title: 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.
abstract: The natural food for Atlantic salmon (Salmo salar) in freshwater has relatively lower levels of omega-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFA) than found in prey for post-smolt salmon in seawater. 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.
authors.affiliation: Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling FK9 4LA, UK. Electronic address: m.b.betancor@stir.ac.uk.
authors.forename: M B
authors.initials: MB
authors.lastname: Betancor
authors.affiliation: Institute of Marine Research, Matre 5984, Matredal, Norway; Norwegian University of Science and Technology, Department of Biology, 7491 Trondheim, Norway.
authors.forename: R E
authors.initials: RE
authors.lastname: Olsen
authors.affiliation: Institute of Marine Research, Matre 5984, Matredal, Norway.
authors.forename: D
authors.initials: D
authors.lastname: Solstorm
authors.affiliation: Institute of Marine Research, Matre 5984, Matredal, Norway.
authors.forename: O F
authors.initials: OF
authors.lastname: Skulstad
authors.affiliation: Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling FK9 4LA, UK.
authors.forename: D R
authors.initials: DR
authors.lastname: Tocher
mesh_terms: D000222:Adaptation, Physiological; D000821:Animal Feed; D000818:Animals; D005075:Biological Evolution; D019587:Dietary Supplements; D005229:Fatty Acids, Monounsaturated; D005231:Fatty Acids, Unsaturated / Q000096:biosynthesis*; D005395:Fish Oils / Q000008:administration & dosage* / Q000378:metabolism; D005398:Fisheries; D005618:Fresh Water; D020869:Gene Expression Profiling / Q000379:methods; D015971:Gene Expression Regulation, Enzymologic; D005838:Genotype; D050356:Lipid Metabolism / Q000235:genetics*; D008099:Liver / Q000201:enzymology / Q000378:metabolism*; D009752:Nutritional Status; D020411:Oligonucleotide Array Sequence Analysis; D010641:Phenotype; D010938:Plant Oils / Q000008:administration & dosage* / Q000378:metabolism; D025341:Principal Component Analysis; D000074262:Rapeseed Oil; D020317:Salmo salar / Q000235:genetics* / Q000378:metabolism*; D013997:Time Factors; D015430:Weight Gain
chemical_list: D005229:Fatty Acids, Monounsaturated; D005231:Fatty Acids, Unsaturated; D005395:Fish Oils; D010938:Plant Oils; D000074262:Rapeseed Oil
keywords: Atlantic salmon; Desaturases; Elongases; Land-locked; Omega−3 long chain polyunsaturated fatty acids