Thesis
The Relationship Between Circadian Gene Transcription and Metabolism in Hibernating Brown Bears, Ursus Arctos
Washington State University
Master of Science (MS), Washington State University
2023
DOI:
https://doi.org/10.7273/000005275
Abstract
Hibernation is a highly seasonal physiological adaptation that allows animals to survive periods of low food availability for up to eight months at a time. Brown bears (Ursus arctos) rely solely on fat reserves that were obtained during the active season (May-July) and hyperphagia (August-October) and subsequently lower their metabolic rate up to 75% and their body temperature (Tb) by 4-7°C to conserve energy during hibernation. Similarly, daily or circadian rhythms conserve energy by coordinating body processes to optimally match the environmental light:dark cycle. Brown bears express circadian rhythms in vivo and in vitro throughout the year, suggesting that they may play an important role during periods of negative energy balance. The present study attempts to link circadian rhythms, temperature, and cellular energetics in bear adipose-derived fibroblasts (ADF’s) collected during the active and hibernation seasons. We examined gene transcription and ATP production in vitro in samples collected at frequent time intervals. Time-series analysis of RNA sequencing data and timed measurements of ATP production in ADF’s of each season type confirmed that rhythmicity was present at the transcriptional level and for ATP production. Culture temperature matching that of hibernation Tb resulted in a delay of daily peak ATP production in comparison to active season temperatures. Peaks of mitochondrial gene transcription were altered as were the amplitudes of genes coding for enzymes of the electron transport chain (ETC). Additionally, we observed changes in mean expression and timing of key metabolic genes such as SIRT1 and AMPK which are tied to the circadian system. These results reveal a direct link between energy conservation in hibernation and a functioning circadian system.
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Details
- Title
- The Relationship Between Circadian Gene Transcription and Metabolism in Hibernating Brown Bears, Ursus Arctos
- Creators
- Ellery Pauline Vincent
- Contributors
- Heiko T Jansen (Advisor)Charles T Robbins (Committee Member)Wesley W Dowd (Committee Member)Patrick A Carter (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Biological Sciences, School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University
- Number of pages
- 72
- Identifiers
- 99901019231901842
- Language
- English
- Resource Type
- Thesis