Grantee Research Project Results

Using a Sensitive Japanese Medaka (Oryzias latipes) Fish Model for Endocrine Disruptors Screening

EPA Grant Number: R831299
Title: Using a Sensitive Japanese Medaka (Oryzias latipes) Fish Model for Endocrine Disruptors Screening
Investigators: Teh, Swee J. , Hall, Linda , Bartosiewicz, Mathew , Johnson, Michael
Current Investigators: Teh, Swee J. , Hall, Linda , Johnson, Michael
Institution: University of California - Davis
EPA Project Officer: Aja, Hayley
Project Period: October 1, 2004 through September 30, 2006 (Extended to September 30, 2008)
Project Amount: $399,168
RFA: Development of High-Throughput Screening Approaches for Prioritizing Chemicals for the Endocrine Disruptors Screening Program (2003) RFA Text | Recipients Lists
Research Category: Endocrine Disruptors , Environmental Justice , Human Health , Safer Chemicals

Objective:

The objective of the proposed research is to develop a rapid, sensitive, biologically-integrated screening assay to identify endocrine-disrupting chemicals (EDCs) using a sensitive medaka (Oryzias latipes) fish model. Specifically, the proposed research will focus on two identified areas of interest:

identification and evaluation of endocrine disrupting chemicals (EDCs),
and categorization of EDCs into estrogenic, anti-estrogenic, androgenic, anti-androgenic, thyroidogenic, and anti-thyroidogenic activity.

Approach:

In the first year, we propose to create a medaka cDNA library from pooled livers, gonads, craniums (a source of brain, pituitary, and thyroid gland) of adult medaka exposed to 6 groups of endocrine disruptors (estrogenic, anti-estrogenic, androgenic, anti-androgenic, thyroidogenic, and anti-thyroidogenic). This approach will provide us with a cDNA library that is enriched in transcripts specifically upregulated by these prototypical EDCs. 5000 individual clones from this library will be sequenced and unique Expressed Sequence Tags (ESTs) will be polymerase chain reaction (PCR) amplified, and used to create the glass slide microarrays. Once developed, predictive gene sets will be identified by exposing medaka to three additional compounds per endocrine disruptor group and evaluating the resulting microarray gene expression patterns with standard statistical tools. In the second and third years, we will test the predictive ability of the microarray gene chip with:

a suite of known EDCs representative of each category of EDC,
substances previously identified as lacking endocrine activity,
and substances not previously characterized as to their endocrine activity.

We will screen these compounds and compare their gene expression profiles or "signatures" to the prototypic EDC profiles and classify the chemicals as:

not an EDC,
low probability of endocrine disrupting (ED) activity,
moderate probability of ED activity,
and high probability of ED activity.

Once each compound has been classified, one chemical from each category will be tested on 1-week-old larvae to confirm the scoring system. A subgroup of the larvae will be allowed to grow to maturity, and growth, sexual abnormalities, and histopathology will be determined to confirm endocrine disruption.

Expected Results:

Our screening assay will enable us to accurately identify gene expression patterns that are both causative and/or predictive of endocrine disruption. Development of a medaka microarray chip will provide a powerful screening tool that can simultaneously yield information on not only the parent chemical's ED activity but also any active metabolites. The basic screening system is also directly amenable to the future characterization of organ-specific responses to EDCs, as well as to characterizing differences in EDC gene-expression profiles associated with exposure of different life stages. Furthermore, assessment of complex contaminant mixtures of EDCs will be possible with this novel method and could greatly facilitate future aquatic environmental EDCs identification and evaluation.

Publications and Presentations:

Publications have been submitted on this project: View all 17 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 2 journal articles for this project

Supplemental Keywords:

water, exposure, risk assessment, ecological effects, dose-response, fish, sex, toxics, indicators, aquatic, integrated assessment, pollution prevention, innovative technology, cost-benefit, genetics, pathology, models, measurement methods, decision making., Health, RFA, Scientific Discipline, Health Risk Assessment, Biology, Endocrine Disruptors - Human Health, endocrine disruptors, Endocrine Disruptors - Environmental Exposure & Risk, Genetics, altered gene expression, altered sexual development, estrogen response, EDCs, developmental biology, Japanese medaka, expressed sequence tags, biochemistry, polymerase chain reaction, endocrine disrupting chemicals, screening assay, biological effects, androgen, endocrine disruption screening assay, rapid genetic screening tool, HPG axis, thyroid toxicants, animal models, endocrine disruptor screening program, gene expression

Progress and Final Reports:

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.