Supplementary material- Lipid and gene expression data and statistics from Interaction between ω6 and ω3 fatty acids of different chain lengths regulates Atlantic salmon hepatic gene expression and muscle fatty acid profiles

Atlantic salmon smolts (approx. 20-month old) were fed experimental diets with different combinations of omega-6:omega-3 fatty acids (FAs) (high-ω6, high-ω3, or balanced) and EPA + DHA levels (0.3, 1.0 or 1.4%) for 12 weeks. Muscle FA (% total FA) reflected dietary C₁₈-polyunsaturated FA; however, muscle EPA % and content (mg g⁻¹) were not different in salmon-fed high-ω3 or balanced diets. Muscle DHA % was similar among treatments, while DHA content increased in fish-fed 1.4% EPA + DHA, compared with those fed 0.3–1.0% EPA + DHA combined with high-ω6 FA. Muscle 20 : 3ω6 (DGLA) content was highest in those fed high-ω6 with 0.3% EPA + DHA. Hepatic quantitative polymerase chain reaction showed that the monounsaturated FA synthesis-related gene, scdb, was upregulated in fish-fed 1.0% EPA + DHA with high-ω6 compared to those fed 0.3% EPA + DHA. In high-ω3 fed salmon, liver elovl2 transcript levels were higher with 0.3% EPA + DHA than with 1.0% EPA + DHA. In high-ω6 fed fish, elovl2 did not vary with EPA + DHA levels, but it was positively correlated with muscle ARA, 22 : 4ω3 and DGLA. These results suggest dietary 18 : 3ω3 elongation contributed to maintaining muscle EPA + DHA levels despite a two- to threefold change in dietary proportions, while 18 : 2ω6 with 0.3% EPA + DHA increased muscle DGLA more than ARA. Positive correlations between hepatic elovl2 and fabp10a with muscle ω6:ω3 and EPA + DHA + ARA, respectively, were confirmed by reanalysing data from a previous salmon trial with lower variations in dietary EPA + DHA and ω6:ω3 ratios.This article is part of the XX ‘The next horizons for lipids as ‘trophic biomarkers’: evidence and significance of consumer modification of dietary fatty acids’.