ANTIOXIDATIVE RESPONSES IN Tubifex tubifex AGAINST THALLIUM INDUCED OXIDATIVE STRESS
Öz
Thallium (Tl) impact on living systems has become an important issue in recent years. However very few data exist about the consequences of Tl exposure in freshwater aquatic systems. The aim of the present study is to investigate alterations in the levels of antioxidative biomarkers (metallothionein (MT), total glutathione (GSH), glutathione peroxidase (GPx), glutathione S-transferase (GST) and catalase (CAT)) in the aquatic oligochaete Tubifex tubifex, in response to sublethal doses of Tl. Experimental groups were exposed to thallium acetate at 0.25, 0.5 and 1 µg l-1 concentrations during 7 or 15 days. MT levels were observed to be interestingly decreased. 0.25 µg l-1 concentration had no effect on total GSH, GPx and GST activities while 0.5 and 1 µg l-1 concentrations induced total GSH and GPx activitiy after 7 days. Longer exposure time resulted in a decrease in total GSH along with GPx and GST activities at all concentrations of Tl. Despite the significant elevation of CAT activity in all experimental groups, lipid peroxidation (LP) was observed to be induced depending on the increasing exposure concentration and time. The results suggested the possible mechanism of action in the antioxidant system of T. tubifex in response to Tl induced oxidative stress (OS) and provide useful information for the future evaluation of Tl impact on aquatic ecosystems.
Anahtar Kelimeler
Thallium,Tubifex tubfex,Oxidative stres,Antioxidants,Lipid peroxidation
Kaynakça
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