title: Effects of copper on growth, metamorphosis and endocrine disruption of Bufo gargarizans larvae.
abstract: Chinese toad (Bufo gargarizans) tadpoles were exposed to copper (1, 6.4, 32 and 64μgL(-1) copper) from the beginning of larval period through completion of metamorphosis. We examined the effects of chronic copper exposure on mortality, growth, time to metamorphosis, tail resorption time, body size at the metamorphic climax (Gs 42) and completion of metamorphosis (Gs 46) and thyroid gland histology. In addition, type 2 and 3 iodothyronine deiodinase (Dio2 and Dio3), thyroid hormone receptors (TRα and TRβ) mRNA levels were also measured to assess disruption of TH synthesis. Our result showed that 6.4-64μgL(-1) copper concentration increased the mortality and inhibited the growth of B. gargarizans tadpoles. In addition, significant reduction in size at Gs 42 and a time delay to Gs 42 were observed at 6.4-64μgL(-1) copper treatments. Moreover, histological examinations have clearly revealed that 64μgL(-1) copper caused follicular cell hyperplasia in thyroid gland. According to real-time PCR results, exposure to 32 and 64μgL(-1) copper significantly up-regulated mRNA expression of Dio3, but down-regulated mRNA expression of TRα and TRβ mRNA level. We concluded that copper delayed amphibian metamorphosis through changing mRNA expression of Dio3, TRα and TRβ, which suggests that copper might have the endocrine-disrupting effect.
authors.affiliation: College of Life Science, Shaanxi Normal University, Xi'an 710119, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Wang
authors.affiliation: College of Life Science, Shaanxi Normal University, Xi'an 710119, China.
authors.forename: Gang
authors.initials: G
authors.lastname: Liang
authors.affiliation: School of Environmental Science and Engineering, Chang'an University, Xi'an 710054, China; Key Laboratory of Subsurface Hydrology and Ecological Effect in Arid Region of Ministry of Education, Xi'an 710062, China.
authors.forename: Lihong
authors.initials: L
authors.lastname: Chai
authors.affiliation: College of Life Science, Shaanxi Normal University, Xi'an 710119, China. Electronic address: hongyuanwang@snnu.edu.cn.
authors.forename: Hongyuan
authors.initials: H
authors.lastname: Wang
mesh_terms: D000818:Animals; D049628:Body Size / Q000187:drug effects; D002025:Bufonidae / Q000235:genetics / Q000254:growth & development*; D003300:Copper / Q000633:toxicity*; D052244:Endocrine Disruptors / Q000633:toxicity*; D004781:Environmental Exposure / Q000032:analysis; D007453:Iodide Peroxidase / Q000235:genetics / Q000378:metabolism; D007814:Larva / Q000187:drug effects; D008675:Metamorphosis, Biological / Q000187:drug effects*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011988:Receptors, Thyroid Hormone / Q000235:genetics / Q000378:metabolism; D013623:Tail; D013961:Thyroid Gland / Q000187:drug effects; D013997:Time Factors; D014874:Water Pollutants, Chemical / Q000633:toxicity
chemical_list: D052244:Endocrine Disruptors; D012333:RNA, Messenger; D011988:Receptors, Thyroid Hormone; D014874:Water Pollutants, Chemical; D003300:Copper; D007453:Iodide Peroxidase
keywords: Bufo gargarizans; Copper; Endocrine disruption; Growth; Metamorphosis