Unknown,Transcriptomics,Genomics,Proteomics

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Evaluation of hepatic gene expression profiles during androgen exposure in female mosquitofish

ABSTRACT: The Eastern Mosquitofish (Gambusia holbrooki) is a non-model species with the potential for development of biomarkers of endocrine disrutpting chemical (EDC) exposure due to its androgen-driven secondary sexual characteristics. While G. holbrooki have been utilized in the field as bioindicator organisms EDC exposure in areas impacted by pulp and paper mills, the lack of molecular tools and general understanding of how G. holbrooki are impacted by androgen exposure hinder the use of this organism as a widespread tool for the evaluation of these chemicals in the environment. While traditional gene-by-gene approaches have provided a list of genes that may be appropriate for developing into biomarkers of androgen exposure, a more inclusive method could provide more rapid and expansive determination of genes that can be developed into biomarkers of androgen exposure. The objective of this study is toutilize a mosquitofish microarray to determine potential biomarkers of chronic androgen exposure. The specific aim was to determine genes that may be developed into biomarkers of chronic androgen exposure in hepatic tissues using 17M-NM-2-trenbolone (TB) exposed adult female G. holbrooki by microarray analysis. Liver tissues from a 14-day exposure of female G. holbrooki to 1 M-BM-5g/L of the potent androgen receptor agonist 17M-NM-2-trenbolone (17M-NM-2-hydroxyestra-4,9,11-trien-3-one; abbreviated as TB) [Brockmeier 2013] were used as the first sample for microarray analysis using the custom G. holbrooki microarray to determine genes that were significantly up or down-regulated during a chronic androgen agonist exposure. RNA was isolated from the livers as previously described using TRIzol (Invitrogen, Grand Island, USA), hydrated using RNAsecure (Ambion, Grand Island, USA), and DNase treated using the Turbo DNA-free kit (Ambion, Grand Island, USA). Four oocyte-development stage-matched RNA samples per treatment were evaluated for RNA integrity using the 2100 BioAnalyzer (Agilent, Santa Clara, USA). The range of RIN values was 8.3-8.9.

ORGANISM(S): Gambusia holbrooki

SUBMITTER: Erica Brockmeier

PROVIDER: E-GEOD-45261 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Triclocarban (TCC) is a widely used antimicrobial agent that is routinely detected in surface waters. The present study was designed to examine TCC’s efficacy and mode of action as a reproductive toxicant in fish. Reproductively mature Pimephales promelas were continuously exposed to either 1 or 5 μg TCC/L, 0.5 μg 17β-trenbolone (TRB)/L or a mixture (MIX) of 5 μg TCC and 0.5 μg TRB/L for 22 d and a variety of reproductive and endocrine-related endpoints were examined. The data were evaluated to answer several key questions: first, whether exposure to TCC could be linked with an ecologically-relevant adverse outcome, i.e., impaired reproduction; second, whether the present study provided additional support for augmentation of androgen action as an endocrine-disrupting mode of action for TCC; and third, whether there were any novel and/or plausible linkages between changes in the ovarian transcriptome and the apical responses observed in females that could support adverse outcome pathway development and/or further hypothesis-driven testing. Fathead minnows were randomly paired (one male, one female) and placed in tanks at a density of two pairs per tank with six replicate tanks per treatment. Pairs were separated by a water permeable mesh divider and each pair had its own breeding substrate. The fish were held in the test system, receiving UV-treated, filtered Lake Superior (control) water only, for a 21 d acclimation period during which the fecundity and fertility of each pair were assessed daily. After 21 d, exposures were initiated with pairs that had spawned successfully during acclimation. Fish were exposed continuously to target test concentrations of 0 (Lake Superior control), TCC (1 and 5 µg/L), TRB (0.5 μg/L), or a mixture of the two chemicals (5 μg TCC and 0.5 μg TRB/L) for 22 d. Water concentrations of TCC and TRB were determined in stock solutions and all exposure tanks every two to three days. General water quality characteristics (mean ± SD) measured regularly over the course of the Experiment were: temperature, 24.8 ± 0.7 oC; pH, 7.87 ± 0.04; dissolved oxygen, 6.8 ± 0.35 mg/L. Ovary RNA samples from twenty four fish (n=5 for all treatments except TRB alone; n=4) were selected for microarray analysis.

Project description:Masculinized female Eastern Mosquitofish (Gambusia holbrooki) have resided downstream of paper mills in Florida since the 1980's. The potential impacts of this effluent on the mosquitofish endocrine system are unknown. The objective of this study was to evaluate gene expression patterns of endocrine system genes and global gene expression patterns in female G. holbrooki from a paper mill-impacted site. Masculinized female G. holbrooki were collected from a paper mill-impacted site (Fenholloway River) and from a reference site (Econfina River) and microarray analysis in livers was conducted. Hepatic microarray analysis revealed an increase in the expression of metabolic genes at the Fenholloway, with similarities in individual genes and biological processes compared to G. holbrooki exposed to androgens. These data indicate G. holbrooki from the Fenholloway may be impacted by a mixture of endocrine-active chemicals, including androgens. During the summer of 2012, G. holbrooki were captured from one site downstream of the Buckeye Pulp and Paper Mill (Taylor County, Perry, FL, USA) on the Fenholloway River (GPS coordinates: N 30 058.341’, W 83 588.569’) and one site in the Econfina conservation area (GPS coordinates: N 30 08.549', W 83 51.962') . Only sexually mature G. holbrooki (females > 15cm standard length and with the presence of the gravid spot near the vent) were collected. A 1/8 mesh seine was used for sample collection. Female G. holbrooki were transferred to 5 gallon aerated buckets filled with site water and were processed at the site immediately after collection. Fish were anesthetized using Tricaine-S (Western Chemical, Ferndale, USA) and sacrificed via spinal transection. Oocyte development was assessed upon dissection and livers were removed and stored in RNAlater (Qiagen, Hilden, Germany) overnight at 4 C before storage at -80 C. RNA was isolated from the livers using TRIzol (Invitrogen, Grand Island, USA), hydrated using RNAsecure (Ambion, Grand Island, USA), and DNase treated using the Turbo DNA-free kit (Ambion, Grand Island, USA). Four oocyte-development stage-matched RNA samples per treatment were evaluated for RNA integrity using the 2100 BioAnalyzer (Agilent, Santa Clara, USA). The range of RIN values was 7.8-8.9.

Project description:The anabolic androgen 17M-NM-2-trenbolone (TB) can cause masculinization and reduce fecundity of fish. However, the underlying mechanisms of various biological pathways including metabolism, biosynthesis etc. are largely unknown. Here, we evaluated the effects of TB using the medaka DNA microarray representing 36,398 genes. Larval medaka, Oryzias latipes, (within 24 hrs posthatch) were exposed to TB at various concentrations (2, 6, 20, 60, 100, 200 ng/L) for up to 7 days. Dose-response relationships in gene expression levels of the categorized genes were analyzed using the cumulative chisquared method. Microarray analyses of the TB-exposed larvae showed that 117 and 32 genes were determined as up and down-regulated genes, respectively. The most significant GO term for biological process identified within this gene list was lipid metabolic process, which contained 26 genes in up-regulated genes. In this category, M-bM-^@M-^\cholesterol biosynthetic processM-bM-^@M-^] was highlighted as an important subcategory with 15 genes, including hydroxymethylglutaryl-CoA synthase cytoplasmic, squalene monooxygenase, lanosterol synthase etc. RT-PCR measurements in these genes were consistent with the microarray results in the direction and magnitude of these changes in gene expression. On the other hands, in the category of M-bM-^@M-^\sexual differentiation and developmentM-bM-^@M-^], genes related to hypothalamic-pituitary-gonadal (HPG) axis were not affected by TB treatment except for one gene encoded to cytochrome P450 19A1. Genes related to oogenesis, such as choriogenins and vitellogenins were weakly down regulated at 2-200 ng/L of TB. Our findings demonstrate that genes encoding cholesterol synthesis pathway via the mevalonate pathway were controlled by TB in larval medaka. TB concentrations used were 0 (control), 2, 6, 20, 60, 100 and 200 ng/L for 7 days of exposure. Each TB treatment had 90 larval medaka for each chamber. At day 7 of the exposures, triplicate samples (30 larvae/sample) from each chamber respectively were collected, flash-frozen in liquid nitrogen, and stored in liquid nitrogen until RNA extraction.

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Evaluation of hepatic gene expression profiles during androgen exposure in female mosquitofish

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