咪鲜胺和多菌灵对斑马鱼联合毒性效应

The Combined Effects of Prochloraz and Carbendazim on the Toxicity and Endocrine Disturbance in Zebrafish

水生生物经常暴露于多种化合物中,多种农药联合会产生不同的毒性作用。在目前农药管理中,仅要求开展单剂的毒性评价,没有考虑到多种混合物对水生生物的联合毒性。咪鲜胺和多菌灵是农业生产中常混用的2种农药,为评价其联合毒性,以斑马鱼为受试生物,采用静态法和实时荧光定量PCR方法,测定了其单剂及混剂对斑马鱼胚胎的急性毒性和对斑马鱼幼鱼甲状腺轴关键基因的影响。急性毒性试验结果显示:咪鲜胺和多菌灵对斑马鱼胚胎96h-LC50值分别为8.41mg·L^-1和0.81mg·L^-1,表现为中毒和高毒。二元组合时,在24~96h暴露时间内,对斑马鱼胚胎的急性毒性均表现为拮抗效应。基因表达结果显示:咪鲜胺抑制斑马鱼幼鱼促甲状腺激素释放激素(CRH)、促甲状腺激素(TSH)、甲状腺激素受体(TRα)、脱碘酶(D1、D2)基因的表达,对甲状腺激素转运蛋白(TTR)基因的表达没有显著影响;多菌灵抑制CRH、TSH、D1和D2基因的表达;暴露于二元组合时,低、中剂量组抑制CRH、TSH、D1和D2基因表达;二元组合与单剂相比,高剂量组促进TSH、D1和D2基因的表达,中剂量组促进TRα基因的表达。综上所述,咪鲜胺和多菌灵联合暴露能够干扰斑马鱼幼鱼早期发育,且与单剂相比,对斑马鱼甲状腺轴上基因干扰效应存在差异。因此,在农药风险评估中,应充分考虑农药联合暴露的效应。

Although the aquatic organisms are exposed to multiple chemicals more often than single chemical,the combined toxicity are not considered by the present pesticide regulations during risk assessment.Prochloraz and carbendazim are used widely in vegetables and fruits in China.In order to evaluate the combined toxicity of prochloraz and carbendazim,zebrafish was taken as the subject organism,and the acute toxicity and the influence on its key genes of the thyroid axis of zebrafish larvae were determined by static method and real-time fluorescence quantitative PCR method.The results of acute toxicity tests showed,the 96 h-LC50 values of prochloraz and carben dazim on zebrafish embryo were 8.41 mg·L^-1 and 0.81 mg·L^-1 respectively,which were medium and high toxicity. The combination of prochloraz and carbendazim presented antagonism effects during 24-96 h.The results of gene expression indicated that prochloraz inhibited the expression of thyroid-stimulating hormone releasing hormone (CRH),thyroid-stimulating hormone (TSH),thyroid hormone receptor (TRα),and deiodinase (D1,D2) genes and there were no significant changes in the expression of thyroid hormone transporter (TTR) gene.Carbendazim inhibited the expression of CRH,TSH,D1 and D2 genes.Combined exposure (low and medium dose) inhibited the expression of CRH,TSH,D1 and D2 genes in zebrafish.Compared with single agent,the high dose combined group enhanced the expression of TSH,D1 and D2 genes,and the medium dose combined group promoted the expression of TRα gene.In conclusion,the combined effects of prochloraz and carbendazim could influence the early development of zebrafish larvae,and there were differences in gene interference on thyroid axis of zebrafish compared with single dose.Therefore,the results suggested that the combined effects should be considered during the risk assessment of pesticide management.