Mechanisms of acclimation to hypersalinity in two European sea bass lineages: a focus on the kidney function

European sea bass (Dicentrarchus labrax), a major aquaculture species, is distributed along the coasts of North-Eastern Atlantic Ocean, Mediterranean and Black Sea. D. labrax enter lagoons estuaries where salinity fluctuates sometimes reaches levels over 60‰, notably in lagoons. Keeping mind that are genetically subdivided an lineage, we compared fish from (A) West (M) populations regarding their capacity to tolerate hypersalinity with focus on kidney, key organ involved water reabsorption at high salinity. Fish were analyzed following two-week transfer seawater (SW, 36‰) either or hypersaline (HW, 55‰). Plasma osmolality was significantly increased MHW group other groups. sodium both lineages whereas plasma chloride showed opposite trend. In order estimate filtration kidney level, size renal glomeruli investigated decreased glomerulus perimeter area seawater. NKA highly expressed all tubules collecting ducts. There effect nka ?1a mRNA expression slightly lower transcript 55‰ 36‰. Relative protein amounts activity however higher exposed regardless origin. AQP1a immunolabeling differed between proximal subtypes only faint detected subapical parts cells lining The aqp 1a HW than SW paralogs (aqp 1b, 8b) did not change according conditions. This study efficient acclimation by increasing active ion transport decreasing filtering minimize loss through urine. Despite supposed more often encounter salinities habitat, blood indicates overall response seems improved lineage. However, traits differ genetic lineages, potentially as osmolalities MHW.