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Colizzi FS, Martínez-Torres D, Helfrich-Förster C. The circadian and photoperiodic clock of the pea aphid. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2024; 210:627-639. [PMID: 37482577 PMCID: PMC11226554 DOI: 10.1007/s00359-023-01660-8] [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: 04/28/2023] [Revised: 07/13/2023] [Accepted: 07/14/2023] [Indexed: 07/25/2023]
Abstract
The pea aphid, Acyrthosiphon pisum, is a paradigmatic photoperiodic species that exhibits a remarkable annual life cycle, which is tightly coupled to the seasonal changes in day length. During spring and summer, characterised by longer days, aphid populations consist exclusively of viviparous females that reproduce parthenogenetically. When autumn comes and the days shorten, aphids switch their reproductive mode and generate males and oviparous sexual females, which mate and produce cold-resistant eggs that overwinter and survive the unfavourable season. While the photoperiodic responses have been well described, the nature of the timing mechanisms which underlie day length discrimination are still not completely understood. Experiments from the 1960's suggested that aphids rely on an 'hourglass' clock measuring the elapsed time during the dark night by accumulating a biochemical factor, which reaches a critical threshold at a certain night length and triggers the switch in reproduction mode. However, the photoperiodic responses of aphids can also be attributed to a strongly dampened circadian clock. Recent studies have uncovered the molecular components and the location of the circadian clock in the brain of the pea aphid and revealed that it is well connected to the neurohormonal system controlling aphid reproduction. We provide an overview of the putative mechanisms of photoperiodic control in aphids, from the photoreceptors involved in this process to the circadian clock and the neuroendocrine system.
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Affiliation(s)
- Francesca Sara Colizzi
- University of Würzburg, Neurobiology and Genetics, Biocenter, Am Hubland, 97074, Würzburg, Germany
| | - David Martínez-Torres
- Institut de Biologia Integrativa de Sistemes, Parc Cientific Universitat de València, C/ Catedrático José Beltrán nº 2, 46980, Paterna,, València, Spain
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2
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Meier SA, Furrer M, Nowak N, Zenobi R, Sundset MA, Huber R, Brown SA, Wagner G. Uncoupling of behavioral and metabolic 24-h rhythms in reindeer. Curr Biol 2024; 34:1596-1603.e4. [PMID: 38503287 DOI: 10.1016/j.cub.2024.02.072] [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: 09/08/2023] [Revised: 01/04/2024] [Accepted: 02/28/2024] [Indexed: 03/21/2024]
Abstract
Reindeer in the Arctic seasonally suppress daily circadian patterns of behavior present in most animals.1 In humans and mice, even when all daily behavioral and environmental influences are artificially suppressed, robust endogenous rhythms of metabolism governed by the circadian clock persist and are essential to health.2,3 Disrupted rhythms foster metabolic disorders and weight gain.4 To understand circadian metabolic organization in reindeer, we performed behavioral measurements and untargeted metabolomics from blood plasma samples taken from Eurasian tundra reindeer (Rangifer tarandus tarandus) across 24 h at 2-h intervals in four seasons. Our study confirmed the absence of circadian rhythms of behavior under constant darkness in the Arctic winter and constant daylight in the Arctic summer, as reported by others.1 We detected and measured the intensity of 893 metabolic features in all plasma samples using untargeted ultra-high-performance liquid chromatography-mass spectrometry (UPLC-MS). A core group of metabolites (66/893 metabolic features) consistently displayed 24-h rhythmicity. Most metabolites displayed a robust 24-h rhythm in winter and spring but were arrhythmic in summer and fall. Half of all measured metabolites displayed ultradian sleep-wake dependence in summer. Irrespective of the arrhythmic behavior, metabolism is rhythmic (24 h) in seasons of low food availability, potentially favoring energy efficiency. In seasons of food abundance, 24-h rhythmicity in metabolism is drastically reduced, again irrespective of behavioral rhythms, potentially fostering weight gain.
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Affiliation(s)
- Sara A Meier
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zurich, Switzerland
| | - Melanie Furrer
- Child Development Center and Children's Research Center, University Children's Hospital Zurich, University of Zurich, 8032 Zurich, Switzerland
| | - Nora Nowak
- Department of Chemistry and Applied Biosciences, Swiss National Technical University (ETH), 8093 Zurich, Switzerland
| | - Renato Zenobi
- Department of Chemistry and Applied Biosciences, Swiss National Technical University (ETH), 8093 Zurich, Switzerland
| | - Monica A Sundset
- Department of Arctic and Marine Biology, UiT The Arctic University of Norway, 9019 Tromsø, Norway
| | - Reto Huber
- Child Development Center and Children's Research Center, University Children's Hospital Zurich, University of Zurich, 8032 Zurich, Switzerland; Department of Child and Adolescent Psychiatry and Psychotherapy, Psychiatric Hospital Zurich, University of Zurich, 8032 Zurich, Switzerland.
| | - Steven A Brown
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zurich, Switzerland
| | - Gabriela Wagner
- Department of Arctic and Marine Biology, UiT The Arctic University of Norway, 9019 Tromsø, Norway; Division of Forest and Forest Resources, Norwegian Institute of Bioeconomy Research, 9016 Tromsø, Norway.
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3
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Furrer M, Meier SA, Jan M, Franken P, Sundset MA, Brown SA, Wagner GC, Huber R. Reindeer in the Arctic reduce sleep need during rumination. Curr Biol 2024; 34:427-433.e5. [PMID: 38141616 DOI: 10.1016/j.cub.2023.12.012] [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: 09/02/2023] [Revised: 11/24/2023] [Accepted: 12/06/2023] [Indexed: 12/25/2023]
Abstract
Timing and quantity of sleep depend on a circadian (∼24-h) rhythm and a specific sleep requirement.1 Sleep curtailment results in a homeostatic rebound of more and deeper sleep, the latter reflected in increased electroencephalographic (EEG) slow-wave activity (SWA) during non-rapid eye movement (NREM) sleep.2 Circadian rhythms are synchronized by the light-dark cycle but persist under constant conditions.3,4,5 Strikingly, arctic reindeer behavior is arrhythmic during the solstices.6 Moreover, the Arctic's extreme seasonal environmental changes cause large variations in overall activity and food intake.7 We hypothesized that the maintenance of optimal functioning under these extremely fluctuating conditions would require adaptations not only in daily activity patterns but also in the homeostatic regulation of sleep. We studied sleep using non-invasive EEG in four Eurasian tundra reindeer (Rangifer tarandus tarandus) in Tromsø, Norway (69°N) during the fall equinox and both solstices. As expected, sleep-wake rhythms paralleled daily activity distribution, and sleep deprivation resulted in a homeostatic rebound in all seasons. Yet, these sleep rebounds were smaller in summer and fall than in winter. Surprisingly, SWA decreased not only during NREM sleep but also during rumination. Quantitative modeling revealed that sleep pressure decayed at similar rates during the two behavioral states. Finally, reindeer spent less time in NREM sleep the more they ruminated. These results suggest that they can sleep during rumination. The ability to reduce sleep need during rumination-undisturbed phases for both sleep recovery and digestion-might allow for near-constant feeding in the arctic summer.
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Affiliation(s)
- Melanie Furrer
- Child Development Center and Children's Research Center, University Children's Hospital Zurich, University of Zurich, Steinwiesstrasse 75, 8032 Zurich, Switzerland
| | - Sara A Meier
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Maxime Jan
- Center for Integrative Genomics, University of Lausanne, Génopode building, 1015 Lausanne, Switzerland; Bioinformatics Competence Center, University of Lausanne, Génopode building, 1015 Lausanne, Switzerland
| | - Paul Franken
- Center for Integrative Genomics, University of Lausanne, Génopode building, 1015 Lausanne, Switzerland
| | - Monica A Sundset
- Department of Arctic and Marine Biology, UiT The Arctic University of Norway, Framstredet 39, 9019 Tromsø, Norway
| | - Steven A Brown
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Gabriela C Wagner
- Department of Arctic and Marine Biology, UiT The Arctic University of Norway, Framstredet 39, 9019 Tromsø, Norway; Division of Forest and Forest Resources, Norwegian Institute of Bioeconomy Research, Holtvegen 66, 9016 Tromsø, Norway.
| | - Reto Huber
- Child Development Center and Children's Research Center, University Children's Hospital Zurich, University of Zurich, Steinwiesstrasse 75, 8032 Zurich, Switzerland; Department of Child and Adolescent Psychiatry and Psychotherapy, Psychiatric Hospital Zurich, University of Zurich, Lenggstrasse 31, 8032 Zurich, Switzerland.
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4
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Hazlerigg DG, Appenroth D, Tomotani BM, West AC, Wood SH. Biological timekeeping in polar environments: lessons from terrestrial vertebrates. J Exp Biol 2023; 226:jeb246308. [PMID: 38031958 DOI: 10.1242/jeb.246308] [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] [Indexed: 12/01/2023]
Abstract
The polar regions receive less solar energy than anywhere else on Earth, with the greatest year-round variation in daily light exposure; this produces highly seasonal environments, with short summers and long, cold winters. Polar environments are also characterised by a reduced daily amplitude of solar illumination. This is obvious around the solstices, when the Sun remains continuously above (polar 'day') or below (polar 'night') the horizon. Even at the solstices, however, light levels and spectral composition vary on a diel basis. These features raise interesting questions about polar biological timekeeping from the perspectives of function and causal mechanism. Functionally, to what extent are evolutionary drivers for circadian timekeeping maintained in polar environments, and how does this depend on physiology and life history? Mechanistically, how does polar solar illumination affect core daily or seasonal timekeeping and light entrainment? In birds and mammals, answers to these questions diverge widely between species, depending on physiology and bioenergetic constraints. In the high Arctic, photic cues can maintain circadian synchrony in some species, even in the polar summer. Under these conditions, timer systems may be refined to exploit polar cues. In other instances, temporal organisation may cease to be dominated by the circadian clock. Although the drive for seasonal synchronisation is strong in polar species, reliance on innate long-term (circannual) timer mechanisms varies. This variation reflects differing year-round access to photic cues. Polar chronobiology is a productive area for exploring the adaptive evolution of daily and seasonal timekeeping, with many outstanding areas for further investigation.
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Affiliation(s)
- David G Hazlerigg
- Arctic Seasonal Timekeeping Initiative (ASTI), Arctic chronobiology and physiology research group, Department of Arctic and Marine Biology, UiT - The Arctic University of Norway, Tromsø NO-9037, Norway
| | - Daniel Appenroth
- Arctic Seasonal Timekeeping Initiative (ASTI), Arctic chronobiology and physiology research group, Department of Arctic and Marine Biology, UiT - The Arctic University of Norway, Tromsø NO-9037, Norway
| | - Barbara M Tomotani
- Arctic Seasonal Timekeeping Initiative (ASTI), Arctic chronobiology and physiology research group, Department of Arctic and Marine Biology, UiT - The Arctic University of Norway, Tromsø NO-9037, Norway
| | - Alexander C West
- Arctic Seasonal Timekeeping Initiative (ASTI), Arctic chronobiology and physiology research group, Department of Arctic and Marine Biology, UiT - The Arctic University of Norway, Tromsø NO-9037, Norway
| | - Shona H Wood
- Arctic Seasonal Timekeeping Initiative (ASTI), Arctic chronobiology and physiology research group, Department of Arctic and Marine Biology, UiT - The Arctic University of Norway, Tromsø NO-9037, Norway
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5
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Prunier J, Carrier A, Gilbert I, Poisson W, Albert V, Taillon J, Bourret V, Côté SD, Droit A, Robert C. CNVs with adaptive potential in Rangifer tarandus: genome architecture and new annotated assembly. Life Sci Alliance 2021; 5:5/3/e202101207. [PMID: 34911809 PMCID: PMC8711850 DOI: 10.26508/lsa.202101207] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 11/29/2021] [Accepted: 11/29/2021] [Indexed: 01/13/2023] Open
Abstract
Rangifer tarandus has experienced recent drastic population size reductions throughout its circumpolar distribution and preserving the species implies genetic diversity conservation. To facilitate genomic studies of the species populations, we improved the genome assembly by combining long read and linked read and obtained a new highly accurate and contiguous genome assembly made of 13,994 scaffolds (L90 = 131 scaffolds). Using de novo transcriptome assembly of RNA-sequencing reads and similarity with annotated human gene sequences, 17,394 robust gene models were identified. As copy number variations (CNVs) likely play a role in adaptation, we additionally investigated these variations among 20 genomes representing three caribou ecotypes (migratory, boreal and mountain). A total of 1,698 large CNVs (length > 1 kb) showing a genome distribution including hotspots were identified. 43 large CNVs were particularly distinctive of the migratory and sedentary ecotypes and included genes annotated for functions likely related to the expected adaptations. This work includes the first publicly available annotation of the caribou genome and the first assembly allowing genome architecture analyses, including the likely adaptive CNVs reported here.
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Affiliation(s)
- Julien Prunier
- Département de Médecine Moléculaire, Faculté de Médecine, Université Laval, Quebec City, Canada
| | - Alexandra Carrier
- Département des sciences animales, Faculté des Sciences de l'Agriculture et de l'Alimentation, Université Laval, Quebec City, Canada
| | - Isabelle Gilbert
- Département des sciences animales, Faculté des Sciences de l'Agriculture et de l'Alimentation, Université Laval, Quebec City, Canada
| | - William Poisson
- Département des sciences animales, Faculté des Sciences de l'Agriculture et de l'Alimentation, Université Laval, Quebec City, Canada
| | - Vicky Albert
- Ministère des Forêts, de la Faune et des Parcs du Québec, Quebec City, Canada
| | - Joëlle Taillon
- Ministère des Forêts, de la Faune et des Parcs du Québec, Quebec City, Canada
| | - Vincent Bourret
- Ministère des Forêts, de la Faune et des Parcs du Québec, Quebec City, Canada
| | - Steeve D Côté
- Caribou Ungava, département de biologie, Faculté des Sciences et de Génie, Université Laval, Quebec City, Canada
| | - Arnaud Droit
- Département de Médecine Moléculaire, Faculté de Médecine, Université Laval, Quebec City, Canada
| | - Claude Robert
- Département des sciences animales, Faculté des Sciences de l'Agriculture et de l'Alimentation, Université Laval, Quebec City, Canada
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6
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Contrasting dynamical responses of sympatric caribou and muskoxen to winter weather and earlier spring green-up in the Arctic. FOOD WEBS 2021. [DOI: 10.1016/j.fooweb.2021.e00196] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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7
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Yin D, Zhou R, Yin M, Chen Y, Xu S, Yang G. Gene duplication and loss of AANAT in mammals driven by rhythmic adaptations. Mol Biol Evol 2021; 38:3925-3937. [PMID: 33944919 PMCID: PMC8382898 DOI: 10.1093/molbev/msab125] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Arylalkylamine N-acetyltransferase (AANAT) plays a crucial role in synchronizing internal biological functions to circadian and circannual changes. Generally speaking, only one copy of AANAT gene has been found in mammals, however, three independent duplications of this gene were detected in several cetartiodactyl lineages (i.e., Suidae, Hippopotamidae, and Pecora), which originated in the middle Eocene, a geological period characterized with the increased climate seasonality. Lineage-specific expansions of AANAT and the associated functional enhancement in these lineages strongly suggest an improvement in regulating photoperiodic response to adapt to seasonal climate changes. In contrast, independent inactivating mutations or deletions of the AANAT locus were identified in the four pineal-deficient clades (cetaceans, sirenians, xenarthrans, and pangolins). Loss of AANAT function in cetaceans and sirenians could disrupt the sleep-promoting effects of pineal melatonin, which might contribute to increasing wakefulness, adapting these clades to underwater sleep. The absence of AANAT and pineal glands in xenarthrans and pangolins may be associated with their body temperature maintenance. The present work demonstrates a far more complex and intriguing evolutionary pattern and functional diversity of mammalian AANAT genes than previously thought and provides further evidence for understanding AANAT evolution as driven by rhythmic adaptations in mammals.
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Affiliation(s)
- Daiqing Yin
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - RuRu Zhou
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Mengxin Yin
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Yue Chen
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Shixia Xu
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Guang Yang
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
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8
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Appenroth D, Wagner GC, Hazlerigg DG, West AC. Evidence for circadian-based photoperiodic timekeeping in Svalbard ptarmigan, the northernmost resident bird. Curr Biol 2021; 31:2720-2727.e5. [PMID: 33930302 DOI: 10.1016/j.cub.2021.04.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 02/09/2021] [Accepted: 04/07/2021] [Indexed: 01/24/2023]
Abstract
The high Arctic archipelago of Svalbard (74°-81° north) experiences extended periods of uninterrupted daylight in summer and uninterrupted night in winter, apparently relaxing the major driver for the evolution of circadian rhythmicity. Svalbard ptarmigan (Lagopus muta hyperborea) is the only year-round resident terrestrial bird species endemic to the high Arctic and is remarkably adapted to the extreme annual variation in environmental conditions.1 Here, we demonstrate that, although circadian control of behavior disappears rapidly upon transfer to constant light conditions, consistent with the loss of daily activity patterns observed during the polar summer and polar night, Svalbard ptarmigans nonetheless employ a circadian-based mechanism for photoperiodic timekeeping. First, we show the persistence of rhythmic clock gene expression under constant light within the mediobasal hypothalamus and pars tuberalis, the key tissues in the seasonal neuroendocrine cascade. We then employ a "sliding skeleton photoperiod" protocol, revealing that the driving force behind seasonal biology of the Svalbard ptarmigan is rhythmic sensitivity to light, a feature that depends on a functioning circadian rhythm. Hence, the unusual selective pressures of life in the high Arctic have favored decoupling of the circadian clock from organization of daily activity patterns, while preserving its importance for seasonal synchronization.
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Affiliation(s)
- Daniel Appenroth
- Arctic Seasonal Timekeeping Initiative (ASTI), Department of Arctic and Marine Biology, UiT - The Arctic University of Norway, Framstredet 42, 9019 Tromsø, Norway
| | - Gabriela C Wagner
- Arctic Seasonal Timekeeping Initiative (ASTI), Department of Arctic and Marine Biology, UiT - The Arctic University of Norway, Framstredet 42, 9019 Tromsø, Norway; Divisjon for skog og utmark, NIBIO, Holtveien 66, 9016 Tromsø, Norway
| | - David G Hazlerigg
- Arctic Seasonal Timekeeping Initiative (ASTI), Department of Arctic and Marine Biology, UiT - The Arctic University of Norway, Framstredet 42, 9019 Tromsø, Norway.
| | - Alexander C West
- Arctic Seasonal Timekeeping Initiative (ASTI), Department of Arctic and Marine Biology, UiT - The Arctic University of Norway, Framstredet 42, 9019 Tromsø, Norway.
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9
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Huffeldt NP, Tigano A, Erikstad KE, Goymann W, Jenni-Eiermann S, Moum T, Reiertsen TK. The relationship between daily behavior, hormones, and a color dimorphism in a seabird under natural continuous light. Horm Behav 2021; 130:104930. [PMID: 33497708 DOI: 10.1016/j.yhbeh.2021.104930] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 11/19/2020] [Accepted: 01/04/2021] [Indexed: 11/18/2022]
Abstract
The predictable oscillation between the light of day and the dark of night across the diel cycle is a powerful selective force that has resulted in anticipatory mechanisms in nearly all taxa. At polar latitude, however, this oscillation becomes highly attenuated during the continuous light of polar day during summer. A general understanding of how animals keep time under these conditions is poorly understood. We tested the hypothesis that the common murre (a seabird, Uria aalge) can use melatonin and corticosterone, hormones associated with timekeeping, to track the diel cycle despite continuous light. We also tested the assumption that common murres breeding during polar summer schedule their colony attendance by time of day and sex, as they do at subpolar latitude. In the Atlantic population, common murres have a plumage color dimorphism associated with fitness-related traits, and we investigated the relationship of this dimorphism with colony attendance, melatonin, and corticosterone. The common murres did not schedule their attendance behavior by time of day or sex, yet they had higher concentrations of melatonin and, to a more limited extent, corticosterone during "night" than "day". Melatonin also linked to behavioral state. The two color morphs tended to have different colony-attendance behavior and melatonin concentrations, lending support for balancing selection maintaining the plumage dimorphism. In common murres, melatonin can signal time of day despite continuous light, and the limited diel variation of corticosterone contributes to the mounting evidence that polar-adapted birds and mammals require little or no diel variation in circulating glucocorticoids during polar day.
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Affiliation(s)
- Nicholas Per Huffeldt
- Greenland Institute of Natural Resources, 3900 Nuuk, Greenland; Arctic Ecosystem Ecology, Department of Bioscience, Aarhus University, 4000 Roskilde, Denmark; Department of Biology, Wake Forest University, Winston-Salem, NC 27109, USA.
| | - Anna Tigano
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, NH 03824, USA; Hubbard Center for Genome Studies, University of New Hampshire, Durham, NH 03824, USA
| | - Kjell Einar Erikstad
- Norwegian Institute for Nature Research, Fram Centre, 9296 Tromsø, Norway; Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Wolfgang Goymann
- Abteilung für Verhaltensneurobiologie, Max-Planck-Institut für Ornithologie, 82319 Seewiesen, Germany
| | | | - Truls Moum
- Genomics Division, Faculty of Bioscience and Aquaculture, Nord University, 8049 Bodø, Norway
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10
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Appenroth D, Nord A, Hazlerigg DG, Wagner GC. Body Temperature and Activity Rhythms Under Different Photoperiods in High Arctic Svalbard ptarmigan ( Lagopus muta hyperborea). Front Physiol 2021; 12:633866. [PMID: 33762966 PMCID: PMC7982588 DOI: 10.3389/fphys.2021.633866] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 02/15/2021] [Indexed: 01/11/2023] Open
Abstract
Organisms use circadian rhythms to anticipate and exploit daily environmental oscillations. While circadian rhythms are of clear importance for inhabitants of tropic and temperate latitudes, its role for permanent residents of the polar regions is less well understood. The high Arctic Svalbard ptarmigan shows behavioral rhythmicity in presence of light-dark cycles but is arrhythmic during the polar day and polar night. This has been suggested to be an adaptation to the unique light environment of the Arctic. In this study, we examined regulatory aspects of the circadian control system in the Svalbard ptarmigan by recording core body temperature (T b) alongside locomotor activity in captive birds under different photoperiods. We show that T b and activity are rhythmic with a 24-h period under short (SP; L:D 6:18) and long photoperiod (LP; L:D 16:8). Under constant light and constant darkness, rhythmicity in T b attenuates and activity shows signs of ultradian rhythmicity. Birds under SP also showed a rise in T b preceding the light-on signal and any rise in activity, which proves that the light-on signal can be anticipated, most likely by a circadian system.
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Affiliation(s)
- Daniel Appenroth
- Arctic Chronobiology and Physiology, Arctic and Marine Biology, UiT The Arctic University of Norway, Tromsø, Norway
| | - Andreas Nord
- Arctic Chronobiology and Physiology, Arctic and Marine Biology, UiT The Arctic University of Norway, Tromsø, Norway.,Section for Evolutionary Ecology, Department of Biology, Lund University, Lund, Sweden
| | - David G Hazlerigg
- Arctic Chronobiology and Physiology, Arctic and Marine Biology, UiT The Arctic University of Norway, Tromsø, Norway
| | - Gabriela C Wagner
- Arctic Chronobiology and Physiology, Arctic and Marine Biology, UiT The Arctic University of Norway, Tromsø, Norway.,Division of Forest and Forest Resources, Norwegian Institute of Bioeconomy Research (NIBIO), Tromsø, Norway
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11
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Reproduction of male reindeer (Rangifer tarandus). Anim Reprod Sci 2021; 227:106722. [PMID: 33621844 DOI: 10.1016/j.anireprosci.2021.106722] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 02/10/2021] [Accepted: 02/11/2021] [Indexed: 11/23/2022]
Abstract
The present review provides a comprehensive assessment on the basic aspects of the reproduction of the Rangifer male with a special focus on pubertal development, and the seasonal dynamics of gametogenesis, androgenesis, antler cycle and other physiological and behavioural characteristics of the rutting male. A greater understanding of the reproductive physiology of the males is needed to improve existing management strategies of semi-domestic stocks in the changing climate and to develop species-specific assisted reproductive technologies for improving the in situ and ex situ conservation programs to preserve endangered subspecies as well as to facilitate the transfer of genetic resources between fragmented wild or semi-domestic populations.
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12
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Weldenegodguad M, Pokharel K, Ming Y, Honkatukia M, Peippo J, Reilas T, Røed KH, Kantanen J. Genome sequence and comparative analysis of reindeer (Rangifer tarandus) in northern Eurasia. Sci Rep 2020; 10:8980. [PMID: 32488117 PMCID: PMC7265531 DOI: 10.1038/s41598-020-65487-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 05/05/2020] [Indexed: 12/24/2022] Open
Abstract
Reindeer are semi-domesticated ruminants that have adapted to the challenging northern Eurasian environment characterized by long winters and marked annual fluctuations in daylight. We explored the genetic makeup behind their unique characteristics by de novo sequencing the genome of a male reindeer and conducted gene family analyses with nine other mammalian species. We performed a population genomics study of 23 additional reindeer representing both domestic and wild populations and several ecotypes from various geographic locations. We assembled 2.66 Gb (N50 scaffold of 5 Mb) of the estimated 2.92 Gb reindeer genome, comprising 27,332 genes. The results from the demographic history analysis suggested marked changes in the effective population size of reindeer during the Pleistocene period. We detected 160 reindeer-specific and expanded genes, of which zinc finger proteins (n = 42) and olfactory receptors (n = 13) were the most abundant. Comparative genome analyses revealed several genes that may have promoted the adaptation of reindeer, such as those involved in recombination and speciation (PRDM9), vitamin D metabolism (TRPV5, TRPV6), retinal development (PRDM1, OPN4B), circadian rhythm (GRIA1), immunity (CXCR1, CXCR2, CXCR4, IFNW1), tolerance to cold-triggered pain (SCN11A) and antler development (SILT2). The majority of these characteristic reindeer genes have been reported for the first time here. Moreover, our population genomics analysis suggested at least two independent reindeer domestication events with genetic lineages originating from different refugial regions after the Last Glacial Maximum. Taken together, our study has provided new insights into the domestication, evolution and adaptation of reindeer and has promoted novel genomic research of reindeer.
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Affiliation(s)
- Melak Weldenegodguad
- Natural Resources Institute Finland, FI-31600, Jokioinen, Finland
- Department of Environmental and Biological Sciences, University of Eastern Finland, FI-70201, Kuopio, Finland
| | - Kisun Pokharel
- Natural Resources Institute Finland, FI-31600, Jokioinen, Finland
| | - Yao Ming
- BGI-Genomics, BGI-Shenzhen, Shenzhen, Guangdong, 518083, China
| | - Mervi Honkatukia
- Natural Resources Institute Finland, FI-31600, Jokioinen, Finland
- Nordic Genetic Resource Centre - NordGen, c/o NMBU - Biovit Box 5003, Ås, NO-1432, Norway
| | - Jaana Peippo
- Natural Resources Institute Finland, FI-31600, Jokioinen, Finland
| | - Tiina Reilas
- Natural Resources Institute Finland, FI-31600, Jokioinen, Finland
| | - Knut H Røed
- Department of Basic Sciences and Aquatic Medicine, Norwegian University of Life Sciences, P.O.Box 369 Centrum, 0102, Oslo, Norway
| | - Juha Kantanen
- Natural Resources Institute Finland, FI-31600, Jokioinen, Finland.
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13
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Lin Z, Chen L, Chen X, Zhong Y, Yang Y, Xia W, Liu C, Zhu W, Wang H, Yan B, Yang Y, Liu X, Sternang Kvie K, Røed KH, Wang K, Xiao W, Wei H, Li G, Heller R, Gilbert MTP, Qiu Q, Wang W, Li Z. Biological adaptations in the Arctic cervid, the reindeer ( Rangifer tarandus). Science 2020; 364:364/6446/eaav6312. [PMID: 31221829 DOI: 10.1126/science.aav6312] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Accepted: 05/16/2019] [Indexed: 12/23/2022]
Abstract
The reindeer is an Arctic species that exhibits distinctive biological characteristics, for which the underlying genetic basis remains largely unknown. We compared the genomes of reindeer against those of other ruminants and nonruminant mammals to reveal the genetic basis of light arrhythmicity, high vitamin D metabolic efficiency, the antler growth trait of females, and docility. We validate that two reindeer vitamin D metabolic genes (CYP27B1 and POR) show signs of positive selection and exhibit higher catalytic activity than those of other ruminants. A mutation upstream of the reindeer CCND1 gene endows an extra functional binding motif of the androgen receptor and thereby may result in female antlers. Furthermore, a mutation (proline-1172→threonine) in reindeer PER2 results in loss of binding ability with CRY1, which may explain circadian arrhythmicity in reindeer.
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Affiliation(s)
- Zeshan Lin
- Center for Ecological and Environmental Sciences, Northwestern Polytechnical University, Xi'an 710072, China
| | - Lei Chen
- Center for Ecological and Environmental Sciences, Northwestern Polytechnical University, Xi'an 710072, China
| | - Xianqing Chen
- Center for Ecological and Environmental Sciences, Northwestern Polytechnical University, Xi'an 710072, China
| | - Yingbin Zhong
- Center for Circadian Clocks, Soochow University, Suzhou 215123, China.,School of Biology and Basic Medical Sciences, Medical College, Soochow University, Suzhou 215123, China
| | - Yue Yang
- Center for Ecological and Environmental Sciences, Northwestern Polytechnical University, Xi'an 710072, China
| | - Wenhao Xia
- Center for Ecological and Environmental Sciences, Northwestern Polytechnical University, Xi'an 710072, China
| | - Chang Liu
- Center for Ecological and Environmental Sciences, Northwestern Polytechnical University, Xi'an 710072, China
| | - Wenbo Zhu
- Center for Ecological and Environmental Sciences, Northwestern Polytechnical University, Xi'an 710072, China
| | - Han Wang
- Center for Circadian Clocks, Soochow University, Suzhou 215123, China.,School of Biology and Basic Medical Sciences, Medical College, Soochow University, Suzhou 215123, China
| | - Biyao Yan
- Center for Ecological and Environmental Sciences, Northwestern Polytechnical University, Xi'an 710072, China
| | - Yifeng Yang
- Department of Special Animal Nutrition and Feed Science, Institute of Special Animal and Plant Sciences, Chinese Academy of Agricultural Sciences, Changchun 130112, China
| | - Xing Liu
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Kjersti Sternang Kvie
- Department of Basic Sciences and Aquatic Medicine, Norwegian University of Life Sciences, Oslo 0102, Norway
| | - Knut Håkon Røed
- Department of Basic Sciences and Aquatic Medicine, Norwegian University of Life Sciences, Oslo 0102, Norway
| | - Kun Wang
- Center for Ecological and Environmental Sciences, Northwestern Polytechnical University, Xi'an 710072, China
| | - Wuhan Xiao
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Haijun Wei
- Department of Special Animal Nutrition and Feed Science, Institute of Special Animal and Plant Sciences, Chinese Academy of Agricultural Sciences, Changchun 130112, China
| | - Guangyu Li
- Department of Special Animal Nutrition and Feed Science, Institute of Special Animal and Plant Sciences, Chinese Academy of Agricultural Sciences, Changchun 130112, China
| | - Rasmus Heller
- Section for Computational and RNA Biology, Department of Biology, University of Copenhagen, Copenhagen N 2200, Denmark
| | - M Thomas P Gilbert
- Section for Evolutionary Genomics, Department of Biology, University of Copenhagen, Copenhagen N 2200, Denmark.,Norwegian University of Science and Technology, University Museum, Trondheim 7491, Norway
| | - Qiang Qiu
- Center for Ecological and Environmental Sciences, Northwestern Polytechnical University, Xi'an 710072, China.
| | - Wen Wang
- Center for Ecological and Environmental Sciences, Northwestern Polytechnical University, Xi'an 710072, China. .,State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China.,Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming 650223, China
| | - Zhipeng Li
- Department of Special Animal Nutrition and Feed Science, Institute of Special Animal and Plant Sciences, Chinese Academy of Agricultural Sciences, Changchun 130112, China.
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14
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Phenotypic plasticity following weaning: winter body mass trends and food intake in relation to temperature by an arctic ungulate. Polar Biol 2020. [DOI: 10.1007/s00300-020-02623-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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15
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Abstract
Ruminants (Ruminantia) are among the most successful herbivorous mammals, exhibiting wide-ranging morphological and ecological characteristics (such as headgear and multichambered stomach) and including various key livestock species (e.g., cattle, buffalo, yak, sheep, and goat). Understanding their evolution is of great significance not only in scientific research but also in applications potential for human society. The rapid growth of genomic resources provides unprecedented opportunities to dissect the evolutionary histories and molecular mechanisms underlying the distinct characteristics of ruminants. Here we summarize our current understanding of the genetic, morphological, and ecological diversity of ruminants and provide prospects for future studies.
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Affiliation(s)
- Bao Wang
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming Yunnan 650223, China.,Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming Yunnan 650204, China
| | - Le Chen
- Center for Ecological and Environmental Sciences, Northwestern Polytechnical University, Xi'an Shaanxi 710072, China, E-mail:chen_
| | - Wen Wang
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming Yunnan 650223, China, E-mail:.,Center for Ecological and Environmental Sciences, Northwestern Polytechnical University, Xi'an Shaanxi 710072, China.,Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming Yunnan 650223, China
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16
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Bertolini E, Schubert FK, Zanini D, Sehadová H, Helfrich-Förster C, Menegazzi P. Life at High Latitudes Does Not Require Circadian Behavioral Rhythmicity under Constant Darkness. Curr Biol 2019; 29:3928-3936.e3. [PMID: 31679928 DOI: 10.1016/j.cub.2019.09.032] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Revised: 08/13/2019] [Accepted: 09/12/2019] [Indexed: 01/08/2023]
Abstract
Nearly all organisms evolved endogenous self-sustained timekeeping mechanisms to track and anticipate cyclic changes in the environment. Circadian clocks, with a periodicity of about 24 h, allow animals to adapt to day-night cycles. Biological clocks are highly adaptive, but strong behavioral rhythms might be a disadvantage for adaptation to weakly rhythmic environments such as polar areas [1, 2]. Several high-latitude species, including Drosophila species, were found to be highly arrhythmic under constant conditions [3-6]. Furthermore, Drosophila species from subarctic regions can extend evening activity until dusk under long days. These traits depend on the clock network neurochemistry, and we previously proposed that high-latitude Drosophila species evolved specific clock adaptations to colonize polar regions [5, 7, 8]. We broadened our analysis to 3 species of the Chymomyza genus, which diverged circa 5 million years before the Drosophila radiation [9] and colonized both low and high latitudes [10, 11]. C. costata, pararufithorax, and procnemis, independently of their latitude of origin, possess the clock neuronal network of low-latitude Drosophila species, and their locomotor activity does not track dusk under long photoperiods. Nevertheless, the high-latitude C. costata becomes arrhythmic under constant darkness (DD), whereas the two low-latitude species remain rhythmic. Different mechanisms are behind the arrhythmicity in DD of C. costata and the high-latitude Drosophila ezoana, suggesting that the ability to maintain behavioral rhythms has been lost more than once during drosophilids' evolution and that it might indeed be an evolutionary adaptation for life at high latitudes.
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Affiliation(s)
- Enrico Bertolini
- Neurobiology and Genetics, Theodor Boveri Institute, Biocentre, University of Würzburg, 97074 Würzburg, Germany
| | - Frank K Schubert
- Neurobiology and Genetics, Theodor Boveri Institute, Biocentre, University of Würzburg, 97074 Würzburg, Germany
| | - Damiano Zanini
- Neurobiology and Genetics, Theodor Boveri Institute, Biocentre, University of Würzburg, 97074 Würzburg, Germany
| | - Hana Sehadová
- Faculty of Science, Biology Centre of the Czech Academy of Sciences, Institute of Entomology and University of South Bohemia, 37005 Ceske Budejovice, Czech Republic
| | - Charlotte Helfrich-Förster
- Neurobiology and Genetics, Theodor Boveri Institute, Biocentre, University of Würzburg, 97074 Würzburg, Germany
| | - Pamela Menegazzi
- Neurobiology and Genetics, Theodor Boveri Institute, Biocentre, University of Würzburg, 97074 Würzburg, Germany.
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17
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Abstract
The evidence that diel patterns of physiology and behaviour in mammals are governed by circadian ‘clocks’ is based almost entirely on studies of nocturnal rodents. The emergent circadian paradigm, however, neglects the roles of energy metabolism and alimentary function (feeding and digestion) as determinants of activity pattern. The temporal control of activity varies widely across taxa, and ungulates, microtine rodents, and insectivores provide examples in which circadian timekeeping is vestigial. The nocturnal rodent/human paradigm of circadian organisation is unhelpful when considering the broader manifestation of activity patterns in mammals. The evidence that daily patterns of physiology and behaviour in mammals are governed by circadian ‘clocks’ is based almost entirely on studies of nocturnal rodents. This Essay proposes that the nocturnal rodent/human paradigm of circadian rhythms is unhelpful when considering the broader manifestation of temporal organisation of activity in mammals.
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18
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Dardente H, Wood S, Ebling F, Sáenz de Miera C. An integrative view of mammalian seasonal neuroendocrinology. J Neuroendocrinol 2019; 31:e12729. [PMID: 31059174 DOI: 10.1111/jne.12729] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 04/29/2019] [Accepted: 04/30/2019] [Indexed: 12/29/2022]
Abstract
Seasonal neuroendocrine cycles that govern annual changes in reproductive activity, energy metabolism and hair growth are almost ubiquitous in mammals that have evolved at temperate and polar latitudes. Changes in nocturnal melatonin secretion regulating gene expression in the pars tuberalis (PT) of the pituitary stalk are a critical common feature in seasonal mammals. The PT sends signal(s) to the pars distalis of the pituitary to regulate prolactin secretion and thus the annual moult cycle. The PT also signals in a retrograde manner via thyroid-stimulating hormone to tanycytes, which line the ventral wall of the third ventricle in the hypothalamus. Tanycytes show seasonal plasticity in gene expression and play a pivotal role in regulating local thyroid hormone (TH) availability. Within the mediobasal hypothalamus, the cellular and molecular targets of TH remain elusive. However, two populations of hypothalamic neurones, which produce the RF-amide neuropeptides kisspeptin and RFRP3 (RF-amide related peptide 3), are plausible relays between TH and the gonadotrophin-releasing hormone-pituitary-gonadal axis. By contrast, the ways by which TH also impinges on hypothalamic systems regulating energy intake and expenditure remain unknown. Here, we review the neuroendocrine underpinnings of seasonality and identify several areas that warrant further research.
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Affiliation(s)
- Hugues Dardente
- Physiologie de la Reproduction et des Comportements, INRA, CNRS, IFCE, Université de Tours, Nouzilly, France
| | - Shona Wood
- Department of Arctic and Marine Biology, The Arctic University of Norway, Tromsø, Norway
| | - Francis Ebling
- School of Life Sciences, University of Nottingham, Nottingham, UK
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19
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Murphy BA. Circadian and Circannual Regulation in the Horse: Internal Timing in an Elite Athlete. J Equine Vet Sci 2019; 76:14-24. [PMID: 31084748 DOI: 10.1016/j.jevs.2019.02.026] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Accepted: 02/25/2019] [Indexed: 12/20/2022]
Abstract
Biological rhythms evolved to provide temporal coordination across all tissues and organs and allow synchronization of physiology with predictable environmental cycles. Most important of these are circadian and circannual rhythms, primarily regulated via photoperiod signals from the retina. Understanding the nature of physiological rhythms in horses is crucially important for equine management. Predominantly, they have been removed from exposure to their natural environmental stimuli; the seasonally changing photoperiod, continuous foraging and feeding activity, social herd interactions, and the continuous low-intensity exercise of a grassland dweller. These have been replaced in many cases with confined indoor housing, regimental feeding and exercise times, social isolation, and exposure to lighting that is often erratic and does not come close to mimicking the spectral composition of sunlight. Man has further altered seasonal timing cues through the use of artificial lighting programs that impact reproductive behavior, breeding efficiency, and the development of youngstock. Understanding how these new environmental cues (some stronger and some weaker) impact the internal physiology of the horse in the context of the natural endogenous rhythms that evolved over millennia is key to helping to improve equine health, welfare, and performance, now and into the future. This review provides an overview of the field, highlights the recent discoveries related to biological timing in horses, and discusses the implications that these findings may have for the production and management of the elite equine athlete.
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Affiliation(s)
- Barbara A Murphy
- School of Agriculture and Food Science, University College Dublin, Dublin, Ireland.
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20
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West AC, Wood SH. Seasonal physiology: making the future a thing of the past. CURRENT OPINION IN PHYSIOLOGY 2018. [DOI: 10.1016/j.cophys.2018.04.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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21
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PELÁEZ M, SAN MIGUEL A, RODRÍGUEZ-VIGAL C, PEREA R. Climate, female traits and population features as drivers of breeding timing in Mediterranean red deer populations. Integr Zool 2017; 12:396-408. [DOI: 10.1111/1749-4877.12252] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Marta PELÁEZ
- Department of Natural Systems and Resources; Technical University of Madrid; Madrid Spain
| | - Alfonso SAN MIGUEL
- Department of Natural Systems and Resources; Technical University of Madrid; Madrid Spain
| | | | - Ramón PEREA
- Department of Natural Systems and Resources; Technical University of Madrid; Madrid Spain
- Department of Biology; Stanford University; Stanford California USA
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22
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Williams CT, Barnes BM, Yan L, Buck CL. Entraining to the polar day: circadian rhythms in arctic ground squirrels. ACTA ACUST UNITED AC 2017. [PMID: 28623226 DOI: 10.1242/jeb.159889] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Circadian systems are principally entrained to 24 h light-dark cycles, but this cue is seasonally absent in polar environments. Although some resident polar vertebrates have weak circadian clocks and are seasonally arrhythmic, the arctic ground squirrel (AGS) maintains daily rhythms of physiology and behavior throughout the summer, which includes 6 weeks of constant daylight. Here, we show that persistent daily rhythms in AGS are maintained through a circadian system that readily entrains to the polar day yet remains insensitive to entrainment by rapid light-dark transitions, which AGS generate naturally as a consequence of their semi-fossorial behavior. Additionally, AGS do not show 'jet lag', the slow realignment of circadian rhythms induced by the inertia of an intrinsically stable master circadian clock in the suprachiasmatic nucleus (SCN). We suggest this is due to the low expression of arginine vasopressin in the SCN of AGS, as vasopressin is associated with inter-neuronal coupling and robust rhythmicity.
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Affiliation(s)
- Cory T Williams
- Department of Biological Sciences and Center for Bioengineering Innovation, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Brian M Barnes
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
| | - Lily Yan
- Neuroscience Program, Michigan State University, East Lansing, MI 48824, USA
| | - C Loren Buck
- Department of Biological Sciences and Center for Bioengineering Innovation, Northern Arizona University, Flagstaff, AZ 86011, USA
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23
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Tyler NJC, Gregorini P, Forchhammer MC, Stokkan KA, van Oort BEH, Hazlerigg DG. Behavioral Timing without Clockwork: Photoperiod-Dependent Trade-Off between Predation Hazard and Energy Balance in an Arctic Ungulate. J Biol Rhythms 2016; 31:522-33. [PMID: 27634928 DOI: 10.1177/0748730416662778] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Occurrence of 24-h rhythms in species apparently lacking functional molecular clockwork indicates that strong circadian mechanisms are not essential prerequisites of robust timing, and that rhythmical patterns may arise instead as passive responses to periodically changing environmental stimuli. Thus, in a new synthesis of grazing in a ruminant (MINDY), crepuscular peaks of activity emerge from interactions between internal and external stimuli that influence motivation to feed, and the influence of the light/dark cycle is mediated through the effect of low nocturnal levels of food intake on gastric function. Drawing on risk allocation theory, we hypothesized that the timing of behavior in ruminants is influenced by the independent effects of light on motivation to feed and perceived risk of predation. We predicted that the antithetical relationship between these 2 drivers would vary with photoperiod, resulting in a systematic shift in the phase of activity relative to the solar cycle across the year. This prediction was formalized in a model in which phase of activity emerges from a photoperiod-dependent trade-off between food and safety. We tested this model using data on the temporal pattern of activity in reindeer/caribou Rangifer tarandus free-living at natural mountain pasture in sub-Arctic Norway. The resulting nonlinear relationship between the phasing of crepuscular activity and photoperiod, consistent with the model, suggests a mechanism for behavioral timing that is independent of the core circadian system. We anticipate that such timing depends on integration of metabolic feedback from the digestive system and the activity of the glucocorticoid axis which modulates the behavioral responses of the animal to environmental hazard. The hypothalamus is the obvious neural substrate to achieve this integration.
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Affiliation(s)
- Nicholas J C Tyler
- Centre for Saami Studies, UiT The Arctic University of Norway, Tromsø, Norway
| | | | - Mads C Forchhammer
- The University Centre in Svalbard (UNIS), Longyearbyen, Norway Center for Macroecology, Evolution and Climate (CMEC) and Greenland Perspective, Natural History Museum of Denmark, Copenhagen, Denmark
| | - Karl-Arne Stokkan
- Department of Arctic and Marine Biology, UiT The Arctic University of Norway, Tromsø, Norway
| | | | - David G Hazlerigg
- Department of Arctic and Marine Biology, UiT The Arctic University of Norway, Tromsø, Norway
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24
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Cribbet MR, Logan RW, Edwards MD, Hanlon E, Bien Peek C, Stubblefield JJ, Vasudevan S, Ritchey F, Frank E. Circadian rhythms and metabolism: from the brain to the gut and back again. Ann N Y Acad Sci 2016; 1385:21-40. [PMID: 27589593 PMCID: PMC5428740 DOI: 10.1111/nyas.13188] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 07/05/2016] [Indexed: 12/21/2022]
Abstract
This paper focuses on the relationship between the circadian system and glucose metabolism. Research across the translational spectrum confirms the importance of the circadian system for glucose metabolism and offers promising clues as to when and why these systems go awry. In particular, basic research has started to clarify the molecular and genetic mechanisms through which the circadian system regulates metabolism. The study of human behavior, especially in the context of psychiatric disorders, such as bipolar disorder and major depression, forces us to see how inextricably linked mental health and metabolic health are. We also emphasize the remarkable opportunities for advancing circadian science through big data and advanced analytics. Advances in circadian research have translated into environmental and pharmacological interventions with tremendous therapeutic potential.
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Affiliation(s)
- Matthew R Cribbet
- Western Psychiatric Institute and Clinic, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Ryan W Logan
- Western Psychiatric Institute and Clinic, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Mathew D Edwards
- Division of Neurobiology, Medical Research Council Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Erin Hanlon
- Department of Medicine, Division of Endocrinology, Metabolism and Molecular Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - Clara Bien Peek
- Department of Medicine, Division of Endocrinology, Metabolism and Molecular Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - Jeremy J Stubblefield
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, Texas
| | | | - Fiona Ritchey
- Western Psychiatric Institute and Clinic, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Ellen Frank
- Western Psychiatric Institute and Clinic, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
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25
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Beale AD, Whitmore D, Moran D. Life in a dark biosphere: a review of circadian physiology in "arrhythmic" environments. J Comp Physiol B 2016; 186:947-968. [PMID: 27263116 PMCID: PMC5090016 DOI: 10.1007/s00360-016-1000-6] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Revised: 05/05/2016] [Accepted: 05/17/2016] [Indexed: 11/25/2022]
Abstract
Most of the life with which humans interact is exposed to highly rhythmic and extremely predictable changes in illumination that occur with the daily events of sunrise and sunset. However, while the influence of the sun feels omnipotent to surface dwellers such as ourselves, life on earth is dominated, in terms of biomass, by organisms isolated from the direct effects of the sun. A limited understanding of what life is like away from the sun can be inferred from our knowledge of physiology and ecology in the light biosphere, but a full understanding can only be gained by studying animals from the dark biosphere, both in the laboratory and in their natural habitats. One of the least understood aspects of life in the dark biosphere is the rhythmicity of physiology and what it means to live in an environment of low or no rhythmicity. Here we describe methods that may be used to understand rhythmic physiology in the dark and summarise some of the studies of rhythmic physiology in "arrhythmic" environments, such as the poles, deep sea and caves. We review what can be understood about the adaptive value of rhythmic physiology on the Earth's surface from studies of animals from arrhythmic environments and what role a circadian clock may play in the dark.
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Affiliation(s)
- Andrew David Beale
- Department of Cell and Developmental Biology, Centre for Cell and Molecular Dynamics, University College London, 21 University Street, London, WC1E 6BT, UK.
| | - David Whitmore
- Department of Cell and Developmental Biology, Centre for Cell and Molecular Dynamics, University College London, 21 University Street, London, WC1E 6BT, UK
| | - Damian Moran
- Plant and Food Research, Seafood Technologies Group, Nelson, New Zealand.
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26
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Williams CT, Barnes BM, Buck CL. Persistence, Entrainment, and Function of Circadian Rhythms in Polar Vertebrates. Physiology (Bethesda) 2015; 30:86-96. [DOI: 10.1152/physiol.00045.2014] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Polar organisms must cope with an environment that periodically lacks the strongest time-giver, or zeitgeber, of circadian organization–robust, cyclical oscillations between light and darkness. We review the factors influencing the persistence of circadian rhythms in polar vertebrates when the light-dark cycle is absent, the likely mechanisms of entrainment that allow some polar vertebrates to remain synchronized with geophysical time, and the adaptive function of maintaining circadian rhythms in such environments.
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Affiliation(s)
- Cory T. Williams
- Department of Biological Sciences, University of Alaska Anchorage, Anchorage, Alaska; and
| | - Brian M. Barnes
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, Alaska
| | - C. Loren Buck
- Department of Biological Sciences, University of Alaska Anchorage, Anchorage, Alaska; and
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27
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Ensing EP, Ciuti S, de Wijs FALM, Lentferink DH, ten Hoedt A, Boyce MS, Hut RA. GPS based daily activity patterns in European red deer and North American elk (Cervus elaphus): indication for a weak circadian clock in ungulates. PLoS One 2014; 9:e106997. [PMID: 25208246 PMCID: PMC4160215 DOI: 10.1371/journal.pone.0106997] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Accepted: 05/28/2014] [Indexed: 11/29/2022] Open
Abstract
Long-term tracking using global positioning systems (GPS) is widely used to study vertebrate movement ecology, including fine-scale habitat selection as well as large-scale migrations. These data have the potential to provide much more information about the behavior and ecology of wild vertebrates: here we explore the potential of using GPS datasets to assess timing of activity in a chronobiological context. We compared two different populations of deer (Cervus elaphus), one in the Netherlands (red deer), the other in Canada (elk). GPS tracking data were used to calculate the speed of the animals as a measure for activity to deduce unbiased daily activity rhythms over prolonged periods of time. Speed proved a valid measure for activity, this being validated by comparing GPS based activity data with head movements recorded by activity sensors, and the use of GPS locations was effective for generating long term chronobiological data. Deer showed crepuscular activity rhythms with activity peaks at sunrise (the Netherlands) or after sunrise (Canada) and at the end of civil twilight at dusk. The deer in Canada were mostly diurnal while the deer in the Netherlands were mostly nocturnal. On an annual scale, Canadian deer were more active during the summer months while deer in the Netherlands were more active during winter. We suggest that these differences were mainly driven by human disturbance (on a daily scale) and local weather (on an annual scale). In both populations, the crepuscular activity peaks in the morning and evening showed a stable timing relative to dawn and dusk twilight throughout the year, but marked periods of daily a-rhythmicity occurred in the individual records. We suggest that this might indicate that (changes in) light levels around twilight elicit a direct behavioral response while the contribution of an internal circadian timing mechanism might be weak or even absent.
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Affiliation(s)
- Erik P. Ensing
- Chronobiology Unit, Centre for Behaviour and Neurosciences, University of Groningen, Groningen, the Netherlands
| | - Simone Ciuti
- Department of Biometry and Environmental System Analysis, University of Freiburg, Freiburg, Germany
- Department of Biological Sciences, University of Alberta, Edmonton, Canada
| | - Freek A. L. M. de Wijs
- Chronobiology Unit, Centre for Behaviour and Neurosciences, University of Groningen, Groningen, the Netherlands
| | - Dennis H. Lentferink
- Chronobiology Unit, Centre for Behaviour and Neurosciences, University of Groningen, Groningen, the Netherlands
| | - André ten Hoedt
- Natuurmonumenten, Eenheid Veluwezoom, Rheden, the Netherlands
| | - Mark S. Boyce
- Department of Biological Sciences, University of Alberta, Edmonton, Canada
| | - Roelof A. Hut
- Chronobiology Unit, Centre for Behaviour and Neurosciences, University of Groningen, Groningen, the Netherlands
- * E-mail:
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Wood S, Loudon A. Clocks for all seasons: unwinding the roles and mechanisms of circadian and interval timers in the hypothalamus and pituitary. J Endocrinol 2014; 222:R39-59. [PMID: 24891434 PMCID: PMC4104039 DOI: 10.1530/joe-14-0141] [Citation(s) in RCA: 114] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Adaptation to the environment is essential for survival, in all wild animal species seasonal variation in temperature and food availability needs to be anticipated. This has led to the evolution of deep-rooted physiological cycles, driven by internal clocks, which can track seasonal time with remarkable precision. Evidence has now accumulated that a seasonal change in thyroid hormone (TH) availability within the brain is a crucial element. This is mediated by local control of TH-metabolising enzymes within specialised ependymal cells lining the third ventricle of the hypothalamus. Within these cells, deiodinase type 2 enzyme is activated in response to summer day lengths, converting metabolically inactive thyroxine (T4) to tri-iodothyronine (T3). The availability of TH in the hypothalamus appears to be an important factor in driving the physiological changes that occur with season. Remarkably, in both birds and mammals, the pars tuberalis (PT) of the pituitary gland plays an essential role. A specialised endocrine thyrotroph cell (TSH-expressing) is regulated by the changing day-length signal, leading to activation of TSH by long days. This acts on adjacent TSH-receptors expressed in the hypothalamic ependymal cells, causing local regulation of deiodinase enzymes and conversion of TH to the metabolically active T3. In mammals, the PT is regulated by the nocturnal melatonin signal. Summer-like melatonin signals activate a PT-expressed clock-regulated transcription regulator (EYA3), which in turn drives the expression of the TSHβ sub-unit, leading to a sustained increase in TSH expression. In this manner, a local pituitary timer, driven by melatonin, initiates a cascade of molecular events, led by EYA3, which translates to seasonal changes of neuroendocrine activity in the hypothalamus. There are remarkable parallels between this PT circuit and the photoperiodic timing system used in plants, and while plants use different molecular signals (constans vs EYA3) it appears that widely divergent organisms probably obey a common set of design principles.
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Affiliation(s)
- Shona Wood
- Faculty of Life SciencesUniversity of Manchester, Manchester M13 9PT, UK
| | - Andrew Loudon
- Faculty of Life SciencesUniversity of Manchester, Manchester M13 9PT, UK
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Bloch G, Barnes BM, Gerkema MP, Helm B. Animal activity around the clock with no overt circadian rhythms: patterns, mechanisms and adaptive value. Proc Biol Sci 2013; 280:20130019. [PMID: 23825202 DOI: 10.1098/rspb.2013.0019] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Circadian rhythms are ubiquitous in many organisms. Animals that are forced to be active around the clock typically show reduced performance, health and survival. Nevertheless, we review evidence of animals showing prolonged intervals of activity with attenuated or nil overt circadian rhythms and no apparent ill effects. We show that around-the-clock and ultradian activity patterns are more common than is generally appreciated, particularly in herbivores, in animals inhabiting polar regions and habitats with constant physical environments, in animals during specific life-history stages (such as migration or reproduction), and in highly social animals. The underlying mechanisms are diverse, but studies suggest that some circadian pacemakers continue to measure time in animals active around the clock. The prevalence of around-the-clock activity in diverse animals and habitats, and an apparent diversity of underlying mechanisms, are consistent with convergent evolution. We suggest that the basic organizational principles of the circadian system and its complexity encompass the potential for chronobiological plasticity. There may be trade-offs between benefits of persistent daily rhythms versus plasticity, which for reasons still poorly understood make overt daily arrhythmicity functionally adaptive only in selected habitats and for selected lifestyles.
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Affiliation(s)
- Guy Bloch
- Department of Ecology, Evolution and Behavior, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
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Hope PR, Jones G. An entrained circadian cycle of peak activity in a population of hibernating bats. J Mammal 2013. [DOI: 10.1644/12-mamm-a-095.1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Piccione G, Giannetto C, Bertolucci C, Refinetti R. Daily rhythmicity of circulating melatonin is not endogenously generated in the horse. BIOL RHYTHM RES 2013. [DOI: 10.1080/09291016.2012.656245] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Abstract
Mammals have an endogenous timing system in the suprachiasmatic nuclei (SCN) of the hypothalamic region of the brain. This internal clock system is composed of an intracellular feedback loop that drives the expression of molecular components and their constitutive protein products to oscillate over a period of about 24 h (hence the term 'circadian'). These circadian oscillations bring about rhythmic changes in downstream molecular pathways and physiological processes such as those involved in nutrition and metabolism. It is now emerging that the molecular components of the clock system are also found within the cells of peripheral tissues, including the gastrointestinal tract, liver and pancreas. The present review examines their role in regulating nutritional and metabolic processes. In turn, metabolic status and feeding cycles are able to feed back onto the circadian clock in the SCN and in peripheral tissues. This feedback mechanism maintains the integrity and temporal coordination between various components of the circadian clock system. Thus, alterations in environmental cues could disrupt normal clock function, which may have profound effects on the health and well-being of an individual.
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Hut RA, Beersma DGM. Evolution of time-keeping mechanisms: early emergence and adaptation to photoperiod. Philos Trans R Soc Lond B Biol Sci 2011; 366:2141-54. [PMID: 21690131 PMCID: PMC3130368 DOI: 10.1098/rstb.2010.0409] [Citation(s) in RCA: 124] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Virtually all species have developed cellular oscillations and mechanisms that synchronize these cellular oscillations to environmental cycles. Such environmental cycles in biotic (e.g. food availability and predation risk) or abiotic (e.g. temperature and light) factors may occur on a daily, annual or tidal time scale. Internal timing mechanisms may facilitate behavioural or physiological adaptation to such changes in environmental conditions. These timing mechanisms commonly involve an internal molecular oscillator (a 'clock') that is synchronized ('entrained') to the environmental cycle by receptor mechanisms responding to relevant environmental signals ('Zeitgeber', i.e. German for time-giver). To understand the evolution of such timing mechanisms, we have to understand the mechanisms leading to selective advantage. Although major advances have been made in our understanding of the physiological and molecular mechanisms driving internal cycles (proximate questions), studies identifying mechanisms of natural selection on clock systems (ultimate questions) are rather limited. Here, we discuss the selective advantage of a circadian system and how its adaptation to day length variation may have a functional role in optimizing seasonal timing. We discuss various cases where selective advantages of circadian timing mechanisms have been shown and cases where temporarily loss of circadian timing may cause selective advantage. We suggest an explanation for why a circadian timing system has emerged in primitive life forms like cyanobacteria and we evaluate a possible molecular mechanism that enabled these bacteria to adapt to seasonal variation in day length. We further discuss how the role of the circadian system in photoperiodic time measurement may explain differential selection pressures on circadian period when species are exposed to changing climatic conditions (e.g. global warming) or when they expand their geographical range to different latitudes or altitudes.
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Affiliation(s)
- R A Hut
- University of Groningen, Chronobiology Research Unit, Life Science building, Nijenborgh 7, 9747AG Groningen, The Netherlands.
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Murphy BA, Martin AM, Furney P, Elliott JA. Absence of a serum melatonin rhythm under acutely extended darkness in the horse. J Circadian Rhythms 2011; 9:3. [PMID: 21569251 PMCID: PMC3103467 DOI: 10.1186/1740-3391-9-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2011] [Accepted: 05/10/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In contrast to studies showing gradual adaptation of melatonin (MT) rhythms to an advanced photoperiod in humans and rodents, we previously demonstrated that equine MT rhythms complete a 6-h light/dark (LD) phase advance on the first post-shift day. This suggested the possibility that melatonin secretion in the horse may be more strongly light-driven as opposed to endogenously rhythmic and light entrained. The present study investigates whether equine melatonin is endogenously rhythmic in extended darkness (DD). METHODS Six healthy, young mares were maintained in a lightproof barn under an LD cycle that mimicked the ambient natural photoperiod outside. Blood samples were collected at 2-h intervals for 48 consecutive h: 24-h in LD, followed by 24-h in extended dark (DD). Serum was harvested and stored at -20°C until melatonin and cortisol were measured by commercial RIA kits. RESULTS Two-way repeated measures ANOVA (n = 6/time point) revealed a significant circadian time (CT) x lighting condition interaction (p < .0001) for melatonin with levels non-rhythmic and consistently high during DD (CT 0-24). In contrast, cortisol displayed significant clock-time variation throughout LD and DD (p = .0009) with no CT x light treatment interaction (p = .4018). Cosinor analysis confirmed a significant 24-h temporal variation for melatonin in LD (p = .0002) that was absent in DD (p = .51), while there was an apparent circadian component in cortisol, which approached significance in LD (p = .076), and was highly significant in DD (p = .0059). CONCLUSIONS The present finding of no 24 h oscillation in melatonin in DD is the first evidence indicating that melatonin is not gated by a self-sustained circadian process in the horse. Melatonin is therefore not a suitable marker of circadian phase in this species. In conjunction with recent similar findings in reindeer, it appears that biosynthesis of melatonin in the pineal glands of some ungulates is strongly driven by the environmental light cycle with little input from the circadian oscillator known to reside in the SCN of the mammalian hypothalamus.
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Affiliation(s)
- Barbara A Murphy
- School of Agriculture, Food Science and Veterinary medicine, University College Dublin, Belfield, Dublin 4, Ireland.
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Lu W, Meng QJ, Tyler NJC, Stokkan KA, Loudon ASI. A circadian clock is not required in an arctic mammal. Curr Biol 2010; 20:533-7. [PMID: 20226667 DOI: 10.1016/j.cub.2010.01.042] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Revised: 01/14/2010] [Accepted: 01/15/2010] [Indexed: 01/05/2023]
Abstract
Seasonally breeding mammals use the annual change in the photoperiod cycle to drive rhythmic nocturnal melatonin signals from the pineal gland, providing a critical cue to time seasonal reproduction. Paradoxically, species resident at high latitudes achieve tight regulation of the temporal pattern of growth and reproduction despite the absence of photoperiodic information for most of the year. In this study, we show that the melatonin rhythm of reindeer (Rangifer tarandus) is acutely responsive to the light/dark cycle but not to circadian phase, and also that two key clock genes monitored in reindeer fibroblast cells display little, if any, circadian rhythmicity. The molecular clockwork that normally drives cellular circadian rhythms is evidently weak or even absent in this species, and instead, melatonin-mediated seasonal timing may be driven directly by photic information received at a limited time of year specific to the equinoxes.
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Affiliation(s)
- Weiqun Lu
- Faculty of Life Sciences, University of Manchester, Manchester M139PT, UK
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Bronson FH. Climate change and seasonal reproduction in mammals. Philos Trans R Soc Lond B Biol Sci 2010; 364:3331-40. [PMID: 19833645 DOI: 10.1098/rstb.2009.0140] [Citation(s) in RCA: 210] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Seasonal reproduction is common among mammals at all latitudes, even in the deep tropics. This paper (i) discusses the neuroendocrine pathways via which foraging conditions and predictive cues such as photoperiod enforce seasonality, (ii) considers the kinds of seasonal challenges mammals actually face in natural habitats, and (iii) uses the information thus generated to suggest how seasonal reproduction might be influenced by global climate change. Food availability and ambient temperature determine energy balance, and variation in energy balance is the ultimate cause of seasonal breeding in all mammals and the proximate cause in many. Photoperiodic cueing is common among long-lived mammals from the highest latitudes down to the mid-tropics. It is much less common in shorter lived mammals at all latitudes. An unknown predictive cue triggers reproduction in some desert and dry grassland species when it rains. The available information suggests that as our climate changes the small rodents of the world may adapt rather easily but the longer lived mammals whose reproduction is regulated by photoperiod may not do so well. A major gap in our knowledge concerns the tropics; that is where most species live and where we have the least understanding of how reproduction is regulated by environmental factors.
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Affiliation(s)
- F H Bronson
- Section of Integrative Biology, The University of Texas at Austin, Austin, TX, USA.
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Physiology and pharmacology of melatonin in relation to biological rhythms. Pharmacol Rep 2009; 61:383-410. [PMID: 19605939 DOI: 10.1016/s1734-1140(09)70081-7] [Citation(s) in RCA: 202] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2008] [Revised: 05/01/2009] [Indexed: 01/01/2023]
Abstract
Melatonin is an evolutionarily conserved molecule that serves a time-keeping function in various species. In vertebrates, melatonin is produced predominantly by the pineal gland with a marked circadian rhythm that is governed by the central circadian pacemaker (biological clock) in the suprachiasmatic nuclei of the hypothalamus. High levels of melatonin are normally found at night, and low levels are seen during daylight hours. As a consequence, melatonin has been called the "darkness hormone". This review surveys the current state of knowledge regarding the regulation of melatonin synthesis, receptor expression, and function. In particular, it addresses the physiological, pathological, and therapeutic aspects of melatonin in humans, with an emphasis on biological rhythms.
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