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In situ imaging of genes of pathogenic bacteria can profile cellular heterogeneity, such as the emergence of drug resistance. Fluorescence in situ hybridization (FISH) serves as a classic approach to image mRNAs inside cells, but it remains challenging to elucidate genomic DNAs and relies on multiple fluorescently labeled probes. Herein, we present a dead Cas12a (dCas12a)-labeled polymerase chain reaction (CasPCR) assay for high-contrast imaging of cellular drug-resistant genes. We employed a syncretic dCas12a-green fluorescent protein (dCas12a–GFP) to tag the amplicons, thereby enabling high-contrast imaging and avoiding multiple fluorescently labeled probes. The CasPCR assay can quantify quinolone-resistant Salmonella enterica in mixed populations and identify them isolated from poultry farms. [ABSTRACT FROM AUTHOR]

Molecular diagnostics for crop diseases can guide the precise application of pesticides, thereby reducing pesticide usage while improving crop yield, but tools are lacking. Here, we report an in-field molecular diagnostic tool that uses a cheap colorimetric paper and a smartphone, allowing multiplexed, low-cost, rapid detection of crop pathogens. Rapid nucleic acid amplification-free detection of pathogenic RNA is achieved by combining toehold-mediated strand displacement with a metal ion-mediated urease catalysis reaction. We demonstrate multiplexed detection of six wheat pathogenic fungi and an early detection of wheat stripe rust. When coupled with a microneedle for rapid nucleic acid extraction and a smartphone app for results analysis, the sample-to-result test can be completed in ~10 min in the field. Importantly, by detecting fungal RNA and mutations, the approach allows to distinguish viable and dead pathogens and to sensitively identify mutation-carrying fungicide-resistant isolates, providing fundamental information for precision crop disease management. On-site crop disease diagnostics is critical for precise application of pesticides. Here, the authors report an in-field molecular diagnostic tool for wheat pathogens using a nucleic acid amplification-free, gene mutation-resolved and smartphone-integrated genetic assay. [ABSTRACT FROM AUTHOR]

Reconstituted tobacco (RT) is a product made by reprocessing tobacco waste, experiencing a growing demand for heat‐not‐burn products. The purpose of this study is to analyze the main flavor ingredients in RT aerosol, as well as the transfer behavior of key flavor substances from substrates to aerosol and the concentrations of these compounds in the substrate after heating. First, we demonstrated that the odor of four RT aerosol samples could be distinguished using an electronic nose. Through non‐targeted analysis, 93 volatile compounds were detected by gas chromatography‐mass spectrometry, and 286 non/semi‐volatile compounds were identified by ultra‐high‐performance liquid electrophoresis chromatography‐mass spectrometry in aerosol. Furthermore, we found that the formation of RT aerosol involves primarily evaporation and distillation, however, the total content delivered from unheated RT samples to aerosol remains relatively low due to compound volatility and cigarette filtration. Thermal reactions during heating indicated the pyrolysis of chlorogenic acid to generate catechol and resorcinol, while Maillard reactions involving glucose and proline produced 2,3‐dihydro‐3,5‐dihydroxy‐6‐methyl‐4h‐pyran‐4‐one. The study highlighted that heating RT at approximately 300°C could mitigate the production of harmful substances while still providing a familiar sensory experience with combusted tobacco. [ABSTRACT FROM AUTHOR]

Foodborne pathogenic infection has brought multifaceted issues to human life, leading to an urgent demand for advanced detection technologies. CRISPR/Cas-based biosensors have the potential to address various challenges that exist in conventional assays such as insensitivity, long turnaround time and complex pretreatments. In this perspective, we review the relevant strategies of CRISPR/Cas-assisted diagnostics on foodborne pathogens, focusing on biosensing platforms for foodborne pathogens based on fluorescence, colorimetric, (electro)chemiluminescence, electrochemical, and surface-enhanced Raman scattering detection. It summarizes their detection principles by the clarification of foodborne pathogenic bacteria, fungi, and viruses. Finally, we discuss the current challenges or technical barriers of these methods against broad application, and put forward alternative solutions to improve CRISPR/Cas potential for food safety. [ABSTRACT FROM AUTHOR]

In response to the problem of moisture absorption or desorption of tobacco core materials during processing and storage, which were easily affected by environmental humidity, this paper summarized the relevant evaluation techniques for the moisture absorption characteristics of tobacco core materials. It was pointed out that the equilibrium moisture content could reflect the water holding capacity of tobacco core materials, and the testing techniques include non-destructive testing (oven method, gas chromatography, Karl Fischer method, difference method) and non-destructive testing (nuclear magnetic method, microwave method, infrared method). The former had high accuracy but took a long time. The latter had the advantage of fast and non-destructive testing, but was easily affected by sample morphology, stacking state, and other factors. Furthermore, the water status could be analyzed by water activity and low field nuclear magnetic resonance. Water activity reflected the availability of water, while low field nuclear magnetic resonance method could monitor and distinguish free water and bound water, but it was subject to interference from other hydrogen-containing components. Adsorption thermodynamics could be explored through isothermal hygroscopicity curves, adsorption models, and adsorption heat, while hygroscopicity kinetics could be explored through hygroscopicity time curves and related models. However, evaluating hygroscopicity characteristics solely from a thermodynamic or kinetic perspective might have limitations in evaluation dimensions and applicability. The future evaluation technology could combine the two to establish a more reasonable and applicable evaluation technique for the moisture absorption characteristics of tobacco core materials, providing reference for the research on the moisture absorption characteristics of tobacco products during processing and storage. [ABSTRACT FROM AUTHOR]