西草净对四角蛤蜊的毒性效应

Toxic Effect of Simetryn on Mactra veneriformis

除草剂污染对海洋环境以及水产品质量安全的影响已引起广泛关注,其中除草剂对滩涂贝类质量安全的影响尚不明确。为探究常用除草剂西草净(simetryn)对黄河三角洲滩涂贝类养殖的影响,本文以四角蛤蜊(Mactra veneriformis)为实验对象,研究不同质量浓度西草净胁迫对四角蛤蜊鳃和肝胰腺抗氧化酶活性和组织结构的影响,测定胁迫阶段和净水消除阶段不同时间点各组织中超氧化物歧化酶(superoxide dismutase,SOD)、过氧化氢酶(catalase,CAT)活性和丙二醛(malondialdehyde,MDA)含量变化,观察组织的显微结构变化并测定了药物残留量。结果显示,鳃的酶活性在0.2×10^(-3)mg·L^(-1)、1.0×10^(-2)mg·L^(-1)浓度药物胁迫下被抑制,肝胰腺酶活性则在0.2×10^(-3)mg·L^(-1)浓度被诱导,1.0×10^(-2)mg·L^(-1)浓度被抑制,肝胰腺MDA含量在胁迫初期显著升高。所有实验组2种组织的SOD、CAT活性和MDA含量均能在净水消除阶段恢复至正常水平,表明1.0×10^(-2)mg·L^(-1)及以下浓度的西草净胁迫21 d后,对抗氧化酶系统的毒性效应是可逆的。西草净胁迫下,鳃的网格结构融化,鳃丝变松散,出现病变结构;肝胰腺消化管受损,结构脱落,出现小空腔。组织的药物含量均在染毒阶段第10天达到最大,残留药物可通过清水恢复消除。结果表明,西草净对四角蛤蜊产生了明显的氧化和组织损伤,同时探讨了其对滩涂贝类质量安全的影响,为实现滩涂贝类养殖质量可控化发展提供参考。

The effect of herbicide pollution on the marine environment and quality and safety of aquatic product has been of great concern,and the impact of herbicides on the quality and safety of tidal flat shellfish is still unclear.To explore the effects of simetryn used commonly on shellfish in the Yellow River Delta,the effects of simetryn of different concentrations on gill and hepatopancreas antioxidant enzyme activity and tissue structure of Mactra veneriformis were investigated.Superoxide dismutase(SOD),catalase(CAT)activities and malondialdehyde(MDA)content were measured in tissues at different time in exposure and elimination phases.The changes of microstructural of tissues were observed and drug residues were determined.The results showed that the enzyme activity of gills was inhibited under 0.2×10-3 mg·L^(-1)and 1.0×10^(-2)mg·L^(-1)of simetryn,while the enzyme activity of hepatopancreas was induced at 0.2×10^(-3)mg·L^(-1)and inhibited at 1.0×10^(-2)mg·L^(-1).SOD,CAT activity and MDA content of the two tissues in all experimental groups could return to normal during the elimination phase,indicating that the toxic effects on antioxidant enzyme system were reversible after exposed to simetryn at 1.0×10^(-2)mg·L^(-1)or below for 21 d.The mesh structure of the gills melted,the gill filaments became loose,and diseased structure appeared;the hepatopancreatic digestive canal was damaged,the structure fell off,and small cavity appeared.The content of simetryn in the tissues reached the maximum on the 10th day of exposure phases,and the residual could be eliminated by the depuration.Simetryn is not easy to be enriched in Mactra veneriformis,and can be metabolized and excreted quickly,and its toxic effect on Mactra veneriformis can also be weakened.The results showed that simetryn were observed to exert obvious oxidation and tissue damage to Mactra veneriformis,and its influence on the quality and safety of tidal flat shellfish was also discussed,which offered a reference for the risk assessment of marine ecosystems and achieved a controllable level of quality and safety in shellfish aquaculture in tidal areas.