'Lost' immune cells partly to blame for reduced vaccine response in older people

Consequences of cells not being in the right place at the right time lead to immune system defects.

Peer-Reviewed Publication

BABRAHAM INSTITUTE

 

IMAGE: MICROSCOPY IMAGE OF A GERMINAL CENTRE STRUCTURE WHICH IS ALTERED IN AGED MICE. view more 

CREDIT: BABRAHAM INSTITUTE

Understanding the ways our immune response changes as we age holds the key to designing better vaccines and boosting protection for people most at risk. Research published by Dr Michelle Linterman and her group today in Nature Immunology has explained that the organisation of the germinal centre, which is vital to the generation of longer-lived protection following vaccination, is altered in ageing. By demonstrating that these age-related changes can be reversed in mice, the research sets the foundation for interventions that bolster an effective vaccine response.

After a vaccination our immune system reacts by creating specialised structures called germinal centres that produce the immune cells (B cells) that provide long-term protection through the production of antibodies. Due to an age-dependent impairment in antibody production, older people have lower levels of protection from vaccination which also wanes more quickly compared to younger people. Protection by vaccination is essential to protect older people who become more susceptible to infections with age. Therefore, understanding how the age-related decline of the immune system can be reversed or mitigated is an important part of securing better health in later years.

The correct function of the germinal centre response requires the coordination of cellular interactions across time and space. Germinal centres are made up of two distinct regions – the light zone and dark zone, with some cells located in specific areas, and others which move between the zones. B cells are shaped by their interactions in first the dark zone and then in the light zone.

Through a combination of mouse research, computer modelling and analysis of human vaccination data, the Linterman lab research team were able to show that changes to key interactors of B cells in the light zone of the germinal centre, T follicular helper cells, and also to light-zone specific cells called follicular dendritic cells (FDCs), were at the heart of the diminished vaccination response.

Dr Michelle Linterman, a group leader in the Institute’s Immunology programme, explains “In this study we looked at what was happening to different cell types in the germinal centre, particularly the structure and organisation of the germinal centre across its two functionally distinct zones, to try and understand what causes the reduced germinal centre response with age.

"What we found is that the T follicular helper cells aren’t where they should be and as a result, antibody-producing cells lose essential selection cues. Surprisingly we also uncovered an unknown role for T follicular helper cells in supporting the expansion of follicular dendritic cells in the light zone after vaccination."

The team used 3D computer modelling to simulate the loss of Tfh cells from the light zone and a reduced FDC network, which recapitulate their findings and strengthened their hypothesis that these two factors were enough to be responsible for a suboptimal germinal centre response in aged mice.

Having identified the dependencies between the cell types, the researchers used genetically modified mice to control the location of Tfh cells in the germinal centre, demonstrating that the defective FDC response was caused by loss of Tfh from the light zone. Importantly, they were also able to correct the defective FDC response and boost the germinal centre response in aged mice by providing T cells that could correctly localise to the light zone.  

The team also utilised data from human vaccination studies and found similar age-dependent changes in mice and humans.

“These findings give us a more complete picture of what the effects of age are on the germinal centre and vital insight into how we might address these in terms of developing effective strategies for enhancing vaccine response in older people” concluded Dr Linterman.

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JOURNAL

Nature Immunology

DOI

10.1038/s41590-023-01519-9 

METHOD OF RESEARCH

Experimental study

ARTICLE TITLE

Spatial dysregulation of T follicular helper cells impairs vaccine responses in aging

ARTICLE PUBLICATION DATE

22-May-2023

Corals mark friendly algae for ingestion—revealing possible conservation target

Understanding how corals tell which algae to take up is an important step in gathering information that will help experts mitigate coral bleaching

Peer-Reviewed Publication

CARNEGIE INSTITUTION FOR SCIENCE

 

IMAGE: THE SOFT, PULSING XENIA CORAL GROWING IN CARNEGIE’S CORAL RESEARCH FACILITY IN BALTIMORE. view more 

CREDIT: PHOTOGRAPH BY ED HIRSCHMUGL AND NAVID MARVI, COURTESY OF THE CARNEGIE INSTITUTION FOR SCIENCE.

Baltimore, MD—New research led by Carnegie’s Yixian Zhen and Minjie Hu reveals how coral cells tag friendly algae before ingesting them, initiating a mutually beneficial relationship. This information could guide next-level coral conservation efforts.  

Their work is published in Nature Microbiology. 

Corals are marine invertebrates that build large exoskeletons 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 called dinoflagellates 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.

Coral reefs have great ecological, economic, and aesthetic value. Many communities depend on them for food and tourism. Despite this, human activity is putting strain on these fragile communities. Warming oceans, pollution, and acidification all affect this symbiotic relationship.

“Many corals are particularly sensitive to elevated temperatures,” explained Hu. “As oceans heat up, they lose algae, starve due to the lack of nutrients, and die off, a phenomenon called bleaching, because it leaves the coral skeleton looking ghostly white."

For several years, teams of Carnegie researchers, including Zheng and Hu, have been elucidating the molecular and cellular mechanisms underpinning coral-algae symbiosis. Understanding these processes could inform strategies to prevent bleaching and promote coral resilience. 

In this new study, the researchers—including Carnegie’s Yun Bai and Xiaobin Zheng—deployed sophisticated bioinformatic and molecular biology tools to reveal the early steps of symbiosis, during which the algae are taken up into the coral. They found a molecule called LePin, which the coral secretes. It is concentrated in the mouth of corals, where it may bind to incoming algae, marking them for uptake into coral cells. 

“Understanding how corals tell which algae to take up is an important step in gathering information that will help us mitigate coral bleaching,” Zheng said. 

LePin is evolutionarily conserved among soft corals, stony corals, and anemones that perform symbiosis with algae, which means that it could be a good target for efforts to genetically engineer at-risk corals to increase their hardiness in the face of temperature increases. 

“Gaining a deeper understanding of LePin could enable us to differentiate how some species of coral are better able to identify and take up heat-resistant algae than others,” Zheng explained. “Once isolated, the LePin sequences that are capable of identifying hardier and more heat-resistant algae could be transplanted into vulnerable coral populations to reduce bleaching events.”

In 2020, Zheng was selected as one of 15 scientists awarded a highly competitive grant from the Gordon and Betty Moore Foundation to support research on symbiosis in aquatic systems. She has been building on Carnegie’s long-standing tradition of model organism development to understand the molecular mechanisms of endosymbiosis in coral. These efforts illustrate how modern biomedical techniques can be applied to solving urgent ecological challenges—a research priority for Carnegie.  

An illustration showing how LePin tags (shown in blue) are secreted from the coral cell and used to mark algae for uptake.

CREDIT

Artwork by Navid Marvi courtesy of the Carnegie Institution for Science.

__________________

This work was supported by the Gordon and Betty Moore Foundation.

The Carnegie Institution for Science (carnegiescience.edu) is a private, nonprofit organization headquartered in Washington, D.C., with three research divisions on both coasts. Since its founding in 1902, the Carnegie Institution has been a pioneering force in basic scientific research. Carnegie scientists are leaders in the life and environmental sciences, Earth and planetary science, and astronomy and astrophysics.

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JOURNAL

Nature Microbiology

DOI

10.1038/s41564-023-01397-9 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

'Coral–algal endosymbiosis characterized using RNAi and single-cell RNA-seq

ARTICLE PUBLICATION DATE

22-May-2023

WVU researchers see need to strengthen mental health programs for first responders

Peer-Reviewed Publication

WEST VIRGINIA UNIVERSITY

 

IMAGE: MENTAL HEALTH PROGRAMS TO COMBAT INCREASING STRESS AMONG FIRST RESPONDERS NEED STRENGTHENED, ACCORDING TO WEST VIRGINIA UNIVERSITY RESEARCH. view more 

CREDIT: WVU ILLUSTRATION/AIRA BURKHART

Controlling traumatic situations is synonymous with the daily duties of first responders, yet many mental health programs to combat the increasing stress they encounter are lacking. That’s why West Virginia University researchers are identifying steps policymakers and community members can take to aid front-line workers.

“With elevated risk for suicide and other mental health issues among first responders, we have a significant public health problem,” said Michael Fisher, assistant professor in the WVU School of Public Health Department of Health Policy Management and Leadership, who led a study analyzing mental health and first responders in one state.

“These issues rarely make front-page news and may not always garner widespread support and financial resources. This situation began to change amid the COVID-19 pandemic, but policymakers and the public need to be informed about these issues so that appropriate policies, programs and resources can ensue.”

Results of the study led researchers to offer five recommendations: link first responders with culturally competent clinicians; establish one or more centralized organizations to coordinate policy and programming activities; examine models of regional collaboration; expand mental health policy and program research and evaluation efforts; and pass legislation to advance mental health policy and program coordination and implementation.

Two federal proposals — the Fighting Post-Traumatic Stress Disorder Act and the Helping Emergency Responders Overcome Act — haven’t gained traction. However, measures on state and local levels are showing promise and those are the ones Fisher and his team want to hold up as examples.

“I wanted to investigate some of those activities,” Fisher said. “There is a dynamic landscape of emerging approaches to mental health prevention and treatment for first responders, but there is still so much to be learned, both about the effectiveness of specific approaches and about the landscape of programs available or, in some cases, not available.”

Fisher chose to focus on Ohio for the study because it is one of the few states where extensive support measures for first responders have been enacted. In 2021, legislation was passed to examine expanding eligibility for workers’ compensation benefits for first responders suffering from PTSD. The same year, Ohio implemented a state-level office focused on the well-being of first responders to coordinate specialized support and training.

The study, published in the Community Mental Health Journal, elicits perspectives on policy and programmatic activities for front-line personnel. Joining Fisher in the study was Catherine D. Lavender, Department of Occupational Therapy & Occupational Science, College of Health Professions, Towson University.

“We were not looking to quantify or evaluate aspects of policies or programs, but instead seeking to understand contextual factors influencing policy or program development and implementation,” Fisher said. “We had two research questions guiding our study. First, how are Ohio’s first responder communities advancing mental health policies and programs? Second, what are the opportunities and challenges faced by these individuals?”

Between March 2021 and June 2022, researchers interviewed firefighters, emergency medical service professionals and law enforcement officers employed in Ohio. Their insights revealed increases in job stress and first responder deaths by suicide as factors intensifying the need for mental health programs and policies. At the same time, they said a decrease in mental health stigma opens the door for more people to seek help. 

Most participants said they saw a heightened workload, often because of staffing constraints. On top of that, situations such as violent crime and drug overdoses added to their stress. Although they were able to complete their duties, they recognized it came with an emotional, physical and mental cost. For example, these pressures can result in compassion fatigue — physical and mental exhaustion and emotional withdrawal experienced by those who care for sick or traumatized people over an extended time.

While nearly all interviewees cited mental illness stigma as a concern for first responder professions, they noted a decline in those levels as colleagues — particularly the younger ones — are more open to peer discussion. However, they said a divide still exists with some first responders thinking they will appear weak or face job-related repercussions if they admit to mental health struggles.

The size of departments or jurisdictions played a role in the types of mental health support available, participants said. Access to programs ranged from extensive peer support to health-focused apps that connect them to resources. While small or rural departments sometimes face barriers to robust programming, others benefit from collaborations and less formal resources they term as “mutual aid agreements for mental health.” Insurance coverage for obtaining mental health treatment also reportedly varied, depending on the size and resources of the jurisdiction.

Fisher plans to use the study as preliminary data for future research which could focus on several themes raised by participants that he believes warrant further investigation.

“I hope this study, in conjunction with other research on first responder mental health and wellbeing, can raise awareness and inform policy and program development,” Fisher said.

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JOURNAL

Community Mental Health Journal

DOI

10.1007/s10597.023.01121.1 

ARTICLE TITLE

Ensuring Optimal Mental Health Programs and Policies for First Responders: Opportunities and Challenges in One U.S. State

ARTICLE PUBLICATION DATE

22-Mar-2023

Identifying the bee’s knees of bumble bee diets

Study details flower preferences for Midwest species

Peer-Reviewed Publication

OHIO STATE UNIVERSITY

COLUMBUS, Ohio – A new study has identified the bee’s knees of bumble bee dietary options in Ohio and the Upper Midwest.

By viewing almost 23,000 bumble bee-flower interactions over two years, researchers found that these bees don’t always settle for the most abundant flowers in their foraging area – suggesting they have more discerning dietary preferences than one might expect.

Being large, strong and social bees that can fly for long distances, bumble bees are major contributors to pollination, particularly for agriculture – but like other pollinators threatened by habitat loss, climate change and disease, the numbers of some species are dwindling.

This new data can help guide planting decisions for professional and amateur conservationists alike, researchers say.

“Getting over 20,000 observations of individual identified bumble bees visiting particular flower species is pretty incredible for a dataset,” said Karen Goodell, senior author of the study and a professor of evolution, ecology and organismal biology at The Ohio State University’s Newark campus. “One of the keys for this project was having flower associations, as well as estimates of flower abundance, so we counted the flowers, too.”

In no particular order, the top flower species preferred by an aggregate of bumble bee species in Ohio are milkweed, native thistles, morning glory, purple cone flower, bee balm, beardtongue, red clover, vetch and rosinweed, or cup plant. Two other “bee magnet” plants in low abundance that were crawling with the fuzzy buzzers are Culver’s root and wild indigo.

The study was published recently in the journal Ecosphere.

Of the 16 bumble bee species historically found in Ohio, researchers observed only 10 species, eight of which were abundant enough to include in the analysis – including the American Bumble Bee (Bombus pensylvanicus), which is under consideration for addition to the Federal Endangered Species List. As expected, the most frequently observed species – 11,555 visits in all – was the Common Eastern Bumble Bee (Bombus impatiens), compared to only 31 observations of the American Bumble Bee.

In fact, despite the extensive sampling, the authors are confident in the range of preferred flowers for only the three most common species. For the five less common species, researchers didn’t witness enough bee-flower interactions to fully account for what they eat. That sparseness of data on the rarer species speaks to the need for this comprehensive analysis, researchers said.

“It’s really important to know what species we do have and what they like to eat, because any of them could become rare,” Goodell said. “It’s not like we’re doing a fantastic job of taking care of our natural areas. The more information we have about their preferences, the better we can manage their habitat.”

Research team members visited 228 locations in Ohio during the summer months of 2017 and 2018, for a total of 477 hours, and observed bumble bees interacting with 96 different species of wildflowers. The sites included unmanaged fields, restored roadsides and meadows, and planted urban patches and hayfields.

The data analysis showed strong nonrandom patterns of bumble bee visits to flowers, meaning the bees selected specific plants in greater proportion than their availability would suggest. Researchers used a selection index to gauge bees’ flower preferences that compared the frequency of bumble bee species visits to the flowers’ overall percent abundance.

“What we were trying to get at was if all else is equal, what do they actually prefer?” said first author Jessie Lanterman Novotny, who led much of the project as an Ohio State PhD student and postdoctoral researcher in Goodell’s lab. “There were flowers that were less abundant that bees actively sought out – they didn’t necessarily eat what was most abundant. There were also plants they avoided: No matter how many of certain flowers there were, they said, ‘No thanks.’”

The researchers identified a few plants that are highly abundant and commonly used in pollinator conservation plantings and seed mixes that bumble bees consistently ignored, including alsike clover, black-eyed Susan and prairie cone flower. Five of the eight bumble bee species also were strongly drawn to non-native plants, which poses a dilemma for conservation planters focused on preserving native plant species.

And it turns out the three most common species don’t all feast at the same flower “table.”

“We compared the flowers each bumble bee species used the most, and species only overlapped by one-third or less,” said Lanterman Novotny, now a visiting assistant professor of biology at Hiram College. “Low overlap could relieve competition, so all these species can coexist together.”

This work was supported by the Ohio Department of Transportation.

Additional co-authors included former Ohio State PhD student Andrew Lybbert, now at Methodist University, and Paige Reeher and Randall Mitchell of the University of Akron.  

#

Contacts:
Karen Goodell, Goodell.18@osu.edu
Jessie Lanterman Novotny, JessieLantermanNovotny@gmail.com

Written by Emily Caldwell, Caldwell.151@osu.edu

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JOURNAL

Ecosphere

DOI

10.1002/ecs2.4425 

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Bumble bee banquet: Genus- and species-level floral selection by Midwestern Bombus

What constitutes a paradigm shift? An olive shrub’s mating system as a case study of Kuhn’s theory

Peer-Reviewed Publication

UNIVERSITY OF CHICAGO PRESS JOURNALS

Philosopher Thomas Kuhn’s influential theory of how scientific knowledge is built introduced the term “paradigm shift” to explain a transformation of a field’s ideas and methods. “A Paradigm Shift, or a Paradigm Adjustment? The Evolution of the Oleaceae Mating System as a Small-Scale Kuhnian Case Study,” a new paper published in The Quarterly Review of Biology, seeks to apply this analytical framework to a small controversy in population biology: the mating system of the shrub Phillyrea angustifolia.

Traditional theory states that the sex ratio of a population should be 1:1 male to female (or highly skewed towards hermaphrodites in male-hermaphrodite populations). But natural populations of P. angustifolia, a shrub in the olive family native to the Mediterranean, have unexpected high frequencies of males, note authors Alexandre Francq, Pierre Saumitou-Laprade, Philippe Vernet, and Sylvain Billiard.

Several possible solutions were floated to resolve this paradigm crisis. One postulated that hermaphroditic individuals were functionally female. Another suggested that a mechanism known as self-incompatibility made it so pollen emitted by males was more successful at fertilization than pollen emitted by hermaphrodites (and also eliminated the advantage of self-fertilization in hermaphrodites). 

The issue was ultimately resolved with the discovery of the link between a distortion segregation biased towards males and a diallelic self-incompatibility system, which advantaged male reproductive fitness. “Hermaphrodites can reproduce through their ovules and pollen, while males can only reproduce through their pollen, but hermaphrodites can only sire approximately one-half of the hermaphrodites … while males can sire all hermaphrodites,” the authors explain. 

Francq, Saumitou-Laprade, Vernet, and Billiard use several criteria to analyze if this discovery and change comports to Kuhn’s theory and represents a true paradigm shift, or only a paradigm adjustment. While the question of P. angustifolia’s sex ratio is a small one, the authors conclude it is indeed an example of an anomaly and associated crisis, central concepts in Kuhn’s theory. And while the discovery “did not change anything to the way most biologists of evolution practice science, it drastically changed the way groups dedicated to plant mating systems pursued their research.”

The question also embodies several examples of what Kuhn called the incommensurability of paradigms. These include the possibility that the same hermaphroditic P. angustifolia plant could be considered functionally as a female, in one paradigm or true hermaphrodites, in another, and the fact that different specialty fields studying the problem were too distinct from each other and unable to operate on common ground, the authors say. Resistances to the shift also arose after the discovery of the mating system, an inherent component to Kuhn’s theory, and the authors also discuss possible future challenges to the new paradigm. 

Ultimately, the authors conclude that the discovery of the diallelic self-incompatibility system in P. angustifolia does indeed fulfill the conditions necessary to constitute a paradigm shift. “Overall, a Kuhnian analysis of this small-scale case study offers a unique opportunity to analyze how science works in action, study some phenomena that are rarely observed for high-level paradigms (e.g., scientists’ conversion from the old to the new paradigm), and thoroughly analyze the roles played by the confrontation between models and data in a paradigm shift,” the authors write.

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JOURNAL

The Quarterly Review of Biology

DOI

10.1086/725275 

ARTICLE TITLE

A Paradigm Shift, or a Paradigm Adjustment? The Evolution of the Oleaceae Mating System as a Small-Scale Kuhnian Case Study

New book eyes Earth's excavators, from microbes to elephants and dinosaurs

Paleontologist explores a billion years of animals breaking up rocks, bones, shells and wood

Book Announcement

EMORY UNIVERSITY

22-MAY-2023

 

IMAGE: EMORY UNIVERSITY PALEONTOLOGIST ANTHONY MARTIN'S LATEST BOOK IS AIMED AT GENERAL AUDIENCES. view more 

CREDIT: ANTHONY MARTIN

The ordinary person looks at Georgia’s Stone Mountain and sees a solid, unmovable monolith. Emory University paleontologist Anthony Martin, who thinks in geologic time, sees something more akin to a giant sugar cube.

Ever since the crystalized mass of igneous-born minerals rose from deep underground, pushed by the upwelling of magma that formed the Blue Ridge Mountains around 350 million years ago, the giant rock’s flanks have faced continuous assault — and not just from weather and water.

Stone Mountain “is fighting a battle against life, and life is winning,” Martin writes in the preface of his new book, “Life Sculpted: Tales of the Animals, Plants and Fungi That Drill, Break and Scrape to Shape the Earth.”

The University of Chicago Press is publishing “Life Sculpted” June 9, marking the fifth book during the past 10 years by Martin, professor of practice in Emory’s Department of Environmental Sciences.

Martin is a geologist and paleontologist focused primarily on ichnology — the study of traces of life such as tracks, burrows, nests and tooth marks. Among his discoveries are the only known burrowing dinosaur and the oldest bird tracks in Australia. His other passion is great science communication, which his books exemplify.

“Life Sculpted” is a follow-up to Martin’s 2017 book “The Evolution Underground: Burrows, Bunkers and the Marvelous Subterranean World Beneath Our Feet.” The current volume, also aimed at anyone interested in Earth sciences, goes beyond burrowing to cover how myriad forms of life have broken down the hard substrates of rock, shells, bones and wood during the past billion years.

“Yes, life can be hard,” Martin quips, “but life also makes everything less hard every day. Bioerosion shapes the world, literally. It’s changed entire ecosystems.”

It has also changed human history. Martin cites the wood-boring clams that perforated the hulls of the Spanish Armada, helping tip the odds toward the English Navy in 1588, when it won a decades-long fight for maritime dominance.

Bioeroders come in all sizes, he writes, from microbes that transport calcium away from rock and shells to elephants that dig caves with their tusks to obtain salt.

Bioeroders can change the soundscape as well as the landscape. In a chapter entitled “Your Beach Is Made of Parrotfish Poop,” Martin describes hearing “a crunching and popping reminiscent of sugary breakfast cereals meeting milk” while snorkeling over a Bahamian reef. The crunching, he explains, is actually the sound of parrotfishes biting out chunks of the reef with jaws and teeth capable of breaking apart rock. Reefs and the surrounding shallow-marine environments have been shaped by millions of years of such fishes gnawing on coral and defecating sediments.

Martin doesn’t just want readers to visualize and hear bioerosion. He also wants them to smell it.

He describes how dinosaurs chewed up rotten wood to get at insects and how insects, in turn, bored into the limb bones of large Jurassic dinosaurs that apparently became trapped in a stinking mud pit of decomposing flesh in Colorado.

The book gives many more familiar, modern-day examples of bioeroders. Georgia “hosts small, furry, bone-destroying beings that descend from the trees and eat skulls,” Martin writes. He knows this from personal observation of gray squirrels that relentlessly gnawed to bits a cow skull he and his wife had hanging in their courtyard.

“It’s their calcium supplement,” he explains.

And then there are all the bioeroders who have been busily at work on Stone Mountain.

Lichens colonized the enormous rock’s surface as soon as it emerged into the air, starting the process of soil formation that then allowed plants to take root. Animals began scurrying across and digging into its crumbling surface. Those animals eventually included humans, among the leading biological excavators of hard materials on the planet.

Humans have chiseled massive chunks from Stone Mountain’s side and removed tons of granite from its core. And any time you hike up Stone Mountain, Martin wants you to consider that you are taking a bit of its powdery dust with you on your footwear when you leave.

“The book is filled with ‘aha’ moments for the reader,” Martin says. “I want to encourage people to look for the evidence and to expand their awareness of how life is shaping the Earth.”

South African fossils reveal ancient beast's epic journey to oblivion


Illustration shows the Permian Period tiger-sized saber-toothed protomammal Inostrancevia atop its dicynodont prey

By Will Dunham
Mon, May 22, 2023

WASHINGTON (Reuters) - It was a dire moment for life on Earth. Runaway global warming triggered by calamitous volcanism in Siberia inflicted the worst mass extinction on record - dooming perhaps 90% of species - roughly 252 million years ago at the end of the Permian Period.

Unlike the asteroid 66 million years ago that ravaged the dinosaurs, this extinction event unfolded over a protracted time span, with species perishing one by one as conditions worsened. Scientists said on Monday fossils unearthed in South Africa provide a peek into this drama, telling the tale of an apex predator that over multiple generations migrated halfway around the world in a desperate, and ultimately failed, bid to survive.

This beast, a tiger-sized, saber-toothed mammal forerunner called Inostrancevia, had been known only from fossils excavated in Russia's northwestern corner bordering the Arctic Sea until new remains were discovered at a farm in central South Africa.

The fossils suggest that Inostrancevia left its place of origin and trekked over time - maybe hundreds or thousands of years - about 7,000 miles (12,000 km) across Earth's ancient supercontinent Pangaea at a time when today's continents were united. Inostrancevia filled the ecological niche of top predator in South Africa left vacant after four other species already had vanished.

"However, it did not survive there long," said paleontologist Christian Kammerer of the North Carolina Museum of Natural Sciences, lead author of the research published in the journal Current Biology, noting that Inostrancevia and all of its closest relatives disappeared in the mass extinction called "the Great Dying."

"So, they have no living descendants, but they are a member of the larger group called synapsids, which includes mammals as living representatives," Kammerer added.

Inostrancevia is part of an assemblage of animals called protomammals that combined reptile-like and mammal-like features. It was 10-13 feet (3-4 meters) long, roughly the size of a Siberian tiger, but with a proportionally larger and elongated skull as well as enormous, blade-like canine teeth.

"I suspect these animals primarily killed prey with their saber-like canine fangs and either carved out chunks of meat with the serrated incisors or, if it was small enough, swallowed the prey whole," Kammerer said.

Inostrancevia's body had an unusual posture typical of protomammals, not quite sprawling like a reptile or erect like a mammal but something in between, with sprawled forelimbs and mostly erect hind limbs. It also lacked the mammalian facial musculature and would not have produced milk.

"Whether these animals were furry or not remains an open question," Kammerer said.

The mass extinction, occurring over a span of a million years or so, set the stage for the rise of the dinosaurs in the subsequent Triassic Period. Massive volcanism unleashed lava flows across large portions of Eurasia and pumped carbon dioxide into the atmosphere for thousands of years. This caused a spike in worldwide temperatures, depletion of oxygen in the seas and atmosphere, ocean acidification and global desertification.

Top predators were especially vulnerable to extinction because they required the most food and space.

"They tend to take a relatively long time to mature and have few offspring. When ecosystems are disrupted and prey supplies are reduced or available habitat is limited, top predators are disproportionately affected," Kammerer said.

The researchers see parallels between the Permian crisis and today's human-induced climate change.

"The hardship these species faced was as a direct result of a global-warming climate crisis, so they really had no choice but to adapt to it or go extinct. This is clear by evidence of their brief perseverance in spite of these conditions, but eventually they disappeared one by one," said paleontologist and study co-author Pia Viglietti of the Field Museum in Chicago.

"Unlike our Permian predecessors," Viglietti added, "we actually have the ability to do something to prevent this kind of ecosystem crisis from happening again."

(Reporting by Will Dunham, Editing by Rosalba O'Brien)

Fossils of a saber-toothed top predator reveal a scramble for dominance leading up to “the Great Dying”

Peer-Reviewed Publication

FIELD MUSEUM

 

IMAGE: GIANT GORGONOPSIAN INOSTRANCEVIA WITH ITS DICYNODONT PREY, SCARING OFF THE MUCH SMALLER AFRICAN SPECIES CYONOSAURUS. view more 

CREDIT: ART BY MATT CELESKEY.

Two hundred and fifty-two million years ago, Earth experienced a mass extinction so devastating that it’s become known as “the Great Dying.” Massive volcanic eruptions triggered catastrophic climate change, killing off nine out of every ten species and eventually setting the stage for the dinosaurs. But the Great Dying was a long goodbye-- the extinction event took place over the course of up to a million years at the end of the Permian period. During that time, the fossil record shows drama and upheaval as species fought to get a foothold in their changing environments. One animal that exemplifies this instability was a tiger-sized, saber-toothed creature called Inostrancevia: a new fossil discovery suggests that Inostrancevia migrated 7,000 miles across the supercontinent Pangaea, filling a gap in a faraway ecosystem that had lost its top predators, before going extinct itself.

“All the big top predators in the late Permian in South Africa went extinct well before the end-Permian mass extinction. We learned that this vacancy in the niche was occupied, for a brief period, by Inostrancevia,” says Pia Viglietti, a research scientist at the Field Museum in Chicago and a co-author of the new study in Current Biology.

The prehistoric creature looked the part of “top predator.” “Inostrancevia was a gorgonopsian, a group of proto-mammals that included the first saber-toothed predators on the planet,” says Viglietti. It was about the size of a tiger and likely had skin like an elephant or a rhino; while vaguely reptilian in appearance, it was part of the group of animals that includes modern mammals.

Prior to this new paper, Inostrancevia had only ever been found in Russia. But while examining the fossil record of South Africa’s Karoo Basin, Viglietti’s colleague Christian Kammerer identified the fossils of two large predatory animals that were different from those normally found in the region. “The fossils themselves were quite unexpected,” says Viglietti. It’s not clear how they made it from what’s now Russia, or how long it took them to cross Pangaea and arrive in what’s now South Africa. But being far from home was just one element of what made the fossils special.

“When we reviewed the ranges and ages of the other top predators normally found in the area, the rubidgeine gorgonopsians, with these Inostrancevia fossils, we found something quite exciting,” she says. “The local carnivores actually went extinct quite a bit before even the main extinction that we see in the Karoo-- by the time the extinction begins in other animals, they're gone.”

The arrival of Inostrancevia from 7,000 miles away and its subsequent extinction indicates that these top predators were “canaries in the coal mine” for the larger extinction event to come.

“This shows that the South African Karoo Basin continues to produce critical data for understanding the most catastrophic mass extinction in Earth’s history,” says co-author Jennifer Botha, director of GENUS Centre of Excellence in Palaeosciences and professor at the Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg.

“We have shown that the shift in which groups of animals occupied apex predator roles occurred four times over less than two million years around the Permian-Triassic mass extinction, which is unprecedented in the history of life on land. This underlines how extreme this crisis was, with even fundamental roles in ecosystems in extreme flux,” said Christian Kammerer, the study’s first author and a research curator of paleontology at the North Carolina Museum of Natural Sciences and research associate at the Field Museum.

The vulnerability of these top predators matches what we see today. “Apex predators in modern environments tend to show high extinction risk, and tend to be among the first species that are locally extirpated due to human-mediated activities such as hunting or habitat destruction,” says Kammerer. “Think about wolves in Europe or tigers in Asia, species which tend to be slow to reproduce and grow and require large geographic areas to roam and hunt prey, and which are now absent from most of their historic ranges. We should expect that ancient apex predators would have had similar vulnerabilities, and would be among the species that first go extinct during mass extinction events.”

In addition to shedding new light on the extinction event that helped lead to the rise of the dinosaurs, Viglietti says that the study is important for what it can teach us about the ecological disasters the planet is currently experiencing.

“It's always good to get a better understanding of how mass extinction events affect ecosystems, especially because the Permian is basically a parallel on what we’re going through now,” said Viglietti. “We don't really have any modern analogs of what to expect with the mass extinction happening today, and the Permo-Triassic  mass extinction event represents one of the best examples of what we could experience with our climate crisis and extinctions. I guess the only difference is, we know what to do and how to stop it from happening.”

Inostrancevia fossils in the field.

  

Paul October, a now retired field technician from Iziko South African Museum, with Inostrancevia fossils in the field.

CREDIT

Photo by Jennifer Botha.

The field location where the Inostrancevia were found (a farm called Nooitgedacht in the Free State Province of South Africa's Karoo Basin).

CREDIT

Photo by Pia Viglietti.

JOURNAL

Current Biology

DOI

10.1016/j.cub.2023.04.007 

ARTICLE TITLE

Rapid turnover of top predators in African terrestrial faunas around the Permian-Triassic mass extinction

ARTICLE PUBLICATION DATE

22-May-2023