The findings, led by scientists at the University of Bristol and the cover story of the journal Nature, mean plants and shallow soil layers are likely removing around one gigatonne more CO2 each year from the atmosphere to counteract this, emphasising their pivotal and greater part in combating climate change.

Lead author Dr Josh Dean, Associate Professor in Biogeochemistry and UKRI Future Leaders Fellow at the University of Bristol, said: “The results took us by surprise because it turns out that old carbon stores are leaking out much more into the atmosphere then previous estimates suggested.

“The implications are potentially huge for our understanding of global carbon emissions. Plants and trees take up CO₂ from the atmosphere and can then lock this carbon away in soils for thousands of years.

“Our findings show some of this old carbon, as well as ancient carbon from rocks, is leaking sideways into rivers and making its way back to the atmosphere. We don’t yet know how humans are affecting this flow of ancient carbon, but we do know plants and trees must be taking up more carbon from the atmosphere today to account for this unrecognised release of old carbon.”

Rivers transport and release methane and carbon dioxide as part of the global carbon cycle. Until now, scientists believed the majority of this was a quick turnover derived from the recycling of recent plant growth – organic material broken down and carried into the river system in the past 70 years or so. This new study indicates the opposite, with more than half – some 60% – of emissions being attributed to long-term carbon stores accumulated over hundreds to thousands of years ago, or even longer.

The international research team, led by scientists at the University of Bristol, University of Oxford and the UK Centre for Ecology and Hydrology, studied more than 700 river reaches from 26 different countries across the world.

They took detailed radiocarbon measurements of carbon dioxide and methane from the rivers. By comparing the levels of carbon-14 in the river samples with a standard reference for modern atmospheric CO₂, the team was able to date the river carbon.

Co-author Prof Bob Hilton, Professor of Sedimentary Geography at the University of Oxford, explained: “We discovered that around half of the emissions are young, while the other half are much older, released from deep soil layers and rock weathering that were formed thousands and even millions of years ago.”

The research was supported by funding from UK Research and Innovation (UKRI) Natural Environment Research Council (NERC).

Co-author Dr Gemma Coxon, Associate Professor in Hydrology and UKRI Future Leaders Fellow at the University of Bristol, said: “Rivers globally release about two gigatonnes of carbon each year, compared to human activity that results in between 10-15 gigatonnes of carbon emissions. These river emissions are significant at a global scale, and we’re showing that over half of these emissions may be coming from carbon stores we considered relatively stable. This means we need to re-evaluate these crucial parts of the global carbon cycle.”

Further building on these findings, the researchers plan to explore how the age of river carbon emissions varies across rivers the study was not able to capture, as well as investigating how the age of these emissions may have changed through time.

The development, published today (June 11) in Nature, represents a major leap toward the realization of thinner, faster and more energy-efficient electronics, the researchers said. They created a complementary metal-oxide semiconductor (CMOS) computer — technology at the heart of nearly every modern electronic device — without relying on silicon. Instead, they used two different 2D materials to develop both types of transistors needed to control the electric current flow in CMOS computers: molybdenum disulfide for n-type transistors and tungsten diselenide for p-type transistors.

“Silicon has driven remarkable advances in electronics for decades by enabling continuous miniaturization of field-effect transistors (FETs),” said Saptarshi Das, the Ackley Professor of Engineering and professor of engineering science and mechanics at Penn State, who led the research. FETs control current flow using an electric field, which is produced when a voltage is applied. “However, as silicon devices shrink, their performance begins to degrade. Two-dimensional materials, by contrast, maintain their exceptional electronic properties at atomic thickness, offering a promising path forward.”

Das explained that CMOS technology requires both n-type and p-type semiconductors working together to achieve high performance at low power consumption — a key challenge that has stymied efforts to move beyond silicon. Although previous studies demonstrated small circuits based on 2D materials, scaling to complex, functional computers had remained elusive, Das said.

“That’s the key advancement of our work,” Das said. “We have demonstrated, for the first time, a CMOS computer built entirely from 2D materials, combining large area grown molybdenum disulfide and tungsten diselenide transistors.”

The team used metal-organic chemical vapor deposition (MOCVD) — a fabrication process that involves vaporizing ingredients, forcing a chemical reaction and depositing the products onto a substrate — to grow large sheets of molybdenum disulfide and tungsten diselenide and fabricate over 1,000 of each type of transistor. By carefully tuning the device fabrication and post-processing steps, they were able to adjust the threshold voltages of both n- and p-type transistors, enabling the construction of fully functional CMOS logic circuits.

“Our 2D CMOS computer operates at low-supply voltages with minimal power consumption and can perform simple logic operations at frequencies up to 25 kilohertz,” said first author Subir Ghosh, a doctoral student pursuing a degree in engineering science and mechanics under Das’s mentorship.

Ghosh noted that the operating frequency is low compared to conventional silicon CMOS circuits, but their computer — known as a one instruction set computer — can still perform simple logic operations.

“We also developed a computational model, calibrated using experimental data and incorporating variations between devices, to project the performance of our 2D CMOS computer and benchmark it against state-of-the-art silicon technology,” Ghosh said. “Although there remains scope for further optimization, this work marks a significant milestone in harnessing 2D materials to advance the field of electronics.”

Das agreed, explaining that more work is needed to further develop the 2D CMOS computer approach for broad use, but also emphasizing that the field is moving quickly when compared to the development of silicon technology.

“Silicon technology has been under development for about 80 years, but research into 2D materials is relatively recent, only really arising around 2010,” Das said. “We expect that the development of 2D material computers is going to be a gradual process, too, but this is a leap forward compared to the trajectory of silicon.”

Ghosh and Das credited the 2D Crystal Consortium Materials Innovation Platform (2DCC-MIP) at Penn State with providing the facilities and tools needed to demonstrate their approach. Das is also affiliated with the Materials Research Institute, the 2DCC-MIP and the Departments of Electrical Engineering and of Materials Science and Engineering, all at Penn State. Other contributors from the Penn State Department of Engineering Science and Mechanics include graduate students Yikai Zheng, Najam U. Sakib, Harikrishnan Ravichandran, Yongwen Sun, Andrew L. Pannone, Muhtasim Ul Karim Sadaf and Samriddha Ray; and Yang Yang, assistant professor. Yang is also affiliated with the Materials Research Institute and the Ken and Mary Alice Lindquist Department of Nuclear Engineering at Penn State. Joan Redwing, director of the 2DCC-MIP and distinguished professor of materials science and engineering and of electrical engineering, and Chen Chen, assistant research professor, also co-authored the paper. Other contributors include Musaib Rafiq and Subham Sahay, Indian Institute of Technology; and Mrinmoy Goswami, Jadavpur University.

The U.S. National Science Foundation, the Army Research Office and the Office of Naval Research supported this work in part.

But aside from skincare benefits, what role might busy cleaner fish stations play in spreading microbes and bacteria — for good or ill — throughout the reef?

A study published in the journal Marine Ecology Progress Series is the first to investigate the influence of cleaner fish stations on reef microbial diversity. It is led by scientists from the University of California, Davis, and Woods Hole Oceanographic Institute (WHOI) in collaboration with the University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science.

Could busy cleaning stations, like some medical clinics, be hotspots for spreading bacteria and pathogens? Conversely, could they help spread beneficial microbes among reef communities? Such questions carry important implications for protecting and restoring coral reefs.

“How pathogens or microbes are moving around a reef could be critically important to understanding how individuals will be affected,” said lead author Anya Brown, an assistant professor with the UC Davis Bodega Marine Laboratory and a National Geographic Explorer who conducted the study while at WHOI. “We know microbes play a role in coral bleaching, for example. This study really lays a foundation for using cleaner fish stations as a way to study movement of microbes around the reef environment.”

Cleaner fish and reef health

One hardworking fish is the cleaning goby, a pinky-sized fish with a boldly colored stripe running along its length. To understand how the presence of cleaner fish stations influence microbial diversity, the researchers experimentally removed cleaning gobies from cleaner stations on two Caribbean reefs in Puerto Rico and St. Croix in June 2021. They compared water nutrients and microbial communities of the surrounding reef area with and without gobies. This also included resident damselfish, frequent clients of cleaner gobies.

They found that more fish visited sites where cleaner fish were present compared to where they were removed in both Puerto Rico and St. Croix. They also found that cleaner fish do influence damselfish and reef microbial diversity, but the extent of their role depends on substrate type and the specific reef environment, as each reef carries a unique microbial signature. In the study, client fish, nutrient concentrations and water bacterial cell densities varied throughout the sites.

The authors say the results highlight yet another potential impact of cleaner fish and the need to further demystify their role in shaping reef microbial diversity and transmission.

Tiny fish can have big impact

“While larger organisms on coral reefs attract the most attention, the study underscores the huge impact tiny organisms such as these fish can have and how important they are to helping healthy reef ecosystems function,” said coauthor Paul Sikkel, a research professor at the Rosenstiel School’s Department of Marine Biology and Ecology. “While cleaner fish are well-known for their role in consuming parasites and reducing stress in other fish, this is the first field study to quantify their effects on microbes of other fish and the surrounding coral reef environment.”

Additional coauthors include Amy Apprill and Jeanne Bloomberg of Woods Hole Oceanographic Institution (WHOI), Gina Hendrick and Matthew Nicholson of the University of Miami Rosenstiel School, and Marta Soares and Raquel Xavier of the University of Porto in Portugal.

The study was funded by the National Science Foundation, WHOI, and The Foundation for Science and Technology in Portugal.

However, as published today in Nature Astronomy, an international team of astronomers have found the unmistakable signature of a giant planet, called TOI-6894b, orbiting this tiny star.

This system has been discovered as part of a large-scale investigation of TESS (Transiting Exoplanet Survey Satellite) data, looking for giant planets around low-mass stars, led by Dr. Edward Bryant, who completed this work at The University of Warwick and at UCL’s Mullard Space Science Laboratory.

Dr. Edward Bryant, Warwick Astrophysics Prize Fellow and first author said: “I was very excited by this discovery. I originally searched through TESS observations of more than 91,000 low-mass red-dwarf stars looking for giant planets.

“Then, using observations taken with one of the world’s largest telescopes, ESO’s VLT, I discovered TOI-6894b, a giant planet transiting the lowest mass star known to date to host such a planet. We did not expect planets like TOI-6894b to be able to form around stars this low-mass. This discovery will be a cornerstone for understanding the extremes of giant planet formation.”

The planet (TOI-6894b) is a low-density gas giant with a radius a little larger than Saturn’s but with only ~50% of Saturn’s mass. The star (TOI-6894) is the lowest mass star to have a transiting giant planet discovered to date and is just 60% the size of the next smallest star to host such a planet.

Dr. Daniel Bayliss, Associate Professor at The University of Warwick said: “Most stars in our Galaxy are actually small stars exactly like this, with low masses and previously thought to not be able to host gas giant planets. So, the fact that this star hosts a giant planet has big implications for the total number of giant planets we estimate exist in our Galaxy.”

A Challenge to the Leading Theory

Dr Vincent Van Eylen, from UCL’s Mullard Space Science Laboratory, said: “It’s an intriguing discovery. We don’t really understand how a star with so little mass can form such a massive planet! This is one of the goals of the search for more exoplanets. By finding planetary systems different from our solar system, we can test our models and better understand how our own solar system formed.”

The most widely held theory of planet formation is called the core accretion theory. A planetary core forms first through accretion (gradual accumulation of material) and as the core becomes more massive, it eventually attracts gases that form an atmosphere. It then gets massive enough to enter a runaway gas accretion process to become a gas giant.

In this theory, the formation of gas giants is harder around low-mass stars because the amount of gas and dust in a protoplanetary disc around the star (the raw material of planet formation) is too limited to allow a massive enough core to form, and the runaway process to occur.

Yet the existence of TOI-6894b (a giant planet orbiting an extremely low-mass star) suggests this model cannot be completely accurate and alternative theories are needed.

Edward added: “Given the mass of the planet, TOI-6894b could have formed through an intermediate core-accretion process, in which a protoplanet forms and steadily accretes gas without the core becoming massive enough for runaway gas accretion.

“Alternatively, it could have formed because of a gravitationally unstable disc. In some cases, the disc surrounding the star will become unstable due to the gravitational force it exerts on itself. These discs can then fragment, with the gas and dust collapsing to form a planet.”

But the team found that neither theory could completely explain the formation of TOI-6894b from the available data, which leaves the origin of this giant planet as an open question for now.

Atmospheric Answers

One avenue to shed light on the mystery of TOI-6894b’s formation is a detailed atmospheric analysis. By measuring the distribution of material within the planet, astronomers can determine the size and structure of the planet’s core, which can tell us whether TOI-6894b formed via accretion or via an unstable disc.

This is not the only interesting feature of TOI-6894b’s atmosphere; it is unusually cold for a gas giant. Most of the gas giants found by exoplanet hunters are hot Jupiters, massive gas giants with temperatures of ~1000-2000 Kelvin. TOI-6894b, by comparison, is just 420 Kelvin. The cool temperature alongside other features of this planet, such as the very deep transits, makes it one of the most promising giant planets for astronomers to characterise with a cool atmosphere.

Professor Amaury Triaud, University of Birmingham, co-author, and member of the SPECULOOS collaboration said: “Based on the stellar irradiation of TOI-6894b, we expect the atmosphere is dominated by methane chemistry, which is exceedingly rare to identify. Temperatures are low enough that atmospheric observations could even show us ammonia, which would be the first time it is found in an exoplanet atmosphere.

“TOI-6894b likely presents a benchmark exoplanet for the study of methane-dominated atmospheres and the best ‘laboratory’ to study a planetary atmosphere containing carbon, nitrogen, and oxygen outside the Solar System.”

The atmosphere of TOI-6894b is already scheduled to be observed by the James Webb Space Telescope (JWST) within the next 12 months. This should allow astronomers to determine which, if either, of the possible theories can explain the formation of this unexpected planet.

Co-author Dr. Andrés Jordán, researcher at the Millennium Institute of Astrophysics and professor at Adolfo Ibáñez University, said: “This system provides a new challenge for models of planet formation, and it offers a very interesting target for follow-up observations to characterize its atmosphere.

“This discovery is the result of a systematic program we have been carrying out for several years from Chile and the UK. Our efforts have allowed us to contribute significantly to a better understanding of how often small stars can form giant planets, and we are providing prime targets for follow-up with space-based platforms.”

Scientists have discovered a specific group of brain cells that create memories of meals, encoding not just what food was eaten but when it was eaten. The findings, published today in Nature Communications, could explain why people with memory problems often overeat and why forgetting about a recent meal can trigger excessive hunger and lead to disordered eating.

During eating, neurons in the ventral hippocampus region of the brain become active and form what the team of researchers call “meal engrams” — specialized memory traces that store information about the experience of food consumption. While scientists have long studied engrams for their role in storing memories and other experiences in the brain, the new study identified engrams dedicated to meal experiences.

“An engram is the physical trace that a memory leaves behind in the brain,” said Scott Kanoski, professor of biological sciences at the USC Dornsife College of Letters, Arts and Sciences and corresponding author of the study. “Meal engrams function like sophisticated biological databases that store multiple types of information such as where you were eating, as well as the time that you ate.”

Distracted eating implications

The discovery has immediate relevance for understanding human eating disorders. Patients with memory impairments, such as those with dementia or brain injuries that affect memory formation, may often consume multiple meals in quick succession because they cannot remember eating.

Furthermore, distracted eating — such as mindlessly snacking while watching television or scrolling on a phone — may impair meal memories and contribute to overconsumption.

Based on the experiment’s findings, meal engrams are formed during brief pauses between bites when the brain of laboratory rats naturally survey the eating environment. These moments of awareness allow specialized hippocampal neurons to integrate multiple streams of information.

Kanoski said it can be assumed a human’s brain would undergo a similar phenomenon. When someone’s attention is focused elsewhere — on phone or television screens — these critical encoding moments are compromised. “The brain fails to properly catalog the meal experience,” said Lea Decarie-Spain, postdoctoral scholar at USC Dornsife and the study’s first author, “leading to weak or incomplete meal engrams.”

Mechanism of ‘meal memories’

The research team used advanced neuroscience techniques to observe the brain activity of laboratory rats as they ate, providing the first real-time view of how meal memories form.

The meal memory neurons are distinct from brain cells involved in other types of memory formation. When researchers selectively destroyed these neurons, lab rats showed impaired memory for food locations but retained normal spatial memory for non-food-related tasks, indicating a specialized system dedicated to meal-related information processing. The study revealed that meal memory neurons communicate with the lateral hypothalamus, a brain region long known to control hunger and eating behavior. When this hippocampus-hypothalamus connection was blocked, the lab rats overate and could not remember where meals were consumed.

Eating management implications

Kanoski said the findings could eventually inform new clinical approaches for treating obesity and weight management. Current weight management strategies often focus on restricting food intake or increasing exercise, but the new research suggests that enhancing meal memory formation could be equally important.

“We’re finally beginning to understand that remembering what and when you ate is just as crucial for healthy eating as the food choices themselves,” Kanoski said.

In addition to Kanoski, other study authors include Lea Decarie-Spain, Cindy Gu, Logan Tierno Lauer, Alicia E. Kao, Iris Deng, Molly E. Klug, Alice I. Waldow, Ashyah Hewage Galbokke, Olivia Moody, Kristen N. Donohue, Keshav S. Subramanian, Serena X. Gao, Alexander G. Bashaw and Jessica J. Rea of USC; and Samar N. Chehimi, Richard C. Crist, Benjamin C. Reiner and Matthew R. Hayes from the University of Pennsylvania’s Perelman School of Medicine; and Mingxin Yang and Guillaume de Lartigue from the Monell Chemical Senses Center; and Kevin P. Myers from the Department of Psychology at Bucknell University.

The study was supported by a Quebec Research Funds Postdoctoral Fellowship (315201), an Alzheimer’s Association Research Fellowship (AARFD-22-972811), a National Science Foundation Graduate Research Fellowship (DK105155), and a National Institute of Diabetes and Digestive and Kidney Diseases grant (K104897).

The study found that oleic acid, a monounsaturated fat associated with obesity, causes the body to make more fat cells. By boosting a signaling protein called AKT2 and reducing the activity of a regulating protein called LXR, high levels of oleic acid resulted in faster growth of the precursor cells that form new fat cells.

“We know that the types of fat that people eat have changed during the obesity epidemic. We wanted to know whether simply overeating a diet rich in fat causes obesity, or whether the composition of these fatty acids that make up the oils in the diet is important. Do specific fat molecules trigger responses in the cells?” said Michael Rudolph, Ph.D., assistant professor of biochemistry and physiology at the University of Oklahoma College of Medicine and member of OU Health Harold Hamm Diabetes Center.

Rudolph and his team, including Matthew Rodeheffer, Ph.D., of Yale University School of Medicine and other collaborators at Yale and New York University School of Medicine, fed mice a variety of specialized diets enriched in specific individual fatty acids, including those found in coconut oil, peanut oil, milk, lard and soybean oil. Oleic acid was the only one that caused the precursor cells that give rise to fat cells to proliferate more than other fatty acids.

“You can think of the fat cells as an army,” Rudolph said. “When you give oleic acid, it initially increases the number of ‘fat cell soldiers’ in the army, which creates a larger capacity to store excess dietary nutrients. Over time, if the excess nutrients overtake the number of fat cells, obesity can occur, which can then lead to cardiovascular disease or diabetes if not controlled.”

Unfortunately, it’s not quite so easy to isolate different fatty acids in a human diet. People generally consume a complex mixture if they have cream in their coffee, a salad for lunch and meat and pasta for dinner. However, Rudolph said, there are increasing levels of oleic acid in the food supply, particularly when access to food variety is limited and fast food is an affordable option.

“I think the take-home message is moderation and to consume fats from a variety of different sources,” he said. “Relatively balanced levels of oleic acid seem to be beneficial, but higher and prolonged levels may be detrimental. If someone is at risk for heart disease, high levels of oleic acid may not be a good idea.”