Waterborne exposure to triadimefon causes thyroid endocrine disruption and developmental delay in Xenopus laevis tadpoles.
Triadimefon (TDF) is a triazole-derivative fungicide that is detectable in the environment and target agricultural products, prompting concern over its risk to wildlife and human health. In our study, Nieuwkoop & Faber stage 51 Xenopus laevis tadpoles were exposed to different nominal concentrations TDF (0, 0.112, and 1.12mg/L) for 21 days while the tadpoles were undergoing pre-morphological development. Developmental condition, bioaccumulation and thyroid hormone levels, and mRNA expression of genes involved in the hypothalamic-pituitary-thyroid (HPT) axis were examined. Exposure to TDF caused a reduction in developmental rates on pre-metamorphosis of X. laevis. TDF exposure significantly decreased thyroid hormone (T4 and T3) concentrations, indicating thyroid endocrine disruption. The downregulation of thyroglobulin and upregulation of genes related to thyroid hormone metabolism (ugt1ab) might be responsible for the decreased thyroid hormone concentrations. Treatment with TDF also significantly increased mRNA expression of genes involved in thyroid-stimulating hormone as a compensatory mechanism response to decreased thyroid hormone concentrations. Gene expression and in silico ligand docking studies were combined to study the interaction between TDF and thyroid hormone receptor. Results showed that TDF could consequently affect the HPT axis signaling pathway. In addition, bioconcentration of TDF was observed in tadpoles, indicating the bioactivity of this compound. Taken together, the results suggest that TDF alters the HPT axis-related genes and changes thyroid hormone contents in X. laevis tadpoles, thus causing thyroid endocrine disruption and consequently delaying thyroid hormones-dependent metamorphic development.
Institute of Pesticide and Environmental Toxicology, Zhejiang University, Hangzhou 310058, PR China.
Meng
M
Li
Institute of Pesticide and Environmental Toxicology, Zhejiang University, Hangzhou 310058, PR China.
Shuying
S
Li
Institute of Pesticide and Environmental Toxicology, Zhejiang University, Hangzhou 310058, PR China.
Tingting
T
Yao
Institute of Pesticide and Environmental Toxicology, Zhejiang University, Hangzhou 310058, PR China.
Renjie
R
Zhao
Institute of Pesticide and Environmental Toxicology, Zhejiang University, Hangzhou 310058, PR China. Electronic address: wqiangwei@zju.edu.cn.
Qiangwei
Q
Wang
Institute of Pesticide and Environmental Toxicology, Zhejiang University, Hangzhou 310058, PR China.
Guonian
G
Zhu
D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D052244:Endocrine Disruptors / Q000378:metabolism / Q000633:toxicity*; D005659:Fungicides, Industrial / Q000378:metabolism / Q000633:toxicity*; D007814:Larva / Q000502:physiology; D008675:Metamorphosis, Biological / Q000187:drug effects / Q000502:physiology; D013961:Thyroid Gland / Q000187:drug effects* / Q000378:metabolism; D013963:Thyroid Hormones / Q000378:metabolism*; D018675:Toxicity Tests; D014230:Triazoles / Q000378:metabolism / Q000633:toxicity*; D014874:Water Pollutants, Chemical / Q000378:metabolism / Q000633:toxicity*; D014982:Xenopus laevis / Q000502:physiology*
D015415:Biomarkers; D052244:Endocrine Disruptors; D005659:Fungicides, Industrial; D013963:Thyroid Hormones; D014230:Triazoles; D014874:Water Pollutants, Chemical; C032910:triadimefon
Fungicides; Metamorphosis; Thyroid endocrine disruption; Triadimefon; Xenopus laevis