title: Low temperature acclimation decreases rates of protein synthesis in rainbow trout (Oncorhynchus mykiss) heart.
abstract: Protein synthesis was assessed in rainbow trout (Oncorhynchus mykiss) hearts perfused with medium containing (3)H phenylalanine. Isolated hearts from fish acclimated to 5° and 15°C were used as the model system, and were perfused at variable test temperatures and pH. Protein synthesis expressed as nmol PHE mg protein(-1) h(-1) was two fold higher in hearts from fish acclimated to 15°C and tested at 15°C and extracellular pH 7.6 than in hearts from fish acclimated to 5°C and tested at 5°C and extracellular pH 8.0. The prime determinant of the decreased rate of protein synthesis was thermal history. Fish acclimated to 5°C had lower levels of RNA mg protein(-1) than fish held at 15°C. There was a direct linear relationship between the rate of protein synthesis in nmol PHE mg protein(-1) h(-1) and RNA content. RNA activity (nmol PHE μg RNA(-1) h(-1) remained constant regardless of thermal history or perfusion condition. Elevated pH resulted in only a marginal decrease in protein synthesis. Test temperature had no effect on in vitro rates of protein synthesis.
authors.affiliation: Department of Biology, Mount Allison University, Sackville, N.B., Canada, EOA 3CO.
authors.forename: D H
authors.initials: DH
authors.lastname: Sephton
authors.forename: W R
authors.initials: WR
authors.lastname: Driedzic