Scientists find key reason why loss of smell occurs in long COVID-19

The reason some people fail to recover their sense of smell after COVID-19 is linked to an ongoing immune assault on olfactory nerve cells and an associated decline in the number of those cells, a team of scientists led by Duke Health report.

The finding, publishing online Dec. 21 in the journal Science Translational Medicine, provides an important insight into a vexing problem that has plagued millions who have not fully recovered their sense of smell after COVID-19.

While focusing on the loss smell, the finding also sheds light on the possible underlying causes of other long COVID-19 symptoms -- including generalized fatigue, shortness of breath, and brain fog -- that might be triggered by similar biological mechanisms.

"One of the first symptoms that has typically been associated with COVID-19 infection is loss of smell," said senior author Bradley Goldstein, M.D., Ph.D., associate professor in Duke's Department of Head and Neck Surgery and Communication Sciences and the Department of Neurobiology.

"Fortunately, many people who have an altered sense of smell during the acute phase of viral infection will recover smell within the next one to two weeks, but some do not," Goldstein said. "We need to better understand why this subset of people will go on to have persistent smell loss for months to years after being infected with SARS-CoV2."

In the study, Goldstein and colleagues at Duke, Harvard and the University of California-San Diego analyzed olfactory epithelial samples collected from 24 biopsies, including nine patients suffering from long-term smell loss following COVID-19.

This biopsy-based approach -- using sophisticated single-cell analyses in collaboration with Sandeep Datta, M.D., Ph.D., at Harvard University -- revealed widespread infiltration of T-cells engaged in an inflammatory response in the olfactory epithelium, the tissue in the nose where smell nerve cells are located. This unique inflammation process persisted despite the absence of detectable SARS-CoV-2 levels.

Additionally, the number of olfactory sensory neurons were diminished, possibly due to damage of the delicate tissue from the ongoing inflammation.

"The findings are striking," Goldstein said. "It's almost resembling a sort of autoimmune-like process in the nose."

Goldstein said learning what sites are damaged and what cell types are involved is a key step toward beginning to design treatments. He said the researchers were encouraged that neurons appeared to maintain some ability to repair even after the long-term immune onslaught.

"We are hopeful that modulating the abnormal immune response or repair processes within the nose of these patients could help to at least partially restore a sense of smell," Goldstein said, noting this work is currently underway in his lab.

He said the findings from this study could also inform additional research into other long-COVID-19 symptoms that might be undergoing similar inflammatory processes.

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Rwandan tree carbon stock mapped from above

As the first country, Rwanda can now present a national inventory based on a mapping of the carbon stock of each individual tree. Researchers at University of Copenhagen have developed a method to achieve this task in collaboration with Rwandan authorities and researchers.

"Large uncertainties exist for the current forest assessments internationally. By mapping the carbon stock of all individual trees, accuracy is greatly improved. Further, the way different countries make their inventories is not consistent due to different contexts, goals, and available datasets. We hope that this method will establish itself as a standard, thereby enabling better comparisons between countries," says PhD Researcher Maurice Mugabowindekwe, Department of Geosciences and Natural Resources Management (IGN), University of Copenhagen. He is first author on the scientific article presenting the new method. The article has been accepted for publication by Nature Climate Change, one of the most prominent journals for the field.

Maurice Mugabowindekwe being Rwandan himself is helpful during the work, but the choice of Rwanda for development of the method was scientifically based, he emphasizes:

"The country has a rich landscape variation including savannas, woodlands, sub-humid and humid forests, shrubland, agro-ecosystem mosaics, and urban tree ecosystems which are representative of most tropical countries. We wanted to prove the method for all these landscape types. Moreover, Rwanda is a signatory to several international agreements on forest preservation and climate change mitigation. For instance, Rwanda has pledged to restore about 80 % of its surface area by 2030 under the Bonn Challenge. So, it is highly relevant to have a reliable method for monitoring tree carbon."

First method for mapping individual trees

Preservation of natural forests and planting of new trees are recognized as vital routes to limiting climate change. However, large uncertainties regarding the carbon content of the trees have made it hard to assess the efficiency of concrete initiatives. The University of Copenhagen researchers have overcome this problem.

The new method benefits from databases which give the relationship between the extent of the crown and the total carbon content of an individual tree.

"Mapping individual trees and calculating their carbon stocks has traditionally been done in forestry, albeit at a much smaller scale. Basically, what we do equals scaling up these approaches from a very local to a national level," says Researcher Ankit Kariryaa, working 50:50 at IGN and at the Department of Computer Sciences (DIKU). Scientists from these two University of Copenhagen departments have developed the method with IGN as lead, in collaboration with other international scientists.

The new method will support Rwanda in verifying fulfilment of commitments under schemes such as the global forestry climate change mitigation scheme REDD+ or the African Forest Landscape Restoration Initiative, AFR 100.

Many trees are found outside forests

Manually mapping the trees of an entire country would be a huge endeavor and excessively costly. Thus, the new method constitutes a breakthrough since no other method would realistically be able to provide the same information at the level of individual trees.

"It is important to take a holistic approach and also include trees which are outside forests," says Ankit Kariryaa, noting that 72 % of the mapped trees were in farmlands and savannas, and 17 % in plantations.

At the same time, the relatively small proportion of trees which are found in natural forests -- 11 % of the total tree count -- comprise about 51 % of the national carbon stock of Rwanda. This is possible mainly because natural forests have a very high carbon content per tree volume, thanks to the very low human disturbance secured through national legislation.

"This suggests that conservation, regeneration, and sustainable management of natural forests is more effective at mitigating climate change than plantation," Maurice Mugabowindekwe comments.

Rainforest appears to be "a huge green blanket"

It is paramount that the computer can distinguish the individual trees. This is because the relationship between the extent of the crown and the total carbon content of a tree is very different depending on the size of a tree. One very large tree will have a much higher carbon content than a group of trees with the same joint crown extent. So, if the group was mistaken for one tree, the carbon content would be significantly overestimated. A deep neural network is used for detecting the individual trees.

"Especially for the rainforest, it is highly challenging to determine how many different trees are present in an image. At first glance, the forest just appears to be one huge green blanket. But by using methods from Machine Learning and Computer Vision, our system can also be applied to identify the individual trees in overstory of dense forests," explains Christian Igel, Professor of Machine Learning at DIKU.

Training the computer on verified samples is at the core of Machine Learning. In the Rwandan study, the computer was trained on a set of some 97,500 manually delineated tree crowns representing the full range of biogeographical conditions across the country.

The study used publicly available aerial and satellite images of Rwanda at 0.25 x 0.25 m resolution. These images were collected in June-August 2008 and 2009 and were provided by the Rwanda Land Management and Use Authority and the University of Rwanda. More than 350 million trees were mapped.

Applications beyond Rwanda

Nine researchers from University of Copenhagen visited Rwanda in July 2022 with a dual purpose of field work and presenting results from the first nation-wide mapping to the Rwandan authorities and other stakeholders in the country's forestry sector.

"The presentation was well received," reports Maurice Mugabowindekwe. He was immediately tasked by the Rwandan authorities with an updated mapping based on newer aerial images acquired in 2019. This work is now ongoing.

Further, the method has already been tested for a handful of countries besides Rwanda. These include Tanzania, Burundi, Uganda, and Kenya.

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Unveiling the mysteries of senescent cells and their effect on aging and human health

Multiple researchers at the Jackson Laboratory are taking part in an ambitious research program spanning several top research institutions to study senescent cells. Senescent cells stop dividing in response to stressors and seemingly have a role to play in human health and the aging process. Recent research with mice suggests that clearing senescent cells delays the onset of age-related dysfunction and disease as well as all-cause mortality.

Could therapies that remove senescent cells -- called senotherapeutics -- also improve the health of humans as we age? Answering this question and more has the potential to significantly advance human health, and the National Institutes of Health (NIH) has launched an extensive research initiative for this very purpose.

The SenNet Consortium, a collaboration of institutions from throughout the United States, was initially launched in 2021 with centers established to gather and analyze human data. The researchers will collect and analyze 18 tissues from healthy humans across lifespan to discern the full scope of senescent cells and how they may contribute to the aging process. The work of the SenNet Consortium was recently presented in a paper published in Nature Aging.

Along with colleagues from Mayo Clinic, University of Texas Health Science center at San Antonio, and UConn Health, JAX Professor Paul Robson, Ph.D. is taking part in the mapping of four human tissue types (kidney, adipose, pancreas, and placenta) within the KAPP-Sen Tissue Mapping Center. The Robson Lab also leads the Biological Analysis Core, and the Data Analysis Core of KAPP-Sen TMC is led by JAX Associate Professor Duygu Ucar, Ph.D., and JAX Professor Jeff Chuang, Ph.D.

SenNet has also grown over the past year to add mouse-focused investigators, and JAX was designated as a Tissue Mapping Center (TMC) for SenNet in August 2022, supported by a four-year, $10.7 million grant from the National Institute on Aging. JAX-Sen is led by Professor and Maxine Groffsky Endowed Chair Nadia Rosenthal, Ph.D., FMedSci with co-principal investigators Robson, JAX Associate Professor Ron Korstanje, Ph.D., and UConn Health's Ming Xu, Ph.D. Associate Professor Sheng Li and Principal Computational Scientist Matt Mahoney lead the Data Analysis Core of the JAX-Sen TMC.

JAX is poised to make substantial contributions to SenNet by profiling senescent cells in kidney, placenta, pancreas, and heart, all tissues that are relevant to chronic diseases of aging. The team will draw upon its genetically diverse mouse resources, including Diversity Outbred mouse populations, to model a range of molecular senescence traits, as well as inbred mice specifically engineered to help visualize senescent cell subsets.

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Human brain organoids implanted into mouse cortex respond to visual stimuli for first time

A team of engineers and neuroscientists has demonstrated for the first time that human brain organoids implanted in mice have established functional connectivity to the animals' cortex and responded to external sensory stimuli. The implanted organoids reacted to visual stimuli in the same way as surrounding tissues, an observation that researchers were able to make in real time over several months thanks to an innovative experimental setup that combines transparent graphene microelectrode arrays and two-photon imaging.

The team, led by Duygu Kuzum, a faculty member in the University of California San Diego Department of Electrical and Computer Engineering, details their findings in the Dec. 26 issue of the journal Nature Communications. Kuzum's team collaborated with researchers from Anna Devor's lab at Boston University; Alysson R. Muotri's lab at UC San Diego; and Fred H. Gage's lab at the Salk Institute.

Human cortical organoids are derived from human induced pluripotent stem cells, which are usually derived themselves from skin cells. These brain organoids have recently emerged as promising models to study the development of the human brain, as well as a range of neurological conditions.

But until now, no research team had been able to demonstrate that human brain organoids implanted in the mouse cortex were able to share the same functional properties and react to stimuli in the same way. This is because the technologies used to record brain function are limited, and are generally unable to record activity that lasts just a few milliseconds.

The UC San Diego-led team was able to solve this problem by developing experiments that combine microelectrode arrays made from transparent graphene, and two-photon imaging, a microscopy technique that can image living tissue up to one millimeter in thickness.

"No other study has been able to record optically and electrically at the same time," said Madison Wilson, the paper's first author and a Ph.D. student in Kuzum's research group at UC San Diego. "Our experiments reveal that visual stimuli evoke electrophysiological responses in the organoids, matching the responses from the surrounding cortex."

The researchers hope that this combination of innovative neural recording technologies to study organoids will serve as a unique platform to comprehensively evaluate organoids as models for brain development and disease, and investigate their use as neural prosthetics to restore function to lost, degenerated or damaged brain regions.

"This experimental setup opens up unprecedented opportunities for investigations of human neural network-level dysfunctions underlying developmental brain diseases," said Kuzum.

Kuzum's lab first developed the transparent graphene electrodes in 2014 and has been advancing the technology since then. The researchers used platinum nanoparticles to lower the impedance of graphene electrodes by 100 times while keeping them transparent. The low-impedance graphene electrodes are able to record and image neuronal activity at both the macroscale and single cell levels.

By placing an array of these electrodes on top of the transplanted organoids, researchers were able to record neural activity electrically from both the implanted organoid and the surrounding host cortex in real time. Using two-photon imaging, they also observed that mouse blood vessels grew into the organoid providing necessary nutrients and oxygen to the implant.

Researchers applied a visual stimulus-an optical white light LED-to the mice with implanted organoids, while the mice were under two-photon microscopy. They observed electrical activity in the electrode channels above the organoids showing that the organoids were reacting to the stimulus in the same way as surrounding tissue. The electrical activity propagated from the area closest to the visual cortex in the implanted organoids area through functional connections. In addition, their low noise transparent graphene electrode technology enabled electrical recording of spiking activity from the organoid and the surrounding mouse cortex. Graphene recordings showed increases in the power of gamma oscillations and phase locking of spikes from organoids to slow oscillations from mouse visual cortex. These findings suggest that the organoids had established synaptic connections with surrounding cortex tissue three weeks after implantation, and received functional input from the mouse brain. Researchers continued these chronic multimodal experiments for eleven weeks and showed functional and morphological integration of implanted human brain organoids with the host mice cortex.

Next steps include longer experiments involving neurological disease models, as well as incorporating calcium imaging in the experimental set up to visualize spiking activity in organoid neurons. Other methods could also be used to trace axonal projections between organoid and mouse cortex.

"We envision that, further along the road, this combination of stem cells and neurorecording technologies will be used for modeling disease under physiological conditions; examining candidate treatments on patient-specific organoids; and evaluating organoids' potential to restore specific lost, degenerated or damaged brain regions," Kuzum said.

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Precise solar observations fed millions in ancient Mexico

Without clocks or modern tools, ancient Mexicans watched the sun to maintain a farming calendar that precisely tracked seasons and even adjusted for leap years.

Before the Spanish arrival in 1519, the Basin of Mexico's agricultural system fed a population that was extraordinarily large for the time. Whereas Seville, the largest urban center in Spain, had a population of fewer than 50,000, the Basin, now known as Mexico City, was home to as many as 3 million people.

To feed so many people in a region with a dry spring and summer monsoons required advanced understanding of when seasonal variations in weather would arrive. Planting too early, or too late, could have proved disastrous. The failure of any calendar to adjust for leap-year fluctuations could also have led to crop failure.

Though colonial chroniclers documented the use of a calendar, it was not previously understood how the Mexica, or Aztecs, were able to achieve such accuracy. New UC Riverside research demonstrates how they did it. They used the mountains of the Basin as a solar observatory, keeping track of the sunrise against the peaks of the Sierra Nevada mountains.

"We concluded they must have stood at a single spot, looking eastwards from one day to another, to tell the time of year by watching the rising sun," said Exequiel Ezcurra, distinguished UCR professor of ecology who led the research.

To find that spot, the researchers studied Mexica manuscripts. These ancient texts referred to Mount Tlaloc, which lies east of the Basin. The research team explored the high mountains around the Basin and a temple at the mountain's summit. Using astronomical computer models, they confirmed that a long causeway structure at the temple aligns with the rising sun on Feb. 24, the first day of the Aztec new year.

"Our hypothesis is that they used the whole Valley of Mexico. Their working instrument was the Basin itself. When the sun rose at a landmark point behind the Sierras, they knew it was time to start planting," Ezcurra said.

The sun, as viewed from a fixed point on Earth, does not follow the same trajectory every day. In winter, it runs south of the celestial equator and rises toward the southeast. As summer approaches, because of the Earth's tilt, sunrise moves northeast, a phenomenon called solar declination.

This study may be the first to demonstrate how the Mexica were able to keep time using this principle, the sun, and the mountains as guiding landmarks. Though some may be familiar with the "Aztec calendar," that is an incorrect name given to the Sun Stone, arguably the most famous work of Aztec sculpture used solely for ritual and ceremonial purposes.

"It did not have any practical use as a celestial observatory. Think of it as a monument, like Nelson's Column in Trafalgar Square or Lincoln's Memorial in Washington, D.C.," Ezcurra said.

Learning about Aztec tools that did have practical use offers a lesson about the importance of using a variety of methods to solve questions about the natural world.

"The same goals can be achieved in different ways. It can be difficult to see that sometimes. We don't always need to rely solely on modern technology," Ezcurra said. "The Aztecs were just as good or better as the Europeans at keeping time, using their own methods."

The Aztec observatory could also have a more modern function, according to Ezcurra. Comparing old images of the Basin of Mexico to current ones shows how the forest is slowly climbing up Mount Tlaloc, likely as a result of an increase in average temperatures at lower elevation.

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Designing with DNA

Marvel at the tiny nanoscale structures emerging from research labs at Duke University and Arizona State University, and it's easy to imagine you're browsing a catalog of the world's smallest pottery.

A new paper reveals some of the teams' creations: itty-bitty vases, bowls, and hollow spheres, one hidden inside the other, like housewares for a Russian nesting doll.

But instead of making them from wood or clay, the researchers designed these objects out of threadlike molecules of DNA, bent and folded into complex three-dimensional objects with nanometer precision.

These creations demonstrate the possibilities of a new open-source software program developed by Duke Ph.D. student Dan Fu with his adviser John Reif. Described December 23 in the journal Science Advances, the software lets users take drawings or digital models of rounded shapes and turn them into 3D structures made of DNA.

The DNA nanostructures were assembled and imaged by co-authors Raghu Pradeep Narayanan and Abhay Prasad in professor Hao Yan's lab at Arizona State. Each tiny hollow object is no more than two millionths of an inch across. More than 50,000 of them could fit on the head of a pin.

But the researchers say these are more than mere nano-sculptures. The software could allow researchers to create tiny containers to deliver drugs, or molds for casting metal nanoparticles with specific shapes for solar cells, medical imaging and other applications.

To most people, DNA is the blueprint of life; the genetic instructions for all living things, from penguins to poplar trees. But to teams like Reif's and Yan's, DNA is more than a carrier of genetic information -- it's source code and construction material.

There are four "letters," or bases, in the genetic code of DNA, which pair up in a predictable way in our cells to form the rungs of the DNA ladder. It's these strict base-pairing properties of DNA -- A with T, and C with G -- that the researchers have co-opted. By designing DNA strands with specific sequences, they can "program" the strands to piece themselves together into different shapes.

The method involves folding one or a few long pieces of single-stranded DNA, thousands of bases long, with help from a few hundred short DNA strands that bind to complementary sequences on the long strands and "staple" them in place.

Researchers have been experimenting with DNA as a construction material since the 1980s. The first 3D shapes were simple cubes, pyramids, soccer balls -- geometric shapes with coarse and blocky surfaces. But designing structures with curved surfaces more akin to those found in nature has been tricky. The team's aim is to expand the range of shapes that are possible with this method.

To do that, Fu developed software called DNAxiS. The software relies on a way to build with DNA described in 2011 by Yan, who was a postdoc with Reif at Duke 20 years ago before joining the faculty at Arizona State. It works by coiling a long DNA double helix into concentric rings that stack on each other to form the contours of the object, like using coils of clay to make a pot. To make the structures stronger, the team also made it possible to reinforce them with additional layers for increased stability.

Fu shows off the variety of forms they can make: cones, gourds, clover leaf shapes. DNAxiS is the first software tool that lets users design such shapes automatically, using algorithms to determine where to place the short DNA "staples" to join the longer DNA rings together and hold the shape in place.

"If there are too few, or if they're in the wrong position, the structure won't form correctly," Fu said. "Before our software, the curvature of the shapes made this an especially difficult problem."

Given a model of a mushroom shape, for example, the computer spits out a list of DNA strands that would self-assemble into the right configuration. Once the strands are synthesized and mixed in a test tube, the rest takes care of itself: by heating and cooling the DNA mixture, within as little as 12 hours "it sort of magically folds up into the DNA nanostructure," Reif said.

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Appreciating the value of elephants

New research examining the services and benefits of elephants has revealed many values are often overlooked when deciding how they should be protected.

The collaboration between universities in England and South Africa, including the University of Portsmouth, found conservation strategies often have a narrow focus and tend to prioritise certain values of nature, such as economic or ecological, over moral ones.

When looking specifically at elephants, the study found financial benefits including ecotourism, trophy hunting and as a source of ivory or labour, often conflicts with the animal's ecological, cultural and spiritual contributions.

The authors argue not fully understanding or considering the value systems of all stakeholders involved in conservation, including local people, leads to social inequality, conflict and unsustainable strategies.

Study co-author Antoinette van de Water, from the University of KwaZulu-Natal in South Africa, said: "We chose to look at elephants as the case study because their conservation can be especially challenging and contentious.

"We're not saying economic contributions aren't important, but there's a lot of different values at play and they all need to be considered in conservation strategies if they are going to succeed."

The study also highlights conservation decision makers tend to take a single worldview when considering the value of nature.

Co-author Dr Lucy Bates, from the University of Portsmouth, explained: "Whether it's economic, ecological, or social, a blanket approach to values can impact the success of a conservation strategy.

"Consider something like the ivory trade for example. International trade in ivory is illegal, but many southern African countries want to restart the trade leading to contention across the African continent. If you focus less on the potential economic value of ivory, and turn to other ways elephants can support communities, it can be a game-changer.

"On a smaller scale, you can also apply this framework to defining protected areas and what land could be made available to elephants. By listening to those living in these areas, you can get a clear understanding of how decisions will affect human life as well, and work out ways to resolve any issues."

The paper, published in Ecosystems Services, says nature's non-material benefits include recreation, inspiration, mental health, and social cohesion.

But it points out broader moral values, such as human rights, environmental justice, rights of nature and intergenerational legacy, also have a big part to play in the success of conservation.

The study recommends incorporating moral values related to biodiversity conservation into the valuation framework to create a positive loop between benefits to humans and to nature.

The researchers believe that this approach will help policymakers and managers have a better understanding of what elephants mean to people, why elephants are important in themselves, and what values and interests are at stake. It can also be applied to other species and ecosystems.

"What is really needed is a change of thinking," added Antoinette van de Water.

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Hunter-gatherer social ties spread pottery-making far and wide

Analysis of more than 1,200 vessels from hunter-gatherer sites has shown that pottery-making techniques spread vast distances over a short period of time through social traditions being passed on.

The team, which includes researchers from the University of York and the British Museum, analysed the remains of 1,226 pottery vessels from 156 hunter-gatherer sites across nine countries in Northern and Eastern Europe. They combined radiocarbon dating, together with data on the production and decoration of ceramic vessels, and analysis of the remains of food found inside the pots.

Their findings, published in the journal Nature Human Behaviour, suggest that pottery-making spread rapidly westwards from 5,900 BCE onwards and took only 300-400 years to advance over 3,000 km, equivalent to 250 km in a single generation.

Professor Oliver Craig, from the University of York's Department of Archaeology, said: "Our analysis of the ways pots were designed and decorated as well as new radiocarbon dates suggests that knowledge of pottery spread through a process of cultural transmission.

"By this we mean that the activity spread by the exchange of ideas between groups of hunter-gatherers living nearby, rather than through migration of people or an expanding population as we see for other key changes in human history such as the introduction of agriculture."

"That methods of pottery-making spread so far and so fast through the passing on of ideas is quite surprising. Specific knowledge may have been shared through marriages or at centres of aggregation, specific points in the landscape where groups of hunter-gatherers came together perhaps at certain times of the year."

By studying traces of organic materials left in the pots, the team demonstrated that the pottery was used for cooking, so the ideas of pottery-making may have been spread through shared culinary traditions.

Carl Heron, from the British Museum, said: "We found evidence that the vessels were used for cooking a wide range of animals, fish and plants, and this variety suggests that the drivers for making the pottery were not in response to a particular need, such as detoxifying plants or processing fish, as has previously been suggested.

"We also found patterns suggesting that pottery use was transmitted along with knowledge of their manufacture and decoration. These can be seen as culinary traditions that were rapidly transmitted with the artefacts themselves."

The world's earliest pottery containers come from East Asia and may have spread rapidly eastwards through Siberia, before being taken up by hunter-gatherer societies across Northern Europe, long before the arrival of farming.

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The world's largest turbulence simulation unmasks the flow of energy in astrophysical plasmas

Researchers have uncovered a previously hidden heating process that helps explain how the atmosphere that surrounds the Sun called the "solar corona" can be vastly hotter than the solar surface that emits it.

The discovery at the U.S. Department of Energy's (DOE) Princeton Plasma Physics Laboratory (PPPL) could improve tackling a range of astrophysical puzzles such as star formation, the origin of large-scale magnetic fields in the universe, and the ability to predict eruptive space weather events that can disrupt cell phone service and black out power grids on Earth. Understanding the heating process also has implications for fusion research.

Breakthrough

"Our direct numerical simulation is the first to provide clear identification of this heating mechanism in 3D space," said Chuanfei Dong, a physicist at PPPL and Princeton University who unmasked the process by conducting 200 million hours of computer time for the world's largest simulation of its kind."Current telescope and spacecraft instruments may not have high enough resolution to identify the process occurring at small scales," said Dong, who details the breakthrough in the journal Science Advances.

The hidden ingredient is a process called magnetic reconnection that separates and violently reconnects magnetic fields in plasma, the soup of electrons and atomic nuclei that forms the solar atmosphere. Dong's simulation revealed how rapid reconnection of the magnetic field lines turns the large-scale turbulent energy into small-sale internal energy. As a consequence the turbulent energy is efficiently converted to thermal energy at small scales, thus superheating the corona.

"Think of putting cream in coffee," Dong said. "The drops of cream soon become whorls and slender curls. Similarly, magnetic fields form thin sheets of electric current that break up due to magnetic reconnection. This process facilitates the energy cascade from large-scale to small-scale, making the process more efficient in the turbulent solar corona than previously thought."

When the reconnection process is slow while the turbulent cascade is fast, reconnection cannot affect the transfer of energy across scales, he said. But when the reconnection rate becomes fast enough to exceed the traditional cascade rate, reconnection can move the cascade toward small scales more efficiently.

It does this by breaking and rejoining the magnetic field lines to generate chains of small twisted lines called plasmoids. This changes the understanding of the turbulent energy cascade that has been widely accepted for more than half a century, the paper says. The new finding ties the energy transfer rate to how fast the plasmoids grow, enhancing the transfer of energy from large to small scales and strongly heating the corona at these scales.

The new discovery demonstrates a regime with an unprecedentedly large magnetic Reynolds number as in the solar corona. The large number characterizes the new high energy transfer rate of the turbulent cascade. "The higher the magnetic Reynolds number is, the more efficient the reconnection-driven energy transfer is," said Dong, who is moving to Boston University to take up a faculty position.

200 million hours

"Chuanfei has carried out the world's largest turbulence simulation of its kind that has taken over 200 million computer CPUs [central processing units] at the NASA Advanced Supercomputing (NAS) facility," said PPPL physicist Amitava Bhattacharjee, a Princeton professor of astrophysical sciences who supervised the research. "This numerical experiment has produced undisputed evidence for the first time of a theoretically predicted mechanism for a previously undiscovered range of turbulent energy cascade controlled by the growth of the plasmoids.

"His paper in the high-impact journal Science Advances completes the computational program he began with his earlier 2D results published in Physical Review Letters. These papers form a coda to the impressive work that Chuanfei has done as a member of the Princeton Center for Heliophysics," a joint Princeton and PPPL facility. "We are grateful for a PPPL LDRD [Laboratory Directed Research & Development] grant that facilitated this work, and to the NASA High-End Computing (HEC) program for its generous allocation of computer time."

The impact of this finding in astrophysical systems across a range of scales can be explored with current and future spacecraft and telescopes. Unpacking the energy transfer process across scales will be crucial to solving key cosmic mysteries, the paper said.

Read more at Science Daily

Ethereal color variant of mysterious plant is actually a new species

Green leaves and photosynthesis were once considered essential characteristics of plants. However, some plants have stopped performing photosynthesis and take the nutrients they need from other organisms instead. One such mycoheterotrophic plant is ghostly-looking Monotropastrum humile that is widely found across East and Southeast Asia. It often grows in woodlands where there is little sunlight, obtaining the nutrients it needs by feeding off the hyphae of fungi. Despite its wide distribution, it was previously believed that only one species of this plant existed in the world. However, Professor SUETSUGU Kenji and colleagues have discovered that a variant found in Japan is actually a new species, shaking up our understanding of this unusual-looking genus of plants.

It has rosy pink petals and stems resembling milk glass, giving it a beautiful, otherworldly appearance. As it was first found around Kirishima in Kagoshima Prefecture, Japan, the new species has been named Monotropastrum kirishimense.

Originally, this new species was tentatively treated as a color variant of M. humile, known as M. humile f. roseum. Thus began an extensive and multifaceted 20-year study to determine how exactly these plants differed. Specimens were collected from throughout Japan and Taiwan, as well as Vietnam.

Results of various analyses revealed morphological differences, including the following; M. kirishimense flowers and ovaries are more rounded than those of M. humile, and its rootball is more obscured by the surrounding soil (in contrast to M. humile's protruding root tips). M. kirishimense individuals are shorter above ground (under 5cm) and longer below ground (over 10cm). The flowering season is different too; M. humile flowers bloom approximately 40 days earlier than M. kirishimense. As the two plant species have the same primary pollinator (the bumblebee Bombus diversus), this difference in flowering times can reduce heterospecific pollen deposition, helping to ensure conspecific mating, and thereby preventing them from producing hybrids.

There are several other possible reasons why M. kirishimense and M. humile may have evolved into separate species. One possibility is that they have become specialized in feeding on different fungi, which has led to reproductive isolation, or the inability to produce offspring together. This process is known as resource partitioning and is one of the major ways that species can evolve from a common ancestor. Genetic analysis of mycobionts revealed that M. kirishimense has a consistent, specialized association with a particular lineage of fungi, whereas M. humile is associated with different lineages. Therefore, this study suggests that M. kirishimense may have evolved into a new species by relying on a specific type of fungus. In fact, the phylogenetic tree (a 'family tree' of the evolutionary history of a group of organisms) of the plants themselves shows that the genetic characteristics of M. kirishimense and M. humile can be separated into two clades. Based on the researchers' analysis of various characteristics, it has been revealed that M. kirishimense is distinct from M. humile in terms of its appearance, flowering patterns, evolutionary history, and ecological relationships. Therefore, the researchers concluded that it should be recognized as an independent species.

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Spontaneous baby movements have purpose

Spontaneous, random baby movements aid development of their sensorimotor system, according to new research led by the University of Tokyo. Detailed motion capture of newborns and infants was combined with a musculoskeletal computer model, to enable researchers to analyze communication among muscles and sensation across the whole body. Researchers found patterns of muscle interaction developing based on the babies' random exploratory behavior, that would later enable them to perform sequential movements as infants. Better understanding how our sensorimotor system develops could help us gain insight into the origin of human movement as well as earlier diagnosis of developmental disorders.

If you've spent time with a baby, you'll probably have noticed that they hardly keep still. Right from birth -- and even in the womb -- babies start to kick, wiggle and move seemingly without aim or external stimulation. These are called "spontaneous movements" and researchers believe that they have an important role to play in the development of the sensorimotor system, i.e., our ability to control our muscles, movement and coordination. If we can better understand these seemingly random movements and how they are involved in early human development, we might also be able to identify early indicators for certain developmental disorders, such as cerebral palsy.

Currently, there is limited knowledge about how newborns and infants learn to move their body. "Previous research into sensorimotor development has focused on kinematic properties, muscle activities which cause movement in a joint or a part of the body," said Project Assistant Professor Hoshinori Kanazawa from the Graduate School of Information Science and Technology. "However, our study focused on muscle activity and sensory input signals for the whole body. By combining a musculoskeletal model and neuroscientific method, we found that spontaneous movements, which seem to have no explicit task or purpose, contribute to coordinated sensorimotor development."

First, the team recorded the joint movements of 12 healthy newborns (less than 10 days old) and 10 young infants (about 3 months old) using motion capture technology. Next, they estimated the babies' muscle activity and sensory input signals with the aid of a whole-body, infant-scale musculoskeletal computer model which they had created. Finally, they used computer algorithms to analyze the spatiotemporal (both space and time) features of the interaction between the input signals and muscle activity.

"We were surprised that during spontaneous movement, infants' movements "wandered" and they pursued various sensorimotor interactions. We named this phenomenon 'sensorimotor wandering,'" said Kanazawa. "It has been commonly assumed that sensorimotor system development generally depends on the occurrence of repeated sensorimotor interactions, meaning the more you do the same action the more likely you are to learn and remember it. However, our results implied that infants develop their own sensorimotor system based on explorational behavior or curiosity, so they are not just repeating the same action but a variety of actions. In addition to this, our findings provide a conceptual linkage between early spontaneous movements and spontaneous neuronal activity."

Previous studies on humans and animals have shown that motor behavior (movement) involves a small set of primitive muscular control patterns. These are patterns that can typically be seen in task-specific or cyclic movements, like walking or reaching. The results of this latest study supports the theory that newborns and infants can acquire sensorimotor modules, i.e., synchronized muscle activities and sensory inputs, through spontaneous whole-body movements without an explicit purpose or task. Even through sensorimotor wandering, the babies showed an increase in coordinated whole-body movements and in anticipatory movements. The movements performed by the infant group showed more common patterns and sequential movements, compared to the random movements of the newborn group.

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Bering Land Bridge formed surprisingly late during last ice age

A new study that reconstructs the history of sea level at the Bering Strait shows that the Bering Land Bridge connecting Asia to North America did not emerge until around 35,700 years ago, less than 10,000 years before the height of the last ice age (known as the Last Glacial Maximum).

The new findings, published the week of December 26 in Proceedings of the National Academy of Sciences, indicate that the growth of the ice sheets -- and the resulting drop in sea level -- occurred surprisingly quickly and much later in the glacial cycle than previous studies had suggested.

"It means that more than 50 percent of the global ice volume at the Last Glacial Maximum grew after 46,000 years ago," said Tamara Pico, assistant professor of Earth and planetary sciences at UC Santa Cruz and a corresponding author of the paper. "This is important for understanding the feedbacks between climate and ice sheets, because it implies that there was a substantial delay in the development of ice sheets after global temperatures dropped."

Global sea levels drop during ice ages as more and more of Earth's water gets locked up in massive ice sheets, but the timing of these processes has been hard to pin down. During the Last Glacial Maximum, which lasted from about 26,500 to 19,000 years ago, ice sheets covered large areas of North America. Dramatically lower sea levels uncovered a vast land area known as Beringia that extended from Siberia to Alaska and supported herds of horses, mammoths, and other Pleistocene fauna. As the ice sheets melted, the Bering Strait became flooded again around 13,000 to 11,000 years ago.

The new findings are interesting in relation to human migration because they shorten the time between the opening of the land bridge and the arrival of humans in the Americas. The timing of human migration into North America remains unresolved, but some studies suggest people may have lived in Beringia throughout the height of the ice age.

"People may have started going across as soon as the land bridge formed," Pico said.

The new study used an analysis of nitrogen isotopes in seafloor sediments to determine when the Bering Strait was flooded during the past 46,000 years, allowing Pacific Ocean water to flow into the Arctic Ocean. First author Jesse Farmer at Princeton University led the isotope analysis, measuring nitrogen isotope ratios in the remains of marine plankton preserved in sediment cores collected from the seafloor at three locations in the western Arctic Ocean. Because of differences in the nitrogen composition of Pacific and Arctic waters, Farmer was able to identify a nitrogen isotope signature indicating when Pacific water flowed into the Arctic.

Pico, whose expertise is in sea level modeling, then compared Farmer's results with sea level models based on different scenarios for the growth of the ice sheets.

"The exciting thing to me is that this provides a completely independent constraint on global sea level during this time period," Pico said. "Some of the ice sheet histories that have been proposed differ by quite a lot, and we were able to look at what the predicted sea level would be at the Bering Strait and see which ones are consistent with the nitrogen data."

The results support recent studies indicating that global sea levels were much higher prior to the Last Glacial Maximum than previous estimates had suggested, she said. Average global sea level during the Last Glacial Maximum was about 130 meters (425 feet) lower than today. The actual sea level at a particular site such as the Bering Strait, however, depends on factors such as the deformation of the Earth's crust by the weight of the ice sheets.

"It's like punching down on bread dough -- the crust sinks under the ice and rises up around the edges," Pico said. "Also, the ice sheets are so massive they have gravitational effects on the water. I model those processes to see how sea level would vary around the world and, in this case, to look at the Bering Strait."

The findings imply a complicated relationship between climate and global ice volume and suggest new avenues for investigating the mechanisms underlying glacial cycles.

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Drying process could be key step in the development of life

One-hundred fifty years ago, Charles Darwin speculated that life likely originated in a warm little pond. There, Darwin supposed, chemical reactions and the odd lightning strike might have led to chains of amino acids that, over time, became more and more complex until the beginnings of life emerged.

Ever since, researchers have investigated this type of pre-life or "prebiotic" chemistry, trying to figure out the chemical pathways that could have led from a pool filled with simple amino acids to bacteria, redwood trees and people. After a series of experiments, University of Wisconsin-Madison chemical engineering PhD student Hayley Boigenzahn and John Yin, a professor of chemical and biological engineering and a founding faculty member of the Wisconsin Institute for Discovery, can explain how one of the potentially crucial early steps on the path of life could have happened. They published their findings in the Dec. 2022 issue of the journal Origins of Life and Evolution of Biospheres.

In a famous 1952 study called the Miller-Urey experiment, researchers simulated the conditions thought to be present on the prebiotic Earth, including certain ratios of water, methane, hydrogen and other elements. When zapped with electricity to simulate lightning, the researchers found that the reaction produced amino acids, suggesting that these molecules were widely present on the prebiotic Earth.

"We know amino acids are the building blocks of proteins and proteins are essential for life," says Yin. "In prebiotic chemistry, it's long been a question of how we could we get these things to form bonds and strings in a manner that might eventually lead to a living cell. The question is hard because the particular chemistry involved is one that tends to fail in the presence of water."

In her experiment, Boigenzahn investigated whether it's possible these amino acids could have come together during periods of environmental change -- for instance, as a pool of water evaporated. In the presence of a chemical activator, these amino acids could bond together into peptides, or short chains of amino acids.

To study how amino acids might form bonds during the drying process, Boigenzahn created solutions of the amino acid glycine and trimetaphosphate, an activator that is naturally created during volcanic processes. Using a heater to evaporate the solution, Boigenzahn watched what happened to the amino acids over 24 hours.

What she found was a two-stage process. In the first stage, when the pH of the solution was alkaline, the glycine combined into two-molecule units called dimers, which are also produced protons, making the pH of the solution neutral. In the second stage, as evaporation took place, the dimers began to bond together to form longer peptide chains, called oligoglycine.

It's easy to imagine a scenario in which amino acids in a volcanically warmed hot spring containing an activator first combine into dimers. Then, as the water evaporates and its chemistry changes, the dimers bond and begin to form into longer chains of amino acids.

"What we're showing here is that that it doesn't necessarily have to be the same environment throughout all the reactions," says Boigenzahn. "They can occur in different environments, provided that the reactions that are occurring help create an environment that's beneficial for the next steps."

Through multiple wet-dry cycles, it's possible the peptide chains grew longer and longer. Eventually, they could have begun to fold in on themselves, forming enzymes, or proteins that catalyze chemical reactions. That could set the stage for more complex proteins and the beginnings of metabolism.

Boigenzahn and Yin both say it will be a long time before researchers figure out a possible path from Darwin's warm little pond to the beginnings of life. But, especially for chemical engineers, the effort of studying prebiotic chemistry could have big payoffs.

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Plants between light and darkness

For research, plants are frequently grown under stable lighting, which does not reflect natural conditions. In a series of experiments with changing light conditions, simulating the natural interplay of light and shadow, researchers from the Max Planck Institute of Molecular Plant Physiology in Potsdam-Golm (Germany) and the College of Natural Science at Michigan State University (USA) reveal the importance of two key proteins for the dynamic control of photosynthesis.

Plants perform photosynthesis to grow. In this process they use energy from sunlight, release oxygen, and produce carbohydrates, which are the basic food resource for all humans and almost all animals on earth. Under natural conditions, light availability can change rapidly in a very short time. One of the main reasons are clouds which provide light and shadow as they pass in front of the sun. Plant leaves and branches can also temporarily provide shade when they are moved by the wind. Plants cannot move from shade to sun when light is limited, and conversely, cannot evade from sun to shade when exposed to too much sunlight. They have to respond to changing light conditions in other ways.

Just like for humans, too much sunlight is harmful to plants. In particular, a rapid change between faint and intense light is problematic. Like the retina in our eyes, plants use molecules in their leaves to capture light particles. When light is low, these light traps are very efficient at catching as much of the low light as possible. If light conditions suddenly change, too much light energy might reach the plant. This energy can overload or damage the sensitive photosynthetic apparatus inside the plant cells. Accordingly, plants have to constantly adapt their photosynthetic activity to their environmental conditions in order to obtain maximum light yield on the one hand, but avoid being harmed by too much light on the other hand.

To date, plants in greenhouses and laboratories are grown almost exclusively under stable and uniform light conditions. Therefore, our understanding of how adaptation to changing light conditions works is very limited. In the worst case, this can lead to plants that are growing well in laboratories and greenhouses but suddenly perform much worse than expected when cultured in the field.

Regulation of photosynthesis under changing light conditions

The researchers around Ute Armbruster from the Max Planck Institute of Molecular Plant Physiology in Potsdam-Golm and David Kramer from the College of Natural Science at Michigan State University (USA) examined the model plant Arabidopsis thaliana for their study. Plants were grown under a wide variety of conditions including static, fluctuating and natural light. The study focused on two ion transport proteins called VCCN1 and KEA3 which play a key role in dynamically adjusting photosynthetic performance. It is known from earlier studies that VCCN1 activates sun protection if the light suddenly becomes too strong. When the light intensity decreases, the second protein KEA3 quickly breaks down this sun protection so that the plant can catch more light again. However, the two proteins VCCN1 and KEA3 have never been examined under realistic light conditions.

The researchers used an innovative new approach to measure photosynthesis in combination with a targeted use of gene knockouts -- i.e. plants whose genes for VCCN1 and KEA3 have been switched off. They show that the activities of the proteins VCCN1 and KEA3 depend on the light conditions the plants were raised in. Following suggestions by the head of the Plant Cultivation Infrastructure Group, Dr. Karin Köhl, the researchers focused on two growth-related light factors in the analysis and were able to show that both the amount of light a plant receives, and the frequency of light fluctuations have a strong influence on the function of the two ion transporters. The protective function of VCCN1 is only important in plants previously grown under low light. On the other hand, KEA3 which abolishes protection, was even active in high light periods when the plants were grown under conditions with elevated light intensities.

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Glassfrogs achieve transparency by packing red blood cells into mirror-coated liver

New research shows that glassfrogs -- known for their highly transparent undersides and muscles -- perform their "disappearing acts" by stowing away nearly all of their red blood cells into their uniquely reflective livers. The study, led by scientists at the American Museum of Natural History and Duke University, is being published Friday in the journal Science. The work could lead to new avenues of research tied to blood clots, which the frogs somehow avoid while packing and unpacking about 90 percent of their red blood cells into their livers on a daily basis.

"There are more than 150 species of known glassfrogs in the world, and yet we're really just starting to learn about some of the really incredible ways they interact with their environment," said co-lead author Jesse Delia, a Gerstner postdoctoral fellow in the Museum's Department of Herpetology.

Glassfrogs, which live in the American tropics, are nocturnal amphibians that spend their days sleeping upside down on translucent leaves that match the color of their backs -- a common camouflage tactic. Their tummies, however, show something surprising: translucent skin and muscle that allows their bones and organs to be visible, giving the glassfrog its common name. Recent research has proposed that this adaptation masks the frogs' outlines on their leafy perches, making them harder for predators to spot.

Transparency is a common form of camouflage among animals that live in water, but it's rare on land. In vertebrates, attaining transparency is difficult because their circulatory system is full of red blood cells that interact with light. Studies have shown that ice fish and larval eels achieve transparency by not producing hemoglobin and red blood cells. But glassfrogs use an alternative strategy, according to the findings of the new study.

"Glassfrogs overcome this challenge by essentially hiding red blood cells from view," said Carlos Taboada, the study's co-lead author from Duke University. "They almost pause their respiratory system during the day, even at high temperatures."

At Duke, the researchers used a technique called photoacoustic imaging, which uses light to induce sound-wave propagation from red blood cells. This allows researchers to map the location of the cells within sleeping frogs without restraint, contrast agents, sacrifice, or surgical manipulation -- particularly important to this study because glassfrog transparency is disrupted by activity, stress, anesthesia, and death.

The researchers focused on one particular species of glassfrog, Hyalinobatrachium fleischmanni. They found that resting glassfrogs increase transparency two- to threefold by removing nearly 90 percent of their red blood cells from circulation and packing them within their liver, which contains reflective guanine crystals. Whenever the frogs need to become active again, they bring the red blood cells back into the blood, which gives the frogs the ability to move around -- at which point, light absorption from these cells breaks transparency.

In most vertebrates, aggregating red blood cells can lead to potentially dangerous blood clots in veins and arteries. But glassfrogs don't experience clotting, which raises a set of significant questions for biological and medical researchers.

"This is the first of a series of studies documenting the physiology of vertebrate transparency, and it will hopefully stimulate biomedical work to translate these frogs' extreme physiology into novel targets for human health and medicine," Delia said.

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Archaeologists uncover oldest known projectile points in the Americas

Oregon State University archaeologists have uncovered projectile points in Idaho that are thousands of years older than any previously found in the Americas, helping to fill in the history of how early humans crafted and used stone weapons.

The 13 full and fragmentary projectile points, razor sharp and ranging from about half an inch to 2 inches long, are from roughly 15,700 years ago, according to carbon-14 dating. That's about 3,000 years older than the Clovis fluted points found throughout North America, and 2,300 years older than the points previously found at the same Cooper's Ferry site along the Salmon River in present-day Idaho.

The findings were published today in the journal Science Advances.

"From a scientific point of view, these discoveries add very important details about what the archaeological record of the earliest peoples of the Americas looks like," said Loren Davis, an anthropology professor at OSU and head of the group that found the points. "It's one thing to say, 'We think that people were here in the Americas 16,000 years ago;' it's another thing to measure it by finding well-made artifacts they left behind."

Previously, Davis and other researchers working the Cooper's Ferry site had found simple flakes and pieces of bone that indicated human presence about 16,000 years ago. But the discovery of projectile points reveals new insights into the way the first Americans expressed complex thoughts through technology at that time, Davis said.

The Salmon River site where the points were found is on traditional Nez Perce land, known to the tribe as the ancient village of Nipéhe. The land is currently held in public ownership by the federal Bureau of Land Management.

The points are revelatory not just in their age, but in their similarity to projectile points found in Hokkaido, Japan, dating to 16,000-20,000 years ago, Davis said. Their presence in Idaho adds more detail to the hypothesis that there are early genetic and cultural connections between the ice age peoples of Northeast Asia and North America.

"The earliest peoples of North America possessed cultural knowledge that they used to survive and thrive over time. Some of this knowledge can be seen in the way people made stone tools, such as the projectile points found at the Cooper's Ferry site," Davis said. "By comparing these points with other sites of the same age and older, we can infer the spatial extents of social networks where this technological knowledge was shared between peoples."

These slender projectile points are characterized by two distinct ends, one sharpened and one stemmed, as well as a symmetrical beveled shape if looked at head-on. They were likely attached to darts, rather than arrows or spears, and despite the small size, they were deadly weapons, Davis said.

"There's an assumption that early projectile points had to be big to kill large game; however, smaller projectile points mounted on darts will penetrate deeply and cause tremendous internal damage," he said. "You can hunt any animal we know about with weapons like these."

These discoveries add to the emerging picture of early human life in the Pacific Northwest, Davis said. "Finding a site where people made pits and stored complete and broken projectile points nearly 16,000 years ago gives us valuable details about the lives of our region's earliest inhabitants."

The newly discovered pits are part of the larger Cooper's Ferry record, where Davis and colleagues have previously reported a 14,200-year-old fire pit and a food-processing area containing the remains of an extinct horse. All told, they found and mapped more than 65,000 items, recording their locations to the millimeter for precise documentation.

The projectile points were uncovered over multiple summers between 2012 and 2017, with work supported by a funding partnership held between OSU and the BLM. All excavation work has been completed and the site is now covered. The BLM installed interpretive panels and a kiosk at the site to describe the work.

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