http://hdl.handle.net/10400.22/8 Sat, 13 Oct 2018 12:44:02 GMT 2018-10-13T12:44:02Z http://hdl.handle.net/10400.22/7600 Título: Role of the DHH1 Gene in the Regulation of Monocarboxylic Acids Transporters Expression in Saccharomyces cerevisiae Autor: Mota, Sandra; Vieira, Neide; Barbosa, Sónia; Delaveau, Thierry; Torchet, Claire; Saux, Agnès Le; Garcia, Mathilde; Pereira, Ana; Lemoine, Sophie; Coulpier, Fanny; Darzacq, Xavier; Benard, Lionel; Casal, Margarida; Devaux, Frédéric; Paiva, Sandra Resumo: Previous experiments revealed that DHH1, a RNA helicase involved in the regulation of mRNA stability and translation, complemented the phenotype of a Saccharomyces cerevisiae mutant affected in the expression of genes coding for monocarboxylic-acids transporters, JEN1 and ADY2 (Paiva S, Althoff S, Casal M, Leao C. FEMS Microbiol Lett, 1999, 170∶301–306). In wild type cells, JEN1 expression had been shown to be undetectable in the presence of glucose or formic acid, and induced in the presence of lactate. In this work, we show that JEN1 mRNA accumulates in a dhh1 mutant, when formic acid was used as sole carbon source. Dhh1 interacts with the decapping activator Dcp1 and with the deadenylase complex. This led to the hypothesis that JEN1 expression is post-transcriptionally regulated by Dhh1 in formic acid. Analyses of JEN1 mRNAs decay in wild-type and dhh1 mutant strains confirmed this hypothesis. In these conditions, the stabilized JEN1 mRNA was associated to polysomes but no Jen1 protein could be detected, either by measurable lactate carrier activity, Jen1-GFP fluorescence detection or western blots. These results revealed the complexity of the expression regulation of JEN1 in S. cerevisiae and evidenced the importance of DHH1 in this process. Additionally, microarray analyses of dhh1 mutant indicated that Dhh1 plays a large role in metabolic adaptation, suggesting that carbon source changes triggers a complex interplay between transcriptional and post-transcriptional effects. Wed, 01 Jan 2014 00:00:00 GMT http://hdl.handle.net/10400.22/7600 2014-01-01T00:00:00Z http://hdl.handle.net/10400.22/7443 Título: Candida glabrata susceptibility to antifungals and phagocytosis is modulated by acetate Autor: Mota, Sandra; Alves, Rosana; Carneiro, Catarina; Silva, Sónia; Brown, Alistair J.; Istel, Fabian; Kuchler, Karl; Sampaio, Paula; Casal, Margarida; Henriques, Mariana; Paiva, Sandra Resumo: Candida glabrata is considered a major opportunistic fungal pathogen of humans. The capacity of this yeast species to cause infections is dependent on the ability to grow within the human host environment and to assimilate the carbon sources available. Previous studies have suggested that C. albicans can encounter glucose-poor microenvironments during infection and that the ability to use alternative non-fermentable carbon sources, such as carboxylic acids, contributes to the virulence of this fungus. Transcriptional studies on C. glabrata cells identified a similar response, upon nutrient deprivation. In this work, we aimed at analyzing biofilm formation, antifungal drug resistance, and phagocytosis of C. glabrata cells grown in the presence of acetic acid as an alternative carbon source. C. glabrata planktonic cells grown in media containing acetic acid were more susceptible to fluconazole and were better phagocytosed and killed by macrophages than when compared to media lacking acetic acid. Growth in acetic acid also affected the ability of C. glabrata to form biofilms. The genes ADY2a, ADY2b, FPS1, FPS2, and ATO3, encoding putative carboxylate transporters, were upregulated in C. glabrata planktonic and biofilm cells in the presence of acetic acid. Phagocytosis assays with fps1 and ady2a mutant strains suggested a potential role of FPS1 and ADY2a in the phagocytosis process. These results highlight how acidic pH niches, associated with the presence of acetic acid, can impact in the treatment of C. glabrata infections, in particular in vaginal candidiasis. Thu, 01 Jan 2015 00:00:00 GMT http://hdl.handle.net/10400.22/7443 2015-01-01T00:00:00Z http://hdl.handle.net/10400.22/6174 Título: The transport of carboxylic acids and important role of the Jen1p transporter during the development of yeast colonies Autor: Paiva, Sandra; Strachotová, Dita; Kucerová, Helena; Hlavácek, Otakar; Mota, Sandra; Casal, Margarida; Palkova, Zdena; Váchová, Libuse Resumo: On solid substrates, yeast colonies pass through distinct developmental phases characterized by the changes in pH of their surroundings from acidic to nearly alkaline and vice versa. At the beginning of the alkali phase colonies start to produce ammonia, which functions as a quorum-sensing molecule inducing the reprogramming of cell metabolism. Such reprogramming includes, among others, the activation of several plasma membrane transporters and is connected with colony differentiation. In the present study, we show that colony cells can use two transport mechanisms to import lactic acid: a ‘saturable’ component of the transport, which requires the presence of a functional Jen1p transporter, and a ‘non-saturable’ component (diffusion) that is independent of Jen1p. During colony development, the efficiency of both transport components changes similarly in central and outer colonial cells. Although the lactate uptake capacity of central cells gradually decreases during colony development, the lactate uptake capacity of outer cells peaks during the alkali phase and is also kept relatively high in the second acidic phase. This lactate uptake profile correlates with the localization of the Jen1p transporter to the plasma membrane of colony cells. Both lactic acid uptake mechanisms are diminished in sok2 colonies where JEN1 expression is decreased. The Sok2p transcription factor may therefore be involved in the regulation of non-saturable lactic acid uptake in yeast colonies. Tue, 01 Jan 2013 00:00:00 GMT http://hdl.handle.net/10400.22/6174 2013-01-01T00:00:00Z http://hdl.handle.net/10400.22/1355 Título: Caracterização microbiológica de águas utilizadas em hemodiálise Autor: Pinheiro, C.; Araújo, André; Amorim, Maria Manuela; Moreira, Anabela; Condeço, Jorge Resumo: A insuficiência renal crónica tem como possível tratamento a hemodiálise de alto-fluxo de hemodiafiltração. Este estudo tem por objectivo caracterizar a qualidade de águas de diálise, provenientes de 4 clínicas. Realizou-se um estudo observacional descritivo transversal com base nos resultados das análises de águas de diálise, de 07-2009 a 04-2010. Nas amostras, à entrada do tratamento, verificou-se que 100% destas se encontravam nãoconformes nos parâmetros microbiológicos e 53,85% apresentavam-se não-conformes nos parâmetros químicos. Após tratamento, 6,41% continuavam não-conformes nos parâmetros microbiológicos e todas as amostras apresentaram-se conformes nos parâmetros químicos. Conclui-se que o tratamento tem elevado grau de efectividade.; Chronic kidney disease has as possible treatment the high-flux hemodialysis hemodiafiltration. To characterize the quality of dialysis water, from four clinics, were analyzed the results of dialysis water analysis, from 07-2009 to 04-2010. Before treatment, it was found that 100% of the samples were non-conforming in microbiological parameters and 53.85% presented non-conformity in chemical parameters. After treatment, 6.41% of the samples were non-conforming in the microbiological parameters and all samples presented conformity regarding chemical parameters. The water treatment presents a high degree of effectiveness. Fri, 01 Jan 2010 00:00:00 GMT http://hdl.handle.net/10400.22/1355 2010-01-01T00:00:00Z http://hdl.handle.net/10400.22/1354 Título: Comparação entre os valores de Procalcitonina e Proteína C reactiva em adultos com doença hemato-oncológica Autor: Cardoso, A.; Gonçalves, N.; Moreira, Anabela; Neves, Fabiana; Amorim, Maria Manuela Resumo: Os pacientes com doença hemato-oncológica submetidos a quimioterapia possuem maior propensão para infecções bacterianas. O seu diagnóstico pode ser efectuado recorrendo-se aos marcadores biológicos: procalcitonina (PCT) e proteína C reactiva (PCR). Neste estudo, observaram-se diferenças estatisticamente significativas na concentração de PCT nos diferentes grupos de infecção, o que não se verificou na concentração de PCR. Observou-se ainda uma fraca correlação entre estes marcadores nos grupos de infecção. Apenas os valores de PCT estão directamente relacionados com a gravidade da infecção, evidenciando-o como um bom marcador de diagnóstico, mais eficaz do que a PCR.; Patients with hemato-oncological disease undergoing chemotherapy have a higher susceptibility for bacterial infections. The infection’s diagnosis can be performed by resorting to the use of biological markers: procalcitonin (PCT) and C-reactive protein (CRP). In this study, we observed statistically significant differences in the concentration of PCT between the different groups of infection, which were not observed in CRP concentration. There was also a weak correlation between these markers of infection in these groups. Only PCT values are directly related with the severity of infection, making it a good marker for its diagnosis, more effective than the CRP. Fri, 01 Jan 2010 00:00:00 GMT http://hdl.handle.net/10400.22/1354 2010-01-01T00:00:00Z