We have developed an ingenious method, termed Cas9 nickase‐based amplification reaction (Cas9nAR), to amplify a target fragment from genomic DNA at a constant temperature of 37 °C. Cas9nAR employs a ...sgRNA:Cas9n complex with a single‐strand nicking property, a strand‐displacing DNA polymerase, and two primers bearing the cleavage sequence of Cas9n, to promote cycles of DNA replication through priming, extension, nicking, and displacement reaction steps. Cas9nAR exhibits a zeptomolar limit of detection (2 copies in 20 μL of reaction system) within 60 min and a single‐base discrimination capability. More importantly, the underlying principle of Cas9nAR offers simplicity in primer design and universality in application. Considering the superior sensitivity and specificity, as well as the simple‐to‐implement, rapid, and isothermal features, Cas9nAR holds great potential to become a routine assay for the quantitative detection of nucleic acids in basic and applied studies.
In good nick: A method, termed Cas9 nickase‐based amplification reaction (Cas9nAR), for the isothermal amplification of a target fragment from genomic DNA was developed. The method has a zeptomolar limit of detection and a single‐nucleotide discrimination capability.
Water electrolysis has been considered as a sustainable way for producing renewable energy of hydrogen. However, this process requires a low-cost and high-efficient hydrogen evolution reaction (HER) ...catalyst to improve the overall reaction efficiency. Molybdenum (Mo)-based electrocatalysts are regarded as the promising candidates to replace the benchmark but expensive Pt-based HER catalysts, due to their high activity and stability in a wide pH range. In this review, we present a comprehensive and critical summary on the recent progress in the Mo-based electrodes for HER, including molybdenum alloys, molybdenum sulfides, molybdenum selenides, molybdenum carbides, molybdenum phosphides, molybdenum borides, molybdenum nitrides, and molybdenum oxides. Particular attention is mainly focused on the synthetic methods of Mo-based materials, the strategies for increasing the catalytic activity, and the relationship between structure/composition and electrocatalytic performance. Finally, the future development and perspectives of Mo-based electrocatalysts toward high HER performance are proposed.
Graphic abstract
Observing the structure and regeneration of the myelin sheath in peripheral nerves following injury and during repair would help in understanding the pathogenesis and treatment of neurological ...diseases caused by an abnormal myelin sheath. In the present study, transmission electron microscopy, immunofluorescence staining, and transcriptome analyses were used to investigate the structure and regeneration of the myelin sheath after end-to-end anastomosis, autologous nerve transplantation, and nerve tube transplantation in a rat model of sciatic nerve injury, with normal optic nerve, oculomotor nerve, sciatic nerve, and Schwann cells used as controls. The results suggested that the double-bilayer was the structural unit that constituted the myelin sheath. The major feature during regeneration was the compaction of themyelin sheath, wherein the distance between the 2 layers of cell membrane in the double-bilayer became shorter and the adjacent double-bilayers tightly closed together and formed the major dense line. The expression level of myelin basic protein was positively correlated with the formation of the major dense line, and the compacted myelin sheath could not be formed without the anchoring of the lipophilin particles to the myelin sheath.
Summary
High‐osmolarity glycerol (HOG) pathway required for yeast osmoregulation relies upon the mitogen‐activated protein kinase (MAPK) Hog1 cascade that comprise the MAPKKKs Ssk2/Ssk22 and Ste11 ...converging on the MAPKK Pbs2. Here we show a Hog1 cascade with the unique MAPKKK Ssk2 acting in Beauveria bassiana. Hypersensitivity to high osmolarity and high resistance to fludioxonil fungicide appeared in Δssk2, Δpbs2 and Δhog1 mutants whereas the two hallmark phenotypes were reversed in Δste11. Increased sensitivity to heat shock and decreased sensitivity to cell wall perturbation also occurred in the three mutants but not in Δste11 although antioxidant phenotypes were different in all deletion mutants. Intriguingly, signals of Hog1 phosphorylation induced by osmotic, oxidative and thermal cues were present in Δste11 but absent in Δssk2 and Δpbs2. Moreover, vegetative growth on minimal media with different carbon/nitrogen sources was much more suppressed in Δste11 and Δssk2 than in Δpbs2 and Δhog1 although all mutants suffered similar, but severe, conidiation defects on a standard medium. Normal host infection was abolished in Δste11 while virulence was differentially attenuated in other mutants. Our findings exclude Ste11 from the Hog1 cascade that regulates multiple stress responses and environmental adaptation of B. bassiana and perhaps other filamentous fungi.
MicroRNAs (miRNAs) play a vital role in various biological processes and act as important biomarkers for clinical cancer diagnosis, prognosis, and therapy. Here, we took advantage of Cas12a
trans
...-cleavage activity to develop an enzyme-assisted cascade amplification method for isothermal miRNA detection. A target miRNA-initiated ligation reaction would allow for the production of transcription templates that triggered the transcriptional amplification of RNA strands. These RNA strands were cleaved by the 8-17E DNAzyme to generate crRNAs and recycled RNAs which have the same sequence as the target miRNA. The amplified abundant crRNAs bound to Cas12a and dsDNA activators to form the complex, which
trans
-cleaved the ssDNA reporters to generate a fluorescence signal for miRNA quantitative analysis. The proposed method exhibits a femtomolar limit of detection and a good specificity in distinguishing the homologous sequences of miRNAs. Its practical application ability was further tested in different cell lines.
MicroRNAs (miRNAs) play a vital role in various biological processes and act as important biomarkers for clinical cancer diagnosis, prognosis, and therapy.
The aims of this study were to systematically evaluate and comparatively analyse the mental health status of left‐behind children (LBC) in China and to provide a scientific basis for mental ...intervention and healthy education for LBC. Six electronic databases were searched for studies (published from 1 January 2010 to 5 March 2018) of the mental health of LBC using the Mental Health Test scale. We only selected original articles that either reported the incidence of serious mental health status or the means and standard deviations of each factor score of the scale. The pooled rates and weighted mean difference were calculated. The results indicated that the incidence of serious mental health status of LBC is nearly 2.7 times higher than that of non‐LBC. The scores for most of the factors analysed by the Mental Health Test of LBC were higher than those of non‐LBC. In addition, the mental health status of left‐behind girls is worse than that of left‐behind boys. Except for impulsive tendency, there was no significant difference in the mental health status of LBC in primary and junior high schools. In terms of the different types of guardianship, the mental health status of LBC under a grandparent's guardianship and parental peer' guardianship is more serious than that of LBC under a single‐parent guardianship. The mental health status of LBC is poor, particularly for left‐behind girls. The primary mental problems faced by LBC are learning anxiety, social anxiety and physical symptoms. It is necessary to develop more targeted measures to prevent and manage LBC.
Cross-coupling of organoboron compounds with electrophiles (Suzuki–Miyaura reaction) has greatly advanced C–C bond formation and has been well received in medicinal chemistry. During the past 50 ...years, transition metals have played a central role throughout the catalytic cycle of this important transformation. In this process, chemoselectivity among multiple carbon–halogen bonds is a common challenge. In particular, selective oxidative addition of transition metals to alkyl halides rather than aryl halides is difficult due to unfavorable transition states and bond strengths. We describe a new approach that uses a single organic sulfide catalyst to activate both C(sp3) halides and arylboronic acids via a zwitterionic boron “ate” intermediate. This “ate” species undergoes a 1,2-metalate shift to afford Suzuki coupling products using benzyl chlorides and arylboronic acids. Various diaryl methane analogues can be prepared, including those with complex and biologically active motifs. The reactions proceed under transition-metal-free conditions, and C(sp2) halides, including aryl bromides and iodides, are unaffected. The orthogonal chemoselectivity is demonstrated in the streamlined synthesis of highly functionalized diaryl methane scaffolds using multi-halogenated substrates. Preliminary mechanistic experiments suggest both the sulfonium salt and the sulfur ylide are involved in the reaction, with the formation of sulfonium salt being the slowest step in the overall catalytic cycle.
Unprotected indoles are prepared with the title method, which has a wide scope for alkynes. Excellent regioselectivity was accomplished for aryl–alkyl and alkyl–alkyl disubstituted acetylenes. This ...reaction features an unusual 1,2 rhodium migration and ring‐contraction‐triggered NN bond cleavage. It allows rapid conversion of the reaction products into several functional molecules.
A quaternary carbon center containing an oxindole motif is constructed via NHC-catalyzed transition-metal and aldehyde-free intermolecular Heck-type alkyl radical addition initiated annulation. This ...redox-neutral protocol also features a simple procedure, broad substrate scope, good functional group tolerance and could be smoothly amplified to a gram scale. The mechanism study shows that the reaction possibly undergoes two folds of SET processes with an NHC radical cation intermediate involved.
The softness of polypropylene (PP) fabrics, which is related to fiber properties and fabric structure, is a pivotal perception for their application in skin contacts. However, tailoring the softness ...of PP fabrics remains challenging. The effects of mixing different percentages of polyethylene (PE) and PP during the melt‐blowing process on the polymer properties and morphology characteristics, including the softness, preparation, and characterization of the micro‐nanofibrous fabrics were determined. Rheological tests and differential scanning calorimetry results showed that the addition of PE helped destroy the crystalline integrity of PP. Moreover, scanning electron microscopy images depicted a fluffy structure consisting of micro‐nanofibers with average diameters ranging from 1.3 to 3.2 μm. Furthermore, the softness scores ranged from 70.39 to 83.11 by changing the die temperature and PE mass ratio by applying a response surface model. Consequently, this micro‐nanofibrous fabric may become a good material for skin contacts, such as baby diapers, feminine sanitary, and other personal hygiene uses.
A commercial PE polymer was selected to be blended with PP during the melt‐blowing process to prepare micro‐nanofibrous fabrics with tailored softness., Introducing PE and using higher die temperatures in the blended melt‐blowing led to fibers with average diameters in the range of 1.3 to 3.2 μm. Moreover, softness testing revealed that these fabrics possessed softness scores ranging from 70.39 to 83.11. This micro‐nanofibrous fabric may become a good material for skin contacts, such as baby diapers, feminine sanitary, and other personal hygiene uses.
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