Distinct freshwater and seawater isoforms of Na + /K + -ATPase in gill chloride cells of Atlantic salmon
Gill Na + /K +-ATPase (NKA) in teleost fishes is involved in ion regulation in both freshwater and seawater. We have developed and validated rabbit polyclonal antibodies specific to the NKA �1a and �1b protein isoforms of Atlantic salmon (Salmo salar Linnaeus), and used western blots and immunohisto...
| Main Authors: | , , |
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| Other Authors: | |
| Format: | Text |
| Language: | English |
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2009
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.419.921 http://www.bio.umass.edu/biology/mccormick/pdf/JEB 2009 fw sw NKA.pdf |
| Summary: | Gill Na + /K +-ATPase (NKA) in teleost fishes is involved in ion regulation in both freshwater and seawater. We have developed and validated rabbit polyclonal antibodies specific to the NKA �1a and �1b protein isoforms of Atlantic salmon (Salmo salar Linnaeus), and used western blots and immunohistochemistry to characterize their size, abundance and localization. The relative molecular mass of NKA �1a is slightly less than that for NKA �1b. The abundance of gill NKA �1a was high in freshwater and became nearly undetectable after seawater acclimation. NKA �1b was present in small amounts in freshwater and increased 13fold after seawater acclimation. Both NKA isoforms were detected only in chloride cells. NKA �1a was located in both filamental and lamellar chloride cells in freshwater, whereas in seawater it was present only as a faint background in filamental chloride cells. In freshwater, NKA �1b was found in a small number of filamental chloride cells, and after seawater acclimation it was found in all chloride cells on the filament and lamellae. Double simultaneous immunofluorescence indicated that NKA �1a and �1b are located in different chloride cells in freshwater. In many chloride cells in seawater, NKA �1b was present in greater amounts in the subapical region than elsewhere in the cell. The combined patterns in abundance and immunolocalization of these two isoforms can explain the salinity-related changes in total NKA and chloride cell abundance. The results indicate that there is a freshwater and a seawater isoform of NKA �-subunit in the gills of Atlantic salmon and that they are present in distinct chloride cells. Key words: osmoregulation, ion transport, mitochondrion-rich cell, Salmo salar. |
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