Changes in expressions of oxidative stress-related genes in Mytilus galloprovincialis with hypoxia exposure. Mussels were exposed to 2 mg/L dissolved oxygen (DO 2) for 24 and 48 h, and RNAs were extracted from muscle tissues. mRNA levels were evaluated by a real-time quantitative PCR, and results are expressed relative to actin expression levels. Each histogram represents the mean ± SD (n = 3). Asterisk indicates significant difference from each control group (p < 0.05).