The entropy of elliptical galaxies in Coma: a clue for a distance indicator

We have fitted the surface brightness of a sample of 79 elliptical galaxies pertaining to the Coma cluster of galaxies using the Sersic profile. This model is defined through three primary parameters: scale length (a), intensity (\Sigma_0), and a shape parameter (\nu); physical and astrophysical quantities may be computed from these parameters. We show that correlations are stronger among primary parameters than the classical astrophysical ones. In particular, the galaxies follow a high correlation in \nu and a parameters. We show that the \nu and a correlation satisfies a constant specific entropy condition. We propose to use this entropy relation as distance indicator for clusters.Comment: 5 pages, 3 figures, submitted to MNRAS Letter

Um olhar para o discurso docente a partir dos processos de recontextualizações de uma prática pedagógica inovadora no Brasil

Nesta pesquisa, a partir da entrevista com uma professora que participou de um programa de formação continuada, no qual tratou-se da questão da inovação no ensino de ciências e com base no referencial teórico-metodológico da Análise Crítica do Discurso e do conceito de recontextualização desenvolvido por Bernstein, investigamos como o discurso docente é constituído e constitui discursos que moldam práticas pedagógicas. Análises de realocações, reorganizações e rearticulações discursivas nos permitiram entender o discurso da professora no contexto das relações de poder e de controle estabelecidas entre os campos discursivos ao qual está subordinada

Comparative study of the opportunistic yeasts Candida glabrata and Candida bracarensis infection strategies

Dissertação de mestrado em Genética MolecularYeasts of the genus Candida are important human pathogens. A new species, Candida bracarensis, was recently described revealing phenotypic and genetic similarities with Candida glabrata, a widespread pathogen, and also with Saccharomyces cerevisiae. The incidence of C. bracarensis has increased globally being now regarded as an emergent fungal pathogen. However, little is known about its characteristics as a pathogenic agent and the interaction with its host. The aim of this work was to compare C. bracarensis with C. glabrata and S. cerevisiae concerning their virulence atributes and the interaction with the host. The analysis of virulence factors has an important role in the study of pathogens and their strategies of infection. However, most of the virulence attributes of the successful pathogen C. albicans are absent in C. glabrata. Here, the inability of C. glabrata to produce secreted aspartyl proteinases (Sap) or hyphae was confirmed. Moreover, we show in this study that all C. bracarensis strains analysed failed to produce Sap and to filament. Phagocytosis plays a critical role in innate immunity, facilitating the removal and killing of pathogens, and priming the adaptive immune response. The phagocytosis rate of the different yeast species was evaluated in murine and human macrophages. C. glabrata was phagocytosed at higher rates than the other two yeast species, being S. cerevisiae the one inducing the lowest phagocytosis rate. Upon interaction with pathogens, phagocytes rapidly produce ROS to destroy invading microbes, however, several pathogens have developed strategies to evade this microcidal mechanism. Here, it is shown that not only viable C. glabrata and C. bracarensis could suppress ROS production, but unexpectedly, S. cerevisiae could reduce ROS production to more than a half. Although these results do not by themselves fully elucidate the disparate incidence of C. glabrata vs C. bracarensis, they nevertheless contribute to better understand the differences on the interaction of these two related species with the host.As leveduras do género Candida são importantes agentes patogénicos em infeções fúngicas humanas. Recentemente foi descrita uma nova espécie, Candida bracarensis, que se assemelha tanto fenotípica como genotipicamente com Candida glabrata e também com Saccharomyces cerevisiae. A incidência desta nova espécie tem vindo a aumentar, estando entre os fungos considerados emergentes. Contudo, muito pouco se conhece acerca das suas características como patogéneo, dos seus fatores de virulência e sobre a sua interação com o hospedeiro. Assim, o objetivo deste projeto foi comparar C. bracarensis, C. glabrata e S. cerevisiae no que diz respeito aos mecanismos de interação com o hospedeiro. A análise dos fatores de virulência tem um papel importante no estudo de agentes patogênicos e das suas estratégias de infecção. No entanto, a maioria dos factores de virulência do agente oportunista bem sucedido C. albicans estão ausentes em C. glabrata. Neste estudo, confirmou-se a incapacidade de C. glabrata de produzir proteinases asparticas (Sap) ou hifas. Além disso, mostramos neste estudo que todas as estirpes de C. bracarensis analisadas não conseguiram produzir Sap nem filamentar. A fagocitose desempenha um papel crítico na imunidade inata, facilitando a remoção e morte de agentes patogênicos e estimulando a resposta imune adaptativa. A taxa de fagocitose das diferentes espécies de levedura foi avaliada em macrófagos murinos e macrófagos humanos. C. glabrata foi fagocitada a taxas superiores do que as outras duas espécies de leveduras, sendo S. cerevisiae o que induz a menor taxa de fagocitose. Após a interação com agentes patogênicos, os fagócitos produzem rapidamente ROS para destruir microrganismos invasores, no entanto, vários microrganismos desenvolveram estratégias para evitar esse mecanismo microbicida. Aqui, mostra-se que não só C. glabrata e C. bracarensis apresentam capacidade de suprimir a produção de ROS, mas, inesperadamente, S. cerevisiae consegue reduzir a produção de ROS para mais de metade. Ainda que estes resultados não expliquem por si só a disparidade encontrada na incidência de C. glabrata e C. bracarensis, contribuem no entanto para um melhor conhecimento da interação destas duas espécies com o hospedeiro

Micoteca da Universidade do Minho: 9 years operation

The Micoteca da Universidade do Minho culture collection (MUM) was established in 1996, at the Biological Engineering Department of Minho University, in Portugal, aiming to maintain and supply fungal strains for research in biotechnology and teaching, and to become a centre of knowledge, information and training in mycology. The original collection, containing 38 strains with specific degradatory capabilities, mainly cellulolytic, was typically a private research collection, and accompanied the researchers throughout various laboratories. Pressing solicitations from the local agro-food industry, from which several cooperative research projects had been developed, and the fact that University of Minho was developing an institutional policy for the establishment of horizontal services to support research, made possible, among other factors, the creation of a culture collection capable of addressing the issues of availability of strains and related information, of research and selection of appropriate technologies, and of training and building of expertise. MUM now harbours 138 species and 59 genera, totalling 396 strains. Among its holdings the collection includes fungi producing extracellular enzymes, mycotoxins, fungi from tap and bottled water, and airborne fungi, isolated during research activities on biodegradation and biodeterioration, mycotoxins in food products and studies of air quality in industrial environments. Penicillium and Aspergillus are the main genera represented in the culture collection in termos of species diversity and number of preserved strains. Standard procedures have been set up for strain reception within established admission criteria and for strain preservation, storage and supply. A computerised data base was built in-house, having in mind the storage and retrieval of strain data and also the stock management of preserved strains. External access to information on available strains is possible through the electronic catalogue at http://www.micoteca.deb.uminho.pt. MUM was built on well established criteria taking into account relevant international quality standards. Membership in international organizations such as ECCO and WFCC was accomplished and MUM is also registered in the WDCM, BioCise, and BioCase information services. In the last three years MUM has been involved in the OECD initiatives related to guidance for the operation of Biological Resource Centres (BRC’s). It is foreseen that in the near future new facilities will be available at the Health of Sciences research building with better working and storage areas, in the vicinity of PCL3 laboratories. MUM is therefore in position to plan ahead in relation to the widening of the scope of its holdings, and to propose the strengthening of ties with other specialised sectors in life sciences within the University in order to achieve a certified BRC for the University of Minho (BRC-UMinho)

Micoteca da Universidade do Minho (MUM)

PRAXIS XXI

Understanding biochar functionalities based on feedstock characteristics and processing conditions

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