【作者】 吴海一；

【导师】 孙世春；

【作者基本信息】 中国海洋大学 ， 水生生物学， 2008， 博士

【摘要】 本文以青岛海滨常见种扁额细首纽虫Cephalothrix simula（Iwata,1952）为实验材料,研究了纽虫暴露在铜离子浓度为0.005,0.018和0.056 mg/l、锌离子浓度为0.14,0.43和1.35mg/l、镉离子浓度为0.5,1.6和5.0 mg/l溶液里96 h,纽虫体内金属积累、抗氧化酶、金属硫蛋白以及丙二醛的变化情况。目的是为了揭示重金属对扁额细首纽虫抗氧化防御系统及脂质过氧化作用的影响,为利用纽形动物监测重金属污染提供理论依据。通过将扁额细首纽虫暴露在不同浓度铜、锌、镉溶液里96 h,分析了纽虫积累金属离子含量的变化。结果表明纽虫金属积累的量和溶液里的金属浓度正相关,溶液里的金属离子浓度越高,其体内金属离子含量也越高。另外,虫体内的金属离子含量与暴露时间成明显的线性关系,即,随着暴露时间的延长,其体内金属离子含量逐渐增加。当扁额细首纽虫暴露在0.006 mg/l Cu²⁺溶液里,与对照组相比,虫体内金属含量显著增加发生在24 h（p＜0.05）,在0.018和0.056 mg/l Cu²⁺溶液里,其显著增加在12和6 h（p＜0.05）;暴露在0.14,0.43和1.35 mg/l Zn²⁺溶液里,其显著增加在24、12和6 h（p＜0.05）;在0.5,1.6和5.0mg/l Cd²⁺溶液,其显著增加在6 h（p＜0.05）。实验证明,扁额细首纽虫具有较强的金属积累能力,尤其是对镉离子积累能力。通过将扁额细首纽虫暴露在铜,锌和镉不同浓度的溶液里96 h,分析了其体内CAT,SOD及GPX活力变化规律。结果表明:CAT,SOD和GPX（除了GPX在浓度0.006和0.018 mg/l Cu处理组）均在6-12 h内发生显著变化（p＜0.05）。三种金属离子显著的抑制了CAT,CAT的活力在6或12 h达到最小值（p＜0.05）,之后逐渐增加。当纽虫暴露铜溶液时,其SOD的活力变化在48 h内,表现为显著增加,而暴露在锌溶液里24 h后,才被诱导,在镉溶液里72 h前一直被抑制。另外,纽虫暴露在铜溶液里,GPX在24 h达到极大值,在锌溶液里则分别在6 h达到极大值,在镉溶液里6或12 h被显著抑制（p＜0.05）。实验结果说明扁额细首纽虫体内的CAT,SOD及GPX对铜,锌和镉三种重金属离子均具有较强的敏感性,尤其是CAT,在短时间内可以作为一种监测环境中重金属污染的指示指标。将扁额细首纽虫暴露在不同浓度的铜、锌、镉溶液里96 h,分析了其体内的金属硫蛋白含量变化。结果表明,三种不同浓度的重金属离子均诱导纽虫合成金属硫蛋白,浓度越高,诱导作用也越大。当纽虫暴露在0.018和0.056 mg/l Cu²⁺溶液里时,其体内的MT含量快速增加,12 h达到最大值（p＜0.05）,然后缓慢的降低,直到48 h后MT开始逐渐增加（p＜0.05）;而在浓度为0.006 mg/l Cu²⁺溶液组,MT含量直到24 h处才达到最大值（p＜0.05）。当纽虫暴露在浓度为0.14,0.43和1.35mg/l Zn²⁺三种溶液里时,MT的含量均在12 h达到最大值（p＜0.05）,然后快速降低,24 h开始保持稳定。当暴露在浓度为0.5,1.6和5.0 mg/l Cd²⁺三种溶液里时,MT的含量变化与Zn²⁺溶液组的变化相似,但是MT含量在6 h处就达到最大值（p＜0.05）,然后快速降低,12 h开始缓慢增加。通过揭示重金属污染后,MT含量的变化规律,阐明了扁额细首纽虫MT可以作为一种理想的生物标志物用来监测环境中重金属污染状况。通过对扁额细首纽虫暴露在不同浓度铜、锌、镉溶液里96 h,分析纽虫体内丙二醛含量的变化,结果表明纽虫体内的丙二醛含量均在6 h就产生了明显的变化（除了在浓度为5.0mg/lCd溶液里）。当纽虫暴露三种浓度Cu²⁺溶液时,其体内的MDA含量均高于对照组。在0.056 mg/l Cu²⁺溶液处理组,其体内的MDA含量快速增加,6 h达到最大值（p＜0.05）,然后缓慢的降低,保持稳定。而在浓度为0.006、0.018 mg/l Cu²⁺溶液组,其体内的MDA含量在72 h处出现高峰值（p＜0.05）。当纽虫暴露三种浓度Zn²⁺溶液时,其体内的MDA含量除了在高浓度组(0.43 mg/l Zn²⁺)96 h时高于对照组,MDA含量均小于对照组、均在6 h迅速降低（p＜0.05）,而后逐渐增加。当纽虫暴露在浓度为0.5和1.6 mg/l Cd²⁺溶液里时,MDA含量在6 h处显著增加（p＜0.05）,在12 h处,三个实验处理组的纽虫体内的MDA含量均降到最小值（p＜0.05）,而后逐渐增加;但是在5.0 mg/l Cd²⁺处理组,48 h处恢复到正常水平,之后又开始减少（p＜0.05）;1.6 mg/l Cd²⁺处理组,MDA含量在48 h处,出现第二次高峰（p＜0.05）;而在0.5 mg/l Cd²⁺处理组,72 h后保持稳定。实验结果说明,三种金属离子均对扁额细首纽虫体内的脂质过氧化作用产生了影响,导致机体内MDA的含量产生了明显的变化。MDA含量的变化,揭示了不同浓度三种金属离子对纽虫产生了毒性作用,改变了纽虫体内的正常生理代谢水平。MDA的含量变化可以间接的反应环境中重金属污染状况。更多还原

【Abstract】 Cephalothrix simula（Iwata） is one of the most common nemertean along the coast of Qingdao.In present study,the nemertean were exposed in copper（Cu） ion solutions at concentration of 0.005,0.018,0.056 mg/l,and zinc（Zn） ion solutions at concentration of 0.14,0.43,1.35 mg/l,cadmium（Cd） ion solutions at concentration of 0.5,1.6,5.0 mg/l for 96 h.Then heavy metal accumulation in vivo,variations of antioxidant enzyme activities,metallothionein（MT） contents and malondialdehyde （MDA） contents of the nemertean were determined respectively.The aim is to explore the effects of heavy metals on the antioxidant defense system and lipid peroxidation of the nemertean,and then accumulate the knowledge that the nemertean was used as a bioindicator to monitor heavy metal pollutants.The results are as follows.The results of heavy metal accumulation in vivo showed that positive correlation existed between the contents of metal ions in vivo and in exposed solutions,and in groups of higher concentrations of ion solutions,the contents of metal ions in vivo were more than the lower ones.In addition,a linear correlation appeared between the contents of metal ions in vivo and the exposed time,the contents of metal ions in vivo were increased by exposed time extended.When the nemertean were exposed in 0.006 mg/l Cu²⁺ solutions,the significant increase of Cu concentrations in vivo appeared at 24 h（p＜0.05）,while in 0.018 and 0.056 mg/l Cu²⁺ solutions,it appeared at 12 and 6 h（p＜0.05）.Similarly,in Zn²⁺ treatment groups,the significant increase appeared at 24,12 and 6 h（p＜0.05）.But in Cd²⁺ treatment groups,it all appeared at 6 h（p＜0.05）.The data revealed that the nemertean C.simula has a high ability to accumulate Cu,Zn and Cd,especially Cd. Determination of the activities of CAT,SOD and GPX of C.simula illustrated that activities of CAT,SOD and GPX showed distinct changes at 6-12 h（p＜0.05） except for GPX in groups of 0.006 and 0.018 mg/l Cu²⁺ treatment.CAT was significantly inhibited by the three heavy metal ions and its activity reached the nadir level at 6 or 12 h（p＜0.05） before it started to increase.SOD activities were significantly increased within 48 h in a Cu²⁺ solution,it was only induced after 24 h in Zn solutions.However,it was inhibited before 72 h in Cd²⁺ solutions.Additionally, the activity of GPX reached maximum at 24 h in Cu²⁺ solution and at 6 h in Zn²⁺ solution,but it was significantly inhibited at 6 or 12 h in Cd²⁺ solution.These results revealed that CAT,SOD and GPX of C.simula are sensitive to Cu,Zn and Cd ions in vivo,especially CAT,which might be considered as a biomarker of Cu,Zn and Cd monitor within short time.Variations of MT contents demonstrated MT was significantly induced by three heavy metal ions and at the same time in groups of higher concentrations of metal solutions the contents of MT in vivo were induced more than the lower ones.In groups of 0.018 and 0.056 mg/l Cu²⁺ solutions,MT contents increased fast and got the highest points at 12 h（p＜0.05）,then slowly decreased till 48 h.After that increased gradually till 96 h（p＜0.05）,but in group of 0.006 mg/l Cu²⁺ treatment the contents of MT got the highest points at 24 h（p＜0.05）.When in 0.14,0.43 and 1.35 mg/l of Zn²⁺ treatment,MT contents got the highest points at 12 h（p＜0.05）,and rapidly decreased. After 24 h,MT contents tended to be steady.However,when exposed in 0.5,1.6 and 5.0 mg/l of Cd²⁺ solution,variations of MT were similar to that in Zn²⁺ treatment,but MT contents got the highest points at 6 h（p＜0.05）,then rapidly decreased till 12 h. Variations of MT contents in vivo after heavy metal ions treatments reflected that MT in C.simula might be considered as a biomarker to monitor heavy metals pollutants.Variations of MDA contents after the worms were exposed in Cu,Zn and Cd solutions at different concentrations for 96 h demonstrated that the contents of MDA distinctly changed at 6 h（p＜0.05） in all the treatment groups,except for in the 5.0 mg/l Cd²⁺ treatment.MDA contents in Cu²⁺ treatment groups were all higher than that of control groups.In 0.056 mg/l Cu²⁺ treatment,it quickly increased and reached the peak values at 6 h,then slowly decreased and tended to be steady,but in groups of 0.006 and 0.018 mg/l Cu²⁺ solutions peak values of MDA contents appeared at 72 h（p＜0.05）.While in three concentrations of Zn²⁺ solutions,MDA contents all kept lower than control values(except for 0.43 mg/l Zn²⁺ treatment at 96 h),and rapidly decreased at 6 h（p＜0.05）,then gradually increased.However,in groups of 0.5 and 1.6 mg/l Cd²⁺ treatments,the significant increase of MDA content appeared at 6 h（p＜0.05）,then the values in all concentration treatments decreased to the nadir at 12 h（p＜0.05）,and then gradually increased,but differently,in 5.0 mg/l Cd²⁺ treatment,it was near to control values at 48 h,and then slowly decreased.In group of 1.6 mg/l Cd²⁺ treatment,MDA content reached the second peak values at 48 h.Present data showed that three heavy metal ions could affect lipid peroxidation and MDA content in C.simula.And the variations of MDA content implied the toxicity of three heavy metal ions to C.simula,and mignt be used as a biomarker to monitor indirectly heavy metal pollution.更多还原