Heat acclimation

To optimise the performance and welfare of horses during equestrian competitions in hot climates, it is advised to acclimate them to the heat. The effects of training in a heated indoor arena were studied. Four Olympic horses (13.3 ± 2.2 years; three eventers, one para-dressage horse) were trained for 14 consecutive days in a heated indoor arena (32 ± 1 °C; 50-60% humidity) following their normal training schedule in preparation for the Tokyo Olympic games. Standardised exercise tests (SETs) were performed on Day 1 and Day 14, measuring heart rate (HR; bpm), plasma lactate concentration (LA; mmol/L), deep rectal temperature (Trec ; °C), sweat loss (SL; L), and sweat composition (K+ , Cl- and Na+ concentration)...

Global warming has caused the degradation of coral reefs around the world. While stress-tolerant corals have demonstrated the ability to acclimatize to ocean warming, it remains unclear whether they can sustain their thermal resilience when superimposed with other coastal environmental stressors. We report the combined impacts of a photosystem II (PSII) herbicide, prometryn, and ocean warming on the stress-tolerant coral Galaxea fascicularis through physiological and omics analyses. The results demonstrate that the heat-stress-induced inhibition of photosynthetic efficiency in G...

Ocean warming is a prevailing threat to marine ectotherms. Recently the "plastic floors, concrete ceilings" hypothesis was proposed, which suggests that a warmed fish will acclimate to higher temperatures by reducing standard metabolic rate (SMR) while keeping maximum metabolic rate (MMR) stable, therefore improving aerobic scope (AS). Here we evaluated this hypothesis on red drum (Sciaenops ocellatus) while incorporating measures of hypoxia vulnerability (critical oxygen threshold; Pcrit ) and mitochondrial performance...

The gaseous signaling molecules, ethylene (ET) and hydrogen sulfide (H2 S) are well known for their ability to mitigate abiotic stress, but how they interact with mineral nutrients under heat stress is unclear. We have studied the involvement of ET and H2 S in adaptation of heat stress on the availability of sulfur (S) levels in rice (Oryza sativa L.). Heat stress (40 °C) negatively impacted growth and photosynthetic-sulfur use efficiency (p-SUE), with accumulation of reactive oxygen species (ROS) in six rice cultivars, namely PS 2511, Birupa, Nidhi, PB 1509, PB 1728, and Panvel...

BACKGROUND: The lesser grain borer (Rhyzopertha dominica), a worldwide primary pest of stored grain, causes serious economic losses and threatens stored food safety. R. dominica can respond to changes in temperature, especially the adaptability to heat. In this study, transcriptome analysis of R. dominica exposed to different temperatures was performed to elucidate differences in gene expression and the underling molecular mechanism. RESULTS: Isoform-sequencing generated 17,721,200 raw reads and yielded 20,416 full-length transcripts...

Common bean ( Phaseolus vulgaris ) can efficiently fix atmospheric nitrogen when associated with Rhizobia. However, drought stress impairs plant metabolic processes, especially the biological nitrogen fixation (BNF). Here, we assessed transcriptional responses in nodules of two common bean genotypes to drought stress under BNF reliance. The RNA-Seq analysis yielded a total of 81,489,262 and 72,497,478 high quality reads for Negro Argel and BAT 477 genotypes, respectively. The reads were mapped to the Phaseolus vulgaris reference genome and expression analysis identified 145 and 1451 differentially expressed genes (DEGs) for Negro Argel and BAT 477 genotypes, respectively...

This study investigated the impact of long-term heat acclimation (HA) training on mouse thermoregulation, metabolism, and running performance in temperate (T) and hot (H) environments. Male Swiss mice were divided into 1) Sedentary (SED) mice kept in T (22 °C; SED/T), 2) Endurance Trained mice (ET, 1 h/day, 5 days/week, 8 weeks, 60 % of maximum speed) in T (ET/T), 3) SED kept in H (32 °C; SED/H), and 4) ET in H (ET/H). All groups performed incremental load tests (ILT) in both environments before (pre-ET) and after four and eight weeks of ET...

In nature, plants are exposed to a range of climatic conditions. Those negatively impacting plant growth and survival are called abiotic stresses. Although abiotic stresses have been extensively studied separately, little is known about their interactions. Here, we investigate the impact of long-term mild metal exposure on the cold acclimation of Salix viminalis roots using physiological, transcriptomic, and proteomic approaches. We found that, while metal exposure significantly affected plant morphology and physiology, it did not impede cold acclimation...

Chlorophyll (Chl) fluorescence induction (FI) upon a dark-light transition has been widely analyzed to derive information on initial events of energy conversion and electron transfer in photosystem II (PSII). However, currently, there is no analytical solution to the differential equation of QA reduction kinetics, raising a doubt about the fitting of FI by numerical iteration solution. We derived an analytical solution to fit the OJ phase of FI, thereby yielding estimates of three parameters: the functional absorption cross-section of PSII ( σ PSII ), a probability parameter that describes the connectivity among PSII complexes ( p ), and the rate coefficient for QA - oxidation ( k ox )...

Ongoing climate change is increasing the frequency and intensity of extreme temperature events. Unlike the gradual increase on average environmental temperatures, these short-term and unpredictable temperature extremes impact population dynamics of ectotherms through their effect on individual survival. While previous research has predominantly focused on the survival rate of terrestrial embryos under acute heat stress, less attention has been dedicated to the nonlethal effects of ecologically realistic timing and magnitude of temperature extremes on aquatic embryos...

Changes in ambient temperature profoundly affect plant growth and performance. Therefore, the molecular basis of plant acclimation to temperature fluctuation is of great interest. In this study, we demonstrate that GLYCINE-RICH RNA-BINDING PROTEIN 7 (GRP7) contributes to cold and heat tolerance mechanisms in Arabidopsis (Arabidopsis thaliana). We show that exposure to a warm temperature can rapidly induce GRP7 condensates in planta, which can be reversed by transfer to a lower temperature. GRP7 undergoes liquid-liquid phase separation (LLPS) in vivo and in vitro...

Mounting evidence suggests that ectotherms are already living close to their upper physiological thermal limits. Phenotypic plasticity has been proposed to reduce the impact of climate change in the short-term providing time for adaptation, but the tolerance-plasticity trade-off hypothesis predicts organisms with higher tolerance have lower plasticity. Empirical evidence is mixed, which may be driven by methodological issues such as statistical artefacts, nonlinear reaction norms, threshold shifts or selection...

Global warming is causing quick changes in mean annual temperature and more severe drought periods. These are major contributors of forest dieback, which is becoming more frequent and widespread. In this work we investigated how the transcriptome of Pinus radiata changed during initial heat stress response and acclimation. To this end, we generated a high-density dataset employing Illumina technology. This approach allowed us to reconstruct the needle transcriptome, defining 12164 and 13590 transcripts as down- and upregulated, respectively, during time course stress acclimation experiment...

Plants growing under natural conditions experience high light (HL) intensities that are often accompanied by elevated temperatures. These conditions could affect photosynthesis, reduce yield, and negatively impact agricultural productivity. The combination of different abiotic challenges creates a new type of stress for plants by generating complex environmental conditions that often exceed the impact of their individual parts. Transcription factors (TFs) play a key role in integrating the different molecular signals generated by multiple stress conditions, orchestrating the acclimation response of plants to stress...

Interest in the health consequences of climate change (global warming, heatwaves) has increased in the neurological community. This review addresses the impact of elevated ambient temperatures and heatwaves on patients with neurological and mental health disorders, including multiple sclerosis, synucleinopathies, dementia, epilepsies, mental health, and stroke. Patients with such conditions are highly vulnerable during heatwaves because of functional disorders affecting sleep, thermoregulation, autonomic system reactivity, mood, and cognitive ability...

Extreme temperatures threaten species under climate change and can limit range expansions. Many species cope with changing environments through plastic changes. This study tested phenotypic changes in heat and cold tolerance under hardening and acclimation in the melon thrips, Thrips palmi Karny (Thysanoptera: Thripidae), an agricultural pest of many vegetables. We first measured the critical thermal maximum (CTmax ) of the species by the knockdown time under static temperatures and found support for an injury accumulation model of heat stress...

The world is experiencing increased frequency, duration, and severity of life-threatening heat extremes. Most hospitalizations and excess deaths during extreme heat events are associated with pre-existing diseases in older adults. As climate change persists, the global population ages, and the number of individuals with chronic diseases expands, more people are at risk of adverse health outcomes during extreme heat events. Therefore, proactive preventive measures are urgently needed to mitigate heat-related health risks within these populations...

Embryos of Ilyanassa obsoleta (from Massachusetts and Florida) and Phrontis vibex (from Florida) were exposed to temperatures from 33 to 37°C. In both species, very young embryos are especially sensitive to thermal stress. Brief early heat shock did not disturb spiral cleavage geometry but led to variable, typically severe defects in larval morphogenesis and tissue differentiation. In Ilyanassa but not P. vibex, early heat shock resulted in immediate slowing or arrest of interphase progression during early cleavage...

Objectives were to examine the temporal pattern of intestinal mast cell dynamics and the effects of a mast cell stabilizer [ketotifen (Ket)] during acute heat stress (HS) in growing pigs. Crossbred barrows [n=42; 32.3±1.9 kg body weight (BW)] were randomly assigned to 1 of 7 environmental-therapeutic treatments: 1) thermoneutral (TN) control (TNCon; n=6), 2) 2 h HS control (2 h HSCon; n=6); 3) 2 h HS + Ket (2 h HSKet; n=6); 4) 6 h HS control (6 h HSCon; n=6); 5) 6 h HS + Ket (6 h HSKet; n=6); 6) 12 h HS control (12 h HSCon; n=6), or 7) 12 h HS + Ket (12 h HSKet; n=6)...

Temperature varies on multiple timescales and ectotherms must adjust to these changes to survive. These adjustments may lead to energetic trade-offs between self-maintenance and reproductive investment. However, we know little about how diurnal and seasonal temperature changes impact energy allocation. Here we used a combination of empirical data and modeling of both thermoregulatory behaviors and body temperature to examine potential energetic trade-offs in the dung beetle Onthophagus taurus. Beginning in March 2020, universities and laboratories were officially closed due to the COVID-19 pandemic...