Stress Agents Research Articles

Glutathione peroxidase LtGPX3 contributes to oxidative stress tolerance, virulence, and plant defense suppression in the peach gummosis fungus Lasiodiplodia theobromae

The notorious woody plant-degrading pathogen Lasiodiplodia theobromae is a major causal agent of peach gummosis, one of the prevalent and devastating trunk diseases to peach production; however, its pathogenesis is largely unknown. Our previous study showed that L. theobromae LtGPX3, which encodes a glutathione peroxidase resembling yeast GPX3/HYR1-like, was constantly and dramatically upregulated at the infectious stages. Here, we functionally characterized LtGPX3 using the CRISPR-Cas9-aided split marker approach. The ΔLtgpx3 deletion mutants displayed increased sensitivity to the osmotic stress agent KCl and less sensitivity to the cell wall-damaging agent calcofluor white. Exogenous oxidants highly induced the expression of LtGPX3, and the ΔLtgpx3 mutants displayed increased sensitivity to ROS-generating oxidants. Pathogenicity assays revealed that ΔLtgpx3 mutants showed compromised virulence in peach shoots, which was partially restored when peach shoots were pretreated with an NADPH oxidase inhibitor before inoculation. Moreover, ROS levels were strongly boosted, and transcripts of plant defense-related genes were highly induced in the ΔLtgpx3 mutants-infected peach shoots compared with the wild-type-inoculated. Overall, our results showed the essential roles of LtGPX3 in the oxidative stress response and tolerance and pathological functions in L. theobromae. These findings deepen our understanding of the survival strategies of the woody plant-degrading pathogen L. theobromae and provide new insights into developing new strategies for peach gummosis disease control.

Role of the clinical radiopharmacist in patient safety during myocardial perfusion imaging with vasodilator stress agents

AimTo assess the radiopharmacist’s role in a multidisciplinary team focused on the contraindications of regadenoson in order to ensure the safe use of pharmacologic vasodilator stress agents in patients undergoing SPECT-MPI. MethodsWe ambispectively studied its safe use in 1905 patients (54.1% female, mean age: 66.6±11.7 years, range: 20–95 years). Sex, age, medical history, medications, drug allergies, and contraindications for stress testing were registered together with recommendations for the nuclear physician in charge. ResultsDetected contraindications and corresponding recommendations were as follows: risk factors for QTc interval prolongation 7.5% – measurement of QTc interval previously to test and monitor ECG; prior stroke or TIA 4.2% – consider carotid stenosis assessment; salicylates/sulfonamides allergy 3.1% – use 99mTc-sestamibi; epilepsy or risk factors for seizures 2.4% – use of adenosine or reconsider test indication; systemic corticosteroid therapy for severe COPD 1.3% – reassessment of patient’s condition; acute exacerbation of COPD 0.8% – defer test until acute episode is over; severe asthma 0.4% – do not perform test; methylxanthine ingestion 0.3% – avoid consumption previously; other 6.1% – evaluation of other contraindications. No contraindications were detected in 73.6% of patients. The test was canceled due to absolute contraindications in 2.9% of the requests. ConclusionsWorking in a systematic way, the radiopharmacist was able to detect a high number of issues related to regadenoson, with one out of four patients presenting some clinical contraindication. The recommendations given by the radiopharmacist were well accepted by the nuclear physicians who changed their approach contributing to increase the safety of patients referred for MPI.

The New Nano-Resuscitation Solution (TPP-MR) Attenuated Myocardial Injury in Hemorrhagic Shock Rats by Inhibiting Ferroptosis.

Hemorrhagic shock was a leading cause of death worldwide, with myocardial injury being a primary affected organ. As commonly used solutions in fluid resuscitation, acetated Ringer's (AR) and Lactate Ringer's solution (LR) were far from perfect for their adverse reactions such as lactic acidosis and electrolyte imbalances. In previous studies, TPP@PAMAM-MR (TPP-MR), a novel nanocrystal resuscitation fluid has been found to protect against myocardial injury in septic rats. However, its role in myocardial injury in rats with hemorrhagic shock and underlying mechanism is unclear. The hemorrhagic shock rats and hypoxia-treated cardiomyocytes (H9C2) were utilized to investigate the impact of TPP-MR on cardiac function, mitochondrial function, and lipid peroxidation. The expressions of ferritin-related proteins glutathione peroxidase 4 (GPX4), Acyl CoA Synthase Long Chain Family Member 4 (ACSL4), and Cyclooxygenase-2(COX2) were analyzed through Western blotting to explore the mechanism of TPP-MR on hemorrhagic myocardial injury. TPP-MR, a novel nanocrystalline resuscitation fluid, was synthesized using TPP@PAMAM@MA as a substitute for L-malic acid. We found that TPP-MR resuscitation significantly reduced myocardial injury reflected by enhancing cardiac output, elevating mean arterial pressure (MAP), and improving perfusion. Moreover, TPP-MR substantially prolonged hemorrhagic shock rats' survival time and survival rate. Further investigations indicated that TPP-MR improved the mitochondrial function of myocardial cells, mitigated the production of oxidative stress agents (ROS) and increased the glutathione (GSH) content. Additionally, TPP-MR inhibited the expression of the ferroptosis-associated GPX4 protein, ACSL4 and COX2, thereby enhancing the antioxidant capacity. The results showed that TPP-MR had a protective effect on myocardial injury in rats with hemorrhagic shock, and its mechanism might be related to improving the mitochondrial function of myocardial cells and inhibiting the process of ferroptosis.

Less Frequently Used Growth Regulators in Plant Tissue Culture.

Plant growth regulators are routinely added to in vitro culture media to foster the growth and differentiation of the cells, tissues, and organs. However, while the literature on usage of the more common auxins, cytokinins, gibberellins, abscisic acid, and ethylene is vast, other compounds that also have shown a growth-regulating activity have not been studied as frequently. Such substances are also capable of modulating the responses of plant cells and tissues in vitro by regulating their growth, differentiation, and regeneration competence, but also by enhancing their responses toward biotic and abiotic stress agents and improving the production of secondary metabolites of interest. This chapter will discuss the in vitro effects of several of such less frequently added plant growth regulators, including brassinosteroids (BRS), strigolactones (SLs), phytosulfokines (PSKs), methyl jasmonate, salicylic acid (SA), sodium nitroprusside (SNP), hydrogen sulfite, various plant growth retardants and inhibitors (e.g., ancymidol, uniconazole, flurprimidol, paclobutrazol), and polyamines.

TURMERIC'S ROLE AS A NATURAL ANTIBIOTIC AGAINST IMMUNOSUPPRESSIVE DISEASES IN POULTRY

The poultry industry, a vital constituent of global food production, poses formidable threats from immunosuppressive illnesses that compromise poultry health, output, and economic sustainability. Due to various infectious and non-infectious agents, these immunosuppressive provisions significantly heighten birds' susceptibility to secondary infections and undermine the efficacy of vaccination. Poultry mortality and morbidity can be caused by non-infectious factors such as environmental stressors and nutritional deficiencies. The overuse of antibiotics in poultry production raises concerns about antibiotic resistance and public health, leading to the search for natural alternatives. Turmeric, scientifically known as Curcuma longa, has emerged as a promising solution due to its various attributes, including antimicrobial, antioxidant, anti-inflammatory, and immunomodulatory properties. It is poised to effectively supplant synthetic antibiotics in poultry, thus mitigating the risks to public health. This review paper investigates the role of turmeric as a natural antibiotic against immunosuppressive diseases in poultry. It comprehensively explores the multifaceted causes of immunosuppression in poultry, encompassing environmental stress, nutritional factors, and infectious agents. Furthermore, the article explores how turmeric can combat various issues and highlights its potent antimicrobial, anti-inflammatory, and antioxidant properties. Turmeric has been shown to enhance growth, boost immune function, and mitigate the adverse effects of stress, making it a valuable and sustainable solution for the poultry industry. By alleviating the risk of immunosuppression, turmeric safeguards avian health and augments the industry's overall success. This paper underscores the significance of embracing natural remedies like turmeric to uphold poultry health and well-being while diminishing reliance on synthetic antibiotics.

Intrinsically disordered Prosystemin discloses biologically active repeat motifs

The in-depth studies over the years on the defence barriers by tomato plants have shown that the Systemin peptide controls the response to a wealth of environmental stress agents. This multifaceted stress reaction seems to be related to the intrinsic disorder of its precursor protein, Prosystemin (ProSys). Since latest findings show that ProSys has biological functions besides Systemin sequence, here we wanted to assess if this precursor includes peptide motifs able to trigger stress-related pathways. Candidate peptides were identified in silico and synthesized to test their capacity to trigger defence responses in tomato plants against different biotic stressors. Our results demonstrated that ProSys harbours several repeat motifs which triggered plant immune reactions against pathogens and pest insects. Three of these peptides were detected by mass spectrometry in plants expressing ProSys, demonstrating their effective presence in vivo. These experimental data shed light on unrecognized functions of ProSys, mediated by multiple biologically active sequences which may partly account for the capacity of ProSys to induce defense responses to different stress agents.

Elevated Expression of HSP72 in the Prefrontal Cortex and Hippocampus of Rats Subjected to Chronic Mild Stress and Treated with Imipramine.

The HSP70 and HSP90 family members belong to molecular chaperones that exhibit protective functions during the cellular response to stressful agents. We investigated whether the exposure of rats to chronic mild stress (CMS), a validated model of depression, affects the expression of HSP70 and HSP90 in the prefrontal cortex (PFC), hippocampus (HIP) and thalamus (Thal). Male Wistar rats were exposed to CMS for 3 or 8 weeks. The antidepressant imipramine (IMI, 10 mg/kg, i.p., daily) was introduced in the last five weeks of the long-term CMS procedure. Depressive-like behavior was verified by the sucrose consumption test. The expression of mRNA and protein was quantified by real-time PCR and Western blot, respectively. In the 8-week CMS model, stress alone elevated HSP72 and HSP90B mRNA expression in the HIP. HSP72 mRNA was increased in the PFC and HIP of rats not responding to IMI treatment vs. IMI responders. The CMS exposure increased HSP72 protein expression in the cytosolic fraction of the PFC and HIP, and this effect was diminished by IMI treatment. Our results suggest that elevated levels of HSP72 may serve as an important indicator of neuronal stress reactions accompanying depression pathology and could be a potential target for antidepressant strategy.

Papel del radiofarmacéutico clínico en la seguridad del paciente durante los estudios de perfusión miocárdica de esfuerzo con vasodilatadores

AimTo assess the radiopharmacist's role in a multidisciplinary team focused on the contraindications of regadenoson in order to ensure the safe use of pharmacologic vasodilator stress agents in patients undergoing SPECT-MPI. MethodsWe ambispectively studied its safe use in 1905 patients (54.1% female, mean age: 66.6±11.7 years, range: 20-95years). Sex, age, medical history, medications, drug allergies, and contraindications for stress testing were registered together with recommendations for the nuclear physician in charge. ResultsDetected contraindications and corresponding recommendations were as follows: risk factors for QTc interval prolongation 7.5% — measurement of QTc interval previously to test and monitor ECG; prior stroke or TIA 4.2% — consider carotid stenosis assessment; salicylates/sulfonamides allergy 3.1% — use 99mTc-sestamibi; epilepsy or risk factors for seizures 2.4% — use of adenosine or reconsider test indication; systemic corticosteroid therapy for severe COPD 1.3% — reassessment of patient's condition; acute exacerbation of COPD 0.8% — defer test until acute episode is over; severe asthma 0.4% — do not perform test; methylxanthine ingestion 0.3% — avoid consumption previously; other 6.1% — evaluation of other contraindications. No contraindications were detected in 73.6% of patients. The test was cancelled due to absolute contraindications in 2.9% of the requests. ConclusionsWorking in a systematic way, the radiopharmacist was able to detect a high number of issues related to regadenoson, with one out of four patients presenting some clinical contraindication. The recommendations given by the radiopharmacist were well accepted by the nuclear physicians who changed their approach contributing to increase the safety of patients referred for MPI.

Response of the antioxidant system of wheat seedlings with different genotypes to exogenous prooxidants: the relationship with resistance to abiotic stressors

Oxidative stress is an important component of heat- and drought-induced damage in plants. However­, information on the relationship between the resistance of cultivated plants with different genotypes to environmental factors and their ability to maintain a pro-/antioxidant balance remains contradictory. This study aimed to compare the growth responses and adaptation ability of the antioxidant system in different wheat cultivars to oxidative stress agents hydrogen peroxide and iron(II) sulfate. Etiolated seedlings of common winter wheat (Triticum aestivum L.) Antonivka and Tobak (heat- and drought-tolerant), and Avgustina and Doskonala (not resistant to heat and drought) were used for the study. Three-day-old etiolated seedlings were exposed to 50 mM H2O2 or 5 mM FeSO4 for one day. It was found that seedlings of Antonivka and Tobak cultivars treated with H2O2 or FeSO4 were able to maintain relatively intensive growth, accumulated significantly lower amounts of endogenous hydrogen peroxide and lipid peroxidation products, significantly increased anthocyanin content and had a higher activity of SOD and catalase as compared with non-resistant cultivars. The non-tolerant cultivars’ response to stress agents was only to increase proline content with a simultaneous decrease in SOD activity and anthocyanins content. The identified varietal markers of the antioxidant system adaptive strategy can be used to develop new approaches for screening wheat cultivars with cross-resistance to major abiotic stressors. Keywords: antioxidant system, drought resistan­ce, ferrous sulphate, H2O2, heat tolerance, oxidative stress, Triticum aestivum seedlings

Energy deficit in surgery on the examples of cholestasis and massive liver resection

The paper is dedicated to the energy processes associated with diseases in living organisms. Experiments involved 151 rats. Liver tissue was taken to determine its energy state in cholestasis (common bile duct ligation) and after resection of 60% and 80% of the parenchyma (without cholestasis). Adenine nucleotides (ATP, ADP, and AMP) and activity of gluconeogenesis enzymes were studied in cholestasis every 3 days for 15 days and after liver resection – every 6 hours for 3 days. Particular attention was paid to the energy deficit in liver tissue. A certain level of energy deficit n agent of metabolic stress. The experiments revealed that the energy deficit in the liver tissue increased by 15% by day 6 of cholestasis and by 48–50% of the initial energy level by days 12–15. The increase in energy deficit in liver tissue inversely correlated with the decrease in the activity of gluconeogenesis enzymes – by day 15 glucose-6- phosphate dehydrogenase reduced by 44% and isocitrate dehydrogenase – by 48% of the initial energy level. Decompression after 15 days from the onset of cholestasis was followed by an increase in energy deficit by 15%, as compared to the initial energy level, within 3–5 days. No development of metabolic stress was evidenced by a decrease in the activity of gluconeogenesis enzymes. After 12 hours after resection of 60% and 80% of the liver parenchyma, the liver energy deficit in both groups accounted for 50% of the initial energy level. After resection of 60% of the liver parenchyma, the energy deficit decreased rapidly: after 24 hours to 30%, after 72 hours to 11%; 2 rats out of 30 died during this period. After 12 hours after resection of 80% of the liver parenchyma, the energy deficit rose sharply: after 24 hours to 70% of the initial energy level. This led to the death of 26 animals out of 31. Both groups of animals demonstrated an inverse relationship between the decreased amount of energy used for hepatocyte function and the increased activity of key enzymes of gluconeogenesis. The obtained results suggest that in both groups of animals, metabolic stress developed after liver resection, however, after resection of 80% of the organ parenchyma, it “choked” due to the deficit of remnant hepatocytes. Most of the energy was spent for the development of regeneration. Metabolic stress and regeneration develop simultaneously. A deficit of 50% of energy in liver tissue with a further increase may indicate a critical condition, both in cholestasis and after a massive resection. The research into energy changes in cholestasis and after massive liver resections reveals new patterns of internal processes of the body.

Adaptive changes in tumor cells in response to reductive stress

Reductive stress is characterized by an excess of cellular electron donors and can be linked with various human pathologies including cancer. We developed melanoma cell lines resistant to reductive stress agents: rotenone (ROTR), n-acetyl-L-cysteine, (NACR), or dithiothreitol (DTTR). Resistant cells divided more rapidly and had intracellular homeostatic redox-couple ratios that were shifted towards the reduced state. Resistance caused alterations in general cell morphology, but only ROTR cells had significant changes in mitochondrial morphology with higher numbers that were more isolated, fragmented and swollen, with greater membrane depolarization and decreased numbers of networks. These changes were accompanied by lower basal oxygen consumption and maximal respiration rates. Whole cell flux analyses and mitochondrial function assays showed that NACR and DTTR preferentially utilized tricarboxylic acid (TCA) cycle intermediates, while ROTR used ketone body substrates such as D, L-β-hydroxybutyric acid. NACR and DTTR cells had constitutively decreased levels of reactive oxygen species (ROS), although this was accompanied by activation of nuclear factor erythroid 2–related factor 2 (Nrf2), with concomitant increased expression of the downstream gene products such as glutathione S-transferase P (GSTP). Further adaptations included enhanced expression of endoplasmic reticulum proteins controlling the unfolded protein response (UPR). Although expression patterns of these UPR proteins were distinct between the resistant cells, a trend implied that resistance to reductive stress is accompanied by a constitutively increased UPR phenotype in each line. Overall, tumor cells, although tolerant of oxidative stress, can adapt their energy and survival mechanisms in lethal reductive stress conditions.

Major adverse cardiovascular events in patients with ECG changes during dipyridamole infusion as a myocardial stress agent and normal MPI among filipino patients at a tertiary hospital

Abstract Introduction There is paucity and conflicting results of data regarding the prognostic significance of ST-segment depression during vasodilator stress testing in patients with normal myocardial perfusion imaging (MPI). It is even less well studied in minorities such as Filipino population. Purpose This study aims to determine the major adverse cardiovascular events (MACE) in patients with ECG changes during dipyridamole infusion as a myocardial stress agent and normal myocardial perfusion imaging. Methodology We performed a cross-sectional retrospective analysis of 266 adult patients aged 18 years and above who underwent dipyridamole MPI. Patients with abnormal baseline ECG, patients subjected to tests other than the Dipyridamole VST and those with missing clinical, electrocardiogram, or myocardial perfusion Imaging data were excluded. The primary endpoint was the composite MACE: of all-cause mortality, nonfatal MI, stroke, hospitalization because of heart failure, and revascularization. Results Among 226 included patients (mean age ‘61.11 + 10.72’ years; 58% women), those with ST segment depression >0.5mm were more likely to have MACE (OR 281.12; 95% CI 37.59 to 2101.82, p-value <0.001), female patients were more likely to have MACE compared to male patients (OR 2.1839; 95% CI 1.1373 to 4.1936; p-value 0.019), and patients with atypical type of chest pain were likely to have MACE (OR 2.1767; CI 1.1844 to 4.0003; p-value 0.012). During follow-up of 3 years, a total of 55 patients had MACE. All-cause mortality occurred in 3 patients, non-fatal MI in 40 patients, Hospitalization due to heart failure in 5 patients, stroke in 6 patients, and revascularization in 1 patient. Conclusion Dipyridamole-induced ischemic ST depression is more common in women, and is associated with increased risk for future cardiac events compared with similar patients without ECG evidence of ischemia. Ischemic ECG changes during dipyridamole MPI should warrant further evaluation and follow up, even when perfusion images are reassuring.

Abstract 12361: Predictors and Utilization of Ultrasound Enhancing Agents for Echocardiography in the Outpatient Setting

Background: The national utilization of ultrasound enhancing agents (UEAs) for transthoracic (TTE) or stress (SE) echocardiography in the outpatient setting and their association with downstream utilization of care remains uncertain. Methods: In a set of large, all-payer claims databases (ACTICS Open and Closed Claims) encompassing 90% of the US population, we evaluated rates, predictors of use, and association of UEAs with downstream utilization using linear mixed effects models amongst adult outpatients receiving TTE or SE, 2019-2022. Amongst those with recent hospitalization for AMI, we evaluated the association of UEA receipt and downstream healthcare utilization. Results: A total of 11,270,268 individuals receiving TTE and 744,175 adults receiving SE across 2,407 sites were included (mean age 63, 54.8% female), of which 6.8% receiving TTE and 21.0% receiving SE received UEAs. Patients receiving UEAs were more frequently older, male, and had a greater number of comorbidities. Sites performing UEAs were more frequently large, rural, nonprofits, and teaching facilities. Use varied widely by state ( Figure; 19.7% in Minnesota vs. 1.1% in Delaware) and was not explained by patient or site characteristics (median odds ratios = 4.35). Amongst those receiving TTE after AMI, UEA use was associated with a reduction in cardiac non-stress imaging (adjusted RR 0.77, 95% CI 0.64-0.92, p = 0.004), but no substantial differences in cost, days alive at home, readmission rates, cardiac catheterization, or stress imaging (p > 0.05 for all). Conclusions: In this large, nationally representative cohort study, UEAs were used in 6.8% of TTEs and 21.0% of SEs performed in the outpatient setting but use varied widely across sites, unexplained by patient or site characteristics. Amongst outpatients, UEA receipt after AMI was associated with a reduction in cardiac stress imaging, but not other outcomes.

Physics-Informed Deep Learning-Based Approach for Probabilistic Modeling of Degradation

Deep learning (DL) models have gained significant popularity for the prognostics of systems experiencing degradation. However, there are two major concerns with such models. Firstly, they require a substantial amount of training data due to their large number of parameters. Secondly, they disregard the underlying physics and solely fit the available data, leading to potentially weak generalization capabilities when faced with unseen out-of-distribution data in the field. This study aims to tackle these challenges by incorporating the underlying physics of degradation into DL models. The objective is to develop a novel DL-based approach in conjunction with Bayesian filtering, enabling physics-informed probabilistic life prediction for systems subject to environmentally induced degradation. The proposed framework consists of two main components: physics discovery and degradation prediction. The former involves identifying the dominant stress agents and formulating the underlying physics of degradation. The latter predicts the degradation of the system by incorporating the discovered physics into a DL model. It is expected the results indicate that by combining data-driven DL with physics-based insights, more robust and reliable life predictions can be achieved, addressing the limitations of DL approaches. This framework holds promise for enhancing decision-making processes related to maintenance strategies in various industries.

Pincer Ligands as Multifunctional Agents for Alzheimer's Copper Dysregulation and Oxidative Stress: A Computational Evaluation.

Alzheimer's disease (AD) is the most common form of dementia worldwide, affecting millions of people around the globe. AD is characterized by different pathologies being beta-amyloid (Aβ) plaque formation, metal ion dysregulation, and oxidative stress (OS) central topics under investigation. Copper-Aβ complexes have been shown to induce catalytic hydrogen peroxide formation and increase OS in the brain leading to neuronal death. Pincer-type compounds are tridentate ligands that coordinate metals in a planar fashion whose properties can be tuned via group substitutions, giving rise to many possibilities in catalysis and drug discovery. In this work we evaluated the potential pharmaceutical activity of 26 pincer compounds in AD's copper ion-related oxidative stress framework. In this sense, four key aspects were considered: 1) Lipinski's rule of five, 2) blood-brain barrier permeation, 3) standard reduction potential (SRP) of the formed copper complexes, and 4) the ligand's affinity towards copper cations. The evaluation of these criteria was performed by means of bioinformatic tools and electronic structure calculations at the DFT level of theory. Our results suggest that two compounds from this set are potential antioxidant agents, whereas five of them are promissory distributor-like compounds in the context of AD.

Microcystin aids in cold temperature acclimation: Differences between a toxic Microcystis wildtype and non-toxic mutant

For Microcystis aeruginosa PCC 7806, temperature decreases from 26 °C to 19 °C double the microcystin quota per cell during growth in continuous culture. Here we tested whether this increase in microcystin provided M. aeruginosa PCC 7806 with a fitness advantage during colder-temperature growth by comparing cell concentration, cellular physiology, reactive oxygen species damage, and the transcriptomics-inferred metabolism to a non-toxigenic mutant strain M. aeruginosa PCC 7806 ΔmcyB. Photo-physiological data combined with transcriptomic data revealed metabolic changes in the mutant strain during growth at 19 °C, which included increased electron sinks and non-photochemical quenching. Increased gene expression was observed for a glutathione-dependent peroxiredoxin during cold treatment, suggesting compensatory mechanisms to defend against reactive oxygen species are employed in the absence of microcystin in the mutant. Our observations highlight the potential selective advantages of a longer-term defensive strategy in management of oxidative stress (i.e., making microcystin) vs the shorter-term proactive strategy of producing cellular components to actively dissipate or degrade oxidative stress agents.

Impact of β-glucan dietary supplementation on productive, reproductive performance and physiological response of laying hens under heat stress conditions

The exploration for effective in-feed additives is growing owing to the global climatic change trend to alleviate the negative effects of heat stress in laying hens. This research assessed the potential of using B-glucan (G) as an antiheat stress agent in Matrouh laying hens subjected to early heat shock programs during the growing period. Factorial design (3 × 3) was used, including 3 levels of heat stress (control, heat shock at 3 d and at 3 d and 8 wk of age) and 3 levels of β-glucan (0, 100, and 200 mg β-glucan /kg diet). During the first 12 wk of egg production (EP), treatments were exposed to heat challenge. The results revealed that heat shock program applications at 3 d and 8 wk of age significantly decreased body weight at 36 wk of age (P < 0.05) and reduced (P < 0.05) feed intake (FI). While significantly (P < 0.05) improved feed conversion ratio (FCR), hemoglobin, RBCs, WBCs, immunoglobulin M (IgM), immunoglobulin G (IgG), and Heat shock protein (HSP70) of the Liver (P < 0.01) as compared with the control group. At the same time, there was a decrease in lymphocyte%, H/L ratio, cortisol, and T3 compared to the thermo-neutral control. When compared to the control group, hens fed a diet containing 200 mg of βG significantly (P < 0.05) improved body weight at 16 wk and final weight at 36 wk, feed conversion (FCR) (g. feed/g. egg mass), hen-day egg production, and egg mass, as well as the digestibility coefficients of crude protein (CP), dry matter (DM), metabolizable energy (ME), and cortisol. The interactions between heat chock programs and βG levels were nonsignificant for the most studied traits except daily feed intake. Therefore, the early heat shock exposure 2 times and supplementation of Β-glucan (βG) at 200 mg/kg diet during the growth period for laying hens that are exposed to heat stress during the reproductive period could improve productive, reproductive performance, HSP70 level and enhance immunity responses.

Spermidine synthase is essential for vegetative growth, stress response, secondary metabolism and pathogenicity in Alternaria alternata

Black spot, caused by the fungus Alternaria alternata, is one of the postharvest diseases that cause significant economic losses. Polyamine metabolism in fungi plays key roles in cellular processes and pathogen-host interactions. However, little is known about their detailed regulatory mechanisms on pathogenicity of plant fungi. In this study, we characterized the spermidine synthase AaSPDS in A. alternata. Knocking out AaSPDS caused a total loss of vegetative growth and sporulation which was partially restored by exogenous spermidine (Spd), so supplying 0.5 mM exogenous Spd to medium for evaluating the characteristics of WT and ΔAaSPDS. The deletion strain showed albino colonies, sparse mycelial tips and significant decreased biomass accumulation and melanin production. ΔAaSPDS strain was also more sensitive to osmotic stress, oxidative stress and cell wall-perturbing agents. Interestingly, the expression level of AaSPDS was greatly up-regulated during infection structure differentiation stage of A. alternata, and appressorium formation of the AaSPDS deletion strain was completely blocked. In addition, deletion of the AaSPDS gene led to a significant reduction in pathogenicity to pear fruit, altenuene (ALT) mycotoxin accumulation and the activities of cellulase (CL), β-glucosidase (β-GC) and polygalacturonase (PG). The results presented in this study suggested that AaSPDS influences the pathogenicity of A. alternata by regulating infection structure formation, cell wall degrading enzyme (CWDE) activity and mycotoxin production.

Nitric Oxide Modulates Salt Stress Tolerance in Lettuce

Crops are constantly threatened by salinity. Nitric oxide (NO) is an attenuating agent for salt stress; however, the specific roles of NO in gas exchange and lettuce production are not well established. The objective of this study was to evaluate the application of different concentrations of sodium nitroprusside (SNP) as an agent to mitigate salt stress in lettuce plants. Lettuce seedlings in pots were subjected to irrigation without and with saline water (0.2 and 3.5 dS m−1) and applications of different concentrations (0, 50, 100, 150, and 200 µM) of SNP, a NO donor. Saline stress negatively affected lettuce development with a reduction of 29.5% in leaf area, 6.3% in relative water content in the leaf, 17.2% in stem diameter, and 10.7% in dry matter mass in the control, but the application of SNP mitigated the deleterious effects of salt stress. Concentrations between 100 and 150 µM of SNP improved the photosynthetic metabolism of lettuce under salinity, with an increase of 46.7% in CO2 assimilation and 42.3% in fresh matter mass. Pearson’s correlation showed that fresh matter correlated positively with CO2 assimilation. Therefore, SNP can be used to mitigate salt stress in lettuce.

Kaempferol attenuates carbon tetrachloride (CCl4)-induced hepatic fibrosis by promoting ASIC1a degradation and suppression of the ASIC1a-mediated ERS

BackgroundKaempferol is a flavonoid derived from the herb, Kaempferia galanga L., in addition to exhibiting a wide range of pharmacological properties, kaempferol is also an anti-inflammatory, anti-lipid metabolizing, and anti-oxidative stress agent. The underlying molecular mechanisms of its effects on vascular endothelial growth factor (VEGF) secretion and activation of hepatic stellate cells (HSCs) are yet unknown. Activated HSCs induces VEGF release and extracellular matrix (ECM) accumulation which are important factors in hepatic fibrosis. PurposeOur aim is to explore how kaempferol may affect hepatic fibrosis and the mechanisms behind its effects. MethodsThe in vivo model was Sprague-Dawley rats induced with carbon tetrachloride (CCl4). Histological staining was used to observe histological features of the liver. The levels of (alanine aminotransferase) ALT and (aspartate aminotransferase) AST were detected by the corresponding kits. Platelet-derived growth factor (PDGF) was used to stimulate the HSC-T6 rat hepatic stellate cells. The mechanisms underlying this process were investigated using a variety of molecular approaches, including immunofluorescence, RT-qPCR, and western blotting. Moreover, intracellular Ca2+ were observed by laser confocal microscope. ResultsIt was found that kaempferol significantly reduced the expression of ASIC1a, VEGF, α-SMA and Collagen-I proteins in a model of CCl4-induced hepatic fibrosis in rats. In HSC-T6, kaempferol inhibits activation of HSCs by decreasing expression of ASIC1a, eIF2α, p-eIF2α and ATF-4. Laser confocal fluorescence showed that kaempferol inhibited Ca2+ influx and reduced Ca2+ concentration around the endoplasmic reticulum. Molecular docking and cellular thermal shift assay (CETSA) results further indicated that kaempferol interacted with ASIC1a. We found that kaempferol may promote the degradation of ASIC1a and inhibited ASIC1a- mediated upregulation of ERS. ConclusionThe data from our in vivo experiments demonstrate that kaempferol effectively attenuates hepatic fibrosis. In vitro studies we further propose a novel mechanism of kaempferol against hepatic fibrosis which can interact with ASIC1a and promote ASIC1a degradation while inhibiting the activation and VEGF release of HSCs by suppressing the ASIC1a-eIF2α-ATF-4 signaling pathway.