title: Dietary methionine level affects growth performance and hepatic gene expression of GH-IGF system and protein turnover regulators in rainbow trout (Oncorhynchus mykiss) fed plant protein-based diets.
abstract: The effects of dietary level of methionine were investigated in juvenile rainbow trout (Oncorhynchus mykiss) fed five plant-based diets containing increasing content of crystalline methionine (Met), in a six week growth trial. Changes in the hepatic expression of genes related to i) the somatotropic axis: including the growth hormone receptor I (GHR-I), insulin-like growth hormones I and II (IGF-I and IGF-II, respectively), and insulin-like growth hormone binding protein-1b (IGFBP-1b); and ii) protein turnover: including the target of rapamycin protein (TOR), proteasome 20 delta (Prot 20D), cathepsin L, calpains 1 and 2 (Capn 1 and Capn 2, respectively), and calpastatin long and short isoforms (CAST-L and CAST-S, respectively) were measured for each dietary treatment. The transcript levels of GHR-I and IGF-I increased linearly with the increase of dietary Met content (P<0.01), reflecting overall growth performances. The apparent capacity for hepatic protein degradation (derived from the gene expression of TOR, Prot 20D, Capn 1, Capn 2, CAST-L and CAST-S) decreased with increasing dietary Met level in a relatively linear manner. Our results suggest that Met availability affects, directly or indirectly, the expression of genes involved in the GH/IGF axis response and protein turnover, which are centrally involved in the regulation of growth.
authors.affiliation: BioMar A/S, Mylius Erichsensvej 35, DK-7330 Brande, Denmark; Technical University of Denmark, DTU Aqua, Section for Aquaculture, The North Sea Research Center, P.O. Box 101, DK-9850 Hirtshals, Denmark. Electronic address: mrol@aqua.dtu.dk.
authors.forename: Marine
authors.initials: M
authors.lastname: Rolland
authors.affiliation: Technical University of Denmark, DTU Aqua, Section for Aquaculture, The North Sea Research Center, P.O. Box 101, DK-9850 Hirtshals, Denmark.
authors.forename: Johanne
authors.initials: J
authors.lastname: Dalsgaard
authors.affiliation: BioMar A/S, Mylius Erichsensvej 35, DK-7330 Brande, Denmark.
authors.forename: Jørgen
authors.initials: J
authors.lastname: Holm
authors.affiliation: BioMar A/S, Mylius Erichsensvej 35, DK-7330 Brande, Denmark.
authors.forename: Pedro
authors.initials: P
authors.lastname: Gómez-Requeni
authors.affiliation: Technical University of Denmark, DTU Aqua, Section for Aquaculture, The North Sea Research Center, P.O. Box 101, DK-9850 Hirtshals, Denmark.
authors.forename: Peter V
authors.initials: PV
authors.lastname: Skov
mesh_terms: D000818:Animals; D004032:Diet; D015870:Gene Expression; D013006:Growth Hormone / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D007335:Insulin-Like Growth Factor II / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D008715:Methionine / Q000378:metabolism*; D017686:Oncorhynchus mykiss / Q000254:growth & development / Q000378:metabolism*; D014674:Plant Proteins, Dietary / Q000378:metabolism*; D014176:Protein Biosynthesis; D059748:Proteolysis
chemical_list: D014674:Plant Proteins, Dietary; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D013006:Growth Hormone; D008715:Methionine
keywords: Crystalline amino acid; Fish; Proteolytic pathways; Somatotropic axis; TOR