Heat shock proteins: modifying factors in physiological stress responses and acquired thermotolerance

Acclimation to constant and fluctuating temperatures promotes distinct metabolic responses in Arctic char (Salvelinus alpinus)

The Arctic is warming three times faster than the global average, imposing challenges to cold-adapted fish, such as Arctic char (Salvelinus alpinus). We evaluated stress and metabolic responses of Arctic char to different thermal acclimation scenarios to determine whether responses to thermal variation differed from those to stable exposures. Fish were exposed for 7 days to one of four treatments: (1) control (12°C); (2) mean (16°C), corresponding to the mean temperature of the diel thermal cycle; (3) constant high temperature (20°C); and (4) diel thermal cycling (12 to 20°C every 24 h). Exposure to 20°C causes increases plasma lactate and glucose, an imbalance in antioxidant systems, and oxidative stress in the liver. The 20°C treatment also elevated fractional rates of protein synthesis and caused oxidative stress in the heart. Stress responses were more pronounced in diel thermal cycling than in mean (16°C) fish, indicating that peak exposure temperatures or variation are physiologically important. Cortisol was highest in diel thermal cycling fish and oxidative stress was noted in the liver. Gill Na+/K+-ATPase activity was also significantly reduced in diel thermal cycling fish, suggesting gill remodeling in response to an osmoregulatory stress. Exposure to a constant 20°C was more challenging than a diel thermal cycle, demonstrating the importance of daily cooling to recovery. Arctic char inhabit a thermally variable environment and understanding how this impacts their physiology will be critical for informing conservation strategies in the context of a rapidly warming Arctic.

Early life thermal conditioning alters heat-shock protein expression in response to an adult thermal stressor

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.

Progressive Thickening of Retinal Nerve Fiber and Ganglion Cell Complex Layers Following SDM Laser Vision Protection Therapy in Open-Angle Glaucoma

INTRODUCTION

This work aims to determine the effect on nerve fiber layer (NFL) and ganglion cell complex (GCC) thickness trends in eyes with open-angle glaucoma (OAG) treated with Vision Protection Therapy™ (VPT).

METHODS

A retrospective analysis of spectral-domain optical coherence tomography (OCT) measured NFL and GCC thickness trends was performed, excluding eyes with poor-quality scans and principal diagnoses other than OAG. This study compares eyes with OAG managed conventionally with IOP control alone (controls) to eyes managed with the addition of VPT (VPT eyes). The direction (+ or -) and magnitude (microns/year) of the OCT trends were the study endpoints.

RESULTS

Seventy-eight control eyes of 40 patients and 61 VPT-treated eyes of 39 patients were included in the study. Positive NFL trends were noted in 5% of control eyes vs. 71% of VPT eyes (p < 0.0001). Positive GCC trends were noted in 8% of control eyes vs. 43% of VPT eyes (p < 0.0001). Mean NFL trends (µm/year) were - 0.692 for controls vs. 0.347 for VPT (p < 0.0001). Mean GCC trends (µm/year) were - 0.554 for controls vs. - 0.148 for VPT (p = 0.0175).

CONCLUSIONS

The addition of VPT to the conventional management of OAG resulted in highly significant improvements in NFL and GCC trends, indicating a reversal of key indicators of glaucoma severity and progression.

Thermo-adaptive evolution of Corynebacterium glutamicum reveals the regulatory functions of fasR and hrcA in heat tolerance

BACKGROUND

High-temperature fermentation technology is promising in improving fermentation speed and product quality, and thereby widely used in various fields such as food, pharmaceuticals, and biofuels. However, extreme temperature conditions can disrupt cell membrane structures and interfere with the functionality of biological macromolecules (e.g. proteins and RNA), exerting detrimental effects on cellular viability and fermentation capability.

RESULTS

Herein, a microbial thermotolerance improvement strategy was developed based on adaptive laboratory evolution (ALE) for efficient high-temperature fermentation. Employing this strategy, we have successfully obtained Corynebacterium glutamicum strains with superior resistance to high temperatures. Specifically, the genome analysis indicated that the evolved strains harbored 13 missense genetic mutations and 3 same-sense genetic mutations compared to the non-evolved parent strain. Besides, reverse transcription quantitative PCR analysis (RT qPCR) of the hrcA-L119P mutant demonstrated that both groEL genes were upregulated under 42 °C, which enabled the construction of robust strains with improved heat tolerance. Furthermore, a significant increase in FAS-IA and FAS-IB expression of the fasR-L102F strain was proved to play a key role in protecting cells against heat stress.

CONCLUSIONS

This work systematically reveals the thermotolerance mechanisms of Corynebacterium glutamicum and opens a new avenue for revolutionizing the design of cell factories to boost fermentation efficiency.

Laser-Based Therapy Approaches in the Retina: A Review of Micropulse Laser Therapy for Diabetic Retinopathy

PURPOSE

This review aims to elucidate the mechanisms and clinical utility of subthreshold micropulse laser (SML) therapy in the context of retinal care. Subthreshold or "nondestructive" laser therapy encompasses treatment modalities that induce minimal or no harm to retinal or choroidal tissue and leave no visible sings post-application, while achieving clinical efficacy.

METHODS

A comprehensive review of literature sourced from databases including PubMed, Medline, Embase, Cochrane, and Web of Science was conducted, focusing on articles published before February 2024, and discussing the contemporary use of SML therapy in treating diabetic retinopathy (DR).

RESULTS

The review presents evidence from scientific literature supporting SML therapy as a viable therapeutic approach for management of DR. Across numerous studies, SML therapy has demonstrated safety and additional therapeutic efficacy without causing damage to underlying retinal tissue.

CONCLUSION

Subthreshold laser treatment emerges as a safe strategy for addressing DR. Numerous studies have shown its additional efficacy to anti-VEGF pharmacotherapy, which is the currently approved monotherapy for complications of DR. Ongoing research and clinical investigations aim to further elucidate the mechanisms and optimize the therapeutic advantages of this technology.

O-GlcNAc modification of HSP27 alters its protein interactions and promotes refolding of proteins through the BAG3/HSP70 co-chaperone

Almost all types of cellular stress induce post-translational O-GlcNAc modifications of proteins, and this increase promotes cell survival. We previously demonstrated that O-GlcNAc on certain small heat shock proteins (sHSPs), including HSP27, directly increases their chaperone activity as one potential protective mechanism. Here, we furthered our use of synthetic proteins to prepare biotinylated sHSPs and show that O-GlcNAc modification of HSP27 also changes how it interacts within the sHSP system and the broader HSP network. Specifically, we show that O-GlcNAc modified HSP27 binds more strongly to the co-chaperone protein BAG3, which then promotes refolding of a model substrate by HSP70. We use proteomics to identify other potential HSP27 interactions that are changed by O-GlcNAc, including one that we confirm with another sHSP, αB-crystallin. These findings add additional evidence for O-GlcNAc as a switch for regulating protein-protein interactions and for modifications of chaperones as one mechanism by which O-GlcNAc protects against protein aggregation.

Radiofrequency ablation: mechanisms and clinical applications

Radiofrequency ablation (RFA), a form of thermal ablation, employs localized heat to induce protein denaturation in tissue cells, resulting in cell death. It has emerged as a viable treatment option for patients who are ineligible for surgery in various diseases, particularly liver cancer and other tumor-related conditions. In addition to directly eliminating tumor cells, RFA also induces alterations in the infiltrating cells within the tumor microenvironment (TME), which can significantly impact treatment outcomes. Moreover, incomplete RFA (iRFA) may lead to tumor recurrence and metastasis. The current challenge is to enhance the efficacy of RFA by elucidating its underlying mechanisms. This review discusses the clinical applications of RFA in treating various diseases and the mechanisms that contribute to the survival and invasion of tumor cells following iRFA, including the roles of heat shock proteins, hypoxia, and autophagy. Additionally, we analyze‌ the changes occurring in infiltrating cells within the TME after iRFA. Finally, we provide a comprehensive summary of clinical trials involving RFA in conjunction with other treatment modalities in the field of cancer therapy, aiming to offer novel insights and references for improving the effectiveness of RFA.

High temperature induces oxidative stress in spotted seabass (Lateolabrax maculatus) and leads to inflammation and apoptosis

Our study aims to examine the changes of long-term high temperature on the mortality and health status of spotted seabass (Lateolabrax maculatus), as well as to screen suitable biomarkers to determine whether the spotted seabass is under heat stress. In this study, 360 juvenile spotted seabass were evenly distributed into three temperature-controlled systems at 27 °C (N, normal temperature), 31 °C (M, moderate temperature), and 35 °C (H, high temperature) for an 8-week aquaculture experiment. The results revealed that 35 °C water temperature significantly increased the mortality and the MDA content in tissues (P < 0.05). Meanwhile, 35 °C water temperature significantly increased the activity of SOD enzyme and T-AOC capacity in tissues, as well as the expression of hsp60, hsp70, and hsp90 (P < 0.05). Additionally, the expression of nrf2, il1β, il8, caspase3, caspase9, and bax in the liver significantly increased (P < 0.05), while the expression of keap1, il10, tgfβ, and bcl2 decreased significantly (P < 0.05). These results indicate that 35 °C water temperature induces oxidative stress in spotted seabass, leading to tissue oxidative damage, promoting inflammation and apoptosis in liver, and increasing mortality. However, the organism compensates by heightening its antioxidant capacity via the Nrf2-Keap1 signaling pathway and inducing high expression of heat shock proteins for self-protection. Furthermore, the alterations in the mRNA level of hsp70 and MDA content in the liver, muscle, and kidney can serve as indicators for evaluating spotted seabass under prolonged heat stress.

Transcriptome Analysis Identifies Key Genes Involved in Response and Recovery to High Heat Stress Induced by Fire in Schima superba

Fire-resistant tree species play a crucial role in forest fire prevention, utilizing several physiological and molecular mechanisms to respond to extreme heat stress. Many transcription factors (TFs) and genes are known to be involved in the regulatory network of heat stress response in plants. However, their roles in response to high temperatures induced by fire remain less understood. In this study, we investigated Schima superba, a fire-resistant tree, to elucidate these mechanisms. Leaves of S. superba seedlings were exposed to fire stimulation for 10 s, 30 s, and 1 min, followed by a 24-h recovery period. Fifteen transcriptomes were assembled to identify key molecular and biological pathways affected by high temperatures. Differentially expressed genes (DEGs) analysis revealed essential candidate genes and TFs involved in the heat stress response, including members of the ethylene-responsive factors, WRKY, MYB, bHLH, and Nin-like families. Genes related to heat shock proteins/factors, lipid metabolism, antioxidant enzymes, dehydration responses, and hormone signal transduction were differentially expressed after heat stress and recovery, underscoring their roles in cellular process and recovery after heat stress. This study advances our understanding of plant response and defense strategies against extreme abiotic stresses.

JRK binds satellite III DNA and is necessary for the heat shock response

JRK is a DNA-binding protein of the pogo superfamily of transposons, which includes the well-known centromere binding protein B (CENP-B). Jrk null mice exhibit epilepsy, and growth and reproductive disorders, consistent with its relatively high expression in the brain and reproductive tissues. Human JRK DNA variants and gene expression levels are implicated in cancers and neuropsychiatric disorders. JRK protein modulates β-catenin-TCF activity but little is known of its cellular functions. Based on its homology to CENP-B, we determined whether JRK binds centromeric or other satellite DNAs. We show that human JRK binds satellite III DNA, which is abundant at the chromosome 9q12 juxtacentromeric region and on Yq12, both sites of nuclear stress body assembly. Human JRK-GFP overexpressed in HeLa cells strongly localises to 9q12. Using an anti-JRK antiserum we show that endogenous JRK co-localises with a subset of centromeres in non-stressed cells, and with heat shock factor 1 following heat shock. Knockdown of JRK in HeLa cells proportionately reduces heat shock protein gene expression in heat-shocked cells. A role for JRK in regulating the heat shock response is consistent with the mouse Jrk null phenotype and suggests that human JRK may act as a modifier of diseases with a cellular stress component.

Thermal tolerance plasticity and dynamics of thermal tolerance in Eublepharis macularius: Implications for future climate-driven heat stress

The intensity and duration of heat waves, as well as average global temperatures, are expected to increase due to climate change. Heat waves can cause physiological stress and reduce fitness in animals. Species can reduce overheating risk through phenotypic plasticity, which allows them to raise their thermal tolerance limits over time. This mechanism could be important for ectotherms whose body temperatures are directly influenced by available environmental temperatures. Geckos are a large, diverse group of ectotherms that vary in their thermal habitats and times of daily activity, which could affect how they physiologically adjust to heat waves. Data on thermal physiology are scarce for reptiles, with only one study in geckos. Understanding thermal tolerance and plasticity, and their relationship, is essential for understanding how some species are able to adjust or adapt to changing temperatures. In this study, we estimated thermal tolerance and plasticity, and their interaction, in the crepuscular gecko, Eublepharis macularius, a species that is emerging as a model for reptile biology. After estimating basal thermal tolerance for 28 geckos, thermal tolerance was measured for each individual a second time at several timepoints (3, 6, or 24 h) to determine thermal tolerance plasticity. We found that thermal tolerance plasticity (1) does not depend on the basal thermal tolerance of the organism, (2) was highest after 6 h from initial heat shock, and (3) was negatively influenced by individual body mass. Our findings contribute to the increasing body of work focused on understanding the influence of biological and environmental factors on thermal tolerance plasticity in organisms and provide phenotypic data to further investigate the molecular basis of thermal tolerance plasticity in organisms.

Central Serous Chorioretinopathy: An Update on the Current State of Management

Central serous chorioretinopathy (CSCR) is a relatively common retinal disorder that leads to central vision impairment, often with a high recurrence rate. The exact etiology and pathogenetic mechanisms have not been fully elucidated but are likely to be associated with hyperpermeability of the choroidal capillaries and failure of the retinal pigment epithelium (RPE), leading to serous detachment of the neurosensory retina. Multimodal imaging plays a critical role in the diagnostic approach and monitoring of CSCR. Fortunately, the natural course of the disease is usually self-limiting, with spontaneous resolution and total fluid reabsorption. However, some patients may exhibit recurrences or persistent subretinal fluid (chronic CSCR), leading to progressive and irreversible RPE atrophy or photoreceptor damage. Thus, to prevent permanent visual loss, individualized treatment should be considered. Recent developments in the diagnostic and therapeutic approach have contributed to better outcomes in patients with CSCR. More studies are required to improve our understanding of epidemiology, pathogenesis, diagnosis, and treatment, with a significant impact on the management of this challenging clinical entity. The purpose of this review is to summarize the current knowledge about the clinical features, diagnostic workup, and therapeutic approach of CSCR.

Embryonic thermal manipulation: a potential strategy to mitigate heat stress in broiler chickens for sustainable poultry production

Due to high environmental temperatures and climate change, heat stress is a severe concern for poultry health and production, increasing the propensity for food insecurity. With climate change causing higher temperatures and erratic weather patterns in recent years, poultry are increasingly vulnerable to this environmental stressor. To mitigate heat stress, nutritional, genetic, and managerial strategies have been implemented with some success. However, these strategies did not adequately and sustainably reduce the heat stress. Therefore, it is crucial to take proactive measures to mitigate the effects of heat stress on poultry, ensuring optimal production and promoting poultry well-being. Embryonic thermal manipulation (TM) involves manipulating the embryonic environment's temperature to enhance broilers' thermotolerance and growth performance. One of the most significant benefits of this approach is its cost-effectiveness and saving time associated with traditional management practices. Given its numerous advantages, embryonic TM  is a promising strategy for enhancing broiler production and profitability in the poultry industry. TM increases the standard incubation temperature in the mid or late embryonic stage to induce epigenetic thermal adaption and embryonic metabolism. Therefore, this review aims to summarize the available literature and scientific evidence of the beneficial effect of pre-hatch thermal manipulation on broiler health and performance.

Phosphorylation of 399S at CsHsp70 of Cymbidium sinense is essential to maintain chlorophyll stability

The Chinese orchids symbolise nobility and gentility in China, and the variation of leaf color makes Cymbidium sinense more diversified and valuable. However, its color variations especially at the protein level still remain largely unexplored. In this study, the proteomics and phosphoproteomics of Cymbidium sinense leaf color variation mutants were studied. A total of 1059 differentially abundant proteins (DAPs) and 1127 differentially abundant phosphorylation sites belonging to 644 phosphoproteins (DAPPs) were identified in the yellow section of leaf variegation mutant of Cymbidium sinense (MY) compared with the green section (MG). Moreover, 349 co-expressing proteins were found in both omics' datasets, while only 26 proteins showed the same expression patterns in the two omics. The interaction network analysis of kinases and phosphatases showed that DAPs and DAPPs in photosynthesis, response to hormones, pigment metabolic process, phosphorylation, glucose metabolic process, and dephosphorylation might contribute to leaf color variation. The abundance of 28 Hsps and 28 phosphorylation sites belonging to 10 Hsps showed significant differences between MG and MY. CsHsp70 was selected to explore the function in Cymbidium sinense leaf variegation. The results showed CsHsp70 is essential for maintaining photosynthetic pigment content and the 399S phosphorylation site is crucial to the function of CsHsp70. Collectively, our findings construct a comprehensive coverage of protein and protein phosphorylation in leaf variegation of C. sinense, providing valuable insights into its formation mechanisms.

Transcriptome analysis revealed potential mechanisms of channel catfish growth advantage over blue catfish in a tank culture environment

Channel catfish (Ictalurus punctatus) and blue catfish (Ictalurus furcatus) are two economically important freshwater aquaculture species in the United States, with channel catfish contributing to nearly half of the country's aquaculture production. While differences in economic traits such as growth rate and disease resistance have been noted, the extent of transcriptomic variance across various tissues between these species remains largely unexplored. The hybridization of female channel catfish with male blue catfish has led to the development of superior hybrid catfish breeds that exhibit enhanced growth rates and improved disease resistance, which dominate more than half of the total US catfish production. While hybrid catfish have significant growth advantages in earthen ponds, channel catfish were reported to grow faster in tank culture environments. In this study, we confirmed channel fish's superiority in growth over blue catfish in 60-L tanks at 10.8 months of age (30.3 g and 11.6 g in this study, respectively; p < 0.001). In addition, we conducted RNA sequencing experiments and established transcriptomic resources for the heart, liver, intestine, mucus, and muscle of both species. The number of expressed genes varied across tissues, ranging from 5,036 in the muscle to over 20,000 in the mucus. Gene Ontology analysis has revealed the functional specificity of differentially expressed genes within their respective tissues, with significant pathway enrichment in metabolic pathways, immune activity, and stress responses. Noteworthy tissue-specific marker genes, including lrrc10, fabp2, myog, pth1a, hspa9, cyp21a2, agt, and ngtb, have been identified. This transcriptome resource is poised to support future investigations into the molecular mechanisms underlying environment-dependent heterosis and advance genetic breeding efforts of hybrid catfish.

Association between physiological responses and heat shock protein 70 (HSP70) expressions in the vulnerable populations of Kuala Lumpur

Continued heat exposure can cause physiological and cellular responses. This study investigated the association between physiological responses and heat shock protein 70 (HSP70) expressions in Kuala Lumpur's urban vulnerable population. We conducted a cross-sectional study involving 54 participants from four areas classified as experiencing moderate to strong heat stress. Physiological measurements included core body temperature, heart rate, and diastolic and systolic blood pressure. RT-qPCR and ELISA were also performed on blood samples to assess HSP70 gene and protein expressions. Despite indoor heat stress, participants maintained normal physiological parameters while there were significant indications of HSP70 expression at both the gene and protein levels. However, our study found no significant correlation (p > 0.05) between physiological responses and HSP70 expressions. This study shows no interaction between physiological responses and HSP70 expressions in the study population, revealing the complex mechanisms of indoor heat stress in vulnerable individuals.

Molecular Characterization and Seasonal Variation in Expression of HSP70.1 Gene in Gangatiri Cattle and Its Comparison with Buffalo

Under tropical climate heat stress is a major challenge for livestock production. HSP70.1 is a ubiquitously expressed protein maintaining cellular machinery through proper folding of denatured proteins and prevents cellular apoptosis and protect cell from heat stress. Therefore, present investigation was undertaken to explore genetic variability in HSP70.1 gene in Gangatiri cattle, its comparison with buffalo sequences and differential expression in different season. The allelic variant was identified by sequencing amplified PCR product of HSP70.1 gene by primer walking. Season-wise total RNA samples was prepared for differential expression study. Brilliant SYBR Green QPCR technique was used to study the expression kinetics of this gene. DNA sequencing by primer walking identified four allelic variants in Gangatiri cattle. Sequence alignment study revealed four, six and one substitutions in the 5' untranslated region (5'UTR), coding and 3' untranslated region ((3'UTR) of HSP70.1 gene, respectively. Comparative analysis of HSP70.1 gene revealed that Cattle has shorter 5'UTR and 3' UTR than the buffalo. In Gangatiri cattle, summer season has significantly higher (P ≤ 0.05) expression of HSP70.1 than the spring and winter. The relative expression of HSP70.1 was increased by more than six folds in summer and nearly 1.5 folds higher in winter in comparison to the spring season. Therefore, HSP70.1 may be considered to have a critical role in the development of thermal tolerance in Gangatiri cattle.

Testicular expression of heat SHOCK proteins 60, 70, and 90 in cryptorchid horses

Heat shock proteins are the most evolutionarily conserved protein families induced by stressors including hyperthermia. In the context of pathologies of the male reproductive tract, cryptorchidism is the most common genital defect that compromises the reproductive potential of the male because it induces an increase in intratesticular temperature. In equine species, cryptorchidism affects almost 9 % of newborns and few studies have been carried out on the molecular aspects of the retained testis. In this study, the expression pattern of HSP60, 70, and 90 in abdominal and inguinal testes, in their contralateral descended normally testes, and in testes of normal horses were investigated by Western blot and immunohistochemistry. The histomorphological investigation of retained and scrotal testes was also investigated. The seminiferous epithelium of the retained testes showed a vacuolized appearance and displayed a completely blocked spermatogenesis for lacking meiotic and spermiogenetic cells. On the contrary, the contralateral scrotal testes did not show morphological damage and the seminiferous epithelium displayed all phases of the spermatogenetic cycle as in the normal testes. The morphology of Leydig cells was not affected by the cryptorchid state. Western blot and immunohistochemistry evidenced that equine testis (both scrotal and retained) expresses the three investigated HSPs. More in detail, the Western blot evidenced that HSP70 is the more expressed chaperone and that together with HSP90 it is highly expressed in the retained gonad (P < 0.05). The immunohistochemistry revealed the presence of the three HSPs in the spermatogonia of normal and cryptorchid testes. Spermatogonia of retained testes showed the lowest expression of HSP60 and the highest expression of HSP90. Spermatocytes, spermatids of scrotal testes, and the Sertoli cells of retained and scrotal testes did not display HSP60 whereas expressed HSP70 and HSP90. These two proteins were also localized in the nucleus of the premeiotic cells. The Leydig cells displayed the three HSPs with the higher immunostaining of HSP70 and 90 in the cryptorchid testes. The results indicate that the heat stress condition occurring in the cryptorchid testis influences the expression of HSPs.

HSP gene superfamily in Aspongopus chinensis Dallas: unravelling identification, characterisation and expression patterns during diapause and non-diapause stages

Aspongopus chinensis Dallas 1851, an insect of important economic value, faces challenges in artificial breeding due to mandatory diapause and limited access to wild resources. Heat shock proteins (Hsps) are thought to influence diapause in insects, but little is known about their role in A. chinensis during diapause. This study used genomic methods to identify 25 Hsp genes in A. chinensis, including two Hsp90, 14 Hsp70, four Hsp60 and five small Hsp genes, were located on seven chromosomes, respectively. The gene structures among the same families are relatively conserved. Meanwhile, the motif compositions and secondary structures of A. chinensis Hsps (AcHsps) were predicted. RNA-seq data and fluorescence quantitative PCR analysis showed that there were differences in the expression patterns of AcHsps in diapause and non-diapause stages, and AcHsp70-5 was significantly differentially expressed in both analysis, which was enriched in the pathway of response to hormone. All the results showed that Hsps play an important role in the diapause mechanism of A. chinensis. Our observations highlight the molecular evolution of the Hsp gene and their effect on diapause in A. chinensis.

Alterations in network robustness upon simultaneous temperature and pH perturbations

Nervous systems have evolved to function consistently in the face of the normal environmental fluctuations experienced by animals. The stomatogastric nervous system (STNS) of the crab, Cancer borealis, produces a motor output that has been studied for its remarkable robustness in response to single global perturbations. Changes in environments, however, are often complex and multifactorial. Therefore, we studied the robustness of the pyloric network in the stomatogastric ganglion (STG) in response to simultaneous perturbations of temperature and pH. We compared the effects of elevated temperatures on the pyloric rhythm at control, acid, or base pHs. In each pH recordings were made at 11°C, and then the temperature was increased until the rhythms became disorganized ("crashed"). Pyloric burst frequencies and phase relationships showed minor differences between pH groups until reaching close to the crash temperatures. However, the temperatures at which the rhythms were disrupted were lower in the two extreme pH conditions. This indicates that one environmental stress can make an animal less resilient to a second stressor.NEW & NOTEWORTHY Resilience to environmental fluctuations is important for all animals. It is common that animals encounter multiple stressful events at the same time, the cumulative impacts of which are largely unknown. This study examines the effects of temperature and pH on the nervous system of crabs that live in the fluctuating environments of the Northern Atlantic Ocean. The ranges of tolerance to one perturbation, temperature, are reduced under the influence of a second, pH.

Selection Signal Analysis Reveals Hainan Yellow Cattle Are Being Selectively Bred for Heat Tolerance

Hainan yellow cattle are indigenous Zebu cattle from southern China known for their tolerance of heat and strong resistance to disease. Generations of adaptation to the tropical environment of southern China and decades of artificial breeding have left identifiable selection signals in their genomic makeup. However, information on the selection signatures of Hainan yellow cattle is scarce. Herein, we compared the genomes of Hainan yellow cattle with those of Zebu, Qinchuan, Nanyang, and Yanbian cattle breeds by the composite likelihood ratio method (CLR), Tajima's D method, and identifying runs of homozygosity (ROHs), each of which may provide evidence of the genes responsible for heat tolerance in Hainan yellow cattle. The results showed that 5210, 1972, and 1290 single nucleotide polymorphisms (SNPs) were screened by the CLR method, Tajima's D method, and ROH method, respectively. A total of 453, 450, and 325 genes, respectively, were identified near these SNPs. These genes were significantly enriched in 65 Gene Ontology (GO) functional terms and 11 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways (corrected p < 0.05). Five genes-Adenosylhomocysteinase-like 2, DnaJ heat shock protein family (Hsp40) member C3, heat shock protein family A (Hsp70) member 1A, CD53 molecule, and zinc finger and BTB domain containing 12-were recognized as candidate genes associated with heat tolerance. After further functional verification of these genes, the research results may benefit the understanding of the genetic mechanism of the heat tolerance in Hainan yellow cattle, which lay the foundation for subsequent studies on heat stress in this breed.

Molecular and functional characterization of heat-shock protein 70 in Aphis gossypii under thermal and xenobiotic stresses

Aphis gossypii, a globally distributed and economically significant pest of several crops, is known to infest a wide range of host plants. Heat shock proteins (Hsps), acting as molecular chaperones, are essential for the insect's environmental stress responses. The present study investigated the molecular characteristics and expression patterns of AgHsp70, a heat shock protein gene, in Aphis gossypii. Our phylogenetic analysis revealed that AgHsp70 shared high similarity with homologs from other insects, suggesting a conserved function across species. The developmental expression profiles of AgHsp70 in A. gossypii showed that the highest transcript levels were observed in the fourth instar nymphs, while the lowest levels were detected in the third instar nymphs. Heat stress and exposure to four different xenobiotics (2-tridecanone, tannic acid, gossypol, and flupyradifurone (4-[(2,2-difluoroethyl)amino]-2(5H)-furanone)) significantly up-regulated AgHsp70 expression. Knockdown of AgHsp70 using RNAi obviously increased the susceptibility of cotton aphids to 2-tridecanone, gossypol and flupyradifurone. Dual-luciferase reporter assays revealed that gossypol and flupyradifurone significantly enhanced the promoter activity of AgHsp70 at a concentration of 10 mg/L. Furthermore, we identified the transcription factor heat shock factor (HSF) as a regulator of AgHsp70, as silencing AgHSF reduced AgHsp70 expression. Our results shed light on the role of AgHsp70 in xenobiotic adaptation and thermo-tolerance.

Effects of Temperature Adaptation on the Metabolism and Physiological Properties of Sturgeon Fish Larvae Cell Line

This study investigated how Atlantic sturgeon cells respond to elevated temperatures, shedding light on the potential impacts of climate change on fish. Atlantic sturgeon (Acipenser oxyrinchus), an IUCN (International Union for Conservation of Nature) Red List species and evolutionarily related to paleonisiform species, may have considerable physiological adaptability, suggesting that this species may be able to cope with changing climatic conditions and higher temperatures. To test this hypothesis, the AOXlar7y cell line was examined at 20 °C (control) and at elevated temperatures of 25 °C and 28 °C. Parameters including proliferation, vitality, morphology, and gene expressions related to proliferation, stemness, and stress were evaluated. Additionally, to achieve a comprehensive understanding of cellular changes, mitochondrial and metabolic activities were assessed using Seahorse XF96. AOXlar7y cells adapted to 28 °C exhibited enhanced mitochondrial adaptability, plasticity, heightened cell proliferation, and increased hsp70 expression. Increased baseline respiration indicated elevated ATP demand, which is potentially linked to higher cell proliferation and heat stress defense. Cells at 28 °C also displayed elevated reserve respiration capacity, suggesting adaptation to energy demands. At 25 °C, AOXlar7y cells showed no changes in basal respiration or mitochondrial capacity, suggesting unchanged ATP demand compared to cells cultivated at 20 °C. Proliferation and glycolytic response to energy requirements were diminished, implying a connection between glycolysis inhibition and proliferation suppression. These research results indicate sturgeon cells are capable of withstanding and adapting to an 8 °C temperature increase. This cellular analysis lays a foundation for future studies aimed at a deeper understanding of fish cell physiological adaptations, which will contribute to a better knowledge of environmental threats facing Atlantic sturgeon and fish populations amid climate change.

Comprehensive Proteomic Analysis of Common Bean (Phaseolus vulgaris L.) Seeds Reveal Shared and Unique Proteins Involved in Terminal Drought Stress Response in Tolerant and Sensitive Genotypes

This study identified proteomic changes in the seeds of two tolerant (SB-DT3 and SB-DT2) and two sensitive (Merlot and Stampede) common bean genotypes in response to terminal drought stress. Differentially expressed proteins (DEPs) were abundant in the susceptible genotype compared to the tolerant line. DEPs associated with starch biosynthesis, protein-chromophore linkage, and photosynthesis were identified in both genotypes, while a few DEPs and enriched biological pathways exhibited genotype-specific differences. The tolerant genotypes uniquely showed DEPs related to sugar metabolism and plant signaling, while the sensitive genotypes displayed more DEPs involved in plant-pathogen interaction, proteasome function, and carbohydrate metabolism. DEPs linked with chaperone and signal transduction were significantly altered between both genotypes. In summary, our proteomic analysis revealed both conserved and genotype-specific DEPs that could be used as targets in selective breeding and developing drought-tolerant common bean genotypes.

The response of heat shock proteins in honey bees to abiotic and biotic stressors

Honey bees, Apis mellifera, are the most important managed pollinators worldwide. They are highly impacted by various abiotic and biotic stressors, especially temperature extremes, which can lead to cellular damage and death. The induction of heat shock proteins (HSPs) has been recorded in honey bees as a response to various types of stressors. HSPs are classified into different gene families according to their molecular weights. HSPs play an important role in maintaining cellular protein homeostasis due to their contribution as molecular chaperones or co-chaperones. HSPs in honey bees have complex functions with induction even under normal colony conditions. Previous studies have suggested various functions of HSPs to protect cells from damage under exposure to environmental stressors, pollutants, and pathogens. Surprisingly, HSPs have also been found to play roles in larval development and age-related tasks. The expression of HSPs varies depending on tissue type, developmental stage, age, and stress period. This article reviews studies on HSPs (sHSPs, HSP40, HSP60, HSP70, and HSP90) in honey bees and highlights gaps in the available knowledge. This review is crucial for honey bee research, particularly in the face of climate change challenges.

Effects of acute and chronic chromium stress on the expression of heat shock protein genes and activities of antioxidant enzymes in larvae of Orthetrum albistylum

The dragonfly species Orthetrum albistylum, can accumulate heavy metals from its aquatic environment and thus serves as a biological indicator for monitoring and evaluating water quality. Heat shock proteins (HSPs) play important biological roles in resistance to various types of environmental stress. The full-length cDNA sequences of the heat shock cognate (hsc) 70 and heat shock protein (hsp) 70 genes were cloned from O. albistylum larvae. Relative levels of expression of hsc70 and hsp70 in the head, epidermis, midgut, and adipose tissue were measured by qRT-PCR after chronic and acute contamination of 5-8 instar larvae with chromium (Cr) solution, and under control conditions. Activities of superoxide dismutase (SOD) and catalase (CAT) in chronically contaminated larvae were also measured. Phylogenetic analysis revealed that the cloned hsc70 and hsp70 genes were highly homologous to known HSP70 family members reported in other insects. The mRNA levels of hsc70 and hsp70 did not differ significantly in various larval tissues. Under chronic chromium stress, hsc70 and hsp70 expression were upregulated to a maximum and then downregulated; hsp70 mRNA levels were higher than those of hsc70 at all concentrations of chromium. Under acute chromium stress, hsc70 expression was inhibited at low chromium concentrations and upregulated at chromium concentrations higher than 125 mg/L. However, hsp70 expression was higher than that in the control group and markedly higher than that of hsc70. Changes in SOD and CAT activities displayed consistent trends for different chronic chromium concentrations, first increasing and then decreasing over time. Collectively, these findings demonstrated the response of the HSP family of genes and antioxidant enzymes following exposure to heavy metal stress, as well as their potential applicability as biomarkers for monitoring environmental pollutants.

A comprehensive review of the interaction between COVID-19 spike proteins with mammalian small and major heat shock proteins

Coronavirus disease 2019 (COVID-19) is a novel disease that had devastating effects on human lives and the country's economies worldwide. This disease shows similar parasitic traits, requiring the host's biomolecules for its survival and propagation. Spike glycoproteins severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 spike protein) located on the surface of the COVID-19 virus serve as a potential hotspot for antiviral drug development based on their structure. COVID-19 virus calls into action the chaperonin system that assists the attacker, hence favoring infection. To investigate the interaction that occurs between SARS-CoV-2 spike protein and human molecular chaperons (HSPA8 and sHSP27), a series of steps were carried out which included sequence attainment and analysis, followed by multiple sequence alignment, homology modeling, and protein-protein docking which we performed using Cluspro to predict the interactions between SARS-CoV-2 spike protein and human molecular chaperones of interest. Our findings depicted that SARS-CoV-2 spike protein consists of three distinct chains, chains A, B, and C, which interact forming hydrogen bonds, hydrophobic interactions, and electrostatic interactions with both human HSPA8 and HSP27 with -828.3 and -827.9 kcal/mol as binding energies for human HSPA8 and -1166.7 and -1165.9 kcal/mol for HSP27.

Comprehensive genome‑wide analysis of the chicken heat shock protein family: identification, genomic organization, and expression profiles in indigenous chicken with highly pathogenic avian influenza infection

BACKGROUND

Heat shock proteins (HSPs) function as molecular chaperones with critical roles in chicken embryogenesis, immune response to infectious diseases, and response to various environmental stresses. However, little is known on HSP genes in chicken. In this study, to understand the roles of chicken HSPs, we performed genome-wide identification, expression, and functional analyses of the HSP family genes in chicken.

RESULTS

A total of 76 HSP genes were identified in the chicken genome, which were further classified into eight distinct groups (I-VIII) based on phylogenetic tree analysis. The gene-structure analysis revealed that the members of each clade had the same or similar exon-intron structures. Chromosome mapping suggested that HSP genes were widely dispersed across the chicken genome, except in chromosomes 16, 18, 22, 25, 26, and 28-32, which lacked chicken HSP genes. On the other hand, the interactions among chicken HSPs were limited, indicating that the remaining functions of HSPs could be investigated in chicken. Moreover, KEGG pathway analysis showed that the HSP gene family was involved in the regulation of heat stress, apoptotic, intracellular signaling, and immune response pathways. Finally, RNA sequencing data revealed that, of the 76 chicken HSP genes, 46 were differentially expressed at 21 different growth stages in chicken embryos, and 72 were differentially expressed on post-infection day 3 in two indigenous Ri chicken lines infected with highly pathogenic avian influenza.

CONCLUSIONS

This study provides significant insights into the potential functions of HSPs in chicken, including the regulation of apoptosis, heat stress, chaperone activity, intracellular signaling, and immune response to infectious diseases.

Review: The role of heat shock proteins in chicken: Insights into stress adaptation and health

This review article aimed to provide readers with a comprehensive understanding of the function of heat shock proteins (HSPs) in chicken physiology, stress response, and overall poultry health. With the increasing challenges faced by the livestock industry, particularly the poultry sector, due to climate change-induced high ambient temperatures, heat stress (HS) has become a critical concern. HS disrupts the thermal balance in poultry, leading to detrimental effects on growth, immune function, and overall health. HSPs play a pivotal role in mitigating the impacts of HS in chickens. These molecular chaperones are involved in protein folding, unfolding, and assembly, and they are classified into several families based on their size, including small molecule HSPs, HSP40, HSP60, HSP70, HSP90, and HSP110. By maintaining cellular homeostasis and promoting stress tolerance, HSPs act as vital guardians in helping chickens cope with HS and its associated consequences. The review synthesized relevant literature to shed light on the importance of HSPs in stress adaptation, cellular homeostasis, and the maintenance of normal cell metabolism in chickens. The adverse effects of HS on chickens include oxidative stress and compromised immune systems, making them more susceptible to infections. So also, HS negatively affects production performance and meat quality in poultry. Understanding the functions of HSPs in chickens offers valuable insights into stress adaptation and health, and could potentially lead to the identification of HSP biomarkers, genetic selection for heat tolerance, investigations into the interplay between HSPs and immune function, and the development of nutritional interventions to enhance HSP activity. By exploring these potential research directions, the review aimed to contribute to the development of novel approaches to mitigate the negative effects of HS on poultry, ultimately improving productivity and animal welfare in a changing climate.

Extracellular heat shock protein 70 levels in tumour-bearing dogs and cats treated with radiation therapy and hyperthermia

Hyperthermia is a form of a cancer treatment which is frequently applied in combination with radiotherapy (RT) to improve therapy responses and radiosensitivity. The mode of action of hyperthermia is multifactorial; the one hand by altering the amount of the blood circulation in the treated tissue, on the other hand by modulating molecular pathways involved in cell survival processes and immunogenic interactions. One of the most dominant proteins induced by hyperthermia is the major stress-inducible heat shock protein 70 (Hsp70). Hsp70 can be found in the blood either as a free-protein (free HSP70) derived from necrotic cells, or lipid-bound (liposomal Hsp70) when it is actively released in extracellular vesicles (EVs) by living cells. The aim of the study was to evaluate the levels of free and liposomal Hsp70 before and after treatment with RT alone or hyperthermia combined with radiotherapy (HTRT) in dogs and cats to evaluate therapy responses. Peripheral blood was collected from feline and canine patients before and at 2, 4, 6 and 24 h after treatment with RT or HTRT. Hsp70 enzyme-linked immunosorbent assays (ELISAs) were performed to determine the free and liposomal Hsp70 concentrations in the serum. The levels were analysed after the first fraction of radiation to study immediate effects and after all applied fractions to study cumulative effects. The levels of free and liposomal Hsp70 levels in the circulation were not affected by the first singular treatment and cumulative effects of RT in cats however, after finalizing all treatment cycles with HTRT free and liposomal Hsp70 levels significantly increased. In dogs, HTRT, but not treatment with RT alone, significantly affected liposomal Hsp70 levels during the first fraction. Free Hsp70 levels were significantly increased after RT, but not HTRT, during the first fraction in dogs. In dogs, on the other hand, RT alone resulted in a significant increase in liposomal Hsp70, but HTRT did not significantly affect the liposomal Hsp70 when cumulative effects were analysed. Free Hsp70 was significantly induced in dogs after both, RT and HTRT when cumulative effects were analysed. RT and HTRT treatments differentially affect the levels of free and liposomal Hsp70 in dogs and cats. Both forms of Hsp70 could potentially be further investigated as potential liquid biopsy markers to study responses to RT and HTRT treatment in companion animals.

Heat stress adaptation in cows - Physiological responses and underlying molecular mechanisms

Heat stress is a key abiotic stressor for dairy production in the tropics which is further compounded by the ongoing climate change. Heat stress not only adversely impacts the production and welfare of dairy cows but severely impacts the economics of dairying due to production losses and increased cost of rearing. Over the years, selection has ensured development of high producing breeds, however, the thermotolerance ability of animals has been largely overlooked. In the past decade, the ill effects of climate change have made it pertinent to rethink the selection strategies to opt for climate resilient breeds, to ensure optimum production and reproduction. This has led to renewed interest in evaluation of the impacts of heat stress on cows and the underlying mechanisms that results in their acclimatization and adaptation to varied thermal ambience. The understanding of heat stress and associated responses at various level of animal is crucial to device amelioration strategies to secure optimum production and welfare of cows. With this review, an effort has been made to provide an overview on temperature humidity index as an important indicator of heat stress, general effect of heat stress in dairy cows, and impact of heat stress and subsequent response at physiological, haematological, molecular and genetic level of dairy cows.

Effect of Butyl Paraben on Oxidative Stress in the Liver of Mauremys sinensis

Butyl paraben (BuP) has been widely used as a preservative in the cosmetics, food, and medicine industries. Recently, it has become a new pollutant and has attracted much attention. In order to evaluate the toxic effect of BuP on aquatic animals, Chinese striped-neck turtles (Mauremys sinensis) were exposed to BuP solutions with different concentrations of 0, 5, 50, 500, and 5000 µg/L for 20 weeks. The results showed that with an increase in BuP concentration, the activity of antioxidant enzymes (SOD, CAT and GSH-PX) in liver decreased. The expression of key genes in the Nrf2-Keap1 signal pathways first increased and then decreased, while the expression of the HSP70 and HSP90 genes increased. In addition, the liver had an inflammatory reaction. The expression of the BAFF and IL-6 genes increased and then decreased with an increase in BuP concentration, while the expression of P50 and P65 increased significantly. Oxidative stress induced apoptosis, and the expression of pro-apoptosis genes (BAX, cytc, Caspase3 and Caspase9) increased, while the expression of the anti-apoptosis gene Bcl2 decreased. The results provide an important reference for the comprehensive ecological and health risk assessment of environmental BuP.

Physiological, haematological and electroencephalographic responses to heat stress in Katjang and Boer goats

The present study aimed to determine the effect of repeated heat stress on serum levels of cortisol (CORT), acute phase proteins (APP) and heat shock protein (HSP) 70, haematological indicators, and electroencephalographic (EEG) response in the native Katjang and exotic Boer goats. Six female Katjang (15.7 kg ± 0.68) and six female Boer (16.8 kg ± 1.16) goats aged 5 to 6 months old were exposed to 38 ± 1℃ for 8 h, and the procedure was repeated at three different weeks (weeks 1, 2 and 3). Measurements of rectal temperatures and EEG activity and collection of blood samples were conducted before heat exposure (0 h), immediately after the heat exposure (8 h), and 8 h after completion of heat exposure (16 h) (recovery period). The current results revealed that the Boer animals had significantly higher rectal temperatures (RT), haemoglobin (Hb) and packed cell volume (PCV) counts than their Kajang counterparts. There were significant breed × stage of heat treatment (SHT) × week of heat treatment (WHT) interactions for neutrophil to lymphocyte ratios (NLR). In general, the Katjang animals had elevated NLR compared to those of Boer. The Boer goats had reduced capacity to express serum HSP70 compared to their Katjang counterparts following the heat challenge at week 3. Boer goats demonstrated higher delta waves than the Katjang group, which suggested the former were more stressed following the heat exposure. Breed had a negligible effect on CORT, APP, WBC counts and backfat thickness. Our findings suggested that the Katjang breed, as measured by RT, HB and PCV count, and EEG activity, could be more tolerant to heat stress than Boer. The Katjang goats showed higher HSP70 expression than their Boer counterparts, suggesting improved thermoregulation in the former.

Molecular biomarkers for assessing the heat-adapted phenotype: a narrative scoping review

Heat acclimation/acclimatisation (HA) mitigates heat-related decrements in physical capacity and heat-illness risk and is a widely advocated countermeasure for individuals operating in hot environments. The efficacy of HA is typically quantified by assessing the thermo-physiological responses to a standard heat acclimation state test (i.e. physiological biomarkers), but this can be logistically challenging, time consuming, and expensive. A valid molecular biomarker of HA would enable evaluation of the heat-adapted state through the sampling and assessment of a biological medium. This narrative review examines candidate molecular biomarkers of HA, highlighting the poor sensitivity and specificity of these candidates and identifying the current lack of a single 'standout' biomarker. It concludes by considering the potential of multivariable approaches that provide information about a range of physiological systems, identifying a number of challenges that must be overcome to develop a valid molecular biomarker of the heat-adapted state, and highlighting future research opportunities.

Expression of HSP70 in Human Skin After Cryolipolysis Treatment

BACKGROUND

Cryolipolysis nonsurgically targets and reduces subcutaneous fat through controlled cooling of skin and underlying fatty tissue. Although skin changes after cryolipolysis treatment have been observed clinically, the mechanisms by which these occur are not well understood.

OBJECTIVES

The aim of this study was to investigate the expression of heat shock protein 70 (HSP70) in the epidermal and dermal layers of human skin following cryolipolysis treatment.

METHODS

Subjects (N = 11; average age, 41.8 years; average BMI, 29.59 kg/m2) were recruited to receive cryolipolysis treatment with a vacuum cooling cup applicator (-11°C/35 minutes) prior to abdominoplasty surgery. Treated and untreated abdominal tissue samples were harvested immediately after surgery (average follow-up, 15 days; range, 3 days to 5 weeks). Immunohistochemistry for HSP70 was performed on all samples. Slides were digitized and quantified in epidermal and dermal layers.

RESULTS

There was higher epidermal and dermal HSP70 expression in cryolipolysis-treated pre-abdominoplasty samples vs untreated samples. There was a 1.32-fold increase of HSP70 expression in the epidermis (P < .05) and a 1.92-fold increase in the dermis (P < .04) compared with untreated samples.

CONCLUSIONS

We found significant induction of HSP70 after cryolipolysis treatment in epidermal and dermal layers. HSP70 has potential therapeutic benefits and is recognized to have a role in skin protection and adaption after thermal stress. Although cryolipolysis is popular for subcutaneous fat reduction, cryolipolytic HSP induction in the skin may prove valuable for additional therapeutic applications, including skin wound healing, remodeling, rejuvenation, and photoprotection.

LEVEL OF EVIDENCE: 4

Effects of melittin on production performance, antioxidant function, immune function, heat shock protein, intestinal morphology, and cecal microbiota in heat-stressed quails

The purpose of this study was to investigate the effects of melittin on production performance, antioxidant function, immune function, heat shock protein, intestinal morphology, and cecal microbiota of heat-stressed quails. A total of 120 (30-day-old) male quails were randomly divided into 3 groups. Each group consisted of 4 replicates with 10 birds per replicate. The ambient temperature of the control group (group W) was 24°C ± 2°C. The heat stress group (group WH) and the heat stress + melittin group (group WHA2) were subjected to heat stress for 4 h from 12:00 to 16:00 every day, and the temperature was 36°C ± 2°C for 10 d. The results showed that compared with the group W, heat stress significantly decreased growth performance, serum and liver antioxidative function, immune function, intestinal villus height (VH) and villus height-to-crypt depth ratio (VH/CD), and cecal microbiota Chao and ACE index (P < 0.05). The crypt depth (CD) in the small intestine, and HSP70 and HSP90 mRNA levels in the heart, liver, spleen, and kidney were significantly increased (P < 0.05). Dietary melittin significantly increased growth performance, serum and liver antioxidative function, immune function, intestinal VH and VH/CD, and cecal microbiota Shannon index in heat-stressed quails (P < 0.05). Melittin significantly decreased small intestinal CD, and HSP70 and HSP90 mRNA levels in the viscera (P < 0.05). Furthermore, dietary melittin could have balanced the disorder of cecal microbiota caused by heat stress and increased the abundance and diversity of beneficial microbiota (e.g., Firmicutes were significantly increased). PICRUSt2 functional prediction revealed that most of the KEGG pathways with differential abundance caused by high temperature were related to metabolism, and melittin could have restored them close to normal levels. Spearman correlation analysis showed that the beneficial intestinal bacteria Anaerotruncus, Bacteroidales_S24-7_group_norank, Lachnospiraceae_unclassified, Shuttleworthia, and Ruminococcaceae_UCG-014 increased by melittin were positively correlated with average daily feed intake, the average daily gain, serum and liver superoxide dismutase, IgG, IgA, bursa of Fabricius index, and ileum VH and VH/CD. In sum, our results demonstrate for the first time that dietary melittin could improve the adverse effects of heat stress on antioxidant function, immune function, heat shock protein, intestinal morphology, and cecal microbiota in quails, consequently improving their production performance under heat stress.

Carbohydrate, but not fat, oxidation is reduced during moderate-intensity exercise performed in 33 vs. 18 °C at matched heart rates

PURPOSE

Exposure to environmental heat stress increases carbohydrate oxidation and extracellular heat shock protein 70 (HSP70) concentrations during endurance exercise at matched absolute, external work rates. However, a reduction in absolute work rate typically occurs when unacclimated endurance athletes train and/or compete in hot environments. We sought to determine the effect of environmental heat stress on carbohydrate oxidation rates and plasma HSP70 expression during exercise at matched heart rates (HR).

METHODS

Ten endurance-trained, male cyclists performed two experimental trials in an acute, randomised, counterbalanced cross-over design. Each trial involved a 90-min bout of cycling exercise at 95% of the HR associated with the first ventilatory threshold in either 18 (TEMP) or 33 °C (HEAT), with ~ 60% relative humidity.

RESULTS

Mean power output (17 ± 11%, P < 0.001) and whole-body energy expenditure (14 ± 8%, P < 0.001) were significantly lower in HEAT. Whole-body carbohydrate oxidation rates were significantly lower in HEAT (19 ± 11%, P = 0.002), while fat oxidation rates were not different between-trials. The heat stress-induced reduction in carbohydrate oxidation was associated with the observed reduction in power output (r = 0.64, 95% CI, 0.01, 0.91, P = 0.05) and augmented sweat rates (r = 0.85, 95% CI, 0.49, 0.96, P = 0.002). Plasma HSP70 and adrenaline concentrations were not increased with exercise in either environment.

CONCLUSION

These data contribute to our understanding of how moderate environmental heat stress is likely to influence substrate oxidation and plasma HSP70 expression in an ecologically-valid model of endurance exercise.

Acute exercise in a hot environment increases heat shock protein 70 and peroxisome proliferator-activated receptor γ coactivator 1α mRNA in Thoroughbred horse skeletal muscle

Heat acclimatization or acclimation training in horses is practiced to reduce physiological strain and improve exercise performance in the heat, which can involve metabolic improvement in skeletal muscle. However, there is limited information concerning the acute signaling responses of equine skeletal muscle after exercise in a hot environment. The purpose of this study was to investigate the hypothesis that exercise in hot conditions induces greater changes in heat shock proteins and mitochondrial-related signaling in equine skeletal muscle compared with exercise in cool conditions. Fifteen trained Thoroughbred horses [4.6 ± 0.4 (mean ± SE) years old; 503 ± 14 kg] were assigned to perform a treadmill exercise test in cool conditions [COOL; Wet Bulb Globe Temperature (WBGT), 12.5°C; n = 8] or hot conditions (HOT; WBGT, 29.5°C; n = 7) consisting of walking at 1.7 m/s for 1 min, trotting at 4 m/s for 5 min, and cantering at 7 m/s for 2 min and at 90% of VO2max for 2 min, followed by walking at 1.7 m/s for 20 min. Heart rate during exercise and plasma lactate concentration immediately after exercise were measured. Biopsy samples were obtained from the middle gluteal muscle before and at 4 h after exercise, and relative quantitative analysis of mRNA expression using real-time RT-PCR was performed. Data were analyzed with using mixed models. There were no significant differences between the two groups in peak heart rate (COOL, 213 ± 3 bpm; HOT, 214 ± 4 bpm; p = 0.782) and plasma lactate concentration (COOL, 13.1 ± 1.4 mmoL/L; HOT, 17.5 ± 1.7 mmoL/L; p = 0.060), while HSP-70 (COOL, 1.9-fold, p = 0.207; HOT, 2.4-fold, p = 0.045), PGC-1α (COOL, 3.8-fold, p = 0.424; HOT, 8.4-fold, p = 0.010), HIF-1α (COOL, 1.6-fold, p = 0.315; HOT, 2.2-fold, p = 0.018) and PDK4 (COOL, 7.6-fold, p = 0.412; HOT, 14.1-fold, p = 0.047) mRNA increased significantly only in HOT at 4 h after exercise. These data indicate that acute exercise in a hot environment facilitates protective response to heat stress (HSP-70), mitochondrial biogenesis (PGC-1α and HIF-1α) and fatty acid oxidation (PDK4).

Impact of Heat Stress on Blood, Production, and Physiological Indicators in Heat-Tolerant and Heat-Sensitive Dairy Cows

Heat stress affects production and health in cows severely. Since it is difficult to define heat-tolerant animals, studies of response to heat stress are important for understanding dairy cows' health and production. However, information on the impact of heat stress on various indicators in heat-tolerant and heat-sensitive cows is sparse. This study aimed to investigate the effects of heat stress (HS) on blood, production, and physiological indicators in heat-tolerant and heat-sensitive cows. A total of 43 dairy cows were used from 9 May to 7 August 2021, under Temperature-Humidity Index (THI) measurements that ranged from 65.9 to 86.7. We identified cows that were tolerant or sensitive to HS based on the slope of the response of physiological and production traits against THI during the HS period by using a clustering method. After HS, serum glucose (Glu), cortisol (COR), 5-hydroxytryptamine (5-HT), and interleukin-6 (IL-6) levels of cows in the heat-tolerant group were lower than in the heat-sensitive group (p < 0.05). With THI as the predictor, the R2 for predicting respiration rate (RR) and body surface temperature (BT) in heat-tolerant cows was 0.15 and 0.16, respectively, whereas the R2 for predicting RR and BT in heat-sensitive cows was 0.19 and 0.18, respectively. There were low to moderate, positive correlations between RR, BT, and MY with THI, with Pearson correlation coefficients ranging from r = 0.11 to 0.4 in the heat-tolerant group, and from r = 0.24 to 0.43 in the heat-sensitive group. There was a low positive correlation between VT and THI, with a Spearman correlation coefficient of r = 0.07 in the heat-sensitive group. The heat-tolerant dairy cows had lower MY losses and had lower MY (p = 0.0007) in mixed models. Heat-tolerant cows with low-stress levels, through upregulating RR rapidly, increased their adaptability to thermal environments. They have better thermoregulation capability; the hypothalamic-pituitary-adrenal (HPA) axis regulated the thermoregulatory in animals by releasing a variety of neurotransmitters and hormones.

Effects of different stocking densities on organ development, blood biochemical indices, and antioxidative status of breeder pigeons during the rearing period

The present experiment was conducted to investigate the effect of different stocking densities on the organ development, blood biochemical indices, and antioxidative status of breeder pigeons during the rearing period. A total of 280 (half male and half female) 40-day-old young pigeons were allocated into 4 groups, including 3 experimental groups (in compartments of the flying room): the high stocking density (HSD) (0.308 m3/bird), standard stocking density (SD) (0.616 m3/bird), and low stocking density (LSD) (1.232 m3/bird) and a caged control (0.04125 m3/bird). The results showed that the contents of corticosterone and heat shock protein 70 in males and the corticosterone content in females were higher in the control than in the other groups. The relative weight of liver, lung, and gizzard in males of the HSD group was the highest among the 4 treatments, whereas the abdominal fat index in the control group was higher than those in the other 3 treatments. Body weight and the relative weight of liver and abdominal fat in female pigeons in HSD group increased significantly. The levels of serum urea nitrogen and uric acid in pigeons of LSD group increased significantly, while the concentration of total cholesterol and the activity of alanine aminotransferase were higher in the control group. Ion (K+, Ca2+, and Na+) concentrations in female pigeon serum were also elevated in the control. The activity of antioxidant enzymes, including the total antioxidant capacity, superoxide dismutase, and glutathione peroxidase in pigeon breast muscle and liver had different degrees of inhibition when the space room was crowded. Moreover, the level of malondialdehyde in the liver of male caged pigeons was higher than that in the other treatments. In summary, rearing in cages or at a high density caused stress responses in the breeder pigeons. The stocking density of breeder pigeons during the rearing period should be ranged from 0.616 m3/bird to 1.232 m3/bird.

Surviving high temperatures: a case study of the spotted munia (Lonchura punctulata)

Every year, a combination of summer with extreme weather events such as "heatwaves" affects the life of organisms on earth. Previous studies on humans, rodents, and some birds signify the impact of heat stress on their survival and existence. Over the past four decades, the frequency of heatwaves has increased because of global warming. Therefore, we performed a longitudinal study on a resident bird species, the spotted munia (Lonchura punctulata) by simulating a heatwave-like condition. We were interested in understanding how a Passeriformes native to a sub-tropical country deals with heatwave-like conditions. Initially, the birds were subjected to room temperature (25 ± 2 °C; T1) for 10 days, followed by a simulated heatwave-like condition (42 ± 1 °C; T2) for 7 days and again back to room temperature (25 ± 2 °C; RT1) for the next 7 days. To elucidate how birds cope with simulated heatwave conditions, we examined different behavioral and physiological parameters. We found that although heat stress significantly reduced total activity counts and food intake but, the body mass, blood glucose, and hemoglobin levels remained unaffected by any of the temperature conditions. Furthermore, HSP70 and biochemical markers of liver injuries such as ALP, AST, ALT, bilirubin direct, and bilirubin total were found elevated in response to the simulated heatwave-like condition, whereas uric acid and triglyceride were reduced. Creatinine and total protein levels were unaffected by the heatwave. The post heatwave treatment resulted in a rebound of the behavioral and physiological responses, but the recovered responses were not equivalent to the pre-heatwave levels (T1 conditions). Thus, the present study demonstrates heatwave-associated behavioral and physiological changes in a resident passerine finch which has tremendous physiological flexibility.

New Insights into the Role and Therapeutic Potential of Heat Shock Protein 70 in Bovine Viral Diarrhea Virus Infection

Bovine viral diarrhea virus (BVDV), a positive-strand RNA virus of the genus Pestivirus in the Flaviviridae family, is the causative agent of bovine viral diarrhea-mucosal disease (BVD-MD). BVDV's unique virion structure, genome, and replication mechanism in the Flaviviridae family render it a useful alternative model for evaluating the effectiveness of antiviral drugs used against the hepatitis C virus (HCV). As one of the most abundant and typical heat shock proteins, HSP70 plays an important role in viral infection caused by the family Flaviviridae and is considered a logical target of viral regulation in the context of immune escape. However, the mechanism of HSP70 in BVDV infection and the latest insights have not been reported in sufficient detail. In this review, we focus on the role and mechanisms of HSP70 in BVDV-infected animals/cells to further explore the possibility of targeting this protein for antiviral therapy during viral infection.

Combining hypoxia with thermal stimuli in humans: physiological responses and potential sex differences

Increasing prevalence of native lowlanders sojourning to high altitudes (>2,500 m) for recreational, occupational, military, and competitive reasons has generated increased interest in physiological responses to multistressor environments. Exposure to hypoxia poses recognized physiological challenges that are amplified during exercise and further complicated by environments that might include combinations of heat, cold, and high altitude. There is a sparsity of data examining integrated responses in varied combinations of environmental conditions, with even less known about potential sex differences. How this translates into performance, occupational, and health outcomes requires further investigation. Acute hypoxic exposure decreases arterial oxygen saturation, resulting in a reflex hypoxic ventilatory response and sympathoexcitation causing an increase in heart rate, myocardial contractility, and arterial blood pressure, to compensate for the decreased arterial oxygen saturation. Acute altitude exposure impairs exercise performance, for example, reduced time to exhaustion and slower time trials, largely owing to impairments in pulmonary gas exchange and peripheral delivery resulting in reduced V̇o2max. This exacerbates with increasing altitude, as does the risk of developing acute mountain sickness and more serious altitude-related illnesses, but modulation of those risks with additional stressors is unclear. This review aims to summarize and evaluate current literature regarding cardiovascular, autonomic, and thermoregulatory responses to acute hypoxia, and how these may be affected by simultaneous thermal environmental challenges. There is minimal available information regarding sex as a biological variable in integrative responses to hypoxia or multistressor environments; we highlight these areas as current knowledge gaps and the need for future research.

Multi biomarker approach to assess manganese and manganese nanoparticles toxicity in Pangasianodon hypophthalmus

Manganese (Mn) is an essential element for humans and animals including, fish. It is a still poorly studied in aquatic organisms, where it can be noticeably useful for dietary components and also found pollutant in aquatic environment at high concentrations. On the above information, an experiment was delineated to determine the lethal concentration of manganese (Mn) and manganese nanoparticles (Mn-NPs) alone and with high temperature (34 °C) and its effect on various biochemical markers in Pangasianodon hypophthalmus. The median lethal concentration (96-LC₅₀) of Mn alone (111.75 mg L^-1) and along with high temperature (110.76 mg L^-1), Mn-NPs alone (93.81 mg L^-1) and with high temperature (34 °C) (92.39 mg L^-1) was determined in P. hypophthalmus. The length and weight of the fish were 6.32 ± 0.23 cm and 7.57 ± 1.35 g. The present investigation used five hundred forty-six fish, including range finding (216 fish) and definitive test (330 fish). The acute definitive doses were applied to assess the effect of oxidative stress, glycolytic biomarkers, protein biomarkers, fish immunity, neurotransmitter, energy level, stress hormone and histopathology. Oxidative stress (catalase, superoxide dismutase, glutathione-s-transferase and glutathione peroxidase), stress biomarkers (lipid peroxidation, cortisol, heat shock protein, and blood glucose), lactate and malate dehydrogenase, alanine and aspartate aminotransferase, a neurotransmitter, glucose-6-phosphate dehydrogenase (G6PDH), ATPase, immune system biomarkers (NBT, total protein, albumin, globulin and A:G ratio) were altered with exposure to Mn and Mn-NPs. The histopathology of the liver and gill were also changed due to exposure to Mn and Mn-NPs. The bioaccumulation of Mn in the liver, gill, kidney, brain and muscle tissues, and experimental water at different intervals of 24, 48, 72 and 96 h were determined. Based on the present results, it is strongly suggested that Mn and Mn-NPs exposure alone and with high temperature (34 °C) enhanced toxicity and altered biochemical and morphological attributes. This study also suggested that essential elements in both forms (inorganic and nano) at higher concentrations of Mn and Mn-NPs lead to pronounced deleterious alteration in cellular and metabolic activities and histopathology of P. hypophthalmus.

Ranavirus infection does not reduce heat tolerance in a larval amphibian

Extreme heat events and emerging infectious diseases negatively impact wildlife populations, but the interacting effects of infection and host heat tolerance remain understudied. The few studies covering this subject have demonstrated that pathogens lower the heat tolerance of their hosts, which places infected hosts at a greater risk experiencing lethal heat stress. Here, we studied how ranavirus infection influenced heat tolerance in larval wood frogs (Lithobates sylvaticus). In line with similar studies, we predicted the elevated costs of ranavirus infection would lower heat tolerance, measured as critical thermal maximum (CT_max), compared to uninfected controls. Ranavirus infection did not reduce CT_max and there was a positive relationship between CT_max and viral loads. Our results demonstrate that ranavirus-infected wood frog larvae had no loss in heat tolerance compared to uninfected larvae, even at viral loads associated with high mortality rates, which contradicts the common pattern for other pathogenic infections in ectotherms. Larval anurans may prioritize maintenance of their CT_max when infected with ranavirus to promote selection of warmer temperatures during behavioral fever that can improve pathogen clearance. Our study represents the first to examine the effect of ranavirus infection on host heat tolerance, and because no decline in CT_max was observed, this suggests that infected hosts would not be under greater risk of heat stress.

Cellular Mechanisms Mediating Exercise-Induced Protection against Cardiotoxic Anthracycline Cancer Therapy

Anthracyclines such as doxorubicin are widely used chemotherapy drugs. A common side effect of anthracycline therapy is cardiotoxicity, which can compromise heart function and lead to dilated cardiomyopathy and heart failure. Dexrazoxane and heart failure medications (i.e., beta blockers and drugs targeting the renin-angiotensin system) are prescribed for the primary prevention of cancer therapy-related cardiotoxicity and for the management of cardiac dysfunction and symptoms if they arise during chemotherapy. However, there is a clear need for new therapies to combat the cardiotoxic effects of cancer drugs. Exercise is a cardioprotective stimulus that has recently been shown to improve heart function and prevent functional disability in breast cancer patients undergoing anthracycline chemotherapy. Evidence from preclinical studies supports the use of exercise training to prevent or attenuate the damaging effects of anthracyclines on the cardiovascular system. In this review, we summarise findings from experimental models which provide insight into cellular mechanisms by which exercise may protect the heart from anthracycline-mediated damage, and identify knowledge gaps that require further investigation. Improved understanding of the mechanisms by which exercise protects the heart from anthracyclines may lead to the development of novel therapies to treat cancer therapy-related cardiotoxicity.

Behavioural changes in slime moulds over time

Changes in behaviour over the lifetime of single-cell organisms have primarily been investigated in response to environmental stressors. However, growing evidence suggests that unicellular organisms undergo behavioural changes throughout their lifetime independently of the external environment. Here we studied how behavioural performances across different tasks vary with age in the acellular slime mould Physarum polycephalum. We tested slime moulds aged from 1 week to 100 weeks. First, we showed that migration speed decreases with age in favourable and adverse environments. Second, we showed that decision making and learning abilities do not deteriorate with age. Third, we revealed that old slime moulds can recover temporarily their behavioural performances if they go throughout a dormant stage or if they fuse with a young congener. Last, we observed the response of slime mould facing a choice between cues released by clone mates of different age. We found that both old and young slime moulds are attracted preferentially toward cues left by young slime moulds. Although many studies have studied behaviour in unicellular organisms, few have taken the step of looking for changes in behaviour over the lifetime of individuals. This study extends our knowledge of the behavioural plasticity of single-celled organisms and establishes slime moulds as a promising model to investigate the effect of ageing on behaviour at the cellular level. This article is part of a discussion meeting issue 'Collective behaviour through time'.

ACD-containing chaperones reveal the divergent thermo-tolerance in penaeid shrimp

The α-crystallin domain-containing (ACD-containing) gene family, which includes typical small heat shock proteins (sHSPs), is the most ubiquitous and diverse family of putative chaperones in all organisms, including eukaryotes and prokaryotes. In the present study, approximately 54-117 ACD-containing genes were identified in five penaeid shrimp species, yielding a significant expansion in comparison with other crustaceans (generally 6-20 ACD-containing genes). Unlike typical sHSPs, which contain a single ACD domain, the ACD-containing genes of penaeid shrimp contain additional ACD domains (3-7 domains, in general), thus having a larger molecular weight and a more complex 3D structure. As indicated by the RNA-seq and qRT-PCR results, the ACD-containing genes of penaeid shrimp showed a strong response to high temperatures. Furthermore, heterologous expression and citrate synthase assays of three representative ACD-containing genes confirmed that their chaperone activity could enhance the thermo-tolerance of E. coli and prevent the aggregation of substrate proteins at high temperatures. Compared with penaeid shrimp species with a relatively low thermo-tolerance (Fenneropenaeus chinensis and Marsupenaeus japonicus), the species with high thermo-tolerance (Litopenaeus vannamei and Fenneropenaeus indicus) contained more ACD-containing genes due to tandem duplication and exhibited biased expression levels under high temperatures. This can explain the divergent thermo-tolerance of different penaeid shrimp species. In conclusion, the ACD-containing genes in penaeid shrimp could be assigned as new chaperones and contribute to their divergent thermo-tolerance phenotypes and adaptations to the ecological environment.

Genetic studies of heat stress regulation in goat during hot climatic condition

Various direct and indirect environmental constraints have an impact on livestock performance. The physiological parameters, such as rectal temperature, heart rate, and respiratory rate, are the primary indicators of thermal stress. Under a stressed environment temperature humidity index (THI) had established as a vital measurement to identify the thermal stress in livestock. THI in association with climatic variations can define the environmental effect as stressful or comfortable for livestock. Goats are small ruminants that adapt to a wide range of ecological variations due to their anatomical and physiological characteristics. However, the productivity of animals declines at the individual level during thermal stress. Stress tolerance can be determined through genetic studies associated with at the cellular level using physiological as well as molecular approaches. Information on genetic association with thermal stress in goats is scanty, this severely affects their survival and hence productivity of livestock. The ever-increasing demand for food across the globe needs deciphering novel molecular markers as well as stress indicators that play a vital role in livestock improvement. This review represents an analysis of current knowledge of phenotypic differences during thermal stress and signifies the importance of physiological responses and their association at the cellular level in goats. The regulation of vital genes associated with thermal stress such as Aquaporins (AQP 0, 1, 2, 4, 5, 6, 8), aquaglyceroporins (AQP3, 7, 9, and 10) and super-aquaporins (AQP 11, 12); BAX inhibitors such as PERK (PKR like ER kinase), IRE 1(inositol-requiring-1); Redox regulating genes such as NOX; Transport of Na+ and K+ such as ATPase (ATP1A1) and several heat shock proteins have been implicated in heat-stress related adaptations have been elucidated. As these changes have a significant impact on production performance as well as on livestock productivity. Such efforts may help in the development of molecular markers and will assist the breeders to develop heat-tolerant goats with improved productivity.

Shear stress induces monocyte/macrophage-mediated inflammation by upregulating cell-surface expression of heat shock proteins

The loss of endothelial cells is associated with the accumulation of monocytes/macrophages underneath the surface of the arteries, where cells are prone to mechanical stimulation, such as shear stress. However, the impact of mechanical stimuli on monocytic cells remains unclear. To assess whether mechanical stress affects monocytic cell function, we examined the expression of inflammatory molecules and surface proteins, whose levels changed following shear stress in human THP-1 cells. Shear stress increased the inflammatory chemokine CCL2, which enhanced the migration of monocytic cells and tumor necrosis factor (TNF)-α and interleukin (IL)- 1β at transcriptional and protein levels. We identified that the surface levels of heat shock protein 70 (HSP70), HSP90, and HSP105 increased using mass spectrometry-based proteomics, which was confirmed by western blot analysis, flow cytometry, and immunofluorescence. Treatment with HSP70/HSP105 and HSP90 inhibitors suppressed the expression and secretion of CCL2 and monocytic cell migration, suggesting an association between HSPs and inflammatory responses. We also demonstrated the coexistence and colocalization of increased HSP90 immunoreactivity and CD68 positive cells in atherosclerotic plaques of ApoE deficient mice fed a high-fat diet and human femoral artery endarterectomy specimens. These results suggest that monocytes/macrophages affected by shear stress polarize to a pro-inflammatory phenotype and increase surface protein levels involved in inflammatory responses. The regulation of the abovementioned HSPs upregulated on the monocytes/macrophages surface may serve as a novel therapeutic target for inflammation due to shear stress.