Differential effects of brevetoxin and β-naphthoflavone on xenobiotic metabolizing enzymes in striped bass (Morone saxatilis)
The goal of this study was to determine the effects of brevetoxin, a polyether marine biotoxin, on xenobiotic metabolizing enzymes and to identify potential biomarkers of exposure. Brevetoxin (PbTx) is responsible for the death of millions of fish during algals blooms or 'red tides'. To this end, striped bass (Morone saxatilis) were exposed to either brevetoxin; a positive control, β-naphthoflavone (BNF); or a negative control the toxicant solvent, for five days. Hepatic microsomal and cytosolic fractions were prepared and assayed for ethoxyresorufin O-deethylase (EROD), UDP glucuronosyl transferase, microsomal epoxide hydrolase, and four isozymes of glutathione S-transferase. BNF induced a 30 fold increase in EROD activity; PbTx caused a 3 fold increase in EROD activity as well as 35 and 50 percent increase in the activity of two GST isozymes. Although PbTx is not an aromatic molecule, the present findings validates previous work with another species fish, redfish (Scaienops ocellatus), that PbTx induces Cytochrome P450IA activity. As is characteristic for molecules with Michael acceptor groups, PbTx also induced the GST, in particular those isozymes sensitive to ethacrynic acid and trans-phenylbutenone (pi and mu forms in mammals). Brevetoxin's affect on GST isozymes make them potentially useful biomarkers.
Washburn, BS; Vines, CA; Baden, DG; Hinton, DE; Walsh, PJ
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