| Over the last decade, researchers have begun using genomic, proteomic and hormone biomarkers to better understand the physiologic state of aquatic organisms in response to a variety of chemicals in the environment. To date, most environmental toxicology studies employ molecular biomarkers to assess the impact of an individual chemical at a high level of exposure. While these studies have great value in identifying potential biomarkers, these types of studies present three key limitations: 1) While effective and validated in a lab setting, these studies are less effective when used in a field setting; 2) Little is known about how other factors, such as gender and diet affect the metabolism of environmental contaminants in fish; and 3) There is little research that assesses the impacts of chemical mixtures at sub-lethal levels (more common in the environment) over long periods of time, leaving largely unknown the mechanism by which these chemicals can impact an organism at low levels. The goal of this work was to assess how biomarkers perform under environmentally realistic conditions. We demonstrate that oxidative stress biomarkers are good predictors of egg production aquatic habitats with varying physico-chemical conditions; that gender and diet can influence the expression of genes involved in xenobiotic metabolism; and environmentally relevant exposures of chemical mixtures potentially affect an organism through different pathways as compared to single chemical exposures. The results from these studies highlight the importance of developing molecular biomarkers that are robust across multiple environmental conditions and populations for use in risk assessment. |
