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(41-08) Alternative mechanism of microcystin toxicity in the estuarine crab, Chasmagnathus granulata. Pinho, Grasiela1, Moura da Rosa, Cristiane1, Yunes, JoMISSING CHARACTER ENTITY: aaccento1, Bianchini, Adalto1, Monserrat, José*,1, 1 Fundação Universidade Federal do Rio Grande, Rio Grande, RS, BRAZIL ABSTRACT- Microcystins are produced by cyanobacteria species, including Microcystis aeruginosa, and have been recognized as being toxic to aquatic fauna due to their inhibitory effect on serine/threonine phosphatases. We analyzed the effect of this toxin on the antioxidant enzyme activity and lipid peroxidation (LPO) in the hepatopancreas of Chasmagnathus granulata. Toxin (17.6 Key words: hepatotoxin, antioxidant enzymes, lipid peroxidation, estuarine crab |
g) or saline was orally administered to crabs acclimated to 2 ‰, for 1 week. Crabs were not fed during the test. At 0, 2 and 7 days, intoxicated and control crabs were sacrificed. Catalase (CAT), superoxide dismutase (SOD), glutathione-S-transferase (GST) activity and LPO were determined by spectrophotometry. After 7 days of test, CAT activity was higher (p<0.05) in intoxicated than in control crabs (1.33±0.33 and 0.03±0.05 U/mg protein, respectively), although a decrease in enzyme activity over time (7.00±2.98 U/mg protein) was verified in both groups. No differences were detected in SOD activity. GST activity did not change over time in control crabs. However, it was higher (p<0.05) in intoxicated than in control crabs after 7 days of test (0.137±0.021 and 0.035±0.005 U/mg protein, respectively). In both groups, LPO did not change even after 7 days of exposure to microcystin (control=47.33±2.22 and intoxicated=59.89±14.33 nmoles/g ww). We conclude that: (1) augmented GST activity in intoxicated crabs indicated a higher conjugation rate of the toxin with glutathione, as previously established; (2) starvation induced a lower CAT activity even in control crabs; (3) higher CAT activity in intoxicated crabs could be related to an increase in ROS generation induced by the toxin; (4) the antioxidant system capacity was not overwhelmed by ROS generation since LPO remained constant after microcystin exposure.