York, J. M. | Search bioRxiv

bioRxiv2023

A potential cost of evolving epibatidine resistance in poison frogs

BackgroundSome poison arrow frogs sequester the toxin epibatidine as a defense against predators. We previously identified a single amino acid substitution (S108C) at a highly conserved site in a neuronal nicotinic acetylcholine receptor (nAChR) {beta}2 subunit that prevents epibatidine from binding to this receptor. When placed in a homologous mammalian nAChR this substitution minimized epibatidine binding but also perturbed acetylcholine binding, a clear cost. However, in the nAChRs of poison arrow frogs, this substitution appeared to have no detrimental effect on acetylcholine binding and, thus, appeared cost-free. ResultsThe introduction of S108C into the 4{beta}2 nAChRs of non-dendrobatid frogs also does not affect ACh sensitivity, when these receptors are expressed in Xenopus laevis oocytes. However, 4{beta}2 nAChRs with C108 had a decreased magnitude of neurotransmitter-induced currents in all species tested (Epipedobates anthonyi, non-dendrobatid frogs, as well as human), compared with 4{beta}2 nAChRs with the conserved S108. Immunolabeling of frog or human 4{beta}2 nAChRs in the plasma membrane using radiolabeled antibody against the {beta}2 nAChR subunit shows that C108 significantly decreased the number of cell-surface 4{beta}2 nAChRs, compared with S108. ConclusionsWhile S108C protects these species against sequestered epibatidine, it incurs a potential physiological cost of disrupted 4{beta}2 nAChR function. These results may explain the high conservation of a serine at this site in vertebrates, as well as provide an example of a tradeoff between beneficial and deleterious effects of an evolutionary change. They also provide important clues for future work on assembly and trafficking of this important neurotransmitter receptor.

evolutionary biology↗

bioRxiv2019

Using a Systems Change Framework to Evaluate Academic Equity & Climate Efforts in a Graduate Program

While academia is moving forward in terms of diversifying recruitment of undergraduate and graduate students, diverse representation is still not found across the academic hierarchy. At the graduate level, new discussions are emerging around efforts to improve the experiences of women and underrepresented minorities through inclusive graduate programming. Inclusive graduate programs are that which actively center and prioritize support for diverse experiences, identities, career goals, and perspectives, from recruitment through graduation. Establishing regular and rigorous evaluation of equity and inclusion efforts and needs is a critical component of this work. This is recognized by funding agencies that increasingly require reporting on inclusion efforts; here we suggest use of a systems change framework for these evaluations. A systems change approach emphasizes three levels: explicit change (e.g. policies), semi-explicit change (e.g. power dynamics), and implicit change (e.g. biases). We use the Ecology, Evolution, and Behavior (EEB) PhD Program at the University of Texas at Austin in an exercise to (1) identify areas of concern regarding inclusive programming voiced by graduate students, (2) categorize efforts to address these concerns, and (3) integrating and evaluating which areas of the systems change framework show the greatest progress or potential for progress. We argue this framework is particularly useful for academic systems as they are complex, composed of variable individuals, and must address diverse stakeholder needs.

scientific communication and education↗