2023-11-16 ワシントン州立大学(WSU)
◆クマの冬眠における生体内時計の変動は、代謝健康との関連性が指摘されており、人間においても夜勤務などで生体リズムが乱れると体重増加や糖尿病のリスクが高まることが知られています。今後は、クマの冬眠中の異常な行動や変動が骨量減少や糖尿病などの疾患にどのように影響するかの調査が進む見通しです。
<関連情報>
- https://news.wsu.edu/press-release/2023/11/16/bear-genes-show-circadian-rhythms-even-during-hibernation/
- https://link.springer.com/article/10.1007/s00360-023-01513-5
冬眠中のヒグマ(Ursus arctos)の細胞代謝にサーカディアン遺伝子の転写が関与していることを発見 Circadian gene transcription plays a role in cellular metabolism in hibernating brown bears, Ursus arctos
Ellery P. Vincent,Blair W. Perry,Joanna L. Kelley,Charles T. Robbins &Heiko T. Jansen
Journal of Comparative Physiology B Published:11 October 2023
DOI:https://doi.org/10.1007/s00360-023-01513-5
Abstract
Hibernation is a highly seasonal physiological adaptation that allows brown bears (Ursus arctos) to survive extended periods of low food availability. 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 their cells do in vitro throughout the year, suggesting that these rhythms may play important roles during periods of negative energy balance. Here, we use time-series analysis of RNA sequencing data and timed measurements of ATP production in adipose-derived fibroblasts from active and hibernation seasons under two temperature conditions to confirm that rhythmicity was present. Culture temperature matching that of hibernation body temperature (34 °C) resulted in a delay of daily peak ATP production in comparison with active season body temperatures (37 °C). The timing of peaks of mitochondrial gene transcription was altered as were the amplitudes of transcripts coding for enzymes of the electron transport chain. Additionally, we observed changes in mean expression and timing of key metabolic genes such as SIRT1 and AMPK which are linked to the circadian system and energy balance. The amplitudes of several circadian gene transcripts were also reduced. These results reveal a link between energy conservation and a functioning circadian system in hibernation.
