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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
231

Vacinas de administração oral contra diarréia associada à Escherichia coli enteropatogênica baseada em linhagens geneticamente modificadas de Bacillus subtilis / Oral vaccines against diarrhea associated with enteropathogenic Escherichia coli strains based on genetically modified Bacillus subtilis strains

Luiz, Wilson Barros 07 May 2010 (has links)
O objetivo deste trabalho foi a construção de linhagens geneticamente modificadas de B. subtilis capazes de expressar porções de intimina, principal componente envolvido na capacidade de colonização de linhagens enteropatogênicas de Escherichia coli (EPEC), como estratégia vacinal de administração oral contra diarréias infecciosas. As vacinas desenvolvidas empregaram cinco regiões da intimina de EPEC e linhagens de B. subtilis capazes de expressar e acumular proteínas recombinantes no citoplasma. Além disso, avaliamos o uso de esporos e células vegetativas como veículos vacinais para a entrega de antígenos recombinantes a partir de sistema de expressão epissomal. A eficácia do modelo vacinal foi demonstrada pela: (i) produção de anticorpos sistêmicos (IgG) e secretados (sIgA) contra intimina, (ii) capacidade de neutralização das intiminas expressas por diferentes linhagens de EPEC pelos anticorpos específicos gerados nos animais imunizados; e (iii) proteção a desafio com linhagens de EPEC a partir de modelo experimental que emprega camundongos recém-nascidos. Os resultados representam uma etapa importante na validação de uma nova estratégia vacinal para o controle de patógenos entéricos. Além disto, propomos a utilização de um modelo animal como uma nova ferramenta para se avaliar o potencial protetor de vacinas contra EPEC. / The objective of this work was the construction of genetically modified strains of B. subtilis able to express portions of intimin, the main component involved in colonization by enteropathogenic Escherichia coli strains (EPEC) as a strategy of oral vaccination against infectious diarrhea. The vaccines employed five regions of EPEC intimin and B. subtilis strains expressing recombinant proteins in the cytoplasm. Furthermore, we evaluated the use of spores and vegetative cells as vaccine vehicles for the delivery of recombinant antigens based on an epissomal expression system. The efficacy of the vaccines was demonstrated by: (i) production of systemic (IgG) and mucosal (sIgA) antibody responses to intimin, (ii) neutralizing of intimin expressed by different strains of EPEC by the antibodies generated in immunized animals, and (iii) protection to lethal challenges carried out with EPEC strains using an experimental model based in newborn mice. The results represent an important step in the validation of a new vaccine strategy for the control of enteric pathogens. Moreover, we propose the use of an animal model as a new tool to evaluate the protective potential of vaccines against EPEC.
232

Estudo da esterilização por plasma de acoplamento indutivo e análise comparativa com esterilização por óxido de etileno / Study of sterilization by Inductively coupled plasma and comparison with sterilization by ethilene oxyde

Boscariol, Michelle Rigamonti 10 August 2006 (has links)
Em âmbito hospitalar é crescente o emprego de dispositivos confeccionados de distintos materiais termossensíveis. Assim, o emprego de metodologias esterilizantes compatíveis tem sido o foco de muitas pesquisas, dentre as quais destacam-se estudos envolvendo o plasma. O mecanismo de ação deste desenvolve-se com a aplicação de Rádio-Freqüência a gases precursores, resultando na inativação microbiana por espécies altamente reativas. Este método inovador caracteriza-se por não gerar riscos de toxicidade ocupacional e aos pacientes, e ser processado em temperatura próxima ao ambiente. Para análise comparativa foi utilizado o método de esterilização por óxido de etileno (agente químico na forma gasosa). Este gás apresenta características de elevada inflamabilidade, explosividade e toxicidade, por isso é usado diluído em gases inertes, além de deixar residual no material esterilizado, tendo que ter um controle rigoroso no processo de aeração; porém atualmente é um dos métodos mais utilizados para esterilização de materiais odonto-médico-hospitalares, particularmente os termossensíveis. O principal objetivo deste trabalho foi estudar diferentes parâmetros do processo e seus respectivos resultados, que influenciam na esterilização empregando plasma e compará-los com os obtidos empregando óxido de etileno. O equipamento utilizado para o estudo dos processos de esterilização por plasma foi o ICP (Inductively Coupled Plasma). Analisou-se assim para o plasma algumas distintas combinações de parâmetros, tais como: gases (oxigênio puro e mistura deste com peróxido de hidrogênio a 5,10 e 20%), pressão (330 mTor), vazão do gás (100sccm), temperatura (próxima ao ambiente), potência de rádio-freqüência (300, 350 e 400W), tempos de exposição (com intervalos de 3 a 60 min) e umidade relativa (80±5%). No ICP foram desenvolvidas duas fases planejadas para os processos, seguindo uma programação experimental, já no óxido de etileno foram realizadas três séries de exposições sub–letais utilizando mistura esterilizante Oxyfume® 2002 (10% Óxido de Etileno, 63% HCFC 124 e 27% HCFC 22), sendo os parâmetros padronizados: umidade relativa (40 a 60%), concentração do gás (450 mg/L), temperatura (55° C) e tempos de exposição (com intervalos de 3 a 15 min.). Todos os ciclos foram realizados em triplicata. Esporos de Bacillus subtilis var. niger ATCC 9372 foram obtidos a partir de suspensões de microrganismos e inoculados em suportes na concentração de 107 UFC/suporte para serem utilizados nos estudos dos processos de esterilização. Empregou-se a técnica de Pour Plate (incubação em estufa por 24hs a 37 °C) para a quantificação dos esporos. Para o processo de esterilização por plasma os resultados obtidos forneceram valores D que variaram entre 8 e 3 min., dependendo dos parâmetros testados, e para o processo de esterilização por óxido de etileno o Valor D foi de 2,80 min. Concluiu-se que o processo de esterilização por plasma apresentou resultados interessantes e promissores e os melhores resultados foram obtidos com as potências maiores de 350 e 400W para o gás oxigênio puro, caracterizando o plasma como alternativa promissora de esterilização, devido às suas características positivas frente ao óxido de etileno, pois os valores D entre os dois processos de esterilização não apresentaram uma diferença significativa. / The gas Plasma sterilization technology has been emerging as an alternative to conventional low temperature processes since the advent of new therapies using heat sensitive materials in the healthcare field is greater than ever. The gas Plasma mechanism of action includes the generation of actives species by an electrical discharge, which is able to promote lethal effect on microorganisms. The sterilization techniques using gas plasma are under intense investigation and it has already been demonstrated by recent studies that this technology is simple, cost-effective, suitable for microbicidal activity and absent of toxic residuals. Ethylene oxide is the sterilization agent most widely applied to medical devices. However, its explosiveness, inflammability and toxicity led to the search for other sterilization methods at low temperature and it has been used associated to non active gases which inhibit these properties and it is necessary to have the control at the occupational safety and environmental monitoration. Therefore, the aim of this work was to explore possible microbicidal application of the gas plasma sterilization generated by an inductively coupled system and to compare this sterilization method with ethylene oxide (chemistry substance in gaseous form), observing their D value. It was used distinct combinations of process parameters to sterilization by plasma, as follows: radio-frequency powers (300, 350 and 400 watts), exposition times (in the range of 3 to 60 minutes), gas (pure oxygen and mixture with hydrogen peroxide 5,10 and 20%), gas flow (100 sccm), pressure (330 mTorr), temperature (close to the environmental one) and relative humidity 80±5%. For ethylene oxide, Oxyfume 2002® was used (mixture of ethylene oxide, HCFCs 22 and 124), under the concentration of 450mg/L, at the temperature of 55°C and relative humidity of 50±5% and it was submitted to a time of exposition between 3 to 15 minutes. Both processes were submitted to exposition cycles in triple. Bacillus subtilis var. niger ATCC 9372 inoculated in a standard load of 107 spores per carrier was used as biological indicator. After the exposition, the biological indicator\'s spore survivors were counted by the \"Pour Plate\" technique (incubation temperature of 35 ± 2ºC for 24 hours). Significant microbial reduction was observed in some cases where the plasma D value was between 3 and 8 min and 3,08 min, 3,04 min. to 350 and 400W powers respectively. In the ethylene oxide process the D value was 2,80 min. These results evidenced the higher effectiveness of ethylene oxide comparatively to plasma. However the latter presents advantages that make it an interesting alternative to low temperature sterilization processes.
233

Aplicação de microscopia de série temporal para o estudo da expressão gênica e montagem do divisomo em Bacillus subtilis / Aplications of time-lapse microscopy to study gene expression thoughout cell cycle and divisome assembly in Bacillus subtilis

Rados, Theopi Alexandra Varvakis 21 May 2013 (has links)
A divisão celular nas bactérias requer a formação do divisomo, um complexo protéico que tem como o primeira etapa a polimerização da proteína FtsZ, seguida pela associação de 15 outras proteínas conhecidas. Os mecanismos envolvidos na regulação espacial do divisomo são bem caracterizados, mas o controle temporal da divisão celular em relação a outros eventos do ciclo, como a replicação do cromossomo, segue controversa. Neste trabalho, aplicamos a metodologia de microscopia de série temporal para estudar duas questões fundamentais do processo de divisão: a montagem do complexo que executa a divisão e a possibilidade da oscilação periódica na expressão de um ou mais genes envolvidos em divisão possa participar do controle temporal da montagem do divisomo. Para investigar se há oscilação da expressão gênica, construímos inicialmente variantes instáveis GFP através da adição de sequências peptídicas C-terminais que encaminham para a degradação em B. subtilis e utilizamos estes repórteres para criar fusões transcricionais sob o controle de promotores de genes centrais do processo de divisão. Depois de otimizar as condições de microscopia de série temporal com fusões transcricionais usando a variante instável GFPAISV, observamos que a autofluorescência de B. subtilis interferia nas nossas quantificações. Como forma de contornar a autofluorescência, construímos então fusões transcricionais com duas variantes de YFP (proteína fluorescente amarela) e optamos por trabalhar com Ypet-AISV. A análise de filmes de células individuais, tanto com fusões a GFPAISV como a Ypet-AISV, indicou que apenas o promotor do operon ftsL-pbpB apresentava um padrão de oscilação significativamente diferente de um promotor artificial usado como controle negativo. Esta hipótese, no entanto, não foi confirmada por medidas estáticas de populações de células nas quais correlacionamos intensidade de fluorescência com posição no ciclo celular. Portanto, nossos dados não foram capazes de evidenciar flutuações na expressão dos genes ftsL-pbpB, minCD, ftsZ, ftsA e zapA ao longo do ciclo celular. Para estudar a cinética de montagem divisomo foram realizados experimentos de microscopia de série temporal de FtsZ-mCherry e Pbp2B-GFP, onde observamos que a associação de Pbp2B ao divisomo ocorre 3 minutos após a formação do anel de FtsZ em meio rico e 4 minutos em meio mínimo. Também realizamos experimentos de microscopia de série temporal com uma cepa contendo FtsZ-YFP e DivIVA-CFP, determinando que DivIVA é incorporado ao divisomo 16 minutos após a formação do anel de FtsZ em meio rico e 20 minutos em meio mínimo. Estes dados confirmam que a montagem do divisomo ocorre em três etapas, e não duas, como anteriormente proposto. / Cell division in bacteria requires the formation of the divisome, a protein complex that has as the first step polymerization of FtsZ, followed by the assembly of 15 other known proteins. The mechanisms that underlie spatial regulation of divisome assembly have been largely elucidated, but the temporal control that ties the timing of cell division to other cell cycle events, such as chromosomal replication, remains surrounded by controversy. In this work, we use time-lapse microscopy to address two issues in B. subtilis cell division: the timing of divisome assembly, and the possibility that a periodic oscillation in expression of one or more genes essential for divisome assembly may play a role in defining the timing of cell division. To study the possibility of oscilation in gene expression, we have first built unstable variants of GFP by adding to its C-terminus peptide sequences that target the protein for degradation and used those variants to build transcriptional fusions to access the promoter activity of core cell division genes. After optimizing time-lapse conditions with transcriptional fusions to cell divison genes with the unstable GFPAISV, we observed that B. subtilis autofluorescence was an issue to our quantifications. To improve our signal-to-noise ratio, we built transcriptional fusions with two variants of YFP (Yellow Fluorescent Protein), and decided to work with Ypet. In our single-cell analysis for GFPAISV and for Ypet-AISV, only the ftsL operon promoter presented an oscilating pattern different from our negative control. This was not confirmed, however, when we attempted to correlate fluorescence signal with cell cycle position in static single-cell measurements. Thus, we conclude that that there are no fluctuations in ftsL, pbpB, minCD, ftsZ, ftsA or zapA gene expression throughout the cell cycle. To study divisome assembly we performed time-lapse microscopy of FtsZ-mCherry and Pbp2B-GFP, and determined that the association of Pbp2B occurs 3 minutes after FtsZ polymerization in rich medium and 4 minutes in minimal medium. We also performed time-lapse microscopy with FtsZ-YFP and DivIVA-CFP, determining that DivIVA is incorporated to the divisome in 16 minutes after FtsZ polymerization in rich medium and 20 minutes in minimal medium. This data confirms the assembly of the divisome in three steps rather than two, as previously proposed.
234

Relation between the expression of prion protein and the cellular response to oxidative stress: a biological and proteomic approach

Motte dit Falisse, Nandini 07 April 2008 (has links)
Several functions have been attributed to the cellular prion protein, PrPc, amongst which its anti-oxidant role has rapidly been gaining interest in the recent years. We and others have previously shown, that PrPc expressing cells, of neuroblastoma or epithelial origin, seem to exhibit a higher overall viability towards paraquat toxicity than cells expressing basal or low levels of the protein. Although several studies propose a protective mechanism that involves PrPc dependent activation of the superoxide dismutase (SOD) enzymatic machinery or an activation of its own intrinsic antioxidant function, others argue against this SOD-like role. Our objective was to investigate, at a biological and proteomic level, by which potential mechanism PrPc could protect neuroblastoma cells against paraquat induced oxidative damage. Using a biological aproach, we firstly evaluated the status of the Cu/Zn-SOD enzyme in Human neuroblastoma cells expressing different forms of PrPc following their exposure to paraquat. Next, we performed a proteomic study to investigate by which other potential mechanism(s), PrPc could protect the cell against paraquat induced oxidative stress. Our proteomic approach made use of an optimised two-dimensional liquid chromatography system, the ProteomeLab PF-2D, and reverse phase chromatography coupled with lava purple stained SDS-PAGE, both interfaced with tandem mass spectrometry. An interesting aspect of our study has been the development of an original immunoproteomic technique called immuno-PF2D-MS/MS, coupling classical immunological methods to a two-dimensional liquid chromatography proteomic tool interfaced with tandem mass spectrometry. We have proposed this technique for antigenic and serological characterization that have important implications in the study of biomarkers. Another important aspect of our study has been the detection of several candidates that could participate in PrPc-mediated protection against paraquat induced oxidative stress. Although, it was out of our scope to investigate each of these candidates in the present study, it presents an interesting perspective for future studies. We have, however, shown the implication of one such candidate: PARP-1. Complimentary tests will be necessary in the future to confirm the actual interaction of this candidate with PrPc.
235

Control of glutamate homeostasis in the Gram-positive model organism Bacillus subtilis

Stannek, Lorena 28 April 2015 (has links)
No description available.
236

Regulation der Glutamatsynthese in Bacillus subtilis durch die Glutamatdehydrogenase RocG und das Aktivatorprotein GltC / Regulation of glutamate synthesis in Bacillus subtilis by the glutamate dehydrogenase RocG and the activator protein GltC

Commichau, Fabian Moritz 01 November 2006 (has links)
No description available.
237

Struktur- und Funktionsanalyse der Protease RasP aus Bacillus subtilis

Drechsel, Susan 10 October 2014 (has links) (PDF)
Bacillus subtilis ist einer der bislang am besten untersuchten Organismen. Es gilt als Modellbakterium, an welchem stoffwechselphysiologische und genetische Phänomene grundlegend aufgeklärt wurden. Daneben gehört B. subtilis zu den generell unbedenklichen Mikroorganismen und wird von der U.S. Food and Drug Administration (FDA) als ‚GRAS‘ (Generally Regarded As Safe) eingestuft. Dementsprechend wird B. subtilis in der biotechnologischen Industrie zur Herstellung vielfältiger Produkte, z.B. in der Lebensmittelindustrie, eingesetzt. Als Gram-positives Bakterium eignet sich B. subtilis vor allem zur Produktion extrazellulärer Enzyme wie Proteasen und Amylasen. Die Untersuchung der Sekretion dieser Proteine ist sowohl für die grundlagen- als auch für die anwendungsorientierte Forschung von wichtiger Bedeutung. Vorarbeiten der Arbeitsgruppe von Prof. Wiegert haben gezeigt, dass eine Deletionsmutante im Gen der Protease RasP einen vollständigen Defekt der Sekretion einer α-Amylase verursacht. In meiner Promotionsarbeit soll untersucht werden, welche Rolle RasP bei der Sekretion dieser α-Amylase spielt, und welchen Einfluss diese Protease auf die Proteinsekretion allgemein ausübt. Zudem soll, u.a. am Beispiel von Signalpeptiden, der Mechanismus der Substraterkennung durch RasP untersucht werden. Ich erhoffe, mit dieser Arbeit einen entscheidenden Beitrag zum Verständnis der Funktion der Protease RasP zu leisten und damit eine weitere gezieltere Optimierung von B. subtilis Produktionsstämmen in der biotechnologischen Industrie zu ermöglichen.
238

Fusarium sambucinum ASSOCIADO A SEMENTES DE Pinus elliottii: PATOGENICIDADE, MORFOLOGIA, FILOGENIA MOLECULAR E CONTROLE / Fusarium sambucinum ASSOCIATED TO SEEDS OF Pinus elliottii: PATHOGENICITY, MORPHOLOGY, MOLECULAR PHYLOGENY AND CONTROL

Maciel, Caciara Gonzatto 16 July 2012 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Pinus elliottii is an important forestal culture, whose seeds, in terms of health quality, display high vulnerability to fungal pathogenic agents, especially to the association of especially by association of Fusarium spp. which is a responsible agent for seedlings losses in the nursery. This study aims to determine the appropriate method to assess the pathogenicity of Fusarium sp. associated with seeds of P. elliottii, and characterize the fungus, morphological- and molecularly, on its species level, as well as to verify the efficiency of its in vitro and in vivo biological control. Pathogenicity to different treatments were applied: T1 - Contact + Fusarium sp.; T2 - Contact + film coating + Fusarium sp.; T3 - film coating + Fusarium sp.; T4 film coating; T5 - Contact PDA and T6 - No treatment. Morphological characterization was performed using a specific identification key for the genus Fusarium, and the molecular identification, we sequenced three genomic regions of isolate, which are: ITS, elongation factor 1-α and beta-tubulin. In tests of biological control used is Trichoderma spp. and Bacillus subtilis in the commercial forms Agrotrich Plus® and Rizolyptus®, respectively. The control tests were performed in vitro by the method of paired comparison of cultures (pathogen x antagonist) and in vivo tests were carried out in nursery conditions. Fusarium s species that was identified on the seeds was characterized as Fusarium sambucinum, which is pathogenic to P. elliottii, when the seeds are inoculated via contact to the fungal culture during 48 hours. Microbilization of seeds with Bacillus subtilis and Trichoderma spp. provided improvement on the germination potential of them, and, in the case of Agrotrich Plus®, reduced the incidence of rot agent fungi, such as Penicillium sp. and Aspergillus sp.. The antagonistic agents were efficient on the in vitro control of F. sambucinum. Rizolyptus® stood out against the pathogen on the in vivo biocontrol test; it reduced seedlings losses and increased values of their length, as well as, of their green and dry masses. / Pinus elliottii é uma espécie de importância no setor florestal e que apresenta vulnerabilidade na qualidade sanitária de suas sementes, especialmente pela associação de Fusarium spp., responsável por perdas de plântulas no viveiro. O presente trabalho tem como objetivo determinar o método adequado para avaliar a patogenicidade de Fusarium spp. associado a sementes de P. elliottii e caracterizar morfologica e molecularmente o patógeno em nível de espécie, bem como verificar a eficiência do controle biológico in vitro e in vivo do fungo. Para patogenicidade foram aplicados diferentes tratamentos: T1- Contato + Fusarium sp.; T2 - Peliculização + Contato + Fusarium sp.; T3 - Peliculização + Fusarium sp.; T4 Peliculização; T5 - Contato com meio BDA e T6 - Sem tratamento. A caracterização morfológica foi realizada, utilizando uma chave de identificação específica para o gênero Fusarium, e para a identificação molecular, foram sequenciadas três regiões genômicas do isolado, sendo elas: ITS, fator de elongação 1- α e beta-tubulina. Nos testes de controle biológico utilizou-se Trichoderma spp. e Bacillus subtilis, nas formas comerciais Agrotrich Plus® e Rizolyptus®, respectivamente. Os testes de controle in vitro foram realizados pelo método de confronto pareado de culturas (antagonista x patógeno) e os testes in vivo, foram desenvolvidos em condições de viveiro. A espécie de Fusarium identificada nas sementes foi caracterizada como Fusarium sambucinum, patogênico a P. elliottii, quando inoculado via contato com a cultura fúngica por 48 horas. A microbiolização das sementes com Rizolyptus® e Agrotrich Plus® promoveu incremento no potencial germinativo e, no caso do Agrotrich Plus®, reduziu a incidência de fungos apodrecedores como Penicillium sp. e Aspergillus sp. Os antagonistas foram eficientes no controle in vitro de F. sambucinum e, no teste de biocontrole in vivo, o produto Rizolyptus® destacou-se, reduzindo as perdas de plântulas causadas pelo patógeno, assim como, potencializando as variáveis de comprimento de plântula, massa verde e massa seca.
239

Recherche des substrats et des activateurs d'une nouvelle famille de protéine kinase bactérienne / Search for substrates and activators of a new family of bacterial protein kinases

El khoury, Takla 29 February 2016 (has links)
Les protéines kinases sont responsables de la phosphorylation des protéines, une modification post-traductionnelle qui contrôle ainsi de manière très efficace et presque instantanée une multitude de processus cellulaires. Elles sont impliquées dans la régulation des voies métaboliques dans les organismes permettant leurs adaptations aux changements environnementaux. Chez les procaryotes, l'existence de sérine/thréonine et tyrosine kinases est resté pendant longtemps un sujet de controverse. Cependant, au cours des deux dernières décennies, de nombreuses études ont montré que ces types de phosphorylation (Ser/Thr/Tyr) existent chez les bactéries et sont impliqués dans la régulation d'une grande variété de processus biologiques. En plus de protéines kinases apparentés à des enzymes eucaryotes, les bactéries ont également des protéines kinases spécifiques n’ayant aucune ressemblance structurale avec des protéines eucaryotes ce qui, lorsqu’elles sont essentielles, les qualifient en tant que cible pour de nouveaux agents antimicrobiens. YdiB est une nouvelle protéine kinase bactérienne de Bacillus subtilis. La localisation d’YdiB a été étudiée par immunofluorescence révélant sa présence à proximité de la membrane plasmique. L'interaction d’YdiB avec les phospholipides a été étudiée par des essais de flottation et résonance plasmonique de surface. Ceci révèle la présence d'une interaction stable et forte entre la kinase et deux phospholipides: la phosphatidylsérine et la phosphatidyléthanolamine. En outre, la constante d'affinité (KD) entre YdiB et la phosphatidylsérine a été identifiée et est de l’ordre de 13.3x10-9 M. De plus, ces deux phospholipides, ainsi que leur têtes polaires, sont capables d'induire de manière significative l'autophosphorylation d’YdiB.Par ailleurs, le rôle d’YdiB dans la croissance bactérienne en particulier lors d’un stress oxydant a également été étudié dans la souche sauvage et dans le mutant ∆ydiB. Dans des conditions de stress oxydant, la souche ∆ydiB est incapable de survivre alors qu’une complémentation conditionnelle de ce mutant a permis de restaurer un profil de croissance normale de la bactérie. Cela révèle le rôle important joué par YdiB dans la résistance bactérienne au stress oxydant. En outre, des protéines impliquées dans la résistance au stress oxydant comme la superoxide dismutase F (SodF) et superoxide dismutase A (SodA) ont été testés comme substrats potentiels pour YdiB. Par des tests de trans-phosphorylation, nous avons pu montrer que SodA pourrait être un substrat potentiel pour YdiB expliquant ainsi son implication dans la résistance au stress oxydatif dans Bacillus subtilis. / Protein kinases are responsible of protein phosphorylation, a post-translational modification and a very effective and almost instantaneous control of a multitude of cellular processes. They are involved in the regulation of metabolic pathways in living organisms enabling their adaptation to environmental changes. In prokaryotes, the existence of serine/threonine and tyrosine kinases was, for a long time, a subject of controversy. However, over the past two decades, many studies have shown that these types of phosphorylation (Ser/Thr/Tyr) do exist in bacteria and are involved in the regulation of a wide variety of biological processes. In addition to protein kinases related to eukaryotic enzymes, bacteria also have some specific protein kinases having no structural resemblance to their eukaryotic homologues which, if essential, made them a possible target for new antimicrobial agents. YdiB is a novel bacterial protein kinase from Bacillus subtilis. In situ localisation of YdiB has been studied by immunofluorescence which reveals its presence near the plasma membrane. The interaction of YdiB with the membrane phospholipids was assessed by flotation assay and surface plasmon resonance demonstrating the presence of a stable and strong interaction between the kinase and two phospholipids: phosphatidylserine and phosphatidylethanolamine. In addition, the affinity constant (KD) between YdiB and phosphatidylserine was found to be equal to 13.3 x 10-9 M. Moreover, these two phospholipids or just their charged headgroups were able to significantly induce the autophosphorylation of YdiB.On the other hand, the role of YdiB in the bacterial growth especially under oxidative stress was also studied in the wild-type strain and in ∆ydiB mutant. Under oxidative stress conditions, the deleted strain was unable to survive whereas a conditional complementation of ∆ydiB mutant was able to restore a normal growth profile for the bacterium. This reveals the important role played by YdiB in the bacterial resistance to oxidative stress. In addition, protein involved in the resistance to oxidative stress like Superoxide dismutase F (SodF) and superoxide dismutase A (Sod A) were tested as potential substrates for YdiB. Doing the trans-phosphorylation assay, we were able to prove that Sod B could be a potential substrate for YdiB thus explaining its involvement in the resistance to oxidative stress in Bacillus subtilis.
240

Tempo de residência da água em um sistema experimental de aquicultura integrada com camarões, ostras e macroalgas. / Residence time of water in an experimental integrated aquaculture with shrimp, oysters and seaweeds.

Rocha, Nayana Moura da January 2009 (has links)
ROCHA, Nayana Moura da. Tempo de residência da água em um sistema experimental de aquicultura integrada com camarões, ostras e macroalgas. 2009. 97 f. : Dissertação (mestrado) - Universidade Federal do Ceará, Centro de Ciências Agrárias, Departemento de Engenharia de Pesca, Fortaleza-CE, 2009 / Submitted by Nádja Goes (nmoraissoares@gmail.com) on 2016-07-20T12:42:26Z No. of bitstreams: 1 2009_dis_nmrocha.pdf: 1596577 bytes, checksum: b038df8495915b1a6a78859b019fa251 (MD5) / Approved for entry into archive by Nádja Goes (nmoraissoares@gmail.com) on 2016-07-20T12:42:41Z (GMT) No. of bitstreams: 1 2009_dis_nmrocha.pdf: 1596577 bytes, checksum: b038df8495915b1a6a78859b019fa251 (MD5) / Made available in DSpace on 2016-07-20T12:42:41Z (GMT). No. of bitstreams: 1 2009_dis_nmrocha.pdf: 1596577 bytes, checksum: b038df8495915b1a6a78859b019fa251 (MD5) Previous issue date: 2009 / Shrimp culture presented at a world-wide level a significant growth in recent years, mainly in tropical and subtropical regions, however, this expansion comes with diverse environment negative impacts, mainly related to the cultures effluents, which are rich in nitrogen and phosphorous, that are many times discarded in the environment without any previous treatment. Aiming the improvement of its techniques the aquaculture industry needs to develop new culture methods, which can improve its efficiency and attenuate the consequences of its activities to keep the health of aquatic ecosystems. In this context appears the integrated aquaculture, witch involves the culture of different organisms in the production process, and can be an ambient and economic viable alternative. In order to study this technology efficiency, the water quality of an integrated aquaculture system with shrimps, oysters and macroalgae was evaluated in laboratory conditions, using three different water residence times. The integrated system was composed of five 50 L aquariums, one for shrimps culture, one destined to ration remaining portions and dejections sedimentation, one for oysters culture, another one for macroalgae culture and a last one to store the recirculation water, which was carried through the system by pumping after 48, 72 and 96 hours of water residence. The physical-chemical parameters temperature, salinity and dissolved oxygen were daily monitored and the concentrations of ammonium, nitrite, nitrate and phosphate, turbidity and pH evaluated weekly. Cultivated organisms growth was also weekly attended and after the end of the experiment, shrimps, oysters and macroalgae total protein content were determined. The results showed that sedimentation reduced nitrite and nitrate concentrations, as well as the turbidity of the culture water. Oysters stage reduced ammonium concentrations and also the turbidity, beyond had kept low levels of nitrite concentrations in the water, while macroalgae stage did not interfered with ammonium, nitrite, nitrate and turbidity levels. With exception of phosphate, witch practically did not varied throughout the experimental period all the evaluated parameters at all water residence tested times were efficiently reduced by the integrated system. Shrimps presented an excellent development and survival mainly with 72 hours of water residence in the system, and the oysters practically kept its initial biomass. Although macroalgae did not showed a good development and significantly not modify the nutrients levels of the water, they were capable to accumulate nitrogen in the protein form and to increase their absorption capacity when cultivated with nutrients limitation. The results suggest that the establishment of aquaculture integrated systems can be a viable vii alternative for aquafarmers, since it is possible to minimize the environment impacts, provide the costs reduction without water pumping and increase the profits by the production diversification. / O cultivo de camarões apresentou, a nível mundial, um crescimento bastante significativo nos últimos anos, principalmente em regiões tropicais e subtropicais, no entanto, esta expansão vem causando diversos impactos ambientais negativos, principalmente relacionados aos efluentes dos cultivos, os quais são ricos em nitrogênio e fósforo, que muitas vezes são descartados no ambiente sem qualquer tratamento prévio. Visando a melhoria de suas técnicas, a indústria da aqüicultura necessita desenvolver novos métodos de cultivo, os quais podem melhorar sua eficiência e remediar as conseqüências de suas atividades, para manter a saúde dos ecossistemas aquáticos. Neste contexto surge a aqüicultura integrada, a qual, envolve o cultivo de diferentes organismos no processo de produção, e pode ser uma alternativa ambiental e economicamente viável. Buscando estudar a eficiência desta tecnologia, foi avaliada a qualidade da água, em um sistema de aqüicultura integrada com camarões, ostras e macroalgas em condições laboratoriais, utilizando três diferentes tempos de residência da água. O sistema integrado foi composto por cinco aquários de 50 L, sendo um para o cultivo de camarões, um destinado à sedimentação de restos de ração e dejetos, um para o cultivo de ostras, outro para o cultivo de macroalgas e um último para armazenar a água durante a recirculação, a qual foi movida no sistema através de bombeamento após 48, 72 e 96 horas de residência da água. Os parâmetros físico-químicos temperatura, salinidade e oxigênio dissolvido foram monitorados diariamente e as concentrações de amônia, nitrito, nitrato e fosfato, a turbidez e o pH foram avaliados semanalmente. O crescimento dos organismos também foi acompanhado semanalmente e, após o término do experimento, foi realizada a determinação do conteúdo de proteína total nos camarões, ostras e macroalgas. Os resultados mostraram que a sedimentação reduziu as concentrações de nitrito e nitrato, bem como a turbidez da água de cultivo. A etapa das ostras reduziu as concentrações de amônia e também a turbidez, além de manter baixas as concentrações de nitrito na água, enquanto a etapa das macroalgas não interferiu nos níveis de amônia, nitrito, nitrato e turbidez. Com exceção do fosfato que praticamente não variou no período experimental, todos os parâmetros avaliados, em todos os tempos de residência da água testados, foram eficientemente reduzidos pelo sistema integrado. Os camarões apresentaram um ótimo desenvolvimento e sobrevivência, principalmente com 72 horas de residência da água no sistema e as ostras praticamente mantiveram sua biomassa inicial. Apesar das macroalgas não terem se desenvolvido bem e não alterarem significativamente os níveis de nutrientes na água, foram capazes de acumular nitrogênio na forma de proteínas e aumentar sua capacidade de absorção, quando cultivadas com limitação de nutrientes. Os resultados sugerem que o estabelecimento de sistemas de aqüicultura integrada pode ser uma alternativa viável para os aqüicultores, visto que é possível minimizar os impactos ambientais, reduzir custos evitando o bombeamento de água e aumentar os lucros com a diversificação da produção.

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