Earth

Anti-transpirant products unnecessary in cycad propagation

image: Benjamin Deloso holds a Zamia stem cutting that has successfully produced a healthy root system. In his recently published research, he found the use of anti-transpirants to neither help nor hinder successful propagation of cycads.

Image: 
University of Guam

In a first-of-its-kind study within cycad horticulture literature, University of Guam researchers have found that the use of anti-transpirants neither help nor hinder successful propagation of cycad stem cuttings.

The Guam-based study, published Oct. 22 in the journal Tropical Conservation Science, investigated whether retaining leaves during the propagation of cycad stem cuttings conferred any benefit to propagation success. Additionally, two anti-transpirant products were utilized to investigate their efficacy during the propagation process.

Leaves perform a variety of critical functions for plants, including the transport of water and nutrients from the roots via transpiration, the synthesis of useful sugars via photosynthesis, and the reduction of water loss via the closing of stomata, or little openings on the undersides of the leaves. Horticulturists sometimes manipulate these openings to the plant's benefit.

Anti-transpirants are products used in the commercial fruit industry to reduce water demands during periods of drought and have been shown to be useful during grafting trials of some plants. Some of these products work by coating the stomata, preventing the escape of gases and thereby water loss. Others purportedly induce chemical reactions within the plant to help reduce water loss. One of each type of anti-transpirant was used for the studies.

The study tested the use of anti-transpirants on two species of Zamia cycads.

"To our knowledge no anti-transpirant product has ever been used on any cycad species prior to these studies," said Benjamin Deloso, a cycad specialist who led the study as part of his master's thesis at UOG.

Numerous traits were measured throughout the duration of the study, including the speed of adventitious root formation, the behavior of the retained leaves, the date of first leaf emergence, and plant survival.

The results revealed that leaf retention on stem cuttings yielded no beneficial or detrimental influence on propagation success or the speed of adventitious root formation and that when cycad plants are healthy, regeneration of roots and leaves is possible from stem cuttings when under the care of an experienced cycad horticulturist.

"You can think of a healthy cycad stem as a bank account. Even if you experience some losses -- loss of roots or leaves -- you still have reserves in the account that can be used to recover," Deloso said.

The University of Guam continues to publish original research and expand knowledge on cycads, the world's most threatened plant group.

Although this latest research did not include Guam's native cycad, Cycas micronesica, known locally as fadang, the research is of interest to its conservation.

"As a native CHamoru, I am concerned about the state of Guam's environment," said C.J. Paulino, an environmental science graduate student at UOG and a co-author of the study. "Given the decline of the island's native fadang, I was happy to contribute to research that would benefit its conservation."

Credit: 
University of Guam

2020-2025 Dietary Guidelines for Americans recommend grains at all life stages

image: 2020-2025 Dietary Guidelines for Americans recommend maintaining existing serving size for whole and enriched grains.

Image: 
The Grain Chain

The Grain Chain, a farm to fork coalition of stakeholders in the grain industry sector and chaired by the American Bakers Association (ABA), celebrates the recommendation published today in the 2020-2025 Dietary Guidelines for Americans (DGAs) to "consume half of your grains from whole grain sources" and the remainder from enriched grains. A foundational piece of the DGAs, the guidelines recognize whole grains are "one of the three food groups that are fundamental constituents of a healthy dietary pattern."

The United States Department of Agriculture (USDA) and Health and Human Services (HHS) oversee and publish the Dietary Guidelines, the cornerstone of all Federal nutrition policy and nutrition education guidelines. The guidelines shape consumer health decisions and doctor recommendations.

Of importance, the DGAs maintained the existing recommendation for the average healthy American adult to consume six one-ounce servings of grain foods daily, with half of those servings coming from whole grains.

For the first time, the DGAs included recommendations for birth to two years. The Grain Chain applauds the recognition of grains as one of the traditional, nutritious first foods for infants. Numerous research studies have demonstrated significant, positive effects of nutrient absorption, improved nutrition quality, and overall wellness from enriched grains at various life stages.

The key takeaways from the 2020-2025 Dietary Guidelines for Americans for the grains-based foods industry:

Grains, both enriched and whole, play a key role in healthy dietary patterns and diet quality

Grains are a significant contributor of dietary fiber, a generally under-consumed nutrient for Americans

Grains contribute to overall diet quality through key essential nutrients

Grains are a delicious, versatile, affordable, and sustainable plant-based food

Enrichment and fortification of grains are key contributors to positive public health impacts

Since folic acid fortification of enriched grain foods became required in 1998, the prevalence of babies born with neural tube defects (NTDs) has decreased by 35% in the U.S., leading the Centers for Disease Control & Prevention (CDC) to name folic acid fortification of enriched grains one of the top 10 public health achievements of the first decade of the 21st century

The DGAs included guidance on enriched grains, maintaining the existing recommendation of three one-ounce servings of enriched grains daily. While the guidelines cite science-backed evidence of positive health outcomes from the inclusion of enriched grains, the Grain Chain is extremely concerned to see the DGAs include contradictory language linking "refined grains" with poor dietary patterns and health outcomes.

Published scientific research clearly and unequivocally illustrates the key roles of grains - both enriched and whole - in healthy dietary patterns and their significant contributions to diet quality. To clarify and correct potential consumer confusion resulting from this contradictory language, the members of the Grain Chain look forward to partnering with the USDA and HHS to help educate the public on the value of both enriched and whole grains.

For more information about grains, go to GoGrains.org.

Others in the Grain Chain weighed in on the recommendations published in the 2020-2025 Dietary Guidelines:

"The American Bakers Association is very appreciative of the thorough work of the DGAC as well as USDA staff in the culmination of their efforts, published today," said Lee Sanders, Senior Vice President of Government Relations and Public Affairs, ABA. "ABA has been pleased to lead and work with the Grain Chain throughout the 2020-2025 process, and we strongly agree on the goodness of six grain servings, half enriched grains and half whole grains, on Americans' daily plates."

"The Guidelines are an essential map for consumers, policy-makers, and feeding program implementers to use as they feed themselves, their families, and the most vulnerable in our country," said Christine Cochran, Executive Director, Grain Foods Foundation. "The unity of the Grain Chain's message and the importance of its being heard have been affirmed in this DGA cycle today: the nutritional contribution of grains is essential in the diet at all stages of life."

As a member of the Grain Chain coalition the USA Rice Federation supports and appreciates the ongoing efforts to provide input and guidance on the development of the 2020-2025 Dietary Guidelines for Americans. "Research has repeatedly demonstrated the benefits of enriched and whole grain consumption and its correlation to a healthy eating pattern," said USA Rice President & CEO Betsy Ward. "USA Rice stands with its Grain Chain partners in support of the comments submitted and the overall recommendation that the nutritional benefit of grain consumption is vital at all stages of life."

"Enriched and whole wheat and grain-based foods provide important nutritional benefits, are affordable and foundational foods in many cultures. Regular consumption of wheat and other grains delivers key nutrients including B vitamins, folate, iron and fiber," said Tim O'Connor, President, of the Wheat Foods Council.

NAMA President Jane DeMarchi stated, "We are delighted that the nutritional value of both whole and enriched grains in the diet, which is supported by vast scientific research, is acknowledged by the updated Dietary Guidelines. Grain foods are staples that create the foundation for a healthy and balanced diet. They are affordable, versatile, convenient, and easy to store. The significance of these qualities cannot be overstated in normal times, much less during a global pandemic where families are stressed, and food dollars are stretched."

Pasta is an essential staple on the American table and plays an important role in supporting healthy dietary patterns, especially in the Mediterranean Diet, which has been shown to have a number of positive benefits," said Delia Murphy, Executive Director of the National Pasta Association. "Through our participation in the Grain Chain, NPA is proud to reinforce and acknowledge the importance of both enriched and whole grains in the Dietary Guidelines and their contribution to diet quality and key positive nutrients."

Credit: 
The Cyphers Agency

Music-induced emotions can be predicted from brain scans

Researchers at the University of Turku have discovered what type of neural mechanisms are the basis for emotional responses to music. Altogether 102 research subjects listened to music that evokes emotions while their brain function was scanned with functional magnetic resonance imaging (fMRI). The study was carried out in the national PET Centre.

The researchers used a machine learning algorithm to map which brain regions are activated when the different music-induced emotions are separated from each other.

- Based on the activation of the auditory and motor cortex, we were able to accurately predict whether the research subject was listening to happy or sad music. The auditory cortex processes the acoustic elements of music, such as rhythm and melody. Activation of the motor cortex, then again, may be related to the fact that music inspires feelings of movement in the listeners even when they are listening to music while holding still in an MRI machine, says Postdoctoral Researcher Vesa Putkinen.

The researchers also discovered which brain regions are activated when the research participants watched videos that evoke strong emotions, and tested whether the same regions were activated when the participants were listening to music that evokes emotions.

The results suggest that the emotions evoked by films and music are partially based on the operation of different mechanisms in the brain.

- Films, for instance, activate the deeper parts of the brain that regulate emotions in real-life situations. Listening to music did not strongly activate these regions nor did their activation separate the music-induced emotions from each other. This may be due to the fact that films can more realistically copy the real-life events that evoke emotions and thus activate the innate emotion mechanisms. As for the music-induced emotions, they are based on the acoustic characteristics of music and coloured by cultural influences and personal history.

Traditionally, music-induced emotions have been studied through classical instrumental music.

- We wanted to use only instrumental music in this study as well, so that lyrics did not impact the emotions of the research subjects. However, we included film music and songs by the guitar virtuoso Yngwie J. Malmsteen, notes Putkinen.

Credit: 
University of Turku

The liverwort oil body is formed by redirection of the secretory pathway

video: Hungry pill bugs were placed in a petri dish containing liverworts with no or over-generated oil bodies, and compared their herbivory. The liverworts without the oil body were eaten by pill bugs, but the liverworts with an increased number of oil bodies were not, indicating that the oil bodies have a function for protection against herbivores including arthropods.

Image: 
Takehiko Kanazawa, NIBB

Cells, the basic unit of life, are surrounded by a limiting membrane called the plasma membrane. Inside cells, there are various membrane-bounded organelles, each of which has various and distinctive functions. How these organelles, which individually boast different functions, have been developed during evolution remains unknown. This phenomenon has fascinated many researchers.

In the study published in Nature Communications, the evolutionary relationship between two different organelles in liverwort cells has been revealed: the cell plate, which divides cells during cell division, and the oil body, which is a reservoir for various chemical substances.

The mechanism for exchanging proteins and lipids between organelles is very important for cellular activities and is called "membrane traffic". A research team led by Professor Takashi Ueda and Assistant Professor Takehiko Kanazawa of the National Institute for Basic Biology (NIBB) focused their research on a group of proteins called SYP1, which play pivotal roles in membrane traffic, using the liverwort, Marchantia polymorpha.

They found that MpSYP12A, a protein belonging to the SYP1 group of the liverwort, is required for formation of the cell plate. They also found that MpSYP12B, a protein very similar to MpSYP12A, works only in cells containing oil bodies and targets the membrane of the oil body.

By examining how MpSYP12B localizes to the oil body membrane, the team showed that the direction of the secretory pathway, which is generally sent along the plasma membrane and extracellular space, is redirected to the oil body during oil body formation.

Professor Takashi Ueda, the leader of the research group said, "It remains almost unknown how these organelles arose during evolution, although a theoretical framework that states organelle acquisition through expansion and neofunctionalization of machinery components of membrane traffic has been proposed. Our results provide strong empirical support to this hypothesis, namely, the organelle paralogy hypothesis".

Furthermore, the research group also discovered the master regulator for oil body formation, MpERF13. Loss of function of MpERF13 resulted in the complete loss of the oil body, whereas the enhanced MpERF13 function caused over-generation of the oil body throughout the plant.

The research group also investigated the biological significance of the oil body, which was previously not well understood. Dr. Takehiko Kanazawa conducted an experiment, in which hungry pill bugs were placed in a petri dish containing liverworts with no or over-generated oil bodies, and compared their herbivory.

Upon looking back on his undergraduate days, Dr. Takehiko Kanazawa, the first author of the article, stated "I had eaten some liverwort when I started my research on this plant. It tasted really horrible. This extreme experience helped me come up with the idea of the pill bug assay in exploring the biological function of the oil body."

The liverworts without the oil body were eaten by pill bugs, but the liverworts with an increased number of oil bodies were not, indicating that the oil bodies have a function for protection against herbivores such as arthropods.

The oil body accumulates various compounds of divergent bioactivities, some of which have been reported to exhibit antibacterial, anticancer, and/or antiviral activities. The mechanism of and the group of genes involved in oil body formation revealed in this study can be applicable to efficient production of such useful compounds.

Credit: 
National Institutes of Natural Sciences

New research makes strong case for restoring Hong Kong's lost oyster reefs

image: Oyster reefs in Hong Kong

Image: 
©Kyle Obermann/Courtesy TNC

New research produced jointly by The Swire Institute of Marine Science (SWIMS), Faculty of Science, The University of Hong Kong (HKU), and The Nature Conservancy (TNC), published recently in the scientific journal Restoration Ecology, shows the enormous potential of restoring lost oyster reefs, bringing significant environmental benefits.

Benefits of oyster reefs

Hong Kong was once home to thriving shellfish reefs, but due to a combination of factors including over-exploitation, coastal reclamation and pollution, shellfish populations have declined drastically. Restoring oyster reefs along urbanized coastlines can mitigate some of the environmental problems typical of coastal development, such as damage from storm surge and loss of biodiversity.

"Globally, we have lost 85% of shellfish reefs, making it the most endangered marine habitat on earth," said Marine Thomas, Conservation Project Manager, for TNC in Hong Kong. "Most people associate oysters with food, but less well-known is that oysters create reef habitats that support coastal marine life. Only by restoring these lost habitats can we start to bring back some of the associated environmental benefits."

A primary benefit that healthy oyster reefs contribute to coastal environments is their role as natural water purifiers: This new study found that, just 7 m2 of Hong Kong oyster reef can filter up to one Olympic swimming pool of water each day; a single Hong Kong oyster (Crassostrea hongkongensis) can filter up to 30 liters of water per hour at summer temperatures, among the highest filtration rates recorded of any oyster species.

Even more importantly, oyster reefs provide habitat and nursery grounds for many native species that are otherwise lost from our shores. Another recent SWIMS study conducted in partnership with TNC found that these reefs house six times more species than bare muddy shores. The research found over 80 species on intertidal muddy shores in Deep Bay, 95% of which were found in oyster reefs, and almost 60% of which were exclusively found in those reefs.

Oyster reefs restoration

"A previous SWIMS study found that Hong Kong is home to approximately 6,000 marine species and 26% of all marine species in China. This new research adds to that list, as we've identified a small crab previously not seen in Hong Kong. This shows us just how under-studied these ecosystems are," said Dr Bayden D Russell, an Associate Director of SWIMS and Associate Professor in the Research Division for Ecology and Biodiversity, HKU.

Another benefit of restored reefs is increased production of commercially and recreationally valuable fish and crabs.

Further, demonstration of successful restoration in one of Asia's coastal mega-cities can also act as model, providing evidence for the environmental and societal benefits of ecological restoration within the region.

In some parts of the world, oyster reef restoration has only been successful by transplanting juvenile oysters cultivated in hatcheries into the wild. However, this new research demonstrates that natural recruitment of oysters in Hong Kong is high, meaning that restoration could potentially be achieved without the need for hatchery-reared oysters.

"We were excited to find high natural recruitment levels which suggests that oyster reef restoration is possible without hatchery intervention," said Dr Russell. "We think that this recruitment is because traditional oyster farming in the Pearl River Delta has maintained populations of native oysters in the system in spite of the loss of oyster reefs and these farms could potentially act as a source of larvae."

In assessing 10 sites where small remnant shellfish habitats are found in Hong Kong, the study also found that large oysters (beyond 1 year old) are very hard to find in the wild, due to on-going harvesting pressures.

"While we are excited by the biological feasibility of restoration, unfortunately the human aspect remains our biggest challenge to bring these habitats back at scale. Shellfish habitats are still severely under protected in Hong Kong, with very little public awareness of their ecological value. Wild harvesting is a huge problem - as soon as oysters or mussels are big enough to eat, someone will harvest them. We are working with Government on gaining more protection and recognition for these important ecosystems and hope to include them in the next Hong Kong Biodiversity Strategy and Action Plan (BSAP)," said Ms Thomas.

Credit: 
The University of Hong Kong

Human-made landscape promotes coexistence of two normally separated Andean warblers

image: The two species and their habitats at the study site in Ecuador (Photos by J. Nowakowski). The higher elevation species, the Spectacled Whitestart, chooses fragmented forests with few trees and with open spaces comprising patches of bushes and meadows. The lower elevation species, the Slate-throated Whitestart, chooses dark dense montane forest stands. Both species forage in a very similar way by a method called "flush-pursue": a bird uses contrasting plumage, spread tail and wings and pirouetting body movements to visually trigger escapes/flights in insects (hence to flush insects), which are subsequently pursued in air and captured. These two species co-occur in man-made fragmented montane landscape because open habitats preferred by the Spectacled Whitestart are similar to the typical high elevation habitats where this species occurs, and the dark, dense forests are the typical habitats of the Slate-throated Whitestart. Therefore the scientists did not observe any aggression between the two species during foraging: the species occurred next to each other at the same elevation but were spatially separated because they used different habitats. Those habitats are available next to each other due to human activities leading to degradation of the dense montane forest.

Image: 
photo by Jacek Nowakowski, the coauthor of the original paper at www.nature.com/articles/s41598-020-78804-2

In the mountains across the world, different types of vegetation occur at different elevations creating distinct zones with well-defined borders between them. Each vegetation zone provides specific living conditions for animals. Therefore species that are adapted to habitats created in the specific zone occur only at the specific elevations and do not overlap with other species of similar ecology and behavior adapted to other vegetation zones at different elevations. This zonation is believed to be especially true for ecologically similar species that narrowly specialize to use specific resources and therefore compete with each other if they co-occur next to each other in the same habitat.

However, human activities modify the natural zones and create new types of habitats disrupting the clear natural borders between them. This has consequences for the distribution, ecology and behavior of animals that in a natural situation would rarely co-occur. In the recent paper published in Scientific Reports a team of Polish ornithologists illustrates how those anthropogenic modifications of natural vegetation in the Andes create new conditions in which two ecologically specialized species of birds, that typically occur in different elevational zones, can now co-occur next to each other at the same elevation.

The team of Polish ornithologists, following the long-standing traditions of Polish ornithology in South America since 1800s (https://en.wikipedia.org/wiki/Jan_Sztolcman; https://en.wikipedia.org/wiki/W%C5%82adys%C5%82aw_Taczanowski; https://academic.oup.com/auk/article/120/3/577/5561874), have undertook field research on ecology of two warblers in the tropical montane forests of eastern slopes of the Ecuadorian Andes. Piotr Jablonski (Museum and Institute of Zoology PAS & Seoul National University), Jacek Nowakowski (University of Warmia and Mazury in Olsztyn), Marta Borowiec and Tadeusz Stawarczyk (University of Wroclaw) have focused on two very special warblers: the Slate-throated Whitestart, which typically occurs in the Andean montane forests [example of habitat is here and here, and its close relative, the Spectacled Whitestart, which typically occurs at higher elevation in cloud forests [example of habitat is here]. Both species forage in almost identical way: by foraging with outspread wings and tail, and by presenting spots of contrasting plumage during fast pirouetting movements these birds are able to "overstimulate" and to trigger escapes in their prey, which then is pursued and captured in the air. Therefore, this type of foraging is called "flush-pursue" foraging and it has been extensively studied by Piotr Jablonski. Examples of how "flush-pursuers" forage can be seen here and here.

During several visits to the Yanayacu Biological Station & Center for Creative Studies (Ecuador) , the researchers mapped the distribution of territories of the two species near the station in the landscape that contains patches of natural or secondary forests intermixed with pastures and open bushy areas. [aerial view is here ]. "The field work was hard but exciting for us because we are field ornithologists, who value real field work in various exotic locations" mentions Jacek Nowakowski. "We used classical "old-fashioned" typical ornithological methods of field observations based on ornithological skills and perseverance" comments Tadeusz Stawarczyk, who studied Slate-throated Whitestarts in Costa Rica in the past. "It took us three visits until we collected sufficient material" adds Marta Borowiec, who has also studied Painted Whitestarts in Arizona in the past.

The study found that both species occurred next to each other, but occupied different vegetation types. The Spectacled Whitestart was observed in a sunny man-made mosaic of pastures, clearings, and shrubs with small proportion of high trees, all of which created a landscape similar to the high elevation Andean vegetation where the species normally occurs. The Slate-throated Whitestart, was mostly observed in shady and dense forests with high proportion of tall trees. The two species differed relatively little in their foraging technique, but because they foraged in different habitats and locations they seem to co-occur without any direct competitive aggressive interactions. "In the future, we plan to evaluate the idea that the spatial separation of breeding territories between the two species at the study site may be created during territory establishment, when it is possible that the two species respond aggressively to each other's songs" says Jacek Nowakowski.

This work represents the first quantitative field study that incorporates both, the detailed foraging information and the habitat descriptions in order to evaluate the mechanisms that allows two "flush-pursue" species, that are normally separated in space along the elevation, to co-occur at the same elevation in the Andean landscape modified by man. "Our results illustrate how modern science can benefit from the "good old style" expedition-based intense field work" says Piotr Jablonski.

Credit: 
Laboratory of Behavioral Ecology and Evolution at Seoul National University

Shapeshifting crystals-varying stability in different forms of gallium selenide monolayers

image: The P and AP phases of a GaSe monolayer

Image: 
Hirokazu Nitta from Japan Advanced Institute of Science and Technology

The gallium selenide monolayer has been recently discovered to have an alternative crystal structure and has diverse potential applications in electronics. Understanding its properties is crucial to understand its functions. Now, scientists from the Japan Advanced Institute of Science and Technology and the University of Tokyo have explored its structural stability, electronic states, and transformation of crystal phases.

Solid materials comprise a symmetric arrangement of atoms that confer properties like conductivity, strength, and durability. Changes in size can change this arrangement, thereby changing the overall properties of the material. For instance, the electrical, chemical, optical and mechanical properties of certain materials can change as we move towards the "nano" scale. Science now lets us study the differences in properties across various dimensions right from monolayer (atomic) level.

Gallium selenide (GaSe) is a "layered metal-chalcogenide," which is known to have polytypes, which differ in their stacking sequence of layers, but not a polymorph, which has a different atomic arrangement inside the layer. GaSe has sparked a great deal of interest in areas of physical and chemical research, owing to its potential usage in photoconduction, far-infrared conversion, and optical applications. Conventionally, a GaSe monolayer is composed of gallium (Ga) and selenium (Se) atoms bonded covalently, with the Se atoms projecting outwards, forming a trigonal prism-like structure named "P phase." Part of the same research group had earlier reported a novel crystal phase of GaSe using transmission electron microscopy in Surface and Interface Analysis, wherein the Se atoms are arranged in a trigonal antiprismatic manner to the Ga atoms referred to as "AP phase" with a symmetry different from the conventional P phase (see Picture 1). Because of the novelty of this monolayer structure, very little is known about how it does its "shapeshifting." Moreover, how do variations in the intralayer structure of such compounds affect stability?

To answer this, Mr. Hirokazu Nitta and Prof. Yukiko Yamada-Takamura from the Japan Advanced Institute of Science and Technology (JAIST) explored the structural stability and electronic states of phases of GaSe monolayer using first-principles calculations, in their latest study in Physical Review B.

Hirokazu Nitta explains their study, stating, "We have found out through first-principles calculations that this new phase is metastable, and stability against the ground-state conventional phase reverses upon applying tensile strain, which we think is strongly related to the fact that we saw this phase formed only at the film-substrate interface." The published study is also trending as a #PRBTopDownload on the official Physical Review B handle on Twitter: https://twitter.com/PhysRevB/status/1338837972003811331

To compare the structural stability of the P and AP phases of GaSe, the researchers first calculated the total energy at different in-plane lattice constants, which represent the size of a unit cell in the crystal, given that its structure comprises a "lattice" or organized meshwork of atoms. The lowest energy that corresponds to the most stable state was computed and at this state, the P phase was found to be more stable than the AP phase.

Then, to investigate if the AP and P phases can transform into each other, they determined the "energy barriers" that the material needs to cross to change, and additionally performed molecular dynamics calculations using a supercomputer (see Picture 2). They found the energy barrier for phase transition of P-phase and AP-phase GaSe monolayers is large likely due to the need of breaking and making new bonds, which prohibits direct transition from P to AP phase. The calculations also revealed that the relative stability of P-phase and AP-phase GaSe monolayers can be reversed by applying "tensile strain," or a stretching-type force.

Highlighting the importance and future prospects of their study, Prof. Yamada-Takamura remarks, "Layered chalcogenides are interesting 2D materials after graphene, having wide variety and especially bandgap. We have just found out a new polymorph (not polytype) of a layered monochalcogenide. Its physical as well as chemical properties are yet to be discovered."

Together, the findings of this study describe the electronic structure of a less-known structure of GaSe that can provide insights into the behavior of similar epitaxially grown monolayers, revealing yet another secret about the unknown family members of GaSe and related monochalcogenides.

Credit: 
Japan Advanced Institute of Science and Technology

Astrocytes eat connections to maintain plasticity in adult brains

image: A 3-D animated image showing our synapse phagocytosis reporter in mouse hippocampus. Presynapses in green, astrocytes in white, and microglia in blue. Phagocytosed presynapses by glia were shown in red.

Image: 
KAIST

Developing brains constantly sprout new neuronal connections called synapses as they learn and remember. Important connections -- the ones that are repeatedly introduced, such as how to avoid danger -- are nurtured and reinforced, while connections deemed unnecessary are pruned away. Adult brains undergo similar pruning, but it was unclear how or why synapses in the adult brain get eliminated.

Now, a team of researchers based in Korea has found the mechanism underlying plasticity and, potentially, neurological disorders in adult brains. They published their findings on December 23 in Nature.

"Our findings have profound implications for our understanding of how neural circuits change during learning and memory, as well as in diseases," said paper author Won-Suk Chung, an assistant professor in the Department of Biological Sciences at KAIST. "Changes in synapse number have strong association with the prevalence of various neurological disorders, such as autism spectrum disorder, schizophrenia, frontotemporal dementia, and several forms of seizures."

Gray matter in the brain contains microglia and astrocytes, two complementary cells that, among other things, support neurons and synapses. Microglial are a frontline immunity defense, responsible for eating pathogens and dead cells, and astrocytes are star-shaped cells that help structure the brain and maintain homeostasis by helping to control signaling between neurons. According to Professor Chung, it is generally thought that microglial eat synapses as part of its clean-up effort in a process known as phagocytosis.

"Using novel tools, we show that, for the first time, it is astrocytes and not microglia that constantly eliminate excessive and unnecessary adult excitatory synaptic connections in response to neuronal activity," Professor Chung said. "Our paper challenges the general consensus in this field that microglia are the primary synapse phagocytes that control synapse numbers in the brain."

Professor Chung and his team developed a molecular sensor to detect synapse elimination by glial cells and quantified how often and by which type of cell synapses were eliminated. They also deployed it in a mouse model without MEGF10, the gene that allows astrocytes to eliminate synapses. Adult animals with this defective astrocytic phagocytosis had unusually increased excitatory synapse numbers in the hippocampus. Through a collaboration with Dr. Hyungju Park at KBRI, they showed that these increased excitatory synapses are functionally impaired, which cause defective learning and memory formation in MEGF10 deleted animals.

"Through this process, we show that, at least in the adult hippocampal CA1 region, astrocytes are the major player in eliminating synapses, and this astrocytic function is essential for controlling synapse number and plasticity," Chung said.

Professor Chung noted that researchers are only beginning to understand how synapse elimination affects maturation and homeostasis in the brain. In his group's preliminary data in other brain regions, it appears that each region has different rates of synaptic elimination by astrocytes. They suspect a variety of internal and external factors are influencing how astrocytes modulate each regional circuit, and plan to elucidate these variables.

"Our long-term goal is understanding how astrocyte-mediated synapse turnover affects the initiation and progression of various neurological disorders," Professor Chung said. "It is intriguing to postulate that modulating astrocytic phagocytosis to restore synaptic connectivity may be a novel strategy in treating various brain disorders."

Credit: 
The Korea Advanced Institute of Science and Technology (KAIST)

Eavesdropping on the pH levels inside the brain

image: The multiplexed pH probe with a light-addressable potentiometric sensor and a schematic diagram of the multimodal fiber. The implantable device can acquire real time multi-site acquisition to detect pH levels in vivo.

Image: 
Tohoku University

Researchers at Tohoku University have developed the first all-in-one miniature pH probe for real-time investigations of intrinsic extracellular pH dynamics in the deep brain structures.

In our brain, over billions of dedicated workers --neurons and glial cells --form complex and efficient networks that constantly communicate with each other via subtle chemical signals to govern our behavioral output.

The brain chemistry is the fundamental language among brain cells. In our healthy brains, the chemistry stays relatively neutral and must constantly regulate the acid-alkaline fluctuations; otherwise it can lead to chronic brain disorders such as mental illness, glioma and seizures. Correlating in brain pH fluctuations with brain signaling and functions, therefore, provides a clearer understanding of the influence of pH on how our brain operates and how it malfunctions in a diseased state.

However, despite recent technical progression in electrical recordings of the brain and chemical monitoring technologies, limitations remain in measuring the chemical signaling, especially the pH of living organisms, i.e. in vivo.

The research team addressed these limitations by pioneering a hybrid device that fused two different technologies: a strand of thin fibers with seamless integration of electrical and optical functions and chemical sensors with measurement locations defined by light. The combination allows for in vivo spatially resolved detection of intrinsic chemical signaling inside the brain, especially the deeper regions, with high spatial, temporal and chemical resolution.

"We leveraged the thermal drawing process that is conventionally used in the telecommunication industry to fabricate fibers that integrate multiple functions, such as an optical waveguide, electrodes and chemical channels,' said Yuanyuan Guo, an assistant professor at the Frontier Research Institute of Interdisciplinary Sciences, Tohoku University.

Collaboration with professor Tatsuo Yoshinobu from the Graduate School of Biomedical Engineering led to the coupling of an active component --a chemical sensor with light addressability --to the fiber to realize an all-in-one hybrid chemical sensing probe for in vivo detections of subtle chemical changes in the brain. The first prototype focused on pH detections.

The probe was also tested for in vivo measurements thanks to professor Hajime Mushiake from the Graduate School of Medicine. It was able to detect slight pH fluctuations in response to seizures in rats.

"The next step for our team is to improve the spatial, temporal and chemical resolution to the level pertinent to the scales of the intrinsic neuronal dynamics," added Guo. "Our technological breakthrough will advance our basic understanding of brain chemistry and its correlation with brain functions."

Credit: 
Tohoku University

Evidence for a massive paleo-tsunami at ancient Tel Dor, Israel

image: Geoprobe drilling rig extraction of a sediment core with evidence of a tsunami from South Bay, Tel Dor, Israel

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Photo by T. E. Levy

Underwater excavation, borehole drilling, and modelling suggests a massive paleo-tsunami struck near the ancient settlement of Tel Dor between 9,910 to 9,290 years ago, according to a study published December 23, 2020 in the open-access journal PLOS ONE by Gilad Shtienberg, Richard Norris and Thomas Levy from the Scripps Center for Marine Archaeology, University of California, San Diego, USA, and colleagues from Utah State University and the University of Haifa.

Tsunamis are a relatively common event along the eastern Mediterranean coastline, with historical records and geographic data showing one tsunami occurring per century for the last six thousand years. The record for earlier tsunami events, however, is less defined. In this study, Shtienberg and colleagues describe a large early Holocene tsunami deposit (between 9,910 to 9,290 years ago) in coastal sediments at Tel Dor in northwest Israel, a maritime city-mound occupied from the Middle Bronze II period (2000-1550 BCE) through the Crusader period.

To conduct their analysis, the authors used photogrammetric remote sensing techniques to create a digital model of the Tel Dor site, combined with underwater excavation and terrestrial borehole drilling to a depth of nine meters.

Along the coast of the study area, the authors found an abrupt marine shell and sand layer with an age of constraint 9,910 to 9,290 years ago, in the middle of a large ancient wetland layer spanning from 15,000 to 7,800 years ago. The authors estimate the wave capable of depositing seashells and sand in the middle of what was at the time fresh to brackish wetland must have travelled 1.5 to 3.5 km, with a coastal wave height of 16 to 40 m. For comparison, previously documented tsunami events in the eastern Mediterranean have travelled inland only around 300 m--suggesting the tsunami at Dor was generated by a far stronger mechanism. Local tsunamis tend to arise due to earthquakes in the Dead Sea Fault system and submarine landslides; the authors note that an earthquake contemporary to the Dor paleo-tsunami (dating to around 10,000 years ago) has already been identified using cave damage in the nearby Carmel ridge, suggesting this specific earthquake could have triggered an underwater landslide causing the massive tsunami at Dor.

This paleo-tsunami would have occurred during the Early to Middle Pre-Pottery Neolithic B cultural period of the region (10,700-9,250 years ago 11,700-10,500 cal BP), and potentially wiped out evidence of previous Natufian (12,500-12,000 years ago) and Pre-Pottery Neolithic coastal villages (previous surveys and excavations show a near absence of low-lying coastal villages in this region). The re-appearance of abundant Late Neolithic archaeological sites (ca. 6,000 BCE) along the coast in the years after the Dor tsunami coincides with the resumption of wetland deposition in the Dor core samples and indicates resettlement followed the event--highlighting residents' resilience in the face of massive disruption.

According to Gilad Shtienberg, a postdoc at the Scripps Center for Marine Archaeology at UC San Diego who is studying the sediment cores, "Our project focuses on reconstructing ancient climate and environmental change over the past 12,000 years along the Israeli coast; and we never dreamed of finding evidence of a prehistoric tsunami in Israel. Scholars know that at the beginning of the Neolithic, around 10,000 years ago, the seashore was 4 kilometers from where it is today. When we cut the cores open in San Diego and started seeing a marine shell layer embedded in the dry Neolithic landscape, we knew we hit the jackpot."

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PLOS

VR simulations shed potential light on goalkeepers' ability to stop free kicks

image: The study's VR technology being used for training purposes

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INCISIV

Virtual reality simulations of football (soccer) free kicks suggests placing a defensive wall can block a goalie's view and hamper their performance - and simulations might be useful in other sports too.

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PLOS

Capturing 40 years of climate change for an endangered Montana prairie

image: The intermountain bunchgrass prairie at the National Bison Range, Montana, USA at one of the study areas.

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Gary Belovsky

Over 40 years of monitoring, an endangered bunchgrass prairie became hotter, drier and more susceptible to fire annually--but dramatic seasonal changes (not annual climate trends) seem to be driving the biggest changes in plant production, composition, and summer senescence. Gary Belovsky and Jennifer Slade of The University of Notre Dame, Indiana, present these findings in the open-access journal PLOS ONE on December 23.

Intermountain bunchgrass prairie is one of North America's most endangered ecosystems, now covering less than 1 percent of the area it once did. Over the past century, bunchgrass prairies have become warmer and drier, and human-driven climate change is expected to continue that trend, with potential impacts on bunchgrass ecosystems. However, bunchgrass is often overlooked in studies of grasslands.

To better understand the effects of climate change on bunchgrass prairies, Belovsky and Slade studied the National Bison Range, a bunchgrass prairie in Montana, for 40 years. They made repeated observations of plant growth and production, abundances of different plant species, and availability of nitrogen (an important nutrient for plants), generating a comprehensive timeline of ecosystem changes.

Over the course of the study, annual temperatures rose and precipitation declined in the prairie, making it more susceptible to fire. Surprisingly, the researchers found that annual aboveground primary production--the amount of plant material produced every year--rose by 110 percent, associated with increased precipitation and cooler temperatures during the important growth period of late May through June. However, this was associated with a change in plant composition, with a 108 percent increase in invasive species, more drought-tolerant species being favored overall, and declines in dicot non-grass plants (decreasing by 65 percent) over the 40-year study period.

The researchers also found that other ecosystem changes followed seasonal climate trends, instead of annual trends. For instance, summer temperatures were higher than might be expected from annual trends, boosting summer senescence-- the yearly "browning" of green plant material.

These findings highlight the importance of considering local and seasonal changes when forecasting the effects of climate change on a given ecosystem. The authors report that intermountain bunchgrass prairie could be morphing into a different type of grassland that may be previously unknown.

Dr. Belovsky adds: "Forecasting climate change effects on plant production based on expected average annual increased temperature and decreased precipitation may not be appropriate, because seasonal climate changes may be more important and may not follow average annual expectations."

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PLOS

Caspian crisis: Sinking sea levels threaten biodiversity, economy and regional stability

image: Infographic showing the effects of water level change in the Caspian Sea area.

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Naturalis

The water levels of the Caspian Sea will be 9 to 18 meters lower than they are now, German and Dutch researchers calculate. In the Nature-journal Communications Earth & Environment they urge the world to act.

Coastal nations are rightly worried about a sea level rise, but in the countries around the Caspian Sea over a hundred million people are facing the opposite problem: an enormous drop in sea level. Technically, this sea is a land-locked lake, but it is the largest on the planet (371.000 km2), and quite salty.

The largest lake in the world is getting smaller every year, though. Since the 90's, the water level has been dropping a few centimeters every year. This drop will accelerate during the upcoming decades, scientists from the German universities of Gießen and Bremen calculated, together with Dutch geologist Frank Wesselingh.

Nine to eighteen metre drop

"If the North Sea would drop two or three meters, access to ports like Rotterdam, Hamburg and London would be impeded. Fishing boats and container giants alike would struggle, and all the countries on the North Sea would have a huge problem", Wesselingh says. "Here, we are talking about a decrease of no less than nine meters - in the best case scenario." In the worst case scenario, the drop will be eighteen meters, and the Caspian Sea will lose over a third of its surface area.

In the journal Communications Earth & Environment, the three scientists are calling for action. Increased evaporation and the loss of sea ice in the winter will accelerate water level drop, they explain. This will affect the unique ecosystems in the area, with their migratory birds, beluga and the endemic Caspian seal, that raises its puppies on the sea ice in the North of the Caspian Sea. It will also have dire consequences for the millions of people living near the sea, or around the rivers that run into it.

Politically tense region

These problems also play in a region that is already politically tense. Azerbaijan, Russia, Iran, Turkmenistan and Kazakhstan all share a piece of the Caspian Sea, and would have to make new agreements on borders and fishing rights. Wesselingh and his German colleagues urge the formation of an international task force, led by the United Nations Environmental Programme, that would coordinate the mitigation of this problem.

"This aspect of climate change - falling levels of lakes -could be similarly devastating as global sea level rise", the three researchers write in their article. "Immediate and coordinated action is required to make up for valuable time lost. The shrinking Caspian Sea might serve as a poster child of the problem, and will help to galvanize such actions."

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Utrecht University

Assessment of air contamination by SARS-CoV-2 in hospital settings

What The Study Did: In this systematic review of current evidence on air contamination with SARS-CoV-2 in hospital settings, the air close to and distant from patients with COVID-19 was frequently contaminated with SARS-CoV-2 RNA; however, few of these samples contained viable viruses. High viral loads found in toilets and bathrooms, staff areas and public hallways suggest that these areas should be carefully considered.

Authors: Gabriel Birgand, Ph.D., of the Centre Hospitalo-Universitaire de Nantes in France, is the corresponding author.

To access the embargoed study: Visit our For The Media website at this link https://media.jamanetwork.com/

(doi:10.1001/jamanetworkopen.2020.33232)

Editor's Note: The article includes conflict of interest and funding/support disclosures. Please see the article for additional information, including other authors, author contributions and affiliations, conflict of interest and financial disclosures, and funding and support.

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JAMA Network

Molecular reporters expose the allies of the brain tumor

image: Previously only suspected, now made it visible thanks to the molecular reporter: where human tumor cells and brain cells of a mouse meet, the tumor cells have a different identity than everywhere else (green).

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Gargiulo Lab, MDC

Glioblastoma is the most common malignant brain tumor in adults. Roughly five in every 100,000 people develop this type of cancer each year. The diagnosis amounts to a death sentence: Even after surgical resection followed by radiation and chemotherapy, the glioblastoma will kill the patient in a few months. This is because the tumor invariably returns after treatment, and in a more aggressive form than before.

Researchers investigating glioblastoma tissue always find immune cells inside the tumor. They have therefore long suspected that these cells strengthen the tumor, instead of fighting it. A team led by Dr. Gaetano Gargiulo at the Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC) has now supplied direct evidence of this. "We developed a new technology which allows us to visualize, on a molecular level, how the innate immune cells end up defending the tumor cells rather than body" says Gargiulo.

The researchers generated/created molecular reporters that produce fluorescence in a cell if that cell is running complex programs, such as the kind that changes the cell identity. They have published their findings in the journal Cancer Discovery. The lead authors are Matthias Jürgen Schmitt, Carlos Company, and Yuliia Dramaretska - all doctoral students in Gargiulo's Molecular Oncology Lab. The group collaborated with scientists at the Netherlands Cancer Institute, the Ludwig-Maximilians-Universität München, and the Spanish National Cancer Research Center.

Glioblastoma, previously known as glioblastoma multiforme, is a highly heterogeneous tumor. Drugs that are used successfully to treat some forms of bowel or breast cancer are powerless against glioblastoma. "This is firstly because most cancer drugs can't get across the blood-brain barrier," says Gargiulo. The blood-brain barrier is a complex set of cellular and molecular channels that regulates the access of substances to the brain tissue from circulating blood. It stops substances that don't belong in the central nervous system from entering the brain via the capillaries. This is certainly one reason why only one drug could be approved so far for chemotherapy in glioblastoma patients and it eventually stops working pretty soon.

A basis for developing new medicines

Secondly, not all cancer cells are alike. The cells that give rise to glioblastoma are divided into multiple molecular subtypes. The composition changes over time. This is especially true with a recurrence - when a tumor returns after treatment. In these cases, the cells frequently transition to the most aggressive of the subtypes, which is deadlier than the others. "A better understanding of the glioblastoma subtype identities, and of what triggers their changes, could be a guide for developing new and more effective therapies," says Matthias Schmitt.

This requires researchers to have an accurate understanding of the tumor's biology - how it regulates its growth and how it interacts with nearby cells. Gargiulo and his team have now found the tool that allows them to comprehend these cellular processes. "Within the tumor cells' genome, we've identified the regulators that program each subtype signature," says Yuliia Dramaretska. "We then turned these short DNA segments into molecular reporters that fluoresce when the cells change." They also show what triggered the change - e.g., immune cells, drugs, or ionizing radiation.

A versatile technology

"The molecular reporters can now help us work out how to stop the immune cells from making the tumor cells more aggressive," says Gargiulo, explaining the future research plans. "Perhaps we can also encourage them to recruit other immune cells that will help them fight the tumor."

The technology has already been patented, and the plan is to set up a spin-off that will further develop it. "It's not only useful with glioblastoma," says Carlos Company. "It is potentially applicable to many other biological systems." One very contemporary use that Gargiulo mentions is for research into the COVID-19. The MDC scientists plan to use it to develop tests that show, at a very early stage, whether the virus is attacking the lung tissue. They could investigate drug combinations to see whether these stop the pathogen from replicating in the cells and mount an anti-viral response. The method could also provide insights into how and why drugs work against COVID-19.

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Max Delbrück Center for Molecular Medicine in the Helmholtz Association