185 research outputs found
Studies on CheA(B): Phosphorylation, methylation and behavioral control during chemotactic signal transduction in Bacillus subtilis
No full textChemotaxis in Bacillus subtilis is a prototypical behavior and signal transduction process, and CheA\sb{\rm B} plays an important role in it. The cheA\sb{\rm B} gene was isolated, sequenced, expressed and mutated. It encoded a large negatively charged protein with a molecular weight of approximately 74,000. The predicted protein sequence has 33% homology with the Escherichia coli and CheA\sb{\rm E}. Such proteins have been found to autophosphorylate and are members of the same histidine kinase signal modulating family. CheA\sb{\rm B} has several conserved regions (including the histidine that is phosphorylated in CheA\sb{\rm E}) that coincide with the other autophosphorylated signal transducers. In vitro experiments on partially purified CheA\sb{\rm B} indicates that it also appears to autophosphorylate. CheA\sb{\rm E} mediates the effect of binding of attractants or repellents at the MCPs (receptors) by altering its rate of autophosphorylation and subsequent phosphorylation of CheY, to bring about behavioral change, and CheB, to bring about adaptation. CheA\sb{\rm B} appears to play a similar central controlling role, for a null mutant and all point mutants tested were defective in attractant-induced methanol production and showed no behavioral response upon addition of chemoeffectors. Furthermore, methylation of the MCPs, in which methyl groups are transferred away to an acceptor and replaced by methyl groups from S-adenosylmethionine, is regulated by CheB\sb{\rm B}, whose activity is controlled by CheA\sb{\rm B}.Although the chemotactic mechanism in B. subtilis thus appears to involve phosphoryl transfer, it is significantly different from that in E. coli. First, the cheA\sb{\rm B} null mutant mostly tumbles, whereas cheA\sb{\rm E} mutants swim smoothly. Since the null mutant in cheY\sb{\rm B} also tumbles whereas that in cheY\sb{\rm E} swims smoothly, it is likely that CheY\sb{\rm B}-P causes smooth swimming, whereas CheY\sb{\rm E}-P is known to cause tumbling. Second, only in B. subtilis does excitation lead to methyl transfer and methanol formation, probably to help bring about adaptation, and CheA\sb{\rm B} controls this. It also is required for some, but not all, changes in methylation of MCPs following addition of the attractant aspartate. All of these experiments suggest a unique mechanism for chemotaxis in B. subtilis.Made available in DSpace on 2011-05-07T14:20:44Z (GMT). No. of bitstreams: 2
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Biochemistry and regulation of CheA in Bacillus subtilis chemotaxis
No full textBacterial chemotaxis is one of the most well understood signal transduction processes in biology. By controlling the direction of flagella rotation, this process allows the organism to sense changes in its surroundings and migrate toward more favorable environments. The process of chemotaxis is controlled by the activity of an autophosphorylating histidine kinase, CheA. The work described in this thesis shows that Bacillus subtilis CheA differs from other members of this family of bacterial histidine kinases in two respects: it is able to achieve its maximum phosphorylation potential at very low ATP concentrations, and the phosphorylated form of the enzyme is very stable in the presence of ADP and other potential phosphoryl group acceptors. We have long hypothesized that attractant-bound methyl-accepting chemotaxis proteins (MCPs) in B. subtilis increase the activity of CheA. Asparagine-bound McpB has been shown here to increase CheA activity in vitro, the first example of activation of a two-component signal transducing kinase by its proposed environmental ligand to date. Studies on the enteric chemotaxis system revealed that taxis toward certain sugars is mediated solely through a separate phosphoenolpyruvate-dependent phosphotransferase system (PTS), involved in sugar transport. In B. subtilis, we have determined that taxis toward PTS carbohydrates is mediated both by MCPs and the PTS. Finally, a restriction map of the distal end of the 26kb fla/che operon has been deduced, which will be of value in attempts to clone additional chemotaxis genes in B. subtilis.Made available in DSpace on 2011-05-07T12:51:56Z (GMT). No. of bitstreams: 2
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Genome sequence of Rhodobacter sphaeroides strain WS8N
No full textCopyright © 2011, American Society for MicrobiologyRhodobacter sphaeroides is a metabolically diverse photosynthetic alphaproteobacterium found ubiquitously in soil and freshwater habitats. Here we present the annotated genome sequence of R. sphaeroides WS8N.This research was funded by the UK Biotechnology and Biological Sciences Research Council
Improving access to health care amongst vulnerable populations: a qualitative study of village malaria workers in Kampot, Cambodia.
No full textBACKGROUND: There is growing interest in the expansion of community health workers programmes in low- and middle-income countries as a cost-effective approach to address shortages of health professionals. However, our understanding of the reception of large-scale programmes and how to improve them remains limited, with knowledge gaps about factors that may promote or discourage equitable access to services. This paper examines the case of the Village Malaria Workers (VMW) programme in Cambodia, an extensive community-based intervention for the management of malaria cases in remote rural areas. METHOD: Fieldwork was conducted in Kampot province, in six case villages characterised by different programme configuration, population size, and distance to the nearest public health facility. In these locations, in-depth interviews (n = 71) with VMWs, village authorities, and residents were conducted to identify facilitators and challenges to service utilisation. Data analysis was informed by a conceptual framework based on five domains of access to services: awareness, accessibility, accommodation, availability, and acceptability. RESULTS: Factors that influenced the utilisation of VMW services in our research sites include: the nature of dissemination activities and their ability to reach different population groups; the village topography and the changing road infrastructure; the involvement of VMWs in other community roles and activities; perceptions about the type of disease after the onset of symptoms; the need for comprehensive diagnosis and care; perceptions about the status of VMWs as medical providers; length of VMW appointment. CONCLUSIONS: This study highlights the complexity and diversity of contextual factors that may influence the uptake of a community health programme. As in other countries, continued use of lay health workers in Cambodia to deliver diagnostic and curative services has the potential for great health and economic impact. However, further consideration should be given to the problem of access in different categories of residents and different contexts of implementation. In addition, a comprehensive mapping of changes in disease epidemiology, road infrastructure and the geography of access to services is crucial to inform policy development in this area
Focused Screening and Treatment (FSAT): a PCR-based strategy to detect malaria parasite carriers and contain drug resistant P. falciparum, Pailin, Cambodia.
No full textRecent studies have shown that Plasmodium falciparum malaria parasites in Pailin province, along the border between Thailand and Cambodia, have become resistant to artemisinin derivatives. To better define the epidemiology of P. falciparum populations and to assess the risk of the possible spread of these parasites outside Pailin, a new epidemiological tool named "Focused Screening and Treatment" (FSAT), based on active molecular detection of asymptomatic parasite carriers was introduced in 2010. Cross-sectional malariometric surveys using PCR were carried out in 20 out of 109 villages in Pailin province. Individuals detected as P. falciparum carriers were treated with atovaquone-proguanil combination plus a single dose of primaquine if the patient was non-G6PD deficient. Interviews were conducted to elicit history of cross-border travel that might contribute to the spread of artemisinin-resistant parasites. After directly observed treatment, patients were followed up and re-examined on day 7 and day 28. Among 6931 individuals screened, prevalence of P. falciparum carriers was less than 1%, of whom 96% were asymptomatic. Only 1.6% of the individuals had a travel history or plans to go outside Cambodia, with none of those tested being positive for P. falciparum. Retrospective analysis, using 2010 routine surveillance data, showed significant differences in the prevalence of asymptomatic carriers discovered by FSAT between villages classified as "high risk" and "low risk" based on malaria incidence data. All positive individuals treated and followed-up until day 28 were cured. No mutant-type allele related to atovaquone resistance was found. FSAT is a potentially useful tool to detect, treat and track clusters of asymptomatic carriers of P. falciparum along with providing valuable epidemiological information regarding cross-border movements of potential malaria parasite carriers and parasite gene flow
Optimising Strategies for Malaria Elimination: Primaquine, Mass Drug Administration and Artemisinin Resistance
No full textResilience and Vulnerability Assessment as the Basis for Adaptation Dialogue in Information-Poor Environments: A Cambodian Example
No full textIntegrating child health services into malaria control services of village malaria workers in remote Cambodia: service utilization and knowledge of malaria management of caregivers
No full textPerspectivas interdisciplinarias: contribuciones significativas desde el campo editorial, la ilustración y el emprendimiento al medio cultural
No full textA lo largo de su trayectoria como diseñadora gráfica profesional, la
autora del presente informe incursiona en diversos sectores del mercado
laboral, destacándose especialmente en el diseño editorial y el branding. El
objetivo principal de este informe es recapitular y respaldar su desempeño
profesional alineado con sus motivaciones personales. En el presente
documento se detallan, de manera concisa, tres proyectos seleccionados que
abarcan los últimos siete años de su carrera. En primer lugar, se analiza el rol
desempeñado en el diseño editorial para más de veinte publicaciones bajo el
sello editorial del Fondo de Cultura Económica (Perú), utilizando cuatro como
ejemplos, y se destaca cómo esta experiencia ha constituido una plataforma
de aprendizaje para proyectos futuros. Seguidamente, se explor en detalle su
contribución al diseño de marca, planificación, conceptualización y gestión de
contenido para el perfil de Instagram de Vuelo Ámbar Print Studio, espacio
especializado en grabado y letterpress y cofundado por la autora, Giselle
Adrianzén, junto con Diego Cabanillas, (grabador de la PUCP), resaltando
también su labor como directora artística para diversos proyectos. Por último,
se examina su aporte como ilustradora editorial para la reedición del libro
"Autobiografía de un Yogui" de Paramahansa Yogananda, destacando cómo
sus ilustraciones enriquecen la interpretación reflexiva del lector, según la
editora del proyecto, Cindy Torrejón. Cada proyecto está respaldado con
material gráfico que ilustra los resultados del diseño, detallando la
metodología empleada para fundamentar sus aspectos estéticos,
comunicacionales, técnicos y funcionales.Throughout her career as a professional graphic designer, the author of
this report has ventured into various sectors of the job market, particularly
excelling in editorial design and branding. The main objective of this report is
to recapitulate and support her professional performance aligned with her
personal motivations. This document will detail, concisely, three selected
projects spanning the last seven years of her career. Firstly, the role played in
editorial design for over twenty publications under the editorial imprint of Fondo
de Cultura Económica (Peru) will be analyzed, utilizing four as examples, and
emphasizing how this experience has served as a learning platform for future
projects. Subsequently, her contribution to brand design, planning,
conceptualization, and content management for the Instagram profile of Vuelo
Ámbar Print Studio, an studio specialized in engraving and letterpress cofounded by the author, Giselle Adrianzén, alongside Diego Cabanillas
(engraver from PUCP), will be explored in detail, also highlighting her role as
artistic director for various projects. Finally, her contribution as an editorial
illustrator for the reissue of "Autobiography of a Yogi" by Paramahansa
Yogananda will be examined, emphasizing how her illustrations enriched the
reflective interpretation of the reader, according to the project's editor, Cindy
Torrejón. Each project is supported by graphical material illustrating the design
results, detailing the methodology used to support its aesthetic,
communicational, technical, and functional aspects
Perspectivas interdisciplinarias: contribuciones significativas desde el campo editorial, la ilustración y el emprendimiento al medio cultural
No full textA lo largo de su trayectoria como diseñadora gráfica profesional, la
autora del presente informe incursiona en diversos sectores del mercado
laboral, destacándose especialmente en el diseño editorial y el branding. El
objetivo principal de este informe es recapitular y respaldar su desempeño
profesional alineado con sus motivaciones personales. En el presente
documento se detallan, de manera concisa, tres proyectos seleccionados que
abarcan los últimos siete años de su carrera. En primer lugar, se analiza el rol
desempeñado en el diseño editorial para más de veinte publicaciones bajo el
sello editorial del Fondo de Cultura Económica (Perú), utilizando cuatro como
ejemplos, y se destaca cómo esta experiencia ha constituido una plataforma
de aprendizaje para proyectos futuros. Seguidamente, se explor en detalle su
contribución al diseño de marca, planificación, conceptualización y gestión de
contenido para el perfil de Instagram de Vuelo Ámbar Print Studio, espacio
especializado en grabado y letterpress y cofundado por la autora, Giselle
Adrianzén, junto con Diego Cabanillas, (grabador de la PUCP), resaltando
también su labor como directora artística para diversos proyectos. Por último,
se examina su aporte como ilustradora editorial para la reedición del libro
"Autobiografía de un Yogui" de Paramahansa Yogananda, destacando cómo
sus ilustraciones enriquecen la interpretación reflexiva del lector, según la
editora del proyecto, Cindy Torrejón. Cada proyecto está respaldado con
material gráfico que ilustra los resultados del diseño, detallando la
metodología empleada para fundamentar sus aspectos estéticos,
comunicacionales, técnicos y funcionales.Throughout her career as a professional graphic designer, the author of
this report has ventured into various sectors of the job market, particularly
excelling in editorial design and branding. The main objective of this report is
to recapitulate and support her professional performance aligned with her
personal motivations. This document will detail, concisely, three selected
projects spanning the last seven years of her career. Firstly, the role played in
editorial design for over twenty publications under the editorial imprint of Fondo
de Cultura Económica (Peru) will be analyzed, utilizing four as examples, and
emphasizing how this experience has served as a learning platform for future
projects. Subsequently, her contribution to brand design, planning,
conceptualization, and content management for the Instagram profile of Vuelo
Ámbar Print Studio, an studio specialized in engraving and letterpress cofounded by the author, Giselle Adrianzén, alongside Diego Cabanillas
(engraver from PUCP), will be explored in detail, also highlighting her role as
artistic director for various projects. Finally, her contribution as an editorial
illustrator for the reissue of "Autobiography of a Yogi" by Paramahansa
Yogananda will be examined, emphasizing how her illustrations enriched the
reflective interpretation of the reader, according to the project's editor, Cindy
Torrejón. Each project is supported by graphical material illustrating the design
results, detailing the methodology used to support its aesthetic,
communicational, technical, and functional aspects
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