Cold adaptation and oxidative metabolism of Antarctic fish

Abstract

A well known characteristic of the oxidative metabolism of Antarctic fishes is their preferential utilization of the lipid metabolic pathway. Since oxidative metabolism may lead to a significant production of oxygen-derived free radicals, which may have several harmful effects on biological structures, it seemed worthwhile to investigate the presence, in various tissues from different Antarctic fishes, of those ions and molecules which are known to be at the basis of the antioxidant defense mechanisms. Hence, the Coenzyme Q and trace elements (selenium, copper, and zinc) content of tissues from several Antarctic fishes was determined and compared with that of non-Antarctic species. Unlike temperate fishes, in which the Coenzyme Q is Q 10 , all the Antarctic species examined displayed the homolog Q 9 form. This particular finding was related to the difference in the crystallisation temperature existing between Coenzyme Q 10 and Coenzyme Q 9 . Taken together, the results indicate a higher level of antioxidant defenses for Antarctic species, with respect to temperate fishes. This may be considered a stimulating basis for further studies on the adaptation mechanisms centered on the oxidative metabolism of organisms living in extreme environments.

Coenzyme Q in Thraustochytrium sp. RT2316-16: Effect of the Medium Composition

“…A relationship has been suggested to exist between the length of the hydrophobic polyisoprenoid chain of CoQ and the hydrophobicity of the membrane of the organism synthesizing CoQ [58]. Furthermore, the difference between the crystallization temperatures of CoQ 9 (0.5 • C) and CoQ 10 (9.7 • C) might explain the preponderance of CoQ 9 in the organisms adapted to cold environments [61]. In this context, it is worth noting that the thraustochytrid RT2316-16 was isolated from the cold Antarctic environment, although how the temperature might affect the CoQ content of its biomass is yet to be assessed.…”