Correlates of Cytochrome P450 1A1 Expression in Bottlenose Dolphin (Tursiops truncatus) Integument Biopsies

Abstract

Integument biopsy is a nondestructive method for sampling free-ranging cetaceans, which allows for the determination of both contaminant concentrations and biomarker responses. Cytochrome P450 1A1 (CYP1A1) expression is induced by polycyclic aromatic hydrocarbons and planar halogenated aromatic hydrocarbons such as the non-ortho and mono-ortho polychlorinated biphenyls (PCBs). CYP1A induction has been used extensively as a biomarker of exposure to such compounds in vertebrates. We measured PCB concentrations and CYP1A1 expression in integument biopsies from bottlenose dolphins (Tursiops truncatus) resident in Sarasota Bay, FL. This population of dolphins has been the subject of long-term population and health assessment, affording the opportunity to evaluate the influence of age, sex, and reproductive status on CYP1A1 expression. CYP1A1 expression was seen in endothelial cells, vascular smooth muscle, and nerve cells in the dermis, similar to what has been observed in other cetacean species. Endothelial CYP1A1 expression varied along the length of the biopsy, which could be related to differences in the structure and functionality of the blubber in different parts of the integument. Neither age nor sex was related to CYP1A1 expression in these biopsies, and reproductive status did not relate to levels of CYP1A1 in females. Total PCB and toxic equivalent quotient concentrations in blubber were positively correlated with dermal endothelial CYP1A1 expression, although Sigmamono-ortho PCBs concentrations did not show this relationship. Contaminant concentrations appear to be stronger determinants of CYP1A1 expression in integument of these dolphins, than are age, sex, or reproductive status.