Biomarkers early-warning response of caddisfly larvae to copper and uranium

GRAÇA, MANUEL A.S.; GONÇALVES, ANA M.M.; SOBRAL, OLÍMPIA; TAGLIAFERRO, MARINA; BERGMANN, MELISSA

Coimbra

Congreso; XIX Congreso de la Asociación Ibérica de Limnología; 2018

Asociación Ibérica de Limnologia, Universidade de Coimbra, IMAR, MARE

Copper and uranium are of environmental concern because of mining. Here, we used copper and uranium as toxic models for sublethal exposure. We determined the responses of Calamoceras marsupus larvae to exposure of uranium and copper, using a set of biomarkers.The aim of this study was to identify potential biomarkers as early warning signals in ecotoxicological studies.We hypothesized that enzymatic responses would decrease with increasing concentration of stressors. Specimens were reared in groups of 10 in 1.5 L (3 replicates) using standard moderate hard synthetic water, and fed with alder leaf discs previously stream-conditioned. We tested two treatments of copper (35 and 70 ug L?1) and uranium (25 and 50 ug L?1) plus one negative control. Laboratory bioassays were performed under constant temperature 15.7 ± 0.6°C and photoperiod (12:12 h light/dark) for 35 days. We measured the activity of five enzymes in specimens exposed to all treatments: glutathione-S-transferases (GST), acetylcholinesterase (AChE), lactate dehydrogenase (LDH), catalase (CAT), and sodium-potassium adenosine triphosphatase (Na+/K+-ATPase). All enzymes' activities were expressed as nmol min?1.mg?1 of protein, with Na+/K+-ATPase expressed as nmol of inorganic phosphate (Pi) min?1.mg?1 of protein. Catalase activity significantly increased with the increase in copper concentration (F= 12.7, df=2, 8 p= 0.003) from 0.20 ± 0.04 to 1.10 ± 0.21 nmol min?1 mg?1 protein (mean ± SE). Na+/K+-ATPase activity was affected by uranium, with lower activity (0.11 ± 0.02nM Pi min?1 mg?1 protein) at high U concentrations (50 g U L?1) and higher activity (0.15 ± 0.02nM Pi min?1 mg?1 protein) at lower concentrations (Control and 25 g U L?1; ANOVA ? F=5.49, df=2, 8, p=0.029;). No significant differences were observed in the activities of LDH, GST and AChE among the uranium or copper treatments. Changes in enzymes' activities have been used as biomarkers to assess the stress induced by chemicals and other environmental changes. Through the present research we found that CAT and Na+/K+-ATPase seem to be promising biomarkers for use as ecotoxicological endpoints for monitoring stress conditions of copper and uranium respectively, in freshwater systems.