Transcriptome and proteome analysis of changes induced in trout liver by suppression of dietary fish oil

The expression of many genes is sensitive to dietary n-3 fatty acid levels in mammals. Fish diets are currently rich in fish oil that supplies both energy and highly unsaturated n-3 fatty acids, but fish oil is becoming scarce. Hepatic transcriptome and proteome were analyzed to investigate global metabolic changes induced by the absence of fish oil in trout diets. Rainbow trout were fed fishmeal based diets with fish oil supplementation (FO+: 230 g lipids/kg dry matter) or without (FO−: 100 g lipids/kg dry matter), from the first feeding for 6 months. Liver were sampled 24h after the last meal. As expected, while their feed efficiency was reduced, fish fed FO− exhibited lower growth rate and body fat deposition. 23 genes were down- and 99 up-regulated with FO−. About 900 hepatic proteins were analyzed for expression pattern. 105 were found to be differentially expressed between diets and 13 proteins were identified in database after MALDI-TOF analysis. We found that fish oil suppression increased fatty acid transport, de novo lipid synthesis and fatty acid desaturation, while decreasing fatty acid catabolism. Genes and proteins involved in glycolysis, amino acid catabolism and energy production were up regulated, showing a shift in nutrient utilization for energy production. This work is supported by the French Aquitaine region and AGENOP contract.