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Todd Adam Castoe
Professor
University of Texas Arlington
Stress response pathways and the origins of novelty: How snakes regenerate organs and regulate venom
Abstract: Understanding the processes by which novel regulatory systems evolve to drive novel phenotypes can provide valuable insight the processes and constraints that govern adaptation. Among vertebrates, snakes are an interesting model for studying the evolution of novel phenotypes because they possess a number of unique or extreme adaptations, including the ability to regenerate organ tissues at unparalleled scales, and the evolution of complex venom systems. Here we focus on these two traits to understand how snakes have co-opted regulatory systems to enable these extreme adaptive phenotypes, which we dissect using an array of functional genomics and single-cell approaches. We first discuss how our studies of regenerative organ growth in snakes have highlighted the importance of stress-response pathways in this unique organ regenerative response. We then focus on dissecting how gene regulatory networks have been re-wired to regulate snake venom, and find remarkable parallels in venom system evolution for the importance of stress response pathways. Specifically, we find evidence that two conserved vertebrate pathways, the Extracellular Signal-Regulated Kinase and Unfolded Protein Response pathways, were co-opted to regulate snake venom. Our work on venom regulation provides an insightful model for understanding how novel regulatory systems may evolve through a combination of diverse genomic processes, including tandem duplication of genes and regulatory sequences, cis-regulatory sequence seeding by transposable elements, and diverse transcriptional regulatory proteins controlled by a co-opted regulatory cascade. Taken together, our work on snakes, as well as work in other systems, highlights the potential importance of stress response mechanisms in the evolution of novel cellular and physiological traits.
Host: Professor Scott Edwards