Abstract
Using a recently developed approach for testing endocrine disruptive chemicals (EDCs) in amphibians, comprising synchronized tadpole exposure plus genetic and histological sexing of metamorphs in a flow-through-system, we tested the effects of 17β-Trenbolone (Tb), a widely used growth promoter in cattle farming, in three deeply diverged anuran families: the amphibian model species Xenopus laevis (Pipidae) and the non-models Bufo(tes) viridis (Bufonidae) and Hyla arborea (Hylidae). Trenbolone was applied in three environmentally and/or physiologically relevant concentrations (0.027 µg/L (10−10 M), 0.27 µg/L (10−9 M), 2.7 µg/L (10−8 M)). In none of the species, Tb caused sex reversals or masculinization of gonads but had negative species-specific impacts on gonad morphology and differentiation after the completion of metamorphosis, independently of genetic sex. In H. arborea and B. viridis, mounting Tb-concentration correlated positively with anatomical abnormalities at 27 µg/L (10−9 M) and 2.7 µg/L (10−8 M), occurring in X. laevis only at the highest Tb concentration. Despite anatomical aberrations, histologically all gonadal tissues differentiated seemingly normally when examined at the histological level but at various rates. Tb-concentration caused various species-specific mortalities (low in Xenopus, uncertain in Bufo). Our data suggest that deep phylogenetic divergence modifies EDC-vulnerability, as previously demonstrated for Bisphenol A (BPA) and Ethinylestradiol (EE2).
Highlights
IntroductionAmong the complex reasons for global amphibian decline (like industrial agriculture, habitat destruction, invasive species, climate change, land use, and infectious diseases), endocrine disruptive compounds (EDCs) are suspected to play a role in the multiple stress syndrome that this vertebrate class experiences[1,2,3,4,5,6]
Among the complex reasons for global amphibian decline, endocrine disruptive compounds (EDCs) are suspected to play a role in the multiple stress syndrome that this vertebrate class experiences[1,2,3,4,5,6]
Total mortality for this species ranged from 30% (10−8 M) to 42.5% (10−10 M) (Fig. 2, Table 2)
Summary
Among the complex reasons for global amphibian decline (like industrial agriculture, habitat destruction, invasive species, climate change, land use, and infectious diseases), endocrine disruptive compounds (EDCs) are suspected to play a role in the multiple stress syndrome that this vertebrate class experiences[1,2,3,4,5,6]. The most commonly applied synthetic androgen presents Trenbolone (hereafter: Tb), which has been used to increase muscle mass from the seventies of the twentieth century[8,9,10]. Www.nature.com/scientificreports cultures, the isoform 17α was about 20 times less androgenically active compared to the isoform 17β16 but had almost the same activity on the fathead minnow Pimephales promelas[17]. Both isoforms are excreted with cattle feces in concentrations from 5 to 75 ng/g, and their half-life was measured to be about 260 days[12,18]. Other examples are female fathead minnows Pimephales promelas[13] and Japanese medaka Oryzias latipes[25] that developed external male features when exposed to Tb
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