Streptolysin O and its Co-Toxin NAD-glycohydrolase Protect Group A Streptococcus from Xenophagic Killing

Group A Streptococcus (Streptococcus pyogenes or GAS) causes pharyngitis, severe invasive infections, and the post-infectious syndromes of glomerulonephritis and rheumatic fever. GAS can be internalized and killed by epithelial cells in vitro, a process that may contribute to local innate defense against pharyngeal infection. Secretion of the pore-forming toxin streptolysin O (SLO) by GAS has been reported to stimulate targeted autophagy (xenophagy) upon internalization of the bacteria by epithelial cells. Whereas this process was associated with killing of GAS in HeLa cells, studies in human keratinocytes found SLO production enhanced intracellular survival. To reconcile these conflicting observations, we now report in-depth investigation of xenophagy in response to GAS infection of human oropharyngeal keratinocytes, the predominant cell type of the pharyngeal epithelium. We found that SLO expression was associated with prolonged intracellular survival; unexpectedly, expression of the co-toxin NADase was required for this effect. Enhanced intracellular survival was lost upon deletion of NADase or inactivation of its enzymatic activity. Shortly after internalization of GAS by keratinocytes, SLO-mediated damage to the bacteria-containing vacuole resulted in exposure to the cytosol, ubiquitination of GAS and/or associated vacuolar membrane remnants, and engulfment of GAS in LC3-positive vacuoles. We also found that production of streptolysin S could mediate targeting of GAS to autophagosomes in the absence of SLO, a process accompanied by galectin 8 binding to damaged GAS-containing endosomes. Maturation of GAS-containing autophagosome-like vacuoles to degradative autolysosomes was prevented by SLO pore-formation and by SLO-mediated translocation of enzymatically active NADase into the keratinocyte cytosol. We conclude that SLO stimulates xenophagy in pharyngeal keratinocytes, but the coordinated action of SLO and NADase prevent maturation of GAS-containing autophagosomes, thereby prolonging GAS intracellular survival. This novel activity of NADase to block autophagic killing of GAS in pharyngeal cells may contribute to pharyngitis treatment failure, relapse, and chronic carriage

Smoking around the campfire: A San encounter with the colonial

In 1873 Joseph Orpen, resident of Nomansland, engaged a San1 man Qing to guide a combined force of levies and mounted police through the Maloti mountains in present-day Lesotho where they hoped to intercept a group of reluctant Hlubi rebels under chief Langalibalele. Orpen was not only a colonial official but also a keen scholar. In response to his questions Qing commented on some of the rock paintings they saw on their short journey and recounted folklore. A year later Qing’s narratives and his comments on rock art were published along with Orpen’s account of the journey and ‘remarks’ by the celebrated linguist and collector of |Xam narrative, Wilhelm Bleek in an article in the Cape Monthly Magazine (CMM). Orpen’s piece has enjoyed a seminal position in San studies ever since, especially in the field of rock art. The encounter between Qing and Orpen occurred in a context of colonial violence. Not only was the campaign that was being pursued against Langalibalele and his men unnecessary but the San had been subject to genocidal attacks by both regular and irregular colonial forces for a considerable period of time, and the studies of San rock art and narrative at the time were largely carried out in an intellectual climate that saw the extinction of the San as inevitable. This article will locate the CMM article more firmly in its colonial context by combining a close reading of elements of the CMM article itself with a consideration of a wider body of writing that relates to Orpen’s piece.IBS

Representations of revolutionary violence in recent Indian and South African fiction

Several recent novels in English by Indian and South African authors explore the theme of violent political resistance to the entrenched injustices of the hierarchical Indian social order and South Africa’s institutionalised system of racial and economic domination, respectively. This article will investigate and compare the ways in which this theme is treated in four novels: Jhumpa Lahiri’s Lowland (2013), Neel Mukherjee’s Lives of Others (2015), Mandla Langa’s The Texture of Shadows (2014) and Nkosinathi Sithole’s Hunger Eats a Man (2015). The first two chart the consequences for their protagonists of their participation in the Naxalite insurrection in the late 1960s. While Langa’s The Texture of Shadows does not question the decision to engage in armed struggle against the apartheid regime, it refuses to evade the bitter consequences of this decision both for individuals and for the country more generally. Nkosinathi Sithole’s Hunger Eats a Man situates the theme of resistance in relation to the extreme poverty and inequality of the contemporary South African countryside. The comparative approach followed in this article reveals continuities in the representation of resistant violence in the Indian and South African texts in terms of its consequences both for individuals and for post-revolutionary society. At the same time, the comparison exposes significant disjunctions relating to national and generational histories, political ideologies and the ways in which race, class, caste and gender intersect with political resistance in the two countries, as these concerns are imagined in fiction.IS

Optical Satellite Volcano Monitoring: A Multi-Sensor Rapid Response System

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'A glimpse into Bushman mythology': interpretation, power and knowledge

In 1873, Qing, a young man of Bushman background, recounted a cycle of stories and commented on some of the rock paintings he and the magistrate Joseph Orpen saw on a journey through the Maloti mountains. A year later Qing's narratives and comments on rock art, as recorded by Orpen, were published along with Orpen's account of the journey in an article in The Cape Monthly Magazine. The article is a blend of European and indigenous discourses and forms of knowledge, the latter mediated by the processes of recording, translation, writing and publication. This essay explores the different sorts of knowledge that are represented in the text, in Orpen's statements about his research and in Qing's stories in particular. It uses the literary technique of close reading in order to open the text up to different possibilities of reading and interpretation.Scopu

Interpretation and the /Xam narratives.

Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2006.There has, in the last quarter of a century, been an increased interest in the /Xam narratives that form the major part of the nineteenth century archive of materials collected by Lucy Lloyd and Wilhelm Bleek in Cape Town from /Xam informants. This has resulted in a proliferation of writing about the Bleek and Lloyd collection and its contents. The critical examination of some of this body of writing forms part of the project of this thesis. The other aim of the thesis is to provide a close reading of certain of the /Xam texts themselves. This thesis is based on the view that the first of these projects has only been attempted in a cursory and indirect fashion and that the second, namely the close reading of/Xam texts, has not yet been undertaken on a scale that parallels the range and complexity of the materials or which exhausts the interpretative possibilities they offer. This thesis aims to fill some of these gaps in the literature without claiming that a comprehensive or definitive study is possible in so wide and rich a field. Postmodern and postcolonial theory has emphasised the discursive and ideological nature of the language of both hermeneutics and literature. In my consideration of the /Xam texts and the writing that has been produced in relation to them, I attempt to consistently foreground the historicity and textuality of my own practice and the practices of the materials with which I am working. In this regard I question, especially, two assumptions about the /Xam narratives: that they are primarily aetiological and that their chief character, /Kaggen, the Mantis, is a trickster

The Use of Financial Literacy for Growing Personal Finance

Financial literacy played an important role for everyone in managing personal finances.This research aimed to determine how the level of financial literacy in students S1 Facultyof Economics and Business, Universitas Pasundan and investigate what factors are influencingit. The observed respondents were students from the Faculty of Economics andBusiness, Universitas Pasundan. The research data was collected through questionnaires,descriptive analysis, and test multinomial logit. Based on the results of the researchshowed that the level of financial literacy from undergraduate students UniversitasPasundan was in the low category. Financial literacy was determined by gender, GreaterAcademic Achievement (GPA), parental education level, and parental income level;,whereas for age, year of study and residence do not contribute to the research model. Theresults of this study were expected to support personal financial planning of students inimproving the skills of reading, analyzing, and managing their own finances, thus avoidingthe daily financial problems

Streptolysin O and NAD-Glycohydrolase Prevent Phagolysosome Acidification and Promote Group A Streptococcus Survival in Macrophages

ABSTRACT Group A Streptococcus (GAS, Streptococcus pyogenes) is an ongoing threat to human health as the agent of streptococcal pharyngitis, skin and soft tissue infections, and life-threatening conditions such as necrotizing fasciitis and streptococcal toxic shock syndrome. In animal models of infection, macrophages have been shown to contribute to host defense against GAS infection. However, as GAS can resist killing by macrophages in vitro and induce macrophage cell death, it has been suggested that GAS intracellular survival in macrophages may enable persistent infection. Using isogenic mutants, we now show that the GAS pore-forming toxin streptolysin O (SLO) and its cotoxin NAD-glycohydrolase (NADase) mediate GAS intracellular survival and cytotoxicity for macrophages. Unexpectedly, the two toxins did not inhibit fusion of GAS-containing phagosomes with lysosomes but rather prevented phagolysosome acidification. SLO served two essential functions, poration of the phagolysosomal membrane and translocation of NADase into the macrophage cytosol, both of which were necessary for maximal GAS intracellular survival. Whereas NADase delivery to epithelial cells is mediated by SLO secreted from GAS bound to the cell surface, in macrophages, the source of SLO and NADase is GAS contained within phagolysosomes. We found that transfer of NADase from the phagolysosome to the macrophage cytosol occurs not by simple diffusion through SLO pores but rather by a specific translocation mechanism that requires the N-terminal translocation domain of NADase. These results illuminate the mechanisms through which SLO and NADase enable GAS to defeat macrophage-mediated killing and provide new insight into the virulence of a major human pathogen

Identification of Group A Streptococcus Genes Directly Regulated by CsrRS and Novel Intermediate Regulators

Adaptation of group A Streptococcus (GAS) to its human host is mediated by two-component systems that transduce external stimuli to regulate bacterial physiology. Among such systems, CsrRS (also known as CovRS) is the most extensively characterized for its role in regulating ∼10% of the GAS genome, including several virulence genes. Here, we show that extracellular magnesium and the human antimicrobial peptide LL-37 have opposing effects on the phosphorylation of the response regulator CsrR by the receptor kinase CsrS. Genetic inactivation of CsrS phosphatase or kinase activity, respectively, had similar but more pronounced effects on CsrR phosphorylation compared to growth in magnesium or LL-37. These changes in CsrR phosphorylation were correlated with the repression or activation of CsrR-regulated genes as assessed by NanoString analysis. Chromatin immunoprecipitation and DNA sequencing (ChIP-seq) revealed CsrR occupancy at CsrRS-regulated promoters and lower-affinity associations at many other locations on the GAS chromosome. Because ChIP-seq did not detect CsrR occupancy at promoters associated with some CsrR-regulated genes, we investigated whether these genes might be controlled indirectly by intermediate regulators whose expression is modulated by CsrR. Transcriptional profiling of mutant strains deficient in the expression of either of two previously uncharacterized transcription regulators in the CsrR regulon indicated that one or both proteins participated in the regulation of 22 of the 42 CsrR-regulated promoters for which no CsrR association was detected by ChIP-seq. Taken together, these results illuminate CsrRS-mediated regulation of GAS gene expression through modulation of CsrR phosphorylation, CsrR association with regulated promoters, and the control of intermediate transcription regulators. Importance: Group A Streptococcus (GAS) is an important public health threat as a cause of sore throat, skin infections, life-threatening invasive infections, and the postinfectious complications of acute rheumatic fever, a leading cause of acquired heart disease. This work characterizes CsrRS, a GAS system for the detection of environmental signals that enables adaptation of the bacteria for survival in the human throat by regulating the production of products that allow the bacteria to resist clearance by the human immune system. CsrRS consists of two proteins: CsrS, which is on the bacterial surface to detect specific stimuli, and CsrR, which receives signals from CsrS and, in response, represses or activates the expression of genes coding for proteins that enhance bacterial survival. Some of the genes regulated by CsrR encode proteins that are themselves regulators of gene expression, thereby creating a regulatory cascade