2种抗生素联合暴露对食蚊鱼抗氧化酶活力及相关基因表达的影响

Effects of Co-exposure of Two Antibiotics on the Antioxidant Enzyme Activities and Related Genes Expression in Mosquitofish(Gambusia affinis)

水环境中存在多种抗生素残留,其造成的联合毒性对生物链产生不可忽视的影响。本研究采用氧氟沙星(ofloxacin,OFL)和磺胺甲恶唑(sulfamethoxazole,SMX)对食蚊鱼进行联合暴露10 d,检测其肝脏、肠道和肌肉组织的抗氧化酶活力和相关基因mRNA表达量变化,探究典型抗生素OFL和SMX联合暴露对食蚊鱼的毒性效应。结果表明,不同浓度OFL和SMX联合暴露10 d,对食蚊鱼机体造成了不同程度的氧化损伤,呈典型的剂量-效应关系,并具有组织特异性,这可能与Nrf2通路激活有关。主成分分析和Spearman相关性分析显示,谷胱甘肽S-转移酶(GST)、超氧化物歧化酶(SOD)、热激蛋白基因(HSP70和HSP90)对OFL和SMX联合暴露的响应较为灵敏,可作为良好的生态毒理指标。OFL和SMX联合暴露10 d后,相关基因mRNA的表达变化可更灵敏地指示食蚊鱼抗氧化系统的损伤。本研究从蛋白和mRNA表达水平揭示了OFL和SMX对食蚊鱼的联合毒性,并结合主成分分析和相关性分析,识别反应灵敏指标,为复合抗生素的生态风险评估和安全应用提供科学依据。

Many kinds of antibiotic residues in the aquatic environment cause combined toxicity to the biology chain,which is an nonnegligible ecological problem.This study investigated the combined toxic effects of ofloxacin(OFL)and sulfamethoxazole(SMX)on mosquitofish(exposure for 10 d)via detecting the changes of antioxidant enzyme activity and mRNA expression of related genes in the liver,intestine and muscle.The results showed that OFL and SMX combined exposure at different concentrations would lead to different levels of oxidative damage to mosquitofish and exhibited a typical dose-response relationship.In addition,the activation of Nrf2 pathway should be responsible for the tissue specificity of oxidative stress which induced by OFL and SMX.The principal component analysis and Spearman bivariate correlate analysis indicated that glutathione S-transferase(GST),superoxide dismutase(SOD)and heat shock protein genes(HSP70 and HSP90)were sensitive to the combined exposure of OFL and SMX which can be used as the ecotoxicological indicators.The changes of mRNA expressions can more accurately and sensitively indicated the antioxidant system damage in mosquitofish than the enzymes when through combined exposure for 10 d.This study revealed the combined toxicity of OFL and SMX to mosquitofish at protein and mRNA expression levels and identified the sensitive indicators which would provide some related scientific evidence to the ecological risk assessment and practical application of compound antibiotics.