ANTIESTROGENIC EFFECTS OF BENZO[a]PYRENE REVEALED BY TRANSCRIPTOME ANALYSIS IN POLAR COD LIVER SLICE CULTURE

Background The arctic region can be susceptible to effects of pollution from sources such as northward expanding petroleum related activities and long-range transport of pollutants. The Arctic marine environment is characterized by a high seasonality in light and food availability and strongly influenced by global warming, which might influence effects of pollutants in organisms. Toxicological investigations and development of methodologies for future environmental monitoring of arctic fish are therefore warranted. The aim of this work is to demonstrate the use of ex vivo liver slice culture method to investigate transcriptome responses to Benzo[a]pyrene (BaP) in key arctic fish species during research cruises. Methods We used a precision-cut liver slice culture method developed for Atlantic cod (Gadus morhua) (Eide et al., 2014) and adapted the protocol for use in a wide range of species including small fish. On board R/V Kronprins Haakon of the Q3-2019 Nansen Legacy cruise, we developed liver slice culture from four key arctic and sub-arctic fish species, Atlantic cod, capelin (Mallotus villosus), polar cod (Boreogadus saida) and long rough dab (Hippoglossoides platessoides). The liver slice cultures were exposed to BaP, a ubiquitous environmental pollutant, also found in crude oil. Samples were harvested for transcriptomics (qPCR and RNA-seq) and other analyses. Results The precision-cut liver slice method (Eide et al., 2014) was adapted for flexible and higher throughput experiments with diverse fish species including small fish such as polar cod. Liver slicing and exposure studies were successfully performed on board R/V Kronprins Haakon. The first results show that BaP induced cyp1a gene expression in a dose-dependent manner in slice culture from all the fish sampled. Results from ongoing transcriptomics analysis will be presented. Conclusions We successfully performed liver slice culture and exposure experiments using diverse fish species, demonstrating that ex vivo experiments can be performed during field studies and sampling campaigns. This technique will be especially valuable to study species that are not available in the laboratory, or that are difficult to transport to the laboratory from the field.