Effect of osmotic stress on protein concentration and antioxidant enzymes activity in the organism of nine-spined stickleback Pungitius pungitius (Gasterosteidae) from the White Sea Basin

Abstract

The life cycle of P. pungitius (Linnaeus, 1758) includes migrations from the open sea to coastal and freshwater biotopes which are accompanied by osmotic shock and following oxidative stress in fish. The complex multilevel antioxidant system (AOS) includes low-molecular compounds and specific enzymes and protects cells from reactive oxygen species, hydrogen peroxide, and hydroperoxides generated in excess. To study the response of AOS components to oxidative stress caused by acute salinity changes, nine-spined stickleback juveniles from the White Sea estuary were alternately exposed to hypo- and hyperosmotic conditions. In the tissues of stickleback transferred from saltwater to freshwater for 1 and 24 hours a decrease in water-soluble protein concentration and catalase activity was shown. The increased guaiacol-dependent peroxidase activity in estuary fish successively exposed to fresh and saltwater for 24 hours was also observed. Under studied exposures, no changes in the activities of superoxide dismutase and glutathione S-transferase were detected. The involvement of AOS enzymes, particularly neutralizing hydrogen peroxide by the peroxidase-dependent pathway, in the response to acute changes in ambient salinity was described in White sea P. pungitius for the first time. The results of our study provide the new data on the AOS response to hypo- and hyperosmotic stress in euryhaline fish species. The obtained data could be used in predicting the possibility of industrial fish farming in the White Sea-Barents basin.