Pub Date : 2024-07-02DOI: 10.1038/s44323-024-00002-4
Shingo Gibo, Yoshifumi Yamaguchi, Elena O. Gracheva, Sviatoslav N. Bagriantsev, Isao T. Tokuda, Gen Kurosawa
Hibernation allows mammals to endure harsh seasons by reducing their basal metabolism and body temperature (Tb) to minimize energy expenditure. During hibernation in small animals such as Syrian hamsters and 13-lined ground squirrels, Tb decreases to an ambient level ( < 5 °C) and remains constant for days to weeks in a physiological condition termed deep torpor. Torpor is interrupted by periods of arousal, during which Tb recovers to a euthermic level (approximately 37 °C), and these torpor–arousal cycles are repeated multiple times during hibernation. However, little is known about the mechanisms governing Tb fluctuations during hibernation. In this study, we employed an unbiased model selection approach to Tb data and revealed that a model incorporating frequency modulation quantitatively reproduced Tb fluctuation during hibernation in Syrian hamsters. We found that an unexpectedly long period of 120–430 days modulates a shorter period of several days. In addition, the aforementioned model reproduced Tb fluctuation in 13-lined ground squirrels, which can undergo repeated hibernation according to intrinsic circannual rhythms in constant laboratory conditions. This is the first quantitative study to demonstrate the concerted action of two endogenous periods, one lasting a few days and the other lasting a year, in the torpor–arousal cycles of distinct mammalian hibernators. We anticipate that our theoretical analysis of Tb fluctuation will be a starting point for quantitative comparisons of hibernation patterns across various hibernating species. Furthermore, quantification of Tb data using models will foster our understanding of the molecular mechanisms of hibernation by revealing the biological processes operating within these periods.
{"title":"Frequency-modulated timer regulates torpor–arousal cycles during hibernation in distinct small mammalian hibernators","authors":"Shingo Gibo, Yoshifumi Yamaguchi, Elena O. Gracheva, Sviatoslav N. Bagriantsev, Isao T. Tokuda, Gen Kurosawa","doi":"10.1038/s44323-024-00002-4","DOIUrl":"10.1038/s44323-024-00002-4","url":null,"abstract":"Hibernation allows mammals to endure harsh seasons by reducing their basal metabolism and body temperature (Tb) to minimize energy expenditure. During hibernation in small animals such as Syrian hamsters and 13-lined ground squirrels, Tb decreases to an ambient level ( < 5 °C) and remains constant for days to weeks in a physiological condition termed deep torpor. Torpor is interrupted by periods of arousal, during which Tb recovers to a euthermic level (approximately 37 °C), and these torpor–arousal cycles are repeated multiple times during hibernation. However, little is known about the mechanisms governing Tb fluctuations during hibernation. In this study, we employed an unbiased model selection approach to Tb data and revealed that a model incorporating frequency modulation quantitatively reproduced Tb fluctuation during hibernation in Syrian hamsters. We found that an unexpectedly long period of 120–430 days modulates a shorter period of several days. In addition, the aforementioned model reproduced Tb fluctuation in 13-lined ground squirrels, which can undergo repeated hibernation according to intrinsic circannual rhythms in constant laboratory conditions. This is the first quantitative study to demonstrate the concerted action of two endogenous periods, one lasting a few days and the other lasting a year, in the torpor–arousal cycles of distinct mammalian hibernators. We anticipate that our theoretical analysis of Tb fluctuation will be a starting point for quantitative comparisons of hibernation patterns across various hibernating species. Furthermore, quantification of Tb data using models will foster our understanding of the molecular mechanisms of hibernation by revealing the biological processes operating within these periods.","PeriodicalId":501704,"journal":{"name":"npj Biological Timing and Sleep","volume":" ","pages":"1-12"},"PeriodicalIF":0.0,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44323-024-00002-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141500488","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-19DOI: 10.1038/s44323-024-00003-3
Mostafa Mortada, Lu Xiong, Paloma Mas
The plant circadian clock regulates daily and seasonal rhythms of key biological processes, from growth and development to metabolism and physiology. Recent circadian research is moving beyond whole plants to specific cells, tissues, and organs. In this review, we summarize our understanding of circadian organization in plants, with a focus on communication and synchronization between circadian oscillators, also known as circadian coupling. We describe the different strengths of intercellular coupling and highlight recent advances supporting interorgan communication. Experimental and mathematical evidence suggests that plants precisely balance both the circadian autonomy of individual cellular clocks and synchronization between neighboring cells and across distal tissues and organs. This complex organization has probably evolved to optimize the specific functions of each cell type, tissue, or organ while sustaining global circadian coordination. Circadian coordination may be essential for proper regulation of growth, development, and responses to specific environmental conditions.
{"title":"Dissecting the complexity of local and systemic circadian communication in plants","authors":"Mostafa Mortada, Lu Xiong, Paloma Mas","doi":"10.1038/s44323-024-00003-3","DOIUrl":"10.1038/s44323-024-00003-3","url":null,"abstract":"The plant circadian clock regulates daily and seasonal rhythms of key biological processes, from growth and development to metabolism and physiology. Recent circadian research is moving beyond whole plants to specific cells, tissues, and organs. In this review, we summarize our understanding of circadian organization in plants, with a focus on communication and synchronization between circadian oscillators, also known as circadian coupling. We describe the different strengths of intercellular coupling and highlight recent advances supporting interorgan communication. Experimental and mathematical evidence suggests that plants precisely balance both the circadian autonomy of individual cellular clocks and synchronization between neighboring cells and across distal tissues and organs. This complex organization has probably evolved to optimize the specific functions of each cell type, tissue, or organ while sustaining global circadian coordination. Circadian coordination may be essential for proper regulation of growth, development, and responses to specific environmental conditions.","PeriodicalId":501704,"journal":{"name":"npj Biological Timing and Sleep","volume":" ","pages":"1-7"},"PeriodicalIF":0.0,"publicationDate":"2024-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44323-024-00003-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141435706","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-19DOI: 10.1038/s44323-024-00001-5
Aya Honma, Marina Nohara, Sato Honma, Akihiro Homma
This study aims to evaluate the association between sleep-wake rhythm regularity and continuous positive airway pressure (CPAP) adherence. We retrospectively analyzed sleep-wake rhythms with activity monitoring and CPAP adherence among obstructive sleep apnea (OSA) patients newly diagnosed and introduced to CPAP therapy at the Sapporo Hanazono Hospital from January 2018 to June 2022. Among a total of 45 patients, 10 withdrew from CPAP therapy within a year. Nineteen were classified into the good-adherence and 16 into the poor-adherence group. No significant differences were detected among the groups in apnea-hypopnea index (AHI), sleep efficiency, or subjective sleep quality, but a difference was observed in sleep latency, with the CPAP withdrawal group showing higher variability in sleep onset and lower regularity and/or amplitude in circadian behavior activity rhythm than the good-adherence group. Our results suggest that irregularities, particularly in sleep onset, and damped sleep-wake rhythm can be risk factors for CPAP withdrawal.
{"title":"The association between irregularity in sleep-wake rhythm and CPAP adherence","authors":"Aya Honma, Marina Nohara, Sato Honma, Akihiro Homma","doi":"10.1038/s44323-024-00001-5","DOIUrl":"10.1038/s44323-024-00001-5","url":null,"abstract":"This study aims to evaluate the association between sleep-wake rhythm regularity and continuous positive airway pressure (CPAP) adherence. We retrospectively analyzed sleep-wake rhythms with activity monitoring and CPAP adherence among obstructive sleep apnea (OSA) patients newly diagnosed and introduced to CPAP therapy at the Sapporo Hanazono Hospital from January 2018 to June 2022. Among a total of 45 patients, 10 withdrew from CPAP therapy within a year. Nineteen were classified into the good-adherence and 16 into the poor-adherence group. No significant differences were detected among the groups in apnea-hypopnea index (AHI), sleep efficiency, or subjective sleep quality, but a difference was observed in sleep latency, with the CPAP withdrawal group showing higher variability in sleep onset and lower regularity and/or amplitude in circadian behavior activity rhythm than the good-adherence group. Our results suggest that irregularities, particularly in sleep onset, and damped sleep-wake rhythm can be risk factors for CPAP withdrawal.","PeriodicalId":501704,"journal":{"name":"npj Biological Timing and Sleep","volume":" ","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2024-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44323-024-00001-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141435711","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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