Deletion of PimE mannosyltransferase results in increased copper sensitivity in Mycobacterium smegmatis

Abstract

The unique cell envelope structure of Mycobacterium tuberculosis is fundamental to its pathogenesis. Phosphatidylinositol (PI)-anchored glycolipids, such as PI mannosides (PIMs), lipomannan, and lipoarabinomannan, are essential components of the cell envelope widely conserved among mycobacteria, but their roles in the cell envelope integrity are not fully understood. We previously identified PimE in Mycobacterium smegmatis, a nonpathogenic model organism, as a mannosyltransferase that catalyzes the fifth mannose transfer for the biosynthesis of hexamannosyl PIMs. Our analyses, reported here, further demonstrate that the growth of the pimE deletion mutant (ΔpimE) is defective in the presence of copper. We first found that the small colony phenotype of ΔpimE on a solid Middlebrook 7H10 agar surface was alleviated when grown on M63 agar. Comparative analysis of the two media led us to identify copper in Middlebrook 7H10 as the cause of growth retardation seen in ΔpimE. We further demonstrated that ΔpimE is sensitized to several antibiotics, but the increased sensitivities were independent of the presence of copper. We conclude that the deletion of the pimE gene does not cause growth defects under optimal growth conditions, but makes the cell envelope vulnerable to toxic compounds such as copper and antibiotics.

http://ift.tt/2E1XNA4

A Case of First Branchial Cleft Fistula Presenting with an External Opening on the Root of the Helical Crus

Background. First branchial cleft anomalies (FBCA) are rare clinical entities of the head and neck. Typically, the tract of the FBCA begins in the external auditory canal and ends in the postauricular or submandibular region. Case Presentation. We present a case of a 23-year-old man who had a first branchial cleft fistula with atypical opening on the root of the helical crus. Complete excision of the tract, including the cuff of surrounding cartilage, was performed. Histopathology revealed a fistular tract lined with squamous epithelium. To our knowledge, this is the first case to be reported of type I FBCA with an opening on the root of the helical crus. The low incidence and varied presentation often result in misdiagnosis and inappropriate treatment. Conclusions. In the patients with FBCA, careful recognition of atypical variants is essential for complete excision.

http://ift.tt/2EmG4B6

Endosymbiont diversity and prevalence in herbivorous spider mite populations in South-Western Europe

Abstract

Bacterial endosymbionts are known as important players of the evolutionary ecology of their hosts. However, their distribution, prevalence and diversity are still largely unexplored. To this aim, we investigated infections by the most common bacterial reproductive manipulators in herbivorous spider mites of South-Western Europe. Across 16 populations belonging to three Tetranychus species, Wolbachia was the most prevalent (ca. 61%), followed by Cardinium (12–15%), while only few individuals were infected by Rickettsia (0.9–3%), and none carried Arsenophonus or Spiroplasma. These endosymbionts are here reported for the first time in T. evansi and T. ludeni, and showed variable infection frequencies between and within species, with several cases of coinfections. Moreover, Cardinium was more prevalent in Wolbachia-infected individuals, which suggests facilitation between these symbionts. Finally, sequence comparisons revealed no variation of the Wolbachia wsp and Rickettsia gtlA genes, but some diversity of the Cardinium 16S rRNA, both between and within populations of the three mite species. Some of the Cardinium sequences identified belonged to distantly related clades, and the lack of association between these sequences and spider mite mitotypes suggests repeated host switching of Cardinium. Overall, our results reveal a complex community of symbionts in this system, opening the path for future studies.

http://ift.tt/2rUEvrK

An integrative overview of genomic, transcriptomic and proteomic analyses in organohalide respiration research

Abstract

Organohalide respiration (OHR) is a crucial process in the global halogen cycle and of interest for bioremediation. However, investigations on OHR are hampered by the restricted genetic accessibility and the poor growth yields of many organohalide-respiring bacteria (OHRB). Therefore, genomics, transcriptomics and proteomics are often used to investigate OHRB. In general, these gene expression studies are more useful when the data of the different 'omics' approaches are integrated and compared among a wide range of cultivation conditions and ideally involve several closely related OHRB. Despite the availability of a couple of proteomic and transcriptomic datasets dealing with OHRB, such approaches are currently not covered in reviews. Therefore, we here present an integrative and comparative overview of omics studies performed with the OHRB Sulfurospirillum multivorans, Dehalococcoides mccartyi, Desulfitobacterium spp. and Dehalobacter restrictus. Genes, transcripts, proteins and the regulatory and biochemical processes involved in OHR are discussed and a comprehensive view on the unusual metabolism of D. mccartyi, which is one of the few bacteria possibly using a quinone-independent respiratory chain, is provided. Several 'omics'-derived theories on OHRB, e.g. the organohalide-respiratory chain, hydrogen metabolism, corrinoid biosynthesis or one-carbon metabolism are critically discussed on the basis of this integrative approach.

http://ift.tt/2GtQksd

Discerning autotrophy, mixotrophy, and heterotrophy in marine TACK archaea from the North Atlantic

Abstract

DNA stable isotope probing (SIP) was used to track the uptake of organic and inorganic carbon sources for TACK archaea (Thaumarchaeota/Aigarchaeota/Crenarchaeota/Korarchaeota) on a cruise of opportunity in the North Atlantic. Due to water limitations, duplicate samples from the deep photic (60–115 m), the mesopelagic zones (local oxygen minimum; 215–835 m), and the bathypelagic zone (2085–2835 m) were amended with various combinations of ¹²C- or ¹³C-acetate/urea/bicarbonate to assess cellular carbon acquisition. The SIP results indicated the majority of TACK archaeal operational taxonomic units (OTUs) incorporated ¹³C from acetate and/or urea into newly synthesized DNA within 48 hours. A small fraction (16%) of the OTUs, often representing the most dominant members of the archaeal community, were able to incorporate bicarbonate in addition to organic substrates. Only two TACK archaeal OTUs were found to incorporate bicarbonate but not urea or acetate. These results further demonstrate the utility of SIP to elucidate the metabolic capability of mesothermal archaea in distinct oceanic settings and suggest that TACK archaea play a role in organic carbon recycling in the mid-depth to deep ocean.

http://ift.tt/2rOK2Qx

Accelerated induction regimens of TNF-alpha inhibitors in patients with inflammatory bowel disease: a scoping review protocol

Introduction

Tumour necrosis factor (TNF)-alpha inhibitors are commonly used to treat inflammatory bowel disease (IBD). In patients with IBD who are unresponsive to their first induction dose, the implementation of an 'accelerated' induction dose schedule (doses more frequent than recommended in product monographs) is becoming increasingly common. It is unclear whether this practice results in favourable patient outcomes, such as avoidance of surgery and disease remission. As such, there is a need to identify and map the current evidence base on accelerated induction schedules of these medications in the treatment of IBD.

Methods and analysis

A scoping review will be employed to systematically identify and characterise the nature of scientific literature on accelerated induction regimens of TNF-alpha inhibitors. MEDLINE, Embase, International Pharmaceutical Abstracts and grey literature will be searched to identify relevant studies. The titles/abstracts of all records and full text of potentially relevant articles will be independently screened for inclusion by two reviewers. Data will be abstracted from included studies by one reviewer and verified for accuracy by another. The findings will be synthesised descriptively.

Ethics and dissemination

We intend to report the findings of this scoping review in a peer-reviewed journal and a scientific conference.

Trial registration

This research was registered prospectively with the Open Science Framework (https://osf.io/z7n2d/).

http://ift.tt/2DLwSFu

Health science communication strategies used by researchers with the public in the digital and social media ecosystem: a systematic scoping review protocol

Introduction

The optimisation of health science communication (HSC) between researchers and the public is crucial. In the last decade, the rise of the digital and social media ecosystem allowed for the disintermediation of HSC. Disintermediation refers to the public's direct access to information from researchers about health science-related topics through the digital and social media ecosystem, a process that would otherwise require a human mediator, such as a journalist. Therefore, the primary aim of this scoping review is to describe the nature and the extent of the literature regarding HSC strategies involving disintermediation used by researchers with the public in the digital and social media ecosystem. The secondary aim is to describe the HSC strategies used by researchers, and the communication channels associated with these strategies.

Methods and analysis

We will conduct a scoping review based on the Joanna Briggs Institute's methodology and perform a systematic search of six bibliographical databases (CINAHL, EMBASE, IBSS, PubMed, Sociological Abstracts and Web of Science), four trial registries and relevant sources of grey literature. Relevant journals and reference lists of included records will be hand-searched. Data will be managed using the EndNote software and the Rayyan web application. Two review team members will perform independently the screening process as well as the full-text assessment of included records. Descriptive data will be synthesised in a tabular format. Data regarding the nature and the extent of the literature, the HSC strategies and the associated communication channels will be presented narratively.

Ethics and dissemination

This review does not require institutional review board approval as we will use only collected and published data. Results will allow the mapping of the literature about HSC between researchers and the public in the digital and social media ecosystem, and will be published in a peer-reviewed journal.

http://ift.tt/2DNuo9L