- The symbiotic relationship between cnidarians and algae is important to the marine ecosystem due to the photosynthesis produced by the algae and the coral reefs that cnidarians provide. Corals provide their algal partner with a safe home and the algae supply the cnidarians with inorganic materials as a food source. The algal symbionts are intracellular, residing inside of a host-derived vesicle called a symbiosome. However, during ocean warming, the symbiotic relationship can break down causing cnidarians to lose their symbiotic algae (commonly referred to as coral bleaching). Here, we investigate the cellular mechanisms that may cause bleaching (i.e., loss of symbiotic algae). This project focuses on a symbiotic-specific gene, called NADPH oxidase (NOX) protein, and its role in host degradation of the algae. We hypothesized NOX is located at the symbiosome membrane during heat stress and the NOX complex is not activated until the activator, p67phox, binds to the NOX complex, resulting in an oxidative burst. We predicted that NOX expression will be higher in algal loss and heat stressed situations as compared to a control group of Aiptasia kept at ambient temperature. We will use the sea anemone, Aiptasia, as a model organism for corals due to the faster regeneration time, easier accessibility, and easier husbandry care. The first step in this process is to dissect anemones small enough for microscopy. Next, we heat stress the anemones to induce algal loss (bleaching) and quantify algal loss using autofluorescence. Finally, to determine the location of the NOX protein, we will use antibody staining.