title: Effects of 17α-ethinylestradiol at different water temperatures on zebrafish sex differentiation and gonad development.
abstract: In the current climate change scenario, studies combining effects of water contaminants with environmental parameters, such as temperature, are essential to predict potentially harmful impacts on aquatic organisms. In zebrafish (Danio rerio), sex determination seems to have a polygenic genetic basis, which can be secondarily influenced by environmental factors, such as temperature and endocrine disrupting chemicals (EDCs). The present study aimed to evaluate the effects of the EDC 17α-ethinylestradiol (EE2), a potent synthetic estrogen, on zebrafish sex differentiation and gonad development at different water temperatures. Therefore, zebrafish raised at three distinct water temperatures (23, 28 or 33±0.5°C), were exposed to 4ng/L of EE2, from 2hours to 60days post-fertilization (dpf). Subsequently, a quantitative (stereological) assessment of zebrafish gonads was performed, at 35 and 60dpf, to identify alterations on gonadal development and differentiation. The results show that low temperature delayed general growth of zebrafish, as well as gonad differentiation and maturation, while high temperature induced an opposite effect. Moreover, sex ratio was skewed toward males when zebrafish were exposed to the high temperature. In general, EE2 exposure promoted gonad maturation in both genders, independently of the temperature. However, at the high temperature condition, exposure to EE2 induced a delay in the male gonad development, with some individuals still showing differentiating gonads at 60dpf. The findings of this study support the notion that zebrafish has a genetic sex determination mechanism highly sensitive to environmental factors and show that it is essential to study the effects of water contaminants at different climate scenarios in order to understand potential future impacts on organisms.
authors.affiliation: Centre for the Research and Technology of Agro-Environmental and Biological Sciences, CITAB, Departamento de Biologia e Ambiente (DeBA), University of Trás-os-Montes and Alto Douro, UTAD, Quinta de Prados, 5000-801 Vila Real, Portugal; Life Sciences and Environment School, University of Trás-os-Montes and Alto Douro, UTAD, Quinta de Prados, 5000-801 Vila Real, Portugal. Electronic address: aluzio@utad.pt.
authors.forename: Ana
authors.initials: A
authors.lastname: Luzio
authors.affiliation: Life Sciences and Environment School, University of Trás-os-Montes and Alto Douro, UTAD, Quinta de Prados, 5000-801 Vila Real, Portugal.
authors.forename: Dércia
authors.initials: D
authors.lastname: Santos
authors.affiliation: Centre for the Research and Technology of Agro-Environmental and Biological Sciences, CITAB, Departamento de Biologia e Ambiente (DeBA), University of Trás-os-Montes and Alto Douro, UTAD, Quinta de Prados, 5000-801 Vila Real, Portugal; Life Sciences and Environment School, University of Trás-os-Montes and Alto Douro, UTAD, Quinta de Prados, 5000-801 Vila Real, Portugal.
authors.forename: António A
authors.initials: AA
authors.lastname: Fontaínhas-Fernandes
authors.affiliation: Centre for the Research and Technology of Agro-Environmental and Biological Sciences, CITAB, Departamento de Biologia e Ambiente (DeBA), University of Trás-os-Montes and Alto Douro, UTAD, Quinta de Prados, 5000-801 Vila Real, Portugal; Life Sciences and Environment School, University of Trás-os-Montes and Alto Douro, UTAD, Quinta de Prados, 5000-801 Vila Real, Portugal.
authors.forename: Sandra M
authors.initials: SM
authors.lastname: Monteiro
authors.affiliation: Centre for the Research and Technology of Agro-Environmental and Biological Sciences, CITAB, Departamento de Biologia e Ambiente (DeBA), University of Trás-os-Montes and Alto Douro, UTAD, Quinta de Prados, 5000-801 Vila Real, Portugal; Life Sciences and Environment School, University of Trás-os-Montes and Alto Douro, UTAD, Quinta de Prados, 5000-801 Vila Real, Portugal. Electronic address: acoimbra@utad.pt.
authors.forename: Ana M
authors.initials: AM
authors.lastname: Coimbra
mesh_terms: D000818:Animals; D057231:Climate Change; D052244:Endocrine Disruptors / Q000633:toxicity; D004997:Ethinyl Estradiol / Q000633:toxicity*; D005260:Female; D005306:Fertilization / Q000187:drug effects; D006066:Gonads / Q000187:drug effects*; D008297:Male; D012733:Sex Differentiation / Q000187:drug effects*; D012744:Sex Ratio; D013696:Temperature; D014867:Water / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000633:toxicity; D015027:Zebrafish / Q000254:growth & development*
chemical_list: D052244:Endocrine Disruptors; D014874:Water Pollutants, Chemical; D014867:Water; D004997:Ethinyl Estradiol
keywords: 17α-Ethinylestradiol; Danio rerio; Sex differentiation; Sex ratio; Stereology; Temperature