19 research outputs found

    Exposure to Mutagenic Disinfection Byproducts Leads to Increase of Antibiotic Resistance in <i>Pseudomonas aeruginosa</i>

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    Bacterial antibiotic resistance (BAR) in drinking water has become a global issue because of its risks on the public health. Usually, the antibiotic concentrations in drinking water are too low to select antibiotic resistant strains effectively, suggesting that factors other than antibiotics would contribute to the emergence of BAR. In the current study, the impacts of mutagenic disinfection byproducts (DBPs) on BAR were explored, using four typical DBPs: dibromoacetic acid, dichloroacetonitrile, potassium bromate, and 3-chloro-4-(dichloromethyl)-5-hydroxy-2­(5H)-furanone (MX). After exposure to DBPs, resistances to 10 individual antibiotics and multiple antibiotics were both raised by various levels, norfloxacin and polymycin B resistances were enhanced even greater than 10-fold compared with control. MX increased the resistance most observably in the selected DBPs, which was consistent with its mutagenic activity. The resistant mutants showed hereditary stability during 5-day culturing. The increase of BAR was caused by the mutagenic activities of DBPs, since mutation frequency declined by adding ROS scavenger. Mutagenesis was further confirmed by sequencing of the related genes. Our study indicated that mutagenic activities of the selected DBPs could induce antibiotic resistance, even multidrug resistance, which may partially explain the lack of agreement between BAR and antibiotic levels in drinking water

    UV Disinfection Induces a Vbnc State in <i>Escherichia coli</i> and <i>Pseudomonas aeruginosa</i>

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    The occurrence of a viable but nonculturable (VBNC) state in bacteria may dramatically underestimate the health risks associated with drinking water. Therefore, the potential for UV treatment to induce a VBNC state in <i>Escherichia coli</i> and <i>Pseudomonas aeruginosa</i> was investigated. UV disinfection effectively reduced the culturability of <i>E. coli</i> and <i>P. aeruginosa</i>, with the destruction of nucleic acids demonstrated using <i>gad</i>A long gene fragment qPCR amplification. Following UV radiation, copy numbers for the high transcriptional levels of the 16S rRNA gene varied insignificantly in both strains, confirming results from plate counting assays indicating that VBNC states were induced in both strains. Furthermore, the virulence genes <i>gadA</i> and <i>oprL</i> remained highly expressed, suggesting that the VBNC bacteria still displayed pathogenicity. Propidium monoazide qPCR indicated that cell membranes remained intact even at a UV dose of 300 mJ/cm<sup>2</sup>. The RT-qPCR results after UV and chlorine treatments in <i>E. coli</i> were significantly different (8.41 and 5.59 log units, respectively), further confirming the induction of VBNC bacteria induced by UV radiation. Finally, resuscitation was achieved, with <i>E. coli</i> showing greater resuscitation ability than <i>P. aeruginosa</i>. These results systematically revealed the potential health risks of UV disinfection and strongly suggest a combined disinfection strategy

    Visible Light Photocatalytic Degradation of RhB by Polymer-CdS Nanocomposites: Role of the Host Functional Groups

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    Surface groups of the host polystyrene beads play an important role in the properties of the polymer-based nano-CdS composites in terms of the distribution, dispersion, crystal structure, pH-dependent stability of nano-CdS, and thereafter affect their photocatalytic activity. Surface modification of the host materials can be taken as an effective and general approach to mediate the structure and properties of the nanocomposite materials

    Image_1_Fecal microbiota transplantation from HUC-MSC-treated mice alleviates acute lung injury in mice through anti-inflammation and gut microbiota modulation.tif

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    IntroductionAcute lung injury (ALI) is a severe respiratory tract disorder facilitated by dysregulated inflammation, oxidative stress and intestinal ecosystem. Fecal microbiota transplantation (FMT) is a rapid method for gut microbiota (GM) reconstruction. Furthermore, our previous studies have confirmed that human umbilical cord mesenchymal stromal cells (HUC-MSCs) can alleviate ALI by improving GM composition. Therefore, we aimed to explore the efficacy and mechanism of FMT from HUC-MSCs-treated mice on ALI.MethodsIn brief, fresh feces from HUC-MSCs-treated mice were collected for FMT, and the mice were randomly assigned into NC, FMT, LPS, ABX-LPS, and ABX-LPS-FMT groups (n = 12/group). Subsequently, the mice were administrated with antibiotic mixtures to deplete GM, and given lipopolysaccharide and FMT to induce ALI and rebuild GM. Next, the therapeutic effect was evaluated by bronchoalveolar lavage fluid (BALF) and histopathology. Immune cells in peripheral blood and apoptosis in lung tissues were measured. Furthermore, oxidative stress- and inflammation-related parameter levels were tested in BALF, serum, lung and ileal tissues. The expressions of apoptosis-associated, TLR4/NF-κB pathway-associated, Nrf2/HO-1 pathway related and tightly linked proteins in the lung and ileal tissues were assessed. Moreover, 16S rRNA was conducted to assess GM composition and distribution.ResultsOur results revealed that FMT obviously improved the pathological damage of lung and ileum, recovered the immune system of peripheral blood, decreased the cell apoptosis of lung, and inhibited inflammation and oxidative stress in BALF, serum, lung and ileum tissues. Moreover, FMT also elevated ZO-1, claudin-1, and occludin protein expressions, activating the Nrf2/HO-1 pathway but hindering the TLR4/NF-κB pathway. Of note, the relative abundances of Bacteroides, Christensenella, Coprococcus, and Roseburia were decreased, while the relative abundances of Xenorhabdus, Sutterella, and Acinetobacter were increased in the ABX-LPS-FMT group.ConclusionFMT from HUC-MSCs-treated mice may alleviate ALI by inhibiting inflammation and reconstructing GM, additionally, we also found that the TLR4/NF-κB and Nrf2/HO-1 pathways may involve in the improvement of FMT on ALI, which offers novel insights for the functions and mechanisms of FMT from HUC-MSCs-treated mice on ALI.</p

    Additional file 1 of Insights into the combined toxic impacts of phoxim and deltamethrin on the embryo-larval stage of zebrafish (Danio rerio)

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    Additional file 1: Table S1 Detailed information about the biochemical parameters tested. Table S2 Gene primer sequences in real time quantitative PCR reaction

    Incorporating Isolated Molybdenum (Mo) Atoms into Bilayer Epitaxial Graphene on 4H-SiC(0001)

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    The atomic structures and electronic properties of isolated Mo atoms in bilayer epitaxial graphene (BLEG) on 4H-SiC(0001) are investigated by low temperature scanning tunneling microscopy (LT-STM). LT-STM results reveal that isolated Mo dopants prefer to substitute C atoms at α-sites and preferentially locate between the graphene bilayers. First-principles calculations confirm that the embedding of single Mo dopants within BLEG is energetically favorable as compared to monolayer graphene. The calculated band structures show that Mo-incorporated BLEG is n-doped, and each Mo atom introduces a local magnetic moment of 1.81 μ<sub>B</sub> into BLEG. Our findings demonstrate a simple and stable method to incorporate single transition metal dopants into the graphene lattice to tune its electronic and magnetic properties for possible use in graphene spin devices

    Dicer-Dependent Biogenesis of Small RNAs Derived from 7SL RNA

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    <div><p>It has been reported that decreased Dicer expression leads to Alu RNAs accumulation in human retinal pigmented epithelium cells, and Dicer may process the endogenous SINE/B1 RNAs (the rodent equivalent of the primate Alu RNAs) into small interfering RNAs (siRNAs). In this study, we aimed to address whether Dicer can process Alu RNAs and their common ancestor, 7SL RNA. Using Solexa sequencing technology, we showed that Alu-derived small RNAs accounted for 0.6% of the total cellular small RNAs in HepG2.2.15 cells, and the abundance decreased when Dicer was knocked down. However, Alu-derived small RNAs showed different characteristics from miRNAs and siRNAs, the classic Dicer-processed products. Interestingly, we found that small RNAs derived from 7SL RNA accounted for 3.1% of the total cellular small RNAs in the control cells, and the abundance dropped about 3.4 folds in Dicer knockdown cells. Dicer-dependent biogenesis of 7SL RNA-derived small RNAs was validated by northern blotting. <em>In vitro</em> cleavage assay using the recombinant human Dicer protein also showed that synthetic 7SL RNA was processed by Dicer into fragments of different lengths. Further functional analysis suggested that 7SL RNA-derived small RNAs do not function like miRNAs, neither do they regulate the expression of 7SL RNA. In conclusion, the current study demonstrated that Dicer can process 7SL RNA, however, the biological significance remains to be elucidated.</p> </div

    Primary information for <i>OPG</i> rs3102735 T>C, rs2073618 G>C, <i>RANK</i> rs1805034 T>C, <i>RANKL</i> rs9533156 T>C and rs2277438 A>G polymorphisms.

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    a<p>http://<a href="http://www.regulomedb.org/" target="_blank">www.regulomedb.org/</a>;</p>b<p>TFBS: Transcription Factor Binding Site (<a href="http://snpinfo.niehs.nih.gov/snpinfo/snpfunc.htm" target="_blank">http://snpinfo.niehs.nih.gov/snpinfo/snpfunc.htm</a>);</p>c<p>MAF: minor allele frequency, <i>OPG</i> rs2073618 G>C MAF is in CHB+JPT population;</p>d<p>HWE: Hardy–Weinberg equilibrium;</p>e<p>LDR: Ligation Detection Reaction.</p

    Characterization of 7SL RNA-derived small RNAs.

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    <p>(A) Diagram of 7SL RNA-derived small RNAs in the control cells, the abundance and the length of 7SL RNA-derived small RNAs are drawn as a function of their positions along 7SL RNA. The horizontal line represents the position of small RNAs along the 7SL RNA sequence, the vertical length represents the abundance of small RNAs. (B) Secondary structure of human 7SL RNA. Sequences and positions of 7SL sRNA5cd and 7SL sRNA8b are marked with red color. (C) Length distribution and (D) First nucleotide bias of 7SL RNA-derived small RNAs in Dicer knockdown (K/D) and the control (Con) cells.</p
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