Intracellular proteolysis in Atlantic salmon Salmo salar fingerlings (0+) from different biotopes in an Arctic river (Varzuga River, White Sea Basin)

ABSTRACTThe activity of intracellular proteolytic enzymes was studied in Atlantic salmon (Salmo salar L.) fingerlings (0+) after hatching from spawning nests and dispersal in the Varzuga River main stem and its Pyatka tributary (Kola Peninsula, White Sea Basin). The study focused on calcium-dependent cytosolic proteinases (µ- and m-calpains), lysosomal proteinases (cathepsins В and D) and collagenase, and determined the free/protein-bound hydroxyproline ratio, which portrays collagenolytic activity. Compared to fingerlings from the Varzuga main stem, the intracellular proteolytic enzyme activity of cysteine proteinase and collagenase was higher in fingerlings from the Pyatka tributary, where current velocities and food availability were higher. These results indicate that there is a higher rate of intracellular protein metabolism in the juveniles from this phenotypic group.