PH19 Biomonitoring
Exhibit Hall
8:00 AM - Thursday
(PH218) Immunohistochemical evaluation of P450 expression and tissue distribution in striped bass experimentally exposed to beta-naphthoflavone.
Ostrach, D1, Groff, J1, Naydan, D1, Zinkl, J1, 1 Department of Pathology, Microbiology & Immunology, School of Veterinary Medicine, University of California Davis, Davis, CA, USA
ABSTRACT- Striped bass are an important sentinel species that reflect the general health of the San Francisco Estuary system. Objectives of this study were to evaluate the expression and tissue distribution of P450 enzymes in striped bass exposed to the P450 inducer beta-naphthoflavone (BNF) using three anti-P450 antibodies and to develop a routine immunohistochemical biomarker technique for evaluating P450 induction/contaminant exposure in striped bass and related species. Juvenile 14 month old striped bass were segregated into three equal treatment groups: intracoelomic injection with 50mcg of BNF suspended in 0.5 ml cod liver oil; injection with 0.5 ml cod liver oil; and no injection. Five days post-injection, fish were euthanized and tissues fixed in 10% formalin for 48 hours prior to paraffin embedding. P450 expression was evaluated by standard immunohistochemical methods using an HRP labeled biotin-free polymer linked antibody. Monoclonal antibody CYP1A-C10-7 resulted in positive staining of the vascular endothelium of all organs including lamellar capillaries of the gill, reticuloendothelium of the heart, hepatocytes, epithelium of the gall bladder and tubular epithelium and glomerular mesangium of the kidney. Monoclonal antibody CYP1A-FA-1 resulted in a similar distribution of staining, although the staining was generally less intense. Polyclonal antibody CYP1A-CP-226 resulted in poor staining or an absence of staining. Both control treatments showed no staining/P450 induction. The results of this study indicate that two monoclonal antibodies, but primarily CYP2-C10-7, can be used to determine exposure to P450 inducing toxicants in striped bass using standard immunohistochemical methods. The intense staining of the branchial lamellar vasculature also permits nonlethal collection of samples from wild fish or otherwise valuable fish for evaluation of exposure to environmental toxicants. This study provides a useful technique to determine and evaluate biomarkers of exposure to P450 inducible contaminants in striped bass and related species in the San Francisco Estuary system.
Key words: cytochrome P450, biomonitoring, immunohistochemical evaluation, striped bass