低浓度镱暴露对鲫鱼肝脏多种酶活性的影响

选择重稀土元素镱（Yb)和幼体鲫鱼为材料，研究了稀土元素低浓度长期（40d）暴露对鲫鱼幼体（Carassius auratus)肝脏所产生的生理生化反应。在实验剂量范围内，镱对鲫鱼肝脏内过氧化氢酶（CAT）表现出明显的抑制作用，对谷丙转氨酶（GPT）、谷胱甘肽过氧化物酶（GSH－Px）活性的影响在低浓度时表现为诱导作用，高浓度时抑制，对超氧化物歧化酶（SOD）活性表现为诱导。过氧化氢酶（CAT）对镱最为敏感，是一种很有前途的水生生态系统中镱的生物监测指标。

The Effects of Ytterbium on the Enzymes Activities of Crucian (Carassius auratus) Liver

In China, rare earth elements(REEs) were widely used in agriculture, forestry, animal husbandry and aquaculture as microelement fertilizers or animal food, which brought about high environmental concern. The fate of REEs in natural water bodies and their influences on aquatic organisms were of major importance in assessing potential risk of REEs .The aim of this work was to study the effects of long-term exposure of trace Rare earth element Ytterbium (Yb 3+) on several enzymes activities, such as the activities of Glutamate-pyruvate transaminase (GPT), Superoxide dismutase (SOD), Catalase(CAT) and Glutathione peroxidase (GSH-Px) in the liver of Crucian (Carassius auratus). During the 40-day exposure, it was found that the activities of CAT were inhibited significantly from 0.01 mg/L to 1.0 mg/L Yb 3+ solution. There were nearly 30% CAT activities which were inhibited after the exposure. The activities of GPT and GSH-Px were induced when the concentration was lower than 0.05 mg/L and inhibited when the concentration was higher than 0.05mg/L. The activities of SOD were induced from 0.05 mg/L to 1.0 mg/L Yb 3+ solution, but the induced ratio decreased when the concentration of Yb 3+ was higher than 0.05 mg/L. It was reported that REEs intoxication might bring large quantities of reactive oxygen intermediates(ROIs) which could cause various damage to fish. Antioxidant defense, e.g. superoxide dismutase (SOD) and Catase (CAT) in vivo could clear ROIs to make fish avoid damage. So the changes of the enzymes activities in fish liver could show the early influence of the pollution before the damage was obvious. The conclusion suggested that the fish might be damaged even at the low concentration such as 0.05 mg/L for the reason that several enzymes activities had changed obviously and it might cause the cumulation of ROIs. In addition, of the several indictors measured in the liver of fish, CAT was the most sensitive to Yb 3+, indicating that CAT might be regarded as a good bio-monitor index of Yb 3+ in aquatic ecosystem.