Multilocus sequence typing (MLST) analysis of Vibrio cholerae O1 El Tor isolates from Mozambique that harbour the classical CTX prophage.

Vibrio cholerae O1 isolates belonging to the Ogawa serotype, El Tor biotype, harbouring the classical CTX prophage were first isolated in Mozambique in 2004. Multilocus sequence typing (MLST) analysis using nine genetic loci showed that the Mozambique isolates have the same sequence type (ST) as O1 El Tor N16961, a representative of the current seventh cholera pandemic. Analysis of the CTX prophage in the Mozambique isolates indicated that there is one type of rstR in these isolates: the classical CTX prophage. It was also found that the ctxB-rstR-rstA-rstB-phs-cep fragment was PCR-amplified from these isolates, which indicates the presence of a tandem repeat of the classical CTX prophage in the genome of the Mozambique isolates. The possible origin of these isolates and the presence of the tandem repeat of the classical prophage in them implicate the presence of the classical CTX phage

Comparative genomic analysis reveals evidence of two novel Vibrio species closely related to V. cholerae

Background: In recent years genome sequencing has been used to characterize new bacterial species, a method of analysis available as a result of improved methodology and reduced cost. Included in a constantly expanding list of Vibrio species are several that have been reclassified as novel members of the Vibrionaceae. The description of two putative new Vibrio species, Vibrio sp. RC341 and Vibrio sp. RC586 for which we propose the names V. metecus and V. parilis, respectively, previously characterized as non-toxigenic environmental variants of V. cholerae is presented in this study. Results: Based on results of whole-genome average nucleotide identity (ANI), average amino acid identity (AAI), rpoB similarity, MLSA, and phylogenetic analysis, the new species are concluded to be phylogenetically closely related to V. cholerae and V. mimicus. Vibrio sp. RC341 and Vibrio sp. RC586 demonstrate features characteristic of V. cholerae and V. mimicus, respectively, on differential and selective media, but their genomes show a 12 to 15% divergence (88 to 85% ANI and 92 to 91% AAI) compared to the sequences of V. cholerae and V. mimicus genomes (ANI <95% and AAI <96% indicative of separate species). Vibrio sp. RC341 and Vibrio sp. RC586 share 2104 ORFs (59%) and 2058 ORFs (56%) with the published core genome of V. cholerae and 2956 (82%) and 3048 ORFs (84%) with V. mimicus MB-451, respectively. The novel species share 2926 ORFs with each other (81% Vibrio sp. RC341 and 81% Vibrio sp. RC586). Virulence-associated factors and genomic islands of V. cholerae and V. mimicus, including VSP-I and II, were found in these environmental Vibrio spp. Conclusions: Results of this analysis demonstrate these two environmental vibrios, previously characterized as variant V. cholerae strains, are new species which have evolved from ancestral lineages of the V. cholerae and V. mimicus clade. The presence of conserved integration loci for genomic islands as well as evidence of horizontal gene transfer between these two new species, V. cholerae, and V. mimicus suggests genomic islands and virulence factors are transferred between these species.

Centrality evolution of the charged-particle pseudorapidity density over a broad pseudorapidity range in Pb-Pb collisions at root s(NN)=2.76TeV

Peer reviewe

N-acetylglucosaminidase activities in wetlands: A global survey

A fluorogenic model substrate, methylumbelliferyl-N-acetylglucosamine was used to measure N-acetylglucosaminidase activities in wetland soils. The enzyme activity exhibited substrate saturation around 200 muM, and an approximate linearity for at least 90 min incubation time. The effects of temperature, pH, toluene, and gamma-radiation on the enzyme were also determined. The method was applied to 32 different wetland samples from both freshwater wetlands and salt-water wetlands. Overall, the activities were the lowest in bogs and much higher in freshwater marshes and flooded grasslands. The variations of the activity were not explained by a single environmental variable. However, among peatland samples (e.g., bogs and fens) only, specific enzyme activity per organic matter exhibited a significant correlation with N-acetylglucosaminidase activity, suggesting the importance of the enzyme activity in organic matter dynamics in such systems.

Artifical neural network analysis of pyrolysis spectrometric data in the identification of Streptomyces strains

Sixteen representatives of three morphologically distinct groups of streptomycetes were recovered from soil using selective isolation procedures. Duplicated batches of the test strains were examined by Curie-point pyrolysis mass spectrometry and the first data set used for conventional multivariate statistical analyses and as a training set for an artificial neural network. The second set of data was used for 'operational finger-printing' and for testing the artificial neural network. All of the test strains were correctly identified using the artificial neural network whereas only fifteen of the sixteen strains were assigned to the correct group using the conventional operational fingerprinting procedure. Artificial neural network analysis of pyrolysis mass spectrometric data provides a rapid, cost-effective and reproducible way of identifying and typing large numbers of microorganisms.

Controlling the Pyrolysis Conditions of Microporous/Mesoporous MIL-125 To Synthesize Porous, Carbon-Supported Ti Catalysts with Targeted Ti Phases for the Oxidation of Dibenzothiophene

Metal–organic frameworks (MOFs) have been used as templates to synthesize a variety of functional materials. Pyrolysis of Zn-MOFs typically yields materials that retain the high surface area of the parent MOF while imparting mesoporosity due to carbothermal reduction and Zn evaporation. When non-Zn containing MOFs are used, significant loss in surface area and porosity after pyrolysis is observed. To overcome these limitations, a hierarchical microporous/mesoporous analogue of microporous MIL-125 (Ti) was synthesized and subjected to pyrolysis at various temperatures. By varying the pyrolysis temperature, both Ti content and phase in the final materials could be altered. The resulting materials exhibited enhanced mesoporosity and activity as catalysts in the oxidation of dibenzothiophene when compared to pyrolyzed microporous MIL-125. This increased activity was attributed to the greater mesoporosity of the hierarchical materials. This work demonstrated that the properties of MOF-templated materials can be tuned by altering the morphology of the precursor MOF

Long-term identification of streptomycetes using pyrolysis mass spectrometry and artificial neural networks

Sixteen reference strains and thirteen fresh isolates of three putatively novel Streptomyces species were examined six times over twenty months using pyrolysis mass spectrometry to examine the long-term reproducibility of the procedure. The reference strains and new isolates were correctly identified using information in each of the datasets and operational fingerprinting, but direct statistical comparison of the datasets for strain identification was unsuccessful between datasets. Artificial neural networks were also used to identify the strains held in the datasets. Neural networks trained with pyrolysis mass spectra from a single dataset were found to successfully identify the reference strains and fresh isolates in that dataset but were unable to identify many of the strains in the other datasets. However, a neural network trained on representative pyrolysis mass spectra from each of the first three datasets were found to identify the reference strains and fresh isolates in those three datasets and in the three subsequent datasets. Therefore, artificial neural network analysis of pyrolysis mass spectrometric data can provide a rapid, cost-effective, accurate and long-term reproducible way of identifying and typing microorganisms.

Enhancing C–H Bond Activation of Methane via Temperature-Controlled, Catalyst–Plasma Interactions

Recent shale gas discoveries and advances in plasma chemistry provide the basis to exploit metal surface–plasma interactions to precisely control C–H bond activation on catalytic surfaces, leading to improved reaction efficiencies. Although the exact determination of plasma–catalyst interactions remains a topic of continuing research, this Letter provides evidence that plasma–catalyst interactions exist and can be used to significantly enhance the activation of C–H bonds at temperatures >630 K, probed by the catalytic dry reforming of methane with carbon dioxide using Ni/Al₂O₃. We systematically varied bulk temperature and plasma power to determine Ni–plasma interactions. In contrast to reactions at low temperatures (<630 K), CH₄ conversion, H₂ yield (selectivity), and forward CH₄ consumption rate were significantly enhanced at higher temperatures with plasma (>8 fold increase). Other competing contributors, such as gas-phase plasma reactions, charge confinement, and plasma-driven enhanced bulk gas temperatures, played minor roles when operating at temperatures >630 K

Inhibition of HIV budding by a genetically selected cyclic peptide targeting the Gag?TSG101 interaction

The egress of HIV particles from virus-infected cells is accomplished by the recruitment of proteins that normally mediate host cell endocytic functions. This process requires interaction of the HIV Gag protein with the host protein TSG101 (tumor susceptibility gene 101). Here, we report the use of a bacterial reverse two-hybrid system to identify cyclic peptides that interfere with the Gag?TSG101 interaction and the finding that a five amino acid peptide discovered by this approach can disrupt the interaction and consequently inhibit HIV egress. The inhibiting molecule, which was selected from a cyclic peptide library containing 3.2 × 106 members, differs in primary sequence from the interacting sites of either TSG101 or Gag. Addition of cyclic peptide tagged with an HIV Tat sequence, which previously has been shown to enhance protein translocation across plasma membranes, to cultured human cells inhibited the production of virus-like particles (VLPs) by these cells (IC50 of 7 ?M), and this inhibition occurred in the absence of adverse affects on normal endocytic functions mediated by TSG101. A mutant Gag protein not dependent on TSG101 for release was unaffected by the cyclic peptide. Our findings, which suggest that interference with the TSG101?Gag interaction by cyclic peptides may be of practical use in the treatment of HIV infections, identify a specific cyclic peptide that reduces VLP release by this mechanism; they also demonstrate that the efficiency of interference with protein?protein interactions by cyclic peptides can be enhanced by tagging the peptides with translocation-promoting sequences. Collectively our results support the notion that small molecule therapeutics that inhibit specific interactions between viral and host proteins may have general applicability in antiviral therapy.<br/

Carbothermal Reduction of Ti-Modified IRMOF-3: An Adaptable Synthetic Method to Support Catalytic Nanoparticles on Carbon

This work describes a novel method for the preparation of titanium oxide nanoparticles supported on amorphous carbon with nanoporosity (Ti/NC) via the post-synthetic modification of a Zn-based MOF with an amine functionality, IRMOF-3, with titanium isopropoxide followed by its carbothermal pyrolysis. This material exhibited high purity, high surface area (>1000 m²/g), and a high dispersion of metal oxide nanoparticles while maintaining a small particle size (∼4 nm). The material was shown to be a promising catalyst for oxidative desulfurization of diesel using dibenzothiophene as a model compound as it exhibited enhanced catalytic activity as compared with titanium oxide supported on activated carbon via the conventional incipient wetness impregnation method. The formation mechanism of Ti/NC was also proposed based on results obtained when the carbothermal reduction temperature was varied