The effects of short-term heat stress on normal-diet rats are well-known, but the impact of long-term heat and humidity on rats fed a carbohydrate-rich diet remains unexplored. The study examined the alterations caused by chronic heat and humidity stress in liver enzymes, blood biochemistry, and histology in rats fed a carbohydrate-rich diet. One hundred and eighty adult rats were divided into routine diet (RD) and carbohydrate-rich diet (CRD) groups, further divided into no stress, heat, and humidity stress conditions. Heat and humidity stress were applied daily for 4h over 30 days. Blood and liver samples were collected at three decapitation intervals for enzyme (ALT, AST, ALP, GGT) and protein (TP, ALB, TB) analysis, and histological examination. CRD-fed rats exhibited higher ALT, AST, and GGT levels than RD-fed rats, with males showing greater increases, especially under heat stress. ALP levels rose in CRD-fed groups, particularly in females at the 3rd decapitation. TP and ALB levels varied by gender and diet but were not significantly different under stress, while TB showed non-significant results across interactions. Histological analysis indicated normal hepatic structures in controls, whereas CRD-fed rats under heat stress displayed cellular disorganization, inflammatory infiltration, and hepatocyte degeneration. Based on biochemical and histological changes, prolonged heat and humidity stress in CRD-fed rats exacerbates liver damage. The findings emphasize the need for dietary and environmental management strategies to support liver health in stressful conditions.

High summer temperatures increasingly constrain sweet cherry production, yet field-validated assessments of rootstock resilience remain scarce. To fill this gap, this study presents a pioneering multidimensional evaluation of five widely used sweet cherry rootstocks (Gisela 6, Gisela 12, Krymsk 5, Colt, and Lanting) under prolonged natural heat stress. Morphological traits, leaf anatomical characteristics, antioxidant enzyme activities (SOD, CAT, POD), lipid peroxidation (MDA), phytohormones (ABA and JA), and osmotic regulators were assessed. Traits with high coefficients of variation, including POD activity, ABA, JA, and soluble protein content, were identified as sensitive indicators of heat stress. Lanting exhibited the strongest heat tolerance, characterized by thicker leaves, fewer heat-induced lesions, and enhanced antioxidant capacity, whereas Gisela 6 showed severe leaf abscission, elevated MDA and ABA accumulation, and the weakest defense capacity. Correlation analysis indicated that root sucker number was positively associated with SOD activity and soluble sugar content, suggesting a potential role of whole-plant carbon allocation in mitigating oxidative stress. Using the Entropy Weight–TOPSIS model, we provided a robust ranking that identifies Lanting and Colt as superior heat-resilient genotypes. The results provide a field-validated framework that bridges the gap between controlled-environment theory and practical orchard management, offering critical guidance for expanding sweet cherry cultivation into high-temperature regions.

Global warming has made heat stress a major constraint on grapevine growth and grape production. This study aimed to evaluate the heat tolerance of three prevalent trellis systems-V-shaped (VT), upward-trained pendulous (U-PT), and H-shaped (HT)-for Vitis labruscana × V. vinifera 'Shine Muscat'. We specifically tested the hypothesis that U-PT enhances heat tolerance by optimizing canopy structure to mitigate high-temperature stress, thereby alleviating its negative impacts on stomatal function, chloroplast integrity, and photosynthetic performance. Under summer rain-shelter cultivation, the three trellis systems werecompared using five-year-old 'Shine Muscat' grapevines based on canopy temperature, relative humidity, leaf sunburn, chlorophyll content, stomatal morphology, chloroplast ultrastructure, leaf gas exchange, and chlorophyll fluorescence. Under prolonged heat stress, stomatal aperture dimensions and aperture ratio decreased (p < 0.05) without significant changes in stomatal density (p > 0.05). Chloroplasts displayed volumetric expansion and substantial lipid droplet accumulation, with particularly pronounced chloroplast envelope disintegration in HT. From Day 3 to Day 15 of prolonged high-temperature stress, net photosynthetic rate (P n), stomatal conductance (g s), transpiration rate (T r), intercellular CO₂ concentration (C i), chlorophyll content, and photochemical quenching coefficient (qP) initially increased, peaking on Day 3 or Day 6, then progressively declined. Maximum energy conversion efficiency (F v/F m), actual photochemical efficiency (Φ PSII) and non-photochemical quenching coefficient (NPQ) remained stable on Day 3. Subsequently, F v/F m and Φ PSII gradually decreased, while NPQ gradually increased. Comparative analysis revealed U-PT maintained the lowest intensity and shortest duration of high canopy temperatures along with higher canopy relative humidity, exhibited the minimal leaf sunburn damage index, and sustained the highest stomatal aperture, P n, F v/F m, Φ PSII, qP, and chlorophyll content, and most stable chloroplast structure, whereas HT performed poorest. The principal component analysis (PCA) confirmed U-PT as the most heat-tolerant trellis system. These findings could provide insights into the responses and adaptions of grapevines to heat stress and aid in the optimization of heat-tolerant trellis systems under everchanging climatic conditions.

Changes in leukocyte indices of Holstein cows under prolonged heat stress conditions.

Crosstalk between physiological and genetic mechanisms during maintenance of acquired thermotolerance in tomato.

An unprecedented number of studies have explored hormone levels in plants; however, only a small fraction includes comprehensive metabolite analyses spanning multiple hormone classes. Here, we aim to establish a unique and detailed resource integrating the absolute concentrations of diverse hormone classes and their metabolites in tomato floral organs and early fruit tissues across developmental stages. We quantified 58 hormone metabolites from six chemical classes in whole flower buds, individual floral organs at five developmental stages, mature pollen, and early fruit tissues up to 15 days after anthesis. Hormone profiling was complemented by matched transcriptomic and shotgun proteomic analyses. This integrated dataset revealed distinct spatial and temporal hormone signatures, including a gradual decline in active auxin levels-especially in stamens-contrasting with the accumulation of oxidized and conjugated auxin forms toward anthesis. Multi-omics analyses identified three GRETCHEN HAGEN 3(GH3) genes (GH3-2, GH3-7, and GH3-15) likely involved in auxin inactivation within reproductive organs. In vitro enzyme assays and transient overexpression in Nicotiana benthamiana confirmed their capacity to conjugate indole-3-acetic acid (IAA) to various amino acids. CRISPR/Cas9-generated single, double, and triple gh3 mutants showed increased levels of free IAA in mature stamens. Proteomic profiling of gh3-2 stamens revealed upregulation of stress-related proteins under normal conditions, whereas under heat stress, gh3-2 stamens exhibited fewer proteomic changes than the wild type. Moreover, pollen from gh3-2 and gh3-7 mutants maintained higher viability after prolonged heat stress. This study offers the most comprehensive hormone-focused multi-omics resource for tomato reproductive development to date. It provides a detailed map of hormone distribution across floral and early fruit tissues, and demonstrates its utility by uncovering a stamen-specific auxin conjugation mechanism that contributes to pollen thermotolerance.

In South Korea, cherry tomato (Solanum lycioersucum) is a major greenhouse vegetable crop. However, climate change has steadily raised Earth’s average temperature, posing a serious challenge for greenhouse agriculture. Elevated temperatures can trigger heat stress in greenhouse crops, leading to considerable yield losses. This study developed a greenhouse tomato growth model for two cherry tomato accessions, HR17 and HR24, cultivated under heat stress conditions during growing periods. Climate projections based on polynomial regression were incorporated into the plant growth model to assess climate change impacts on tomato yields. The two tomato accessions demonstrate distinct growth characteristics: HR24 allocates more biomass relative to fruit yield (Harvest index:0.48), whereas HR17 shows greater fruit production than biomass accumulation (Harvest index:0.65). Their yield responses also vary under future climate scenarios highlighted by temperature increases of 1-8°C and extended hot seasons compared to historical records. HR24 appears more resilient to heat stress than HR17. Under Climate Change scenarios (SSP245 and SSP585 pathways), HR17 will decrease its fruit yield by around 1.2 Dry Ma/ha, while HR24 yields will be increased by round 1.3 Dry Mg/ha. This increased tolerance in HR24 may be attributable to its ability to sustain photosynthetic activity through higher production of biomass organs such as leaves and stems. These findings form a foundation for developing greenhouse crop models in future research and supporting farmers by providing more reliable yield forecasts.

Climate change causes frequent periods of heat stress that threaten global wheat production and food security. High temperatures, particularly during grain-filling stage, shorten filling duration and reduce grain yield. Therefore, this study aimed to evaluate the performance, heat stress tolerance, and yield stability of 35 bread wheat genotypes under normal and heat stress conditions during two consecutive growing seasons. Field experiments were conducted under six environments created by varying heat stress duration using plastic tunnel covers (two and four weeks) compared to control plots. Yield components, including number of grains per spike, 1000-grain weight, grain weight per spike, and grain yield, were measured. Heat stress significantly reduced all yield traits, with the greatest relative losses occurring for grain yield and grain weight per spike. Substantial genotypic variability was observed, and genotype-by-environment interaction effects were highly significant. Advanced statistical models, including AMMI1, AMMI2, GGE dendrogram, and hierarchical clustering, were employed to dissect genotype performance and stability across heat treatments and seasons, revealing significant variations in tolerance and adaptation. Dendrogram, heatmaps, and stability analyses identified genotypes with broad adaptability and yield stability under thermal stress. The advanced lines G11, G13, G15, G16, G29, and G25, and G32 exhibited superior heat tolerance and stable high yields. Significant positive correlations among grain yield traits were observed under normal and short-term heat stress. However, prolonged heat stress disrupted these relationships, weakening the association among yield components, which indicates detrimental impact of extended thermal stress on wheat yield formation. The results of this study provide valuable insights into wheat genotypic responses to heat stress and identify promising genotypes for breeding, aiming to improve wheat productivity and sustainability under increasing temperature pressures in arid agroecological zones.

In mammals, prolonged heat stress induces an endoplasmic reticulum (ER) stress response that can damage internal organs. In Drosophila, larvae grow and develop into adults faster at warmer temperatures (e.g., 30°C) than at lower temperatures, but with reduced body size and fertility. In this study, we show that the neuropeptide gene neuropeptide-like precursor 1 (Nplp1) alleviates temperature-induced ER stress in imaginal discs. Warm temperatures increase production of a specific Nplp1 splice variant that inhibits PKR-like endoplasmic reticulum kinase (PERK) activation and cell death. Nplp1 inhibits Dilp8 expression through the PERK/ATF4/Yki pathway, thereby enabling imaginal disc growth and ecdysone homeostasis under warm temperature conditions. These findings provide valuable insights into how animals cope with elevated temperatures.

Transcriptional Insights into Soybean Genotypes Under Prolonged Heat Stress: Identification of Key Genes and Soil Influences for Enhanced Tolerance

Chicken ovaries possess the machinery of VLDL production in response to heat stress (HS). The study sought to define the role of VLDL secretion by hierarchical follicles along their development under HS. HS (42°C) for 8 hr (HS8H) or HS3H and following recovery at 37°C to 16 hr (3H13R) upregulated PCNA and/or IL-1β expressions in granulosa (GC) and theca (TH) cells and augmented progesterone (P4) and estradiol (E2) production, respectively. Inhibition of VLDL production by Lomitapide and Mipomersen suppressed P4 secretion at 3H13R and HS8H, but differentially affected E2 production, leading to altered secretion fashions under thermoneutral conditions (37°C, NC) and during post-HS recovery, suggesting interfered steroidogenic competence toward maturation. HS regardless of duration and recovery or interference with VLDL secretion under NC provoked ROS and MDA accumulation in both cell types. GCs transiently increased VLDL secretion at HS3H and showed overt cell death at 3H13R, while TH cells sustained VLDL production and retained viability. Prolonged HS over 8 hr impaired viability of both cell types with disparate responses in lipid dynamics; constantly depressed neutral lipids and cholesterol in GCs, while TH cells showed increased neutral lipids before HS8H but rapid dissipation to HS16H and suppressed cholesterol at HS8H. Surprisingly, Lomitapide and Mipomersen rescued TH cell viability at HS8H and 8H8R in association with alleviated lipid, MDA, and ROS accumulations, whereas GCs exhibited improved viability at HS8H, but not at 8H8R and 3H13R in couple with worse depletion of neutral lipids and cholesterol, suggesting that HS operates at VLDL production to alter cellular lipid dynamics to potentiate cell death, while TH cells are more thermoresistant due to a proficient adaption in lipid disposal. In conclusion, HS enhances VLDL production in hierarchical follicles to augment its impacts on follicular cell fate, but routine secretion of VLDL is obligatory to sustain follicle maturation under normal conditions, in which TH cells are highly agile in lipid remodeling and redox regulation in adaption to heat insults.

Prolonged heat stress (HS) in poultry has both immediate and transgenerational effects. Carotenoids, with their antioxidant properties, may enhance stress tolerance by reducing oxidative damage. This study assessed the effects of parental HS on offspring (F1) and whether feeding high-carotenoid orange corn (OC) to breeders mitigates these effects. Breeder Pekin ducks were fed either OC or yellow corn (YC) for 3 weeks before and during a 3-week HS exposure. A control breeder group (CON) was kept under thermoneutral conditions with a YC diet. Eggs collected in the final 3 days of HS. CON eggs were collected during the same days and incubated in the same incubator as OC and YC groups. Resulting offspring was allocated to treatment based on parental treatment (n = 56/group: OCF1, YCF1, CONF1) and reared to 5 weeks of age. Weekly body weight (n = 20/group), body condition scores (n = 20 ducks/treatment), and novel object test were measured. At week 3, ducks (n = 8/injection type/group) received Adrenocorticotropic hormone (ACTH; 0.0625 mg/kg) or saline, and blood was collected at 0, 1, 2, 3, and 4 h post-injection for glucocorticoid and heterophil-to-lymphocyte ratio (HLR) analysis. Corticosterone increased at 1 h in all ACTH-injected groups (p < 0.001) and remained elevated in YCF1 at 2 h compared to the CONF1 and OCF1 treatments. Baseline cortisol was higher in F1 from HS parents than CONF1 (p < 0.01) and remained elevated at 1 and 4 h post-ACTH (p < 0.05). HLR at 3 h was higher in YCF1-ACTH compared to CONF1-ACTH (p < 0.05). Body weight was higher in CONF1 compared to OCF1 and YCF1 at weeks 2 - 5 (p < 0.05). Fearful behavior was higher in YCF1 at weeks 1 (p < 0.01), 2 (p < 0.01), and 4 (p = 0.09) compared to CONF1. In conclusion, while parental HS reduced growth in F1 ducks, OC-fed breeders produced offspring without the exaggerated physiological responses to stress. These observations suggest a transgenerational effect of parental OC diet on stress-related physiological responses in the offspring.

As global temperatures continue to rise, heat stress presents significant risks to animal health, particularly affecting kidney function that is of vital importance due to its essential role in detoxification and fluid balance. This study investigates the effects of a carbohydrate rich diet (CRD) on renal health in albino rats subjected to prolonged heat and humidity stress. A total of 180 rats (90 males, 90 females) were assigned to Routine Diet (RD) and CRD groups, each further divided into no-stress, heat stress, and humidity stress subgroups. Stress exposure lasted 4h daily for 30 days, with sample collection at 10, 20, and 30 days. The results demonstrated that heat and humidity stress significantly impacted renal biomarkers (urea, creatinine, uric acid, and BUN) in both male and female albino rats. Males generally exhibited higher serum levels of these markers compared to females, indicating greater susceptibility to stress-induced renal strain. Under no-stress conditions, CRD-fed males and females showed elevated renal markers compared to RD-fed counterparts, with females exhibiting relatively lower values. Humidity stress caused the most pronounced increase in renal markers, with RD-fed males and females reaching peak urea and BUN levels. The CRD diet partially mitigated these elevations in both sexes, although values remained significantly higher than in the no-stress group. Moreover, decapitation interval analysis revealed a consistent increase in urea, creatinine, and uric acid levels over time in both sexes, suggesting cumulative physiological stress. These findings highlight the complex interplay between diet, environmental stress, and gender in renal health, underscoring the potential of dietary strategies to mitigate stress-induced kidney damage. Further research is needed to elucidate the mechanisms underlying these gender-specific and dietary effects.

High-temperature events are projected to increase in frequency under future climate scenarios, threatening rice yields globally. This study investigated the physiological and molecular responses of two Brazilian flooded rice varieties, IRGA 428 and BR-IRGA 409, during the anthesis stage under high-temperature stress, aiming to uncover mechanisms of heat tolerance. Plants were exposed to a daytime temperature of 38°C for 7 h across 3, 5, or 7 days. Prolonged heat stress led to a significant reduction in filled grain in both cultivars, although BR-IRGA 409 demonstrated greater heat tolerance, particularly under 3 days of stress, as it maintained higher spikelet fertility compared to IRGA 428. Comparative transcriptome analysis revealed that BR-IRGA 409 had more differentially expressed genes in response to heat stress, including a significant upregulation of canonical heat-responsive genes such as heat shock factors, heat shock proteins, and peptidyl-prolyl isomerase FK506-binding proteins (FKBPs). Furthermore, BR-IRGA 409 displayed enhanced modulation of the mitochondrial electron transport pathway, which is crucial for adenosine triphosphate (ATP) synthesis and cellular energy production. Interestingly, while photosynthetic performance varied between cultivars, only a few genes associated with photosynthesis were significantly altered in response to heat stress. Instead, BR-IRGA 409 displayed a higher basal expression of photosynthesis-related genes, suggesting that this pre-adaptation might mitigate heat stress impacts on photosynthesis. The ability to preserve functional photosynthetic activity is critical for sustaining the energy-intensive process required to cope with heat stress. This study highlights the difference between the varieties in their response to heat stress and identifies candidate molecular and physiological mechanisms that contribute to maintaining cellular energy homeostasis and heat tolerance in Brazilian rice, providing valuable insights for crop improvement strategies.

Abstract Understanding the response of various seagrass species to prolonged elevated water temperatures is crucial for effective management and seagrass species restoration amid increasing climate change‐induced ocean warming and marine heat waves. This is especially important in intertidal seagrass meadows, where heat can penetrate substrate depths of up to 50 cm. We assessed and contrasted the responses of five intertidal species— Zostera muelleri Irmisch ex Asch, Halophila ovalis (R.Br.) Hook f., Halodule uninervis (Forssk.) Asch, Halophila decipiens Ostenf., and Halophila spinulosa (R.Br.) Asch—over a month of elevated temperatures by examining rhizome growth, number of living shoots, root development, and sprig survival. While all the species appeared to negatively respond to elevated water temperatures, our results indicate notable interspecific variations in their reactions to prolonged warming stress. Two Halophila species, including H. ovalis and H. spinulosa , are sensitive to prolonged heat stress exceeding 10°C above ambient. Halodule uninervis is the most tolerant of elevated water temperature, followed by Zostera muelleri, although the latter is still negatively affected. Intertidal H. decipiens appears to be highly vulnerable to disturbance and performs poorly in mesocosm settings. This study offers an initial understanding of how climate change might impact these seagrass species, whose ecological functions are not easily replaceable once lost.

ABSTRACTBackground and Aim:Tropical climates expose livestock to prolonged heat stress, leading to compromised health, growth, and productivity. Nutritional interventions using omega-3 fatty acids and antioxidants may improve resilience in such environments. This study evaluated the effects of lemuru fish oil (LO), vitamin E, and selenium – individually and in combination – on hematological, physiological, antioxidant, and growth parameters of Garut lambs exposed to tropical heat stress.Materials and Methods:Forty male Garut lambs (23.52 ± 2.51 kg; 9–10 months old) were randomly assigned to five dietary groups: Control (CNT), LO (6%, LO), LO + 500 IU Vitamin E, LO + 0.5 ppm selenium, and LO + both Vitamin E and selenium (LOES). The 60-day trial took place during the dry season under severe to extreme heat stress conditions (temperature-humidity index: 25.13–40.07). Parameters assessed included nutrient intake, physiological responses, blood hematology, antioxidant status, and growth performance.Results:Supplementation with LO and antioxidants significantly improved hematological indicators (e.g., hemoglobin), enhanced antioxidant defenses (e.g., increased superoxide dismutase [SOD] and glutathione, reduced malondialdehyde [MDA], and cortisol levels), and stabilized physiological responses (e.g., lower rectal temperature and heart rate). The LOES group showed the most pronounced improvements: SOD increased by 107%, MDA decreased by 62%, and cortisol levels were reduced by 28% compared to the CNTs. However, no significant differences were observed in average daily gain or feed efficiency.Conclusion:The combination of LO with Vitamin E and selenium effectively mitigated heat-induced oxidative and physiological stress in Garut lambs. Although growth parameters remained unchanged, the improved physiological and antioxidant status suggests that these supplements may be valuable functional feed additives for enhancing animal welfare and resilience under heat stress. Further research is warranted to investigate the long-term effects on productivity and reproduction.

Heat stress-induced dysregulation of bovine reproduction: A focus on corpus luteum and progesterone perspectives.

Abstract. Anthropogenic climate change, combined with specific modifications of the urban climate, is expected to lead to an increase in the intensity, duration, and frequency of heat waves in urban areas. Prolonged heat stress - as expected due to these changes - has serious health consequences for vulnerable urban population groups. This study examines the effects of heat stress on the accessibility of essential services in Heidelberg, Germany. The concept of isochrones was extended to include heat stress factors and applied to the study area, the city of Heidelberg in Germany. The analysis was based on a heat-sensitive routing approach that uses OpenStreetMap data together with a digital surface model that was used to model solar exposure. Results showed that under moderate heat stress conditions, accessibility to essential services (transportation, healthcare, retail and social services) was largely maintained, while under high heat stress conditions, a significant portion of the population was excluded from these services. Differences in the affected population can be identified according to both administrative territorial units and building structures. The results provide relevant information for urban planning as they indicate where city inhabitants will face problems to access essential services under heat spells.

Prolonged exposure to extreme humid heat can induce systemic inflammation, organ stress, and hormonal imbalance. While fluid replacement is commonly recommended, its mechanistic efficacy under humid heat stress remains unclear. This study investigated the impact of fluid intake on thermoregulation, inflammation, organ function, and stress signaling during 8 h of humid heat exposure (ambient temperature: 40 °C, relative humidity: 55%) in 32 healthy young adults (20 males and 12 females). Participants completed two randomized trials: limited fluid intake (LFI, 125 mL/h) and full fluid intake (FFI, 375 mL/h). Core temperature (Tcore), inflammatory cytokines (IL-6, IL-1β, IFN-γ, TNF-α), organ stress markers (ALT, BUN), oxidative stress indices (MDA, SOD), and cortisol were assessed pre- and post-exposure. FFI significantly reduced post-exposure Tcore (37.8 ± 0.3 °C vs. 38.1 ± 0.3 °C, p = 0.046), mitigated cytokine elevations, and decreased BUN (blood urea nitrogen), ALT (alanine aminotransferase), and cortisol levels. Western blot analysis of PBMCs revealed that LFI activated NF-κB p65, JNK2, p38, and STAT3α phosphorylation, whereas FFI suppressed these responses. These findings demonstrate that adequate hydration attenuates heat-induced systemic and molecular stress responses. Our results highlight hydration as a key modulator of inflammatory signaling pathways during prolonged heat stress, offering insights into preventive strategies for populations vulnerable to climate-induced extreme heat events.

Improving the accuracy of yield predictions for cash crops such as pepper (Capsicum annum L.) has increasingly captured the interest of many scientists in South Korea. This study marks the first initiative to develop yield prediction tools for peppers cultivated under heat stress conditions. To refine the yield prediction model, field studies were conducted to establish the plant growth curve and parameter sets for two different pepper accessions, PHR18 and PHR23, under heat stress conditions. According to field studies, the two pepper accessions exhibited distinct growth patterns under prolonged heat stress conditions. PHR18 experienced significant heat stress effects in the first month of exposure, whereas it demonstrated stress priming to regain growth by the 75th day of heat stress exposure. PHR23, having a larger leaf area, accumulated more biomass than fruit yields in the initial month of exposure, thus increasing its yields at higher temperature conditions due to enhanced photosynthesis rates. The crop growth curve and parameters were formulated based on these studies, and the open field simulations were calibrated with measured yields from multiple locations in South Korea from 2020-2024. Consequently, a robust pepper growth model was developed and employed to assess the effects of heat stress on the yields of two pepper accessions across various South Korean locations. The development of this crop growth model under stressful conditions will aid farmers and policymakers in making informed decisions during extreme events.