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DEVELOPMENT, APPLICATION AND VALIDATION OF A SHEEPSHEAD MINNOW ESTROGEN-RESPONSIVE CDNA MACROARRAY
Citation:
Hemmer, M J. AND L C. Folmar. DEVELOPMENT, APPLICATION AND VALIDATION OF A SHEEPSHEAD MINNOW ESTROGEN-RESPONSIVE CDNA MACROARRAY. Presented at Ecotoxicogenomics Workshop, Pensacola, FL, Sep 23-25, 2002.
Description:
This presentation provides an overview of research conducted by the Gulf Ecology Division investigating the effects of endocrine disrupting chemicals on estuarine fish species. A series of research studies were initiated to examine the comparative dose-response characteristics and potencies of estrogenic chemicals using the sheepshead minnow (Cyprinodon variegatus) as a small fish model. These studies required the development of procedures for measuring hepatic vitellogenin (VTG) mRNA synthesis and serum VTG levels in male sheepshead minnows in response to aqueous exposure to natural, pharmaceutical and xeno-estrogenic chemicals. The time-course of hepatic VTG mRNA regulation and VTG plasma accumulation and clearance
kinetics were also determined to add a temporal component to the field application and interpretation of VTG as a biomarker of exposure. In further studies, differential display techniques were applied to samples taken from dose-response studies to discriminate variably expressed gene fragments between untreated control fish and fish treated with 17b-estradiol. Information from these studies were used to develop an estrogen-responsive cDNA membrane macroarray. Laboratory validation of the macroarray was accomplished by measuring the hepatic expression of these genes in male sheepshead minnows using fish previously exposed to 17b-estradiol, 17a-ethynyl estradiol, diethystilbestrol, methoxychlor and p-nonylphenol. Identical patterns of gene expression were observed between native ligand,17b-estradiol and the four estrogenic compounds tested. In addition, intensities of the gene responses as measured on the macroarrays clearly followed a dose-response pattern for each chemical tested. The research described is the first step toward developing a suite of specific macroarrays for application to chemical screening and prioritization programs, or as a monitoring tool to identify chemical contamination of aquatic environments.