title: Influence of Temperature on the Thyroidogenic Effects of Diuron and Its Metabolite 3,4-DCA in Tadpoles of the American Bullfrog (Lithobates catesbeianus).
abstract: Temperature is a key variable affecting the timing of amphibian metamorphosis from tadpoles to tetrapods, through the production and subsequent function of thyroid hormones (TH). Thyroid function can be impaired by environmental contaminants as well as temperature. Tadpoles can experience large temperature fluctuations in their habitats and many species are distributed in areas that may be impacted by agriculture. Diuron is a widely used herbicide detected in freshwater ecosystems and may impact endocrine function in aquatic organisms. We evaluated the influence of temperature (28 and 34 °C) on the action of diuron and its metabolite 3,4-dichloroaniline (3,4-DCA) on thyroid function and metamorphosis in tadpoles of Lithobates catesbeianus. Exposure to both compounds induced more pronounced changes in gene expression and plasma 3,3',5-triiodothyronine (T3) concentrations in tadpoles treated at higher temperature. T3concentrations were increased in tadpoles exposed to 200 ng/L of diuron at 34 °C and an acceleration of metamorphosis was observed for the same group. Transcriptomic responses included alteration of thyroid hormone induced bZip protein (thibz), deiodinases (dio2, dio3), thyroid receptors (trα, trβ) and Krüppel-like factor 9 (klf9), suggesting regulation by temperature on TH-gene expression. These results suggest that environmental temperature should be considered in risk assessments of environmental contaminants for amphibian species.
authors: Graduate Program in Animal Biology, Department of Chemistry and Environmental Sciences, Universidade Estadual Paulista "Júlio de Mesquita Filho" , Cristóvão Colombo, 2265, 15054-000 São José do Rio Preto, SP, Brazil.
authors: Juliane S
authors: JS
authors: Freitas
authors: Department of Environmental Sciences, University of California , Riverside 900 University Ave, 92521 Riverside, California, United States.
authors: Allison
authors: A
authors: Kupsco
authors: Department of Environmental Sciences, University of California , Riverside 900 University Ave, 92521 Riverside, California, United States.
authors: Graciel
authors: G
authors: Diamante
authors: Graduate Program in Animal Biology, Department of Chemistry and Environmental Sciences, Universidade Estadual Paulista "Júlio de Mesquita Filho" , Cristóvão Colombo, 2265, 15054-000 São José do Rio Preto, SP, Brazil.
authors: Andreia A
authors: AA
authors: Felicio
authors: Department of Natural Sciences, Fundação Universidade Regional de Blumenau , Av. Antonio da Veiga 140, Itoupava Seca 89030-903, Blumenau, Santa Catarina, Brazil.
authors: Eduardo A
authors: EA
authors: Almeida
authors: Department of Environmental Sciences, University of California , Riverside 900 University Ave, 92521 Riverside, California, United States.
authors: Daniel
authors: D
authors: Schlenk
mesh_terms: D000818:Animals; D004237:Diuron / Q000494:pharmacology; D007814:Larva / Q000187:drug effects*; D008675:Metamorphosis, Biological / Q000187:drug effects; D011892:Rana catesbeiana / Q000235:genetics*; D013696:Temperature
chemical_list: D004237:Diuron