The resistance of the yeast Saccharomyces cerevisiae to the biocide polyhexamethylene biguanide: involvement of cell wall integrity pathway and emerging role for YAP1

<p>Abstract</p> <p>Background</p> <p>Polyhexamethylene biguanide (PHMB) is an antiseptic polymer that is mainly used for cleaning hospitals and pools and combating <it>Acantamoeba </it>infection. Its fungicide activity was recently shown by its lethal effect on yeasts that contaminate the industrial ethanol process, and on the PE-2 strain of <it>Saccharomyces cerevisiae</it>, one of the main fermenting yeasts in Brazil. This pointed to the need to know the molecular mechanism that lay behind the cell resistance to this compound. In this study, we examined the factors involved in PHMB-cell interaction and the mechanisms that respond to the damage caused by this interaction. To achieve this, two research strategies were employed: the expression of some genes by RT-qPCR and the analysis of mutant strains.</p> <p>Results</p> <p>Cell Wall integrity (CWI) genes were induced in the PHMB-resistant <it>Saccharomyces cerevisiae </it>strain JP-1, although they are poorly expressed in the PHMB-sensitive <it>Saccharomyces cerevisiae </it>PE2 strain. This suggested that PHMB damages the glucan structure on the yeast cell wall. It was also confirmed by the observed sensitivity of the yeast deletion strains, <it>Δslg1, Δrom2, Δmkk2</it>, <it>Δslt2</it>, <it>Δknr4</it>, <it>Δswi4 </it>and <it>Δswi4</it>, which showed that the protein kinase C (PKC) regulatory mechanism is involved in the response and resistance to PHMB. The sensitivity of the <it>Δhog1 </it>mutant was also observed. Furthermore, the cytotoxicity assay and gene expression analysis showed that the part played by <it>YAP1 </it>and <it>CTT1 </it>genes in cell resistance to PHMB is unrelated to oxidative stress response. Thus, we suggested that Yap1p can play a role in cell wall maintenance by controlling the expression of the CWI genes.</p> <p>Conclusion</p> <p>The PHMB treatment of the yeast cells activates the PKC1/Slt2 (CWI) pathway. In addition, it is suggested that HOG1 and YAP1 can play a role in the regulation of CWI genes.</p

Qualidade das sementes de mamona, momento adequado para colheita de cachos e sua influência no valor da produção.

Tese (Doutorado em Recursos Naturais) - Universidade Federal de Campina Grande, Centro de Tecnologia e Recursos Naturais, Campina Grande, PB. Orientador: Clodoaldo Roque Dolajustina Bortoluzi; Orientador: Napoleão Esberard de Macêdo Beltrão - Embrapa Algodão

Principais aspectos da biologia da mosca do sorgo, Contarinia sorghicola (Coquillett, 1898) (Diptera: Cecidomyiidae).

O mosca do sorgo, Contarinia sorghicola (Coquillet, 1898) (Diptera: Cecidomyiidae) constitui um dos serios problemas para o cultivo do sorgo no Brasil. A sua biologia foi estudada no Sorghum bicolor (L.) Moench em ambiente de laboratorio, para as condicoes de Sete Lagoas, MG, sendo repetida em 5 epocas com intervalo de 20 dias. Observou-se o florescimento das paniculas e o controle de oviposicao de mosca. As plantas foram levadas para o laboratorio e mantidas em provetas com agua. Suas espiguetas foram examinadas diariamente para identificacao das fases do inseto. O periodo medio de incubacao foi de 3,00 +/- 0,00 dias, o larval de 8,20 +/- 0,08 dias e o pupal de 3,77 +/- 0,09 dias. A menor mortalidade deu-se na fase de ovo e a maior na fase de larva

Como definir o ponto de colheita da mamona.

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Observations of OJ 287 from the Geodetic VLBI Archive of the Washington Correlator

We present 27 geodetic VLBI maps of OJ 287 obtained from the archive of the Washington correlator. The observations presented here were made between 1990 October and 1996 December. During this period a sequence of six superluminal components has been identified. We measured the proper motion of these components to be approximately 0.5 mas/yr, which is about twice as high as that seen in previous VLBI observations. These results imply a higher component ejection rate than previously observed, in good agreement with the observed occurrences of radio outbursts. We have examined a possible connection between VLBI components and optical flares in the framework of a binary black hole system.Comment: 9 pages, 5 included figures, emulateapj.sty, accepted to The Astrophysical Journa

Productive performance of vernalizated semi-noble garlic cultivars in western Rio Grande do Norte State, Brazil.

Com o presente estudo, objetivou-se o desenvolvimento e a produção de cultivares de alho semi-noble, submetidas a diferentes períodos de vernalização pré-plantio dos bulbos-sementeem dois municípios da Mesorregião Oeste Potiguar

Descrição das fases do desenvolvimento reprodutivo da mamoneira visando ao manejo da colheita.

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