The activities of total superoxide dismutase (Tot-SOD), manganese-containing superoxide dismutase (Mn-SOD), copper zinc containing superoxide dismutase (Cu/Zn-SOD) and catalase (CAT) protein concentration, as well as protein and SOD electrophoretic profiles in the liver and muscle of barbel (Barbus barbus) and its intestinal parasite Pomphoryinchus laevis from the river Danube, within the suburban area of Belgrade, Serbia (the stretch between Višnjica and Grocka) in spring and summer were investigated. Specific activities of Tot-SOD, Mn-SOD, Cu/Zn-SOD were higher in spring, while specific CAT activity was higher in summer in all investigated samples. Temperature influence on the antioxidant defense enzymes in barbel tissue and in its intestinal parasite Pomphoryinchus laevis, as well as seasonal patterns, are evident. Our work represents the first study of SOD and CAT activities in the barbel and its intestinal parasites and shows that barbel and acanthocephalans are very useful for biomonitoring studies in aquatic ecosystems

We investigated the potential use of the antioxidant defense enzymes in freshwater mussel (Unio pictorum) as biomarkers of oxidative stress. The enzymatic activities of superoxide dismutase (SOD, EC 1.15.1.1) and catalase (CAT, EC 1.11.1.6), total protein concentration in addition to protein and SOD electrophoretic profiles were examined in the digestive gland and gills of the freshwater bivalve Unio pictorum at two localities on the River Sava. The differences between SOD and CAT activities in examined tissues of freshwater bivalve Unio pictorum reflect dissimilar metabolic and antioxidative activities and this can be the result of both tissue or locality specificities and diverse ecophysiological influences on the organism

The river snail (Viviparus acerosus) from the Velika Morava River, Serbia was chosen in our study in order to determine seasonal changes in oxidative stress biomarkers between July (summer) and September (autumn). The activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GR) and the phase II biotransformation enzyme glutathione-S-transferase (GST), as well as the concentration of total glutathione (GSH), were examined in the whole body of the river snails. The obtained results show significantly higher activities of CAT, GSH-Px, GR and biotransformation phase II enzyme GST in September compared to July, while the GSH concentration was lower. There was no general trend in the seasonal changes in the activity of SOD. The presented data show that animals in their natural environment are exposed to constant fluctuations of environmental conditions that could cause antioxidants to exhibit seasonal variations. This fact should be considered as an important variable in the interpretation of results in biomonitoring studies. [Acknowledgments. This study was supported by the Ministry of Education and Science of the Republic of Serbia, Grants Nos. 173041 and 173025

The aim of this study was to investigate the activity of oxidative stress biomarkers (total superoxide dismutase - Tot SOD; and copper and zinc-containing superoxide dismutase - CuZn SOD; manganese-containing superoxide dismutase - Mn SOD; catalase - CAT; glutathione peroxidase - GSH-Px; and glutathione reductase - GR), as well as the biotransformation phase II enzyme glutathione-S-transferase (GST), in the white muscle of red mullet (Mullus barbatus L.) at Platamuni (PL) and Valdanos (VAL) in the Adriatic Sea during the winter and spring seasons. The obtained results show both site and seasonal influences on the investigated parameters, with lower enzyme activities at VAL than at PL and in spring than in winter

Specimens of a marine freshwater fish - hake (Merluccius merluccius L.) - were collected at the localities of Platamuni and Valdanos (Montenegro, South Adriatic) in the spring of 2003. Our results showed higher concentrations of LPO, Vit C, and Vit E in the liver in comparison with white muscle. The concentration of LPOin both tissues was higher, while that of Vit E was lower at Valdanos compared to Platamuni. These differences in parameters of oxidative stress are partly due to differences in temperature and the concentrations of nitrites, nitrates, and detergents in the waters of Valdanos compared to Platamuni