Project description:The data comes from a study, where three-spined sticklebacks (Gasterosteus aculeatus) were exposed to di-n-butyl phthalate (DBP) and 17α ethinyl-oestradiol (EE2) at nominal concentrations 35 μg/L and 40 ng/L, respectively, for four days. The aim of the study was to obtain insight into the acute transcriptional responses putatively associated with endocrine disruption. RNA samples from the testes of eight individuals fish per treatment (including solvent controls, exposed only to DMSO) were used in the microarray analysis, covering the expression of approximately 21000 genes.
Project description:There is an urgent demand for more efficient and ethical approaches in chemical risk assessment. Using 17α-ethinylestradiol (EE2) as a model compound, this study established a live-animal alternative embryo benchmark-dose (BMD) assay for rainbow trout (RBT; Oncorhynchus mykiss) to derive transcriptomic points-of-departure (tPODs). Embryos were exposed to graded concentrations of EE2 (0, 1.13, 1.57, 6.22, 16.3, 55.1, and 169 ng/L) from hatch to 4 and up to 60 days post-hatch (dph) to assess molecular and apical responses, respectively. Whole proteome analyses of alevins did not show clear estrogenic effects, while transcriptomics revealed responses that were in agreement with apical effects including excessive accumulation of intravascular and hepatic proteinaceous fluid and significant increases in mortality at 55.1 and 169 ng/L EE2 at later time points. Transcriptomic BMD analysis estimated the median of the 20th lowest geneBMD to be 0.18 ng/L; the most sensitive tPOD. Other estimates (0.78, 3.64, and 1.63 ng/L for the tenth percentile geneBMD, first peak geneBMD distribution, and median geneBMD of the most sensitive overrepresented pathway, respectively) were within the same order of magnitude as empirically derived apical P ODs for EE2 in the literature. This 4-day alternative RBT embryonic assay was effective in deriving protective tPODs for EE2.
Project description:Aquatic organisms are continuously exposed to complex mixtures of chemicals, many of which can interfere with their endocrine system, resulting in impaired reproduction, development or survival, among others. In order to analyze the effects and mechanisms of action of estrogen/anti-estrogen mixtures, we exposed male fathead minnows (Pimephales promelas) for 48 hours via the water to 2, 5, 10, and 50 ng 17α- ethinylestradiol (EE2)/L, 100 ng ZM 189,154/L (a potent antiestrogen known to block activity of all estrogen receptors) or mixtures of 5 or 50 ng EE2/L with 100 ng ZM 189,154/L. We analyzed gene expression changes in the gonad, as well as hormone and vitellogenin plasma levels. Steroidogenesis was down-regulated by EE2 as reflected by the reduced plasma levels of testosterone in the exposed fish and down-regulation of genes in the steroidogenic pathway. Microarray analysis of testis of fathead minnows treated with 5 ng EE2/L or with the mixture of 5 ng EE2/L and 100 ng ZM 189,154/L indicated that some of the genes whose expression was changed by EE2 were blocked by ZM 189,154, while others were either not blocked or enhanced by the mixture, generating two distinct expression patterns. Gene ontology and pathway analysis programs were used to determine categories of genes for each expression pattern. Our results suggest that response to estrogens occurs via multiple mechanisms, including canonical binding to soluble estrogen receptors, membrane estrogen receptors, and other mechanisms that are not blocked by pure antiestrogens.
Project description:There is an urgent demand for more efficient and ethical approaches in chemical risk assessment. Using 17α-ethinylestradiol (EE2) as a model compound, this study established a live-animal alternative embryo benchmark-dose (BMD) assay for rainbow trout (RBT; Oncorhynchus mykiss) to derive transcriptomic points-of-departure (tPODs). Embryos were exposed to graded concentrations of EE2 (0, 1.13, 1.57, 6.22, 16.3, 55.1, and 169 ng/L) from hatch to 4 and up to 60 days post-hatch (dph) to assess molecular and apical responses, respectively. Whole proteome analyses of alevins did not show clear estrogenic effects, while transcriptomics revealed responses that were in agreement with apical effects including excessive accumulation of intravascular and hepatic proteinaceous fluid and significant increases in mortality at 55.1 and 169 ng/L EE2 at later time points. Transcriptomic BMD analysis estimated the median of the 20th lowest geneBMD to be 0.18 ng/L; the most sensitive tPOD. Other estimates (0.78, 3.64, and 1.63 ng/L for the tenth percentile geneBMD, first peak geneBMD distribution, and median geneBMD of the most sensitive overrepresented pathway, respectively) were within the same order of magnitude as empirically derived apical PODs for EE2 in the literature. This 4-day alternative RBT embryonic assay was effective in deriving protective tPODs for EE2.
Project description:Sex steroids play a key role in triggering sec differentiation in fish and the use of exogenous hormone treatment leads to partial or complete sex reversal. This phenomenon has attracted attention since the discovery taht even low environmental doses of exogenous steroids can adversely affect gonad morphology (ovotestis development) and induce reproductive failure. Modern genomic-based technologies have enhanced opportunities to find mechanisms of action (MOA) and dentify biomarkers for the toxic action of a compound. The goal of this study are to improve the understanding of feminization in fish by analyzing gene expression patterns in the gonads of rainbow trout fry after a chronic exposure to several doses (0.01, 0.1, 1 and 10 μg/L) of ethynylestradiol (EE2) and to offer target genes as potential biomarkers of ovotestis development.
Project description:17α-Ethinylestradiol (EE2) is a ubiquitous aquatic contaminant shown to decrease fish fertility at low concentrations, especially in fish exposed during development. The mechanisms of the decreased fertility are not fully understood. In this study, we perform transcriptome analysis by RNA sequencing of testes from zebrafish with previously reported lowered fertility due to exposure to low concentrations of EE2 during development. Fish were exposed to 1.2 and 1.6 ng/L (measured concentration) of EE2 from fertilization to 80 days of age, followed by 82 days of remediation in clean water.
Project description:The objective of this study was to gain mechanistic insight into how mummichog are able to produce eggs during exposures to high levels of EE2. Mummichog were exposed to 0, 50 or 250 ng/L of EE2 for 14 d. A mummichog microarray was used to identify genomic responses associated with high EE2 exposure, and effects of EE2 on target genes involved in lipid mobilization and transport and steroidogenesis, two important (EE2 regulated) pathways involved in egg production, were measured using real-time PCR. In addition, changes at higher level biological endpoints such as plasma steroid production and gonad morphology were measured to examine downstream responses to EE2. There were no differences in gonadosomatic index, liversomatic index, gonad development, or plasma estradiol levels after exposure to EE2, although testosterone decreased with EE2 exposures. Similar to other species, mummichog showed alterations to plasma steroid levels, and similar processes at the molecular level were identified as being altered by EE2, including cell processes associated with lipids. However, unlike other species, mummichog showed no differences in GSI or ovarian development. Fatty acids were affected at both the transcript and translation level, which suggests they are a major target of estrogens. Lipids are important for both growth and reproduction, and provide oocytes with nutrients. Interestingly, mummichog showed no effect on apolipoprotein expression, which is important in lipid transport. Therefore, it is hypothesized that mummichog are normally able to transport lipids for energy and nutrients to the ovary, while this is affected in other species. Novel gene regulatory networks for protein modification targets were also constructed to learn more about the potential roles of estrogens in the teleost liver. Although post-translational modifications (PTMs) are important regulatory mechanisms, the roles of PTMs in protein regulation in fish and the susceptibility of PTMs to aquatic pollutants are largely unexplored and may offer novel insight into mechanisms of endocrine disruption.