Abstract: Nuclear speckles, a type of membrane-less nuclear body, are increasingly recognized as dynamic regulators of 3D genome organization and gene expression. My talk will explore the connection between nuclear speckles and chromatin architecture, highlighting how this association coordinates gene expression and influences pathways involved in stress responses and diseases, including cancer and neurodevelopmental disorders.

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Abstract: Nuclear speckles organize into 20-50 irregularly shaped structures on the sub-micron-scale and are enriched in serine/arginine-rich splicing factors (SRSFs) involved in mRNA splicing. Speckle-associated RNA binding proteins (RBPs) have multi-domain architectures comprising one or two folded RNA recognition motifs and intrinsically disordered regions. The molecular architectures of SRSFs map onto di- or tetra-block copolymers, driving microphase separation above a threshold concentration. Accordingly, we observe the formation of size-limited, ordered assemblies that result from a balance of attractive and repulsive interactions among the SRSF domains. Structural investigations using freeze-fracture deep-etch electron microscopy show assemblies of 30-40 nm in diameter with distinct morphologies. We also observe that microphases can associate to form sub-micron scale clusters by short-range attractive and long-range repulsive interactions that are disrupted by the presence of a co-ion. We also find that the speckle-enriched long non-coding RNA MALAT1 and the C-terminal domain of the RNA polymerase II promote microphase separation of SRSF1 by lowering the threshold concentration. This suggests a model for a molecular mechanism of interplay among the essential components involved in RNA processing.
 

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Abstract: Nectar-feeding bats defy mammalian norms by thriving on sugar-rich diets that would typically induce glucotoxicity in other mammals. Consuming up to 1.5 times their body weight in nectar daily, they offer a natural model for studying metabolic resilience. My research explores their adaptations in digestive physiology, glucose regulation, and energy metabolism that enable them to sustain extreme hyperglycemia while maintaining metabolic health. In Part 1, I will discuss the anatomical and cellular adaptations in the small intestine that support their capacity for extreme hyperglycemia. Nectar-feeding bats exhibit an elongated duodenum and increased microvilli absorption, enhancing glucose uptake. Positive selection in glucose transporters, particularly GLUT2, which shows elevated expression in the duodenum, underscores the gut’s role in regulating blood glucose levels and supporting a sugar-rich diet. Part 2 focuses on glucose homeostasis and muscle-specific adaptations. Using metabolomics, proteomics, and RNA sequencing, I identified altered insulin signaling and energy storage strategies that promote glucose utilization for immediate energy rather than glycogen synthesis. Exercise-mediated glucose homeostasis also supports their high-energy demands during flight. In Part 3, I will present molecular tools developed for this research, including stable cell lines (fibroblast and muscle), a lipidomics and metabolomics platform, and a single-cell energy metabolism profiling assay using flow cytometry. These resources reveal how bats utilize glycolysis, fatty acid oxidation, and amino acid oxidation for ATP production. Ultimately, I will discuss how these findings pave the way for uncovering novel principles of metabolic adaptation, enhancing our understanding of nectar-feeding bats and offering potential insights into strategies for managing human metabolic disorders such as diabetes and obesity.

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Abstract: Slithering, sprinting, swimming, soaring – virtually all vertebrate animal motion relies on the joints that hold our skeletons together. However, despite our ability to repair torn ACLs and replace faulty hips in humans, we have a surprisingly poor understanding of how joints work at a basic level. Disentangling how the structure of joints relates to their function is essential to explaining the anatomical basis of adaptations, attributing functional diversity to differences in morphology versus behavioral plasticity, and anticipating how animals will move and migrate through risky and ever-changing environments. In this seminar, I will discuss how integrating methods and approaches from disparate fields like paleontology, computer animation, and cartography empowers us to illuminate (1) how joints work and (2) where they come from, both developmentally and evolutionarily. In the process, I will share explorations of joint form and function from across the vertebrate body plan (from skulls to toes) and phylogenetic tree (from sharks to humans).

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Abstract: Biological nitrogen fixation, performed by the enzyme nitrogenase, supplies nearly 50% of the bioavailable nitrogen pool on Earth. However, the structural basis for its mechanism remains ambiguous. In particular, the structural intermediates involved in the enzyme’s catalytic cycle are unknown. My work is focused on the structural understanding of nitrogenase activity, isolated from A. vinelandii, and reacted under defined atmosphere environments using cryogenic electron microscopy (cryoEM). My application of anaerobic cryoEM to nitrogenase has facilitated views of its resting state as well as its state inactivated by reaction under alkaline conditions. This approach also facilitated high resolution structures of the nitrogenase MoFe-protein sampled along a time course of alkaline reaction mixtures under an acetylene atmosphere, revealing a sequence of salient active site changes. cryoEM also reveals unprecedented complexes, including that the nitrogenase associated factor T protein can recognize an alkaline inactivated MoFe-protein in vitro. The time-resolved studies illuminate structural rearrangements potentially relevant to nitrogen fixation by biological and synthetic clusters. My In situ studies of A. vinelandii reveal molecular assemblies associated with nitrogen fixation and offer a cellular context that could serve as a platform to investigate the structural and molecular events of nitrogen fixation.

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The CoS Graduate Student Committee and C-PIES invite you to a kick-off event for the "Making Science Accessible Seminar," which will take place each semester. This monthly series will feature graduate students presenting their research to the CoS community!
 
The kickoff event will feature keynote speaker Joshua Weitz of the University of Maryland, College Park. The theme of this talk will be "Communicating Science and Public Health". Weitz will also discuss his book, "Asymptomatic: The Silent Spread of COVID-19 and the Future of Pandemics."
 
The talk, which ends at 12:00 p.m., will be followed by refreshments.
 

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Abstract: Transposon-encoded genes are the most abundant and ubiquitous genes in nature. Their widespread presence across diverse genomes has driven the evolution of novel mechanisms to manipulate genetic information, enabling them to selfishly propagate their own genetic material. Remarkably, many essential cellular functions, including RNA splicing, telomere maintenance, and V(D)J recombination, all trace their origins to components originally encoded within transposable elements. Our findings reveal that the RNA-guided mechanisms of CRISPR and snoRNA-guided RNA modification also originated within transposable elements, where they facilitated their spread before being co-opted by cells for diverse RNA-guided processes. These insights highlight how the adaptive strategies of transposable elements have not only ensured their persistence but also driven the development of key molecular processes that underpin cellular function, shaping the evolution of life at the molecular level.

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Abstract: Like humans and other primates, faces are special visual objects for the paper wasp Polistes fuscatus. These wasps possess individually distinctive color patterns on their face, which they can use to visually recognize and discriminate nestmates. To investigate the neural mechanisms underlying this ability, and compare this to what is known in primate systems I presented a large set of visual stimuli, while recording extracellular activity across the brain. I ask (1) if there are neural responses that are selective to conspecific wasp images, (2) where they are located, and (3) what the tuning features of neurons with highly selective responses to conspecific wasp images are. We find broad selectivity to forward-facing wasp shapes (i.e., silhouettes) across the brain, including the optic lobe. We also find highly localized neural responses in the wasp protocerebrum selective to full images of forward-facing wasps, which have color patterns. We term these forward-facing wasp units, wasp cells. Wasp cells show idiosyncratic facial tuning, tending to prefer a subset of faces or specific facial features in our dataset. Collectively this population of wasp cells exhibited a specific location both within and across animals. Together, these cells show similar responses to more similar facial patterns such that at the population response level neural distance among faces is correlated with phenotypic facial distance, suggesting a population level encoding of facial identity by wasp cells. Despite having independently evolved vision let alone facial recognition, wasp cells show remarkable parallels to the face cells found in primates, suggesting that dedicated circuits with idiosyncratic feature tuning may be critical features of visual identity recognition. Further, this system now provides a key opportunity to study how these tuning features emerge through development and how social experience may shape the key axes of these tuning properties.

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Come join the Spatial Ecology and Paleontology Lab every Friday for Fossil Fridays! 

Become a fossil hunter and help discover how vertebrate communities have changed through time. Experience firsthand what it is like to be a paleontologist, finding and identifying new specimens! 

You will be picking and sorting 3,000 to 30,000-year-old fossil specimens from rock matrix that has been brought back from Natural Trap Cave, WY. These specimens are part of many research projects examining how the community of species living around Natural Trap Cave has changed since the extinction of the cheetahs, lions, dire wolves, mammoths, camels, horses, and other megafauna that used to live in North America. 

You are welcome to participate anytime that is convenient, with no commitment necessary. In fact, you can drop in or leave anytime within the two-hour timeframe. All are welcome, so bring your friends! 

For more information join the mailing list and/or contact Katie Slenker (kslenker3@gatech.edu) or Jenny McGuire (jmcguire@gatech.edu).

​* No T. rex actually helped with the excavations of Natural Trap Cave as their arms would be much too small.

Event Details

Come join the Spatial Ecology and Paleontology Lab every Friday for Fossil Fridays! 

Become a fossil hunter and help discover how vertebrate communities have changed through time. Experience firsthand what it is like to be a paleontologist, finding and identifying new specimens! 

You will be picking and sorting 3,000 to 30,000-year-old fossil specimens from rock matrix that has been brought back from Natural Trap Cave, WY. These specimens are part of many research projects examining how the community of species living around Natural Trap Cave has changed since the extinction of the cheetahs, lions, dire wolves, mammoths, camels, horses, and other megafauna that used to live in North America. 

You are welcome to participate anytime that is convenient, with no commitment necessary. In fact, you can drop in or leave anytime within the two-hour timeframe. All are welcome, so bring your friends! 

For more information join the mailing list and/or contact Katie Slenker (kslenker3@gatech.edu) or Jenny McGuire (jmcguire@gatech.edu).

​* No T. rex actually helped with the excavations of Natural Trap Cave as their arms would be much too small.

Event Details

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