An Evaluation of the Sensitivity and Applicability of a Droplet Digital Polymerase Chain Reaction Assay to Simultaneously Detect Pseudomonas aeruginosa and Pseudomonas fragi in Foods.

Achieving effective control over microbial contamination necessitates the precise and concurrent identification of numerous pathogens. As a common bacterium in the environment, Pseudomonas is rich in variety. It not only has pathogenic strains, but also spoilage bacteria that cause food spoilage. In this research, we devised a remarkably sensitive duplex droplet digital PCR (dddPCR) reaction system to simultaneously detect pathogenic Pseudomonas aeruginosa (P. aeruginosa) and spoilage Pseudomonas fragi (P. fragi). By employing comparative genomics, we identified four genes of P. fragi. Through a specific analysis, the RS22680 gene was selected as the detection target for P. fragi, and the lasR gene was chosen for P. aeruginosa, which were applied to construct a dddPCR reaction. In terms of specificity, sensitivity and anti-interference ability, the constructed dddPCR detection system was verified and analyzed. The assay showed excellent sensitivity and applicability, as evidenced by a limit of detection of 100 cfu/mL. When the concentration of natural background bacteria in milk or fresh meat was 100 times that of the target detection bacteria, the method was still capable of completing the absolute quantification. In the simulation of actual sample contamination, P. aeruginosa could be detected after 3 h of enrichment culture, and P. fragi could be detected after 6 h. The established dddPCR detection system exhibits exceptional performance, serving as a foundation for the simultaneous detection of various pathogenic bacteria in food products.

Efficacy of repeated low-level red-light therapy in the prevention and control of myopia in children.

OBJECTIVE: In this study, we aimed to determine how different factors influence the effectiveness of repeated low-level red-light (RLRL) therapy in preventing and treating myopia in children. METHODS: Between June 2022 and April 2023, 336 children who visited our hospital due to myopia or significant decreases in hyperopia reserve were enrolled. The children were treated twice daily for three minutes with a head-mounted low-level red-light (single wavelength of 650 nm) therapeutic device. Each of the two treatment sessions was separated by at least four hours. The axial lengths and diopters of the children's eyes were compared before and three months after treatment, and the effects of gender, age, and baseline diopter on the efficacy of RLRL therapy were analyzed. RESULTS: Following three months of treatment, the average axial length of the eyes decreased by 0.031 mm. The condition was better for the boys than for girls, but the difference was not statistically significant. As age increased (F = 8.112, P = 0.000) or as the absolute value of baseline myopia degree increased (F = 10.51, P = 0.000), axial lengths of the eyes tended to decrease. The spherical equivalent refraction (SER) of children decreased by an average of 0.012 ± 0.355D. The condition was better for the boys than for girls, but the difference was not statistically significant. SER increased in the direction of hyperopic drift as age increased (F = 2.48, P = 0.031), or as the absolute value of baseline myopia degrees increased (F = 6.835, P = 0.000). There were no obvious side effects following the treatment. CONCLUSION: This study showed that RLRL therapy is a potential efficient, easily operable, and practically feasible method for the prevention and control of myopia.

Quorum sensing: cell-to-cell communication in Saccharomyces cerevisiae.

Quorum sensing (QS) is one of the most well-studied cell-to-cell communication mechanisms in microorganisms. This intercellular communication process in Saccharomyces cerevisiae began to attract more and more attention for researchers since 2006, and phenylethanol, tryptophol, and tyrosol have been proven to be the main quorum sensing molecules (QSMs) of S. cerevisiae. In this paper, the research history and hotspots of QS in S. cerevisiae are reviewed, in particular, the QS system of S. cerevisiae is introduced from the aspects of regulation mechanism of QSMs synthesis, influencing factors of QSMs production, and response mechanism of QSMs. Finally, the employment of QS in adaptation to stress, fermentation products increasing, and food preservation in S. cerevisiae was reviewed. This review will be useful for investigating the microbial interactions of S. cerevisiae, will be helpful for the fermentation process in which yeast participates, and will provide an important reference for future research on S. cerevisiae QS.

Effect of ultrasonic degradation on the structural feature, physicochemical property and bioactivity of plant and microbial polysaccharides: A review.

With the bioactivities of antioxidant, anti-bacteria, anti-inflammation, immune regulation, antitumor and anti-coagulation, plant and microbial polysaccharides have been widely used in foods, medicine and cosmetics. However, how structure features affect the physicochemical property and bioactivity of plant and microbial polysaccharides is still unclear. Ultrasonic degradation usually degrades or modifies plant and microbial polysaccharides with different physicochemical properties and bioactivities by affecting their chemical or spatial structures via mechanical bond breaking and cavitation effects. Therefore, ultrasonic degradation might be an effective strategy for producing bioactive plant and microbial polysaccharides and analyzing their structure-function relationship. Present review summarized the influence of ultrasonic degradation on structural feature, physicochemical property and bioactivity of plant and microbial polysaccharides. Moreover, further problems need to be paid attention to during the application of ultrasonication for plant and microbial polysaccharides degradation are also recommended. Overall, present review will provide an efficient method for producing enhanced bioactive plant and microbial polysaccharides and analyzing their structure-activity relationship based on ultrasonic degradation.

Comprehensive bioinformatics analysis and molecular validation of lncRNAs-mediated ceRNAs network in schizophrenia.

AIMS: The present study aimed to investigate how Schizophrenia (SCZ)-specific long non-coding RNAs (lncRNAs) served as competing endogenous RNAs (ceRNAs) to modulate the biological functions and pathways involved in the pathogenesis of SCZ. MAIN METHODS: Microarray dataset (GSE54913) was obtained from Gene Expression Omnibus (GEO) database. Differently expressed (DE) lncRNAs and mRNAs were identified by "limma" package. The binding miRNAs of lncRNAs and target mRNAs of shared miRNAs were predicted by miRcode, miRDB, miRTarbase and targetscan databases. Following the ceRNAs theory, interaction network was established and visualized with the cytoscape. Functional enrichment analysis uncovered the concentrated functions and signaling pathways that may be associated with SCZ progression. Protein-protein interaction (PPI) analysis was utilized to determine hub genes. Quantitative real-time PCR (qRT-PCR) and receiver operating characteristic curve (ROC) were performed to evaluate the expression and diagnostic value of ceRNAs members, respectively. KEY FINDINGS: DElncRNAs and DEmRNAs were initially screened from GSE54913 to construct the SCZ-related ceRNAs network with 42 nodes and 53 edges. Functional enrichment analysis revealed that ceRNAs members appeared to be highly correlated with transcription factor activation, cell replication and tumor-related pathways. Once validated, a significant ceRNAs subnetwork was proposed as being implicated in the pathogenesis of SCZ. ROC analysis indicated that SCZ-related ceRNAs members may be sensitive diagnostic biomarkers for SCZ. SIGNIFICANCE: The significant SCZ-related ceRNAs subnetworks (lncRNA-C2orf48A/hsa-miR-20b-5p,-17-5p/KIF23, FOXJ2) may represent promising predictive and diagnostic biomarkers and provide novel insights into the mechanism by which lncRNAs act as microRNA sponges and contribute to the pathogenesis of SCZ.

Novel processing strategies to enhance the bioaccessibility and bioavailability of functional components in wheat bran.

Dietary fiber, polysaccharides and phenols are the representative functional components in wheat bran, which have important nutritional properties and pharmacological effects. However, the most functional components in wheat bran exist in bound form with low bioaccessibility. This paper reviews these functional components, analyzes modification methods, and focuses on novel solid-state fermentation (SSF) strategies in the release of functional components. Mining efficient microbial resources from traditional fermented foods, exploring the law of material exchange between cell populations, and building a stable self-regulation co-culture system are expected to strengthen the SSF process. In addition, emerging biotechnology such as synthetic biology and genome editing are used to transform the mixed fermentation system. Furthermore, combined with the emerging physical-field pretreatment coupled with SSF strategies applied to the modification of wheat bran, which provides a theoretical basis for the high-value utilization of wheat bran and the development of related functional foods and drugs.

Isolation, Mutagenesis, and Organic Acid Secretion of a Highly Efficient Phosphate-Solubilizing Fungus.

The highly effective phosphate-solubilizing microorganisms are significant for making full use of the potential phosphorus resources in the soil and alleviating the shortage of phosphorus resources. In this study, a phosphate-solubilizing fungus was isolated from wheat and cotton rhizosphere soils in the lower reaches of the Yellow River in China and was identified as Penicillium oxalicum by morphological and ITS sequencing analysis. In order to obtain a fungus with more efficient phosphorus solubilization ability, we tested three positive mutant strains (P1, P2, and P3) and three negative mutant strains (N1, N2, and N3) through low-energy nitrogen ion implantation mutagenesis. Compared with the parental strain, the phosphate-solubilizing capacity of P1, P2, and P3 was enhanced by 56.88%, 42.26%, and 32.15%, respectively, and that of N1, N2, and N3 was weakened by 47.53%, 35.27%, and 30.86%, respectively. Compared with the parental strain, the total amount of organic acids secreted significantly increased in the three positive mutant strains and decreased in the negative mutant strains; the pH of culture medium was significantly lower in the positive mutant strains and higher in the negative mutant strains. The capacity of phosphate-solubilizing fungus to secrete organic acids and reduce the growth-medium pH was closely related to its phosphate-solubilizing ability. The changes in the amount of organic acids secreted by mutants can alter their acidification and phosphate-solubilizing capacity. In conclusion, this study offers a theoretical basis and strain materials for the exploration and application of phosphate-solubilizing fungi.

L-Carnitine and Acetyl-L-Carnitine: Potential Novel Biomarkers for Major Depressive Disorder.

The lack of biomarkers greatly limits the diagnosis and treatment of major depressive disorder (MDD). Endogenous L-carnitine (LC) and its derivative acetyl-L-carnitine (ALC) play antidepressant roles by improving brain energy metabolism, regulating neurotransmitters and neural plasticity. The levels of ALC in people and rodents with depression are significantly reduced. It is necessary to determine whether serum LC and ALC might be used as novel biomarkers for the diagnosis of MDD. Here, ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was used to determine the concentration of LC and ALC in the serum of healthy controls and patients with MDD; among the latter, in patients who were responsive (effective group) and non-responsive (ineffective group) after 2 weeks of treatment. The diagnostic value of serum LC and ALC for MDD was assessed. Compared with healthy controls, the serum LC and ALC concentrations in patients with MDD were significantly decreased (P < 0.001). Pearson correlation analysis shows that the HDRS-24 score was negatively associated with serum ALC (r = -0.325, P = 0.007). Receiver operating characteristic (ROC) analysis revealed an area under the curve (AUC) of 0.801 with 83.1% sensitivity and 66.3% specificity for LC, and an AUC of 0.898 with 88.8% sensitivity and 76.4% specificity for ALC, differentiating patients with MDD from healthy controls. Furthermore, the concentration of LC and ALC in patients with depression was significantly increased in the effective treatment group, and no significant change was observed in the ineffective treatment group. These results suggest that serum LC and ALC may be novel biomarkers for the diagnosis of MDD.

Providing a view for toxicity mechanism of tetracycline by analysis of the connections between metabolites and biologic endpoints of wheat.

Metabolomics is an implement for testing the toxicity of antibiotics, and provides a comprehensive view of the overall response to stress; however, the connections between metabolites and biologic endpoints keep unclear in response to antibiotics. In this study, wheat seeds were exposed to tetracycline for 5 days. The results proved that tetracycline restrained growth, reduced chlorophyl and carotinoid contents and cell permeability, and increased reactive oxygen species (ROS) levels and malondialdehyde (MDA) content. Orthogonal partial least squares (OPLS) was used to analyze the connections between metabolites and biologic endpoints, which discovered that 11 metabolic pathways were significantly affected by tetracycline, and amino acid metabolism could largely apply to root growth and ROS accumulation, while carbohydrate metabolism could have a ruling effect on tetracycline-induced cell permeability. 13 metabolites all played active roles in mediating tetracycline's effects on root length, root fresh weight and cell permeability but had no significant effects on ROS levels. The majority of metabolites with passive effects on root length, root fresh weight and cell permeability had active effects on ROS levels. These results offer a view about stress reaction of wheat to tetracycline.

Efficient biorefinery of whole cassava for citrate production using Aspergillus niger mutated by atmospheric and room temperature plasma and enhanced co-saccharification strategy.

BACKGROUND: The non-grain crop cassava has attracted intense attention in the biorefinery process. However, efficient biorefinery of whole cassava is faced with some challenges due to the existence of strain inhibition and refractory cellulose during the citrate production process. RESULTS: Here, a novel breeding method - atmospheric and room temperature plasma (ARTP) - was applied for strain improvement of citrate-producing strain Aspergillus niger from whole cassava. The citrate yield of the mutant obtained using ARTP mutagenesis increased by 36.5% in comparison with the original strain. Moreover, citric acid fermentation was further improved on the basis of an enhanced co-saccharification strategy by supplementing glucoamylase and cellulase. The fermentation efficiency increased by 35.8% with a 17.0 g L-1 reduction in residual sugar on a pilot scale. CONCLUSIONS: All these results confirmed that a combination of the novel breeding method and enhanced co-saccharification strategy could be used to efficiently refine whole cassava. The results also provide inspiration for the production of value-added products and waste disposal in agro-based industries. © 2021 Society of Chemical Industry.

Fine regulation of the starch liquefaction process and its application in the production of citric acid.

Citric acid (CA), generally fermented from the starchy material, has attracted intense attention because of its wide applications in many aspects. However, the traditional starchy-liquefaction process based on the dextrose equivalent value and iodine-testing method is inappropriate as it hinders the subsequent CA fermentations. Here, a novel method of evaluating the starch liquefaction in the CA production process was established. Firstly, dextrin samples with the molecular weight (Mw) narrow distribution were prepared by alcohol fractional precipitation. Glucoamylase (GM) from the culture of CA-producing strain Aspergillus niger was purified. Then, the structure-activity relationship between the dextrin and GM was analyzed. Results demonstrated that the Mw of liquefied components aggregated in the range of 1.4-1.9 kDa could improve the efficiency of simultaneous saccharification and fermentation process. CA production rate and total sugar uptake rate were evidently improved with residual total sugar decreasing by 10.8% and fermentation efficiency enhanced by 21.1% in 9 h shorter fermentation time. All these results confirmed that fine regulation of the starch liquefaction based on the Mw characteristics was feasible and effective to improve the CA fermentation. Our proposed strategy could also be useful for other fermentations and sugar industry involving the starchy material.

Potential roles of telomeres and telomerase in neurodegenerative diseases.

Telomeres, protective DNA-protein complexes at the end of eukaryotic linear chromosomes, play pivotal roles in the maintenance of genomic stability during cell division. When telomeres are severely shortened, cells stop dividing and die, consequently leading to tissues degeneration. Concretely, replicative senescence and genomic damage are generally accompanied with telomere shortening, which may be a potential contributor in the pathogenesis of neurological disorders. Regardless of occasional negative findings, accelerated telomere erosion is routinely found in neurodegenerative diseases and has been believed to be positively correlated with the severity of neurodegenerative diseases. As considerable knowledge of telomeres and telomerase continues to accumulate, telomerase is increasingly being recognized as a promising therapeutic target for neurodegenerative disease. Until now, strong evidence has accumulated that activated telomerase is responsible for telomere elongation that may be sufficient to prevent "mother cells" from replicative aging, and besides, telomerase activators exhibit remarkable neuroprotective effects through the prolongation of telomere length and the promotion of neuronal survival as well as proliferation. Therefore, a consensus is emerging that the activation of telomerase, promoted by peptides, natural herbal extracts, small molecules compounds and others, represents a novel promising treatment strategy for neurodegenerative diseases.

H2S induces NO in the regulation of AsA-GSH cycle in wheat seedlings by water stress.

In current study, we investigated the relationship between hydrogen sulfide (H2S) and nitric oxide (NO) in the regulation of ascorbate-glutathione (AsA-GSH) cycle in wheat seedlings by water stress. Findings showed that water stress significantly stimulated the production of H2S and NO, the transcript levels and activities of enzymes in AsA-GSH cycle, as well as malondialdehyde (MDA) production and electrolyte leakage, but significantly decreased AsA/DHA and GSH/GSSG. Meanwhile, water stress significantly decreased plant height and dry biomass. Except MDA and electrolyte leakage, above changes induced by water stress were reversed by H2S synthesis inhibitor aminooxyacetic acid (AOA) and NO synthesis inhibitor NG-nitro-L-arginine methyl ester (L-NAME). However, AOA and L-NAME significantly enhanced MDA production and electrolyte leakage, which further decreased plant height and dry biomass of wheat seedlings under water stress. Application of exogenous H2S donor sodium hydrosulfide (NaHS) to AOA-treated plants and application of exogenous NO donor sodium nitroprusside (SNP) to L-NAME-treated plants reversed above effects of AOA and L-NAME, respectively. Application of L-NAME plus water stress significantly decreased NO production induced by water stress. However, application of L-NAME plus water stress had no obvious influence on H2S production induced by water stress, while application of AOA plus water stress significantly reduced the production of H2S and NO induced by water stress. Current findings suggested that H2S acted upstream of NO in the regulation of AsA-GSH cycle in wheat seedlings by water stress.

High-efficient production of citric acid by Aspergillus niger from high concentration of substrate based on the staged-addition glucoamylase strategy.

Citric acid (CA), an important platform-compound, has attracted much attention because of its broad applications and huge market demand. To solve high residual sugar at the fermentation end, we put forwarded strategy of pre-saccharification and then fermentation. Results showed that the residual total sugar decreased by 10.4% and the productivity increased by 4.0% and initially high glucose inhibited cell growth. Furthermore, commercial glucoamylase with high low-pH stability was proposed to staged-add in the fermentation process, which timely compensated enzyme loss, ensuring the glucose supply rate. The fermentation productivity was evidently enhanced by 13.3% with residual total sugar decreasing by 31.3%, simplifying the subsequent product separation and extraction process. Our results confirmed that staged-addition glucoamylase strategy was feasible to effective production of CA.

Pellet-dispersion strategy to simplify the seed cultivation of Aspergillus niger and optimize citric acid production.

Citric acid (CA) as an extremely important platform compound has attracted intense attention due to wide applications and huge markets. Here, we proposed a novel method, using pellet inoculation to replace spores, and constructed the seed recycling cultivation process, effectively avoided the longtime (spore preparation 30 days) of seed culture (including spores germination 12 h) in the traditional batch-fermentation. On this basis, using pellet-dispersion strategy, the bottleneck caused by the mycelium structure was overcome, with the seed restoring high cell-viability with CA titer (11.0 g/L) even in the eighth batch compared to that in the control (4.6 g/L). The optimum morphology of these recycling cultured seeds for CA production was dispersed pattern rather than pellets. And the CA production was 130.5 g/L on average in 5 L five-conjoined-fermenters recycling eight batches, especially increasing 3.1 g/L compared with the control. To our knowledge, this is the first that reported the application of these strategies in effective production of CA. Our fermentation strategies not only significantly enhanced CA productivity, but also severed as a promising stepping-stone for other fermentations dominated with the filamentous fungi.

Nanocomposite scaffold with enhanced stability by hydrogen bonds between collagen, polyvinyl pyrrolidone and titanium dioxide.

In this study, three-dimensional (3D) nanocomposite scaffolds, as potential substrates for skin tissue engineering, were fabricated by freeze drying the mixture of type I collagen extracted from porcine skin and polyvinyl pyrrolidone (PVP)-coated titanium dioxide (TiO2) nanoparticles. This procedure was performed without any cross-linker or toxic reagents to generate porosity in the scaffold. Both morphology and thermal stability of the nanocomposite scaffold were examined. The swelling behavior, mechanical properties and hydrolytic degradation of the composite scaffolds were carefully investigated. Our results revealed that collagen, PVP and TiO2 are bonded together by four main hydrogen bonds, which is an essential action for the formation of nanocomposite scaffold. Using Coasts-Redfern model, we were able to calculate the thermal degradation apparent activation energy and demonstrated that the thermal stability of nanocomposites is dependent on amount of PVP incorporated. Furthermore, SEM images showed that the collagen fibers are wrapped and stabilized on scaffolds by PVP molecules, which improve the ultimate tensile strength (UTS). The UTS of PVP-contained scaffold is four times higher than that of scaffold without PVP, whereas ultimate percentage of elongation (UPE) is decreased, and PVP can enhance the degradation resistance.

Reconstruction of circulation in the fingertip without vein repair in zone I replantation.

PURPOSE: In fingertip replantation, adequate venous drainage is important for success. As the level of amputation becomes more distal, anastomosis of veins becomes more technically difficult. External bleeding is a common solution to venous congestion, but the process is burdensome because of duration of bleeding for 3 or more days after surgery. We present a new technique for reconstructing circulation without vein anastomosis in zone I replantation and analyze the outcomes of this technique in terms of eliminating external bleeding and of a high survival rate of the replanted digits. METHODS: Between 1997 and 2007, we performed 120 replantations in 112 patients (83 male and 29 female; mean age, 33 years; range, 3-54 years). All were zone I amputations, based on the Tamai classification. We surgically repaired both proper digital arteries, excluded the vein, and then ligated 1 of the arteries. Using this technique, circulation was restored. Included in the outcome evaluation were 91 digits in the 87 patients (mean age, 35 years; range, 14-54) who returned for outcome assessments 12 months after surgery. RESULTS: Of 120 digits replanted, 115 digits survived, corresponding to an overall success rate of 96%. No patients received alternative means to alleviate venous congestion, such as leeches or other means of external bleeding. Nearly all of the 87 patients (91 digits) were satisfied with the results of the replantations. CONCLUSIONS: Our technique reconstructs circulation without vein anastomosis in zone I replantation. This alternative to venous congestion involves a simple surgical procedure and straightforward postoperative care. Follow-up assessments of a series of 120 replantations show that the majority of zone I replantations led to satisfactory function. We therefore propose this technique as an effective method for zone I replantation. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.