- The sea anemone Anthopleura elegantissima is a model organism for the study of temperate symbiosis. Anthopleura elegantissima can engage in symbiosis with two different algal symbionts: the dinoflagellate Breviolum muscatinei and the chlorophyte Elliptochloris marina. One host enzyme that has been shown to be important in cnidarian-algal symbioses is carbonic anhydrase (CA). Carbonic anhydrase catalyzes the interconversion of bicarbonate and carbon dioxide and assists in the transportation of inorganic carbon from the host cnidarian to the photosynthetic algae. Factors such as temperature, light intensity, latitude, and size influence the productivity of symbiotic cnidarians. In this study, I hypothesized that A. elegantissima with small column crown diameters would have lower CA activity than larger animals. Anemones with a smaller column crown diameter have increased surface area to allow for the diffusion of materials, such as carbon dioxide, to occur and present a decreased need for CA activity. To test this, I measured and compared the CA activity of anemones of varying column crown diameters and developed a method to measure the surface area to volume ratio of A. elegantissima. Linear regression of carbonic anhydrase analysis showed that CA activity was negatively correlated with column crown. Additionally, the smooth regression of CA activity as a function of column crown diameter followed a bell-shaped curve, where the peak of the curve was at a crown diameter of 20 mm. These results suggest an optimal energetic size of A. elegantissima and that column crown diameter of A. elegantissima negatively influences rates of CA activity. This study furthers the knowledge of the principal enzyme CA and provides an exploration of the effects of varying physical characteristics of A. elegantissima on CA activity.
- Key Words: Anthopleura elegantissima, carbonic anhydrase, column crown diameter, surface area, volume