Research Areas > Contaminants > Contaminants of Emerging Concern > Effects on Biota > Causes of Endocrine Disruption in Fish

Project: Causes of Endocrine Disruption in Fish

Background and Objective

Several indicators of endocrine disruption have been detected in fish collected from areas near large POTWs, but it is not known what specifically causes these effects (e.g., legacy contamination, ongoing discharges, combination of factors). Both the source and identity of the endocrine disrupting compounds (EDCs) need to be determined before appropriate management actions can be taken. Unfortunately, data from previous studies are not sufficient for determining the source of contaminant exposure, largely due to technology limitations and expense of acquiring a large dataset. Rapid advances in biotechnology have resulted in new tools, which use microarray technology to measure changes in gene expression.

The goal of this project is to develop and apply a gene microarray tool for investigating contaminant exposure and identifying impacts on sentinel organisms in the coastal marine environment. This project is comprised of four objectives:

1) Compare microarray results to more intensive measures of chemical exposure and biological response;
2) Examine relationships between endocrine disruption in lab-exposed or wild fish to the level of contaminant exposure associated with POTW effluent or nonpoint (runoff) discharges;
3) Determine whether microarray results correspond to other environmental assessment methods; and
4) Develop microarrays for other sentinel species.

Status

This is an ongoing study with completion anticipated in 2011.

Methods

SCCWRP is working with the collaborators at University of California, San Diego and other institutions to develop gene microarrays and other genomics tools that can be used to study endocrine disruption in local fish species. Searches of gene libraries are being performed to identify highly conserved gene sequences among a variety of species that can be used in microarrays. Newly developed microarrays will be tested and validated by application to fish tissue samples from contaminated field sites, as well as laboratory exposures to model endocrine disruptors (e.g., estradiol) and complex mixtures (e.g., wastewater effluent). Comparison of the microarray results with concurrent measurements of hormone concentrations and gene expression (via quantitative PCR or qPCR) will indicate the sensitivity, accuracy, and specificity of the microarray as a screening tool to investigate endocrine disruption effects.
 

Findings

Preliminary results of the microarray validation experiments are promising. The microarray is able to hybridize with RNA from diverse species including freshwater zebrafish and marine flatfish (hornyhead turbot). Relative measurements of gene expression in hornyhead turbot obtained using the microarray have also been shown to correspond to qPCR data.

Preliminary results from validation experiments have demonstrated the potential utility of the microarray for identifying characteristic response patterns to endocrine disrupting chemicals (see figure below).

Partners

University of California, San Diego
University of California, Riverside
California State University, Long Beach
Ocean Institute
Orange County Sanitation District
City of San Diego
City of Los Angeles
Los Angeles County Sanitation Districts
City of Oxnard

Presentation

• Gene Microarray Development for Investigating Emerging Contaminant Effects (Video)- January 2009 presentation to SCCWRP member agencies. Discusses the potential applications of gene microarray technology in SCCWRP's contaminant research.