The complete mitochondrial genome of Epomophorus gambianus (Chiroptera: Pteropodidae) and its phylogenetic analysis

The Gambian epauletted fruit bat, Epomophorus gambianus, is widely distributed across sub-Saharan Africa. Its assembled and annotated mitochondrial genome (GenBank accession no. KT963027) is 16,702 bases in length, containing 13 protein-coding genes, 22 transfer RNA genes, two ribosomal RNA genes and two non-coding regions: the control region (D-loop) and the origin of light-strand replication (OL). The average base composition is 32.2% A; 27.6% C; 14% G; and 26.1% T. The mitogenome presented a structural composition greatly conserved between members of the Pteropodidae family

Analysis of Campylobacter jejuni infection in the gnotobiotic piglet and genome-wide identification of bacterial factors required for infection

To investigate how Campylobacter jejuni causes the clinical symptoms of diarrhoeal disease in humans, use of a relevant animal model is essential. Such a model should mimic the human disease closely in terms of host physiology, incubation period before onset of disease, clinical signs and a comparable outcome of disease. In this study, we used a gnotobiotic piglet model to study determinants of pathogenicity of C. jejuni. In this model, C. jejuni successfully established infection and piglets developed an increased temperature with watery diarrhoea, which was caused by a leaky epithelium and reduced bile re-absorption in the intestines. Further, we assessed the C. jejuni genes required for infection of the porcine gastrointestinal tract utilising a transposon (Tn) mutant library screen. A total of 123 genes of which Tn mutants showed attenuated piglet infection were identified. Our screen highlighted a crucial role for motility and chemotaxis, as well as central metabolism. In addition, Tn mutants of 14 genes displayed enhanced piglet infection. This study gives a unique insight into the mechanisms of C. jejuni disease in terms of host physiology and contributing bacterial factors.This work was funded by BBSRC awards BB/F020988/1 and BB/K004514/1. Moredun Research Institute receives funding via Rural and Environment Science and Analytical Services (RESAS) division of the Scottish Government. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Comparative analysis and supragenome modeling of twelve Moraxella catarrhalis clinical isolates

Contains fulltext : 97744.pdf (publisher's version ) (Open Access)BACKGROUND: M. catarrhalis is a gram-negative, gamma-proteobacterium and an opportunistic human pathogen associated with otitis media (OM) and exacerbations of chronic obstructive pulmonary disease (COPD). With direct and indirect costs for treating these conditions annually exceeding $33 billion in the United States alone, and nearly ubiquitous resistance to beta-lactam antibiotics among M. catarrhalis clinical isolates, a greater understanding of this pathogen's genome and its variability among isolates is needed. RESULTS: The genomic sequences of ten geographically and phenotypically diverse clinical isolates of M. catarrhalis were determined and analyzed together with two publicly available genomes. These twelve genomes were subjected to detailed comparative and predictive analyses aimed at characterizing the supragenome and understanding the metabolic and pathogenic potential of this species. A total of 2383 gene clusters were identified, of which 1755 are core with the remaining 628 clusters unevenly distributed among the twelve isolates. These findings are consistent with the distributed genome hypothesis (DGH), which posits that the species genome possesses a far greater number of genes than any single isolate. Multiple and pair-wise whole genome alignments highlight limited chromosomal re-arrangement. CONCLUSIONS: M. catarrhalis gene content and chromosomal organization data, although supportive of the DGH, show modest overall genic diversity. These findings are in stark contrast with the reported heterogeneity of the species as a whole, as wells as to other bacterial pathogens mediating OM and COPD, providing important insight into M. catarrhalis pathogenesis that will aid in the development of novel therapeutic regimens

Unexpected differential metabolic responses of Campylobacter jejuni to the abundant presence of glutamate and fucose

Introduction: Campylobacter jejuni is the leading cause of foodborne bacterial enteritis in humans, and yet little is known in regard to how genetic diversity and metabolic capabilities among isolates affect their metabolic phenotype and pathogenicity. Objectives: For instance, the C. jejuni 11168 strain can utilize both l-fucose and l-glutamate as a carbon source, which provides the strain with a competitive advantage in some environments and in this study we set out to assess the metabolic response of C. jejuni 11168 to the presence of l-fucose and l-glutamate in the growth medium. Methods: To achieve this, untargeted hydrophilic liquid chromatography coupled to mass spectrometry was used to obtain metabolite profiles of supernatant extracts obtained at three different time points up to 24 h. Results: This study identified both the depletion and the production and subsequent release of a multitude of expected and unexpected metabolites during the growth of C. jejuni 11168 under three different conditions. A large set of standards allowed identification of a number of metabolites. Further mass spectrometry fragmentation analysis allowed the additional annotation of substrate-specific metabolites. The results show that C. jejuni 11168 upon l-fucose addition indeed produces degradation products of the fucose pathway. Furthermore, methionine was faster depleted from the medium, consistent with previously-observed methionine auxotrophy. Conclusions: Moreover, a multitude of not previously annotated metabolites in C. jejuni were found to be increased specifically upon l-fucose addition. These metabolites may well play a role in the pathogenicity of this C. jejuni strain.</p

Analysis of Campylobacter jejuni\textit{Campylobacter jejuni} infection in the gnotobiotic piglet and genome-wide

To investigate how $\textit{Campylobacter jejuni}$ causes the clinical symptoms of diarrhoeal disease in humans, use of a relevant animal model is essential. Such a model should mimic the human disease closely in terms of host physiology, incubation period before onset of disease, clinical signs and a comparable outcome of disease. In this study, we used a gnotobiotic piglet model to study determinants of pathogenicity of C. $\textit{C. jejuni}$. In this model, C. $\textit{C. jejuni}$ successfully established infection and piglets developed an increased temperature with watery diarrhoea, which was caused by a leaky epithelium and reduced bile re-absorption in the intestines. Further, we assessed the C. $\textit{C. jejuni}$ genes required for infection of the porcine gastrointestinal tract utilising a transposon (Tn) mutant library screen. A total of 123 genes of which Tn mutants showed attenuated piglet infection were identified. Our screen highlighted a crucial role for motility and chemotaxis, as well as central metabolism. In addition, Tn mutants of 14 genes displayed enhanced piglet infection. This study gives a unique insight into the mechanisms of C. $\textit{C. jejuni}$ disease in terms of host physiology and contributing bacterial factors.This work was funded by BBSRC awards BB/F020988/1 and BB/K004514/1. Moredun Research Institute receives funding via Rural and Environment Science and Analytical Services (RESAS) division of the Scottish Government

Analysis of Campylobacter jejuni\textit{Campylobacter jejuni} infection in the gnotobiotic piglet and genome-wide

To investigate how $\textit{Campylobacter jejuni}$ causes the clinical symptoms of diarrhoeal disease in humans, use of a relevant animal model is essential. Such a model should mimic the human disease closely in terms of host physiology, incubation period before onset of disease, clinical signs and a comparable outcome of disease. In this study, we used a gnotobiotic piglet model to study determinants of pathogenicity of C. $\textit{C. jejuni}$. In this model, C. $\textit{C. jejuni}$ successfully established infection and piglets developed an increased temperature with watery diarrhoea, which was caused by a leaky epithelium and reduced bile re-absorption in the intestines. Further, we assessed the C. $\textit{C. jejuni}$ genes required for infection of the porcine gastrointestinal tract utilising a transposon (Tn) mutant library screen. A total of 123 genes of which Tn mutants showed attenuated piglet infection were identified. Our screen highlighted a crucial role for motility and chemotaxis, as well as central metabolism. In addition, Tn mutants of 14 genes displayed enhanced piglet infection. This study gives a unique insight into the mechanisms of C. $\textit{C. jejuni}$ disease in terms of host physiology and contributing bacterial factors.This work was funded by BBSRC awards BB/F020988/1 and BB/K004514/1. Moredun Research Institute receives funding via Rural and Environment Science and Analytical Services (RESAS) division of the Scottish Government

Genomic variations leading to alterations in cell morphology of Campylobacter\textit{Campylobacter} spp

$\textit{Campylobacter jejuni}$, the most common cause of bacterial diarrhoeal disease, is normally helical. However, it can also adopt straight rod, elongated helical and coccoid forms. Studying how helical morphology is generated, and how it switches between its different forms, is an important objective for understanding this pathogen. Here, we aimed to determine the genetic factors involved in generating the helical shape of $\textit{Campylobacter}$. A C. $\textit{jejuni}$ transposon (Tn) mutant library was screened for non-helical mutants with inconsistent results. Whole genome sequence variation and morphological trends within this Tn library, and in various C. $\textit{jejuni}$ wild type strains, were compared and correlated to detect genomic elements associated with helical and rod morphologies. All rod-shaped C. $\textit{jejuni}$ Tn mutants and all rod-shaped laboratory, clinical and environmental C. $\textit{jejuni}$ and $\textit{Campylobacter coli}$ contained genetic changes within the $\textit{pgp1}$ or $\textit{pgp2}$ genes, which encode peptidoglycan modifying enzymes. We therefore confirm the importance of Pgp1 and Pgp2 in the maintenance of helical shape and extended this to a wide range of C. $\textit{jejuni}$ and C. $\textit{coli}$ isolates. Genome sequence analysis revealed variation in the sequence and length of homopolymeric tracts found within these genes, providing a potential mechanism of phase variation of cell shape.This work was funded by The Wellcome Trust through a PhD training studentship awarded to DE, and was supported by an Isaac Newton Trust/Wellcome Trust ISSF/University of Cambridge joint research grant awarded to AJG. SG and SPWDV were funded by BBSRC grant BB/K004514/1. AEM, SH, NRT and JP were supported by the Wellcome Trust grant number 098051. AEM was also supported by BBSRC grant BB/M014088/1. SKS was funded by Biotechnology and Biological Sciences Research Council grant BB/I02464X/1, Medical Research Council grant MR/L015080/1 and Wellcome Trust grant 088786/C/09/Z. GM was supported by a National Institute for Social Care and Health Research Fellowship (HF-14-13)

Genome-wide association of functional traits linked with Campylobacter jejuni survival from farm to fork

Campylobacter jejuni is a major cause of bacterial gastroenteritis worldwide, primarily associated with the consumption of contaminated poultry. C. jejuni lineages vary in host range and prevalence in human infection, suggesting differences in survival throughout the poultry processing chain. From 7343 MLST-characterised isolates, we sequenced 600 C. jejuni and C. coli isolates from various stages of poultry processing and clinical cases. A genome-wide association study (GWAS) in C. jejuni ST-21 and ST-45 complexes identified genetic elements over-represented in clinical isolates that increased in frequency throughout the poultry processing chain. Disease-associated SNPs were distinct in these complexes, sometimes organised in haplotype blocks. The function of genes containing associated elements was investigated, demonstrating roles for cj1377c in formate metabolism, nuoK in aerobic survival and oxidative respiration, and cj1368-70 in nucleotide salvage. This work demonstrates the utility of GWAS for investigating transmission in natural zoonotic pathogen populations and provides evidence that major C. jejuni lineages have distinct genotypes associated with survival, within the host specific niche, from farm to fork