Study identifies jet-stream pattern that locks in extreme winter cold, wet spells

Big waves have doubled since 1950s, possibly due to shifting climate

Peer-Reviewed Publication

COLUMBIA CLIMATE SCHOOL

 

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AN IDEALIZED ILLUSTRATION OF GIANT MEANDERS IN THE GLOBAL JET STREAM KNOWN AS WAVE-4 PATTERNS, WHICH ARE BRINGING EXTREME WINTER COLD AND/OR PRECIPITATION (BLUE AREAS) TO PARTS OF NORTH AMERICA AND EUROPE.

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CREDIT: GRAPHIC BY KAI KORNHUBER.

Winter is coming—eventually. And while the earth is warming, a new study suggests that the atmosphere is being pushed around in ways that cause long bouts of extreme winter cold or wet in some regions.

The study’s authors say they have identified giant meanders in the global jet stream that bring polar air southward, locking in frigid or wet conditions concurrently over much of North America and Europe, often for weeks at a time. Such weather waves, they say, have doubled in frequency since the 1960s. In just the last few years, they have killed hundreds of people and paralyzed energy and transport systems.

The new paper appears this week in the Bulletin of the American Meteorological Society.

“Even though winters are getting milder on average, it’s happening at the expense of increasingly devastating heat extremes in the warm season,” said author Kai Kornhuber, an adjunct scientist at Columbia University’s Lamont-Doherty Earth Observatory. “A hundred years from now, we will probably not have to worry as much about extreme cold, because everything is getting warmer. But today and going forward, cold is still a very relevant hazard.”

The jet stream is a fast-moving river of air that continuously circles the Northern Hemisphere from east to west. It generally flows within relatively straight boundaries, segregating cold polar air masses from the midlatitudes, but at times it can naturally develop big wobbles. Some scientists think these wobbles are increasing in size and frequency due to rapid warming in the Arctic that is far out proportion to more southerly regions; this destabilizes the system, generating winds that break down the north-south barrier, they say. Given the right conditions, certain of these wobbles can become amplified into symmetrical waves that then lock in place across the globe, somewhat similar to the vibrations that produce a constant musical pitch. These are called Rossby waves.

In a 2019 study Kornhuber and colleagues showed that a repeating Rossby wave pattern known as a wave-7—that is, seven giant peaks and seven matching troughs spanning the globe—draws warm, dry air from the subtropics up to the midlatitudes, causing concurrent summer heat waves and droughts in predictable parts of North America, Europe and Asia. These can cause widespread, simultaneous crop losses in important breadbasket regions, the study said.

The newer paper shows more or less the other side of the coin. A winter pattern known as a wave-4—globally, four peaks and four matching troughs —tend to lock in place. The authors say that when this happens, the chances of extreme cold or wet in the trough triples. At the same time, abnormally warm or dry conditions may develop in the peaks.

The most recent major wave-4 iteration brought a February 2021 cold wave to much of Canada, the United States and even northern Mexico. Temperatures fell as much as 50 degrees F below average as far south as the U.S. Gulf Coast. Parts of the Deep South saw rare snowfall. Hardest hit: Texas, where record cold paralyzed natural gas pipelines and other energy infrastructure, knocking out much of the electricity grid and causing homes and businesses to go dark and freeze. All told, at least 278 people were killed directly or indirectly by the cold wave, and there was nearly $200 billion in damage. A similar though less destructive event caused a January-February 2019 cold snap in the eastern United States, killing more than 20 people.

The same pattern often hits on the other side of the Atlantic at the same time, usually most most extreme in southwestern Europe and Scandinavia. The January-February 2019 event brought extreme low temperatures to both southern France and Sweden. At the same time, by sweeping in moist air from the Atlantic, it caused extreme precipitation and flooding across many areas in central and eastern Europe. Similar events took place in Europe in 2013 and 2018.

The researchers say that 50 years ago, such concurrent waves took hold on average only once each winter. The numbers vary year to year, but now the average has risen to twice a year.

“This adds to the growing evidence that extreme weather over North America and Europe are often synchronized,” said the study’s other author, Gabriele Messori of Sweden’s Uppsala University. Messori published a paper earlier this year noting repeated example of this phenomenon, and hypothesizing a connection to large-scale atmospheric circulation patterns.

Kornhuber said the exact mechanisms that cause the emergence of the wave-4 pattern require further research, but he suspects it starts with periodic changes in oceanic conditions over parts of the Pacific that, under the right circumstances, can trigger a global chain reaction. Pinning down that mechanism might allow scientists to better predict the cold or wet waves, he said.

Kornuber said that there is growing evidence of a connection between warming climate and the summer meanders that bring heat waves; however the winter waves are still a matter of intense scientific discourse. Scientists are currently investigating several possible mechanisms that could point to a climate connection, and how things might evolve in future.

Kornhuber noted that a study he coauthored earlier this year showed that climate models still struggle to reproduce the most extreme regional weather anomalies associated with these larger-scale patterns even in summer; this could lead to underestimations of potential weather-related crop losses in particular areas. He said upcoming work will focus on investigating whether the worst extreme are linked to human causes or just natural variability.

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JOURNAL

Bulletin of the American Meteorological Society

DOI

10.1175/BAMS-D-21-0295.1 

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Recent Increase in a Recurrent Pan-Atlantic Wave Pattern Driving Concurrent Wintertime Extremes

ARTICLE PUBLICATION DATE

2-Oct-2023

 

New research finds that ancient carbon in rocks releases as much carbon dioxide as the world's volcanoes

Peer-Reviewed Publication

UNIVERSITY OF OXFORD

 

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SEDIMENTARY ROCKS ON THE BANKS OF THE MACKENZIE RIVER, CANADA, A MAJOR RIVER BASIN WHERE ROCK WEATHERING IS A CO2 SOURCE. IMAGE CREDIT: ROBERT HILTON.

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CREDIT: ROBERT HILTON.

Main points:

• New research has overturned the traditional view that natural rock weathering acts as a CO2 sink that removes CO2 from the atmosphere. Instead, this can also act as a large CO2 source, rivalling that of volcanoes.
• The results have important implications for modelling climate change scenarios but at the moment, CO2 release from rock weathering is not captured in climate modelling.
• Future work will focus on whether human activities may be increasing CO2 release from rock weathering, and how this could be managed.

A new study led by the University of Oxford has overturned the view that natural rock weathering acts as a CO2 sink, indicating instead that this can also act as a large CO2 source, rivalling that of volcanoes. The results, published today in the journal Nature, have important implications for modelling climate change scenarios.

Rocks contain an enormous store of carbon in the ancient remains of plants and animals that lived millions of years ago. This means that the “geological carbon cycle” acts as a thermostat that helps to regulate the Earth’s temperature. For instance, during chemical weathering rocks can suck up CO2 when certain minerals are attacked by the weak acid found in rainwater. This process helps to counteract the continuous CO2 released by volcanoes around the world, and forms part of Earth’s natural carbon cycle that has helped keep the surface habitable to life for a billion years or more.

However, for the first time this new study measured an additional natural process of CO2 release from rocks to the atmosphere, finding that it is as significant as the CO2 released from volcanoes around the world. Currently, this process is not included in most models of the natural carbon cycle.

The process occurs when rocks that formed on ancient seafloors (where plants and animals were buried in sediments) are pushed back up to Earth’s surface, for example when mountains like the Himalayas or Andes form. This exposes the organic carbon in the rocks to oxygen in the air and water, which can react and release CO2. This means that weathering rocks could be a source of CO2, rather than the commonly assumed sink.

Up to now, measuring the release of this CO2 from weathering organic carbon in rocks has proved difficult. In the new study, the researchers used a tracer element (rhenium) which is released into water when rock organic carbon reacts with oxygen. Sampling river water to measure rhenium levels makes it possible to quantify CO2 release. However, sampling all river water in the world to get a global estimate would be a significant challenge.

To upscale over Earth’s surface, the researchers did two things. First, they worked out how much organic carbon is present in rocks near the surface. Second, they worked out where these were being exposed most rapidly, by erosion in steep, mountain locations.

Dr Jesse Zondervan, the researcher who led the study at the Department of Earth Sciences, University of Oxford, said: “The challenge was then how to combine these global maps with the river data, while considering uncertainties. We fed all of our data into a supercomputer at Oxford, simulating the complex interplay of physical, chemical, and hydrological processes. By piecing together this vast planetary jigsaw, we could finally estimate the total carbon dioxide emitted as these rocks weather and exhale their ancient carbon into the air."

This could then be compared to how much CO2 could be drawn down by natural rock weathering of silicate minerals. The results identified many large areas where weathering was a CO2 source, challenging the current view about how weathering impacts the carbon cycle. Hotspots of CO2 release were concentrated in mountain ranges with high uplift rates that cause sedimentary rocks to be exposed, such as the eastern Himalayas, the Rocky Mountains, and the Andes. The global CO2 release from rock organic carbon weathering was found to be 68 megatons of carbon per year.

Professor Robert Hilton (Department of Earth Sciences, University of Oxford), who leads the ROC-CO2 research project that funded the study, said: “This is about 100 times less than present day human CO2 emissions by burning fossil fuels, but it is similar to how much CO2 is released by volcanoes around the world, meaning it is a key player in Earth’s natural carbon cycle”.

These fluxes could have changed during Earth’s past. For instance, during periods of mountain building that bring up many rocks containing organic matter, the CO2 release may have been higher, influencing global climate in the past.

Ongoing and future work is looking into how changes in erosion due to human activities, alongside the increased warming of rocks due to anthropogenic climate changes, could increase this natural carbon leak. A question the team are now asking is if this natural CO2 release will increase over the coming century. “Currently we don’t know – our methods allow us to provide a robust global estimate, but not yet assess how it could change’’ says Hilton.

“While the carbon dioxide release from rock weathering is small compared to present-day human emissions, the improved understanding of these natural fluxes will help us better predict our carbon budget” concluded Dr. Zondervan.

Notes to editors:

Media contact – Professor Robert Hilton, robert.hilton@earth.ox.ac.uk

The study ‘Rock organic carbon oxidation CO2 release offsets silicate weathering sink’ will be published in Nature at 16:00 BST/ 11:00 ET on Wednesday 04 October 2023 at https://doi.org/10.1038/s41586-023-06581-9

To view a copy of the paper before this under embargo, contact Dr Caroline Wood: caroline.wood@admin.ox.ac.uk

About the University of Oxford

Oxford University has been placed number 1 in the Times Higher Education World University Rankings for the eighth year running, and ​number 3 in the QS World Rankings 2024. At the heart of this success are the twin-pillars of our ground-breaking research and innovation and our distinctive educational offer.

Oxford is world-famous for research and teaching excellence and home to some of the most talented people from across the globe. Our work helps the lives of millions, solving real-world problems through a huge network of partnerships and collaborations. The breadth and interdisciplinary nature of our research alongside our personalised approach to teaching sparks imaginative and inventive insights and solutions.

Through its research commercialisation arm, Oxford University Innovation, Oxford is the highest university patent filer in the UK and is ranked first in the UK for university spinouts, having created more than 300 new companies since 1988. Over a third of these companies have been created in the past five years. The university is a catalyst for prosperity in Oxfordshire and the United Kingdom, contributing £15.7 billion to the UK economy in 2018/19, and supports more than 28,000 full time jobs.

Shale rocks high up in the remote Mackenzie mountains Canada, which contain lots of rock organic carbon and are hotspots of CO2 release. Image credit: Robert Hilton.

Landslides in the high Andes of Peru, exposing rocks full of organic matter to weathering which can release CO2. Image credit: Robert Hilton.

High erosion in southern France exposes these sedimentary rocks to weathering, releasing CO2 as the ancient organic carbon breaks down. Image credit: Robert Hilton

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JOURNAL

Nature

DOI

10.1038/s41586-023-06581-9 

ARTICLE TITLE

Rock organic carbon oxidation CO2 release offsets silicate weathering sink

 

Reactivate, repurpose, and rewire the brain

Peer-Reviewed Publication

COLD SPRING HARBOR LABORATORY

 

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INSIDE MOUSE MOTHERS’ HEARING CENTER, PARVALBUMIN INTERNEURONS (PVIN, MAGENTA) ARE SURROUNDED BY PERINEURONAL NETS (PNNS, GREEN). UPON HEARING CRYING PUPS, MICE WITH PVIN LACKING THE MECP2 PROTEIN (BOTTOM ROW) EXPERIENCE A DRAMATIC INCREASE IN PNN NUMBER AND INTENSITY, ESPECIALLY ON DAY ONE OF THE EXPERIMENT (MIDDLE COLUMN). THIS MANIFESTS AS PARENTAL NEGLECT.

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CREDIT: SHEA LAB/MICROSCOPY CORE FACILITY/COLD SPRING HARBOR LABORATORY

Developing brains become shaped by the sights, sounds, and experiences of early life. The brain’s circuits grow more stable as we age. However, some experiences later in life open up opportunities for these circuits to be rapidly rewired. New research from Cold Spring Harbor Laboratory Associate Professor Stephen Shea helps explain how the brain adapts during a critical period of adulthood: the time when new mothers learn to care for their young.

Shea’s work in mice shows how this learning process is disrupted when a small set of neurons lack a protein called MECP2. In humans, MECP2 dysfunction causes the rare neurodevelopmental disorder Rett syndrome. Shea’s findings could point researchers toward the brain circuits involved in Rett syndrome and potential treatment strategies. His research could also have implications for more common neurological conditions. Shea explains:

“It’s not lost on us that Rett syndrome patients have difficulty interpreting and producing language. Difficulties with communicating are widespread in autism spectrum disorders. One of the reasons we study Rett syndrome is that this may be a valuable model for other forms of autism.”

The Shea lab’s studies of MECP2 began about 10 years ago when he first learned that female mice with mutations in the Mecp2 gene are poor parents. When it comes to parenting, most mother mice are quick learners. But without adequate MECP2 protein, Shea says, “they neglect their children and don’t listen to their cries.”

Shea and his team tested how eliminating MECP2 from specific cells in the mouse brain affected maternal behavior. They found that for pup retrieval to be delayed, the protein only had to go missing from a small subset of cells in a sound-processing part of the brain. The crucial cells are known as parvalbumin (PV) neurons. To efficiently learn to retrieve their pups, mice need MECP2 in those specific brain cells when they first hear the young animals’ cries of distress.

Shea points out that PV neurons also play an essential role in brain circuits earlier in life. These cells normally dampen the signals of other neurons. But they release this inhibition during development, creating conditions that are favorable for change. Shea says:

“We find that some of the same mechanisms engaged in development are actually at play in adults. They can be reactivated and repurposed for rewiring the brain in a new life time point.”

In other words, it’s not just about development or adulthood. This research may provide clues about brain disorders that arise later on, like dementia and Alzheimer’s disease.

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JOURNAL

JNeurosci

DOI

10.1523/JNEUROSCI.0838-23.2023 

ARTICLE TITLE

Selective deletion of Methyl CpG binding protein 2 from parvalbumin interneurons in the auditory cortex delays the onset of maternal retrieval in mice

 

Food insecurity doubles rate of severe hypoglycaemia in adults with diabetes

Results are timely, given cost-of-living concerns, say researchers

Reports and Proceedings

DIABETOLOGIA

New research being presented at the Annual Meeting of the European Association for the Study of Diabetes (EASD) in Hamburg, Germany (2-6 Oct) has found that severe hypoglycaemia is more than twice as common among adults with diabetes who struggle to afford food.

Severe hypoglycaemia occurs when a person’s blood sugar levels fall to such an extent that it can cause loss of consciousness, seizures, coma and, in rare cases, death.

Severe hypoglycaemia is rare in people with diabetes unless they are taking insulin or secretagogues – two commonly prescribed classes of diabetes drug.  When people are taking insulin or secretagogues, severe hypoglycaemia occurs primarily as a side-effect of their medication.

The analysis of data from the US revealed that severe hypoglycaemia was 2.2 times more frequent in people who experienced food insecurity.

Food insecurity is known to influence health but there has been little real-world population-based research into its effect on rates of severe hypoglycaemia.

In the first investigation of its kind, Dr Alexandria Ratzki-Leewing, of Western University, London, Ontario, Canada, and colleagues conducted a secondary analysis of data from the US-wide iNPHORM study: a 12-month prospective panel survey of real-world hypoglycaemia risk.1 

Their analysis comprised 1,001 adults (49.6% male) with either type 1 diabetes (T1D, 16.1%) or type 2 diabetes (T2D) who were treated, for at least one year, with insulin and/or secretagogues. Participants were on average 51 years old and had a median diabetes duration of 12 years.

Questionnaires at baseline (spring 2020) and over 12 consecutive months captured data on respondents’ characteristics and frequency of severe hypoglycaemia. Based on the American Diabetes Association Standards of Care guidelines, severe hypoglycaemia was defined as a Level 3 low blood glucose concentration, regardless of blood glucose value, causing altered mental and/or physical status requiring professional or non-professional aid for recovery.At baseline, participants were asked this screening question, “Within the past 12 months, did you ever cut the size of your meals or skip meals because there was not enough food?”. Those who answered “yes” were classified as having experienced food insecurity.

Around one in five of the participants said they’d experienced food insecurity; rates were similar in T1D (18.6%) and T2D (20.4%). Among these individuals, over half experienced at least one Level 3 event in the past year.

The authors performed multivariable regression to determine if food insecurity caused higher rates of severe hypoglycaemia. Their analysis revealed that, after adjusting for potential confounders (age, annual gross household income, insurance coverage, living arrangements and diabetes type), those who had experienced food insecurity had just over twice as many severe hypoglycaemia events during the year studied as those not exposed to food insecurity.

Dr Ratzki-Leewing said: “This is the first community-based, prospective study to look at the impact of food insecurity on rates of Level 3 (severe) hypoglycaemia in adults in the US with diabetes on insulin and/or secretagogues.

“We showed that food insecurity is alarmingly common across this population and that it more than doubles the rate of severe hypoglycaemia.

“We recommend clinicians use our screening question and exercise vigilance when managing individuals with food insecurity prescribed insulin or secretagogues. Public health strategies to address food insecurity are also vital to prevent severe hypoglycaemia and its profound consequences.

“In the short term, severe hypoglycaemia can cause dangerous symptoms (such as seizures and coma) and accidents. It can also lead to impaired awareness of hypoglycaemia (the diminished ability to perceive falling blood glucose levels), which in turn, can increase the risk of future hypoglycaemia events.

“Long-term, severe hypoglycaemia has been associated with nerve and heart damage, as well as premature mortality. These effects have substantial direct and indirect economic costs.

“Ultimately, our study uncovers a key opportunity to reduce the burden of diabetes-related severe hypoglycaemia, while improving overall health. The results are timely given the rising cost of living, not only in the US but also globally.”

Note to editors 

This press release is based on poster abstract 750 at the annual meeting of the European Association for the Study of Diabetes (EASD). The material has been peer reviewed by the congress selection committee. There is no full paper at this stage. 

 

 

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ARTICLE PUBLICATION DATE

1-Oct-2023

COI STATEMENT

Dr Ratzki-Leewing has declared these conflicts of interest: Sanofi Global: grant, member advisory board, fees paid for presentations; Sanofi Canada: fees paid for presentations; Abbott: consultant, fees paid for presentations; Dexcom, consultant; Eli Lilly: consultant, fees paid for presentations; Novo Nordisk: consultant.

 

Massive low earth orbit communications satellites could disrupt astronomy

Peer-Reviewed Publication

IMPERIAL COLLEGE LONDON

 

IMAGE: 

TRAIL LEFT BY BLUEWALKER 3 OVER OBSERVATORIO ASTRONOMICO NACIONAL, SAN PEDRO MARTIR, MEXICO

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CREDIT: I. PLAUCHU-FRAYN

Observations of the BlueWalker 3 prototype satellite show it is one of the brightest objects in the night sky, outshining all but the brightest stars.

Astronomers have raised concerns that without mitigation, groups of large satellites could disrupt our ability to observe the stars from Earth and perform radio astronomy.

Several companies are planning ‘constellations’ of satellites – groups of potentially hundreds of satellites that can deliver mobile or broadband services anywhere in the world.

However, these satellites need to be in ‘low-Earth’ orbit and can be relatively large, so their potential to disrupt night-sky observations is a concern.

Now, an international team of scientists led by astronomers from the IAU Centre for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference (CPS) and including Imperial College London researchers, have published a paper in Nature assessing the detailed impact of the prototype BlueWalker 3 satellite on astronomy.

Dr Dave Clements, from the Department of Physics at Imperial, said: “The night sky is a unique laboratory that allows scientists to conduct experiments that cannot be done in terrestrial laboratories. Astronomical observations have provided insights into fundamental physics and other research at the boundaries of our knowledge and changed humanity’s view of our place in the cosmos. The pristine night sky is also an important part of humanity’s shared cultural heritage and should be protected for society at large and for future generations.”

Bright observations

BlueWalker 3 was launched into low-Earth orbit on 10 September 2022 by AST SpaceMobile, as a prototype for a planned constellation of over a hundred similar satellites intended for use in mobile communications. Observations taken within weeks of the launch showed that the satellite was among the brightest objects in the sky.

However, to better understand its effects on astronomy, the CPS initiated an international observing campaign. As part of this initiative, both professional and amateur observations were contributed from across the world, from sites in Chile, the US, Mexico, Aotearoa New Zealand, the Netherlands, and Morocco.

Documenting BlueWalker 3’s brightness over a period of 130 days, the newly released data show an abrupt increase coinciding with the complete unfolding of the antenna array, which at 64 square meters is the largest commercial antenna system ever deployed into low-Earth orbit.

A subset of the observations were also used to calculate the satellite’s trajectory over time. Comparing the predicted path with the observations collected, the authors were able to evaluate the accuracy of predictions and how this can change due to factors such as atmospheric drag.

Knowing the positions of the satellites is important, so astronomers can try to avoid them or at least know where they will be in the data. However, mitigating against the brightness is difficult beyond masking their position and losing data for that portion of the sky.

Radio interference

Besides visible observations, BlueWalker 3 could also interfere with radio astronomy, since it uses wavelengths close to those that radio telescopes observe in. While some telescopes are located within designated radio quiet zones, the restrictions in place to preserve these areas currently only apply to terrestrial transmitters, so they are not necessarily protected from satellite transmission.

Dr Mike Peel, co-lead of IAU CPS's Sathub and researcher in the Department of Physics at Imperial, said: "BlueWalker 3 actively transmits at radio frequencies that are close to bands reserved for radio astronomy, and existing observatory protections from radio interference may not be sufficient. Further research is therefore required to develop strategies for protecting existing and upcoming telescopes from the numerous satellites planned for launch over the next decade.”

The IAU and CPS partners recognize that the new satellite constellations have an important role in improving worldwide communications. However, their interference with astronomical observations could severely hamper progress in our understanding of the cosmos. Their deployment should therefore be conducted with due consideration of their side effects and with efforts made to minimize their impact on astronomy.

Observations of BlueWalker 3 will continue, with plans by astronomers to observe its thermal emission later this year. Astronomers will continue to discuss this topic at the upcoming IAU Symposium: Astronomy and Satellite Constellations: Pathways Forward in October.

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JOURNAL

Nature

DOI

10.1038/s41586-023-06672-7 

ARTICLE TITLE

Optical observations find high brightness of the BlueWalker 3 satellite

ARTICLE PUBLICATION DATE

2-Oct-2023

 

Graphene oxide reduces the toxicity of Alzheimer’s proteins

Peer-Reviewed Publication

CHALMERS UNIVERSITY OF TECHNOLOGY

 

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GRAPHENE OXIDE (ORANGE) CAN EFFECTIVELY ENTER YEAST CELLS AND REDUCE THE TOXICITY OF HARMFUL PROTEIN AGGREGATES (LIGHT GREY), BY PROMOTING DISASSEMBLY AND THEN DEGRADATION OF THE AGGREGATES. RESEARCHERS AT CHALMERS UNIVERSITY OF TECHNOLOGY HAVE DEVELOPED A YEAST MODEL, WHICH MIMICS THE NEURONS IN A HUMAN BRAIN AFFECTED BY ALZHEIMER’S DISEASE, TO DEMONSTRATE THIS. MOREOVER (NOT SHOWN BY THE ILLUSTRATION), GRAPHENE OXIDE TREATMENT CAN ALTER THE METABOLISM OF THE CELLS TO INCREASE THEIR CAPACITY TO COPE WITH STRESS.

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CREDIT: ILLUSTRATION: CHALMERS UNIVERSITY OF TECHNOLOGY / KATHARINA MERL

A probable early driver of Alzheimer's disease is the accumulation of molecules called amyloid peptides. These cause cell death, and are commonly found in the brains of Alzheimer’s patients. Researchers at Chalmers University of Technology, Sweden, have now shown that yeast cells that accumulate these misfolded amyloid peptides can recover after being treated with graphene oxide nanoflakes.

Alzheimer’s disease is an incurable brain disease, leading to dementia and death, that causes suffering for both the patients and their families. It is estimated that over 40 million people worldwide are living with the disease or a related form of dementia. According to Alzheimer’s News Today, the estimated global cost of these diseases is one percent of the global gross domestic product.

Misfolded amyloid-beta peptides, Aβ peptides, that accumulate and aggregate in the brain, are believed to be the underlying cause of Alzheimer’s disease. They trigger a series of harmful processes in the neurons (brain cells) – causing the loss of many vital cell functions or cell death, and thus a loss of brain function in the affected area. To date, there are no effective strategies to treat amyloid accumulation in the brain.

Researchers at Chalmers University of Technology have now shown that treatment with graphene oxide leads to reduced levels of aggregated amyloid peptides in a yeast cell model.

“This effect of graphene oxide has recently also been shown by other researchers, but not in yeast cells”, says Xin Chen, Researcher in Systems Biology at Chalmers and first author of the study. “Our study also explains the mechanism behind the effect. Graphene oxide affects the metabolism of the cells, in a way that increases their resistance to misfolded proteins and oxidative stress. This has not been previously reported.”

Investigating the mechanisms using baker’s yeast affected by Alzheimer’s disease
In Alzheimer’s disease, the amyloid aggregates exert their neurotoxic effects by causing various cellular metabolic disorders, such as stress in the endoplasmic reticulum – a major part of the cell, in which many of its proteins are produced. This can reduce cells’ ability to handle misfolded proteins, and consequently increase the accumulation of these proteins.

The aggregates also affect the function of the mitochondria, the cells’ powerhouses. Therefore, the neurons are exposed to increased oxidative stress (reactive molecules called oxygen radicals, which damage other molecules); something to which brain cells are particularly sensitive.

The Chalmers researchers have conducted the study by a combination of protein analysis (proteomics) and follow-up experiments. They have used baker's yeast, Saccharomyces cerevisiae, as an in vivo model for human cells. Both cell types have very similar systems for controlling protein quality. This yeast cell model was previously established by the research group to mimic human neurons affected by Alzheimer’s disease.

“The yeast cells in our model resemble neurons affected by the accumulation of amyloid-beta42, which is the form of amyloid peptide most prone to aggregate formation”, says Xin Chen. “These cells age faster than normal, show endoplasmic reticulum stress and mitochondrial dysfunction, and have elevated production of harmful reactive oxygen radicals.”

High hopes for graphene oxide nanoflakes
Graphene oxide nanoflakes are two-dimensional carbon nanomaterials with unique properties, including outstanding conductivity and high biocompatibility. They are used extensively in various research projects, including the development of cancer treatments, drug delivery systems and biosensors.

The nanoflakes are hydrophilic (water soluble) and interact well with biomolecules such as proteins. When graphene oxide enters living cells, it is able to interfere with the self-assembly processes of proteins.

“As a result, it can hinder the formation of protein aggregates and promote the disintegration of existing aggregates”, says Santosh Pandit, Researcher in Systems Biology at Chalmers and co-author of the study. “We believe that the nanoflakes act via two independent pathways to mitigate the toxic effects of amyloid-beta42 in the yeast cells.”

In one pathway, graphene oxide acts directly to prevent amyloid-beta42 accumulation. In the other, graphene oxide acts indirectly by a (currently unknown) mechanism, in which specific genes for stress response are activated. This increases the cell’s ability to handle misfolded proteins and oxidative stress.

How to treat Alzheimer’s patients is still a question for the future. However, according to the research group at Chalmers, graphene oxide holds great potential for future research in the field of neurodegenerative diseases. The research group has already been able to show that treatment with graphene oxide also reduces the toxic effects of protein aggregates specific to Huntington’s disease in a yeast model.

“The next step is to investigate whether it is possible to develop a drug delivery system based on graphene oxide for Alzheimer’s disease.” says Xin Chen. “We also want to test whether graphene oxide has beneficial effects in additional models of neurodegenerative diseases, such as Parkinson’s disease.”

More about: proteins and peptides
Proteins and peptides are fundamentally the same type of molecule and are made up of amino acids. Peptide molecules are smaller – typically containing less than 50 amino acids – and have a less complicated structure. Proteins and peptides can both become deformed if they fold in the wrong way during formation in the cell. When many amyloid-beta peptides accumulate in the brain, the aggregates are classified as proteins.

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JOURNAL

Advanced Functional Materials

DOI

10.1002/adfm.202304053 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Cells

ARTICLE TITLE

Graphene Oxide Attenuates Toxicity of Amyloid-β Aggregates in Yeast by Promoting Disassembly and Boosting Cellular Stress Response