PROTEIN-SYNTHESIS, GROWTH AND ENERGETICS IN LARVAL HERRING (CLUPEA-HARENGUS) AT DIFFERENT FEEDING REGIMES

Rates of growth, protein synthesis and oxygen consumption were measure d in herring larvae, Chupea harengus, in order to estimate the contrib ution that protein synthesis makes to oxygen consumption during rapid growth at 8 degrees C. Protein synthesis rates were determined in larv ae 9 to 17 d after hatching. Larvae were bathed in H-3 phenylalanine f or several hours and the free pool and protein-bound phenylalanine spe cific radioactivities were determined. Fractional rates of protein syn thesis increased 5 to 11 fold with feeding after a period of fasting. Efficiencies of retention of synthesized protein were approximately 50 % during rapid growth. Rapid growth in herring larvae thus appears to be characterized by moderate levels of protein turnover similar to tho se obtained for larger fish. Increases in growth rate occurred without changes in RNA concentration, i.e., the larvae increased the efficien cy of RNA rapidly. Oxygen consumption rates were not correlated with g rowth rates. Protein synthesis was estimated to account for 79% of the oxygen consumption, and energy costs of protein synthesis were high, i.e., about 98 mmole O-2 g(-1) protein synthesized.