Alison M. Roark, PhD, Furman University
PROJECT TITLE: Interspecific communication between anemones and their algal symbionts
Using a novel model organism (Exaiptasia pallida), I am exploring the mechanistic basis by which one organism (a symbiotic alga) and/or environmental contaminants can influence performance of another organism (an anemone). Specifically, I am attempting to identify and sequence novel genes that underlie this mechanism.
Given their evolutionarily ancient origins, simple body plans, well established life histories, and mutualistic interactions with photosymbionts, anthozoan cnidarians are particularly appropriate models for studying the impacts of interspecific cell signaling processes. In particular, studying the mechanisms by which endocrine-active compounds affect reproductive function of anthozoans can provide information about conserved signaling pathways that are relevant to all animals. These endocrine-active compounds include phytochemicals produced by photosymbionts, as well as exogenous environmental contaminants. Phytochemicals, such as flavonoids, are increasingly recognized as endocrine-active compounds that influence reproductive capacity of animals including humans. My proposed work using the sea anemone Exaiptasia pallida thus provides insight into the effects of plant-derived compounds on reproductive performance and the mechanisms underlying these effects in all animals, not just anthozoans.
Cnidarians are evolutionarily ancient metazoans including jellyfish, anemones, and corals, many of which form symbioses with intracellular, photosynthetic algae. It is assumed that this symbiosis primarily confers metabolic benefits to the host, with the organic products of algal photosynthesis donated to the anemone in return for inorganic nutrients. However, symbionts likely modulate host performance in other ways. For example, recent work in our laboratory demonstrated that symbiotic anemones (harboring symbionts) developed larger gonads than aposymbiotic anemones (lacking symbionts). Our working hypothesis is that symbiotic algae produce compounds that modulate the development and reproduction of their cnidarian hosts by acting on nuclear receptors. Like higher plants, free-living algae and cyanobacteria produce compounds including alkaloids, saponins, and flavonoids, many of which bind to nuclear receptors (NRs). Thus, it is likely that compounds from symbiotic algae affect host development and reproduction via such NR-mediated signaling pathways.
I have made several trips to NC State University to learn and employ a competitive receptor binding assay that leverages recombinant estrogen receptors from fish. Preliminary data provide support for my hypothesis that symbiotic algae residing within anemones produce compounds that act as ligands of the estrogen receptor. Additional data are forthcoming and will be analyzed within the next few weeks. In addition, I initiated a transcriptomics study of anemones that were exposed to estradiol. Using a 2x2 factorial design, I am simultaneously testing the differences between treated and untreated anemones and between males and females. Anemone RNA has been extracted and sequenced, and a professor affiliated with the genomics core at NC State University is currently analyzing these data. Lastly, I have begun attempting to purify and identify a putative “estrogen receptor” from anemones. Using size exclusion chromatography and affinity chromatography, I have successfully purified estrogen receptor from cow ovary tissue. The next step is to use these same methods to purify whatever receptor is capable of responding to estrogen from anemone tissues.
My SC INBRE Developmental Research Project Program grant provided all of the funding that allowed me to complete the work described above. The grant paid my stipend, as well as the stipends of two undergraduate research students during the summer of 2017. The supply and travel money has allowed me to do the bench work that I described above and to meet with my mentor several times.
March 30, 2018