As the Southern Ocean cooled during the past 25 million years, the fishes of Antarctic coastal waters evolved biochemical and physiological adaptations that maintain essential cellular processes such as cytoskeletal function and gene transcription. Their microtubules, for example, assemble and function at body temperatures (-1.8 to +1 degree centigrade) well below those of temperate species. The long-range goals of this research project are to determine, at the molecular level, the adaptations that enhance the assembly of microtubules, the expression of tubulin and globin genes, and the activity of microtubule motors in this extreme thermal regime. The specific objects are three in number: 1) to determine the primary sequence changes that contribute to the efficient polymerization of Antarctic fish tubulins at low temperatures; 2) to characterize the structure, organization and promoter-driven expression of tubulin and globin genes from an Antarctic rockcod and a temperate congener; and 3) to examine the biochemical adaptation required for efficient function of the brain kinesin motor of Antarctic fishes at low temperatures. Together, these studies should reveal the molecular adaptation of Antarctic fishes that maintain efficient cytoskeletal assembly, mechanochemical motor function, and gene expression at low temperatures.
