title: Effects of genotype and dietary fish oil replacement with vegetable oil on the intestinal transcriptome and proteome of Atlantic salmon (Salmo salar).
abstract: BACKGROUND
  Expansion of aquaculture requires alternative feeds and breeding strategies to reduce dependency on fish oil (FO) and better utilization of dietary vegetable oil (VO). Despite the central role of intestine in maintaining body homeostasis and health, its molecular response to replacement of dietary FO by VO has been little investigated. This study employed transcriptomic and proteomic analyses to study effects of dietary VO in two family groups of Atlantic salmon selected for flesh lipid content, 'Lean' or 'Fat'.
  
  
  RESULTS
  Metabolism, particularly of lipid and energy, was the functional category most affected by diet. Important effects were also measured in ribosomal proteins and signalling. The long-chain polyunsaturated fatty acid (LC-PUFA) biosynthesis pathway, assessed by fatty acid composition and gene expression, was influenced by genotype. Intestinal tissue contents of docosahexaenoic acid were equivalent in Lean salmon fed either a FO or VO diet and expression of LC-PUFA biosynthesis genes was up-regulated in VO-fed fish in Fat salmon. Dietary VO increased lipogenesis in Lean fish, assessed by expression of FAS, while no effect was observed on β-oxidation although transcripts of the mitochondrial respiratory chain were down-regulated, suggesting less active energetic metabolism in fish fed VO. In contrast, dietary VO up-regulated genes and proteins involved in detoxification, antioxidant defence and apoptosis, which could be associated with higher levels of polycyclic aromatic hydrocarbons in this diet. Regarding genotype, the following pathways were identified as being differentially affected: proteasomal proteolysis, response to oxidative and cellular stress (xenobiotic and oxidant metabolism and heat shock proteins), apoptosis and structural proteins particularly associated with tissue contractile properties. Genotype effects were accentuated by dietary VO.
  
  
  CONCLUSIONS
  Intestinal metabolism was affected by diet and genotype. Lean fish may have higher responsiveness to low dietary n-3 LC-PUFA, up-regulating the biosynthetic pathway when fed dietary VO. As global aquaculture searches for alternative oils for feeds, this study alerts to the potential of VO introducing contaminants and demonstrates the detoxifying role of intestine. Finally, data indicate genotype-specific responses in the intestinal transcriptome and proteome to dietary VO, including possibly structural properties of the intestinal layer and defence against cellular stress, with Lean fish being more susceptible to diet-induced oxidative stress.
authors.affiliation: Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA Scotland, UK. sofia.morais@irta.cat
authors.forename: Sofia
authors.initials: S
authors.lastname: Morais
authors.forename: Tomé
authors.initials: T
authors.lastname: Silva
authors.forename: Odete
authors.initials: O
authors.lastname: Cordeiro
authors.forename: Pedro
authors.initials: P
authors.lastname: Rodrigues
authors.forename: Derrick R
authors.initials: DR
authors.lastname: Guy
authors.forename: James E
authors.initials: JE
authors.lastname: Bron
authors.forename: John B
authors.initials: JB
authors.lastname: Taggart
authors.forename: J Gordon
authors.initials: JG
authors.lastname: Bell
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Tocher
mesh_terms: D000818:Animals; D004042:Dietary Fats, Unsaturated / Q000494:pharmacology*; D005395:Fish Oils / Q000494:pharmacology*; D005838:Genotype; D007413:Intestinal Mucosa / Q000378:metabolism*; D010938:Plant Oils / Q000494:pharmacology*; D020543:Proteome / Q000187:drug effects*; D059467:Transcriptome / Q000187:drug effects* / Q000235:genetics; D014675:Vegetables / Q000378:metabolism*
chemical_list: D004042:Dietary Fats, Unsaturated; D005395:Fish Oils; D010938:Plant Oils; D020543:Proteome