The Superfund Research Program (SRP) presents "Assessing Ecological Risk of Endocrine Disrupting Chemicals: State-of-the-Science Approaches" featuring Dr. Gerald (Gary) Ankley (USEPA/ORD Mid-Continent Ecology Division) and Dr. Nancy Denslow (University of Florida). Dr. Ankley will focus on the problems EDC present for ecological risk assessment and will talk about the types of assessment tools needed and their potential applications. Dr. Denslow's presentation will show how molecular biomarkers and "omics" technologies may be useful in risk assessment, focusing on a Lake Apopka study of largemouth bass, fathead minnows, and organochlorine pesticides. This is the first session of the RiskeLearning Spring/Summer 2010 series "Ecological Risk: New Tools and Approaches." For more information on the series visit: http://www.niehs.nih.gov/research/supported/srp/events/riskelearning/.
Molecular Biomarkers and Omics Technologies in Risk Assessment for Endocrine Disrupting Chemicals, Nancy Denslow, University of Florida
Microarray technology is a relatively novel tool in ecotoxicology, but the ability to use a global analysis to understand the adverse effects on fish of exposure to mixtures of anthropogenic chemicals has focused interest in this area. Microarrays can be used as tools for risk characterization for ecological risk assessment. To illustrate the approach, two field studies are described. The first study focuses on organochlorine pesticide contamination of Lake Apopka and the North Shore muck farms. Largemouth bass (LMB) inhabiting these sites exhibit poor reproduction. To ascertain how OCPs impact the hypothalamic-pituitary-gonadal axis, LMB were exposed either in mesocosm sites built directly in the muck farms or subchronically through the diet to p,pÕ-DDE and dieldrin at concentrations approximating exposures in contaminated sites. Effects of treatments on gene expression were analyzed using a novel 15,000 gene array specific for LMB constructed by transcriptome pyrosequencing Pathway analysis of regulated genes identified effects of treatment on steroidogenesis, metabolism, gonad development, sex differentiation, cell growth and innate immune response, among others. In the second study, we used fathead minnows in laboratory experiments to obtain specific gene expression profiles for estrogen- and androgen-receptor dependent pathways. We have identified unique gene expression fingerprints which are robust and clearly distinguish estrogenic from androgenic exposures. Using the validated microarrays we have tested the effects from exposure of fathead minnows to effluents from water treatment plants and animal agricultural areas in Minnesota. 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 adverse outcome pathways that may be of importance for assessing the risk of exposure to complex effluents.
Assessing EDCs in the Field: New Approaches to Old Challenges, Gerald Ankley, U.S. EPA, Office of Research and Development, Mid-Continent Ecology Division
Assessing the occurrence and effects of EDCs in the environment can be challenging from a number of perspectives. For example, conventional analytical approaches and/or toxicity tests may not be appropriate to detecting very potent chemicals that impact specific pathways, and often are present as components of complex mixtures. Meeting these challenges requires short-term in vitro and in vivo assays suitable for complex mixtures, analytical/fractionation approaches to identify specific chemicals causing biological effects, diagnostic endpoints (biomarkers) indicative of endocrine mechanism of action, and approaches to link diagnostic responses to alterations in individuals and populations. This talk provide an overview of EDCs and problems they present in terms of ecological risk assessment, and present examples of the types assessment tools needed and their potential applications.