Award: OCE-1536530

Toxins are a key mechanism the mediate the interactions of venomous organisms with potential prey and predators. Evolutionary, ecological, and physiological factors that mediate the composition and expression of toxins in these organisms are important to determine to understand the survival and distribution of venomous organisms. Cnidarians are a group of venomous aquatic organisms that express toxin genes in both the stinging cells as well as glandular cells. Like other venomous groups of animals, there is little data on the diversity of toxin genes between populations, how individuals vary in expression for each toxin depending on geographic location or environmental conditions, or how toxin genes originate and evolve in populations. In this collaborative project with Dr. Yehu Moran (Hebrew University of Jerusalem, Israel), we used a multidisciplinary approach combining field work and laboratory experiments to determine the contributions of geography, environmental variation, physiological acclimation, and genetic variation in populations on the expression and function of toxins for the cnidarian Nematostella vectensis distributed along the Atlantic and Pacific coasts of North America. We completed field collections of anemones from multiple locations and seasons along the Atlantic coast of North America to compare diet, toxin expression, and to establish lab colonies for experiments. During these collections, we deployed temperature loggers to collect data over the course of the year that yielded an in-depth characterization of temperature dynamics within and between locations. Data from the field collections supported a diet composed primarily of arthropods throughout this species’ range, significant shifts in toxin expression over season, and significant differences in toxin expression between locations. The temperature data were further utilized for design and analyses of thermal response experiments in the laboratory. In laboratory experiments, we showed that anemones from each location have significant differences in toxin expression in response to temperature, salinity, UV, and combination treatments. When combined with measurements of physiology, our results support adaptation of particular populations where individual trade-off expression of a stress response and toxin expression. We utilized the diet data to design laboratory experiments to compare the impacts of differential feeding on expression of the toxin arsenal. These results strongly suggested that expression of individual toxin genes is modulated depending on the frequency of feeding as well as the food type (example, arthropod vs. mollusk). We employed whole transcriptome sequencing and analysis of selection to identify toxin genes that had unique alleles in particular populations or where there was evidence of copy number variation. These results indicated substantial variation in copy number of a toxin gene that is highly toxic to arthropods but not vertebrates. Our comparisons identified a number of additional, previously unannotated genes closely related to this duplicated toxin gene that are rapidly evolving in both sequence composition as well as expression patterns during the life cycle. Together, our comparisons of toxin gene batteries across the geographic range of this venomous species indicate substantial variation in both toxin diversity and expression. These insights resulting from this project have been productive in closing an important gap of knowledge for the evolution and expression of venom for marine species. This project resulted in Broader Impacts related to research training, outreach to the community, and an international collaboration. Student-centered training was completed for a postdoctoral scholar as well as multiple graduate and undergraduate students throughout the life of the award. All trainees supported through this award led research in the field and the laboratory, presented at conferences, contributed to publications or led information activities for current and incoming undergraduate students majoring in STEM. Our research successes expanded opportunities for collaborative projects with local educators, including a local science museum. These activities will continue after this project through both classroom instructional lessons as well as public informational displays. The international collaboration with Dr. Moran’s lab resulted in unique training opportunities for the postdoctoral scholar as well as synergistic experiments combining field and laboratory experiments. Last Modified: 10/28/2020 Submitted by: Adam Reitzel