Assessment of a land-locked Atlantic salmon (Salmo salar L.) population as a potential genetic resource with a focus on long-chain polyunsaturated fatty acid biosynthesis

• Published in: Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids
• Main Authors: Betancor, Monica, Olsen, Rolf E, Solstorm, David, Skulstad, Ole Fredrik, Tocher, Douglas R
• Other Authors: Institute of Aquaculture, Matre Aquaculture Research Station, Norwegian Institute of Marine Research, orcid:0000-0003-1626-7458, orcid:0000-0002-8603-9410
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2016
• Subjects: omega-3 long chain polyunsaturated fatty acids; Atlantic salmon; land-locked; desaturases; elongases; Salmo salar
• Online Access: http://hdl.handle.net/1893/23417; https://doi.org/10.1016/j.bbalip.2015.12.015; http://dspace.stir.ac.uk/bitstream/1893/23417/1/Betancor%20et%20al%202016%20BBA.pdf

The natural food for Atlantic salmon (Salmo salar) in freshwater has relatively low levels of omega-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFA), whereas post-smolt salmon in seawater have a diet naturally rich in n-3 LC-PUFA. Land-locked salmon such as the Gullspång population feed exclusively on freshwater type lipids during its entire life cycle, a successful adaptation derived from divergent evolution. Studying land-locked populations may provide insights into the molecular and genetic control mechanisms that determine and regulate n-3 LC-PUFA biosynthesis and retention in Atlantic salmon. A two factorial study was performed comparing land-locked and farmed salmon parr fed diets formulated with fish or rapeseed oil for 8 weeks. The land-locked parr had higher capacity to synthesise n-3 LC-PUFA as indicated by higher expression and activity of desaturase and elongase enzymes. The data suggested that the land-locked salmon had reduced sensitivity to dietary fatty acid composition and that dietary docosahexaenoic acid (DHA) did not appear to suppress expression of LC-PUFA biosynthetic genes or activity of the biosynthesis pathway, probably an evolutionary adaptation to a natural diet lower in DHA. Increased biosynthetic activity did not translate to enhanced n-3 LC-PUFA contents in the flesh and diet was the only factor affecting this parameter. Additionally, high lipogenic and glycolytic potentials were found in land-locked salmon, together with decreased lipolysis which in turn could indicate increased use of carbohydrates as an energy source and a sparing of lipid.