UTHSC researchers awarded $3.69 million to study genetics mediating response to THC, the major psychoactive component in cannabis

Grant and Award Announcement

UNIVERSITY OF TENNESSEE HEALTH SCIENCE CENTER

 

IMAGE: MEGAN MULLIGAN, PHD, AND BOB MOORE, PHD view more 

CREDIT: COURTESY UTHSC

Researchers at the University of Tennessee Health Science Center have received a five-year grant totaling $3.69 million from the National Institute on Drug Abuse to study how genetic differences influence behavioral and physiological responses to tetrahydrocannabinol (THC), the major psychoactive component in cannabis.

Increased legalization for medical and/or recreational use and more favorable public perspectives has led to an increased use of cannabis. At the same time, the amount of THC in cannabis and derived products has dramatically increased. Recognizing a current lack of research on how high levels of THC impact health and behavior, principal investigators Bob Moore, PhD, professor in the Department of Pharmaceutical Sciences, and Megan Mulligan, PhD, associate professor in the Department of Genetics, Genomics & Informatics (GGI), are conducting research to identify genetic differences in bran effector signaling pathways that mediate individual differences in response to THC.

Their research aims to identify genetic variation in cannabinoid receptor signaling pathways mediating the response to delta-9-tetrahydrocannabinol (THC). The team will use a pharmacogenomic screen in a recombinant inbred mouse population with different genetic backgrounds to help identify the specific genes and molecular signaling pathways responsible for variation in physiological response following exposure to a high dose of THC, similar to what may be present in current high-potency cannabis and derived products.

“This is the first screen for initial response to THC in a genetic population of any animals,” said Dr. Mulligan. “We are positive that we will be able to identify gene variants in cannabinoid receptor signaling and metabolic pathways that underlie differences in THC response in rodents, and we expect these responses and pathways to be similar in humans.”

The team, which includes co-investigators Byron Jones, PhD, professor in the Department of Genetics, Genomics and Informatics, and Xusheng Wang, PhD, associate professor in the Department of Genetics, Genomics and Informatics, hopes to make a significant impact in better understanding the genetic regulation of cannabinoid receptor signaling in the brain. The study’s findings will be important for future investigations into the impact of THC over the lifespan and in other biological systems beyond the brain.

“If the scientific community sees us having success in identifying how genetics regulates responses to THC, then this approach could be used as a screen to understand whole system effects of new drug candidates,” Dr. Moore said. “I hope it will bring a new approach to potentially identify unwanted side-effects of new therapies and guide medicinal chemists in the drug development effort.”

 

Archaeology: Mummification balm ingredients reflect Ancient Egyptian noblewoman’s high status

Peer-Reviewed Publication

SCIENTIFIC REPORTS

The ingredients of balms used in the mummification of ancient Egyptian noblewoman named Senetnay — whose remains were excavated by Howard Carter in 1900 CE — are described in a study published in Scientific Reports. The origins and complexity of the balms provide clues as to the high status of the individual.

Previous research has identified that Senetnay lived in Egypt around 1,450 BCE, was wet nurse to the Pharaoh Amenhotep II during his infancy, and bore the title “Ornament of the King”. After her death, her mummified organs were stored in four jars in a royal tomb in the Valley of the Kings.

Barbara Huber, Nicole Boivin and colleagues analysed the substances found within six balm samples from two jars that were used to store Senetnay’s lungs and liver. They report that both balms contained beeswax, plant oils, animal fats, the naturally occurring petroleum product bitumen, and resins from the family of coniferous trees that includes pines and larches. The authors also identified the presence of the compounds coumarin and benzoic acid within samples from both jars. Coumarin has a vanilla-like scent and is found in a wide range of plants including cinnamons and pea plants, while benzoic acid occurs in fragrant resins and gums obtained from several types of trees and shrubs.

While the composition of the balms from both jars appeared to be very similar, the authors identified two substances that were only present in the jar used to store Senetnay’s lungs. These were a compound known as larixol — which is found in larch resin — and another fragrant resin that they suggest is either dammar, which is obtained from dipterocarp trees that grow in India and southeast Asia, or a resin obtained from Pistacia trees — a group that is part of the cashew family. The presence of these ingredients in only one of the two jars could indicate that different balms were used to preserve different organs.

Based on a review of previous analyses of mummification balms, the authors report that the composition of those applied to Senetnay’s organs was relatively complex compared to others from the same period. Additionally, they suggest that most of the potential ingredients would likely have been imported from locations outside Egypt. The authors propose that the complexity of the balms and use of imported ingredients used in the mummification of Senetnay reflect her high social status and indicate that she was a highly valued member of the Pharaoh’s entourage.

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Article details

Biomolecular characterization of 3500-year-old ancient Egyptian mummification balms from the Valley of the Kings

DOI: 10.1038/s41598-023-39393-y

Please link to the article in online versions of your report (the URL will go live after the embargo ends): https://www.nature.com/articles/s41598-023-39393-y.

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JOURNAL

Scientific Reports

DOI

10.1038/s41598-023-39393-y 

ARTICLE TITLE

Biomolecular characterization of 3500-year-old ancient Egyptian mummification balms from the Valley of the Kings

 

Biodiversity: Gardens could be an Eden for vulnerable plants

Peer-Reviewed Publication

SCIENTIFIC REPORTS

Conservation gardening — the practice of planting declining native species in urban and rural green spaces — could help to address the increasing issue of plant biodiversity losses in Germany, reports a paper published in Scientific Reports. The authors find that on average across Germany, 41 percent of plants (988 species) on the Red List of Threatened Species would suit conservation gardening, and that this approach could be expanded to boost biodiversity in other countries.  

Although there is increasing public awareness of the importance of plant biodiversity in green spaces, there is a continuing strong preference for tidy gardens with ornamental plants. While local plants may also be grown, gardens tend to show low levels of diversity and plant choices are heavily influenced by availability and personal experience.

Ingmar Staude and colleagues obtained the most recent Red List data for endangered and vulnerable plants across all 16 German states. The authors included extinct in the wild species as conservation gardens can provide new habitats for these plants. They then collated data from the NaturaDB database to categorise which of these threatened species were suitable for gardening. Finally, they used data from plant and seed producer websites to assess the commercial availability of listed species. Based on this data, the authors created a web app to provide lists of plants for gardeners and local authorities so that they could easily select suitable plants for conservation gardening. 

The number of Red List species ranged from 515 to 1,123 in different German states, with a median of 41 percent (988 species) of these being suitable for conservation gardening. In Hamburg, 53 percent (352 of 670) of threatened species could be grown, while in Bavaria only 29 percent (321 of 1,123 species) were suitable. Of the total suitable species, 650 (66 percent) were commercially available for purchase. Additionally, the authors calculate that 45 percent of conservation gardening-suitable threatened plants prefer dry soils, compared to 27 percent of conventional garden plants.

These findings indicate that many threatened species are both suitable for gardening and are commercially available. The authors also suggest that, overall, these plants may also be more tolerant of drier conditions. Together, this presents a new approach to reducing biodiversity loss.

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JOURNAL

Scientific Reports

DOI

10.1038/s41598-023-39432-8 

ARTICLE TITLE

Putting conservation gardening into practice

 

Evolutionary imbalance explains global plant invasions

Plant species from certain geographic regions are more successful in spreading outside their native ranges than others – but why?

Peer-Reviewed Publication

UNIVERSITY OF KONSTANZ

Human activities – for example, global trade and travel – are driving the spread of plants beyond their natural ranges and around the globe. However, not all species benefit equally from these movements; only some are able to successfully establish populations (i.e. naturalize) in new locations. Data on the global distribution of alien plants reveals that plants originating from certain geographic regions are more successful at naturalizing than others.

The evolutionary imbalance hypothesis (EIH) offers possible explanations for this phenomenon, but has not yet been verified on a global scale. An international research team led by biologist Mark van Kleunen from the University of Konstanz has now succeeded in confirming key predictions of this hypothesis using extensive global data. In their study in Nature Ecology & Evolution, the researchers also discover intriguing similarities in the origins of plants that successfully establish populations outside their natural ranges and those that humans have selected for cultivation and economic use – suggesting that biogeographic factors influence biological and cultural systems in similar ways.

Dating back to Darwin
At its essence, the ideas of the EIH date back to Charles Darwin. "Darwin proposed that geographic barriers divide the Earth's ecosystems into various evolutionary arenas," says Trevor Fristoe, first author of the study and ecologist at the Department of Biology at the University of Konstanz. Within each of these arenas, the organisms inhabiting them would be exposed to unique geographic and ecological conditions that influence the intensity of natural selection. "The result is differences in the absolute fitness for species originating from different regions – evolutionary imbalances –, and these differences have consequences for which species are more likely to successfully establish in new areas when barriers are removed," Fristoe continues.

Based on these ideas, the EIH makes predictions about the characteristics of global regions that drive the evolution of particularly successful aliens. For example, larger regions should support larger populations and higher genetic diversity to allow for more efficient natural selection. Species-rich regions should serve as intense proving grounds where species must evolve to persist in the presence of a wide variety of competitors and enemies.

The current study tested these predictions on a global scale. For this, the researchers used an unprecedented data set that included the native and alien distributions of over 99 percent of all known seed plants – over 330,000 species. Consistent with the EIH, they demonstrated that plants originating from vast, species-rich regions are among the most successful alien plants. "Thus, our study confirms two key predictions of the EIH on a global scale," emphasizes Mark van Kleunen, head of the international research team.

Economic plants show a similar pattern
What is more, the data revealed a previously unrecognized link between evolutionary imbalance and the economic use of plants by humans: the native range characteristics that select for successful invaders are also associated with the species that we grow for economic use. “All else equal, humans should chose to cultivate plants with a higher capacity for survival, growth, and proliferation. This has resulted in feedbacks where species with high potential as invaders are also more likely to be intentionally moved around the globe. Our study demonstrates these intriguing links and suggests how evolutionary imbalances in biological and cultural systems may even interact," says van Kleunen.

 

Key facts:

• EMBARGOED UNTIL THURSDAY, 31 AUGUST 2023, 17:00 CEST (16:00 LONDON TIME, 11:00 U.S. EASTERN TIME)
• Original publication: T. S. Fristoe et al. (2023) Evolutionary imbalance, climate and human history jointly shape the global biogeography of alien plants. Nature Ecology & Evolution; doi: 10.1038/s41559-023-02172-z
• International research team led by biologists from Konstanz confirms key predictions of the "evolutionary imbalance hypothesis" on the naturalization success of plants from specific native regions.
• The study takes into account distribution data from over 330,000 plants – almost all (99.5%) known seed plants.
• Funding: German Research Foundation (DFG)

 

 

Note to editors:
You can download images here:

Link: https://www.uni-konstanz.de/fileadmin/pi/fileserver/2023/evolutionaeres_ungleichgewicht_vetch.jpg

Caption: Alien individuals of the tufted vetch (Vicia cracca) in interior Alaska. This species has a native distribution spanning much of Eurasia and has successfully established alien populations on every continent but Antarctica.

Image: © Trevor Fristoe

 

Link: https://www.uni-konstanz.de/fileadmin/pi/fileserver/2023/evolutionaeres_ungleichgewicht_goldenrod.jpg

Caption: Among the most invasive plants in Europe (shown invading a meadow in Germany), the Canadian goldenrod (Solidago Canadensis) has a native range that stretches from Alaska, across Canada, and all the way into tropical Mexico.

Image: © Jonas Bleilevens & Trevor Fristoe

 

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JOURNAL

Nature Ecology & Evolution

DOI

10.1038/s41559-023-02172-z 

ARTICLE TITLE

Evolutionary imbalance, climate and human history jointly shape the global biogeography of alien plants

Coastal fisheries show surprising resilience to marine heat waves

Rutgers-led study finds that in the years following marine heat waves, effects on fish communities were often minimal

Peer-Reviewed Publication

RUTGERS UNIVERSITY

Rutgers-led research found that marine heat waves – prolonged periods of unusually warm ocean temperatures – haven’t had a lasting effect on the fish communities that feed most of the world.

The finding is in stark contrast to the devastating effects seen on other marine ecosystems cataloged by scientists after similar periods of warming, including widespread coral bleaching and harmful algal blooms.

“There is an emerging sense that the oceans do have some resilience, and while they are changing in response to climate change, we don’t see evidence that marine heat waves are wiping out fisheries,” said Alexa Fredston, the lead author of the study who conducted the research as a postdoctoral associate in the Global Change Research Group, part of the Department of Ecology, Evolution and Natural Resources in the Rutgers School of Environmental and Biological Sciences (SEBS.)

The study, published in Nature, assessed effects on commercially important fish such as flounder, pollock and rockfish based on data extracted from long-running scientific trawl surveys – conducted by towing a net along the seafloor – of continental shelf ecosystems in North America and Europe between 1993 and 2019. The analysis included 248 marine heat waves with extreme sea bottom temperatures during this period. The researchers were surprised to find that marine heat waves in general don’t show major adverse effects on regional fish communities.

Although declines in biomass did occur after some marine heat waves, the researchers said these cases were the exception, not the rule. Overall, they found that the effects of marine heat waves aren’t distinguishable from the natural variability in these ecosystems.

“The oceans are highly variable, and fish populations vary quite a lot,” said Fredston, now an assistant professor of ocean sciences at University of California, Santa Cruz. “Marine heat waves can drive local change, but there have been hundreds of marine heat waves with no lasting impacts.”

In addition to assessing the impact on the total quantity of organisms in a given area, known as biomass, the researchers examined whether marine heat waves were causing changes in the variety of fish species composing fish communities. For example, evidence might show the loss of species associated with cold water and an increase in species associated with warm water, a phenomenon known as tropicalization.

The findings suggest fish may be able to find safe havens by moving to areas with cooler water during marine heat waves, which the researchers defined as periods of more than five days with extreme sea bottom temperatures for that region and season.

The data included some notable examples of marine heat waves that did have profound impacts, such as the 2014-2016 marine heat wave in the Northeast Pacific known as “the Blob,” one of the largest on record.

While “the Blob” led to a 22 percent loss of biomass in the Gulf of Alaska, a 2012 marine heat wave in the Northwest Atlantic led to a 70 percent biomass gain. The authors also noted that these weren’t large changes compared to natural variability in biomass, and similar effects weren’t seen after most other marine heat waves.

“We found that these negative impacts are unpredictable and that other heat waves had no strong impacts,” said Malin Pinsky, an associate professor in the Department of Ecology, Evolution and Natural Resources and director of the Global Change Research Group at SEBS and a co-author of the study. “This means that each heat wave that hits is like rolling the dice: Will it be a bad one or not? We don't know until it happens.”

Other Rutgers researchers who participated in the study include Zoë Kitchel, a doctoral student, and Aurore Maureaud, a postdoctoral associate, both with the Department of Ecology, Evolution and Natural Resources at SEBS.

Researchers from other institutions participated in the study, including the University of British Columbia, the University of Bern in Switzerland, the National Oceanic and Atmospheric Administration, the French Research Institute for Exploitation of the Sea, the University of Montpellier in France, the University of Tromsø in Norway and Fisheries and Oceans Canada.

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JOURNAL

Nature

DOI

10.1038/s41586-023-06449-y 

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Marine heatwaves are not a dominant driver of change in demersal fishes

 

Using evidence from last Ice Age, scientists predict effects of rising seas on coastal habitats

Extent of future warming will dictate impacts, according to research

Peer-Reviewed Publication

RUTGERS UNIVERSITY

The rapid sea level rise and resulting retreat of coastal habitat seen at the end of the last Ice Age could repeat itself if global average temperatures rise beyond certain levels, according to an analysis by an international team of scientists from more than a dozen institutions, including Rutgers.

In a study published in Nature, scientists reported how ancient coastal habitats adapted as the last glacial period ended more than 10,000 years ago and projected how they are likely to change with this century’s predicted sea level rise. They conducted their analysis by examining the ocean sediments of ancient shorelines from a time when oceans rose rapidly, mainly because of melting ice sheets in the Northern Hemisphere. This examination allowed them to infer how ancient coastal habitats changed and formed the basis of improved predictions about the present.

“Every ton of carbon dioxide humankind emits turns up the global thermostat, which in turn increases the pace of global sea level rise,” said Robert Kopp, a Distinguished Professor in the Department of Earth and Planetary Sciences in the Rutgers School of Arts and Sciences and an author of the study. “The faster the oceans rise, the greater the threat to tidal marshes, mangroves and coral reefs around the world. For example, in our analysis, most tidal marshes are likely to be able to keep up with sea level rise under 1.5 degrees Celsius [2.7 degrees Fahrenheit] of warming, but two-thirds are unlikely to be able to keep up with 2 degrees Celsius [3.6 degrees Fahrenheit] of warming."

The temperature ranges mentioned in the study are significant because they relate directly to the Paris Agreement, an international treaty on climate change adopted in 2015, said Kopp, who is also the director of the Megalopolitan Coastal Transformation Hub and co-director of the University Office of Climate Action. The goal of the Paris treaty is to substantially reduce carbon emissions worldwide to limit the global temperature increase in this century to 2 degrees Celsius above preindustrial levels while pursuing efforts to limit the increase even further to 1.5 degrees Celsius.

The study predicted higher global temperatures will provoke sea level rises that will lead to instability and profound changes to coastal ecosystems, including tidal marshes, mangrove forests, coral reefs and coral islands.

Tidal marshes – low-lying areas flooded and drained by tidal salt water – protect many of the world’s coastlines. They sequester pollutants, absorb carbon dioxide and protect nearby communities from storm surge and flooding. They are common along the Atlantic shores of North America. Large expanses of tidal marshes line New Jersey’s coast.

“This new paper provides evidence from geological history that, without mitigation and under current projections, tidal marshes will not have the capacity to adjust,” said Judith Weis, a Professor Emerita of Biological Sciences at Rutgers–Newark who isn’t an author of the study but is an expert on tidal marshes. “For many tidal marshes in New Jersey, this is not a prediction but a description of the present situation, in which sea level is rising faster than the marshes can increase their elevation. This makes it even more vital to reduce climate change as rapidly as possible.”

Tidal marshes and mangrove forests adapt to rising seas by accumulating sediment and moving slowly inland.

“Mangroves and tidal marshes act as a buffer between the ocean and the land – they absorb the impact of wave action, prevent erosion and are crucial for biodiversity of fisheries and coastal plants,” said Neil Saintilan, the paper’s lead author and a professor at Macquarie University in Sydney, Australia. “When the plants become water-logged due to higher sea levels, they start to flounder.”

Under worst-case scenarios, these coastal habitats, buffeted by rising sea levels, will shrink and, in some cases, wash away, as they have in the distant past, according to the study.

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JOURNAL

Nature

DOI

10.1038/s41586-023-06448-z 

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Widespread retreat of coastal habitat likely at warming levels above 1.5C

 

Arctic soil methane consumption may be larger than previously thought and increases in a drier climate

Peer-Reviewed Publication

UNIVERSITY OF EASTERN FINLAND

 

IMAGE: AUTOMATED CHAMBER MEASUREMENT SET-UP AT TRAIL VALLEY CREEK, WESTERN CANADIAN ARCTIC. view more 

CREDIT: CAROLINA VOIGT.

Arctic wetlands are known emitters of the strong greenhouse gas methane (CH4). Well-drained soils on the other hand remove methane from the atmosphere. In the Arctic and boreal biomes, well drained upland soils with a high potential for atmospheric methane consumption cover more than 80% of the land area. Despite the large upland coverage and their potential importance for methane uptake, the underlying mechanisms, environmental controls and even the magnitude of Arctic soil methane uptake are poorly understood.

A recent study led by researchers from the University of Eastern Finland and the University of Montreal finds that Arctic soil methane uptake may be larger than previously thought, and that methane uptake increases under dry conditions and with availability of labile carbon substrates. The article was published in Nature Climate Change – one of the top-level journals in natural sciences.

The study was primarily conducted at Trail Valley Creek, a tundra site in the Western Canadian Arctic. The authors used a unique experimental set-up consisting of 18 automated chambers for continuous measurements of methane fluxes. No other automated chamber system exists this far North in the Canadian Arctic, and only few exist above the Arctic circle globally, most of which are installed at methane-emitting sites.

The high-resolution measurements of methane uptake (more than 40 000 flux measurements) revealed previously unknown diel and seasonal dynamics in methane uptake: while methane uptake in early and peak summer was largest during the afternoons, coinciding with maximum soil temperature, methane uptake during late summer peaked during the night. Underlying biogeochemical mechanisms are complex, but the study shows that the strongest methane uptake coincided with peaks of ecosystem carbon dioxide (CO2) respiration. Complementing flux measurements at Trail Valley Creek with measurements at other sites spread across the Arctic in Canada and Finland showed that the availability of labile carbon substrates and nutrients may promote methane consumption in Arctic soils.  

On a larger scale, these findings are highly relevant for estimating the current Arctic methane budget, and for predicting the future response of Arctic soil methane uptake to a changing climate. According to the study, high-latitude warming itself, occurring up to four times faster in the Arctic than the rest of the world, will promote atmospheric methane uptake to a lesser extent than the associated large-scale drying.

The study was carried out by an international team of researchers from Canada and Finland, and collaborators from the United States and Germany. The main funding sources for the study were the Academy of Finland, the Canada Foundation for Innovation project Changing Arctic Network, ArcticNet, and the Canada Research Chair and NSERC Discovery Grants programs. Field work was supported by Metsähallitus and the Aurora Research Institute.

CAPTION

Conditions during field work at Trail Valley Creek research camp, Western Canadian Arctic. Photo taken during June, 2021.

Upland tundra landscape during autumn near Inuvik, Western Canadian Arctic.

Upland tundra landscape near Inuvik, Western Canadian Arctic.

CREDIT

Carolina Voigt.

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JOURNAL

Nature Climate Change

DOI

10.1038/s41558-023-01785-3 

ARTICLE TITLE

Arctic soil methane sink increases with drier conditions and higher ecosystem respiration.

 

Evolving chemical system changes its environment

Synthetic replicators show first signs of Darwinian evolution

Peer-Reviewed Publication

UNIVERSITY OF GRONINGEN

 

IMAGE: A POPULATION OF THE TWO MUTANTS CAN UNDERGO DARWINIAN EVOLUTION THROUGH MUTATION AND SELECTION, ADAPTING TO A CHANGE IN THE ENVIRONMENT CAUSED BY THE REPLICATORS THEMSELVES. THE TWO REPLICATOR MUTANTS, A SIX-RING AND A THREE-RING, COMPETE FOR A COMMON BUILDING BLOCK. BOTH REPLICATORS CAN PRODUCE SINGLET OXYGEN WHEN IRRADIATED WITH LIGHT, CAUSING A CHANGE IN THE OXIDATION STATE OF THEIR ENVIRONMENT. AT A HIGH OXIDATION STATE, THE HEXAMER CAN NO LONGER REPLICATE EFFICIENTLY, WHILE TRIMER REPLICATION STALLS AT A LOW OXIDATION STATE. THESE EFFECTS RESULT IN THE ADAPTATION OF THE REPLICATOR POPULATION TO A CHANGE IN OXIDATION LEVEL, WHICH, IN TURN, DEPENDS ON THE LIGHT INTENSITY. THIS BEHAVIOUR SHOWS THAT NATURAL SELECTION CAN ALSO ACT OUTSIDE BIOLOGY ON SYSTEMS OF MAN-MADE MOLECULES. view more 

CREDIT: OTTO LAB, UNIVERSITY OF GRONINGEN

A chemical system of synthetic replicators showing the first signs of Darwinian evolution: two different replicators compete for a common building block, and which one wins depends on the environment. As the replicators can also change their environment, ecological-evolutionary dynamics ensue. This finding shows that Darwinian principles extend beyond biology to synthetic systems. These results, which may be used to develop new catalysts, were published by chemists from the University of Groningen (the Netherlands) in the journal Nature Chemistry on 31 August.

What is life? This question has puzzled scientists for ages. Sijbren Otto, Professor of Systems Chemistry at the University of Groningen, addresses the question by attempting to synthesize a simple form of life from scratch. He has experimented extensively with a system of monomers, that react with each other to produce rings. These, in turn, assemble into fibres. In this process, the rings are replicated and the fibres grow and divide. Previous work showed that the fibres can also perform catalysis under the influence of light, accelerating the formation of the molecules they grow from: a primitive form of metabolism.

Adapting

In their recent study, Otto and his team focused on another key aspect of life: Darwinian evolution. They studied fibres made from self-replicating rings of two different sizes: 3-rings and 6-rings. ‘All rings assemble from the same monomer, for which they compete’, explains Otto. ‘We then placed these systems in a flow cell while adding a solution of monomers at a constant rate. At the same time, we were removing an equal amount of fluid from the cell.’ The scientists then watched the fibres reproduce and evolve by changing their ring size.

Replicators will only survive if they can replicate faster than the rate at which they are removed by the outflow. In this system, the two replicators exhibited different growth rates in different environments: the 3-rings grew fastest if they were in a highly oxidized environment, while the 6-rings won the competition if the environment was less oxidizing. Otto: ‘We saw that the replicators could mutate into a different ring size when the oxidation state of the environment was changed. Thus, these replicators appear to be capable of adapting to a changing environment.’

Dynamics

The researchers further developed this system by giving the replicators the ability to alter the oxidation state of their environment by themselves in response to light. Weak light conditions caused only little oxidation, allowing the 6-ring replicators to dominate. However, under strong light, the 6-ring replicators increased the oxidation level, thereby poisoning its own environment. This reduced the ability of this replicator to grow, and the mutant 3-ring fibres now took over.

‘Our system is very simple, yet it shows some of the dynamics normally only seen in living systems’, says Otto. ‘We showed how a kind of natural selection determines which type of replicator dominates, and also that these replicators can change their own environment, which, in turn, influences replicator evolution. Such eco-evolutionary dynamics are well known in biology, and it is now clear that they also extend to (our) synthetic system.’ But Otto does not yet call the system alive, as this would require additional features, such as the compartmentalization of the replicators in a cell-like structure.

Biology

‘However, it is interesting that Darwinian principles, which are the cornerstone of biology, can also be introduced into our synthetic system. We have replication, a metabolism, and now also a limited kind of Darwinian evolution’, concludes Otto. ‘This is still very rudimentary, but we are keen to see if we can push our systems to become ever more life-like.’ Apart from uncovering how chemical systems can transition into living ones, such systems could also harness the inventive power of Darwinian evolution to develop novel catalysts or materials, for example.

Reference: Kai Liu, Alex Blokhuis, Chris van Ewijk, Armin Kiani, Juntian Wu, Wouter H. Roos and Sijbren Otto: Light-driven eco-evolutionary dynamics in a synthetic replicator system. Nature Chemistry, 31 August 2023

A system of two self-replicating molecules can change the oxidation state of their environment in response to light and depending on light intensity. Intense light leads to a high oxidation state which causes an adaptation of the replicator distribution to favor the 3-ring replicator by mutation and selection. A similar adaptation occurs at a lower light intensity, now favouring the competing 6-ring replicator.

CREDIT

Otto Lab, University of Groningen

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JOURNAL

Nature Chemistry

DOI

10.1038/s41557-023-01301-2 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Light-driven eco-evolutionary dynamics in a synthetic replicator system

Single-dose psilocybin treatment for major depressive disorder

JAMA

Peer-Reviewed Publication

JAMA NETWORK

About The Study: In a randomized clinical trial with 104 participants, psilocybin treatment was associated with a clinically significant sustained reduction in depressive symptoms and functional disability, without serious adverse events. These findings add to increasing evidence that psilocybin—when administered with psychological support—may hold promise as a novel intervention for major depressive disorder.

Authors: Charles L. Raison, M.D., of Usona Institute in Fitchburg, Wisconsin, is the corresponding author.

link https://media.jamanetwork.com/

(doi:10.1001/jama.2023.14530)

Editor’s Note: 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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JOURNAL

JAMA