PT20 Ecotoxicology of Tropical Aquatic Environments
Exhibit Hall
8:00 AM - Tuesday
(PT297) Effect of domestic sewage exposure on oxidative stress responses and Hsp levels in the mangrove oyster, Crassostrea rhizophorae.
Marques, M.1, Medeiros, I.1, Trivella, D.1, Bresolin, T.1, Toledo-Silva, G.1, Ferreira, J.2, Bainy, A.1, 1 Lab. Biomarcadores de Contaminacao Aquatica e Imunoquimica, Dept. Bioquimica, CCB, UFSC, Florianopolis, SC, Brazil2 Lab. Cultivo de Moluscos Marinhos, Dept. Aquicultura, CCA, UFSC, Florianopolis, SC, Brazil
ABSTRACT- Domestic sewage discharges may compromise farmed mollusk quality and therefore represent a potential risk for human health. The aim of the present study was to evaluate biomarker responses in gill tissue of the mangrove oyster, Crassostrea rhizophorae., exposed to domestic sewage under laboratory conditions. The oysters were acclimated for 10 days at 25 ppm salinity. Temperature and aeration were kept constant and animals were fed daily. Two different sewage dilutions (14.5 and 29.0 %) were used for a 48 hour-exposure period (n=7 for each group). Activity of oxidative stress related enzymes, Catalase (CAT), Glutathione peroxidase (GPx), Glutathione reductase (GR) and Glutathione-S-transferase (GST) was measured according to conventional procedures. Hsp70 and Hsp60 levels were determined on Western and dot-blots with anti-human Hsp antibodies. The immune complex was visualized by chemiluminescence. No mortality was observed upon treatment. GR, GPx and total GST activities showed no changes in the exposed groups. A slight, but not statistically significant, increase in CAT activity was seen after treatment. Accordingly, although a slight increase in Hsp70 levels was observed in the oysters exposed to 14.5% of domestic sewage. Apparently, exposure to 29.0 % dilution of domestic sewage was associated with lower, but not significant, levels of Hsp70 and Hsp60. On the other hand, GST activity towards ethacrynic acid (EA) was significantly higher (p<0.0001) in the treated groups. This finding is related to GST isoforms of C. rhizophorae, corroborating the fact that analysis of total GST activity in environmental samples may be conflicting. Further studies are required to identify the class of contaminants present in the domestic sewage. Ongoing differential gene expression studies will contribute to better characterize the molecular response of this mollusk upon exposure to domestic sewage. Supported by CNPq, 475995/2003-1
Key words: Domestic sewage, Oyster, Biomarkers, Crassostrea rhizophorae