Picocyanobacteria From a Clade Of Marine Cyanobium Revealed Bioactive Potential Against Microalgae, Bacteria, And Marine

The production of bioactive compounds either toxic or with pharmacological applications by cyanobacteria is well established. However, picoplanktonic forms within this group of organisms have rarely been studied in this context. In this study, the toxicological potential of picocyanobacteria from a clade of marine Cyanobium strains isolated from the Portuguese coast was examined using different biological models. First, strains were identified by applying morphological and molecular approaches and cultured under lab conditions. A crude extract and three fractions reflecting a preliminary segregation of lipophilic metabolites were tested for toxicity with the marine microalga Nannochloropsis sp., the bacteria Pseudomonas sp., the brine shrimp Artemia salina, and fertilized eggs of the sea urchin Paracentrotus lividus. No significant apparent adverse effects were noted against Artemia salina. However, significant adverse effects were found in all other assays, with an inhibition of Nannochloropsis sp. and Pseudomonas sp. growth and marked reduction in Paracentrotus lividus larvae length. The results obtained indicated that Cyanobium genus may serve as a potential source of interesting bioactive compounds and emphasize the importance of also studying smaller picoplanktonic fractions of marine cyanobacteria.

Avaliação do efeito da microfauna do tanque de arejamento no efluente final

O presente trabalho, efetuado na Estação de Tratamento de Águas Residuais do Freixo (ETAR do Freixo), decorreu durante um período de nove meses, (entre Dezembro de 2012 e Agosto de 2013), e teve como principais objetivos: - a observação microscópica e respetiva identificação dos organismos presentes nas lamas ativadas dos reatores biológicos da ETAR (incidindo nos protozoários, metazoários e bactérias filamentosas); - estabelecer a relação entre os organismos identificados/quantidade respetiva e a sedimentabilidade das lamas ativadas e sua influência no processo de depuração; - avaliar a variação das espécies identificadas com as alterações processuais. Para o efeito, a metodologia utilizada foi: - a colheita diária de amostras em vários pontos da ETAR; - a determinação dos parâmetros operacionais e caracterização das amostras recolhidas, tendo sido efetuadas 6039 análises físico-químicas, incluindo ao afluente à ETAR, ao afluente e ao conteúdo dos dois reatores biológicos, à corrente de recirculação de lamas e ao efluente; - a visualização diária microscópica ótica sem contraste de fase dos microrganismos presentes nos reatores biológicos; - a visualização microscópica ótica com contraste de fase da microfauna presente nos reatores biológicos, sendo efetuadas 16 identificações e quantificações dos protozoários presentes nas lamas ativadas dos dois reatores e 10 identificações e quantificações das bactérias filamentosas presentes nos dois reatores biológicos. O início do estudo ocorreu num período em que se começou a verificar um aumento excessivo de espumas nos decantadores secundários, resultando numa fraca sedimentabilidade das lamas e numa menor qualidade do efluente final. Na tentativa de reduzir a excessiva ascensão do manto de lamas que se verificou, foram efectuadas alterações operacionais, consistindo: - na alteração da razão de recirculação da decantação secundária para os reatores biológicos; - na introdução de um composto altamente concentrado em matéria orgânica na corrente de recirculação de lamas; - na alteração da extração de lamas biológicas. Verificou-se que as alterações processuais efetuadas foram muito eficazes na diminuição do manto de lamas da decantação secundária, bem como muito eficazes na qualidade do efluente final. Durante os meses de Fevereiro a Agosto fez-se o acompanhamento diário de todas as condições de operação de modo a manter e validar o procedimento de operação, o qual se considerou muito eficaz em termos de obtenção de uma água tratada de excelente qualidade. Durante o estudo efetuado, verificou-se que a população microbiológica existente nos dois reatores biológicos se manteve praticamente inalterada durante todo o período, sendo os móveis de fundo e os sésseis os grupos dominantes. Esta dominância traduziu-se na elevada qualidade do efluente final que se observou a partir do mês de Fevereiro, tendo dificultado o estudo de novas condições de operação, mas facilitando a validação do procedimento adotado. No que se refere às bactérias filamentosas, verificou-se que são diversas as espécies presentes nos reatores biológicos e que existem em grande abundância, sendo que o Tipo 0092 é claramente dominante. O excessivo crescimento deste tipo de bactérias mostrou ser o maior problema a nível microbiológico no processo de tratamento da instalação, tornando-se crítico no período de inverno em que a temperatura e os picos de pluviosidade se mostraram condições favoráveis ao seu desenvolvimento. Para além da temperatura outros fatores mostraram-se responsáveis pelo seu crescimento tais como a razão Alimento/Microrganismo (A/M), a idade das lamas, a carga mássica afluente e o teor de oxigénio dissolvido nos reatores biológicos. Pode-se concluir que apesar de não se trabalhar com os valores teóricos dos parâmetros microbiológicos e operacionais considerados ideais, a ETAR do Freixo, possui um tratamento bastante eficaz na remoção da carga orgânica, na remoção de nutrientes e na remoção de sólidos suspensos totais, apesar da não existência de uma etapa de afinação final como a filtração.

Mitosis and protein Na-terminal acetylation

Dissertation presented to obtain the Ph.D degree in Developmental Biology

Heat stress adaptation in hyperthermophiles: bosynthesis of inositol-containing compatible solutes

Dissertation presented to obtain the Ph.D. degree in Biochemistry

Vibrio vulnificus as a health hazard for shrimp consumers

Over the last 30 years, a number of Vibrio species found in the aquatic environment have been indicated as cause of disease in human beings. Vibrio vulnificus is an emergent pathogen, an invasive and lethal marine bacterium related to wound infection and held accountable for gastroenteritis and primary septicemia. It occurs quite frequently in marine organisms, mainly in mollusks. This study aimed at isolating and identifying strains of V. vulnificus based upon the analysis of twenty samples of seabob shrimp, Xiphopenaeus kroyeri (Heller), purchased at the Mucuripe fish market (Fortaleza, Brazil). TCBS agar was used to isolate suspect strains. Seven of twenty-nine strains isolated from six different samples were confirmed as such by means of biochemical evidence and thus submitted to biological assays to determine their virulence. The susceptibility of the V. vulnificus strains to a number of antibiotics was tested. None of the V. vulnificus strains showed signs of virulence during a 24-hour observation period, possibly due to the shedding of the capsules by the cells. As to the results of the antimicrobial susceptibility tests, the seven above-mentioned V. vulnificus strains were found to be sensitive to nitrofurantoin (NT), ciprofloxacin (CIP), gentamicin (GN) and chloramphenicol (CO) and resistant to clindamycin (CI), penicillin (PN) and ampicillin (AP).

Prevalence of putative periodontopathogens from periodontal patients and healthy subjects in São Paulo, SP, Brazil

A. actinomycetemcomitans, B. forsythus, P. gingivalis, C. rectus, E. corrodens, P. intermedia, F. nucleatum, and T. denticola were identified from subgingival plaque from 50 periodontal patients and 50 healthy subjects. PCR products from each species showed a specific band and could be used to identify periodontal organisms from clinical specimens. Identical negative or positive results between PCR and culture occurred in 66% (A. actinomycetemcomitans) to 93% (F. nucleatum) of the samples. PCR detection odds ratio values for A. actinomycetemcomitans, B. forsythus, C. rectus, E. corrodens, P. intermedia, and T. denticola were significantly associated with disease having a higher OR values for B. forsythus (2.97, 95% CI 1.88 - 4.70). Cultures showed that A. actinomycetemcomitans, B. forsythus and P. intermedia were associated with periodontitis, however, P. gingivalis, C. rectus, E. corrodens and F. nucleatum were not significantly associated with the disease.

Evidence of spotted fever group rickettsiae in state of Rio de Janeiro, Brazil

Ticks were obtained from dogs from February to September of 1999 at weekly intervals, in the County of Piraí, State of Rio de Janeiro. Four hundred seventy four ixodids were taxonomically identified, 103 Amblyomma cajennense, seven Amblyomma ovale, 209 Rhipicephalus sanguineus, and 155 Amblyomma sp. An hemolymph test associated with Giemsa's stain revealed two specimens in 163 ticks tested (R. sanguineus and Amblyomma sp), containing rickettsia-like organisms. Direct immunofluorescence verified the presence of spotted fever group rickettsia in one specimen of R. sanguineus. Considering the limited information on rickettsiosis in Brazil, principally in relation to the vectors involved in perpetuating it in foci, these preliminary results give us an idea on the importance of infection in ticks, allowing to expand our knowledge on this zoonosis.

Chromatin dynamics in Arbidopsis development: a live cell imaging approach

Dissertation presented to obtain the Ph.D degree in Biology

Formate metabolism in sulfate reducing bacteria

Dissertation presented to obtain the Ph.D degree in Biochemistry

Crystallographic studies on two hyperthermophilic enzymes

Dissertation presented to obtain the Ph.D degree in Biochemistry

Functional and molecular characterization of SR45, a plant-specific factor involved in sugar and stress signaling in Arabidopsis thaliana

Dissertation presented to obtain the Ph.D degree in Molecular Biology

Detection of Vibrio parahaemolyticus and Vibrio cholerae in oyster, Crassostrea rhizophorae, collected from a natural nursery in the Cocó river estuary, Fortaleza, Ceará, Brazil

Oysters are edible organisms that are often ingested partially cooked or even raw, presenting therefore a very high risk to the consumers' health, especially in tropical regions. The presence of Vibrio cholerae and Vibrio parahaemolyticus in oysters sampled at an estuary in the Brazilian northeastern region was studied, with 300 oysters tested through an 8-months period. The salinity of the water at the sampling point varied between 3% and 27‰. V. cholerae was the most frequently detected species (33.3% of the samples), and of the 22 V. cholerae isolates, 20 were identified as non-O1/non-O139, with two of the colonies presenting a rough surface and most of remaining ones belonging to the Heiberg II fermentation group. V. parahaemolyticus was isolated from just one of the samples. Other bacteria such as Providencia spp., Klebsiella spp. and Morganella morganii were also isolated.

Cytotoxicity Induced by Extracts of Pisolithus tinctorius Spores on Human Cancer and Normal Cell Lines—Evaluation of the Anticancer Potential

Fungi have been considered a potential source of natural anticancer drugs. However, studies on these organisms have mainly focused on compounds present in the sporocarp and mycelium. The aim of this study was to assess the anticancer potential of fungal spores using a bioassay-guided fractionation with cancer and normal cell lines. Crude extracts from spores of the basidiomycetous fungus Pisolithus tinctorius were prepared using five solvents/solvent mixtures in order to select the most effective crude extraction procedure. A dichloromethane/methanol (DCM/MeOH) mixture was found to produce the highest extraction yield, and this extract was fractionated into 11 fractions. Crude extracts and fractions were assayed for cytotoxicity in the human osteocarcinoma cell line MG63, the human breast carcinoma cell line T47D, the human colon adenocarcinoma cell line RKO, and the normal human brain capillary endothelial cell line hCMEC/D3. Cytotoxicity was assessed by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) reduction assay. The results showed a reduction in cancer cell viability of approximately 95% with 4 of 11 fractions without a significant reduction in viability of hCMEC/D3 cells. Data demonstrated that spores of P. tinctorius might serve as an interesting source of compounds with potential anticancer properties.

Stochastic model of transcription initiation of closely spaced promoters in escherichia coli

Dissertação para obtenção do Grau de Mestre em Engenharia Biomédica

Chronic disseminated histoplasmosis with lesions restricted to the mouth: case report

We report a rare case of chronic disseminated histoplasmosis with several ulcerated lesions in the oral cavity in an alcoholic patient without human immunodeficiency virus infection, with no detectable signs and symptoms of systemic disease or extraoral manifestations. Histopathological analysis revealed chronic inflammatory process with granulomas containing Histoplasma-like organisms. The isolation of Histoplasma capsulatum provided the definitive diagnosis. Treatment with itraconazole resulted in complete remission of oral lesions. As far we aware, this is the second case report of oral histoplasmosis in an HIV negative patient described in Brazil.