In the present study immune response was the second highest category of genes affected by diet, after metabolism. Whether this is due to the potential anti inflammatory role of dietary FO or whether VO diets can have detrimental health effects is not clear as the fold changes were subtle, as expected in unchallenged animals. Nonetheless, the majority of genes related Inhibitors,Modulators,Libraries to processes of both innate and adaptive immunity were up regulated in fish fed VO. Only T cell and leukotriene B4 receptors, that are reduced after antigen and LTB4 exposure, respectively, and, in the case of LTB4 receptor, increased after EPA adminis tration, were down regulated in salmon fed VO.

Differences in gene expression between Lean and Fat genotypes Muscle adiposity is a trait of great importance in animal production, aquaculture included, and hence physiologi cal changes induced Inhibitors,Modulators,Libraries by genetic selection for this pheno type have been examined in various animals, including rainbow trout. In the present study the main differ ences between family groups were associated with signal transduction pathways, followed by metabolism. Only a small number of lipid metabolism genes varied in rela tion to muscle adiposity, as reported previously in rain bow trout, where the main differences were related to lipogenesis and mitochondrial oxidative metabolism. In our study glycerophospholipid metabolism may have been down regulated in the Lean family group through AGPAT and LPP2, two enzymes acting conse cutively on Cilengitide de novo TAG and phospholipid biosynthesis.

Quantification of AGPAT and LPP2 expression by RT qPCR confirmed this Inhibitors,Modulators,Libraries down regulation but fold changes were too subtle to be significant. AGPAT con verts lysophosphatidic acid into phosphatidic acid, while LPP2 then catalyzes the conversion of PA to dia cylglycerol. All these molecules can function as second messengers and are involved in the regulation of multi ple signalling pathways. Therefore, down regulation of this pathway in the Lean group has the potential to lower lipid biosynthesis, at least partly explaining the Inhibitors,Modulators,Libraries flesh lipid phenotype, but may also alter levels of lipid signalling molecules. On the other hand, differences in muscle adiposity might also be caused by higher hepatic de novo fatty acid synthesis in the Fat family group, as indicated by the expression of FAS.

In a previous study, no differences were found in the expression of ACO and CPT1, which suggested that the phenotypes could not be explained by differences in b oxidation. By contrast, in rainbow trout Fat and Lean families, b oxi dation and mitochondrial oxidative metabolism, but not lipogenesis, were affected by genetic selection, although another study using the same trout lines sug gested differences related to lipogenesis rather than fatty acid oxidation.