Major transporters responsible for desalinization (NaCl absorption) and low water permeability in the esophageal epithelia of SW eels. CA provides H+ and HCO3− to facilitate coordinated action of NHE and AE for NaCl absorption. Upregulation of the genes is shown in the inserted figures. The molecular identity of AE is still unknown because of the lack of upregulated genes in SW. AQP genes are downregulated in SW. For details, see 2.1. For abbreviation definitions, see the list. Modified from Takei et al.