. Their study, published in ‘Nature Communications’, shows that a process known as interfacial polarization can be used to tune the surface work function of ruthenium dioxide (RuO₂) by more than 1 electron volt. The change was achieved simply by adjusting the thickness of an ultra-thin film by just a few nanometres. Researchers said the finding challenges the long-held belief that polarization mainly occurs in insulating or ferroelectric materials, not metals. “We often think of polarization as something that belongs to insulators or ferroelectrics — not metals,” said Bharat Jalan. “Our work shows that, through careful interface design, you can stabilise polarization in a metallic system and use it to tune electronic properties.” The effect was found to depend strongly on thickness, with the most significant change occurring when the ruthenium dioxide layer reached around four nanometres — roughly the width of a DNA strand. At this scale, the metal shifts from a strained atomic structure to a more relaxed arrangement, leading to noticeable changes in its electronic behaviour. “This was surprising,” said Seung Gyo Jeong. “We expected subtle interface effects, but not such a large and controllable change in work function.” Researchers said the ability to observe and link tiny atomic movements with major electronic changes shows how interface engineering can be used to precisely control metallic materials. They added that the discovery could have future applications in electronics, catalytic systems and emerging quantum technologies. Source: Science Daily

Pigeons may rely on an unexpected body part to navigate over long distances: their liver, according to a new study that sheds light on one of nature’s long-standing mysteries. Scientists have long known that many animals use Earth’s magnetic field to help them find their way. Birds, fish and sea turtles are among the species believed to use this natural compass, but researchers have struggled for decades to understand exactly how the process works. Pigeons are particularly famous for their navigation skills. They can travel hundreds of miles in a single day and have been used by humans for thousands of years to carry messages and important information. Over the years, scientists have proposed several theories about how pigeons detect magnetic signals, including through special molecules in their eyes, their beaks or their inner ears. However, a new study points to a different possibility. Researchers led by scientists in Germany found strong magnetic signals in the birds’ livers, specifically in iron-rich immune cells that help break down old red blood cells and store iron. When scientists temporarily removed these immune cells from pigeons and then observed their flights, the birds struggled to find their way home, according to the study published in the journal Science. “The magnetic sense has remained a mystery for nearly a century,” said Martin Wikelski of the Max Planck Institute of Animal Behavior. Researchers believe the iron-containing cells may help pigeons detect Earth’s magnetic field and provide navigation information to the brain. The effect was most noticeable on cloudy days. Scientists said that under clear skies pigeons can also use the sun as a guide, but when sunlight is unavailable, their magnetic sensing system becomes more important. According to study co-author Christian Kurts of the University of Bonn, the findings suggest the liver cells may play a key role in helping birds maintain their sense of direction. Another researcher involved in the study, Clivia Lisowski, said the immune cells are located close to nerve fibers in the liver, which could allow magnetic information to be transmitted to the brain. Experts not involved in the research described the findings as intriguing. Albert Kao of the University of Massachusetts Boston said he would not have expected the liver to play such a role, but the explanation appeared plausible. The researchers believe similar mechanisms could exist in other birds and animals, including mice. However, outside experts caution that more studies are needed to confirm the theory and understand exactly how magnetic signals are processed by the brain. Scientists also noted that magnetic-sensitive immune cells have been found in other parts of pigeons' bodies, including the beak and spleen, suggesting navigation may involve multiple systems rather than a single mechanism. In an accompanying editorial, researchers argued that pigeons may use several methods to navigate depending on the situation, such as traveling long distances or locating a specific destination. Having more than one way to find their way home, they noted, could be a useful advantage for birds flying in difficult conditions.

Researchers have found that storing mangoes at 12 degrees Celsius can significantly extend the fruit’s freshness while preventing cold damage, offering a potential breakthrough for mango transportation and storage systems. According to a study by scientists from Hainan University, mangoes kept at 12°C ripened more slowly, retained their firmness and flavor longer, and activated stronger natural antioxidant defenses compared to fruit stored at warmer temperatures. The findings, published in Tropical Plants, could help reduce spoilage and improve cold-chain transport for tropical fruits. Mangoes are widely popular for their sweet taste and nutritional value, but they spoil quickly after harvesting because they continue to ripen during storage and transport. In many tropical countries, mangoes are usually transported at temperatures between 26°C and 30°C. Scientists say such warm conditions speed up ripening and moisture loss, causing the fruit to soften and deteriorate faster. Although colder storage is known to slow ripening, mangoes are also sensitive to extremely low temperatures, which can cause chilling injuries. Earlier studies had suggested that 12°C might be an effective storage temperature for ‘Tainong No.1’ mangoes, but researchers did not fully understand why. To explore the issue, scientists compared mangoes stored at 12°C and 30°C over 24 days. The team monitored several factors including fruit color, firmness, weight loss, sugar content, acidity, respiration rate, and levels of harmful molecules linked to cell damage. Researchers also examined antioxidant compounds such as vitamin C, phenolics and flavonoids, along with protective enzymes that help fruits resist spoilage. The study found that mangoes stored at 12°C stayed fresh much longer than those kept at 30°C. After 16 days, mangoes stored at warmer temperatures turned yellow quickly, while those kept at 12°C maintained their green color for a longer period. Fruit stored at 30°C also lost acidity faster and experienced sharp increases and later declines in sugar content. In contrast, mangoes kept at 12°C showed slower and steadier ripening. The difference in physical condition was even more noticeable. Mangoes stored at 30°C lost over 17% of their weight, while fruit kept at 12°C lost less than 4%. Cooler storage also helped the fruit remain firm for longer periods. Microscopic analysis showed that mangoes stored at 12°C retained stronger cell walls and starch structures even after 24 days, while fruit stored at 30°C showed early cell damage and collapse. Researchers further discovered that cooler temperatures reduced oxidative stress inside the fruit by limiting the buildup of harmful molecules linked to spoilage. At the same time, mangoes stored at 12°C maintained higher levels of vitamin C and other antioxidant compounds. Protective enzymes also remained active for longer under cooler conditions. Gene analysis showed increased activity in several antioxidant-related genes, helping strengthen the fruit’s natural defense system and reduce cellular damage during storage. Scientists said the findings could provide practical guidance for the mango industry, allowing fruit to be harvested earlier, transported over longer distances, and ripened closer to consumer markets with less waste and quality loss. The research received funding support from several Chinese agricultural and research programmes, including the Hainan Province Agricultural Reclamation Team Joint Innovation Project and China’s National Key Research and Development Programme. Source: Science Daily

Scientists say the most extreme climate change scenarios once used in global projections are becoming less realistic, with both the worst and best-case futures now largely ruled out, reflecting how global emissions trends have shifted over time. A new set of seven climate scenarios suggests that while the most catastrophic warming outcomes are now less likely due to the gradual rise of renewable energy, the world is also no longer on track to meet the Paris Agreement’s most ambitious target of limiting warming to 1.5°C above pre-industrial levels. Carbon dioxide emissions from fossil fuels such as coal, oil and gas remain the primary driver of global warming. Although the growing use of cleaner energy sources like solar and wind has reduced the probability of the most extreme warming pathways, scientists say the transition has not been fast enough to prevent significant long-term temperature rise. The updated scenarios replace earlier projections that included both very high-emission futures and highly optimistic pathways. Researchers now say the upper-end projection has been revised downward to about 3.5°C of warming by the end of the century, compared to earlier estimates of around 4.5°C. However, even the most optimistic scenario now exceeds the 1.5°C threshold set in 2015 under the Paris climate accord. Scientists say the planet is currently about 1.3°C warmer than pre-industrial levels and is warming at a rate of roughly 0.1°C every five years. Even small increases, they warn, are intensifying extreme weather, water shortages and biodiversity loss. “There is kind of a narrowing of the futures. It cannot be as bad as we thought, but it cannot be as good as we hoped,” said Johan Rockström of the Potsdam Institute for Climate Impact Research. Researchers say the world is now likely headed toward a “middle” pathway of around 3°C warming by 2100 if current policies continue. Experts also warn that even the best-case scenario would likely see temperatures overshoot 1.5°C for decades before any potential decline, assuming future carbon-removal technologies become viable at scale. “This is just physics,” said climate scientist Bill Hare. “We are losing the ability to limit warming even by two degrees without strong action.” Others stress that exceeding 1.5°C carries serious consequences, particularly for vulnerable nations such as small island states facing rising sea levels. The revision of older high-end scenarios, once widely used in climate research, has also sparked debate. Some scientists argue that extreme coal-heavy projections were never realistic, while others say they were useful as upper-bound possibilities for planning. Despite improvements in renewable energy costs and adoption, scientists caution that emissions are still high enough to lock in significant long-term warming. They also warn that natural climate feedbacks—such as carbon released from oceans, forests and permafrost—could add additional warming beyond human control. “The risks of climate change have not disappeared,” said study author Detlef van Vuuren. “We are still heading towards a future with significant climate impacts that we should avoid.”

Scientists have identified unexpectedly high levels of a little-known silicone-based pollutant in the atmosphere, found across cities, rural areas and forests, raising concerns about its possible impact on human health and the climate. The compounds, known as methylsiloxanes, are widely used in cosmetics, industrial products, transport systems and household items. Researchers say they are now being detected almost everywhere in the air, from densely populated cities to remote natural areas. The study was conducted by researchers from Utrecht University and University of Groningen and published in the journal Atmospheric Chemistry and Physics. Scientists say this form of pollution has received far less attention compared to better-known contaminants such as PFAS and microplastics, even though it may be more widespread in the atmosphere. Researchers previously believed these chemicals mainly entered the air through evaporation from personal care products and industrial materials. However, the new findings show that larger forms of methylsiloxanes are also released from vehicle and ship engines through lubricating oils. The study found that these larger particles are not limited to traffic-heavy zones. They were detected in urban centres, coastal regions, rural areas and even forests, suggesting they are globally distributed. Lead researcher Rupert Holzinger of Utrecht University said the findings show atmospheric levels are higher than expected. According to the study, methylsiloxanes make up between 2 percent and 4.3 percent of total organic aerosols in the air, making them one of the most common synthetic substances found in airborne particles. By comparison, PFAS levels in the atmosphere are more than a thousand times lower. Researchers explained that engine lubricants containing methylsiloxanes can enter combustion chambers during vehicle operation. Because the compounds are highly heat-resistant, they do not fully break down and are released into the air through exhaust emissions. The highest levels were recorded in urban areas, including São Paulo in Brazil, while the lowest were found in forest locations in Lithuania. Samples from rural areas in the Netherlands showed moderate levels. Scientists collected air samples from multiple regions, including Europe, South America and rural locations, to understand how the pollutant spreads across different environments. Researchers warn that people are likely inhaling these compounds continuously, but the long-term health effects remain unknown. Holzinger said estimated daily exposure may already exceed that of other synthetic pollutants such as PFAS and microplastics, calling for urgent research into possible health risks. The study also raises concerns about climate impacts. Methylsiloxanes may affect how aerosols behave in the atmosphere, potentially influencing cloud formation and ice processes. Scientists also found that more than half of the pollution likely comes from vehicle emissions. The chemicals appear to travel long distances in the atmosphere due to their stability, making them more persistent than some related hydrocarbons. Researchers say further studies are needed to understand how far the compounds spread globally and what risks they may pose over time.

Scientists say they have identified a hidden chemical pattern that could help detect life beyond Earth. The new study, published in the journal Nature Astronomy, suggests that scientists may not need to focus only on finding specific molecules on distant planets and moons. Instead, they can look at how those molecules are organized. “We’re showing that life does not only produce molecules,” said Fabian Klenner, an assistant professor of planetary sciences at University of California, Riverside and co-author of the study. “Life also produces an organizational principle that we can see by applying statistics.” Looking beyond individual molecules For years, scientists have searched for signs of life by looking for compounds such as amino acids and fatty acids. But these molecules can also form naturally without any biological activity. They have been found in meteorites and created in laboratories that mimic conditions in space. As a result, simply detecting these chemicals is not enough to confirm the presence of life. The researchers found that amino acids in living organisms are usually more diverse and more evenly distributed than those produced through non-biological processes. Fatty acids showed the opposite pattern. In this case, non-living chemical reactions tended to produce more evenly distributed mixtures than living systems. Statistical clues to life The team said this is the first study to show that signs of life can be identified using statistical analysis alone, without relying on a specific instrument. That means the method could potentially be applied to data already being collected by missions exploring Mars, Europa and Enceladus. “Astrobiology is fundamentally a forensic science,” said Gideon Yoffe, a postdoctoral researcher at the Weizmann Institute of Science and lead author of the study. “We’re trying to infer processes from incomplete clues, often with very limited data collected by missions that are extraordinarily expensive and infrequent,” he said. Borrowing from ecology To develop the method, the researchers adapted a statistical approach commonly used in ecology to measure biodiversity. Ecologists use two key concepts: richness, which counts how many different species are present, and evenness, which measures how evenly they are distributed. The scientists applied the same ideas to chemical data from around 100 existing datasets, including samples from microbes, soils, fossils, meteorites, asteroids and laboratory-made materials. In study after study, biological samples showed clear organizational patterns that distinguished them from non-living chemistry. Ancient fossils still carried the signal The method was also able to detect different levels of preservation in biological materials. “That was genuinely surprising,” Klenner said. “The method captured not only the distinction between life and nonlife, but also degrees of preservation and alteration.” Even heavily degraded samples retained signs of their biological origin. Fossilized dinosaur eggshells included in the study still showed detectable statistical patterns linked to ancient life. A useful tool for future missions The researchers stressed that no single method will be enough to prove the existence of extraterrestrial life. Klenner said any future claim would need multiple independent lines of evidence, interpreted within the geological and chemical context of the environment being studied. Still, the team believes the new statistical approach could become an important tool for future space missions. “Our approach is one more way to assess whether life may have been there,” Klenner said. “And if different techniques all point in the same direction, then that becomes very powerful.” Source: Science Daily