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Abstract Background Nipah virus (NiV) is a zoonotic pathogen that poses a significant threat because of its wide host range, multiple transmission modes, high transmissibility, and high mortality rates, affecting both human health and animal husbandry. In this study, we developed a one-step reverse transcription droplet digital PCR (RT-ddPCR) assay that targets the N gene of NiV. Results Our RT-ddPCR assay exhibited remarkable sensitivity, with a lower limit of detection of 6.91 copies/reaction. Importantly, it displayed no cross-reactivity with the other 13 common viruses and consistently delivered reliable results with a coefficient of variation below 10% across different concentrations. To validate the effectiveness of our RT-ddPCR assay, we detected 75 NiV armored RNA virus samples, mimicking real-world conditions, and negative control samples, and the RT-ddPCR results perfectly matched the simulated results. Furthermore, compared with a standard quantitative real-time PCR (qPCR) assay, our RT-ddPCR assay demonstrated greater stability when handling complex matrices with low viral loads. Conclusions These findings show that our NiV RT-ddPCR assay is exceptionally sensitive and provides a robust tool for quantitatively detecting NiV, particularly in stimulated field samples with low viral loads or complex matrices. This advancement has significant implications for early NiV monitoring, safeguarding human health and safety, and advancing animal husbandry practices.

Vitamin B2 is an essential water-soluble vitamin. For most prokaryotes, a bifunctional enzyme called FAD synthase catalyzes the successive conversion of riboflavin to FMN and FAD. In this study, the plasmid pNEW-AZ containing six key genes for the riboflavin synthesis was transformed into strain R2 with the deleted FMN riboswitch, yielding strain R5. The R5 strain could produce 540.23 ± 5.40 mg/L riboflavin, which was 10.61 % higher than the R4 strain containing plasmids pET-AE and pAC-Z harboring six key genes. To further enhance the production of riboflavin, homology matching and molecular docking were performed to identify key amino acid residues of FAD synthase. Nine point mutation sites were identified. By comparing riboflavin kinase activity, mutations of T203D and N210D, which respectively decreased by 29.90 % and 89.32 % compared to wild-type FAD synthase, were selected for CRISPR/Cas9 gene editing of the genome, generating engineered strains R203 and R210. pNEW-AZ was transformed into R203, generating R6. R6 produced 657.38 ± 47.48 mg/L riboflavin, a 21.69 % increase compared to R5. This study contributes to the high production of riboflavin in recombinant E. coli BL21.

ABSTRACT: Indicating hydrogels have shown the advantages of being fast, sensitive, and real-time in demonstrating the freshness of aquatic products due to their noticeable color change. In this work, an anti-freezing hydrogel embedded with pH-sensitive alizarin was developed as an original colorimetric indicator for monitoring the corruption of aquatic products at low temperatures. The anti-freezing hydrogel was prepared from 2-carboxyethyl acrylate, [2-(methacryloyloxy)ethyl]-trimethylammonium chloride, and 2-hydroxyethyl methacrylate monomers with triethylene glycol dimethacrylate as cross-linking agent. The hydrogel showed excellent anti-freezing capability, which was further incorporated with the pH-sensitive dye alizarin to gain the indicating capability. When applied in the indication of the freshness of salmon under low-temperature storage, it was found that the color changes of the indicator corresponded with the total volatile basic nitrogen contents of salmon, the correlation coefficient of which was 0.959 6. These results indicated the application potential of the hydrogels as freshness indicators during low-temperature storage or cold-chain transportation.

Glycosylation is a post-transcriptional modification that can influence protein structure and function, yet the glycosylation of the major shellfish allergen, sarcoplasmic calcium-binding protein (SCP), remains poorly understood. In this study, we characterized the glycosylation profile of SCP and explored the role of N-glycans in its allergenicity. Tandem mass spectrometry (MSn) revealed seven distinct N-glycans conjugated to SCP and provided detailed structural identification. ELISA and mast cell degranulation assay using sera from allergic individuals demonstrated that SCP exhibits significant allergenicity, which was markedly reduced following deglycosylation. Additionally, through the integration of various bioinformatics approaches, seven potential epitopes of SCP were predicted, and two glycosylated conformational epitopes were identified. In summary, this study elucidated the detailed glycosylation pattern and allergenic properties of SCP, offering a theoretical foundation for future research on the impact of glycosylation on allergenicity and contributing to the development of hypoallergenic products.

Specific algal polysaccharides exhibit significant anti-allergic activity. B cell class switch recombination (CSR) is a crucial step in food allergies, however, the role of polysaccharides in regulating CSR remains unclear. To investigate the regulation of B cell CSR by algal polysaccharides, an in vitro IgE-type CSR cell model was used to screen for active algal polysaccharides, and four active polysaccharides were identified. In a food allergy mouse model, Undaria pinnatifida polysaccharides (UPP) and phosphoryl oligosaccharides (POS) suppressed allergic responses and reduced the proliferation of IgE+ B cells. Transcriptome sequencing of B cells identified LCN2 as a potential target of POS, and inhibition of LCN2 blocked the activity of POS on CSR. These findings demonstrated the efficacy of POS in regulating B cell CSR and alleviating allergic responses and revealed the underlying mechanisms. This work provided data and theoretical support for the development of polysaccharide-based functional foods for individuals with allergies.

Biogenic amine is one of the main categories of hazardous compounds in meat and meat products, making its detection methods vital for the assurance of edible safety. In this sense, many biogenic amine detection techniques such as chromatographic, electrophoretic, and electrochemical methods have been developed, which play an irreplaceable role in ensuring the safety of meat and meat products. Due to the increasing demand for fast and on-site detection techniques, visual detection methods have been gradually developed compared with non-visual methods such as chromatography and electrophoresis. Herein, we comprehensively review the mechanism and the latest progress of these biogenic amine detection methods; besides, we put forward the prospects for the future development of biogenic amine detection techniques, with a view to providing support for the establishment of more accurate and efficient detection, prevention and control strategies of biogenic amines.

N-glycans in many proteins are of great concern because of their strong association with food allergies. Triticum aestivum (bread wheat), a major food crop, is known as one of the “Big Eight” allergenic groups. However, little research has been done about N-glycans in wheat glycoproteins. In this study, a soluble wheat glycoprotein was purified from wheat and further identified as globulin-1 S allele (GSA). The wheat GSA displayed significant IgE-binding activity. Moreover, one N-glycosylation site and 6 kinds of N-glycans were identified by mass spectrometry, including 3 high mannose types and 3 complex types. Furthermore, the IgE-binding activity of wheat GSA is proved to be reduced by the removal of N-glycan, thermal treatment (temperatures > 80 °C), and strong acidic treatment (pH 3.0). These findings would provide a better understanding of the effects of N-glycosylation, thermal treatment, and acidic treatment on the molecular characteristics of GSA, and further provide new insights into the development of hypoallergenic wheat products.

As one of the most important cereals, wheat (Triticum aestivum) has high nutritional value and is widely cultivated in China. However, wheat can cause severe allergic reactions, and a growing number of people are developing allergies to Chinese wheat. Low molecular weight glutenin (LMW-GS), an important allergen in susceptible populations, is responsible for celiac disease and wheat contacts dermatitis. In this study, LMW-GS was highly purified from Chinese wheat (Xiaoyan 6) and further identified and characterized. In addition, 8 peptides were predicted efficiently by 5 immunological tools, among which five peptides showed significant immunoglobulin E (IgE) binding abilities. Two specific epitopes were found to be in the non-conserved region of the amino acid sequence of LMW-GS, which was speculated to be the specific epitope of Chinese wheat. This systematic research of LMW-GS may provide new insights into the prevention of wheat allergy and development of hypoallergenic wheat products.

Simple yet efficient detection methods for food allergens are in urgent need to help people avoid the risks imposed by allergenic food. In this work, a polydopamine (PDA)-based fluorescent aptasensor was developed to detect arginine kinase (AK), one of the major allergens in shellfish. The aptamer towards AK was firstly selected via systematic evolution of ligands by exponential enrichment method and labeled with fluorescein amidite (FAM) to build a fluorescence resonance energy transfer (FRET) system with PDA particles. Polyethylene glycol (PEG) was employed to construct an antifouling surface for the aptasensor to eliminate food matrix interferences. With the presence of AK, the PDA-based aptasensor exhibited elevated fluorescent signals as the FAM-labeled aptamer bound to AK and detached from the PDA particles. The aptasensor showed great stability and resistance to nonspecific interference of background proteins and had a limit of detection (LOD) of 0.298 μg/mL. The proposed aptasensor was further proved to be feasible for quantitative analysis of AK in nine species of shrimps and five commercial processed products, which indicated its high potential in tracing the presence of AK in complex aquatic products.

Porphyra polysaccharide is a special kind of nutrient showing multiple physiological functions including regulating cell proliferation, but the detailed mechanisms are not fully revealed, impairing its further development and applications. This work was to purify and characterize the Porphyra haitanensis polysaccharide (PH), investigate its physiological function, and demonstrate the underlying mechanisms. The purified PH was first characterized by Fourier-transform infrared spectroscopy. Then an intestinal epithelial cell model was established, in which PH significantly suppressed cell hyperplasia. Specifically, PH activated the Hippo/YAP pathway, which subsequently activated mTOR pathway, however mTOR activated Hippo in the absence of PH. Moreover, both the inhibition of Hippo by YAP1 knock-down and the suppression of mTOR by rapamycin impaired PH function. These results indicated that PH attenuated hyperplasia activity by remodeling the cross-talk between Hippo/YAP and mTOR pathways, which revealed potential targets and approaches for treating hyperplasia-related diseases and provided novel ways to utilize P. haitanensis as well as other related functional foods.

Bacillus coagulans, as a probiotic, has attracted much attention in recent years for its unique probiotic characteristics. In view of this, the current research status and future development trend at home and abroad are reviewed, based on the in-depth analysis of the probiotic properties of Bacillus coagulans. This paper reveals the application mechanism of Bacillus coagulans in the food field from three aspects: Digestive tract microecology, digestion and absorption of nutrients and immune system. Meanwhile, this paper foresees the future research hotspots in this field, aiming to support the wide application of Bacillus coagulans in food industry and help the sustainable development of probiotic industry.

D-tryptophan is a special kind of nonprotein amino acid showing multiple physiological functions, but the detailed mechanisms are not fully revealed, impairing its further development and applications. This work was to investigate D-tryptophan physiological function and demonstrate the underlying mechanisms. D-tryptophan suppressed HaCaT cell proliferation but increased cell migration. Specifically, D-tryptophan decreased E-cadherin and increased Snail, Twist, and Slug expression, resulting in the development of an epithelial-mesenchymal transitions (EMT) phenomenon. Moreover, D-tryptophan promoted the expression of transforming growth factor-β (TGF-β) 1, and Smad4 knockout damages D-tryptophan's ability. These results indicated that D-tryptophan stimulated HaCaT cells to produce TGF-β1 and thus activated the TGF-β/Samd pathway, resulting in the triggering of EMT. This study revealed the molecular mechanisms of D-tryptophan activity, provided D-tryptophan as a potential approach for cancer treatment, wound healing, organ development and other relevant applications.

Allergy has become a public health problem worldwide, but effective diagnostic and therapeutic approaches are limited currently. Amino acids are essential macronutrients that potentially participated in the allergy process. This work aimed to investigate whether amino acids can be applied as a mediator for allergy diagnosis and therapy. Two cohort studies were performed to investigate the correlation between fecal amino acids and allergy responses, and a spleen cell model was used to validate the role of amino acids in regulating allergy. In a cohort study with 193 volunteers, fecal proline was found to be negatively correlated with serum IgE, and detailed data analysis revealed that people with high-IgE-mediated allergy had decreased odds of high intestinal proline. In another cohort study with distinct allergic and non-allergic individuals, proline concentration was significantly lower in the allergic group. Daily diet and metagenomics analysis showed that the proline intake and microbiota amino acid metabolism were not significantly different, implying that the body’s proline metabolism might be different between allergic and non-allergic individuals. Furthermore, the spleen cell model demonstrated that proline specifically targeted Th2 and Treg activity. Overall, this work revealed a tight correlation between gut proline and serum IgE, indicating proline as a promising biomarker and a potential therapeutic method for allergic diseases.

Rice bran is a “treasure house of natural nutrition”. Even so, utilization of rice bran is often ignored, and this has resulted in the wastage of nutrients. Polysaccharides are one of the active substances in rice bran that have gained widespread attention for their antioxidant, antitumor, immune-enhancing, antibacterial, and hypoglycemic properties. This review summarizes the extraction methods, structural characterization, bioactivity, and application of rice bran polysaccharides that have been developed and studied in recent years, laying a foundation for its development into foods and medicines. In addition, we also discuss the prospects for future research on rice bran polysaccharides.

Food allergy is a worldwide food safety problem with increasing prevalence. Developing novel approaches for food allergy investigations is the basis for controlling food allergies. In this work, a 3-dimensional (3D) intestinal cell model was established to simulate the intestinal mucosal immune system. Gut epithelial cell line CMT93 was cultured in a transwell insert above dendritic cells (DCs) isolated from mouse spleen and stimulated by egg allergen ovalbumin (OVA), then the conditioned media of DCs was transferred to T cells isolated from mouse spleen. The allergy-related indexes of each cell type were determined by qPCR and flow cytometry. Then the TAZ gene was knocked down in the CMT93 cells and the role of the Hippo pathway in OVA-induced food allergy was investigated. The 3D intestinal cell model showed more significant and more specific allergic responses than conventional cell models and is more convenient to be manipulated than the mouse models. This model is an ideal tool for food allergy investigations and would facilitate studies in the field of intestinal mucosal immunity.

The global tendency towards financial integmtion means that secuTities transactions dre often transnational. In China, such transactions are covered by the Securities Law; with the enactment in March 2020 of the additional art 2, pam 4, China took the first step towards the extraterritorial application of this law. This article discusses the theoretical basis for extraterritorial jurisdiction and examines the problems posed by the new article. It addresses the limitation of the ambiguous "effect test", the way in which the article is formulated, and the construction of the whole process from establishing the jurisdiction to law application. In development for over 40 years, the relatively mature and comprehensive extratel-ritorial jurisdiction system of the United States is used as a reference. This study proposes implementing a clearer effect test revolving around theideas of "certainty", "directness" and "reasonable predictability"; it also suggests relevant amendments to other related laws. [ABSTRACT FROM AUTHOR]