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Hutchinson AJ, Duffy BM, Rego LH, Staples JF. Paper towel shredding as a novel, affordable, noninvasive method for detecting arousals in hibernating rodents. Lab Anim (NY) 2024; 53:117-120. [PMID: 38637688 DOI: 10.1038/s41684-024-01362-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Accepted: 03/18/2024] [Indexed: 04/20/2024]
Abstract
Many research groups explore the regulation of hibernation or compare the physiology of heterothermic mammals between the torpid and aroused, euthermic states. Current methods for monitoring torpor (for example, infrared cameras, body temperature or heart-rate telemetry, and motion sensing) are costly, require specialized techniques, and can be invasive. Here we present an alternate method for determining torpor-bout duration that is cost-effective, noninvasive and accurate: paper towel shredding. In the winter, euthermic thirteen-lined ground squirrels will shred paper towels placed in the cage, but torpid animals will not. The presence of a shredded paper towel, indicating an arousal from torpor, is easily evaluated during routine daily monitoring. In 12 animals over 52 days, this simple technique detected 59 arousals with 100% accuracy when compared with the body temperature telemetry of the same animals. Moreover, this novel method avoids some of the drawbacks of other cheap monitoring systems such as the sawdust technique.
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Affiliation(s)
- Amalie J Hutchinson
- Department of Biology, The University of Western Ontario, London, Ontario, Canada.
| | - Brynne M Duffy
- Department of Biology, The University of Western Ontario, London, Ontario, Canada
| | - Lauren H Rego
- Department of Biology, The University of Western Ontario, London, Ontario, Canada
| | - James F Staples
- Department of Biology, The University of Western Ontario, London, Ontario, Canada
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2
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Scherman SJ, Risch TS, Rolland V. Fall and winter activity of two bat species in response to winter flooding and decreasing temperature. Glob Ecol Conserv 2022. [DOI: 10.1016/j.gecco.2022.e02276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022] Open
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3
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Temperature driven hibernation site use in the Western barbastelle Barbastella barbastellus (Schreber, 1774). Sci Rep 2021; 11:1464. [PMID: 33446821 PMCID: PMC7809113 DOI: 10.1038/s41598-020-80720-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Accepted: 12/24/2020] [Indexed: 12/12/2022] Open
Abstract
In temperate regions, winter is characterized by cold temperatures and low food availability. Heterothermic animals can bridge this period by entering a state of torpor characterized by decreased body temperature and reduced metabolic rate. Hibernation site choice is crucial since temperature conditions in the hibernaculum will impact torpor. We analysed temperature-dependent hibernation site use of Barbastella barbastellus. Bats and temperature were monitored in an underground system (1999–2019) and standalone bunkers (2007–2019) in Western Poland. During the winter of 2017–2018 we analysed the thermal variability of the hibernacula. Seasonal variation is higher in bunkers and thus temperatures get colder in winter than in the underground system. On the other hand, short-term variability (thermal variability index) in the bunkers was lower than in the underground system. This makes bunkers a more stable environment to hibernate for cold dwelling bats in warm winters, when temperatures in the bunkers do not get below freezing. Bats use both the warm underground system and the colder bunkers. During the last decade, a continuous series of warm winters occurred and the population of barbastelle bats partly moved from the underground system to the bunkers. These present temperature increases broadened the range of potential hibernation sites for barbastelles. Our study indicates that long-term trends, seasonal variation and short-term variability in temperatures are all important and should be analysed to investigate hibernaculum use by bats. Our study shows that small hibernation sites may become more important in the future.
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4
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Bevelacqua JJ, Welsh J, Mortazavi SMJ. On the immunological limitations of hibernation and synthetic torpor as a supporting technique for astronauts’ radioprotection in deep space missions. World J Immunol 2019; 9:1-4. [DOI: 10.5411/wji.v9.i1.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2019] [Revised: 11/29/2019] [Accepted: 12/14/2019] [Indexed: 02/05/2023] Open
Abstract
Although human hibernation has been introduced as an effective technique in space exploration, there are concerns regarding the intrinsic risks of the approach (i.e., synthetic torpor) and other factors involved in this procedure. Besides concerns about the brain changes and the state of consciousness during hibernation, an "Achilles heel" of the hibernation is the negative impact of torpor on factors such as the number of circulating leukocytes, complement levels, response to lipopolysaccharides, phagocytotic capacity, cytokine production, lymphocyte proliferation, and antibody production. Moreover, increased virulence of bacteria in deep space can significantly increase the risk of infection. The increased infection risk during long-term space missions with the combined effects of radiation and microgravity affect the astronauts’ immune system. With these additional immune system stressors, torpor-induced extra-immunosuppression can be potentially life threatening for astronauts.
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Affiliation(s)
| | - James Welsh
- Department of Radiation Oncology, Loyola Stritch School of Medicine, Hines VA Hospital Chicago, Chicago, IL 60153, United States
| | - Seyed Mohammad Javad Mortazavi
- Shiraz University of Medical Sciences, Shiraz 7134845794, Iran
- Department of Diagnostic Imaging, Fox Chase Cancer Center, Philadelphia, PA 19111, United States
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5
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Poo S, Hinkson KM, Stege E. Sperm output and body condition are maintained independently of hibernation in an endangered temperate amphibian. Reprod Fertil Dev 2019; 31:796-804. [PMID: 30514432 DOI: 10.1071/rd18073] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Accepted: 11/13/2018] [Indexed: 11/23/2022] Open
Abstract
Hibernation is an integral part of the life history of species living in seasonal environments. However, our knowledge about the link between hibernation and reproductive success in amphibians remains limited, which poses an obstacle for critical conservation efforts. To fill this gap, we quantified the effects of captive hibernation on sperm quality, sperm quantity and body condition in an endangered anuran, the Wyoming toad (Anaxyrus baxteri), and used naturally hibernated wild toads as a standard for comparison. We hypothesised that hibernation is essential for optimal sperm output but is detrimental to body condition. Sperm collection was performed using assisted reproductive technologies for both captive and wild toads. Contrary to our hypotheses, no differences were observed in sperm metrics (total number of cells, concentration, motility and viability) or in body condition across captive treatment groups (0, 30 or 60 days of hibernation). Moreover, no difference was found between sperm metrics of captive toads and wild toads. These unexpected findings suggest that hibernation may not be an essential process for spermiation in A. baxteri while using exogenous hormones, and illustrate the potential of temperate amphibians to adapt to varying environmental conditions during winter months.
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Affiliation(s)
- Sinlan Poo
- Department of Research and Conservation, Memphis Zoo, 2000 Prentiss Place, Memphis, TN 38112, USA
| | - Kristin M Hinkson
- Department of Research and Conservation, Memphis Zoo, 2000 Prentiss Place, Memphis, TN 38112, USA
| | - Edward Stege
- US Fish and Wildlife Services, Leadville National Fish Hatchery, 2846 Highway 300, Leadville, CO 80461, USA
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6
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Borowiec BG, McClelland GB, Rees BB, Scott GR. Distinct metabolic adjustments arise from acclimation to constant hypoxia and intermittent hypoxia in estuarine killifish (Fundulus heteroclitus). J Exp Biol 2018; 221:221/23/jeb190900. [DOI: 10.1242/jeb.190900] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 10/16/2018] [Indexed: 12/15/2022]
Abstract
ABSTRACT
Many fish experience daily cycles of hypoxia in the wild, but the physiological strategies for coping with intermittent hypoxia are poorly understood. We examined how killifish adjust O2 supply and demand during acute hypoxia, and how these responses are altered after prolonged acclimation to constant or intermittent patterns of hypoxia exposure. We acclimated killifish to normoxia (∼20 kPa O2), constant hypoxia (2 kPa) or intermittent cycles of nocturnal hypoxia (12 h:12 h normoxia:hypoxia) for 28 days, and then compared whole-animal O2 consumption rates (ṀO2) and tissue metabolites during exposure to 12 h of hypoxia followed by reoxygenation in normoxia. Normoxia-acclimated fish experienced a pronounced 27% drop in ṀO2 during acute hypoxia, and modestly increased ṀO2 upon reoxygenation. They strongly recruited anaerobic metabolism during acute hypoxia, indicated by lactate accumulation in plasma, muscle, liver, brain, heart and digestive tract, as well as a transient drop in intracellular pH, and they increased hypoxia inducible factor (HIF)-1α protein abundance in muscle. Glycogen, glucose and glucose-6-phosphate levels suggested that glycogen supported brain metabolism in hypoxia, while the muscle used circulating glucose. Acclimation to constant hypoxia caused a stable ∼50% decrease in ṀO2 that persisted after reoxygenation, with minimal recruitment of anaerobic metabolism, suggestive of metabolic depression. By contrast, fish acclimated to intermittent hypoxia maintained sufficient O2 transport to support normoxic ṀO2, modestly recruited lactate metabolism and increased ṀO2 dramatically upon reoxygenation. Both groups of hypoxia-acclimated fish had similar glycogen, ATP, intracellular pH and HIF-1α levels as normoxic controls. We conclude that different patterns of hypoxia exposure favour distinct strategies for matching O2 supply and O2 demand.
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Affiliation(s)
| | - Grant B. McClelland
- Department of Biology, McMaster University, Hamilton, Ontario, Canada, L8S 4K1
| | - Bernard B. Rees
- Department of Biological Sciences, University of New Orleans, New Orleans, LA 70148, USA
| | - Graham R. Scott
- Department of Biology, McMaster University, Hamilton, Ontario, Canada, L8S 4K1
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7
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Mandic M, Regan MD. Can variation among hypoxic environments explain why different fish species use different hypoxic survival strategies? ACTA ACUST UNITED AC 2018; 221:221/21/jeb161349. [PMID: 30381477 DOI: 10.1242/jeb.161349] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
In aquatic environments, hypoxia is a multi-dimensional stressor that can vary in O2 level (partial pressure of O2 in water, PwO2 ), rate of induction and duration. Natural hypoxic environments can therefore be very different from one another. For the many fish species that have evolved to cope with these different hypoxic environments, survival requires adjusting energy supply and demand pathways to maintain energy balance. The literature describes innumerable ways that fishes combine aerobic metabolism, anaerobic metabolism and metabolic rate depression (MRD) to accomplish this, but it is unknown whether the evolutionary paths leading to these different strategies are determined primarily by species' phylogenetic histories, genetic constraint or their native hypoxic environments. We explored this idea by devising a four-quadrant matrix that bins different aquatic hypoxic environments according to their duration and PwO2 characteristics. We then systematically mined the literature for well-studied species native to environments within each quadrant, and, for each of 10 case studies, described the species' total hypoxic response (THR), defined as its hypoxia-induced combination of sustained aerobic metabolism, enhanced anaerobic metabolism and MRD, encompassing also the mechanisms underlying these metabolic modes. Our analysis revealed that fishes use a wide range of THRs, but that distantly related species from environments within the same matrix quadrant have converged on similar THRs. For example, environments of moderately hypoxic PwO2 favoured predominantly aerobic THRs, whereas environments of severely hypoxic PwO2 favoured MRD. Capacity for aerial emergence as well as predation pressure (aquatic and aerial) also contributed to these responses, in addition to other biotic and abiotic factors. Generally, it appears that the particular type of hypoxia experienced by a fish plays a major role in shaping its particular THR.
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Affiliation(s)
- Milica Mandic
- Department of Biology, University of Ottawa, Ottawa, ON, Canada, K1N 6N5
| | - Matthew D Regan
- Comparative Biosciences Department, University of Wisconsin-Madison, Madison, WI 35706, USA
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8
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Field KA, Sewall BJ, Prokkola JM, Turner GG, Gagnon MF, Lilley TM, Paul White J, Johnson JS, Hauer CL, Reeder DM. Effect of torpor on host transcriptomic responses to a fungal pathogen in hibernating bats. Mol Ecol 2018; 27:3727-3743. [PMID: 30080945 DOI: 10.1111/mec.14827] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 07/25/2018] [Accepted: 07/28/2018] [Indexed: 01/07/2023]
Abstract
Hibernation, the use of prolonged torpor to depress metabolism, is employed by mammals to conserve resources during extended periods of extreme temperatures and/or resource limitation. Mammalian hibernators arouse to euthermy periodically during torpor for reasons that are not well understood, and these arousals may facilitate immune processes. To determine whether arousals enable host responses to pathogens, we used dual RNA-Seq and a paired sampling approach to examine gene expression in a hibernating bat, the little brown myotis (Myotis lucifugus). During torpor, transcript levels differed in only a few genes between uninfected wing tissue and adjacent tissue infected with Pseudogymnoascus destructans, the fungal pathogen that causes white-nose syndrome. Within 70-80 min after emergence from torpor, large changes in gene expression were observed due to local infection, particularly in genes involved in pro-inflammatory host responses to fungal pathogens, but also in many genes involved in immune responses and metabolism. These results support the hypothesis that torpor is a period of relative immune dormancy and arousals allow for local immune responses in infected tissues during hibernation. Host-pathogen interactions were also found to regulate gene expression in the pathogen differently depending on the torpor state of the host. Hibernating species must balance the benefits of energy and water conservation achieved during torpor with the costs of decreased immune competence. Interbout arousals allow hibernators to optimize these, and other, trade-offs during prolonged hibernation by enabling host responses to pathogens within brief, periodic episodes of euthermy.
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Affiliation(s)
- Kenneth A Field
- Department of Biology, Bucknell University, Lewisburg, Pennsylvania
| | - Brent J Sewall
- Department of Biology, Temple University, Philadelphia, Pennsylvania
| | - Jenni M Prokkola
- Department of Biology, Bucknell University, Lewisburg, Pennsylvania
| | - Gregory G Turner
- Wildlife Diversity Division, Pennsylvania Game Commission, Harrisburg, Pennsylvania
| | - Marianne F Gagnon
- Department of Biology, Temple University, Philadelphia, Pennsylvania
| | - Thomas M Lilley
- Department of Biology, Bucknell University, Lewisburg, Pennsylvania
| | - J Paul White
- Wisconsin Department of Natural Resources, Madison, Wisconsin
| | - Joseph S Johnson
- Department of Biology, Bucknell University, Lewisburg, Pennsylvania
| | | | - DeeAnn M Reeder
- Department of Biology, Bucknell University, Lewisburg, Pennsylvania
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9
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Reynolds DS, Shoemaker K, Oettingen SV, Najjar S. High Rates of Winter Activity and Arousals in Two New England Bat Species: Implications for a Reduced White-Nose Syndrome Impact? Northeast Nat (Steuben) 2017. [DOI: 10.1656/045.024.s720] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- D. Scott Reynolds
- St. Paul's School, Concord, NH 03301
- North East Ecological Services, Concord, NH 03301
| | - Kevin Shoemaker
- Natural Resources and Environmental Science, University of Nevada, Reno, NV 89557
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10
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Klüg-Baerwald B, Gower L, Lausen C, Brigham R. Environmental correlates and energetics of winter flight by bats in southern Alberta, Canada. CAN J ZOOL 2016. [DOI: 10.1139/cjz-2016-0055] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Winter activity of bats is common, yet poorly understood. Other studies suggest a relationship between winter activity and ambient temperature, particularly temperature at sunset. We recorded echolocation calls to determine correlates of hourly bat activity in Dinosaur Provincial Park, Alberta, Canada. We documented bat activity in temperatures as low as −10.4 °C. We observed big brown bats (Eptesicus fuscus (Palisot de Beauvois, 1796)) flying at colder temperatures than species of Myotis bats (genus Myotis Kaup, 1829). We show that temperature and wind are important predictors of winter activity by E. fuscus and Myotis, and that Myotis may also use changes in barometric pressure to cue activity. In the absence of foraging opportunity, we suggest these environmental factors relate to heat loss and thus the energetic cost of flight. To understand the energetic consequences of bat flight in cold temperatures, we estimated energy expenditure during winter flights of E. fuscus and little brown myotis (Myotis lucifugus (Le Conte, 1831)) using species-specific parameters. We estimated that winter flight uses considerable fat stores and that flight thermogenesis could mitigate energetic costs by 20% or more. We also show that temperature-dependent interspecific differences in winter activity likely stem from differences between species in heat loss and potential for activity–thermoregulatory heat substitution.
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Affiliation(s)
- B.J. Klüg-Baerwald
- Department of Biology, University of Regina, 3737 Wascana Parkway, Regina, SK S4S 0A2, Canada
| | - L.E. Gower
- School of Biosciences, Sir Martin Evans Building, Cardiff University, Museum Avenue, Cardiff CF10 3AX, United Kingdom
| | - C.L. Lausen
- Wildlife Conservation Society Canada, P.O. Box 606, Kaslo, BC V0G 1M0, Canada
| | - R.M. Brigham
- Department of Biology, University of Regina, 3737 Wascana Parkway, Regina, SK S4S 0A2, Canada
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11
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Postawa T, Nagy Z. Variation of parasitism patterns in bats during hibernation: the effect of host species, resources, health status, and hibernation period. Parasitol Res 2016; 115:3767-78. [PMID: 27240839 PMCID: PMC5040749 DOI: 10.1007/s00436-016-5138-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Accepted: 05/17/2016] [Indexed: 02/01/2023]
Abstract
During critical periods of food shortage or variable climatic conditions, the choice of an appropriate host can increase the survival and reproductive performance of parasites. In turn, one of the unique adaptations to periodical food shortages is hibernation, which is often found among insectivorous bat species in the temperate zone. While hibernating, bats are completely defenseless against both predators and ectoparasites, their immune and endocrine systems are diminished, and survival is dependent on the accumulated fat reserves. Differences in the health status or in the rate of consumption of the resources might also explain species-specific differences in ectoparasite abundance, especially between closely related host species, such as the greater mouse-eared bat (Myotis myotis) and the lesser mouse-eared bat (M. blythii) during hibernation. In the present study, the abundance of two ecologically distinct (summer and winter) types of ectoparasites was examined in terms of its influence on the body condition and hemoglobin content of the two host species. The effects of demographic factors, such as host sex and age, were also investigated. Despite a similar pattern of deteriorating body condition and hemoglobin concentration, M. myotis was more parasitized than was M. blythii. The marked decrease in hemoglobin content in first-year females of both host species correlated with the highest parasite load and indicated a risk of anemia. At the intraspecific level, ectoparasite abundance was not correlated with body condition (resources), but it negatively affected hemoglobin content; however, this mostly concerned M. blythii, which had a lower parasite load. Therefore, it can be concluded that interspecific differences in ectoparasite abundance may result from parasites selecting the host species that is less sensitive to their activity. In turn, in summer ectoparasites, the preference for female hosts is probably attributable to the likelihood of reinfection rather than to an effect of host resources or health status. The absence of sex-based preferences in winter ectoparasites could be explained by equal host availability.
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Affiliation(s)
- Tomasz Postawa
- Institute of Systematics and Evolution of Animals, Polish Academy of Sciences, Sławkowska 17, 31-016, Kraków, Poland.
| | - Zoltan Nagy
- Foundation for School, Densusianu Str. 6/A, 400428, Cluj-Napoca, Romania
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12
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Cooper ST, Sell SS, Fahrenkrog M, Wilkinson K, Howard DR, Bergen H, Cruz E, Cash SE, Andrews MT, Hampton M. Effects of hibernation on bone marrow transcriptome in thirteen-lined ground squirrels. Physiol Genomics 2016; 48:513-25. [PMID: 27207617 DOI: 10.1152/physiolgenomics.00120.2015] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 05/17/2016] [Indexed: 12/17/2022] Open
Abstract
Mammalian hibernators adapt to prolonged periods of immobility, hypometabolism, hypothermia, and oxidative stress, each capable of reducing bone marrow activity. In this study bone marrow transcriptomes were compared among thirteen-lined ground squirrels collected in July, winter torpor, and winter interbout arousal (IBA). The results were consistent with a suppression of acquired immune responses, and a shift to innate immune responses during hibernation through higher complement expression. Consistent with the increase in adipocytes found in bone marrow of hibernators, expression of genes associated with white adipose tissue are higher during hibernation. Genes that should strengthen the bone by increasing extracellular matrix were higher during hibernation, especially the collagen genes. Finally, expression of heat shock proteins were lower, and cold-response genes were higher, during hibernation. No differential expression of hematopoietic genes involved in erythrocyte or megakaryocyte production was observed. This global view of the changes in the bone marrow transcriptome over both short term (torpor vs. IBA) and long term (torpor vs. July) hypothermia can explain several observations made about circulating blood cells and the structure and strength of the bone during hibernation.
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Affiliation(s)
- Scott T Cooper
- Biology Department, University of Wisconsin-La Crosse, La Crosse, Wisconsin;
| | - Shawn S Sell
- Biology Department, University of Wisconsin-La Crosse, La Crosse, Wisconsin
| | - Molly Fahrenkrog
- Biology Department, University of Wisconsin-La Crosse, La Crosse, Wisconsin
| | - Kory Wilkinson
- Biology Department, University of Wisconsin-La Crosse, La Crosse, Wisconsin
| | - David R Howard
- Biology Department, University of Wisconsin-La Crosse, La Crosse, Wisconsin
| | - Hannah Bergen
- Biology Department, University of Wisconsin-La Crosse, La Crosse, Wisconsin
| | - Estefania Cruz
- Biology Department, University of Wisconsin-La Crosse, La Crosse, Wisconsin
| | - Steve E Cash
- Hematology/Oncology, Gundersen Lutheran Medical Foundation, La Crosse, Wisconsin
| | - Matthew T Andrews
- Department of Biology, University of Minnesota-Duluth, Duluth, Minnesota; and
| | - Marshall Hampton
- Department of Mathematics and Statistics, University of Minnesota-Duluth, Duluth, Minnesota
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13
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Regan MD, Gill I, Richards JG. Calorespirometry reveals that goldfish prioritize aerobic metabolism over metabolic rate depression in all but near-anoxic environments. J Exp Biol 2016; 220:564-572. [DOI: 10.1242/jeb.145169] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Accepted: 11/21/2016] [Indexed: 10/20/2022]
Abstract
Metabolic rate depression (MRD) has long been proposed as the key metabolic strategy of hypoxic survival, but surprisingly the effects of changes in hypoxic O2 tensions (PwO2) on MRD are largely unexplored. We simultaneously measured the O2 consumption rate (ṀO2) and metabolic heat of goldfish using calorespirometry to test the hypothesis that MRD is employed at hypoxic PwO2s and initiated just below Pcrit, the PwO2 below which ṀO2 is forced to progressively decline as the fish oxyconforms to decreasing PwO2. Specifically, we used closed-chamber and flow-through calorespirometry together with terminal sampling experiments to examine the effects of PwO2 and time on ṀO2, metabolic heat and anaerobic metabolism (lactate and ethanol production). The closed-chamber and flow-through experiments yielded slightly different results. Under closed-chamber conditions with a continually decreasing PwO2, goldfish showed a Pcrit of 3.0±0.3 kPa and metabolic heat production was only depressed at PwO2 between 0 and 0.67 kPa. Under flow-through conditions with PwO2 held at a variety of oxygen tensions for 1 and 4 h, goldfish also initiated MRD between 0 and 0.67 kPa but maintained ṀO2 to 0.67 kPa, indicating that Pcrit is at or below this PwO2. Anaerobic metabolism was strongly activated at PwO2 ≤1.3 kPa, but only used within the first hour at 1.3 and 0.67 kPa as anaerobic end-products did not accumulate between 1 and 4 h exposure. Taken together, it appears that goldfish reserve MRD for near-anoxia, supporting routine metabolic rate at sub-Pcrit PwO2s with the help of anaerobic glycolysis in the closed-chamber experiments, and aerobically after an initial (<1 h) activation of anaerobic metabolism in the flow-through experiments, even at 0.67 kPa PwO2.
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Affiliation(s)
- Matthew D. Regan
- Department of Zoology, University of British Columbia, 6270 University Blvd., Vancouver, BC V6T 1Z4, Canada
| | - Ivan Gill
- Department of Zoology, University of British Columbia, 6270 University Blvd., Vancouver, BC V6T 1Z4, Canada
| | - Jeffrey G. Richards
- Department of Zoology, University of British Columbia, 6270 University Blvd., Vancouver, BC V6T 1Z4, Canada
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14
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Ruf T, Geiser F. Daily torpor and hibernation in birds and mammals. Biol Rev Camb Philos Soc 2015; 90:891-926. [PMID: 25123049 PMCID: PMC4351926 DOI: 10.1111/brv.12137] [Citation(s) in RCA: 484] [Impact Index Per Article: 53.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Revised: 07/16/2014] [Accepted: 07/16/2014] [Indexed: 12/11/2022]
Abstract
Many birds and mammals drastically reduce their energy expenditure during times of cold exposure, food shortage, or drought, by temporarily abandoning euthermia, i.e. the maintenance of high body temperatures. Traditionally, two different types of heterothermy, i.e. hypometabolic states associated with low body temperature (torpor), have been distinguished: daily torpor, which lasts less than 24 h and is accompanied by continued foraging, versus hibernation, with torpor bouts lasting consecutive days to several weeks in animals that usually do not forage but rely on energy stores, either food caches or body energy reserves. This classification of torpor types has been challenged, suggesting that these phenotypes may merely represent extremes in a continuum of traits. Here, we investigate whether variables of torpor in 214 species (43 birds and 171 mammals) form a continuum or a bimodal distribution. We use Gaussian-mixture cluster analysis as well as phylogenetically informed regressions to quantitatively assess the distinction between hibernation and daily torpor and to evaluate the impact of body mass and geographical distribution of species on torpor traits. Cluster analysis clearly confirmed the classical distinction between daily torpor and hibernation. Overall, heterothermic endotherms tend to be small; hibernators are significantly heavier than daily heterotherms and also are distributed at higher average latitudes (∼35°) than daily heterotherms (∼25°). Variables of torpor for an average 30 g heterotherm differed significantly between daily heterotherms and hibernators. Average maximum torpor bout duration was >30-fold longer, and mean torpor bout duration >25-fold longer in hibernators. Mean minimum body temperature differed by ∼13°C, and the mean minimum torpor metabolic rate was ∼35% of the basal metabolic rate (BMR) in daily heterotherms but only 6% of BMR in hibernators. Consequently, our analysis strongly supports the view that hibernators and daily heterotherms are functionally distinct groups that probably have been subject to disruptive selection. Arguably, the primary physiological difference between daily torpor and hibernation, which leads to a variety of derived further distinct characteristics, is the temporal control of entry into and arousal from torpor, which is governed by the circadian clock in daily heterotherms, but apparently not in hibernators.
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Affiliation(s)
- Thomas Ruf
- Department of Integrative Biology and Evolution, Research Institute of Wildlife Ecology, University of Veterinary Medicine, Vienna, Savoyenstraße 1, A-1160 Vienna, Austria
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, New South Wales 2351, Australia
| | - Fritz Geiser
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, New South Wales 2351, Australia
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Johnson JS, Reeder DM, Lilley TM, Czirják GÁ, Voigt CC, McMichael JW, Meierhofer MB, Seery CW, Lumadue SS, Altmann AJ, Toro MO, Field KA. Antibodies to Pseudogymnoascus destructans are not sufficient for protection against white-nose syndrome. Ecol Evol 2015; 5:2203-14. [PMID: 26078857 PMCID: PMC4461422 DOI: 10.1002/ece3.1502] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 03/22/2015] [Indexed: 12/12/2022] Open
Abstract
White-nose syndrome (WNS) is a fungal disease caused by Pseudogymnoascus destructans (Pd) that affects bats during hibernation. Although millions of bats have died from WNS in North America, mass mortality has not been observed among European bats infected by the fungus, leading to the suggestion that bats in Europe are immune. We tested the hypothesis that an antibody-mediated immune response can provide protection against WNS by quantifying antibodies reactive to Pd in blood samples from seven species of free-ranging bats in North America and two free-ranging species in Europe. We also quantified antibodies in blood samples from little brown myotis (Myotis lucifugus) that were part of a captive colony that we injected with live Pd spores mixed with adjuvant, as well as individuals surviving a captive Pd infection trial. Seroprevalence of antibodies against Pd, as well as antibody titers, was greater among little brown myotis than among four other species of cave-hibernating bats in North America, including species with markedly lower WNS mortality rates. Among little brown myotis, the greatest titers occurred in populations occupying regions with longer histories of WNS, where bats lacked secondary symptoms of WNS. We detected antibodies cross-reactive with Pd among little brown myotis naïve to the fungus. We observed high titers among captive little brown myotis injected with Pd. We did not detect antibodies against Pd in Pd-infected European bats during winter, and titers during the active season were lower than among little brown myotis. These results show that antibody-mediated immunity cannot explain survival of European bats infected with Pd and that little brown myotis respond differently to Pd than species with higher WNS survival rates. Although it appears that some species of bats in North America may be developing resistance to WNS, an antibody-mediated immune response does not provide an explanation for these remnant populations.
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Affiliation(s)
- Joseph S Johnson
- Department of Biology, Bucknell University Lewisburg, Pennsylvania, 17837
| | - DeeAnn M Reeder
- Department of Biology, Bucknell University Lewisburg, Pennsylvania, 17837
| | | | - Gábor Á Czirják
- Leibniz Institute for Zoo and Wildlife Research Berlin, Germany
| | | | - James W McMichael
- Department of Biology, Bucknell University Lewisburg, Pennsylvania, 17837
| | | | | | - Shayne S Lumadue
- Department of Biology, Bucknell University Lewisburg, Pennsylvania, 17837
| | | | - Michael O Toro
- Department of Biology, Bucknell University Lewisburg, Pennsylvania, 17837
| | - Kenneth A Field
- Department of Biology, Bucknell University Lewisburg, Pennsylvania, 17837
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17
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Hanna E, Cardillo M. Clarifying the relationship between torpor and anthropogenic extinction risk in mammals. J Zool (1987) 2014. [DOI: 10.1111/jzo.12136] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- E. Hanna
- Macroevolution & Macroecology Group Research School of Biology Australian National University Canberra ACT Australia
| | - M. Cardillo
- Macroevolution & Macroecology Group Research School of Biology Australian National University Canberra ACT Australia
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O’Shea TJ, Bowen RA, Stanley TR, Shankar V, Rupprecht CE. Variability in seroprevalence of rabies virus neutralizing antibodies and associated factors in a Colorado population of big brown bats (Eptesicus fuscus). PLoS One 2014; 9:e86261. [PMID: 24465996 PMCID: PMC3899234 DOI: 10.1371/journal.pone.0086261] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Accepted: 12/11/2013] [Indexed: 12/25/2022] Open
Abstract
In 2001–2005 we sampled permanently marked big brown bats (Eptesicus fuscus) at summer roosts in buildings at Fort Collins, Colorado, for rabies virus neutralizing antibodies (RVNA). Seroprevalence was higher in adult females (17.9%, n = 2,332) than males (9.4%, n = 128; P = 0.007) or volant juveniles (10.2%, n = 738; P<0.0001). Seroprevalence was lowest in a drought year with local insecticide use and highest in the year with normal conditions, suggesting that environmental stress may suppress RVNA production in big brown bats. Seroprevalence also increased with age of bat, and varied from 6.2 to 26.7% among adult females at five roosts sampled each year for five years. Seroprevalence of adult females at 17 other roosts sampled for 1 to 4 years ranged from 0.0 to 47.1%. Using logistic regression, the only ranking model in our candidate set of explanatory variables for serological status at first sampling included year, day of season, and a year by day of season interaction that varied with relative drought conditions. The presence or absence of antibodies in individual bats showed temporal variability. Year alone provided the best model to explain the likelihood of adult female bats showing a transition to seronegative from a previously seropositive state. Day of the season was the only competitive model to explain the likelihood of a transition from seronegative to seropositive, which increased as the season progressed. We found no rabies viral RNA in oropharyngeal secretions of 261 seropositive bats or in organs of 13 euthanized seropositive bats. Survival of seropositive and seronegative bats did not differ. The presence of RVNA in serum of bats should not be interpreted as evidence for ongoing rabies infection.
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Affiliation(s)
- Thomas J. O’Shea
- United States Geological Survey, Fort Collins Science Center, Fort Collins, Colorado, United States of America
- * E-mail:
| | - Richard A. Bowen
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Thomas R. Stanley
- United States Geological Survey, Fort Collins Science Center, Fort Collins, Colorado, United States of America
| | - Vidya Shankar
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
- Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Charles E. Rupprecht
- Ross University School of Veterinary Medicine, Basseterre, Saint Kitts, West Indies
- The Global Alliance for Rabies Control, Manhattan, Kansas, United States of America
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19
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Zervanos SM, Maher CR, Florant GL. Effect of body mass on hibernation strategies of woodchucks (Marmota monax). Integr Comp Biol 2013; 54:443-51. [PMID: 24345658 DOI: 10.1093/icb/ict100] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The benefits of mammalian hibernation have been well documented. However, the physiological and ecological costs of torpor have been emphasized only recently as part of a hibernation-optimization hypothesis. This hypothesis predicts that hibernators with greater availability of energy minimize costs of torpor by less frequent utilization of torpor and by maintaining higher body temperatures (T(b)) during torpor. In order to further examine the relationship between body mass and other parameters of hibernation, we present data, collected over a 12-year period, on the hibernation patterns of free-living woodchucks (Marmota monax) in southeastern Pennsylvania. Body mass was positively correlated with T(b) and negatively correlated with percentage of the heterothermic period spent in torpor. Thus, woodchucks with greater mass exhibited less time in torpor as a proportion of their heterothermic period and at higher T(b) than those with lesser mass. This strategy potentially enhances the physiological and physical ability of woodchucks to defend territories, avoid predation, find mates, and complete the reproductive cycle upon emergence from hibernation. Our results further support the hibernation-optimization hypothesis by demonstrating the relationship between body mass and characteristics of torpor and contributing toward a fuller understanding of this concept.
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Affiliation(s)
- Stam M Zervanos
- *Department of Biology, Pennsylvania State University/Berks, PO Box 7009, Reading, PA 19610-6009, USA; Department of Biological Sciences, University of Southern Maine, Portland, ME 04104, USA; Department of Biology, Colorado State University, Ft. Collins, CO 80523, USA
| | - Christine R Maher
- *Department of Biology, Pennsylvania State University/Berks, PO Box 7009, Reading, PA 19610-6009, USA; Department of Biological Sciences, University of Southern Maine, Portland, ME 04104, USA; Department of Biology, Colorado State University, Ft. Collins, CO 80523, USA
| | - Gregory L Florant
- *Department of Biology, Pennsylvania State University/Berks, PO Box 7009, Reading, PA 19610-6009, USA; Department of Biological Sciences, University of Southern Maine, Portland, ME 04104, USA; Department of Biology, Colorado State University, Ft. Collins, CO 80523, USA
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20
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Kronfeld-Schor N, Dayan T. Thermal Ecology, Environments, Communities, and Global Change: Energy Intake and Expenditure in Endotherms. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2013. [DOI: 10.1146/annurev-ecolsys-110512-135917] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
To survive, animals must maintain a balance between energy acquisition (foraging) and energy expenditure. This challenge is particularly great for endotherm vertebrates that require high amounts of energy to maintain homeothermy. Many of these endotherms use hibernation or daily torpor as a mechanism to reduce energy expenditure during anticipated or stochastic periods of stress. Although ecological researchers have focused extensively on energy acquisition, physiologists have largely studied thermal ecology and the mechanisms allowing endotherms to regulate energy expenditure, with little research explicitly linking ecology and thermal biology. Nevertheless, theoretical considerations and research conducted so far point to a significant ecological role for torpor in endotherms. Moreover, global-change challenges facing vertebrate endotherms are also considered in view of their ability to regulate their energy expenditure. We review the thermal ecology of endothermic vertebrates and some of its ecological and evolutionary implications.
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Affiliation(s)
| | - Tamar Dayan
- Department of Zoology, Tel Aviv University, Tel Aviv 69978, Israel;,
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21
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Bieber C, Lebl K, Stalder G, Geiser F, Ruf T. Body mass dependent use of hibernation: why not prolong the active season, if they can? Funct Ecol 2013. [DOI: 10.1111/1365-2435.12173] [Citation(s) in RCA: 113] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Claudia Bieber
- Department of Integrative Biology and Evolution University of Veterinary Medicine Savoyenstrasse 1, 1160, Vienna Austria
- Centre for Behavioural and Physiological Ecology, Zoology University of New England Armidale NSW 2351 Australia
| | - Karin Lebl
- Department of Integrative Biology and Evolution University of Veterinary Medicine Savoyenstrasse 1, 1160, Vienna Austria
| | - Gabrielle Stalder
- Department of Integrative Biology and Evolution University of Veterinary Medicine Savoyenstrasse 1, 1160, Vienna Austria
| | - Fritz Geiser
- Centre for Behavioural and Physiological Ecology, Zoology University of New England Armidale NSW 2351 Australia
| | - Thomas Ruf
- Department of Integrative Biology and Evolution University of Veterinary Medicine Savoyenstrasse 1, 1160, Vienna Austria
- Centre for Behavioural and Physiological Ecology, Zoology University of New England Armidale NSW 2351 Australia
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22
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Nord A, Chiriac S, Hasselquist D, Nilsson JÅ. Endotoxin injection attenuates rest-phase hypothermia in wintering great tits through the onset of fever. Funct Ecol 2012. [DOI: 10.1111/1365-2435.12003] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Andreas Nord
- Department of Biology; Section for Evolutionary Ecology; Lund University; Ecology Building; SE-223 62; Lund; Sweden
| | | | - Dennis Hasselquist
- Department of Biology, MEMEG, Molecular Ecology and Evolution Group; Lund University; Ecology Building; SE-223 62; Lund; Sweden
| | - Jan-Åke Nilsson
- Department of Biology; Section for Evolutionary Ecology; Lund University; Ecology Building; SE-223 62; Lund; Sweden
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23
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Jonasson KA, Willis CKR. Hibernation energetics of free-ranging little brown bats. ACTA ACUST UNITED AC 2012; 215:2141-9. [PMID: 22623203 DOI: 10.1242/jeb.066514] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Hibernation physiology and energy expenditure have been relatively well studied in large captive hibernators, especially rodents, but data from smaller, free-ranging hibernators are sparse. We examined variation in the hibernation patterns of free-ranging little brown bats (Myotis lucifugus) using temperature-sensitive radio-transmitters. First, we aimed to test the hypothesis that age, sex and body condition affect expression of torpor and energy expenditure during hibernation. Second, we examined skin temperature to assess whether qualitative differences in the thermal properties of the hibernacula of bats, compared with the burrows of hibernating rodents, might lead to different patterns of torpor and arousal for bats. We also evaluated the impact of carrying transmitters on body condition to help determine the potential impact of telemetry studies. We observed large variation in the duration of torpor bouts within and between individuals but detected no effect of age, sex or body condition on torpor expression or estimates of energy expenditure. We observed the use of shallow torpor in the midst of periodic arousals, which may represent a unique adaptation of bats for conservation of energy during the most costly phase of hibernation. There was no difference in the body condition of hibernating bats outfitted with transmitters compared with that of control bats captured from the same hibernaculum at the same time. This study provides new information on the energetics of hibernation in an under-represented taxon and baseline data important for understanding how white-nose syndrome, a new disease devastating populations of hibernating bats in North America, may alter the expression of hibernation in affected bats.
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Affiliation(s)
- Kristin A Jonasson
- Department of Biology and Centre for Forest Inter-disciplinary Research, University of Winnipeg, 515 Portage Avenue, Winnipeg, MB, Canada R3B 2E9
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Inoculation of bats with European Geomyces destructans supports the novel pathogen hypothesis for the origin of white-nose syndrome. Proc Natl Acad Sci U S A 2012; 109:6999-7003. [PMID: 22493237 DOI: 10.1073/pnas.1200374109] [Citation(s) in RCA: 277] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
White-nose syndrome (WNS) is an emerging disease of hibernating bats associated with cutaneous infection by the fungus Geomyces destructans (Gd), and responsible for devastating declines of bat populations in eastern North America. Affected bats appear emaciated and one hypothesis is that they spend too much time out of torpor during hibernation, depleting vital fat reserves required to survive the winter. The fungus has also been found at low levels on bats throughout Europe but without mass mortality. This finding suggests that Gd is either native to both continents but has been rendered more pathogenic in North America by mutation or environmental change, or that it recently arrived in North America as an invader from Europe. Thus, a causal link between Gd and mortality has not been established and the reason for its high pathogenicity in North America is unknown. Here we show that experimental inoculation with either North American or European isolates of Gd causes WNS and mortality in the North American bat, Myotis lucifugus. In contrast to control bats, individuals inoculated with either isolate of Gd developed cutaneous infections diagnostic of WNS, exhibited a progressive increase in the frequency of arousals from torpor during hibernation, and were emaciated after 3-4 mo. Our results demonstrate that altered torpor-arousal cycles underlie mortality from WNS and provide direct evidence that Gd is a novel pathogen to North America from Europe.
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25
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Warming up for dinner: torpor and arousal in hibernating Natterer's bats (Myotis nattereri) studied by radio telemetry. J Comp Physiol B 2011; 182:569-78. [PMID: 22124860 DOI: 10.1007/s00360-011-0631-x] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Revised: 11/03/2011] [Accepted: 11/09/2011] [Indexed: 10/15/2022]
Abstract
The frequency and function of arousals during hibernation in free-living mammals are little known. We used temperature-sensitive radio transmitters to measure patterns of torpor, arousal and activity in wild Natterer's bats Myotis nattereri during hibernation. Duration of torpor bouts ranged from 0.06 to 20.4 days with individual means ranging from 0.9 to 8.9 days. Arousals from torpor occurred most commonly coincident with the time (relative to sunset) typical for bats emerging from summer roosts to forage. Bats with lower body condition indices had a shorter average duration of their torpor bouts. We found a non-linear relationship between duration of torpor bout and ambient temperature: the longest average torpor bouts were at temperatures between 2 and 4°C with shorter bouts at lower and higher ambient temperatures. One individual was radio-tracked for ten nights, remained active for an average of 297 min each night and was active for longer on warmer nights. Our results suggest that vespertilionid bats use relatively short torpor bouts during hibernation in a location with a maritime climate. We hypothesise that Natterer's bats time arousals to maximise opportunities for potential foraging during winter although winter feeding is not the sole determinant of arousal as bats still arouse at times when foraging is unlikely.
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26
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Jonasson KA, Willis CKR. Changes in body condition of hibernating bats support the thrifty female hypothesis and predict consequences for populations with white-nose syndrome. PLoS One 2011; 6:e21061. [PMID: 21731647 PMCID: PMC3120823 DOI: 10.1371/journal.pone.0021061] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Accepted: 05/19/2011] [Indexed: 11/19/2022] Open
Abstract
White-nose syndrome (WNS) is a new disease of bats that has devastated populations in eastern North America. Infection with the fungus, Geomyces destructans, is thought to increase the time bats spend out of torpor during hibernation, leading to starvation. Little is known about hibernation in healthy, free-ranging bats and more data are needed to help predict consequences of WNS. Trade-offs presumably exist between the energetic benefits and physiological/ecological costs of torpor, leading to the prediction that the relative importance of spring energy reserves should affect an individual's use of torpor and depletion of energy reserves during winter. Myotis lucifugus mate during fall and winter but females do not become pregnant until after spring emergence. Thus, female reproductive success depends on spring fat reserves while male reproductive success does not. Consequently, females should be "thrifty" in their use of fat compared to males. We measured body condition index (BCI; mass/forearm length) of 432 M. lucifugus in Manitoba, Canada during the winter of 2009/2010. Bats were captured during the fall mating period (n = 200), early hibernation (n = 125), and late hibernation (n = 128). Adult females entered hibernation with greater fat reserves and consumed those reserves more slowly than adult males and young of the year. Consequently, adult females may be more likely than males or young of the year to survive the disruption of energy balance associated with WNS, although surviving females may not have sufficient reserves to support reproduction.
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Affiliation(s)
- Kristin A. Jonasson
- Department of Biology, Centre for Forest Interdisciplinary Research (C-FIR), University of Winnipeg, Winnipeg, Canada
| | - Craig K. R. Willis
- Department of Biology, Centre for Forest Interdisciplinary Research (C-FIR), University of Winnipeg, Winnipeg, Canada
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27
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28
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Rambaldini DA, Brigham RM. Torpor Use by Free-Ranging Pallid Bats (Antrozous pallidus) at the Northern Extent of Their Range. J Mammal 2008. [DOI: 10.1644/08-mamm-a-029.1] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Kurtz CC, Carey HV. Seasonal changes in the intestinal immune system of hibernating ground squirrels. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2007; 31:415-28. [PMID: 16930701 DOI: 10.1016/j.dci.2006.07.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2006] [Revised: 06/23/2006] [Accepted: 07/03/2006] [Indexed: 05/06/2023]
Abstract
Hibernation is associated with a prolonged fast (5-8 mo) which has the potential to affect intestinal immunity. We examined several aspects of the intestinal immune system in summer (non-hibernating) and hibernating ground squirrels. Peyer's patches were largely unaffected by hibernation, but numbers of intraepithelial lymphocytes (IEL) and lamina propria leukocytes (LPL) were greater in hibernators compared with summer. Hibernator IEL were less mature as demonstrated by low numbers of cells expressing activation-associated markers and co-receptors. Compared with summer, the percentage of B cells was higher and percentage of T cells was lower in the hibernator LPL. Hibernation was associated with greater mucosal levels of IFN-gamma, TNF-alpha, IL-10 and IL-4, but IL-6 and TGF-beta were unchanged. Mucosal IgA levels were greater in entrance and torpid hibernators compared with summer. The results suggest that modifications of the intestinal immune system during hibernation may help preserve gut integrity throughout the winter fast.
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Affiliation(s)
- Courtney C Kurtz
- Department of Comparative Biosciences, University of Wisconsin, School of Veterinary Medicine, 2015 Linden Drive, Madison, WI 53706, USA
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30
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Abstract
Periodic arousal from hibernation among mammalian hibernators is poorly understood. In bats, arousal is often associated with flight. We acoustically monitored two rocky areas along the Red Deer River in southeastern Alberta for bat activity in autumn, winter, and spring months. We found bats to be active in all months and at unexpectedly cold temperatures (coldest activity –8 °C). Bats were active even when ambient temperatures remained below 0 °C during the day and night. We documented Myotis ciliolabrum (Merriam, 1886), Myotis evotis (H. Allen, 1864), and Eptesicus fuscus (Beauvois, 1796) flying outside hibernacula in winter. Active E. fuscus that we captured in mid-winter of 2004–2005 weighed less than bats captured in the fall, but masses ranged from 14.0 to 21.0 g, indicating that some individuals still had fat reserves. Captured individuals were of various ages, with a male bias. Using radiotelemetry, we located the first natural rock-crevice hibernacula for male and female E. fuscus in the Canadian prairies. Winter roosts were narrow, deep rock crevices or erosion holes located in steep valley walls. We found evidence to suggest that dehydration may be a driving force for winter flights.
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Affiliation(s)
- C.L. Lausen
- Department of Biological Sciences, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - R.M.R. Barclay
- Department of Biological Sciences, University of Calgary, Calgary, AB T2N 1N4, Canada
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Berggren KT, Ellegren H, Hewitt GM, Seddon JM. Understanding the phylogeographic patterns of European hedgehogs, Erinaceus concolor and E. europaeus using the MHC. Heredity (Edinb) 2005; 95:84-90. [PMID: 16077505 DOI: 10.1038/sj.hdy.6800694] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The genome of the European hedgehog, Erinaceus concolor and E. europaeus, shows a strong signal of cycles of restriction to glacial refugia and postglacial expansion. Patterns of expansion, however, differ for mitochondrial DNA (mtDNA) and preliminary analysis of nuclear markers. In this study, we determine phylogeographic patterns in the hedgehog using two loci of the major histocompatibility complex (MHC), isolated for the first time in hedgehogs. These genes show long persistence times and high polymorphism in many species because of the actions of balancing selection. Among 84 individuals screened for variation, only two DQA alleles were identified in each species, but 10 DQB alleles were found in E. concolor and six in E. europaeus. A strong effect of demography on patterns of DQB variability is observed, with only weak evidence of balancing selection. While data from mtDNA clearly subdivide both species into monophyletic subgroups, the MHC data delineate only E. concolor into distinct subgroups, supporting the preliminary findings of other nuclear markers. Together with differences in variability, this suggests that the refugia history and/or expansion patterns of E. concolor and E. europaeus differ.
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Affiliation(s)
- K T Berggren
- Department of Evolutionary Biology, EBC, Uppsala University, Uppsala, Sweden
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33
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Park KJ, Jones G, Ransome RD. Torpor, arousal and activity of hibernating Greater Horseshoe Bats (Rhinolophus ferrumequinum
). Funct Ecol 2003. [DOI: 10.1046/j.1365-2435.2000.t01-1-00460.x] [Citation(s) in RCA: 122] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Carey HV, Andrews MT, Martin SL. Mammalian hibernation: cellular and molecular responses to depressed metabolism and low temperature. Physiol Rev 2003; 83:1153-81. [PMID: 14506303 DOI: 10.1152/physrev.00008.2003] [Citation(s) in RCA: 792] [Impact Index Per Article: 37.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Mammalian hibernators undergo a remarkable phenotypic switch that involves profound changes in physiology, morphology, and behavior in response to periods of unfavorable environmental conditions. The ability to hibernate is found throughout the class Mammalia and appears to involve differential expression of genes common to all mammals, rather than the induction of novel gene products unique to the hibernating state. The hibernation season is characterized by extended bouts of torpor, during which minimal body temperature (Tb) can fall as low as -2.9 degrees C and metabolism can be reduced to 1% of euthermic rates. Many global biochemical and physiological processes exploit low temperatures to lower reaction rates but retain the ability to resume full activity upon rewarming. Other critical functions must continue at physiologically relevant levels during torpor and be precisely regulated even at Tb values near 0 degrees C. Research using new tools of molecular and cellular biology is beginning to reveal how hibernators survive repeated cycles of torpor and arousal during the hibernation season. Comprehensive approaches that exploit advances in genomic and proteomic technologies are needed to further define the differentially expressed genes that distinguish the summer euthermic from winter hibernating states. Detailed understanding of hibernation from the molecular to organismal levels should enable the translation of this information to the development of a variety of hypothermic and hypometabolic strategies to improve outcomes for human and animal health.
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Affiliation(s)
- Hannah V Carey
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI 53706, USA.
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35
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Humphries MM, Kramer DL, Thomas DW. The role of energy availability in Mammalian hibernation: an experimental test in free-ranging eastern chipmunks. Physiol Biochem Zool 2003; 76:180-6. [PMID: 12794671 DOI: 10.1086/367949] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/23/2002] [Indexed: 11/03/2022]
Abstract
Reduced torpor expression by hibernating mammals is often attributed to physiological constraints that limit their hibernation ability but may instead reflect adaptive, plastic responses to surplus energy availability. We evaluated this hypothesis by supplementing the food hoards of free-ranging eastern chipmunks (Tamias striatus) before hibernation and then documenting their use of torpor during the subsequent winter. In both years of study, chipmunks that received additional food were euthermic more than twice as frequently as nonsupplemented individuals. Furthermore, when food-supplemented individuals did express torpor, their minimum collar temperature was 5 degrees -10 degrees C warmer than nonsupplemented animals. These results indicate that reduced torpor expression by hibernators can result from an absence of energetic necessity rather than a lack of physiological capability and suggest that even endotherms sequestered in a hibernaculum may benefit from maintaining an elevated body temperature whenever possible.
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Affiliation(s)
- Murray M Humphries
- Department of Biology, McGill University, 1205 Avenue Docteur Penfield, Montreal, Quebec H3A 1B1, Canada.
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Humphries MM, Thomas DW, Kramer DL. The role of energy availability in Mammalian hibernation: a cost-benefit approach. Physiol Biochem Zool 2003; 76:165-79. [PMID: 12794670 DOI: 10.1086/367950] [Citation(s) in RCA: 296] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/23/2002] [Indexed: 11/03/2022]
Abstract
Hibernation is widely regarded as an adaptation to seasonal energy shortage, but the actual influence of energy availability on hibernation patterns is rarely considered. Here we review literature on the costs and benefits of torpor expression to examine the influence that energy may have on hibernation patterns. We first establish that the dichotomy between food- and fat-storing hibernators coincides with differences in diet rather than body size and show that small or large species pursuing either strategy have considerable potential scope in the amount of torpor needed to survive winter. Torpor expression provides substantial energy savings, which increase the chance of surviving a period of food shortage and emerging with residual energy for early spring reproduction. However, all hibernating mammals periodically arouse to normal body temperatures during hibernation. The function of these arousals has long been speculated to involve recovery from physiological costs accumulated during metabolic depression, and recent physiological studies indicate these costs may include oxidative stress, reduced immunocompetence, and perhaps neuronal tissue damage. Using an optimality approach, we suggest that trade-offs between the benefits of energy conservation and the physiological costs of metabolic depression can explain both why hibernators periodically arouse from torpor and why they should use available energy to minimize the depth and duration of their torpor bouts. On the basis of these trade-offs, we derive a series of testable predictions concerning the relationship between energy availability and torpor expression. We conclude by reviewing the empirical support for these predictions and suggesting new avenues for research on the role of energy availability in mammalian hibernation.
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Affiliation(s)
- Murray M Humphries
- Department of Biology, McGill University, 1205 Avenue Docteur Penfield, Montreal, Quebec H3A 1B1, Canada.
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Prendergast BJ, Freeman DA, Zucker I, Nelson RJ. Periodic arousal from hibernation is necessary for initiation of immune responses in ground squirrels. Am J Physiol Regul Integr Comp Physiol 2002; 282:R1054-62. [PMID: 11893609 DOI: 10.1152/ajpregu.00562.2001] [Citation(s) in RCA: 159] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Golden-mantled ground squirrels (Spermophilus lateralis) undergo seasonal hibernation during which core body temperature (T(b)) values are maintained 1-2 degrees C above ambient temperature. Hibernation is not continuous. Squirrels arouse at approximately 7-day intervals, during which T(b) increases to 37 degrees C for approximately 16 h; thereafter, they return to hibernation and sustain low T(b)s until the next arousal. Over the course of the hibernation season, arousals consume 60-80% of a squirrel's winter energy budget, but their functional significance is unknown and disputed. Host-defense mechanisms appear to be downregulated during the hibernation season and preclude normal immune responses. These experiments assessed immune function during hibernation and subsequent periodic arousals. The acute-phase response to bacterial lipopolysaccharide (LPS) was arrested during hibernation and fully restored on arousal to normothermia. LPS injection (ip) resulted in a 1-1.5 degrees C fever in normothermic animals that was sustained for > 8 h. LPS was without effect in hibernating squirrels, neither inducing fever nor provoking arousal, but a fever did develop several days later, when squirrels next aroused from hibernation; the duration of this arousal was increased sixfold above baseline values. Intracerebroventricular infusions of prostaglandin E(2) provoked arousal from hibernation and induced fever, suggesting that neural signaling pathways that mediate febrile responses are functional during hibernation. Periodic arousals may activate a dormant immune system, which can then combat pathogens that may have been introduced immediately before or during hibernation.
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Affiliation(s)
- Brian J Prendergast
- Department of Psychology, The Ohio State University, Columbus, Ohio 43210, USA.
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