A first attempt to estimate protein turnover using a simulation model for amino acid metabolism in yolk-sac larvae of Clarias gariepinus (Burchell) and Hippoglossus hippoglossus (L.)

Larval growth can be improved through the reduction of energy expenditure, which has been correlated with the rate of protein synthesis and hence to amino acid metabolism. Understanding the dynamics and regulation of the amino acid metab­olism may contribute to the formulation of larval diets. A model was developed to simulate amino acid fluxes in yolk-sac larvae. The model considers the flux of amino acids through three pools: amino acids in the yolk; free amino acids in the body; and protein-bound amino acids in the body. Each pool is subdivided into sub-pools of the individual amino acids. Yolk amino acids are absorbed into the body free pool, a process which is proportional to yolk volume and to the pool of amino acids in the yolk. The body-free pool is used for catabolism and protein synthesis, with the respective rates increasing with both body size and amino acid concentration. Amino acids are released into the free pool as a result of protein breakdown. Protein turnover was estimated during development of yolk-sac larvae. Results suggest that efficiency of protein retention is lower than 50% in yolk-sac larvae. Minimal values for fractional rates of protein synthesis were estimated to be 300% d -1 (Clarias gariepinus) and 30% d -1 (Hippoglossus hippoglossus). Different amino acids provided similar estimates for protein turnover. Article from Marine Science Symposia Vol. 201 - "Mass rearing of juvenile fish". Symposium held in Bergen, 21-23 June 1993. To access the remaining articles please click on the keyword "MSS Vol. 201".