Antioxidant response and metal accumulation in tissues of Iberian green frogs (Pelophylax perezi) inhabiting a deactivated uranium mine

Abstract

Human mining activities tend often to generate greatly impacted areas which remain contaminated for long periods of time, giving rise to extreme habitats. Mining sites are usually characterized for the production of metal rich effluents with very low pH. In this work we analyzed physical and chemical parameters of water from a deactivated uranium mine pond (M) and a reference site (REF) as well as their metal content. Furthermore, we determined and compared metal accumulation in liver, kidney, bones, muscle and skin of Pelophylax perezi from REF with P. perezi from M. We also determined the enzymatic activities of glutathione-S-transferases (GSTs), catalase (CAT), glutathione reductase (Gred), and glutathione peroxidase (GPx; both selenium-dependent and selenium-independent) in liver, kidney, lung and heart. Additionally, lipoperoxidation (LPO) was also assessed in the same tissues via thiobarbituric acid reactive substances (TBARS) assay and lactate dehydrogenase (LDH) activity was determined in muscle. Our results revealed that the majority of metals were in higher concentrations in tissues of organisms from M. This trend was especially evident for U whose content reached a difference of 1350 fold between REF and M organisms. None of the organs tested for antioxidant defenses revealed LPO, nonetheless, with exception for liver, all organs from the M frogs presented increased total GPx activity and selenium-dependent GPx. However, this response was significant only for the lung, probably as a consequence of the significant inhibition of CAT upstream and to cope with the subsequent increase in H(2)O(2). Lungs were the organs displaying greater responsiveness of the anti-oxidant stress system in frogs from the uranium mine area.

Copper sulphate impact on the antioxidant defence system of the marine bivalves Cerastoderma edule and Scrobicularia plana

“…The samples were sampled to plastic bottles and acidified with nitric acid Pro Analysis MERCK® (65%) to a pH bellow 2, to prevent metal adsorption, according to the protocol described by Marques et al . 25 , to then be analysed, at the laboratory, to quantify copper concentrations. The tissues were dried at 105 °C by about 24 hours and then weighted and digested in closed falcon tubes with 3 ml HNO 3 (Pro Analysis MERCK®, 65%), at 60 °C, on the oven, by about 8 hours to copper quantification.…”

“…The volume was completed to 5 ml per sample with Milli-Q® water (18.2 ῼ), according to Marques et al . 25 .…”

Nickel toxicity in wood frog tadpoles: Bioaccumulation and sublethal effects on body condition, food consumption, activity, and chemosensory function

“…Wood frog tadpoles accumulated whole-body Ni with increasing aqueous Ni concentration. Few researchers examined accumulation of Ni by amphibians in controlled experiments; they rather documented the concentration of Ni in amphibians from contaminated sites in situ that indicated that several amphibian species can accumulate Ni from contaminated sites (Sparling and Lowe 1996;Venne et al 2006;Sohani and Samant 2010;Marques et al 2011;Taiwo et al 2014). In our study, the whole-body Ni concentration never came into equilibrium with the exposure environment based on the log-linear uptake relationship (Figure 1) and BCF values (Table 2).…”

Evaluation of the use of Leptodactylus ocellatus (Anura: Leptodactylidae) frog tissues as bioindicator of metal contamination in Contas River, Northeastern Brazil

“…Schuytema and Nebeker (1999) analyzed the growth and death of amphibian species Rana aurora exposed to ammonium nitrate and sodium nitrate and tadpoles of the species Xenopus laevis and Pseudacris regilla exposed to urea. Marques et al (2011) studied the contamination of amphibian species Pelophylax perezi in an uranium mine and a non-anthropic reference site and found that some elements may be up to 1000 times more concentrated in mining areas. Nations et al (2011) evaluated the acute effects of ZnO, TiO 2 , Fe 2 O 3 , and CuO in Xenopus laevis and demonstrated that at trace concentrations these compounds were not harmful to the organisms studied.…”