Effects of Persistent Organic Pollutants and Their Mixtures on Biotransformation and Oxidative Stress in Zebrafish Embryo

Sammanfattning: Persistent organic pollutants (POPs) cause significant effects on organisms due to their resistance to environmental degradation and specific toxic responses. Although POPs toxicities were linked to oxidative stress in the previous studies, there are few POPs studies that link them with oxidative stress in zebrafish during development. Aim of this study is to investigate effect of selected POPs on expression of genes involved in oxidative stress response and biotransformation of xenobiotics in zebrafish. Zebrafish embryos in 96 hours’ post-fertilization were exposed to selected POPs and their mixture. To explore the developmental toxicity in zebrafish early stage, we exposed 3,3',4,4',5-pentachlorobiphenyl (PCB), perfluorooctanesulfonic acid (PFOS) and perfluorohexanoic acid (PFHxA) at concentrations of 7.5 μg/L, 50 μM, 50 μM until 96 hours’ post-fertilization. The effects were measured by gene expression quantification technique - quantitative real-time PCR (qPCR). Significant up-regulation in gene expression was detected in embryos treated with mixture of PCB with PFHxA and PCB with PFOS only for cytochrome P450(cyp1a). The results also showed the treatment with selected compound caused significant higher upregulation of cyp1a when we compare the treatment in the individual compounds to the mixture compounds. However, treatments did not cause changes in expression of genes involved in oxidative stress response (glutathione peroxidase 1a(gpx1a), tumor protein p53(tp53), aryl hydrocarbon receptor 2 (ahr2)). The result also suggests that exposure to selected POPs in mixtures or alone is not causing oxidative stress in early stage of embryonal development of zebrafish but activating biotransformation function of the organism. Effect of activation of biotransformation capacity by means of cyp1a upregulation is also higher when POPs are in mixtures over when used as individual substance.