title: Dietary Fatty Acid Metabolism is Affected More by Lipid Level than Source in Senegalese Sole Juveniles: Interactions for Optimal Dietary Formulation.
abstract: This study analyses the effects of dietary lipid level and source on lipid absorption and metabolism in Senegalese sole (Solea senegalensis). Juvenile fish were fed 4 experimental diets containing either 100 % fish oil (FO) or 25 % FO and 75 % vegetable oil (VO; rapeseed, linseed and soybean oils) at two lipid levels (~8 or ~18 %). Effects were assessed on fish performance, body proximate composition and lipid accumulation, activity of hepatic lipogenic and fatty acid oxidative enzymes and, finally, on the expression of genes related to lipid metabolism in liver and intestine, and to intestinal absorption, both pre- and postprandially. Increased dietary lipid level had no major effects on growth and feeding performance (FCR), although fish fed FO had marginally better growth. Nevertheless, diets induced significant changes in lipid accumulation and metabolism. Hepatic lipid deposits were higher in fish fed VO, associated to increased hepatic ATP citrate lyase activity and up-regulated carnitine palmitoyltransferase 1 (cpt1) mRNA levels post-prandially. However, lipid level had a larger effect on gene expression of metabolic (lipogenesis and β-oxidation) genes than lipid source, mostly at fasting. High dietary lipid level down-regulated fatty acid synthase expression in liver and intestine, and increased cpt1 mRNA in liver. Large lipid accumulations were observed in the enterocytes of fish fed high lipid diets. This was possibly a result of a poor capacity to adapt to high dietary lipid level, as most genes involved in intestinal absorption were not regulated in response to the diet.
authors.affiliation: IRTA, Centre de Sant Carles de la Ràpita (SCR), Ctra. Poble Nou km 5.5, 43540, Tarragona, Spain. kruno.bonacic@gmail.com.
authors.forename: Kruno
authors.initials: K
authors.lastname: Bonacic
authors.affiliation: IRTA, Centre de Sant Carles de la Ràpita (SCR), Ctra. Poble Nou km 5.5, 43540, Tarragona, Spain. alicia.estevez@irta.cat.
authors.forename: Alicia
authors.initials: A
authors.lastname: Estévez
authors.affiliation: IRTA, Centre de Sant Carles de la Ràpita (SCR), Ctra. Poble Nou km 5.5, 43540, Tarragona, Spain. olga.bellot@irta.cat.
authors.forename: Olga
authors.initials: O
authors.lastname: Bellot
authors.affiliation: CIMAR/CIIMAR, Centro Interdisciplinar de Investigação Marinha e Ambiental, Universidade do Porto, Rua dos Bragas, 289, 4050-123, Porto, Portugal. mconde@uvigo.es.|Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía, Universidade de Vigo, 36310, Vigo, Spain. mconde@uvigo.es.
authors.forename: Marta
authors.initials: M
authors.lastname: Conde-Sieira
authors.affiliation: IRTA, Centre de Sant Carles de la Ràpita (SCR), Ctra. Poble Nou km 5.5, 43540, Tarragona, Spain. enric.gisbert@irta.cat.
authors.forename: Enric
authors.initials: E
authors.lastname: Gisbert
authors.affiliation: IRTA, Centre de Sant Carles de la Ràpita (SCR), Ctra. Poble Nou km 5.5, 43540, Tarragona, Spain. sofia.morais@irta.cat.
authors.forename: Sofia
authors.initials: S
authors.lastname: Morais
mesh_terms: D000821:Animal Feed / Q000032:analysis* / Q000592:standards*; D000818:Animals; D019587:Dietary Supplements; D005227:Fatty Acids / Q000008:administration & dosage / Q000378:metabolism*; D005412:Flatfishes / Q000254:growth & development / Q000378:metabolism*; D005526:Food, Formulated; D050356:Lipid Metabolism
chemical_list: D005227:Fatty Acids
keywords: Beta-oxidation; Fatty acid binding proteins; Fish nutrition; Fish oil; Lipid absorption; Lipid trafficking; Lipogenesis; Molecular biology