Type III secretion systems (T3SSs) are crucial for bacterial infections because they deliver effector proteins into host cells. The Escherichia coli type III secretion system 2 (ETT2) is present in ...the majority of E. coli strains, and although it is degenerate, ETT2 regulates bacterial virulence. An ATPase is essential for T3SS secretion, but the function of the ETT2 ATPase has not been demonstrated. Here, we show that EivC is homologous to the β subunit of F0F1 ATPases and it possesses ATPase activity. To investigate the effects of ETT2 ATPase EivC on the phenotype and virulence of avian pathogenic Escherichia coli (APEC), eivC mutant and complemented strains were constructed and characterized. Inactivation of eivC led to impaired flagella production and augmented fimbriae on the bacterial surface, and, consequently, reduced bacterial motility. In addition, the eivC mutant strain exhibited attenuated virulence in ducks, diminished serum resistance, reduced survival in macrophage cells and in ducks, upregulated fimbrial gene expression, and downregulated flagellar and virulence gene expression. The expression of the inflammatory cytokines interleukin (IL)-1β and IL-8 were increased in HD-11 macrophages infected with the eivC mutant strain, compared with the wild-type strain. These virulence-related phenotypes were restored by genetic complementation. These findings demonstrate that ETT2 ATPase EivC is involved in the motility and pathogenicity of APEC.
The CRISPR/Cas system protects bacteria against bacteriophage and plasmids through a sophisticated mechanism where
operon plays a crucial role consisting of
and
. However, comprehensive studies on ...the regulation of
operon of the Type I-E CRISPR/Cas system are scarce. Herein, we investigated the regulation of
in
. The mutation in
or
reduced the CRISPR/Cas system interference ability and increased bacterial susceptibility to phage, when the
operon of the CRISPR/Cas system was activated. The silence of the glycine cleavage system (GCS) encoded by
operon reduced
expression. Adding
,
-methylene tetrahydrofolate (
,
-mTHF), which is the product of GCS-catalyzed glycine, was able to activate
expression. In addition, a cAMP receptor protein (CRP) encoded by
activated
expression via binding to the
promoter in response to cAMP concentration. Since
,
-mTHF provides one-carbon unit for purine, we assumed GCS regulates
through associating with CRP. It was evident that the mutation of
failed to further reduce the
expression with the
deletion. These results illustrated a novel regulatory pathway which GCS and CRP co-regulate
of the CRISPR/Cas system and contribute to the defence against invasive genetic elements, where CRP is indispensable for GCS regulation of
expression.
Typhimurium (
Typhimurium) is a zoonotic pathogen posing a threat to animal husbandry and public health. Due to the emergence of antibiotic-resistant strains, alternative prevention and control ...strategies are needed. Live attenuated vaccines are an ideal option that provide protection against an
Typhimurium pandemic. To develop a safe and effective vaccine, double-gene mutations are recommended to attenuate virulence. In this study, we chose
and
genes, whose deletion significantly attenuates
Typhimurium's virulence and enhances immunogenicity, to construct the double-gene mutant vaccine strain SAT52ΔaroAΔluxS. The results show that the mutant strain's growth rate, adherence and invasion of susceptible cells are comparable to a wild-type strain, but the intracellular survival, virulence and host persistence are significantly attenuated. Immunization assay showed that 10
colony-forming units (CFUs) of SAT52ΔaroAΔluxS conferred 100% protection against wild-type challenges; the bacteria persistence in liver and spleen were significantly reduced, and no obvious pathological lesions were observed. Therefore, the double-gene mutant strain SAT52ΔaroAΔluxS exhibits potential as a live attenuated vaccine candidate against
Typhimurium infection.
(
) is a gram-positive bacterium and zoonotic pathogen. Currently it poses a serious problem in the swine industry due to the emergence of antibiotic-resistant bacteria. Thus, novel antimicrobials ...against
infections are urgently needed. In the previous study, a cell wall hydrolase or lysin derived from Streptococcus prophage phi5218, termed Ply5218, was identified. This lysin showed strong bacteriolytic activity against
. In the current study, the in vitro data showed that after incubation with pig serum, the bacteriolytic efficacy of Ply5218 declined in a time-dependent manner. The in vivo assays indicated that a Ply5218 triple treatment (6, 24, and 48 h post infection) was effective against various serotypes of
in a murine infection model. This regimen also alleviated streptococcal-induced clinical symptoms in piglets and significantly reduced the bacterial burden and levels of interleukin 6, a proinflammatory cytokine. This study indicates that Ply5218 shows strong antibacterial activity in pigs and has the potential to be used as a treatment for infectious diseases caused by
.
In mobile scenarios, there is a need for general user representations to solve multiple target tasks. However, there are some challenges in the related research (e.g., difficulty in learning a ...representation that satisfies both great generalization and performance). To address these problems, we proposed a network for downstream-adaptable mobile user modeling, which employed a novel fine-tuning strategy for optimizing the performance of several downstream tasks. Additionally, we designed a time-difference module to eliminate the impact of low-frequency and non-uniform app usage behavior over time. A parallel decoder structure was developed to incorporate multi-type features by minimizing information loss. We evaluated our method on a real-world dataset of 100,000 mobile users and three downstream tasks (i.e., age prediction, gender prediction, and app recommendation). The experimental results showed that our method could outperform existing methods significantly. It achieved 96.5% ACC on gender prediction, 68.1% ACC on age prediction, and 64.2% Recall@5 on app recommendation. These results imply that our method performs well on both generalization and performance. It could be anticipated promising to the unseen tasks inference.
Sp2-carbon-conjugated covalent organic frameworks (sp2c-COFs) have emerged as promising platforms for phototo–chemical energy conversion due to their tailorable optoelectronic properties, in-plane ...π-conjugations, and robust structures. However, the development of sp2c-COFs in photocatalysis is still highly hindered by their limited linkage chemistry. Herein, we report a novel thiadiazole-bridged sp2c-COF (sp2c-COF-ST) synthesized by thiadiazole-mediated aldol-type polycondensation. The resultant sp2c-COF-ST demonstrates high chemical stability under strong acids and bases (12 M HCl or 12 M NaOH). The electro-deficient thiadiazole together with fully conjugated and planar skeleton endows sp2c-COF-ST with superior photoelectrochemical performance and charge-carrier separation and migration ability. As a result, when employed as a photocathode, sp2c-COF-ST exhibits a significant photocurrent up to ∼14.5 μA cm–2 at 0.3 V vs reversible hydrogen electrode (RHE) under visible-light irradiation (>420 nm), which is much higher than those analogous COFs with partial imine linkages (mix-COF-SNT ∼ 9.5 μA cm–2) and full imine linkages (imi-COF-SNNT ∼ 4.9 μA cm–2), emphasizing the importance of the structure–property relationships. Further temperature-dependent photoluminescence spectra and density functional theory calculations demonstrate that the sp2c-COF-ST has smaller exciton binding energy as well as effective mass in comparison to mix-COF-SNT and imi-COF-SNNT, which suggests that the sp2c-conjugated skeleton enhances the exciton dissociation and carrier migration under light irradiation. This work highlights the design and preparation of thiadiazole-bridged sp2c-COFs with promising photocatalytic performance.
It is of great significance and challenges to construct physical field-enhanced photocatalysts for energy and environmental applications. Herein, an artificial-photosynthesized CdS/PbTiO3 S-scheme ...heterostructures with the enhancement of polarization electric field have been developed to promote the bifunctionally catalytic efficiencies for Cr(VI) photoreduction degradation of heavy metal pollution and Tetracycline (TC) photooxidation degradation of antibiotic. In our work, CdS nanoparticles are selectively grown on the positive polarization planes of PbTiO3 microplates to form the same direction for both the ferroelectric polarization field of PbTiO3 and the built-in electric field of S-scheme heterojunction. In this case, the stable heterostructures of PTO(00−1)/CdS(010) are obtained, and the greatly improved photocatalytic performances of redox degradation are achieved. The charge transfer mechanism and the synergetic effect between the spontaneous ferroelectric polarization and S-scheme heterojunction have been revealed by DFT calculations and experimental verifications. This interesting finding provides new insight into the design of efficient artificial-photosynthesized photocatalytic systems and we hope our work could serve as a valuable reference for our colleagues.
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•The two-step hydrothermal method is employed to prepare the artificial-photosynthesized S-scheme heterostructures.•CdS nanoparticles selectively grow on the positive polarization planes of PbTiO3 microplates.•The photophysical process and the catalytic mechanism are revealed by the experiments and the DFT calculations.•The ferroelectric polarization electric field and the built-in electric field synergistically act on this composite.•The synergism boosts bifunctionally catalytic applications of S-scheme heterostructures.
•Contents of trans fatty acids in oils was determined by 1H NMR spectroscopy in association with multivariate calibration.•The 1H NMR spectra of edible and cis-trans isomerized oils are different in ...three chemical shift regions.•The difference of the 1H NMR spectra of cis and tans unsaturated fatty acids was analyzed.•The PLS method were successfully applied to predict the contents of unsaturated fatty acids in oils.
In this work, cis and trans fatty acid (FA) contents in edible oils was determined using 1H nuclear magnetic resonance (1H NMR) spectroscopy. The comparison of 1H NMR spectra of edible oil and cis-trans isomerized oil showed that they were different in three regions: (1) 2.880 - 2.650 ppm caused by bis-allylic protons; (2) 2.140 - 1.900 ppm due to allylic protons; and (3) 1.030 - 0.930 ppm due to methyl protons of linolenic acyl groups. The 1H NMR signals in these regions were combined with partial least squares method to predict contents of cis/trans fatty acids in edible oils. The results showed that the predicted values were consistent with the gas chromatography-measured values and had a good linear relationship with a correlation coefficient (R2) of above 0.98. This work demonstrates that 1H NMR spectroscopy was successfully used to determine the composition of both cis and trans fatty acids in edible oils.
Catalysts with different Cu/Zn ratios were prepared by the complete liquid-phase method, and their catalytic CO hydrogenation performance was investigated at slurry bed. Their physicochemical ...properties were characterized by XRD, BET, H
2
-TPR, and XPS. The results show that Cu1.0Zn1.0 catalyst had higher ethanol selectivity and Cu1.0Zn3.0 catalyst had higher CO conversion and methanol selectivity. It was found that the number of Cu
+
sites plays a crucial role in the syngas conversion. More surface Cu
+
content is favorable to ethanol synthesis, while less surface Cu
+
content is favorable to methanol synthesis. In addition, more oxygen vacancies are conducive to the generation of stronger Cu–Zn interaction, which is beneficial to ethanol selectivity. It is further indicated that there was a synergy of Cu
0
, Cu
+
, and ZnO
x
on the catalyst surface.
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