Modulation of gene expression in heart and liver of hibernating black bears ( XXXX ).

@entity1 @entity1522 @entity844 @entity308 @entity535 @entity1735 @entity25785 @entity2057
BACKGROUND: Hibernation is an adaptive strategy to survive in highly seasonal or unpredictable environments. The molecular and genetic basis of hibernation physiology in mammals has only recently been studied using large scale genomic approaches. We analyzed gene expression in the @entity25785 , @entity25785 , using a custom 12,800 cDNA probe microarray to detect differences in expression that occur in heart and liver during winter hibernation in comparison to summer active animals. RESULTS: We identified 245 genes in heart and 319 genes in liver that were differentially expressed between winter and summer. The expression of 24 genes was significantly elevated during hibernation in both heart and liver. These genes are mostly involved in lipid catabolism and protein biosynthesis and include RNA binding protein motif 3 (Rbm3), which enhances protein synthesis at mildly hypothermic temperatures. Elevated expression of protein biosynthesis genes suggests induction of translation that may be related to adaptive mechanisms reducing cardiac and @entity2057 over extended periods of low metabolism and immobility during hibernation in bears. Coordinated reduction of transcription of genes involved in @entity535 catabolism suggests redirection of @entity1522 from catabolic pathways to protein biosynthesis. We identify common for black bears and small @entity1 hibernators transcriptional changes in the liver that include induction of genes responsible for @entity844 b oxidation and @entity1735 synthesis and @entity308 of genes involved in lipid biosynthesis, @entity1735 catabolism, cellular respiration and detoxification pathways. CONCLUSIONS: Our findings show that modulation of gene expression during winter hibernation represents molecular mechanism of adaptation to extreme environments.
