PNAS Science Sessions

Getting to the root of the rhizosphere Science Sessions are brief conversations with cutting-edge researchers, National Academy members, and policymakers as they discuss topics relevant to today's scientific community. Learn the behind-the-scenes story of work published in the Proceedings of the National Academy of Sciences (PNAS), plus a broad range of scientific news about discoveries that affect the world around us. In this episode, researchers describe methods for illuminating interactions between plants and microbes in the rhizosphere. In this episode, we cover: •[00:00] Introduction •[00:35] Molly Hanlon describes a relatively inexpensive technique for rapidly imaging plant anatomy along the root axis. •[01:47] Oumeng Zhang explains a microscopy technique for imaging 3D microbial interactions with improved speed and reduced phototoxicity compared to traditional methods. •[03:07] Reinaldo Alcalde describes the results of his and Oumeng's approach. •[04:08] Victoria Orphan used synthetic cryolite to create a transparent, soil-like scaffold, allowing belowground microbial processes to be visualized. •[05:31] Final thoughts and conclusion. About Our Guests: Molly Hanlon Senior Research Scientist Donald Danforth Plant Science Center Oumeng Zhang Assistant Professor Texas A&M University Reinaldo Alcalde Senior Postdoctoral Scholar California Institute of Technology Victoria Orphan James Irvine Professor of Environmental Science and Geobiology California Institute of Technology View related content here: https://www.sciencedirect.com/science/article/pii/S2643651525001566 https://www.pnas.org/doi/10.1073/pnas.2403122121 https://academic.oup.com/pnasnexus/article/4/5/pgaf118/8114130 Follow us on Spotify, Apple Podcasts, or wherever you get your podcasts for more captivating discussions on scientific breakthroughs! Visit Science Sessions on PNAS.org: https://www.pnas.org/about/science-sessions-podcast Follow PNAS: Twitter/X Facebook LinkedIn YouTube Sign up the PNAS Highlights newsletter

Economic costs of measles outbreaks Science Sessions are brief conversations with cutting-edge researchers, National Academy members, and policymakers as they discuss topics relevant to today's scientific community. Learn the behind-the-scenes story of work published in the Proceedings of the National Academy of Sciences (PNAS), plus a broad range of scientific news about discoveries that affect the world around us. In this episode, Alison Galvani explains the costs of waning measles vaccination rates. In this episode, we cover: •[00:00] Introduction. •[01:12] Epidemiologist Alison Galvani introduces the MMR vaccine and describes its efficacy. •[02:23] Galvani recounts the changes in MMR vaccination rates in recent years. •[03:56] She describes how the researchers modeled the economic impacts of measles outbreaks. •[05:49] Galvani talks about what the economic impacts look like in everyday life. •[06:39] She talks about the findings regarding the costs of measles outbreaks in 2025. •[07:06] Galvani enumerates the costs of a percentage decrease in vaccination rates. •[08:06] She lists the takeaways from the study, including the disproportionate societal effects of a small decrease in vaccination rates. •[08:58] She lists the caveats and limitations of the study. •[10:13] Conclusion. About Our Guest: Alison Galvani Director, Center of Infectious Disease Modeling and Analysis Yale School of Public Health View related content here: https://www.pnas.org/doi/abs/10.1073/pnas.2605971123 Follow us on Spotify, Apple Podcasts, or wherever you get your podcasts for more captivating discussions on scientific breakthroughs! Visit Science Sessions on PNAS.org: https://www.pnas.org/about/science-sessions-podcast Follow PNAS: Twitter/X Facebook LinkedIn YouTube Sign up for the PNAS Highlights newsletter

Evidence of early plate tectonics Science Sessions are brief conversations with cutting-edge researchers, National Academy members, and policymakers as they discuss topics relevant to today's scientific community. Learn the behind-the-scenes story of work published in the Proceedings of the National Academy of Sciences (PNAS), plus a broad range of scientific news about discoveries that affect the world around us. In this episode, Brad Peters explores what we can learn from the journey of sediments from the early Earth through the rock cycle. In this episode, we cover: •[00:00] Introduction. •[01:04] Geochemist Brad Peters tells us about the Marquesas Archipelago and why is it a place of interest for geologists. •[02:42] He recounts evidence suggesting that one component of the Marquesas lavas was recycled sediment from the early Earth. •[04:59] Peters walks us through the likely journey of this sediment from its origins to its eruption on the Marquesas Archipelago. •[06:24] He explains what this lava tells us about the tectonic processes that were active four billion years ago. •[07:43] Peters summarizes how this result is different than what we previously thought about the inception of plate tectonics. •[08:19] He talks about what the results mean for the story of the early Earth. •[09:13] He lists the caveats and limitations of the study. •[10:09] Conclusion. About Our Guest: Brad Peters Postdoctoral researcher ETH Zurich View related content here: https://www.pnas.org/doi/abs/10.1073/pnas.2500506123 Follow us on Spotify, Apple Podcasts, or wherever you get your podcasts for more captivating discussions on scientific breakthroughs! Visit Science Sessions on PNAS.org: https://www.pnas.org/about/science-sessions-podcast Follow PNAS: Twitter/X Facebook LinkedIn YouTube Sign up for the PNAS Highlights newsletter

Domestication of wheat Science Sessions are brief conversations with cutting-edge researchers, National Academy members, and policymakers as they discuss topics relevant to today's scientific community. Learn the behind-the-scenes story of work published in the Proceedings of the National Academy of Sciences (PNAS), plus a broad range of scientific news about discoveries that affect the world around us. In this episode, David Lordkipanidze recounts archaeological findings from Georgia expanding the history of bread wheat. In this episode, we cover: •[00:00] Introduction. •[00:51] Archaeologist and paleobotanist David Lordkipanidze tells about the archaeological sites where wheat samples were found. •[02:53] He talks about methods for identifying plant grains among archeological artifacts. •[04:49] Lordkipanidze explains the significance of finding bread wheat and goat grass grains together. •[06:45] He talks about how the findings change the origin story of bread wheat. •[08:28] He lists the caveats and limitations of the study. •[09:24] Conclusion. About Our Guest: David Lordkipanidze Director Georgia National Museum View related content here: https://www.pnas.org/doi/10.1073/pnas.2537697123 Follow us on Spotify, Apple Podcasts, or wherever you get your podcasts for more captivating discussions on scientific breakthroughs! Visit Science Sessions on PNAS.org: https://www.pnas.org/about/science-sessions-podcast Follow PNAS: Twitter/X Facebook LinkedIn YouTube Sign up for the PNAS Highlights newsletter

Xiaofeng Li, an oceanographer who built a machine-learning model to forecast rapid tropical cyclone intensification, discusses his approach. He explains using environmental, satellite, and storm history data to isolate signals. The model achieves high detection with low false alarms. The conversation highlights AI methods that boost forecast reliability and operational usefulness.

Cryopreservation of brain tissue structures Science Sessions are brief conversations with cutting-edge researchers, National Academy members, and policymakers as they discuss topics relevant to today's scientific community. Learn the behind-the-scenes story of work published in the Proceedings of the National Academy of Sciences (PNAS), plus a broad range of scientific news about discoveries that affect the world around us. In this episode, Alexander German explains how to cryopreserve brain tissue through vitrification. In this episode, we cover: •[00:00] Introduction. •[01:14] Physician-scientist Alexander German introduces the problems with traditional cryopreservation methods. •[02:22] German explains why we cryopreserve tissue. •[03:23] He tells about vitrification and why it's different than traditional cryopreservation. •[04:13] German explains why osmotic stress is a concern in cryopreservation. •[04:51] He talks about how the protocol minimizes damage to brain structures and tissues. •[06:26] He recounts the tests they performed to evaluate the preservation and function of the vitrified tissues. •[07:03] German describes the usefulness of vitrification. •[08:48] He lists the caveats and limitations of the study. •[10:03] Conclusion. About Our Guest: Alexander German Resident Universität Erlangen-Nürnberg View related content here: https://www.pnas.org/doi/full/10.1073/pnas.2516848123 Follow us on Spotify, Apple Podcasts, or wherever you get your podcasts for more captivating discussions on scientific breakthroughs! Visit Science Sessions on PNAS.org: https://www.pnas.org/about/science-sessions-podcast Follow PNAS: Twitter/X Facebook LinkedIn YouTube Sign up for the PNAS Highlights newsletter

The lost forests of Doggerland Science Sessions are brief conversations with cutting-edge researchers, National Academy members, and policymakers as they discuss topics relevant to today's scientific community. Learn the behind-the-scenes story of work published in the Proceedings of the National Academy of Sciences (PNAS), plus a broad range of scientific news about discoveries that affect the world around us. In this episode, Robin Allaby explores the paleoecology of the submerged area known as Doggerland. In this episode, we cover: •[00:00] Introduction. •[01:10] Evolutionary biologist Robin Allaby introduces the location of Doggerland and history of its exploration. •[02:58] He introduces sedimentary DNA, including how it can be used to reconstruct paleoecology. •[03:43] Allaby describes the methods of the study. •[05:18] He introduces the primary findings about the plant and animal life of Doggerland. •[06:14] He describes the surprising find of Pterocarya in Doggerland. •[08:07] Allaby discusses the habitability of Doggerland for Mesolithic societies. •[09:38] He lists the caveats and limitations of the study. •[10:13] Conclusion. About Our Guest: Robin Allaby Professor University of Warwick View related content here: https://www.pnas.org/doi/full/10.1073/pnas.2508402123 Follow us on Spotify, Apple Podcasts, or wherever you get your podcasts for more captivating discussions on scientific breakthroughs! Visit Science Sessions on PNAS.org: https://www.pnas.org/about/science-sessions-podcast Follow PNAS: Twitter/X Facebook LinkedIn YouTube Sign up for the PNAS Highlights newsletter

Generative AI and scientific journals Science Sessions are brief conversations with cutting-edge researchers, National Academy members, and policymakers as they discuss topics relevant to today's scientific community. Learn the behind-the-scenes story of work published in the Proceedings of the National Academy of Sciences (PNAS), plus a broad range of scientific news about discoveries that affect the world around us. In this episode, Yi Bu explores how generative AI has changed academic publishing. In this episode, we cover: •[00:00] Introduction. •[00:50] Computational social scientist Yi Bu tells about the policies academic journals have introduced to address generative AI. •[02:17] Bu describes the dataset he analyzed and his findings regarding journals' policies. •[04:07] He answers the question: Did journal policies have any effect on AI usage? •[05:39] Bu talks about how the rate of AI disclosure compares with estimates of probable AI use. •[06:53] He explains the takeaway for journal editors and the scientific community at large. •[07:27] He lists the caveats and limitations of the study. •[10:11] Conclusion. About Our Guest: Yi Bu Assistant Professor Peking University View related content here: https://www.pnas.org/doi/abs/10.1073/pnas.2526734123 Follow us on Spotify, Apple Podcasts, or wherever you get your podcasts for more captivating discussions on scientific breakthroughs! Visit Science Sessions on PNAS.org: https://www.pnas.org/about/science-sessions-podcast Follow PNAS: Twitter/X Facebook LinkedIn YouTube Sign up for the PNAS Highlights newsletter

Genomics of the Golden Horde Science Sessions are brief conversations with cutting-edge researchers, National Academy members, and policymakers as they discuss topics relevant to today's scientific community. Learn the behind-the-scenes story of work published in the Proceedings of the National Academy of Sciences (PNAS), plus a broad range of scientific news about discoveries that affect the world around us. In this episode, Ayken Askapuli explains genomic insights into the ancestors and descendants of the Golden Horde. In this episode, we cover: •[00:00] Introduction. •[00:56] Population geneticist Ayken Askapuli introduces the Golden Horde. •[02:01] He describes the individuals in the mausoleums whose DNA the team sampled. •[04:11] Askapuli explains findings about the modern populations the Golden Horde individuals were related to. •[05:08] He then explains findings about the Y chromosome characteristics of the Golden Horde individuals. •[06:14] Askapuli talks about what the results say about the ancestry of the Golden Horde. •[06:48] He describes how the results aid understanding of population genetics in central Eurasia. •[08:10] He lists the caveats and limitations of the study. •[09:53] Conclusion. About Our Guest: Ayken Askapuli PhD candidate University of Wisconsin-Madison View related content here: https://www.pnas.org/doi/abs/10.1073/pnas.2531003123 Follow us on Spotify, Apple Podcasts, or wherever you get your podcasts for more captivating discussions on scientific breakthroughs! Visit Science Sessions on PNAS.org: https://www.pnas.org/about/science-sessions-podcast Follow PNAS: Twitter/X Facebook LinkedIn YouTube Sign up for the PNAS Highlights newsletter

How much carbon dioxide concrete can absorb Science Sessions are brief conversations with cutting-edge researchers, National Academy members, and policymakers as they discuss topics relevant to today's scientific community. Learn the behind-the-scenes story of work published in the Proceedings of the National Academy of Sciences (PNAS), plus a broad range of scientific news about discoveries that affect the world around us. In this episode, Hessam Azarijafari explains the extent to which concrete can absorb carbon dioxide over its lifecycle. In this episode, we cover: •[00:00] Introduction. •[00:56] Construction engineer Hessam Azarijafari introduces us to the recipe for concrete. •[01:41] He explains how concrete absorbs carbon dioxide throughout its lifespan, and why this absorption is important. •[02:52] Azarijafari talks about the background of the study. •[03:45] He describes the model built for the study and the data source. •[05:59] Azarijafari tells the study's results, including variation in absorption across sectors and between the US and Mexico. •[07:41] He compares this analysis with previous estimates of concrete carbon absorption. •[08:25] He explains the takeaways from this study for policymakers and the concrete industry. •[09:36] He lists the caveats and limitations of the study. •[10:19] Conclusion. About Our Guest: Hessam Azarijafari Research Scientist Massachusetts Institute of Technology View related content here: https://www.pnas.org/doi/abs/10.1073/pnas.2515116122 Follow us on Spotify, Apple Podcasts, or wherever you get your podcasts for more captivating discussions on scientific breakthroughs! Visit Science Sessions on PNAS.org: https://www.pnas.org/about/science-sessions-podcast Follow PNAS: Twitter/X Facebook LinkedIn YouTube Sign up for the PNAS Highlights newsletter