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Turbill C, Walker M, Boardman W, Martin JM, McKeown A, Meade J, Welbergen JA. Torpor use in the wild by one of the world's largest bats. Proc Biol Sci 2024; 291:20241137. [PMID: 38981525 DOI: 10.1098/rspb.2024.1137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Accepted: 06/12/2024] [Indexed: 07/11/2024] Open
Abstract
Torpor is widespread among bats presumably because most species are small, and torpor greatly reduces their high mass-specific resting energy expenditure, especially in the cold. Torpor has not been recorded in any bat species larger than 50 g, yet in theory could be beneficial even in the world's largest bats (flying-foxes; Pteropus spp.) that are exposed to adverse environmental conditions causing energy bottlenecks. We used temperature telemetry to measure body temperature in wild-living adult male grey-headed flying-foxes (P. poliocephalus; 799 g) during winter in southern Australia. We found that all individuals used torpor while day-roosting, with minimum body temperature reaching 27°C. Torpor was recorded following a period of cool, wet and windy weather, and on a day with the coldest maximum air temperature, suggesting it is an adaptation to reduce energy expenditure during periods of increased thermoregulatory costs and depleted body energy stores. A capacity for torpor among flying-foxes has implications for understanding their distribution, behavioural ecology and life history. Furthermore, our discovery increases the body mass of bats known to use torpor by more than tenfold and extends the documented use of this energy-saving strategy under wild conditions to all bat superfamilies, with implications for the evolutionary maintenance of torpor among bats and other mammals.
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Affiliation(s)
- Christopher Turbill
- Hawkesbury Institute for the Environment, Western Sydney University , Penrith, New South Wales, Australia
- School of Science, Western Sydney University , Penrith, New South Wales, Australia
| | - Melissa Walker
- Hawkesbury Institute for the Environment, Western Sydney University , Penrith, New South Wales, Australia
| | - Wayne Boardman
- School of Animal and Veterinary Sciences, University of Adelaide , Roseworthy, South Australia, Australia
| | - John M Martin
- Taronga Conservation Society , Mosman, New South Wales, Australia
| | - Adam McKeown
- CSIRO Land & Water , Atherton, Queensland, Australia
| | - Jessica Meade
- Hawkesbury Institute for the Environment, Western Sydney University , Penrith, New South Wales, Australia
| | - Justin A Welbergen
- Hawkesbury Institute for the Environment, Western Sydney University , Penrith, New South Wales, Australia
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2
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van der Vinne V, McKillop LE, Wilcox SL, Cantley J, Peirson SN, Swoap SJ, Vyazovskiy VV. Methods to estimate body temperature and energy expenditure dynamics in fed and fasted laboratory mice: effects of sleep deprivation and light exposure. J Comp Physiol B 2024; 194:369-381. [PMID: 38653849 PMCID: PMC11233429 DOI: 10.1007/s00360-024-01554-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Accepted: 04/04/2024] [Indexed: 04/25/2024]
Abstract
Monitoring body temperature and energy expenditure in freely-moving laboratory mice remains a powerful methodology used widely across a variety of disciplines-including circadian biology, sleep research, metabolic phenotyping, and the study of body temperature regulation. Some of the most pronounced changes in body temperature are observed when small heterothermic species reduce their body temperature during daily torpor. Daily torpor is an energy saving strategy characterized by dramatic reductions in body temperature employed by mice and other species when challenged to meet energetic demands. Typical measurements used to describe daily torpor are the measurement of core body temperature and energy expenditure. These approaches can have drawbacks and developing alternatives for these techniques provides options that can be beneficial both from an animal-welfare and study-complexity perspective. First, this paper presents and assesses a method to estimate core body temperature based on measurements of subcutaneous body temperature, and second, a separate approach to better estimate energy expenditure during daily torpor based on core body temperature. Third, the effects of light exposure during the habitual dark phase and sleep deprivation during the light period on body temperature dynamics were tested preliminary in fed and fasted mice. Together, the here-published approaches and datasets can be used in the future to assess body temperature and metabolism in freely-moving laboratory mice.
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Affiliation(s)
- Vincent van der Vinne
- Sleep and Circadian Neurosciences Institute, Department of Physiology and Genetics, University of Oxford, Oxford, UK.
- Department of Psychology & Neuroscience, Drake University, Des Moines, IA, USA.
| | - Laura E McKillop
- Sleep and Circadian Neurosciences Institute, Department of Physiology and Genetics, University of Oxford, Oxford, UK
| | - Sian L Wilcox
- Sleep and Circadian Neurosciences Institute, Department of Physiology and Genetics, University of Oxford, Oxford, UK
| | - James Cantley
- Division of Systems Medicine, School of Medicine, University of Dundee, Dundee, UK
| | - Stuart N Peirson
- Sleep and Circadian Neurosciences Institute, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Steven J Swoap
- Department of Biology, Williams College, Williamstown, MA, USA
| | - Vladyslav V Vyazovskiy
- Sleep and Circadian Neurosciences Institute, Department of Physiology and Genetics, University of Oxford, Oxford, UK.
- The Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford, UK.
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3
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Noiret A, Karanewsky C, Aujard F, Terrien J. Sex-specific heterothermy patterns in wintering captive Microcebus murinus do not translate into differences in energy balance. J Therm Biol 2024; 121:103829. [PMID: 38569326 DOI: 10.1016/j.jtherbio.2024.103829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 02/28/2024] [Accepted: 02/28/2024] [Indexed: 04/05/2024]
Abstract
The physiological mechanisms of responses to stressors are at the core of ecophysiological studies that examine the limits of an organism's flexibility. Interindividual variability in these physiological responses can be particularly important and lead to differences in the stress response among population groups, which can affect population dynamics. Some observations of intersexual differences in heterothermy raise the question of whether there is a difference in energy management between the sexes. In this study, we assessed male and female differences in mouse lemurs (Microcebus murinus), a highly seasonal malagasy primate, by measuring their physiological flexibility in response to caloric restriction and examining the subsequent impact on reproductive success. Using complementary methods aiming to describe large-scale and daily variations in body temperature throughout a 6-month winter-like short-day (SD) period, we monitored 12 males and 12 females, applying chronic 40% caloric restriction (CR) to 6 individuals in each group. We found variations in Tb modulation throughout the SD period and in response to caloric treatment that depended on sex, as females, regardless of food restriction, and CR males, only, entered deep torpor. The use of deeper torpor, however, did not translate into a lower loss of body mass in females and did not affect reproductive success. Captive conditions may have buffered the depth of torpor and minimised the positive effects of torpor on energy savings. However, the significant sex differences in heterothermy we observed may point to physiological benefits other than preservation of energy reserves.
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Affiliation(s)
- Aude Noiret
- Unité Mécanismes Adaptatifs et Evolution (MECADEV), Muséum National D'Histoire Naturelle, CNRS UMR 7179, Brunoy, France.
| | - Caitlin Karanewsky
- Department of Biochemistry, Stanford University School of Medicine, California, 94305, USA
| | - Fabienne Aujard
- Unité Mécanismes Adaptatifs et Evolution (MECADEV), Muséum National D'Histoire Naturelle, CNRS UMR 7179, Brunoy, France
| | - Jérémy Terrien
- Unité Mécanismes Adaptatifs et Evolution (MECADEV), Muséum National D'Histoire Naturelle, CNRS UMR 7179, Brunoy, France.
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4
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Hare MT, Carter ME, Swoap SJ. Activation of oxytocinergic neurons enhances torpor in mice. J Comp Physiol B 2024; 194:95-104. [PMID: 38170253 DOI: 10.1007/s00360-023-01528-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2023] [Revised: 11/13/2023] [Accepted: 11/20/2023] [Indexed: 01/05/2024]
Abstract
Mus musculus enters a torpid state in response to caloric restriction in sub-thermoneutral ambient temperatures. This torpid state is characterized by an adaptive and controlled decrease in metabolic rate, heart rate, body temperature, and activity. Previous research has identified the paraventricular nucleus (PVN) within the hypothalamus, a region containing oxytocin neurons, as a location that is active during torpor onset. We hypothesized that oxytocin neurons within the PVN are part of this neural circuit and that activation of oxytocin neurons would deepen and lengthen torpor bouts. We report that activation of oxytocin neurons alone is not sufficient to induce a torpor-like state in the fed mouse, with no significant difference in body temperature or heart rate upon activation of oxytocin neurons. However, we found that activation of oxytocin neurons prior to the onset of daily torpor both deepens and lengthens the subsequent bout, with a 1.7 ± 0.4 °C lower body temperature and a 135 ± 32 min increase in length. We therefore conclude that oxytocin neurons are involved in the neural circuitry controlling daily torpor in the mouse.
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Affiliation(s)
- Maia T Hare
- Department of Biology, Williams College, Williamstown, MA, 01267, USA
- Zucker School of Medicine at Hofstra/Northwell, 500 Hofstra Blvd, Hempstead, NY, 11549, USA
| | - Matthew E Carter
- Department of Biology, Williams College, Williamstown, MA, 01267, USA
| | - Steven J Swoap
- Department of Biology, Williams College, Williamstown, MA, 01267, USA.
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5
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Diedrich V, Haugg E, Van Hee J, Herwig A. Role of glucose in daily torpor of Djungarian hamsters ( Phodopus sungorus): challenge of continuous in vivo blood glucose measurements. Am J Physiol Regul Integr Comp Physiol 2023; 325:R359-R379. [PMID: 37519255 DOI: 10.1152/ajpregu.00040.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 07/03/2023] [Accepted: 07/23/2023] [Indexed: 08/01/2023]
Abstract
Djungarian hamsters use daily torpor to save energy during winter. This metabolic downstate is part of their acclimatization strategy in response to short photoperiod and expressed spontaneously without energy challenges. During acute energy shortage, torpor incidence, depth, and duration can be modulated. Torpor induction might rely on glucose availability as acute metabolic energy source. To investigate this, the present study provides the first continuous in vivo blood glucose measurements of spontaneous daily torpor in short photoperiod-acclimated and fasting-induced torpor in long photoperiod-acclimated Djungarian hamsters. Glucose levels were almost identical in both photoperiods and showed a decrease during resting phase. Further decreases appeared during spontaneous daily torpor entrance, parallel with metabolic rate but before body temperature, while respiratory exchange rates were rising. During arousal, blood glucose tended to increase, and pretorpor values were reached at torpor termination. Although food-restricted hamsters underwent a considerable energetic challenge, blood glucose levels remained stable during the resting phase regardless of torpor expression. The activity phase preceding a torpor bout did not reveal changes in blood glucose that might be used as torpor predictor. Djungarian hamsters show a robust, circadian rhythm in blood glucose irrespective of season and maintain appropriate levels throughout complex acclimation processes including metabolic downstates. Although these measurements could not reveal blood glucose as proximate torpor induction factor, they provide new information about glucose availability during torpor. Technical innovations like in vivo microdialysis and in vitro transcriptome or proteome analyses may help to uncover the connection between torpor expression and glucose metabolism.
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Affiliation(s)
| | - Elena Haugg
- Institute of Neurobiology, Ulm University, Ulm, Germany
| | - Justin Van Hee
- Data Sciences International, St. Paul, Minnesota, United States
| | - Annika Herwig
- Institute of Neurobiology, Ulm University, Ulm, Germany
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6
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Nogueira-de-Sá PG, Bicudo JEPW, Chaui-Berlinck JG. Energy and time optimization during exit from torpor in vertebrate endotherms. J Comp Physiol B 2023:10.1007/s00360-023-01494-5. [PMID: 37171656 DOI: 10.1007/s00360-023-01494-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Accepted: 04/25/2023] [Indexed: 05/13/2023]
Abstract
Torpor is used in small sized birds and mammals as an energy conservation trait. Considerable effort has been put towards elucidating the mechanisms underlying its entry and maintenance, but little attention has been paid regarding the exit. Firstly, we demonstrate that the arousal phase has a stereotyped dynamic: there is a sharp increase in metabolic rate followed by an increase in body temperature and, then, a damped oscillation in body temperature and metabolism. Moreover, the metabolic peak is around two-fold greater than the corresponding euthermic resting metabolic rate. We then hypothesized that either time or energy could be crucial variables to this event and constructed a model from a collection of first principles of physiology, control engineering and thermodynamics. From the model, we show that the stereotyped pattern of the arousal is a solution to save both time and energy. We extended the analysis to the scaling of the use of torpor by endotherms and show that variables related to the control system of body temperature emerge as relevant to the arousal dynamics. In this sense, the stereotyped dynamics of the arousal phase necessitates a certain profile of these variables which is not maintained as body size increases.
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Affiliation(s)
- Pedro Goes Nogueira-de-Sá
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brasil
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7
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Christmas MJ, Kaplow IM, Genereux DP, Dong MX, Hughes GM, Li X, Sullivan PF, Hindle AG, Andrews G, Armstrong JC, Bianchi M, Breit AM, Diekhans M, Fanter C, Foley NM, Goodman DB, Goodman L, Keough KC, Kirilenko B, Kowalczyk A, Lawless C, Lind AL, Meadows JRS, Moreira LR, Redlich RW, Ryan L, Swofford R, Valenzuela A, Wagner F, Wallerman O, Brown AR, Damas J, Fan K, Gatesy J, Grimshaw J, Johnson J, Kozyrev SV, Lawler AJ, Marinescu VD, Morrill KM, Osmanski A, Paulat NS, Phan BN, Reilly SK, Schäffer DE, Steiner C, Supple MA, Wilder AP, Wirthlin ME, Xue JR, Birren BW, Gazal S, Hubley RM, Koepfli KP, Marques-Bonet T, Meyer WK, Nweeia M, Sabeti PC, Shapiro B, Smit AFA, Springer MS, Teeling EC, Weng Z, Hiller M, Levesque DL, Lewin HA, Murphy WJ, Navarro A, Paten B, Pollard KS, Ray DA, Ruf I, Ryder OA, Pfenning AR, Lindblad-Toh K, Karlsson EK. Evolutionary constraint and innovation across hundreds of placental mammals. Science 2023; 380:eabn3943. [PMID: 37104599 PMCID: PMC10250106 DOI: 10.1126/science.abn3943] [Citation(s) in RCA: 49] [Impact Index Per Article: 49.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 12/16/2022] [Indexed: 04/29/2023]
Abstract
Zoonomia is the largest comparative genomics resource for mammals produced to date. By aligning genomes for 240 species, we identify bases that, when mutated, are likely to affect fitness and alter disease risk. At least 332 million bases (~10.7%) in the human genome are unusually conserved across species (evolutionarily constrained) relative to neutrally evolving repeats, and 4552 ultraconserved elements are nearly perfectly conserved. Of 101 million significantly constrained single bases, 80% are outside protein-coding exons and half have no functional annotations in the Encyclopedia of DNA Elements (ENCODE) resource. Changes in genes and regulatory elements are associated with exceptional mammalian traits, such as hibernation, that could inform therapeutic development. Earth's vast and imperiled biodiversity offers distinctive power for identifying genetic variants that affect genome function and organismal phenotypes.
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Affiliation(s)
- Matthew J. Christmas
- Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, 751 32 Uppsala, Sweden
| | - Irene M. Kaplow
- Department of Computational Biology, School of Computer Science, Carnegie Mellon University, Pittsburgh, PA 15213, USA
- Neuroscience Institute, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | | | - Michael X. Dong
- Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, 751 32 Uppsala, Sweden
| | - Graham M. Hughes
- School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Xue Li
- Broad Institute of MIT and Harvard, Cambridge, MA 02139, USA
- Morningside Graduate School of Biomedical Sciences, UMass Chan Medical School, Worcester, MA 01605, USA
- Program in Bioinformatics and Integrative Biology, UMass Chan Medical School, Worcester, MA 01605, USA
| | - Patrick F. Sullivan
- Department of Genetics, University of North Carolina Medical School, Chapel Hill, NC 27599, USA
- Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden
| | - Allyson G. Hindle
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV 89154, USA
| | - Gregory Andrews
- Program in Bioinformatics and Integrative Biology, UMass Chan Medical School, Worcester, MA 01605, USA
| | - Joel C. Armstrong
- Genomics Institute, University of California Santa Cruz, Santa Cruz, CA 95064, USA
| | - Matteo Bianchi
- Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, 751 32 Uppsala, Sweden
| | - Ana M. Breit
- School of Biology and Ecology, University of Maine, Orono, ME 04469, USA
| | - Mark Diekhans
- Genomics Institute, University of California Santa Cruz, Santa Cruz, CA 95064, USA
| | - Cornelia Fanter
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV 89154, USA
| | - Nicole M. Foley
- Veterinary Integrative Biosciences, Texas A&M University, College Station, TX 77843, USA
| | - Daniel B. Goodman
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, CA 94143, USA
| | | | - Kathleen C. Keough
- Fauna Bio, Inc., Emeryville, CA 94608, USA
- Department of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, CA 94158, USA
- Gladstone Institutes, San Francisco, CA 94158, USA
| | - Bogdan Kirilenko
- Faculty of Biosciences, Goethe-University, 60438 Frankfurt, Germany
- LOEWE Centre for Translational Biodiversity Genomics, 60325 Frankfurt, Germany
- Senckenberg Research Institute, 60325 Frankfurt, Germany
| | - Amanda Kowalczyk
- Department of Computational Biology, School of Computer Science, Carnegie Mellon University, Pittsburgh, PA 15213, USA
- Neuroscience Institute, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Colleen Lawless
- School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Abigail L. Lind
- Department of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, CA 94158, USA
- Gladstone Institutes, San Francisco, CA 94158, USA
| | - Jennifer R. S. Meadows
- Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, 751 32 Uppsala, Sweden
| | - Lucas R. Moreira
- Broad Institute of MIT and Harvard, Cambridge, MA 02139, USA
- Program in Bioinformatics and Integrative Biology, UMass Chan Medical School, Worcester, MA 01605, USA
| | - Ruby W. Redlich
- Department of Biological Sciences, Mellon College of Science, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Louise Ryan
- School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Ross Swofford
- Broad Institute of MIT and Harvard, Cambridge, MA 02139, USA
| | - Alejandro Valenzuela
- Department of Experimental and Health Sciences, Institute of Evolutionary Biology (UPF-CSIC), Universitat Pompeu Fabra, 08003 Barcelona, Spain
| | - Franziska Wagner
- Museum of Zoology, Senckenberg Natural History Collections Dresden, 01109 Dresden, Germany
| | - Ola Wallerman
- Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, 751 32 Uppsala, Sweden
| | - Ashley R. Brown
- Department of Computational Biology, School of Computer Science, Carnegie Mellon University, Pittsburgh, PA 15213, USA
- Neuroscience Institute, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Joana Damas
- The Genome Center, University of California Davis, Davis, CA 95616, USA
| | - Kaili Fan
- Program in Bioinformatics and Integrative Biology, UMass Chan Medical School, Worcester, MA 01605, USA
| | - John Gatesy
- Division of Vertebrate Zoology, American Museum of Natural History, New York, NY 10024, USA
| | - Jenna Grimshaw
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA
| | - Jeremy Johnson
- Broad Institute of MIT and Harvard, Cambridge, MA 02139, USA
| | - Sergey V. Kozyrev
- Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, 751 32 Uppsala, Sweden
| | - Alyssa J. Lawler
- Neuroscience Institute, Carnegie Mellon University, Pittsburgh, PA 15213, USA
- Broad Institute of MIT and Harvard, Cambridge, MA 02139, USA
- Department of Biological Sciences, Mellon College of Science, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Voichita D. Marinescu
- Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, 751 32 Uppsala, Sweden
| | - Kathleen M. Morrill
- Broad Institute of MIT and Harvard, Cambridge, MA 02139, USA
- Morningside Graduate School of Biomedical Sciences, UMass Chan Medical School, Worcester, MA 01605, USA
- Program in Bioinformatics and Integrative Biology, UMass Chan Medical School, Worcester, MA 01605, USA
| | - Austin Osmanski
- Medical Scientist Training Program, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Nicole S. Paulat
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA
| | - BaDoi N. Phan
- Department of Computational Biology, School of Computer Science, Carnegie Mellon University, Pittsburgh, PA 15213, USA
- Neuroscience Institute, Carnegie Mellon University, Pittsburgh, PA 15213, USA
- Medical Scientist Training Program, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Steven K. Reilly
- Department of Genetics, Yale School of Medicine, New Haven, CT 06510, USA
| | - Daniel E. Schäffer
- Department of Computational Biology, School of Computer Science, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Cynthia Steiner
- Conservation Genetics, San Diego Zoo Wildlife Alliance, Escondido, CA 92027, USA
| | - Megan A. Supple
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, CA 95064, USA
| | - Aryn P. Wilder
- Conservation Genetics, San Diego Zoo Wildlife Alliance, Escondido, CA 92027, USA
| | - Morgan E. Wirthlin
- Department of Computational Biology, School of Computer Science, Carnegie Mellon University, Pittsburgh, PA 15213, USA
- Neuroscience Institute, Carnegie Mellon University, Pittsburgh, PA 15213, USA
- Allen Institute for Brain Science, Seattle, WA 98109, USA
| | - James R. Xue
- Broad Institute of MIT and Harvard, Cambridge, MA 02139, USA
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | | | - Bruce W. Birren
- Broad Institute of MIT and Harvard, Cambridge, MA 02139, USA
| | - Steven Gazal
- Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
| | | | - Klaus-Peter Koepfli
- Center for Species Survival, Smithsonian’s National Zoo and Conservation Biology Institute, Washington, DC 20008, USA
- Computer Technologies Laboratory, ITMO University, St. Petersburg 197101, Russia
- Smithsonian-Mason School of Conservation, George Mason University, Front Royal, VA 22630, USA
| | - Tomas Marques-Bonet
- Catalan Institution of Research and Advanced Studies (ICREA), 08010 Barcelona, Spain
- CNAG-CRG, Centre for Genomic Regulation, Barcelona Institute of Science and Technology (BIST), 08036 Barcelona, Spain
- Department of Medicine and Life Sciences, Institute of Evolutionary Biology (UPF-CSIC), Universitat Pompeu Fabra, 08003 Barcelona, Spain
- Institut Català de Paleontologia Miquel Crusafont, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Barcelona, Spain
| | - Wynn K. Meyer
- Department of Biological Sciences, Lehigh University, Bethlehem, PA 18015, USA
| | - Martin Nweeia
- Department of Comprehensive Care, School of Dental Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
- Department of Vertebrate Zoology, Canadian Museum of Nature, Ottawa, Ontario K2P 2R1, Canada
- Department of Vertebrate Zoology, Smithsonian Institution, Washington, DC 20002, USA
- Narwhal Genome Initiative, Department of Restorative Dentistry and Biomaterials Sciences, Harvard School of Dental Medicine, Boston, MA 02115, USA
| | - Pardis C. Sabeti
- Broad Institute of MIT and Harvard, Cambridge, MA 02139, USA
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA 02138, USA
| | - Beth Shapiro
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, CA 95064, USA
- Howard Hughes Medical Institute, University of California Santa Cruz, Santa Cruz, CA 95064, USA
| | | | - Mark S. Springer
- Department of Evolution, Ecology and Organismal Biology, University of California Riverside, Riverside, CA 92521, USA
| | - Emma C. Teeling
- School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Zhiping Weng
- Program in Bioinformatics and Integrative Biology, UMass Chan Medical School, Worcester, MA 01605, USA
| | - Michael Hiller
- Faculty of Biosciences, Goethe-University, 60438 Frankfurt, Germany
- LOEWE Centre for Translational Biodiversity Genomics, 60325 Frankfurt, Germany
- Senckenberg Research Institute, 60325 Frankfurt, Germany
| | | | - Harris A. Lewin
- The Genome Center, University of California Davis, Davis, CA 95616, USA
- Department of Evolution and Ecology, University of California Davis, Davis, CA 95616, USA
- John Muir Institute for the Environment, University of California Davis, Davis, CA 95616, USA
| | - William J. Murphy
- Veterinary Integrative Biosciences, Texas A&M University, College Station, TX 77843, USA
| | - Arcadi Navarro
- Catalan Institution of Research and Advanced Studies (ICREA), 08010 Barcelona, Spain
- Department of Medicine and Life Sciences, Institute of Evolutionary Biology (UPF-CSIC), Universitat Pompeu Fabra, 08003 Barcelona, Spain
- BarcelonaBeta Brain Research Center, Pasqual Maragall Foundation, 08005 Barcelona, Spain
- CRG, Centre for Genomic Regulation, Barcelona Institute of Science and Technology (BIST), 08003 Barcelona, Spain
| | - Benedict Paten
- Genomics Institute, University of California Santa Cruz, Santa Cruz, CA 95064, USA
| | - Katherine S. Pollard
- Department of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, CA 94158, USA
- Gladstone Institutes, San Francisco, CA 94158, USA
- Chan Zuckerberg Biohub, San Francisco, CA 94158, USA
| | - David A. Ray
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA
| | - Irina Ruf
- Division of Messel Research and Mammalogy, Senckenberg Research Institute and Natural History Museum Frankfurt, 60325 Frankfurt am Main, Germany
| | - Oliver A. Ryder
- Conservation Genetics, San Diego Zoo Wildlife Alliance, Escondido, CA 92027, USA
- Department of Evolution, Behavior and Ecology, School of Biological Sciences, University of California San Diego, La Jolla, CA 92039, USA
| | - Andreas R. Pfenning
- Department of Computational Biology, School of Computer Science, Carnegie Mellon University, Pittsburgh, PA 15213, USA
- Neuroscience Institute, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Kerstin Lindblad-Toh
- Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, 751 32 Uppsala, Sweden
- Broad Institute of MIT and Harvard, Cambridge, MA 02139, USA
| | - Elinor K. Karlsson
- Broad Institute of MIT and Harvard, Cambridge, MA 02139, USA
- Program in Bioinformatics and Integrative Biology, UMass Chan Medical School, Worcester, MA 01605, USA
- Program in Molecular Medicine, UMass Chan Medical School, Worcester, MA 01605, USA
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8
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Revelo Hernández DC, Baldwin JW, Londoño GA. Ecological drivers and consequences of torpor in Andean hummingbirds. Proc Biol Sci 2023; 290:20222099. [PMID: 36919431 PMCID: PMC10015325 DOI: 10.1098/rspb.2022.2099] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 02/20/2023] [Indexed: 03/16/2023] Open
Abstract
Daily torpor allows endotherms to save energy during energetically stressful (e.g. cold) conditions. Although studies on avian torpor have mostly been conducted under laboratory conditions, information on the usage of torpor in the wild is limited to few, predominantly temperate-zone species. We studied torpor under seminatural conditions from 249 individuals from 29 hummingbird species across a 1920 m elevational gradient in the western Andes of Colombia using cloacal thermistors. Small birds were more likely to use torpor than large birds, but only at low ambient temperatures, where torpor was prolonged. We also found effects of proxy variables for body condition and energy expenditure on the use of torpor, its characteristics, and impacts. Our results suggest that context-dependency and phylogenetic variation in the probability of deploying torpor can help understand clade-wide patterns of elevational distribution in Andean hummingbirds.
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Affiliation(s)
| | - Justin W. Baldwin
- Department of Biology, Washington University, St. Louis, MO 63130, USA
| | - Gustavo A. Londoño
- Universidad Icesi, Facultad de Ciencias Naturales, Departamento de Ciencias Biológicas, Calle 18 No. 122-135, Cali, Colombia
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9
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Tupone D, Hernan S, Chiavetta P, Morrison S, Cano G. Central circuit controlling thermoregulatory inversion and torpor-like state. RESEARCH SQUARE 2023:rs.3.rs-2698203. [PMID: 36993654 PMCID: PMC10055657 DOI: 10.21203/rs.3.rs-2698203/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
Abstract
To maintain core body temperature in mammals, the CNS thermoregulatory networks respond to cold exposure by increasing brown adipose tissue and shivering thermogenesis. However, in hibernation or torpor, this normal thermoregulatory response is supplanted by "thermoregulatory inversion", an altered homeostatic state in which cold exposure causes inhibition of thermogenesis and warm exposure stimulates thermogenesis. Here we demonstrate the existence of a novel, dynorphinergic thermoregulatory reflex pathway between the dorsolateral parabrachial nucleus and the dorsomedial hypothalamus that bypasses the normal thermoregulatory integrator in the hypothalamic preoptic area to play a critical role in mediating the inhibition of thermogenesis during thermoregulatory inversion. Our results indicate the existence of a neural circuit mechanism for thermoregulatory inversion within the CNS thermoregulatory pathways and support the potential for inducing a homeostatically-regulated, therapeutic hypothermia in non-hibernating species, including humans.
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10
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Determining the different phases of torpor from skin- or body temperature data in heterotherms. J Therm Biol 2023; 111:103396. [PMID: 36585072 DOI: 10.1016/j.jtherbio.2022.103396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 10/28/2022] [Accepted: 11/22/2022] [Indexed: 11/27/2022]
Abstract
Technological innovations have made heat-sensitive data-loggers smaller, more efficient and less expensive, which has led to a growing body of literature that measures the skin- or body temperatures of small animals in their natural environments. Studies of this type on heterothermic endotherms have prompted much debate regarding how to best define 'torpor' expressions from skin- or body temperature data alone. We propose a new quantitative method for defining torpor 'entries', 'arousals' and 'stable torpor periods' whilst comparing the results to 'torpor bout' durations identified using only the torpor cut-off method. By decomposing a torpor bout into 'entries', 'stable torpor periods', and 'active arousals', we avoid biases introduced by using strict threshold temperature values for the onset of torpor, thereby allowing better insight into individual use of torpor. We present our method as an easy-to-use function written in R-code, offering an un-biased and consistent methodology to be applied on skin- or body temperature measurements across datasets and research groups. When testing the function on a large dataset of skin temperature data collected on three bat species in Norway (Plecotus auritus: Nind = 39; Eptesicus nilssonii: Nind = 11; Myotis brandtii: Nind = 10), we identified 461 complete torpor bouts across species. More than 40% of the torpor bouts (Nbouts = 192) did not contain stable torpor periods, because the bats aroused before they had reached a stable skin temperature level. Furthermore, only considering 'torpid' and 'euthermic' temperature values by applying strict cut-off thresholds led to potentially large underestimations of torpor bout durations compared to our quantitative determination of the onset and termination of each torpor bout. We highlight the importance of differentiating between torpor phases, especially for active arousals that can be very energetically expensive and may alter our evaluation of the actual energetic savings gained by an individual employing torpor.
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11
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A thermodynamic-based approach to model the entry into metabolic depression by mammals and birds. J Comp Physiol B 2022; 192:593-610. [PMID: 35737097 DOI: 10.1007/s00360-022-01442-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 05/05/2022] [Accepted: 05/15/2022] [Indexed: 10/17/2022]
Abstract
For decades, there was an intense debate in relation to the mechanism behind the entry into metabolic depression (EMD) of mammals and birds. The fulcrum of the argument was whether the depression of metabolic rate ([Formula: see text]) was caused by the drop in body temperature, the so-called "Q10 effect", or whether it was caused by a metabolic downregulation. One present-day model of this process is a qualitative (textual) description: the initial step of EDM would be a downregulation in [Formula: see text] from the value maintaining euthermia at a given ambient temperature to the basal metabolic rate of the animal and, then, Q10 effect would take over and drop [Formula: see text] to its lower levels. Despite widely accepted, this qualitative description still misses a theoretical analysis. Here, we transpose the descriptive model to a formal quantitative one and analyze it under necessary thermodynamic conditions of a system. We, then, compare the results of the formal model to empirical data of EMD by mammals and birds. The comparisons indicate that the metabolic evolution in the course of the entry phase does not follow the descriptive model. Instead, as proposed by alternate models, EMD is a downregulated process as a whole until a new equilibrium Tb is attained.
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12
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Hill RW. Nestling Altricial Rodents and Lagomorphs Are Not Ectotherms. Physiol Biochem Zool 2022; 95:474-483. [DOI: 10.1086/721446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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13
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Reinisch I, Klymiuk I, Michenthaler H, Moyschewitz E, Galhuber M, Krstic J, Domingo M, Zhang F, Karbiener M, Vujić N, Kratky D, Schreiber R, Schupp M, Lenihan-Geels G, Schulz TJ, Malli R, Madl T, Prokesch A. p53 Regulates a miRNA-Fructose Transporter Axis in Brown Adipose Tissue Under Fasting. Front Genet 2022; 13:913030. [PMID: 35734423 PMCID: PMC9207587 DOI: 10.3389/fgene.2022.913030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 05/02/2022] [Indexed: 11/25/2022] Open
Abstract
Active thermogenic adipocytes avidly consume energy substrates like fatty acids and glucose to maintain body temperature upon cold exposure. Despite strong evidence for the involvement of brown adipose tissue (BAT) in controlling systemic energy homeostasis upon nutrient excess, it is unclear how the activity of brown adipocytes is regulated in times of nutrient scarcity. Therefore, this study aimed to scrutinize factors that modulate BAT activity to balance thermogenic and energetic needs upon simultaneous fasting and cold stress. For an unbiased view, we performed transcriptomic and miRNA sequencing analyses of BAT from acutely fasted (24 h) mice under mild cold exposure. Combining these data with in-depth bioinformatic analyses and in vitro gain-of-function experiments, we define a previously undescribed axis of p53 inducing miR-92a-1-5p transcription that is highly upregulated by fasting in thermogenic adipocytes. p53, a fasting-responsive transcription factor, was previously shown to control genes involved in the thermogenic program and miR-92a-1-5p was found to negatively correlate with human BAT activity. Here, we identify fructose transporter Slc2a5 as one direct downstream target of this axis and show that fructose can be taken up by and metabolized in brown adipocytes. In sum, this study delineates a fasting-induced pathway involving p53 that transactivates miR-92a-1-5p, which in turn decreases Slc2a5 expression, and suggests fructose as an energy substrate in thermogenic adipocytes.
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Affiliation(s)
- Isabel Reinisch
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Division of Cell Biology, Histology and Embryology, Medical University of Graz, Graz, Austria
| | - Ingeborg Klymiuk
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Division of Cell Biology, Histology and Embryology, Medical University of Graz, Graz, Austria
| | - Helene Michenthaler
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Division of Cell Biology, Histology and Embryology, Medical University of Graz, Graz, Austria
| | - Elisabeth Moyschewitz
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Division of Cell Biology, Histology and Embryology, Medical University of Graz, Graz, Austria
| | - Markus Galhuber
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Division of Cell Biology, Histology and Embryology, Medical University of Graz, Graz, Austria
| | - Jelena Krstic
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Division of Cell Biology, Histology and Embryology, Medical University of Graz, Graz, Austria
| | - Magnus Domingo
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Division of Cell Biology, Histology and Embryology, Medical University of Graz, Graz, Austria
| | - Fangrong Zhang
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Division of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
- Key Laboratory of Gastrointestinal Cancer, Ministry of Education, School of Basic Medical Sciences, Fujian Medical University, Fuzhou, China
| | | | - Nemanja Vujić
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Division of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Dagmar Kratky
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Division of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Renate Schreiber
- Institute of Molecular Biosciences, University of Graz, NAWI Graz, Graz, Austria
- BioHealth Graz, Graz, Austria
| | - Michael Schupp
- Cardiovascular Metabolic Renal (CMR)- Research Center, Institute of Pharmacology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt- Universität zu Berlin, Berlin, Germany
| | - Georgia Lenihan-Geels
- Department of Adipocyte Development and Nutrition, German Institute of Human Nutrition Potsdam-Rehbrücke, Nuthetal, Germany
| | - Tim J. Schulz
- Department of Adipocyte Development and Nutrition, German Institute of Human Nutrition Potsdam-Rehbrücke, Nuthetal, Germany
| | - Roland Malli
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Division of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Tobias Madl
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Division of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Andreas Prokesch
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Division of Cell Biology, Histology and Embryology, Medical University of Graz, Graz, Austria
- *Correspondence: Andreas Prokesch,
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14
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Ambler M, Hitrec T, Pickering A. Turn it off and on again: characteristics and control of torpor. Wellcome Open Res 2022; 6:313. [PMID: 35087956 PMCID: PMC8764563 DOI: 10.12688/wellcomeopenres.17379.2] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/14/2022] [Indexed: 11/20/2022] Open
Abstract
Torpor is a hypothermic, hypoactive, hypometabolic state entered into by a wide range of animals in response to environmental challenge. This review summarises the current understanding of torpor. We start by describing the characteristics of the wide-ranging physiological adaptations associated with torpor. Next follows a discussion of thermoregulation, control of food intake and energy expenditure, and the interactions of sleep and thermoregulation, with particular emphasis on how those processes pertain to torpor. We move on to review the evidence for the systems that control torpor entry, including both the efferent circulating factors that signal the need for torpor, and the central processes that orchestrate it. Finally, we consider how the putative circuits responsible for torpor induction integrate with the established understanding of thermoregulation under non-torpid conditions and highlight important areas of uncertainty for future studies.
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Affiliation(s)
- Michael Ambler
- School of Physiology, Pharmacology, & Neuroscience, University of Bristol, Bristol, Bristol, BS8 1TD, UK
| | - Timna Hitrec
- School of Physiology, Pharmacology, & Neuroscience, University of Bristol, Bristol, Bristol, BS8 1TD, UK
| | - Anthony Pickering
- School of Physiology, Pharmacology, & Neuroscience, University of Bristol, Bristol, Bristol, BS8 1TD, UK
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15
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Mejías C, Navedo J, Sabat P, Franco LM, Bozinovic F, Nespolo RF. Body Composition and Energy Savings by Hibernation: Lessons from the South American Marsupial Dromiciops gliroides. Physiol Biochem Zool 2022; 95:239-250. [DOI: 10.1086/719932] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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16
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Reher S, Rabarison H, Nowack J, Dausmann KH. Limited Physiological Compensation in Response to an Acute Microclimate Change in a Malagasy Bat. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.779381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Rapid environmental changes are challenging for endothermic species because they have direct and immediate impacts on their physiology by affecting microclimate and fundamental resource availability. Physiological flexibility can compensate for certain ecological perturbations, but our basic understanding of how species function in a given habitat and the extent of their adaptive scope is limited. Here we studied the effect of acute, experimental microclimate change on the thermal physiology of two populations of the widespread Malagasy bat, Macronycteris commersoni. Populations of this species are found roosting under contrasting conditions, i.e., in a constant hot and humid cave or below foliage unprotected from fluctuations in ambient conditions. We exposed free-ranging individuals of each population to the respective opposite condition and thus to novel microclimate within an ecologically realistic scope while measuring metabolic rate and skin temperature. Cave bats in forest setting had a limited capacity to maintain euthermia to the point that two individuals became hypothermic when ambient temperature dropped below their commonly experienced cave temperature. Forest bats on the other hand, had difficulties to dissipate heat in the humid cave set-up. The response to heat, however, was surprisingly uniform and all bats entered torpor combined with hyperthermia at temperatures exceeding their thermoneutral zone. Thus, while we observed potential for flexible compensation of heat through “hot” torpor, both populations showed patterns suggestive of limited potential to cope with acute microclimate changes deviating from their typically occupied roosts. Our study emphasizes that intraspecific variation among populations could be misleading when assessing species’ adaptive scopes, as variation may arise from genetic adaptation, developmental plasticity or phenotypic flexibility, all of which allow for compensatory responses at differing time scales. Disentangling these mechanisms and identifying the basis of variation is vital to make accurate predictions of species’ chances for persisting in ever rapidly changing habitats and climates.
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17
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Fontúrbel FE, Franco LM, Bozinovic F, Quintero‐Galvis JF, Mejías C, Amico GC, Vazquez MS, Sabat P, Sánchez‐Hernández JC, Watson DM, Saenz‐Agudelo P, Nespolo RF. The ecology and evolution of the monito del monte, a relict species from the southern South America temperate forests. Ecol Evol 2022; 12:e8645. [PMID: 35261741 PMCID: PMC8888251 DOI: 10.1002/ece3.8645] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 01/12/2022] [Accepted: 01/14/2022] [Indexed: 12/23/2022] Open
Abstract
The arboreal marsupial monito del monte (genus Dromiciops, with two recognized species) is a paradigmatic mammal. It is the sole living representative of the order Microbiotheria, the ancestor lineage of Australian marsupials. Also, this marsupial is the unique frugivorous mammal in the temperate rainforest, being the main seed disperser of several endemic plants of this ecosystem, thus acting as keystone species. Dromiciops is also one of the few hibernating mammals in South America, spending half of the year in a physiological dormancy where metabolism is reduced to 10% of normal levels. This capacity to reduce energy expenditure in winter contrasts with the enormous energy turnover rate they experience in spring and summer. The unique life history strategies of this living Microbiotheria, characterized by an alternation of life in the slow and fast lanes, putatively represent ancestral traits that permitted these cold‐adapted mammals to survive in this environment. Here, we describe the ecological role of this emblematic marsupial, summarizing the ecophysiology of hibernation and sociality, updated phylogeographic relationships, reproductive cycle, trophic relationships, mutualisms, conservation, and threats. This marsupial shows high densities, despite presenting slow reproductive rates, a paradox explained by the unique characteristics of its three‐dimensional habitat. We finally suggest immediate actions to protect these species that may be threatened in the near future due to habitat destruction and climate change.
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Affiliation(s)
- Francisco E. Fontúrbel
- Instituto de Biología Pontificia Universidad Católica de Valparaíso Valparaíso Chile
- Millennium Nucleus of Patagonian Limit of Life (LiLi) Santiago Chile
| | - Lida M. Franco
- Facultad de Ciencias Naturales y Matemáticas Universidad de Ibagué Ibagué Colombia
| | - Francisco Bozinovic
- Departamento de Ecología Facultad de Ciencias Biológicas Center of Applied Ecology and Sustainability (CAPES) Pontificia Universidad Católica de Chile Santiago Chile
| | | | - Carlos Mejías
- Instituto de Ciencias Ambientales y Evolutivas Universidad Austral de Chile Valdivia Chile
| | | | | | - Pablo Sabat
- Departamento de Ciencias Ecológicas Facultad de Ciencias Universidad de Chile Santiago Chile
| | | | - David M. Watson
- School of Agricultural, Environmental and Veterinary Sciences Charles Sturt University Albury NSW Australia
| | - Pablo Saenz‐Agudelo
- Instituto de Ciencias Ambientales y Evolutivas Universidad Austral de Chile Valdivia Chile
| | - Roberto F. Nespolo
- Millennium Nucleus of Patagonian Limit of Life (LiLi) Santiago Chile
- Departamento de Ecología Facultad de Ciencias Biológicas Center of Applied Ecology and Sustainability (CAPES) Pontificia Universidad Católica de Chile Santiago Chile
- Instituto de Ciencias Ambientales y Evolutivas Universidad Austral de Chile Valdivia Chile
- Millennium Institute for Integrative Biology (iBio) Santiago Chile
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18
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Shankar A, Cisneros INH, Thompson S, Graham CH, Powers DR. A heterothermic spectrum in hummingbirds. J Exp Biol 2022; 225:273909. [PMID: 34989393 DOI: 10.1242/jeb.243208] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 12/29/2021] [Indexed: 11/20/2022]
Abstract
Many endotherms use torpor, saving energy by a controlled reduction of their body temperature and metabolic rate. Some species (e.g., arctic ground squirrels, hummingbirds) enter deep torpor, dropping their body temperatures by 23-37°C, while others can only enter shallow torpor (e.g., pigeons, 3-10°C reductions). However, deep torpor in mammals can increase predation risk (unless animals are in burrows or caves), inhibit immune function, and result in sleep deprivation, so even for species that can enter deep torpor, facultative shallow torpor might help balance energy savings with these potential costs. Deep torpor occurs in three avian orders, but the trade-offs of deep torpor in birds are unknown. Although the literature hints that some bird species (mousebirds and perhaps hummingbirds) can use both shallow and deep torpor, little empirical evidence of such an avian heterothermy spectrum within species exists. We infrared imaged three hummingbird species that are known to use deep torpor, under natural temperature and light cycles, to test if they were also capable of shallow torpor. All three species used both deep and shallow torpor, often on the same night. Depending on the species, they used shallow torpor for 5-35% of the night. The presence of a heterothermic spectrum in these bird species indicates a capacity for fine-scale physiological and genetic regulation of avian torpid metabolism.
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Affiliation(s)
- Anusha Shankar
- Stony Brook University, Stony Brook, NY 11794, USA.,Swiss Federal Research Institute (WSL), Birmensdorf, CH-8903, Switzerland
| | | | | | - Catherine H Graham
- Stony Brook University, Stony Brook, NY 11794, USA.,Swiss Federal Research Institute (WSL), Birmensdorf, CH-8903, Switzerland
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19
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Emser SV, Schaschl H, Millesi E, Steinborn R. Extension of Mitogenome Enrichment Based on Single Long-Range PCR: mtDNAs and Putative Mitochondrial-Derived Peptides of Five Rodent Hibernators. Front Genet 2021; 12:685806. [PMID: 35027919 PMCID: PMC8749263 DOI: 10.3389/fgene.2021.685806] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 11/10/2021] [Indexed: 12/14/2022] Open
Abstract
Enriching mitochondrial DNA (mtDNA) for sequencing entire mitochondrial genomes (mitogenomes) can be achieved by single long-range PCR. This avoids interference from the omnipresent nuclear mtDNA sequences (NUMTs). The approach is currently restricted to the use of samples collected from humans and ray-finned fishes. Here, we extended the use of single long-range PCR by introducing back-to-back oligonucleotides that target a sequence of extraordinary homology across vertebrates. The assay was applied to five hibernating rodents, namely alpine marmot, Arctic and European ground squirrels, and common and garden dormice, four of which have not been fully sequenced before. Analysis of the novel mitogenomes focussed on the prediction of mitochondrial-derived peptides (MDPs) providing another level of information encoded by mtDNA. The comparison of MOTS-c, SHLP4 and SHLP6 sequences across vertebrate species identified segments of high homology that argue for future experimentation. In addition, we evaluated four candidate polymorphisms replacing an amino acid in mitochondrially encoded subunits of the oxidative phosphorylation (OXPHOS) system that were reported in relation to cold-adaptation. No obvious pattern was found for the diverse sets of mammalian species that either apply daily or multiday torpor or otherwise cope with cold. In summary, our single long-range PCR assay applying a pair of back-to-back primers that target a consensus sequence motif of Vertebrata has potential to amplify (intact) mitochondrial rings present in templates from a taxonomically diverse range of vertebrates. It could be promising for studying novel mitogenomes, mitotypes of a population and mitochondrial heteroplasmy in a sensitive, straightforward and flexible manner.
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Affiliation(s)
- Sarah V. Emser
- Genomics Core Facility, VetCore, University of Veterinary Medicine, Vienna, Austria
- Department of Behavioral and Cognitive Biology, University of Vienna, Vienna, Austria
| | - Helmut Schaschl
- Department of Evolutionary Anthropology, University of Vienna, Vienna, Austria
| | - Eva Millesi
- Department of Behavioral and Cognitive Biology, University of Vienna, Vienna, Austria
| | - Ralf Steinborn
- Genomics Core Facility, VetCore, University of Veterinary Medicine, Vienna, Austria
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20
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Ambler M, Hitrec T, Pickering A. Turn it off and on again: characteristics and control of torpor. Wellcome Open Res 2021; 6:313. [DOI: 10.12688/wellcomeopenres.17379.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/12/2021] [Indexed: 11/20/2022] Open
Abstract
Torpor is a hypothermic, hypoactive, hypometabolic state entered into by a wide range of animals in response to environmental challenge. This review summarises the current understanding of torpor. We start by describing the characteristics of the wide-ranging physiological adaptations associated with torpor. Next follows a discussion of thermoregulation, control of food intake and energy expenditure, and the interactions of sleep and thermoregulation, with particular emphasis on how those processes pertain to torpor. We move on to take a critical view of the evidence for the systems that control torpor entry, including both the efferent circulating factors that signal the need for torpor, and the central processes that orchestrate it. Finally, we consider how the putative circuits responsible for torpor induction integrate with the established understanding of thermoregulation under non-torpid conditions and highlight important areas of uncertainty for future studies.
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21
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Nowack J, Turbill C. Survivable hypothermia or torpor in a wild-living rat: rare insights broaden our understanding of endothermic physiology. J Comp Physiol B 2021; 192:183-192. [PMID: 34668054 PMCID: PMC8817056 DOI: 10.1007/s00360-021-01416-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 09/08/2021] [Accepted: 10/03/2021] [Indexed: 12/16/2022]
Abstract
Maintaining a high and stable body temperature as observed in endothermic mammals and birds is energetically costly. Thus, it is not surprising that we discover more and more heterothermic species that can reduce their energetic needs during energetic bottlenecks through the use of torpor. However, not all heterothermic animals use torpor on a regular basis. Torpor may also be important to an individual’s probability of survival, and hence fitness, when used infrequently. We here report the observation of a single, ~ 5.5 h long hypothermic bout with a decrease in body temperature by 12 °C in the native Australian bush rat (Rattus fuscipes). Our data suggest that bush rats are able to rewarm from a body temperature of 24 °C, albeit with a rewarming rate lower than that expected on the basis of their body mass. Heterothermy, i.e. the ability to withstand and overcome periods of reduced body temperature, is assumed to be an evolutionarily ancestral (plesiomorphic) trait. We thus argue that such rare hypothermic events in species that otherwise appear to be strictly homeothermic could be heterothermic rudiments, i.e. a less derived form of torpor with limited capacity for rewarming. Importantly, observations of rare and extreme thermoregulatory responses by wild animals are more likely to be discovered with long-term data sets and may not only provide valuable insight about the physiological capability of a population, but can also help us to understand the constraints and evolutionary pathways of different phenologies.
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Affiliation(s)
- Julia Nowack
- Hawkesbury Institute for the Environment and School of Science, Western Sydney University, Richmond, NSW, Australia. .,School of Biological and Environmental Sciences, Liverpool John Moores University, Byrom Street, Liverpool, L3 3AF, UK.
| | - Christopher Turbill
- Hawkesbury Institute for the Environment and School of Science, Western Sydney University, Richmond, NSW, Australia
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22
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Linek N, Volkmer T, Shipley JR, Twining CW, Zúñiga D, Wikelski M, Partecke J. A songbird adjusts its heart rate and body temperature in response to season and fluctuating daily conditions. Philos Trans R Soc Lond B Biol Sci 2021; 376:20200213. [PMID: 34121457 PMCID: PMC8200648 DOI: 10.1098/rstb.2020.0213] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/15/2021] [Indexed: 12/11/2022] Open
Abstract
In a seasonal world, organisms are continuously adjusting physiological processes relative to local environmental conditions. Owing to their limited heat and fat storage capacities, small animals, such as songbirds, must rapidly modulate their metabolism in response to weather extremes and changing seasons to ensure survival. As a consequence of previous technical limitations, most of our existing knowledge about how animals respond to changing environmental conditions comes from laboratory studies or field studies over short temporal scales. Here, we expanded beyond previous studies by outfitting 71 free-ranging Eurasian blackbirds (Turdus merula) with novel heart rate and body temperature loggers coupled with radio transmitters, and followed individuals in the wild from autumn to spring. Across seasons, blackbirds thermoconformed at night, i.e. their body temperature decreased with decreasing ambient temperature, but not so during daytime. By contrast, during all seasons blackbirds increased their heart rate when ambient temperatures became colder. However, the temperature setpoint at which heart rate was increased differed between seasons and between day and night. In our study, blackbirds showed an overall seasonal reduction in mean heart rate of 108 beats min-1 (21%) as well as a 1.2°C decrease in nighttime body temperature. Episodes of hypometabolism during cold periods likely allow the birds to save energy and, thus, help offset the increased energetic costs during the winter when also confronted with lower resource availability. Our data highlight that, similar to larger non-hibernating mammals and birds, small passerine birds such as Eurasian blackbirds not only adjust their heart rate and body temperature on daily timescales, but also exhibit pronounced seasonal changes in both that are modulated by local environmental conditions such as temperature. This article is part of the theme issue 'Measuring physiology in free-living animals (Part I)'.
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Affiliation(s)
- Nils Linek
- Max Planck Institute of Animal Behavior, Radolfzell, Germany
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Tamara Volkmer
- Max Planck Institute of Animal Behavior, Radolfzell, Germany
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - J Ryan Shipley
- Max Planck Institute of Animal Behavior, Radolfzell, Germany
| | - Cornelia W Twining
- Max Planck Institute of Animal Behavior, Radolfzell, Germany
- Limnological Institute, University of Konstanz, Konstanz, Germany
| | - Daniel Zúñiga
- Max Planck Institute of Animal Behavior, Radolfzell, Germany
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Martin Wikelski
- Max Planck Institute of Animal Behavior, Radolfzell, Germany
- Department of Biology, University of Konstanz, Konstanz, Germany
- Centre for the Advanced Study of Collective Behaviour, University of Konstanz, Konstanz, Germany
| | - Jesko Partecke
- Max Planck Institute of Animal Behavior, Radolfzell, Germany
- Department of Biology, University of Konstanz, Konstanz, Germany
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Cerri M, Hitrec T, Luppi M, Amici R. Be cool to be far: Exploiting hibernation for space exploration. Neurosci Biobehav Rev 2021; 128:218-232. [PMID: 34144115 DOI: 10.1016/j.neubiorev.2021.03.037] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 03/23/2021] [Accepted: 03/26/2021] [Indexed: 01/08/2023]
Abstract
In mammals, torpor/hibernation is a state that is characterized by an active reduction in metabolic rate followed by a progressive decrease in body temperature. Torpor was successfully mimicked in non-hibernators by inhibiting the activity of neurons within the brainstem region of the Raphe Pallidus, or by activating the adenosine A1 receptors in the brain. This state, called synthetic torpor, may be exploited for many medical applications, and for space exploration, providing many benefits for biological adaptation to the space environment, among which an enhanced protection from cosmic rays. As regards the use of synthetic torpor in space, to fully evaluate the degree of physiological advantage provided by this state, it is strongly advisable to move from Earth-based experiments to 'in the field' tests, possibly on board the International Space Station.
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Affiliation(s)
- Matteo Cerri
- Department of Biomedical and NeuroMotor Sciences, Alma Mater Studiorum -University of Bologna, Piazza di Porta S.Donato, 2 40126, Bologna, Italy.
| | - Timna Hitrec
- Department of Biomedical and NeuroMotor Sciences, Alma Mater Studiorum -University of Bologna, Piazza di Porta S.Donato, 2 40126, Bologna, Italy.
| | - Marco Luppi
- Department of Biomedical and NeuroMotor Sciences, Alma Mater Studiorum -University of Bologna, Piazza di Porta S.Donato, 2 40126, Bologna, Italy.
| | - Roberto Amici
- Department of Biomedical and NeuroMotor Sciences, Alma Mater Studiorum -University of Bologna, Piazza di Porta S.Donato, 2 40126, Bologna, Italy.
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24
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Limits of temperature adaptation and thermopreferendum. Cell Biosci 2021; 11:69. [PMID: 33823918 PMCID: PMC8025563 DOI: 10.1186/s13578-021-00574-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 03/18/2021] [Indexed: 11/10/2022] Open
Abstract
Background Managing the limits of temperature adaptation is relevant both in medicine and in biotechnology. There are numerous scattered publications on the identification of the temperature limits of existence for various organisms and using different methods. Dmitry Petrovich Kharakoz gave a general explanation for many of these experimental results. The hypothesis implied that each cycle of synaptic exocytosis includes reversible phase transitions of lipids of the presynaptic membrane due to the entry and subsequent removal of calcium ions from the synaptic terminal. The correspondence of the times of phase transitions has previously been experimentally shown on isolated lipids in vitro. In order to test the hypothesis of D.P. Kharakoz in vivo, we investigated the influence of the temperature of long-term acclimatization on the temperature of heat and cold shock, as well as on the kinetics of temperature adaptation in zebrafish. Testing the hypothesis included a comparison of our experimental results with the results of other authors obtained on various models from invertebrates to humans. Results The viability polygon for Danio rerio was determined by the minimum temperature of cold shock (about 6 °C), maximum temperature of heat shock (about 43 °C), and thermopreferendum temperature (about 27 °C). The ratio of the temperature range of cold shock to the temperature range of heat shock was about 1.3. These parameters obtained for Danio rerio describe with good accuracy those for the planarian Girardia tigrina, the ground squirrel Sermophilus undulatus, and for Homo sapiens. Conclusions The experimental values of the temperatures of cold shock and heat shock and the temperature of the thermal preferendum correspond to the temperatures of phase transitions of the lipid-protein composition of the synaptic membrane between the liquid and solid states. The viability range for zebrafish coincides with the temperature range, over which enzymes function effectively and also coincides with the viability polygons for the vast majority of organisms. The boundaries of the viability polygon are characteristic biological constants. The viability polygon of a particular organism is determined not only by the genome, but also by the physicochemical properties of lipids that make up the membrane structures of synaptic endings. The limits of temperature adaptation of any biological species are determined by the temperature range of the functioning of its nervous system.
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25
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Aharon-Rotman Y, Körtner G, Wacker CB, Geiser F. Do small precocial birds enter torpor to conserve energy during development? J Exp Biol 2020; 223:jeb231761. [PMID: 32978318 DOI: 10.1242/jeb.231761] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 09/15/2020] [Indexed: 01/24/2023]
Abstract
Precocial birds hatch feathered and mobile, but when they become fully endothermic soon after hatching, their heat loss is high and they may become energy depleted. These chicks could benefit from using energy-conserving torpor, which is characterised by controlled reductions of metabolism and body temperature (Tb). We investigated at what age the precocial king quail Coturnix chinensis can defend a high Tb under a mild thermal challenge and whether they can express torpor soon after achieving endothermy to overcome energetic and thermal challenges. Measurements of surface temperature (Ts) using an infrared thermometer showed that king quail chicks are partially endothermic at 2-10 days, but can defend high Tb at a body mass of ∼13 g. Two chicks expressed shallow nocturnal torpor at 14 and 17 days for 4-5 h with a reduction of metabolism by >40% and another approached the torpor threshold. Although chicks were able to rewarm endogenously from the first torpor bout, metabolism and Ts decreased again by the end of the night, but they rewarmed passively when removed from the chamber. The total metabolic rate increased with body mass. All chicks measured showed a greater reduction of nocturnal metabolism than previously reported in quails. Our data show that shallow torpor can be expressed during the early postnatal phase of quails, when thermoregulatory efficiency is still developing, but heat loss is high. We suggest that torpor may be a common strategy for overcoming challenging conditions during development in small precocial and not only altricial birds.
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Affiliation(s)
- Yaara Aharon-Rotman
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, NSW 2351, Australia
| | - Gerhard Körtner
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, NSW 2351, Australia
| | - Chris B Wacker
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, NSW 2351, Australia
| | - Fritz Geiser
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, NSW 2351, Australia
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26
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Zhang Z, Zhai Q, Gu Y, Zhang T, Huang Z, Liu Z, Liu Y, Xu Y. Impaired function of the suprachiasmatic nucleus rescues the loss of body temperature homeostasis caused by time-restricted feeding. Sci Bull (Beijing) 2020; 65:1268-1280. [PMID: 32864176 PMCID: PMC7455017 DOI: 10.1016/j.scib.2020.03.025] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The suprachiasmatic nucleus (SCN) is the master circadian pacemaker that drives body temperature rhythm. Time-restricted feeding (TRF) has potential as a preventative or therapeutic approach against many diseases. The potential side effects of TRF remain unknown. Here we show that a 4-hour TRF stimulus in mice can severely impair body temperature homeostasis and can result in lethality. Nearly half of the mice died at 21 °C, and all mice died at 18 °C during 4-hour TRF. Moreover, this effect was modulated by the circadian clock and was associated with severe hypothermia due to loss of body temperature homeostasis, which is different from "torpor", an adaptive response under food deprivation. Disrupting the circadian clock by the SCN lesions or a non-invasive method (constant light) which disrupts circadian clock rescued lethality during TRF. Analysis of circadian gene expression in the dorsomedial hypothalamus (DMH) demonstrated that TRF reprograms rhythmic transcriptome in DMH and suppresses expression of genes, such as Ccr5 and Calcrl, which are involved in thermoregulation. We demonstrate a side effect of 4-hour TRF on the homeostasis of body temperature and a rescue function by impairing the SCN function. Altogether, our results suggested that constructing a circadian arrhythmicity may have a beneficial effect on the host response to an acute stress.
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Affiliation(s)
- Zhihui Zhang
- Model Animal Research Center, Nanjing University, 12 Xuefu Road, Pukou District, Nanjing 210061, China
| | - Qiaocheng Zhai
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and Cambridge-Suda Genomic Resource Center, Soochow University, Suzhou, Jiangsu 215123, China
| | - Yue Gu
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and Cambridge-Suda Genomic Resource Center, Soochow University, Suzhou, Jiangsu 215123, China
| | - Tao Zhang
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and Cambridge-Suda Genomic Resource Center, Soochow University, Suzhou, Jiangsu 215123, China
| | - Zhengyun Huang
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and Cambridge-Suda Genomic Resource Center, Soochow University, Suzhou, Jiangsu 215123, China
| | - Zhiwei Liu
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and Cambridge-Suda Genomic Resource Center, Soochow University, Suzhou, Jiangsu 215123, China
| | - Yi Liu
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX 75390,Correspondence to: (Y.X.), (Y.L.)
| | - Ying Xu
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and Cambridge-Suda Genomic Resource Center, Soochow University, Suzhou, Jiangsu 215123, China,State Key Laboratory of Radiation Medicine and Protection, Soochow University, Suzhou 215123, China,Correspondence to: (Y.X.), (Y.L.)
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27
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Noiret A, Puch L, Riffaud C, Costantini D, Riou JF, Aujard F, Terrien J. Sex-Specific Response to Caloric Restriction After Reproductive Investment in Microcebus murinus: An Integrative Approach. Front Physiol 2020; 11:506. [PMID: 32612534 PMCID: PMC7308708 DOI: 10.3389/fphys.2020.00506] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 04/24/2020] [Indexed: 12/22/2022] Open
Abstract
In seasonal environments, males and females usually maintain high metabolic activity during the whole summer season, exhausting their energy reserves. In the global warming context, unpredictability of food availability during summer could dramatically challenge the energy budget of individuals. Therefore, one can predict that resilience to environmental stress would be dramatically endangered during summer. Here, we hypothesized that females could have greater capacity to survive harsh conditions than males, considering the temporal shift in their respective reproductive energy investment, which can challenge them differently, as well as enhanced flexibility in females' physiological regulation. We tackled this question on the gray mouse lemur (Microcebus murinus), focusing on the late summer period, after the reproductive effort. We monitored six males and six females before and after a 2-weeks 60% caloric restriction (CR), measuring different physiological and cellular parameters in an integrative and comparative multiscale approach. Before CR, females were heavier than males and mostly characterized by high levels of energy expenditure, a more energetic mitochondrial profile and a downregulation of blood antioxidants. We observed a similar energy balance between sexes due to CR, with a decrease in metabolic activity over time only in males. Oxidative damage to DNA was also reduced by different pathways between sexes, which may reflect variability in their physiological status and life-history traits at the end of summer. Finally, females' mitochondria seemed to exhibit greater flexibility and greater metabolic potential than males in response to CR. Our results showed strong differences between males and females in response to food shortage during late summer, underlining the necessity to consider sex as a factor for population dynamics in climate change models.
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Affiliation(s)
- Aude Noiret
- Unité Mécanismes Adaptatifs et Evolution (MECADEV), Muséum National d'Histoire Naturelle, CNRS UMR 7179, Brunoy, France
| | - Laura Puch
- Unité Mécanismes Adaptatifs et Evolution (MECADEV), Muséum National d'Histoire Naturelle, CNRS UMR 7179, Brunoy, France
| | - Coralie Riffaud
- Unité Mécanismes Adaptatifs et Evolution (MECADEV), Muséum National d'Histoire Naturelle, CNRS UMR 7179, Brunoy, France
| | - David Costantini
- Unité Physiologie Moléculaire et Adaptation (PhyMA), Muséum National d'Histoire Naturelle, CNRS UMR 7221, Paris, France
| | - Jean-Francois Riou
- Unité Structure et Instabilité des Génomes (STRING), Muséum National d'Histoire Naturelle, CNRS UMR 7196, INSERM U1154, Paris, France
| | - Fabienne Aujard
- Unité Mécanismes Adaptatifs et Evolution (MECADEV), Muséum National d'Histoire Naturelle, CNRS UMR 7179, Brunoy, France
| | - Jeremy Terrien
- Unité Mécanismes Adaptatifs et Evolution (MECADEV), Muséum National d'Histoire Naturelle, CNRS UMR 7179, Brunoy, France
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28
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Hrvatin S, Sun S, Wilcox OF, Yao H, Lavin-Peter AJ, Cicconet M, Assad EG, Palmer ME, Aronson S, Banks AS, Griffith EC, Greenberg ME. Neurons that regulate mouse torpor. Nature 2020; 583:115-121. [PMID: 32528180 DOI: 10.1038/s41586-020-2387-5] [Citation(s) in RCA: 119] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Accepted: 05/07/2020] [Indexed: 12/27/2022]
Abstract
The advent of endothermy, which is achieved through the continuous homeostatic regulation of body temperature and metabolism1,2, is a defining feature of mammalian and avian evolution. However, when challenged by food deprivation or harsh environmental conditions, many mammalian species initiate adaptive energy-conserving survival strategies-including torpor and hibernation-during which their body temperature decreases far below its homeostatic set-point3-5. How homeothermic mammals initiate and regulate these hypothermic states remains largely unknown. Here we show that entry into mouse torpor, a fasting-induced state with a greatly decreased metabolic rate and a body temperature as low as 20 °C6, is regulated by neurons in the medial and lateral preoptic area of the hypothalamus. We show that restimulation of neurons that were activated during a previous bout of torpor is sufficient to initiate the key features of torpor, even in mice that are not calorically restricted. Among these neurons we identify a population of glutamatergic Adcyap1-positive cells, the activity of which accurately determines when mice naturally initiate and exit torpor, and the inhibition of which disrupts the natural process of torpor entry, maintenance and arousal. Taken together, our results reveal a specific neuronal population in the mouse hypothalamus that serves as a core regulator of torpor. This work forms a basis for the future exploration of mechanisms and circuitry that regulate extreme hypothermic and hypometabolic states, and enables genetic access to monitor, initiate, manipulate and study these ancient adaptations of homeotherm biology.
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Affiliation(s)
- Sinisa Hrvatin
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA.
| | - Senmiao Sun
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA.,Program in Neuroscience, Harvard Medical School, Boston, MA, USA
| | - Oren F Wilcox
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Hanqi Yao
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | | | - Marcelo Cicconet
- Image and Data Analysis Core, Harvard Medical School, Boston, MA, USA
| | - Elena G Assad
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | | | | | - Alexander S Banks
- Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center, Boston, MA, USA
| | - Eric C Griffith
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
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29
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Marmol P, Krapacher F, Ibáñez CF. Control of brown adipose tissue adaptation to nutrient stress by the activin receptor ALK7. eLife 2020; 9:54721. [PMID: 32366358 PMCID: PMC7200161 DOI: 10.7554/elife.54721] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Accepted: 04/21/2020] [Indexed: 12/22/2022] Open
Abstract
Adaptation to nutrient availability is crucial for survival. Upon nutritional stress, such as during prolonged fasting or cold exposure, organisms need to balance the feeding of tissues and the maintenance of body temperature. The mechanisms that regulate the adaptation of brown adipose tissue (BAT), a key organ for non-shivering thermogenesis, to variations in nutritional state are not known. Here we report that specific deletion of the activin receptor ALK7 in BAT resulted in fasting-induced hypothermia due to exaggerated catabolic activity in brown adipocytes. After overnight fasting, BAT lacking ALK7 showed increased expression of genes responsive to nutrient stress, including the upstream regulator KLF15, aminoacid catabolizing enzymes, notably proline dehydrogenase (POX), and adipose triglyceride lipase (ATGL), as well as markedly reduced lipid droplet size. In agreement with this, ligand stimulation of ALK7 suppressed POX and KLF15 expression in both mouse and human brown adipocytes. Treatment of mutant mice with the glucocorticoid receptor antagonist RU486 restored KLF15 and POX expression levels in mutant BAT, suggesting that loss of BAT ALK7 results in excessive activation of glucocorticoid signaling upon fasting. These results reveal a novel signaling pathway downstream of ALK7 which regulates the adaptation of BAT to nutrient availability by limiting nutrient stress-induced overactivation of catabolic responses in brown adipocytes.
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Affiliation(s)
- Patricia Marmol
- Department of Neuroscience, Karolinska Institute, Stockholm, Sweden
| | - Favio Krapacher
- Department of Neuroscience, Karolinska Institute, Stockholm, Sweden
| | - Carlos F Ibáñez
- Department of Neuroscience, Karolinska Institute, Stockholm, Sweden.,Department of Physiology, National University of Singapore, Singapore, Singapore.,Life Sciences Institute, National University of Singapore, Singapore, Singapore.,Stellenbosch Institute for Advanced Study, Wallenberg Research Centre at Stellenbosch University, Stellenbosch, South Africa
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30
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Romano AB, Hunt A, Welbergen JA, Turbill C. Nocturnal torpor by superb fairy-wrens: a key mechanism for reducing winter daily energy expenditure. Biol Lett 2019; 15:20190211. [PMID: 31238856 DOI: 10.1098/rsbl.2019.0211] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Many passerine birds are small and require a high mass-specific rate of resting energy expenditure, especially in the cold. The energetics of thermoregulation is, therefore, an important aspect of their ecology, yet few studies have quantified thermoregulatory patterns in wild passerines. We used miniature telemetry to record the skin temperature ( Tskin) of free-living superb fairy-wrens ( Malurus cyaneus, 8.6 g; n = 6 birds over N = 7-22 days) and determine the importance of controlled reductions in body temperature during resting to their winter energy budgets. Fairy-wrens routinely exhibited large daily fluctuations in Tskin between maxima of 41.9 ± 0.6°C and minima of 30.4 ± 0.7°C, with overall individual minima of 27.4 ± 1.1°C (maximum daily range: 14.7 ± 0.9°C). These results provide strong evidence of nocturnal torpor in this small passerine, which we calculated to provide a 42% reduction in resting metabolic rate at a Ta of 5°C compared to active-phase Tskin. A capacity for energy-saving torpor has important consequences for understanding the behaviour and life-history ecology of superb fairy-wrens. Moreover, our novel field data suggest that torpor could be more widespread and important than previously thought within passerines, the most diverse order of birds.
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Affiliation(s)
- Alex B Romano
- 1 Hawkesbury Institute for the Environment, Western Sydney University , Richmond, New South Wales , Australia
| | - Anthony Hunt
- 2 Australian Bird Study Association , 16 Alderson Ave, North Rocks, New South Wales 2151 , Australia
| | - Justin A Welbergen
- 1 Hawkesbury Institute for the Environment, Western Sydney University , Richmond, New South Wales , Australia
| | - Christopher Turbill
- 1 Hawkesbury Institute for the Environment, Western Sydney University , Richmond, New South Wales , Australia
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31
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Endo T, Komatsuzaki A, Miyagawa Y, Kamoda T, Goto S, Koide K, Mizutani M. Thermographic assessment of facial temperature in patients undergoing orthognathic surgery. J Oral Sci 2019; 61:321-326. [PMID: 31217382 DOI: 10.2334/josnusd.18-0194] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
Abstract
This study was conducted to assess the usefulness of thermography for quantifying facial temperature before and after orthognathic surgery and intermaxillary fixation, and the effects of these orthognathic procedures on facial temperature. Facial thermograms of 10 patients who underwent bilateral sagittal split ramus osteotomy (SSRO, one-jaw group) and another 10 patients who underwent Le Fort I osteotomy and bilateral SSRO (two-jaw group) were taken 1 day before orthognathic surgery (T1) and at release of intermaxillary fixation 7 days later (T2). Two thermograms taken 30 s (TG1) and 3 min (TG2) after the start of recording at T1 and T2 were used. A square (26 × 26 pixels) was marked on each thermogram and the mean facial temperature for each square was measured. Three-way analysis of variance was used for statistical comparisons. Facial temperatures were significantly higher at T2 than at T1 on TG1 and TG2, and were significantly higher on TG2 than on TG1 at T1 and T2. The two-jaw group had a significantly higher facial temperature than the one-jaw group. Thermography was useful for quantitative assessment of facial temperature in patients undergoing orthognathic surgery. Changes in facial temperature were due predominantly to inflammation after surgery, rather than to sarcopenia.
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Affiliation(s)
- Toshiya Endo
- Department of Orthodontics and Dentofacial Orthopedics, Graduate School of Life Dentistry at Niigata, The Nippon Dental University
| | - Akira Komatsuzaki
- Department of Preventive and Community Dentistry, The Nippon Dental University School of Life Dentistry at Niigata
| | - Yukio Miyagawa
- Department of Dental Materials Science, The Nippon Dental University School of Life Dentistry at Niigata
| | - Takeshi Kamoda
- Department of Preventive and Community Dentistry, The Nippon Dental University School of Life Dentistry at Niigata
| | - Sho Goto
- Department of Orthodontics and Dentofacial Orthopedics, Graduate School of Life Dentistry at Niigata, The Nippon Dental University
| | - Katsunori Koide
- Department of Orthodontics and Dentofacial Orthopedics, Graduate School of Life Dentistry at Niigata, The Nippon Dental University
| | - Masutaka Mizutani
- Oral and Maxillofacial Surgery, The Nippon Dental University Niigata Hospital
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32
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Miyano CA, Orezzoli SF, Buck CL, Nishikawa KC. Severe thermoregulatory deficiencies in mice with a deletion in the titin gene TTN. ACTA ACUST UNITED AC 2019; 222:jeb.198564. [PMID: 31015287 DOI: 10.1242/jeb.198564] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 04/10/2019] [Indexed: 12/12/2022]
Abstract
Muscular dystrophy with myositis (mdm) mice carry a deletion in the N2A region of the gene for the muscle protein titin (TTN), shiver at low frequency, fail to maintain body temperatures (T b) at ambient temperatures (T a) <34°C, and have reduced body mass and active muscle stiffness in vivo compared with wild-type (WT) siblings. Impaired shivering thermogenesis (ST) could be due to the mutated titin protein causing more compliant muscles. We hypothesized that non-shivering thermogenesis (NST) is impaired. To characterize the response to cold exposure, we measured T b and metabolic rate (MR) of WT and mdm mice at four nominal temperatures: 20, 24, 29 and 34°C. Subsequently, we stimulated NST with noradrenaline. Manipulation of T a revealed an interaction between genotype and MR: mdm mice had higher MRs at 29°C and lower MRs at 24°C compared with WT mice. NST capacity was lower in mdm mice than in WT mice. Using MR data from a previous study, we compared MR of mdm mice with MR of Perognathus longimembris, a mouse species of similar body mass. Our results indicated low MR and reduced NST of mdm mice. These were more pronounced than differences between mdm and WT mice owing to body mass effects on MR and capacity for NST. Correcting MR using Q 10 showed that mdm mice had lower MRs than size-matched P. longimembris, indicating that mutated N2A titin causes severe thermoregulatory defects at all levels. Direct effects of the titin mutation lead to lower shivering frequency. Indirect effects likely lead to a lower capacity for NST and increased thermal conductance through decreased body size.
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Affiliation(s)
- Carissa A Miyano
- Center for Bioengineering Innovation, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Santiago F Orezzoli
- Center for Bioengineering Innovation, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - C Loren Buck
- Center for Bioengineering Innovation, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Kiisa C Nishikawa
- Center for Bioengineering Innovation, Northern Arizona University, Flagstaff, AZ 86011, USA
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33
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Turbill C, Körtner G, Geiser F. Roost use and thermoregulation by female Australian long-eared bats (Nyctophilus geoffroyi and N. gouldi) during pregnancy and lactation. AUST J ZOOL 2019. [DOI: 10.1071/zo20036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Small insectivorous bats commonly use torpor while day-roosting, even in summer. However, reproductive female bats are believed to benefit from avoiding torpor because a constant, elevated body temperature maximises the rate of offspring growth, which could increase offspring survival. We used temperature-sensitive radio-transmitters to locate roosts and document the thermal biology of pregnant and lactating females of Nyctophilus geoffroyi (9 g) and N. gouldi (11 g) at a woodland in a cool temperate climate. Unlike males, reproductive female Nyctophilus spp. roosted as small groups (<25) within insulated tree cavities. Roost switching occurred every 3.7 ± 1.5 (N. geoffroyi) or 1.7 ± 0.8 days (N. gouldi), and radio-tagged individuals roosted together and apart on different days. Skin temperature during roosting was most often between 32 and 36°C, and torpor was used infrequently. Male Nyctophilus have been shown in previous studies to use torpor daily during summer. These contrasting torpor patterns likely reflect the warmed cavities occupied by maternity colonies and the thermally unstable shallow crevices occupied by individual males. Our results support the hypothesis that availability of thermally suitable roosts will influence thermoregulatory patterns of reproductive females and hence the growth rates and survival of their offspring. Thus, it is important to conserve woodland habitat with trees in a range of decay stages to provide opportunities for selection and movement among roost trees by reproductive female bats.
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Hibernating astronauts-science or fiction? Pflugers Arch 2018; 471:819-828. [PMID: 30569200 PMCID: PMC6533228 DOI: 10.1007/s00424-018-2244-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 11/29/2018] [Accepted: 12/03/2018] [Indexed: 12/13/2022]
Abstract
For long-duration manned space missions to Mars and beyond, reduction of astronaut metabolism by torpor, the metabolic state during hibernation of animals, would be a game changer: Water and food intake could be reduced by up to 75% and thus reducing payload of the spacecraft. Metabolic rate reduction in natural torpor is linked to profound changes in biochemical processes, i.e., shift from glycolysis to lipolysis and ketone utilization, intensive but reversible alterations in organs like the brain and kidney, and in heart rate control via Ca2+. This state would prevent degenerative processes due to organ disuse and increase resistance against radiation defects. Neuro-endocrine factors have been identified as main targets to induce torpor although the exact mechanisms are not known yet. The widespread occurrence of torpor in mammals and examples of human hypometabolic states support the idea of human torpor and its beneficial applications in medicine and space exploration.
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Turbill C, Stojanovski L. Torpor reduces predation risk by compensating for the energetic cost of antipredator foraging behaviours. Proc Biol Sci 2018; 285:20182370. [PMID: 30963890 PMCID: PMC6304060 DOI: 10.1098/rspb.2018.2370] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2018] [Accepted: 11/27/2018] [Indexed: 11/12/2022] Open
Abstract
Foraging activity is needed for energy intake but increases the risk of predation, and antipredator behavioural responses, such as reduced activity, generally reduce energy intake. Hence, the mortality and indirect effects of predation risk are dependent on the energy requirements of prey. Torpor, a controlled reduction in resting metabolism and body temperature, is a common energy-saving mechanism of small mammals that enhances their resistance to starvation. Here we test the hypothesis that torpor could also reduce predation risk by compensating for the energetic cost of antipredator behaviours. We measured the foraging behaviour and body temperature of house mice in response to manipulation of perceived predation risk by adjusting levels of ground cover and starvation risk by 24 h food withdrawal every third day. We found that a voluntary reduction in daily food intake in response to lower cover (high predation risk) was matched by the extent of a daily reduction in body temperature. Our study provides the first experimental evidence of a close link between energy-saving torpor responses to starvation risk and behavioural responses to perceived predation risk. By reducing the risk of starvation, torpor can facilitate stronger antipredator behaviours. These results highlight the interplay between the capacity for reducing metabolic energy expenditure, optimal decisions about foraging behaviour and the life-history ecology of prey.
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Affiliation(s)
- Christopher Turbill
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, New South Wales, Australia
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Lo Martire V, Valli A, Bingaman MJ, Zoccoli G, Silvani A, Swoap SJ. Changes in blood glucose as a function of body temperature in laboratory mice: implications for daily torpor. Am J Physiol Endocrinol Metab 2018; 315:E662-E670. [PMID: 30040481 PMCID: PMC6230715 DOI: 10.1152/ajpendo.00201.2018] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Many small mammals, such as the laboratory mouse, utilize the hypometabolic state of torpor in response to caloric restriction. The signals that relay the lack of fuel to initiate a bout of torpor are not known. Because the mouse will only enter a torpid state when calorically challenged, it may be that one of the inputs for initiation into a bout of torpor is the lack of the primary fuel (glucose) used to power brain metabolism in the mouse. Using glucose telemetry in mice, we tested the hypotheses that 1) circulating glucose (GLC), core body temperature (Tb), and activity are significantly interrelated; and 2) that the level of GLC at the onset of torpor differs from both GLC during arousal from torpor and during feeding when there is no torpor. To test these hypotheses, six C57Bl/6J mice were implanted with glucose telemeters and exposed to different feeding conditions (ad libitum, fasting, limited food intake, and refeeding) to create different levels of GLC and Tb. We found a strong positive and linear correlation between GLC and Tb during ad libitum feeding. Furthermore, mice that were calorically restricted entered torpor bouts readily. GLC was low during torpor entry but did not drop precipitously as Tb did at the onset of a torpor bout. GLC significantly increased during arousal from torpor, indicating the presence of endogenous glucose production. While low GLC itself was not predictive of a bout of torpor, hyperactivity and low GLC preceded the onset of torpor, suggesting that this may be involved in triggering torpor.
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Affiliation(s)
- Viviana Lo Martire
- Department of Biomedical and Neuromotor Sciences, Alma Mater Studiorum-University of Bologna, Bologna , Italy
| | - Alice Valli
- Department of Biomedical and Neuromotor Sciences, Alma Mater Studiorum-University of Bologna, Bologna , Italy
| | - Mark J Bingaman
- Department of Biology, Williams College , Williamstown, Massachusetts
| | - Giovanna Zoccoli
- Department of Biomedical and Neuromotor Sciences, Alma Mater Studiorum-University of Bologna, Bologna , Italy
| | - Alessandro Silvani
- Department of Biomedical and Neuromotor Sciences, Alma Mater Studiorum-University of Bologna, Bologna , Italy
| | - Steven J Swoap
- Department of Biology, Williams College , Williamstown, Massachusetts
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Currie SE. No effect of season on the electrocardiogram of long-eared bats (Nyctophilus gouldi) during torpor. J Comp Physiol B 2018; 188:695-705. [PMID: 29623413 DOI: 10.1007/s00360-018-1158-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 03/27/2018] [Accepted: 04/01/2018] [Indexed: 01/23/2023]
Abstract
Heterothermic animals regularly undergo profound alterations of cardiac function associated with torpor. These animals have specialised tissues capable of withstanding fluctuations in body temperature > 30 °C without adverse effects. In particular, the hearts of heterotherms are able to resist fibrillation and discontinuity of the cardiac conduction system common in homeotherms during hypothermia. To investigate the patterns of cardiac conduction in small insectivorous bats which enter torpor year round, I simultaneously measured ECG and subcutaneous temperature (Tsub) of 21 Nyctophilus gouldi (11 g) during torpor at a range of ambient temperatures (Ta 1-28 °C). During torpor cardiac conduction slowed in a temperature dependent manner, primarily via prolongation along the atrioventricular pathway (PR interval). A close coupling of depolarisation and repolarisation was retained in torpid bats, with no isoelectric ST segment visible until animals reached Tsub <6 °C. There was little change in ventricular repolarisation (JT interval) with decreasing Tsub, or between rest and torpor at mild Ta. Bats retained a more rapid rate of ventricular conduction and repolarisation during torpor relative to other hibernators. Throughout all recordings across seasons (> 2500 h), there was no difference in ECG morphology or heart rate during torpor, and no manifestations of significant conduction blocks or ventricular tachyarrhythmias were observed. My results demonstrate the capacity of bat hearts to withstand extreme fluctuations in rate and temperature throughout the year without detrimental arrhythmogenesis. I suggest that this conduction reserve may be related to flight and the daily extremes in metabolism experienced by these animals, and warrants further investigation of cardiac electrophysiology in other flying hibernators.
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Affiliation(s)
- Shannon E Currie
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, NSW, 2351, Australia. .,Department of Zoology, Faculty of Life Sciences, Tel Aviv University, P.O. Box 39040, Tel Aviv, 6997801, Israel.
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Abstract
Mice subjected to cold or caloric deprivation can reduce body temperature and metabolic rate and enter a state of torpor. Here we show that administration of pyruvate, an energy-rich metabolic intermediate, can induce torpor in mice with diet-induced or genetic obesity. This is associated with marked hypothermia, decreased activity, and decreased metabolic rate. The drop in body temperature correlates with the degree of obesity and is blunted by housing mice at thermoneutrality. Induction of torpor by pyruvate in obese mice relies on adenosine signaling and is accompanied by changes in brain levels of hexose bisphosphate and GABA as detected by mass spectroscopy-based imaging. Pyruvate does not induce torpor in lean mice but results in the activation of brown adipose tissue (BAT) with an increase in the level of uncoupling protein-1 (UCP1). Denervation of BAT in lean mice blocks this increase in UCP1 and allows the pyruvate-induced torpor phenotype. Thus, pyruvate administration induces torpor in obese mice by pathways involving adenosine and GABA signaling and a failure of normal activation of BAT.
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Barak O, Geiser F, Kronfeld-Schor N. Flood-induced multiday torpor in golden spiny mice (Acomys russatus). AUST J ZOOL 2018. [DOI: 10.1071/zo19061] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Mammalian and avian torpor is widely viewed as an adaptation for survival of cold winters. However, in recent years it has been established that torpor can also be expressed in summer and that the functions of torpor are manyfold, including survival of adverse environmental events such as fires, storms, heat waves and droughts. Here we provide the first evidence on (1) torpor induction via an accidental flooding event in mammals (in captivity) and (2) expression of multiday torpor by spiny mice, lasting >7 times as long as usually observed for this desert rodent. Our data suggest yet another function of mammalian torpor, as a response to flood, in addition to many other adverse environmental events, and not just in response to cold.
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Seasonal energetics and torpor use in North American flying squirrels. J Therm Biol 2017; 70:46-53. [DOI: 10.1016/j.jtherbio.2017.10.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2017] [Revised: 10/04/2017] [Accepted: 10/21/2017] [Indexed: 11/18/2022]
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Nakipova OV, Averin AS, Evdokimovskii EV, Pimenov OY, Kosarski L, Ignat’ev D, Anufriev A, Kokoz YM, Reyes S, Terzic A, Alekseev AE. Store-operated Ca2+ entry supports contractile function in hearts of hibernators. PLoS One 2017; 12:e0177469. [PMID: 28531217 PMCID: PMC5439705 DOI: 10.1371/journal.pone.0177469] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 04/27/2017] [Indexed: 11/30/2022] Open
Abstract
Hibernators have a distinctive ability to adapt to seasonal changes of body temperature in a range between 37°C and near freezing, exhibiting, among other features, a unique reversibility of cardiac contractility. The adaptation of myocardial contractility in hibernation state relies on alterations of excitation contraction coupling, which becomes less-dependent from extracellular Ca2+ entry and is predominantly controlled by Ca2+ release from sarcoplasmic reticulum, replenished by the Ca2+-ATPase (SERCA). We found that the specific SERCA inhibitor cyclopiazonic acid (CPA), in contrast to its effect in papillary muscles (PM) from rat hearts, did not reduce but rather potentiated contractility of PM from hibernating ground squirrels (GS). In GS ventricles we identified drastically elevated, compared to rats, expression of Orai1, Stim1 and Trpc1/3/4/5/6/7 mRNAs, putative components of store operated Ca2+ channels (SOC). Trpc3 protein levels were found increased in winter compared to summer GS, yet levels of Trpc5, Trpc6 or Trpc7 remained unchanged. Under suppressed voltage-dependent K+, Na+ and Ca2+ currents, the SOC inhibitor 2-aminoethyl diphenylborinate (2-APB) diminished whole-cell membrane currents in isolated cardiomyocytes from hibernating GS, but not from rats. During cooling-reheating cycles (30°C–7°C–30°C) of ground squirrel PM, 2-APB did not affect typical CPA-sensitive elevation of contractile force at low temperatures, but precluded the contractility at 30°C before and after the cooling. Wash-out of 2-APB reversed PM contractility to control values. Thus, we suggest that SOC play a pivotal role in governing the ability of hibernator hearts to maintain their function during the transition in and out of hibernating states.
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Affiliation(s)
- Olga V. Nakipova
- Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
| | - Alexey S. Averin
- Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
| | - Edward V. Evdokimovskii
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Science, Pushchino, Moscow Region, Russia
| | - Oleg Yu. Pimenov
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Science, Pushchino, Moscow Region, Russia
| | - Leonid Kosarski
- Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
| | - Dmitriy Ignat’ev
- Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
| | - Andrey Anufriev
- Institute of Biology, Yakutsk Branch, Siberian Division, Russian Academy of Sciences, Yakutsk, Russia
| | - Yuri M. Kokoz
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Science, Pushchino, Moscow Region, Russia
| | - Santiago Reyes
- Division of Cardiovascular Diseases, Department of Molecular Pharmacology and Experimental Therapeutics, Stabile 5, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Andre Terzic
- Division of Cardiovascular Diseases, Department of Molecular Pharmacology and Experimental Therapeutics, Stabile 5, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Alexey E. Alekseev
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Science, Pushchino, Moscow Region, Russia
- Division of Cardiovascular Diseases, Department of Molecular Pharmacology and Experimental Therapeutics, Stabile 5, Mayo Clinic, Rochester, Minnesota, United States of America
- * E-mail:
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Central activation of the A 1 adenosine receptor in fed mice recapitulates only some of the attributes of daily torpor. J Comp Physiol B 2017; 187:835-845. [PMID: 28378088 DOI: 10.1007/s00360-017-1084-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Revised: 11/02/2016] [Accepted: 03/07/2017] [Indexed: 01/23/2023]
Abstract
Mice enter bouts of daily torpor, drastically reducing metabolic rate, core body temperature (T b), and heart rate (HR), in response to reduced caloric intake. Because central adenosine activation has been shown to induce a torpor-like state in the arctic ground squirrel, and blocking the adenosine-1 (A1) receptor prevents daily torpor, we hypothesized that central activation of the A1 adenosine receptors would induce a bout of natural torpor in mice. To test the hypothesis, mice were subjected to four different hypothermia bouts: natural torpor, forced hypothermia (FH), isoflurane-anesthesia, and an intracerebroventricular injection of the selective A1 receptor agonist N6-cyclohexyladenosine (CHA). All conditions induced profound hypothermia. T b fell more rapidly in the FH, isoflurane-anesthesia, and CHA conditions compared to torpor, while mice treated with CHA recovered at half the rate of torpid mice. FH, isoflurane-anesthesia, and CHA-treated mice exhibited a diminished drop in HR during entry into hypothermia as compared to torpor. Mice in all conditions except CHA shivered while recovering from hypothermia, and only FH mice shivered substantially while entering hypothermia. Circulating lactate during the hypothermic bouts was not significantly different between the CHA and torpor conditions, both of which had lower than baseline lactate levels. Arrhythmias were largely absent in the FH and isoflurane-anesthesia conditions, while skipped beats were observed in natural torpor and periodic extended (>1 s) HR pauses in the CHA condition. Lastly, the hypothermic bouts showed distinct patterns of gene expression, with torpor characterized by elevated hepatic and cardiac Txnip expression and all other hypothermic states characterized by elevated c-Fos and Egr-1 expression. We conclude that CHA-induced hypothermia and natural torpor are largely different physiological states.
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Wacker CB, McAllan BM, Körtner G, Geiser F. The role of basking in the development of endothermy and torpor in a marsupial. J Comp Physiol B 2017; 187:1029-1038. [PMID: 28283794 DOI: 10.1007/s00360-017-1060-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 01/02/2017] [Accepted: 01/18/2017] [Indexed: 10/20/2022]
Abstract
Marsupials have a slow rate of development and this allows a detailed examination of thermoregulatory developmental changes and stages. We quantified the cooling rates of marsupial dunnarts (Sminthopsis crassicaudata) at 40-56 days (d) old, and torpor and basking behaviour in animals given the option to bask in four age groups from 60 to 150 d. The development of thermoregulation was a continuum, but was characterised by three major thermoregulatory stages: (1) at 40 d, animals were unable to maintain a constant high body temperature during short-term cold exposure; (2) at 60 d, animals could maintain a high T b for the first part of the night at an ambient temperature of 15.0 ± 0.7 °C; later in the night, they entered an apparent torpor bout but could only rewarm passively when basking under a heat lamp; (3) from ~90 d, they expressed prolonged torpor bouts and were able to rewarm endogenously. Young newly weaned 60 d animals were able to avoid hypothermia by basking. In this case, basking was not an optional behavioural method of reducing the cost of rewarming from torpor, but was essential for thermoregulation independent of the nest temperature. Results from our study suggest that basking is a crucial behavioural trait that permits young marsupials and perhaps other juvenile altricial mammals to overcome the developmental stage between poikilothermy early in development and full endothermy later in life.
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Affiliation(s)
- Chris B Wacker
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, NSW, 2351, Australia.
| | - Bronwyn M McAllan
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, NSW, 2351, Australia.,Physiology, School of Medical Sciences, Bosch Institute, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Gerhard Körtner
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, NSW, 2351, Australia
| | - Fritz Geiser
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, NSW, 2351, Australia
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Ignat’ev DA, Andreeva LA, Amerkhanov ZG, Anufriev AI, Alekseev AE, Nakipova OV. The effect of insulin on the heart rate and temperature of the ground squirrel Spermofilus undulatus during arousal from hibernation. Biophysics (Nagoya-shi) 2017. [DOI: 10.1134/s0006350917010080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Swoap SJ, Körtner G, Geiser F. Heart rate dynamics in a marsupial hibernator. J Exp Biol 2017; 220:2939-2946. [DOI: 10.1242/jeb.155879] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Accepted: 05/30/2017] [Indexed: 11/20/2022]
Abstract
The eastern pygmy-possum (Cercartetus nanus) is a small marsupial that can express spontaneous short bouts of torpor, as well as multi-day bouts of deep hibernation. To examine heart rate (HR) control at various stages of torpor in a marsupial hibernator, and to see whether HR variability differs from deep placental hibernators, we used radiotelemetry to measure ECG and Tb while measuring the rate of O2 consumption and ventilation. The HR and rate of O2 consumption during euthermia was at its minimum (321±34 bpm, 0.705±0.048 ml O2/g*h) at an ambient temperature (Ta) of 31°C. HR had an inverse linear relationship with Ta to a maximum of 630±19 bpm at a Ta of 20°C. During entry into torpor at an Ta of 20°C, HR slowed primarily as a result of episodic periods of cardiac activity where electrical activity of the heart occurred in groups of 3 or 4 heart beats. When Tb was stable at 24°C in these torpor bouts, the episodic nature of HR had disappeared (i.e. no asystoles) with a rate of 34±3 bpm. For multi-day bouts of deep torpor, Ta was lowered to 6.6±0.8°C. During these deep bouts of torpor, Tb reached a minimum of 8.0±1.0°C, with a minimum HR of 8 bpm and a minimum rate of O2 consumption of 0.029±0.07 ml O2/g*h. Shivering bouts occurred in deep torpor about every 8 minutes, during which ventilation occurred, and HR was elevated to 40 bpm. The duration of the QRS complex increased from 12ms during euthermia to 69 ms at a Tb of 8°C. These findings demonstrate the dynamic functioning range of heart rate to be about 600 bpm (∼80 fold), one of the largest known ranges in mammals. Our study shows that despite a separation of ∼160 million years the control and function of the cardiac system seems indistinguishable in marsupial and placental hibernating mammals.
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Affiliation(s)
- Steven J. Swoap
- Department of Biology, Williams College, Williamstown, MA 01267, USA
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, Australia
| | - Gerhard Körtner
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, Australia
| | - Fritz Geiser
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, Australia
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Dausmann KH, Warnecke L. Primate Torpor Expression: Ghost of the Climatic Past. Physiology (Bethesda) 2016; 31:398-408. [DOI: 10.1152/physiol.00050.2015] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Torpor, the controlled depression of virtually all bodily function during scarce periods, was verified in primates under free-ranging conditions less than two decades ago. The large variety of different torpor patterns found both within and among closely related species is particularly remarkable. To help unravel the cause of these variable patterns, our review investigates primate torpor use within an evolutionary framework. First, we provide an overview of heterothermic primate species, focusing on the Malagasy lemurs, and discuss their use of daily torpor or hibernation in relation to habitat type and climatic conditions. Second, we investigate environmental characteristics that may have been involved in shaping the high variability of torpor expression found in lemurs today. Third, we examine potential triggers for torpor use in lemurs. We propose the “torpor refugia hypothesis” to illustrate how disparate primate torpor patterns possibly evolved in response to environmental cues during glacial periods, when animals were restricted to different refuge habitats along riverine corridors. For example, individuals enduring harsher conditions at higher altitudes likely developed seasonal hibernation, whereas those inhabiting lower elevation river catchments might have coped with unfavorable conditions by employing daily torpor. The ultimate stimuli triggering torpor use today likely differ between the different habitats of Madagascar. The broad diversity of torpor patterns in lemurs among closely related species, both within the same and in distinctly different habitat types, provides an ideal base for research into the stimuli for torpor use in endotherms in general. Our hypothesis highlights the importance of considering the environmental conditions under which ecosystems and species evolved when trying to explain physiological adaptations seen today.
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Affiliation(s)
- Kathrin H. Dausmann
- Zoological Institute, Functional Ecology, University Hamburg, Hamburg, Germany
| | - Lisa Warnecke
- Zoological Institute, Functional Ecology, University Hamburg, Hamburg, Germany
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Jansen HT, Leise T, Stenhouse G, Pigeon K, Kasworm W, Teisberg J, Radandt T, Dallmann R, Brown S, Robbins CT. The bear circadian clock doesn't 'sleep' during winter dormancy. Front Zool 2016; 13:42. [PMID: 27660641 PMCID: PMC5026772 DOI: 10.1186/s12983-016-0173-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 08/22/2016] [Indexed: 01/25/2023] Open
Abstract
Background Most biological functions are synchronized to the environmental light:dark cycle via a circadian timekeeping system. Bears exhibit shallow torpor combined with metabolic suppression during winter dormancy. We sought to confirm that free-running circadian rhythms of body temperature (Tb) and activity were expressed in torpid grizzly (brown) bears and that they were functionally responsive to environmental light. We also measured activity and ambient light exposures in denning wild bears to determine if rhythms were evident and what the photic conditions of their natural dens were. Lastly, we used cultured skin fibroblasts obtained from captive torpid bears to assess molecular clock operation in peripheral tissues. Circadian parameters were estimated using robust wavelet transforms and maximum entropy spectral analyses. Results Captive grizzly bears housed in constant darkness during winter dormancy expressed circadian rhythms of activity and Tb. The rhythm period of juvenile bears was significantly shorter than that of adult bears. However, the period of activity rhythms in adult captive bears was virtually identical to that of adult wild denning bears as was the strength of the activity rhythms. Similar to what has been found in other mammals, a single light exposure during the bear’s active period delayed subsequent activity onsets whereas these were advanced when light was applied during the bear’s inactive period. Lastly, in vitro studies confirmed the expression of molecular circadian rhythms with a period comparable to the bear’s own behavioral rhythms. Conclusions Based on these findings we conclude that the circadian system is functional in torpid bears and their peripheral tissues even when housed in constant darkness, is responsive to phase-shifting effects of light, and therefore, is a normal facet of torpid bear physiology. Electronic supplementary material The online version of this article (doi:10.1186/s12983-016-0173-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Heiko T Jansen
- Department of Integrative Physiology and Neuroscience, College of Veterinary Medicine, Washington State University, Mailstop 7620, Veterinary and Biomedical Research Bldg., Room 205, Pullman, WA 99164-7620 USA
| | - Tanya Leise
- Department of Mathematics and Statistics, Amherst College, Amherst, MA 01002 USA
| | | | - Karine Pigeon
- Foothills Research Institute, Hinton, AB T7V 1X6 Canada
| | | | | | | | - Robert Dallmann
- Institute for Pharmacology and Toxicology, University of Zürich, Zürich, 8057 Switzerland ; Present address: Warwick Medical School and Warwick Systems Biology Centre, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL UK
| | - Steven Brown
- Institute for Pharmacology and Toxicology, University of Zürich, Zürich, 8057 Switzerland
| | - Charles T Robbins
- School of the Environment, Washington State University, Pullman, WA 99164 USA
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Otto MS, Becker NI, Encarnação JA. Roost characteristics as indicators for heterothermic behavior of forest-dwelling bats. Ecol Res 2016. [DOI: 10.1007/s11284-016-1348-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Yan Q, Zhu X, Jiang L, Ye M, Sun L, Terblanche JS, Wu R. A computing platform to map ecological metabolism by integrating functional mapping and the metabolic theory of ecology. Brief Bioinform 2016; 18:137-144. [DOI: 10.1093/bib/bbv116] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Revised: 12/17/2015] [Indexed: 11/12/2022] Open
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Cubuk C, Bank JHH, Herwig A. The Chemistry of Cold: Mechanisms of Torpor Regulation in the Siberian Hamster. Physiology (Bethesda) 2016; 31:51-9. [DOI: 10.1152/physiol.00028.2015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Siberian hamsters use spontaneous daily torpor, a state of hypometabolism and hypothermia, to save energy during winter. Multiple neuroendocrine signals set the scene for spontaneous torpor to occur, and several brain areas have been identified as potential sites for torpor regulation. Here, we summarize the known mechanisms of a fascinating physiological state in the Siberian hamster.
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Affiliation(s)
- Ceyda Cubuk
- Biozentrum Grindel und Zoologisches Museum, Universität Hamburg, Hamburg, Germany
| | - Jonathan H. H. Bank
- Biozentrum Grindel und Zoologisches Museum, Universität Hamburg, Hamburg, Germany
| | - Annika Herwig
- Biozentrum Grindel und Zoologisches Museum, Universität Hamburg, Hamburg, Germany
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