Identification of Metabolites of Trenbolone Acetate in Androgenic Runoff from a Beef Feedlot-1

<p><b>Copyright information:</b></p><p>Taken from "Identification of Metabolites of Trenbolone Acetate in Androgenic Runoff from a Beef Feedlot"</p><p></p><p>Environmental Health Perspectives 2005;114(S-1):65-68.</p><p>Published online 21 Oct 2005</p><p>PMCID:PMC1874171.</p><p>This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original DOI</p

Short-Term Study Investigating the Estrogenic Potency of Diethylstilbesterol in the Fathead Minnow (Pimephales promelas)

Diethylstilbestrol (DES) is a synthetic estrogen that has been banned for use in humans, but still is employed in livestock and aquaculture operations in some parts of the world. Detectable concentrations of DES in effluent and surface waters have been reported to range from slightly below 1 to greater than 10 ng/L. Little is known, however, concerning the toxicological potency of DES in fish. In this study, sexually mature fathead minnows (Pimephales promelas) of both sexes were exposed to 1, 10, or 100 ng of DES/L of water in a flow-through system. Tissue concentrations of DES and changes in a number of estrogen-responsive end points were measured in the fish at the end of a 4 d exposure and after a 4 d depuration/recovery period in clean water. Accumulation of DES was sex-dependent, with females exhibiting higher tissue residues than males after the 4 d exposure. The observed bioconcentration of DES in the fish was about 1 order of magnitude lower than that predicted on the basis of the octanol–water partition coefficient of the chemical, suggesting relatively efficient metabolic clearance by the fish. Exposure to 1, 10, or 100 ng of DES/L caused decreased testis weight and morphological demasculinization of males (regression of dorsal nuptial tubercles). Diethylstilbesterol induced plasma vitellogenin (VTG) in both sexes at water concentrations ≥10 ng/L; this response (especially in males) persisted through the end of the 4 d recovery period. Hepatic transcripts of VTG and estrogen receptor-α also were affected at DES concentrations ≥10 ng/L. Evaluation of transcript profiles in the liver of females using a 15K-gene fathead minnow microarray revealed a concentration-dependent change in gene expression, with mostly up-regulated transcripts after the exposure and substantial numbers of down-regulated gene products after depuration. Genes previously identified as vitellogenesis-related and regulated by 17β-estradiol were significantly enriched among those differentially expressed following exposure to DES. Overall, our studies show that DES causes a range of responses in fish at water concentrations comparable to those reported in the environment and that in vivo potency of the estrogen is on par with that of the better-studied estrogenic contaminant 17α-ethinylestradiol

Ecotoxicogenomics to Support Ecological Risk Assessment: A Case Study with Bisphenol A in Fish

Effects of bisphenol A (BPA) on ovarian transcript profiles as well as targeted end points with endocrine/reproductive relevance were examined in two fish species, fathead minnow (<i>Pimephales promelas</i>) and zebrafish (<i>Danio rerio</i>), exposed in parallel using matched experimental designs. Four days of waterborne exposure to 10 μg BPA/L caused significant vitellogenin induction in both species. However, zebrafish were less sensitive to effects on hepatic gene expression and steroid production than fathead minnow and the magnitude of vitellogenin induction was more modest (i.e., 3-fold compared to 13 000-fold in fathead minnow). The concentration–response at the ovarian transcriptome level was nonmonotonic and violated assumptions that underlie proposed methods for estimating hazard thresholds from transcriptomic results. However, the nonmonotonic profile was consistent among species and there were nominal similarities in the functions associated with the differentially expressed genes, suggesting potential activation of common pathway perturbation motifs in both species. Overall, the results provide an effective case study for considering the potential application of ecotoxicogenomics to ecological risk assessments and provide novel comparative data regarding effects of BPA in fish

Ecotoxicogenomics to Support Ecological Risk Assessment: A Case Study with Bisphenol A in Fish

Effects of bisphenol A (BPA) on ovarian transcript profiles as well as targeted end points with endocrine/reproductive relevance were examined in two fish species, fathead minnow (<i>Pimephales promelas</i>) and zebrafish (<i>Danio rerio</i>), exposed in parallel using matched experimental designs. Four days of waterborne exposure to 10 μg BPA/L caused significant vitellogenin induction in both species. However, zebrafish were less sensitive to effects on hepatic gene expression and steroid production than fathead minnow and the magnitude of vitellogenin induction was more modest (i.e., 3-fold compared to 13 000-fold in fathead minnow). The concentration–response at the ovarian transcriptome level was nonmonotonic and violated assumptions that underlie proposed methods for estimating hazard thresholds from transcriptomic results. However, the nonmonotonic profile was consistent among species and there were nominal similarities in the functions associated with the differentially expressed genes, suggesting potential activation of common pathway perturbation motifs in both species. Overall, the results provide an effective case study for considering the potential application of ecotoxicogenomics to ecological risk assessments and provide novel comparative data regarding effects of BPA in fish

Ecotoxicogenomics to Support Ecological Risk Assessment: A Case Study with Bisphenol A in Fish

Effects of bisphenol A (BPA) on ovarian transcript profiles as well as targeted end points with endocrine/reproductive relevance were examined in two fish species, fathead minnow (<i>Pimephales promelas</i>) and zebrafish (<i>Danio rerio</i>), exposed in parallel using matched experimental designs. Four days of waterborne exposure to 10 μg BPA/L caused significant vitellogenin induction in both species. However, zebrafish were less sensitive to effects on hepatic gene expression and steroid production than fathead minnow and the magnitude of vitellogenin induction was more modest (i.e., 3-fold compared to 13 000-fold in fathead minnow). The concentration–response at the ovarian transcriptome level was nonmonotonic and violated assumptions that underlie proposed methods for estimating hazard thresholds from transcriptomic results. However, the nonmonotonic profile was consistent among species and there were nominal similarities in the functions associated with the differentially expressed genes, suggesting potential activation of common pathway perturbation motifs in both species. Overall, the results provide an effective case study for considering the potential application of ecotoxicogenomics to ecological risk assessments and provide novel comparative data regarding effects of BPA in fish