Serine protease mediates Ovomermis sinensis-inhibited host immune responses by inducing apoptosis: implications for successful parasitism and host mortality

BACKGROUND

Mermithid nematodes are entomopathogens that parasitize and kill insect hosts and are used for biological control. It is widely believed that mermithid nematodes kill their host upon nematode emergence, unlike other parasites that depend on virulence factors. In this study, we disproved this theory by demonstrating that the mermithid nematode Ovomermis sinensis mediates host mortality by serine protease-induced apoptosis.

RESULTS

Successful parasitism of O. sinensis increased with the infection rate, and the inhibition of host immunity by O. sinensis increased with the parasitic load. A serine protease was identified from the host hemolymph. This protease belongs to the trypsin-like serine protease family, which is an apoptosis-inducing serine protease. Specifically, Os-sp was highly expressed only during the parasitic stage and could be induced by host hemocytes and the fat body. Importantly, host immune effectors (melanization, phenoloxidase activity, and encapsulation) were suppressed by the recombinant protein rOs-sp that induced apoptosis of hemocytes and fat body in a dose-dependent manner, which contributes to host death.

CONCLUSION

Serine protease mediates O. sinensis-inhibited host immune responses by inducing apoptosis that is lethal to the insect host. Our findings have broader implications for understanding the mechanism of successful parasitism and killing of host by nematodes. © 2023 Society of Chemical Industry.

[Association of waist-to-height ratio with sarcopenic obesity in hemodialysis patients with normal body mass index]

Objective: To explore the association between waist-to-height ratio (WHtR) and sarcopenic obesity (SO) in maintenance hemodialysis (MHD) patients with normal body mass index (BMI). Methods: A multicenter and cross-sectional study that included adult patients undergoing MHD was conducted in 20 hemodialysis centers from June 1st to August 30th, 2021. Body composition was evaluated by body composition monitor based on bioimpedance spectroscopy. According to the quartiles of WHtR, patients were divided into four groups: Q1, Q2, Q3 and Q4 group. The association of WHtR with SO was determined by multiple logistic regression models, stratified analyses, interactive analyses, and receiver operating characteristic (ROC) analyses, respectively. Results: A total of 2 207 MHD patients (1 341 males and 866 females) were included, and aged [M (Q1, Q3)] 57 (44, 68) years. The prevalence of SO was increased with increasing quartiles of WHtR [8.6% (46/533), 22.5% (141/628), 35.4% (215/608), and 44.3% (194/438) for Q1, Q2, Q3, and Q4 group, respectively]. Multivariate logistic regression analysis showed that WHtR was associated with SO. The association remained statistically significant even after adjusting for age, gender, dialysis vintage, BMI, biochemical indicators, and various medical histories. Compared with Q1 group, the odds ratios (OR) were 2.54 (95%CI: 1.69-3.83), 4.30 (95%CI: 2.88-6.42) and 5.18 (95%CI: 3.37-7.96) for Q2, Q3 and Q4 group, respectively. The interaction analysis showed that age, sex and history of diabetes had interactive roles in the association between WHtR and SO (all P<0.05). The association stably existed across subgroups, and it was more obvious in male patients, those with older age and without a history of diabetes（all P<0.05）. Furthermore, the cut-off value of WHtR identifying SO in male patients was 0.49, and the corresponding area under the curve (AUC) was 0.73 (95%CI: 0.70-0.75), with the sensitivity of 72.7% and specificity of 60.3%. In female patients, the cut-off value was 0.51, and the AUC was 0.68 (95%CI: 0.65-0.71), with the sensitivity of 70.1% and specificity of 57.8%. Conclusion: WHtR could be used as a simple index to evaluate the risk of SO in MHD patients with normal BMI.

Response mechanism of carbon metabolism of Pinus massoniana to gradient high temperature and drought stress

BACKGROUND

The carbon metabolism pathway is of paramount importance for the growth and development of plants, exerting a pivotal regulatory role in stress responses. The exacerbation of drought impacts on the plant carbon cycle due to global warming necessitates comprehensive investigation into the response mechanisms of Masson Pine (Pinus massoniana Lamb.), an exemplary pioneer drought-tolerant tree, thereby establishing a foundation for predicting future forest ecosystem responses to climate change.

RESULTS

The seedlings of Masson Pine were utilized as experimental materials in this study, and the transcriptome, metabolome, and photosynthesis were assessed under varying temperatures and drought intensities. The findings demonstrated that the impact of high temperature and drought on the photosynthetic rate and transpiration rate of Masson Pine seedlings was more pronounced compared to individual stressors. The analysis of transcriptome data revealed that the carbon metabolic pathways of Masson Pine seedlings were significantly influenced by high temperature and drought co-stress, with a particular impact on genes involved in starch and sucrose metabolism. The metabolome analysis revealed that only trehalose and Galactose 1-phosphate were specifically associated with the starch and sucrose metabolic pathways. Furthermore, the trehalose metabolic heat map was constructed by integrating metabolome and transcriptome data, revealing a significant increase in trehalose levels across all three comparison groups. Additionally, the PmTPS1, PmTPS5, and PmTPPD genes were identified as key regulatory genes governing trehalose accumulation.

CONCLUSIONS

The combined effects of high temperature and drought on photosynthetic rate, transpiration rate, transcriptome, and metabolome were more pronounced than those induced by either high temperature or drought alone. Starch and sucrose metabolism emerged as the pivotal carbon metabolic pathways in response to high temperature and drought stress in Masson pine. Trehalose along with PmTPS1, PmTPS5, and PmTPPD genes played crucial roles as metabolites and key regulators within the starch and sucrose metabolism.

Reactions of Ethynyloxy Radical with Hydroperoxyl Radical: Bridging Theoretical Reaction Dynamics and Chemical Modeling of Combustion

A detailed and accurate combustion reaction mechanism is crucial for understanding the nature of fuel combustion. In this work, a theoretical study of reaction HCCO+HO2 using M06-2X/6-311++G(d,p) for geometry optimization and combined methods based on spin-unrestricted CCSD(T)/CBS level of theory with basis set extrapolation from MP2/aug-cc-pVnZ (n=T and Q) for energy calculations were performed. The temperature- and pressure-dependent rate coefficients at 300-2000 K and 0.01-100 atm, suitable for combustion conditions, were derived using the Rice-Ramsberger-Kassel-Marcus/Master-Equation approach. Furthermore, temperature-dependent thermochemistry data of key species for the HCCO+HO2 system has also been studied. Finally, an updated ketene model is developed by supplementing the most recent theoretical work and the theoretical work in this paper. This updated model was tested to simulate the speciation of ketene oxidation in available experimental research. It is shown that the updated model for predicting ketene oxidation exhibits a high level of agreement with experimental data across a wide range of species profiles. An analysis was conducted to identify the crucial reactions that influence ketene ignition. This paper's research findings are essential for enhancing the combustion mechanism of ketene and other hydrocarbons and oxygenated hydrocarbon fuels.

Synthesis, biological activities and mechanism studies of 1,3,4-oxadiazole analogues of petiolide A as anticancer agents

In order to develop new natural product-based anticancer agents, a series of 1,3,4-oxadiazole analogues based on petiolide A were prepared and evaluated for their anticancer activities by MTT method. The structures of all analogues were characterized by various spectral analyses, and B9 was further confirmed by X-ray crystallography. Among all the synthesized compounds, B1 displayed the most promising growth inhibitory effect on colon cancer cells (HCT116) with the IC50 value of 8.53 μM. Flow cytometric analysis exhibited that B1 arrested the cell cycle at G2 phase and induced apoptosis. Additionally, network pharmacology analysis calculated that B1 might target several key proteins, including AKT serine/threonine kinase 1 (AKT1), SRC proto-oncogene, non-receptor tyrosine kinase (SRC) and epidermal growth factor receptor (EGFR). Furthermore, molecular docking study indicated that B1 had potentially high binding affinity to these three target proteins. Given these results, analogue B1 could be deeply developed as potential anticancer agents.

Deep Eutectic Solvent-Based Dispersive Liquid-Liquid Microextraction Coupled with LC-MS/MS for the Analysis of Two Ochratoxins in Capsicum

Ochratoxins, a common class of mycotoxin in capsicum, and techniques and methods for the determination of mycotoxins in spices have been increasingly developed in recent years. An innovative and eco-friendly method of dispersive liquid-liquid microextraction (DLLME) was demonstrated in this study, based on a synthesized deep eutectic solvent (DES) combined with LC-MS/MS, for the quantification and analysis of two ochratoxins in capsicum. The DES-DLLME method parameters entail selecting the DES type (thymol:decanoic acid, molar ratio 1:1) and DES volume (100 μL). The volume of water (3 mL) and salt concentration (0 g) undergo optimization following a step-by-step approach to achieve optimal target substance extraction efficiency. The matrix effect associated with the direct detection of the target substance in capsicum was significantly reduced in this study by the addition of isotopic internal standards corresponding to the target substance. This facilitated optimal conditions wherein quantitative analysis using LC-MS/MS revealed a linear range of 0.50-250.00 µg/mL, with all two curves calibrated with internal standards showing correlation coefficients (r2) greater than 0.9995. The method's limits of detection (LODs) and limits of quantification (LOQs) fell in the ranges of 0.14-0.45 μg/kg and 0.45-1.45 μg/kg, respectively. The method's spiked recoveries ranged from 81.97 to 105.17%, indicating its sensitivity and accuracy. The environmental friendliness of the technique was assessed using two green assessment tools, AGREE and complexGAPI, and the results showed that the technique was more in line with the concept of sustainable development compared to other techniques for detecting ochratoxins in capsicum. Overall, this study provides a new approach for the determination of mycotoxins in a complex food matrix such as capsicum and other spices using DES and also contributes to the application of green analytical chemistry methods in the food industry.

Effects of PmaIAA27 and PmaARF15 genes on drought stress tolerance in pinus massoniana

BACKGROUND

Auxin plays an important role in plant resistance to abiotic stress. The modulation of gene expression by Auxin response factors (ARFs) and the inhibition of auxin/indole-3-acetic acid (Aux/IAA) proteins play crucial regulatory roles in plant auxin signal transduction. However, whether the stress resistance of Masson pine (Pinus massoniana), as a representative pioneer species, is related to Aux/IAA and ARF genes has not been thoroughly studied and explored.

RESULTS

The present study provides preliminary evidence for the regulatory role of the PmaIAA27 gene in abiotic stress response in Masson pine. We investigated the effects of drought and hormone treatments on Masson pine by examining the expression patterns of PmaIAA27 and PmaARF15 genes. Subsequently, we conducted gene cloning, functional testing using transgenic tobacco, and explored gene interactions. Exogenous auxin irrigation significantly downregulated the expression of PmaIAA27 while upregulating PmaARF15 in Masson pine seedlings. Moreover, transgenic tobacco with the PmaIAA27 gene exhibited a significant decrease in auxin content compared to control plants, accompanied by an increase in proline content - a known indicator of plant drought resistance. These findings suggest that overexpression of the PmaIAA27 gene may enhance drought resistance in Masson pine. To further investigate the interaction between PmaIAA27 and PmaARF15 genes, we performed bioinformatics analysis and yeast two-hybrid experiments which revealed interactions between PB1 structural region of PmaARF15 and PmaIAA27.

CONCLUSION

The present study provides new insights into the regulatory functions of Aux/IAA and ARF genes in Masson pine. Overexpression of PmaIAA gene may have negative effects on the growth of Masson pine, but may improve the drought resistance. Therefore, this study has great application prospects.

Audiovisual n-Back Training Alters the Neural Processes of Working Memory and Audiovisual Integration: Evidence of Changes in ERPs

(1) Background: This study investigates whether audiovisual n-back training leads to training effects on working memory and transfer effects on perceptual processing. (2) Methods: Before and after training, the participants were tested using the audiovisual n-back task (1-, 2-, or 3-back), to detect training effects, and the audiovisual discrimination task, to detect transfer effects. (3) Results: For the training effect, the behavioral results show that training leads to greater accuracy and faster response times. Stronger training gains in accuracy and response time using 3- and 2-back tasks, compared to 1-back, were observed in the training group. Event-related potentials (ERPs) data revealed an enhancement of P300 in the frontal and central regions across all working memory levels after training. Training also led to the enhancement of N200 in the central region in the 3-back condition. For the transfer effect, greater audiovisual integration in the frontal and central regions during the post-test rather than pre-test was observed at an early stage (80-120 ms) in the training group. (4) Conclusion: Our findings provide evidence that audiovisual n-back training enhances neural processes underlying a working memory and demonstrate a positive influence of higher cognitive functions on lower cognitive functions.

Root relative water content is a potential signal for impending mortality of a subtropical conifer during extreme drought stress

Adaptation to future climates characterized by more frequent severe droughts requires enhanced mechanistic understanding of tree mortality. However, our knowledge of the physiological limits to withstand extreme drought, and how the coordination between water and carbon traits enhances survival, is still limited. Potted seedlings of Pinus massoniana were dehydrated to three target droughts (percentage loss of stem hydraulic conductivity of ca. 50%, 85%, and 100%; PLC₅₀ , PLC₈₅ and PLC₁₀₀ ) and then relieved from these target droughts by fully rewatering. Predawn and midday water potentials (Ψ), relative water content (RWC), PLC and nonstructural carbohydrates (NSC) were monitored. During drought, Ψ and RWC declined as PLC increased. Root RWC declined more rapidly than other organ RWCs, particularly after PLC₅₀ stress. All organ NSC concentrations were above predrought values. During rewatering, water trait recovery declined as drought increased, with no mortality at PLC₅₀ but 75% mortality at PLC₈₅ . The observed stem hydraulic recovery at PLC₅₀ following rewatering was not correlated to NSC dynamics. Collectively, our results highlighted the primary role of hydraulic failure in Pinus massoniana seedling mortality by assessing mortality threshold and links among water status and water supply. Root RWC can be considered as a potential warning signal of P. massoniana mortality.

Hydroxide-Mediated SNAr Rearrangement for Synthesis of Novel Depside Derivatives Containing Diaryl Ether Skeleton as Antitumor Agents

A simple and efficient hydroxide-mediated S_NAr rearrangement was reported to synthesize new depside derivatives containing the diaryl ether skeleton from the natural product barbatic acid. The prepared compounds were determined using ¹H NMR, ¹³C NMR, HRMS, and X-ray crystallographic analysis and were also screened in vitro for cytotoxicity against three cancer cell lines and one normal cell line. The evaluation results showed that compound 3b possessed the best antiproliferative activity against liver cancer HepG2 cell line and low toxicity, which made it worth further study.

Semisynthesis, Biological Evaluation and Molecular Docking Studies of Barbatic Acid Derivatives as Novel Diuretic Candidates

Barbatic acid, a compound isolated from lichen, has demonstrated a variety of biological activities. In this study, a series of esters based on barbatic acid (6a-q') were designed, synthesized, and evaluated for their diuretic and litholytic activity at a concentration of 100 μmol/L in vitro. All target compounds were characterized using ¹H NMR, ¹³C NMR, and HRMS, and the spatial structure of compound 6w was confirmed using X-ray crystallography. The biological results showed that some derivatives, including 6c, 6b', and 6f', exhibited potent diuretic activity, and 6j and 6m displayed promising litholytic activity. Molecular docking studies further suggested that 6b' had an optimal binding affinity to WNK1 kinases related to diuresis, while 6j could bind to the bicarbonate transporter CaSR through a variety of forces. These findings indicate that some barbatic acid derivatives could be further developed into novel diuretic agents.

Chick Early Amniotic Fluid (ceAF) Deters Tumorigenesis via Cell Cycle Arrest and Apoptosis

In recent years, amniotic fluids have gained attention in cancer research. They have an influential role in protecting embryos against several anomalies. Chick early amniotic fluid (ceAF)-amniotic fluid isolated from growing chicken-has been used in many other studies, including myocardial infarctions and skin regeneration. In this study, we employed ceAF's promising therapeutic applications against tumorigenesis in both in vitro and in vivo studies. We selected three robust proliferating tumor cell lines: BCaP37, MCF7, and RKO. We found that selective dosage is required to obtain maximum impact to deter tumorigenesis. ceAF not only disrupted the uniform colonies of tumor cell lines via disturbing mitochondrial transmembrane potential, but also arrested many cells at growing G1 state via working agonistically with aphidicolin. The significant inhibition of tumor metastasis by ceAF was indicated by in vivo models. This leads to apoptosis analysis as verified by annexin-V staining stays and immunoblotting of critical proteins as cell cycle meditators and apoptosis regulators. Not only on the protein level, but we also tested ceAF's therapeutic potentials on mRNA levels as indicated by quantitative real-time PCR summarizing the promising role of ceAF in deterring tumor progression. In conclusion, our study reveals the potent role of ceAF against tumorigenesis in breast cancer and colon carcinoma. Further studies will be required to determine the critical components present in ceAF and its purification to narrow down this study.