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EE2 Changes Gene Expression in Fathead Minnow Testis
Citation:
DENSLOW, N. D., N. GARCIA-REYERO, K. J. KROLL, E. F. ORLANDO, K. H. WATANABE, M. S. SEPULVEDA, D. L. VILLENEUVE, E. J. PERKINS, AND G. T. ANKLEY. EE2 Changes Gene Expression in Fathead Minnow Testis. Presented at 15th Annual Symposium on Pollutant Responses in Marine Organisms, Bordeaux, FRANCE, May 17 - 20, 2009.
Impact/Purpose:
To study the effects of environmental estrogens being implicated in altering reproductive health of aquatic animals
Description:
Environmental estrogens have been implicated in altering reproductive health of aquatic animals. Early studies of sewage treatment effluents attributed the feminization of male fish to exposure to mixtures of natural and synthetic estrogens. One of the most potent estrogens known is 17á- ethinylestradiol (EE2) a pharmaceutical that is one of the active ingredients in contraceptives. We have treated male fathead minnows (Pimephales promelas) for 48 hours via the water to 2, 5, 10, and 50 ng 17á- ethinylestradiol (EE2)/L, 100 ng ZM 189,154/L (a potent antiestrogen known to block activity of all estrogen receptors) or to mixtures of 5 or 50 ng EE2/L with 100 ng ZM 189,154/L. We analyzed gene expression changes in the gonad, as well as hormone and vitellogenin plasma levels. Steroidogenesis was down-regulated by EE2 as reflected by the reduced plasma levels of testosterone in the exposed fish and down-regulation of genes in the steroidogenic pathway. Microarray analysis of testis of fathead minnows treated with 5 ng EE2/L or with the mixture of 5 ng EE2/L and 100 ng ZM 189,154/L indicated that some of the genes whose expression was changed by EE2 were blocked by ZM 189,154, while others were either not blocked or enhanced by the mixture, generating two distinct expression patterns. Some of the genes that were competitively blocked by the antiestrogen contain EREs in their promoters in mammalian systems; while a large percentage of genes in the noncompetitive group appear to function in non-genomic signaling pathways. Clearly both pathways alter genes that are necessary for reproduction.