亚心形扁藻超氧化物歧化酶活性对镉和铜的应答

以亚心形扁藻为实验材料,对不同浓度重金属镉(Cd2 )和铜(Cu2 )作用下亚心形扁藻的超氧化物歧化酶(SOD)活性的变化和膜脂过氧化作用进行了探讨,以期了解藻类抗重金属的机制。结果表明:随着Cd2 和Cu2 浓度的增加亚心形扁藻的SOD的活性逐渐升高,但高浓度Cd2 可导致SOD活性活性下降。膜脂过氧化实验结果显示,半抑制浓度的重金属处理72hr后,膜脂过氧化产物丙二醛(MDA)显著提高。用72h半抑制浓度的重金属处理亚心形扁藻随时间的变化关系表明,在最初的12hr内SOD活性被两种重金属离子诱导迅速升高,然后逐渐趋于平稳。总之,SOD活性的变化与重金属的种类、浓度和处理时间有关。

RESPONSE OF SUPEROXIDE DISMUTASE ACTIVITY TO CADIUM AND COPPER IN PLATYMONAS SUBCORDIFORMING

The response of superoxide dismutase(SOD) activity and metal-induced lipid peroxidation in the marine alga Platymonas subcordiforming at different concentrations of cadmium(Cd) and copper(Cu) was investigated to understand the mechanisms of metal resistance in algal cells.After 72 hr exposure,higher SOD activities were generally found in cells exposed to greater metal concentrations in a dose dependent manner,while low enzyme activities were observed at the highest cadmium doses.In addition,assays for oxidative damage to lipids revealed high levels of lipid peroxidation in cells for 72 hr kept in EC50 concentrations of metals.Effects of exposure time in EC50 concentrations of Cd and Cu showed that total SOD activity were in cells increased rapidly in the first 12 hr.The plateau value attained after 12 hr was maintained throughout the rest of the experiment.Changes in SOD activity dependent on the metal,its concentration and the time of exposure.These results suggested that oxidative stress may be an important mediator of metal toxicity in algal systems,with SOD providing antioxidant protection.