Unusual team finds gigantic planet hidden in plain sight

A UC Riverside astronomer and a group of eagle-eyed citizen scientists have discovered a giant gas planet hidden from view by typical stargazing tools.

The planet, TOI-2180 b, has the same diameter as Jupiter, but is nearly three times more massive. Researchers also believe it contains 105 times the mass of Earth in elements heavier than helium and hydrogen. Nothing quite like it exists in our solar system.

Details of the finding have been published in the Astronomical Journal and presented at the American Astronomical Society virtual press event on Jan. 13.

"TOI-2180 b is such an exciting planet to have found," said UCR astronomer Paul Dalba, who helped confirm the planet's existence. "It hits the trifecta of 1) having a several-hundred-day orbit, 2) being relatively close to Earth (379 lightyears is considered close for an exoplanet), and 3) us being able to see it transit in front of its star. It is very rare for astronomers to discover a planet that checks all three of these boxes."

Dalba also explained that the planet is special because it takes 261 days to complete a journey around its star, a relatively long time compared to many known gas giants outside our solar system. Its relative proximity to Earth and the brightness of the star it orbits also make it likely astronomers will be able to learn more about it.

In order to locate exoplanets, which orbit stars other than our sun, NASA's TESS satellite looks at one part of the sky for a month, then moves on. It is searching for dips in brightness that occur when a planet crosses in front of a star.

"The rule of thumb is that we need to see three 'dips' or transits before we believe we've found a planet," Dalba said. A single transit event could be caused by a telescope with a jitter, or a star masquerading as a planet. For these reasons, TESS isn't focused on these single transit events. However, a small group of citizen scientists is.

Looking over TESS data, Tom Jacobs, a group member and former U.S. naval officer, saw light dim from the TOI-2180 star, just once. His group alerted Dalba, who specializes in studying planets that take a long time to orbit their stars.

Using the Lick Observatory's Automated Planet Finder Telescope, Dalba and his colleagues observed the planet's gravitational tug on the star, which allowed them to calculate the mass of TOI-2180 b and estimate a range of possibilities for its orbit.

Hoping to observe a second transit event, Dalba organized a campaign using 14 different telescopes across three continents in the northern hemisphere. Over the course of 11 days in August 2021, the effort resulted in 20,000 images of the TOI-2180 star, though none of them detected the planet with confidence.

However, the campaign did lead the group to estimate that TESS will see the planet transit its star again in February, when they're planning a follow up study. Funding for Dalba's research is provided by the National Science Foundation's Astronomy and Astrophysics Postdoctoral Fellowship Program.

The citizen planet hunters' group takes publicly available data from NASA satellites like TESS and looks for single transit events. While professional astronomers use algorithms to scan a lot of data automatically, the Visual Survey Group uses a program they created to inspect telescope data by eye.

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Your gut senses the difference between real sugar and artificial sweetener

Your taste buds may or may not be able to tell real sugar from a sugar substitute, but there are cells in your intestines that can and do distinguish between the two sweet solutions. And they can communicate the difference to your brain in milliseconds.

Not long after the sweet taste receptor was identified in the mouths of mice 20 years ago, scientists attempted to knock those taste buds out. But they were surprised to find that mice could still somehow discern and prefer natural sugar to artificial sweetener, even without a sense of taste.

The answer to this riddle lies much further down in the digestive tract, at the upper end of the gut just after the stomach, according to research led by Diego Bohórquez, an associate professor of medicine and neurobiology in the Duke University School of Medicine.

In a paper appearing Jan. 13 in Nature Neuroscience, "we've identified the cells that make us eat sugar, and they are in the gut," Bohórquez said. Infusing sugar directly into the lower intestine or colon does not have the same effect. The sensing cells are in the upper reaches of the gut, he said.

Having discovered a gut cell called the neuropod cell, Bohórquez with his research team has been pursuing this cell's critical role as a connection between what's inside the gut and its influence in the brain. The gut, he argues, talks directly to the brain, changing our eating behavior. And in the long run, these findings may lead to entirely new ways of treating diseases.

Originally termed enteroendrocrine cells because of their ability to secrete hormones, specialized neuropod cells can communicate with neurons via rapid synaptic connections and are distributed throughout the lining of the upper gut. In addition to producing relatively slow-acting hormone signals, the Bohórquez research team has shown that these cells also produce fast-acting neurotransmitter signals that reach the vagus nerve and then the brain within milliseconds.

Bohórquez said his group's latest findings further show that neuropods are sensory cells of the nervous system just like taste buds in the tongue or the retinal cone cells in the eye that help us see colors.

"These cells work just like the retinal cone cells that that are able to sense the wavelength of light," Bohórquez said. "They sense traces of sugar versus sweetener and then they release different neurotransmitters that go into different cells in the vagus nerve, and ultimately, the animal knows 'this is sugar' or 'this is sweetener.'"

Using lab-grown organoids from mouse and human cells to represent the small intestine and duodenum (upper gut), the researchers showed in a small experiment that real sugar stimulated individual neuropod cells to release glutamate as a neurotransmitter. Artificial sugar triggered the release of a different neurotransmitter, ATP.

Using a technique called optogenetics, the scientists were then able to turn the neuropod cells on and off in the gut of a living mouse to show whether the animal's preference for real sugar was being driven by signals from the gut. The key enabling technology for the optogenetic work was a new flexible waveguide fiber developed by MIT scientists. This flexible fiber delivers light throughout the gut in a living animal to trigger a genetic response that silenced the neuropod cells. With their neuropod cells switched off, the animal no longer showed a clear preference for real sugar.

"We trust our gut with the food we eat," Bohórquez said. "Sugar has both taste and nutritive value and the gut is able to identify both."

"Many people struggle with sugar cravings, and now we have a better understanding of how the gut senses sugars (and why artificial sweeteners don't curb those cravings)," said co-first author Kelly Buchanan, a former Duke University School of Medicine student who is now an Internal Medicine resident at Massachusetts General Hospital. "We hope to target this circuit to treat diseases we see every day in the clinic."

In future work, Bohórquez said he will be showing how these cells also recognize other macronutrients. "We always talk about 'a gut sense,' and say things like 'trust your gut,' well, there's something to this," Bohórquez said.

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Cosmic 'spider' found to be source of powerful gamma-rays

Using the 4.1-meter SOAR Telescope in Chile, astronomers have discovered the first example of a binary system where a star in the process of becoming a white dwarf is orbiting a neutron star that has just finished turning into a rapidly spinning pulsar. The pair, originally detected by the Fermi Gamma-ray Space Telescope, is a "missing link" in the evolution of such binary systems.

A bright, mysterious source of gamma rays has been found to be a rapidly spinning neutron star -- dubbed a millisecond pulsar -- that is orbiting a star in the process of evolving into an extremely-low-mass white dwarf. These types of binary systems are referred to by astronomers as "spiders" because the pulsar tends to "eat" the outer parts of the companion star as it turns into a white dwarf.

The duo was detected by astronomers using the 4.1-meter SOAR Telescope on Cerro Pachón in Chile, part of Cerro Tololo Inter-American Observatory (CTIO), a Program of NSF's NOIRLab.

NASA's Fermi Gamma-ray Space Telescope has been cataloging objects in the Universe that produce copious gamma rays since its launch in 2008, but not all of the sources of gamma rays that it detects have been classified. One such source, called 4FGL J1120.0-2204 by astronomers, was the second brightest gamma-ray source in the entire sky that had gone unidentified, until now.

Astronomers from the United States and Canada, led by Samuel Swihart of the US Naval Research Laboratory in Washington, D.C., used the Goodman Spectrograph on the SOAR Telescope to determine the true identity of 4FGL J1120.0-2204. The gamma-ray source, which also emits X-rays, as observed by NASA's Swift and ESA's XMM-Newton space telescopes, has been shown to be a binary system consisting of a "millisecond pulsar" that spins hundreds of times per second, and the precursor to an extremely-low-mass white dwarf. The pair are located over 2600 light-years away.

"Michigan State University's dedicated time on the SOAR Telescope, its location in the southern hemisphere and the precision and stability of the Goodman spectrograph, were all important aspects of this discovery," says Swihart.

"This is a great example of how mid-sized telescopes in general, and SOAR in particular, can be used to help characterize unusual discoveries made with other ground and space-based facilities," notes Chris Davis, NOIRLab Program Director at US National Science Foundation. "We anticipate that SOAR will play a crucial role in the follow-up of many other time-variable and multi-messenger sources over the coming decade."

The optical spectrum of the binary system measured by the Goodman spectrograph showed that light from the proto-white dwarf companion is Doppler shifted -- alternately shifted to the red and the blue -- indicating that it orbits a compact, massive neutron star every 15 hours.

"The spectra also allowed us to constrain the approximate temperature and surface gravity of the companion star," says Swihart, whose team was able to take these properties and apply them to models describing how binary star systems evolve. This allowed them to determine that the companion is the precursor to an extremely-low-mass white dwarf, with a surface temperature of 8200 °C (15,000 °F), and a mass of just 17% that of the Sun.

When a star with a mass similar to that of the Sun or less reaches the end of its life, it will run out of the hydrogen used to fuel the nuclear fusion processes in its core. For a time, helium takes over and powers the star, causing it to contract and heat up, and prompting its expansion and evolution into a red giant that is hundreds of millions of kilometers in size. Eventually, the outer layers of this swollen star can be accreted onto a binary companion and nuclear fusion halts, leaving behind a white dwarf about the size of Earth and sizzling at temperatures exceeding 100,000 °C (180,000 °F).

The proto-white dwarf in the 4FGL J1120.0-2204 system hasn't finished evolving yet. "Currently it's bloated, and is about five times larger in radius than normal white dwarfs with similar masses," says Swihart. "It will continue cooling and contracting and, in about two billion years, it will look identical to many of the extremely low mass white dwarfs that we already know about."

Millisecond pulsars twirl hundreds of times every second. They are spun up by accreting matter from a companion, in this case from the star that became the white dwarf. Most millisecond pulsars emit gamma rays and X-rays, often when the pulsar wind, which is a stream of charged particles emanating from the rotating neutron star, collides with material emitted from a companion star.

About 80 extremely low-mass white dwarfs are known, but "this is the first precursor to an extremely low-mass white dwarf found that is likely orbiting a neutron star," says Swihart. Consequently, 4FGL J1120.0-2204 is a unique look at the tail-end of this spin-up process. All the other white dwarf-pulsar binaries that have been discovered are well past the spinning-up stage.

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Scientists dive deep into the different effects of morning and evening exercise

It is well established that exercise improves health, and recent research has shown that exercise benefits the body in different ways, depending on the time of day. However, scientists still do not know why the timing of exercise produces these different effects. To gain a better understanding, an international team of scientists recently carried out the most comprehensive study to date of exercise performed at different times of the day.

Their research shows how the body produces different health-promoting signaling molecules in an organ-specific manner following exercise depending on the time of day. These signals have a broad impact on health, influencing sleep, memory, exercise performance, and metabolic homeostasis. Their findings were recently published in the journal Cell Metabolism.

"A better understanding of how exercise affects the body at different times of day might help us to maximize the benefits of exercise for people at risk of diseases, such as obesity and type 2 diabetes," says Professor Juleen R. Zierath from Karolinska Institutet and the Novo Nordisk Foundation Center for Basic Metabolic Research (CBMR) at the University of Copenhagen.

Using exercise to fix a faulty body clock

Almost all cells regulate their biological processes over 24 hours, otherwise called a circadian rhythm. This means that the sensitivity of different tissues to the effects of exercise changes depending on the time of day. Earlier research has confirmed that exercise timing according to our circadian rhythm can optimize the health-promoting effects of exercise.

The team of international scientists wanted a more detailed understanding of this effect, so they carried out a range of experiments on mice that exercised either in the early morning or the late evening. Blood samples and different tissues, including brain, heart, muscle, liver, and fat were collected and analyzed by mass spectrometry. This allowed the scientists to detect hundreds of different metabolites and hormone signaling molecules in each tissue, and to monitor how they were changed by exercising at different times of the day.

The result is an 'Atlas of Exercise Metabolism' -- a comprehensive map of exercise-induced signaling molecules present in different tissues following exercise at different times of day.

"As this is the first comprehensive study that summarizes time and exercise dependent metabolism over multiple tissues, it is of great value to generate and refine systemic models for metabolism and organ crosstalk," adds Dominik Lutter, Head of Computational Discovery Research from the Helmholtz Diabetes Center at Helmholtz Munich.

New insights include a deeper understanding of how tissues communicate with each other, and how exercise can help to 'realign' faulty circadian rhythms in specific tissues -- faulty circadian clocks have been linked to increased risks of obesity and type 2 diabetes. Finally, the study identified new exercise-induced signaling molecules in multiple tissues, which need further investigation to understand how they can individually or collectively influence health.

"Not only do we show how different tissues respond to exercise at different times of the day, but we also propose how these responses are connected to induce an orchestrated adaptation that controls systemic energy homeostasis," says Associate Professor Jonas Thue Treebak from CBMR at the University of Copenhagen, and co-first author of the publication.

A resource for future exercise research

The study has several limitations. The experiments were carried out in mice. While mice share many common genetic, physiological, and behavioral characteristics with humans, they also have important differences. For example, mice are nocturnal, and the type of exercise was also limited to treadmill running, which can produce different results compared to high-intensity exercise. Finally, the impact of sex, age and disease were not considered in the analysis.

"Despite the limitations, it's an important study that helps to direct further research that can help us better understand how exercise, if timed correctly, can help to improve health," says Assistant Professor Shogo Sato from the Department of Biology and the Center for Biological Clocks Research at Texas A&M University, and fellow co-first author.

Fellow co-first author Kenneth Dyar, Head of Metabolic Physiology from the Helmholtz Diabetes Center at Helmholtz Munich, stressed the utility of the atlas as a comprehensive resource for exercise biologists. "While our resource provides important new perspectives about energy metabolites and known signaling molecules, this is just the tip of the iceberg. We show some examples of how our data can be mined to identify new tissue and time-specific signaling molecules," he says.

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Why do we forget? New theory proposes 'forgetting' is actually a form of learning

We create countless memories as we live our lives but many of these we forget. Why? Counter to the general assumption that memories simply decay with time, 'forgetting' might not be a bad thing -- that is according to scientists who believe it may represent a form of learning.

The scientists behind the new theory -- outlined today in leading international journal Nature Reviews Neuroscience -- suggest that changes in our ability to access specific memories are based on environmental feedback and predictability. Rather than being a bug, forgetting may be a functional feature of the brain, allowing it to interact dynamically with the environment.

In a changing world like the one we and many other organisms live in, forgetting some memories can be beneficial as this can lead to more flexible behaviour and better decision-making. If memories were gained in circumstances that are not wholly relevant to the current environment, forgetting them can be a positive change that improves our wellbeing.

So, in effect, the scientists believe we learn to forget some memories while retaining others that are important. Forgetting of course comes at the cost of lost information, but a growing body of research indicates that, at least in some cases, forgetting is due to altered memory access rather than memory loss.

The new theory has been proposed by Dr Tomás Ryan, Associate Professor in the School of Biochemistry and Immunology and the Trinity College Institute of Neuroscience at Trinity College Dublin, and Dr Paul Frankland, Professor in the Department of Psychology at the University of Toronto and the Hospital for Sick Children in Toronto.

Both Dr Ryan and Dr Frankland are fellows of the Canadian global research organization CIFAR, which enabled this collaboration through its Child & Brain Development program, which is pursuing interdisciplinary work in this area.

Dr Ryan, whose research team is based in the Trinity Biomedical Sciences Institute (TBSI), said:

"Memories are stored in ensembles of neurons called 'engram cells' and successful recall of these memories involves the reactivation of these ensembles. The logical extension of this is that forgetting occurs when engram cells cannot be reactivated. The memories themselves are still there, but if the specific ensembles cannot be activated they can't be recalled. It's as if the memories are stored in a safe but you can't remember the code to unlock it.

"Our new theory proposes that forgetting is due to circuit remodelling that switches engram cells from an accessible to an inaccessible state. Because the rate of forgetting is impacted by environmental conditions, we propose that forgetting is actually a form of learning that alters memory accessibility in line with the environment and how predictable it is."

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Past eight years: Warmest since modern recordkeeping began

Earth's global average surface temperature in 2021 tied with 2018 as the sixth warmest on record, according to independent analyses done by NASA and the National Oceanic and Atmospheric Administration (NOAA).

Continuing the planet's long-term warming trend, global temperatures in 2021 were 1.5 degrees Fahrenheit (0.85 degrees Celsius) above the average for NASA's baseline period, according to scientists at NASA's Goddard Institute for Space Studies (GISS) in New York. NASA uses the period from 1951-1980 as a baseline to see how global temperature changes over time.

Collectively, the past eight years are the warmest years since modern recordkeeping began in 1880. This annual temperature data makes up the global temperature record -- which tells scientists the planet is warming.

According to NASA's temperature record, Earth in 2021 was about 1.9 degrees Fahrenheit (or about 1.1 degrees Celsius) warmer than the late 19th century average, the start of the industrial revolution.

"Science leaves no room for doubt: Climate change is the existential threat of our time," said NASA Administrator Bill Nelson. "Eight of the top 10 warmest years on our planet occurred in the last decade, an indisputable fact that underscores the need for bold action to safeguard the future of our country -- and all of humanity. NASA's scientific research about how Earth is changing and getting warmer will guide communities throughout the world, helping humanity confront climate and mitigate its devastating effects."

This warming trend around the globe is due to human activities that have increased emissions of carbon dioxide and other greenhouse gases into the atmosphere. The planet is already seeing the effects of global warming: Arctic sea ice is declining, sea levels are rising, wildfires are becoming more severe and animal migration patterns are shifting. Understanding how the planet is changing -- and how rapidly that change occurs -- is crucial for humanity to prepare for and adapt to a warmer world.

Weather stations, ships, and ocean buoys around the globe record the temperature at Earth's surface throughout the year. These ground-based measurements of surface temperature are validated with satellite data from the Atmospheric Infrared Sounder (AIRS) on NASA's Aqua satellite. Scientists analyze these measurements using computer algorithms to deal with uncertainties in the data and quality control to calculate the global average surface temperature difference for every year. NASA compares that global mean temperature to its baseline period of 1951-1980. That baseline includes climate patterns and unusually hot or cold years due to other factors, ensuring that it encompasses natural variations in Earth's temperature.

Many factors affect the average temperature any given year, such as La Nina and El Nino climate patterns in the tropical Pacific. For example, 2021 was a La Nina year and NASA scientists estimate that it may have cooled global temperatures by about 0.06 degrees Fahrenheit (0.03 degrees Celsius) from what the average would have been.

A separate, independent analysis by NOAA also concluded that the global surface temperature for 2021 was the sixth highest since record keeping began in 1880. NOAA scientists use much of the same raw temperature data in their analysis and have a different baseline period (1901-2000) and methodology.

"The complexity of the various analyses doesn't matter because the signals are so strong," said Gavin Schmidt, director of GISS, NASA's leading center for climate modeling and climate change research. "The trends are all the same because the trends are so large."

NASA's full dataset of global surface temperatures for 2021, as well as details of how NASA scientists conducted the analysis, are publicly available from GISS (https://data.giss.nasa.gov/gistemp).

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'Slushy' magma ocean led to formation of the Moon’s crust

Scientists have shown how the freezing of a 'slushy' ocean of magma may be responsible for the composition of the Moon's crust.

The scientists, from the University of Cambridge and the Ecole normale supérieure de Lyon, have proposed a new model of crystallisation, where crystals remained suspended in liquid magma over hundreds of millions of years as the lunar 'slush' froze and solidified. The results are reported in the journal Geophysical Review Letters.

Over fifty years ago, Apollo 11 astronauts collected samples from the lunar Highlands. These large, pale regions of the Moon -- visible to the naked eye -- are made up of relatively light rocks called anorthosites. Anorthosites formed early in the history of the Moon, between 4.3 and 4.5 billion years ago.

Similar anorthosites, formed through the crystallisation of magma, can be found in fossilised magma chambers on Earth. Producing the large volumes of anorthosite found on the Moon however, would have required a huge global magma ocean.

Scientists believe that the Moon formed when two protoplanets, or embryonic worlds, collided. The larger of these two protoplanets became the Earth, and the smaller became the Moon. One of the outcomes of this collision was that the Moon was very hot -- so hot that its entire mantle was molten magma, or a magma ocean.

"Since the Apollo era, it has been thought that the lunar crust was formed by light anorthite crystals floating at the surface of the liquid magma ocean, with heavier crystals solidifying at the ocean floor," said co-author Chloé Michaut from Ecole normale supérieure de Lyon. "This 'flotation' model explains how the lunar Highlands may have formed."

However, since the Apollo missions many lunar meteorites have been analysed and the surface of the Moon has been extensively studied. Lunar anorthosites appear more heterogenous in their composition than the original Apollo samples, which contradicts a flotation scenario where the liquid ocean is the common source of all anorthosites.

The range of anorthosite ages -- over 200 million years -- is difficult to reconcile with an ocean of essentially liquid magma whose characteristic solidification time is close to 100 million years.

"Given the range of ages and compositions of the anorthosites on the Moon, and what we know about how crystals settle in solidifying magma, the lunar crust must have formed through some other mechanism," said co-author Professor Jerome Neufeld from Cambridge's Department of Applied Mathematics and Theoretical Physics.

Michaut and Neufeld developed a mathematical model to identify this mechanism.

In the low lunar gravity, the settling of crystal is difficult, particularly when strongly stirred by the convecting magma ocean. If the crystals remain suspended as a crystal slurry, then when the crystal content of the slurry exceeds a critical threshold, the slurry becomes thick and sticky, and the deformation slow.

This increase of crystal content occurs most dramatically near the surface, where the slushy magma ocean is cooled, resulting in a hot, well-mixed slushy interior and a slow-moving, crystal rich lunar 'lid'.

"We believe it's in this stagnant 'lid' that the lunar crust formed, as lightweight, anorthite-enriched melt percolated up from the convecting crystalline slurry below," said Neufeld. "We suggest that cooling of the early magma ocean drove such vigorous convection that crystals remained suspended as a slurry, much like the crystals in a slushy machine."

Enriched lunar surface rocks likely formed in magma chambers within the lid, which explains their diversity. The results suggest that the timescale of lunar crust formation is several hundreds of million years, which corresponds to the observed ages of the lunar anorthosites.

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World's largest fish breeding area discovered in Antarctica

Near the Filchner Ice Shelf in the south of the Antarctic Weddell Sea, a research team has found the world's largest fish breeding area known to date. A towed camera system photographed and filmed thousands of nests of icefish of the species Neopagetopsis ionah on the seabed. The density of the nests and the size of the entire breeding area suggest a total number of about 60 million icefish breeding at the time of observation. These findings provide support for the establishment of a Marine Protected Area in the Atlantic sector of the Southern Ocean. A team led by Autun Purser from the Alfred Wegener Institute publish their results in the current issue of the scientific journal Current Biology.

The joy was great when, in February 2021, researchers viewed numerous fish nests on the monitors aboard the German research vessel Polarstern, which their towed camera system transmitted live to the vessel from the seabed, 535 to 420 metres below the ship, from the seafloor of the Antarctic Weddell Sea. The longer the mission lasted, the more the excitement grew, finally ending in disbelief: nest followed nest, with later precise evaluation showing that there were on average one breeding site per three square metres, with the team even finding a maximum of one to two active nests per square metre.

The mapping of the area suggests a total extent of 240 square kilometres, which is roughly the size of the island of Malta. Extrapolated to this area size, the total number of fish nests was estimated to be about 60 million. "The idea that such a huge breeding area of icefish in the Weddell Sea was previously undiscovered is totally fascinating," says Autun Purser, deep-sea biologist at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) and lead author of the current publication. After all, the Alfred Wegener Institute has been exploring the area with its icebreaker Polarstern since the early 1980s. So far, only individual Neopagetopsis ionah or small clusters of nests have been detected here.

The unique observations are made with a so-called OFOBS, the Ocean Floor Observation and Bathymetry System. It is a camera sledge built to survey the seafloor of extreme environments, like ice-covered seas. It is towed on a special fibre-optic and power cable normally at a speed of about one half to one knot, about one and half metres above the seafloor. "After the spectacular discovery of the many fish nests, we thought about a strategy on board to find out how large the breeding area was -- there was literally no end in sight. The nests are three quarters of a metre in diameter -- so they are much larger than the structures and creatures, some of which are only centimetres in size, that we normally detect with the OFOBS system," Autun Purser reports. "So, we were able to increase the height above ground to about three metres and the towing speed to a maximum of three knots, thus multiplying the area investigated. We covered an area of 45,600 square metres and counted an incredible 16,160 fish nests on the photo and video footage," says the AWI expert.

Based on the images, the team was able to clearly identify the round fish nests, about 15 centimetres deep and 75 centimetres in diameter, which were made distinct from the otherwise muddy seabed by a round central area of small stones. Several types of fish nests were distinguished: "Active" nests, containing between 1,500 and 2,500 eggs and guarded in three-quarters of the cases by an adult icefish of the species Neopagetopsis ionah, or nests which contained only eggs; there were also unused nests, in the vicinity of which either only a fish without eggs could be seen, or a dead fish. The researchers mapped the distribution and density of the nests using OFOBS's longer-range but lower-resolution side scan sonars, which recorded over 100,000 nests.

The scientists combined their results with oceanographic and biological data. The result: the breeding area corresponds spatially with the inflow of warmer deep water from the Weddell Sea onto the higher shelf. With the help of transmitter equipped seals, the multidisciplinary team was also able to prove that the region is also a popular destination for Weddell seals. 90 per cent of the seals' diving activities took place within the region of active fish nests, where they presumably go in search of food. No wonder, the researchers calculate the biomass of the ice fish colony there at 60 thousand tonnes.

With its biomass, this huge breeding area is an extremely important ecosystem for the Weddell Sea and, according to current research, likely to be the most spatially extensive contiguous fish breeding colony discovered worldwide to date, the experts report in the publication in Current Biology.

German Federal Research Minister Bettina Stark-Watzinger said: "My congratulations to the researchers involved on their fascinating discovery. After the MOSAiC expedition, German marine and polar research has once more reaffirmed its outstanding position. German research vessels are floating environmental research laboratories. They continue to sail the polar seas and our oceans almost non-stop, serving as platforms for science aimed at generating important findings to support climate and environmental protection. Funding by the Federal Ministry of Education and Research (BMBF) provides German marine and polar research with one of the most state-of-the-art research vessel fleets worldwide. This discovery can make an important contribution towards protecting the Antarctic environment. The BMBF will continue to work towards this goal under the umbrella of the United Nations Decade of Ocean Science for Sustainable Development that runs until 2030."

For AWI Director and deep-sea biologist Prof. Antje Boetius, the current study is a sign of how urgent it is to establish marine protected areas in Antarctica. "This great discovery was enabled by a specific under-ice survey technology we developed during my ERC Grant. It shows how important it is to be able to investigate unknown ecosystems before we disturb them. Considering how little known the Antarctic Weddell Sea is, this underlines all the more the need of international efforts to establish a Marine Protected Area (MPA)," Antje Boetius classifies the results of the study, in which she was not directly involved. A proposal for such an MPA has been prepared under the lead of the Alfred Wegener Institute and is defended since 2016 by the European Union and its member states as well as other supporting countries in the international Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR).

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Epigenetic mechanisms for parent-specific genetic activation decoded

Hereditary diseases as well as cancers and cardiovascular diseases may be associated with a phenomenon known as genomic imprinting, in which only the maternally or paternally inherited gene is active. An international research team involving scientists at the Technical University of Munich (TUM), the Max Planck Institute for Molecular Genetics (MPIMG) in Berlin and Harvard University in Cambridge (USA) has now investigated the mechanisms responsible for the deactivation of the genes.

Our cells contain the entire genetic information from our mother and our father. From each of them we inherit 23 chromosomes that contain our DNA. Two copies of each gene are therefore present in our genome and, as a general rule, both are active. This has the advantage that defective mutations inherited from the mother or father are generally cancelled out by the other copy of the gene.

However, for around one percent of our genes, only the gene inherited from the father or mother is active, while the other is deactivated, a phenomenon known as genomic imprinting.

Approach for treating diseases

"Many genetic and epigenetic diseases are associated with genomic imprinting, such as Beckwith-Wiedemann syndrome, Angelman syndrome and Prader-Willi syndrome," explains Dr. Daniel Andergassen, the head of the Independent Junior Research Group at the Institute of Pharmacology and Toxicology at TUM. "If the healthy, deactivated gene could be reactivated, it would be theoretically possible to compensate for complications caused by the active, defective gene."

"But before developing future treatments, we need to understand the fundamentals," says Prof. Alexander Meissner, director at the MPIMG. "It has become clear in recent years that genomic imprinting is mediated by multiple molecular mechanisms."

Read lock for the gene

In genomic imprinting, either the "packaging" of the genetic material or the DNA itself is chemically modified. Instead of the genetic information being changed, the modifications block the gene from being read.

"These are so-called epigenetic mechanisms," says Andergassen. "The DNA can be seen as the hardware, and epigenetics as the software responsible for regulating the genes." Genetic regulation takes place in every cell in the body. All the cells contain the same genetic information, but depending on the organ, different genes are active.

Genetic scissors remove the "off switch"

Meissner and Andergassen, who at the beginning of the study where still conducting the research at Harvard University (USA) along with Dr. Zachary Smith, used mice to investigate which epigenetic mechanisms were behind the imprinting.

They used the molecular biology technique known as CRISPR-Cas9 that functions as a "genetic scissors," removing and inserting segments of DNA. The scientists removed known epigenetic "off switches" and observed whether the deactivated gene was reactivated. With this approach, they were able to link the most important epigenetic "off switches" with imprinted genes.

Hydrocarbon molecules render genes inactive

It turns out that most of the genes are inactivated through DNA methylation that attaches hydrocarbon molecules to the genetic material. Another group of genes is silenced by a set of enzymes known as Polycombs. In the placenta, an additional mechanism comes into play: In this tissue, some genes are deactivated by chemically modifying the proteins that serve as a structural scaffold for the DNA.

The small but crucial difference

Along with genomic imprinting that switches off individual genes, the researchers investigated another phenomenon. In female cells, which unlike male cells have two X chromosomes, one chromosome is entirely deactivated very early in embryonic development. This is true in almost all mammals, including humans.

"We discovered that the enzyme PRC2 plays an important role in the inactivation of the X chromosome, at least in the placenta," says Andergassen. "Once we remove this enzyme, the silent X chromosome is reactivated." The results could be significant for X-chromosome-related disease because reactivation of the silent gene could compensate for the malfunctioning active gene. In a follow-up project at TUM, Andergassen will study whether heart diseases might also be associated with epigenetics and especially with the inactive X chromosome in women. "Because our epigenetics change as we get old, it is conceivable that the X chromosome becomes active again and that the duplicate genetic activity has a negative influence," says the researcher.

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Rare African script offers clues to the evolution of writing

The world's very first invention of writing took place over 5000 years ago in the Middle East, before it was reinvented in China and Central America. Today, almost all human activities -- from education to political systems and computer code -- rely on this technology.

But despite its impact on daily life, we know little about how writing evolved in its earliest years. With so few sites of origin, the first traces of writing are fragmentary or missing altogether.

In a study just published in Current Anthropology, a team of researchers at the Max Planck Institute for the Science of Human History in Jena, Germany, showed that writing very quickly becomes 'compressed' for efficient reading and writing.

To arrive at this insight they turned to a rare African writing system that has fascinated outsiders since the early 19th century.

"The Vai script of Liberia was created from scratch in about 1834 by eight completely illiterate men who wrote in ink made from crushed berries," says lead author Dr Piers Kelly, now at the University of New England, Australia. The Vai language had never before been written down.

According to Vai teacher Bai Leesor Sherman, the script was always taught informally from a literate teacher to a single apprentice student. It remains so successful that today it is even used to communicate pandemic health messages.

"Because of its isolation, and the way it has continued to develop up until the present day, we thought it might tell us something important about how writing evolves over short spaces of time," says Kelly.

"There's a famous hypothesis that letters evolve from pictures to abstract signs. But there are also plenty of abstract letter-shapes in early writing. We predicted, instead, that signs will start off as relatively complex and then become simpler across new generations of writers and readers."

The team scrutinised manuscripts in the Vai language from archives in Liberia, the United States, and Europe. By analysing year-by-year changes in its 200 syllabic letters, they traced the entire evolutionary history of the script from 1834 onwards. Applying computational tools for measuring visual complexity, they found that the letters really did become visually simpler with each passing year.

"The original inventors were inspired by dreams to design individual signs for each syllable of their language. One represents a pregnant woman, another is a chained slave, others are taken from traditional emblems. When these signs were applied to writing spoken syllables, then taught to new people, they became simpler, more systematic and more similar to one another," says Kelly.

This pattern of simplification can be observed over much longer time scales for ancient writing systems as well.

"Visual complexity is helpful if you're creating a new writing system. You generate more clues and greater contrasts between signs, which helps illiterate learners. This complexity later gets in the way of efficient reading and reproduction, so it fades away," says Kelly.

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