Sammendrag
Crude oil is a complex mixture of several hundreds or thousands of compounds that are dominated by aliphatic and aromatic hydrocarbons (50-90 % of crude oils). Most studies concerning environmental impacts of oil hydrocarbons to North Sea environments have focused on well characterized compound groups like volatile monoaromatics, naphthalenes, and PAH compounds. The crude oil water-soluble fraction (WSF) contains a large group of poorly characterized mixtures of hydrocarbons. Often, these are referred to as unresolved complex mixtures (UCM) that have recently been shown to cause a number of toxic effects to marine organisms. Herein, we show that exposure of zebrafish to crude oil UCM rich WSFs from the Troll reservoir (Norway) produced toxicological gene and enzyme biomarker effects measured as modulation of brain and whole-body homogenate steroidogenesis and biotransformation enzyme system. In the brain (i.e. head), WSF produced an apparent concentration-specific decrease in the StAR protein, P450scc, aromatase (a and b), ER (a and b), AhR2 and increase in 3b-HSD, AhR1 and CYP1A gene expression patterns. Analysis of whole-body homogenate for testosterone (T), estradiol (E2) and EROD, BROD, MROD and PROD levels were also performed. Our data showed a unique WSFs effect on T and E2 that decreased and increased, respectively, with increasing concentration of the WSFs. For the biotransformation enzymes, WSF produced a concentration-specific increase of EROD, MROD, BROD and PROD (putatively activity for different CYP isoforms) activity levels. In general, the data presented in this study showed multiple biological effects of WSFs targeting the steroidogenic and biotransformation pathways. Thus these data on the regulation and expression of genes and proteins that control physiological responses will help in defining the link between exposure effects on health and reproductive endpoints with individual consequences of exposure to PWD from the offshore oil industry.
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