Both seawater acclimation and environmental ammonia exposure lead to increases in mRNA expression and protein abundance of Na+:K+:2Cl− cotransporter in the gills of the climbing perch, Anabas testudineus

摘要: The freshwater climbing perch, Anabas testudineus, is an obligatory air-breathing teleost which can acclimate to seawater, survive long period of emersion, and actively excrete ammonia against high concentrations environmental ammonia. This study aimed clone sequence the Na+:K+:2Cl− cotransporter (nkcc) from gills A. determine effects seawater acclimation or exposure 100 mmol l−1 NH4Cl in on its branchial mRNA expression. complete coding cDNA nkcc testudineus consisted 3,495 bp, was translated into a protein with 1,165 amino acid residues estimated molecular mass 127.4 kDa. A phylogenetic analysis revealed that Nkcc closer fish Nkcc1a than Nkcc1b Nkcc2. After progressive increase salinity, there were significant increases expression abundance nkcc1a acclimated as compared control. Hence, it be concluded similar marine teleosts, Cl− excretion through basolateral Nkcc1 mitochondrion-rich cells (MRCs) essential testudineus. Exposure for 1 6 days also resulted gills, indicating functional role active excretion. It probable NH4+ enter MRCs before being transported across apical membrane. Since operation would lead intracellular Na+ concentration, deduced upregulation Na+/K+-ATPase (Nka) activity necessary compensate increased influx during imply main function Nka maintain K+ homeostasis instead transporting directly proposed previously. In conclusion, salt secretion could involve transport mechanisms