Establishment of killer whale cell cultures and their responses to pollutant exposure

Abstract

The cosmopolitan apex predator killer whale (Orcinus orca) is one of the species worldwide with the highest levels of persistent organic pollutants (POPs) in their tissues. The knowledge of how POPs may affect the species is limited, likely due to the ethical, legal, and practical challenges of researching toxicology on free-ranging marine mammals. The use of in vitro models has proved to be a functional tool which may provide information of cellular responses to POPs exposure in marine mammals. Skin biopsies of killer whales were sampled from the Northern Norwegian fjords during aggregation of killer whales for foraging on spring spawning herring. Primary fibroblast-like cells were established from the dermis of 11 out of 13 killer whales sampled. Cytotoxic and gene transcript analysis were conducted on the fibroblast-like cells exposed to ecologically relevant concentrations of POPs, reflecting the 10 most abundant POPs found in Norwegian killer whales. The pollutants were applied at different concentrations to explore dose-dependent responses. Significant downregulation of the target gene CYP1A was observed at medium and highest exposure concentration, as well as non-significant tendencies of another downregulated gene (CD36) and seven upregulated genes (ADIPOQ, CYP4A, ERA, GR, PPARA, PPARG and THRA) at the highest concentration of POPs exposure. This study provides a successful establishment of killer whale fibroblast-like cells, as well as proven gene alterations of the cells exposed to POPs.