Extracytoplasmic function (ECF) sigma factor ^F is involved in Caulobacter crescentus response to heavy metal stress

Background: The -proteobacterium Caulobacter crescentus inhabits low-nutrient environments and can tolerate certain levels of heavy metals in these sites. It has been reported that C. crescentus responds to exposure to various heavy metals by altering the expression of a large number of genes.Results: In this work, we show that the ECF sigma factor F is one of the regulatory proteins involved in the control of the transcriptional response to chromium and cadmium. Microarray experiments indicate that F controls eight genes during chromium stress, most of which were previously described as induced by heavy metals. Surprisingly, F itself is not strongly auto-regulated under metal stress conditions. Interestingly, F-dependent genes are not induced in the presence of agents that generate reactive oxygen species. Promoter analyses revealed that a conserved F-dependent sequence is located upstream of all genes of the F regulon. In addition, we show that the second gene in the sigF operon acts as a negative regulator of F function, and the encoded protein has been named NrsF (Negative regulator of sigma F). Substitution of two conserved cysteine residues (C131 and C181) in NrsF affects its ability to maintain the expression of F-dependent genes at basal levels. Furthermore, we show that F is released into the cytoplasm during chromium stress and in cells carrying point mutations in both conserved cysteines of the protein NrsF.Conclusion: A possible mechanism for induction of the F-dependent genes by chromium and cadmium is the inactivation of the putative anti-sigma factor NrsF, leading to the release of F to bind RNA polymerase core and drive transcription of its regulon.</p

Pyrolyzed chitosan-based materials for CO2/CH4 separation

Chitosan is a biopolymer obtained by deacetylation of chitin extracted from sub-products of the food industry and it is rich in nitrogen content. Pyrolyzed chitosan– and chitosan-periodic mesoporous organosilica (PMO)– based porous materials with different pore structures and chemical features are prepared using different dry methods and ensuing pyrolysis at 800 °C, for application in the CO2/CH4 adsorption/separation. The highest CO2 adsorption capacity (1.37 mol·kg−1 at 100 kPa; 1.9 mol·kg−1 at 500 kPa) and the best selectivity for CO2/CH4 separation (95 at 500 kPa) is obtained using 1.5% (m/v) of chitosan solution dried under supercritical CO2. This material combines a good CO2 adsorption capacity with one of the highest selectivities for CO2/CH4 separation of the literature, arising as a promising alternative adsorbent for natural gas or biogas upgrading at reduced cost. The presence of high nitrogen content together with pores of diameter around 2 nm leads to an increase of the CO2 adsorption capacity. In the case of chitosan-PMO-based materials, the activation step using both acid and crushing methods is crucial to increase the CO2 adsorbed amount. Here, the highest CO2 adsorption capacity and the highest selectivity are obtained by the chitosan-PMO crushed adsorbent and the chitosan-PMO material activated with sulfuric acid, respectively. These observations indicate the importance of the controlled attack of the material surface to enhance the diffusion of the target gases within the adsorbent, avoiding the adsorption of other species.publishe

Systematisation of seismic mitigation planning at urban scale

This chapter explores the relation between the seismic mitigation planning that was developed to contribute to minimise effects at urban scale, which arise within the seismic impact. In this sense, it deepens the notion that interdependence, solidarity and cohesion of the different morphological constituents promote a better prepared built fabric, when facing catastrophic phenomena of seismic origin. Preventive approaches and reactive measures arising from the testimony of earthquake-resistant culture in Portugal are also mentioned. From the recognition of the importance of local know-how, infers a set of logical that evidence conditions to transcend the respective vernacular context, making it possible to generically systematize them.Portuguese Science and Technology Foundation (FCT) to the research project ‘SEISMIC-V – Vernacular Seismic Culture in Portugal’ (PTDC/ATPAQI/ 3934/2012

Morphological changes in Bombyx Mori silk gland and gut, in association with the feeding of iron oxide nanoparticles

The Bombyx mori silkworm is very important econom- ically and is a model for several studies. The larval life of silkworms is divided into five instars. The 5th instar is the longest, where the larvae show maximum food consumption and growth. The silk is produced in a paired gland composed of glandular epithelium and a lumen. Food digestion occurs in the midgut, represented by a folded columnar monolayered epithelium, which includes goblet cells and stem cells in a basal lamina. We aimed to investigate the influence of concentrations of iron oxide nanoparticles (IONPs) in food on the silk gland and midgut morphology

Perfil sensorial de queijos mussarela de búfala comercializados em Belém, Pará.

V.1, p.1-3

Perfil sensorial de queijos mussarela de búfala comercializados em Belém, Pará.

Derivados de leite de búfala têm sido foco de pesquisas no mundo inteiro e, no Brasil, sua produção e consumo estão em expansão. Entretanto, a inexistência de legislação específica para esse produto dificulta a padronização de sua produção e de derivados, a exemplo de queijos mussarela, prato, minas frescal e padrão. Dessa forma, objetivou-se, através da análise sensorial, avaliar as características sensoriais, aparência, textura e sabor, de duas marcas de mussarela de búfala disponíveis no mercado de Belém, Pará. Os derivados A e B receberam notas entre 6 "gostei ligeiramente" e 8 "gostei muito". Foram observadas diferenças significativas para aparência: 7,8 e 6,9; textura: 7,9 e 6,0, e aceitação semelhante no sabor, 7,3 e 7,0, respectivamente, nos derivados A e B. Quanto à intenção de compra, na mesma ordem, 5% e 25% não comprariam o produto, 30% e 40% talvez comprassem e 65% e 35% com certeza comprariam, o que indica a preferência dos provadores, pelas características organolépticas do derivado A. Na análise microbiológica constatou-se que, os queijos A e B atendem à legislação quanto ao limite de coliformes totais, ausência de Staphylococcus aureus e Salmonella ssp., portanto, indica boa expectativa de mercado e agrada ao consumidor

Nutrição e manejo alimentar na piscicultura.

Alimentação e nutrição de peixes. Práticas de alimentação.bitstream/item/46457/1/Doc-23.pdfTambém em edição especial, que compõe o acervo do projeto Minibibliotecas da Embrapa

Seleção de materiais para a construção de tanques-rede.

Estrutura dos tanques-rede flutuantes. Realidade amazônica. Testes com material natural disponível na região. Testes com tela de alambrado revestido de PVC. Difusão de tecnologia e adoção por pequenos produtores rurais.bitstream/CPAA-2009-09/10245/1/Com-Tec-14.pd

Critérios para seleção de local para piscicultura em tanques-rede na Amazônia.

Critérios ambientais para a espécie a ser criada. Critérios ambientais para a instalação do tanque-rede. Estabelecimento da criação e rentabilidade.bitstream/item/46456/1/Doc-22.pd