384 research outputs found
Imagining Intimacy Beyond Boundaries: \u27Born-Frees\u27 Conceptions of Race and Relationships in South Africa
No full textThough South Africans are no longer legislatively governed by the color of their skin, race remains salient in the way individuals make meaning of themselves and the world around them. Previous scholarship suggests that citizens of the ‘Rainbow Nation’ still see race as a fixed category of difference, making socialization between races fraught and relatively rare (Finchilescu et al. 2007). This study seeks to explore how born-frees understand race in South Africa’s shifting socio-political terrain through the lens of intimate interracial relationships—a form of cross-racial contact complicated by histories of sexual stigma and constraint. Conversations with 17 ‘born-frees’ across the racial spectrum centered on how youth’s sexual and romantic desires extend past the boundaries of their own race and how youth envisage interracial intimacy. From focus groups and interviews, the author produces an interrogation of the discursive links between race and sexuality in contemporary South Africa. The study explores apartheid’s legacies, current discourses of race, attraction and desire, and hopes for the future, as well as the connections these topics present to gender, class, and space. Linking historical forces to youth’s intimate worlds, the author argues that apartheid still holds powerful influence over the way youth conceptualize, desire, and enact intimacy. Attention has to be paid, however, to the growing belief in interracial intimacy as a method of achieving a more open and accepting world, as this view suggests fissures in existing notions of race and sexuality
Stress Responses in Staphylococcus aureus
No full textStaphylococcus aures are prominent members of the normal flora of humans and animals, but are also a major cause of mild and severe infections. To persist and disseminate in the human host, and to survive in environmental settings, such as hospitals, S. aureus have developed a plethora of cellular stress responses allowing it to sense and adapt to its very different niches. The stress responses often involve dramatic cellular reprogramming, and the technological advances provided by the access to whole genome sequences have let to an unprecedented insight into the global reorganization of gene and protein expression following stress-exposure. Characterization of global gene responses has been very helpful both in identifying regulators sensing specific environmental stress signals and overlaps between different stress responses. In this chapter we review the recent progress in our understanding of the specific and general S. aureusstress responses, with a special emphasis on how stress responses contribute to virulence and antibiotic resistance in this important human pathogen
Finding New Fundamental Pieces for the Bacterial Cell Division Puzzle
No full textThe division of bacterial cells into two daughter cells requires a precise balance of more than a dozen highly conserved proteins that coordinate chromosome segregation with the synthesis of the novel cell envelope. The paradigms of cell division were established in rod-shaped bacteria and this fundamental process is far less characterized in spherical bacteria. In a search for novel, essential cell division proteins in Staphylococci, Myrbråten et al. used combined depletion and subcellular localization analyses to identify the staphylococcal morphology determinant, SmdA, that is exclusively found in cocci. Knockdown of smdA results in severe division defects and increased sensitivity to cell wall targeting antibiotics. Although determining the precise role of SmdA in S. aureus cell division will require further research, this study provides a striking example of how researchers can assign functions to genes that are too fundamental to cell biology to allow genetic inactivation.</p
Expression and secretion of the RTX-toxin GtxA among members of the genus <em>Gallibacterium </em>
No full textAntibiotic Resistance and the MRSA Problem
No full textStaphylococcus aureus is capable of becoming resistant to all classes of antibiotics clinically available and resistance can develop through de novo mutations in chromosomal genes or through acquisition of horizontally transferred resistance determinants. This review covers the most important antibiotics available for treatment of S. aureus infections and a special emphasis is dedicated to the current knowledge of the wide variety of resistance mechanisms that S. aureus employ to withstand antibiotics. Since resistance development has been inevitable for all currently available antibiotics, new therapies are continuously under development. Besides development of new small molecules affecting cell viability, alternative approaches including anti-virulence and bacteriophage therapeutics are being investigated and may become important tools to combat staphylococcal infections in the future.</p
Bacterial proteases and virulence
No full textBacterial pathogens rely on proteolysis for variety of purposes during the infection process. In the cytosol, the main proteolytic players are the conserved Clp and Lon proteases that directly contribute to virulence through the timely degradation of virulence regulators and indirectly by providing tolerance to adverse conditions such as those experienced in the host. In the membrane, HtrA performs similar functions whereas the extracellular proteases, in close contact with host components, pave the way for spreading infections by degrading host matrix components or interfering with host cell signalling to short-circuit host cell processes. Common to both intra- and extracellular proteases is the tight control of their proteolytic activities. In general, substrate recognition by the intracellular proteases is highly selective which is, in part, attributed to the chaperone activity associated with the proteases either encoded within the same polypeptide or on separate subunits. In contrast, substrate recognition by extracellular proteases is less selective and therefore these enzymes are generally expressed as zymogens to prevent premature proteolytic activity that would be detrimental to the cell. These extracellular proteases are activated in complex cascades involving auto-processing and proteolytic maturation. Thus, proteolysis has been adopted by bacterial pathogens at multiple levels to ensure the success of the pathogen in contact with the human host
GtxA from <em>Gallibacterium anatis</em>, a cytolytic RTX-toxin with a novel domain organisation
No full textGallibacterium anatis is a pathogen in chickens and other avian species where it is a significant cause of salpingitis and peritonitis. We found that bacterial cells and cell-free, filter-sterilised culture supernatant from the haemolytic G. anatis biovar haemolytica were highly cytotoxic towards avian-derived macrophage-like cells (HD11). We obtained the genome sequence of G. anatis 12656-12 and used a rational approach to identify a gene predicted to encode a 2026 amino acid RTX-toxin, which we named GtxA (Gallibacterium toxin). The construction of a gtxA knock-out mutant showed gtxA to be responsible for G. anatis’ haemolytic and leukotoxic activity. In addition, Escherichia coli expressing gtxA and an adjacent acyltransferase, gtxC, became cytolytic. GtxA was expressed during in vitro growth and was localised in the extracellular protein fraction in a growth phase dependent manner. GtxA had an unusual modular structure; the C-terminal 1000 amino acids of GtxA were homologous to the classical pore-forming RTX-toxins in other members of Pasteurellaceae. In contrast, the N-terminal approximately 950 amino acids had few significant matches in sequence databases. Expression of truncated GtxA proteins demonstrated that the C-terminal RTX-domain had a lower haemolytic activity than the full-length toxin, indicating that the N-terminal domain was required for maximal haemolytic activity. Cytotoxicity towards HD11 cells was not detected with the C-terminal alone, suggesting that the N-terminal domain plays a critical role for the leukotoxicity
Clp ATPases and ClpP proteolytic complexes regulate vital biological processes in low GC, Gram-positive bacteria
No full textGlobal virulence regulation in Staphylococcus aureus:pinpointing the roles of ClpP and ClpX in the sar/agr regulatory network
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