Implication of proteases in the respiration dependent inactivation of the lactose permease of E. coli

AbstractThe lactose permease of E. coli becomes irreversibly inactivated during lactose transport under conditions of high respiratory activity. This inactivation is characterized by a decrease in the steady state of lactose accumulation, a decrease in the influx rate of lactose, and a decrease in the transmembrane electrical potential. We report here that inhibitors of serine proteases (phenylmethylsulfonyl fluoride and N-α-P-tosyl-L-lysine chloromethyl ketone) prevent this inactivation, thus implicating proteases in this process

Conocer con otrxs: vivencias durante la construcción colectiva del proyecto de investigación “Arcillas, cerámica y ciencia”

Compartimos en este resumen la experiencia transformativa que con un grupo de colegas mujeres hemos tenido, transitando el proyecto de investigación “Arcillas, cerámica y ciencia”. Este proyecto comenzó a rodar en el año 2018 y el grupo de trabajo (formalizado en un proyecto Mincyt-Córdoba) está conformado por geólogas, químicas y ceramistas. Gestado desde el seno de las ciencias naturales, el proyecto intenta incorporar miradas y prácticas que no son habituales en nuestras disciplinas, acercarnos a otras formas posibles de sentir y pensar nuestro quehacer. La intención de trabajar inter /transdisciplinariamente entre quienes nos entendíamos inicialmente como “el grupo de investigación” dejó en claro que los tiempos no serían los tiempos académicos tradicionales, Surgió la necesidad de acomodarnos a una temporalidad colectiva, muchas veces con la sensación de una temporalidad cíclica o espiralada, y esto fue lo que permitió en primer lugar encontrarnos desde la escucha, la sensibilidad, los deseos. El disparador original del proyecto fue el de recopilar prácticas y tecnologías de ceramistas de Córdoba y caracterizar las acumulaciones de arcilla utilizadas actualmente con destino cerámico-alfarero y potencialmente utilizadas en el pasado para confección de piezas arqueológicas. Esta intención original fue transmutando en la medida en que deseos e inquietudes se iban encontrando, pero también se transformó a partir de los encuentros en territorio con ceramistas de Córdoba que trabajan con arcillas locales. El proyecto inicial se convirtió en un disparador de nuevos proyectos colectivos. Comenzamos pensando en estos ceramistas, sus técnicas y producciones como objeto de investigación, considerándolos como centrales productores del conocimiento. Lo que compartimos aquí es parte de lo vivido/gestado a partir de encuentros con Atilio y Mariana López, familia de alfareros tradicionales de Traslasierra, y con el Círculo de Alfareros de la Comunidad Camichingón Tulián en San Marcos Sierras, ambos en la provincia de Córdoba.Facultad de Informátic

Glycolytic and Non-glycolytic Functions of Mycobacterium tuberculosis Fructose-1,6-bisphosphate Aldolase, an Essential Enzyme Produced by Replicating and Non-replicating Bacilli

The search for antituberculosis drugs active against persistent bacilli has led to our interest in metallodependent class II fructose- 1,6-bisphosphate aldolase (FBA-tb), a key enzyme of gluconeogenesis absent from mammalian cells. Knock-out experiments at the fba-tb locus indicated that this gene is required for the growth of Mycobacterium tuberculosis on gluconeogenetic substrates and in glucose-containing medium. Surface labeling and enzymatic activity measurements revealed that this enzyme was exported to the cell surface of M. tuberculosis and produced under various axenic growth conditions including oxygen depletion and hence by non-replicating bacilli. Importantly, FBA-tb was also produced in vivo in the lungs of infected guinea pigs and mice. FBA-tb bound human plasmin(ogen) and protected FBA-tb-bound plasmin from regulation by α 2-antiplasmin, suggestive of an involvement of this enzyme in host/pathogen interactions. The crystal structures of FBA-tb in the native form and in complex with a hydroxamate substrate analog were determined to 2.35- and 1.9-Å resolution, respectively. Whereas inhibitor attachment had no effect on the plasminogen binding activity of FBA-tb, it competed with the natural substrate of the enzyme, fructose 1,6-bisphosphate, and substantiated a previously unknown reaction mechanism associated with metallodependent aldolases involving recruitment of the catalytic zinc ion by the substrate upon active site binding. Altogether, our results highlight the potential of FBA-tb as a novel therapeutic target against both replicating and non-replicating bacilli.Fil: Santangelo, María de la Paz. State University of Colorado - Fort Collins; Estados Unidos. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Biotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gest, Petra M.. State University of Colorado - Fort Collins; Estados UnidosFil: Guerin, Marcelo E.. Universidad del País Vasco; EspañaFil: Coinçon, Mathieu. University of Montreal; CanadáFil: Pham, Ha. State University of Colorado - Fort Collins; Estados UnidosFil: Ryan, Gavin. State University of Colorado - Fort Collins; Estados UnidosFil: Puckett, Susan E.. Cornell University; Estados UnidosFil: Spencer, John S.. State University of Colorado - Fort Collins; Estados UnidosFil: Gonzalez Juarrero, Mercedes. State University of Colorado - Fort Collins; Estados UnidosFil: Daher, Racha. Universite de Paris XI. Institut de Chimie Moléculaire et des Matériaux d'Orsay; FranciaFil: Lenaerts, Anne J.. State University of Colorado - Fort Collins; Estados UnidosFil: Schnappinger, Dirk. Cornell University; Estados UnidosFil: Therisod, Michel. Universite de Paris XI. Institut de Chimie Moléculaire et des Matériaux d'Orsay; FranciaFil: Ehrt, Sabine. Cornell University; Estados UnidosFil: Sygusch, Jurgen. University of Montreal; CanadáFil: Jackson, Mary. State University of Colorado - Fort Collins; Estados Unido

Riesgo Climático de la Región Pampeana respecto a la liberación de ascosporas de Diaporthe helianthi

El cancro del tallo del girasol fue identificado por primera vez en la Ex Yugoslavia en 1980 (Mihaljcevic et al 1980). Actualmente se encuentra distribuido en forma amplia a nivel mundial en Serbia, Francia, Rumania, Estados Unidos, Canadá, Argentina, Australia, entre otros. A nivel mundial, en regiones endémicas, se registra entre 40 al 80 % de plantas afectadas, las cuales presentan pérdidas en rendimiento y calidad (Marisevich et al 2016). Las estimaciones de daño realizadas sobre cultivares susceptibles en el noreste de La Pampa, Argentina, en plantas enfermas apareadas con plantas sanas, registran pérdida del 45 % del rendimiento de aquenios y del 4 - 15 % del contenido de materia grasa (Ghironi E et al 2018). Estos valores de referencia de daño deben ser asociados a la evaluación de incidencia de cancros en tallos para la estimación de las pérdidas a nivel de campo.AER INTA General PicoFil: Corro Molas, Andres. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Anguil. Agencia de Extensión Rural General Pico; ArgentinaFil: Edwards Molina, Juan Pablo. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Patología Vegetal; ArgentinaFil: Therisod, Gaston. Asesor CREA. Región Mar y Sierras, Sudeste; ArgentinaFil: Colombo, Denis Nahuel. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Anguil; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Martinez, Malvina Irene. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Clima y Agua; ArgentinaFil: Bilbao, Agustín. Asesor privado; ArgentinaFil: Bertero, Amelia. Asesor privado; ArgentinaFil: Moschini, Ricardo. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Clima y Agua; Argentin

Enzymatic glyceride synthesis in a foam reactor

We report the results of our study on Rhizomucor miehei lipaseâ catalyzed lauric acidâ glycerol esterification in a foam reactor. A satisfactory yield of glyceride synthesis can be achieved with an unusually high initial water content (50% w/w). We found that product formation could be regulated by controlling foaming. Foaming was a function of the air flow rate, reaction temperature, pH value, ionic strength, and substrate molar ratio. Monolaurin and dilaurin, which constituted nearly 80% of the total yield, were the two dominant products in this reaction; trilaurin was also formed at the initial stages of the reaction. A study of pH and ionic strength effects on an independent basis revealed that they affect the interfacial mechanism in different manners. On varying the ratio of lauric acid and glycerol, only a slight change in the degree of conversion was detected and the consumption rate of fatty acid was approximately the same.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141443/1/aocs0643.pd

Resonant optical trapping in hollow photonic crystal cavities and its potential use for bacterial characterisation

During the last decade, the development of optofluidic chips has become a large field of research. The integration of nano and microstructures with microfluidics layers allowed for the miniaturisation of a number of tools traditionally used in laboratories and optofluidic systems found their main applications in lab-on-a-chip and sensing platforms. At the same time, optical tweezers have become the tool of choice for the trapping and the manipulation of nano and micrometer-sized objects, that can be inert (dielectric or metallic particles) or biological (proteins, bacteria, viruses,...). In this context, nanostructures are the ideal candidate for tweezers miniaturisation, thanks to their ability to strongly confine light in small volumes and hence to generate intense gradient forces. This work reports on the fabrication of an optofluidic chip based on a two-dimensional photonic crystal cavity and on its use in particle and bacteria differentiation. The cavity has a hollow design that maximises the overlap between the confined field and the trapped objects and it supports Self-Induced Back-Action effects that allow for reducing the trapping power (down to few microwatts) and to simultaneously acquire information of the trapped specimen. The system is excited in an end-fire setup and the detection is carried out by recording the light intensity transmitted through the photonic crystal. The fabrication process, that is entirely carried out in the Institue of Physics and in the Center of MicroNanoTechnology cleanrooms, is first detailed. For the cavity design normally used, typical quality factors of 10000 were obtained. Moreover, SU8 mode adaptors were developed to increase the coupling with lensed fibers and a microfluidic membrane presenting two injection channels is proposed for rapid switch between liquids. The trapping and the differentiation of 250 and 500 nm polystyrene is then presented. The differentiation can be achieved qualitatively by direct observation of the transmitted intensity records and quantitatively by the use of histograms and of statistical moments. Finally, the trapping of seven species of living bacteria is shown and their Gram-type is determined by the analysis of the induced transmission increase. This ability to probe the cell wall of bacteria in a fast, label-free and non-destructive way paves the way for applications in biological and biomedical environments