Growth-phase regulation of lipopolysaccharide O-antigen chain length influences serum resistance in serovars of Salmonella

The amount of lipopolysaccharide (LPS) O antigen (OAg) and its chain length distribution are important factors that protect bacteria from serum complement. Salmonella enterica serovar Typhi produces LPS with long chain length distribution (L-OAg) controlled by the wzz gene, whereas serovar Typhimurium produces LPS with two OAg chain lengths: an L-OAg controlled by Wzz(ST) and a very long (VL) OAg determined by Wzz(fepE). This study shows that serovar Enteritidis also has a bimodal OAg distribution with two preferred OAg chain lengths similar to serovar Typhimurium. It was reported previously that OAg production by S. Typhi increases at the late exponential and stationary phases of growth. The results of this study demonstrate that increased amounts of L-OAg produced by S. Typhi grown to stationary phase confer higher levels of bacterial resistance to human serum. Production of OAg by serovars Typhimurium and Enteritidis was also under growth-phase-dependent regulation; however, while the total amount of OAg increased during growth, the VL-OAg distribution remained constant. The VL-OAg distribution was primarily responsible for complement resistance, protecting the non-typhoidal serovars from the lytic action of serum irrespective of the growth phase. As a result, the non-typhoidal species were significantly more resistant than S. Typhi to human serum. When S. Typhi was transformed with a multicopy plasmid containing the S. Typhimurium wzz(fepE) gene, resistance to serum increased to levels comparable to the non-typhoidal serovars. In contrast to the relevant role for high-molecular-mass OAg molecules, the presence of Vi antigen did not contribute to serum resistance of clinical isolates of serovar Typhi.

O-antigen modal chain length in Shigella flexneri 2a is growth-regulated through RfaH-mediated transcriptional control of the wzy gene

Shigella flexneri 2a 2457T produces lipopolysaccharide (LPS) with two O-antigen (OAg) chain lengths: a short (S-OAg) controlled by WzzB and a very long (VL-OAg) determined by Wzz(pHS-2). This study demonstrates that the synthesis and length distribution of the S. flexneri OAg are under growth-phase-dependent regulation. Quantitative electrophoretic analysis showed that the VL-OAg increased during growth while the S-OAg distribution remained constant. Increased production of VL-OAg correlated with the growth-phase-regulated expression of the transcription elongation factor RfaH, and was severely impaired in a DeltarfaH mutant, which synthesized only low-molecular-mass OAg molecules and a small amount of S-OAg. Real-time RT-PCR revealed a drastic reduction of wzy polymerase gene expression in the DeltarfaH mutant. Complementation of this mutant with the wzy gene cloned into a high-copy-number plasmid restored the bimodal OAg distribution, suggesting that cellular levels of Wzy influence not only OAg polymerization but also chain-length distribution. Accordingly, overexpression of wzy in the wild-type strain resulted in production of a large amount of high-molecular-mass OAg molecules. An increased dosage of either wzzB or wzz(pHS-2) also altered OAg chain-length distribution. Transcription of wzzB and wzz(pHS-2) genes was regulated during bacterial growth but in an RfaH-independent manner. Overall, these findings indicate that expression of the wzy, wzzB and wzz(pHS-2) genes is finely regulated to determine an appropriate balance between the proteins responsible for polymerization and chain-length distribution of S. flexneri OAg.

Evangélicos en América Latina

Considerada tradicionalmente "el continente católico" por excelencia, Latinoamérica siempre ha contado con una presencia minoritaria protestante, y en los últimos treinta años, a pesar de llegar a concentrar en su territorio a la mitad de los católicos del mundo, ha visto una acelerada diversificación del universo religioso, con una proliferación impresionante de denominaciones y grupos, cuya mayorÍa se declara "evangélica". Este proceso, con frecuencia descrito con expresión simplista "invasión de las sectas", se muestra complejo en sus características y articulado en su composición. Frente a tal crecimiento numérico, que en el año 2000 deberÍa involucrar al 20% de la población del continente, la Iglesia Católica parece oscilar entre la crÍtica al papel "alienante" de estos movimientos y la adopción de sus formas culturales celebrativas y espiritualizantes. Además, desde la mitad de los años 80, luego -y acaso como consecuencia- de tal expansión, los evangélicos empezaron a afirmar una inédita presencia polÍtica, culminada en l991 con la obtención en Guatemala del máximo cargo del Estado por parte de Jorge Serrano, primer presidente evangélico elegido en Latinoamérica. Contando con un sólido arraigo popular, los partidos y políticos evangélicos ya están difundidos en todos los paÍses, con un papel que alterna el conservadorismo milenarista, el corporativismo confesional y la concientización liberadora. Con este número especial, SIAL pretende principalmente ofrecer algunos materiales para un mejor conocimiento de este dinámico y complejo fenómeno religioso y social.

Duas poéticas individuais: a metaficção em Finisterra, de Carlos de Oliveira e em o Triunfo da Morte de Augusto Abelaira

Dissertação de mestrado, Literatura, Faculdade de Ciências Humanas e Sociais, Universidade do Algarve, 2005

Domesticated domesticated! Some comments on the translation into English of José Carlos Somoza's La Caverna de las ideas

In order to cater for an extended readership, crime fiction, like most popular genres, is based on the repetition of a formula allowing for the reader's immediate identification. This first domestication is followed, at the time of its translation, by a second process, which wipes out those characteristics of the source text that may come into conflict with the dominant values of the target culture. An analysis of the textual and paratextual strategies used in the English translation of José Carlos Somoza's La caverna de las ideas (2000) shows the efforts to make the novel more easily marketable in the English-speaking world through the elimination of most of the obstacles to easy readability.

Relatório de Estágio na Teodolito de Carlos da Veiga Ferreira

O presente trabalho académico é o relato das principais actividades que desenvolvi como estagiário na editora Teodolito, criada em 2011 por Carlos da Veiga Ferreira. Foi uma campanha inesquecível que começou com uma entrevista que fiz ao editor e continuou depois com a minha visita à Feira do Livro de Frankfurt, pela mão do editor. De regresso a Portugal, pude ler e elaborar recensões de originais, analisar contratos de direitos de autor, participar nos lançamentos da editora e, em conjunto com Carlos da Veiga Ferreira, tratar da comunicação estabelecida entre a editora e outros elementos ligados ao sector do livro

Reliure de : El Desafio de los reyes de Francia y d'Inglaterra al emperador y rey ñro señor (Carlos V) , con sus respuestas

Numérisation partielle de reliure

[Télégramme d'Albert Alvarez à Colleuille, Arcachon, 21 août 1907]

Demande le répertoire et la date de la rentrée