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Purpose: Precooling (PreC) may only benefit performance when thermal strain experienced by an individual is sufficiently high. We explored the effect of mixed-method PreC on 20-km cycling time-trial (CTT) performance under 3 different apparent temperatures (AT). Methods: On separate days, 12 trained or highly trained male cyclists/triathletes completed six 20-km CTTs in 3 different ATs: hot-dry (35 °C AT), moderately hot-humid (40 °C AT), and hot-humid (46 °C AT). All trials were preceded by 30 minutes of mixed-method PreC or no PreC (control [CON]). Results: Faster 2.5-km-split completion times occurred in PreC compared with CON in 46 °C AT (P =.02), but not in 40 °C AT (P =.62) or 35 °C AT (P =.57). PreC did not affect rectal and body temperature during the 20-km CTT. Skin temperature was lower throughout the CTT in PreC compared with CON in 46 °C AT (P =.01), but not in 40 °C AT (P = 1.00) and 35 °C AT (P = 1.00). Heart rate had a greater rate of increase during the CTT for PreC compared with CON in 46 °C AT (P =.01), but not in 40 °C AT (P =.57) and 35 °C AT (P = 1.00). Ratings of perceived exertion (P <.001) and thermal comfort (P =.04) were lower for PreC compared with CON in 46 °C AT only, while thermal sensation was not different between PreC and CON. Conclusion: Mixed-method PreC should be applied prior to 20-km CTTs conducted in hot-humid conditions (≥46 °C AT). Alternatively, mixed-method PreC may be a priority in moderately hot-humid (∼40 °C AT) conditions but should not be in hot-dry (∼35 °C AT) conditions for 20-km CTT. [ABSTRACT FROM AUTHOR]

The aim of this audit was to quantify female representation in research on heat adaptation. Using a standardized audit tool, the PubMed database was searched for heat adaptation literature from inception to February 2023. Studies were included if they investigated heat adaptation among female and male adults (≥18–50 years) who were free from noncommunicable diseases, with heat adaptation the primary or secondary outcome of interest. The number and sex of participants, athletic caliber, menstrual status, research theme, journal impact factor, Altmetric score, Field-Weighted Citation Impact, and type of heat exposure were extracted. A total of 477 studies were identified in this audit, including 7,707 participants with ∼13% of these being female. Most studies investigated male-only cohorts (∼74%, n = 5,672 males), with ∼5% (n = 360 females) including female-only cohorts. Of the 126 studies that included females, only 10% provided some evidence of appropriate methodological control to account for ovarian hormone status, with no study meeting best-practice recommendations. Of the included female participants, 40% were able to be classified to an athletic caliber, with 67% of these being allocated to Tier 2 (i.e., trained/developmental) or below. Exercise heat acclimation was the dominant method of heat exposure (437 interventions), with 21 studies investigating sex differences in exercise heat acclimation interventions. We recommend that future research on heat adaptation in female participants use methodological approaches that consider the potential impact of sexual dimorphism on study outcomes to provide evidence-based guidelines for female athletes preparing for exercise or competition in hot conditions. [ABSTRACT FROM AUTHOR]

Understanding forest water limitation during droughts within a warming climate is essential for accurate predictions of forest-climate interactions. In hyperdiverse ecosystems like the Amazon forest, the mechanisms shaping hysteresis patterns in transpiration relative to environmental factors are not well understood. From this perspective, we investigated these dynamics by conducting in situ leaf-level measurements throughout and after the 2015 El Niño-Southern Oscillation (ENSO) drought. Our findings indicate a substantial increase in the hysteresis area (Harea) among transpiration (E), vapor pressure deficit (VPD), and stomatal conductance (gs) at canopy level during the ENSO peak, attributed to both temporal lag and differences in magnitude between gs and VPD peaks. Specifically, the canopy species Pouteria anomala exhibited an increased Harea, due to earlier maximum gs rates leading to a greater temporal lag with VPD compared to the post-drought period. Additionally, leaf water potential (ΨL) and canopy temperature (Tcanopy) showed larger Harea during the ENSO peak compared to post-drought conditions across all studied species, suggesting that stomatal closure, particularly during the afternoon, acts to minimize water loss and may explain the counterclockwise hysteresis observed between ΨL and Tcanopy. The pronounced Harea during the drought points to a potential imbalance between water supply and demand, underlining the role of stomatal behavior of isohydric species in response to drought.

Humid heatwaves, characterized by high temperature and humidity combinations, challenge tropical societies. Extreme wet-bulb temperatures (TW) over tropical land are coupled to the warmest sea surface temperatures by atmospheric convection and wave dynamics. Here, we harness this coupling for seasonal forecasts of the annual maximum of daily maximum TW (TWmax). We develop a multiple linear regression model that explains 80% of variance in tropical mean TWmax and significant regional TWmax variances. The model considers warming trends and El Niño and Southern Oscillation indices. Looking ahead, the strong-to-very-strong El Niño at the end of 2023, with an Oceanic Niño Index of ∼2.0, suggests a 2024 tropical land mean TWmax of 26.2°C (25.9–26.4°C), and a 68% chance (24%–94%) of breaking existing records. This method also predicts regional TWmax in specific areas.

There are more incidents of violence in summer and on hot days, a trend likely to be exacerbated by climate change. Urban areas experience additional temperature modulation due to the urban form, however, to date, no studies have considered the effect of the urban heat island (UHI) or green space with respect to the temperature-violence relationship. This study modelled the relationship between the number of daily violent crime incidents that occurred inside or outside between July 2013 and June 2018, and the average surface UHI or percentage greencover (including grasses, shrubs and trees) within each local government area in Greater Sydney, Australia. Panelised negative binomial time series regression models indicated that the violent crime rate was associated with higher surface UHI for crimes committed outside (p = 0.006) but not inside (p = 0.072). Greater percentage of all vegetation was associated with significantly lower rates of violent crime committed outside (p = 0.011) but was not associated with violent crimes committed inside (p = 0.430). More socio-economic disadvantage was associated with higher rates of violent crime committed inside (p = 0.002) but not outside (p = 0.145). Greater temperature was non-linearly associated with higher rates of violent crime committed both inside and outside (p

Heat stress results in significant economic losses to the poultry industry. Genetics plays an important role in chickens adapting to the warm environment. Physiological parameters such as hematochemical parameters change in response to heat stress in chickens. To explore the genetics of heat stress resilience in chickens, a genome-wide association study (GWAS) was conducted using Hy-Line Brown layer chicks subjected to either high ambient temperature or combined high temperature and Newcastle disease virus infection. Hematochemical parameters were measured during three treatment phases: acute heat stress, chronic heat stress, and chronic heat stress combined with NDV infection. Significant changes in blood parameters were recorded for 11 parameters (sodium (Na+, potassium (K+), ionized calcium (iCa2+), glucose (Glu), pH, carbon dioxide partial pressure (PCO2), oxygen partial pressure (PO2), total carbon dioxide (TCO2), bicarbonate (HCO3), base excess (BE), and oxygen saturation (sO2)) across the three treatments. The GWAS revealed 39 significant SNPs (p < 0.05) for seven parameters, located on Gallus gallus chromosomes (GGA) 1, 3, 4, 6, 11, and 12. The significant genomic regions were further investigated to examine if the genes within the regions were associated with the corresponding traits under heat stress. A candidate gene list including genes in the identified genomic regions that were also differentially expressed in chicken tissues under heat stress was generated. Understanding the correlation between genetic variants and resilience to heat stress is an important step towards improving heat tolerance in poultry.

Heat stress has become one of the abiotic stresses that pose an increasing threat to maize production due to global warming. The Hsp20 gene family confers tolerance to various abiotic stresses in plants. However, very few Hsp20s have been identified in relation to maize thermotolerance. In this study, we conducted a comprehensive study of Hsp20s involved in thermotolerance in maize. A total of 33 maize Hsp20 genes (ZmHsp20s) were identified through scanning for a conserved α-crystalline domain (ACD), and they were categorized into 14 subfamilies based on phylogenetic analysis. These genes are distributed across all maize chromosomes and nine of them are in regions previously identified as heat-tolerance quantitative trait loci (hrQTL). These hrQTL-associated ZmHsp20s show variation in tissue-specific expression profiles under normal conditions, and seven of them possess 1–5 heat stress elements in their promoters. The integration of RNA-seq data with real-time RT-PCR analysis indicated that ZmHsp23.4, ZmHsp22.8B and ZmHsp18 were dramatically induced under heat stress. Additionally, these genes exhibited co-expression patterns with key ZmHsfs, which are crucial in the heat tolerance pathway. When a null mutant carrying a frame-shifted ZmHsp18 gene was subjected to heat stress, its survival rate decreased significantly, indicating a critical role of ZmHsp18 in maize thermotolerance. Our study lays the groundwork for further research into the roles of ZmHsp20s in enhancing maize's thermotolerance. [ABSTRACT FROM AUTHOR]

Autophagy is a mechanism for the degradation of cellular components in eukaryotes and plays a critical role in plant responses to abiotic stress. As a core member of the autophagy process, ATG8's role in how plants respond to heat stress remains unclear. To investigate the response of the tomato autophagy core member ATG8f to heat stress, we studied the key gene ATG8f and generated tomato lines overexpressing SlATG8f using the recombinant expression vector pBWA(V)HS. We observed that under heat stress, SlATG8f overexpression (OE) plants exhibited decreased heat tolerance compared to wild-type (WT) plants. Specifically, OE plants showed increased relative electrolyte leakage, reduced soluble solid content, elevated chlorophyll content, and higher autophagosome numbers, with less damage to chloroplasts and mitochondria. Additionally, expression of some ATG8 family genes and heat shock protein-related genes was upregulated. Moreover, SlATG8f overexpressing plants had higher pollen vitality and more intact pollen morphology. These results suggest that while SlATG8f overexpression renders plants more sensitive to heat, it helps mitigate high-temperature damage to tomato pollen by maintaining chloroplast integrity and interacting with heat shock proteins to respond to heat stress. [ABSTRACT FROM AUTHOR]

Increasing global temperatures and the incidence of extreme weather conditions will result in heat stress becoming a greater issue in production animals. Genetic selection and breeding for heat-tolerant animals have been promoted as a possible mitigation strategy in dairy cattle. The objectives of this study were to obtain in-field skin temperature measurements of the eye, muzzle and udder using infra-red thermography to examine the genetic variation in skin temperature within cows of a dairy herd and to estimate the genetic correlations between skin temperature and production traits. Thermal images and herd test records were obtained for the dairy herd at Massey University’s dairy farm 1. Estimates of (co)variances were obtained using the JWAS program with univariate and bivariate animal models. The heritability estimates for the eye, muzzle and udder temperature were low to moderate at 0.20, 0.24 and 0.39, respectively. All genetic correlations between production and temperature traits were positive except for eye temperature with milk yield and protein yield which was negative and weak. These results indicate that it may be possible to select for a greater skin temperature, however, these results need to be validated using a larger sample size. [ABSTRACT FROM AUTHOR]

Heat stress poses a substantial challenge to poultry production worldwide, highlighting the urgent need for effective management strategies. This study investigated the efficacy of probiotics (Saccharomyces cerevisiae) and ascorbic acid as antistress agents using cloacal and body surface temperatures (CT and BST) as heat stress biomarkers in broiler chickens. A total of 56 broiler chicks were used for the experiment and were divided into four distinct groups: control, probiotics (1 g/kg of feed), ascorbic acid (200 mg/kg of feed) and the combination of probiotics and ascorbic acid (1 g/kg and 200 mg/kg of feed, respectively). The study lasted 35 days; measurements were taken for ambient temperature (AT), CT, and BST. The ambient temperature in the pens consistently exceeded the thermoneutral zone (TNZ) established for broiler chickens. The CT values for broiler chickens in the probiotic group were significantly lower (p < 0.05) compared to the control group. Additionally, the BST values in the probiotic and probiotic + ascorbic acid groups were significantly lower (p < 0.05) than those in the control group. The findings suggest that incorporating probiotics, with or without ascorbic acid, can effectively reduce CT and BST values in broiler chickens thereby, enhancing thermoregulation when compared to the control group. This implies that using probiotics in poultry diets may enhance health and growth performance, potentially leading to better feed efficiency and reduced reliance on antibiotics. Implementing these dietary strategies could improve the productivity and welfare of broiler chickens in commercial settings. [ABSTRACT FROM AUTHOR]

With global warming, heat stress has been recognized as a significant factor limiting grapevine development and fruit quality. MicroRNAs (miRNAs) are a class of small non-coding RNAs known to play crucial regulatory roles in stress resistance. Hence, there is an immediate requirement to cultivate and identify grapevine varieties that are resistant to heat and explore miRNA-mediated heat stress defense mechanisms. In this study, we assessed the thermal resistance of 38 grape germplasm resources and identified a series of miRNAs involved in heat stress resistance. The CK (25°C) and HS (45°C) groups of "Shenyue" cuttings of grapes were used as experimental materials for next-generation sequencing and construct libraries of small RNAs. A total of 177 known and 20 novel miRNAs were detected in the libraries. Differential expression analysis identified 65 differentially expressed miRNAs (DEMs) using the DE-Seq procedure. Furthermore, RT-qPCR validation confirmed complementary expression profiles of eight DEMs and their target genes between the HS and CK groups. Heterologous transformation further identified the function of Vvi-miR3633a downregulated under heat stress in Arabidopsis. In the heterologous expression lines, the survival rate was reduced by high temperature treatment indicating the ability of Vvi-miR3633a to regulate heat resistance. Assessing the heat resistance of grape species and the expression patterns of miRNA in response to high temperatures may reveal the molecular processes of heat resistance regulation mediated by miRNA in grapes under heat stress. [ABSTRACT FROM AUTHOR]

Summary Heat stress (HS) has become a major factor limiting crop yields worldwide. HS inhibits plant growth by ROS accumulation, and NADPH oxidases (Rbohs) are major ROS producers in plants. Here, we show that CRISPR/Cas knockout of the OsRbohB (OsRbohB‐KO) significantly increased rice tolerance to HS imposed at various different growth stages. We produced OsRbohB‐KO and OsRbohB‐overexpression (OsRbohB‐OE) lines in a japonica cultivar, Nipponbare. Compared with nontransgenic wild‐type (WT) plants, the OsRbohB‐KO lines showed a significant increase in chlorophyll contents (5.2%–58.0%), plant growth (48.2%–65.6%) and grain yield (8.9%–20.5%), while reducing HS‐induced ROS accumulation in seeds (21.3%–33.0%), seedlings (13.0%–30.4%), anthers (13.1%–20.3%) and grains (9.7%–22.1%), under HS conditions. Analysis of yield components revealed that the increased yield of OsRbohB‐KO plants was due to increased starch synthetase activity, spikelets per panicle (2.0%–9.3%), filled spikelets (4.8%–15.5%), percentage of filled spikelets (2.4%–6.8%) and 1000‐grain weight (2.9%–7.4%) under HS conditions during the reproductive stage. Grain milling and appearance quality, and starch content were also significantly increased in OsRbohB‐KO plants under HS conditions during the mature stage. Furthermore, OsRbohB‐KO significantly upregulated the expression levels of heat shock‐related genes, OsHSP23.7, OsHSP17.7, OsHSF7 and OsHsfA2a, in rice seedlings and grains under long‐term HS conditions. Conversely, OsRbohB‐OE resulted in phenotypes that were opposite to OsRbohB‐KO in most cases. Our results suggest that suppression of OsRbohB provides an effective approach for alleviating heat damage and improving grain yield and quality of rice under long‐term HS conditions. [ABSTRACT FROM AUTHOR]

The general objective of this study is to comparatively assess the climate-resilient potential of four different poultry genotypes-Giriraja (n = 8), Country chicken (n = 8), Naked neck (n = 8), and Kadaknath (n = 8)—reared in a hot-humid tropical environment. Birds from all genotypes had ad libitum access to feed and water and were exposed to identical environmental temperatures in the experimental shed. Diurnal meteorological data were recorded inside and outside the shed daily. Blood biochemical, hormonal, and endocrine variables were monitored monthly until the birds reached 12 weeks of age. Significant variations (P < 0.01) were observed at different intervals in variables, including total protein, albumin, globulin, triglycerides, and cholesterol. Genotype-specific differences were noted in triglycerides (P < 0.01), albumin (P < 0.01), total protein (P < 0.05), and cholesterol (P < 0.05). Inter-genotype variations (P < 0.05) were also observed in serum cortisol, T3, and T4 levels. Distinct variations (P < 0.05) were also observed during specific intervals, particularly in cortisol and T3 levels. The study of hepatic mRNA expression of HSPs and HSF-1 revealed a significant breed difference (P < 0.05) in the expression pattern of HSP60, HSP70, HSP90, and HSP110, while no difference was observed between genotypes for HSP40 and HSF-1. The study highlights the Naked Neck breed as an exemplar of resilience, showcasing its distinctive ability to maintain homeostasis under heat stress compared to other genotypes. The genetic and physiological insights gained from this investigation offer prospective pathways for aligning sustainable poultry farming with environmental exigencies. [ABSTRACT FROM AUTHOR]

Exposure to heat stress can cause a significant increase in the death rate and disease susceptibility of poultry birds, ultimately impacting the profitability of the poultry industry. Despite being a more economical choice, Japanese quails (Coturnix japonica) are not immune to the harmful effects of heat stress. Quails may experience negative effects on their reproductive performance due to excessive reactive molecules caused by heat stress. However, they have developed various mechanisms to maintain their reproductive abilities in such conditions. The neuroendocrine system in birds plays a vital role in regulating their reproductive responses to thermal stress, and it is also connected to other environmental factors such as photoperiod that can impact their reproductive performance. Hormones are crucial in the complex interactions necessary for sexual maturation and reproductive responses to heat stress in Japanese quails living in stressful thermal conditions. [ABSTRACT FROM AUTHOR]

Purpose: The current study investigated whether sustained mild dehydration affects thermoregulatory function and cognitive performance during prolonged exercise. Methods: Twelve young adults performed a test consisting of three sets of 20-min exercise with 2-min intervals under euhydrated (control, CON) and mildly dehydrated conditions (MDEH) at an ambient temperature of 30 °C and 60% relative humidity. MDEH was established by restricting water intake for 24 h, resulting in urine specific gravity of ≥ 1.020. Heart rate (HR), mean arterial blood pressure (MAP), skin blood flow (SkBF), sweat rate (SR) on the chest and forearm, and ear canal and mean skin surface temperatures (Tear and mean Tskin, respectively) were continuously recorded. For each exercise set, thermal and humid sensations and thermal discomfort were assessed using visual analog scales (VAS), and the rating of perceived exertion (RPE) was estimated. Cognitive performance on the Go/No-Go (easy) and incongruent Stroop (difficult) tasks was assessed before and after the test. Results: No differences were observed in HR, MAP, SkBF, SR, Tear, and mean Tskin between the CON and MDEH. Thermal and humidity sensations, thermal discomfort, and RPE were higher in MDEH than in CON. Moreover, response time to the Stroop task was prolonged in MDEH. Conclusion: These findings suggest that sustained mild dehydration does not affect autonomic thermoregulation during exercise. Augmented thermal perception and perceived exertion, which are necessary for behavioral thermoregulation, were noted; however, cognitive function may be attenuated under MDEH. [ABSTRACT FROM AUTHOR]

Purpose: We tested the hypothesis that heat stress influences the closed-loop cardio-postural control by an increased blood pressure (BP) drop and postural sway. Methods: Fourteen healthy individuals (eight women) performed two orthostatic tests under thermal reference (TC; ~ 24 ºC) and HOT (~ 38 ºC) conditions. The center-of-pressure (COP) displacements and the electromyography (EMG) activity of the calf muscles (medial gastrocnemius and tibialis anterior) were recorded during the initial orthostasis (ORT onset) after the supine-to-stand challenge. At the same period, BP (beat-to-beat) was continuously monitored, and supine-to-stand variations (∆%) were calculated. Sublingual temperature (Tsl) was measured as a surrogate of internal temperature. Results: Tsl increased in HOT compared to TC (TC 36.5 ± 0.3 vs. HOT 36.7 ± 0.3 ºC; p < 0.01). COP distance was greater in HOT compared to TC condition (TC 596.6 ± 242.4 vs. HOT 680.2 ± 249.1 mm; p < 0.01). EMG activity of the gastrocnemius decreased in HOT compared to TC condition (TC 95.5 ± 19.8 vs. HOT 78.4 ± 22.8%mV; p = 0.02). EMG of tibialis did not change between TC and HOT (TC 83.5 ± 42.9 vs. HOT 66.1 ± 31.9% mV; p = 0.29). BP showed a greater fall in HOT compared to TC condition (∆%TC − 24.5 ± 13.2 vs. ∆%HOT − 33.2 ± 20.2%; p = 0.01). Conclusion: Heat stress causes a greater fall in blood pressure and a reduction in musculoskeletal pump activity during orthostatic onset. These effects could be potential mechanisms that underlie augmented postural instability under a heated environment. [ABSTRACT FROM AUTHOR]

Exposure to temperatures outside of a fish's optimal range results in suppression of the immune system, ultimately leaving aquaculture stocks susceptible to disease outbreaks. This effect is exacerbated in triploid fishes, which demonstrate greater susceptibility to stress than their diploid counterparts. This study investigates the impacts of acute heat stress on the abundance of immune transcripts and proteins in diploid and triploid Chinook salmon (Oncorhynchus tshawytscha), an important finfish crop. This study also demonstrates that acute heat stress induces significant increases in the abundance hsp70, hsp90 and il1b transcripts in the head kidneys, gills and heart ventricles of both diploid and triploid Chinook salmon. Widespread dysregulation of antigen‐presentation transcripts was also observed in fish of both ploidies. These results suggest that acute heat stress activates acute‐phase responses in Chinook salmon and dysregulates antigen presentation, potentially leaving fish more susceptible to infection. At the protein level, IL‐1β was differentially expressed in the head kidney and ventricles of diploid and triploid salmon following heat shock. Differential expression of two tapasin‐like proteins in diploid and triploid salmon subjected to heat shock was also observed. Altogether, these data indicate that diploid and triploid Chinook salmon respond differently to acute thermal stressors. [ABSTRACT FROM AUTHOR]

Spray drying is a promising technique for embedding and stabilizing lactic acid bacteria. However, bacteria are unable to withstand high-temperature environment. Naturally small molecules fall short in meeting the evolving demands of production. Therefore, it is imperative to explore non-chemical pretreatment methods urgently, with the aim of enhancing their protective efficacy. In this study, natural deep eutectic solvents (NADES) were synthesized by glycerin-betaine to improve the survival rates of spray-dried Lactobacillus bulgaricus sp1.1. Results revealed that the spray drying survival rate of L. bulgaricus sp1.1 after adding NADES was 30.54%, which was 4.72 times higher than adding equal amounts of untreated glycerin and betaine, and the number of viable bacteria decreased less than 1 log after 6 months of storage. The investigation revealed that the impact of NADES was localized external to the cell rather than within. Through crosslinking with the peptidoglycan on the cell wall, NADES bolstered the cell wall structure thereby creating a protective barrier. This resulted in a reduction of damage to the membrane and ribosome induced by high temperatures during the lactic acid bacteria's exposure. This study synthesized NADES using current protective agents as an effective method to enhance heat resistance of lactic acid bacteria for spray drying for the first time, and the lactic acid bacteria powder with high survival rate and high storage stability was successfully prepared, which provides a new approach for its industrial application. [ABSTRACT FROM AUTHOR]

Key message: Barley reproductive fitness and efficient heat stress adaptation requires the activity of TFIIS, the elongation cofactor of RNAPII. Regulation of transcriptional machinery and its adaptive role under different stress conditions are studied extensively in the dicot model plant Arabidopsis, but our knowledge on monocot species remains elusive. TFIIS is an RNA polymerase II-associated transcription elongation cofactor. Previously, it was shown that TFIIS ensures efficient transcription elongation that is necessary for heat stress survival in A. thaliana. However, the function of TFIIS has not been analysed in monocots. In the present work, we have generated and studied independent tfIIs-crispr-mutant barley lines. We show that TFIIS is needed for reproductive development and heat stress survival in barley. The molecular basis of HS-sensitivity of tfIIs mutants is the retarded expression of heat stress protein transcripts, which leads to late accumulation of HSP chaperones, enhanced proteotoxicity and ultimately to lethality. We also show that TFIIS is transcriptionally regulated in response to heat, supporting a conserved adaptive function of these control elements for plant thermal adaptation. In sum, our results are a step forward for the better understanding of transcriptional machinery regulation in monocot crops. [ABSTRACT FROM AUTHOR]

Developmental environmental stressors can have instructive effects on an organism's phenotype. This developmental plasticity can prepare organisms for potentially stressful future environments, circumventing detrimental effects on fitness. However, the physiological mechanisms underlying such adaptive plasticity are understudied, especially in vertebrates. We hypothesized that captive male zebra finches (Taeniopygia castanotis) exposed to a mild heat conditioning during development would acquire a persisting thermotolerance, and exhibit increased heat‐shock protein (HSP) levels associated with a decrease in oxidative damage when exposed to a high‐intensity stressor in adulthood. To test this, we exposed male finches to a prolonged mild heat conditioning (38°C) or control (22°C) treatment as juveniles. Then in a 2 × 2 factorial manner, these finches were exposed to a high heat stressor (42°C) or control (22°C) treatment as adults. Following the adult treatment, we collected testes and liver tissue and measured HSP70, HSP90, and HSP60 protein levels. In the testes, finches exhibited lower levels of HSP90 and HSP60 when exposed to the high heat stressor in adulthood if they were exposed to the mild heat conditioning as juveniles. In the liver, finches exposed to the high heat stressor in adulthood had reduced HSP90 and HSP60 levels, regardless of whether they were conditioned as juveniles. In some cases, elevated testes HSP60 levels were associated with increased liver oxidative damage and diminishment of a condition‐dependent trait, indicating potential stress‐induced tradeoffs. Our results indicate that a mild conditioning during development can have persisting effects on HSP expression and acquired thermotolerance. Research Highlights: Our results indicate that a mild heat conditioning during development can induce an increase in thermotolerance that persists into adulthood, and results in variation in testes and liver heat‐shock protein expression in response to heat stress. [ABSTRACT FROM AUTHOR]

As global warming continues, safeguarding the health and safety of construction workers in extremely hot environments becomes imperative. Real-time and quantitative assessment of workers' cognitive states affected by heat stress is essential. Previous studies, which relied mainly on cognitive performance tests and subjective questionnaires, lacked the capability for real-time tracking of individual cognitive states. The analysis of physiological responses also faced challenges in quantitative evaluation of individual cognitive states. To address these issues, this study proposed a reliable and quantitative approach to explore the negative impact of heat stress on cognitive states such as attention, mental fatigue, and emotion, using electroencephalogram (EEG) metrics in immersive virtual reality (VR)–based construction safety training. This study recruited 20 volunteers, divided evenly between an experimental group exposed to extreme heat (36°C/70%) and a control group in moderate heat (26°C/45%). All participants experienced simulated hazardous working conditions across four distinct VR training scenarios. The findings revealed significant differences in attention control, fatigue, and arousal between the two groups, demonstrating that extreme heat impairs workers' attention, increases fatigue, and heightens arousal. These conditions could potentially increase unsafe actions and accident rates, posing risks to construction worker safety. The identified EEG metrics provide a strategy for the real-time and quantitative evaluation of workers' cognitive states under heat stress. Furthermore, it is expected to develop a heat stress monitoring and diagnostics framework integrating VR and augmented reality (AR) technologies to enhance worker safety in extremely hot environments. [ABSTRACT FROM AUTHOR]

Spermatogenesis in eukaryotes is a process that occurs within a very narrow temperature threshold, typically not exceeding 36 °C. SPO11 was isolated from the temperature-sensitive mutant receptor of Saccharomyces cerevisiae and is thought to be the only protein that functions during meiosis. This suggested that SPO11 may be the key protein that influenced the temperature of spermatogenesis not exceeding 36 °C. Elevated temperatures typically damage the spermatogenic cells. Birds have a core body temperature of 41–42 °C, and their testis are located inside their bodies, providing an alternative perspective to investigate the potential impact of temperature threshold on spermatogenesis. The objective of this study was to ascertain whether elevated ambient temperatures affect spermatogenesis in birds and whether SPO11 is the key gene affecting the temperature threshold for spermatogenesis. STRA8, SCP3, SPO11, γ-H2AX, and RAD51 were all crucial components in the process of meiotic initiation, synapsis, DNA double-strand break (DSB) induction, homologous chromosome crossover recombination, and repair of DSB. In this study, 39-day-old Japanese quail were subjected to heat stress (HS) at 38 °C for 8 h per day for 3 (3d HS) and 13 (13d HS) consecutive days and analyzed the expression of meiotic signaling molecules (STRA8, SCP3, SPO11, γ-H2AX, and RAD51) using molecular biology techniques, including Immunohistochemistry (IHC), Western Blot (WB), and Real-time Quantitative Polymerase Chain Reaction (qRT-PCR). We found that spermatogenesis was normal in both groups exposed to HS. Meiotic signaling molecules were expressed normally in the 3d HS group. All detected signaling molecules were normally expressed in the 13d HS group, except for SPO11, which showed a significant increase in expression, indicating that SPO11 was temperature-sensitive. We examined the localized expression of each meiotic signaling molecule in quail testis, explored the temperature sensitivity of SPO11, and determined that quail testis can undergo normal spermatogenesis at ambient temperatures exceeding 36 °C. This study concluded that SPO11 is not the key protein influencing spermatogenesis in birds. These findings enhance our understanding of avian spermatogenesis. [ABSTRACT FROM AUTHOR]

Abiotic stresses, such as heat, drought and salinity, affect the development of wheat crop and hinder its expansion to the central region of Brazil. The identification of genotypes tolerant to these conditions is important for improving yield performance. The present research evaluated the impact of different abiotic stresses on germination and seedling development and selected wheat genotypes tolerant to these stresses, using multi-trait analysis. Heat, drought and salinity stresses were induced in seeds of 23 wheat genotypes. Seed germination, seedling length and dry mass were evaluated. An adaptability and stability model and a multi-trait selection index were applied to the data. Drought and salinity negatively affected the development of seedlings of the 23 evaluated genotypes. However, the VI 14055, ORS Madre Pérola and BRS 404 genotypes conferred the best adaptability and stability results and were selected by the MGIDI, which revealed that great performance can be achieved in regions with potential for abiotic stress, in the early stages of development. [ABSTRACT FROM AUTHOR]

The study investigated selenium’s (Se) efficiency in preserving South African Zulu rams’ sperm quality and testicular parameters when they were exposed to heat stress. Indigenous Zulu rams (20) between 2 and 5 years old were allocated into four groups, namely the Se, testicular heat stress (THS), selenium plus testicular heat stress (SeTHS), and control. Each group comprised five rams; the groups were balanced according to the rams’ body weight and scrotal circumference. The Se and SeTHS groups received sodium selenite orally bi-weekly for 5 months. To induce heat stress, testicular heat insulation bags were wrapped around the testes of the rams receiving the THS and SeTHS treatments for 49 days. Semen was collected from the rams weekly from the third month onward; the first two months were for Se & THS acclimatization. In addition, testicular measurements were taken bi-weekly. Analysis of variance was used to analyze the sperm quality data. Duncan’s multiple range test was used to compare the groups’ data for significant differences. The results showed that the Se-supplemented rams’ scrotal circumference was smaller (p < 0.05) compared with the other groups. The Se, SeTHS, and control groups demonstrated similar total sperm motility; in contrast, the THS and SeTHS groups recorded low and high total sperm motility, respectively, compared with other treatment groups (p < 0.05). The semen from the rams that received THS without Se displayed a significantly higher number of immotile sperm cells (p < 0.05) and poor sperm quality, including total and progressive motility, and kinematic parameters when compared with other treatments, suggesting that Se protects sperm against THS. We concluded that selenium protected some sperm parameters (TSM, PSM, MV, VCL, VSL) of THS- treated rams while others did not improve (RV, NSM, C, STR). [ABSTRACT FROM AUTHOR]

This study aimed to investigate the effect of diet supplementation with a symbiotic (SY), bee pollen (BP), honey bee (HB), date palm pollen (DPP) and their mixture (MIX) on female rabbit productive and reproductive performances under desert hot climates. Seventy-two Californian does of 5 months age and average body weight of 3250 ± 78.2 g were randomly allotted into six groups, each of 12 does. All does orally receive 3 ml distilled water for 10 days before mating and 28 days during pregnancy. Treatments were repeated for four consecutive parities. The first group served as control (C) given distilled water only, however the second, third, fourth and fifth groups were supplemented with 3 ml distilled water containing 0.2 ml SY, 200 mg DPP, 200 mg BP, 0.2 ml HB/doe per day, respectively. While, the sixth group does were given all previous ingredients (MIX). Sexual receptivity rate, fertility rate, kindling rate, and newborn traits were recorded. Also, maternal feed intake, feed conversion ratio, and digestibility coefficients of nutrients were recorded. Does in all groups were artificially inseminated with 0.5 ml of fresh heterospermic semen of 15 fertile bucks extended in Tris at 806–1006 sperm/ml. Treatment increased maternal body weight and daily gain with highest values (P < 0.05) in BP, SY, and MIX does. All treatments enhanced feed intake and feed conversion ratio (FCR) compared with control. Number services per conception decreased (P < 0.01), while litter size and weight and survival at birth and weaning increased (P < 0.01) in treated than control does. Treated does produced more milk than control. Digestibility coefficients of all nutrients were improved (P < 0.01) in treated does. In conclusion, supporting rabbit does pre- and during pregnancy with diets supplemented with a mixture of honey bee, date palm pollen, bee pollen, and synbiotic improves the productive and reproductive performances of rabbit does and their offspring. [ABSTRACT FROM AUTHOR]

Sweat absorbed by clothing forms a moisture film on fabric surfaces, reducing fabric breathability and disrupting thermoregulation during exercise in a hot environment. We investigated whether T‐shirts made from a newly developed fabric with hydrophobic and water‐repellent fibers near the through holes could prevent sweat film formation, thereby enhancing intraclothing microclimate and thermoregulatory responses. Thirteen male runners completed 30‐min treadmill sessions at moderate and high intensities while wearing either the new fabric T‐shirt (Dry Aeroflow, DAF) or a polyester T‐shirt (CONT) at an ambient temperature of 32°C and a relative humidity of 50% with an air velocity of 0.8 m/s. Compared with CONT, intraclothing humidity was decreased on the chest and back, and chest but not back skin temperature was decreased by 2°C in DAF. However, thermoregulatory key variables such as rectal temperature, mean skin temperature, sweat rates, and heart rate did not differ between the T‐shirts. We concluded that the a T‐shirt with enhanced breathability does not affect overall thermoregulatory response during exercise in the heat despite the partial improvements in intraclothing microclimate and in reducing local skin temperature. [ABSTRACT FROM AUTHOR]

This study investigated the effects of in ovo betaine and thermal manipulation during incubation on growth performance, and some immune parameters of broilers under cyclic heat stress (CHS). Eggs were divided into 5 groups and incubated at 1) 37.8 °C and 60% relative humidity (Control incubation and not-injected, CI); 2) eggs were incubated at CI and in ovo betaine injected into yolk sac on d 11 (E11) (CI + In ovo); 3) eggs were exposed to 38.8 °C for 8 h between 10 and 18d of incubation (heat acclimation, HA); 4) eggs were incubated at HA and in ovo betaine applied (HA + In ovo); 5) positive control: eggs were incubated at CI and injected with saline. Hatched chicks were raised under standard management conditions until 21 d, between 21 and 42 d half of the chickens in each incubation treatment were kept either at optimum (OPT) or at CHS. In ovo and HA did not affect hatching performance. In ovo increased thymus and spleen weights of chicks. Serum IgG was higher in HA + In ovo chicks. From d 7 to 21, in ovo chicks were heavier body weights, consumed more feed, and better feed conversion than those from CI. The body weights of HA chickens were similar in OPT and CHS on d 28 and 35. CHS reduced the body weight of CI chickens which was compatible with their feed consumption. Moreover, feed intake of HA + In ovo chickens exposed to CHS was higher than those not injected indicating that HA + In ovo enhanced thermoregulation of chickens under CHS. [ABSTRACT FROM AUTHOR]

Seasonal variations significantly impact buffalo bull semen production and quality, particularly during the summer months. Understanding the genetic basis of these changes is important for managing bull fertility and improving sperm quality. The present study focused on characterizing and identifying polymorphisms in chromatin remodeling genes, protamines (PRMs) and Transition Nuclear Proteins (TNPs) in Murrah buffalo bulls with varying semen quality due to seasonal effects. Our findings revealed none of the coding region variation in PRM1, PRM2, TNP1, and TNP2, these genes are highly conserved in buffalo. Two intronic variants were identified, including G16C in PRM1 intron 1 and intronic SNP in PRM2 intron 1 (G96A). The complete CDS of consensus sequence of bubaline PRM1 was 86.3% identical and 94.1% similar to the bovine PRM1. Whereas the complete CDS of consensus sequence of bubaline TNP2 was 78.2% identical and 91.0% similar to bovine TNP2. Further, no statistically significant differences in the fold change of TNP1, TNP2, PRM1, and PRM2 levels between the hot summer SNA and SA groups and the winter SNA and SA groups This study represents the first comprehensive report on the characterization of bubaline PRM1 (complete CDS), PRM2 (partial CDS), TNP1 (partial CDS), and TNP2 (complete CDS) genes in buffalo sperm cells. Results of the study, clearly indicate that the genes associated with protamine (PRM1 and TNP2) are highly conserved in Bubalus bubalis. Understanding these genetic underpinnings can have implications for improving buffalo bull fertility and semen quality. [ABSTRACT FROM AUTHOR]

Heat stress has various detrimental effects on poultry production. The aim of the study was to alleviate the effects of heat stress in broiler production. For this purpose, 288 one-day-old broiler chicks (Ross 308) were obtained from a commercial hatchery and randomly allocated to one of three treatment groups; CON: corn-soybean meal based commercial diet, SEO100: CON with 100 mg/kg Sage essential oil (SEO) and SEO200: CON with 200 mg/kg SEO with 96 birds in each group (4 replicates each) in a completely randomized design under hot ambient temperatures for 42 days. No differences were observed in the body weight, feed intake, and feed conversion ratio at 42 days of age among groups. However, there was a significant increase in 21-day body weight in SEO200 chicks compared to CON. Furthermore, the addition of SEO significantly decreased the mortality rate under heat stress conditions. The total oxidant status value was lower in broiler chickens in which SEO was added to their diets. While the total antioxidant status value was higher in SEO100 chicks, it did not show a linear increase. Additionally, the results demonstrated that the addition of SEO to broiler diets under heat stress did not have a significant effect on inspected meat quality traits, with the exception of the b*(yellowness) value of breast muscle. In conclusion, the results of this study indicate that 200 mg/kg SEO can be added to diets for the welfare of broiler chickens under heat stress conditions for struggling with oxidants and increasing viability. Further research is needed to investigate the antioxidant activity and meat quality of different levels of SEO in hot ambient conditions. [ABSTRACT FROM AUTHOR]

Heat stress is a condition that impairs the animal’s productive and reproductive performance, and can be monitored by physiological and environmental variables, including body surface temperature, through infrared thermography. The objective of this work is to develop computational models for classification of heat stress from respiratory rate variable in dairy cattle using infrared thermography. The database used for the construction of the models was obtained from 10 weaned heifers, housed in a climate chamber with temperature control, and submitted to thermal comfort and heat wave treatments. Physiological and environmental data were collected, as well as thermographic images. The machine learning modeling environment used was IBM Watson, IBM’s cognitive computing services platform, which has several data processing and mining tools. Classifier models for heat stress were evaluated using the confusion matrix metrics and compared to the traditional method based on Temperature and Humidity Index. The best accuracy obtained for classification of the heat stress level was 86.8%, which is comparable to previous works. The authors conclude that it was possible to develop accurate and practical models for real-time monitoring of dairy cattle heat stress. [ABSTRACT FROM AUTHOR]

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Wildlife faces an increasing threat from extreme climatic events, such as heatwaves, which can have a severe impact on various species, including crucial pollinators like bumblebees. Bumblebees are cold‐adapted and heterothermic, possessing the ability to regulate their internal temperature. The impact of heat stress seems species specific in bumblebees. While most species are impacted, some bumblebee species manage to survive, potentially by employing physiological mechanisms, including the modulation of their protein profile (e.g. Heat Shock Proteins). However, there is limited understanding of how their protein profiles are associated with heat exposure. In this study, we examined the global variation in the protein profile of males from two bumblebee species sampled in the wild: the heat‐tolerant Bombus terrestris and the heat‐sensitive Bombus magnus. After subjecting them to heat stupor at 40°C in controlled condition, it was observed that nearly all B. terrestris survived the stress, while over 50% of B. magnus individuals succumbed to the heat exposure. Through off‐gel bottom‐up proteomics and LC–MS/MS analysis of the hemolymph proteome, we identified 164 proteins in both species with a large part of differentially expressed proteins after heat exposure. Additionally, quantitative analysis of fat bodies revealed that the relative mass was stable in B. terrestris, while it was significantly lower in B. magnus exposed to heat stress. Our data suggest that compared with B. magnus, B. terrestris displays a higher adaptability of its hemolymph proteome in response to heat stress. This adaptability could be a key factor contributing to the high physiological resistance of B. terrestris and its ability to adapt to new, stressful environments expected due to climate change. Understanding these mechanisms of protein regulation in bumblebees could provide valuable insights into their resilience and vulnerability facing environmental stresses. [ABSTRACT FROM AUTHOR]

Background: Extensive research on the diversity and functional roles of the microorganisms associated with reef-building corals has been promoted as a consequence of the rapid global decline of coral reefs attributed to climate change. Several studies have highlighted the importance of coral‐associated algae (Symbiodinium) and bacteria and their potential roles in promoting coral host fitness and survival. However, the complex coral holobiont extends beyond these components to encompass other entities such as protists, fungi, and viruses. While each constituent has been individually investigated in corals, a comprehensive understanding of their collective roles is imperative for a holistic comprehension of coral health and resilience. Results: The metagenomic analysis of the microbiome of the coral Oculina patagonica has revealed that fungi of the genera Aspergillus, Fusarium, and Rhizofagus together with the prokaryotic genera Streptomyces, Pseudomonas, and Bacillus were abundant members of the coral holobiont. This study also assessed changes in microeukaryotic, prokaryotic, and viral communities under three stress conditions: aquaria confinement, heat stress, and Vibrio infections. In general, stress conditions led to an increase in Rhodobacteraceae, Flavobacteraceae, and Vibrionaceae families, accompanied by a decrease in Streptomycetaceae. Concurrently, there was a significant decline in both the abundance and richness of microeukaryotic species and a reduction in genes associated with antimicrobial compound production by the coral itself, as well as by Symbiodinium and fungi. Conclusion: Our findings suggest that the interplay between microeukaryotic and prokaryotic components of the coral holobiont may be disrupted by stress conditions, such as confinement, increase of seawater temperature, or Vibrio infection, leading to a dysbiosis in the global microbial community that may increase coral susceptibility to diseases. Further, microeukaryotic community seems to exert influence on the prokaryotic community dynamics, possibly through predation or the production of secondary metabolites with anti-bacterial activity. 5jxNwVcR-vUc4t1YJ-ryph Video Abstract [ABSTRACT FROM AUTHOR]

Background: A recent study has shown that niacin supplementation induces the conversion of type II to type I muscle fibres, thereby promoting a phenotypic shift in oxidative metabolism in porcine skeletal muscle. These effects may be mediated by modulation of the AMPK1/SIRT1 pathway, which activates peroxisome proliferator-activated receptor γ coactivator-1a (PGC-1a), a key regulator of fibre conversion, thereby promoting skeletal muscle mitochondrial biogenesis and myofibre conversion. In this study, we explored how niacin (NA) supplementation impacts the quality of meat and the characteristics of muscle fibers in Taihe Black-bone Silky Fowls (TBsf) exposed to heat conditions. Methods: Chickens were rationally assigned to five different treatment groups with five replicates of six chickens each: thermophilic (TN), heat stress (HS) and HS + NA (HN) groups, with the HN group being supplemented with 200, 400 and 800 mg/kg (HS + NA0.02, HS + NA0.04 and HS + NA0.08) NA in the premix, respectively. Results: The results of the experiment showed that addition of 800 mg/kg NA to the diet significantly improved TBsf muscle tenderness compared to HS. Dietary enrichment with 200-800 mg/kg NA significantly increased total antioxidant capacity, superoxide dismutase, and glutathione peroxidase activities, while significantly decreasing malondialdehyde compared to HS. Incorporation of 200-800 mg/kg NA into the diet significantly reduced lactate dehydrogenase activity and myosin heavy chain (MyHC-IIB) gene expression. Furthermore, adding 800 mg/kg NA can significantly enhance the mRNA expression of mitochondrial transcription factors (TFAM and TFB1M) in TBsf skeletal muscle. Adding 400 and 800 mg/kg of NA significantly increased the mRNA expression of AMP-activated protein kinase 1 (AMPK1), PGC-1a, cytochrome c oxidase (Cytc), and nuclear respiratory factor (NRF-1) in the skeletal muscle of TBsf. Supplementing NA at 200-400 mg/kg significantly increased the expression of Sirtuin 1 (SIRT1) mRNA in TBsf skeletal muscle. Conclusion: The experimental results showed that the addition of NA to the diet reduced the shear force of TBsf muscle under heat exposure conditions. It increased the proportion of type I muscle fibres by increasing the antioxidant capacity of the muscle and by promoting mitochondr fibreial biogenesis. Considering the results of this study, it is recommended that TBsf be supplemented with 400-800 mg/kg of NA in the diet to reduce the adverse effects of heat stress on meat quality. [ABSTRACT FROM AUTHOR]

China's global infrastructure financing flagship, the Belt and Road Initiative (BRI) encompasses countries hosting over 60% of the global population and one-third of worldwide GDP. It is based mainly on long-term loans that will mature decades into the future, and timely repayments are only possible if they remain commercially viable. But despite its vast global scope, little is known about the climate risks that could imperil the operations of BRI projects over the next few decades, and, consequently, threaten their long-term sustainability. We narrow this gap by estimating the impacts of future climate change on 217 BRI projects across 70 countries and 9 sectors in two dimensions. First, the effects of increased heat stress on human physical work capacity are calculated using the wet bulb globe temperature and an assessment of the workload for each selected BRI project. Second, the potential structural damages from more frequent flooding incidents are measured by return period (RP), where a shorter RP signals heightened risk. Both have direct impacts on human productivity and infrastructural integrity, which are essential to maintaining the operational viability and financial stability of BRI projects. We compared projected changes on both measures for the mid- and late-twentieth centuries (2041–2060 and 2081–2100) to the historical baseline (1981–2010). We found that BRI projects face escalating vulnerability to climatic risks on both counts. The results underscore a broad variance across different future carbon emission scenarios measured under the Shared Socioeconomic Pathways (including SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5). BRI's aggregated climatic risks are substantially elevated under a high carbon emission scenario compared to a low emission scenario. By the end of the twentieth century, labor workability under SSP3-7.0 (31%) could potentially decrease three times more compared to SSP1-2.6 (10%). Under an intermediate-emission scenario (SSP2-4.5), floods with a historical return period of 10 years could have a return period of 5 years in the future. Significantly hampering the utilization and economic return generation potential of infrastructure projects. In addition, regional geography contributes to risk heterogeneity, with 100-year floods occurring every 15 years in South Asia and every 24 years in Sub-Saharan Africa. Such climate risk implications, potentially overlooked by development financiers, represent significant risks to the sustenance of the BRI, estimated to be worth $1 trillion. [ABSTRACT FROM AUTHOR]

This study was designed to assess the role of nano-zinc oxide in mitigating the deleterious effects of heat stress in African catfish (Clarias gariepinus) by evaluating parameters such as aggressive behavior (biting frequency and chasing duration), hematological indicators, and stress-related biochemical markers. A total of 96 catfish were divided into four distinct groups (24 fish/group): The first group (CON) served as the control group, receiving a diet free of nano-zinc oxide. The second group (HS) was exposed to heat stress at 35 °C ± 1 °C. The third group (ZN) was fed a diet containing nano-zinc oxide at 30 mg/kg of the diet, and the fourth group (ZHN) was exposed to heat stress (35 °C ± 1 °C) and fed a diet containing nano-zinc oxide at 30 mg/kg of the diet. The results clarified that the aggressive behavior and cortisol levels were significantly higher (P < 0.05) in the HS group compared to the CON and ZHN groups. Additionally, the level of acetylcholinesterase (AChE) was significantly lower (P < 0.05) in the HS group compared to the CON and ZHN groups. Meanwhile, a significant (P < 0.05) decrease in red blood cells, hemoglobin, packed cell volume, white blood cells, alkaline phosphatase, and lymphocytes, was observed in fish belonging to the HS group, while the levels of alanine aminotransferase, aspartate aminotransferase, neutrophils, and monocytes showed a significant increase (P < 0.05). Supplementation with nano-zinc oxide significantly recovered most hematological and biochemical parameters. In conclusion, nano-zinc oxide contributed significantly to the regulation of the negative impacts of heat stress on fish by reducing aggressive behavior and cortisol levels. Additionally, it improved the levels of AChE and certain hematological and biochemical parameters. [ABSTRACT FROM AUTHOR]

Background: Examining the mechanistic cellular responses to heat stress could aid in addressing the increasing prevalence of decreased fertility due to elevated ambient temperatures. Here, we aimed to study the differential responses of oocytes and granulosa cells to thermal fluctuations due to seasonal differences. Dry beef cows (n = 10) were housed together, synchronized and subjected to a stimulation protocol to induce follicular growth before ovum pick-up (OPU). Two OPU's were conducted (summer and winter) to collect cumulus-oocyte-complexes (COCs) and granulosa cells. In addition, rectal temperatures and circulating blood samples were collected during OPU. Oocytes were separated from the adherent cumulus cells, and granulosa cells were isolated from the collected OPU fluid. RNA was extracted from pools of oocytes and granulosa cells, followed by library preparation and RNA-sequencing. Blood samples were further processed for the isolation of plasma and leukocytes. The transcript abundance of HSP70 and HSP90 in leukocytes was evaluated using RT-qPCR, and plasma cortisol levels were evaluated by immunoassay. Environmental data were collected daily for three weeks before each OPU session. Data were analyzed using MIXED, Glimmix or GENMOD procedures of SAS, according to each variable distribution. Results: Air temperatures (27.5 °C vs. 11.5 °C), average max air temperatures (33.7 °C vs. 16.9 °C), and temperature-humidity indexes, THI (79.16 vs. 53.39) were shown to contrast significantly comparing both the summer and winter seasons, respectively. Rectal temperatures (Summer: 39.2 ± 0.2 °C; Winter: 38.8 ± 0.2 °C) and leukocyte HSP70 transcript abundance (Summer: 4.18 ± 0.47 arbitrary units; Winter: 2.69 ± 0.66 arbitrary units) were shown to increase in the summer compared to the winter. No visual differences persisted in HSP90 transcript abundance in leukocytes and plasma cortisol concentrations during seasonal changes. Additionally, during the summer, 446 and 940 transcripts were up and downregulated in oocytes, while 1083 and 1126 transcripts were up and downregulated in the corresponding granulosa cells, respectively (Fold Change ≤ -2 or ≥ 2 and FDR ≤ 0.05). Downregulated transcripts in the oocytes were found to be involved in ECM-receptor interaction and focal adhesion pathways, while the upregulated transcripts were involved in protein digestion and absorption, ABC transporters, and oocyte meiosis pathways. Downregulated transcripts in the granulosa cells were shown to be involved in cell adhesion molecules, chemokine signaling, and cytokine-cytokine receptor interaction pathways, while those upregulated transcripts were involved in protein processing and metabolic pathways. Conclusion: In conclusion, seasonal changes dramatically alter the gene expression profiles of oocytes and granulosa cells in beef cows, which may in part explain the seasonal discrepancies in pregnancy success rates during diverging climatic weather conditions. [ABSTRACT FROM AUTHOR]

The increasing incidence of heat stress due to global climate change poses a significant challenge to avocado (Persea americana) cultivation, particularly in regions with intense solar radiation. This review evaluates sun protection strategies, focusing on the efficacy of different sunscreen products such as kaolin, titanium dioxide, and calcium oxide in mitigating thermal stress in avocado trees. The application of these materials was shown to reduce leaf and fruit surface temperatures, improve photosynthetic efficiency, and enhance fruit quality by preventing sunburn and dehydration. Despite these benefits, challenges remain, including the optimal timing and dosage of application, and the potential residue impacts on fruit marketability. The review emphasizes the need for ongoing research to develop more effective formulations and to integrate these sun protection strategies with other agronomic practices. The role of extension services in educating producers about the proper use of these technologies is also highlighted as crucial for the successful adoption of sun protection measures in avocado farming. [ABSTRACT FROM AUTHOR]

Introduction: Melatonin, a tryptophan-derived indoleamine metabolite with important roles in plant growth and defense, has recently been regarded as a new plant hormone. Maize is one of the most important cereal crops in the world. Although the melatonin receptor gene, ZmPMTR1, has already been identified, the genetic basis of melatonin biosynthesis in maize has still not been elucidated. Serotonin N-acetyltransferase (SNAT) is the enzyme that converts serotonin to N-acetylserotonin (NAS) or 5-methoxytryptamine (5MT) to melatonin in Arabidopsis and rice, but no SNAT encoding gene has been identified yet in maize. Methods: The bioinformatics analysis was used to identify maize SNAT genes and the enzyme activity of the recombinant proteins was determined through in vitro assay. The expression levels of ZmSNAT1 and ZmSNAT3 under drought and heat stresses were revealed by public RNA-seq datasets and qRT-PCR analysis. Results: We first identified three maize SNAT genes, ZmSNAT1, ZmSNAT2, and ZmSNAT3, through bioinformatics analysis, and demonstrated that ZmSNAT2 was present in only eight of the 26 cultivars analyzed. We then determined the enzyme activity of ZmSNAT1 and ZmSNAT3 using their recombinant proteins through in vitro assay. The results showed that both ZmSNAT1 and ZmSNAT3 could convert serotonin to NAS and 5-MT to melatonin. Recombinant ZmSNAT1 catalyzed serotonin into NAS with a higher catalytic activity (Km, 8.6 mM; Vmax, 4050 pmol/min/mg protein) than ZmSNAT3 (Km, 11.51 mM; Vmax, 142 pmol/min/mg protein). We further demonstrated that the 228th amino acid Tyr (Y228) was essential for the enzymatic activity of ZmSNAT1. Finally, we revealed that the expression of ZmSNAT1 and ZmSNAT3 varied among different maize cultivars and different tissues of a plant, and was responsive to drought and heat stresses. Discussion: In summary, the present study identified and characterized the first two functional SNAT genes in maize, laying the foundation for further research on melatonin biosynthesis and its regulatory role in plant growth and response to abiotic stresses. [ABSTRACT FROM AUTHOR]

SUMMARY Basic helix–loop–helix (bHLH) proteins comprise one of the largest families of transcription factors in plants, which play roles in plant development, secondary metabolism, and the response to biotic/abiotic stresses. However, the roles of bHLH proteins in thermotolerance are largely unknown. Herein, we identified a heat‐inducible member of the bHLH family in lily (Lilium longiflorum), named LlbHLH87, which plays a role in thermotolerance. LlbHLH87 was rapidly induced by transient heat stress, and its encoded protein was localized to the nucleus, exhibiting transactivation activity in both yeast and plant cells. Overexpression of LlbHLH87 in Arabidopsis enhanced basal thermotolerance, while silencing of LlbHLH87 in lily reduced basal thermotolerance. Further analysis showed that LlbHLH87 bound to the promoters of HEAT STRESS TRANSCRIPTION FACTOR A2 (LlHSFA2) and ETHYLENE‐INSENSITIVE 3 (LlEIN3) to directly activate their expression. In addition, LlbHLH87 interacted with itself and with SPATULA (LlSPT) protein. LlSPT was activated by extended heat stress and its protein competed for the homologous interaction of LlbHLH87, which reduced the transactivation ability of LlbHLH87 for target genes. Compared with that observed under LlbHLH87 overexpression alone, co‐overexpression of LlbHLH87 and LlSPT reduced the basal thermotolerance of lily to sudden heat shock, but improved its thermosensitivity to prolonged heat stress treatment. Overall, our data demonstrated that LlbHLH87 regulates thermotolerance via activation of LlEIN3 and LlHSFA2, along with an antagonistic interaction with LlSPT. [ABSTRACT FROM AUTHOR]

Key points Prolonged passive heat treatment (PHT) has been suggested to trigger skeletal muscle adaptations that may improve muscle maintenance in older individuals. To assess the effects of PHT on skeletal muscle tissue capillarization, perfusion capacity, protein synthesis rates, hypertrophy and leg strength, 14 older adults (9 males, 5 females; 73 ± 6 years) underwent 8 weeks of PHT (infrared sauna: 3× per week, 45 min at ∼60°C). Before and after PHT we collected muscle biopsies to assess skeletal muscle capillarization and fibre cross‐sectional area (CSA). Basal and postprandial muscle tissue perfusion kinetics and protein synthesis rates were assessed using contrast‐enhanced ultrasound and primed continuous l‐[ring‐13C6]phenylalanine infusions, respectively. One‐repetition maximum (1RM) leg strength and vastus lateralis muscle CSA were assessed. Type I and type II muscle fibre capillarization strongly increased following PHT (capillary‐to‐fibre perimeter exchange index: +31 ± 18 and +33 ± 30%, respectively; P < 0.001). No changes were observed in basal (0.24 ± 0.27 vs. 0.18 ± 0.11 AU; P = 0.266) or postprandial (0.20 ± 0.12 vs. 0.18 ± 0.14 AU; P = 0.717) microvascular blood flow following PHT. Basal (0.048 ± 0.014 vs. 0.051 ± 0.019%/h; P = 0.630) and postprandial (0.041 ± 0.012 vs. 0.051 ± 0.024%/h; P = 0.199) muscle protein synthesis rates did not change in response to prolonged PHT. Furthermore, no changes in vastus lateralis muscle CSA (15.3 ± 4.6 vs. 15.2 ± 4.6 cm2; P = 0.768) or 1RM leg strength (46 ± 12 vs. 47 ± 12 kg; P = 0.087) were observed over time. In conclusion, prolonged PHT increases muscle tissue capillarization but this does not improve muscle microvascular blood flow or increase muscle protein synthesis rates in healthy, older adults. Prolonged PHT does not induce skeletal muscle hypertrophy or increase leg strength in healthy, older adults. Repeated exposure to heat has been suggested to trigger skeletal muscle adaptive responses. We investigated the effect of 8 weeks of whole‐body passive heat treatment (PHT; infrared sauna: 3× per week for 45 min at ∼60°C) on skeletal muscle tissue capillarization, perfusion capacity, basal, and postprandial muscle protein synthesis rates, muscle (fibre) hypertrophy, and leg strength in healthy, older adults. Prolonged PHT increases muscle tissue capillarization, but this does not improve muscle microvascular blood flow or increase muscle protein synthesis rates. Despite increases in muscle tissue capillarization, prolonged PHT does not suffice to induce skeletal muscle hypertrophy or increase leg strength in healthy, older adults. [ABSTRACT FROM AUTHOR]

Indoxyl sulfate (IS), a uremic toxin, is a harmful factor that damages kidneys. Chronic heat stress in laying hens causes renal injury; however, whether IS accumulation is involved in this injury remains unknown. We selected 20 Boris brown laying hens (27 weeks old) and randomly assigned them to two groups (n = 10), one group was exposed to chronic heat stress (32 °C for 4 weeks), whereas the other was maintained at 24 °C. Chronic heat exposure significantly increased plasma and renal IS concentrations (P < 0.05). Exposure to heat also increased renal expression of the aryl hydrocarbon receptor (AhR) and its target genes (CYP1A4 and CYP1B1). Furthermore, chronic heat exposure tended to increase the 2-thiobarbituric acid reactive substances content (P = 0.08) and significantly decreased the antioxidant capacity in the kidney, while increasing the transcription levels of nuclear factor κB and fibrosis-related genes (COLA1A1, αSMA, TGF-β, Smad3, and VCAM-1) and the area of renal fibrosis. Our results indicate that chronic heat exposure induces systemic and renal IS accumulation in laying hens. This accumulated IS may activate the AhR pathway and chronically disrupt the oxidative stress status and antioxidant activity, thus promoting renal fibrosis and dysfunction in laying hens. [ABSTRACT FROM AUTHOR]

Background: The effect of vitamin E and Selenium supplementation in diet of broiler chicken on growth performance and Heat shock protein70 (HSP70) level under summer heat stress was studied. Methods: The current study was conducted on 240 day-old commercial broiler chicks, which were divided randomly into four treatment groups of 60 numbers, with three replicates of 20 in each group. The control (T0) group was allotted with basal diet, group T1 (basal diet + Vitamin E @ 100 mg/kg and Selenium @ 0.2 mg/kg), T2 (basal diet + Vitamin E @ 125 mg/kg and Selenium @ 0.25 mg/kg) and T3 (basal diet + Vitamin E @ 150 mg/kg and Selenium @ 0.3 mg/kg). Result: In the present study, it has been found that, vitamin E and selenium supplementation in the diet of heat stressed broilers influenced the body weight (P=0.002), Body weight gain (P=0.001), Feed Intake (P=0.311) and BPEI (P=0.013) but not the Feed conversion ratio. Dietary vitamin E and Selenium supplementation increased the dressing percentage (P<0.001), Breast meat yield percentage (P=0.004), Thigh yield percentage (P=0.018), Drum stick yield percentage (P=0.013) and decreased abdominal fat percentage (P=0.004) under heat stress. The Heat shock protein level was improved (P<0.001) by dietary supplementation of vitamin E and Selenium under heat stress. The study indicated that growth performance, carcass characteristics and HSP70 level could be improved by dietary vitamin E and selenium supplementation under heat stress. [ABSTRACT FROM AUTHOR]

The efficacy of probiotics in providing health benefits may be related to their ability to survive at a sufficient concentration of 106 CFU/g during storage in food and colonization in the gastrointestinal tract. Microencapsulation is a viable method to improve the survivability of probiotics under harsh environmental conditions. In this research, microencapsulated Lactobacillus rhamnosus (MLR) was produced by a two‐layer extrusion technique with sodium alginate and wild sage (Salvia macrosiphon) mucilage (SMM) in varying concentrations ranging from 0.2% to 0.8% as the first and second wall materials, respectively. The microencapsulation efficiency and second layer diameter of beads increased significantly with the increase in SMM concentrations. Microencapsulated Lactobacillus rhamnosus (LR) maintained its minimal concentration (6 log CFU/g) during 9 min at 72°C. The MLR‐date yogurt (DY) sample had the lowest pH, highest acidity, and highest survival rate among the others at the end of storage. In simulated gastrointestinal conditions (SGC), the survival rates of free LR (FLR) and MLR were 45% and 47% on the 14th day of storage, respectively. In sensory properties, MLR had the highest score in odor and texture parameters but not in others. The MLR viscosity (666.3 mPa·s−1) and SEM images show a relatively denser structure for MLR. In conclusion, this study emphasized the potential of using double‐layered beads to protect probiotics, providing valuable inspiration for developing new functional foods with higher survival ability in harsh conditions. [ABSTRACT FROM AUTHOR]

Faba bean is grown globally for human consumption and animal feed and is a significant rotation crop in cereal-dominant areas in many countries, including Australia. It is sensitive to several abiotic stresses, such as drought, frost, and high temperatures, especially at the reproductive stage. However, little is known of the upper and lower temperature limits for successful podding. Experiments were conducted over 2 years at Breeza and Narrabri in northwestern New South Wales to assess the impact of temperature on flowering and podset of three genotypes—Doza, Cairo, and IX1148f—under field conditions. Flowering nodes were tagged from designated plants in the field and scored for podding; field temperatures were recorded. Optimum maximum temperature for podset ranged from 23.7–26.1 °C, and the equivalent minimum temperature was 3.2–3.8 °C. Optimum average daily temperature for podset ranged from 12.7–13.9 °C. The strongest correlations between temperature and podding were observed at minimum temperatures, indicating that low temperatures are more important than high temperatures in determining yield in faba bean. [ABSTRACT FROM AUTHOR]

With the increasing human population and urbanization, the demand for animal origin products is going to grow, especially in the developing nations till the 2050s and the production needs to be escalated and optimized with the changing climate. Heat stress is known to reduce the animal performance, production, shelf life and meat quality in all animals. The beef cattle are globally reared, following different managemental practices, so the usage of natural resources like land and water, manpower, fodders, production systems and the environmental impact also varies profoundly. Recent changes in the climate, global warming and depletion of resources have severely affected the production and heat stress is now a common constraint all over the world. Due to evolutionary diversification the tropical and temperate breeds are comparatively more thermotolerant, but the beef cattle in the colder regions are vulnerable to high environmental temperatures. Also, the production of beef increases the carbon footprint and is much less eco-friendly than growing plant-based protein. So, we comprehended the environmental temperature variation over the continents and impact of heat stress on beef cattle. Also, other factors like cattle population, land and pasture usage, livestock units in trade, methane emissions and gross beef production value were examined to evaluate the collective impact of all these on the beef sector. Our findings and predictions reveal that, in the advent of climate change, depleting natural resources and rise in the greenhouse gases, beef production will be a constant challenge, which can be only achieved by maintaining a healthy cattle population and optimum usage of natural resources. Only then can the beef sector be efficient, sustainable, and a profitable enterprise in future. [ABSTRACT FROM AUTHOR]

Sheep are an important source of protein for humans, and recent decades have seen a significant increase in the production of sheep-based products, thus indicating an increase in demand for this commodity. At a time when this sector is growing, sheep are exposed to various challenges. These include climate change, which can cause heat stress in sheep, including rams, which later negatively affects their growth and reproductive performance. Exposure to heat stress results in physiological and reproductive behaviour responses in rams, which could also be used to visually identify the effect of heat stress as it will affect the productivity of livestock. In addition, the year-round hot and humid climate of the tropics is expected to contribute to a higher probability of heat stress occurrences in rams reared in developing countries around the equator. Nevertheless, the adaptability of rams to heat stress varies according to their origin, whereby native breeds tend to adapt better. Despite that, native breeds still can be affected by adverse environmental conditions and rely on thermoregulation mechanisms to mitigate heat stress. This results in numerous negative physiological changes, such as sweating and increased heart rate. This review highlights the effects of heat stress on the physiology, reproductive behaviour and reproductive performance of male sheep. The review also discusses the impact of management systems on heat stress in rams, which affects sheep productivity. [ABSTRACT FROM AUTHOR]

The primary objective of this study was to evaluate the effects of liquid (Fructose-added lactic acid bacteria, F-LAB) and commercial (Commercial LAB, C-LAB) probiotics sourced from Rye-Grass Lactic Acid Bacteria (LAB) on broiler chickens experiencing heat stress (HS). The research involved 240 broiler chicks, divided into six groups: control, F-LAB, C-LAB (raised at 24 °C), HS, F-LAB/HS, and C-LAB/HS (exposed to 5–7 h of 34–36 °C daily). The study followed a randomized complete block design, with each group consisting of 40 chicks. F-LAB and HS/F-LAB groups received a natural probiotic added to their drinking water at a rate of 0.5 ml/L, while C-LAB and HS/C-LAB groups were supplemented with a commercial probiotic at the same dosage. Control and HS groups received no probiotic supplementation. The duration of the study was 42 days, with data collected on growth performance, feed intake, feed conversion ratio, and health parameters. Statistical analyses were performed using ANOVA, and significant differences between groups were determined using post hoc tests. The results revealed that without probiotic supplementation, heat stress led to a decrease in body weight gain, T3 levels, citrulline, and growth hormone levels, along with an increase in the feed conversion ratio, serum corticosterone, HSP70, ALT, AST, and leptin levels (p < 0.05 for all). Heat stress also adversely affected cecal microbiota, reducing lactic acid bacteria count (LABC) while increasing Escherichia coli and coliform bacteria (CBC) counts. However, in the groups receiving probiotic supplementation under heat stress (F-LAB/HS and C-LAB/HS), these effects were alleviated (p < 0.05 for all). Particularly noteworthy was the observation that broiler chickens supplemented with natural lactic acid bacteria (F-LAB) exhibited greater resilience to heat stress compared to those receiving the commercial probiotic, as evidenced by improvements in growth, liver function, hormonal balance, intestinal health, and cecal microbiome ecology (p < 0.05). These findings suggest that the supplementation of naturally sourced probiotics (F-LAB) may positively impact the intestinal health of broiler chickens exposed to heat stress, potentially supporting growth and health parameters. [ABSTRACT FROM AUTHOR]