Parametri antioksidacionog sistema u tkivima žaba Pelophylax esculentus kompleksa kao biomarkeri izlaganja metalima
Parameters of antioxidative defense system in tissues of the frogs from the Pelophylax esculentus complex exposure to metals
Doctoral thesis (Published version)
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Organisms are exposed to different environmental factors and contaminants. Metals are marked as a major problem due to their ubiquitous and toxicity. The oxidative stress has been suggested as one of the main mechanisms of metal toxicity effects on organisms. The redox active metals (Fe, Cu, Cr and Ni), induce oxidative stress directly through the Fenton and Haber-Weiss reactions, while the redox inactive metals (Cd, Pb, Zn, and Hg) act indirectly through alterations of the antioxidant defense system (AOS). The Pelophylax esculentus hydride complex is comprised of three semiaquatic frog species (parent species Pelophylax lessonae and Pelophylax ridibundus and their hybrid Pelophylax kl. esculentus) that coexist and can crossbreed. Frogs are distinguished by a number of properties (biphasic life- aquatic and terrestrial, complex life cycle and semipermeable skin) that make them highly susceptible to metal accumulation trough water and food chain and are therefore potentially useful bioindicator species. The aims of this doctoral dissertation were to determine: differences in metals bioaccumulation, activities and concentration of antioxidative defense system parameters and activity of cholinesterases in the liver, skin and muscle tissues of P. esculentus complex species from four localities; the changes in antioxidative defense system parameters and activity of cholinesterases induced by different metals concentration, and in the end potential usefulness of examined parameters as biomarkers of metals effects. Frogs were caught from next localities: Lake Popovica as a part of National Park “Fruška Gora”, Special Nature Reserve "Obedska Bara", Nature Park "Ponjavica" and the Grand Canal as part of the Danube-Tisa-Danube canal. Analyzed parameters of antioxidative defense system included enzymatic components: activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GR), enzyme of phase II biotransformation glutathione-S-transferase (GST), and non-enzymatic components: the concentration of glutathione (GSH) and free sulfhydryl groups (SH). The concentrations of metals (As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Zn) were measured in the water and tissues. The results of metals accumulation in liver, skin and muscle of P. esculentus complex frogs showed that P. ridibundus accumulated highest concentrations of metals, then P. esculentus and P. lessonae. Differences in metals accumulation of examined frogs could be related with some interspecies differences in life history, hibernation, prey diversity and body size. P. ridibundus is the largest and always hibernate in water, while other two have smaller body, different prey diversity and/or hibernate on land. Among the all examined AOS parameters, enzymes SOD, GSH-Px and concentration of SH groups displayed the highest level of variability. Relationship between activities of CAT and GSH-Px in liver denoted of hydride P. esculentus from its parental species. P. esculentus had higher activity of CAT and lower activity of GSH-Px in comparison to P. ridibundus and P. lessonae. The results indicate that beside differences in interaction with environment and in some physiological processes the species of this complex also differ in parameters of AOS. Intertissue differences in AOS, cholinesterase activity and metals accumulation between liver, skin and muscle of P. esculentus frogs point out liver as tissue with highest values of all parameters and highest number and concentration of metals, then followed by skin and the lowest were for muscle. The effects of different localities on P. esculentus comlpex species revealed that the concentrations of metals in tissues and water differ, this can be the result of the exposure of frogs to elevated concentrations of metals in the past, and/or to indirect accumulation of these elements via food intake. The general trend showed that the increased locality pollution is in compliance with increased metal accumulation, this trend was not observed for changes in AOS. Relationship between concentration of metals and AOS parameters showed that P. esculentus exhibited the highest number of correlations, this was followed by P. ridibundus and by P. lessonae which exhibited the lowest number of correlations. The highest effects on frogs antioxidative defense system had next redox active metals: Cr, As, Ni, Fe i Cu, and redox inactive metals: Hg i Cd. The highest number of correlations were determined for the following biomarkers: SH groups, SOD and GR. This parameters (SH groups, SOD and GR) can be used as biomarkers of metal pollution-induced oxidative stress in frogs tissues. Cholinesterase activity correlated with concentration of metals, positively with Al, Zn and Cu and negatively with As and Hg, this indicate that cholinesterase could be included in biomonitoring studies of metals effects. Research conducted in this doctoral dissertation showed: that the species of P. esculentus complex differ in concentration of accumulated metals and antioxidative defense system parameters; and that used parameters can be good biomarkers of exposure and effects of metals. In the light of these findings we can suggest the use of P. esculentus complex species as a biomonitoring species in studies of metal accumulation and metal-induced oxidative stress.
Keywords:Antioxidative defense system; Oxidative stress; Cholinesterase; Frog; Pelophylax esculentus complex; Pelophylax ridibundus; Pelophylax lessonae; Biomarkers; Biomonitoring; metals
Source:University of Belgrade, Faculty of Biology, 2016, 1-199
- Molecular and physiological biomonitoring of aerobic organisms based on the determination of biochemical biomarkers of oxidative stress (RS-173041)
APA:Prokić, M. (2016). Parametri antioksidacionog sistema u tkivima žaba Pelophylax esculentus kompleksa kao biomarkeri izlaganja metalima. University of Belgrade, Faculty of Biology.
Vancouver:Prokić M. Parametri antioksidacionog sistema u tkivima žaba Pelophylax esculentus kompleksa kao biomarkeri izlaganja metalima [dissertation]. Belgrade: University of Belgrade, Faculty of Belgrade; 2016.199 p.
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