氨氮对栉孔扇贝血淋巴活性氧含量和抗氧化酶活性的影响

实验测定了不同浓度氨氮胁迫下栉孔扇贝(Chlamys farreri)血淋巴中胞内胞外活性氧自由基(ROIs)含量、超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性的变化。结果表明，在较低浓度氨氮胁迫下，胞内胞外活性氧含量都随氨氮浓度升高而增加，当浓度继续增加到20～40mg／L时，胞内外活性氧含量都明显下降且低于对照组；不同氨氮浓度下两种酶活性也不同，当氨氮浓度为1．25～20mg／L时，CAT活性随氨氮浓度增加而升高，当浓度增大到40mg／L时，CAT活性明显下降且低于对照组；当氨氮浓度为1．25～5mg／L时，SOD活性随氨氮浓度增加而升高，而当浓度为10～40mg／L时，酶活性显著下降。实验结果说明，适当的氨氮刺激可增加胞内外活性氧的含量，增强扇贝的两种抗氧化酶活性，但较高浓度氨氮则使胞内外活性氧的含量显著下降并明显抑制抗氧化酶的活性。

Effect of Ammonia-N on the content of ROIs and the activities of antioxidant enzyme in the haemolymph of Chlamys farreri

Effect of Ammonia-N on the content of reactive oxygen species (ROIs) and the activities of superoxide dismutase(SOD) and catalase(CAT) in haemolymph of Chlamys farreri was studied. The results showed that at low Ammonia-N concentrations, the contents of intracellular and extracellular ROIs increased significantly with the increasing concentration of Ammonia-N compared with the control group. When the concentrations reached 20~40 mg/L, the contents of them went down conspicuously and even below the control group. The activities of SOD and CAT also changed at different Ammonia-N concentrations.When the concentrations were 1.25~20 mg/L, the activity of CAT went up with the increasing Ammonia-N concentration. But the activity decreased sharply and below the control group at 40 mg/L. The activity of SOD increased when the concentrations were 1.25~5 mg/L, but decreased radically at 10~40 mg/L and even below the level of control group. The results indicated appropriate Ammonia-N stimulant can increase the content of ROIs, and promote the activities of the two kinds of antioxidant enzymes; but the content of ROIs decreased evidently and the activities of the two enzymes were inhibited obviously at high Ammonia-N concentrations.