The long-term goal of this continuing research is to understand the role of cytochrome P450 enzymes in developmental toxicity of environmental chemicals. Such effects are among the most significant concerns in environmental toxicology, and yet a mechanistic understanding is largely absent. Understanding these effects of chemicals requires explicit knowledge of the CYP involved, given the central role that CYP have in the oxidative biotransformation of xenobiotics and many regulatory molecules. At present, there is no animal model for which there is a synoptic view of developmental expression of the full complement of CYP genes. The dual goals of this research are to establish a comprehensive picture of normal and chemically impacted CYP gene expression during development, and to determine the roles of selected CYP in developmental toxicity of prominent environmental chemicals. The major effort will involve the zebrafish (Danio rerio) vertebrate model system, and initially will focus on establishing the identities of CYP in zebrafish by profile Hidden Markov Models and Bayesian analysis. The expression of CYP during development and induction or suppression by developmental toxicants will be established by quantitative PCR and focused microarray technology. Developmental expression of nuclear receptors potentially involved in CYP induction also will be examined. Key CYP induced during development will be examined for contribution to toxicity by knocking down their expression in chemically treated embryos. In particular the roles of CYP1 family genes in toxicity will be established by gene knockdown and transient over-expression studies. This will include assessment of the potential contribution of CYP to oxidative stress, a possible common pathway to developmental toxicity. The environmental relevance of findings in zebrafish will be tested by examining selected homologous genes in another fish species, Fundulus heteroclitus, from a Superfund site highly contaminated by polychlorinated biphenyls. These studies will address further whether the adaptive responses evolved in these fish involve altered expression of CYP that are implicated in toxicity. The proposed studies will provide a uniquely comprehensive view of CYP in developing zebrafish, pointing to homologues that may be similarly involved in other vertebrate species. The studies will provide a lasting foundation essential to current and future assessment of the contribution of CYP to developmental toxicity of chemicals.
Principal Investigator: John J. Stegeman, Woods Hole Oceanographic Institution
Research Brief No. 124: DNA Damage Index: A New Tool For Assessing Toxic Effects of Contaminants
External Advisory Committee Presentation: A portion of the presentation that Postdoctoral Investigator Jed Goldstone gave at the BU SRP External Advisory Committee meeting on March 20, 2007.
