Saturday, January 14, 2023

Images capture 850-year-old aftermath of stellar collision

A Dartmouth professor's images of the explosive aftermath from the collision of two dying stars could help scientists better understand this rare type of astronomical event—and may finally confirm the identity of a brilliant but short-lived star observed nearly 850 years ago.

Robert Fesen, a professor of physics and astronomy, captured telescopic images that show a fireworks-like burst of thin filaments radiating from a highly unusual star at the center of an object called Pa 30, according to findings he announced Jan. 12 at the 241st Meeting of the American Astronomical Society. Fesen is lead author of a paper reporting the findings that has been submitted to the The Astrophysical Journal Letters for publication.

Pa 30 is a dense region of illuminated gas, dust and other matter known as a nebula. Fesen and his co-authors report that Pa 30 appears to contain little to no hydrogen and helium but is instead rich in the elements of sulfur and argon.

The nebula's unusual structure and characteristics match the predicted result of a collision between end-stage stars known as white dwarfs, Fesen said. White dwarfs are faint, extremely dense stars about the size of Earth that contain the mass of the Sun. The merger of two white dwarfs is one proposed explanation for a subclass of supernovae—or star explosions—called Iax events, in which the star is not completely destroyed, Fesen said.

"I have never seen any object—and certainly no supernova remnant in the Milky Way galaxy—that looks quite like this, and neither have any of my colleagues," Fesen said. "This remnant will allow astronomers to study a particularly interesting type of supernova that up to now they could only investigate from theoretical models and examples in distant galaxies."

The size of Pa 30 and the speed at which it is expanding—about 2.4 million miles per hour—suggest the explosive collision occurred around the year 1181, the researchers report. That coincides with observations by Chinese and Japanese astronomers at the time of a very bright star that suddenly appeared in the constellation Cassiopeia and was visible for about six months as it slowly faded. These fleeting stars are known as "guest stars."

The images Fesen captured of the nebula's structure and luminosity not only provide the most accurate estimate yet of its age, but also could allow astronomers to refine existing models of white dwarf mergers. Pa 30 was discovered in 2013 by co-author and amateur astronomer Dana Patchick, but up until now, images of the nebula had shown only an extremely faint and diffuse object, Fesen said.

"Our deeper images show that Pa 30 is not only beautiful, but now that we can see the nebula's true structure, we can investigate its chemical makeup and how the central star generated its remarkable appearance, then compare these properties to predictions from specific models of rare white dwarf mergers," Fesen said.

Fesen took the images of Pa 30 in late 2022 using the 2.4-meter Hiltner Telescope at the MDM Observatory—which Dartmouth owns and operates with four other universities—adjacent to Kitt Peak National Observatory in Arizona. Fesen equipped the telescope with an optical filter sensitive to a particular emission line of sulfur. He captured Pa 30 in three 2,000-second exposures under very clear skies and took additional data on the nebula's structure, size and velocity.

The study by Fesen and his co-authors built upon work published in 2019 by Russian researchers who found an extremely unusual star nearly in the dead center of Pa 30. That star exhibited several properties suggesting the collision of two white dwarfs, and it had a surface temperature of nearly 400,000 degrees Fahrenheit with an astounding outflowing wind velocity of about 35 million miles per hour.

In 2021, astronomers from the University of Hong Kong that had revisited the Russian team's results reported that Pa 30 was roughly 1,000 years old and in nearly the same sky location as the guest star recorded in 1181. These researchers proposed that Pa 30 is the aftermath of a white dwarf collision that lit up the night sky nearly a millennium ago, though their margin of error on its age was 300 years.

"Our new observations put a much tighter constraint on the object as having an expansion age of around 850 years, which is perfect for it to be the remains of the 1181 guest star," Fesen said. To the ancient astronomers, the new star would have been nearly as bright as, or brighter than, Vega, the fifth-brightest star in the sky as seen from Earth.

"The guest star was bright enough that three separate groups in China observed it within a couple of days of each other and it also was seen in Japan," Fesen said. "A new star as bright as Vega would've been quite noticeable. To the ancients, their TV set was the sky, so they would've easily noticed and certainly recorded the sudden appearance of a bright new star in the heavens."

Journal information: Astrophysical Journal Letters

Provided by Dartmouth College

Astronomers solve 900-year-old cosmic mystery surrounding Chinese supernova of 1181AD

Research improves ability to identify and study algae species

by University of Oklahoma

OU-led group improves ability to identify and study algae species — Summer Microcystis bloom in Castle Rock Pond, Norman, Oklahoma.

Harmful algal blooms create challenges around the globe for water quality and health risk management for humans, wildlife and pets. A team of researchers from the University of Oklahoma is leading an effort toward better management of Microcystis blooms and toxins through a new genome-based taxonomy.

OU Regents' Professor of Biology Dave Hambright and members of his Plankton Ecology and Limnology Lab, in conjunction with OU microbiology professor Lee Krumholz, collaborated on this project with faculty members at the University of North Carolina, James Madison University and Auburn University. The results of their work were published in Science Advances.

Through the development of a new genome-based taxonomy, researchers for the first time will be able to characterize ecological niches of Microcystis, including nutrient requirements and seasonality, and ultimately, control harmful Microcystis blooms. The team has developed genetic markers that will allow researchers to identify Microcystis species present in water systems. In their paper, the researchers have identified 16 unique species, with as many as 30 or more likely, that are genetically distinct, but that do not correspond to current morphologically defined species.

"This new genome-based taxonomy lays the basis for researchers to formulate science-based proactive management programs to rid our waters of harmful Microcystis blooms," Hambright said. "Our improved ability to identify and study species of this algae will aid our ability to reduce health risks, as well as manage and protect our increasingly vulnerable water resources."

Understanding Microcystis ecology and evolution is foundational to lake and water quality management aimed toward preventing and reducing harmful Microcystis blooms. While traditional Microcystis taxonomy (classification into species) recognizes multiple species, these classifications are controversial as they are based on morphology and not ecological features. Additionally, they conflict with standard DNA-sequence-based classifications, which suggest one species with complex and variable ecologies.

Based on the work of OU biology doctoral student Katherine Cook, which was published in 2020 in Limnology & Oceanography, the group hypothesized Microcystis and its microbiome were a coevolved community of complementary interacting bacteria species (an interactome), with each necessary for the success of the others.

Their goal was to examine the genetic makeup of Microcystis from around the world using 122 published entire genomes and make predictions of potential metabolic functions that might be provided by the microbiome bacteria. Their paper represents the foundation for that goal in the form of a robust taxonomic classification, including evolutionary relationships.

The majority of the bioinformatic analyses in this paper was conducted by OU postdoctoral fellow Haiyuan Cai, with assistance from OU doctoral student Chris McLimans. Additional data analysis was supported by OU research assistant professor Jessica Beyer.

More information: Haiyuan Cai et al, Microcystis pangenome reveals cryptic diversity within and across morphospecies, Science Advances (2023). DOI: 10.1126/sciadv.add3783. www.science.org/doi/10.1126/sciadv.add3783

Journal information: Science Advances

Provided by University of Oklahoma Are zebra mussels eating or helping toxic algae?

DNA collected from slave skeletons interred in unmarked 18th-century burial ground reveals their history

A team of researchers affiliated with several institutions in the U.S., working with members of The Anson Street African Burial Ground Project, have discovered some of the history behind some of the enslaved people buried in 18th century Charleston, South Carolina—home to one of the busiest slave ports in American history.

In their paper published in Proceedings of the National Academy of Sciences, the group describes how they collected tissue samples from as many of the skeletons in the cemetery as possible and what analysis of their DNA revealed about their history.

Starting in the early 1500s, as part of a larger slave trade, white Europeans brought black people living in Africa by force to work as slaves in the colonial America. They continued to do so for the following three hundred years. Many of those slaves began their life in America in Charleston South Carolina.

Approximately half of all such slaves arrived at the port there and were summarily sold. In this new effort, the researchers conducted a DNA analysis of skeletons of slaves who had been buried in an unmarked burial ground during the 18th century near the heart of the city.

The cemetery was discovered back in 2013 and since that time, efforts have been made to identify those who were buried there. In all, 36 skeletons were found in the cemetery but only 18 had tissue samples suitable for use in a genetic study. Prior work on the project showed that all of the people in the cemetery had been placed in coffins prior to burial and that most had artifacts in the coffin with them, such as pipes, beads or even coins.

In looking at the DNA, the researchers found that all but one of the slaves had come directly from Africa, or had ancestors that had. They also found that slave ancestry was not confined to the west coast of Africa—some of the slaves had been taken from parts of sub-Saharan areas. The team found that 13 of them had been born in West Africa, the rest likely in the U.S. The researchers also found that none of the people buried in the cemetery were related to any other—a sign that suggests family members were separated upon arrival.

The researchers also found that one person in the cemetery had Native American maternal lineage, which they suggest highlights the multigenerational aspect of the American slave trade.

More information: Raquel E. Fleskes et al, Community-engaged ancient DNA project reveals diverse origins of 18th-century African descendants in Charleston, South Carolina, Proceedings of the National Academy of Sciences (2023). DOI: 10.1073/pnas.2201620120

Journal information: Proceedings of the National Academy of Sciences

How brachyuran crabs survive in highly acidic areas near shallow-water hydrothermal vents

by Bob Yirka , Phys.org

A team of researchers affiliated with multiple institutions in Taiwan and one in Germany has discovered the means by which brachyuran crabs are able to survive in highly acidic waters near shallow-water hydrothermal vents. In their paper published in Proceedings of the Royal Society B, the group describes how they studied crab specimens and the environment in which they live to solve the puzzle of their existence.

Hydrothermal vents are hot springs that exist on the sea floor. In most instances, they occur along mid-ocean ridges. Such vents spew heated water, along with other materials, into the surrounding water creating a mix. In this new effort, the researchers were curious about a species of crab that lives in a shallow-water hydrothermal vent field off the southeast coast of Kueishantao Island, near Taiwan. They noted that the crab is the only metazoan creature living in the area due to the large amount of sulfide emitted by the hydrothermal vent.

To find out how the crab survives in such a hostile environment (hydrogen sulfide is toxic to most animals) the researchers collected samples of the water in which they lived and conducted experiments on the crabs they found living there. They also captured some of the crabs and brought them back to their lab for closer inspection.

In looking at the crabs, the researchers found that they had unique gills (located under the carapace)—they were able to oxidize the sulfide to thiosulfate and to bind it to hypotaurine which led to the generation of thiotaurine, which is much less toxic than hydrogen sulfide. And then, bacteria living in the gills absorbed the thiotaurine—they used it as an energy source and in so doing made it even less toxic.

The net result was that the crab was able to get the oxygen it needed from the water without succumbing to the hydrogen sulfide from the hydrothermal vent. The researchers suspect that the detoxification allows the crab to gain energy from the thiotaurine as well. They note that the arrangement with the bacteria makes the crab a holobiont—a species able to survive in an environment inhospitable to virtually all other creatures.

More information: Pei-Hsuan Chou et al, Cellular mechanisms underlying extraordinary sulfide tolerance in a crustacean holobiont from hydrothermal vents, Proceedings of the Royal Society B: Biological Sciences (2023). DOI: 10.1098/rspb.2022.1973

Journal information: Proceedings of the Royal Society B

Making the case for using insects as food for both humans and livestock

crickets food

Credit: Pixabay/CC0 Public Domain

Two pairs of academics are making the case for using insects as a food source in Perspectives pieces published in the journal Science.

The first pair, Arup Kumar Hazarika and Unmilan Kalita, with Cotton University and Barnagar College, respectively, both in India, argue that a strong case can be made for using insects to meet the growing need for food around the world in the coming years. Arnold van Huis with Wageningen University & Research in the Netherlands and Laura Gasco with the University of Torino in Italy argue that there is a strong case to be made for using insects as feed for livestock.

As the global population rises and the land available for growing more food becomes more scarce, scientists around the around the world have begun looking for alternative sources. In the two papers in Science, the authors all agree that insects could provide the answer.

In the first paper, the authors note that humans eating insects is not novel. People have been eating them for as long as there have been people. And many people in the world today still eat them; however, most do not. And in fact, in most places, people see eating insects as disgusting or even dirty. That could change, the authors argue, if insects were provided through commercially viable outlets.

They note that eating insects can provide many nutritional benefits—common crickets, for example, are high in protein. That makes them competitive with meat from animals. The researchers note also that insects require fewer resources to raise than livestock, making them a prime green alternative.

In the second paper, the authors note that currently, most livestock feed is made from fishmeal and soybean meal. They also note that the production of meat worldwide uses between 70% and 80% of all agricultural land and yet produces about 25% of the protein consumed by humans.

They suggest that replacing conventional feed with feed made from insects would free up large parcels of land now used to grow food for livestock. It would also be a healthier food source for the animals. Also, farming insects is likely to become more feasible as the planet continues to warm.

In both articles, the authors argue that the only factor holding back the use of insects as a food source is the will to do so by those producing the food.

More information: Arup Kumar Hazarika et al, Human consumption of insects, Science (2023). DOI: 10.1126/science.abp8819

Arnold van Huis et al, Insects as feed for livestock production, Science (2023). DOI: 10.1126/science.adc9165

Journal information: Science

Singing gibbons found to be more rhythmic when performing duets

Singing gibbons found to be more isochronous when performing duets

Organization of lar gibbon's songs. (a) Male lar gibbon singing in the Huai Kha Khaeng

Wildlife Sanctuary (Thailand). (b) Spectrogram and inter-onset-interval graphs of the male

solo. The fundamental frequency is highlighted in light blue on the spectrogram. The

colored bar indicates inter-onset intervals (tk) of the solo singing male, where solid white

lines on the bar represent the onsets. (c) Spectrograms and inter-onset-interval graphs of

the reproductive couple's whole duet. The fundamental frequency of individuals'

contributions is highlighted on the spectrogram in dark blue for the male contribution to

duet and dark yellow for the female contribution to duet. The sections of the song are

labeled in the upper part of the spectrogram and separated with dotted lines. Colored bars

indicate inter-onset intervals (tk) of the contributions of each individual with white lines

again corresponding to the onsets. Black bars turn white when the co-singers overlap.

Notice how rhythmicity unfolds heterogeneously throughout the duet, alternating periods

of higher and lower overlap. Note clusters onsets of the duetting gibbons influence each

other (see also figure 4), with introductory sequences and interludes showing higher levels

of synchrony, while great calls and codas partly overlap.

Credit: Proceedings of the Royal Society B: Biological Sciences (2023).

DOI: 10.1098/rspb.2022.2244

A team of researchers at the University of Turin, working with a colleague from the Max Planck Institute for Psycholinguistics and another from Aarhus University and The Royal Academy of Music, has found that the lar gibbon tends to be more isochronous (repeating notes more regularly) when singing as part of a duet with a member of the opposite gender. The research is published in the journal Proceedings of the Royal Society B: Biological Sciences.

The researchers recorded and studied songs performed by lar gibbons (also known as white-handed gibbons) living in a wildlife sanctuary in Thailand and a zoo park in Italy. Lar gibbons, they note, are among the few singing primates. Their work was part of an effort aimed at learning about the origins of rhythm in humans. Prior research has shown that not only do both genders of lar gibbons sing, they sometimes do so together as duets.

In all, the researchers made 215 recordings of songs voiced by 12 gibbons. Their analysis consisted of labeling notes making it possible to discern patterns, particularly those that were repeating. They also measured the intervals and the intertwining of notes as duets occurred.

The researchers found evidence of rhythm in all of the songs on their recordings, noting that they were in many respects similar to rhythm in human songs. They also found differences in rhythm based on gender—males tended to sing with more beats when singing with a female partner. During duets, the researchers found that notes sung by the male and female singers overlapped approximately 16 to 18% of the time, which they note is greater than chance.

The researchers also found that during duets, the males tended to sing more than the females, which they discovered meant that the females sang fewer notes when singing with a partner. This, they suggest, was evidence of rhythm playing a social role with the apes.

The researchers suggest that rhythmic ability in apes may have evolved as a means for coordinating vocalisms between genders. They also note that it is still not known if the last common ancestor between primates had similar abilities or if they evolved independently.

More information: Teresa Raimondi et al, Isochrony and rhythmic interaction in ape duetting, Proceedings of the Royal Society B: Biological Sciences (2023). DOI: 10.1098/rspb.2022.2244

Journal information: Proceedings of the Royal Society B

Looking for musical abilities in primates

NESUN DORMA PAVAROTTI & FREDDY MERCURY

ChatGPT writes convincing fake scientific abstracts that fool reviewers in study

by Marla Paul, Northwestern University

Could the new and wildly popular chatbot ChatGPT convincingly produce fake abstracts that fool scientists into thinking those studies are the real thing?

That was the question worrying Northwestern Medicine physician-scientist Dr. Catherine Gao when she designed a study—collaborating with University of Chicago scientists—to test that theory.

Yes, scientists can be fooled, their new study reports. Blinded human reviewers—when given a mix real and falsely generated abstracts—could only spot ChatGPT generated abstracts 68% of the time. The reviewers also incorrectly identified 14% of real abstracts as being AI generated.

"Our reviewers knew that some of the abstracts they were being given were fake, so they were very suspicious," said corresponding author Gao, an instructor in pulmonary and critical care medicine at Northwestern University Feinberg School of Medicine. "This is not someone reading an abstract in the wild. The fact that our reviewers still missed the AI-generated ones 32% of the time means these abstracts are really good. I suspect that if someone just came across one of these generated abstracts, they wouldn't necessarily be able to identify it as being written by AI."

The hard-to-detect fake abstracts could undermine science, Gao said. "This is concerning because ChatGPT could be used by 'paper mills' to fabricate convincing scientific abstracts," Gao said. "And if other people try to build their science off these incorrect studies, that can be really dangerous."

Paper mills are illegal organizations that produce fabricated scientific work for profit.

The ease with which ChatGPT produces realistic and convincing abstracts could increase production by paper mills and fake submissions to journals and scientific conferences, Gao worries.

AI sleuths can identify AI fakes

For the study, Gao and co-investigators took titles from recent papers from high-impact journals and asked ChatGPT to generate abstracts based on that prompt. They ran these generated abstracts and the original abstracts through a plagiarism detector and AI output detector, and had blinded human reviewers try to differentiate between generated and original abstracts. Each reviewer was given 25 abstracts that were a mixture of the generated and original abstracts and asked to give a binary score of what they thought the abstract was.

"The ChatGPT-generated abstracts were very convincing," Gao said, "because it even knows how large the patient cohort should be when it invents numbers." For a study on hypertension, which is common, ChatGPT included tens of thousands of patients in the cohort, while a study on a monkeypox had a much smaller number of participants.

"Our reviewers commented that it was surprisingly difficult to differentiate between the real and fake abstracts," Gao said.

The study found that the fake abstracts did not set off alarms using traditional plagiarism-detection tools. However, in the study, AI output detectors such as GPT-2 Output Detector, which is available online and free, could discriminate between real and fake abstracts.

"We found that an AI output detector was pretty good at detecting output from ChatGPT and suggest that it be included in the scientific editorial process as a screening process to protect from targeting by organizations such as paper mills that may try to submit purely generated data," Gao said.

ChatGPT also can be used for good

But ChatGPT can also be used for good, said senior study author Yuan Luo, director of the Institute for Augmented Intelligence in Medicine at Feinberg.

"AI language models such as ChatGPT have a potential to help automate the writing process, which is often the speed bottleneck in knowledge generation and dissemination," Luo said. "The results from the paper showed this is likely doable for the field of medicine, but we need to bridge certain ethical and practical gaps."

For example, is AI-assisted writing still considered original, Luo asked. Also, AI-generated text currently has difficulty in proper citation, which is a must for scientific writing, he noted.

"Generative text technology has a great potential for democratizing science, for example making it easier for non-English-speaking scientists to share their work with the broader community," said senior author Dr. Alexander Pearson, director of data sciences and the Head/Neck Cancer Program in Hematology/Oncology at the University of Chicago. "At the same time, it's imperative that we think carefully on best practices for use."

The research is available on the bioRxiv preprint server.

More information: Catherine A. Gao et al, Comparing scientific abstracts generated by ChatGPT to original abstracts using an artificial intelligence output detector, plagiarism detector, and blinded human reviewers, bioRxiv (2022). DOI: 10.1101/2022.12.23.521610

Provided by Northwestern University EXPLAINER: What is ChatGPT and why are schools blocking it?

The world in grains of interstellar dust

by Hokkaido University

Understanding how dust grains form in interstellar gas could offer significant insights to astronomers and help materials scientists develop useful nanoparticles.

Laboratory and rocket-borne studies have revealed new insights into how interstellar dust grains came into being before our solar system formed. The results, published by Hokkaido University researchers and colleagues in Japan and Germany in the journal Science Advances, might also help scientists make nanoparticles with useful applications in more efficient and eco-friendly ways.

These "presolar" grains can be found in meteorites that fall to Earth, allowing laboratory studies that reveal possible routes for their formation.

"Just as the shapes of snowflakes provide information on the temperature and humidity of the upper atmosphere, the characteristics of presolar grains in meteorites limits the environments in the outflow of gas from stars in which they could have formed," explains Yuki Kimura of the Hokkaido team. Unfortunately, however, it has proved difficult to pin down the possible environments for the formation of grains consisting of a titanium carbide core and a surrounding graphitic carbon mantle.

Better understanding of the environment around stars in which the grains could have formed is crucial to learning more about the interstellar environment in general. That could, in turn, help clarify how stars evolve and how the materials around them become the building blocks for planets.

The structure of the grains appears to suggest that their titanium carbide core first formed and was then subsequently coated in a thick layer of carbon in more distant regions of gas outflow from stars that formed before the sun.

The team explored the conditions that might recreate the grain formation in laboratory modeling studies guided by theoretical work on grain nucleation—the formation of grains from tiny original specks. This work was augmented by experiments performed in the periods of microgravity experienced aboard sub-orbital rocket flights.

The results offered some surprises. They suggest the grains most likely formed in what the researchers call a non-classical nucleation pathway: a series of three distinct steps not predicted by conventional theories. First, carbon forms tiny, homogenous nuclei; titanium then deposits on these carbon nuclei to form carbon particles containing titanium carbide; finally, thousands of these fine particles fuse to form the grain.

"We also suggest that the characteristics of other types of presolar and solar grains that formed at later stages in the development of the solar system might be accurately explained by considering non-classical nucleation pathways, such as those suggested by our work," Kimura concludes.

The research could aid understanding of distant astronomical events, including giant stars, newly forming planetary systems, and the atmospheres of planets in alien solar systems around other stars. But it might also help scientists here on Earth to gain better control over the nanoparticles they are exploring for use in many fields, including solar energy, chemical catalysis, sensors and nanomedicine. The potential implications of studying the tiny grains in meteorites therefore range from the future industries of Earth to as far away as we can imagine.

More information: Yuki Kimura, Nucleation experiments on a titanium-carbon system imply nonclassical formation of presolar grains, Science Advances (2023). DOI: 10.1126/sciadv.add8295. www.science.org/doi/10.1126/sciadv.add8295

Journal information: Science Advances

Provided by Hokkaido University

Meteoritic stardust unlocks timing of supernova dust formation

Researchers identify protein that counteracts key rattlesnake venom toxins

by University of Maryland

Venomous snakes cause an estimated 120,000 deaths and 400,000 disabling injuries worldwide each year, with approximately 8,000 snake bite cases in the United States alone.

To reduce and mitigate the severity of venomous snake bites, a team of University of Maryland biologists launched an investigation into the genome of the western diamondback rattlesnake (Crotalus atrox), a species with more venom toxins encoded in its genome than any other known rattlesnake. The team pinpointed a single protein—called FETUA-3—that inhibits a broad spectrum of rattlesnake venom toxins.

Published in the Proceedings of the National Academy of Sciences, the team's findings have notable implications for the development of improved snake bite treatments.

"A good snakebite treatment needs to be able to counteract the venoms of more than just one species of snake," said the study's senior author Sean Carroll, a Distinguished University Professor of Biology at UMD and vice president for science education at the Howard Hughes Medical Institute (HHMI).

"FETUA-3 inhibited a huge number of toxins—over 20—that we detected and even bound to and inhibited the toxins of venoms from several other rattlesnakes we tested. We'll need to learn more about how broadly FETUA-3 can be applied or if it'll need some additional tinkering but knowing that this one protein can neutralize an entire class of toxins brings researchers even closer to creating a better anti-venom."

A natural history mystery

According to Carroll, the team's research began with a simple yet intriguing enigma that has long eluded researchers: how and why are poisonous snakes resistant to their own venom?

"It's like a constant, three-way biological arms race where each side is always innovating to conquer the other," explained Carroll, who is also the Andrew and Mary Balo and Nicholas and Susan Simon Endowed Chair at UMD.

"To survive a venomous snake bite, prey have to evolve resistance to the venom. If the prey become a little resistant, then the snakes have to adjust with a better venom. But snakes have also been able to protect themselves from their own evolving venom during their arms race against prey—our goal was to figure out exactly how."

Most snake venoms carry an arsenal of dangerous toxins that facilitates the paralysis, killing and digestion of prey. One of the core components in rattlesnake venom is a class of molecules called metalloproteinases, which prevent blood clots from forming, break down tissue and ultimately cause hemorrhage. To protect themselves from these toxins, both snakes and their prey rely on special proteins encoded within their genomes that stymie the venom's debilitating effects.

The researchers investigated a family of five proteins generally attributed to venom resistance. Unexpectedly, only a single member of the protein family had most of the venom-counteracting activity—FETUA-3—binding nearly all the toxins in the western diamondback's venom. It also bound to and inhibited the toxins of venoms from several other rattlesnakes.

After tracing the evolutionary origins of FETUA-3, the researchers were surprised to find that while FETUA-3 was present in the western diamondback rattlesnake's closest Asian and South American relatives, a different protein from the same family was responsible for protecting them against venom toxins.

In other words, the rattlesnakes developed their resistance through two separate genetic events. The discovery suggests that a major evolutionary shift occurred somewhere in the species' evolutionary timeline, causing the family of inhibitors to expand and diversify throughout the Crotalus lineage.

With this new knowledge, the team gained insight into how ecological situations drive innovation and "arms races" in animals like rattlesnakes and their prey. They hope their findings will help researchers learn more about how FETUA-3 and other evolving toxin-blocking proteins may serve as ingredients for more effective snake bite treatments.

"Many current treatments using antiquated technologies and anti-venoms have drawbacks, including variation in or lack of potency, impurities that trigger side effects, and manufacturing inconsistency," said the study's lead author Fiona Ukken, a visiting faculty specialist in UMD's Department of Biology and HHMI. "But by improving our understanding of the molecular basis of venom inhibition, we can help create novel and more effective therapeutic treatments."

More information: Fiona P. Ukken et al, A novel broad spectrum venom metalloproteinase autoinhibitor in the rattlesnake Crotalus atrox evolved via a shift in paralog function, Proceedings of the National Academy of Sciences (2022). DOI: 10.1073/pnas.2214880119