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heat acclimation and acclimatization

Oliver R Gibson, Lee Taylor, Peter W Watt, Neil S Maxwell
To prepare for extremes of heat, cold or low partial pressures of oxygen (O2), humans can undertake a period of acclimation or acclimatization to induce environment-specific adaptations, e.g. heat acclimation (HA), cold acclimation (CA), or altitude training. While these strategies are effective, they are not always feasible due to logistical impracticalities. Cross-adaptation is a term used to describe the phenomenon whereby alternative environmental interventions, e.g. HA or CA, may be a beneficial alternative to altitude interventions, providing physiological stress and inducing adaptations observable at altitude...
April 7, 2017: Sports Medicine
Gonzalo Barceló, Oliver P Love, François Vézina
Avian basal metabolic rate (BMR) and summit metabolic rate (Msum) vary in parallel during cold acclimation and acclimatization, which implies a functional link between these variables. However, evidence suggests that these parameters may reflect different physiological systems acting independently. We tested this hypothesis in white-throated sparrows (Zonotrichia albicollis) acclimated to two temperatures (-8° and 28°C) and two diets (0% and 30% cellulose). We expected to find an uncoupling of Msum and BMR where Msum, a measure of maximal shivering heat production, would reflect muscle and heart mass variation and would respond only to temperature, while BMR would reflect changes in digestive and excretory organs in response to daily food intake, responding to both temperature and diet...
March 2017: Physiological and Biochemical Zoology: PBZ
Arabinda Mahanty, Gopal Krishna Purohit, Ravi Prakash Yadav, Sasmita Mohanty, Bimal Prasanna Mohanty
Changes in the expression of a number of hsp genes in minnow Puntius sophore collected from a hot spring run-off (Atri hot spring in Odisha, India; 20(o)09'N 85(°)18'E, 36-38 °C) were investigated to study the upper thermal acclimation response under heat stress, using same species from aquaculture ponds (water temperature 27 °C) as control. Expression of hsp genes was analyzed in both groups using RT-qPCR, which showed up-regulation of hsp90 (2.1-fold) and hsp47 (2.5-fold) in hot spring run-off fishes, whereas there was no alteration in expression of other hsps...
February 2017: Fish Physiology and Biochemistry
John W Castellani, Andrew J Young
Cold exposure in humans causes specific acute and chronic physiological responses. This paper will review both the acute and long-term physiological responses and external factors that impact these physiological responses. Acute physiological responses to cold exposure include cutaneous vasoconstriction and shivering thermogenesis which, respectively, decrease heat loss and increase metabolic heat production. Vasoconstriction is elicited through reflex and local cooling. In combination, vasoconstriction and shivering operate to maintain thermal balance when the body is losing heat...
April 2016: Autonomic Neuroscience: Basic & Clinical
Flávio G Oliveira, Joaquim T Tapisso, Rita I Monarca, Ana M Cerveira, Maria L Mathias
The balance between energetic acquisition and expenditure depends on the amount of energy allocated to biological functions such as thermoregulation, growth, reproduction and behavior. Ambient temperature has a profound effect on this balance, with species inhabiting colder climates often needing to invest more energy in thermoregulation to maintain body temperature. This leads to local behavioral and physiological adaptations that increase energetic efficiency. In this study, we investigated the role of activity, behavior and thermogenic capacity in the ability of the greater white-toothed shrew, Crocidura russula, to cope with seasonal changes...
February 2016: Journal of Thermal Biology
Jan S Boratyński, Małgorzata Jefimow, Michał S Wojciechowski
As photoperiod shortens with the approach of winter, small mammals should reduce their energy expenditure to survive periods of food limitation. However, within seasons, animals should balance their energy budgets as abiotic conditions change, sometimes unpredictably; cold spells should increase heat production, while warm spells should do the opposite. Therefore, we addressed specific questions about the possible interactions between seasonal acclimatization and the intra-seasonal phenotypic flexibility of metabolic rate...
April 2016: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
Cyril Schmit, Rob Duffield, Christophe Hausswirth, Aaron J Coutts, Yann Le Meur
PURPOSE: To describe the effect of the initial perceptual experience from heat familiarization on the pacing profile during a freepaced endurance time trial (TT) compared with temperate conditions. METHODS: Two groups of well-trained triathletes performed two 20-km TTs in either hot (35°C and 50% relative humidity [RH], n = 12) or temperate (21°C and 50% RH, n = 22) conditions, after standardization of training for each group before both trials. To ensure no physiological acclimation differences between conditions, the TTs for both groups were separated by 11 ± 4 d...
October 2016: International Journal of Sports Physiology and Performance
M J Zurawlew, N P Walsh, M B Fortes, C Potter
We examined whether daily hot water immersion (HWI) after exercise in temperate conditions induces heat acclimation and improves endurance performance in temperate and hot conditions. Seventeen non-heat-acclimatized males performed a 6-day intervention involving a daily treadmill run for 40 min at 65% V̇O2max in temperate conditions (18 °C) followed immediately by either HWI (N = 10; 40 °C) or thermoneutral (CON, N = 7; 34 °C) immersion for 40 min. Before and after the 6-day intervention, participants performed a treadmill run for 40 min at 65% V̇O2max followed by a 5-km treadmill time trial (TT) in temperate (18 °C, 40% humidity) and hot (33 °C, 40% humidity) conditions...
July 2016: Scandinavian Journal of Medicine & Science in Sports
E Gnaiger, R Boushel, H Søndergaard, T Munch-Andersen, R Damsgaard, C Hagen, C Díez-Sánchez, I Ara, C Wright-Paradis, P Schrauwen, M Hesselink, J A L Calbet, M Christiansen, J W Helge, B Saltin
During evolution, mitochondrial DNA haplogroups of arctic populations may have been selected for lower coupling of mitochondrial respiration to ATP production in favor of higher heat production. We show that mitochondrial coupling in skeletal muscle of traditional and westernized Inuit habituating northern Greenland is identical to Danes of western Europe haplogroups. Biochemical coupling efficiency was preserved across variations in diet, muscle fiber type, and uncoupling protein-3 content. Mitochondrial phenotype displayed plasticity in relation to lifestyle and environment...
December 2015: Scandinavian Journal of Medicine & Science in Sports
J A Loeppky
PURPOSE: The reported magnitude of plasma volume increase (Δ%PV) following heat acclimation (HA) varies widely. Variations may result from differences in measurement techniques, season and subjects' fitness. This report compares direct and indirect measurements of Δ%PV after 10 days of HA from studies in winter (WIN, n = 8) and summer (SUM, n = 10) in men, age 21-43 yr, at two fitness levels (VO(2)max: 35 and 51 ml/min/kg). Direct measurements were made before and after HA (cycling at 30% of VO(2)max at 50 °C, for 100 min/day) by carbon monoxide (CO) rebreathing and compared with indirect estimates from changes in hematocrit, hemoglobin and plasma protein concentration...
September 2015: Acta Physiologica Hungarica
Michal Horowitz
Studying "phenotypic plasticity" involves comparison of traits expressed in response to environmental fluctuations and aims to understand tolerance and survival in new settings. Reversible phenotypic changes that enable individuals to match their phenotype to environmental demands throughout life can be artificially induced, i.e., acclimation or occur naturally, i.e., acclimatization. The onset and achievement of acclimatory homeostasis are determined by molecular programs that induce the acclimated transcriptome...
March 15, 2016: Journal of Applied Physiology
Satyaveer Singh Dangi, Saroj K Dangi, V S Chouhan, M R Verma, Puneet Kumar, Gyanendra Singh, Mihir Sarkar
Changing climatic scenario with expected global rise in surface temperature compelled more focus of research over decoding heat stress response mechanism of animals and mitigation of heat stress. Recently betaine, a trimethyl form of glycine has been found to ameliorate heat stress in some species of animals. To overcome deleterious effect of heat stress, an attempt was taken to investigate the effect of betaine supplementation on heat stress mitigation in goats. Eighteen female Barbari goats were taken and randomly divided into 3 groups (n=6) such as control, HS (Heat stressed), HS+B (Heat stressed administered with betaine)...
January 10, 2016: Gene
Lisa M Komoroske, Richard E Connon, Ken M Jeffries, Nann A Fangue
Forecasting species' responses to climate change requires understanding the underlying mechanisms governing environmental stress tolerance, including acclimation capacity and acute stress responses. Current knowledge of these physiological processes in aquatic ectotherms is largely drawn from eurythermal or extreme stenothermal species. Yet many species of conservation concern exhibit tolerance windows and acclimation capacities in between these extremes. We linked transcriptome profiles to organismal tolerance in a mesothermal endangered fish, the delta smelt (Hypomesus transpacificus), to quantify the cellular processes, sublethal thresholds and effects of thermal acclimation on acute stress responses...
October 2015: Molecular Ecology
Zhenshan Liu, Mingming Xin, Jinxia Qin, Huiru Peng, Zhongfu Ni, Yingyin Yao, Qixin Sun
BACKGROUND: Hexaploid wheat (Triticum aestivum) is a globally important crop. Heat, drought and their combination dramatically reduce wheat yield and quality, but the molecular mechanisms underlying wheat tolerance to extreme environments, especially stress combination, are largely unknown. As an allohexaploid, wheat consists of three closely related subgenomes (A, B, and D), and was reported to show improved tolerance to stress conditions compared to tetraploid. But so far very little is known about how wheat coordinates the expression of homeologous genes to cope with various environmental constraints on the whole-genome level...
2015: BMC Plant Biology
Mads Fristrup Schou, Volker Loeschcke, Torsten Nygaard Kristensen
Studies on thermal acclimation in insects are often performed on animals acclimated in the laboratory under conditions that are not ecologically relevant. Costs and benefits of acclimation responses under such conditions may not reflect costs and benefits in natural populations subjected to daily and seasonal temperature fluctuations. Here we estimated costs and benefits in thermal tolerance limits in relation to winter acclimatization of Drosophila melanogaster. We sampled flies from a natural habitat during winter in Denmark (field flies) and compared heat and cold tolerance of these to that of flies collected from the same natural population, but acclimated to 25 °C or 13 °C in the laboratory (laboratory flies)...
2015: PloS One
Tomáš Štětina, Vladimír Koštál, Jaroslava Korbelová
BACKGROUND: The ubiquitous occurrence of inducible Heat Shock Proteins (Hsps) up-regulation in response to cold-acclimation and/or to cold shock, including massive increase of Hsp70 mRNA levels, often led to hasty interpretations of its role in the repair of cold injury expressed as protein denaturation or misfolding. So far, direct functional analyses in Drosophila melanogaster and other insects brought either limited or no support for such interpretations. In this paper, we analyze the cold tolerance and the expression levels of 24 different mRNA transcripts of the Hsps complex and related genes in response to cold in two strains of D...
2015: PloS One
Alex R Gunderson, Jonathon H Stillman
Global warming is increasing the overheating risk for many organisms, though the potential for plasticity in thermal tolerance to mitigate this risk is largely unknown. In part, this shortcoming stems from a lack of knowledge about global and taxonomic patterns of variation in tolerance plasticity. To address this critical issue, we test leading hypotheses for broad-scale variation in ectotherm tolerance plasticity using a dataset that includes vertebrate and invertebrate taxa from terrestrial, freshwater and marine habitats...
June 7, 2015: Proceedings. Biological Sciences
Rachael A Bay, Stephen R Palumbi
Population response to environmental variation involves adaptation, acclimation, or both. For long-lived organisms, acclimation likely generates a faster response but is only effective if the rates and limits of acclimation match the dynamics of local environmental variation. In coral reef habitats, heat stress from extreme ocean warming can occur over several weeks, resulting in symbiont expulsion and widespread coral death. However, transcriptome regulation during short-term acclimation is not well understood...
June 2015: Genome Biology and Evolution
Stephanie P Mueller, Daniel M Krause, Martin J Mueller, Agnes Fekete
Heat acclimation enables plants to tolerate and survive short-term heat stress on hot days. In Arabidopsis thaliana, a genetically programmed heat shock response can be rapidly triggered in the temperature range of 32-38°C through activation of heat shock transcription factors (HSF). The heat shock response leads to heat acclimation and confers short-term protection against temperatures above 40°C. However, little is known about metabolic adjustments during heat acclimation.Untargeted metabolite analyses of A...
August 2015: Journal of Experimental Botany
Yong Long, Junjun Yan, Guili Song, Xiaohui Li, Xixi Li, Qing Li, Zongbin Cui
BACKGROUND: Hypoxia and temperature stress are two major adverse environmental conditions often encountered by fishes. The interaction between hypoxia and temperature stresses has been well documented and oxygen is considered to be the limiting factor for the thermal tolerance of fish. Although both high and low temperature stresses can impair the cardiovascular function and the cross-resistance between hypoxia and heat stress has been found, it is not clear whether hypoxia acclimation can protect fish from cold injury...
May 15, 2015: BMC Genomics
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