Novel biomarkers of dioxin effects

Mark E. Hahn

The overall objective of research in our laboratory is to understand the biochemical and molecular mechanisms that underlie the interactions of marine animals with their chemical environment. Our general approach is to examine these mechanisms from a comparative/phylogenetic perspective, in order to understand the fundamental features of chemical action. We are especially interested in the halogenated aromatic hydrocarbons (HAH), a group of chemicals that includes the chlorinated dioxins, polychlorinated biphenyls, halogenated diphenyl ethers, as well as a variety of marine natural products.

The highest concentrations of many of these chemicals are often found in urban harbors and other coastal areas; however, these compounds have been documented in remote locations as well, including open ocean, polar regions, and in the deep sea. These chemicals pose a well-documented risk to marine organisms and ecosystems. To more accurately measure the impact of these compounds in marine environments, we need to identify responses that can serve as sensitive indicators, or biomarkers, of adverse effects in marine animals.

Existing biomarkers, such as cytochrome P4501A (CYP1A) have not been closely linked to toxic endpoints, despite extensive research. Though useful as markers of exposure to contaminants, CYP1A may be less useful as an indicator of toxic effects. Our laboratory is working on identifying genes whose expression is induced or repressed by TCDD in killifish and that are directly related to changes in cell growth and proliferation. In addition, we are cloning and sequencing selected candidate genes potentially linked to toxicity, and testing the value of these genes as biomarkers by measuring their expression in animals exposed to halogenated hydrocarbons in the laboratory and in the marine environment.

This research is supported by WHOI Sea Grant.

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