Over the last decades, growing concern regarding contamination by environmental pollutants of marine mammals has led to an increased effort to understand the hazardous effects they might inflict on wild population dynamics. A group of chemicals known as persistent organic pollutants pose a great threat to marine wildlife by accumulating in organisms at the bottom of the food chain and biomagnify as they are transferred up trophic levels, while inducing toxic effects on the organism’s immune system, nervous system, and endocrine system. Being the fiercest predator of the ocean, orcas or killer whales (Orcinus orca) are thought to be especially vulnerable to chemical pollution due to their feeding and behavioral habits. Orcas are not only efficient hunters, but highly intelligent and social animals. Mothers have been observed carrying their dead newborns for weeks, and increasing numbers of stillbirths and declining populations are thought to be a cause of toxic pollutants. The Fram Centre in Tromsø is putting effort into addressing these threats associated with contamination with their flagship program «Hazardous Substances» in collaboration with the Norwegian Polar Institute.
Primary cell cultures
But how do we study the impacts of toxic chemicals in free-living animals that spend most of their time below water, weigh up to 6 tons and make even the great white shark shake its fins?
Deriving primary cells from original skin tissue sampled from wild orcas provides a low-invasive, species-specific method to study their biochemical responses to environmental pollutants on cellular level. By investigating changes in gene expression and cell viability, cell cultures can function as a model system to estimate the impacts on individual and population levels. Establishing cell cultures with whale cells is, however, far from easy! This project aimed to optimize the culturing conditions to increase the growth rate and longevity of fibroblast cells from orcas – with success!
Established a robust cell culture
By modifying the composition of nutrients in the cell culture growth media we were able to establish a robust cell culture with orca fibroblasts. These cells were further exposed to persistent organic pollutants at different concentrations to study if the chemicals would induce harmful effects on the cells, of which – at high concentrations – they did. This demonstrates the need for establishing functional model systems, such as cell cultures, for investigating the toxic effects of pollution on orcas and other whales.
Thankful for excellent collaboration
The mentioned difficulties involved with establishing orca primary cell cultures were overcome with contributions from the DLN projects: 3Dlife at SINTEF and dCod1.0 at UiB. Thus, this study became a joint project in which we would like to thank the Centre for Digital Life Norway for supporting. I would also like to thank Heli Routti at the Norwegian Polar Institute and the Fram Centre for additional funding of the project. Further acknowledgments are pointed towards Anders Goksøyr (dCod.1.0, UiB), Hanne Haslene-Hox (3DLife, SINTEF) and Aman Chahal (NTNU/SINTEF) for their expertise, useful advice and help with experiments and Audun Rikardsen for sampling the skin biopsies. It should also be mentioned that Anders and Heli, together with Audun and other national and international partners last fall were successful in obtaining a 4-year and 12 MNOK grant from the Norwegian Research Council for developing this approach to study marine mammal toxicology further, in the project called Whales and polar bear in a petri dish: Decoding marine mammal toxicology using in vitro and in silico approaches – Marma-detox The project is also now a partner project in Digital Life Norway.