【作者】 周彦锋；

【导师】 陈家长；

【作者基本信息】 南京农业大学 ， 水产养殖， 2008， 硕士

【摘要】 金属硫蛋白（metallothionein,MT）是一类相对低分子质量（6～7kDa）、富含半胱氨酸、能够结合金属的蛋白或多肽。水体中的重金属可以诱导鱼体内金属硫蛋白的表达。本研究以鲫鱼（Carassius auratus）为试验材料,通过体外静态染毒,采用血红蛋白饱和分析法,研究了在一定环境条件下,经不同浓度重金属镉和锌的连续暴露后,鲫鱼肝脏、肾脏、鳃丝和肌肉中MT含量的动态变化,为建立以金属硫蛋白作为评判淡水生态系统中重金属镉和锌污染的生物标志物提供理论依据。研究结果表明:1.平均体长为16.32±0.63cm,平均体重为320.6±6.19g的鲫鱼不同组织中的MT本底值存在着显著差异（P＜0.05）,含量顺序为肝脏＞肾脏＞鳃丝＞肌肉,鳃丝、肌肉、肝脏和肾脏中MT含量范围分别为1.506～2.014、1.367～1.868、3.018～4.169和2.582～3.602μg·g^-1。在相同试验条件下,受试鲫鱼组织中的MT本底值稳定在同一水平,差异不显著（P＞0.05）;水温16.5±1℃和26±1℃时鲫鱼同一组织中MT含量差异显著（P＜0.01）,但组织间MT含量顺序不变。2.在水温为16.5±1℃时,与对照组相比,在0.005、0.05、0.10、0.25和0.5 mg·L^-1浓度下镉胁迫对鲫鱼4种组织中MT的表达产生了诱导作用。鲫鱼的4种组织在12h内MT的增加量与镉的浓度表现出一定的剂量.效应关系其中肝脏MT的诱导量最大,变化规律也最明显。鲫鱼各组织中MT含量的总体变化趋势较为一致,均为先升高后略微下降并趋于稳定,其中鲫鱼鳃丝、肝脏和肾脏三种组织中MT的含量在12h时达到峰值,随后略有下降并趋于稳定,而肌肉中的MT含量在12h时没有出现峰值,其随着作用时间的延长逐渐到达峰值。试验水温为26.5±1℃时,在其它试验条件不变的情况下,鲫鱼组织中MT的合成表达表现出相同的规律,但此时鲫鱼组织中MT诱导的峰值比16.5±1℃时鲫鱼组织中MT的峰值高,二者差异显著（P＜0.01）,表明温度的升高可以增强重金属镉对鲫鱼组织中MT的诱导。3.水温为26±1℃时,与对照组相比,在0.1、0.5、1.0和10 mg·L^-1浓度下锌的胁迫对鲫鱼4种组织中MT的表达产生了诱导作用,但低剂量锌诱导效果不明显,高剂量的锌可以诱导鲫鱼组织中MT的大量合成。鲫鱼的4种组织在24h内MT的增加量与锌的浓度表现出一定的剂量-效应关系,其中肾脏MT的诱导量最大,变化规律也最明显。鲫鱼的4种组织中MT含量的总体变化趋势与重金属镉诱导规律较为一致,均为先升高后略微下降并趋于稳定,但组织中MT含量峰值的出现时间推迟到了染毒后的24h。试验结果显示锌对鲫鱼组织中MT含量的诱导能力弱于镉的诱导能力。4.环境中锌的存在可以加强重金属镉对鲫鱼组织中MT的诱导能力。试验结果表明,暴露在不同镉、锌浓度比的染毒液中,鲫鱼肝脏和肾脏组织中MT含量的总体变化趋势较为一致,均呈先升高后降低然后再升高的趋势,肝脏中MT在12h时增加速率最大,而肾脏中MT在6h时增加速率最快。鲫鱼组织肝脏和肾脏MT在12h内的增加量、12-48h内MT的减少量和48-96hMT的增加量都与镉的浓度表现出一定的剂量-效应关系,12h时鲫鱼组织中MT含量达到高峰,表明水体中的镉、锌联合可诱导鲫鱼组织中MT的合成与表达,且主要诱导时间在12h之内。鲫鱼组织肝脏和肾脏中MT含量均高于单独暴露于镉和锌时组织中MT的含量（P＜0.01）。在锌浓度一定的条件下,随着镉浓度的逐渐增加,肝脏和肾脏组织中MT含量也逐渐升高,呈现出一定剂量-效应关系。研究结果显示,在一定的试验条件下,鲫鱼鱼体组织中的MT,尤其是肝脏和肾脏中的MT含量可以作为指示水体中重金属镉、锌过度暴露的生物标志物。更多还原

【Abstract】 Metallothionein is a kind of protein which is low molecular weight,rich in cysteine, can combine heavy metal.Heavy metal in water could induce MT synthesize in fish.This research investigated the impact of waterborne heavy metal on the content of metallothionein（MT） in different tissues of Carassius auratus in experimental condition,in order to give some theoretical basis for applying MT as a biomarker of waterborne cadmium and zinc pollution.The water temperature was 16.5±1℃,the average length of the Carassius auratus was 16.32±0.63cm and the middleweight was 320.6±6.19g.The result indicates that MT background value is significantly different in different Carassius auratus tissues（P＜0.05）. The order is liver＞kidney＞gill＞muscle.Respective concentrations of MT in gill,muscle, liver and kidney is 1.523±0.017～1.623±0.009,1.432±0.011～1.474±0.005,3.018±0.023～3.226±0.010 and 2.6625±0.009～2.8516±0.003μg·g^-1.In the same experimental condition, MT background values of Carassius auratus tissues are relatively stable.In different temperature 16.5±1℃and 26.5±1℃,The MT concentration in the same tissues is significantly different（P＜0.01）.However the MT concentration in different tissues is in the same order.At 16.5±1℃,cadmium(0.005,0.05,0.10,0.25,0.5 mg·L^-1)induced the synthesis of MT in four Carassius auratus tissues.The comparative MT concentrations in four tissues general followed the same changing curvilinear trend,had a positive relativity with the concentration of cadmium in water,and showed dose-response relationship.The results indicates that the comparative MT concentrations were quite different according to Cadmium concentration and exposure time and the inducement mainly appeared in 12h,the peak values in gill,liver and kidney appeared in the 12th hour,but in muscle it did not peaked in the first 12hs but appeared latter.At 26.5±1℃,the comparative MT concentrations in four tissues also followed the same changing curvilinear trend,the peak values were extremely significantly higher than that in 16.5±1℃temperature groups （P＜0.01）.It said that temperature may impact on MT concentration in Carassius auratus tissues.At the water temperature of 26.5±1℃,0.1,0.5,1.0 and 10 mg·L^-1 Zinc induced the synthesis of MT in four Carassius auratus tissues.MT concentration in high dose group were greatly induced,while low dose group had no significant different with control.The comparative MT concentrations in four tissues general followed the same changing curvilinear trend,had a positive relativity with the concentration of zinc in water,and showed dose-response relationship within 24h.MT concentration in kidney was induced by the largest amount,changed of the most obvious.MT concentrates changed according to exposure time and four tissues showed the same curvilinear trend with that in Cadmium groups:first increase then declining slightly and stabilizing.But the peak values of MT concentration appeared in the 24th hour.The induce potency of Zinc was not as big as Cadmium.Heavy metal Zinc can enhance Cadmiums’ induce potency to MT synthesis in Carassius auratus tissues.After exposure in Cadmium & Zinc solution,MT concentration in liver and kidney changed in the same curvilinear trend,which can be generally described as increase-decrease-increase.The peak value of MT content appeared at 12h after exposure.The comparative MT concentrations had a significantly relativity with the concentration of Cadmium & Zinc solution,showed a dose-effect relation.The results indicate that Cadmium & Zinc can induce the synthesis of MT in Carassius auratus tissues and this inducing mainly happened during the first 12hs.The comparative MT concentration in liver and kidney of Carassius auratus in Cadmium & Zinc treatment groups were higher than that in Cadmium groups or Zinc groups.It indicates that Zinc can enhance Cadmium inducing effect on Carassius auratus MT and liver and kidney tissue MT does not mean that the content of individual exposure to Cadmium and separate when exposed to Zinc MT combined（P＜0.01）.Zinc concentration in certain circumstances The MT content in the liver and kidney gradually increased along with the increase of the Cadmium concentration,showed a certain dose-effect relationship.The results indicate that MT content in Carassius auratus liver and kidney can be used as a biomarker of waterborne cadmium and zinc pollution.更多还原