Microtubule Function, Protein Folding, and Embryogenesis in Antarctic Fishes: An Integrative Approach

Since the advent of Antarctic continental glaciation, the opening of the Drake Passage between South America and the Antarctic Peninsula, and the onset of cooling of the Southern Ocean ~40-25 million years ago, evolution of the Antarctic marine biota has been driven by the development of extreme cold temperatures. The biochemical and physiological challenges facing ectotherms living in the Southern Ocean include the reduction of reaction rates and metabolic fluxes and a pervasive weakening of macromolecular interactions. Yet, Southern Ocean ectotherms are now threatened by warming over periods measured in centuries or less. The proposed research seeks to understand the molecular mechanisms of cold adaptation in Antarctic marine fishes and to assess the physiological capacity of these organisms to resist or compensate for rapid oceanic warming. The P.I. will characterize two important and interacting protein systems, the tubulins that form microtubules and the chaperonin CCT (cytoplasmic chaperonin-containing TCP-1, a family of proteins that assists the folding of the tubulins). Higher-level, integrative responses to global temperature change will be analyzed by studying the thermal dependence of cleavage in Antarctic fish embryos (a microtubule-dependent process). The objectives are (1) to determine the contributions of five novel amino acid substitutions found in Antarctic fish beta-tubulins to microtubule assembly at cold temperature. (2) to compare the functional properties of CCT from testis tissues of Antarctic fishes and mammals. (3) to evaluate the effects of increased temperature on embryogenesis in Antarctic fishes. The research will introduce graduate and REU undergraduate students to state-of-the-art biochemical, cellular, and molecular-biological research relevant to ecological and environmental issues of the Antarctic marine ecosystem. The proposed work also will benefit society by developing a cold-functioning chaperonin protein folding system, of great value to the biopharmaceutical and biotechnological industries for use in folding insoluble proteins.