A simple model for the early events of quorum sensing in Pseudomonas aeruginosa: modeling bacterial swarming as the movement of an "activation zone"

<p>Abstract</p> <p>Background</p> <p>Quorum sensing (QS) is a form of gene regulation based on cell-density that depends on inter-cellular communication. While there are a variety of models for bacterial colony morphology, there is little work linking QS genes to movement in an open system.</p> <p>Results</p> <p>The onset of swarming in environmental <it>P. aeruginosa </it>PUPa3 was described with a simplified computational model in which cells in random motion communicate via a diffusible signal (representing <it>N</it>-acyl homoserine lactones, AHL) as well as diffusible, secreted factors (enzymes, biosurfactans, i.e. "public goods") that regulate the intensity of movement and metabolism in a threshold-dependent manner. As a result, an "activation zone" emerges in which nutrients and other public goods are present in sufficient quantities, and swarming is the spontaneous displacement of this high cell-density zone towards nutrients and/or exogenous signals. The model correctly predicts the behaviour of genomic knockout mutants in which the QS genes responsible either for the synthesis (<it>lasI, rhlI</it>) or the sensing (<it>lasR, rhlR</it>) of AHL signals were inactivated. For wild type cells the model predicts sustained colony growth that can however be collapsed by the overconsumption of nutrients.</p> <p>Conclusion</p> <p>While in more complex models include self-orienting abilities that allow cells to follow concentration gradients of nutrients and chemotactic agents, in this model, displacement towards nutrients or environmental signals is an emergent property of the community that results from the action of a few, well-defined QS genes and their products. Still the model qualitatively describes the salient properties of QS bacteria, i.e. the density-dependent onset of swarming as well as the response to exogenous signals or cues.</p> <p>Reviewers</p> <p>This paper was reviewed by Gáspár Jékely, L. Aravind, Eugene V. Koonin and Artem Novozhilov (nominated by Eugene V. Koonin).</p

A construção do SUS e a participação do assistente social

O artigo analisa os desafios na construção e implementação do Sistema Único de Saúde (SUS), que se dá num contexto em que as políticas sociais são orientadas pelos ideais neoliberais, de caráter restritivo e de privatização, e a saúde é tratada segundo a lógica do mercado, ferindo os princípios e as diretrizes constitucionais. A participação do assistente social no processo de construção e desenvolvimento do SUS, busca fortalecer a perspectiva da universalização do acesso aos programas e políticas sociais. A profissão vem produzindo conhecimentos e alternativas para enfrentar as dificuldades vivenciadas no cotidiano, provocando o alargamento do trabalho na área da saúde pública.  Abstract: The article examines the challenges in the construction and implementation of the Single Health System (SUS), which occurs in a context in which social policies are guided by neoliberal ideals, and restrictive nature of privatization, and health is treated according to the logic the market, injuring the principles and constitutional guidelines. The involvement of a social worker in the process of construction and development of the SUS, seeks to strengthen the prospect of universal access to programs and social policies. The profession has been producing knowledge and alternatives to face the difficulties experienced in daily life, causing enlargement of work in the area of public health

Rituais do poder nas organizações de saúde

O poder é ambicionado pelo ser humano que o deseja ter para si; já que através dele se sente equiparado a uma divindade capaz de tudo dominar. Quando mais frágil se encontra estruturada a personalidade do sujeito, mais necessita de poder para camuflar sua impotência. As organizações sempre foram lugares de exercício de poder. Nas organizações clássicas o poder se confunde com o pai-trão ou com os chefes. Nas organizações hipermodernas o poder se despersonaliza, passando as relações passionais a serem vivenciadas através das estruturas e valores nelas cultivados. Nas organizações de saúde, o poder se concentra no médico, pelo consentimento implícito da sociedade, tornando rígida a construção da sua identidade profissional. Os rituais são desenvolvidos e adotados nas instituições como forma de perpetuar o poder instituído. Há uma identificação dos trabalhadores com a imagem projetada da organização, surgindo um campo fértil para se implantar ideologias e políticas que são culturalmente introjetadas como verdadeiras

UM PROJETO, DUAS CIDADES: ESTUDO COMPARATIVO COM PESSOAS IDOSAS DE FRANCA E AVEIRO

Aumentou o tempo vivido pelas pessoas no mundo todo, mas sem melhoriasna sociedade contemporânea, nem culturais, econômicas ou físicas. Vida saudável, atualmente se reduz à perseguição dos modismos consumistas cada vez mais acelerados, incentivados pelo sistema econômico capitalista neoliberal globalizado do mundo atual. O planejamento das novas condições societárias deve possibilitar a implantação de medidas para atingir a qualidade de vida da população em geral com menores custos pessoais e sociais. A idéia da manutenção da autonomia e independência vincula-se à constatação que a saúde da pessoa idosa é a interação entre saúde física, saúde mental, independência financeira, capacidade funcional e suporte social. Tendo como objetivo comparar a percepção das pessoas idosas de Franca, Brasil, e Aveiro, Portugal, o estudo versa sobre o envelhecimento saudável e a expectativa que nutrem sobre a continuidade de suas vidas. Conclui-se que as idéias a respeito do envelhecimento ativo que culminam no Projeto Cidade Amiga da Pessoa Idosa, são fontes inesgotáveis de reflexão, que convidam à ação. Implicam numa inversão de valores das forças vivas da sociedade diante dos novosparadigmas que se apresentam

Shortening of the Lactobacillus paracasei subsp. paracasei BGNJ1-64 AggLb Protein Switches Its Activity from Auto-aggregation to Biofilm Formation

AggLb is the largest (318.6 kDa) aggregation-promoting protein of Lactobacillus paracasei subsp. paracasei BGNJ1-64 responsible for forming large cell aggregates, which causes auto-aggregation, collagen binding and pathogen exclusion in vitro. It contains an N-terminus leader peptide, followed by six successive collagen binding domains, 20 successive repeats (CnaB-like domains) and an LPXTG sorting signal at the C-terminus for cell wall anchoring. Experimental information about the roles of the domains of AggLb is currently unknown. To define the domain that confers cell aggregation and the key domains for interactions of specific affinity between AggLb and components of the extracellular matrix (ECM), we constructed a series of variants of the aggLb gene and expressed them in Lactococcus lactis subsp. lactis BGKP1-20 using a lactococcal promoter. All of the variants contained a leader peptide, an inter collagen binding-CnaB domain region (used to raise an anti-AggLb antibody), an anchor domain and a different number of collagen binding and CnaB-like domains. The role of the collagen binding repeats of the N-terminus in auto-aggregation and binding to collagen and fibronectin was confirmed. Deletion of the collagen binding repeats II, III and IV resulted in a loss of the strong auto-aggregation, collagen and fibronectin binding abilities whereas the biofilm formation capability was increased. The strong auto-aggregation, collagen and fibronectin binding abilities of AggLb were negatively correlated to biofilm formation

Shortening of the Lactobacillus paracasei subsp paracasei BGNJ164 AggLb Protein Switches Its Activity from Auto-aggregation to Biofilm Formation

AggLb is the largest (318.6 kDa) aggregation-promoting protein of Lactobacillus paracasei subsp. paracasei BGNJ1-64 responsible for forming large cell aggregates, which causes auto-aggregation, collagen binding and pathogen exclusion in vitro. It contains an N-terminus leader peptide, followed by six successive collagen binding domains, 20 successive repeats (CnaB-like domains) and an LPXTG sorting signal at the C-terminus for cell wall anchoring. Experimental information about the roles of the domains of AggLb is currently unknown. To define the domain that confers cell aggregation and the key domains for interactions of specific affinity between AggLb and components of the extracellular matrix, we constructed a series of variants of the aggLb gene and expressed them in Lactococcus lactis subsp. lactis BGKP1-20 using a lactococcal promoter. All of the variants contained a leader peptide, an inter collagen binding-CnaB domain region (used to raise an anti-AggLb antibody), an anchor domain and a different number of collagen binding and CnaB-like domains. The role of the collagen binding repeats of the N-terminus in auto-aggregation and binding to collagen and fibronectin was confirmed. Deletion of the collagen binding repeats II, III, and IV resulted in a loss of the strong auto-aggregation, collagen and fibronectin binding abilities whereas the biofilm formation capability was increased. The strong auto-aggregation, collagen and fibronectin binding abilities of AggLb were negatively correlated to biofilm formation

AS POLÍTICAS PÚBLICAS DE SAÚDE NO BRASIL: O SISTEMA ÚNICO DE SAÚDE (SUS) E A REDE DE SAÚDE EM FRANCA

Este artigo nasceu de reflexões realizadas na Disciplina “Saúde e Relações de Trabalho”, do Programa de Pós-Graduação de Serviço Social da UNESP de Franca, ministrado pela Profª Drª Iris Fenner Bertani. As autoras procuram fazer uma breve análise da história das políticas sociais e como foi se configurando a saúde pública no Brasil, enfocando a atenção primária que favorece o acesso da população e a promoção da saúde. O artigo mostra o SUS como uma das políticas sociais mais avançadas, as dificuldades no enfrentamento das questões apresentadas em cumprir seus princípios e diretrizes e aborda ainda como está estruturada a rede de saúde pública no município de Franca/SP. PALAVRAS-CHAVE: Políticas Sociais; Saúde Pública; Atenção Primária; SUS

Negative Regulation of Violacein Biosynthesis in Chromobacterium violaceum

In Chromobacteium violaceum, the purple pigment violacein is under positive regulation by the N-acylhomoserine lactone CviI/R quorum sensing system and negative regulation by an uncharacterized putative repressor. In this study we report that the biosynthesis of violacein is negatively controlled by a novel repressor protein, VioS. The violacein operon is regulated negatively by VioS and positively by the CviI/R system in both C. violaceum and in a heterologous Escherichia coli genetic background. VioS does not regulate the CviI/R system and apart from violacein, VioS, and quorum sensing regulate other phenotypes antagonistically. Quorum sensing regulated phenotypes in C. violaceum are therefore further regulated providing an additional level of control

Bacterial Endophytes Contribute to Rice Seedling Establishment Under Submergence

Flooding events caused by severe rains and poor soil drainage can interfere with plant germination and seedling establishment. Rice is one of the cereal crops that has unique germination strategies under flooding. One of these strategies is based on the fast coleoptile elongation in order to reach the water surface and re-establish the contact with the air. Microorganisms can contribute to plant health via plant growth promoters and provide protection from abiotic stresses. To characterise the community composition of the microbiome in rice germination under submergence, a 16S rRNA gene profiling metagenomic analysis was performed of temperate japonica rice varieties Arborio and Lamone seedlings, which showed contrasting responses in terms of coleoptile length when submerged. This analysis showed a distinct microbiota composition of Arborio seeds under submergence, which are characterised by the development of a long coleoptile. To examine the potential function of microbial communities under submergence, culturable bacteria were isolated, identified and tested for plant growth-promoting activities. A subgroup of isolated bacteria showed the capacity to hydrolyse starch and produce indole-related compounds under hypoxia. Selected bacteria were inoculated in seeds to evaluate their effect on rice under submergence, showing a response that is dependent on the rice genotype. Our findings suggest that endophytic bacteria possess plant growth-promoting activities that can substantially contribute to rice seedling establishment under submergence

In Planta Colonization and Role of T6SS in Two Rice Kosakonia Endophytes.

Endophytes live inside plants and are often beneficial. Kosakonia is a novel bacterial genus that includes many diazotrophic plant-associated isolates. Plant–bacteria studies on two rice endophytic Kosakonia beneficial strains were performed, including comparative genomics, secretome profiling, in planta tests, and a field release trial. The strains are efficient rhizoplane and root endosphere colonizers and localized in the root cortex. Secretomics revealed 144 putative secreted proteins, including type VI secretory system (T6SS) proteins. A Kosakonia T6SS genomic knock-out mutant showed a significant decrease in rhizoplane and endosphere colonization ability. A field trial using rice seed inoculated with Kosakonia spp. showed no effect on plant growth promotion upon nitrogen stress and microbiome studies revealed that Kosakonia spp. were significantly more present in the inoculated rice. Comparative genomics indicated that several protein domains were enriched in plant-associated Kosakonia spp. This study highlights that Kosakonia is an important, recently classified genus involved in plant–bacteria interaction