Unknown,Transcriptomics,Genomics,Proteomics

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Getting inside of the molecular pathways associated with intersex in the rainbow darter (Etheostoma caeruleum)

ABSTRACT: Rainbow darter (Etheostoma caeruleum) are a small benthic fish found in North America. This species is sensitive to sewage effluent in the environment, showing the presence of intersex in up to 80% of males in near-field areas in the Grand River, ON. To learn more about the molecular events associated with intersex, we developed a customized oligonucleotide microarray (4x180K) with next generation sequencing (454 Roche) to characterize molecular responses in the gonad. Transcriptomics was performed on both males and females from both a reference site and a polluted site. Males with and without intersex from the polluted site were compared to the control males. Rainbow darter were sampled from from the Grand River in May 2011. Fish were selected according to the location, gonad maturity, and intersex index. Reference fish were taken from the upstream to the urban area; exposed fish were taken from downstream of from Kitchener MWWE treatment plant.

ORGANISM(S): Etheostoma caeruleum

SUBMITTER: Paulina Bahamonde

PROVIDER: E-GEOD-57394 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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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:Abstract. The molecular pathways in embryonic vertebrates leading to gonad formation in each sex are incompletely understood. The purpose of this study was to identify novel genes that could be associated with sex-specific gonadal differentiation in a fish, the rainbow trout (Oncorhynchus mykiss). This study was facilitated by a custom microarray based on 7,681 genes derived from embryonic rainbow trout gonad cDNA libraries and public databases. Gonad samples for total RNA isolation were obtained from pvasa-green fluorescent protein (pvasa-GFP) transgenic rainbow between 300 and 700 degree days of development post-fertilization. The transgenic fish permitted the collection of gonads from embryonic rainbow trout during the period of molecular sex differentiation in advance of any morphologically distinguishable characteristics of sex. A bioinformatic method was used with the microarray data that looked for strong associations in gene expression patterns between known sex differentiation genes (the target genes) and novel genes (the target-associated genes) previously not allied with sex differentiation in fishes. The expression patterns of representative targets genes from both sexes and their target-associated genes were independently confirmed by real-time reverse transcription-polymerase chain reaction to support the validity of the bioinformatics method employed. Numerous, novel genes were identified in the gonads of embryonic female and male rainbow trout that could be involved in sex-specific differentiation pathways in this fish. Embryonic gonads were removed by dissection from known genetic female (XX) and male (XY) rainbow trout (Oncorhynchus mykiss) from a transgenic population where expression of GFP is controlled by vasa-gene regulatory elements (Yoshizaki et al. 2000; Takeuchi et al. 2002). These fish were maintained in incubators containing flowing freshwater (10Â°C) at the Ooizumi Research Station, Yamanashi, Japan. Ten female or male transgenic rainbow trout were randomly selected every 5 days, beginning at 30 days (i.e., 300 degree days = incubation temperature in Â°C x number of days) post fertilization through until 70 days (i.e., 700 degree days) post fertilization. The gonads from each sex, at each sampling time, were pooled and immediately frozen for subsequent total RNA isolation.

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Getting inside of the molecular pathways associated with intersex in the rainbow darter (Etheostoma caeruleum)

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