Molecular Biomarkers: Endocrine Disruptors and Environmental Health

Personal care products and human pharmaceuticals are widely used and have been found in surface waters around the world.  These products have been designed to exert biological effects on target organisms, e.g., in the case of pharmaceuticals on humans, but when released into the environment they can also affect aquatic non-target organisms.  New advances in next generation sequencing technology have catapulted the use of molecular tools, such as microarrays, to assess the effects of exposures on fish.  Microarray technology is a relatively novel tool in ecotoxicology, but the ability to use a global analysis to understand the effects on fish of exposure to mixtures of anthropogenic chemicals has focused interest in this area.  Fathead minnows (Pimephales promelas) were treated with 17α-ethinylestradiol, the estrogen antagonist, ZM 189,154, 17β-trenbolone (androgen) and the androgen antagonist, flutamide.  For ethinylestradiol many genes were up regulated including those involved in the production of good quality eggs and sex hormone synthesis while other genes were down regulated by the exposures.  Genes altered by trenbolone include those involved in signaling through G-protein receptors, cell cycling, cell adhesion, proteins involved in egg-sperm binding interactions, spermine/spermidine biosynthesis, among others.  In the presence of excess antagonist, the gene expression is reversed, but only for some genes. We have identified unique gene expression fingerprints which are robust and clearly distinguish estrogenic from androgenic exposures. Using the validated microarrays we have tested effluents from water treatment plants and animal agricultural areas. Sites chosen were up- and down-stream from water treatment plants or sites receiving agricultural runoff. Expression profiles were unique at each of the locations, suggesting that they each vary in their composition and complexity.  Expression changes in key genes such as steroidogenic acute regulatory protein (StAR), estrogen receptors, among others illustrate the presence of endocrine disrupting chemicals.  Pathway analysis illustrates toxicity pathways that may be of importance for complex effluents.