The expression pattern of calcium signaling-related genes during smoltification of Salmo salar in productive conditions

Variations in the mRNA expression of hepatic and muscle genes that are related to calcium signaling were analyzed by real-time qPCR in farmed Atlantic salmon (Salmo solar L. 1758) to determine changes in expression between parr and smolt stages. These organs were selected due to their close relationship with calcium signaling and metabolism (e.g., glycolysis, oxidative phosphorylation, muscle contraction). Differential expression between smolt and parr specimens and between organs was observed. Compared to parr specimens, smolts exhibited upregulated expression of the calcitonin receptor precursor, calcitonin receptor, calcitonin isoform, parathyroid hormone, and calmodulin in the liver. This pattern was inverse in muscle, with the exception of calmodulin, which was significantly upregulated in smolts compared to parr. Additionally, plasma calcium was decreased in the smolt condition. This study is the first to characterize the expression pattern of calcium signaling -related genes in the liver and muscle of parr and smolt S. salar. However, further functional studies are required to obtain a wider understanding about the physiological changes that accompany the productive conditions during smoltification.