Kathrin Dausmann releasing a fat-tailed lemur from a silver box.
Kathrin Dausmann, an ecologist at the University of Hamburg, travels to field sites in Madagascar to study tropical hibernators, such as the fat-tailed dwarf lemur.
Kathrin Dausmann, Julian Glos

The term hibernation evokes images of plump bears curled up in cozy dens to survive winter. But these aren’t the only places to find slumbering critters. 

Earlier in her career, Kathrin Dausmann, an ecologist at the University of Hamburg, became perplexed while running fieldwork in Madagascar. “We had a very cute species in the forest that nobody knew what they did during winter. They just were gone,” she said. Eventually, Dausmann found the adorable fat-tailed dwarf lemur hibernating in tree holes and underground chambers.1,2 

During hibernation, animals slow their metabolisms and match their internal body temperatures to ambient conditions. Whether tropical hibernators—primates in particular—use similar cellular and molecular mechanisms as cold-weather animals to regulate this state of suspended animation remains largely unknown. “We lag behind 50 years of hibernation research in the tropical areas,” said Dausmann. 

To change that, Ken Storey, a molecular physiologist at Carleton University, ran a series of studies in the grey mouse lemur, a warm weather primate. In one study comparing lemurs in and out of hibernation, he measured changes in the expression of genes that scientists previously identified to regulate hibernation in arctic ground squirrels.4 Relative to awake controls, hibernating lemurs exhibited an upregulation in only a selection of the genes, which primarily occurred in the liver and brown fat. Storey also observed tissue-specific, differential activation of the mitogen-activated protein kinase (MAPK) signal transduction and insulin signaling pathways, elevations in heat shock proteins and antioxidant enzymes, an upregulation in microRNA implicated in cell development and survival pathways, and a downregulation in microRNA targeting immune function.5-8

Understanding the molecular drivers of hibernation, especially in primates, could provide new solutions for organ preservation. Rather than cooling organs, which can cause damage, exploiting strategies that tropical hibernators use to maintain organs at nearly normal physiological levels could extend the transplant timeline.9 

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References

  1. Dausmann KH, et al. Nature. 2004;429(6994):825-826.
  2. Blanco MB, et al. Sci Rep. 2013;3:1768.
  3. Mohr SM, et al. Annu Rev Cell Dev Biol. 2020;36:315-338.
  4. Biggar KK, et al. Genomics Proteomics Bioinformatics. 2015;13(2):111-118.
  5. Biggar KK, et al. Genomics Proteomics Bioinformatics. 2015;13(2):81-90.
  6. Tessier SN, et al. Genomics Proteomics Bioinformatics. 2015;13(2):91-102.
  7. Wu C-W, et al. Genomics Proteomics Bioinformatics. 2015;13(2):119-126.
  8. Biggar KK, et al. Gene. 2018;677:332-339.
  9. Hadj-Moussa H, Storey KB. FEBS J. 2019;286(6):1094-1100.