Validation of a cell culture bioassay for detection of petroleum exposure in mink (Mustela vison) as a model for detection in sea otters (Enhydra lutris).
OBJECTIVE
To validate a luciferase bioassay, which is based on a recombinant mouse hepatoma cell line, for the detection of exposure to petroleum in mustelid species.


METHODS
122 American mink (Mustela vison) and 15 sea otters (Enhydra lutris).


METHODS
Mink were exposed to Bunker C fuel oil or Alaska North Slope crude oil externally as a single exposure or internally via low dose concentrations in their ration for 6 months. Serum samples were analyzed for cytochrome P450 1A1 induction by quantification of luciferase activity in the bioassay. Mink liver specimens were also evaluated for cytochrome P450 1A1 induction by quantification of ethoxyresorufin-o-deethylase activity. Serum collected from exposed and unexposed sea otters was also analyzed using the luciferase bioassay.


RESULTS
Serum samples from mink externally exposed to petroleum had significantly increased luciferase activities at 1 week after exposure. Serum samples taken at later time points or from mink exposed to either product in the ration did not cause significant luciferase induction. Samples from otters exposed to petroleum had significantly higher luciferase induction as compared with samples from otters not exposed to petroleum at 2 and 8 years after the spill. Cytochrome P450 1A1 activity in liver specimens collected from mink that were internally exposed through diet was significantly increased at the conclusion of our study.


CONCLUSIONS
The luciferase bioassay is a sensitive and specific method for determining recent exposure to petroleum in mink. The lack of luciferase activity in serum samples collected from mink greater than 1 week after experimental exposure was likely attributable to lower overall petroleum exposure in our trial, compared with natural exposures.
Wildlife Health Center, Department of Pathology, School of Veterinary Medicine, University of California, Davis 95616, USA.
Michael H
MH
Ziccardi
Jonna A K
JA
Mazet
Ian A
IA
Gardner
Walter M
WM
Boyce
Michael S
MS
Denison
D000818:Animals; D001681:Biological Assay / Q000379:methods / Q000662:veterinary*; D002478:Cells, Cultured; D019363:Cytochrome P-450 CYP1A1 / Q000097:blood / Q000378:metabolism*; D004781:Environmental Exposure / Q000009:adverse effects*; D004784:Environmental Monitoring / Q000379:methods; D005260:Female; D008099:Liver / Q000201:enzymology; D008156:Luciferases / Q000097:blood; D051379:Mice; D008907:Mink / Q000378:metabolism*; D010041:Otters / Q000378:metabolism*; D010578:Petroleum / Q000009:adverse effects* / Q000032:analysis; D011897:Random Allocation
D010578:Petroleum; D008156:Luciferases; D019363:Cytochrome P-450 CYP1A1