Oxidative Stress in Antarctic Algae and Molluscs

MALANGA G., GONZALEZ P.M., ESTEVEZ M.S., ABELE D. Y PUNTARULO S.

Reports on Polar and Marine Research. Evolution of Antarctic Fauna

Año: 2008; p. 208 - 215

Since the discovery of the importance of radical reactions in normal biological processes, there has been an explosion of research into pro-oxidant and antioxidant processes, principally in mammalian systems (Halliwell & Gutteridge 1984). The normal fate of most of the molecular oxygen consumed by animals is tetravalent reduction to water coupled to the oxidation of food and the production of energy. Partial reduction results in the formation of reactive oxygen species, including superoxide anion radical (O2-), hydroxyl radical (·OH), peroxyl radical (ROO·), alkoxyl radical (RO·), hydrogen peroxide (H2O2), singlet oxygen (1O2) and peroxynitrite (ONOO-). It has been estimated that about 1–3% of O2 consumed in animal systems is converted to ROS (Halliwell & Gutteridge 1984). Moreover, Fe can catalyze the conversion of H2O2 into ·OH, via Fenton or Haber-Weiss reactions. Of more recent interest has been reactive oxygen species production and resulting oxidative damage as a mechanism of toxicity in aquatic organisms (Livingstone 1991; Winston & Di Giulio 1991; Regoli et al. 2004). Recently, new information on the formation of reactive oxygen species by mitochondria in aquatic organisms was reported (Heise et al. 2003; Philipp et al. 2005). Reactive species produced in biological systems are detoxified by antioxidant defenses, which are broadly investigated in aquatic organisms (for rev. Abele & Puntarulo 2004; Abele et al. 2007). A physical attribute of low temperature waters is the well-mixed surface that contains higher levels of dissolved oxygen available to coldwater ectotherms than is capable of saturating warmer waters. Metabolic processes are adapted in compensation for reduced energy for enzyme activation at low temperature (Vetter & Buchholz, 1998).The aim of this work was to characterize the oxidative status of both, algae and molluscs, isolated from the nearshore waters around the Antarctic Continent and islands (Potter Cove, King George Island, Antarctic Peninsula).