Uptake, accumulation and detoxication of Microcystin-LR in shrimps (Palaemonetes argentinus)

GALANTI, L.N.; AMÉ, M.V.; WUNDERLIN, DANIEL ALBERTO

Berlin

Congreso; 6th SETAC World Congress/SETAC Europe 22nd Annual Meeting; 2012

Microcystins (MCs) are cyclic heptapeptide produced by cianobacteria. There are over 100 different MCs congeners reported up to now, having different toxicity. MC-LR is by far the most studied and ubiquitous toxin, with know hepatotoxic effects, inhibition of protein-phosphatases 1 and 2-A, which promotes cancer and other diseases. MC-LR has been found in water bodies worldwide. Still today, little is known on how this toxin is transferred through the food web from water or cianobacteria. Our main goal was evaluating the uptake of soluble MC-LR by small shrimps (P. argentinus) that share the same habitat with cianobacteria. Additionally, we evaluated the detoxication period after initial uptake as well as the activity of several enzymes involved in detoxicatio Glutathion-S-Tranferase or antioxidant defence system Catalase, Glutathion Reductase and Glutathion Peroxidase. So, we look to evaluate both bioaccumulation and detoxication of MC-LR in shrimps as the first step in the transference of MCs within the aquatic food web, considering that shrimps are predated by fish, which are then captured by other fish or used as food by humans. Analysis of MC-LR in water and shrimps was done by HPLC-PDA-ESI-MS (either triple quadrupole or Q-TOF). Shrimps were exposed to soluble MC-LR (50 µg L-1) during 3 days and then translated to new tanks without MCs for additional three days. Crustaceans presented bioaccumulation after 3 days exposure (0.74 ± 0.15 µg MC-LR g-1 shrimp). The amount of MC-LR was reduced to 0.18 ± 0.01 µg MC-LR g-1 shrimp after three days detoxication (75% MC-LR removal during the detoxication period). The activity of studied enzymes remained almost unchanged during the exposure period but Glutathion-S-Tranferase and Glutathion Reductase were induced (activated) during the detoxication period. These preliminary results suggest that MC-LR can be bioaccumulated and eliminated in shimps. On the other hand both detoxication and antioxidant enzymes seem to be repressed during the exposure but stimulated after exposure, enabling detoxication. Our current results suggest that the uptake, bioaccumulation and detoxication process is complex and demonstrate that MC-LR is bioaccumulated by shrimps upon exposure to environmental relevant amounts of this toxin. Furthermore, detoxication enzymes seem to be inhibited during the exposure period. However, detoxication enzymes are activated as soon as the exposure stops, enabling 75% removal after three days.