Induced gene expression in oyster Crassostrea gigas exposed to sewage

Abstract Pacific oysters, Crassostrea gigas , were exposed to untreated sewage diluted in seawater. After 48 h of exposure, the expression of genes associated to biotransformation pathways ( CYP356A1 , GSTO , MDR , FABP and ALAS ) were analyzed in gills through semi-quantitative RT-PCR. A significant induction in all genes analyzed in the sewage-exposed oysters was observed. These genes are related to phase I ( CYP356A1 ), phase II ( GSTO ) and phase III ( MDR ) biotransformation systems, to the uptake and transport of hydrophobic ligands ( FABP ) and to the synthesis of prosthetic group heme ( ALAS ). The organisms were able to survive in contaminated conditions since protective mechanisms have been properly stimulated.