Chapter 7: OxidaƟve Stress And AnƟoxidant Defense Mechanisms In Fishes

Abstract

Aquatic organisms are always exposed to a variety of environmental pressures. These include heavy metals and pesticides as well as industry-based waste and climate-related changes that disrupt normal cellular stability. When they are exposed to these types of stressors, there is often an increase in production of reactive oxygen species (ROS), which, in turn, creates oxidative stress. Oxidative Stress is created when there are higher levels of ROS than the cellular antioxidant defense systems can neutralize. This imbalance can damage important cellular macromolecules like lipids, proteins, and nucleic acids, and thus affects their ability to properly perform certain physiological and metabolic functions. Fishes have evolved complex antioxidant defense systems that consist of both enzymatic and nonenzymatic elements that protect them from oxidative damage. Common antioxidant enzymes are superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione S-transferase (GST).