Thermal Stress and Antioxidant Activity in Sea Anemones, Exaiptasia pallida

• Published in: The FASEB Journal
• Main Authors: Rideb, Jernie Rae, Varghese, Anabel, Nguyen, Thien, Pham, Kim, Nguyen, Isabelle, Herrera, Nadia, Bagnall, Ruth Ann, Rosell, Rosemarie
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2022
• Subjects: Ocean acidification
• Online Access: http://dx.doi.org/10.1096/fasebj.2022.36.s1.r6315

When exposed to stress, coral reefs undergo bleaching, a process in which the host‐symbiont relationship is disrupted. Stressors can be environmental including ocean acidification, exposure to ultraviolet radiation, or rising ocean temperatures due to global warming. The sea anemone, Exaiptasia pallida , serves as a model organism of coral reef biology since both species share symbiotic relationships with their algal symbionts and can undergo bleaching resulting in the expulsion of algal symbionts. This is the ultimate phenotypic result of high levels of stress experienced by the coral reef. Stress factors can lead to an increase in free radicals, like reactive oxygen species (ROS), that will adversely alter lipids, proteins, and DNA and trigger bleaching events. Although oxygen free radicals are natural by‐products of metabolic processes in most organisms, they are closely regulated through endogenous systems, such as antioxidants like superoxide dismutase (SOD). We hypothesized that as temperatures increase, the levels of SOD activity in the sea anemone will increase over time. We used commercially available E. pallida to establish a ‘stock’ aquaria to rear anemones under optimal conditions for at least two weeks before use. The stock aquaria were maintained at 28‐30% salinity at 22℃ during a 12‐hour light/dark period, at a pH of approximately 8.4, with low levels nitrate, nitrite, and ammonia (checked weekly). E. pallida were moved from the stock tank and placed into one of three identical tanks, maintained at increasing temperatures of 22℃ (control), 24℃, and 29℃. We sampled 5 anemones from each tank at two‐week intervals for 8 weeks. Seawater was removed by aspiration, anemones were weighed, flash‐frozen in liquid nitrogen, and stored at ‐80℃. We extracted proteins from each sample by homogenization on ice. For each sample, total protein concentrations were established with a Bradford assay and SOD concentration in units of activity was established with a commercially available SOD assay. By observation, ...