再生水对斑马鱼幼鱼下丘脑-垂体-甲状腺轴相关基因转录水平的影响

Effects of reclaimed water on gene transcription of the hypothalamuspituitary-thyroid axis in zebra fish larvae(Danio rerio)

再生水中具有多种微量内分泌干扰化合物,对水体生物具有潜在危害.为探究再生水对斑马鱼分子水平的甲状腺内分泌干扰效应,以斑马鱼幼鱼为研究对象,将斑马鱼幼鱼分别暴露于再生水中3 d和7 d后,然后在洁净水体中恢复7d,采用实时荧光定量PCR方法测定下丘脑-垂体-甲状腺轴上关键基因的转录水平.结果显示,与对照组相比,再生水暴露3 d、7 d和自来水恢复7 d对斑马鱼幼鱼存活率没有显著影响.与对照组相比,再生水暴露3 d后,斑马鱼幼鱼Trh、Dio2、Thrα、Thrβ基因转录水平显著上调(P<0.05),Dio1基因转录水平显著下调(P<0.05).再生水暴露7 d后,Trh、Tshβ、Dio2、Nis、Thrβ基因转录水平相对于对照组显著下调(P<0.05),Dio1、Thrα基因转录水平极显著下调(P<0.01);自来水恢复7d后,斑马鱼幼鱼Trh、Dio1、Dio2、Nis、Thrα、Thrβ基因转录水平相对于对照组无显著改变(P>0.05),仅Tshβ基因转录水平显著下调(P<0.05).本研究表明再生水影响了斑马鱼幼鱼HPT轴相关基因的转录水平,在洁净水体中恢复可减弱再生水对斑马鱼幼鱼HPT轴相关基因的影响,结果可为再生水中的内分泌干扰物生态毒性效应及风险评估提供理论依据.

There are many trace endocrine disrupting compounds in reclaimed water,and it can be potentially harmful to aquatic organisms.Therefore,to investigate the effects of reclaimed water on thyroid endocrine disruption at molecular level in zebra fish,zebra fish larvae were used as the research object in this study.Zebra fish larvae were exposed to reclaimed water for 3 to 7 days and then recovered in clean water for 7 days.Quantitative real-time polymerase chain reaction was used to measure the transcription levels of key genes in the hypothalamus-pituitary-thyroid(HPT)axis.Results showed that compared with that of the control group,the survival rate of zebra fish larvae was not significantly affected by reclaimed water exposure.Compared with those of the control group,the transcription levels of Trh,Dio2,Thrα,and Thrβgenes of zebra fish larvae were significantly increased(P<0.05)and the transcription levels of Dio1 gene was significantly decreased(P<0.05)after reclaimed water exposure for 3 days.After reclaimed water exposure for 7 days,the transcription levels of Trh,Tshβ,Dio2,Nis,and Thrβgenes were significantly decreased(P<0.05),and the transcription levels of Dio1 and Thrαgenes were extremely down-regulated(P<0.01)compared with the those of the control group in zebra fish larvae.After tap water recovery for 7 days,the transcription levels of Trh,Dio1,Dio2,Nis,Thrα,and Thrβgenes were not significantly changed compared with those of the control group(P>0.05),but the transcription levels of Tshβwas significantly decreased(P<0.05)in zebra fish larvae.In conclusion,reclaimed water affected the transcription levels of HPT axis-related genes in zebra fish larvae.The effects of reclaimed water on HPT axisrelated genes in zebra fish larvae were recovered after tap water exposure.This study provides a theoretical basis for ecotoxicity effect and risk assessment of endocrine-disrupting chemicals in reclaimed water.