It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Tuesday, December 22, 2020
Under Antarctica's ice, Weddell seals produce ultrasonic vocalizations
University of Oregon-led study identifies nine types of sound outside the range of human hearing
IMAGE: UNIVERSITY OF OREGON EVOLUTIONARY BIOLOGIST PAUL CZIKO LOOKS OVER THE UNDERWATER CAMERA DURING A DIVE AT THE NATIONAL SCIENCE FOUNDATION-FUNDED MCMURDO OCEANOGRAPHIC OBSERVATORY. THE OBSERVATORY, COMPLETED IN 2017, IS LOCATED... view more
CREDIT: PHOTO BY HENRY KAISER
EUGENE, Ore. -- Dec. 21, 2020 -- Weddell seals are chirping, whistling and trilling under Antarctica's ice at sound frequencies that are inaudible to humans, according to a research team led by University of Oregon biologists.
Two years of recordings at a live-streaming underwater observatory in McMurdo Sound have captured nine types of tonal ultrasonic seal vocalizations that reach to 50 kilohertz. Humans hear in the sonic range of 20 to 20,000 hertz, or 20 kilohertz.
The discovery is detailed in a paper published online Dec. 18 ahead of print the Journal of the Acoustical Society of America.
Weddell seals (Leptonychotes weddelii), the world's southernmost-ranging mammal, thrive under the continent's sea ice, using their large teeth to create air holes. They can dive to 600 meters in search of prey and remain submerged for 80 minutes. Researchers had first identified 34 seal call types at sonic frequencies in 1982, tying the sounds to social interactions.
The study's lead author Paul Cziko, a visiting research professor in the UO's Institute of Ecology and Evolution, began recording the seals' sonic-ranged vocalizations in 2017 after completing the installation of the McMurdo Oceanographic Observatory. Workers at McMurdo Station, he said, often fell asleep listening to broadcasts of the seals' sonic sounds coming from below.
"The Weddell seals' calls create an almost unbelievable, otherworldly soundscape under the ice," Cziko said. "It really sounds like you're in the middle of a space battle in 'Star Wars,' laser beams and all."
Over the next two years, the observatory's broadband digital hydrophone - more sensitive than equipment used in earlier recordings - picked up the higher-frequency vocalizations during passive monitoring of the seals.
"We kept coming across these ultrasonic call types in the data," said co-author Lisa Munger, a marine biologist who studies marine mammal acoustics and a career instructor in the UO's Clark Honors College. "Finally, it dawned on us that the seals were actually using them quite regularly."
The nine new call types were composed of single or multiple vocal elements having ultrasonic fundamental frequencies. Eleven elements, including chirps, whistles and trills, were above 20 kHz. Two exceeded 30 kHz and six were always above 21 kHz. One whistle reached 44.2 kHz and descending chirps in another call type began at about 49.8 kHz. Harmonics, or the overtones, of some vocalizations exceeded 200 kHz.
"It was really surprising that other researchers previously had, in effect, missed a part of the conversation," said Cziko, who earned a doctorate in evolutionary biology from the UO in 2014.
What the ultrasonic vocalizations mean in the Weddell seals' repertoire is unknown. The seals are among 33 species of fin-footed mammals grouped as pinnipeds. Until now, pinnipeds, which also include sea lions and walruses, were believed to vocalize only at sonic levels.
It could be, Cziko said, that the seals produce the sounds simply to "stand out over all the lower-frequency noise, like changing to a different channel for communicating."
Or, the researchers noted, the ultrasonic vocalizations may be used for echolocation, a biological sonar that dolphins, toothed whales and bats use to navigate in limited visibility to avoid obstacles and locate friends or prey.
"The possibility of seals using some kind of echolocation has really been discounted over the years," Cziko said. "We actually had a lot of somewhat heated discussions in our group about whether or how the seals use these ultrasonic sounds for echolocation-like behaviors."
It is not known how Weddell seals navigate and find prey during the months of near absolute darkness in the Antarctic winter. The study provides no evidence for echolocation.
"We'd like to know who is producing the ultrasonic calls -- males, females, juveniles, or all of the above," Munger said. "And how are the seals using these sounds when they're out in deeper water, looking for fish? We need to record in more places to be able to correlate sounds with behaviors."
CAPTION
Two Weddell seals relax atop the sea ice at McMurdo Sound, Antarctica. A University of Oregon-led research team has discovered that Weddell seals produce nine types of vocalizations at sound frequencies that are inaudible to humans.
CREDIT
Photo by Elliott Devries
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Nick Santos of the Center for Information Technology Research in the Interest of Society at the University of California, Merced, and John Terhune, professor emeritus at the University of New Brunswick in Saint John, Canada, were co-authors. Santos engineered the data-collection pipelines for the observatory.
The National Science Foundation primarily supported the research through a grant to Cziko and Arthur L. DeVries, professor emeritus at the University of Illinois at Urbana-Champaign who has conducted research since 1961 in Antarctica. DeVries discovered the biological antifreeze that allows fish to survive in seawater at temperatures at and just below freezing.
Baltimore, MD-- The CRISPR/Cas9 genome editing system can help scientists understand, and possibly improve, how corals respond to the environmental stresses of climate change. Work led by Phillip Cleves--who joined Carnegie's Department of Embryology this fall--details how the revolutionary, Nobel Prize-winning technology can be deployed to guide conservation efforts for fragile reef ecosystems.
Cleves' research team's findings were recently published in two papers in the Proceedings of the National Academy of Sciences.
Corals are marine invertebrates that build extensive calcium carbonate skeletons from which reefs are constructed. But this architecture is only possible because of a mutually beneficial relationship between the coral and various species of single-celled algae that live inside individual coral cells. These algae convert the Sun's energy into food using a process called photosynthesis and they share some of the nutrients they produce with their coral hosts--kind of like paying rent.
Coral reefs have great ecological, economic, and aesthetic value. Many communities depend on them for food and tourism. However, human activity is putting strain on coral reefs including warming oceans, pollution, and acidification and that affects this symbiotic relationship.
"In particular, increasing ocean temperatures can cause coral to lose their algae, a phenomenon called bleaching, because the coral takes on a ghostly white look in the absence of the algae's pigment," Cleves explained. "Without the nutrients provided by photosynthesis, the coral can die of starvation."
In 2018, Cleves headed up the team that demonstrated the first use of the CRISPR/Cas9 genome editing on coral. Now, his teams used CRISPR/Cas9 to identify a gene responsible for regulating coral's response to heat stress.
Working first in the anemone Aiptasia, one team--including Stanford University's Cory Krediet, Erik Lehnert, Masayuki Onishi, and John Pringle--identified a protein, called Heat Shock Factor 1 (HSF1), which activates many genes associated with the response to heat stress. Anemones are close coral relatives that have similar symbiotic relationships with photosynthetic algae, but they grow faster and are easier to study. These traits make Aiptasia a powerful model system to study coral biology in the lab.
Then another Cleves-led team--including Stanford University's Amanda Tinoco and John Pringle, Queensland University of Technology's Jacob Bradford and Dimitri Perrin, and Line Bay of the Australian Institute of Marine Science (AIMS)--used CRISPR/Cas9 to create mutations in the gene that encodes HSF1 in the coral Acropora millepora, demonstrating its importance for coping with a warming environment. Without a functioning HSF1 protein, the coral died rapidly when the surrounding water temperature increased.
"Understanding the genetic traits of heat tolerance of corals holds the key to understanding not only how corals will respond to climate change naturally but also balancing the benefits, opportunities and risks of novel management tools," said Bay, who is the AIMS principal research scientist and head of its Reef Recovery, Restoration and Adaptation team.
Added Cleves: "Our work further demonstrates how CRISPR/Cas9 can be used to elucidate aspects of coral physiology that can be used to guide conservation. This time we focused on one particular heat tolerance gene, but there are so many more mechanisms to reveal in order to truly understand coral biology and apply this knowledge to protecting these important communities."
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Funding for the Acropora research was provided by The Simons Foundation and the Australian Institute of Marine Science.
Coral collection was conducted under permit from GBRMPA and experimental work undertaken under the approval of the AIMS Institutional Biosafety Committee.
Funding for the Aiptasia study was provided by the Gordon and Betty Moore Foundation, the Simons Foundation, and the U.S. National Science Foundation.
This work used the Genome Sequencing Service Center of the Stanford Center for Genomics and Personalized Medicine supported by grant awards from the U.S. National Institutes of Health
The Carnegie Institution for Science (carnegiescience.edu) is a private, nonprofit organization headquartered in Washington, D.C., with three research divisions on both coasts of the U.S.. Since its founding in 1902, the Carnegie Institution has been a pioneering force in basic scientific research. Carnegie scientists are leaders in plant biology, developmental biology, astronomy, materials science, global ecology, and Earth and planetary science.
The far-reaching effects of mutagens on human health
IMAGE: MICHAEL LYNCH IS THE DIRECTOR OF THE BIODESIGN CENTER FOR MECHANISMS OF EVOLUTION AND PROFESSOR AT ASU'S SCHOOL OF LIFE SCIENCES. view more
CREDIT: THE BIODESIGN INSTITUTE AT ARIZONA STATE UNIVERSITY
In order to survive, flourish and successfully reproduce, organisms rely on a high degree of genetic stability. Mutagenic agents, which can threaten the integrity of the genetic code by causing mutations in DNA, pose a serious risk to human health. They have long been implicated in a range of genetically inherited afflictions, as well as cancer, aging and neurodegenerative diseases like Alzheimer's.
It now appears that mutagenic threats to a cell's subtle machinery may be far more widespread than previously appreciated. In a new study, Michael Lynch and his colleagues demonstrate that DNA mutation itself may represent only a fraction the health-related havoc caused by mutagens.
The study highlights the ability of mutagenic compounds to also affect the process of transcription, during which a DNA sequence is converted (or transcribed) to mRNA, an intermediary stage preceding translation into protein.
The research findings, (which highlight mutagenic transcription errors in yeast, worms, flies and mice), suggest that the harmful effects of mutagens on transcription are likely much more pervasive than previously appreciated--a fact that may have momentous implications for human health.
"Our results have the potential to completely transform the way we think about the consequences of environmental mutagens," Lynch says.
Professor Lynch is the director of the Biodesign Center for Mechanisms in Evolution and a researcher in ASU's School of Life Sciences.
The research results appear in the current issue of the journal PNAS.
Cells under threat
Due to their important role in disease processes, mutagenic compounds have long been a topic of intensive scientific study. Such agents include sunlight and other sources of radiation, chemotherapeutics, toxic byproducts of cellular metabolism, or chemicals present in food and water.
Mutagens can inflict damage to the DNA, which can later snowball when cells divide, and DNA replication multiplies these errors. Such mutations, if not corrected through DNA proofreading mechanisms, can be passed to subsequent generations and depending on the location at which they appear along the human DNA strand's three billion letter code may seriously impact health, in some cases, with lethal results.
But even if repaired prior to replication, transiently damaged DNA can also interfere with transcription--the process of producing RNA from a DNA sequence. This can happen when RNA polymerase, an enzyme that moves along a single strand of DNA, producing a complementary RNA strand, reads a mutated sequence of DNA, causing an error in the resulting RNA transcript.
Because RNA transcripts are the templates for producing proteins, transcription errors can produce aberrant proteins harmful to health or terminate protein synthesis altogether. It is already known that even under the best of conditions, transcript error rates are orders of magnitude higher than those at the DNA level.
RNA: a string of errors?
While the existence of transcription errors has long been recognized, their quantification has been challenging. The new study describes a clever technique for ferreting out transcription errors caused by mutagens and separating these from experimental artifacts--mutations caused during library preparation of RNA transcripts through processes of reverse-transcription and sequencing.
The method described involves the use of massively parallel sequencing technology to identify only those errors in RNA sequence directly caused by the activity of a mutagen. The results demonstrate that at least some mutagenic compounds are potent sources of both genomic mutations and abundant transcription errors.
The circular sequencing assay outlined in the study creates redundancies in the reverse-transcribed message, providing a means of proofreading the resultant linear DNA. In this way, researchers can confirm that the transcription errors observed are a result of the mutagen's effects on transcription and not an artifact of sample preparation.
The DNA molecule has been shown to be particularly vulnerable to a class of mutagens known as alkylating agents. One of these, known as MNNG, was used to inflict transcriptional errors on the four study organisms. The effects observed were dose-dependent, with higher levels of mutagen causing a corresponding increase in transcriptional errors.
Hidden mistakes may be costly to health
Transcription errors differ from mutations in the genome in at least one vital respect. While DNA replication during cell division acts to amplify mutations to the genome, transcription errors can accumulate in non-dividing cells, with a single mutated DNA template giving rise to multiple abnormal RNA transcripts.
The full effects of these transcription errors on human health remain largely speculative because they have not been amenable to study until now. Using the new technique, researchers can mine the transcriptome--the full library of a living cell's RNA transcripts, searching for errors caused by mutagens.
While the new research offers hope for a more thorough understanding of the relationship between various mutagens and human health, it is also a cautionary tale. A preoccupation with mutational defects in DNA sequence may have blinded science to the potential effects of agents that result in transcription errors without leaving permanent traces in the genome.
This fact raises the possibility that a broad range of environmental factors as well as chemicals and foods deemed safe for human consumption are in need of careful reevaluation based on their potential for producing transcriptional mutagenesis. Further, transcriptional errors in both dividing and non-dividing cell types are likely key players in the complex processes of physical aging
Beyond changing DNA itself, mutagensalso cause errors in gene transcription
The discovery that toxic stressors can cause errors in gene transcription opens new avenues of research on diseases such as Alzheimer's and Parkinson's and sheds light on the potential role of the "transcriptome" in aging.
IMAGE: ASSISTANT PROFESSOR MARC VERMULST view more
CREDIT: USC/STEPHANIE KLEINMAN
Exposure to mutagens, or mutation-causing agents, can not only bring about changes in DNA but also appear to induce errors when genes are transcribed to make proteins, which may be an important factor in age-related diseases.
USC Leonard Davis School of Gerontology Assistant Professor Marc Vermulst and colleagues made the discovery by using state-of-the-art circle sequencing techniques to determine how frequently molecules called RNA polymerases make mistakes when they read (or "transcribe") our DNA. RNA polymerases transcribe DNA to make temporary copies of genes, which are then used to build all of the proteins required to keep us alive and healthy.
Transcription errors vastly outnumber DNA mutations
Vermulst compared our cells to a busy kitchen, teeming with hundreds of chefs that are all making dishes out of a single recipe book. Because it's so busy, they cannot take the recipe book with them when an order comes in. So instead they send the kitchen staff to the recipe book to read the recipes as carefully as possible and then bring the instructions to the chefs. Our cells work in a very similar manner. When an "order" for a protein comes in, RNA polymerases are sent to our genome (or in other words, our recipe book), to make a temporary copy of a gene. That temporary copy is then brought to the chefs, who cook the protein just like the message they received dictates. In this example, transcription errors could be an incorrect amount or ingredient that wasn't properly recorded by the person jotting down the recipe.
"The molecule doing the reading and writing is what's introducing the errors, even if the DNA itself isn't mutated," he explained.
To demonstrate that a mutagen - an agent that can cause a genetic mutation - can induce these errors, Vermulst and his team exposed yeast cells to the chemical N-Methyl-N?-nitro-N-nitrosoguanidine (MNNG), then screened for transcription errors. The cells exposed to MNNG displayed many more transcription errors than the unexposed cells, and in addition, the rate of transcription errors vastly outnumbered the rate of DNA mutations. The team confirmed similar results when the experiments were repeated in cells from the worm species C. elegans, fruit fly D. melanogaster and mice.
DNA mutations occur when the genome is inaccurately copied during cell division, leaving the newly formed cells with a mistake in their DNA. However, a few types of cells, including neurons and muscle cells, rarely divide in adults. These cells all still need to transcribe proteins, which means that harmful errors within these cells are much more likely to arise from transcription, Vermulst explained.
"There are a hundredfold more transcription errors being made for every DNA mutation that eventually arises," he said.
A possible role in several diseases
The genes that code for a protein not only instruct which amino acids to put in what order but also control the specific shape into which the finished protein folds itself. Transcription errors often cause proteins to misfold into a dysfunctional shape, which can result in clusters, or plaques, of nonfunctioning proteins that hinder healthy cell function. This raises questions of how these errors may play roles in diseases such as Alzheimer's, Parkinson's, amyotrophic lateral sclerosis (ALS) and others, Vermulst said.
In future research, Vermulst is pushing for more investigation into whether other substances known to cause DNA mutations also affect transcription, as well as if there are any substances previously thought of as safe that may be in fact inducing transcription errors.
"This is potentially a really important finding in the context of genetic toxicology: a new mechanism by which all these molecules - from exposures in our environment or from our lifestyle choices - can result in pathology," he said. "There could potentially be molecules that we're eating and drinking that are deemed safe because they don't result in any genetic changes, but do result in transcription errors, that have gone completely unnoticed because nobody had a tool to see whether or not that was happening."
He also hopes that the research will make new links between established pillars of aging research - DNA damage, mitochondrial dysfunction, oxidative species and others - and connect them in a mechanistic way to detrimental outcomes such as Alzheimer's, Parkinson's and cancer. It may also help identify sources of the symptoms in DNA repair deficiency disorder, in which patients are unable to repair damage to their genome properly and often results in accelerated aging or increased cancer risk.
While recent years have seen increased interest in the "transcriptome" - the entirety of what is transcribed from a genome - Vermulst wants to focus on the accuracy of what's being transcribed and not just the amount of each protein produced. He hopes this quality-over-quantity approach offers new insight into the fundamental processes of diseases.
"If you've done the same thing a hundred times and you don't get a solution for your problem, it might be something that you've overlooked," he said. "So we're trying to find this something else."
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Vermulst's co-corresponding author for the study was Michael Lynch of Arizona State University, and first author was Clark Fritsch of the University of Pennsylvania. Other coauthors included Berenice Benayoun, Prakroothi S. Danthi, Eric McGann, Jessica LaGosh and Claire Chung of the USC Leonard Davis School; Jean-Francois Gout of Mississippi State University; Suraiya Haroon, Atif Towheed, Yuanquan Song and Douglas Wallace of the Children's Hospital of Philadelphia; Xinmin Zhang of BioInfoRx, Inc.; and Stephen Simpson and Kelley Thomas of the University of New Hampshire.
The study, "Genome-wide surveillance of transcription errors in response to genotoxic stress," appeared online in Proceedings of the National Academy of Sciences on December 21, 2020. This research was supported by the National Institute on Aging Award R01AG054641 and American Federation for Aging Research young investigator award in Alzheimer's disease to Vermulst; the Multidisciplinary University Research Initiative Awards W911NF-09-1-0444 from the US Army Research Office and NIH Award R35-GM122566-01 to Lynch; and Environmental Toxicology Training Grant T32ES019851 by the National Institute of Environmental Health Sciences to Fritsch.
Deep, slow-slip action may direct largest earthquakes and their tsunamis
IMAGE: MAP OF THE CASCADIA SUBDUCTION ZONE. view more
CREDIT: PUBLIC DOMAIN
Megathrust earthquakes and subsequent tsunamis that originate in subduction zones like Cascadia -- Vancouver Island, Canada, to northern California -- are some of the most severe natural disasters in the world. Now a team of geoscientists thinks the key to understanding some of these destructive events may lie in the deep, gradual slow-slip behaviors beneath the subduction zones. This information might help in planning for future earthquakes in the area.
"What we found was pretty unexpected," said Kirsty A. McKenzie, doctoral candidate in geoscience, Penn State.
Unlike the bigger, shallower megathrust earthquakes that move and put out energy in the same direction as the plates move, the slow-slip earthquakes' energy may move in other directions, primarily down.
Subduction zones occur when two of the Earth's plates meet and one moves beneath the other. This typically creates a fault line and some distance away, a line of volcanoes. Cascadia is typical in that the tectonic plates meet near the Pacific coast and the Cascade Mountains, a volcanic range containing Mount St. Helens, Mount Hood and Mount Rainier, forms to the east.
According to the researchers, a megathrust earthquake of magnitude 9 occurred in Cascadia in 1700 and there has not been a large earthquake there since then. Rather, slow-slip earthquakes, events that happen deeper and move very short distances at a very slow rate, happen continuously.
"Usually, when an earthquake occurs we find that the motion is in the direction opposite to how the plates have moved, accumulating that slip deficit," said Kevin P. Furlong, professor of geosciences, Penn State. "For these slow-slip earthquakes, the direction of movement is directly downward in the direction of gravity instead of in the plate motion directions."
The researchers have found that areas in New Zealand, identified by other geologists, slow slip the same way Cascadia does.
"But there are subduction zones that don't have these slow-slip events, so we don't have direct measurements of how the deeper part of the subducting plate is moving," said Furlong. "In Sumatra, the shallower seismic zone, as expected, moves in the plate-motion direction, but even though there are no slow-slip events, the deeper plate movement still appears to be primarily controlled by gravity."
Slow-slip earthquakes occur at a deeper depth than the earthquakes that cause major damage and earth-shaking events, and the researchers have analyzed how this deep slip may affect the timing and behavior of the larger, damaging megathrust earthquakes.
"Slow-slip earthquakes rupture over several weeks, so they are not just one event," said McKenzie. "It's like a swarm of events."
According to the researchers, in southern Cascadia, the overall plate motion is about an inch of movement per year and in the north by Vancouver Island, it is about 1.5 inches.
"We don't know how much of that 30 millimeters (1 inch) per year is accumulating to be released in the next big earthquake or if some movement is taken up by some non-observable process," said McKenzie. "These slow-slip events put out signals we can see. We can observe the slow-slip events going east to west and not in the plate motion direction."
Slow-slip events in Cascadia occur every one to two years, but geologists wonder if one of them will be the one that will trigger the next megathrust earthquake.
The researchers measure surface movement using permanent, high-resolution GPS stations on the surface. The result is a stair step pattern of loading and slipping during slow-slip events. The events are visible on the surface even though geologists know they are about 22 miles beneath the surface. They report their results in Geochemistry, Geophysics, Geosystems.
"The reason we don't know all that much about slow-slip earthquakes is they were only discovered about 20 years ago," said Furlong. "It took five years to figure out what they were and then we needed precise enough GPS to actually measure the motion on the Earth's surface. Then we had to use modeling to convert the slip on the surface to the slip beneath the surface on the plate boundary itself, which is bigger."
The researchers believe that understanding the effects of slow-slip earthquakes in the region at these deeper depths will allow them to understand what might trigger the next megathrust earthquake in the area. Engineers want to know how strong shaking in an earthquake will be, but they also want to know the direction the forces will be in. If the difference in direction of slow-slip events indicates a potential change in behavior in a large event, that information would be helpful in planning.
"More fundamentally, we don't know what triggers the big earthquake in this situation," said McKenzie. "Every time we add new data about the physics of the problem, it becomes an important component. In the past, everyone thought that the events were unidirectional, but they can be different by 40 or 50 degrees."
While the slow-events in Cascadia are shedding light on potential megathrust earthquakes in the area and the tsunamis they can trigger, Furlong thinks that other subduction zones may also have similar patterns.
"I would argue that it (differences in direction of motion) is happening in Alaska, Chile, Sumatra," said Furlong. "It is only in a few that we see the evidence of it, but it may be a universal process that has been missed. Cascadia exhibits it because of the slow-slip events, but it may be fundamental to subduction zones."
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Also working on this project was Matthew W. Herman, assistant professor of geology, California State University, Bakersfield.
The National Science Foundation supported this work.
A groggy climate giant: subsea permafrost is still waking up after 12,000 years
New research suggests slow but substantial greenhouse gas release from submarine permafrost
IMAGE: ARTISTIC DIAGRAM OF THE SUBSEA AND COASTAL PERMAFROST ECOSYSTEMS, EMPHASIZING GREENHOUSE GAS PRODUCTION AND RELEASE. view more
CREDIT: ORIGINAL ARTWORK CREATED FOR THIS STUDY BY VICTOR OLEG LESHYK AT NORTHERN ARIZONA UNIVERSITY.
In the far north, the swelling Arctic Ocean inundated vast swaths of coastal tundra and steppe ecosystems. Though the ocean water was only a few degrees above freezing, it started to thaw the permafrost beneath it, exposing billions of tons of organic matter to microbial breakdown. The decomposing organic matter began producing CO2 and CH4, two of the most important greenhouse gases.
Though researchers have been studying degrading subsea permafrost for decades, difficulty collecting measurements and sharing data across international and disciplinary divides have prevented an overall estimate of the amount of carbon and the rate of release. A new study, led by Ph.D. candidate Sara Sayedi and senior researcher Dr. Ben Abbott at Brigham Young University (BYU) published in IOP Publishing journal Environmental Research Letters, sheds light on the subsea permafrost climate feedback, generating the first estimates of circumarctic carbon stocks, greenhouse gas release, and possible future response of the subsea permafrost zone.
Sayedi and an international team of 25 permafrost researchers worked under the coordination of the Permafrost Carbon Network (PCN), which is supported by the U.S. National Science Foundation. The researchers combined findings from published and unpublished studies to estimate the size of the past and present subsea carbon stock and how much greenhouse gas it might produce over the next three centuries.
Using a methodology called expert assessment, which combines multiple, independent plausible values, the researchers estimated that the subsea permafrost region currently traps 60 billion tons of methane and contains 560 billion tons of organic carbon in sediment and soil. For reference, humans have released a total of about 500 billion tons of carbon into the atmosphere since the Industrial Revolution. This makes the subsea permafrost carbon stock a potential giant ecosystem feedback to climate change.
"Subsea permafrost is really unique because it is still responding to a dramatic climate transition from more than ten thousand years ago," Sayedi said. "In some ways, it can give us a peek into the possible response of permafrost that is thawing today because of human activity."
Estimates from Sayedi's team suggest that subsea permafrost is already releasing substantial amounts of greenhouse gas. However, this release is mainly due to ancient climate change rather than current human activity. They estimate that subsea permafrost releases approximately 140 million tons of CO2 and 5.3 million tons of CH4 to the atmosphere each year. This is similar in magnitude to the overall greenhouse gas footprint of Spain.
The researchers found that if human-caused climate change continues, the release of CH4 and CO2 from subsea permafrost could increase substantially. However, this response is expected to occur over the next three centuries rather than abruptly. Researchers estimated that the amount of future greenhouse gas release from subsea permafrost depends directly on future human emissions. They found that under a business-as-usual scenario, warming subsea permafrost releases four times more additional CO2 and CH4 compared to when human emissions are reduced to keep warming less than 2°C.
"These results are important because they indicate a substantial but slow climate feedback," Sayedi explained. "Some coverage of this region has suggested that human emissions could trigger catastrophic release of methane hydrates, but our study suggests a gradual increase over many decades."
Even if this climate feedback is relatively gradual, the researchers point out that subsea permafrost is not included in any current climate agreements or greenhouse gas targets. Sayedi emphasized that there is still a large amount of uncertainty about subsea permafrost and that additional research is needed.
"Compared to how important subsea permafrost could be for future climate, we know shockingly little about this ecosystem," Sayedi said. "We need more sediment and soil samples, as well as a better monitoring network to detect when greenhouse gas release responds to current warming and just how quickly this giant pool of carbon will wake from its frozen slumber."
The coastline of the Bykovsky Peninsula in the central Laptev Sea, Siberia retreats during summer, when ice-rich blocks of permafrost fall to the beach and are eroded by waves
This research was funded by the U.S. National Science Foundation and by BYU Graduate Studies.
Summary of the key scientific points:
Subsea permafrost has been thawing since the end of the last glacial period (~14,000 years ago) when it began to be inundated by the ocean
An international team of 25 permafrost researchers estimate that the subsea permafrost region currently traps 60 billion tons of methane and 560 billion tons of organic carbon in sediment and soil. However, the exact amount of these carbon stocks remains highly uncertain.
This carbon is already being released from the subsea permafrost region, though it remains unclear whether this is a natural response to deglaciation or if anthropogenic warming is accelerating greenhouse gas production and release.
The researchers estimate that currently, the subsea permafrost region releases approximately 140 million tons of CO2 and 5.3 million tons of CH4 to the atmosphere each year. This represents a small fraction of total anthropogenic greenhouse gas emissions--approximately equal to the greenhouse gas footprint of Spain.
Experts predict a gradual increase in emissions from subsea permafrost over the next three hundred years rather than an abrupt release.
The amount of greenhouse gas increase depends on how much human emissions are reduced. Experts estimate that approximately ¾ of the extra subsea emissions can be avoided if humans actively reduce their emissions compared to a no mitigation scenario.
This climate feedback is still virtually absent from climate policy discussions, and more field observations are needed to better predict the future of this system.
CAPTION
The coastline of the Bykovsky Peninsula in the central Laptev Sea, Siberia retreats during summer, when ice-rich blocks of permafrost fall to the beach
Quotes from other co-authors:
"I think there are three important messages from this study. First, subsea permafrost is probably not a climate time bomb on a hair trigger. Second, subsea permafrost is a potentially large climate feedback that needs to be considered in climate negotiations. Third, there is still a huge amount that we don't know about this system. We really need additional research, including international collaboration across northern countries and research disciplines."
Dr. Ben Abbott, senior researcher on the project, Brigham Young University
"This work demonstrates the power of science synthesis and networking by bringing together experts across a range of disciplines in order to assess our state of knowledge based on observations and models currently available. While scientific work will continue to be done to test these ideas, bringing knowledge together with this expert assessment provides an important baseline for shaping future research on subsea permafrost greenhouse gas emissions."
Dr. Ted Schuur, Lead investigator of the Permafrost Carbon Network, Northern Arizona University
"This expert assessment is a crucial contribution to the scientific literature in advancing our knowledge on subsea permafrost and potential greenhouse gas emissions from this so far understudied pool. Bringing together scientists from multiple disciplines, institutions, and countries has made it possible to move beyond individual datapoints or studies providing a much more comprehensive estimate of subsea permafrost. "
Dr. Christina Schädel, Co-Investigator of the Permafrost Carbon Network, Northern Arizona University
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High resolution versions of the photos and illustrations are available at this link.
Study sets baseline for sleep patterns in healthy adult dogs
A new canine sleep study from North Carolina State University could serve as a baseline for research on chronic pain and cognitive dysfunction in dogs, potentially improving detection and treatment of these conditions.
"The study was necessary because research on dogs and sleep has outpaced our basic knowledge about what a 'normal' sleep/wake cycle looks like," says Margaret Gruen, assistant professor of behavioral medicine at NC State and corresponding author of the work. "The studies currently available are over 20 years old, only followed small numbers of dogs or dogs that were not in a home environment, and didn't really capture data that is relevant to how dogs live (and sleep) now. We designed the study to update these findings and fill the knowledge gap.
"And for me, someone interested in how dogs develop and age, it's a critically missing gap: we talk about a symptom of age-related cognitive dysfunction in dogs as being a disruption in the sleep/wake cycle without really understanding where the baseline is."
The study followed 42 healthy adult dogs - 21 male and 21 female - ranging in age from 2 to 8 years old. The dogs wore activity monitors on their collars for a two-week period, and their owners filled out a questionnaire on the dogs' sleep patterns. Functional linear modeling of the activity data showed that most dogs have two activity peaks during the day: a shorter window from 8 a.m. to 10 a.m., followed by a midday lull and a longer active period from about 5 p.m. to 11 p.m. All dogs were more active during weekends than weekdays.
"Since most of the participants were pets of people who work outside the home, we saw that the dogs were most active when human interaction happens," Gruen says. "There were the occasional outliers - we did capture some midday 'zoomies' - but the pattern held true on average across 14 days for each dog. These findings aren't surprising - they line up with many of the assumptions we've been making, but now the data are characterized and documented."
The research revealed that weight and sex had an effect on the active periods; lighter dogs tended to be more active in a short period just after midnight, while female dogs seemed to be more active during the evening peak than males. Even in these healthy adult dogs, age had an effect; older dogs were less active during the peak activity times.
"Our hope is that this will serve as a foundational study for future work on the relationship between pain, cognitive dysfunction and sleep disruption, and as a study that is relevant to the way dogs live now," Gruen says. "By establishing norms, we can better identify abnormalities and intervene earlier in the process. We can also use this as a baseline to evaluate development of adult sleep patterns in puppies."
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The research appears in Scientific Reports. NC State graduate student Hope Woods is first author. Duncan Lascelles, professor of translational pain research and management at NC State, also contributed to the work. Evolutionary anthropologist David Samson and his team, from the University of Toronto, Canada, created the functional linear models.
Note to editors: An abstract follows.
"Let sleeping dogs lie: A functional linear modeling approach to sleep-wake cycles in dogs"
Authors: Margaret Gruen, Hope Woods, Duncan Lascelles, North Carolina State University; Ming Fei Li, Ujas Patel, David Samson, University of Toronto, Canada
Published: Online Dec. 17, 2020 in Scientific Reports
Abstract: The study of companion (pet) dogs is an area of great translational potential, as they share many conditions that afflict both dogs and humans. These include conditions that affect sleep, including chronic pain and cognitive dysfunction. Significant advancements have
Do I know you? Researchers evaluate how masks disrupt facial perception
Study conducted by Ben-Gurion University of the Negev researchers
AMERICAN ASSOCIATES, BEN-GURION UNIVERSITY OF THE NEGEV
IMAGE: THE IDENTIFICATION OF PEOPLE WEARING MASKS HAS OFTEN PRESENTED A UNIQUE CHALLENGE DURING THE PANDEMIC. A NEW STUDY BY RESEARCHERS FROM BEN-GURION UNIVERSITY OF THE NEGEV (BGU) IN ISRAEL AND... view more
CREDIT: CHICAGO FACE DATABASE (MA ET AL., 2015)
BEER-SHEVA, Israel...December 21, 2020 - The identification of people wearing masks has often presented a unique challenge during the pandemic. A new study by researchers from Ben-Gurion University of the Negev (BGU) in Israel and York University in Canada reveals the impact of this predicament and its potentially significant repercussions.
The findings were just published in the journal Scientific Reports.
"For those of you who don't always recognize a friend or acquaintance wearing a mask, you are not alone," according to the researchers Prof. Tzvi Ganel, head of the Laboratory for Visual Perception and Action at the BGU Department of Psychology, and Prof. Erez Freud, who earned his Ph.D. at BGU and is now a faculty member at York University in Toronto, Ontario.
"Faces are among the most informative and significant visual stimuli in human perception and play a unique role in communicative, social daily interactions," the researchers note. "The unprecedented effort to minimize COVID-19 transmission has created a new dimension in facial recognition due to mask wearing."
To examine the effects of wearing masks, Prof. Ganel and Prof. Freud used a modified version of the Cambridge Face Memory Test, the standard for assessing facial perception, which included masked and unmasked faces. The study was conducted online with a large group of nearly 500 people.
The researchers found that the success rate of identifying someone wearing a mask was reduced by 15%. "This could lead to many errors in correctly recognizing people we know, or alternatively, accidently recognizing faces of unfamiliar people as people we know," says Prof. Galia Avidan who is a member of the BGU Department of Psychology and the Department of Cognitive and Brain Sciences, and an expert on facial recognition and perception. "Face masks could be even more challenging to people whose face recognition skills are not ideal to begin with and cause greater impairment."
The research team also found that masks specifically interfered with extracting a holistic impression of faces and led to feature-by-feature processing which is a less accurate and more time-consuming strategy.
"Instead of looking at the entire face, we're now forced to look at eyes, nose, cheeks, and other visible elements separately to construct an entire facial face percept - which we used to do instantly," the researchers say.
These changes in performance, along with the alteration along the processing style of faces, could have significant effects on activities of daily living, including social interactions, as well as other situations involving personal interactions, such as education.
"Given that mask wearing has rapidly become an important norm in countries around the globe, future research should explore the social and psychological implications of wearing masks on human behavior," Ganel says. "The magnitude of the effect of masks that we report in the current study is probably an underestimation of the actual degree in performance dropdown for masked faces."
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In addition to the BGU researchers, the Canadian team included Prof. Erez Freud who led the study, Andreja Stajduhar, and Prof. Shayna Rosenbaum of York University Department of Psychology and the Centre for Vision Research.
This study was supported by the Israel Science Foundation (Grant no. 296/15) and by the Vision Science to Applications (VISTA) program funded by the Canada First Research Excellence Fund (CFREF, 2016-2023) and by the Natural Sciences and Engineering Research Council of Canada.
About American Associates, Ben-Gurion University of the Negev
American Associates, Ben-Gurion University of the Negev (AABGU) plays a vital role in sustaining David Ben-Gurion's vision: creating a world-class institution of education and research in the Israeli desert, nurturing the Negev community and sharing the University's expertise locally and around the globe. Activities include showcasing BGU's academic excellence and cutting-edge research through educational programs, events and informative communications. AABGU's main purpose is to support Ben-Gurion's vision and the university that bears his name by creating a community of Americans committed to improving the world tomorrow from the heart of the Israeli desert today. For more information visit http://www.aabgu.org.
