Friday 7th June 2019, Thomas Nelson Harvey defended his PhD, entitled “Towards a genome wide understanding of salmon lipid metabolism gene regulation across tissues and life stages.”
Atlantic salmon is an important source of omega-3 fatty acids in human diets, but in recent decades omega-3 levels in farmed salmon have decreased due to replacement of omega-3 rich fish oil in feeds with more sustainable plant oils. To overcome this challenge and keep aquaculture sustainable we need to either produce next generation feeds high in omega-3 or produce next generation fish capable of synthesizing high levels of omega-3 from vegetable oil. The latter strategy requires us to greatly expand our current understanding of lipid metabolism in salmon. This thesis uses next-generation omics approaches to understand lipid metabolism at the systems level, especially during the important life stage transition from freshwater to saltwater.
We observed that gene expression related to lipid metabolism generally decreased in the liver of smolts poised to enter saltwater, while gene expression related to absorption and transport of lipids increased in the gut of salmon after saltwater transfer. In addition, we developed an advanced cell culture system that maintains the three dimensional tissue architecture called precision cut liver slice culture (PCLS), and evaluated it as a system to study lipid metabolism in fish. We found that lipid metabolism was maintained in PCLS culture and closely resembled lipid metabolism in live fish. This thesis has advanced our understanding of lipid metabolism in salmon and provided and important tool for continued research, bringing us one step closer to a genome wide understanding of lipid metabolism in salmon