Eddy, S.F., Morin, P.J. and Storey, K.B. 2006. Differential expression of selected mitochondrial genes in hibernating little brown bats, Myotis lucifugus. J. Exp. Zool. A 292, 89-98.

Sean F. Eddy, Pier J. Morin and Kenneth B. Storey
Differential expression of selected mitochondrial genes in hibernating little brown bats, Myotis lucifugus

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Abstract

During hibernation, brown adipose tissue (BAT) is the only tissue or organ remaining metabolically active and is responsible for non-shivering thermogenesis in a number of species, particularly small hibernators, such as the little brown bat, Myotis lucifugus. Previous studies have suggested that changes in the mitochondria occur during hibernation in BAT and are partially responsible for its capacity for non-shivering thermogenesis. In this current study, mitochondrial enzymes and selected genes and proteins were induced during torpor in M. lucifugus. Protein extracts prepared from M. lucifugus BAT showed that cytochrome oxidase activity was found at least three-fold higher during torpor as compared to activity assayed from extracts prepared from euthermic animals. Mitochondrial encoded genes, including coxII and nad4 also displayed three- to four-fold higher levels during torpor as evidenced by northern blotting. Furthermore, carnitine palmitoyl transferase-1ß an enzyme embedded in the outer membrane of the mitochondria that is the rate-limiting step enzyme in ß-oxidation was also elevated during torpor. Partial cloning of cpt-1ß revealed a number of amino acid substitutions in the deduced protein sequence compared to other mammalian CPT-1β proteins, which may be beneficial for low-temperature biology experienced during torpor in M. lucifugus. This study provides further evidence for a role of mitochondria in hibernation.