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Heat acclimation

Silva Suvi, Martin Mooses, Saima Timpmann, Luule Medijainen, Daria Narõškina, Eve Unt, Vahur Ööpik
The purpose of this study was to assess the impact of sodium citrate (CIT) ingestion (600 mg·kg<sup>‒1</sup>) during recovery from dehydrating cycling exercise (DE) on subsequent 40-km cycling performance in a warm environment (32 °C). Twenty male non-heat-acclimated endurance athletes exercised in the heat until 4% body mass (BM) loss occurred. After 16 h recovery with consumption of water ad libitum and prescribed diet (evening meal 20 kcal·kg<sup>‒1</sup>, breakfast 12 kcal·kg<sup>‒1</sup>) supplemented in a double-blind, randomized, crossover manner with CIT or placebo (PLC), they performed 40-km time-trial (TT) on a cycle ergometer in a warm environment...
January 11, 2018: Applied Physiology, Nutrition, and Metabolism, Physiologie Appliquée, Nutrition et Métabolisme
Kentaro Matsuzaki, Naotoshi Sugimoto, Masanori Katakura, Eri Sumiyoshi, Toshiko Hara, Michio Hashimoto, Osamu Shido
Saliva-a water-based fluid containing electrolytes, immunoglobulins, and enzymes-has many functions, including the protection and hydration of mucosal structures within the oral cavity and the initiation of digestion. Aquaporins (AQPs) are proteins that act as water channels through membranes. We have previously reported upregulation of the expression levels of AQP 1 and 5 in the submandibular glands (SMGs) in heat-acclimated rats. In this study, we investigated pilocarpine-induced saliva secretion and AQP expression in rats after voluntary exercise...
January 2018: FEBS Open Bio
Brett R Ely, Laurie A Blanchard, Jared R Steele, Michael A Francisco, Samuel N Cheuvront, Christopher T Minson
Heat acclimation is the best strategy to improve performance in a hot environment. Many athletes seeking the benefits of heat acclimation lack access to a hot environment for exercise, and thus rely on over-dressing to simulate environmental heat stress. It is currently unknown whether this approach produces the requisite thermoregulatory strain necessary for heat acclimation in trained men and women. PURPOSE: To compare physiological and cellular responses to exercise in a hot environment (HOT; 40°C, 30%rh) with minimal clothing (clo= 0...
January 9, 2018: Medicine and Science in Sports and Exercise
Lingling Zhu, Keith J Bloomfield, Charles H Hocart, John J G Egerton, Odhran S O'Sullivan, Aurore Penillard, Lasantha K Weerasinghe, Owen K Atkin
In many biomes, plants are subject to heat-waves, potentially causing irreversible damage to the photosynthetic apparatus. Field surveys have documented global, temperature-dependent patterns in photosynthetic heat tolerance (PHT ); however, it remains unclear if these patterns reflect acclimation in PHT or inherent differences among species adapted to contrasting habitats. To address these unknowns, we quantified seasonal variations in Tcrit (high temperature where minimal chlorophyll-a fluorescence rises rapidly, reflecting disruption to photosystem II) in 62 species native to six sites from five thermally-contrasting biomes across Australia...
January 5, 2018: Plant, Cell & Environment
Maria Cuenca Cambronero, Bettina Zeis, Luisa Orsini
Anthropogenic global warming has become a major geological and environmental force driving drastic changes in natural ecosystems. Due to the high thermal conductivity of water and the effects of temperature on metabolic processes, freshwater ecosystems are among the most impacted by these changes. The ability to tolerate changes in temperature may determine species long-term survival and fitness. Therefore, it is critical to identify coping mechanisms to thermal and hyper-thermal stress in aquatic organisms...
January 2018: Evolutionary Applications
Michael J Buono, Mark Kolding, Eric Leslie, Daniel Moreno, Sarah Norwood, Andrew Ordille, Rebecca Weller
The purpose of this study was to determine the time course for the previously reported reduction in sweat sodium ion concentration during heat acclimation. Four healthy volunteers completed 7 consecutive days of heat acclimation which included 2h of treadmill walking in a 40°C and 40% relative humidity environment. A modified constant hyperthermia protocol was used as workloads were increased each day to maintain a constant core temperature over the 7 days of heat acclimation. Forearm sweat was collected 3 times during each 2h exercise bout on days 1, 3, 5, and 7 of heat acclimation...
January 2018: Journal of Thermal Biology
Meng Li, Xiao-Juan Li, Jian-Hua Lü, Ming-Fei Huo
Lasioderma serricorne (Fabricius) (Coleoptera: Anobiidae) is an important economic insect of various stored products worldwide. With the restricted use of methyl bromide and the increasing negative effects of repeated use of phosphine fumigation, heat treatment becomes the main approach to control stored-product insects. We investigated effect of the acclimation to sublethal high temperature of 36°C and 42°C for different times on heat tolerance of L. serricorne adults, pupae, larvae, and eggs to lethal high temperature of 50°C in laboratory...
January 2018: Journal of Thermal Biology
Md Emon Hossain, Kentaro Matsuzaki, Masanori Katakura, Naotoshi Sugimoto, Abdullah Al Mamun, Rafiad Islam, Michio Hashimoto, Osamu Shido
Heat acclimation in rats is associated with enhanced neurogenesis in thermoregulatory centers of the hypothalamus. To elucidate the mechanisms for heat acclimation, we investigated the effects of direct mild heat exposure on the proliferation and differentiation of neural stem/progenitor cells (NSCs/NPCs). The NSCs/NPCs isolated from forebrain cortices of 14.5-day-old rat fetuses were propagated as neurospheres at either 37.0°C (control) or 38.5°C (mild heat exposure) for four days, and the effects on proliferation were investigated by MTS cell viability assay, measurement of neurosphere diameter, and counting the total number of cells...
2017: PloS One
W C E P Verberk, P Calosi, J I Spicer, S Kehl, D T Bilton
In the face of global warming, both the absolute thermal tolerance of an ectotherms, and its ability to shift its tolerance level via acclimation, are thought to be fundamentally important. Understanding the links between tolerance and its plasticity is therefore critical to accurately predict vulnerability to warming. Previous studies in a number of ectotherm taxa suggest trade-offs in the evolution of thermal tolerance and its plasticity, something which does not, however, apply to Deronectes diving beetles, where these traits are instead positively correlated...
December 23, 2017: Journal of Insect Physiology
Gordon S Waddington
No abstract text is available yet for this article.
February 2018: Journal of Science and Medicine in Sport
Kazuma Katano, Ryo Kataoka, Munetoshi Fujii, Nobuhiro Suzuki
Cyclic nucleotide gated channel 2 (CNGC2) in Arabidopsis has been identified as one of the putative heat sensors which might play a key role in the regulation of heat acclimation. However, it is still not understood how CNGC2 controls heat stress responses during different growth stages. This study aimed to characterize the differences in heat stress responses between seedlings and flowers of Arabidopsis plants deficient in CNGC2. Seedlings of Arabidopsis plants deficient in CNGC2 showed enhanced tolerance to heat stress accompanied by higher accumulation of heat response proteins such as multiprotein bridging factor 1c (MBF1c), ascorbate peroxidases (APXs) and heat shock proteins (HSPs)...
December 13, 2017: Plant Physiology and Biochemistry: PPB
Nicholas I Kelly, Chris C Wilson, Suzanne Currie, Gary Burness
The ability of cold-adapted species to persist in the face of climate change will depend on the capacity of individuals for thermal acclimation, adaptation, and the degree of physiological variation that exists among populations. We tested the acclimation capacity of cardiac HSP70 and HSP90 in four populations of lake trout (Salvelinus namaycush), a cold-adapted salmonid. We acclimated fish to four temperatures (8°C, 11°C, 15°C, and 19°C) and measured cardiac HSP70 and HSP90 levels by western blot prior to and following an acute (1h) heat shock at 23°C...
December 10, 2017: Comparative Biochemistry and Physiology. Part B, Biochemistry & Molecular Biology
Yifan Chen, Tianzheng Yu
AIM: Anti-inflammatory mediators likely play a key role in maintaining thermal homeostasis and providing protection against heat stress. The aim of this study was to investigate the association between activation of the glucocorticoid receptor (GR) and resistance to heat-induced hyperthermia and injury. METHODS: Effects of heat exposure on core body temperature, muscle GR phosphorylation status and subcellular expression were examined in control mice and thermal acclimation (TA)-exposed mice...
December 12, 2017: Acta Physiologica
Ying Ji, Jiangbing Qiu, Tian Xie, Pearse McCarron, Aifeng Li
Azaspiracid (AZA) producing microalgae have been reported internationally and could potentially impact a variety of seafood. Scallops (Chlamys farreri) and mussels (Mytilus galloprovincialis) from China were fed with the AZA2 producer, Azadinium poporum, to study uptake, metabolism and oxidative stress in the shellfish. LC-MS/MS showed significant accumulation and differential metabolism of AZA2 in the scallops and mussels. In mussels AZA2 was metabolized to AZA19, with subsequent decarboxylation to AZA6. In scallops no AZA19 or AZA6 was observed, however, a novel AZA metabolite was formed with that is isobaric with AZA19 ([M+H]+, m/z 886), but elutes at a different retention time...
December 8, 2017: Toxicon: Official Journal of the International Society on Toxinology
Alberto Garre, Juan Pablo Huertas, Gerardo A González-Tejedor, Pablo S Fernández, Jose A Egea, Alfredo Palop, Arturo Esnoz
This contribution presents a mathematical model to describe non-isothermal microbial inactivation processes taking into account the acclimation of the microbial cell to thermal stress. The model extends the log-linear inactivation model including a variable and model parameters quantifying the induced thermal resistance. The model has been tested on cells of Escherichia coli against two families of non-isothermal profiles with different constant heating rates. One of the families was composed of monophasic profiles, consisting of a non-isothermal heating stage from 35 to 70°C; the other family was composed of biphasic profiles, consisting of a non-isothermal heating stage followed by a holding period at constant temperature of 57...
November 27, 2017: International Journal of Food Microbiology
Jie He, Regina M P Lim, Sabrina H J Dass, Tim W Yam
Grammatophyllum speciosum, a native species to Singapore, have become extinct mainly due to habitat loss. Recently, Singapore has reintroduced G. speciosum into the natural environment under the orchid conservation programme. In this study, leaves of G. speciosum grown under low light (LL) under natural conditions had faster expansion rate and higher specific leaf area than leaves grown under intermediate light (IL) and high light (HL). All leaves had more than 95% midday relative water content. Although midday Fv/Fm ratios were lower in HL leaves than in IL and LL leaves, none of them exhibited chronic photoinhibition...
December 5, 2017: Botanical Studies (Taipei, Taiwan)
Xiang Tao, Ming-Xiu Wang, Ya Dai, Yan Wang, Yan-Fen Fan, Ping Mao, Xin-Rong Ma
Plant cytochrome P450s are involved in a wide range of biosynthetic reactions that generate various biomolecules, including a variety of defensive compounds. Perennial ryegrass (Lolium perenne) and tall fescue (Festuca arundinacea) are two major species of turf and forage grasses that usually experience low temperature below -10°C and high temperature over 38°C around the world. In this study, we re-analyzed transcriptome of perennial ryegrass and tall fescue treated with heat and cold stress. Thus, we can evaluate P450 composition in these species and confirm whether P450 genes response to temperature stress...
2017: Frontiers in Plant Science
Reyard Mutamiswa, Frank Chidawanyika, Casper Nyamukondiwa
BACKGROUND: Increasing climatic average temperatures and variability elicit various insect physiological responses that affect fitness and survival and may influence subsequent trophic interactions in agroecosystems. In line with this background, we investigated short and long-term plastic responses to temperature of laboratory-reared stemborer, Chilo partellus and its larval endoparasitoid, Cotesia flavipes. RESULTS: Rapid cold- and -heat hardening effects in C...
November 28, 2017: Pest Management Science
Jeng-Wei Tsai, Hon-Jung Liew, Jyun-Jiang Jhang, Shiou-Han Hung, Pei-Jie Meng, Ming-Yih Leu, Christopher Lim, Cheng-Hao Tang
The mosquitofish (Gambusia affinis) naturally inhabits freshwater (FW; 1-3‰) and seawater (SW; 28-33‰) ponds in constructed wetland. To explore the physiological status and molecular mechanisms for salinity adaptation of the mosquitofish, cytoprotective responses and osmoregulation were examined. In the field study, activation of protein quality control (PQC) mechanism through upregulation of the abundance of heat shock protein (HSP) 90 and 70 and ubiquitin-conjugated proteins was found in the mosquitofish gills from SW pond compared to the individuals of FW pond...
December 1, 2017: Fish Physiology and Biochemistry
Tommaso Manenti, Volker Loeschcke, Jesper Givskov Sørensen
Most research on thermal adaptation of ectotherms is based on experiments performed at constant temperatures. However, for short-lived insects daily fluctuations of temperature could be an important environmental parameter involved in evolutionary adaptation to thermal heterogeneity. In this study we investigated the mechanisms underlying evolutionary adaptation to daily fluctuating temperatures. We studied replicated selection lines of Drosophila simulans evolved in a constant or a daily fluctuating thermal regime...
November 21, 2017: Journal of Insect Physiology
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