重金属镉胁迫下鲫鱼不同组织中金属硫蛋白的动态变化

On the dynamic variations of metallothionein in the different tissues of Carassius auratus due to the exposure of different concentrations of cadmium

研究一定环境条件下,重金属镉(Cd)胁迫对鲫鱼(Carassius auratus)不同组织中金属硫蛋白(MT)含量的影响。结果表明,水温为(16.5±1.0)℃时,平均体长(15.32±0.63)cm、体重(310.60±5.69)g的鲫鱼不同组织中MT含量的本底值存在显著差异(p<0.05),含量顺序为肝脏(3.018±0.023)～(3.226±0.010)μg·g-1>肾脏(2.663±0.009)～(2.852±0.003)μg·g-1>鳃丝(1.523±0.017)～(1.623±0.009)μg·g-1>肌肉(1.432±0.011)～(1.474±0.005)μg·g-1,且相对比较稳定。在0.005mg·L-1、0.050mg·L-1、0.100mg·L-1、0.250mg·L-1和0.500mg·L-1的Cd2+胁迫下,鲫鱼4种组织中MT含量的总体变化趋势基本一致,即先升高后稳定,且在0～6h内MT含量的增加速率最大;鳃丝、肝脏和肾脏3种组织中MT含量在12h时达到峰值,随后略有下降并趋于稳定;肌肉中MT含量在24～96h达到峰值。鲫鱼4种组织中MT含量在12h内的增加量与Cd2+的质量浓度显著相关,表现出一定的剂量-效应关系,这表明水体中Cd2+可诱导鲫鱼组织中MT的合成与表达,且诱导时间主要在前12h内。鲫鱼肝脏、肾脏和鳃丝组织中的MT可作为评价外源重金属Cd污染的生物标志物。

The present article aims to investigate the impact of waterborne cadmium on the content of metallothionein （MT） in different tissues of Carassius auratus under the experimental conditions. To be accurate, the experimental conditions can be stated as follows： the water temperature stands between （16.5 ± 1.0） ℃ ; the average length of the fish is （15.32 ±0.63） cm with the middleweight being （310.60± 5.69） g. The results of our experiments show that the normal trace value of MT in the different tissues of Carassius auratus proves relatively stable during the experimental period, though its contents in the different tissues were found different, for example, those in the gill, muscle, liver and kidney, respectively. The order of the MT contents in the above said tissues can be stated as follows： liver 〉 kidney 〉 gill 〉 muscle. Actually, the contents of MT in the gill, liver and kidney are likely to be as high as up to the maximum in 12 hours, and then it would be likely to drop a little and tend to get steady. However, in the muscles, with the prolonging of the exposure time, the contents of MT would rise to its peak value, though the exposure time would not go beyond 12 hours. A positive relation could be found with the increase of the mass concentrations of cadmium in water. That is to day, the more the content of MT in water, the stranger the dose-response. Therefore, the conclusion tends to indicate that cadmium in water can induce the production and expression of MT in tissues of Carassius auratus at the first 12 hours when being exposed, which means that MT in the liver, kidney and gill can be used as a biomarker for evaluation of the pollution of the exogenous heavy metal.