Calcium-dependent proteases (calpains) in fingerlings (0+) of Atlantic salmon (Salmo salar L.) from two biotopes of Varzuga river

The stage of post-embryonic development in Atlantic salmon, occurring in the main stream of the Varzuga River (one of the major rivers in the basin of the White Sea), includes periods of resettlement and feeding of young fish on different biotopes. Some juveniles of the same generation aggregate close to the spawning nests - in the main channel of the Varzuga River, the Arenga threshold. The other part of young fish moves out from the nests and settles in small tributaries with favorable food supply, particularly in the inflow of the Arenga River - in the mouth of the river. Subsequent maturation and development of the young fish depend on a complex of genetic, biochemical and environmental factors. In the present study, the activity of calcium-dependent proteases of cytosol (calpain), which contributed to the significant intracellular proteolysis and regulation of physiological and biochemical processes in the cell, were investigated. The studied Atlantic salmon fingerlings after hatching from spawning nests moved into the mainstream and tributaries (the Arenga River) of the Varzuga River. The differences in studied enzymes activities in the fingerlings of Atlantic salmon from different microbiotopes of the Varzuga River (the White Sea basin) distinguished by hydrological, feeding, and ecological conditions were found. The calpain activities were compared with certain lipid parameters obtained in previous studies for the young fish of the Atlantic salmon distributed to the same biotopes of the river.