Study on Mechanisms of Resistance to SDHI Fungicide Pydiflumetofen in Fusarium fujikuroi

Rice bakaenii disease (RBD) is a widespread and devastating disease mainly caused by Fusarium fujikuroi. Pydiflumetofen (Pyd) is a novel succinate dehydrogenase inhibitor (SDHI) with strong inhibitory activity against F. fujikuroi, but the mechanism of resistance to Pyd has not been well studied for this pathogen. Through fungicide adaption, a total of 12 Pyd-resistant mutants were obtained and the resistance level could be divided into three categories of high resistance (HR), moderate resistance (MR), and low resistance (LR) with resistance factors (RF) of 184.04-672.90, 12.63-42.49, and <10, respectively. Seven genotypes of point mutations in FfSdh genes (FfSdhBH248L, FfSdhBH248D, FfSdhBH248Y, FfSdhC2A83V, FfSdhC2H144Y, FfSdhDS106F, and FfSdhDE166K) were found in these mutants, among which genotype FfSdhBH248L and FfSdhC2A83V mutants showed HR, genotype FfSdhBH248D, FfSdhBH248Y, FfSdhC2H144Y, and FfSdhDE166K mutants showed MR, and genotype FfSdhDS106F mutants showed LR. Moreover, all the substitutions of amino acid point mutations including FfSdhBH248L/D/Y, FfSdhC2A83V,H144Y, and FfSdhDS106F,E166K conferring resistance to Pyd in F. fujikuroi were verified by protoplast transformation. Additionally, a positive cross-resistance was detected between Pyd and another SDHI fungicide penflufen, while no cross-resistance was detected between Pyd and phenamacril, prochloraz, azoxystrobin, carbendazim, or fludioxonil. Although pathogenicity of the mutants was increased compared with that of the wild-type parental strains, the mycelial growth rate and spore production levels of the resistant mutants were significantly decreased (P < 0.05), indicating significant fitness cost of resistance to Pyd in F. fujikuroi. Taken together, the risk of resistance to Pyd in F. fujikuroi might be moderate, and appropriate precautions against resistance development in natural populations should be taken into account when Pyd is used for the control of RBD.

TDDFT study on the simultaneous sensing mechanism for peroxynitrite and glutathione by a bifunctional fluorescent probe

Using time-dependent density functional theory (TDDFT) method, the response mechanism of a reported bifunctional fluorescent probe for simultaneous recognition of peroxynitrite and glutathione (Chem. Commun. 2018, 54, 11336) was theoretically studied. Calculated vertical excitation energies based on the ground-state and excited-state geometries were consistent with the corresponding experimental ultraviolet-visible and fluorescence spectra. In the ground state, electron delocalization in the probe was limited because its geometry was restrained by steric hindrance. Frontier molecular orbital analysis has shown that the probe should undergo photoinduced electron transfer (PET) from the benzothiazole moiety to the maleimide moiety after excitation. The nonplanar structure together with PET led to fluorescence quenching of the probe. The probe could be dealkylated by peroxynitrite anion. The resulting intramolecular hydrogen bond increasesd the planarity of the molecule, while also gave rise to an excited-state proton-transfer process. Moreover, the addition reaction between the probe and glutathione inhibited the PET process. These two analytes together contributed to the fluorescence enhancement of the final product. This theoretical sensing mechanism for peroxynitrite and glutathione may potentially be important for the design and enhancement of novel probes.

A novel ESIPT-based fluorescent probe with dual recognition sites for the detection of hydrazine in the environmental water samples and in-vivo bioimaging

Hydrazine (N₂H₄), an important chemical intermediate, has been widely used in industrial production and agricultural life, but it has also caused environmental pollution. A novel ESIPT-based fluorescent probe with dual recognition sites, 2-(benzothiazole-2-yl)-1,4-imphenyl bis 4-bromobutyric acid (BRBA), was developed to selectively detect N₂H₄ under complex conditions. BRBA exhibits accurate detection for N₂H₄ with a good linear relationship ranging from 0 to 150 μM, and the LOD can reach 0.1 μM. Importantly, taking advantage of low cytotoxicity and a large Stokes shift, BRBA can be utilized to monitor environmental water samples and successfully applied to imaging HeLa cells and zebrafish.

An ICT-Based Coumarin Fluorescent Probe for the Detection of Hydrazine and Its Application in Environmental Water Samples and Organisms

As an inorganic small molecule pollutant, the toxicity and potential carcinogenicity of hydrazine (N₂H₄) are of increasing concern. In this work, A water-soluble fluorescent probe (OCYB) based on the intramolecular charge transfer (ICT) mechanism for the detection of hydrazine was designed and synthesized. Taking the advantage of 4-bromobutyryl as the recognition group, the high selectivity of OCYB to N₂H₄ was confirmed by steady-state fluorescence spectroscopy. The limit of detection (LOD) was calculated to be 78 nM in the DMSO-HEPES (pH 7.4) system. The detection mechanism was verified by NMR, HRMS and density functional theory (DFT) calculations. In addition, OCYB exhibits strong anti-interference ability and an “Off-On” fluorescence enhancement effect. Importantly, OCYB can be used to effectively monitor the fluorescence distribution of N₂H₄ in environmental water samples and organisms.

Clinical Diagnosis and Treatment Value of CT Three-Dimensional Imaging of Gynecological Pelvic Blood Vessels

For diseases of the abdominal and pelvic system, especially those of the blood duct system, the main examination methods of the transmission system are color Doppler ultrasound, enhanced CT angiography and digital subtraction angiography (DSA). Among them, DSA is the gold standard of angiography, but it is an invasive examination, which is complicated, time-consuming and laborious, and the skill of intubation is very high. Enhanced 3D-CT blood tube imaging has been gradually used in clinic because of its advantages such as fast imaging speed and wide imaging range. It has good vascular imaging conditions and satisfactory vascular imaging results in all parts of the human body, but this examination is radioactive and is not beneficial to young women of childbearing age, children and frail patients. The purpose of this paper is to further illustrate the value of magnetic resonance angiography (CTA) in displaying pelvic vessels by comparing the three-dimensional model of magnetic resonance angiography (CTA) and magnetic resonance angiography (MRA) in healthy young women. The results showed that for the venous system, CTA usually showed only the internal and external iliac vein, but not for the uterine vein and other branches of the internal and external iliac vein, and almost no imaging for the anterior sacral vein. CE-MRA can not only display 1-4 grade arteries to the same extent, but also show more branches of superior and inferior gluteal arteries, and show more abundant veins, especially presacral veins. For cases such as gynecological pelvic floor surgery, it is necessary to know the vascular network of presacral region before operation. In a word, for clinical diagnosis and treatment value, the 3D-CT imaging is the first choice.

A novel near-infrared fluorimetric method for point-of-care monitoring of Fe2+ and its application in bioimaging

Iron is one of the essential trace elements in the human body, which is involved in many important physiological processes of life. The abnormal amount of iron in the body will bring many diseases. Therefore, a novel near-infrared fluorimetric method was developed. The method is based on a fluorescent probe (E)-4-(2-(3-(dicyanomethylene)-5,5-dimethylcyclohex-1-en-1-yl)vinyl)-N, N-diethylaniline oxide (DDED) which uses N-oxide as a recognition group to real-time monitoring and imaging of Fe²⁺ in vivo and in vitro. The method exhibits excellent selectivity and high sensitivity (LOD = 27 nM) for Fe²⁺, fast reaction rate (< 4 min), extremely large Stokes shift (＞ 275 nm), low cytotoxicity. The strip test strongly illustrates the potential application of DDED in real environment. In particular, DDED has been successfully applied to real-time monitoring and imaging of Fe²⁺ in HepG² cells and zebrafish. That is, the method has great potential for the detection of Fe²⁺ in living systems.

Hydrazine exposure: A near-infrared ICT-based fluorescent probe and its application in bioimaging and sewage analysis

Hydrazine (N₂H₄) is an environment pollutant with high acute toxicity and potential carcinogenicity, and detection of N₂H₄ has attracted increasing attention. In the present study, a low toxicity near-infrared fluorescent probe (DCDB) based on the intramolecular charge transfer (ICT) principle was developed. The probe DCDB exhibits excellent selectivity and high sensitivity (LOD = 1.27 ppb) for N₂H₄, fast reaction rate (5 min), extremely large Stokes shift (160 nm). The color transformation of the DCDB-N₂H₄ system from purple to pink can be observed with the naked eye. The success of N₂H₄ test strips to detect trace N₂H₄ in actual sewage strongly illustrates the practical application potential of DCDB. Importantly, DCDB can be utilized to monitor the distribution of exogenous N₂H₄ in vivo and in vitro.

A Pyrene-Based Fluorescent Probe for Specific Detection of Cysteine and its Application in Living Cell

Cysteine (Cys) is an essential amino acid in organism, which is transformed from methionine in vivo and participates in protein synthesis and cell redox process. Therefore, the detection of Cys is of great significance. In this work, a novel fluorescent probe, (E)-3-(2-chloroquinolin-3-yl)-1-(pyren-3-yl) prop-2-en-1-one (PAQ) was designed and synthesized to specifically detect Cys. The response mechanism of the reaction between PAQ and Cys was due to the addition reaction of Cys to α,β-unsaturated ketone of PAQ. Interestingly, the addition of Cys induced significant fluorescence intensity enhancement at 462 nm. PAQ exhibited favorable sensing properties towards Cys such as the low limit of detection (0.27 μM) and fast response speed (2 min). In addition, PAQ displayed high selectivity and anti-interference ability toward Cys among various analytes. Notably, PAQ has been successfully used to image exogenous and endogenous Cys in HeLa cells.

Green Synthesis of Thiazole Derivatives using Multi-component Reaction of Aldehydes, Isothiocyanate and Alkyl Bromides: Investigation of Antioxidant and Antimicrobial Activity

Aims & Objective: In this work, the multicomponent reaction of aldehydes, benzoylisothiocyanate and alkyl bromides in the presence of ammonium acetate, sodium cyanide and a catalytic amount of KF/Clinoptilolite nanoparticles (KF/CP NPs) in the water at 100oC was investigated.

MATERIALS AND METHODS

In these reactions, thiazole derivatives were produced in good to excellent yields and short time. Also, the antioxidant activity was studied for some newly synthesized compounds using the DPPH radical trapping and reducing of ferric ion experiments and comparing results with the synthetic antioxidants (TBHQ and BHT).

RESULTS

As a result, the compounds 4b showed excellent DPPH radical trapping and reducing the strength of ferric ion. These compounds have biological potential because of the thiazole core. For this reason, the antimicrobial activity of some synthesized compounds was studied by employing the disk diffusion test on Gram-positive bacteria and Gram-negative bacteria.

CONCLUSION

The results of the disk diffusion test showed that these compounds prevented bacterial growth.