磺胺甲恶唑污染对颤蚓的氧化胁迫

在实验室模拟条件下分别采用动、静态生物实验方法,研究了不同浓度的磺胺甲恶唑(sulfamethoxazole,SMZ)对颤蚓(Monopyle phorus limosus)体内抗氧化防御系统的影响以及颤蚓暴露于单一浓度的SMZ后,其体内典型的抗氧化酶,超氧化物歧化酶(SOD)的活性随时间的响应。结果显示:染毒8d后,颤蚓体内SOD的活性先降低后逐渐升高。SMZ染毒浓度达到1.00mg·L-1时,SOD的活性被显著诱导(P<0.01),为对照组的1.30倍。过氧化物酶(POD)活性的变化趋势明显分为先升高、再降低2个阶段。染毒浓度达到0.25mg·L-1时,POD的活性受到最大诱导(P<0.01),约为对照组的1.40倍。各处理组过氧化氢酶(CAT)的活性均高于对照组,并且随着SMZ暴露浓度的增加,CAT活性的变化趋势是逐渐降低的,与SMZ染毒浓度间存在较好的剂量-效应关系。随着SMZ暴露时间的延长,SOD、POD和CAT的活性变化趋势类似,均为先升高后降低,并在第8天时达到最大值(P<0.01),增长率分别为32%、26%和82%。综上,SMZ能诱导颤蚓体内产生氧化胁迫,而CAT在活性氧自由基的清除中发挥主要作用。

Oxidation Stress of Sulfamethoxazole (SMZ) on Polychaete Tubifex

The method of dynamic and static exposure was used to study the toxic effects of sulfamethoxazole (SMZ) on the antioxidant enzyme defense systems of Tubifex (Monopylephorus limosus ) in indoor laboratory environments. The changes of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activity in Tubifex exposed to 0.05-1.00 mg·L^-1 SMZ were examined. The changes of the antioxidant enzymes with time were also examined. The results showed that SOD activity was decreased at first and then increased gradually after the 8-day exposure. The highest SOD activity (P<0.01) was observed in Tubifex after the 8-day exposure to 1.00 mg· L^-1 SMZ (1.30 fold of that of control). POD activity increased firstly and then decreased. It reached the highest value after the 8-day exposure to 0.25 mg·L^-1 SMZ (1.40 fold of that of control). The CAT activities in exposure groups were higher than that of the control. The CAT activity decreased with an increase in SMZ concentration, and the dose response effect of SMZ and CAT activity was observed. With exposure time, the changes of SOD, POD and CAT were similar. The activity of antioxidant enzymes increased initially and then decreased. The peak values of them were all detected after the 8-d exposure, and the increase rates were 32%, 26% and 82%, respectively. Thus, it is indicated that SMZ could induce oxidative stress in Tubifex , and CAT played a key role in removing oxygen free radicals.