Antioxidant defense enzyme activities in the liver of red mullet (Mullus barbatus L.) from the Adriatic Sea: The effects of locality and season

The effects of locality and season on the activity of antioxidant defense enzymes (ADE), namely, total superoxide dismutase (Tot SOD), copper zinc containing superoxide dismutase (CuZn SOD), manganese containing superoxide dismutase (Mn SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GR) and biotransformation phase II enzyme glutathione-S-transferase (GST) in the liver of red mullet (Mullus barbatus L.) from the Platamuni and Valdanos localities (Adriatic Sea) in winter and spring season were studied. All enzyme activities were expressed as specific (units/mg proteins) and total (units/g wet tissue) ones. Our results show increased specific and total activities of almost all investigated ADE in winter, with respect to the spring, both in Platamuni and Valdanos. The opposite effect was obtained for the specific and total GSH-Px activity at both localities. The presented results show that the activity of investigated ADE depends mainly on the analyzed season. Also, it was confirmed that biotransformation phase II enzyme GST is the most sensitive indicator of environmental status in the liver of red mullet. The results of Principal Component Analysis (PCA) based on correlations show similar trends in the positive and negative correlations between specific and total ADE in both seasons. At the same time, examination of seasonal patterns of ADE revealed clear differences between the investigated localities in winter and spring for specific and total activities. From the presented results, it can be concluded that seasonal variations of ADE should be incorporated into interpretation of further biomonitoring studies of red mullet.nul