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Grabek KR, Sprenger RJ. The evolution of thermogenesis in mammals. Science 2024; 384:1065-1066. [PMID: 38843350 DOI: 10.1126/science.adp8782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2024]
Abstract
Comparative genomics elucidates the steps enabling heat production in fat tissue.
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2
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Lyons SA, McClelland GB. Highland deer mice support increased thermogenesis in response to chronic cold hypoxia by shifting uptake of circulating fatty acids from muscles to brown adipose tissue. J Exp Biol 2024; 227:jeb247340. [PMID: 38506250 PMCID: PMC11057874 DOI: 10.1242/jeb.247340] [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: 01/15/2024] [Accepted: 03/14/2024] [Indexed: 03/21/2024]
Abstract
During maximal cold challenge (cold-induced V̇O2,max) in hypoxia, highland deer mice (Peromyscus maniculatus) show higher rates of circulatory fatty acid delivery compared with lowland deer mice. Fatty acid delivery also increases with acclimation to cold hypoxia (CH) and probably plays a major role in supporting the high rates of thermogenesis observed in highland deer mice. However, it is unknown which tissues take up these fatty acids and their relative contribution to thermogenesis. The goal of this study was to determine the uptake of circulating fatty acids into 24 different tissues during hypoxic cold-induced V̇O2,max, by using [1-14C]2-bromopalmitic acid. To uncover evolved and environment-induced changes in fatty acid uptake, we compared lab-born and -raised highland and lowland deer mice, acclimated to either thermoneutral (30°C, 21 kPa O2) or CH (5°C, 12 kPa O2) conditions. During hypoxic cold-induced V̇O2,max, CH-acclimated highlanders decreased muscle fatty acid uptake and increased uptake into brown adipose tissue (BAT) relative to thermoneutral highlanders, a response that was absent in lowlanders. CH acclimation was also associated with increased activities of enzymes citrate synthase and β-hydroxyacyl-CoA dehydrogenase in the BAT of highlanders, and higher levels of fatty acid translocase CD36 (FAT/CD36) in both populations. This is the first study to show that cold-induced fatty acid uptake is distributed across a wide range of tissues. Highland deer mice show plasticity in this fatty acid distribution in response to chronic cold hypoxia, and combined with higher rates of tissue delivery, this contributes to their survival in the cold high alpine environment.
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Affiliation(s)
- Sulayman A. Lyons
- Department of Biology, McMaster University, Hamilton, ON, Canada, L8S 4K1
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3
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Flewwelling LD, Wearing OH, Garrett EJ, Scott GR. Thermoregulatory trade-offs underlie the effects of warming summer temperatures on deer mice. J Exp Biol 2023; 226:287070. [PMID: 36808489 DOI: 10.1242/jeb.244852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 02/13/2023] [Indexed: 02/22/2023]
Abstract
Climate warming could challenge the ability of endotherms to thermoregulate and maintain normal body temperature (Tb), but the effects of warming summer temperatures on activity and thermoregulatory physiology in many small mammals remain poorly understood. We examined this issue in deer mice (Peromyscus maniculatus), an active nocturnal species. Mice were exposed in the lab to simulated seasonal warming, in which an environmentally realistic diel cycle of ambient temperature (Ta) was gradually warmed from spring conditions to summer conditions (controls were maintained in spring conditions). Activity (voluntary wheel running) and Tb (implanted bio-loggers) were measured throughout, and indices of thermoregulatory physiology (thermoneutral zone, thermogenic capacity) were assessed after exposure. In control mice, activity was almost entirely restricted to the night-time, and Tb fluctuated ∼1.7°C between daytime lows and night-time highs. Activity, body mass and food consumption were reduced and water consumption was increased in later stages of summer warming. This was accompanied by strong Tb dysregulation that culminated in a complete reversal of the diel pattern of Tb variation, with Tb reaching extreme highs (∼40°C) during daytime heat but extreme lows (∼34°C) at cooler night-time temperatures. Summer warming was also associated with reduced ability to generate body heat, as reflected by decreased thermogenic capacity and decreased mass and uncoupling protein (UCP1) content of brown adipose tissue. Our findings suggest that thermoregulatory trade-offs associated with daytime heat exposure can affect Tb and activity at cooler night-time temperatures, impacting the ability of nocturnal mammals to perform behaviours important for fitness in the wild.
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Affiliation(s)
- Luke D Flewwelling
- Department of Biology, McMaster University, 1280 Main Street West, Hamilton, ON, Canada, L8S 4K1
| | - Oliver H Wearing
- Department of Biology, McMaster University, 1280 Main Street West, Hamilton, ON, Canada, L8S 4K1
| | - Emily J Garrett
- Department of Biology, McMaster University, 1280 Main Street West, Hamilton, ON, Canada, L8S 4K1
| | - Graham R Scott
- Department of Biology, McMaster University, 1280 Main Street West, Hamilton, ON, Canada, L8S 4K1
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4
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Maloney CM, Careau V. Individual variation in heat substitution: is activity in the cold energetically cheaper for some individuals than others? J Exp Biol 2022; 225:276466. [PMID: 36036801 DOI: 10.1242/jeb.244186] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 08/25/2022] [Indexed: 11/20/2022]
Abstract
In many endotherms, a potentially important yet often overlooked mechanism to save energy is the use of the heat generated by active skeletal muscles to replace heat that would have been generated by thermogenesis (i.e., "activity-thermoregulatory heat substitution"). While substitution has been documented numerous times, the extent of individual variation in substitution has never been quantified. Here, we used a home-cage respirometry system to repeatedly measure substitution through the concomitant monitoring of metabolic rate (MR) and locomotor activity in 46 female white-footed mice (Peromyscus leucopus). A total of 117 measures of substitution were taken by quantifying the difference in the slope of the relationship between MR and locomotor activity speed at two different ambient temperatures. Consistency repeatability (±se) of substitution was 0.313±0.131 - hence, about a third of the variation in substitution occurs at the among-individual level. Body length and heart mass were positively correlated with substitution whereas surface area was negatively correlated with substitution. These two sub-organismal traits accounted for the majority of the among-individual variation (i.e., individual differences in substitution were not significant after accounting for these traits). Overall, our results imply that the energetic cost of activity below the thermoneutral zone is consistently cheaper from some individuals than others, and that the energy saved from substitution might be available to invest in fitness-enhancing activities.
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Affiliation(s)
- Caroline M Maloney
- Department of Biology, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - Vincent Careau
- Department of Biology, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
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5
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Welman S, Jastroch M, Mzilikazi N. Obligatory homeothermy of mesic adapted African striped mice, Rhabdomys pumilio, is governed by seasonal basal metabolism and year-round "thermogenic readiness" of brown adipose tissue. J Exp Biol 2022; 225:275893. [PMID: 35694963 DOI: 10.1242/jeb.243860] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 06/08/2022] [Indexed: 11/20/2022]
Abstract
Small mammals undergo thermoregulatory adjustments in response to changing environmental conditions. Whereas small heterothermic mammals can employ torpor to save energy in the cold, homeothermic species must increase heat production to defend normothermia through the recruitment of brown adipose tissue (BAT). Here, we studied thermoregulatory adaptation in an obligate homeotherm, the African striped mouse (Rhabdomys pumilio), captured from a subpopulation living in a mesic, temperate climate with marked seasonal differences. Basal metabolic rate (BMR), non-shivering thermogenesis (NST) and summit metabolic rate (MSUM) increased from summer to winter, with NST and MSUM already reaching maximal rates in autumn, suggesting seasonal preparation to the cold. Typical of rodents, cold-induced metabolic rates positively correlate with BAT mass. Analysis of cytochrome c oxidase (COX) activity and UCP1 content, however, demonstrate that thermogenic capacity declines with BAT mass. This resulted in seasonal differences in NST being driven by changes in BMR. The increase in BMR is supported by a comprehensive anatomical analysis of metabolically active organs, revealing increased mass proportions in the cold season. The thermoregulatory response of R. pumilio is associated with the maintenance of body weight throughout the year (48.3±1.4 g), contrasting large summer-winter mass reductions often observed in Holarctic rodents. Collectively, bioenergetic adaptation of this Afrotropical rodent involves seasonal organ adjustments influencing BMR, combined with a constant thermogenic capacity dictated by trade-offs in thermogenic properties of BAT. Arguably, this high degree of plasticity was a response to unpredictable cold spells throughout the year. Consequently, the reliance on such a resource intensive thermoregulatory strategy may expose more energetic vulnerability in changing environments of food scarcity and extreme weather conditions due to climate change, with major ramifications for survival of the species.
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Affiliation(s)
- Shaun Welman
- Department of Zoology, Nelson Mandela University, Gqeberha, South Africa
| | - Martin Jastroch
- Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, SE-106 91 Stockholm, Sweden.,Institute for Diabetes and Obesity, Helmholtz Zentrum München, German Research Center for Environmental Health, Munich-Neuherberg, Germany
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6
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Lezama-García K, Mota-Rojas D, Martínez-Burnes J, Villanueva-García D, Domínguez-Oliva A, Gómez-Prado J, Mora-Medina P, Casas-Alvarado A, Olmos-Hernández A, Soto P, Muns R. Strategies for Hypothermia Compensation in Altricial and Precocial Newborn Mammals and Their Monitoring by Infrared Thermography. Vet Sci 2022; 9:vetsci9050246. [PMID: 35622774 PMCID: PMC9145389 DOI: 10.3390/vetsci9050246] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Revised: 05/18/2022] [Accepted: 05/18/2022] [Indexed: 02/06/2023] Open
Abstract
Thermoregulation in newborn mammals is an essential species-specific mechanism of the nervous system that contributes to their survival during the first hours and days of their life. When exposed to cold weather, which is a risk factor associated with mortality in neonates, pathways such as the hypothalamic–pituitary–adrenal axis (HPA) are activated to achieve temperature control, increasing the circulating levels of catecholamine and cortisol. Consequently, alterations in blood circulation and mechanisms to produce or to retain heat (e.g., vasoconstriction, piloerection, shivering, brown adipocyte tissue activation, and huddling) begin to prevent hypothermia. This study aimed to discuss the mechanisms of thermoregulation in newborn domestic mammals, highlighting the differences between altricial and precocial species. The processes that employ brown adipocyte tissue, shivering, thermoregulatory behaviors, and dermal vasomotor control will be analyzed to understand the physiology and the importance of implementing techniques to promote thermoregulation and survival in the critical post-birth period of mammals. Also, infrared thermography as a helpful method to perform thermal measurements without animal interactions does not affect these parameters.
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Affiliation(s)
- Karina Lezama-García
- PhD Program in Biological and Health Sciences [Doctorado en Ciencias Biológicas y de la Salud], Universidad Autónoma Metropolitana (UAM), Mexico City 04960, Mexico;
| | - Daniel Mota-Rojas
- Neurophysiology, Behavior and Animal Welfare Assessment, DPAA, Universidad Autónoma Metropolitana (UAM), Mexico City 04960, Mexico; (A.D.-O.); (J.G.-P.); (A.C.-A.); (P.S.)
- Correspondence:
| | - Julio Martínez-Burnes
- Animal Health Group, Facultad de Medicina Veterinaria y Zootecnia, Universidad Autónoma de Tamaulipas, Victoria City 87000, Tamaulipas, Mexico;
| | - Dina Villanueva-García
- Division of Neonatology, National Institute of Health, Hospital Infantil de México Federico Gómez, Doctor Márquez 162, Mexico City 06720, Mexico;
| | - Adriana Domínguez-Oliva
- Neurophysiology, Behavior and Animal Welfare Assessment, DPAA, Universidad Autónoma Metropolitana (UAM), Mexico City 04960, Mexico; (A.D.-O.); (J.G.-P.); (A.C.-A.); (P.S.)
| | - Jocelyn Gómez-Prado
- Neurophysiology, Behavior and Animal Welfare Assessment, DPAA, Universidad Autónoma Metropolitana (UAM), Mexico City 04960, Mexico; (A.D.-O.); (J.G.-P.); (A.C.-A.); (P.S.)
| | - Patricia Mora-Medina
- Department of Livestock Science, FESC, Universidad Nacional Autónoma de México (UNAM), Cuautitlán Izcalli 54714, Mexico;
| | - Alejandro Casas-Alvarado
- Neurophysiology, Behavior and Animal Welfare Assessment, DPAA, Universidad Autónoma Metropolitana (UAM), Mexico City 04960, Mexico; (A.D.-O.); (J.G.-P.); (A.C.-A.); (P.S.)
| | - Adriana Olmos-Hernández
- Division of Biotechnology—Bioterio and Experimental Surgery, Instituto Nacional de Rehabilitación-Luis Guillermo Ibarra Ibarra (INR-LGII), Mexico City 14389, Mexico;
| | - Paola Soto
- Neurophysiology, Behavior and Animal Welfare Assessment, DPAA, Universidad Autónoma Metropolitana (UAM), Mexico City 04960, Mexico; (A.D.-O.); (J.G.-P.); (A.C.-A.); (P.S.)
| | - Ramon Muns
- Agri-Food and Biosciences Institute, Livestock Production Sciences Unit, Hillsborough BT26 6DR, Northern Ireland, UK;
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Lyons SA, McClelland GB. Thermogenesis is supported by high rates of circulatory fatty acid and triglyceride delivery in highland deer mice. J Exp Biol 2022; 225:275398. [PMID: 35552735 DOI: 10.1242/jeb.244080] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 05/06/2022] [Indexed: 10/18/2022]
Abstract
Highland native deer mice (Peromyscus maniculatus) have greater rates of lipid oxidation during maximal cold challenge in hypoxia (hypoxic cold-induced V˙O2max) compared to their lowland conspecifics. Lipid oxidation is also increased in deer mice acclimated to simulated high altitude (cold hypoxia), regardless of altitude ancestry. The underlying lipid metabolic pathway traits responsible for sustaining maximal thermogenic demand in deer mice is currently unknown. The objective of this study was to characterize key steps in the lipid oxidation pathway in highland and lowland deer mice acclimated to control (23oC, 21kPa O2) or cold hypoxic (5oC, 12kPa O2) conditions. We hypothesized that capacities for lipid delivery and tissue uptake will be greater in highlanders and further increase with cold hypoxia acclimation. With the transition from rest to hypoxic cold-induced V˙O2max, both highland and lowland deer mice showed increased plasma glycerol concentrations and fatty acid availability. Interestingly, cold hypoxia acclimation led to increased plasma triglyceride concentrations at cold-induced V˙O2max, but only in highlanders. Highlanders also had significantly greater delivery rates of circulatory free fatty acids and triglycerides due to higher plasma flow rates at cold-induced V˙O2max. We found no population or acclimation differences in fatty acid translocase (FAT/CD36) abundance in the gastrocnemius or brown adipose tissue, suggesting fatty acid uptake across membranes is not limiting during thermogenesis. Our data indicate that circulatory lipid delivery plays a major role in supporting the high thermogenic rates observed in highland versus lowland deer mice.
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Affiliation(s)
- Sulayman A Lyons
- Department of Biology, McMaster University, Hamilton, ON, L8S 4K1, Canada
| | - Grant B McClelland
- Department of Biology, McMaster University, Hamilton, ON, L8S 4K1, Canada
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8
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Zhu H, Zhong L, Li J, Wang S, Qu J. Differential Expression of Metabolism-Related Genes in Plateau Pika (Ochotona curzoniae) at Different Altitudes on the Qinghai–Tibet Plateau. Front Genet 2022; 12:784811. [PMID: 35126457 PMCID: PMC8811202 DOI: 10.3389/fgene.2021.784811] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 12/28/2021] [Indexed: 11/30/2022] Open
Abstract
According to life history theory, animals living in extreme environments have evolved specific behavioral and physiological strategies for survival. However, the genetic mechanisms underpinning these strategies are unclear. As the highest geographical unit on Earth, the Qinghai–Tibet Plateau is characterized by an extreme environment and climate. During long-term evolutionary processes, animals that inhabit the plateau have evolved specialized morphological and physiological traits. The plateau pika (Ochotona curzoniae), one of the native small mammals that evolved on the Qinghai–Tibet Plateau, has adapted well to this cold and hypoxic environment. To explore the genetic mechanisms underlying the physiological adaptations of plateau pika to extremely cold ambient temperatures, we measured the differences in resting metabolic rate (RMR) and metabolism-related gene expression in individuals inhabiting three distinct altitudes (i.e., 3,321, 3,663, and 4,194 m). Results showed that the body mass and RMR of plateau pika at high- and medium-altitudes were significantly higher than those at the low-altitude. The expression levels of peroxisome proliferator-activated receptor α (pparα), peroxisome proliferator-activated receptor-γ coactivator-1α (pgc-1α), and the PR domain-containing 16 (PRDM16) in white (WAT) and brown (BAT) adipose tissues of plateau pika from high- and medium-altitudes were significantly higher than in pika from the low-altitude region. The enhanced expression levels of pgc-1α and pparα genes in the WAT of pika at high-altitude showed that WAT underwent “browning” and increased thermogenic properties. An increase in the expression of uncoupling protein 1 (UCP1) in the BAT of pika at high altitude indicated that BAT increased their thermogenic properties. The gene expression levels of pparα and pgc-1α in skeletal muscles were significantly higher in high-altitude pika. Simultaneously, the expression of the sarcolipin (SLN) gene in skeletal muscles significantly increased in high-altitude pika. Our results suggest that plateau pika adapted to an extremely cold environment via browning WAT, thereby activating BAT and enhancing SLN expression to increase non-shivering thermogenesis. This study demonstrates that plateau pika can increase thermogenic gene expression and energy metabolism to adapt to the extreme environments on the plateau.
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Affiliation(s)
- Hongjuan Zhu
- Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Liang Zhong
- Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining, China
- Qinghai Province Key Laboratory of Animal Ecological Genomics, Xining, China
| | - Jing Li
- Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Suqin Wang
- Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Jiapeng Qu
- Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining, China
- Qinghai Province Key Laboratory of Animal Ecological Genomics, Xining, China
- *Correspondence: Jiapeng Qu,
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9
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Hayward L, Robertson CE, McClelland GB. Phenotypic plasticity to chronic cold exposure in two species of Peromyscus from different environments. J Comp Physiol B 2022; 192:335-348. [PMID: 34988665 DOI: 10.1007/s00360-021-01423-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 11/17/2021] [Accepted: 11/24/2021] [Indexed: 11/28/2022]
Abstract
Effective thermoregulation is important for mammals, particularly those that remain winter-active. Adjustments in thermoregulatory capacity in response to chronic cold can improve capacities for metabolic heat production (cold-induced maximal oxygen consumption, [Formula: see text]), minimize rates of heat loss (thermal conductance), or both. This can be challenging for animals living in chronically colder habitats where necessary resources (i.e., food, O2) for metabolic heat production are limited. Here we used lowland native white-footed mice (Peromyscus leucopus) and highland deer mice (P. maniculatus) native to 4300 m, to test the hypothesis that small winter-active mammals have evolved distinct cold acclimation responses to tailor their thermal physiology based on the energetic demands of their environment. We found that both species increased their [Formula: see text] after cold acclimation, associated with increases in brown adipose tissue mass and expression of uncoupling protein 1. They also broadened their thermoneutral zone to include lower ambient temperatures. This was accompanied by an increase in basal metabolic rate but only in white-footed mice, and neither species adjusted thermal conductance. Unique to highland deer mice was a mild hypothermia as ambient temperatures decreased, which reduced the gradient for heat loss, possibly to save energy in the chronically cold high alpine. These results highlight that thermal acclimation involves coordinated plasticity of numerous traits and suggest that small, winter-active mammals may adjust different aspects of their physiology in response to changing temperatures to best suit their energetic and thermoregulatory needs.
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Affiliation(s)
- Leah Hayward
- Department of Biology, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4K1, Canada
| | - Cayleih E Robertson
- Department of Biology, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4K1, Canada
| | - Grant B McClelland
- Department of Biology, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4K1, Canada.
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10
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Luna F, Okrouhlík J, McKechnie AE, Bennett NC, Šumbera R. Non‐shivering thermogenesis in four species of African mole‐rats differing in their sociality. J Zool (1987) 2021. [DOI: 10.1111/jzo.12892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- F. Luna
- Laboratorio de Ecología Fisiológica y del Comportamiento Instituto de Investigaciones Marinas y Costeras (IIMyC) CONICET‐UNMdP Mar del Plata Argentina
| | - J. Okrouhlík
- Department of Zoology Faculty of Science University of South Bohemia České Budějovice Czech Republic
- Department of Zoology and Entomology Mammal Research Institute University of Pretoria Pretoria South Africa
| | - A. E. McKechnie
- Department of Zoology and Entomology Mammal Research Institute University of Pretoria Pretoria South Africa
- South African Research Chair in Conservation Physiology South African National Biodiversity Institute Pretoria South Africa
| | - N. C. Bennett
- Department of Zoology and Entomology Mammal Research Institute University of Pretoria Pretoria South Africa
| | - R. Šumbera
- Department of Zoology Faculty of Science University of South Bohemia České Budějovice Czech Republic
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11
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Coulson SZ, Robertson CE, Mahalingam S, McClelland GB. Plasticity of non-shivering thermogenesis and brown adipose tissue in high-altitude deer mice. J Exp Biol 2021; 224:268387. [PMID: 34060604 DOI: 10.1242/jeb.242279] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 04/12/2021] [Indexed: 12/22/2022]
Abstract
High altitude environments challenge small mammals with persistent low ambient temperatures that require high rates of aerobic heat production in face of low O2 availability. An important component of thermogenic capacity in rodents is non-shivering thermogenesis (NST) mediated by uncoupled mitochondrial respiration in brown adipose tissue (BAT). NST is plastic, and capacity for heat production increases with cold acclimation. However, in lowland native rodents, hypoxia inhibits NST in BAT. We hypothesize that highland deer mice (Peromyscus maniculatus) overcome the hypoxic inhibition of NST through changes in BAT mitochondrial function. We tested this hypothesis using lab born and raised highland and lowland deer mice, and a lowland congeneric (Peromyscus leucopus), acclimated to either warm normoxia (25°C, 760 mmHg) or cold hypoxia (5°C, 430 mmHg). We determined the effects of acclimation and ancestry on whole-animal rates of NST, the mass of interscapular BAT (iBAT), and uncoupling protein (UCP)-1 protein expression. To identify changes in mitochondrial function, we conducted high-resolution respirometry on isolated iBAT mitochondria using substrates and inhibitors targeted to UCP-1. We found that rates of NST increased with cold hypoxia acclimation but only in highland deer mice. There was no effect of cold hypoxia acclimation on iBAT mass in any group, but highland deer mice showed increases in UCP-1 expression and UCP-1-stimulated mitochondrial respiration in response to these stressors. Our results suggest that highland deer mice have evolved to increase the capacity for NST in response to chronic cold hypoxia, driven in part by changes in iBAT mitochondrial function.
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Affiliation(s)
- Soren Z Coulson
- Department of Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4K1, Canada
| | - Cayleih E Robertson
- Department of Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4K1, Canada
| | - Sajeni Mahalingam
- Department of Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4K1, Canada
| | - Grant B McClelland
- Department of Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4K1, Canada
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12
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Lyons SA, Tate KB, Welch KC, McClelland GB. Lipid oxidation during thermogenesis in high-altitude deer mice ( Peromyscus maniculatus). Am J Physiol Regul Integr Comp Physiol 2021; 320:R735-R746. [PMID: 33729020 DOI: 10.1152/ajpregu.00266.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
When at their maximum thermogenic capacity (cold-induced V̇o2max), small endotherms reach levels of aerobic metabolism as high, or even higher, than running V̇o2max. How these high rates of thermogenesis are supported by substrate oxidation is currently unclear. The appropriate utilization of metabolic fuels that could sustain thermogenesis over extended periods may be important for survival in cold environments, like high altitude. Previous studies show that high capacities for lipid use in high-altitude deer mice may have evolved in concert with greater thermogenic capacities. The purpose of this study was to determine how lipid utilization at both moderate and maximal thermogenic intensities may differ in high- and low-altitude deer mice, and strictly low-altitude white-footed mice. We also examined the phenotypic plasticity of lipid use after acclimation to cold hypoxia (CH), conditions simulating high altitude. We found that lipids were the primary fuel supporting both moderate and maximal rates of thermogenesis in both species of mice. Lipid oxidation increased threefold in mice from 30°C to 0°C, consistent with increases in oxidation of [13C]palmitic acid. CH acclimation led to an increase in [13C]palmitic acid oxidation at 30°C but did not affect total lipid oxidation. Lipid oxidation rates at cold-induced V̇o2max were two- to fourfold those at 0°C and increased further after CH acclimation, especially in high-altitude deer mice. These are the highest mass-specific lipid oxidation rates observed in any land mammal. Uncovering the mechanisms that allow for these high rates of oxidation will aid our understanding of the regulation of lipid metabolism.
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Affiliation(s)
- Sulayman A Lyons
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
| | - Kevin B Tate
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
| | - Kenneth C Welch
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, Ontario, Canada
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13
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Robertson CE, McClelland GB. Ancestral and developmental cold alter brown adipose tissue function and adult thermal acclimation in Peromyscus. J Comp Physiol B 2021; 191:589-601. [PMID: 33644836 DOI: 10.1007/s00360-021-01355-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 01/09/2021] [Accepted: 02/02/2021] [Indexed: 01/21/2023]
Abstract
Small, non-hibernating endotherms increase their thermogenic capacity to survive seasonal cold, through adult phenotypic flexibility. In mammals, this response is primarily driven by remodeling of brown adipose tissue (BAT), which matures postnatally in altricial species. In many regions, ambient temperatures can vary dramatically throughout the breeding season. We used second-generation lab-born Peromyscus leucopus, cold exposed during two critical developmental windows, to test the hypothesis that adult phenotypic flexibility to cold is influenced by rearing temperature. We found that cold exposure during the postnatal period (14 °C, birth to 30 days) accelerated BAT maturation and permanently remodeled this tissue. As adults, these mice had increased BAT activity and thermogenic capacity relative to controls. However, they also had a blunted acclimation response when subsequently cold exposed as adults (5 °C for 6 weeks). Mice born to cold-exposed mothers (14 °C, entire pregnancy) also showed limited capacity for flexibility as adults, demonstrating that maternal cold stress programs the offspring thermal acclimation response. In contrast, for P. maniculatus adapted to the cold high alpine, BAT maturation rate was unaffected by rearing temperature. However, both postnatal and prenatal cold exposure limited the thermal acclimation response in these cold specialists. Our results suggest a complex interaction between developmental and adult environment, influenced strongly by ancestry, drives thermogenic capacity in the wild.
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Affiliation(s)
| | - Grant B McClelland
- Department of Biology, McMaster University, Hamilton, ON, L8S 4K1, Canada
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14
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Abstract
Population genomic studies of humans and other animals at high altitude have generated many hypotheses about the genes and pathways that may have contributed to hypoxia adaptation. Future advances require experimental tests of such hypotheses to identify causal mechanisms. Studies to date illustrate the challenge of moving from lists of candidate genes to the identification of phenotypic targets of selection, as it can be difficult to determine whether observed genotype-phenotype associations reflect causal effects or secondary consequences of changes in other traits that are linked via homeostatic regulation. Recent work on high-altitude models such as deer mice has revealed both plastic and evolved changes in respiratory, cardiovascular, and metabolic traits that contribute to aerobic performance capacity in hypoxia, and analyses of tissue-specific transcriptomes have identified changes in regulatory networks that mediate adaptive changes in physiological phenotype. Here we synthesize recent results and discuss lessons learned from studies of high-altitude adaptation that lie at the intersection of genomics and physiology.
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Affiliation(s)
- Jay F Storz
- School of Biological Sciences, University of Nebraska, Lincoln, Nebraska 68588, USA;
| | - Zachary A Cheviron
- Division of Biological Sciences, University of Montana, Missoula, Montana 59812, USA;
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15
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Robertson CE, Wilsterman K. Developmental and reproductive physiology of small mammals at high altitude: challenges and evolutionary innovations. ACTA ACUST UNITED AC 2020; 223:223/24/jeb215350. [PMID: 33443053 DOI: 10.1242/jeb.215350] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
High-altitude environments, characterized by low oxygen levels and low ambient temperatures, have been repeatedly colonized by small altricial mammals. These species inhabit mountainous regions year-round, enduring chronic cold and hypoxia. The adaptations that allow small mammals to thrive at altitude have been well studied in non-reproducing adults; however, our knowledge of adaptations specific to earlier life stages and reproductive females is extremely limited. In lowland natives, chronic hypoxia during gestation affects maternal physiology and placental function, ultimately limiting fetal growth. During post-natal development, hypoxia and cold further limit growth both directly by acting on neonatal physiology and indirectly via impacts on maternal milk production and care. Although lowland natives can survive brief sojourns to even extreme high altitude as adults, reproductive success in these environments is very low, and lowland young rarely survive to sexual maturity in chronic cold and hypoxia. Here, we review the limits to maternal and offspring physiology - both pre-natal and post-natal - that highland-adapted species have overcome, with a focus on recent studies on high-altitude populations of the North American deer mouse (Peromyscus maniculatus). We conclude that a combination of maternal and developmental adaptations were likely to have been critical steps in the evolutionary history of high-altitude native mammals.
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Affiliation(s)
| | - Kathryn Wilsterman
- Division of Biological Sciences, University of Montana, Missoula, MT 59802, USA
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16
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Grosiak M, Koteja P, Bauchinger U, Sadowska ET. Age-Related Changes in the Thermoregulatory Properties in Bank Voles From a Selection Experiment. Front Physiol 2020; 11:576304. [PMID: 33329026 PMCID: PMC7711078 DOI: 10.3389/fphys.2020.576304] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 10/09/2020] [Indexed: 01/21/2023] Open
Abstract
As with many physiological performance traits, the capacity of endotherms to thermoregulate declines with age. Aging compromises both the capacity to conserve or dissipate heat and the thermogenesis, which is fueled by aerobic metabolism. The rate of metabolism, however, not only determines thermogenic capacity but can also affect the process of aging. Therefore, we hypothesized that selection for an increased aerobic exercise metabolism, which has presumably been a crucial factor in the evolution of endothermic physiology in the mammalian and avian lineages, affects not only the thermoregulatory traits but also the age-related changes of these traits. Here, we test this hypothesis on bank voles (Myodes glareolus) from an experimental evolution model system: four lines selected for high swim-induced aerobic metabolism (A lines), which have also increased the basal, average daily, and maximum cold-induced metabolic rates, and four unselected control (C) lines. We measured the resting metabolic rate (RMR), evaporative water loss (EWL), and body temperature in 72 young adult (4 months) and 65 old (22 months) voles at seven ambient temperatures (13-32°C). The RMR was 6% higher in the A than in the C lines, but, regardless of the selection group or temperature, it did not change with age. However, EWL was 12% higher in the old voles. An increased EWL/RMR ratio implies either a compromised efficiency of oxygen extraction in the lungs or increased skin permeability. This effect was more profound in the A lines, which may indicate their increased vulnerability to aging. Body temperature did not differ between the selection and age groups below 32°C, but at 32°C it was markedly higher in the old A-line voles than in those from other groups. As expected, the thermogenic capacity, measured as the maximum cold-induced oxygen consumption, was decreased by about 13% in the old voles from both selection groups, but the performance of old A-line voles was the same as that of the young C-line ones. Thus, the selection for high aerobic exercise metabolism attenuated the adverse effects of aging on cold tolerance, but this advantage has been traded off by a compromised coping with hot conditions by aged voles.
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Affiliation(s)
- Marta Grosiak
- Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Kraków, Poland
| | - Paweł Koteja
- Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Kraków, Poland
| | - Ulf Bauchinger
- Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Kraków, Poland
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Edyta T. Sadowska
- Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Kraków, Poland
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17
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Tate KB, Wearing OH, Ivy CM, Cheviron ZA, Storz JF, McClelland GB, Scott GR. Coordinated changes across the O 2 transport pathway underlie adaptive increases in thermogenic capacity in high-altitude deer mice. Proc Biol Sci 2020; 287:20192750. [PMID: 32429808 PMCID: PMC7287372 DOI: 10.1098/rspb.2019.2750] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Accepted: 04/24/2020] [Indexed: 01/19/2023] Open
Abstract
Animals native to the hypoxic and cold environment at high altitude provide an excellent opportunity to elucidate the integrative mechanisms underlying the adaptive evolution and plasticity of complex traits. The capacity for aerobic thermogenesis can be a critical determinant of survival for small mammals at high altitude, but the physiological mechanisms underlying the evolution of this performance trait remain unresolved. We examined this issue by comparing high-altitude deer mice (Peromyscus maniculatus) with low-altitude deer mice and white-footed mice (P. leucopus). Mice were bred in captivity and adults were acclimated to each of four treatments: warm (25°C) normoxia, warm hypoxia (12 kPa O2), cold (5°C) normoxia or cold hypoxia. Acclimation to hypoxia and/or cold increased thermogenic capacity in deer mice, but hypoxia acclimation led to much greater increases in thermogenic capacity in highlanders than in lowlanders. The high thermogenic capacity of highlanders was associated with increases in pulmonary O2 extraction, arterial O2 saturation, cardiac output and arterial-venous O2 difference. Mechanisms underlying the evolution of enhanced thermogenic capacity in highlanders were partially distinct from those underlying the ancestral acclimation responses of lowlanders. Environmental adaptation has thus enhanced phenotypic plasticity and expanded the physiological toolkit for coping with the challenges at high altitude.
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Affiliation(s)
- Kevin B. Tate
- Department of Biology, McMaster University, Hamilton, ON L8S 4K1, Canada
- Department of Biology, Texas Lutheran University, Seguin, TX 78155, USA
| | - Oliver H. Wearing
- Department of Biology, McMaster University, Hamilton, ON L8S 4K1, Canada
| | - Catherine M. Ivy
- Department of Biology, McMaster University, Hamilton, ON L8S 4K1, Canada
| | - Zachary A. Cheviron
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
| | - Jay F. Storz
- School of Biological Sciences, University of Nebraska, Lincoln, NE 68588, USA
| | | | - Graham R. Scott
- Department of Biology, McMaster University, Hamilton, ON L8S 4K1, Canada
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Storz JF, Cheviron ZA, McClelland GB, Scott GR. Evolution of physiological performance capacities and environmental adaptation: insights from high-elevation deer mice ( Peromyscus maniculatus). J Mammal 2019; 100:910-922. [PMID: 31138949 DOI: 10.1093/jmammal/gyy173] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 12/14/2018] [Indexed: 12/14/2022] Open
Abstract
Analysis of variation in whole-animal performance can shed light on causal connections between specific traits, integrated physiological capacities, and Darwinian fitness. Here, we review and synthesize information on naturally occurring variation in physiological performance capacities and how it relates to environmental adaptation in deer mice (Peromyscus maniculatus). We discuss how evolved changes in aerobic exercise capacity and thermogenic capacity have contributed to adaptation to high elevations. Comparative work on deer mice at high and low elevations has revealed evolved differences in aerobic performance capacities in hypoxia. Highland deer mice have consistently higher aerobic performance capacities under hypoxia relative to lowland natives, consistent with the idea that it is beneficial to have a higher maximal metabolic rate (as measured by the maximal rate of O2 consumption, VO2max) in an environment characterized by lower air temperatures and lower O2 availability. Observed differences in aerobic performance capacities between highland and lowland deer mice stem from changes in numerous subordinate traits that alter the flux capacity of the O2-transport system, the oxidative capacity of tissue mitochondria, and the relationship between O2 consumption and ATP synthesis. Many such changes in physiological phenotype are associated with hypoxia-induced changes in gene expression. Research on natural variation in whole-animal performance forms a nexus between physiological ecology and evolutionary biology that requires insight into the natural history of the study species.
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Affiliation(s)
- Jay F Storz
- School of Biological Sciences, University of Nebraska, Lincoln, NE, USA
| | - Zachary A Cheviron
- Division of Biological Sciences, University of Montana, Missoula, MT, USA
| | | | - Graham R Scott
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
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19
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Miyano CA, Orezzoli SF, Buck CL, Nishikawa KC. Severe thermoregulatory deficiencies in mice with a deletion in the titin gene TTN. ACTA ACUST UNITED AC 2019; 222:jeb.198564. [PMID: 31015287 DOI: 10.1242/jeb.198564] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 04/10/2019] [Indexed: 12/12/2022]
Abstract
Muscular dystrophy with myositis (mdm) mice carry a deletion in the N2A region of the gene for the muscle protein titin (TTN), shiver at low frequency, fail to maintain body temperatures (T b) at ambient temperatures (T a) <34°C, and have reduced body mass and active muscle stiffness in vivo compared with wild-type (WT) siblings. Impaired shivering thermogenesis (ST) could be due to the mutated titin protein causing more compliant muscles. We hypothesized that non-shivering thermogenesis (NST) is impaired. To characterize the response to cold exposure, we measured T b and metabolic rate (MR) of WT and mdm mice at four nominal temperatures: 20, 24, 29 and 34°C. Subsequently, we stimulated NST with noradrenaline. Manipulation of T a revealed an interaction between genotype and MR: mdm mice had higher MRs at 29°C and lower MRs at 24°C compared with WT mice. NST capacity was lower in mdm mice than in WT mice. Using MR data from a previous study, we compared MR of mdm mice with MR of Perognathus longimembris, a mouse species of similar body mass. Our results indicated low MR and reduced NST of mdm mice. These were more pronounced than differences between mdm and WT mice owing to body mass effects on MR and capacity for NST. Correcting MR using Q 10 showed that mdm mice had lower MRs than size-matched P. longimembris, indicating that mutated N2A titin causes severe thermoregulatory defects at all levels. Direct effects of the titin mutation lead to lower shivering frequency. Indirect effects likely lead to a lower capacity for NST and increased thermal conductance through decreased body size.
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Affiliation(s)
- Carissa A Miyano
- Center for Bioengineering Innovation, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Santiago F Orezzoli
- Center for Bioengineering Innovation, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - C Loren Buck
- Center for Bioengineering Innovation, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Kiisa C Nishikawa
- Center for Bioengineering Innovation, Northern Arizona University, Flagstaff, AZ 86011, USA
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20
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Chen TH, Ma GC, Lin WH, Lee DJ, Wu SH, Liao BY, Chen M, Lin LK. Genome-Wide Microarray Analysis Suggests Transcriptomic Response May Not Play a Major Role in High- to Low-Altitude Acclimation in Harvest Mouse ( Micromys minutus). Animals (Basel) 2019; 9:ani9030092. [PMID: 30871279 PMCID: PMC6466072 DOI: 10.3390/ani9030092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Revised: 03/09/2019] [Accepted: 03/10/2019] [Indexed: 11/29/2022] Open
Abstract
Simple Summary Micromys minutus is a small rodent species that has a wide range of vertical distribution in Taiwan. By comparing the gene expression profile of the skeletal muscle tissues taken from individuals native to the high-altitude environment and those transferred to the low-altitude captive site, the Tnfrsf12a gene was demonstrated to have a differential expression pattern. Although this finding may be correlated with the altitude acclimation, the observation of only one gene transcript with significant alteration leads us to suggest that genetic response may not play a major role in altitude acclimation in M. minutus. Future comparative functional genomics studies involving other organ systems (in addition to skeletal muscles) and alarger sample size are warranted for better insight into the altitude acclimation of this small rodent species. Abstract The harvest mouse (Micromys minutus) is a small rodent species with a wide range of vertical distribution in Taiwan, extending from the sea level to 3100 m altitude. This species has recently suffered from habitat loss in high-altitude areas due to orchard cultivation, which may have resulted in mouse migration from high to low altitude. To investigate whether there is any physiological mechanism involved in altitude acclimation, rat cDNA microarray was used to compare transcriptomic patterns of the skeletal muscle tissues taken from individuals native to the high-altitude environment and those transferred to the low-altitude captive site. Of the 23,188 genes being analyzed, 47 (33 up-regulated and 14 down-regulated) were found to have differential expression (fold change > 4 or < −4, ANOVA p < 0.05). However, after multiple testing correction with a false discovery rate (FDR), only the result for Tnfrsf12a was found to be statistically significant (fold change = 13, FDR p < 0.05). The result was confirmed by quantitative polymerase chain reaction (q-PCR). The expression of Tnfrsf12a possibly relates to the skeletal muscle biology and thus can be correlated with altitude acclimation. However, finding only one gene transcript with significant alteration suggests that transcriptomic response may not play a major role in high- to low-altitude acclimation in harvest mouse.
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Affiliation(s)
- Tze-Ho Chen
- Department of Life Science, Tunghai University, Taichung 40704, Taiwan.
- Department of Obstetrics and Gynecology, Changhua Christian Hospital, Changhua 50006, Taiwan.
| | - Gwo-Chin Ma
- Department of Genomic Medicine and Center for Medical Genetics, Changhua Christian Hospital, Changhua 50046, Taiwan.
- Department of Genomic Science and Technology, Changhua Christian Hospital Healthcare System,Changhua Christian Hospital, Changhua 50046, Taiwan.
- Department of Medical Laboratory Science and Biotechnology, Central Taiwan University of Science and Technology, Taichung 40601, Taiwan.
| | - Wen-Hsiang Lin
- Department of Genomic Medicine and Center for Medical Genetics, Changhua Christian Hospital, Changhua 50046, Taiwan.
- Department of Genomic Science and Technology, Changhua Christian Hospital Healthcare System,Changhua Christian Hospital, Changhua 50046, Taiwan.
| | - Dong-Jay Lee
- Department of Genomic Medicine and Center for Medical Genetics, Changhua Christian Hospital, Changhua 50046, Taiwan.
- Department of Genomic Science and Technology, Changhua Christian Hospital Healthcare System,Changhua Christian Hospital, Changhua 50046, Taiwan.
| | - Sheng-Hai Wu
- Department of Life Sciences, National Chung Hsing University, Taichung 40227, Taiwan.
| | - Ben-Yang Liao
- Division of Biostatistics & Bioinformatics, Institute of Population Health Sciences, National Health Research Institutes, Zhunan, Miaoli County 35053, Taiwan.
| | - Ming Chen
- Department of Life Science, Tunghai University, Taichung 40704, Taiwan.
- Department of Genomic Medicine and Center for Medical Genetics, Changhua Christian Hospital, Changhua 50046, Taiwan.
- Department of Genomic Science and Technology, Changhua Christian Hospital Healthcare System,Changhua Christian Hospital, Changhua 50046, Taiwan.
- Department of Obstetrics and Gynecology, College of Medicine, National Taiwan University, Taipei 10041, Taiwan.
- Department of Medical Genetics, National Taiwan University Hospital, Taipei 10041, Taiwan.
- Department of Molecular Biotechnology, Da-Yeh University, Changhua 51591, Taiwan.
| | - Liang-Kong Lin
- Department of Life Science, Tunghai University, Taichung 40704, Taiwan.
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21
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Thermogenic capacity in subterranean Ctenomys: Species-specific role of thermogenic mechanisms. J Therm Biol 2019; 80:164-171. [PMID: 30784482 DOI: 10.1016/j.jtherbio.2019.01.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 01/28/2019] [Accepted: 01/28/2019] [Indexed: 11/24/2022]
Abstract
One way to understand ecological patterns of species is to determine their physiological diversity on a large geographic and/or temporal scales, in a context of hierarchical biodiversity framework. In particular, macrophysiological studies analyze how environmental factors affect the physiology and therefore the distribution of species. Subterranean species are an excellent model for evaluating the large-scale effects of ambient temperature (Ta) conditions on thermal physiology and distribution, due to their extensive use of burrows that provide a relatively thermal stable environment. Species belonging to the genus Ctenomys are all subterranean and endemic of South America. Cold induced maximum metabolic rate (MMR), basal metabolic rate (BMR) and non shivering thermogenesis (NST) were analyzed, as well as the expression of uncoupled proteins (UCP) in brown adipose tissue (BAT). Biogeographical variables appear to have no effect MMR experimentally induced by cold condition within Ctenomys. Also, mechanisms of heat production are species-specific, varying from a combination of ST and NST to a complete use of shivering mechanisms. This pattern is correlated at tissue level, since species that use only ST show a smaller interscapular BAT patch, not detectable presence of UCP1 and low COX activity. Thus, other factors, including body mass, that constrain cold induced MMR could affect thermogenic variability among Ctenomys. In the evolutionary timescale, if low O2 levels of burrows impose a ceiling in cold induced MMR, and ST is enhanced due to species-specific life history traits, such as digging effort, then the observed differences among Ctenomys species might be explained.
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Wilde LR, Wolf CJ, Porter SM, Stager M, Cheviron ZA, Senner NR. Botfly infections impair the aerobic performance and survival of montane populations of deer mice,
Peromyscus maniculatus rufinus. Funct Ecol 2019. [DOI: 10.1111/1365-2435.13276] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Luke R. Wilde
- Division of Biological Sciences University of Montana Missoula Montana
| | - Cole J. Wolf
- Division of Biological Sciences University of Montana Missoula Montana
| | - Stephanie M. Porter
- College of Veterinary Medicine and Biomedical Sciences Colorado State University Fort Collins Colorado
| | - Maria Stager
- Division of Biological Sciences University of Montana Missoula Montana
| | | | - Nathan R. Senner
- Division of Biological Sciences University of Montana Missoula Montana
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23
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McClelland GB, Scott GR. Evolved Mechanisms of Aerobic Performance and Hypoxia Resistance in High-Altitude Natives. Annu Rev Physiol 2018; 81:561-583. [PMID: 30256727 DOI: 10.1146/annurev-physiol-021317-121527] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Comparative physiology studies of high-altitude species provide an exceptional opportunity to understand naturally evolved mechanisms of hypoxia resistance. Aerobic capacity (VO2max) is a critical performance trait under positive selection in some high-altitude taxa, and several high-altitude natives have evolved to resist the depressive effects of hypoxia on VO2max. This is associated with enhanced flux capacity through the O2 transport cascade and attenuation of the maladaptive responses to chronic hypoxia that can impair O2 transport. Some highlanders exhibit elevated rates of carbohydrate oxidation during exercise, taking advantage of its high ATP yield per mole of O2. Certain highland native animals have also evolved more oxidative muscles and can sustain high rates of lipid oxidation to support thermogenesis. The underlying mechanisms include regulatory adjustments of metabolic pathways and to gene expression networks. Therefore, the evolution of hypoxia resistance in high-altitude natives involves integrated functional changes in the pathways for O2 and substrate delivery and utilization by mitochondria.
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Affiliation(s)
- Grant B McClelland
- Department of Biology, McMaster University, Hamilton, Ontario L8S 4K1, Canada;
| | - Graham R Scott
- Department of Biology, McMaster University, Hamilton, Ontario L8S 4K1, Canada;
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24
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McClelland GB, Lyons SA, Robertson CE. Fuel Use in Mammals: Conserved Patterns and Evolved Strategies for Aerobic Locomotion and Thermogenesis. Integr Comp Biol 2018; 57:231-239. [PMID: 28859408 DOI: 10.1093/icb/icx075] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
SYNOPSIS Effective aerobic locomotion depends on adequate delivery of oxygen and an appropriate allocation of metabolic substrates. The use of metabolic substrates during exercise follows a predictive pattern of lipid and carbohydrate oxidation that is similar in lowland native cursorial mammals. We have found that in two highland lineages of mice (Phyllotis and Peromyscus) the fuel use pattern is shifted to a greater reliance on carbohydrates compared to their lowland conspecifics and congenerics. However, there is variation between lineages in the importance of phenotypic plasticity in the expression of this metabolic phenotype. Moreover, this metabolic phenotype is independent of running aerobic capacity and can also be independent of thermogenic capacity. For example, wild-caught mice from a highland population of deer mice (Peromyscus maniculatus) housed in warm normoxic laboratory conditions maintain higher maximum cold-induced oxygen consumption in acute hypoxia than lowland congenerics, but shivering and non-shivering thermogenesis is supported by high rates of lipid oxidation. This is reflected in the consistently higher activities of oxidative and fatty acid oxidation enzymes in the gastrocnemius of highland deer mice compared to lowlanders, which are resistant to hypoxia acclimation. While a fixed trait in muscle aerobic capacity may reflect the pervasive and unremitting low PO2 at high altitudes, muscle capacities for substrate oxidation may be more flexible to match appropriate substrate use with changing energetic demands. How shivering thermogenesis and locomotion potentially interact in the matching of muscle metabolic capacities to appropriate substrate use is unclear. Perhaps it is possible that shivering serves as "training" to ensure muscles have the capacity to support locomotion or visa-versa.
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Affiliation(s)
- Grant B McClelland
- Department of Biology, McMaster University, Hamilton, ON, Canada L8S 4K1
| | - Sulayman A Lyons
- Department of Biology, McMaster University, Hamilton, ON, Canada L8S 4K1
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25
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Genoud M, Isler K, Martin RD. Comparative analyses of basal rate of metabolism in mammals: data selection does matter. Biol Rev Camb Philos Soc 2017; 93:404-438. [PMID: 28752629 DOI: 10.1111/brv.12350] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 05/29/2017] [Accepted: 06/05/2017] [Indexed: 12/21/2022]
Abstract
Basal rate of metabolism (BMR) is a physiological parameter that should be measured under strictly defined experimental conditions. In comparative analyses among mammals BMR is widely used as an index of the intensity of the metabolic machinery or as a proxy for energy expenditure. Many databases with BMR values for mammals are available, but the criteria used to select metabolic data as BMR estimates have often varied and the potential effect of this variability has rarely been questioned. We provide a new, expanded BMR database reflecting compliance with standard criteria (resting, postabsorptive state; thermal neutrality; adult, non-reproductive status for females) and examine potential effects of differential selectivity on the results of comparative analyses. The database includes 1739 different entries for 817 species of mammals, compiled from the original sources. It provides information permitting assessment of the validity of each estimate and presents the value closest to a proper BMR for each entry. Using different selection criteria, several alternative data sets were extracted and used in comparative analyses of (i) the scaling of BMR to body mass and (ii) the relationship between brain mass and BMR. It was expected that results would be especially dependent on selection criteria with small sample sizes and with relatively weak relationships. Phylogenetically informed regression (phylogenetic generalized least squares, PGLS) was applied to the alternative data sets for several different clades (Mammalia, Eutheria, Metatheria, or individual orders). For Mammalia, a 'subsampling procedure' was also applied, in which random subsamples of different sample sizes were taken from each original data set and successively analysed. In each case, two data sets with identical sample size and species, but comprising BMR data with different degrees of reliability, were compared. Selection criteria had minor effects on scaling equations computed for large clades (Mammalia, Eutheria, Metatheria), although less-reliable estimates of BMR were generally about 12-20% larger than more-reliable ones. Larger effects were found with more-limited clades, such as sciuromorph rodents. For the relationship between BMR and brain mass the results of comparative analyses were found to depend strongly on the data set used, especially with more-limited, order-level clades. In fact, with small sample sizes (e.g. <100) results often appeared erratic. Subsampling revealed that sample size has a non-linear effect on the probability of a zero slope for a given relationship. Depending on the species included, results could differ dramatically, especially with small sample sizes. Overall, our findings indicate a need for due diligence when selecting BMR estimates and caution regarding results (even if seemingly significant) with small sample sizes.
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Affiliation(s)
- Michel Genoud
- Department of Ecology and Evolution, University of Lausanne, CH-1015, Lausanne, Switzerland.,Division of Conservation Biology, Institute of Ecology and Evolution, Department of Biology, University of Bern, CH-3012, Bern, Switzerland
| | - Karin Isler
- Department of Anthropology, University of Zürich-Irchel, CH-8057, Zürich, Switzerland
| | - Robert D Martin
- Integrative Research Center, The Field Museum, Chicago, IL, 60605-2496, U.S.A.,Institute of Evolutionary Medicine, University of Zürich-Irchel, CH-8057, Zürich, Switzerland
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26
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Velotta JP, Jones J, Wolf CJ, Cheviron ZA. Transcriptomic plasticity in brown adipose tissue contributes to an enhanced capacity for nonshivering thermogenesis in deer mice. Mol Ecol 2016; 25:2870-86. [PMID: 27126783 DOI: 10.1111/mec.13661] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Revised: 03/04/2016] [Accepted: 04/01/2016] [Indexed: 01/08/2023]
Abstract
For small mammals living at high altitude, aerobic heat generation (thermogenesis) is essential for survival during prolonged periods of cold, but is severely impaired under conditions of hypobaric hypoxia. Recent studies in deer mice (Peromyscus maniculatus) reveal adaptive enhancement of thermogenesis in high- compared to low-altitude populations under hypoxic cold stress, an enhancement that is attributable to modifications in the aerobic metabolism of muscles used in shivering. However, because small mammals rely heavily on nonshivering mechanisms for cold acclimatization, we tested for evidence of adaptive divergence in nonshivering thermogenesis (NST) under hypoxia. To do so, we measured NST and characterized transcriptional profiles of brown adipose tissue (BAT) in high- and low-altitude deer mice that were (i) wild-caught and acclimatized to their native altitude, and (ii) born and reared under common garden conditions at low elevation. We found that NST performance under hypoxia is enhanced in wild-caught, high-altitude deer mice, a difference that is associated with increased expression of coregulated genes that influence several physiological traits. These traits include vascularization and O2 supply to BAT, brown adipocyte proliferation and the uncoupling of oxidative phosphorylation from ATP synthesis in the generation of heat. Our results suggest that acclimatization to hypoxic cold stress is facilitated by enhancement of nonshivering heat production, which is driven by regulatory plasticity in a suite of genes that influence intersecting physiological pathways.
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Affiliation(s)
- Jonathan P Velotta
- Department of Animal Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61081, USA
| | - Jennifer Jones
- Department of Animal Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61081, USA
| | - Cole J Wolf
- Department of Animal Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61081, USA
| | - Zachary A Cheviron
- Department of Animal Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61081, USA
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Scott GR, Elogio TS, Lui MA, Storz JF, Cheviron ZA. Adaptive Modifications of Muscle Phenotype in High-Altitude Deer Mice Are Associated with Evolved Changes in Gene Regulation. Mol Biol Evol 2015; 32:1962-76. [PMID: 25851956 DOI: 10.1093/molbev/msv076] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
At high-altitude, small mammals are faced with the energetic challenge of sustaining thermogenesis and aerobic exercise in spite of the reduced O2 availability. Under conditions of hypoxic cold stress, metabolic demands of shivering thermogenesis and locomotion may require enhancements in the oxidative capacity and O2 diffusion capacity of skeletal muscle to compensate for the diminished tissue O2 supply. We used common-garden experiments involving highland and lowland deer mice (Peromyscus maniculatus) to investigate the transcriptional underpinnings of genetically based population differences and plasticity in muscle phenotype. We tested highland and lowland mice that were sampled in their native environments as well as lab-raised F1 progeny of wild-caught mice. Experiments revealed that highland natives had consistently greater oxidative fiber density and capillarity in the gastrocnemius muscle. RNA sequencing analyses revealed population differences in transcript abundance for 68 genes that clustered into two discrete transcriptional modules, and a large suite of transcripts (589 genes) with plastic expression patterns that clustered into five modules. The expression of two transcriptional modules was correlated with the oxidative phenotype and capillarity of the muscle, and these phenotype-associated modules were enriched for genes involved in energy metabolism, muscle plasticity, vascular development, and cell stress response. Although most of the individual transcripts that were differentially expressed between populations were negatively correlated with muscle phenotype, several genes involved in energy metabolism (e.g., Ckmt1, Ehhadh, Acaa1a) and angiogenesis (Notch4) were more highly expressed in highlanders, and the regulators of mitochondrial biogenesis, PGC-1α (Ppargc1a) and mitochondrial transcription factor A (Tfam), were positively correlated with muscle oxidative phenotype. These results suggest that evolved population differences in the oxidative capacity and capillarity of skeletal muscle involved expression changes in a small suite of coregulated genes.
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Affiliation(s)
- Graham R Scott
- Department of Biology, McMaster University, Hamilton, ON, Canada
| | - Todd S Elogio
- Department of Biology, McMaster University, Hamilton, ON, Canada
| | - Mikaela A Lui
- Department of Biology, McMaster University, Hamilton, ON, Canada
| | - Jay F Storz
- School of Biological Sciences, University of Nebraska, Lincoln
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Stawski C, Koteja P, Sadowska ET, Jefimow M, Wojciechowski MS. Selection for high activity-related aerobic metabolism does not alter the capacity of non-shivering thermogenesis in bank voles. Comp Biochem Physiol A Mol Integr Physiol 2014; 180:51-6. [PMID: 25446149 DOI: 10.1016/j.cbpa.2014.11.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Revised: 10/31/2014] [Accepted: 11/02/2014] [Indexed: 12/22/2022]
Abstract
An intriguing question is how the capacity of non-shivering thermogenesis (NST)-a special mechanism supporting endothermic thermoregulation in mammals-is affected by selection for high exercise metabolism. It has been proposed that high NST could be a mechanism to compensate for a low basal production of heat. On the other hand, high basal or activity metabolism is associated with physiological characteristics such as high performance of the circulatory system, which are also required for achieving a high NST. Here we tested whether selection for high aerobic exercise performance, which correlates with an increased basal metabolic rate, led to a correlated evolution of maximum and facultative NST. Therefore, we measured the NST of bank voles, Myodes (= Clethrionomys) glareolus, from lines selected for 13-14 generations (n=46) for high aerobic metabolism achieved during swimming and from unselected, control lines (n=46). Open-flow respirometry was used to measure the rate of oxygen consumption (V(·)O2) in anesthetized bank voles injected with noradrenaline (NA). After adjusting for body mass, maximum NST (maximum V(·)O2 recorded after injection of NA) did not differ between the selected (2.38±0.08 mLO2min(-1)) and control lines (2.36±0.08 mLO2min(-1); P=0.891). Facultative NST (= maximum NST minus resting metabolic rate of anesthetized animals) did not differ between the selected (1.49±0.07 mLO2min(-1)) and control lines (1.50±0.07 mLO2min(-1); P=0.985), either. Therefore, our results suggest that NST capacity is not strongly linked to maximum activity-related aerobic metabolic rate.
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Affiliation(s)
- Clare Stawski
- Institute of Environmental Sciences, Jagiellonian University, ul. Gronostajowa 7, 30-387 Kraków, Poland.
| | - Paweł Koteja
- Institute of Environmental Sciences, Jagiellonian University, ul. Gronostajowa 7, 30-387 Kraków, Poland
| | - Edyta T Sadowska
- Institute of Environmental Sciences, Jagiellonian University, ul. Gronostajowa 7, 30-387 Kraków, Poland
| | - Małgorzata Jefimow
- Department of Animal Physiology, Nicolaus Copernicus University, ul. Lwowska 1, 87-100 Toruń, Poland
| | - Michał S Wojciechowski
- Department of Animal Physiology, Nicolaus Copernicus University, ul. Lwowska 1, 87-100 Toruń, Poland
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Cortés PA, Franco M, Moreno-Gómez FN, Barrientos K, Nespolo RF. Thermoregulatory capacities and torpor in the South American marsupial, Dromiciops gliroides. J Therm Biol 2014; 45:1-8. [DOI: 10.1016/j.jtherbio.2014.07.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 07/03/2014] [Accepted: 07/03/2014] [Indexed: 10/25/2022]
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Shirkey NJ, Hammond KA. The relationship between cardiopulmonary size and aerobic performance in adult deer mice at high altitude. ACTA ACUST UNITED AC 2014; 217:3758-64. [PMID: 25147245 DOI: 10.1242/jeb.103713] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Deer mice (Peromyscus maniculatus sonoriensis) populations in the White Mountains of Eastern California are found across a substantial range of partial pressures of oxygen (PO₂). Reduction in PO₂ at high altitude can have a negative impact on aerobic performance. We studied plastic changes in organ mass and volume involved in aerobic respiration in response to acclimation to high altitude, and how those changes are matched with aerobic performance measured by VO₂,max. Adult deer mice born and raised at 340 m were acclimated at either 340 or 3800 m for a period of 9 weeks. Lung volume increased by 9% in mice acclimated to high altitude. VO₂,max was also significantly higher under hypoxic conditions after high altitude acclimation compared with controls. Body mass-corrected residuals of VO₂,max were significantly correlated with an index of cardiopulmonary size (summed standardized residuals of lung volume and heart mass) under both hypoxic and normoxic conditions. These data show that phenotypic plasticity in lung volume and heart mass plays an important role in maintaining aerobic performance under hypoxic conditions, and accounts for up to 55% of the variance in aerobic performance.
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Affiliation(s)
- Nicholas J Shirkey
- Department of Biology, University of California, Riverside, Riverside, CA 92521, USA
| | - Kimberly A Hammond
- Department of Biology, University of California, Riverside, Riverside, CA 92521, USA
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Cheviron ZA, Connaty AD, McClelland GB, Storz JF. Functional genomics of adaptation to hypoxic cold-stress in high-altitude deer mice: transcriptomic plasticity and thermogenic performance. Evolution 2013; 68:48-62. [PMID: 24102503 DOI: 10.1111/evo.12257] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Accepted: 08/16/2013] [Indexed: 12/14/2022]
Abstract
In species that are distributed across steep environmental gradients, adaptive variation in physiological performance may be attributable to transcriptional plasticity in underlying regulatory networks. Here we report the results of common-garden experiments that were designed to elucidate the role of regulatory plasticity in evolutionary adaptation to hypoxic cold-stress in deer mice (Peromyscus maniculatus). We integrated genomic transcriptional profiles with measures of metabolic enzyme activities and whole-animal thermogenic performance under hypoxia in highland (4350 m) and lowland (430 m) mice from three experimental groups: (1) wild-caught mice that were sampled at their native elevations; (2) wild-caught/lab-reared mice that were deacclimated to low-elevation conditions in a common-garden lab environment; and (3) the F(1) progeny of deacclimated mice that were maintained under the same low-elevation common-garden conditions. In each experimental group, highland mice exhibited greater thermogenic capacities than lowland mice, and this enhanced performance was associated with upregulation of transcriptional modules that influence several hierarchical steps in the O(2) cascade, including tissue O(2) diffusion (angiogenesis) and tissue O(2) utilization (metabolic fuel use and cellular oxidative capacity). Most of these performance-related transcriptomic changes occurred over physiological and developmental timescales, suggesting that regulatory plasticity makes important contributions to fitness-related physiological performance in highland deer mice.
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Affiliation(s)
- Zachary A Cheviron
- Department of Animal Biology, University of Illinois, 515 Morrill Hall, 505 S. Goodwin Avenue, Urbana, Illinois, 61801.
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Cheviron ZA, Bachman GC, Storz JF. Contributions of phenotypic plasticity to differences in thermogenic performance between highland and lowland deer mice. ACTA ACUST UNITED AC 2012. [PMID: 23197099 DOI: 10.1242/jeb.075598] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Small mammals face especially severe thermoregulatory challenges at high altitude because the reduced O2 availability constrains the capacity for aerobic thermogenesis. Adaptive enhancement of thermogenic performance under hypoxic conditions may be achieved via physiological adjustments that occur within the lifetime of individuals (phenotypic plasticity) and/or genetically based changes that occur across generations, but their relative contributions to performance differences between highland and lowland natives are unclear. Here, we examined potentially evolved differences in thermogenic performance between populations of deer mice (Peromyscus maniculatus) that are native to different altitudes. The purpose of the study was to assess the contribution of phenotypic plasticity to population differences in thermogenic performance under hypoxia. We used a common-garden deacclimation experiment to demonstrate that highland deer mice have enhanced thermogenic capacities under hypoxia, and that performance differences between highland and lowland mice persist when individuals are born and reared under common-garden conditions, suggesting that differences in thermogenic capacity have a genetic basis. Conversely, population differences in thermogenic endurance appear to be entirely attributable to physiological plasticity during adulthood. These combined results reveal distinct sources of phenotypic plasticity for different aspects of thermogenic performance, and suggest that thermogenic capacity and endurance may have different mechanistic underpinnings.
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Affiliation(s)
- Zachary A Cheviron
- School of Biological Sciences, University of Nebraska, Lincoln, NE 68588, USA.
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Zhang L, Zhu W, Wang Z. Role of photoperiod on hormone concentrations and adaptive capacity in tree shrews, Tupaia belangeri. Comp Biochem Physiol A Mol Integr Physiol 2012; 163:253-9. [PMID: 22955104 DOI: 10.1016/j.cbpa.2012.08.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Revised: 08/22/2012] [Accepted: 08/22/2012] [Indexed: 01/23/2023]
Abstract
Environmental factors, such as photoperiod and temperature, play an important role in the regulation of an animal's physiology and behavior. In the present study, we examined the effects of short photoperiod (SD, 8L:16D) on body mass as well as on several physiological, hormonal, and biochemical measures indicative of thermogenic capacity, to test our hypothesis that short photoperiod stimulates increases thermogenic capacity and energy intake in tree shrews. At the end, these tree shrews (SD) had a significant higher body mass, energy intake, cytochrome C oxidase (COX) activity and uncoupling protein-1 (UCP1) content, serum tri-iodothyronine (T(3)) and thyroxine (T(4)) compared to LD (16L:8D) tree shrews. However, there were no significant differences in serum leptin and melatonin between the two groups. Together, these data suggest tree shrews employ a strategy of maximizing body growth and increasing energy intake in response to cues associated with short photoperiod.
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Affiliation(s)
- Lin Zhang
- School of Life Sciences, Yunnan Normal University, Kunming 650500, People's Republic of China.
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Regulatory changes contribute to the adaptive enhancement of thermogenic capacity in high-altitude deer mice. Proc Natl Acad Sci U S A 2012; 109:8635-40. [PMID: 22586089 DOI: 10.1073/pnas.1120523109] [Citation(s) in RCA: 137] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In response to hypoxic stress, many animals compensate for a reduced cellular O(2) supply by suppressing total metabolism, thereby reducing O(2) demand. For small endotherms that are native to high-altitude environments, this is not always a viable strategy, as the capacity for sustained aerobic thermogenesis is critical for survival during periods of prolonged cold stress. For example, survivorship studies of deer mice (Peromyscus maniculatus) have demonstrated that thermogenic capacity is under strong directional selection at high altitude. Here, we integrate measures of whole-organism thermogenic performance with measures of metabolic enzyme activities and genomic transcriptional profiles to examine the mechanistic underpinnings of adaptive variation in this complex trait in deer mice that are native to different elevations. We demonstrate that highland deer mice have an enhanced thermogenic capacity under hypoxia compared with lowland conspecifics and a closely related lowland species, Peromyscus leucopus. Our findings suggest that the enhanced thermogenic performance of highland deer mice is largely attributable to an increased capacity to oxidize lipids as a primary metabolic fuel source. This enhanced capacity for aerobic thermogenesis is associated with elevated activities of muscle metabolic enzymes that influence flux through fatty-acid oxidation and oxidative phosphorylation pathways in high-altitude deer mice and by concomitant changes in the expression of genes in these same pathways. Contrary to predictions derived from studies of humans at high altitude, our results suggest that selection to sustain prolonged thermogenesis under hypoxia promotes a shift in metabolic fuel use in favor of lipids over carbohydrates.
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35
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Yang DB, Xu YC, Wang DH. Partial removal of brown adipose tissue enhances humoral immunity in warm-acclimated Mongolian gerbils (Meriones unguiculatus). Gen Comp Endocrinol 2012; 175:144-52. [PMID: 22080042 DOI: 10.1016/j.ygcen.2011.10.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Revised: 10/21/2011] [Accepted: 10/25/2011] [Indexed: 11/28/2022]
Abstract
Temperate rodent species experience marked seasonal fluctuations in environmental temperatures. High thermoregulatory demands during winter usually weaken immune function. Brown adipose tissue (BAT) plays a crucial role in adaptive thermoregulatory process. Thus, we proposed the hypothesis that BAT might participate in the regulation of seasonal changes in immune function. The present study examined the trade-off between thermoregulation and immune function and the potential role of BAT in regulating seasonal changes in immune function in Mongolian gerbils. Specifically, surgical removal of interscapular BAT (34% of total BAT) was performed in male gerbils, and subsequently acclimated to either warm (23 ± 1 °C) or cold (4 ± 1 °C) conditions. Gerbils were then challenged with innocuous antigens and the immune responses were measured. Resting metabolic rate (RMR) and nonshivering thermogenesis (NST) were increased under cold conditions. However, the cost of thermoregulation during cold acclimation did not suppress T-cell mediated immunity and humoral immunity or decrease spleen mass, thymus mass and white blood cells. Partial removal of BAT significantly enhanced humoral immunity in warm-acclimated, but not in cold-acclimated gerbils. T-cell mediated immunity, white blood cells and immune organs were not affected by BAT removal under both warm and cold conditions. Collectively, our results imply that BAT has a suppressive effect on humoral immunity in warm-acclimated gerbils and differential effects of BAT on humoral immunity under different temperatures (e.g., summer and winter) might be benefit to their survival.
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Affiliation(s)
- Deng-Bao Yang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
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36
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Mineo PM, Cassell EA, Roberts ME, Schaeffer PJ. Chronic cold acclimation increases thermogenic capacity, non-shivering thermogenesis and muscle citrate synthase activity in both wild-type and brown adipose tissue deficient mice. Comp Biochem Physiol A Mol Integr Physiol 2011; 161:395-400. [PMID: 22233932 DOI: 10.1016/j.cbpa.2011.12.012] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Revised: 10/31/2011] [Accepted: 12/20/2011] [Indexed: 10/14/2022]
Abstract
The purpose of this study was to determine whether chronic cold exposure would increase the aerobic capacity of skeletal muscle in UCP-dta mice, a transgenic line lacking brown adipose tissue (BAT). Wild type and UCP-dta mice were acclimated to either warm (23 °C), or cold (4 °C) conditions. Cold increased muscle oxidative capacity nearly equivalently in wild-type and UCP-dta mice, but did not affect the respiratory function of isolated mitochondria. Summit metabolism ( ̇V O2summit) and norepinephrine-induced thermogenesis ( ̇V O2NST) were significantly lower in UCP-dta mice relative to wild-type mice regardless of temperature treatment, but both were significantly higher in cold relative to warm acclimated mice. BAT mass was significantly higher in the cold relative to warm acclimated wild-type mice, but not in cold acclimated UCP-dta mice. BAT citrate synthase activity was lower in transgenic animals regardless of acclimation temperature and BAT citrate synthase activity per depot was significantly higher only in the cold acclimated wild-type mice. Muscle citrate synthase activity was increased in both genotypes. As defects in muscle oxidative function have been observed with obesity and type 2 diabetes, these results suggest that chronic cold exposure is a useful intervention to drive skeletal muscle oxidative capacity in mouse models of obesity.
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Affiliation(s)
- P M Mineo
- Department of Zoology, Miami University, Oxford, OH 45056, USA
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37
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Variations in thermal physiology and energetics of the tree shrew (Tupaia belangeri) in response to cold acclimation. J Comp Physiol B 2011; 182:167-76. [DOI: 10.1007/s00360-011-0606-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2010] [Revised: 07/26/2011] [Accepted: 07/28/2011] [Indexed: 10/17/2022]
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38
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Almeida MC, Cruz-Neto AP. Thermogenic capacity of three species of fruit-eating phyllostomid bats. J Therm Biol 2011. [DOI: 10.1016/j.jtherbio.2011.03.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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39
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Chi QS, Wang DH. Thermal physiology and energetics in male desert hamsters (Phodopus roborovskii) during cold acclimation. J Comp Physiol B 2010; 181:91-103. [PMID: 20714728 DOI: 10.1007/s00360-010-0506-6] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2010] [Revised: 07/23/2010] [Accepted: 07/28/2010] [Indexed: 12/26/2022]
Abstract
The adjustments in thermal physiology and energetics were investigated in male desert hamsters (Phodopus roborovskii) which were acclimated to 5°C for 4 weeks. Mean core body temperature in cold acclimated animals decreased by 0.21°C compared with controls. Further analysis revealed that the decrease mainly occurred in the scotophase, while in the photophase core body temperature remained constant during the whole cold acclimation. Thermogenic capacity, represented by resting metabolic rate and nonshivering thermogenesis increased in cold acclimated hamsters from initial values of 1.38 ± 0.05 and 5.32 ± 0.30 to 1.77 ± 0.08 and 8.79 ± 0.31 mlO(2) g(-1) h(-1), respectively. After cold acclimation, desert hamsters maintained a relative stable body mass of 21.7 ± 0.1 g very similar to the controls kept at 23°C (21.8 ± 0.1 g). The mean values of food intake and digestible energy (metabolisable energy) in cold acclimated hamsters were 5.3 ± 0.1 g day(-1) and 76.3 ± 0.9 kJ day(-1) (74.8 ± 0.9), respectively, which were significantly elevated by 76.7 and 80.4% compared to that in control group. The apparent digestibility was 81.0 ± 0.3% in cold acclimated animals which was also higher than the 79.7 ± 0.2% observed in controls. This increase corresponded with adaptive adjustments in morphology of digestive tracts with 20.2 and 36.8% increases in total length and wet mass, respectively. Body fat mass and serum leptin levels in cold acclimated hamsters decreased by 40.7 and 67.1%, respectively. The wheel running turns and the onset of wheel running remained unchanged. Our study indicated that desert hamsters remained very active during cold acclimation and displayed adaptive changes in thermal physiology and energy metabolism, such as enhanced thermogenic and energy processing capacities.
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Affiliation(s)
- Qing-Sheng Chi
- State Key Laboratory of Integrated Management for Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.
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40
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Rezende EL, Hammond KA, Chappell MA. Cold acclimation in Peromyscus: individual variation and sex effects in maximum and daily metabolism, organ mass and body composition. ACTA ACUST UNITED AC 2009; 212:2795-802. [PMID: 19684213 DOI: 10.1242/jeb.032789] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We studied metabolic and organ mass responses to thermal acclimation (7 weeks at 5 degrees C or 23 degrees C) in deer mice, Peromyscus maniculatus. Cold acclimation resulted in significantly higher maximal oxygen consumption in thermogenesis (V(O(2)max)) and daily mean oxygen consumption (V(O(2)mean)), an increase in the mass of most visceral organs, a lower absolute body fat and a marginally significant increase in hematocrit. The mass of digestive organs and body fat content differed significantly between sexes. Acclimation effects on fat content were more pronounced in females. Variation in heart and lung mass was positively correlated with V(O(2)max) and V(O(2)mean), while body fat content was negatively correlated with both traits. Nonetheless, a large fraction of the metabolic difference between cold- and warm-acclimated groups remained unexplained. Associations between traits at lower levels of biological organization measured here and whole-organism energetics remained consistent across acclimation temperatures, except for the correlation between kidney mass and V(O(2)mean), which was positive and significant in cold acclimation and negligible following warm acclimation. We conclude that: (1) V(O(2)max) and V(O(2)mean) share a common physiological basis that remains overall the same across acclimation regimes; (2) changes in these traits are associated primarily with changes in heart mass; and (3) male and female deer mice respond differently to thermal acclimation, possibly due to differences in reproductive allocation.
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Affiliation(s)
- Enrico L Rezende
- Departament de Genètica i de Microbiologia, Facultat de Biociències, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain.
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