A conserved epitope III on hepatitis C virus E2 protein has alternate conformations facilitating cell binding or virus neutralization.

Epitope III, a highly conserved amino acid motif of 524APTYSW529 on the hepatitis C virus (HCV) E2 glycoprotein, resides in the critical loop that binds to the host receptor CD81, thus making it one of the most important antibody targets for blocking HCV infections. Here, we have determined the X-ray crystal structure of epitope III at a 2.0-Å resolution when it was captured by a site-specific neutralizing antibody, monoclonal antibody 1H8 (mAb1H8). The snapshot of this complex revealed that epitope III has a relatively rigid structure when confined in the binding grooves of mAb1H8, which confers the residue specificity at both ends of the epitope. Such a high shape complementarity is reminiscent of the "lock and key" mode of action, which is reinforced by the incompatibility of an antibody binding with an epitope bearing specific mutations. By subtly positioning the side chains on the three residues of Tyr527, Ser528, and Trp529 while preserving the spatial rigidity of the rest, epitope III in this cocrystal complex adopts a unique conformation that is different from previously described E2 structures. With further analyses of molecular docking and phage display-based peptide interactions, we recognized that it is the arrangements of two separate sets of residues within epitope III that create these discrete conformations for the epitope to interact selectively with either mAb1H8 or CD81. These observations thus raise the possibility that local epitope III conformational dynamics, in conjunction with sequence variations, may act as a regulatory mechanism to coordinate "mAb1H8-like" antibody-mediated immune defenses with CD81-initiated HCV infections.

Updated insights into anthocyanin stability behavior from bases to cases: Why and why not anthocyanins lose during food processing.

Anthocyanins have received considerable attention for the development of food products with attractive colors and potential health benefits. However, anthocyanin applications have been hindered by stability issues, especially in the context of complex food matrices and diverse processing methods. From the natural microenvironment of plants to complex processed food matrices and formulations, there may happen comprehensive changes to anthocyanins, leading to unpredictable stability behavior under various processing conditions. In particular, anthocyanin hydration, degradation, and oxidation during thermal operations in the presence of oxygen represent major challenges. First, this review aims to summarize our current understanding of key anthocyanin stability issues focusing on the chemical properties and their consequences in complex food systems. The subsequent efforts to examine plenty of cases attempt to unravel a universal pattern and provide thorough guidance for future food practice regarding anthocyanins. Additionally, we put forward a model with highlights on the role of the balance between anthocyanin release and degradation in stability evaluations. Our goal is to engender updated insights into anthocyanin stability behavior under food processing conditions and provide a robust foundation for the development of anthocyanin stabilization strategies, expecting to promote more and deeper progress in this field.

Novel insight into the role of sulfur dioxide in fruits and vegetables: Chemical interactions, biological activity, metabolism, applications, and safety.

Sulfur dioxide (SO2) are a category of chemical compounds widely used as additives in food industry. So far, the use of SO2 in fruit and vegetable industry has been indispensable although its safety concerns have been controversial. This article comprehensively reviews the chemical interactions of SO2 with the components of fruit and vegetable products, elaborates its mechanism of antimicrobial, anti-browning, and antioxidation, discusses its roles in regulation of sulfur metabolism, reactive oxygen species (ROS)/redox, resistance induction, and quality maintenance in fruits and vegetables, summarizes the application technology of SO2 and its safety in human (absorption, metabolism, toxicity, regulation), and emphasizes the intrinsic metabolism of SO2 and its consequences for the postharvest physiology and safety of fresh fruits and vegetables. In order to fully understand the benefits and risks of SO2, more research is needed to evaluate the molecular mechanisms of SO2 metabolism in the cells and tissues of fruits and vegetables, and to uncover the interaction mechanisms between SO2 and the components of fruits and vegetables as well as the efficacy and safety of bound SO2. This review has important guiding significance for adjusting an applicable definition of maximum residue limit of SO2 in food.

Development of a MOF-based SPE method combined with GC-MS for simultaneous determination of alachlor, acetochlor and pretilachlor in field soil.

In this work, a rapid, highly selective, reusable and effective method was developed for simultaneous determination of alachlor, acetochlor and pretilachlor in field soil by GC-MS coupled with MIL-101 based SPE. Main factors affecting the SPE by using MIL-101 were optimized. Moreover, by comparing with the other commercial materials such as C18, PSA and Florisil, the MIL-101(Cr) exhibited excellent adsorption performance, which aimed at amide herbicides. On the other hand, method validation displayed excellent method performance, achieving good linearities with r2 ≥ 0.9921, limits of detection between 0.25-0.45 µg kg-1, enrichment factors ≥ 89, matrix effect in the range of ± 20%, recoveries between 86.3% and 102.4%, and RSD lower than 4.38%. The developed method was successfully applied to the determination of amide herbicides in soil taken from the wheat, corn and soybean field at different depths, where the concentration of alachlor, acetochlor and pretilachlor were in the range of 0.62-8.04 µg kg-1. It was demonstrated that the more depth of soil, the lower of three amide herbicides. This finding could be proposed a novel method to detect the amide herbicides in the agriculture and food industry.

Multiple epitopes of hepatitis B virus surface antigen targeted by human plasma-derived immunoglobulins coincide with clinically observed escape mutations.

Hepatitis B immune globulin (HBIG) is a human plasma-derived immunoglobulin G concentrate that contains a high titer of neutralizing antibodies (anti-HBs) to the hepatitis B virus (HBV) surface antigen (HBsAg). HBIG is known to be highly effective in treating HBV infections, however, a more systematic characterization of the antibody binding sites on HBsAg and their correlation with emerging "escape" mutations in HBsAg was lacking. By using anti-HBs antibodies from HBIG lots to screen random peptide phage display libraries, we identified five clusters of peptides that corresponded to five distinct anti-HBs binding sites on the HBsAg. Three sites, Site II (C121-C124), Site III (M133-P135), and Site IV (T140-G145), were mapped within the "a" determinant, while the two other sites, Site I (Q101-M103) and Site V (I152-S154), were outside the "a" determinant. We then tested in binding assays HBsAg peptides containing clinically relevant mutations previously reported within these sites, such as Y134S, P142S, and G145R, and observed a significant reduction in anti-HBs binding activity to the mutated sites, suggesting a mechanism the virus may use to avoid HBIG-mediated neutralization. The current HBIG treatment could be improved by supplementing it with site-specific neutralizing monoclonal antibodies that target these mutations for control of HBV infections.

Exogenous stimulation-induced biosynthesis of volatile compounds: Aroma formation of oolong tea at postharvest stage.

Volatile organic compounds (VOCs) are produced by plants responding to biotic and abiotic stresses. According to their biosynthetic sources, induced VOCs are divided into three major classes: terpenoids, phenylpropanoid/benzenoid, and fatty acid derivatives. These compounds with specific aroma characteristics importantly contribute to the aroma quality of oolong tea. Shaking and rocking is the crucial procedure for the aroma formation of oolong tea by exerting mechanical damage to fresh tea leaves. Abundant studies have been carried out to investigate the formation mechanisms of VOCs during oolong tea processing in recent years. This review systematically introduces the biosynthesis of VOCs in plants, and the volatile changes due to biotic and abiotic stresses are summarized and expatiated, using oolong tea as an example.

Amphiphilic and Biocompatible DNA Origami-Based Emulsion Formation and Nanopore Release for Anti-Melanogenesis Therapy.

Programmable engineered DNA origami provides infinite possibilities for customizing nanostructures with controllable precision and configurable functionality. Here, a strategy for fabricating an amphiphilic triangular DNA origami with a central nanopore that integrates phase-stabilizing, porous-gated, and affinity-delivering effects is presented. By introducing the DNA origami as a single-component surfactant, the water-in-oil-in-water (W/O/W) emulsion is effectively stabilized with decreased interfacial tension. Microscopic observation validates the attachment of the DNA origami onto the water-in-oil and oil-in-water interfaces. Furthermore, fluorescence studies and molecular docking simulations indicate the binding interactions of DNA origami with arbutin and coumaric acid at docking sites within central nanopores. These central nanopores are functionalized as molecular gates and affinity-based scaffold for the zero-order release of arbutin and coumaric acid at a constant rate regardless of concentration gradient throughout the whole releasing period. In vivo zebrafish results illustrate the advantages of this zero-order release for anti-melanogenesis therapy over direct exposure or Fickian diffusion. The DNA origami-based W/O/W emulsion presents anti-melanogenic effects against UV-B exposure without cardiotoxicity or motor toxicity. These results demonstrate that this non-toxic amphiphilic triangular DNA origami is capable of solely stabilizing the W/O/W emulsion as well as serving as nanopore gates and affinity-based scaffold for constant release.

Plant volatile organic compound (E)-2-hexenal facilitates Botrytis cinerea infection of fruits by inducing sulfate assimilation.

Investigation into plant-fungal pathogen interactions is one of the most interesting fields in plant sciences. However, the roles of plant volatile organic compounds in the arms race are still largely unknown. Based on precise quantification of plant volatiles, we discovered that the plant volatile organic compound (E)-2-hexenal, at concentrations that were similar to or lower than those in tissues of strawberry and tomato fruits, upregulates sulfate assimilation in spores and hyphae of the phytopathogenic fungus Botrytis cinerea. This upregulation is independent of the types of sulfur sources in the plant and can be achieved in the presence of inorganic sulfate and organic sulfur sources. Using the fungal deletion mutants, we further found that sulfate assimilation is involved in the infection of tomato and strawberry fruits by B. cinerea, and that the severity of the disease is proportional to the sulfate content in the fruits. Both before and during the infection, (E)-2-hexenal induced utilisation of plant sulfate by B. cinerea facilitates its pathogenesis through enhancing its tolerance to oxidative stress. This work provides novel insights into the role of plant volatiles in plant-fungal pathogen interaction and highlights the importance of sulfur levels in the host in the prevention of grey mould disease.

Combined thrombogenic effects of vessel injury, pregnancy and procoagulant immune globulin administration in mice.

BACKGROUND: Pregnant women are at increased risk of thrombotic adverse events. Plasma derived immune globulin (IG) products, which are used in pregnancy for various indications, may contain procoagulant impurity activated coagulation factor XI (FXIa). Procoagulant IG products have been associated with increased thrombogenicity but their effect in pregnancy is unknown. METHODS: Late pregnant (gestation days 17-20) or early lactation (days 1-3) and control female mice were treated with IGs supplemented with human FXIa then subjected to ferric chloride (FeCl3) vessel injury. Occlusion of blood vessel was assessed by recording blood velocity in the femoral vein for 20 min using doppler ultrasound laser imaging. FXIa dose was selected by the ability to increase thrombin generation in mouse plasma in vitro. RESULTS: FXIa produced robust thrombin generation in mouse plasma ex vivo. Following FeCl3 injury, pregnant and non-pregnant mice receiving IG + FXIa exhibited faster reduction of blood velocity in femoral vein compared to IG alone or untreated controls. In vitro, thrombin generation in plasma samples collected after thrombosis in FXIa-treated animals was elevated and could be reduced by anti-FXI antibody. CONCLUSIONS: Our results suggest that intravenously-administered FXIa may contribute to thrombosis at the site of vascular injury in both pregnant and non-pregnant animals.

Nanomaterial-based biosensors for sensing key foodborne pathogens: Advances from recent decades.

Foodborne pathogen contamination has become a severe threat to human health. Traditional methods for foodborne pathogen detection have several disadvantages, including long detection time, low sensitivity, and low selectivity. The emergence of multiple excellent nanomaterials enables the construction of novel biosensors for foodborne pathogen detection. Based on the outstanding properties of nanomaterials, the novel biosensors possess the advantages of sensitivity, specificity, rapidity, accuracy, and simplicity. The present review comprehensively summarizes the advanced biosensors, including electrochemical, colorimetric, fluorescent, and surface enhanced Raman scattering biosensors for sensing key foodborne pathogens in recent decades. Furthermore, several issues are identified for further exploration, and possible directions for the development of biosensors are discussed.

Ultraviolet-C priming of strawberry leaves against subsequent Mycosphaerella fragariae infection involves the action of reactive oxygen species, plant hormones, and terpenes.

Ultraviolet-C (UV-C) radiation has been reported to induce defence responses to pathogens in growing crops and described as a new environmentally friendly method for disease control. However, whether the effect of the induced defence mechanisms will persist after the stress imposed by UV-C is alleviated and how these mechanisms interact with pathogen elicitors upon infection have not yet been investigated. Thus, we inoculated strawberry plants with Mycosphaerella fragariae, the causal agent of leaf spot disease, after 5 weeks of repeated UV-C irradiation treatment (cumulative dose of 10.2 kJ m-2 ) and investigated the alteration of gene expression and biochemical phenotypes. The results revealed that UV-C treatment had a significant impact on gene expression in strawberry leaves and led to the overexpression of a set of genes involved in plant-pathogen interaction. UV-C-treated leaves displayed a stronger response to infection after inoculation, with reduced symptoms and increases in accumulation of total phenolics and volatile terpenes, higher expression of pathogenesis-related proteins and the activity of several defence enzymes. This study presumptively describe, for the first time, the involvement of terpenes, reactive oxygen species, and abscisic acid, salicylic acid, jasmonic acid, and their transduction factors, in the network underpinning UV-C priming of growing crops for improved protection against pathogens.

Binding and neutralizing anti-cytomegalovirus activities in immune globulin products.

Congenital infection as well as infection of immunocompromised individuals by cytomegalovirus (CMV) can be associated with significant morbidity, mortality, and long-term adverse health outcomes. Assessment of anti-viral activity using appropriate assays is essential for ensuring safe and efficacious use of therapeutic CMV immune globulin (IG) products. In this study, we used commercial ELISA kits to compare anti-CMV antibody binding activity and avidity for lots of CMV-specific and normal IG products available in the US market. Additionally, neutralizing activity of IG products was measured against CMV strains (AD169wt131 or TB40E-GFP) in MRC-5 human fibroblasts and ARPE-19 human epithelial cells. Our data revealed that, regardless of the method, anti-CMV activity was higher in CMV IG lots we tested compared with normal IG lots; CMV binding activity was at least 4-fold higher, and neutralizing activity at least 2- and 3-fold higher for epithelial and fibroblast cells, respectively, in CMV IG lots compared with normal IG lots. Furthermore, anti-CMV activity values from all three methods (ELISA, neutralization in MRC-5 cells, and neutralization in ARPE-19 cells) were highly correlated, whereas avidity, although higher in CMV IG lots, did not correlate well with either binding or neutralizing activities.

5-Azacytidine accelerates mandarin fruit post-ripening and enhances lignin-based pathogen defense through remarkable gene expression activation.

5-Azacytidine (AZ) is a DNA methylation inhibitor that has recently demonstrated potential in regulating fruit quality through exogenous application. In this study, we treated mandarin fruits for 4-day storage. Noteworthy were the induced degreening and the enhanced citrus aroma of fruits under AZ treatment, involving the promotion of chlorophyll degradation, carotenoid biosynthesis, and limonene biosynthesis. Key genes associated with these processes exhibited expression level increases of up to 123.8 times. Additionally, AZ treatment activated defense-related enzymes and altered phenylpropanoid carbon allocation towards lignin biosynthesis instead of flavonoid biosynthesis. The expression levels of lignin biosynthesis-related genes increased by nearly 100 times, leading to fortified lignin that is crucial for citrus defense against Penicillium italicum. Currently, the underlying mechanisms of such intense AZ-induced changes in gene expressions remain unclear and further research could help establish AZ treatment as a viable strategy for citrus preservation.

The regulation of postharvest strawberry quality mediated by abscisic acid under elevated CO2 stress.

Elevated CO2 was a potential strategy for strawberry preservation. However, the regulatory mechanism remained unclear. In current study, transcriptome analysis showed that elevated CO2 played important roles in regulating strawberry fruit quality at the transcriptional level, and plant hormones metabolism at least partially involved in the regulatory process. Further, ABA was demonstrated to play important roles in the response to elevated CO2. Elevated CO2 inhibited the accumulation of ABA, which was 61% lower than that in control. Elevated CO2 repressed ABA synthesis by inhibiting NCED activity and the expression of FaNCED1/2, leading to the reduction of ABA accumulation as a result. Meanwhile, elevated CO2 also decreased ABA sensitivity by down-regulating FaSnRK2.4/2.6 and FaABI5 expression. The dual down-regulation of ABA signaling accounted for the regulation of fruit quality under elevated CO2 treatment. These results provide new insights into the mechanism of strawberry fruit response to elevated CO2.

Camellia Oleifera shells derived nano cellulose crystals conjugated with gallic acid as a sustainable Pickering emulsion stabilizer.

Lately, emulsions with low-fat and natural stabilizers are predominant. This study extracted the nano cellulose crystals (NCs) from Camellia Oleifera shells, and their gallic acid (GA) conjugates were synthesized by free-radical grafting. Pickering emulsions were prepared using NCs 1 %, 1.5 %, 2.5 %, and gallic acid conjugates NC-GA1, NC-GA2, and NC-GA3 as stabilizers. The obtained nano cellulose crystals exhibited 18-25 nm, -40.01 ±â€¯2.45 size, and zeta potential, respectively. The contact angle of 83.4° was exhibited by NC-GA3 conjugates. The rheological, interfacial, and microstructural properties and stability of the Pickering emulsion were explored. NC-GA3 displayed the highest absorption content of 79.12 %. Interfacial tension was drastically reduced with increasing GA concentration in NC-GA conjugates. Rheological properties suggested that the low-fat NC-GA emulsions showed a viscoelastic behavior, increased viscosity, gel-like structure, and increased antioxidant properties. Moreover, NC-GA3 displayed reduced droplet size and improved emulsion temperature and storage stability (28 days) against phase separation. POV and TBARS values were reduced with the NC-GA3 (P < 0.05). This work confirmed that grafting phenolic compounds on NCs could enhance bioactive properties, which can be used in developing low-fat functional foods. NC-GA conjugates can potentially fulfill the increasing demand for sustainable, healthy, and low-fat foods.

Development of a chitosan/pectin-based multi-active food packaging with both UV and microbial defense functions for effectively preserving of strawberry.

Multi-active food packaging was prepared for strawberry fruit preservation where epigallocatechin gallate (EGCG)-containing pectin matrix and natamycin (NATA)-containing chitosan (CS) matrix were utilized to complete LBL electrostatic self-assembly. The results showed that the physicochemical properties of the multi-active packaging were closely related to the addition of NATA and EGCG. It was found that NATA and EGCG were embedded in the CS/pectin matrix through intermolecular hydrogen bonding interactions. The CN/PE 15 % multi-active films prepared based on the spectral stacking theory formed a barrier to UV light in the outer layer, exhibited excellent NATA protection under UV light exposure conditions at different times, and provided long-lasting and sustained bacterial inhibition in the inner layer. In addition, the CN/PE 15 % multi-active packaging extended the shelf life of strawberry at room temperature compared with the control samples. In conclusion, the developed CN/PE 15 % packaging provided potential applications for multi-active food packaging materials.

Construction of self-assembled nano cellulose crystals/chitosan nanobubbles composite hydrogel with improved gallic acid release property.

Hydrogels are of great significance in the field of bioactive delivery. This study designed the self-assembly of gallic acid-loaded nano cellulose crystals/chitosan (NC/CS) hydrogels via Nano bubbles (NBs). NC/CS NBs 4:2 hydrogels improved the mechanical properties compared to those without NBs. The hardness of NC/CS (4:2) NBs hydrogels was greatly enhanced by 1.15 ± 0.05. The water-holding and swelling behavior can be tuned at different ratios. NC/CS NBs (4:2) showed the electrostatic interaction analyzed by FTIR, XRD, and XPS. SEM results displayed smoother and smaller pores along dense networks promoted by NBs. The antioxidant activity of hydrogels was increased by adding NBs (P < 0.05). In vitro and vivo release activity of gallic acid was higher in simulated intestinal fluid (SIF) at 4:2, depicting the controlled release mechanism. Thus, current work revealed that NBs and low concentrations of NC can be self-assembled with chitosan chains, producing a highly compact hydrogel structure.

Linalool as a key component in strawberry volatile organic compounds (VOCs) modulates gut microbiota, systemic inflammation, and glucolipid metabolism.

Strawberries are rich in volatile organic compounds (VOCs), which are increasingly recognized as potential health-promoting factors. This study explored the health effects of intaking strawberry VOC extract and its dominant terpene, linalool. The results indicated that linalool and strawberry VOC extract significantly increased the abundance of beneficial bacteria like Lactobacillus, Bacillus, and Alistipes in mice. Moreover, mice treated with linalool and strawberry VOC extract exhibited notable reductions in serum pro-inflammatory cytokines; interleukin IL-6 decreased by 14.5% and 21.8%, respectively, while IL-1ß levels decreased by 9.6% and 13.4%, respectively. Triglyceride levels in the treated groups were reduced by 38.3% and 58.1%, respectively. Spearman's correlation analysis revealed that Bacillus negatively correlated with glucolipid indices, and Bifidobacterium and Dubosiella negatively correlated with inflammatory factors, indicating that alterations in glucolipid metabolism might be associated with the regulation of gut microbiota and systemic inflammation.

Valorization and protection of anthocyanins from strawberries (Fragaria×ananassa Duch.) by acidified natural deep eutectic solvent based on intermolecular interaction.

This study introduces an innovative approach for the valorization and protection of anthocyanins from 'Benihoppe' strawberry (Fragaria × ananassa Duch.) based on acidified natural deep eutectic solvent (NADES). Choline chloride-citric acid (ChCl-CA, 1:1) was selected and acidified to enhance the valorization and protection of anthocyanins through hydrogen bond. The optimal conditions (ultrasonic power of 318 W, extraction temperature of 61 °C, liquid-to-solid ratio of 33 mL/g, ultrasonic time of 19 min), yielded the highest anthocyanins of 1428.34 µg CGE/g DW. UPLC-Triple-TOF/MS identified six anthocyanins in acidified ChCl-CA extract. Stability tests indicated that acidified ChCl-CA significantly increased storage stability of anthocyanins in high temperature and light treatments. Molecular dynamics results showed that acidified ChCl-CA system possessed a larger diffusion coefficient (0.05 m2/s), hydrogen bond number (145) and hydrogen bond lifetime (4.38 ps) with a reduced intermolecular interaction energy (-1329.74 kcal/mol), thereby efficiently valorizing and protecting anthocyanins from strawberries.

Azacytidine-induced hypomethylation delays senescence and coloration in harvested strawberries by stimulating antioxidant enzymes and modulating abscisate metabolism to minimize anthocyanin overproduction.

DNA methylation is increasingly known to be essential for fruit ripening and senescence. Currently, 5-azacytidine (AZ) was selected as an effective demethylator and it successfully shaped the genomic hypomethylation in harvested strawberries. This was associated with the reprogramming of global gene expressions, which influenced downstream food traits. The alleviation of decay and softening, as well as the deceleration of soluble solid accumulation, were included. Coloration was also delayed as a result of the AZ-induced hypomethylation. Our examinations of anthocyanin biosynthesis and transport revealed that they were markedly minimized, which was probably involved with the decreased abscisate level and its weakened metabolism. Additionally, under AZ, the retarded postharvest senescence process was observed and it might be induced by the inhibited ROS accumulation accompanying the peroxidase and catalase activities alteration. Overall, these findings underlined the importance of methylation in strawberries and suggested the potential role of epigenetic regulators in the postharvest industry.