Metabolic and Ultrastructural Adaptations to Chronically Cold Body Temperature in Antarctic Fishes

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Thermal conditions under which the evolution of Antarctic fish species occurred are unique among the the waters of the globe. Sea temperatures in the Antarctic are severely cold (near -l.0 degrees C) and vary little seasonally). This project will characterize adaptations to chronically cold body temperature in metabolism and subcellular organization of muscle tissues from Antarctic fishes. Major objectives are: (1) to assess the catabolic capacity of tissues for breakdown of abundant neutral lipid fuels; (2) to determine the relative roles of mitochondrial and peroxismal beta-oxidation and the substrate preferenda of each; (3) to evaluate the possible adaptive significance of high corporeal lipid content of Antarctic fishes in the movement of oxygen through muscle tissues, and; (4) to identify unique aspects of subcellular organization of tissues in Antarctic fishes. Experiments will focus upon two red-blooded (Notothenia gibberifrons, Trematomus newnesi) and one hemoglobinless (Chaenocephalus aceratus) fish species that are abundant in waters of the Antarctic Peninsula. Results will better define the significance in Antarctic fishes of high corporeal fat content which represents an important caloric resource in the Antarctic ecosystem. Findings may also apply to the physiology and biochemistry of less easily studied muscle systems which show similar characteristics, for example, endurance training in mammalian species, including man.