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

GALANTI, LUCAS NICOLáS; AMÉ, MARÍA VALERIA; WUNDERLIN, DANIEL ALBERTO

Congreso; http://berlin.setac.eu/scientific_programme/download_the_abstracts_book/?contentid=582&pr_id=403&last=435; 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 isby 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 maingoal was evaluating the uptake of soluble MC-LR by small shrimps (P. argentinus) that share the same habitat with cianobacteria. Additionally, we evaluated the detoxicationperiod after initial uptake as well as the activity of several enzymes involved in detoxicatio Glutathion-S-Tranferase or antioxidant defence system Catalase, GlutathionReductase 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 MCswithin 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 waterand shrimps was done by HPLC-PDA-ESI-MS (either triple quadrupole or Q-TOF). Shrimps were exposed to soluble MC-LR (50 ìg L-1) during 3 days and then translatedto new tanks without MCs for additional three days. Crustaceans presented bioaccumulation after 3 days exposure (0.74 ± 0.15 ìg MC-LR g-1 shrimp). The amount of MCLRwas reduced to 0.18 ± 0.01 ìg MC-LR g-1 shrimp after three days detoxication (75% MC-LR removal during the detoxication period). The activity of studied enzymesremained almost unchanged during the exposure period but Glutathion-S-Tranferase and Glutathion Reductase were induced (activated) during the detoxication period. Thesepreliminary results suggest that MC-LR can be bioaccumulated and eliminated in shimps. On the other hand both detoxication and antioxidant enzymes seem to be repressedduring the exposure but stimulated after exposure, enabling detoxication. Our current results suggest that the uptake, bioaccumulation and detoxication process is complexand demonstrate that MC-LR is bioaccumulated by shrimps upon exposure to environmental relevant amounts of this toxin. Furthermore, detoxication enzymes seem to beinhibited during the exposure period. However, detoxication enzymes are activated as soon as the exposure stops, enabling 75% removal after three days.