Role of Nitrate Reductase in NO Production in Photosynthetic Eukaryotes

Nitric oxide is a gaseous secondary messenger that is critical for proper cell signaling and plant survival when exposed to stress. Nitric oxide (NO) synthesis in plants, under standard phototrophic oxygenic conditions, has long been a very controversial issue. A few algal strains contain NO synthase (NOS), which appears to be absent in all other algae and land plants. The experimental data have led to the hypothesis that molybdoenzyme nitrate reductase (NR) is the main enzyme responsible for NO production in most plants. Recently, NR was found to be a necessary partner in a dual system that also includes another molybdoenzyme, which was renamed NO-forming nitrite reductase (NOFNiR). This enzyme produces NO independently of the molybdenum center of NR and depends on the NR electron transport chain from NAD(P)H to heme. Under the circumstances in which NR is not present or active, the existence of another NO-forming system that is similar to the NOS system would account for NO production and NO effects. PII protein, which senses and integrates the signals of the C–N balance in the cell, likely has an important role in organizing cell responses. Here, we critically analyze these topics

Cómo afrontar las conductas disruptivas en la Educación Primaria

En este trabajo se presenta un análisis de las conductas disruptivas que se pueden encontrar en el aula de educación primaria, además se plantean una serie de técnicas y procedimientos que pueden ser útiles para mejorarlas. A lo largo del documento, como resultado de la literatura revisada, se observa la estrecha relación que existe entre los problemas del alumnado en el aula y las dificultades en el contexto familiar

From the Eukaryotic Molybdenum Cofactor Biosynthesis to the Moonlighting Enzyme mARC

All eukaryotic molybdenum (Mo) enzymes contain in their active site a Mo Cofactor (Moco), which is formed by a tricyclic pyranopterin with a dithiolene chelating the Mo atom. Here, the eukaryotic Moco biosynthetic pathway and the eukaryotic Moco enzymes are overviewed, including nitrate reductase (NR), sulfite oxidase, xanthine oxidoreductase, aldehyde oxidase, and the last one discovered, the moonlighting enzyme mitochondrial Amidoxime Reducing Component (mARC). The mARC enzymes catalyze the reduction of hydroxylated compounds, mostly N-hydroxylated (NHC), but as well of nitrite to nitric oxide, a second messenger. mARC shows a broad spectrum of NHC as substrates, some are prodrugs containing an amidoxime structure, some are mutagens, such as 6-hydroxylaminepurine and some others, which most probably will be discovered soon. Interestingly, all known mARC need the reducing power supplied by different partners. For the NHC reduction, mARC uses cytochrome b5 and cytochrome b5 reductase, however for the nitrite reduction, plant mARC uses NR. Despite the functional importance of mARC enzymatic reactions, the structural mechanism of its Moco-mediated catalysis is starting to be revealed. We propose and compare the mARC catalytic mechanism of nitrite versus NHC reduction. By using the recently resolved structure of a prokaryotic MOSC enzyme, from the mARC protein family, we have modeled an in silico three-dimensional structure of a eukaryotic homologue

A chloroplast redox relay adapts plastid metabolism to light and affects cytosolic protein quality control

In chloroplasts, thiol-dependent redox regulation is linked to light since the disulfide reductase activity of thioredoxins (Trxs) relies on photo-reduced ferredoxin (Fdx). Furthermore, chloroplasts harbor an NADPH-dependent Trx reductase (NTR) with a joint Trx domain, termed NTRC. The activity of these two redox systems is integrated by the redox balance of 2-Cys peroxiredoxin (Prx), which is controlled by NTRC. However, NTRC was proposed to participate in redox regulation of additional targets, prompting inquiry into whether the function of NTRC depends on its capacity to maintain the redox balance of 2-Cys Prxs or by direct redox interaction with chloroplast enzymes. To answer this, we studied the functional relationship of NTRC and 2-Cys Prxs by a comparative analysis of the triple Arabidopsis (Arabidopsis thaliana) mutant, ntrc-2cpab, which lacks NTRC and 2-Cys Prxs, and the double mutant 2cpab, which lacks 2-Cys Prxs. These mutants exhibit almost indistinguishable phenotypes: in growth rate, photosynthesis performance, and redox regulation of chloroplast enzymes in response to light and darkness. These results suggest that the most relevant function of NTRC is in controlling the redox balance of 2-Cys Prxs. A comparative transcriptomics analysis confirmed the phenotypic similarity of the two mutants and suggested that the NTRC-2-Cys Prxs system participates in cytosolic protein quality control. We propose that NTRC and 2-Cys Prxs constitute a redox relay, exclusive to photosynthetic organisms that fine-tunes the redox state of chloroplast enzymes in response to light and affects transduction pathways towards the cytosol.Ministerio de Economía y Competitividad BIO2017-85195-C2-1-

Estudo dos pombais como elemento característico da arquitectura tradicional de La Mancha, Espanha

El palomar es un espacio presente en toda casa de labor de la región, dedicado a la cría de pichones e integrado, de forma más o menos evidente, en las cámaras de los edificios residenciales y/o sus dependencias anexas. Existen también ejemplos de palomares aislados y de carácter singular, que ponen de manifiesto la enorme relevancia de esta actividad en el pasado, así como su importancia en la configuración de la imagen de las aldeas en el medio rural. Por desgracia este tipo de edificaciones están abocadas a su ruina una vez que han perdido su función y carecen de mantenimiento. Con ello se están perdiendo los últimos vestigios y testimonios de esta actividad complementaria a la agricultura. El presente artículo expone los resultados del análisis de más de 50 edificaciones de este tipo, y describe su estado actual y sus diversos tipos, que están relacionados con la influencia de las costumbres locales y el aprovechamiento de los recursos locales en su construcción.The dovecote is a space present in every farmhouse in this region, dedicated to the breeding of pigeons and integrated, more or less clearly, in the garrets of residential buildings and/or their annexes. There are also examples of isolated dovecotes of a singular character, that show the enormous relevance of this activity in the past, as well as its importance in shaping the image of villages in rural areas. Unfortunately, this type of building inevitably falls into disrepair, once it has lost its function and lacks maintenance. This way, the last vestiges and testimonies of this complementary activity to agriculture are being lost. This article is aimed at presenting the results of the analysis of more than 50 buildings of this kind, and describing their current situation and their diverse types, which are linked to the influence of local customs and the use of local resources in their construction

Efecto del nivel de experiencia clínica del examinador sobre la validez de criterio y fiabilidad inter-sesión de cinco medidas del rango de movimiento de la flexión dorsal del tobillo

El objetivo de este estudio fue analizar el efecto que el diferente grado de experiencia del examinador tiene sobre la validez de criterio y fiabilidad inter-sesión de las medidas de rango de movimiento de la flexión dorsal del tobillo (ROMFDT) obtenidas en las pruebas: flexión dorsal del tobillo pasiva en decúbito prono y rodilla flexionada (FDPAS), zancada coninclinómetro (FDZAN-INC) y cinta métrica (FDZAN-MET), zancada modificada con taburete (FDZAN-TAB) y zancada modificada con cajón (FDZAN-CAJ). Un total de 17 deportistas recreativos completaron este estudio. Cada participante fue evaluado por dos examinadores con distinto nivel de experiencia (experto y novel) del ROMFDT empleando 5 pruebas exploratorias diferentes en dos sesiones distintas. Los resultados muestran bajos valores de validez para el examinador novel en todas las pruebas de valoración del ROMFDTexcepto en la prueba FDZAN-INC (error típico de la estimación estandarizado = 0,5 [pequeño]; Pearson = 0,85 [moderado]; kappa = 0,74 [buena]). El examinador experto presentó niveles altos de fiabilidad inter-sesión en las pruebas FDZAN-INC, FDZAN-MET y FDZAN-CAJ y valores aceptables en las pruebas FDPAS y FDZAN-TAB. El examinador novel obtuvo valores aceptables de fiabilidad en toda las pruebas de valoración excepto en la prueba FDPAS, que fueron considerados como no aceptables. Por lo tanto, se recomienda que tanto los examinadores expertos como noveles utilicen la prueba FDZAN-INC para: (a) identificar a personas con restringida o normal movilidad de la flexión dorsal del tobillo; y (b) monitorizar la eficacia de los programas de intervención aplicados en caso de ser necesarios

Chlamydomonas reinhardtii, an Algal Model in the Nitrogen Cycle

Nitrogen (N) is an essential constituent of all living organisms and the main limiting macronutrient. Even when dinitrogen gas is the most abundant form of N, it can only be used by fixing bacteria but is inaccessible to most organisms, algae among them. Algae preferentially use ammonium (NH4+) and nitrate (NO3−) for growth, and the reactions for their conversion into amino acids (N assimilation) constitute an important part of the nitrogen cycle by primary producers. Recently, it was claimed that algae are also involved in denitrification, because of the production of nitric oxide (NO), a signal molecule, which is also a substrate of NO reductases to produce nitrous oxide (N2O), a potent greenhouse gas. This review is focused on the microalga Chlamydomonas reinhardtii as an algal model and its participation in different reactions of the N cycle. Emphasis will be paid to new actors, such as putative genes involved in NO and N2O production and their occurrence in other algae genomes. Furthermore, algae/bacteria mutualism will be considered in terms of expanding the N cycle to ammonification and N fixation, which are based on the exchange of carbon and nitrogen between the two organisms

Amartya Sen frente al espejo social de la libertad. Límites al enfoque de las capacidades individuales

This paper illustrates somehow aspect of the capabilities approach developed by the economist and philosopher Amartya Sen. Particularly it examines how the concept of freedom (as “opportunity”) reveals unable to empirically and normatively adjust to the notion of freedom as capability. From such categorical contradiction is introduced a set of unprecedented concepts that, gathered to the largest social dimension of freedom, allow releasing from such mismatch. Conclusions are focused on the emphasis of social environment as state that far from its recognized influence on individual capabilities has potentially enablers’ elements.<br><br>En este trabajo se ilustran algunos aspectos relativos al enfoque de las capacidades desarrollado por el economista y filósofo Amartya Sen. Particularmente se examina cómo el concepto de libertad (“de oportunidad”) se revela imposibilitado para atenerse empírica y normativamente a la noción de libertad como capacidad. A partir de tal contradicción categorial se presentan una serie de conceptos inéditos que, vinculados al carácter más social de la libertad, permitan librarnos de tal desajuste. Las conclusiones de este trabajo van enfocadas hacia la enfatización del entorno social como estado donde, lejos de su reconocida influencia sobre las capacidades individuales, atesora elementos potencialmente capacitadores

Biología molecular de la asimilación de nitrato en algas

El alga verde eucariótica Chlamydomonas reinhardtii es un organismo modelo para el estudio de la biología molecular de la asimilación de nitrato. Este sistema biológico presenta excelentes cualidades para estudios bioquímicos, fisiológicos, genéticos y moleculares. Estas investigaciones han permitido los siguientes logros: i) generación de una colección de mutantes; ii) identificación y caracterización de genes para el transporte de amonio; iii) caracterización de genes del transporte biespecífico de bicarbonato/nitrito; iv) clonación y caracterización del gen que codifica la proteína portadora de cofactor de molibdeno (MCP), determinación de la estructura cristalina de la misma y de sus residuos funcionales en la unión del cofactor; v) utilización de una nueva estrategia para identificar mutantes del cofactor de molibdeno; y vi) identificación de un nuevo LTR-retrotransposón de la familia gypsy