title: Dietary protein levels affect growth and protein metabolism in trunk muscle of cod, Gadus morhua.
abstract: Cod (Gadus morhua) of 50 g body weight were kept at 14 degrees C. The fish were fed ad libitum during 80 days a diet containing protein levels which in terms of total energy corresponded to 25%, 45% or 65%. Growth increased in accordance with protein-energy levels. The protein content per gram of wet weight of white trunk muscle was unchanged, as was the myofibrillar protein myosin heavy chain determined by the antigen-antibody reaction of the enzyme-linked immunosorbent assay. The amount of messenger ribonucleic acid (mRNA) coding for myosin heavy chain was lower at 25% than at 45% or 65% protein-energy intake, the differences being significant per gram of wet weight of muscle. Acid proteinase activity was highest at the lowest protein-energy intake. Glycogen content in muscle increased with the protein-energy levels. It is concluded that the metabolic response of white trunk muscle to graded protein-energy intake included a change in the capacity to synthesize myosin heavy chain as judged by its mRNA content. The protein content per gram of wet weight was unaffected by dietary protein-energy levels of 25%, 45% and 65%, but protein accretion and thus growth of the animals increased with the protein intake. Dietary protein-energy restriction caused a rise in acid proteinase activity and a decrease in content of mRNA for myosin heavy chain, resulting in a diminished growth rate at an unchanged protein content per gram of wet weight of muscle.
authors.affiliation: Wenner-Gren Institute, University of Stockholm, Sweden.
authors.forename: A
authors.initials: A
authors.lastname: von der Decken
authors.forename: E
authors.initials: E
authors.lastname: Lied
mesh_terms: D000818:Animals; D004247:DNA / Q000378:metabolism; D004044:Dietary Proteins / Q000008:administration & dosage; D010450:Endopeptidases / Q000378:metabolism; D005399:Fishes / Q000254:growth & development / Q000378:metabolism*; D006003:Glycogen / Q000378:metabolism; D009124:Muscle Proteins / Q000378:metabolism*; D009132:Muscles / Q000378:metabolism; D009218:Myosins / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism
chemical_list: D004044:Dietary Proteins; D009124:Muscle Proteins; D012333:RNA, Messenger; D006003:Glycogen; D004247:DNA; D010450:Endopeptidases; D009218:Myosins