Bacillus subtilis natto: a non-toxic source of poly-γ-glutamic acid that could be used as a cryoprotectant for probiotic bacteria

It is common practice to freeze dry probiotic bacteria to improve their shelf life. However, the freeze drying process itself can be detrimental to their viability. The viability of probiotics could be maintained if they are administered within a microbially produced biodegradable polymer - poly-γ-glutamic acid (γ-PGA) - matrix. Although the antifreeze activity of γ-PGA is well known, it has not been used for maintaining the viability of probiotic bacteria during freeze drying. The aim of this study was to test the effect of γ-PGA (produced by B. subtilis natto ATCC 15245) on the viability of probiotic bacteria during freeze drying and to test the toxigenic potential of B. subtilis natto. 10% γ-PGA was found to protect Lactobacillus paracasei significantly better than 10% sucrose, whereas it showed comparable cryoprotectant activity to sucrose when it was used to protect Bifidobacterium breve and Bifidobacterium longum. Although γ-PGA is known to be non-toxic, it is crucial to ascertain the toxigenic potential of its source, B. subtilis natto. Presence of six genes that are known to encode for toxins were investigated: three component hemolysin (hbl D/A), three component non-haemolytic enterotoxin (nheB), B. cereus enterotoxin T (bceT), enterotoxin FM (entFM), sphingomyelinase (sph) and phosphatidylcholine-specific phospholipase (piplc). From our investigations, none of these six genes were present in B. subtilis natto. Moreover, haemolytic and lecithinase activities were found to be absent. Our work contributes a biodegradable polymer from a non-toxic source for the cryoprotection of probiotic bacteria, thus improving their survival during the manufacturing process.

Does convective aggregation need to be represented in cumulus parameterizations?

Tropical deep convection exhibits a variety of levels of aggregation over a wide range of scales. Based on a multisatellite analysis, the present study shows at mesoscale that different levels of aggregation are statistically associated with differing large-scale atmospheric states, despite similar convective intensity and large-scale forcings. The more aggregated the convection, the dryer and less cloudy the atmosphere, the stronger the outgoing longwave radiation, and the lower the planetary albedo. This suggests that mesoscale convective aggregation has the potential to affect couplings between moisture and convection and between convection, radiation, and large-scale ascent. In so doing, aggregation may play a role in phenomena such as “hot spots” or the Madden-Julian Oscillation. These findings support the need for the representation of mesoscale organization in cumulus parameterizations; most parameterizations used in current climate models lack any such representation. The ability of a cloud system-resolving model to reproduce observed relationships suggests that such models may be useful to guide attempts at parameterizations of convective aggregation.

Em busca da autonomia operacional do Banco Central do Brasil como instrumento de estabilização da moeda

Os Bancos Centrais têm, como função principal, zelar pela moeda, de modo a assegurar a estabilidade financeira de seus países. A partir de tal premissa, buscaremos demonstrar que o Banco Central do Brasil necessita de autonomia operacional, a ser regulamentada em lei, a fim de cumprir com sua missão, que é de natureza essencialmente técnica. Em que pese o fato de questão de se implementar, no Brasil, um Banco Central dotado de autonomia não ser consensual, buscaremos demonstrar as vantagens deste modelo, como fator de obtenção de estabilidade monetária. No Brasil, o Banco Central (BACEN), além de arcar com uma enorme gama de atribuições, encontra-se sujeito a pressões governamentais, em face de projetos de curto prazo, não necessariamente compatíveis com a tarefa de estabilização monetária, que pode requerer uma atuação de longo prazo. A autonomia desejada para o BACEN não significa que ele venha a se tomar independente, pelo contrário, uma vez que ele terá que assumir a responsabilidade de atingir metas pré-determinadas pelo Governo, obrigando-se a prestar contas de sua atuação à sociedade, de modo transparente. Para tanto, é preciso que ele seja dotado de autonomia administrativa, orçamentária e operacional, dentro de limites estabelecidos por lei. Ao destacarmos a autonomia do BACEN, trazemos a tona um fator pertinente à questão que é inflação. Trata-se de um processo que corrói a economia, e, quando se toma crônica, 111 como vinha ocorrendo no Brasil até os anos 90, leva à instabilidade e dificulta um planejamento de longo prazo. A necessidade de se controlar a inflação, em muitos países, levou-os a adotar uma política monetária com metas inflacionárias - Inflatíon Targeting. Os países que adotaram o regime de metas inflacionárias conferiram autonomia aos seus Bancos Centrais, pois tanto mais autonomia, tanto mais credibilidade. Desta forma, países como o Chile, a Nova Zelândia, a Alemanha e os demais países que compõem a União Europeia lograram controlar a inflação. Para que o BACEN cumpra com o que lhe compete, exercendo eficientemente o seu papel, é curial, portanto, que seja dotado de autonomia orçamentária, administrativa e operacional, devendo ser regulamentado o art. 192 da Constituição Federal, através de Lei Complementar. Uma vez assegurada legalmente a autonomia de que o Banco Central do Brasil necessita, ter-se-á um meio valioso de controle da inflação, assegurando a estabilidade da moeda e permitindo que o desenvolvimento seja implementado no prazo adequado, permitindo um planejamento estratégico de longo prazo para o país.

Escolas diferenciadas praticam um ensino de ciências diferenciado para melhor!?: o que dizem os estudantes sobre o ensino de ciências de uma escola de aplicação

O presente estudo é relativo às práticas docentes no ensino de ciências em uma Escola de Aplicação tida como escola diferenciada positivamente em termos da qualidade de suas práticas de ensino, das condições de trabalho de seus professores e pelo suposto interesse de atualização permanente para assegurar aprendizagem significativa aos estudantes e prepará-los para exercer a cidadania. Meu objetivo foi identificar parâmetros de diferenciação qualitativa do ensino na área de Ciências, considerando justamente que a experimentação pedagógica foi uma das vertentes que dirigiu a criação de ‘escolas de aplicação’ no País. Esta investigação se desenvolve em uma modalidade de pesquisa narrativa por meio da qual se objetiva evidenciar, a partir do relato dos estudantes sobre suas experiências no ensino de ciências, como se configuram as práticas de ensino, especialmente em termos de: a) seleção de conteúdos, b) abordagens teórico-metodológicas do ensino, c) interação professor aluno e aluno-aluno em classe e fora desta, bem como d) práticas, critérios e procedimentos de avaliação do ensino e da aprendizagem. Procurei investigar como os alunos percebem e que valores atribuem às práticas de ensino de Ciências, configuradas especialmente como “boas aulas de ciências”. Tendo como foco os relatos dos estudantes de 5ª a 8ª séries da escola pesquisada, sobre as práticas de ensino de ciências que vivenciam, assumo como premissa, que estes possuem idéias, percepções e concepções acerca do processo de ensino e de aprendizagem. As análises por mim procedidas apontam para uma prática de ensino reprodutiva e memorativa, pouco diferente das práticas tradicionais usuais das escolas comuns. No tocante à natureza das aulas e à temática dessas aulas, pouco se valoriza os conhecimentos prévios dos estudantes, predominando um tipo de aula em que os alunos passivamente se limitam a observar o trabalho docente, reproduzem ou repetem quando solicitados aspectos de conteúdos/conhecimento informativo de temas e assuntos das ciências fechados no programa a cumprir e descontextualizados, sem qualquer relação com a realidade, com o mundo em que os estudantes vivem. A guisa de conclusão, considero que as possibilidades e os limites desse ensino obsoleto e ultrapassado de Ciências evidenciados pelos estudantes põem em questão o ensino atual da área e colocam desafios para esta escola de aplicação e para seus professores, em função principalmente das condições privilegiadas de uma escola de aplicação. Torna-se imprescindível que se retome tais práticas de ensino para atualizá-las ao se buscar refletir coletivamente sobre os conteúdos que podem ser significativos para os estudantes, sua relação com o mundo de hoje, bem como sobre as metodologias para tratamento dos conteúdos das Ciências na perspectiva da efetiva construção da aprendizagem significativa dos estudantes, preparando-os de fato para a cidadania.

Description of a rat palatal acrylic plate that can be relined

Purpose: The objective of this article is to describe a method to construct an intraoralacrylic device that permits a reline material to be added to the inner surface of thepalatal plate.Materials and Methods: Fifteen 60-day-old adult female rats (Rattus NorvegicusAlbinus Wistar), weighing 150 to 250 g were used for this study and allocated to threegroups (n = 5): G1, animals wearing a heat-polymerized acrylic resin palatal plate(Lucitone 550) for 14 days; G2, animals wearing a heat-polymerized acrylic resinpalatal plate (Lucitone 550) relined with Tokuyama Rebase II for 14 days; and G3,animals maintained under the same conditions as the experimental groups, withoutwearing palatal plates for 14 days. The manipulation of the animals followed theguidelines of the Brazilian College of Animal Experimentation, under the approval ofthe animal ethics committee of the State University of Ponta Grossa. The palatal platescovered the whole palate, were fixed in the molar region with light-cured resin, andwere kept there for 14 days. The animals received a paste diet and water ad libitum.Before and after the trial period, the rats were weighed individually on a precisionscale. Statistical analysis was performed using a two-way analysis of variance (α =0.05) test for comparison of the animals’ weight (g) at time 0 and after 14 days ofusing the palatal plate.Results: No statistical differences were observed regarding the weight of the animalsamong the experimental groups in the study.Conclusions: The individual master impressions, the molar teeth coverage, and themethod of cementation with nonadhesive composite resin provided good stability forthe palatal plate showed in this study, not disturbing the eating habits and nutritionof the animals. This model seems reproducible, offering adequate histopathologicalevaluation. Differences in tissue morphology exist between the animals that used thepalatal plate and the animals that did not use this device. Use of these palatal platescould clarify how prostheses bring changes in the palatal mucosa of users.

Caracterização funcional e estrutural das proteínas RUV-1 e RUV-2 do fungo Neurospora crassa

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Using landscape metrics to analyze micro-scale soil erosion processes

Methods of recording soil erosion using photographs exist but they are not commonly considered in scientific studies. Digital images may hold an expressive amount of information that can be extracted quickly in different manners. The investigation of several metrics that were initially developed for landscape ecology analysis constitutes one method. In this study we applied a method of landscape metrics to quantify the spatial configuration of surface micro-topography and erosion-related features, in order to generate a possible complementary tool for environmental management. In a 3.7 m wide and 9.7 m long soil box used during a rainfall simulation study, digital images were systematically acquired in four instances: (a) when the soil was dry; (b) after a short duration rain for initial wetting; (c) after the first erosive rain; and (d) after the 2nd erosive rain. Thirteen locations were established in the box and digital photos were taken at these locations with the camera positioned at the same orthogonal distance from the soil surface under the same ambient light intensity. Digital photos were converted into bimodal images and seven landscape metrics were analyzed: percentage of land, number of patches, density of patches, largest patch index, edge density, shape index, and fractal dimension. Digital images were an appropriate tool because they can generate data very quickly. The landscape metrics were sensitive to changes in soil surface micro-morphology especially after the 1st erosive rain event, indicating significant erosional feature development between the initial wetting and first erosive rainfall. The method is considered suitable for spatial patterns of soil micro-topography evolution from rainfall events that bear similarity to landscape scale pattern evolution from eco-hydrological processes. Although much more study is needed for calibrating the landscape metrics at the micro-scale, this study is a step forward in demonstrating the advantages of the method.

Dietary strategies to minimize the detrimental impact of weaning on gut morphology, physiology and microbiota of piglets

Weaning is a crucial period in the management of piglets. In modern piggeries economic interest make weaning age decrease more and more and the detrimental consequences of weaning have as much importance as earlier the weaning occurs. The risk of development of post-weaning diarrhea (PWD) in piglets is high and PWD is the cause of serious economic losses in pig herds. In the past the supplementation of the feed given after weaning with growth promoters antibiotics, in order to keep PWD under control, used to be a common practice, but their usage has been banned in EU since 2006. This measure led to the investigation of alternative suitable feed supplements that would be reasonably efficient in protecting and sustaining animal health and performance. Aim of this thesis was to evaluate the effect of some different alternatives to growth-promoters antibiotics on weaning piglets and to assess if some of them could be considered as valuables options to replace auxinic in animal feeding. The study is composed by four experimental trials. The first one aims to identify mechanisms involved in the auxinic effects of antibiotics in the diets; the following three evaluate the addition butyric acid, tryptophan, and nitrate as alternative to in-feed antimicrobials. Although some results are controversial, it appears from the data presented that the alternatives to in-feed antibiotics considered may exert positive effects on some zootechnical and health parameters on piglet in the post-weaning period. Anyway, the mechanism of action and the interaction with microbiota of such additives should be investigated inside out because many effects remains poorly understood.

Modeling and simulation of a synthetic genetic circuit that implements a multicelled behavior in a growing microcolony of E. coli

Synthetic Biology is a relatively new discipline, born at the beginning of the New Millennium, that brings the typical engineering approach (abstraction, modularity and standardization) to biotechnology. These principles aim to tame the extreme complexity of the various components and aid the construction of artificial biological systems with specific functions, usually by means of synthetic genetic circuits implemented in bacteria or simple eukaryotes like yeast. The cell becomes a programmable machine and its low-level programming language is made of strings of DNA. This work was performed in collaboration with researchers of the Department of Electrical Engineering of the University of Washington in Seattle and also with a student of the Corso di Laurea Magistrale in Ingegneria Biomedica at the University of Bologna: Marilisa Cortesi. During the collaboration I contributed to a Synthetic Biology project already started in the Klavins Laboratory. In particular, I modeled and subsequently simulated a synthetic genetic circuit that was ideated for the implementation of a multicelled behavior in a growing bacterial microcolony. In the first chapter the foundations of molecular biology are introduced: structure of the nucleic acids, transcription, translation and methods to regulate gene expression. An introduction to Synthetic Biology completes the section. In the second chapter is described the synthetic genetic circuit that was conceived to make spontaneously emerge, from an isogenic microcolony of bacteria, two different groups of cells, termed leaders and followers. The circuit exploits the intrinsic stochasticity of gene expression and intercellular communication via small molecules to break the symmetry in the phenotype of the microcolony. The four modules of the circuit (coin flipper, sender, receiver and follower) and their interactions are then illustrated. In the third chapter is derived the mathematical representation of the various components of the circuit and the several simplifying assumptions are made explicit. Transcription and translation are modeled as a single step and gene expression is function of the intracellular concentration of the various transcription factors that act on the different promoters of the circuit. A list of the various parameters and a justification for their value closes the chapter. In the fourth chapter are described the main characteristics of the gro simulation environment, developed by the Self Organizing Systems Laboratory of the University of Washington. Then, a sensitivity analysis performed to pinpoint the desirable characteristics of the various genetic components is detailed. The sensitivity analysis makes use of a cost function that is based on the fraction of cells in each one of the different possible states at the end of the simulation and the wanted outcome. Thanks to a particular kind of scatter plot, the parameters are ranked. Starting from an initial condition in which all the parameters assume their nominal value, the ranking suggest which parameter to tune in order to reach the goal. Obtaining a microcolony in which almost all the cells are in the follower state and only a few in the leader state seems to be the most difficult task. A small number of leader cells struggle to produce enough signal to turn the rest of the microcolony in the follower state. It is possible to obtain a microcolony in which the majority of cells are followers by increasing as much as possible the production of signal. Reaching the goal of a microcolony that is split in half between leaders and followers is comparatively easy. The best strategy seems to be increasing slightly the production of the enzyme. To end up with a majority of leaders, instead, it is advisable to increase the basal expression of the coin flipper module. At the end of the chapter, a possible future application of the leader election circuit, the spontaneous formation of spatial patterns in a microcolony, is modeled with the finite state machine formalism. The gro simulations provide insights into the genetic components that are needed to implement the behavior. In particular, since both the examples of pattern formation rely on a local version of Leader Election, a short-range communication system is essential. Moreover, new synthetic components that allow to reliably downregulate the growth rate in specific cells without side effects need to be developed. In the appendix are listed the gro code utilized to simulate the model of the circuit, a script in the Python programming language that was used to split the simulations on a Linux cluster and the Matlab code developed to analyze the data.