Characterization of Na, K-ATPase genes in Atlantic salmon (Salmo salar) and comparative genomic organization with rainbow trout (Oncorhynchus mykiss)

A combination of molecular and in silico approaches was employed to assemble a survey of Na, K-ATPase genes contained in the ancestrally tetraploid genome of the Atlantic salmon (Salmo salar). Molecular characterization of genomic clones coding for the α subunit revealed two single genes (α1a and α2) and two pairs of presumably homeologous genes (α1b/i-ii and α1c/i-ii). Each of the six genes showed high sequence similarity to isoforms previously isolated from rainbow trout and extensive structural differences relative to putative orthologs in the human genome. In silico analysis of expressed sequence tag (EST) collections indicated that at least five α (α1a, α1b, α1c, α2, and α3) and four β (β1a, β1b, β2, and β3b) subunit isoforms are expressed in Atlantic salmon. Meiotic linkage analysis further showed that Na, K-ATPase genes are dispersed throughout the salmon genome, with the exception of two multigene clusters on linkage groups AS-22 and AS-28. Duplicate gene copies for the isoform α1b were assigned to linkage groups with multiple homeologous anchors (AS-22 and AS-23), while β2 duplicates suggested a new homeologous affinity between AS-05 and AS-28. In addition, the comparison of linkage arrangements with rainbow trout also showed that the genomic organization of Na, K-ATPase genes is consistent with the evolutionary conservation of syntenic chromosome regions between these species.