title: Cloning and mRNA expression of antioxidant enzymes in the Pacific oyster, Crassostrea gigas in response to cadmium exposure.
abstract: Cadmium (Cd) is one of the most toxic heavy metal pollutants in the aquatic environment and can induce the formation of reactive oxygen species (ROS) that cause oxidative stress. In present study, we cloned catalase (CAT) and glutathione peroxidase (GPX) cDNA, and investigated its time- and dose-related effects of three Cd concentrations (0.01, 0.05 or 0.1 ppm) on mRNA levels of antioxidant enzymes (superoxide dismutase (SOD), CAT, GPX) in the gill and changes enzyme levels in the hemolymph of the Pacific oyster, Crassostrea gigas. The cDNA indentified encoded proteins of 516 and 244 amino acids corresponding to CAT and GPX, respectively. BLAST analysis from other species indicated that the residues essential to the enzymatic function of CAT and GPX proteins of C. gigas are highly conserved. Cd treatment significantly increased antioxidant enzyme mRNA expression in the gill in a time- and dose-dependent manner. The mRNA expression at 0.1 ppm Cd concentration increased up to 3 days (CAT, GPX) or 7 days (SOD) and then decreased by 7 days (CAT, GPX) or 11 days (SOD). Aspartate aminotransferase, alanine amintransferase and hydrogen peroxide (H(2)O(2)) concentrations levels increased significantly with exposure to 0.05 or 0.1 ppm Cd for 7 days. These results suggest that antioxidant enzymes play important roles in the physiological changes related to metabolism and cell protection that occur in Pacific oysters exposed to Cd.
authors.affiliation: Division of Marine Environment & Bioscience, Korea Maritime University, Busan 606-791, Republic of Korea.
authors.forename: Pil Gue
authors.initials: PG
authors.lastname: Jo
authors.forename: Yong Ki
authors.initials: YK
authors.lastname: Choi
authors.forename: Cheol Young
authors.initials: CY
authors.lastname: Choi
mesh_terms: D000410:Alanine Transaminase / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D000975:Antioxidants; D001219:Aspartate Aminotransferases / Q000378:metabolism; D019256:Cadmium Chloride / Q000633:toxicity*; D002374:Catalase / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D017124:Conserved Sequence; D049896:Crassostrea; D004305:Dose-Response Relationship, Drug; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D005880:Gills / Q000187:drug effects / Q000201:enzymology; D005979:Glutathione Peroxidase / Q000235:genetics / Q000378:metabolism; D006458:Hemolymph / Q000187:drug effects / Q000201:enzymology; D006861:Hydrogen Peroxide / Q000378:metabolism; D008969:Molecular Sequence Data; D010088:Oxidoreductases / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics*; D016415:Sequence Alignment; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D000975:Antioxidants; D012333:RNA, Messenger; D014874:Water Pollutants, Chemical; D006861:Hydrogen Peroxide; D010088:Oxidoreductases; D002374:Catalase; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D001219:Aspartate Aminotransferases; D000410:Alanine Transaminase; D019256:Cadmium Chloride