Differential proteomic analysis of lactic acid bacteria - Escherichia coli O157:H7 interaction and its contribution to bioprotection strategies in meat

Original ResearchHuman infection by Enterohemorrhagic Escherichia (E.) coli (EHEC) occurs through the ingestion of contaminated foods such as milk, vegetable products, water-based drinks, and particularly minced meats. Indeed EHEC is a pathogen that threatens public health and meat industry. The potential of different Lactic Acid Bacteria (LAB) strains to control EHEC in a meat-based medium was evaluated by using a simple and rapid method and by analyzing the growth kinetics of co-cultures (LAB-EHEC) in a meat-based medium. The activity of LAB toward EHEC in co-cultures showed variable inhibitory effect. Although, LAB were able to control EHEC, neither the produced acid nor bacteriocins were responsible of the inhibition. The bacteriocinogenic Enteroccus (Ent.) mundtii CRL35 presented one of the highest inhibition activities. A proteomic approach was used to evaluate bacterial interaction and antagonistic mechanisms between Ent. mundtii and EHEC. Physiological observations, such as growth kinetics, acidification ability and EHEC inhibitory potential were supported by the proteomic results, demonstrating significant differences in protein expression in LAB: (i) due to the presence of the pathogen and (ii) according to the growth phase analyzed. Most of the identified proteins belonged to carbohydrate/amino acid metabolism, energy production, transcription/translation, and cell division. These results contribute to the knowledge of competition strategies used by Ent. mundtii during its co-culture with EHEC setting new perspectives for the use of LAB to control this pathogen in meatinfo:eu-repo/semantics/publishedVersio

Evaluation of a novel Escherichia coli fusion system for overproduction of recombinant immunogenic proteins

Recombinant protein production has been widely applied for therapeutic and diagnostic applications, namely for polyclonal antibody production. Antibodies are usually raised against a specific protein by immunization of animals with the purified protein. The bacterium Escherichia coli is one of the most used host cells for the bio-production of proteins, but it still presents some drawbacks: many proteins of biomedical interest are difficult to express properly in this host system, resulting in insoluble protein aggregates. Gene fusion technology has been employed to optimize recombinant protein production in E. coli. Fusion partners have also been used to potentially increase protein immunogenicity. In this work, the overproduction and immunopotentiating properties of a novel fusion system were studied. Novel fusion tags, Fh8 and H, were fused to five target proteins with diagnostic interests: CP12, a 12 kDa surface protein from Cryptosporidium parvum oocysts; CWP, a cyst wall protein from Giardia lamblia; ENT, a surface protein from Entamoeba histolytica cysts; TgOWP, a Toxoplasma gondii oocyst wall protein; and Frutalin, a recombinant lectin from Artocarpus incisa seeds. Production yields of all Fh8-fused proteins, H-fused proteins and non-fused recombinant proteins were compared and polyclonal antibodies were raised against CP12, CWP and ENT nonfused and H-fused antigens. Overall, the results showed that the fusion of both Fh8 and H tags to all target proteins improved their production in comparison with the respective non-fused target proteins. Moreover, the H tag efficiently increased CP12, CWP and ENT specific immunogenicity without being removed from the fusion antigens and without coadministration of adjuvants, resulting in a more effective and earlier immune response. The overproduction and immunopotentiating effects observed for this novel fusion system make it a unique alternative for recombinant protein production in E. coli and for immunodiagnostic and immunoprophylactic purposes

OMICs approaches in diarrhetic shellfish toxins research

ReviewDiarrhetic shellfish toxins (DSTs) are among the most prevalent marine toxins in Europe’s and in other temperate coastal regions. These toxins are produced by several dinoflagellate species; however, the contamination of the marine trophic chain is often attributed to species of the genus Dinophysis. This group of toxins, constituted by okadaic acid (OA) and analogous molecules (dinophysistoxins, DTXs), are highly harmful to humans, causing severe poisoning symptoms caused by the ingestion of contaminated seafood. Knowledge on the mode of action and toxicology of OA and the chemical characterization and accumulation of DSTs in seafood species (bivalves, gastropods and crustaceans) has significantly contributed to understand the impacts of these toxins in humans. Considerable information is however missing, particularly at the molecular and metabolic levels involving toxin uptake, distribution, compartmentalization and biotransformation and the interaction of DSTs with aquatic organisms. Recent contributions to the knowledge of DSTs arise from transcriptomics and proteomics research. Indeed, OMICs constitute a research field dedicated to the systematic analysis on the organisms’ metabolisms. The methodologies used in OMICs are also highly e ective to identify critical metabolic pathways a ecting the physiology of the organisms. In this review, we analyze the main contributions provided so far by OMICs to DSTs research and discuss the prospects of OMICs with regard to the DSTs toxicology and the significance of these toxins to public health, food safety and aquacultureinfo:eu-repo/semantics/publishedVersio

Exames de imagem no ensino médio : representações de futuros professores de física

Tomamos como apoio teórico-metodológico noções da Análise de Discurso iniciada por Michel Pêcheux e buscamos responder à seguinte questão: De que maneira o trabalho pedagógico com uma unidade de ensino sobre exames de imagem pode contribuir para que nas representações de futuros professores eles considerem a possibilidade de abordar esse tema no Ensino Médio? As análises realizadas indicaram que antes do trabalho pedagógico com essa unidade eles não levantaram a possibilidade de virem a abordar os exames de imagem em suas aulas. Já depois da efetivação desse trabalho notamos que sentidos que apontam para a relevância em abordá-los parecem ter sido incorporados às suas representações sobre o que deve ser ensinado no Ensino Médio, especialmente devido ao valor social que passaram a atribuir ao tema

A Leitura Por Alunos do Ensino Médio de Um Texto Considerado de Alto Grau de Dificuldade

Considerando resultados de estudos realizados sobre a leitura de divulgação científica (DC) no ensino básico de física/ciências e tomando como apoio teórico-metodológico noções da Análise de Discurso em sua vertente iniciada por Pêcheux, procuramos responder duas questões: como se dá o funcionamento de um texto de DC que consideramos com alto grau de dificuldade se ele for trabalhado sem modificações? E: o possível interesse dos estudantes pela leitura de textos de DC se deve mais ao tema discutido no texto ou ao tipo de linguagem com que foi produzido? As análises de informações coletadas junto a estudantes do Ensino Médio após o desenvolvimento de uma atividade de leitura de DC sugerem, entre outras coisas, que encontrar muitas dificuldades na interpretação de um texto pode desencorajá-los pelo estudo de um tema que lhes interessava e que mesmo textos de DC podem ser pouco acessíveis a alunos desse nível de ensino

Blind multiuser equalization using a PARAFAC-subspace spproach

- Dans cet article, nous utilisons la décomposition tensorielle PARAFAC (PARAllel FACtors) en vue de développer une nouvelle approche pour l'égalisation aveugle multi-utilisateur dans le cadre des systèmes de communications sans fil. Le système considéré est basé sur l'utilisation conjointe d'un réseau d'antennes et d'un sur-échantillonnage à la réception. Nous proposons tout d'abord un modèle tridimensionnel du type PARAFAC pour le signal reçu, dont les 3 dimensions sont l'espace, le temps et le sur-échantillonnage. Ensuite, nous présentons un nouveau récepteur aveugle multi-utilisateur pour la séparation des signaux et pour l'égalisation. Le récepteur proposé combine une modélisation PARAFAC, une méthode de sous-espace et l'exploitation de la propriété d'alphabet fini des symboles transmis. Des résultats de simulations sont montrés pour illustrer la performance du récepteur aveugle proposé

Characterization of CRISPR-Cas systems in the Ralstonia solanacearum species complex

Clustered regularly interspaced short palindromic repeats (CRISPRs) are composed of an array of short DNA repeat sequences separated by unique spacer sequences that are flanked by associated (Cas) genes. CRISPR‐Cas systems are found in the genomes of several microbes and can act as an adaptive immune mechanism against invading foreign nucleic acids, such as phage genomes. Here, we studied the CRISPR‐Cas systems in plant‐pathogenic bacteria of the Ralstonia solanacearum species complex (RSSC). A CRISPR‐Cas system was found in 31% of RSSC genomes present in public databases. Specifically, CRISPR‐Cas types I‐E and II‐C were found, with I‐E being the most common. The presence of the same CRISPR‐Cas types in distinct Ralstonia phylotypes and species suggests the acquisition of the system by a common ancestor before Ralstonia species segregation. In addition, a Cas1 phylogeny (I‐E type) showed a perfect geographical segregation of phylotypes, supporting an ancient acquisition. Ralstoniasolanacearum strains CFBP2957 and K60T were challenged with a virulent phage, and the CRISPR arrays of bacteriophage‐insensitive mutants (BIMs) were analysed. No new spacer acquisition was detected in the analysed BIMs. The functionality of the CRISPR‐Cas interference step was also tested in R. solanacearum CFBP2957 using a spacer‐protospacer adjacent motif (PAM) delivery system, and no resistance was observed against phage phiAP1. Our results show that the CRISPR‐Cas system in R. solanacearum CFBP2957 is not its primary antiviral strategy

Tensor-Based Methods for Blind Spatial Signature Estimation in Multidimensional Sensor Arrays

The estimation of spatial signatures and spatial frequencies is crucial for several practical applications such as radar, sonar, and wireless communications. In this paper, we propose two generalized iterative estimation algorithms to the case in which a multidimensional (R-D) sensor array is used at the receiver. The first tensor-based algorithm is an R-D blind spatial signature estimator that operates in scenarios where the source’s covariance matrix is nondiagonal and unknown. The second tensor-based algorithm is formulated for the case in which the sources are uncorrelated and exploits the dual-symmetry of the covariance tensor. Additionally, a new tensor-based formulation is proposed for an L-shaped array configuration. Simulation results show that our proposed schemes outperform the state-of-the-art matrix-based and tensor-based techniques

Synthesis of Bis(3-indolyl)methanes Mediated by Potassium tert-Butoxide

The authors thank the Fundação para a Ciênciae Tecnologia for the fellowship PD/BD/142876/2018.This work was supported by the Associate Laboratory for Green Chemistry– LAQV which is financed by national funds from FCT/MCTESUIDB/50006/2020,UIDP/50006/2020(LAQV).The National NMR Facility is supported by FCT,ROTEIRO/0031/2013-PINFRA/22161/2016,co-financed by FEDER through COMPETE2020,POCI,andPORLandFCT through PIDDAC)and CERMAX(022162).LBM also thanks to FCT/MCTES for the CEEC-Individual Program Contract(CEECIND/03810/2017)The indole moiety is an important N-heterocycle found in natural products, and a key structural component of many value-added chemicals including pharmaceuticals. In particular, bis(3-indolyl)methanes (BIMs) are an important subgroup of indoles, composed of two indole units. Herein, we report the development of a simple method to access BIMs derivatives in yields of up to 77 % by exploiting a tBuOK-mediated coupling reaction of indoles and benzyl alcohols.publishersversionpublishe