Production of recombinant proteins in E. coli by the heat inducible expression system based on the phage lambda pL and/or pR promoters

The temperature inducible expression system, based on the pL and/or pR phage lambda promoters regulated by the thermolabile cI857 repressor has been widely use to produce recombinant proteins in prokariotic cells. In this expression system, induction of heterologous protein is achieved by increasing the culture temperature, generally above 37°C. Concomitant to the overexpression of heterologous protein, the increase in temperature also causes a variety of complex stress responses. Many studies have reported the use of such temperature inducible expression system, however only few discuss the simultaneous stress effects caused by recombinant protein production and the up-shift in temperature. Understanding the integral effect of such responses should be useful to develop improved strategies for high yield protein production and recovery. Here, we describe the current status of the heat inducible expression system based on the pL and/or pR λ phage promoters, focusing on recent developments on expression vehicles, the stress responses at the molecular and physiological level that occur after heat induction, and bioprocessing factors that affect protein overexpression, including culture operation variables and induction strategies

Modelong and analysis rheology of polymers for application in technologies "self-crimping" and its adaptation to the practices of Polymer Materials Engineering

[EN] Polymers are manufactured in molted state, so the rheological properties are mandatory in order to analyzeand evaluate its processability. The prediction of the viscoelastic response of a material and the simulationof the behavior of the same when it is processed is achieved with the application of the rheological models.In the preparation by extrusion of bicomponent polymer bers with self-crimping e ect it is essentialthat the two components have the same viscosity at the nozzle outlet. In order to obtain such viscosityeach component must be extruded at a di erent temperature maintaining all other processing conditionsunchanged. Using Cross-WLF rheological modelization is it feasible to determine the temperatures for twopolymeric materials in order to obtain the same melt viscosity. In the current work a practical session hasbeen proposed for students of Materials Engineering. Using a capillary rheometer, the students should beable to determine the rheological behavior of two thermoplastic polymers. After adjusting the behavior ofthe polymers to Cross-WLF model and using the proposed model the students should be able to determinethe temperatures in which both polymers have the same viscosity.[ES] El procesado de los polímeros se realiza en estado fundido, por lo que es necesario realizar un análisis de las propiedades reológicas de estos materiales para poder evaluar su procesabilidad. Los modelos reológicos de los polímeros, como el modelo de Cross-WLF, posibilitan predecir la respuesta viscoelástica de un material y simular el comportamiento del mismo cuando va a ser procesado. En la elaboración mediante extrusión de fibras poliméricas bicomponente con efecto “self-crimping” (auto-rizado) es básico que los dos componentes presenten la misma viscosidad a la salida de la boquilla. Para ello, manteniendo el resto de condiciones de procesado de cada polímero idénticas, cada componente se debe extruir a una temperatura diferente. Gracias a la modelización reológica de Cross-WLF se pueden determinar las parejas de temperaturas dónde los materiales modelizados presentan la misma viscosidad. En el presente trabajo se plantea una sesión práctica para los alumnos de Ingeniería de Materiales Poliméricos. Con ayuda de un reómetro capilar los alumnos deberán ser capaces de determinar el comportamiento reológico de dos polímeros termoplásticos. Después ajustar dicho comportamiento al modelo de Cross-WLF y con ayuda de este modelo determinar las parejas de temperaturas dónde ambos polímeros estudiados presentan la misma viscosidad.Montañés Muñoz, N.; Sánchez Nacher, L.; Reig Pérez, MJ.; Fenollar Gimeno, OÁ.; Boronat Vitoria, T. (2017). Análisis y modelizado reológico de polímeros para su aplicación con tecnologías “auto-rizado” y su adaptación a las prácticas de Ingeniería de Materiales Poliméricos. Modelling in Science Education and Learning. 10(1):243-252. doi:10.4995/msel.2017.6598SWORD243252101Sandoval E. R., Quintero A. F., Aponte A. A. (2005). Modelos reológicos aplicados a masas de trigo y maíz. Ingeniería e Investigación, 25(2), 87-93.Cross, M. M. (1965). Rheology of non-Newtonian fluids: A new flow equation for pseudoplastic systems. Journal of Colloid Science, 20(5), 417-437. doi:10.1016/0095-8522(65)90022-xBagley, E. B. (1957). End Corrections in the Capillary Flow of Polyethylene. Journal of Applied Physics, 28(5), 624-627. doi:10.1063/1.1722814Rabinowitsch B. (1955). Uber die Viskosität, Elastizität von Solen. Z. Physik Chem. A 145, 1-26.Williams, M. L., Landel, R. F., & Ferry, J. D. (1955). The Temperature Dependence of Relaxation Mechanisms in Amorphous Polymers and Other Glass-forming Liquids. Journal of the American Chemical Society, 77(14), 3701-3707. doi:10.1021/ja01619a008Reig, M. J., Segui, V. J., Ferrandiz, S., & Zamanillo, J. D. (2007). AN EVALUATION OF PROCESSABILITY BY INJECTION MOLDING OF ABS/PC BLENDS OBTAINED FROM RECYCLED MATERIALS. Journal of Polymer Engineering, 27(1). doi:10.1515/polyeng.2007.27.1.29Reig, M. J., Segui, V. J., & Zamanillo, J. D. (2005). Rheological Behavior Modeling of Recycled ABS/PC Blends Applied to Injection Molding Process. Journal of Polymer Engineering, 25(5). doi:10.1515/polyeng.2005.25.5.435Ferrándiz, S., Arrieta, M., López, J., & Navarro, R. (2013). Demostració pràctica de la validesa dels models matemàtics en elements finits. Aplicació al model de Cross. Modelling in Science Education and Learning, 6, 67. doi:10.4995/msel.2013.198

Non-Frankia Actinomycetes Isolated from Surface-Sterilized Roots of Casuarina equisetifolia Fix Nitrogen

Based on partial 16S sequences, we previously described a novel group of nonsymbiotic, acetylene reduction activity-positive actinomycetes which were isolated from surface-sterilized roots of Casuarina equisetifolia growing in Mexico. An amplified rRNA restriction analysis confirmed that these actinomycetes are distinct from Frankia, a finding substantiated by a 16S rRNA gene phylogenetic analysis of two of the Mexican isolates. Further support for these actinomycetes being separate from Frankia comes from the very low DNA-DNA homology that was found. Nevertheless, the Mexican isolates may be diazotrophs based not only on their ability to grow in N-free medium and reduce acetylene to ethylene but also on the results from (15)N isotope dilution analysis and the finding that a nifH gene was PCR amplified. A comparison of the nifH sequences from the various isolates showed that they are closely related to nifH from Frankia; the similarity was 84 to 98% depending on the host specificity group. An analysis of complete 16S rRNA gene sequences demonstrated that the two strains analyzed in detail are most closely related to actinobacteria in the Thermomonosporaceae and the Micromonosporaceae

PHYSIOLOGICAL DIVERSITY AND CHARACTERIZATION OF BENTHIC MICROAEROBIC BACTERIA

Fatty acid methyl esters (FAME) of prokaryote cell membranes have been scarcely studied in free-living bacterial communities from aquatic ecosystem sediments. There is even less information on the microaerobic bacterial communities from suboxic areas of sediments or stratified water bodies. This paper reports the phenotypical and molecular diversity of FAME of 15 benthic microaerobic bacterial strains isolated from three Mexican aquatic ecosystems. A FAME profile analysis, amplification of segment 16S rDNA and physiological assays at different pO2 were performed. Two of the strains exhibited strict microaerobic metabolism and the other 13 had facultative microaerobic metabolism. The species identified were Caulobacter sp., Ochrobactrum anthropi, Sphingobium sp., Bacillus firmus, Bacillus sp., Pseudomonas stutzeri and Sphingomonas sp. Four fatty acids were characteristic of lagoon sediment strains (C20:4n6, C22:6n3 and C23:0) while three were of marine origin (C22:0, C22:1n9 and C24:0). Some are characteristic of one genus or species: C22:6n3 for Ochrobactrum anthropic; C6:0 for Caulobacter sp.; and C22:0 for Sphingobium sp. and Sphingobium amiense

La pospandemia y políticas públicas para enfrentarla

Este libro tiene el objetivo de analizar las alternativas de política pública necesarias para la preservación de la salud de la población, la reactivación de la economía y la definición de un marco institucional que facilite las relaciones entre individuos en un contexto pospandémico, mediante un enfoque multidimensional. En ese sentido, se analizan los antecedentes de las pandemias de carácter universal, el rol de las organizaciones internacionales, el papel de los bienes públicos globales, los modelos de gobernanza global desde un contexto glocal, las tendencias en investigación acerca de pandemias y sostenibilidad, los nuevos retos del Estado, el financiamiento de las pequeñas y medianas empresas, los incentivos fiscales a la innovación en inteligencia artificial y la utilidad de los modelos matemáticos para la toma de decisiones de política pública. De esta manera, se presenta un análisis ordenado de los retos que enfrenta la sociedad en la actualidad, con su explicación y atención mediante alter-nativas de acción pública. Por lo tanto, es una guía sobre el rol y la capacidad que deben desarrollar coordinadamente los funcionarios nacionales, junto a las organizaciones internacionales, para influir la definición de políticas que reorganicen el equilibrio mundial.The aim of this book is to analyze, through a multidimensional approach, the public policy alternatives necessary for the preservation of the health of the population, the reactivation of the economy, and the definition of the institutional framework that facilitates relations between individuals in a post-pandemic context. To this end, we analyze the background of universal pandemics, the role of international orga-nizations, the role of global public goods, global governance models from a glo-cal context, trends in research on pandemics and sustainability, the new challenges of the State: Sovereignty and network, the financing of small and medium-sized en-terprises, tax incentives for innovation in artificial intelligence, and the usefulness of mathematical models for public policy decision-making. In this way, it presents an or-ganized conceptual analysis of the health, economic, political and social challenges currently facing society, with their explanation and attention through alternatives for public action. Therefore, it is a guide on the role and capacity that national officials, together with international organizations, should develop in a coordinated manner to influence the definition of policies that reorganize the global balance.https://scienti.minciencias.gov.co/cvlac/visualizador/generarCurriculoCv.do?cod_rh=0001753768https://orcid.org/0000-0003-3660-8299https://scienti.minciencias.gov.co/gruplac/jsp/visualiza/visualizagr.jsp?nro=00000000003164alberto.hurtadob@campusucc.edu.cohttps://scholar.google.es/citations?user=AxB_pYkAAAAJ&hl=e

A regional PECS node built from place-based social-ecological sustainability research in Latin America and the Caribbean

Sustainability requires a combination of meaningful co-production of locally relevant solutions, synthesis of insights gained across regions, and increased cooperation between science, policy and practice. The Programme for Ecosystem Change and Society (PECS) has been coordinating Place-Based Social-Ecological Sustainability Research (PBSESR) across the globe and emphasizes the need for regional scientific nodes from diverse biocultural regions to inform sustainability science and action. In this paper, we assess the strengths of the PBSESR communities in Latin America and the Caribbean (LAC). We provide an overview of PBSESR literature associated with this region and highlight the achievements of two prominent regional networks: The Social-Ecological Systems and Sustainability Research Network from Mexico (SocioEcoS) and the South American Institute for Resilience and Sustainability Studies from Uruguay (SARAS Institute). Finally, we identify the potential in these nodes to constitute a regional PECS node in Latin America and discuss the capacity needed to ensure such function. The results of the literature review show that while still loosely interconnected across the region, networks play key roles in connecting otherwise cloistered teams and we illustrate how the SocioEcoS network (focusing on transdisciplinary co-production of knowledge towards sustainability) and the SARAS Institute (focusing on innovative approaches for looking at complex social-ecological problems, rooted in slow science and arts) operate as key connectors in the region. We conclude that these organizations combined can embody a Latin American node for PECS, and would thereby not only contribute to regional but also global capacities to advance the sustainability agenda.Incluye referencias bibliográfica

Tópicos selectos de ciencias químicas

La Química es una de las ramas de la ciencia que ha tomado mayor importancia en las últimas décadas. Es imposible no pensar en ella al escuchar los avances milagrosos de fármacos, materiales inteligentes, tecnología nanométrica, computadoras cuánticas o procesos catalíticos, donde la transformación controlada de la materia ha logrado la creación de sustancias con propiedades hechas a medida. En ese sentido, el papel de la Facultad de Química, en la formación de profesionales de dicha área, cobra una importancia superlativa; además del compromiso y la responsabilidad de formar sujetos no sólo con conocimiento, sino desarrollar su conciencia social y ecológica, indispensables para la situación actual y futura.Universidad Autónoma del Estado de México