Abstract
Increased oil activity in the Arctic poses significant risks to marine ecosystems and key species like Atlantic cod (Gadus morhua). Crude oil and its water-accommodated fractions (WAFs) are complex mixtures, with toxicity often linked to polycyclic aromatic hydrocarbons (PAHs) acting through the aryl hydrocarbon receptor (AhR) pathway. This study used precision-cut liver slices (PCLS) from cod as an ex vivo model to investigate the hepatic and reproductive toxicity of specific WAF chemical fractions.
Five WAF fractions—saturates, monoaromatics, naphthalenes, PAHs, and resins—along with total WAF extract were tested. Liver slices from male and female cod were exposed for 48 hours, and gene expression of cytochrome P450 (cyp1a, detoxification marker) and vitellogenin (vtg, reproductive marker) was quantified using RT-qPCR.
Cyp1a expression increased significantly (20-fold in total WAF, 5-fold in resin), suggesting strong AhR activation, especially in the resin fraction. Chemical analysis identified abundant compounds such as 7-methyl-1-indanone and anthrone in the resin. Other fractions, including PAHs, showed limited effects, likely due to low concentrations or weak AhR agonists like phenanthrene.
These findings highlight key drivers of crude oil toxicity and demonstrate the value of ex vivo methods for dissecting mixture toxicity while reducing the need for live-animal testing.