Conformational Changes in Pediocin AcH upon Vesicle Binding and Approximation of the Membrane-Bound Structure in Detergent Micelles

Pediocin AcH is a 44-residue antimicrobial peptide with bactericidal potency against Gram-positive bacteria such as Listeria. It belongs to a family of bacteriocins that, when membrane-associated, is predicted to contain β-sheet and α-helical regions. All bacteriocins in this family have a conserved N-terminal disulfide bond. An additional C-terminal disulfide bond in pediocin AcH is thought to confer enhanced potency and broader specificity range against sensitive bacteria. The C-terminal disulfide bond may also affect the conformation of the C-terminus. The secondary structures of pediocin AcH in aqueous solution and vesicles from susceptible cells, as well as the ability of trifluoroethanol (TFE) and detergent systems to induce secondary structures like those induced in vesicles, were studied by circular dichroism (CD) spectroscopy. Like related peptides, pediocin AcH was highly unordered in aqueous solution, 56%. However, it also contained 20% β-strand and 15% β-turn structures. Upon complete binding to vesicles, 32% α-helical structure formed, the unordered structure decreased to 32%, and the β-strand and β-turn structures remained largely unchanged. Thus, a βα domain structure formed in vesicles. The helical structure likely forces the C-terminal tail to loop back on the helix so that the C24−C44 disulfide bond can form. Detergent micelles were superior to TFE in their ability to induce secondary structural fractions in pediocin AcH comparable to those observed in vesicles. This demonstrates the importance of a hydrocarbon−water interface to pediocin AcH structure induction and suggests that it is preferable to use detergent micelles as solvents in NMR studies of pediocin AcH structure

4-(8-Eth­oxy-2,3-dihydro-1H-cyclo­penta­[c]quinolin-4-yl)butane-1-peroxol

In the title mol­ecule, C18H23NO3, the hydro­per­oxy­butyl substituent is nearly fully extended, with the four torsion angles in the range 170.23 (10)–178.71 (9)°. The O—O distance in the hydro­peroxide group is 1.4690 (13) Å. This group acts as an inter­molecular hydrogen-bond donor to a quinoline N atom. This results in dimeric units about the respective inversion centers, with graph-set notation R 2 2(18)

Synthetic Plasmodium-Like Hemozoin Activates the Immune Response: A Morphology - Function Study

Increasing evidence points to an important role for hemozoin (HZ), the malaria pigment, in the immunopathology related to this infection. However, there is no consensus as to whether HZ exerts its immunostimulatory activity in absence of other parasite or host components. Contamination of native HZ preparations and the lack of a unified protocol to produce crystals that mimic those of Plasmodium HZ (PHZ) are major technical limitants when performing functional studies with HZ. In fact, the most commonly used methods generate a heterogeneous nanocrystalline material. Thus, it is likely that such aggregates do not resemble to PHZ and differ in their inflammatory properties. To address this issue, the present study was designed to establish whether synthetic HZ (sHZ) crystals produced by different methods vary in their morphology and in their ability to activate immune responses. We report a new method of HZ synthesis (the precise aqueous acid-catalyzed method) that yields homogeneous sHZ crystals (Plasmodium-like HZ) which are very similar to PHZ in their size and physicochemical properties. Importantly, these crystals are devoid of protein and DNA contamination. Of interest, structure-function studies revealed that the size and shape of the synthetic crystals influences their ability to activate inflammatory responses (e.g. nitric oxide, chemokine and cytokine mRNA) in vitro and in vivo. In summary, our data confirm that sHZ possesses immunostimulatory properties and underline the importance of verifying by electron microscopy both the morphology and homogeneity of the synthetic crystals to ensure that they closely resemble those of the parasite. Periodic quality control experiments and unification of the method of HZ synthesis are key steps to unravel the role of HZ in malaria immunopathology

Multiple stressors in Southern Africa: the link between HIV/AIDS, food insecurity, poverty and children's vulnerability now and in the future

Several countries in Southern Africa now see large numbers of their population barely subsisting at poverty levels in years without shocks, and highly vulnerable to the vagaries of the weather, the economy and government policy. The combination of HIV/AIDS, food insecurity and a weakened capacity for governments to deliver basic social services has led to the region experiencing an acute phase of a long-term emergency. “Vulnerability” is a term commonly used by scientists and practitioners to describe these deteriorating conditions. There is particular concern about the “vulnerability” of children in this context and implications for children's future security. Through a review of literature and recent case studies, and using a widely accepted conceptualisation of vulnerability as a lens, we reflect on what the regional livelihoods crisis could mean for children's future wellbeing. We argue that an increase in factors determining the vulnerability of households — both through greater intensity and frequency of shocks and stresses (“external” vulnerability) and undermined resilience or ability to cope (“internal” vulnerability) — are threatening not only current welfare of children, but also their longer-term security. The two specific pathways we explore are (1) erosive coping strategies employed by families and individuals; and (2) their inability to plan for the future. We conclude that understanding and responding to this crisis requires looking at the complexity of these multiple stressors, to try to comprehend their interconnections and causal links. Policy and programme responses have, to date, largely failed to take into account the complex and multi-dimensional nature of this crisis. There is a misfit between the problem and the institutional response, as responses from national and international players have remained relatively static. Decisive, well-informed and holistic interventions are needed to break the potential negative cycle that threatens the future security of Southern Africa's children

Inland Pacific Northwest pasture calendar

The Inland Pacific Northwest (PNW) region, historically referred to as the 'Inland Empire', extends from the Cascade Mountains in the west to former Glacial Lake Missoula in the Rockies in the east and from the Canadian border in the north past the Snake River Canyon in the south. The greatest agricultural enterprises are hay (from various forage species), irrigated and non-irrigated grassland pastures, rangelands, and livestock production. It is also home to numerous wildlife species and flyways for migrating birds. The Inland PNW Pasture Calendar is designed to be a comprehensive guide for improved grassland management in support of forage-livestock systems. Applying the principles described will lead to improved regional economic, ecological, and social sustainability. This publication describes the opportunities and challenges of sustainably raising harvested and grazed forages and developing forage-livestock systems in this incredibly diverse environment. Appendix Chapters provide key information on grass / legume / forb species, how pasture species grow and regrow, soil nutrient management and organic matter, grazing philosophies and systems, matching grazing needs for pasture production, and forage-related animal health issues. Learning these key principles and following best management practices described will lead to improved sustainability of forage-livestock systems

why do romanian universities fail to internalize quality assurance

Despite legal provisions in place since 2005, Romanian universities are considered to perform internal quality assurance only at a formal level, on paper, and usually in anticipation of external evaluations demanded by the government or other official institutions. This paper posits five hypotheses to explain this situation. We analyze 187 interviews with people in universities in order to evaluate these hypotheses. Only two hypotheses are confirmed by the data, allowing us to construct a narrative of policy failure. First, there are top-down failures resulting from unclear and inconsistent legal provisions that focus on multilayered evaluation procedures. Second, there are bottom-up failures related to the lack of ownership over internal quality assurance systems by the actors in the universities. The existing procedures are often seen as control-tools of government, and understood as disconnected from the universities' own goals and problems. Consequently, people on the ground passively try to subvert these tools by carrying them out in a ritualistic manner—which is why quality assurance cannot become internalized

Three dimensional structure directs T-cell epitope dominance associated with allergy

<p>Abstract</p> <p>Background</p> <p>CD4+ T-cell epitope immunodominance is not adequately explained by peptide selectivity in class II major histocompatibility proteins, but it has been correlated with adjacent segments of conformational flexibility in several antigens.</p> <p>Methods</p> <p>The published T-cell responses to two venom allergens and two aeroallergens were used to construct profiles of epitope dominance, which were correlated with the distribution of conformational flexibility, as measured by crystallographic B factors, solvent-accessible surface, COREX residue stability, and sequence entropy.</p> <p>Results</p> <p>Epitopes associated with allergy tended to be excluded from and lie adjacent to flexible segments of the allergen.</p> <p>Conclusion</p> <p>During the initiation of allergy, the N- and/or C-terminal ends of proteolytic processing intermediates were preferentially loaded into antigen presenting proteins for the priming of CD4+ T cells.</p

Syntheses, structures and redox properties of tris(pyrazolyl)borate-capped ruthenium vinyl complexes.

Reaction of RuHCl(CO)(PPh3)3 with aryl alkynes HCCC6H4R-4 [1: R = N(C6H4Me-4)2 (a), OMe (b), Me (c), CO2Me (d), NO2 (e)] gives the five-coordinate vinyl complexes Ru(CHCHC6H4R-4)Cl(CO)(PPh3)2 (2a–e). Reaction of 2a with excess PMe3 gives crystallographically characterised Ru{CHCHC6H4N(C6H4Me-4)2-4}Cl(CO)(PMe3)3 (3a), whilst reaction of 2a–e with KTp affords Ru(CHCHC6H4R-4)(CO)(PPh3)Tp (4a–e) bearing the facially capping Tp− ligand. Electrochemical and spectroelectochemical properties of 4a–e are consistent with substantial redox activity associated with the vinyl ligand, and these properties have been satisfactorily modelled by DFT based calculations of electronic structure

Malarial Hemozoin Activates the NLRP3 Inflammasome through Lyn and Syk Kinases

The intraerythrocytic parasite Plasmodium—the causative agent of malaria—produces an inorganic crystal called hemozoin (Hz) during the heme detoxification process, which is released into the circulation during erythrocyte lysis. Hz is rapidly ingested by phagocytes and induces the production of several pro-inflammatory mediators such as interleukin-1β (IL-1β). However, the mechanism regulating Hz recognition and IL-1β maturation has not been identified. Here, we show that Hz induces IL-1β production. Using knockout mice, we showed that Hz-induced IL-1β and inflammation are dependent on NOD-like receptor containing pyrin domain 3 (NLRP3), ASC and caspase-1, but not NLRC4 (NLR containing CARD domain). Furthermore, the absence of NLRP3 or IL-1β augmented survival to malaria caused by P. chabaudi adami DS. Although much has been discovered regarding the NLRP3 inflammasome induction, the mechanism whereby this intracellular multimolecular complex is activated remains unclear. We further demonstrate, using pharmacological and genetic intervention, that the tyrosine kinases Syk and Lyn play a critical role in activation of this inflammasome. These findings not only identify one way by which the immune system is alerted to malarial infection but also are one of the first to suggest a role for tyrosine kinase signaling pathways in regulation of the NLRP3 inflammasome

Transnational corporations, violence and suffering: the environmental, public health and social impacts from comparative case studies in Zimbabwe and Uganda

The present effects of transnational corporations (TNCs) on social, health, and environmental aspects of local societies have a long history. The preconditions for the insertion of the types of economic initiatives now seen in the Global South, and driven by TNCs, were set through histories of colonialism and development schemes. These initiatives disrupted local economies and modified environments, delivering profound effects on livelihoods. These effects were experienced as structural violence, and have produced social suffering through the decades.In this paper, we compare two African cases across time; the conjunction of development initiatives and structural adjustment in the Zambezi Valley, Zimbabwe in the early 1990s and industrial plantation forestry in present-day Uganda. Each case presents a specific constellation of political and economic forces that has produced prejudicial effects on local populations in their time period of application and are, essentially, different versions of structural violence that produce social suffering. While each case depicts a specific type of violent encounter manifest at a particular historical moment, these are comparable in the domains of environmental impacts, disruptions to societies, co-opting of local economies, disordering of systems of meaning and social reproduction, and nefarious effects on well-being. We analyze the conjunction of these effects through a theoretical lens of structural violence and social suffering. Our analysis draws particular attention to the role of TNCs in driving this structural violence and its effects