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mRNA expression of antioxidant enzymes and physiological responses in the Pacific oyster, Crassostrea gigas, exposed to an hypoxic environment

MI SEON PARK¹, PIL GUE JO², KWANG WOOK AN³, SUNG HWOAN CHO³, GYUNG-SUK KIL⁴ TAE-SEOK MOON² & CHEOL YOUNG CHOI³*
¹ Research and Development Planning Department, National Fisheries Research & Development Institute, Busan, 619-705 Korea
² South Sea Mariculture Research Center, NFRDI, Kyungnam 668-821 Korea
³ Division of Marine Environment & BioScience, Korea Maritime University, Busan 606-791 Korea
⁴ Division of Electrical & Electronic Engineering, Korea Maritime University, Busan 606-791 Korea
*Corresponding author: Cheol Young Choi, Ph.D., Division of Marine Environment & Bioscience, Korea Maritime University, Busan 606-791 Korea. Fax: +82 51 404 3988. Email: choic@hhu.ac.kr

Abstract

We measured the trends of oxygen (O₂) consumption by Pacific oysters (Crassostrea gigas) exposed to an hypoxic environment and compared mRNA expression of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX). We also measured changes in osmolality and inorganic ion concentration in the haemolymph. O₂ consumption led to increased expression of SOD mRNA in gills and digestive glands up to 1 h, when it then decreased. CAT and GPX mRNA in gills and digestive glands tended to decrease. Haemolymph osmolality and K⁺ level decreased with increasing water influx for O₂ uptake, and Ca²⁺ and Mg²⁺ levels increased through mobilization of calcium carbonate to provide bicarbonate to buffer against acidosis. Therefore, under hypoxic conditions, activities of these antioxidant enzymes seem to be key in minimizing tissue damage caused by reactive oxygen species.

Key words: CAT, GPX, hypoxia, osmolality, SOD

Full article (PDF; 6200 KB)