Long-term Stress Research Articles

Dissecting the effect of heat stress on durum wheat under field conditions.

Heat stress negatively affects wheat production in several ways, mainly by reducing growth rate, photosynthetic capacity and reducing spike fertility. Modeling stress response means analyzing simultaneous relationships among traits affecting the whole plant response and determinants of grain yield. The aim of this study was to dissect the diverse impacts of heat stress on key yield traits and to identify the most promising sources of alleles for heat tolerance. We evaluated a diverse durum wheat panel of 183 cultivars and breeding lines from worldwide, for their response to long-term heat stress under field conditions (HS) with respect to non stress conditions (NS), considering phenological traits, grain yield (GY) and its components as a function of the timing of heat stress and climatic covariates. We investigated the relationships among plant and environmental variables by means of a structural equation model (SEM) and Genetic SEM (GSEM). Over two years of experiments at CENEB, CIMMYT, the effects of HS were particularly pronounced for the normalized difference vegetation index, NDVI (-51.3%), kernel weight per spike, KWS (-40.5%), grain filling period, GFP (-38.7%), and GY (-56.6%). Average temperatures around anthesis were negatively correlated with GY, thousand kernel weight TKW and test weight TWT, but also with spike density, a trait determined before heading/anthesis. Under HS, the correlation between the three major determinants of GY, i.e., fertile spike density, spike fertility and kernel size, were of noticeable magnitude. NDVI measured at medium milk-soft dough stage under HS was correlated with both spike fertility and grain weight while under NS it was less predictive of grain weight but still highly correlated with spike fertility. GSEM modeling suggested that the causal model of performance under HS directly involves genetic effects on GY, NDVI, KWS and HD. We identified consistently suitable sources of genetic resistance to heat stress to be used in different durum wheat pre-breeding programs. Among those, Desert Durums and CIMMYT'80 germplasm showed the highest degree of adaptation and capacity to yield under high temperatures and can be considered as a valuable source of alleles for adaptation to breed new HS resilient cultivars.

Handling the Challenges of Small-Scale Labeled Data and Class Imbalances in Classifying the N and K Statuses of Rubber Leaves Using Hyperspectroscopy Techniques.

The nutritional status of rubber trees (Hevea brasiliensis) is inseparable from the production of natural rubber. Nitrogen (N) and potassium (K) levels in rubber leaves are 2 crucial criteria that reflect the nutritional status of the rubber tree. Advanced hyperspectral technology can evaluate N and K statuses in leaves rapidly. However, high bias and uncertain results will be generated when using a small size and imbalance dataset to train a spectral estimaion model. A typical solution of laborious long-term nutrient stress and high-intensive data collection deviates from rapid and flexible advantages of hyperspectral tech. Therefore, a less intensive and streamlined method, remining information from hyperspectral image data, was assessed. From this new perspective, a semisupervised learning (SSL) method and resampling techniques were employed for generating pseudo-labeling data and class rebalancing. Subsequently, a 5-classification spectral model of the N and K statuses of rubber leaves was established. The SSL model based on random forest classifiers and mean sampling techniques yielded optimal classification results both on imbalance/balance dataset (weighted average precision 67.8/78.6%, macro averaged precision 61.2/74.4%, and weighted recall 65.7/78.5% for the N status). All data and code could be viewed on the:Github https://github.com/WeehowTang/SSL-rebalancingtest. Ultimately, we proposed an efficient way to rapidly and accurately monitor the N and K levels in rubber leaves, especially in the scenario of small annotation and imbalance categories ratios.

Effective Recreational Activities in Urban Green Spaces for Mental Health of Scientific Researchers

Scientific researchers are known for their demanding intellectual efforts and are particularly susceptible to mental health disorders. Urban green spaces (UGSs) are beneficial for people’s mental health, yet there is limited research on what types of UGSs and activities are effective for improving researchers’ mental health. Here, we investigate if researchers’ mental health can be enhanced by visiting affiliated green spaces, pocket parks, comprehensive parks, and coastal beaches. The research hypothesis was that the natural and social pathways of recreational ecosystem services jointly reduce researchers’ mental stress and attentional fatigue. The results suggest that nature contact, nature connectedness, and social interaction directly or indirectly have positive impacts on scientific researchers’ mental health. Both nature connectedness and social interaction serve as crucial mediating variables between nature contact and mental health. In terms of direct impact, high-frequency recreational activities in small UGSs with high accessibility, markedly relieve stress, whereas visit frequency in large UGSs with low accessibility has a limited effect on long-term mental stress relief. In terms of indirect impact, small UGSs alleviate attentional fatigue through the mediation of nature connectedness, while large UGSs mainly mitigate mental stress and attentional fatigue through the mediation of social interaction. This study provides a natural-social integrated perspective on recreational ecosystem services to enhance the well-being of scientific researchers. We provide recommendations for researchers to mitigate work-related stress and fatigue and to offer information useful for decision-making support to create a healthy environment for scientific researchers.

Genetic benefits of female from extra-pair paternity are context dependent within the socially monogamous Tree Sparrow

Females actively seek extra-pair paternity (EPP) to acquire a fitness advantage for their offspring. The “context-dependence hypothesis” posits that female extra-pair mate choice has plasticity in response to environmental conditions, and therefore magnitude of female genetic benefits from EPP depends on the environmental variation. Furthermore, chronic heavy metal pollution can cause adverse effects on fitness-related traits of wild birds. However, few studies were available on the interactions between heavy metal pollution and EPP. We selected an area that was contaminated by heavy metals for more than 60 years (Baiyin, BY), a relatively unpolluted area (Liujiaxia, LJX), and Tree Sparrows (Passer montanus) as study species to explore the response of female extra-pair mate choice and genetic benefits from EPP to heavy metal pollution in socially monogamous birds. The relatedness between social mates and extra-pair mates was investigated. Additionally, we compared the body size and heterozygosity of extra-pair offspring (EPO), within-pair offspring (WPO), social males and extra-pair males from the two Tree Sparrow populations. We found that at BY, female Tree Sparrows tended to choose extra-pair males with larger body size and lower genetic similarity, thereby producing higher heterozygosity and larger body size of EPO compared with those of WPO. However, no similar phenomenon was observed in the Tree Sparrow population from LJX. In addition, there was a significant interaction between population and paternity in the analyses of the fitness-related traits, suggesting that environmental variation could affect female genetic benefits from EPP. This study confirmed the existence of presumed interactions between environmental pollution and EPP within the natural population of socially monogamous Tree Sparrows. Our findings shed lights on the possible effects of long-term environmental stress on mating system in wild birds.

Tolerance variations and mechanisms of Salmonella enterica serovar Newport in response to long-term hypertonic stress

Abstract Objectives To assess the variations in hypertonic tolerance among Salmonella enterica serovar Newport (S. Newport) strains isolated from diverse sources and investigate the mechanism underlying the tolerance differences between the sensitive and tolerant strain. Materials and Methods In this work, various S. Newport strains were cultured in 5% and 10% NaCl solutions (hypertonic stress), and the most sensitive and tolerant strains were selected using a Weibull model. The regulatory mechanisms underlying the hypertonic tolerance differences of S. Newport were preliminarily investigated in the aspects of cell phenotype, intracellular solute concentration, and gene expression level. Results With prolonged hypertonic stress time, the leakage of nucleic acids and proteins of S. Newport increased gradually, and the membrane potential of S. Newport declined after increasing. Compared with the sensitive strain, the tolerant counterpart exhibited the ability to maintain the integrity of the cell membrane and sustain a high membrane potential level. The expression levels of the upstream genes proV and otsB in the tolerant strain were significantly lower than those in the sensitive strain; but the Kdp and Trk systems and downstream genes proX, proW, and otsA were highly expressed in the tolerant strain compared with the sensitive strain, leading to higher concentrations of intracellular K+ and trehalose, enabling better survival in a hypertonic environment. Conclusions The findings of this work offer valuable insights into pathogen survival mechanisms under hypertonic stress and contribute to the development of strategies for mitigating microbiological risks during long-term processing and storage in the cured food industry.

The effects of web-based progressive muscle relaxation exercise on perceived stress and anxiety levels of nursing students who were in clinical practice for the first time: A randomized controlled trial

Introduction/Objective. It is reported that during the education process, uncontrollable long-term stress affects professional identity development and health of nursing students negatively. The effects of web-based progressive muscle relaxation exercises on perceived stress and anxiety levels of nursing students who were in clinical practice for the first time were analyzed in the present study. Methods. The present study used a randomized controlled design. The study was carried out at a state university in Turkey. A total of volunteering 66 nursing students (36 in the control and 30 in the intervention group) in clinical practice for the first time who were studying during the 2021-2022 academic year were included in the sample. Intervention group students performed 36 sessions of progressive muscle relaxation exercise three days a week for 12 weeks. The data were collected by using the ?Sociodemographic Characteristics Form?, ?State-Trait Anxiety Inventory (STAI)? and ?Perceived Stress Scale (PSS)?. Results: In comparing post-test mean scores of intervention and control group, PSS and STAI total mean scores of the intervention group were found to be statistically significantly lower than those of the control group (p < 0.05). Conclusion: Progressive muscle relaxation exercise was found to reduce perceived stress and anxiety in nursing students who were in clinical practice for the first time.

Factors and mechanisms influencing seasonal disorders in pig reproduction

The problem of unsatisfactory reproductive results in pigs is visible in a significant percentage of herds, especially during summer months and early autumn (seasonal summer infertility). This is reflected mainly in the reduced percentage of sows entering estrus after weaning and the effectiveness of mating/insemination. The consequence is a significantly lower number of births in November, December and sometimes even in January, compared to other seasons. There are many causes of seasonal summer infertility. The first things mentioned are usually the length of the light day and the high temperature in the pigs environment. An important reason that is not often discussed is the daily temperature fluctuations which usually occur at the end of summer and the beginning of autumn. Persistent unfavorable conditions are responsible for long-term stress. Hormonal disorders related to stress, leading to reproductive disorders, result from connections taking place in the hypothalamus between the hypothalamus-pituitary-gonadal axis (HPG), which regulates, among others, the reproductive functions of the ovaries, and the hypothalamus – pituitary – adrenal axis – HPA which governs organism reaction to stress. Under stressful conditions, glucocorticoids (cortisol, corticosterone) secreted in large amounts by the adrenal glands, as well as adrenaline, norepinephrine and, in small amounts, dopamine, may inhibit reproductive functions at the level of the hypothalamus, reducing the secretion of GnRH. At the same time, by reaching the pituitary gland, these hormones limit the sensitivity of the cells of this endocrine gland to GnRH. As a consequence, the maturation of follicles slows down, the number of ovulating and rupturing follicles decreases, and the secretion of estrogen is reduced. The consequence is the absence of heat or, more often, the so-called “silent heat”. Another problem is the uneven maturation of the follicles, which leads to a delayed appearance of estrus and its longer duration: 3-4 days. The final effect of these is a decrease in the rate of females presenting heat after weaning of piglets, a deterioration in the mating/insemination success rate, an increase in the rate of early abortions and percentage of litters with a small number of piglets in a litter. The summary stated that despite the identification of various seasonal causes of reproductive disorders in pigs, depending on both sows and boars, and the availability of various “tools” to reduce phenomenon of seasonal infertility, the presented problem has not been solved in a large percentage of swine farms. Its intensity varies and depends primarily on awareness, knowledge of ways to eliminate unfavorable conditions and determination in this regard. The first step, as always, is to objectively assess the situation. The assessment can be made through a detailed analysis of production data.

PHYSICAL EUSTRESSORS AS POTENTIAL TOOLS TO IMPROVE CROP STRESS TOLERANCE (REVIEW)

Background. The processes occurring in plants and their seeds under stress, as well as the defense mechanisms used by plants under stress, are poorly understood, which makes it impossible to use them to increase yields.
 Purpose. Review and analysis of scientific publications, devoted to the phenomenon of stress memory acquired by plants as a result of physical stressors on their seeds and possible applications of this phenomenon in plant growing and crop breeding.
 Materials and methods. A selection and systematic review of scientific articles on the research topic for the period 2016-2023 was performed. The study consisted of the following steps: research literature search, evaluation and selection, data synthesis and analysis.
 Results. The use of hormetic effects of physical agents to stimulate seed germination of crops is effective. Responses to abiotic stresses could be 'trained' by priming so that the plant becomes better able to cope with later stress. Evidence of short-term and transgenerational memory formation following plant priming has been obtained. An epigenetic mechanism for the formation of long-term stress memory in plants as a result of a physical eustressor has been identified. The eustressor induces specific epigenetic marks associated with environmental adaptation, forming a new stress-resistant plant phenotype. Physical eustressors have the potential to impart stress tolerance to crops to enhance phenotypic characteristics to prevent yield losses.
 Conclusion. Seed treatment with physical stressors builds plant tolerance and memory to abiotic stresses, but scientific evidence on this issue is incomplete and sketchy. The understanding and application of stress memory for breeding purposes is currently limited, but it has great potential for the development of new crop varieties.

BAG2 and MAPK2 regulate differently on different periods of heat-induced programmed cell death in tomato

High temperature is a significant abiotic stress that affects growth and development of plants. BAG (Bcl-2 associated athanogene) protein family members act as co-chaperones and apoptosis inhibitors in multiple cellular processes. BAG, MAPK (Mitogen-activated protein kinase), and programmed cell death (PCD) play critical roles in plant growth and development, stress response, and disease resistance. In this study, we investigated the interaction of BAG, and MAPK as well as their putative role in PCD under either short or long-term heat stress. We constructed mutants of bag2 and mapk2 in tomato using CRISPR/Cas9. Our results revealed that tomato BAG2 and MAPK2 interacted positively both in vivo and in vitro. In addition, after 3 h of heat stress, the activities of Caspase 3 and antioxidant enzymes, expression levels of Caspase 3 and Caspase 9, and contents of H2O2 in bag2 and mapk2 mutant plants were lower than those in WT (wild type) plants. Moreover, under short-term (3 h) heat stress, the DNA fragmentation phenomena and trypan blue coloration in both mutants were less severe than in WT plants; however, DNA integrities were broken, and the number of dead cells was higher under long-term (24 h) heat stress. Additionally, the electrolyte leakage was increased, but the Fv/Fm (maximum photochemical efficiency) value was decreased in mutants following exposure to heat stress. These results suggested that tomato BAG2 and MAPK2 suppressed short-time heat-induced PCD while promoting long-time heat-induced PCD.

RNA-seq analysis of small intestine transcriptional changes induced by starvation stress in piglets

Piglets may experience a variety of stress injuries, but the molecular regulatory mechanisms underlying these injuries are not well understood. In this study, we analysed the ileum of Large White (LW) and Mashen (MS) piglets at different times of starvation using chemical staining and transcriptome analysis. The intestinal barrier of piglets was damaged after starvation stress, but the intestinal antistress ability of MS piglets was stronger than LW piglets. A total of 8021 differentially expressed genes (DEGs) were identified in two breeds. Interestingly, the immune capacity (CHUK, TLR3) of MS piglets increased significantly after short-term starvation stress, while energy metabolism (NAGS, PLA2G12B, AGCG8) was predominant in LW piglets. After long-term starvation stress, the level of energy metabolism (PLIN5, PLA2G12B) was significantly increased in MS piglets. The expression of immune (HLA-DQB1, IGHG4, COL3A1, CD28, LAT) and disease (HSPA1B, MINPPI, ADH1C, GAL3ST1) related genes were significantly increased in two breeds of piglets. These results suggest that short-term stress mainly enhances immunity and energy metabolism in piglets, while long-term starvation produces greater stress on piglets, making it difficult for them to compensate for the damage to their bodies through self-regulation. This information can help improve the stress resistance of piglets through molecular breeding.

Material properties in regenerating axolotl limbs using inverse finite element analysis

BackgroundThe extracellular mechanical environment plays an important role in the skeletal development process. Characterization of the material properties of regenerating tissues that recapitulate development, provides insights into the mechanical environment experienced by the cells and the maturation of the matrix. In this study, we estimated the viscoelastic material properties of regenerating forelimbs in the axolotl (Ambystoma mexicanum) at three different regeneration stages: 27 days post-amputation (mid-late bud) and 41 days post-amputation (palette stage), and fully-grown time points. A stress-relaxation indentation test followed by two-term Prony series viscoelastic inverse finite element analysis was used to obtain material parameters. Glycosaminoglycan (GAG) content was estimated using a 1,9- dimethyl methylene blue assay. ResultsThe instantaneous and equilibrium shear moduli significantly increased with regeneration while the short-term stress relaxation time significantly decreased with limb regeneration. The long-term stress relaxation time in the fully-grown time point was significantly lower than 27 and 41 DPA groups. The GAG content was not significantly different between 27 and 41 DPA but the GAG content of cartilage in the fully-grown group was significantly greater than in 27 and 41 DPA. ConclusionsThe mechanical environment of the proliferating cells changes drastically during limb regeneration. Understanding how the tissue's mechanical properties change during limb regeneration is critical for linking molecular-level matrix production of the cells to tissue-level behavior and mechanical signals.

A novel refined Caputo kernel and constitutive concepts for semi-exact nonlinear dynamic and creep analyses of suddenly pressurized hollow fractional-order visco-hyperelastic cylinders

Some reports have confirmed that discretizing the mass, damping, and stiffness characteristics of a continuum can result in remarkable deviations from the experimental results; as all these properties are intertwined and coupled within a single material. The viscoelastic constitutive laws with fractional-order time derivatives can model this integrity much more accurately, due to their capability of using a set of an infinite number of orders. Here, an innovative constitutive model with a nonlinear hyperelastic memory element that treats simultaneously the fractional-order viscoelasticity and Mooney-Rivlin hyperelasticity of the continuum is proposed to track the suppression of the short-term dynamic stresses and displacements and the redistribution of the long-term creep stress and deformations of the suddenly pressurized thick cylinders. While the spatial variations of the quantities of the incompressible cylinder are treated by an exact analytical approach, the resulting time-dependent system of equations is converted by a novel numerical solution scheme to an integrodifferential system that contains integer-order partial derivatives and a time-growing number of integral terms. An enhancement to Caputo's singular-kernel integral definition of the fractional-order derivatives is proposed here to replace these derivatives with equivalent integrals whose integer derivatives are computed based on second-order Taylor's expansion. The integer-order and fractional-order time derivatives are then computed numerically using the second-order Runge-Kutta and accumulation-based trapezoidal techniques, respectively. Finally, comparisons are made among the dissipative pattern and time variations of the dynamic/vibration stresses and large-deformations of the hyperelastic and fractional-order visco-hyperelastic cylinders in addition to the assessment of the effects of the constitutive parameters of the fractional-order model. Results show that while the larger magnitudes of both the nonlinear viscosity coefficients and fractional-order time derivatives diminish the resulting deformations and stresses, they respectively lead to smaller and larger frequencies of oscillation.

Chronic Stress Blocks the Endometriosis Immune Response by Metabolic Reprogramming.

Studies have shown that the occurrence and development of endometriosis are closely linked to long-term psychological stress. The specific contribution of chronic stress to the metabolic adaptations in patients with endometriosis is still unknown. Lesions were removed from ten endometriosis patients during an operation, and the participants were divided into two groups using a psychological questionnaire. An mRNA Human Gene Expression Microarray analysis was applied to compare the mRNA expression profiles between the chronic stress group and the control group. In addition, the reliability of the mRNA Human Gene Expression Microarray analysis was verified by using research on metabolites based on both the liquid chromatography (LC-MS/MS) technique and quantitative reverse transcription polymerase chain reaction (RT-PCR). A microarray analysis of significantly up-regulated, differentially expressed genes between the chronic stress and the control groups showed genes that were principally related to metabolism-related processes and immune-related processes, such as the immune response process, negative regulation of T cell proliferation, the leucine metabolic process, and the L-cysteine metabolic process (p < 0.05). LC-MS showed that the differential metabolites were primarily concerned with arginine and proline metabolism, D-glutamine and D-glutamate metabolism, aspartate metabolism, glycine, serine metabolism, and tyrosine metabolism (p < 0.05). The possibility of chronic stress blocks the endometriosis immune response through metabolic reprogramming. Chronic stress reduces the supply of energy substrates such as arginine and serine, down-regulates T immune cell activation, and affects the anti-tumor immune response, thereby promoting the migration and invasion of endometriosis lesions in patients with chronic stress.

Inflammation in the pathogenesis of neurodegenerative diseases

INTRODUCTION: Neurodegenerative diseases are common chronic disorders that are associated with progressive damage to the nervous system. The role of the immune system in the development of neurodegenerative diseases was confirmed by data on the activation of microglia, the presence of an imbalance in the composition and phenotype of peripheral immune cells, and the presence of humoral immunity disorders and intestinal microbiota dysbiosis in patients with this pathology. DISCUSSION: Inflammation has been observed to play a key role in the pathogenesis of diseases associated with progressive damage to the nervous system. The article analyzes the mechanisms in the development of “subclinical” chronic inflammation that leads to development of old-age-related diseases, including neurodegenerative pathology. At least three groups of factors associated with old age play a role in the formation of a proinflammatory status: mitochondrial dysfunction, development of an age-related proinflammatory status of the immune system, and chronic stress. Mitochondrial dysfunction is primarily associated with disruption of mitophagy processes: failure of quality control mechanisms as a result of disruption of mitophagy processes leads to the accumulation of terminally damaged mitochondria, which become a threat to cell survival. Inadequate removal of damaged mitochondria leads to hyperactivation of inflammatory signaling pathways and subsequently to chronic systemic inflammation and the development of inflammatory diseases. A high level of deletions in the mitochondrial genetic apparatus that accumulates with age inevitably leads to increased formation of reactive oxygen species, which in turn are assumed as one of the leading activators of the cytosolic NLRP3 protein, the primary component of inflammasomes. Increased inflammasome formation eventually leads to caspase-1-dependent production of proinflammatory interleukins. Age-related inflammatory imbalance is associated with the fact that the immune system, the main protective mechanism characterized by the inflammatory response, copes with constant antigenic attacks. However, over time, upon reaching a certain threshold, the reaction of the immune system becomes excessive, characterized by increased production of coagulation factors, proinflammatory cytokines, acute phase proteins of inflammation, prostaglandins, and leukotrienes. CONCLUSIONS: Immunological changes that develop during chronic (long-term) stress are the result of a disruption of the homeostatic connection between the neuroendocrine and immune systems, leading to the formation of an inflammatory background that complements the “proinflammatory status” that develops as a result of age-related changes in the immune system and disruption of mitophagy mechanisms.

Post-stress expression of genes involved in neuroplasticity in the hippocampus and blood of rats with different level of nervous system excitability

The causes and mechanisms of most mental disorders remain unclear. While stress is known to trigger depressive and anxiety disorders, the role of genetically determined individual differences in forming vulnerability to post-stress neurochemical disorders, including those that affect neuroplasticity, remains unresolved. Early studies suggest that acute and chronic stress lead to elevated glucocorticoid levels in the bloodstream and alter the expression of glucocorticoid and mineralocorticoid receptors. Additionally, both forms of stress can decrease the levels of brain-derived neurotrophic factor (BDNF), which plays a role in neuronal growth, development, and synapse building [1]. However, current studies insufficiently explain the complete mechanism of the stress response as they only explore variations in post-stress alteration of gene expression for proteins related to differing nervous system functional characteristics. The strains of rats from the Biocollection of the Pavlov Institute of Physiology, RAS, are a convenient model for studying the impact of genetically determined nervous system features on stress reactivity. The strains, selected based on the threshold of nervous system excitability [2], include HT (high threshold of excitability, low excitability) and LT (low threshold of excitability, high excitability) strains. These strains display contrasting responses to extended emotional and painful stress and exhibit unique changes in brain structures implicated in emotional regulation and stress reactivity at the molecular, cellular, and epigenetic levels [2]. The aim of this study is to examine the mRNA levels of genes encoding glucocorticoid and mineralocorticoid receptors (NR3C1, NR3C2) and brain-derived neurotrophic factor (BDNF) in the hippocampus and blood of rat strains that exhibit contrasting nervous system excitability. The study investigates interstrain variations in animals under non-stressful conditions and changes in response to prolonged exposure to emotional and painful stimuli. The experiment utilized 96 animals, with 6 animals in both the control and experimental groups at each time point. The stress model utilized was long-term emotional and painful stress as per K. Gecht [2]. The study assessed the expression of genes for glucocorticoid receptors and neurotrophic factor by isolating RNA from the hippocampus and blood of rats of two strains decapitated at 1, 7, 24, and 60 days post-stress. Gene expression analysis was conducted through real-time PCR and underwent further data processing using the ΔΔCt method. The statistical tests employed included the Kruskal–Wallis and Mann–Whitney tests. The analysis of the expression of the observed genes in intact animals demonstrates that highly excitable LT rats have a significantly lower level of expression of the nr3c2 gene, which encodes the mineralocorticoid receptor in the hippocampus, when compared to the low excitable HT strain. When studying the short-term and long-term effects of stress on the expression of the observed genes (nr3c1, nr3c2, bdnf), a decline was observed in the level of bdnf mRNA in the hippocampus of the LT strain 60 days after stress. The study suggests that the genetically determined characteristics of highly excitable animals affect the weakened adaptive abilities of their nervous system. One of the markers of this weakening is the reduced level of mRNA for the nr3c2 gene in the hippocampus under normal conditions, as well as a decrease in the expression of the bdnf gene in response to stress.

Dynamic response of immobilized microbial denitrification reactor under long-term nitrobenzene stress

Denitrification is an effective method for the synergistic degradation of nitrate and nitrobenzene. In this study, microorganisms were cultured by gradually increasing the influent nitrobenzene concentration over 115 days, achieving efficient synergistic transformation of 50 mg/L nitrobenzene and 100 mg/L nitrate with removal efficiencies of 93.65 % and 98.50 %, respectively. It was studied that electrons flowing towards nitrate accounted for over 93.72 %, with that towards nitrobenzene for less than 6.28 %. Nitrobenzene promoted the enrichment growth of biofilm, significantly increased 64.1 % of the content of polysaccharides and 32.7 % of proteins on extracellular polymeric substance. Shannon index showed that nitrobenzene increased richness of bacteria and fungi by 47.6 % and 73.4 % and the dominant phyla were Proteobacteria and Ascomycota respectively. Metagenomic analysis uncovered a noteworthy surge in gene expression associated with carbon metabolism and nitrobenzene reduction, while the expression of denitrification genes exhibited no substantial alterations, elucidating the consistent denitrification efficiency and formidable nitrobenzene elimination capability of the system.

Temporal differentiation in the adaptation of functional bacteria to low-temperature stress in partial denitrification and anammox system

Despite reliable nitrite supply through partial denitrification, the adaptation of denitrifying bacteria to low temperatures remains elusive in partial denitrification and anammox (PDA) systems. Here, temporal differentiations of the structure, activity, and relevant cold-adaptation mechanism of functional bacteria were investigated in a lab-scale PDA bioreactor at decreased temperature. Although distinct denitrifying bacteria dominated after low-temperature stress, both short- and long-term stresses exerted differential selectivity towards the species with close phylogenetic distance. Species Azonexus sp.149 showed high superiority over Azonexus sp.384 under short-term stress, and long-term stress improved the adaptation of Aquabacterium sp.93 instead of Aquabacterium sp.184. The elevated transcription of nitrite reductase genes suggested that several denitrifying bacteria (e.g., Azonexus sp.149) could compete with anammox bacteria for nitrite. Species Rivicola pingtungensis and Azonexus sp.149 could adapt through various adaptation pathways, such as the two-component system, cold shock protein (CSP), membrane alternation, and electron transport chain. By contrast, species Zoogloea sp.273 and Aquabacterium sp.93 mainly depended on the CSP and oxidative stress response. This study largely deepens our understanding of the performance deterioration in PDA systems during cold shock and provides several references for efficient adaptation to seasonal temperature fluctuation.

Stress-induced influence on the evolution of γ′ phase in dendritic area during long-term stress aging at 900 °C in Ni-based superalloy K444

The evolution of γ′ phase in the Ni-based superalloy K444 alloy is investigated after long-term aging for 5000 h (LTA5,000) at 900 °C under different stresses (0 MPa, 50 MPa, 65 MPa, 80 MPa, 100 MPa and 120 MPa). The role of applied stress in the LTA5,000 process is analyzed in detail from multiple aspects, including morphology, composition partition, the formation of TCP phase, lattice misfit (δ) and dislocations configuration. The results reveal that the stress promotes the γ′ phase directional coarsening when it exceeds the critical value. For this alloy, the rafting structure is obvious when the stress is higher than 80 MPa, while γ′ phases maintain cuboid shape when the stress is below 65 MPa. It is caused by the stress gradient in the γ channels which accelerates the γ′ forming elements diffuse from horizontal γ channels to the vertical channels and only sufficient stress can activate the directional diffusion behavior. Besides, the stress induces that Al and Ti strongly assign to γ′ phases and the concentration of Cr in γ matrix increases clearly. In addition, the σ-TCP is free until the applied stress raises to 120 MPa, it is attributed to the increase in Cr concentration in the γ matrix. Moreover, the value of |δ| increases as the applied stress increases, and reducing interfacial energy becomes the driving force for directional coarsening. Finally, the calculated results based on the threshold stress demonstrate that the dislocations climb over the γ′ particles within the range of 65 MPa ∼ 120 MPa, which is in agreement with the observed phenomena.

Post-stress changes in the gut microbiome composition in rats with different levels of nervous system excitability.

The gut-brain axis is a critical communication system influencing the interactions between the gastrointestinal tract (GI) and the central nervous system (CNS). The gut microbiota plays a significant role in this axis, affecting the development and function of the nervous system. Stress-induced psychopathologies, such as depression and anxiety, have been linked to the gut microbiota, but underlying mechanisms and genetic susceptibility remain unclear. In this study, we examined stress-induced changes in the gut microbiome composition in two rat strains with different levels of nervous system excitability: high threshold (HT strain) and low threshold (LT strain). Rats were exposed to long-term emotional and painful stress using the Hecht protocol, and fecal samples were collected at multiple time points before and after stress exposure. Using 16S rRNA amplicon sequencing, we assessed the qualitative and quantitative changes in the gut microbiota. Our results revealed distinct microbial diversity between the two rat strains, with the HT strain displaying higher diversity compared to the LT strain. Notably, under prolonged stress, the HT strain showed an increase in relative abundance of microorganisms from the genera Faecalibacterium and Prevotella in fecal samples. Additionally, both strains exhibited a decrease in Lactobacillus abundance following stress exposure. Our findings provide valuable insights into the impact of hereditary nervous system excitability on the gut microbiome composition under stress conditions. Understanding the gut-brain interactions in response to stress may open new avenues for comprehending stress-related psychopathologies and developing potential therapeutic interventions targeted at the gut microbiota. However, further research is needed to elucidate the exact mechanisms underlying these changes and their implications for stress-induced disorders. Overall, this study contributes to the growing body of knowledge on the gut-brain axis and its significance in stress-related neurobiology.

Nitraria sibirica adapts to long-term soil water deficit by reducing photosynthesis, stimulating antioxidant systems, and accumulating osmoregulators

Amid climate change and shifts in precipitation patterns, drought conditions are expanding worldwide. Drought stress severely threatens plant growth in arid and semi-arid regions, wherein shrubs play a crucial role in maintaining ecological stability. Despite its ecological significance, studies are lacking on how Nitraria sibirica adapts to long-term drought stress. Therefore, in this study, to elucidate the mechanism of drought stress adaptation in N. sibirica, we analysed morphological, physiological, and transcriptional characteristics of plants in two soil habitats: riparian (moist) and desert (arid). The results showed that in desert soils, as soil water content decreased, leaf thickness increased, while plant height and leaf area decreased. Physiologically, photosynthesis decreased; soluble sugar, starch, proline, and hydrogen peroxide content increased significantly; while soluble proteins decreased significantly. Additionally, membrane lipid peroxidation products and antioxidant enzyme activities significantly increased under drought stress. Then, Kyoto Encyclopaedia of Genes and Genomes (KEGG) enrichment analysis identified 313 key genes, which were considered the most significantly enriched in the photosynthesis and photosynthetic antenna protein pathways. Further, we found that the proteins encoding photosystem II (PsbP, PsbQ, PsbR, PsbY, and Psb27), photosystem I (PsaD, PsaF, PsaG, PsaH, PsaK, and PsaO), photosynthetic electron transport (PetF), and light-trapping antenna proteins were significantly downregulated under drought stress. Taken together, these results suggest that N. sibirica adapts to long-term drought conditions by suppressing photosynthesis, activating antioxidant systems, and recruiting osmoregulators. This study provides a basis for elucidating the growth mechanisms of N. sibirica under long-term drought stress conditions.