66 research outputs found
Tween 80 induces a carbon flux rerouting in Mycobacterium tuberculosis
No full textAs a means to increase the growth rate and reduce aggregation, Tween 80 is routinely added to growth media during mycobacterial culturing. This detergent has, however, been associated with causing alterations to the morphology, pathogenicity and virulence of these bacteria. In an attempt to better understand the underlying mechanism of these alterations, we investigated the effect of Tween 80 on the metabolomes of a M. tuberculosis lab strain (H37Rv) and multidrug-resistant clinical strain (R179), using GC-GCxTOF-MS metabolomics. The metabolite markers identified indicated Tween 80-induced disparities in the central carbon metabolism of both strains, with an upregulation in the glyoxylate cycle, glucogenogenesis and the pentose phosphate pathway. The results also signified an increased production of mycobacterial biosynthetic precursors such as triacylglycerols, proteinogenic amino acids and nucleotide precursors, in the presence of the detergent. Collectively, these metabolome variations mimic the phenotypic changes observed when M. tuberculosis is grown in vivo, in a lipid rich environment. However, in addition to the increased availability of oleic acid as a carbon source from Tween 80, the observed variations, and the morphological changes associated with the detergent, could also be a result of an overall stress response in these bacteria. This study is the first to identify specific metabolome variations related to the addition of Tween 80 to the growth media during M. tuberculosis culturing. The consideration of these results during the method development and data interpretation phases of future metabolomics investigations will improve the quality of the analyses as well as the credibility of potential research outcomes. These results will also assist in the interpretation of research questions specifically aimed at aspects of mycobacterial metabolism, even when using other methodologies such as transcriptomics or fluxomic
Mycobacterium tuberculosis curli pili (MTP) is associated with significant host metabolic pathways in an A549 epithelial cell infection model and contributes to the pathogenicity of Mycobacterium tuberculosis
No full textIntroduction
A clear understanding of the metabolome of Mycobacterium tuberculosis and its target host cell during infection is fundamental for the development of novel diagnostic tools, effective drugs and vaccines required to combat tuberculosis. The surface-located Mycobacterium tuberculosis curli pili (MTP) adhesin forms initial contact with the host cell and is therefore important for the establishment of infection.
Objective
The aim of this investigation was to determine the role of MTP in modulating pathogen and host metabolic pathways in A549 epithelial cells infected with MTP proficient and deficient strains of M. tuberculosis.
Methods
Uninfected A549 epithelial cells, and those infected with M. tuberculosis V9124 wild-type strain, Δmtp and the mtp-complemented strains, were subjected to metabolite extraction, two-dimensional gas chromatography time-of-flight mass spectrometry (GCxGC-TOFMS) and bioinformatic analyses. Univariate and multivariate statistical tests were used to identify metabolites that were significantly differentially produced in the WT-infected and ∆mtp-infected A549 epithelial cell models, comparatively.
Results
A total of 46 metabolites occurred in significantly lower relative concentrations in the Δmtp-infected cells, indicating a reduction in nucleic acid synthesis, amino acid metabolism, glutathione metabolism, oxidative stress, lipid metabolism and peptidoglycan, compared to those cells infected with the WT strain.
Conclusion
The absence of MTP was associated with significant changes to the host metabolome, suggesting that this adhesin is an important contributor to the pathogenicity of M. tuberculosis, and supports previous findings of its potential as a suitable drug, vaccine and diagnostic targe
Mycobacterium tuberculosis curli pili (MTP) deficiency is associated with alterations in cell wall biogenesis, fatty acid metabolism and amino acid synthesis
No full textIntroduction
In an effort to find alternative therapeutic interventions to combat tuberculosis, a better understanding of the pathophysiology of Mycobacterium tuberculosis is required. The Mycobacterium tuberculosis curli pili (MTP) adhesin, present on the surface of this pathogen, has previously been shown using functional genomics and global transcriptomics, to play an important role in establishing infection, bacterial aggregation, and modulating host response in vitro and in vivo.
Objective
This investigation aimed to determine the role of MTP in modulating the metabolism of M. tuberculosis, using mtp gene-knockout mutant and complemented strains.
Methods
Untargeted two-dimensional gas chromatography time-of-flight mass spectrometry, and bioinformatic analyses, were used to identify significant differences in the metabolite profiles among the wild-type, ∆mtp mutant and mtp-complemented strains, and validated with results generated by real-time quantitative PCR.
Results
A total of 28 metabolites were found to be significantly altered when comparing the ∆mtp mutant and the wild-type strains indicating a decreased utilisation of metabolites in cell wall biogenesis, a reduced efficiency in the breakdown of fatty acids, and decreased amino acid biosynthesis in the former strain. Comparison of the wild-type to mtp-complement, and ∆mtp to mtp-complemented strains revealed 10 and 16 metabolite differences, respectively. Real-time quantitative PCR results supported the metabolomics findings. Complementation of the ∆mtp mutant resulted in a partial restoration of MTP function.
Conclusion
The lack of the MTP adhesin resulted in various bacterial cell wall alterations and related metabolic changes. This study highlights the importance of MTP as a virulence factor and further substantiates its potential use as a suitable biomarker for the development of diagnostic tools and intervention therapeutics against T
“There are no monsters, it’s just us”: An interview with Lauren Beukes
No full textLauren Beukes is an award-winning, internationally best-selling South African author who has gained a reputation for crossing genres and styles. Born in Johannesburg, Beukes currently lives in Cape Town, where she writes novels, comics, screenplays, TV shows and journalism. Her latest novel, Broken monsters, won Best Suspense Novel in the American Library Association’s 2015 Reading List and was recently recommended by George R.R. Martin on a list of nine books to read. Her previous novel, The shining girls, has won multiple awards, including the University of Johannesburg Prize and the Exclusive Books Bookseller’s Choice Award. Zoo City won the Arthur C. Clarke Award. I first met Beukes in early 2015 when she was doing research for her new novel at the National English Literary Museum in Grahamstown. The discussion in this interview focuses not on the ideas for her next project, but instead on the artistic motifs, philosophical issues and social themes that recur throughout her first four novels. This conversation was recorded on 13 August 2015, and took place at Beukes’s home in Tamboerskloof, Cape Town
Die gradering en ordening van drie teikentake binne 'n taakgebaseerde leer-en-onderrig-program vir nieAfrikaanssprekende internasionale universiteitstudente
No full textCITATION: Beukes, V. & Adendorff, E. 2019. Die gradering en ordening van drie teikentake binne 'n taakgebaseerde leer-en-onderrig-program vir nieAfrikaanssprekende internasionale universiteitstudente. LitNet Akademies, 16(2):554-583.The original publication is available at https://www.litnet.co.zaDie artikel spruit uit navorsing wat deur die eerste skrywer onderneem is vir die ontwerp van
’n taakgebaseerde program vir internasionale studente wat aan Universiteit Stellenbosch
studeer (Beukes 2017). Die doel van die artikel is om aan te dui hoe drie1 teikentake2 binne ’n
taakgebaseerde leer-en–onderrig-program gegradeer en georden kan word ten einde optimale
taalverwerwing3 binne sillabusontwerp te illustreer. Die studie word deur die volgende
navorsingsvraag gelei: Watter faktore moet in ag geneem word wanneer take vir ’n
taakgebaseerde program gegradeer en georden word? Onder meer Robinson (2001; 2005;
2009; 2010; 2011) se kognisiehipotese en kriteria vir die gradering en ordening van take; Pica,
Kanagy en Falodun (1993) se taaktipologie soos verwerk deur Gleason en Slater (2016); Van
Avermaet en Gysen (2006) se taalgebruiksituasies; asook Foster, Tonkyn en Wigglesworth
(2000) se Analise van Spraak- (AS-) eenhede vorm deel van die teoretiese raamwerk van
hierdie studie. Die deelnemers was die internasionale studente wat die kursus BeginnerAfrikaans Vlak I by die Universiteit Stellenbosch bygewoon het. Die kursus is deur die
Taalsentrum se personeel wat in taalverwerwing spesialiseer, ontwikkel en verfyn, en word
aangebied aan enige internasionale student wat aan die Universiteit Stellenbosch studeer en
geen voorafkennis van Afrikaans het nie. Die metodiek wat gevolg is, spruit uit die studente se
voorstelle in ’n vraelys wat as deel van ’n behoefte-ontleding aan hulle gegee is. Na aanleiding
van die teoretiese raamwerk word aangetoon hoe teikentake effektief gegradeer en georden kan
word deur die toepassing van die navorsers se aanbevelings. In die bevindinge toon ons aan
hoe die teoretiese raamwerk toegepas word op die drie teikentake wat as voorbeeld in die artikel
gebruik word.This article focuses on research previously done by the first author, who developed a taskbased teaching and learning programme for international students studying at the University of
Stellenbosch (Beukes 2017). The main aim of this article is to indicate how the grading and
sequencing of three target tasks within a task-based teaching and learning programme can be
done to optimise language acquisition. The study was conducted according to the following
research question: Which aspects should be considered during the grading and sequencing of
tasks for a task-based programme?Publisher's versio
Leveraging social capital of the church for development : a case study of a farming community in Wellington
No full textCITATION: Beukes, J. W. 2019. Leveraging social capital of the church for development : a case study of a farming community in Wellington. HTS Theological Studies, 75(4), a5528, doi:10.4102/hts.v75i4.5528.The original publication is available at https://hts.org.zaThis article explores how a farming community in Wellington (Bovlei) moved from dependence
towards an empowered community through non-profit organisations’ (NPOs) transformative
community development initiatives, undertaken together with the church’s social capital. This
example serves as the backdrop to explore critical viewpoints by various scholars who are
critical about how the church engages in an unequal and unjust society. The critical questions
that remain are the following; who is the church?, what is the church’s role as a change agent?
and how should churches leverage social capital for development? Although various definitions
have been given in conceptualising the church and its role in society, through this article, the
author engages with the social capital theory in understanding how the transformation came
about in this community by describing the churches’ involvement through a case study.Publisher's versio
Fatty Acid Metabolome Extraction from Mycobacterial Cells for GC-MS Metabolomics Analysis
No full textMetabolomics is becoming an increasingly popular research tool for identifying new biomarkers, which can, among other applications, be applied to elucidate various microbial growth and virulence mechanisms. Since the lipid composition of numerous microorganisms are unique and characteristic of the particular species, and in many instances also associated with several of their growth and virulence features, we developed a method for extracting the total free fatty acid metabolome from mycobacterial cells, in order to better characterize these using a gas chromatography–mass spectrometry (GC-MS) metabolomics approach. The described method can be considered an optimized Bligh–Dyer approach, since it uses the traditional solvents; chloroform, methanol and water, in a ratio of 1:2:1. However, due to the robust cell walls associated with mycobacteria, and many other microorganisms, the method was adapted to include a step which allows for the physical disruption of the cells using a vibration mill, which dramatically increases the efficiency of this approach. Hereafter, the organic phase is collected, dried, and methylated (as a derivatization step), prior to GC-MS analyse
Total Metabolome Extraction from Mycobacterial Cells for GC-MS Metabolomics Analysis
No full textOver the past 10 years, the number of metabolomics based publications in the available scientific literature has exponentially grown, a large portion of which describing new biomarkers better elucidating microbial disease mechanisms and improved diagnostics and treatment thereof. Here, we describe a metabolomics method for extracting the total metabolome (all compounds present in the microbial cell irrespective of the compound class), for analysis in a single analytical run using only one analytical instrument. This method includes disruption of robust microbial cell walls, and the precipitation of proteins and cell debris using a combination of mechanical methods and solvents. These extracts are subsequently derivatized, in order to improve the volatility of polar compounds for efficient gas chromatography-mass spectrometry (GC-MS) analysis. This methodology can be applied to all microbes, including those with robust cell walls, such as M. tuberculosis. To date, the biomarkers identified using this approach have led to improved tuberculosis (TB) diagnostics, improved TB treatment approaches, and better understanding of host–microbe interactions and associated mycobacterial genomic
Écologie et technologie dans les fictions d’épidémie : l’Afrique du futur entre dystopie et utopie chez Paul McAuley, Lauren Beukes, Deon Meyer et Namwali Serpell
No full textDeux imaginaires nourrissent souvent les fictions du futur : la catastrophe écologique et le développement des (bio)technologies. La réalité épidémique surgit précisément à la croisée de ces deux dimensions, permettant l’exploration d’un avenir tantôt utopique tantôt dystopique. C’est sur quatre de ces possibles futurs africains que se penchent les romans du vingt-et-unième siècle étudiés dans le présent article : Les Diables blancs (2004) du Britannique Paul McAuley, Moxyland (2008) de la Sud-Africaine Lauren Beukes, L’Année du lion (2016) de son compatriote Deon Meyer et Mustiks : une odyssée en Zambie (2019) de la Zambienne Namwali Serpell.Two imaginaries often inspire fictions of the future : the ecological catastrophe and the development of (bio)technologies. Epidemic reality arises precisely at the crossroads of these two dimensions, allowing the exploration of a future that is sometimes utopian and sometimes dystopian. The twenty-first century novels examined in this article focus on four of these possible African futures : White Devils (2004) by the British author Paul McAuley, Moxyland (2008) by South African SF-writer Lauren Beukes, Fever (2016) by her compatriot Deon Meyer and The Old Drift (2019) by the Zambian Namwali Serpell
Feasibility Study: Effect of Sample Pre-Treatment Procedures on Creatinine Results and Overall Implication on Downstream Diagnosis of Inherited Metabolic Disorders
No full textAbstract Introduction: Creatinine (Cr) is a chemical waste breakdown product of creatine and Cr levels can assist in diagnosing the functioning of the kidneys and it can be measured as part of basic- or comprehensive metabolic panel tests. Urinary creatinine (UCr) is often used to calculate urine analyte concentrations of metabolic panel tests, which emphasizes the need for infallibly accurate UCr results. Methods: Cr analysis was performed using an enzymatic Cr analysis kit. A total of four ERNDIM EQA urine samples with known Cr values and four samples with unknown Cr values were used in this study. Results: For the known Cr value samples, a percentage difference from the known value was calculated for each comparison. The rotated and centrifuged result comparison showed the lowest % difference from the known UCr value for known samples 1 and 4: 0.31% and 0.34% respectively. The centrifuged comparison showed lower % differences compared to those of the initial and repeat results. For the unknown UCr value samples results, standard deviations, averages and %CV (coefficient of variance) were calculated. Conclusion: This feasibility study, however small, is suggestive proof that there is indeed necessity and room for optimization when it comes to standardisation of pre-treatment procedures prior to UCr analysis
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