| 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.
|
PDF Full Text Request