EROD activity, expressed as both nmol/min/mg microsomal protein and nmol/min/nmol 

 of total P-450, is catalyzed by the P-450 system. About an 11-fold difference in mean EROD 

 activity was observed between BNF-treated and untreated fish, indicating a very high 

 potential for induction in P. stellatus (Table 29). Mean EROD activity, as nmol/min/mg 

 protein, was highest among fish from the OK site; about 6 times higher than in RR fish and 

 4 times higher than in SP fish. When expressed as nmol/min/nmol P-450, the activity in 

 BNF-treated fish was roughly fivefold higher than in untreated fish and the mean activity 

 in OK fish was again highest, exceeding that in the RR fish by 4.5 times. 



Content of the apparent homologue of the BNF-, PCB-, PAH-inducible teleost 

 cytochrome P-450E was determined and expressed as picomoles (pM)/mg microsomal protein 

 (Table 29). Mean P-450E content in BNF-treated fish exceeded that in untreated fish by over 

 15 fold. Mean P-450E content was highest in field collections in the fish from OK and BK 

 and lowest in fish from SP and RR. The mean value for the OK site exceeded that for SP 

 and the RR site by nearly 14 times. 



Table 29. Summary of results for total hepatic cytochrome P-450 content, EROD activity, 

 and "P-450E" content in field-sampled Platichthys stellatus collected in November- 

 December (means ± SD) 



a nM/mg protein 



D nM/min/mg protein 



c nM/min/nmol total P-450 



" pM/mg protein 



e fish injected with p-naphthoflavone 



All of these analyses indicate that the fish at the OK site were exposed to the highest 

 concentrations of P-450 enzyme inducers, including hydrocarbons such as PCBs and PAHs. The 

 BK site ranked second by these measures, followed by VA, SP, and the RR sites. However, 

 the values for BNF-treated fish exceeded those for the OK fish by 1.7 to 8.5 times for the 

 measured end-points, indicating the fish from OK were not exposed to exceptionally high or 

 maximally effective contaminant concentrations. 



65 



