The adaptation to salinity: protein synthesis and some aspects of energy transduction in fish gill mitochondria.

Exposure of freshwater fish to saline conditions brings about somewhat drastic changes in the mitochondrial energy metabolism. These include abolition of oxidative phosphorylation, ATP-induced contraction of swollen mitochondria and transhydrogenase activity. On the other hand the endogenous calcium levels and protein synthetic capacity are elevated. In vitro protein synthesis by mitochondria from freshwater and stressed fish shows qualitative and quantitative variations. Effluxing the excess calcium by treatment with NaCl or inhibiting the protein synthesis by chloramphenicol in stressed mitochondria restores almost all the functions. It is proposed that the energy potential formed by the mitochondrial membrane is channelized to perform different functions and that the ratio of channelization can be altered to suit the needs of the cell.