Nephrocalcinosis and Physiological Perturbations in Atlantic salmon (Salmo salar L.).

Abstract

This master's thesis extends the PREVENTIVE project, funded by CtrlAqua (Center for Research-Based Innovation in Closed-Containment Aquaculture), by focusing on the pathology and physiological disturbances associated with nephrocalcinosis. It discusses various methods for scoring the severity of nephrocalcinosis and highlights the extensive pathological and physiological changes observed in affected Atlantic salmon.

The study examines plasma concentrations of chloride, sodium, calcium, magnesium, and inorganic phosphate. Results show low chloride and sodium levels, while calcium and magnesium levels are elevated, with magnesium demonstrating a significant increasing trend with the severity of nephrocalcinosis. Plasma glucose levels also varied, increasing from mild to moderate cases, and decreasing in severely affected salmon.

Additionally, the expression of the Na+/K+ pump and its α-subunits (NKAα1b1, -b2, -c1, -c2) in the kidney decreased with increasing nephrocalcinosis severity. Sulfate transporter genes (SLC26a1a, -1b, SLC26a6a1) showed similar trends to the Na+/K+ pump. However, magnesium transporter genes (SLC41a1-1, SLC41a1-2, CNNM2b1b2, CNNM3-1, TRPM6-2 and TRPM7-2) exhibited varied responses. Specifically, SCL41a1-2, CNNM2b1b2, and TRPM7-2 were unresponsive to increasing severity, CNNM3-1 decreased, TRPM6-2 increased, and SLC41a1-1 was upregulated from mild to moderate cases but downregulated in severe cases. This variability suggests diverse roles and regulatory mechanisms for magnesium transporters in response to nephrocalcinosis.