A consolidated analysis of the physiologic and molecular responses induced under acid stress in the legume-symbiont model-soil bacterium <i>Sinorhizobium meliloti</i>

Abiotic stresses in general and extracellular acidity in particular disturb and limit nitrogen-fixing symbioses between rhizobia and their host legumes. Except for valuable molecular-biological studies on different rhizobia, no consolidated models have been formulated to describe the central physiologic changes that occur in acid-stressed bacteria. We present here an integrated analysis entailing the main cultural, metabolic, and molecular responses of the model bacterium Sinorhizobium meliloti growing under controlled acid stress in a chemostat. A stepwise extracellular acidification of the culture medium had indicated that S. meliloti stopped growing at ca. pH 6.0-6.1. Under such stress the rhizobia increased the O2 consumption per cell by more than 5-fold. This phenotype, together with an increase in the transcripts for several membrane cytochromes, entails a higher aerobic-respiration rate in the acid-stressed rhizobia. Multivariate analysis of global metabolome data served to unequivocally correlate specific-metabolite profiles with the extracellular pH, showing that at low pH the pentose-phosphate pathway exhibited increases in several transcripts, enzymes, and metabolites. Further analyses should be focused on the time course of the observed changes, its associated intracellular signaling, and on the comparison with the changes that operate during the sub lethal acid-adaptive response (ATR) in rhizobia.Facultad de Ciencias ExactasCentro de Investigación y Desarrollo en Fermentaciones IndustrialesInstituto de Biotecnologia y Biologia Molecula

A consolidated analysis of the physiologic and molecular responses induced under acid stress in the legume-symbiont model-soil bacterium <i>Sinorhizobium meliloti</i>

Abiotic stresses in general and extracellular acidity in particular disturb and limit nitrogen-fixing symbioses between rhizobia and their host legumes. Except for valuable molecular-biological studies on different rhizobia, no consolidated models have been formulated to describe the central physiologic changes that occur in acid-stressed bacteria. We present here an integrated analysis entailing the main cultural, metabolic, and molecular responses of the model bacterium Sinorhizobium meliloti growing under controlled acid stress in a chemostat. A stepwise extracellular acidification of the culture medium had indicated that S. meliloti stopped growing at ca. pH 6.0-6.1. Under such stress the rhizobia increased the O2 consumption per cell by more than 5-fold. This phenotype, together with an increase in the transcripts for several membrane cytochromes, entails a higher aerobic-respiration rate in the acid-stressed rhizobia. Multivariate analysis of global metabolome data served to unequivocally correlate specific-metabolite profiles with the extracellular pH, showing that at low pH the pentose-phosphate pathway exhibited increases in several transcripts, enzymes, and metabolites. Further analyses should be focused on the time course of the observed changes, its associated intracellular signaling, and on the comparison with the changes that operate during the sub lethal acid-adaptive response (ATR) in rhizobia.Facultad de Ciencias ExactasCentro de Investigación y Desarrollo en Fermentaciones IndustrialesInstituto de Biotecnologia y Biologia Molecula

Estructuras de fondo rehundido altomedievales en la Península Ibérica

La presencia de estructuras de fondo rehundido en contextos arqueológicos altomedievales está ampliamente documentada en toda Europa y cuenta con una dilatada historiografía. En la Península Ibérica, asociado a la expansión urbanística, se ha podido detectar un conjunto muy significativo de estas estructuras. Sin embargo, la falta de sistematización y análisis ha llevado a algunos problemas en su detección y documentación, así como a excesos conceptuales y de interpretación. En este trabajo se realiza una recopilación analítica de las evidencias de estructuras de fondo rehundido de época altomedieval presentes en la Península Ibérica mostrando su alta complejidad y diversidad. Basado en un análisis de la evidencia disponible, y frente a las tesis etnicistas que las vinculan a la llegada de grupos alóctonos, se propone una interpretación relacionada con el desarrollo de un modo de producción campesino tras la desarticulación de la economía imperial romana

Contra la Antigüedad Tardía: algunas reflexiones en torno al sistema de poblamiento post-romano en Europa occidental

Since the works by Peter Brown from the 70s of the last century, the concept of «Late Antiquity» has had an exceptional reception within Academy. A project which has produced the development of compelling lines of analysis for the post-Roman period, departing from the slow transformation and continuity in contradistinction with the idea of decline and fall of the Roman Empire. However, the popularity of this concept in a specific academic context has supposed its uncritical, and apparently neutral, use, and thus ignoring the significant theoretical background that its use implies. In this paper I will propose a genealogical analysis for the project of Late Antiquity, with the aim of unraveling the theoretical and methodological implications of the use of this concept. This will be used, in a second part of the paper, and through the analysis of some specific cases on the post-Roman settlement pattern in Western Europe, to show its limitations for tackling the significant changes in the archaeological record of the 5th century. Finally, I will propose an arena of dialogue in which the solid argumentation based on a high-quality empirical base may show the utility, or not, of the use of some historic concepts.Desde los trabajos de Peter Brown publicados en los años 70 del pasado siglo, el concepto de «Antigüedad Tardía» ha tenido una excepcional acogida en la academia. Un proyecto historiográfico que ha implicado el desarrollo de estimulantes líneas de análisis del período post-romano en clave de transformación paulatina y continuidad frente a la idea de la decadencia y caída del Imperio Romano. Sin embargo, el éxito de este concepto ha supuesto su utilización acrítica y aparentemente neutral, obviando en muchas ocasiones la importante carga teórica que implica su empleo. En este trabajo, en primer lugar, se plantea una genealogía del proyecto de la Antigüedad Tardía con el objetivo de desentrañar las implicaciones teóricas y metodológicas del uso de este concepto para, en una segunda parte, y a partir de algunos casos de estudio sobre el poblamiento post-romano en Europa occidental, plantear sus limitaciones a la hora de explicar los importantes cambios que se observan en el registro material de la quinta centuria. Finalmente, se propondrá un espacio de diálogo en el que sea la sólida argumentación sobre bases empíricas de calidad la que, a través del debate, señale la utilidad o no del uso de ciertos conceptos históricos

Contra la Antigüedad Tardía: algunas reflexiones en torno al sistema de poblamiento post-romano en Europa occidental

Since the works by Peter Brown from the 70s of the last century, the concept of «Late Antiquity» has had an exceptional reception within Academy. A project which has produced the development of compelling lines of analysis for the post-Roman period, departing from the slow transformation and continuity in contradistinction with the idea of decline and fall of the Roman Empire. However, the popularity of this concept in a specific academic context has supposed its uncritical, and apparently neutral, use, and thus ignoring the significant theoretical background that its use implies. In this paper I will propose a genealogical analysis for the project of Late Antiquity, with the aim of unraveling the theoretical and methodological implications of the use of this concept. This will be used, in a second part of the paper, and through the analysis of some specific cases on the post-Roman settlement pattern in Western Europe, to show its limitations for tackling the significant changes in the archaeological record of the 5th century. Finally, I will propose an arena of dialogue in which the solid argumentation based on a high-quality empirical base may show the utility, or not, of the use of some historic concepts.Desde los trabajos de Peter Brown publicados en los años 70 del pasado siglo, el concepto de «Antigüedad Tardía» ha tenido una excepcional acogida en la academia. Un proyecto historiográfico que ha implicado el desarrollo de estimulantes líneas de análisis del período post-romano en clave de transformación paulatina y continuidad frente a la idea de la decadencia y caída del Imperio Romano. Sin embargo, el éxito de este concepto ha supuesto su utilización acrítica y aparentemente neutral, obviando en muchas ocasiones la importante carga teórica que implica su empleo. En este trabajo, en primer lugar, se plantea una genealogía del proyecto de la Antigüedad Tardía con el objetivo de desentrañar las implicaciones teóricas y metodológicas del uso de este concepto para, en una segunda parte, y a partir de algunos casos de estudio sobre el poblamiento post-romano en Europa occidental, plantear sus limitaciones a la hora de explicar los importantes cambios que se observan en el registro material de la quinta centuria. Finalmente, se propondrá un espacio de diálogo en el que sea la sólida argumentación sobre bases empíricas de calidad la que, a través del debate, señale la utilidad o no del uso de ciertos conceptos históricos

Mitomycin C in the topical treatment of superficial neoplasms of the bladder.

From January 1982 to October 1987, 100 patients with multifocal superficial bladder cancer received intravesical MMC at the Institute of Urology, University of Padova. Seventy-three patients had papillary multifocal superficial bladder carcinoma (stages Ta-T1): treatment was divided into therapeutic (18 cases), and prophylactic (55 cases). 27 patients had carcinoma in situ. 39 patients affected by neoplasia relapsed to previous intravesical ADM treatment. All patients received 40 mg. intravesical MMC weekly for 8 consecutive weeks, repeating the cycle in cases of relapse. Complete response rates at 12 months was 53%, 50 to 67% for each group, respectively. Recurrence rate was lower compared to that before treatment; progression rate was also lower compared to a group who received only endoscopic treatment. In patients who relapsed with ADM treatment, the percentage of complete response was 69%. We underscore the efficacy of MMC in lowering relapse and progression in multifocal superficial bladder cancer, which represents the best indication for this kind of treatment