The pleiotropic transcriptional regulator NlpR contributes to the modulation of nitrogen metabolism, lipogenesis and triacylglycerol accumulation in oleaginous rhodococci

The regulatory mechanisms involved in lipogenesis and triacylglycerol (TAG) accumulation are largely unknown in oleaginous rhodococci. In this study a regulatory protein (here called NlpR: Nitrogen lipid Regulator), which contributes to the modulation of nitrogen metabolism, lipogenesis and triacylglycerol accumulation in oleaginous rhodococci was identified. Under nitrogen deprivation conditions, in which TAG accumulation is stimulated, the nlpR gene was significantly upregulated, whereas a significant decrease of its expression and TAG accumulation occurred when cerulenin was added. The nlpR disruption negatively affected the nitrate/nitrite reduction as well as lipid biosynthesis under nitrogen-limiting conditions. In contrast, its overexpression increased TAG production during cultivation of cells in nitrogen-rich media. A putative ‘NlpR-binding motif’ upstream of several genes related to nitrogen and lipid metabolisms was found. The nlpR disruption in RHA1 strain led to a reduced transcription of genes involved in nitrate/nitrite assimilation, as well as in fatty acid and TAG biosynthesis. Purified NlpR was able to bind to narK, nirD, fasI, plsC and atf3 promoter regions. It was suggested that NlpR acts as a pleiotropic transcriptional regulator by activating of nitrate/nitrite assimilation genes and others genes involved in fatty acid and TAG biosynthesis, in response to nitrogen deprivation.Fil: Hernández, Martín Alejandro. Universidad Nacional de la Patagonia "san Juan Bosco". Instituto de Biociencias de la Patagonia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biociencias de la Patagonia; ArgentinaFil: Lara, María Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Gago, Gabriela Marisa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Gramajo, Hugo Cesar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Alvarez, Hector Manuel. Universidad Nacional de la Patagonia "san Juan Bosco". Instituto de Biociencias de la Patagonia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biociencias de la Patagonia; Argentin

Transcriptional regulation of fatty acid biosynthesis in mycobacteria

The main purpose of our study is to understand how mycobacteria exert control over the biosynthesis of their membrane lipids and find out the key components of the regulatory network that control fatty acid biosynthesis at the transcriptional level. In this article we describe the identification and purification of FasR, a transcriptional regulator from Mycobacterium sp. that controls the expression of the fatty acid synthase (fas) and the 4-phosphopantetheinyl transferase (acpS) encoding genes, whose products are involved in the fatty acid and mycolic acid biosynthesis pathways. In vitro studies demonstrated that fas and acpS genes are part of the same transcriptional unit and that FasR specifically binds to three conserved operator sequences present in the fas-acpS promoter region (Pfas). The construction and further characterization of a fasR conditional mutant confirmed that FasR is a transcriptional activator of the fas-acpS operon and that this protein is essential for mycobacteria viability. Furthermore, the combined used of Pfas–lacZ fusions in different fasR backgrounds and electrophoretic mobility shift assays experiments, strongly suggested that long-chain acyl-CoAs are the effector molecules that modulate the affinity of FasR for its DNA binding sequences and therefore the expression of the essential fas-acpS operon.Fil: Gramajo, Hugo Cesar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Mondino, Sonia Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Gago, Gabriela Marisa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Biología Molecular y Celular de Rosario; Argentin

Caracterización de inhibidores de acil-CoA carboxilasas de Mycobacterium tuberculosis: un nuevo blanco para el desarrollo de drogas

La pared celular de M. tuberculosis posee numerosos l¡pidos de estructura compleja que no solo son necesarios para la viabilidad y patogenicidad del microorganismo, sino que son capaces de modular la respuesta inmune del huesped. Entre estos, unos de los mas caracteristicos son los acidos micolicos. Algunas de las drogas antituberculosas mas usadas afectan justamente estas vias biosinteticas. Sin embargo, se conoce muy poco acerca de las vias involucradas en la biosintesis de los precursores de estos lipidos complejos. Nuestra hipotesis de trabajo es que los alfa-carboxi acil-CoAs utilizados para la biosintesis de los acidos grasos de membrana y de la pared celular son producidos por los complejos acil-CoA carboxilasas (ACCasas) presentes en M. tuberculosis. Estas enzimas, cuya estructura es diferente a la de la acetil-CoA carboxilasa de humanos, son un blanco atractivo para el diseño de nuevos agentes anti-micobacterianos especificos. En nuestro laboratorio se han caracterizado dos complejos ACCasa a nivel bioquimico y estructural. La obtencion de las estructuras cristalograficas de las subunidades carboxiltransferasas de estos complejos permitio la busqueda in silico de inhibidores, resultando en la identificacion varios compuestos capaces de inhibir la actividad enzimatica in vitro. Uno de estos compuestos tambien fue capaz de inhibir, a concentraciones micromolares, el crecimiento de diferentes especies de micobacterias, incluyendo cepas mutirresistentes de M. tuberculosis. Nuestros resultados sugieren que su accion antimicobacteriana se debe a la inhibicion de una ACCasa especifica. Por un lado se observo que en presencia del inhibidor disminuye la incorporacion de 1-[14C-acetato], y tambien la biosintesis de acidos grasos y micolicos. Ademas la actividad acetil-CoA carboxilasa es menor en extractos de cultivos tratados con el inhibidor, mientras que la actividad acido graso sintasa no se encuentra afectada. En conjunto, estos datos confirman que los complejos ACCasa podrian proveer una herramienta para el diseño de nuevos compuestos antimicobacterianos especificos.Fil: Kurth, Daniel German. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Gago, Gabriela Marisa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Gramajo, Hugo Cesar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaIV Congreso Argentino de Microbiología GeneralCiudad Autónoma de Buenos AiresArgentinaSociedad Argentina de Microbiología Genera

Investigating Membrane Material Alternatives for Air Revitalization in Space

Recently, NASA’s ultimate goal has been to launch a crewed Mars mission. However, the current system used for carbon dioxide (CO2) removal in air revitalization in the International Space Station (ISS) is not equipped to handle beyond low-earth-orbit missions. The Carbon Dioxide Removal Assembly (CDRA) is a complex system that relies heavily on sorbent materials and faces challenges in reliability, energy efficiency, and material degradation. Although the CDRA has operated well in the ISS for the past two decades, health effects from high CO2 levels are amongst the most common complaints from and challenges for astronauts. Recent developments in membrane technology prove to be a promising alternative to sorbent-based systems for CO2 removal. Maintaining high selectivity for CO2 with a reasonable permeability, at such low partial pressures and in the presence of water, is among the main challenges of using membranes in this application. In this work, we have created a membrane-based model with appropriate conditions to identify the membrane technology for this application. We expect to determine a working range of critical parameters such as permeability, selectivity, and membrane area for successful CO2 separation. We will also be comparing the thermodynamic efficiency of a membrane-based process to that of the CDRA to pin-point areas of improvement

Fenologia intrafloral das flores aéreas de Trifolium polymorphum Poir. (Leguminosae) e suas implicações reprodutivas

Trifolium polymorphum is an amphicarpic species that grows in Uruguay, Argentina, Brazil, Paraguay and Chile. Underground flowers are cleistogamous, obligately autogamous and morphologically highly modified in structure and function. Aerial flowers are chasmogamous, and as mentioned in earlier literature, either allogamous or autogamous. The aim of this study is to identify flower characteristics that facilitate or prevent autogamous or allogamous processes. Floral phenology stages are thus studied in correlation with estimated models of aerial flower development, pollen viability and stigmatic receptivity in three Uruguayan T. polymorphum populations. Flower longevity and development (length, width, and anther-stigma distance), anthesis and anther dehiscence initiation, pollen viability and stigmatic receptivity are the variables correlated with floral phenology. Morphological characteristics of aerial flowers favor autogamy processes - even in pre-anthesis - but phenological characteristics tend to prevent it. The most important reproductive events occurring during flower development, that facilitate autogamous or allogamous processes, are discussed here.Trifolium polymorphum é uma espécie que cresce no Uruguai, Argentina, Brasil, Paraguai e Chile. As flores subterrâneas são cleistógamas, autógamas obrigatórias e altamente modificadas na sua estrutura e funcionalidade. As flores aéreas são casmógamas e foram descritas como alógamas e autógamas. Este trabalho tem como objetivo identificar as características florais que facilitam ou evitam os processos de autogamia ou alogamia. A fenologia floral foi correlacionada com os modelos estimados do desenvolvimento das flores aéreas, a viabilidade do pólen e a receptividade estigmática, em três populações uruguaias de T. polymorphum. As variáveis analisadas foram: longevidade e desenvolvimento da flor (comprimento, largura e distância entre anteras e estigma); momento de início da antese e deiscência das anteras; viabilidade do pólen e receptividade estigmática. As flores aéreas têm características que facilitam processos de autogamia ainda em pré-antese e outras características fenológicas que os evitam. Os eventos reprodutivos importantes que ocorrem durante o desenvolvimento da flor e facilitam processos de autogamia ou alogamia são discutidos neste trabalho.Fil: Speroni, Gabriela. Universidad de la República. Facultad de Agronomía. Departamento de Biología Vegetal; UruguayFil: Izaguirre, Primavera. Universidad de la República. Facultad de Agronomía. Departamento de Biología Vegeta; UruguayFil: Bernardello, Gabriel Luis Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Franco, Jorge Cesar. Universidad de la República. Facultad de Agronomía. Departamento de Biometría; Urugua

Particulate matter concentrations originating from industrial and urban sources: Validation of atmospheric dispersion modeling results

This study presents the analysis of the emission, transport, dispersion, and concentration of particulate matter emitted from a large industrial complex dedicated to the manufacture of cement in the town of Malagueño, province of Córdoba (Argentina), using the USEPA's (Environmental Protection Agency) AERMOD model. The model was applied for 224 industrial and background emission sources (8 stacks, 3 limestone quarries, 13 material storage piles, 18 agricultural fields and 182 paved and unpaved segment roads). The application of the model was validated with Total Suspended Particulate matter (TSP) measured at two monitoring sites, where samples were collected for 62 consecutive days in winter. The maximum TSP values obtained at both monitoring sites (748 and 1100 μg m−3) were well above the suggested WHO guidelines. The results obtained showed the impact of this industrial activity on local particulate matter concentrations, from which unpaved industrial roads and stockpiles were the most influential emission sources, directly affecting two of the closest neighborhoods in the area. Future studies will include the accumulation of heavy metals and Polycyclic Aromatic Hydrocarbons in TSP samples, the environmental risk assessment for exposure of the Malagueño population and the source apportionment of these pollutants.Fil: Abril, Gabriela Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Diez, Sebastián Cesar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Tecnológica Nacional. Facultad Regional Córdoba; ArgentinaFil: Pignata, Maria Luisa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Britch, Javier. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Tecnológica Nacional. Facultad Regional Córdoba; Argentin