Metallothionein induction by an essential metal (Zn) in a freshwater decapod crustacean of South America, Palaemonetes argentinus

BERTRAND, L.; MONFERRÁN, M; METAIS, I. ; MOUNEYRAC, C.; AMÉ, M.V

Basel

Congreso; SETAC Europe 24th Annual Meeting; 2014

Aquatic invertebrates take up and accumulate trace metals even when both, essential and nonessential, have the potential to cause toxic effects. The aim of this study was to investigate the potential use of metallothioneins (MTs) as biomarkers of metal contamination in native shrimp Palaemonetes argentinus, a species of ecologic interest because of its wide distribution in different country of South America. Organisms have been exposed at different environmental concentrations of Zinc (ZnSO 4 .7H 2 O): controls (not metal exposed), shrimps exposed to 5 μg Zn L-1 (7.65 x10-5 mM), 50 μg Zn L-1 (7.65 x10-4 mM) and 500 μg Zn L-1 (7.65 x10-3 mM). A significant Zn accumulation has been observed in different body sectors. In cephalothorax, at 500 μg Zn L-1 (369.14 ± 49.75 μg Zn g-1dw, p< 0.0001) and 50 μg Zn L-1 (216.65 ± 65.99 μg Zn g-1dw, p< 0.01) the concentration of metal significantly increased compared to other conditions (Control= 147.08 ± 21.50 μg Zn g-1dw; 5 μg Zn L-1=144.74 ± 22.54 μg Zn g-1dw). Greater accumulation occurred in cephalothorax compared to abdomen, especially at higher exposure concentration (500 μg Zn L-1). Subcellular metal distribution was different in cephalothorax and abdomen. In cephalothorax, Zn was equally distributed between the soluble and the insoluble fractions whereas in abdomen, when total Zn increased, insoluble metal increased more markedly than the soluble one. Cytosolic levels increased greater in the cephalothorax than in the abdomen of shrimps exposed to 500 μg Zn L-1 compared to control. Cephalothorax of organisms exposed to the greater (500 μg Zn L-1) concentration of Zn showed a significant increase in MT levels (0.651 ± 0.025 mg MTs g-1ww) compared to cephalothorax from control and 5 μg Zn L-1 organisms (0.518 ± 0.045 mg MTs g-1ww and 0.516 ± 0.085 mg MT g-1ww respectively, p< 0.05). Conversely, no induction of MTs was observed in the abdomen of P. argentinus even at the highest exposure concentration (p>0.05). A positive and significant correlation (r2=0.52, p< 0.01) has been observed between cephalothorax MTs and cytosolic Zn concentrations. Our results showed a fast response (96 h) of MTs induction in the cephalotorax of P. argentinus at environmental Zn concentrations, indicating its potential use as a biomarker of metal exposure in this native species.