Search

En el presente trabajo se describen y analizan los resultados obtenidos en el aprovecha- miento y rendimiento académico de estudiantes de nivel universitario con la introducción de las metodologías de clase inversa y aprendizaje activo en sesiones de prácticas de laboratorio de Biología Molecular. El aprendizaje inverso fue verificado mediante la aplicación de cuestionarios previos en línea cuya evaluación implicó una bonificación del 10% de la nota final de la práctica de laboratorio. El aprovechamiento de las sesiones presenciales de prácticas fue evaluado con un informe final escrito individual y con un cuestionario integrador final en línea. El resultado de este último cuestionario implicó una bonificación adicional del 10% de la nota final de la práctica. Con el objetivo de estimar la apreciación de los propios alumnos sobre el efecto de la innovación en los resultados del proceso de aprendizaje y el interés en la asignatura, se aplicó una pequeña encuesta anónima en línea voluntaria tras finalizar la asignatura. La introducción de la clase inversa y el empleo de metodologías de aprendizaje activo como preguntas y respuestas, debates de aplicación del conocimiento adquirido a nuevas situaciones experimentales, instrucción por pares, instrucción basada en problemas, entre otras metodologías, permitió incrementar el rendimiento académico en comparación con cursos anteriores y una mayor uniformidad en la adquisición del conocimiento y desarrollo de competencias en la totalidad de los estudiantes. La apreciación de los propios alumnos del efecto de la innovación en los resultados del proceso de aprendizaje fue muy positiva y altamente motivadora. In the present study, we described and analyzed the results obtained after the application of the methodologies of fipped classroom and active learning on achievement and academic performance of university students in laboratory practices of Molecular Biology. Flipped learning was evaluated by short online questionnaires, performed prior to the lab practice, which represented a 10% of the fnal grade. The student performance in the face-to-face lab practices was evaluated by a fnal individual report and a further online questionnaire. The results of this fnal integrative questionnaire represented an additional 10% of the fnal grade. A short anonym survey was applied online after the fnalization of the course in order to value the students’ opinion about the infuence of these learning innovations on their personal achievement and interest for the course. The introduction of fipped classroom and active learning methodologies such as questions and answers, discussion of application to novel contexts, peer instruction, problem-based learning, among others, led to increase academic performance compared to the same results in previous years as well as a higher homogeneity in learning acquisition and competence development by all the students. Students’ opinion of the innovation was highly positive and motivating.

16 pags., 7 figs. Proteins belonging to the FUR (ferric uptake regulator) family are the cornerstone of metalloregulation in most prokaryotes. Although numerous reviews have been devoted to these proteins, these reports are mainly focused on the Fur paralog that gives name to the family. In the last years, the increasing knowledge on the other, less ubiquitous members of this family has evidenced their importance in bacterial metabolism. As the Fur paralog, the major regulator of iron homeostasis, Zur, Irr, BosR and PerR are tightly related to stress defenses and host-pathogen interaction being in many cases essential for virulence. Furthermore, the Nur and Mur paralogs largely contribute to control nickel and manganese homeostasis, which are cofactors of pivotal proteins for host colonization and bacterial redox homeostasis. The present review highlights the main features of FUR proteins that differ to the canonical Fur paralog either in the coregulatory metal, such as Zur, Nur and Mur, or in the action mechanism to control target genes, such as PerR, Irr and BosR. This work has been supported by grants E35_17R Biología Estructural from Gobierno de Aragón, BFU2016-77671-P/ FEDER and PID2019-104889 GB-I00 from MINECO and Ministerio de Ciencia, Innovacion y Universidades

FurC (PerR) from Anabaena sp. PCC7120 was previously described as a key transcriptional regulator involved in setting off the oxidative stress response. In the last years, the cross-talk between oxidative stress, iron homeostasis and nitrogen metabolism is becoming more and more evident. In this work, the transcriptome of a furC-overexpressing strain was compared with that of a wild-type strain under both standard and nitrogen-deficiency conditions. The results showed that the overexpression of furC deregulates genes involved in several categories standing out photosynthesis, iron transport and nitrogen metabolism. The novel FurC-direct targets included some regulatory elements that control heterocyst development (hetZ and asr1734), genes directly involved in the heterocyst envelope formation (devBCA and hepC) and genes which participate in the nitrogen fixation process (nifHDK and nifH2, rbrA rubrerythrin and xisHI excisionase). Likewise, furC overexpression notably impacts the mRNA levels of patA encoding a key protein in the heterocyst pattern formation. The relevance of FurC in these processes is bringing out by the fact that the overexpression of furC impairs heterocyst development and cell growth under nitrogen step-down conditions. In summary, this work reveals a new player in the complex regulatory network of heterocyst formation and nitrogen fixation.

2-oxoglutarate (2-OG) is a central metabolite that acts as a signaling molecule informing about the status of the carbon/nitrogen balance of the cell. In recent years, some transcriptional regulators and even two-component systems have been described as 2-OG sensors. In the nitrogen-fixing cyanobacterium Anabaena sp. PCC 7120, two master regulators, NtcA and FurA, are deeply involved in the regulation of nitrogen metabolism. Both of them show a complex intertwined regulatory circuit to achieve a suitable regulation of nitrogen fixation. In this work, 2-OG is found to bind FurA, modulating the specific binding of FurA to the ntcA promoter. This study provides evidence of a new additional control point in the complex network controlled by the NtcA and FurA proteins.

Cantidades significativas de proteínas puras, solubles y biológicamente activas son requeridas de modo creciente tanto en proyectos de investigación como para su empleo con fines terapéuticos, diagnósticos o industriales. La purificación de proteínas a partir de sus fuentes naturales no logra suplir en la mayoría de los casos los requerimientos de cantidad, calidad, facilidad de aislamiento o factibilidad económica del proceso. El desarrollo de la tecnología del ADN recombinante desde mediados de la década de los 70 del pasado siglo marcó el comienzo de la era moderna de la biotecnología. Con los conocimientos actuales en genómica, proteómica y bioinformática, el número de proteínas producidas por vía recombinante se ha incrementado exponencialmente. Dado su rápido crecimiento y altos rendimientos de biomasa en medios relativamente económicos, el amplio conocimiento sobre su fisiología y genética, así como su elevada capacidad de producción de proteínas heterólogas, la enterobacteria Escherichia coli continúa siendo el sistema de elección para la expresión recombinante, tanto a escala de laboratorio como en la industria. En el presente trabajo revisamos los aspectos metodológicos más importantes a tener en cuenta para garantizar adecuados niveles de expresión de proteínas recombinantes biológicamente activas, empleando a E. coli como organismo hospedero.

Recombinant protein expression and site-directed mutagenesis of target genes have demonstrated an increasing importance in the fields of molecular biology, biochemistry, biotechnology, and medicine. By using the flavodoxin of the model cyanobacterium Anabaena sp. PCC 7120 as a laboratory tool, we designed a comprehensive laboratory practice encompassing several well-established molecular biology techniques and procedures in order to fulfill two main objectives: (1) overexpression and immunodetection of Anabaena flavodoxin in recombinant Escherichia coli cell extracts, and (2) site-directed mutagenesis of the Anabaena flavodoxin gene isiB. This lab practice provides undergraduate students the possibility to perform by themselves several essential techniques in the field. With the aid of professors, students are stimulated to think, to interpret, and to discuss the results based on what they had learned in previous theoretical courses.

Significance: The successful adaptation of microorganisms to ever-changing environments depends, to a great extent, on their ability to maintain redox homeostasis. To effectively maintain the redox balance, cells have developed a variety of strategies mainly coordinated by a battery of transcriptional regulators through diverse mechanisms. Recent Advances: This comprehensive review focuses on the main mechanisms used by major redox-responsive regulators in prokaryotes and their relationship with the different redox signals received by the cell. An overview of the corresponding regulons is also provided. Critical Issues: Some regulators are difficult to classify since they may contain several sensing domains and respond to more than one signal. We propose a classification of redox-sensing regulators into three major groups. The first group contains one-component or direct regulators, whose sensing and regulatory domains are in the same protein. The second group comprises the classical two-component systems involving a sensor kinase that transduces the redox signal to its DNA-binding partner. The third group encompasses a heterogeneous group of flavin-based photosensors whose mechanisms are not always fully understood and are often involved in more complex regulatory networks. Future Directions: Redox-responsive transcriptional regulation is an intricate process as identical signals may be sensed and transduced by different transcription factors, which often interplay with other DNA-binding proteins with or without regulatory activity. Although there is much information about some key regulators, many others remain to be fully characterized due to the instability of their clusters under oxygen. Understanding the mechanisms and the regulatory networks operated by these regulators is essential for the development of future applications in biotechnology and medicine.

Resumen del trabajo presentado al 7th Congress of European Microbiologists, celebrado en Valencia (España) del 9 al 13 de julio de 2017.-- et al., [Backgrounds]: Ferric uptake regulator (Fur) proteins are transcriptional regulators that play key roles in many prokariots. Anabaena PCC 7120 contains in its genome three paralogs of Fur proteins whose genes are called all1691 (furA), all2473 (furB) and alr0954 (furC). Until now, little is known about the role of FurC in cyanobacteria. [Objectives]: This work was focused on the study of the functions of FurC protein in Anabaena PCC7120. In order to achieve this goal, an overexpression mutant of FurC protein was constructed in Anabaena PCC7120 rendering the EB2770 strain. [Methods]: Scanning electron microscopy (SEM) studies and growth curves were performed comparing the EB2770 and the wild type strains. Photosynthetic pigments were also determined. Whole-cell absorbance spectra and the fluorescence emission spectra at 77K were carried out in order to compare the composition and efficiency of photosynthetic apparatus in both strains. Finally, pull down experiments were performed with purified FurC protein to identify proteins that could interact with this protein. [Conclusions]: SEM studies revealed changes in size, shape and roughness of the EB2770 cells. Pigment content and yield of energy transfer between the phycobilisome and the photosystem I and II was notably altered in the EB2770 mutant. Pull down results indicated that two linker proteins of phycobilisome interacted with FurC protein. These results suggest that FurC has a role regulating the final composition of photosynthetic pigments and therefore influencing the yield of energy transfer between the phycobilisome and the photosystem I and II although the detailed mechanism remains unknown.