Grantee Research Project Results
2007 Progress Report: Using a Sensitive Japanese Medaka (Oryzias latipes) Fish Model for Endocrine Disruptors Screening
EPA Grant Number: R831299Title: Using a Sensitive Japanese Medaka (Oryzias latipes) Fish Model for Endocrine Disruptors Screening
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 Period Covered by this Report: October 1, 2007 through 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 overall goal of this proposal is to develop and validate a high-throughput endocrine disrupting chemical (EDC) screening assay utilizing a microarray gene chip. The following four objectives were proposed:
- Develop a microarray chip designed to identify EDCs;
- Identify gene expression profiles associated with all the categories of endocrine-disrupting activity;
- Conduct a statistical analysis of gene expression profiles to develop response criteria that identify patterns predictive of endocrine disruption; and
- Validate the microarray chip using a set of chemicals selected to represent both positive and negative controls, as well as chemicals with previously undefined endocrine activity.
Progress Summary:
EDCs are believed to act primarily by transcription. Therefore, microarray-based alterations in gene expression can be used as a marker of exposure. We developed and tested an oligonucleotide microarray to identify genetic activity of six prototypic EDCs. These EDCs were selected to represent agonist/antagonist pairs for three hormone receptor systems: estrogen/anti-estrogen (i.e., 17-β-estradiol/faslodexTM [ICI 182,780]); androgen/anti-androgen (i.e., 11-ketotestosterone/flutamide); and thyroidogen/anti-thyroidogen (i.e., thyroid hormone [T3]/amiodarone).
Range-finding experiments with 1-week old male and female Qurt medaka larvae were conducted to determine the biologically effective concentration (BEC) for each EDC. Groups of fish were exposed to each of several different concentrations of our reference EDCs for 96 hours grown to sexual maturity (~3 months), and sacrificed. Endpoints analyzed for evidence of endocrine-related effects from each set of whole fish samples included: incidence of intersex, sex ratios, health indicators (i.e., body weight, body length, condition index), and histopathological biomarkers. As a result, we have identified a BEC for each of the six reference EDCs on male and female medaka. Subsequently, the identified BECs were used as exposure concentrations for characterizing the microarray-based response to each EDC. In these latter experiments, male and female medaka were exposed (number of replicates per gender = 3; number of larvae per replicate = 200) to each EDC, sacrificed, and the RNA was isolated for microarray analyses.
After RNA isolation at the University of California-Davis, the genetic material was sent to Combimatrix Corporation in Washington for sample labeling, hybridization, and preliminary data analysis. The custom medaka oligonucleotide array includes approximately 9,300 separate genomic probes. The main features of the medaka microarray (or gene chip) include: EDC-affected genes (n = 131), medaka cDNAs (n = 1,075), sequences from the medaka genome project (n = 890) and additional sequences extracted from the UniGene database.
Microarray data were analyzed by Dr. Ping-Shi Wu (Lehigh University), a statistician and recent addition to the project team. His analyses identified discrete, statistically significant, gene expression profiles for each of the six EDCs studied to date. Dr. Wu has also completed the first phase of an effort to use a subset of differentially expressed genes from each EDC to discriminate between receptor agonist/anatogonist pairs (e.g., 17B estradiol/faslodex).
The medaka microarray is a sensitive tool for detecting endocrine-disrupting activity. There is clear evidence that the medaka microarray can discriminate between the different types of prototypical EDCs.
Future Activities:
Future research activities include: seeking funding to perform (1) time-course; and (2) dose-response experiments with the prototypical EDCs; (3) to develop integrative software to facilitate data analysis; and (4) to screen environmental water samples for endocrine disrupting activity.
Journal Articles on this Report : 1 Displayed | Download in RIS Format
| Other project views: | All 17 publications | 2 publications in selected types | All 2 journal articles |
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Leon A, Teh SJ, Hall LC, Teh FC. Androgen disruption of early development in Qurt strain medaka (Oryzias latipes). Aquatic Toxicology 2007;82(3):195-203. |
R831299 (2006) R831299 (2007) |
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Supplemental Keywords:
sex differentiation, sex reversal, endocrine disruption, EDCs, androgens, antiandrogens, estrogens, antiestrogens, thyroidogens, goitrogens, antithyroidogens, medaka, genomics, ecotoxicogenomics, toxicogenomics, microarrays, histopathology, biomarkers, water, drinking water, groundwater, exposure, risk, risk assessment, effects, ecological effects, sublethal effects, sensitive populations, dose-response, chemicals, toxins, indicators, aquatic, genetics, monitoring, biologically integrated monitor,, 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 expressionRelevant Websites:
http://www.combimatrix.com/ Exit
http://www.genomics.ucdavis.edu/corefacilities.html Exit
Progress and Final Reports:
Original AbstractThe 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.