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Foodborne illness caused by Salmonella spp. is one of the most prevalent public health problems globally, which have brought immeasurable economic burden and social impact to countries around the world. Neither current nucleic acid amplification detection method nor standard culture method (2–3 days) are suitable for field detection in areas with a heavy burden of Salmonella spp. Here, we developed a highly sensitive and accurate assay for Salmonella spp. detection in less than 40 min. Specifically, the invA gene of Salmonella spp. was amplified by recombinase polymerase amplification (RPA), followed by Pyrococcus furiosus Argonaute (Pf Ago)-based target sequence cleavage, which could be observed by a fluorescence reader or the naked eye. The assay offered the lowest detectable concentration of 1.05 × 101 colony forming units/mL (CFU/mL). This assay had strong specificity and high sensitivity for the detection of Salmonella spp. in field samples, which indicated the feasibility of this assay. • The method can be widely used in on-site food sample detection or standard laboratory detection. • The operation process is simple and fast (∼40 min). • High detection sensitivity • Ultraviolet light can read signals. [ABSTRACT FROM AUTHOR]

A facile single hydrothermal method was developed to synthetize P,N codoped carbon dots (P,N/CDs), which show strong and stable fluorescence, good water solubility, low toxicity and good biocompatibility. Hence, a novel and efficient "off-on" P,N/CDs fluorescent probe was developed for the highly sensitive detection of lipoic acid (LA) for the first time. The fluorescence of the P,N/CDs was quenched by Cu2+ forming a P,N/CDs-Cu2+ complex, which acted as the "off" process, but Cu2+ could be removed by LA, due to stronger chelating between LA and Cu2+, forming a more stable complex, which recovered the fluorescence of the P,N/CDs, in order to achieve the "on" process. Under optimal conditions, the concentration of LA and the increased fluorescence intensity of the P,N/CDs-Cu2+ complex displayed a good linear relationship within the range of 0.05–28 μM, with a detection limit (S/N = 3) of 0.02 μM. The established "off-on" fluorescent probe was successfully applied to the analysis of LA in urine samples. The average recoveries were in the range of 98.3–101.5%, with a relative standard deviations of less than 3.1%. In addition, the P,N/CDs were also successfully applied to cellular dual-color imaging of live T24 cells. The results show that the P,N/CDs have great application potential in clinical diagnosis, bioassay and bioimaging. [ABSTRACT FROM AUTHOR]

We developed a near-infrared ratiometric fluorescent nanoprobe with single-excitation dual-emission. The proposed nanoprobe was applied for real-time monitoring the changes in the pH value during hydrogen peroxide-induced apoptosis by ratio imaging. The pH value of HeLa cells changed from 6.6 to 5.6 after H2O2 (100 μM) stimulation for 40 min. [ABSTRACT FROM AUTHOR]

In this work, we prepared glutathione (GSH)-capped copper nanoclusters (Cu NCs) with red emission by simply adjusting the pH of GSH/Cu 2+ mixture at room temperature. A photoluminescence light-up method for detecting Zn 2+ was then developed based on the aggregation induced emission enhancement of GSH-capped Cu NCs. Zn 2+ could trigger the aggregation of Cu NCs, inducing the enhancement of luminescence and the increase of absolute quantum yield from 1.3% to 6.2%. GSH-capped Cu NCs and the formed aggregates were characterized, and the possible mechanism was also discussed. The prepared GSH-capped Cu NCs exhibited a fast response towards Zn 2+ and a wider detection range from 4.68 to 2240 μM. The detection limit (1.17 μM) is much lower than that of the World Health Organization permitted in drinking water. Furthermore, taking advantages of the low cytotoxicity, large Stokes shift, red emission and light-up detection mode, we explored the use of the prepared GSH-capped Cu NCs in the imaging of Zn 2+ in living cells. The developed luminescence light-up nanoprobe may hold the potentials for Zn 2+ -related drinking water safety and biological applications. [ABSTRACT FROM AUTHOR]

At present, the main challenge for Staphylococcus aureus (S. aureus) in food safety is still a lack of rapid, convenient detection methods. This study developed a combination of recombinase polymerase amplification (RPA) and the CRISPR-Cas12a technology (known as the RPA-CRISPR-Cas12a assay) for the detection of S. aureus in food. This novel assay could detect samples with a fluorescence reader, lateral flow dipstick (LFD) or the naked eye under a UV transilluminator. After optimization, the RPA-CRISPR-Cas12a assay could specifically and stably detect S. aureus as low as 1–10 copies/μL within 40 min at 37 °C. This assay had high sensitivity to the detection of S. aureus in both laboratory standard samples and field samples, which indicated the feasibility of this assay. To sum up, this accurate, portable detection method for S. aureus has great potential applications in food safety, especially in the field, without requiring sophisticated equipment or high level of technical expertise. [ABSTRACT FROM AUTHOR]

We investigate the homogeneous initial boundary value problem for a coupled Camassa–Holm system with peakons on the half line. We first establish the local well-posedness for the system. We then present a precise blowup scenario and several blowup results of strong solutions to the system. We finally give the blowup rate of strong solutions to the system when blowup occurs. [ABSTRACT FROM AUTHOR]

First, we establish the local well-posedness of the initial value problem for a new three-component Camassa-Holm system with peakons. We then present a precise blowup scenario and several blowup results for strong solutions to that system. Finally, we determine the blowup rate of strong solutions to the system when a blowup occurs. Our results include all earlier results on the Camassa-Holm equation and on a two-component Camassa-Holm system with peakons. [ABSTRACT FROM AUTHOR]

• A visual method based on RPA and LFD for identification of meat adulteration (beef, sheep, pork, duck, chicken) was firstly developed. • The identification reaction was completed within 20 min. • The identification results could be determined by the naked eye. • The detection limits of the RPA-LFD assays for duck, beef, sheep, chicken, and pork were 101/µL, 102/µL, 102/µL, 101/µL and 101/µL, respectively. • The RPA-LFD assays could differentiate species in boiled, microwaved, pressure -cooked or fried samples. Determining the animal source in meat and meat products is crucial to prevent meat adulteration and fraud. Conventional methods require considerable operator skills, expensive instruments and are unable to provide fast mobile on-site detection systems to detect contamination of meat products. We developed a visual method based on recombinase polymerase amplification (RPA) and a lateral flow dipstick (LFD) to identify beef (Bos taurus), sheep (Ovis aries), pork (Sus scrofa), duck (Anas platyrhynchos) and chicken (Gallus gallus). The reaction was completed within 20 min. The results were determined by the naked eye. The detection limits of the RPA-LFD assays for duck, beef, sheep, chicken and pork were 101/µL, 102/µL, 102/µL, 101/µL and 101/µL, respectively. Furthermore, the RPA-LFD assays could differentiate species in boiled, microwaved, pressure-cooked or fried samples. These RPA-LFD assays represent a rapid, mobile detection system for determining meat product contamination. [ABSTRACT FROM AUTHOR]

Herein, a dual-signal sensing strategy based on ratiometric fluorescence and colorimetry for Cu2+ and glyphosate determination was constructed. Fluorescence silicon nanoparticles (SiNPs) were prepared by hydrothermal reaction, which has maximum fluorescence intensity under the excitation of 355 nm. o-Phenylenediamine (OPD) was oxidized through Cu2+ to generate 2,3-diaminophenazine (oxOPD). The obtained oxOPD showed a strong absorption peak at 417 nm and quenched the fluorescence of SiNPs at 446 nm due to fluorescence resonance energy transfer (FRET). Meanwhile, oxOPD produced a new fluorescence emission at 556 nm forming a ratiometric state. With increasing Cu2+, the original solution changed from colorless to yellow. When glyphosate was present, the interaction between Cu2+ and the functional groups of glyphosate could reduce the oxidation of oxOPD, resulting in the enhancement of fluorescence at 446 nm and the decrease of fluorescence at 556 nm. Furthermore, the addition of glyphosate changed yellow solution to colorless. Under the optimal conditions of OPD (1 mM), 20 mM Tris–HCl buffer (pH 7.5), and incubation time (4 h), the ratiometric fluorescence sensor had good selectivity and showed a wide linear range of 0.025–20 μM with the LOD of 0.008 μM for Cu2+ and 0.15–1.5 μg/mL with the LOD of 0.003 μg/mL for glyphosate, respectively. Besides, it is worth mentioning that this developed sensing system showed good performance in real samples, providing a simple and reliable dual-signal detection strategy. [ABSTRACT FROM AUTHOR]

This study aimed to investigate nutrition in climbing perch Anabas testudineus which is an important nutritious economic freshwater fish in Asia and compare with Carassius auratus (crucian carp). Three kinds of tissues, including muscle, livers, and eggs, were isolated, respectively. Physicochemical properties including moisture, ash, protein, amino acids, fat, vitamins, and calcium contents in those tissues were determined. The results showed climbing perch muscle and liver contained less moisture, but more protein, amino acids, and vitamins than crucian carp muscle and liver. While moisture, ash, protein, and total amino acids contents of climbing perch egg were lower than those of crucian carp egg. Climbing perch egg had more fat, vitamins, and calcium than crucian carp egg. The amino acid profile was also performed, and 16 amino acids were identified and quantified in muscle, liver, and egg. Among tissues, the highest and lowest concentration of total amino acid content was found in crucian carp eggs and livers, respectively. Glutamic acid (Glu) and histidine (His) were the most and least amino acids in climbing perch and crucian carp tissues, respectively. Sixteen amino acids in climbing perch egg were less than those in crucian carp egg while it is an opposite case in muscle and liver, which amino acids of climbing perch tissues were more than those of crucian carp muscle and liver. Vitamin A of climbing perch was more than crucian carp in all three tissues, but vitamin E content in climbing perch liver was lower than that of crucian carp liver. Calcium content of muscle had no difference between two species. The abovementioned comparison of physicochemical properties of different tissues from China climbing perch and crucian carp will provide a necessary supplementary of freshwater muscle nutrition research, also was helpful for application of climbing perch. [ABSTRACT FROM AUTHOR]

• A new application of DNA-templated silver nanoclusters was reported. • A turn-on fluorescence strategy based on Cu2+ modulated DNA-templated silver nanoclusters were constructed for glyphosate detection. • In this fluorescence sensor, we applied a stoichiometry method to investigate the mechanism of the fluorescence system. • Determination of glyphosate in real samples was achieved. The abuse application of glyphosate can result in a potential hazard for environment and human, however its ultrasensitive detection remains challenging. Herein, a Cu2+ modulated DNA-templated silver nanoclusters (DNA-AgNCs) sensor was constructed to sensitively determine glyphosate based on the turn-on fluorescence strategy. The fluorescence quenching of DNA-AgNCs occurred with the existence of Cu2+. Upon the presence of glyphosate, the functional groups on the surface of glyphosate could chelate with Cu2+, following the fluorescence recovery of DNA-AgNCs. Through the stoichiometric methods, we unveil that Cu2+-trigged fluorescence quenching mode is a combination of static and dynamic quenching with the static mode being predominant. In DNA-AgNCs/Cu2+ system, the carboxylate, amine, and phosphonate groups of glyphosate interact with Cu2+ through chelation, in which the carboxylate oxygen, the phosphonate oxygen atoms, and the monoprotonated secondary amine nitrogen atom and Cu2+ form chelate rings. This fluorescence sensor showed a desired linearity of glyphosate analysis under the optimum conditions, ranging from 15 to 100 μg/L with a low detection down to 5 μg/L. Moreover, the proposed sensor was successfully utilized to measure glyphosate in real samples, indicating a promising application in pesticide residues detection. [ABSTRACT FROM AUTHOR]

Seagrass ecosystems are among the most productive marine ecosystems, and diazotrophic communities play a crucial role in sustaining the productivity and stability of such ecosystems by introducing fixed nitrogen. However, information concerning both total and active diazotrophic groups existing in different compartments of seagrass is lacking. This study comprehensively investigated the diversity, structure, and abundance of diazotrophic communities in different parts of the seagrass Halophila ovalis at the DNA and RNA level from clone libraries and real-time quantitative PCR. Our results indicated that nearly one-third of existing nitrogen-fixing bacteria were active, and their abundance might be controlled by nitrogen to phosphorus ratio (N:P). Deltaproteobacteria and Gammaproteobacteria were dominant groups among the total and active diazotrophic communities in all samples. These two groups accounted for 82.21% and 70.96% at the DNA and RNA levels, respectively. The genus Pseudomonas and sulfate-reducing bacteria (genera: Desulfosarcina, Desulfobulbus, Desulfocapsa, and Desulfopila) constituted the significant fraction of nitrogen-fixing bacteria in the seagrass ecosystem, playing an additional role in denitrification and sulfate reduction, respectively. Moreover, the abundance of the nitrogenase gene, nifH, was highest in seawater and lowest in rhizosphere sediments from all samples. This study highlighted the role of diazotropic communities in the subtropical seagrass ecosystem. [ABSTRACT FROM AUTHOR]

Background: Although glucose‐6‐phosphate dehydrogenase (G6PD) deficiency is the most common inherited disorder in the Chinese population, there is scarce evidence regarding the epidemiology, evolutionary origin, and malaria‐induced positive selection effects of G6PD‐deficient alleles in various Chinese ethnic populations. Methods: We performed a large population‐based screening (n = 15,690) to examine the impact of selection on human nucleotide diversity and to infer the evolutionary history of the most common deficiency alleles in Chinese populations. Results: The frequencies of G6PD deficiency ranged from 0% to 11.6% in 12 Chinese ethnic populations. A frequency map based on geographic information showed that G6PD deficiency was highly correlated with historical malaria prevalence in China and was affected by altitude and latitude. The five most frequently occurring G6PD gene variants were NM_001042351.3:c.1376G>T, NM_001042351.3:c.1388G>A, NM_001042351.3:c.95A>G, NM_001042351.3:c.1311T>C, and NM_001042351.3:c.1024C>T, which were distributed with ethnic features. A pathogenic but rarely reported variant site (NM_001042351.3:c.448G>A) was identified in this study. Bioinformatic analysis revealed a strong and recent positive selection targeting the NM_001042351.3:c.1376G>T allele that originated in the past 3125 to 3750 years and another selection targeting the NM_001042351.3:c.1388G>A allele that originated in the past 5000 to 6000 years. Additionally, both alleles originated from a single ancestor. Conclusion: These results indicate that malaria has had a major impact on the Chinese genome since the introduction of rice agriculture. [ABSTRACT FROM AUTHOR]

In this study, a novel genotyping point-of-care testing (POCT) rapid detection device, the locked nucleic acid (LNA)-amplification refractory mutation system (ARMS)-recombinase polymerase amplification (RPA)-GoldMag lateral flow assay (LFA) platform, was provided by mining and synthesis based on prior technology. Research methods based on system-integrated innovation and knowledge-integrated generation have become a new trend in technology development. Here, we exploit the combination of LNA-coupled ARMS-RPA and gold nanoparticle probe technology for detection signal amplification, thus pioneering a new tool for accurate, rapid, and cost-effective genotyping. We also performed SNP typing detection and clinical validation of this new assay platform using common glucose-6-phosphate dehydrogenase (G6PD) gene single nucleotide polymorphism (SNP) loci, and the results demonstrated the high sensitivity, specificity, stability, accuracy and feasibility of the LNA-ARMS-RPA-GoldMag lateral flow assay platform. It is hoped that this new technology will make a significant contribution to the field of POCT rapid diagnosis and aim to expand the application space, reflecting its clinical application value and development prospects. • Constructed a genotyping POCT detection device: LNA-enhanced ARMS-RPA-GoldMag LFA platform. • Innovative combination of LNA, ARMS-RPA and GoldMag technology amplifies the detection signal. • SNP loci of the G6PD typing assay demonstrate the superiority and feasibility of the LARGL platform. [ABSTRACT FROM AUTHOR]

Abstract Molybdenum disulfide (MoS 2), although considered as a promising transition metal dichalcogenides catalyst, owns low plane conductivity that limits its effective application. In this work, we grew monodispersed MoS 2 nanoflakes on reduced graphene oxide (rGO), and then assembled the resulting MoS 2 -rGO with carbon nanotubes (CNTs) in a layer-by-layer manner to form the MoS 2 -rGO-CNTs composite. The CNTs spacing layer not only reduces the whole catalytic material's resistance by bridging different broken MoS 2 -rGO nanosheets, but also constructs a three-dimensional structure to prevent 2D MoS 2 -rGO nanosheets restacking and thus increases the active sites. Such three-dimensional MoS 2 -rGO-CNTs catalyst exhibited a low Tafel slope of 39 mV dec−1 and a high current density of 1200 mA cm−2 at −400 mV. Therefore, our study showed a cheap and simple method to combine three-dimensional hybrid material, facilitating the large-scale application of non-noble catalyst. Graphical abstract Image 1 Highlights • A 3D layer-by-layer MoS 2 -rGO-CNTs hybrid material was fabricated by vacuum filtration. • The possible formation mechanism of such three dimensional nanostructure was provided. • A small Tafel slope of MoS 2 -rGO-CNTs for HER was discovered as 39 mV dec−1. • The HER mechanism of MoS 2 -rGO-CNTs was investigated in detail. [ABSTRACT FROM AUTHOR]

Tooth agenesis is the most common developmental dental anomaly. Absence of one or two permanent teeth is found in the majority of affected subjects. Very few patients suffer severe tooth agenesis. Recent studies revealed that WNT10A gene mutations caused syndromic and isolated severe tooth agenesis. In this study, to determine the contribution of WNT10A variants in different severities of tooth agenesis, we investigated the association between WNT10A variants and non-syndromic tooth agenesis in a Chinese population consisting of 505 tooth agenesis patients and 451 normal controls. Twenty-three novel non-synonymous variants were identified. WNT10A variants were detected in 15.8 % (75/474) of patients with 1-3 missing teeth and 51.6 % (16/31) of patients with 4 or more missing teeth. As compared with a frequency of 3.1 % in individuals with full dentition, variant allele frequencies were significantly elevated in both groups with tooth agenesis ( p values of 1.00 × 10 and 3.89 × 10, respectively). Our findings showed that WNT10A variants were associated with non-syndromic tooth agenesis from mild to severe tooth agenesis, and the more severe tooth agenesis, the stronger association. Biallelic genotypes of WNT10A variants may have a pathogenic effect on tooth development. Presence of a single variant allele would be predisposing for causation with low penetrance. Together with WNT10A variant, there should be other genetic or environmental factors leading to biallelic variant-related variable clinical manifestations and single allele variant-related low penetrance. The frequent missing tooth positions in the WNT10A-related cases were consistent with that in the general population, suggesting WNT10A plays a critically important role in the etiology of general tooth agenesis. [ABSTRACT FROM AUTHOR]

Halloysite nanotubes (Hal) are naturally occurring tubular clay nanomaterials that have a unique tubular structure and surface modifiability. In order to increase the stability and to achieve controlled release of fertilizers, chitosan (CS) was assembled on the surface of Hal as a valve for preparing Hal@CS and to control the mesoporous surface and lumen ports. Transmission electron microscopy (TEM), X-ray diffraction, Fourier transform infrared, thermogravimetric analysis and nitrogen adsorption isotherm analysis were conducted to confirm the successful grafting of CS onto the surface of the Hal. The cumulative release ratio of urea from the Hal@CS in vitro after 96 h was 34.37% without glutathione (GSH). After introducing GSH the rate of release of urea from the Hal@CS increased. The uptake, translocation, and distribution of the Hal@CS in the epidermal layer and endodermis of root tissue were detected by fluorescence labeling and TEM. We conclude that Hal@CS are a potential controlled-release carrier and delivery system for agricultural fertilizers. Unlabelled Image • Hal@CS was synthesized using chitosan-modified Hal. • Hal@CS has GSH stimulation response and can achieve effective controlled release. • Hal@CS was nontoxic to crop growth. • Hal@CS can be taken up by root cells and transported in the plant. [ABSTRACT FROM AUTHOR]