A retrospective study of thermal events on the mortality rate of hutch-reared dairy calves.

Introduction: Heat stress in hutch-reared dairy calves (Bos taurus) is highly relevant due to its adverse effects on animal welfare, health, growth, and economic outcomes. This study aimed to provide arguments for protecting calves against heat stress. It was hypothesized that the thermal stress caused by high ambient temperature in summer months negatively affects the survival rate in preweaning calves. Methods: In a retrospective study, we investigated how calf mortality varied by calendar month and between thermoneutral and heat stress periods on a large-scale Hungarian dairy farm (data of 46,899 calves between 1991 and 2015). Results: The daily mortality rate was higher in the summer (8.7-11.9 deaths per 10,000 calf days) and winter months (10.7-12.5 deaths per 10,000 calf-days) than in the spring (6.8-9.2 deaths per 10,000 calf-days) and autumn months (7.1-9.5 deaths per 10,000 calf-days). The distribution of calf deaths per calendar month differed between the 0-14-day and 15-60-day age groups. The mortality risk ratio was highest in July (6.92). The mortality risk in the 0-14-day age group was twice as high in periods with a daily mean temperature above 22°C than in periods with a daily mean of 5-18°C. Conclusions: Heat stress abatement is advised in outdoor calf rearing when the mean daily temperature reaches 22°C, which, due to global warming, will be a common characteristic of summer weather in a continental region.

Experimental research in environmentally induced hyperthermic older persons: A systematic quantitative literature review mapping the available evidence.

The heat-related health burden is expected to persist and worsen in the coming years due to an aging global population and climate change. Defining the breadth and depth of our understanding of age-related changes in thermoregulation can identify underlying causes and strategies to protect vulnerable individuals from heat. We conducted the first systematic quantitative literature review to provide context to the historical experimental research of healthy older adults - compared to younger adults or unhealthy age matched cases - during exogenous heat strain, focusing on factors that influence thermoregulatory function (e.g. co-morbidities). We identified 4,455 articles, with 147 meeting eligibility criteria. Most studies were conducted in the US (39%), Canada (29%), or Japan (12%), with 71% of the 3,411 participants being male. About 71% of the studies compared younger and older adults, while 34% compared two groups of older adults with and without factors influencing thermoregulation. Key factors included age combined with another factor (23%), underlying biological mechanisms (18%), age independently (15%), influencing health conditions (15%), adaptation potential (12%), environmental conditions (9%), and therapeutic/pharmacological interventions (7%). Our results suggest that controlled experimental research should focus on the age-related changes in thermoregulation in the very old, females, those with overlooked chronic heat-sensitive health conditions (e.g. pulmonary, renal, mental disorders), the impact of multimorbidity, prolonged and cumulative effects of extreme heat, evidence-based policy of control measures (e.g. personal cooling strategies), pharmaceutical interactions, and interventions stimulating protective physiological adaptation. These controlled studies will inform the directions and use of limited resources in ecologically valid fieldwork studies.

Projected ocean temperatures impair key proteins used in vision of octopus hatchlings.

Global warming is one of the most significant and widespread effects of climate change. While early life stages are particularly vulnerable to increasing temperatures, little is known about the molecular processes that underpin their capacity to adapt to temperature change during early development. Using a quantitative proteomics approach, we investigated the effects of thermal stress on octopus embryos. We exposed Octopus berrima embryos to different temperature treatments (control 19°C, current summer temperature 22°C, or future projected summer temperature 25°C) until hatching. By comparing their protein expression levels, we found that future projected temperatures significantly reduced levels of key eye proteins such as S-crystallin and retinol dehydrogenase 12, suggesting the embryonic octopuses had impaired vision at elevated temperature. We also found that this was coupled with a cellular stress response that included a significant elevation of proteins involved in molecular chaperoning and redox regulation. Energy resources were also redirected away from non-essential processes such as growth and digestion. These findings, taken together with the high embryonic mortality observed under the highest temperature, identify critical physiological functions of embryonic octopuses that may be impaired under future warming conditions. Our findings demonstrate the severity of the thermal impacts on the early life stages of octopuses as demonstrated by quantitative proteome changes that affect vision, protein chaperoning, redox regulation and energy metabolism as critical physiological functions that underlie the responses to thermal stress.

Collective effects of rising average temperatures and heat events on oviparous embryos.

Survival of the immobile embryo in response to rising temperature is important to determine a species' vulnerability to climate change. However, the collective effects of 2 key thermal characteristics associated with climate change (i.e., rising average temperature and acute heat events) on embryonic survival remain largely unexplored. We used empirical measurements and niche modeling to investigate how chronic and acute heat stress independently and collectively influence the embryonic survival of lizards across latitudes. We collected and bred lizards from 5 latitudes and incubated their eggs across a range of temperatures to quantify population-specific responses to chronic and acute heat stress. Using an embryonic development model parameterized with measured embryonic heat tolerances, we further identified a collective impact of embryonic chronic and acute heat tolerances on embryonic survival. We also incorporated embryonic chronic and acute heat tolerance in hybrid species distribution models to determine species' range shifts under climate change. Embryos' tolerance of chronic heat (T-chronic) remained consistent across latitudes, whereas their tolerance of acute heat (T-acute) was higher at high latitudes than at low latitudes. Tolerance of acute heat exerted a more pronounced influence than tolerance of chronic heat. In species distribution models, climate change led to the most significant habitat loss for each population and species in its low-latitude distribution. Consequently, habitat for populations across all latitudes will shift toward high latitudes. Our study also highlights the importance of considering embryonic survival under chronic and acute heat stresses to predict species' vulnerability to climate change.

Efectos colectivos del aumento de las temperaturas promedio y los eventos de calor en embriones ovíparos Resumen La supervivencia de los embriones inmóviles en respuesta al incremento de temperatura es importante para determinar la vulnerabilidad de las especies al cambio climático. Sin embargo, los efectos colectivos de dos características térmicas claves asociadas con el cambio climático (i. e., aumento de temperatura promedio y eventos de calor agudo) sobre la supervivencia embrionaria permanecen en gran parte inexplorados. Utilizamos mediciones empíricas y modelos de nicho para investigar cómo el estrés térmico crónico y agudo influye de forma independiente y colectiva en la supervivencia embrionaria de los lagartos en todas las latitudes. Recolectamos y criamos lagartos de cinco latitudes e incubamos sus huevos en un rango de temperaturas para cuantificar las respuestas específicas de la población al estrés por calor crónico y agudo. Posteriormente, mediante un modelo de desarrollo embrionario parametrizado con mediciones de tolerancia embrionaria al calor, identificamos un impacto colectivo de las tolerancias embrionarias al calor agudo y crónico en la supervivencia embrionaria. También incorporamos la tolerancia embrionaria crónica y aguda al calor en modelos de distribución de especies híbridas para determinar los cambios de distribución de las especies bajo el cambio climático. La tolerancia embrionaria al calor crónico (T­crónico) permaneció constante, mientras que la tolerancia al calor agudo (T­agudo) fue mayor en latitudes altas que en latitudes bajas. La tolerancia al calor agudo ejerció una influencia más pronunciada que la tolerancia al calor crónico. En los modelos de distribución de especies, el cambio climático provocó la pérdida de hábitat más significativa para cada población y especie en su distribución de latitudes bajas. En consecuencia, el hábitat para poblaciones en todas las latitudes se desplazará a latitudes altas. Nuestro estudio también resalta la importancia de considerar la supervivencia embrionaria bajo estrés térmico crónico y agudo para predecir la vulnerabilidad de las especies al cambio climático.

Comparative expression and localization of visfatin, chemerin, and chemerin receptor proteins in a heat-stressed mouse testis.

The adipokines, visfatin, chemerin, and its receptor are expressed in the testis. It has also been shown that heat-stress alters the secretion and expression of other adipokines. Testicular heat-stress is now well known to cause the impairment in the testis. It has also been documented that heat-stress changes the expression of genes and proteins in the testis. To the best of our knowledge, the expression and localization of visfatin chemerin and its receptor have not been investigated in the heat-stressed testis. Therefore, the present study has investigated the expression and localization of these proteins in the heat-stressed testis. The expression of visfatin and chemerin and receptor exhibits a differential repossess against the heat stress. Visfatin expression was up-regulated while chemerin and chemerin receptor was down-regulated in the heat-stressed testis as shown by western blot analysis. The immunolocalization of visfatin and chemerin showed increased abundance in the seminiferous tubules of heat-stressed mice testis. Furthermore, abundance of visfatin, chemerin, and its receptor showed a decrease in abundance in the Leydig cells of heat-stressed testis. The decreased abundance of these proteins in the Leydig cells coincides with decreased 3ß-HSD immunostaining along with decreased testosterone levels. These results suggest that heat-stress might decrease testosterone secretion by modulating visfatin and chemerin in the Leydig cells. The increased abundance of visfatin and chemerin in the primary spermatocytes, round spermatid, and multinucleated germ cells also coincides with increased immunostaining of active caspase-3. Moreover, expression of Bcl-2 was down-regulated, and expression of active caspase-3 and HSP70 were up-regulated along with increased oxidative stress in the heat-stressed testis, suggesting stimulated apoptosis. In conclusion, our results showed that visfatin, chemerin, and its receptor are differentially expressed in the testis under heat-stress and within the testis also it might differentially regulate testosterone biosynthesis in the Leydig cells and apoptosis in the seminiferous tubules.

Selection of reference genes for normalizing gene expression data across seasons in spermatozoa of water buffalo (Bubalus bubalis).

Selection of the most stably expressed reference genes is key to monitoring accurate target gene expression across any tissue or cell type. The mRNA in spermatozoa stores valuable information related to changes in spermatogenesis due to variations in environmental conditions, especially during heat stress, which affects various sperm functions. Semen quality in buffalo bulls is significantly influenced by the seasons. In the study, a panel of nine genes was evaluated to identify the most stably expressed internal control gene (ICG) for the normalization of real-time gene expression data generated across various seasons for Murrah buffalo bulls' spermatozoa. Sperm cells were purified from the semen samples collected during different seasons, with temperature-humidity index (THI) ranging from 80.80 ± 1.47 (hot summer) to 55.88 ± 1.98 (winter), using the BoviPure™ gradient purification method. The RNA isolated from the purified spermatozoa fraction was quality checked prior to reverse transcription and subjected to qPCR (quantitative real-time PCR) based expression analysis. An automated 'endoGene' pipeline was employed to apply the geNorm, NormFinder, and BestKeeper algorithms for data analysis. The result indicated that GAPDH and PP1A were the most stably expressed among the gene panel, whereas ATPSF1 and ACTB were the two least stable expressed reference genes. Further, the most suitable ICGs identified were validated by normalization of real time expression data of heat stress and sperm quality genes, HSFY2 and AKAP4, respectively. The genes identified would help in generating the most reliable results for the expression profiling of the genes dictating sperm quality and heat stress cope-up mechanism in buffalo spermatozoa, collected during different seasons.

Effect of chronic cyclic heat stress and supplemented inorganic and organic zinc source levels on grow-finish pig growth performance and estimated body composition.

Zinc (Zn) supplementation has proved to mitigate the effects of heat stress with varying effects evident with Zn source during acute heat events. However, the effects of Zn supplementation during long-term summer weather patterns have yet to be explored. Therefore, the objective of this study was to identify the effects of supplementation source and level of Zn to mitigate the negative effects of long-term, cyclic heat stress in finishing swine. Six hundred cross-bred pigs were housed under thermoneutral (TN) or cyclic heat (HS) conditions simulating summer heat with acute 3-d heat waves for a 70-d study. Thermoneutral conditions were 16.7 to 18.9 °C throughout the study. HS pigs were housed at the same temperature as TN from days 0 to 18, then 28 °C/24 °C for 12 h/12 h on days 18 to 21, followed by 30 °C/26.7 °C for 12 h/12 h on days 24 to 70, except during acute heat (32 to 33 °C/29 to 30 °C, 12 h/12 h) on days 21 to 24, 42 to 45, and 63 to 66. Treatments were arranged in a 2 × 6 factorial with main effects of environment (HS vs. TN) and dietary available Zn supplementation: (1) 50 mg/kg zinc oxide (ZnO), (2) 130 mg/kg ZnO, (3) 50 mg/kg of organic Zn (Availa Zn), (4) 50 mg/kg ZnO + 40 mg/kg organic Zn, (5) 50 mg/kg ZnO + 60 mg/kg organic Zn, and (6) 50 mg/kg ZnO + 80 mg/kg organic Zn. Pigs (5 pigs/pen) were blocked by initial body weight (72.2 kg) and randomly allotted to 1 of 12 temperature and diet treatment combinations across 10 replicates. Body weight and feed intake were determined at the beginning and end of each acute heat event. All pigs were ultrasonically scanned at the 10th rib (TR) to predict loin muscle area (LMA), backfat (BF), and percent lean. Data were analyzed by the MIXED procedure in SAS with pen as the experimental unit. At day 63, HS pigs were lighter (P < 0.05), had lower overall average daily gain (ADG; P < 0.05) and average daily feed intake (P < 0.05). A diet-by-environment interaction was observed for overall ADG (P < 0.05) with diet 5 HS pigs having a 3.9% reduction in ADG whereas diet 6 had 14.4% reduction in ADG, while under TN temperatures diet 6 had the greatest overall ADG of all treatments. Other diets were intermediate in their ADG under both HS and TN conditions. Pigs under HS had less BF at the TR (P < 0.05) and a smaller LMA (P < 0.05), and a greater calculated percent lean (P < 0.05). Our results indicate that a blend of supplemental Zn sources at 50/60 mg/kg may mitigate the reduction in growth performance due to HS. While not directly contrasted, the NRC requirement of 50 mg/kg Zn may be too low to optimize finishing pig growth performance under both TN and HS conditions.

Integrated analysis of intestinal microbiota and transcriptome reveals that a coordinated interaction of the endocrine, immune system and gut microbiota response to heat stress in Litopenaeus vannamei.

Due to the ongoing global warming, the risk of heatwaves in the oceans is continuously increasing while our understanding of the physiological response of Litopenaeus vannamei under extreme temperature conditions remains limited. Therefore, this study aimed to evaluate the physiological responses of L. vannamei under heat stress. Our results indicated that as temperature rose, the structure of intestinal and hepatopancreatic tissues was damaged sequentially. Activity of immune-related enzymes (acid phosphatase/alkaline phosphatase) initially increased before decreased, while antioxidant enzymes (superoxide dismutase and glutathione-S transferase) activity and malondialdehyde content increased with rising temperature. In addition, the total antioxidant capacity decreased with rising temperature. With the rising temperature, there was a significant increase in the expression of caspase-3, heat shock protein 70, lipopolysaccharide-induced tumor necrosis factor-α, transcriptional enhanced associate domain and yorkie in intestinal and hepatopancreatic tissues. Following heat stress, the number of potentially beneficial bacteria (Rhodobacteraceae and Gemmonbacter) increased which maintain balance and promote vitamin synthesis. Intestinal transcriptome analysis revealed 852 differentially expressed genes in the heat stress group compared with the control group. KEGG functional annotation results showed that the endocrine system was the most abundant in Organismal systems followed by the immune system. These results indicated that heat stress leads to tissue damage in shrimp, however the shrimp may respond to stress through a coordinated interaction strategy of the endocrine system, immune system and gut microbiota. This study revealed the response mechanism of L. vannamei to acute heat stress and potentially provided a theoretical foundation for future research on shrimp environmental adaptations.

Protective effect of chlorogenic acid on liver injury in heat-stressed meat rabbits.

This study investigated the protective effects of chlorogenic acid (CGA) on production performance and liver function of rabbits under heat stress (HS) condition. A total of 120 healthy New Zealand weaned rabbits with similar initial body weight, were randomly divided into 3 treatments with 20 replicates per treatment and 2 weaned rabbits per replicate: control (CON) group (rabbits were housed at 25 ± 1°C and fed a basal diet), HS group (rabbits were housed at 35 ± 1°C and fed a basal diet), and HS + CGA group (rabbits were housed at 35 ± 1°C and fed a basal diet supplemented with 800 mg/kg CGA). The trial lasted for 28 days. The results showed that HS challenge decreased (p < 0.05) growth performance, induced oxidative stress and hepatic apoptosis, and caused liver damage in rabbits. However, dietary CGA supplementation increased (p < 0.05) body weight gain and feed efficiency, and enhanced (p < 0.05) antioxidative capacity in serum and liver in HS-challenged rabbits; attenuated HS-induced increases in urea nitrogen (p = 0.03), alanine aminotransferase (p = 0.03), aspartate aminotransferase (p = 0.01), caspase-8 (p = 0.02), and caspase-3 (p = 0.04) as well as decrease albumin (p = 0.04). Moreover, supplementation with CGA upregulated Nrf2/HO-1 pathway-related genes expressions, including Nrf2 (p = 0.009), HO-1 (p = 0.03) and SOD1 (p = 0.04) in HS-challenged rabbits. Our findings demonstrated that dietary CGA supplementation could alleviate HS-induced decline in growth performance, and protect against HS-induced liver damage partially through enhancing antioxidant capacity via acting Nrf2/HO-1 pathway and inhibiting hepatic apoptosis in rabbits.

Heat-related mortality and ambulance transport after a power outage in the Tokyo metropolitan area.

Background: Air conditioners can prevent heat-related illness and mortality, but the increased use of air conditioners may enhance susceptibility to heat-related illnesses during large-scale power failures. Here, we examined the risks of heat-related illness ambulance transport (HIAT) and mortality associated with typhoon-related electricity reduction (ER) in the summer months in the Tokyo metropolitan area. Methods: We conducted event study analyses to compare temperature-HIAT and mortality associations before and after the power outage (July to September 2019). To better understand the role of temperature during the power outage, we then examined whether the temperature-HIAT and mortality associations were modified by different power outage levels (0%, 10%, and 20% ER). We computed the ratios of relative risks to compare the risks associated with various ER values to the risks associated without ER. Results: We analyzed the data of 14,912 HIAT cases and 74,064 deaths. Overall, 93,200 power outage cases were observed when the typhoon hit. Event study results showed that the incidence rate ratio was 2.01 (95% confidence interval [CI] = 1.42, 2.84) with effects enduring up to 6 days, and 1.11 (95% CI = 1.02, 1.22) for mortality on the first 3 days after the typhoon hit. Comparing 20% to 0% ER, the ratios of relative risks of heat exposure were 2.32 (95% CI = 1.41, 3.82) for HIAT and 0.95 (95% CI = 0.75, 1.22) for mortality. Conclusions: A 20% ER was associated with a two-fold greater risk of HIAT because of summer heat during the power outage, but there was little evidence for the association with all-cause mortality.

Estimating metabolic rate from International Organization for Standardization heart rate method and two walking equations.

Assigning a value for metabolic rate is central to heat stress assessment. ISO 8996 describes a predictive method for walking based on the American College of Sports Medicine (ACSM) method and another generalized method based on average heart rate. In addition, the US Army uses the load carriage decision aid (LCDA) predictive equation to estimate metabolic rate. The purpose of this study was to assess the accuracy/bias and precision of the ISO heart rate method and the ACSM and LCDA equations. The laboratory database included metabolic rate, heart rate, treadmill speed, and grade during a progressive heat stress protocol. Treadmill speed and grade were set to represent one of three metabolic rates. Accuracy and precision were assessed with Bland-Altman plots. All three methods had good accuracy (low bias). For precision, the ISO heart rate method had a root mean square error (RMSE) of 34 W and 11% when adjusted for repeated measures. The RMSE for two equations was 20 W and 7%. Although the heart method had less accuracy, its application is more generalizable. The heart rate method should be used below the occupational exposure limit to avoid a bias toward higher predicted values due to heat strain.

Programming effects of intrauterine hyperthermia on adrenal gland development.

Maternal heat stress during late pregnancy can lead to intrauterine hyperthermia and affect fetal hypothalamic-pituitary-adrenal axis development and function. Herein, we investigated the effects of chronic environmental heat stress exposure of Holstein cows in the last 2 mo of gestation on their offspring's adrenal gland histomorphology and transcriptome. Cows in their last 54 ± 5 d of gestation were either heat-stressed (i.e., housed under the shade of a free stall barn) or provided heat-stress abatement via active cooling (i.e., via water soakers and fans) during a subtropical summer (Temperature-Humidity Index >68). Respiration rate (RR) and skin temperature (ST) were elevated in heat-stressed dams relative to the cows with access to heat abatement (23 bpm and 2 ◦C higher for RR and ST, respectively). Heifers born to heat-stressed cows experienced heat stress in utero (HS), while heifers born to actively cooled cows did not (CL). The adrenal gland was harvested from 6 heifers per group that were euthanized at birth (d 0; n = 12) or one week after weaning (d 63; n = 12). Circulating cortisol was measured from blood samples collected weekly throughout the pre-weaning period. At d 63, heifers that experienced HS while developing in utero had heavier adrenal glands, with a greater total tissue surface area and thickness of the zona glomerulosa (ZG), fasciculata (ZF), and reticularis (ZR), compared with CL heifers. In addition, the adrenal gland of in utero HS heifers had less cells in the ZG, more and larger cells in the ZF and larger cells in the ZR, relative to CL heifers. Although no changes in circulating cortisol were observed through the pre-weaning period, the transcriptomic profile of the adrenal tissue was altered by fetal exposure to hyperthermia. Both at birth and on d 63, approximately 30 pathways were differentially expressed in the adrenal glands of in utero HS heifers relative to CL. These pathways were associated with immune function, inflammation, prolactin signaling, cell function, and calcium transport. Upstream regulators significantly activated or inhibited in the adrenal glands of heifers exposed to intrauterine hyperthermia were identified. Maternal exposure to heat stress during late gestation caused an enlargement of their offspring's adrenal glands by inducing ZG and ZF cell hypertrophy, and caused gene expression changes. These phenotypic, histological, and molecular changes in the adrenal gland might lead to alterations in stress, immune, and metabolic responses later in life.

Prevalence of occupational heat stress across the seasons and its management amongst healthcare professionals in the UK.

Occupational heat stress (OHS) is an issue in healthcare facilities (HCFs) in the United Kingdom (UK). The aims of this study were to evaluate perceived levels of OHS during two seasons and its perceived consequences on healthcare professionals (HCPs) and to assess the efficacy of heat stress management (HSM) policies. An anonymous online survey was distributed to HCPs working in HCFs in the UK. The survey returned 1014 responses (87% women). Descriptive statistics and content analysis of survey data identified that OHS in HCFs is frequently experienced throughout the year and concerned most HCPs. Over 90% perceived OHS impairs their performance and 20% reported heat-related absenteeism. Awareness of HSM policies was poor and 73% deemed them not adequate. To help reduce the financial loss and impact on staff performance, health and well-being and patient safety, it is recommended that revisions and widespread dissemination of HSM policies are made.

The combination of high temperature and Vibrio infection worsens summer mortality in the clam Meretrix petechialis by increasing apoptosis and oxidative stress.

The interaction between environmental factors and Vibrio in bivalves is not well understood, despite the widely held belief that pathogen infection and seawater temperature significantly impact summer mortality. In the present study, we conducted simulated experiments to explore the effects of high temperature and Vibrio infection on the clam Meretrix petechialis. The survival curve analysis revealed that the combined challenge of high temperature and Vibrio infection (31°C-vibrio) led to significantly higher clam mortality compared to the groups exposed solely to Vibrio (27°C-vibrio), high temperature (31°C-control), and the control condition (27°C-control). Furthermore, PCoA analysis of 11 immune genes indicated that Vibrio infection predominated during the incubation period, with a gradual equilibrium between these factors emerging during the course of the infection. Additionally, our investigations into apoptosis and autophagy processes exhibited significant induction of mTOR and Bcl2 of the 31°C-vibrio group in the early challenge stage, followed by inhibition in the later stage. Oxidative stress analysis demonstrated a substantial additive effect on malondialdehyde (MDA) and glutathione (GSH) content in the combined challenge group compared to the control group. Comparative transcriptome analysis revealed a significant increase in differentially expressed genes related to immunity, such as complement C1q-like protein, C-type lectin, big defensin, and lysozyme, in the 31°C-vibrio group, suggesting that the synergistic effect of high temperature and Vibrio infection triggers more robust antibacterial immune responses. These findings provide critical insights for understanding the infection process and uncovering the causes of summer mortality.

Folic Acid and Taurine Alleviate the Impairment of Redox Status, Immunity, Rumen Microbial Composition and Fermentation of Lambs under Heat Stress.

The aim of this study was to investigate if the supplementation of folic acid and taurine can relieve the adverse effects of different levels of heat stress (HS) on growth performance, physiological indices, antioxidative capacity, immunity, rumen fermentation and microbiota. A total of 24 Dorper × Hu crossbred lambs (27.51 ± 0.96 kg) were divided into four groups: control group (C, 25 °C), moderate HS group (MHS, 35 °C), severe HS group (SHS, 40 °C), and the treatment group, under severe HS (RHS, 40 °C, 4 and 40 mg/kg BW/d coated folic acid and taurine, respectively). Results showed that, compared with Group C, HS significantly decreased the ADG of lambs (p < 0.05), and the ADG in the RHS group was markedly higher than in the MHS and SHS group (p < 0.05). HS had significant detrimental effects on physiological indices, antioxidative indices and immune status on the 4th day (p < 0.05). The physiological indices, such as RR and ST, increased significantly (p < 0.05) with the HS level and were significantly decreased in the RHS group, compared to the SHS group (p < 0.05). HS induced the significant increase of MDA, TNF-α, and IL-ß, and the decrease of T-AOC, SOD, GPx, IL-10, IL-13, IgA, IgG, and IgM (p < 0.05). However, there was a significant improvement in these indices after the supplementation of folic acid and taurine under HS. Moreover, there were a significant increase in Quinella and Succinivibrio, and an evident decrease of the genera Rikenellaceae_RC9_gut_group and Asteroleplasma under HS (p < 0.05). The LEfSe analysis showed that the genera Butyrivibrio, Eubacterium_ventriosum_group, and f_Bifidobacteriaceae were enriched in the MHS, SHS and RHS groups, respectively. Correlated analysis indicated that the genus Rikenellaceae_RC9_gut_group was positively associated with MDA, while it was negatively involved in IL-10, IgA, IgM, and SOD (p < 0.05); The genus Anaeroplasma was positively associated with the propionate and valerate, while the genus Succinivibrio was negatively involved in TNF-α (p < 0.05). In conclusion, folic acid and taurine may alleviate the adverse effects of HS on antioxidant capacity, immunomodulation, and rumen fermentation of lambs by inducing changes in the microbiome that improve animal growth performance.

Effects of Chronic Heat Stress on Growth, Apoptosis, Antioxidant Enzymes, Transcriptomic Profiles, and Immune-Related Genes of Hong Kong Catfish (Clarias fuscus).

Chronic heat stress can have detrimental effects on the survival of fish. This study aimed to investigate the impact of prolonged high temperatures on the growth, antioxidant capacity, apoptosis, and transcriptome analysis of Hong Kong catfish (Clarias fuscus). By analyzing the morphological statistics of C. fuscus subjected to chronic high-temperature stress for 30, 60, and 90 days, it was observed that the growth of C. fuscus was inhibited compared to the control group. The experimental group showed a significant decrease in body weight and body length compared to the control group after 60 and 90 days of high-temperature stress (p < 0.05, p < 0.01). A biochemical analysis revealed significant alterations in the activities of three antioxidant enzymes superoxide dismutase activity (SOD); catalase activity (CAT); glutathione peroxidase activity (GPx), the malondialdehyde content (MDA), and the concentrations of serum alkaline phosphatase (ALP); Aspartate aminotransferase (AST); and alanine transaminase (ALT) in the liver. TUNEL staining indicated stronger apoptotic signals in the high-temperature-stress group compared to the control group, suggesting that chronic high-temperature-induced oxidative stress, leading to liver tissue injury and apoptosis. Transcriptome analysis identified a total of 1330 DEGs, with 835 genes being upregulated and 495 genes being downregulated compared to the control group. These genes may be associated with oxidative stress, apoptosis, and immune response. The findings elucidate the growth changes in C. fuscus under chronic high temperature and provide insights into the underlying response mechanisms to a high-temperature environment.

Effects of Heat Stress on the Laying Performance, Egg Quality, and Physiological Response of Laying Hens.

As high temperature and relative humidity (RH) are the main environmental factors causing heat stress, the temperature-humidity index (THI) serves as an indicator of heat stress in livestock animals. This study aimed to determine the effects of heat stress on the laying performance, physiological responses, egg quality, and blood profile of laying hens by subjecting them to environmental conditions with varying THI levels (68-85) for 28 days. The indicators of laying performance, such as feed intake (-30%) and egg production rate (-11%), significantly decreased in the hens exposed to severe heat stress (33 °C, 66% RH) compared to those exposed to thermoneutral conditions (21 °C, 68% RH). Moreover, severe heat stress reduced the egg yolk color, eggshell thickness and strength, and Haugh units of the eggs produced by the laying hens. Furthermore, a significant increase in serum K+ and a decrease in Na+ levels were observed in the hens subjected to severe heat stress compared with those under thermoneutral conditions. Our results indicate that heat stress alters the physiological responses and metabolism of laying hens, resulting in a lower egg quality and production rate.

The Role of Heat-Induced Stress Granules in the Blood-Testis Barrier of Mice.

Stress granules (SGs) are membraneless ribonucleoprotein (RNP)-based cellular foci formed in response to stress, facilitating cell survival by protecting against damage. Mammalian spermatogenesis should be maintained below body temperature for proper development, indicating its vulnerability to heat stress (HS). In this study, biotin tracer permeability assays showed that the inhibition of heat-induced SG assembly in the testis by 4-8 mg/kg cycloheximide significantly increased the percentage of seminiferous tubules with a damaged blood-testis barrier (BTB). Western blot results additionally revealed that the suppression of heat-induced SG assembly in Sertoli cell line, TM4 cells, by RNA inference of G3bp1/2 aggravated the decline in the BTB-related proteins ZO-1, ß-Catenin and Claudin-11, indicating that SGs could protect the BTB against damage caused by HS. The protein components that associate with SGs in Sertoli cells were isolated by sequential centrifugation and immunoprecipitation, and were identified by liquid chromatography with tandem mass spectrometry. Gene Ontology and KEGG pathway enrichment analysis revealed that their corresponding genes were mainly involved in pathways related to proteasomes, nucleotide excision repair, mismatch repair, and DNA replication. Furthermore, a new SG component, the ubiquitin associated protein 2 (UBAP2), was found to translocate to SGs upon HS in TM4 cells by immunofluorescence. Moreover, SG assembly was significantly diminished after UBAP2 knockdown by RNA inference during HS, suggesting the important role of UBAP2 in SG assembly. In addition, UBAP2 knockdown reduced the expression of ZO-1, ß-Catenin and Claudin-11, which implied its potential role in the function of the BTB. Overall, our study demonstrated the role of SGs in maintaining BTB functions during HS and identified a new component implicated in SG formation in Sertoli cells. These findings not only offer novel insights into the biological functions of SGs and the molecular mechanism of low fertility in males in summer, but also potentially provide an experimental basis for male fertility therapies.

Enhanced resistance to heat and fungal infection in transgenic Trichoderma via over-expressing the HSP70 gene.

Heat stress is one of the major abiotic stresses affecting the growth, sporulation, colonization and survival of Trichoderma viride. This study aimed to gain a better insight into the underlying mechanism governing the heat stress response of T. viride Tv-1511. We analysed the transcriptomic changes of Tv-1511 under normal and heat stress conditions using RNA sequencing. We observed that Tv-1511 regulates the biosynthesis of secondary metabolites through a complex network of signalling pathways. Additionally, it significantly activates the anti-oxidant defence system, heat shock proteins and stress-response-related transcription factors in response to heat stress. TvHSP70 was identified as a key gene, and transgenic Tv-1511 overexpressing TvHSP70 (TvHSP70-OE) was generated. We conducted an integrated morphological, physiological and molecular analyses of the TvHSP70-OE and wild-type strains. We observed that TvHSP70 over-expression significantly triggered the growth, anti-oxidant capacity, anti-fungal activity and growth-promoting ability of Tv-1511. Regarding anti-oxidant capacity, TvHSP70 primarily up-regulated genes involved in enzymatic and non-enzymatic anti-oxidant systems. In terms of anti-fungal activity, TvHSP70 primarily activated genes involved in the synthesis of enediyne, anti-fungal and aminoglycoside antibiotics. This study provides a comparative analysis of the functional significance and molecular mechanisms of HSP70 in Trichoderma. These findings provide a valuable foundation for further analyses.

Heat stress alters the ovarian proteome in prepubertal gilts.

Heat stress (HS) occurs when exogenous and metabolic heat accumulation exceeds heat dissipation; a thermal imbalance that compromises female reproduction. This study investigated the hypothesis that HS alters the ovarian proteome and negatively impacts proteins engaged with insulin signaling, inflammation, and ovarian function. Prepubertal gilts (n = 19) were assigned to one of three environmental groups: thermal neutral with ad libitum feed intake (TN; n = 6), thermal neutral pair-fed (PF; n = 6), or HS (n = 7). For 7 d, HS gilts were exposed to 12-h cyclic temperatures of 35.0 ±â€…0.2 °C and 32.2 ±â€…0.1 °C, while TN and PF gilts were housed at 21.0 ±â€…0.1 °C. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was performed on ovarian protein homogenates. Relative to TN gilts, 178 proteins were altered (P ≤ 0.05, log2foldchange ≥ 1) by HS, with 76 increased and 102 decreased. STRING gene ontology classified and identified 45 biological processes including those associated with chaperone protein refolding, cytoplasmic translational initiation, and immune activation; with a protein-protein interaction web network of 158 nodes and 563 edges connected based on protein function (FDR ≤ 0.05). Relative to PF, HS altered 330 proteins (P ≤ 0.05, log2foldchange ≥ 1), with 151 increased and 179 decreased. Fifty-seven biological pathways associated with protein function and assembly, RNA processing, and metabolic processes were identified, with a protein-protein interaction network of 303 nodes and 1,606 edges. Comparing HS with both the TN and PF treatments, 72 ovarian proteins were consistently altered by HS with 68 nodes and 104 edges, with biological pathways associated with translation and gene expression. This indicates that HS alters the ovarian proteome and multiple biological pathways and systems in prepubertal gilts; changes that potentially contribute to female infertility.

Heat stress impairs female fertility, yet the mechanisms underlying reduced fecundity remain unclear. This study investigated the ovarian proteomic changes resultant from heat stress in prepubertal gilts and discovered changes related to several important biological processes that could be responsible for reduced female fertility.