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Heat acclimation

Pavel Pospíšil, Yasusi Yamamoto
BACKGROUND: Photosystem II proteins of higher plant chloroplasts are prone to oxidative stress, and most prominently the reaction center-binding D1 protein is damaged under light stress and heat stress. The reactive oxygen species produced under these stress conditions have been suggested to be responsible for the protein injury. SCOPE OF REVIEW: Recently, it has been shown that the primary and secondary products of non-enzymatic and enzymatic lipid peroxidation have a capability to modify photosystem II proteins...
October 11, 2016: Biochimica et Biophysica Acta
Tianzheng Yu, Patricia Deuster, Yifan Chen
The regulation of mitochondrial morphology is closely coupled to cell survival during stress. We examined changes in the mitochondrial morphology of mouse C2C12 skeletal muscle cells in response to heat acclimation and heat shock exposure. Acclimated cells showed a greater survival rate during heat shock exposure than non-acclimated cells, and were characterized by long interconnected mitochondria and reduced expression of dynamin-related protein 1 (Drp1) for their mitochondrial fractions. Exposure of C2C12 muscle cells to heat shock led to apoptotic death featuring activation of caspase 3/7, release of cytochrome c and loss of cell membrane integrity...
October 12, 2016: Journal of Physiology
L W Hall, F R Dunshea, J D Allen, S Rungruang, J L Collier, N M Long, R J Collier
Betaine (BET), a natural, organic osmolyte, improves cellular efficiency by acting as a chaperone, refolding denatured proteins. To test if dietary BET reduced the effect of heat stress (HS) in lactating dairy cows, multiparous, lactating Holstein cows (n = 24) were blocked by days in milk (101.4 ± 8.6 d) and randomly assigned to 1 of 3 daily intakes of dietary BET: the control (CON) group received no BET, mid intake (MID) received 57 mg of BET/kg of body weight, and high dose (HI) received 114 mg of BET/kg of body weight...
October 5, 2016: Journal of Dairy Science
Paul Trayhurn
Brown adipose tissue (BAT) was identified as a thermogenic organ in 1961, and in 1978 shown to be the major site of thermoregulatory non-shivering thermogenesis in rats acclimated to the cold. Investigations in the mid-late 1970s established the uncoupling of oxidative phosphorylation through a proton conductance pathway across the mitochondrial inner membrane as the mechanism for heat production in BAT, this being regulated by UCP1 which was first discovered as a 32,000 Mr cold-inducible protein. These developments came when those concerned with nutritional energetics were proposing that thermogenesis is a significant factor in energy balance and the aetiology of obesity...
September 10, 2016: Biochimie
Jeong-Beom Lee, Jeong-Ho Kim, Hiroyuki Murota
The sudomotor mechanism, wich contributes to tolerating thermal environments, is affected by not only the body temperature, but also sex, ethnicity, exercise training, region, season, and heat adaptation. Aging attenuates the sudomotor function by the decreased peripheral sensitivity to acetylcholine and demyelination of innervating nerves. Women show less sudomotor activity than men. Heat adaptation with sudomotor modification is induced by repetitive physical and/or thermal training. Short-term heat acclimation increases sweat gland activity...
2016: Current Problems in Dermatology
Saul A Cuttell, Victor Kiri, Christopher Tyler
CONTEXT: Cooling the torso and neck can improve exercise performance and capacity in a hot environment; however, the proposed mechanisms for the improvements often differ. OBJECTIVE: To directly compare the effects of cooling the neck and torso region using commercially available devices on exercise capacity in a hot environment (temperature = 35°C ± 0.1°C, relative humidity = 50.1% ± 0.7%). DESIGN: Crossover study. SETTING: Laboratory...
July 2016: Journal of Athletic Training
Odhran S O'sullivan, Mary A Heskel, Peter B Reich, Mark G Tjoelker, Lasantha K Weerasinghe, Aurore Penillard, Lingling Zhu, John J G Egerton, Keith J Bloomfield, Danielle Creek, Nur H A Bahar, Kevin L Griffin, Vaughan Hurry, Patrick Meir, Matthew H Turnbull, Owen K Atkin
High-temperature tolerance in plants is important in a warming world, with extreme heat waves predicted to increase in frequency and duration, potentially leading to lethal heating of leaves. Global patterns of high-temperature tolerance are documented in animals, but generally not in plants, limiting our ability to assess risks associated with climate warming. To assess whether there are global patterns in high-temperature tolerance of leaf metabolism, we quantified Tcrit (high temperature where minimal chlorophyll a fluorescence rises rapidly and thus photosystem II is disrupted) and Tmax (temperature where leaf respiration in darkness is maximal, beyond which respiratory function rapidly declines) in upper canopy leaves of 218 plant species spanning seven biomes...
August 26, 2016: Global Change Biology
Lucie Maršálová, Pavel Vítámvás, Radovan Hynek, Ilja T Prášil, Klára Kosová
Response to a high salinity treatment of 300 mM NaCl was studied in a cultivated barley Hordeum vulgare Syrian cultivar Tadmor and in a halophytic wild barley H. marinum. Differential salinity tolerance of H. marinum and H. vulgare is underlied by qualitative and quantitative differences in proteins involved in a variety of biological processes. The major aim was to identify proteins underlying differential salinity tolerance between the two barley species. Analyses of plant water content, osmotic potential and accumulation of proline and dehydrin proteins under high salinity revealed a relatively higher water saturation deficit in H...
2016: Frontiers in Plant Science
Joshua H Guy, David B Pyne, Glen B Deakin, Catherine M Miller, Andrew M Edwards
PURPOSE: While the intention of endurance athletes undertaking short term heat training protocols is to rapidly gain meaningful physical adaption prior to competition in the heat, it is currently unclear whether or not this process also presents an overt, acute challenge to the immune system. The aim of this study was therefore to examine the effects of heat training on both endurance performance and biomarkers associated with inflammatory and immune system responses. METHODS: Moderately-actively males (n = 24) were allocated randomly to either HOT (n = 8, 35°C, and 70% RH; NEUTRAL (n = 8, 20°C, and 45% RH); or a non-exercising control group, (CON, n = 8)...
2016: Frontiers in Physiology
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...
August 13, 2016: Fish Physiology and Biochemistry
Oliver R Gibson, James A Tuttle, Peter W Watt, Neil S Maxwell, Lee Taylor
Increased intracellular heat shock protein-72 (Hsp72) and heat shock protein-90α (Hsp90α) have been implicated as important components of acquired thermotolerance, providing cytoprotection during stress. This experiment determined the physiological responses characterising increases in Hsp72 and Hsp90α mRNA on the first and tenth day of 90-min heat acclimation (in 40.2 °C, 41.0 % relative humidity (RH)) or equivalent normothermic training (in 20 °C, 29 % RH). Pearson's product-moment correlation and stepwise multiple regression were performed to determine relationships between physiological [e...
August 11, 2016: Cell Stress & Chaperones
Leandro Zuccherato Camerro, Alex Sandro Campos Maia, Marcos Chiquitelli Neto, Cintia Carol de Melo Costa, Patric André Castro
The literature is very sparse regarding research on the thermal equilibrium in Guzerat cattle (Bos indicus) under field conditions. Some factors can modify the physiological response of Guzerat cattle, such as the reactivity of these animals to handling. Thus, the development of a methodology to condition and select Guzerat cattle to acclimate them to the routine collection of data without altering their physiological response was the objective of the preliminary experiment. Furthermore, the animals selected were used in the main experiment to determine their thermal equilibrium according to the thermal environment...
August 2016: Journal of Thermal Biology
Wei Feng, Heike Lindner, Neil E Robbins, José R Dinneny
Water is the most limiting resource on land for plant growth, and its uptake by plants is affected by many abiotic stresses, such as salinity, cold, heat, and drought. While much research has focused on exploring the molecular mechanisms underlying the cellular signaling events governing water-stress responses, it is also important to consider the role organismal structure plays as a context for such responses. The regulation of growth in plants occurs at two spatial scales: the cell and the organ. In this review, we focus on how the regulation of growth at these different spatial scales enables plants to acclimate to water-deficit stress...
August 2016: Plant Cell
Sara I Zandalinas, Damián Balfagón, Vicent Arbona, Aurelio Gómez-Cadenas, Madhuri A Inupakutika, Ron Mittler
Abscisic acid (ABA) plays a key role in plant acclimation to abiotic stress. Although recent studies suggested that ABA could also be important for plant acclimation to a combination of abiotic stresses, its role in this response is currently unknown. Here we studied the response of mutants impaired in ABA signalling (abi1-1) and biosynthesis (aba1-1) to a combination of water deficit and heat stress. Both mutants displayed reduced growth, biomass, and survival when subjected to stress combination. Focusing on abi1-1, we found that although its stomata had an impaired response to water deficit, remaining significantly more open than wild type, its stomatal aperture was surprisingly reduced when subjected to the stress combination...
October 2016: Journal of Experimental Botany
Jesper Givskov Sørensen, Mads Fristrup Schou, Torsten Nygaard Kristensen, Volker Loeschcke
Terrestrial ectotherms are challenged by variation in both mean and variance of temperature. Phenotypic plasticity (thermal acclimation) might mitigate adverse effects, however, we lack a fundamental understanding of the molecular mechanisms of thermal acclimation and how they are affected by fluctuating temperature. Here we investigated the effect of thermal acclimation in Drosophila melanogaster on critical thermal maxima (CTmax) and associated global gene expression profiles as induced by two constant and two ecologically relevant (non-stressful) diurnally fluctuating temperature regimes...
2016: Scientific Reports
B Kurowicka, M Chrusciel, A Zmijewska, G Kotwica
This study aimed to evaluate the effect of heat acclimation of neonatal and adult rats on their testes response to in vitro treatment with triiodothyronine (T3). Four groups of rats were housed from birth as: 1) control (CR) at 20°C for 90 days, 2) neonatal heat-acclimated (NHA) at 34°C for 90 days, 3) adult heat-acclimated (AHA) at 20°C for 45 days followed by 45 days at 34°C and 4) de-acclimated (DA) at 34°C for 45 days followed by 45 days at 20°C. Blood plasma and both testes were harvested from 90-day old rats...
2016: Polish Journal of Veterinary Sciences
Alliea Nankishore, Aidan D Farrell
Efforts to maximize yields of food crops can be undermined by abiotic stress factors, particularly those related to climate change. Here, we use a range of physiological methods to detect the individual and combined effects of heat and drought stress on three contrasting varieties of tomato: Hybrid 61, Moskvich, and Nagcarlang. Seedlings were acclimated under the following treatment regimes: CONTROL (25-36°C; well-watered), DRY (25-36°C; 20% field capacity), HOT (25-42°C; well-watered) and HOT+DRY (25-42°C; 20% field capacity)...
September 1, 2016: Journal of Plant Physiology
Martin P Poirier, Daniel Gagnon, Glen P Kenny
The purpose of this study was to examine if local changes in sweat rate following 14 days of heat acclimation reflect those that occur at the whole-body level. Both prior to and following a 14-day traditional heat acclimation protocol, 10 males exercised in the heat (35 °C, ∼20% relative humidity) at increasing rates of heat production equal to 300 (Ex1), 350 (Ex2), and 400 (Ex3) W·m(-2). A 10-min recovery period followed Ex1, while a 20-min recovery period separated Ex2 and Ex3. The exercise protocol was performed in a direct calorimeter to measure whole-body sweat rate and, on a separate day, in a thermal chamber to measure local sweat rate (LSR), sweat gland activation (SGA), and sweat gland output (SGO) on the upper back, chest, and mid-anterior forearm...
August 2016: Applied Physiology, Nutrition, and Metabolism, Physiologie Appliquée, Nutrition et Métabolisme
Jianhua Lü, Huina Zhang
Heat treatment is a popular alternative to synthetic pesticides in disinfesting food-processing facilities and empty grain storages. Sitophilus zeamais Mostchulsky is one of the most cosmopolitan and destructive insects found in empty grain storage facilities and processing facilities. The effect of acclimation in S. zeamais adults to sublethal high temperature on their subsequent susceptibility to high temperatures was investigated. S. zeamais adults were acclimated to 36°C for 0 (as a control), 1, 3, and 5 h, and then were exposed at 43, 47, 51, and 55°C for different time intervals respectively...
2016: PloS One
Hagit Kvitt, Hanna Rosenfeld, Dan Tchernov
Recent studies suggest that controlled apoptotic response provides an essential mechanism, enabling corals to respond to global warming and ocean acidification. However, the molecules involved and their functions are still unclear. To better characterize the apoptotic response in basal metazoans, we studied the expression profiles of selected genes that encode for putative pro- and anti-apoptotic mediators in the coral Stylophora pistillata under thermal stress and bleaching conditions. Upon thermal stress, as attested by the elevation of the heat-shock protein gene HSP70's mRNA levels, the expression of all studied genes, including caspase, Bcl-2, Bax, APAF-1 and BI-1, peaked at 6-24 h of thermal stress (hts) and declined at 72 hts...
2016: Scientific Reports
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