Influence of different lighting and feeding regimes on the expression of the <i>fadsd5, fadsd6, elovl2, elovl5a</i> desaturase and elongase genes in the liver of juvenile Atlantic Salmon <i>Salmo salar</i> L. under aquaculture

The relative gene expression of enzymes – desaturases and elongases (fadsd5, fadsd6, elovl2, elovl5a, elovl4), which play a key role in the biosynthesis of long-chain polyunsaturated fatty acids, was studied in the liver of juvenile Atlantic salmon Salmo salar Linnaeus, 1758, reared under different lighting and feeding regimes in aquaculture conditions. The expression level of the fadsd5 desaturase gene was higher in Atlantic salmon smolts (0+), reared under round-the-clock lighting and feeding regime, compared to smolts from experimental group with natural photoperiod and daylight feeding. Changes in the level of gene expression (elovl2, elovl5a, fadsd5) in juvenile Salmo salar reflect adaptive processes at the molecular genetic level during the growth and development of fish and in response to changes in environmental conditions. The obtained results make it possible to assess the ability/requirement to the biosynthesis of PUFAs in juvenile salmon during its growth and development.