3,964 research outputs found
Transposon-directed insertion-site sequencing (TraDIS) analysis of Enterococcus faecium using nanopore sequencing and a WebAssembly analysis platform
No full textVancomycin-resistant Enterococcus faecium (VREfm) are healthcare-associated opportunistic pathogens of global significance. Genetic tools are needed to understand the molecular basis for VREfm clinically relevant phenotypes, such as persistence within the human gut or antimicrobial resistance. Here, we present a transposon-directed insertion-site sequencing (TraDIS) platform optimized for E. faecium. We engineered a transposon delivery plasmid, pIMTA(tetM), that can generate high-density transposon mutant libraries, combined with Oxford Nanopore Technology amplicon sequencing to map the transposon insertion sites. We have also customized a bioinformatic analysis suite that includes a WebAssembly powered visualization tool called Diana, for TraDIS data exploration and analysis (https://diana.cpg.org.au/). To demonstrate the performance of our platform, we assessed the impact of vancomycin exposure on a library of 48,458 unique transposon mutants. As expected, we could confirm the importance of the vanB operon for VREfm vancomycin resistance. However, we also identified an essential role for both vanWB and vanYB, each previously designated as protein of unknown function and accessory for resistance, respectively. Our end-to-end platform for running TraDIS experiments in VREfm will permit accessible, genome-scale, forward genetic screens to probe molecular mechanisms of persistence and pathogenesis.IMPORTANCEThere are limited genetic tools specifically developed and optimized for function in Enterococcus faecium. Here, we addressed this gap through the development of a transposon-directed insertion-site sequencing platform with a plasmid we engineered to specifically function in E. faecium. The application of nanopore sequencing, with a highly accessible sequence data processing and bioinformatic analysis pipeline, streamlines and simplifies the methodology. These developments will allow the functional genomic analysis of important traits involved in the pathobiology of this understudied bacterium. The approach and tools we have described here are likely applicable to other Gram-positive bacteria
Antigen 43 associated with Escherichia coli membrane vesicles contributes to bacterial cell association and biofilm formation
No full textBacterial membrane vesicles (MVs) are produced by all bacteria and contribute to numerous bacterial functions due to their ability to package and transfer bacterial cargo. In doing so, MVs have been shown to facilitate horizontal gene transfer, mediate antimicrobial activity, and promote biofilm formation. Uropathogenic Escherichia coli is a pathogenic Gram-negative organism that persists in the urinary tract of its host due to its ability to form persistent, antibiotic-resistant biofilms. The formation of these biofilms is dependent upon proteins such as Antigen 43 (Ag43), which belongs to the widespread Autotransporter group of bacterial surface proteins. In E. coli, the autotransporter Ag43 has been shown to contribute to bacterial cell aggregation and biofilm formation via self-association of Ag43 between neighboring Ag43-expressing bacteria. As MVs package bacterial proteins, we investigated whether MVs produced by E. coli contained Ag43, and the ability of Ag43-expressing MVs to facilitate cell aggregation and biofilm formation. We showed that Ag43 expressing E. coli produced MVs that contained Ag43 on their surface and had an enhanced ability to bind to E. coli bacteria. Furthermore, we demonstrated that the addition of Ag43-containing MVs to Ag43-expressing E. coli significantly enhanced biofilm formation. These findings reveal the contribution of MVs harboring autotransporters in promoting bacterial aggregation and enhancing biofilm formation, highlighting the impact of MVs and their specific composition to bacterial adaptation and pathogenesis.IMPORTANCEAutotransporter proteins are the largest family of outer membrane and secreted proteins in Gram-negative bacteria which contribute to pathogenesis by promoting aggregation, biofilm formation, persistence, and cytotoxicity. Although the roles of bacterial autotransporters are well known, the ability of bacterial membrane vesicles (MVs) naturally released from the surface of bacteria to contain autotransporters and their role in promoting virulence remains less investigated. Our findings reveal that MVs produced by E. coli contain the autotransporter protein Ag43. Furthermore, we show that Ag43-containing MVs function to enhance bacterial cell interactions and biofilm formation. By demonstrating the ability of MVs to carry functional autotransporter adhesins, this work highlights the importance of MVs in disseminating autotransporters beyond the bacterial cell membrane to ultimately promote cellular interactions and enhance biofilm development. Overall, these findings have significant implications in furthering our understanding of the numerous ways in which MVs can facilitate bacterial persistence and pathogenesis
Epigenetic Regulation of Virulence and Immunoevasion by Phase-Variable Restriction-Modification Systems in Bacterial Pathogens
No full textHuman-adapted bacterial pathogens use a mechanism called phase variation to randomly switch the expression of individual genes to generate a phenotypically diverse population to adapt to challenges within and between human hosts. There are increasing reports of restriction-modification systems that exhibit phase-variable expression. The outcome of phase variation of these systems is global changes in DNA methylation. Analysis of phase-variable Type I and Type III restriction-modification systems in multiple human-adapted bacterial pathogens has demonstrated that global changes in methylation regulate the expression of multiple genes. These systems are called phasevarions (phase-variable regulons). Phasevarion switching alters virulence phenotypes and facilitates evasion of host immune responses. This review describes the characteristics of phasevarions and implications for pathogenesis and immune evasion. We present and discuss examples of phasevarion systems in the major human pathogens Haemophilus influenzae, Neisseria meningitidis, Neisseria gonorrhoeae, Helicobacter pylori, Moraxella catarrhalis, and Streptococcus pneumoniae.No Full Tex
Streptococcus suis pathogenesis—A diverse array of virulence factors for a zoonotic lifestyle
No full textStreptococcus suis is a major cause of respiratory tract and invasive infections in pigs and is responsible for a substantial disease burden in the pig industry. S. suis is also a significant cause of bacterial meningitis in humans, particularly in South East Asia. S. suis expresses a wide array of virulence factors, and although many are described as being required for disease, no single factor has been demonstrated to be absolutely required. The lack of uniform distribution of known virulence factors among individual strains and lack of evidence that any particular virulence factor is essential for disease makes the development of vaccines and treatments challenging. Here we review the current understanding of S. suis virulence factors and their role in the pathogenesis of this important zoonotic pathogen.No Full Tex
The SSC of the Generalised Jahangir’s Graph Jm,k and its Algebraic Characterizations
No full textIn this article, we present important combinatorial and algebraicproperties of spanning simplicial complex (SSC) of the generalised Jahangir’sgraph Jm,k. We describe the relation to find f−vectors associatedto Δs(Jm,k) and determine the Hilbert series for the SR-ring KΔs(Jm,k).In the end, we present the associated primes of the facet ideal IF(Δs(Jm,k))and the Cohen-Macaulay characterization of the SR-ring of Δs(Jm,k).AMS (MOS) Subject Classification Codes: Primary 13-P10, Secondary 13-F20, 13-C14, 13-H10.Corresponding Author: Agha KashifKey Words: Simplicial Complexes, f-vectors, Spanning Trees, Face Ring, Hilbert Series, CohenMacaulay
To <i>JM</i> on Its 75th Anniversary
No full text This article discusses how Journal of Marketing ( JM) has influenced marketing science and practice by publishing articles on substantive topics relevant to customers, managers, organizations, markets, and society. The journal's 75th anniversary coincides with the 50th anniversary of the Marketing Science Institute (MSI). Frequently, JM and MSI have collaborated to address important substantive marketing issues identified in MSI's Research Priorities. The author highlights seminal articles on brand equity; business-to-business marketing (including sales force management); connecting marketing information, metrics, and strategy; consumer behavior; innovation, new product development. and product management; marketing orientation and capabilities; and market research, methodology and services. She also draws attention to articles that have won the Sheth Foundation/ JM Award and the H. Paul Root Award. The article describes how JM‘s knowledge dissemination is amplified by powerful social network effects. Ideas in JM articles diffuse through the business community, influencing the mind-set of managers worldwide. </jats:p
JM-20, a Benzodiazepine-Dihydropyridine Hybrid Molecule, Inhibits the Formation of Alpha-Synuclein-Aggregated Species
No full text\ua9 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.Studies showed that JM-20, a benzodiazepine-dihydropyridine hybrid molecule, protects against rotenone and 6-hydroxydopamine neurotoxicity. However, its protective effects against cytotoxicity induced by endogenous neurotoxins involved in Parkinson’s disease (PD) pathogenesis have never been investigated. In this study, we evaluated the ability of JM-20 to inhibit alpha-synuclein (aSyn) aggregation. We also evaluated the interactions of JM-20 with aSyn by molecular docking and molecular dynamics and assessed the protective effect of JM-20 against aminochrome cytotoxicity. We demonstrated that JM-20 induced the formation of heterogeneous amyloid fibrils, which were innocuous to primary cultures of mesencephalic cells. Moreover, JM-20 reduced the average size of aSyn positive inclusions in H4 cells transfected with SynT wild-type and synphilin-1-V5, but not in HEK cells transfected with synphilin-1-GFP. In silico studies showed the interaction between JM-20 and the aSyn-binding site. Additionally, we showed that JM-20 protects SH-SY5Y cells against aminochrome cytotoxicity. These results reinforce the potential of JM-20 as a neuroprotective compound for PD and suggest aSyn as a molecular target for JM-20
Microbial Primer: Phase variation - survival and adaptability by generation of a diverse population
No full textPhase variation is defined as the rapid and reversible switching of gene expression, and typically occurs in genes encoding surface features in small genome bacterial pathogens. Phase variation has evolved to provide an extra survival mechanism in bacteria that lack multiple ‘sense-and-respond’ gene regulation systems. Many bacterial pathogens also encode DNA methyltransferases that are phase-variable, controlling systems called ‘phasevarions’ (phase-variable regulons). This primer will summarize the current understanding of phase variation, describing the role of major phase-variable factors, and phasevarions, in bacterial pathobiology.Full Tex
Uterine transplantation: a promising surrogate to surrogacy?
No full textUterine transplantation: a promising surrogate to surrogacy?
Grynberg M1, Ayoubi JM, Bulletti C, Frydman R, Fanchin R.
Author information
Abstract
Infertility due to the inability of the uterus to carry a pregnancy ranks among the most unresolved issues in reproductive medicine. It affects millions of women worldwide who have congenital or acquired uterine affections, often requiring hysterectomy, and potentially represents a considerable fraction of the general infertile population. Patients suffering from severe uterine infertility are currently compelled to go through gestational surrogacy or adoption; both approaches, unfortunately, deprive them of the maternal experience of pregnancy and birth. Uterine transplantation represents an outstanding, yet complex, perspective to alleviating definitive uterine infertility. In the past decades, a number of scientific experiments conducted both in animals and women, focusing on uterine transplantation, have led to promising results. Collectively, these findings undoubtedly constitute a sound basis to clinically apply uterine transplantation in the near future. This paper is, however, an overview not only of the extent and limitations of accumulated scientific knowledge on uterine transplantation, but also its ethical implications, in an effort to define the actual place of such an approach among the therapeutic arsenal for alleviating infertility.
© 2011 New York Academy of Sciences
Translation and interpretation: Translation redundancy reconsidered
No full textInterpretation is an integral part of the process of translating. This article raises the question of whether interpretation fo a literary work by a translator should be guided by extratextual factors or not. The discussion is illustrated with examples taken from David Hawkes' translation of a Chinese classic, A Dream of Red Mansions. As the work of a scholar-translator, Hawkes' version is richly supplemented with disclosures concerning the characters and explanations of the cultural environment embodied in the novel. In many cases, however, this translation procedure is redundant and explanatory, enlightening the readers but at the same time robbing them of the pleasure of literary interpretation and cultural exploration. By means of this illustration of translation redundancy, the author points out that there is difference between a scholar who helps the interpretation fo a work and a translator who presents a work close to its original version. It is particularly important to pay attention tot his difference in literary translations in a cross-cultural situation involving two enormously different cultures.Language & LinguisticsA&HCI0ARTICLE1,SI115-12
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