Environmental epigenetics: a mechanistic approach to describing persistent effects of PAHs in birds

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There is a growing awareness among scientists that exposure to environmental stress early in life can have lasting impacts on health later in life. Some of these persistent effects may be due to chemical modifications to epigenetic marks, such as DNA methylation, in developing embryos. This concept has been the focus of a tremendous amount of research in the biomedical field in recent years, and will have an equally important (and as of yet unrealized) impact on the ecological sciences. To date, only a handful of studies have applied epigenetic principles to the field of ecotoxicology. The potential for research in this area is exciting. Epigenetics may provide a new perspective on the impact that early-life exposures to environmental chemicals have on the health of populations of wildlife. With epigenetics, environmental conditions that an individual experiences as an embryo have the potential to influence responses to future exposures, health throughout life, and even the health of descendants. This idea has important implications for many areas of ecotoxicology, including risk assessment, biomonitoring, and the elucidation of mechanisms of action. The long-term goal of my research program is to investigate whether pre-natal exposure to environmental chemicals causes persistent and transgenerational effects in avian wildlife through epigenetic mechanisms. I will initially take a mechanistic approach to this question, focusing on a class of chemicals called polycyclic aromatic hydrocarbons (PAHs). These toxic chemicals are widespread in the environment and pose a risk to the health of wild populations of birds. The near-term goal of my research program is to determine the role of DNA methylation in mediating persistent responses to PAHs in birds. DNA methylation will be assessed in relation to the persistence of PAH-mediated changes in gene expression throughout the life of the individual, upon re-exposure, and across multiple generations. This work will initially be accomplished through developmental studies with chicken, and multi-generational studies with Japanese quail. The findings will be translated to an ecological setting by looking at similar endpoints in birds that have been exposed to PAHs under natural conditions. Overall, this work will provide high quality data that will facilitate risk assessment for PAHs in birds, and will establish a framework for studying the persistent and epigenetic effects of environmental contaminants.