TP17 Biomarkers
Tuesday, 15 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(OTT-1117-555893) Effects of benzo(a)pyrene exposed channel catfish on EROD activity, bile fluorescence, and bile constituents.

Otter, R¹, Klaine, S¹, ¹ Clemson Institute of Environmental Toxicology, Pendleton, South Carolina, USA

ABSTRACT- . Ethoxyresorufin-O-deethylase (EROD) and bile fluorescence (BF) are two biomarkers used to assess potential exposure to organic compounds, such as polyaromatic hydrocarbons (PAHs). Interpretation of these biomarkers used in field studies may be confounded if factors such as feeding, dosage, and time after exposure influence biomarker expression. These factors were incorporated into a 96 hour laboratory study that measured the effects of a single IP injection of benzo(a)pyrene (BaP) on EROD activity and BF intensity in channel catfish (Ictalurus punctatus). Fed and unfed fish were exposed to 20 mg/kg BaP, 5 mg/kg BaP, carrier control, or un-injected controls and were sampled at 24, 48, 72 and 96 hours post injection. Results showed that EROD activity and BF intensity significantly increased throughout the duration of the study in exposed fish compared to controls. There were no differences between carrier control and un-injected controls. Feeding and dose level did not affect EROD activity; however a significant increase in EROD activity was observed during the first 72 hours of the study, after which time activity declined. There was no effect of feeding on BF intensity throughout the study, however there was a significant increase in intensity with an increase in dose and time. The bile constituent biliverdin had a significant correlation to BaP exposure, while the bile constituent bilirubin was not detected in any sample. This study demonstrated that EROD was a good biomarker of general PAH exposure while BF was a more quantitative measure of actual bioavailable contaminant concentration.

Key words: EROD, bile fluorescence, benzo(a)pyrene, channel catfish