Open Access
IAOx induces the SUR phenotype and differential signalling from IAA under different types of nitrogen nutrition in Medicago truncatula roots
(Elsevier, 2019) Buezo Bravo, Javier; Esteban Terradillos, Raquel; Cornejo Ibergallartu, Alfonso; López Gómez, Pedro; Marino Bilbao, Daniel; Chamizo Ampudia, Alejandro; Gil Idoate, María José; Martínez Merino, Víctor; Morán Juez, José Fernando; Zientziak; Institute for Multidisciplinary Research in Applied Biology - IMAB; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Indole-3-acetaldoxime (IAOx) is a particularly relevant molecule as an intermediate in the pathway for tryptophan-dependent auxin biosynthesis. The role of IAOx in growth-signalling and root phenotype is poorly studied in cruciferous plants and mostly unknown in non-cruciferous plants. We synthesized IAOx and applied it to M. truncatula plants grown axenically with NO3-, NH4+ or urea as the sole nitrogen source. During 14 days of growth, we demonstrated that IAOx induced an increase in the number of lateral roots, especially under NH4+ nutrition, while elongation of the main root was inhibited. This phenotype is similar to the phenotype known as “superroot” previously described in SUR1- and SUR2-defective Arabidopsis mutants. The effect of IAOx, IAA or the combination of both on the root phenotype was different and dependent on the type of N-nutrition. Our results also showed the endogenous importance of IAOx in a legume plant in relation to IAA metabolism, and suggested IAOx long-distance transport depending on the nitrogen source provided. Finally, our results point out to CYP71A as the major responsible enzymes for IAA synthesis from IAOx.
Open Access
Diferencias de protección frente al riesgo biológico laboral en relación al sistema preventivo elegido por la empresa
(2015) Aguilar Elena, Raúl; Campo Barrio, Alberto; Morchón García, Rodrigo; Martínez Merino, Víctor; Ciencias de la Salud; Osasun Zientziak
El objetivo de este trabajo ha sido obtener información sobre el nivel de exposición y protección de los trabajadores a los agentes biológicos laborales en diferentes sectores de actividad valorando sus diferencias en relación al sistema preventivo elegido por las empresas. Se realizó un estudio en el que participaron 590 trabajadores de 59 empresas españolas en las que se pasaron 2 cuestionarios, uno para la empresa y otro para los trabajadores, obteniéndose una muestra definitiva de 518 trabajadores pertenecientes a 51 empresas en las que existía exposición a agentes biológicos. Se encontraron diferencias significativas en la gestión del riesgo biológico laboral en función del sistema preventivo elegido por la empresa concluyendo que la protección a la exposición laboral a agentes biológicos no está desarrollada por completo porque no se dispone de herramientas que permitan su fácil realización y por lo tanto la gestión de los riesgos biológicos general no es adecuada.
Open Access
Kinetics of the acid-catalyzed hydrolysis of tetraethoxysilane (TEOS) by 29Si NMR spectroscopy and mathematical modeling
(Springer, 2018) Echeverría Morrás, Jesús; Moriones Jiménez, Paula; Arzamendi Manterola, Gurutze; Garrido Segovia, Julián José; Gil Idoate, María José; Cornejo Ibergallartu, Alfonso; Martínez Merino, Víctor; Química Aplicada; Kimika Aplikatua; Institute for Advanced Materials and Mathematics - INAMAT2
Tetraethoxysilane (TEOS) is widely used to synthesize siliceous material by the sol–gel process. However, there is still some disagreement about the nature of the limiting step in the hydrolysis and condensation reactions. The goal of this research was to measure the variation in the concentration of intermediates formed in the acid-catalyzed hydrolysis by 29Si NMR spectroscopy, to model the reactions, and to obtain the rate constants and the activation energy for the hydrolysis and early condensation steps. We studied the kinetics of TEOS between pH 3.8 and 4.4, and four temperature values in the range of 277.2–313.2 K, with a TEOS:ethanol:water molar ratio of 1:30:20. Both hydrolysis and the condensation rate speeded up with the temperature and the concentration of oxonium ions. The kinetic constants for hydrolysis reactions increased in each step kh1 < kh2 < kh3 < kh4, but the condensation rate was lower for dimer formation than for the formation of the fully hydrolyzed Si(OH)4. The system was described according to 13 parameters: six of them for the kinetic constants estimated at 298.2 K, six to the activation energies, and one to the equilibrium constant for the fourth hydrolysis. The mathematical model shows a steady increase in the activation energy from 34.5 kJ mol−1 for the first hydrolysis to 39.2 kJ mol−1 in the last step. The activation energy for the condensation reaction from Si(OH)4 was ca. 10 kJ mol−1 higher than the largest activation energy in the hydrolytic reactions. The decrease in the net positive charge on the Si atom contributes to the protonation of the ethoxy group and makes it a better leaving group.
Open Access
Synthesis and Leishmanicidal activity of novel urea, thiourea, and selenourea derivatives of diselenides
(American Society for Microbiology, 2019) Díaz, Marta; Lucio, Hector de; Moreno, Esther; Espuelas, Socorro; Aydillo, Carlos; Jiménez Ruiz, Antonio; Toro, Miguel Ángel; Gutiérrez, Killian Jesús; Martínez Merino, Víctor; Cornejo Ibergallartu, Alfonso; Ciencias; Zientziak
A novel series of thirty-one N-substituted urea, thiourea, and selenourea derivatives containing diphenyldiselenide entities were synthesized, fully characterized by spectroscopic and analytical methods, and screened for their in vitro leishmanicidal activities. The cytotoxic activity of these derivatives was tested against Leishmania infantum axenic amastigotes, and selectivity was assessed in human THP-1 cells. Thirteen of the synthesized compounds showed a significant antileishmanial activity, with 50% effective concentration (EC50) values lower than that for the reference drug miltefosine (EC50, 2.84 mu M). In addition, the derivatives 9, 11, 42, and 47, with EC50 between 1.1 and 1.95 mu M, also displayed excellent selectivity (selectivity index ranged from 12.4 to 22.7) and were tested against infected macrophages. Compound 11, a derivative with a cyclohexyl chain, exhibited the highest activity against intracellular amastigotes, with EC50 values similar to those observed for the standard drug edelfosine. Structure-activity relationship analyses revealed that N-aliphatic substitution in urea and selenourea is recommended for the leish-manicidal activity of these analogs. Preliminary studies of the mechanism of action for the hit compounds was carried out by measuring their ability to inhibit trypanothione reductase. Even though the obtained results suggest that this enzyme is not the target for most of these derivatives, their activity comparable to that of the standards and lack of toxicity in THP-1 cells highlight the potential of these compounds to be optimized for leishmaniasis treatment.
Open Access
Diferencias de protección frente al riesgo biológico laboral en función del tamaño de la empresa
(Universidad Nacional de Colombia, 2015) Aguilar Elena, Raúl; Campo Barrio, Alberto; Morchón García, Rodrigo; Martínez Merino, Víctor; Ciencias de la Salud; Osasun Zientziak
Objetivo Obtener información sobre el nivel de exposición y protección de los trabajadores a los agentes biológicos laborales, en el sector sanitario, granjas, industria cárnica, laboratorios, plantas de tratamiento de residuos, industria alimentaria y centros veterinarios valorando sus diferencias en relación al tamaño de la empresa. Método Se realizó un estudio en el que participaron 590 trabajadores pertenecientes a 59 empresas españolas en las que se pasó un cuestionario inicial con 3 preguntas dirigidas a las empresas contestadas por los responsables de prevención y otro cuestionario con 34 preguntas para ser contestado por los trabajadores expuestos. Se realizó una validación mediante análisis del alfa de Cronbach global del segundo cuestionario para valorar la consistencia interna y fiabilidad de los cuestionarios. Resultados La muestra definitiva obtenida fue de 518 trabajadores de 51 empresas en las que existía exposición a agentes biológicos. El cuestionario obtuvo un alfa de Cronbach superior a 0,7. Se encontraron diferencias significativas en la gestión del riesgo biológico laboral en función del tamaño de la empresa (p-valor<0,05). Conclusiones Los resultados obtenidos ofrecieron una adecuada consistencia interna del cuestionario. Por otro lado la exposición laboral a agentes biológicos es un factor que debe tenerse en cuenta puesto que no está desarrollada por completo porque tanto las empresas como los profesionales de la prevención no tienen herramientas disponibles que permitan su fácil realización y por lo tanto la gestión de los riesgos biológicos general no es adecuada.
Open Access
Pretreatment and enzymatic hydrolysis for the efficient production of glucose and furfural from wheat straw, pine and poplar chips
(Elsevier, 2019) Cornejo Ibergallartu, Alfonso; Alegría Dallo, Irantzu; García Yoldi, Íñigo; Sarobe Martínez, Íñigo; Sánchez, David; Otazu, Eduardo; Funcia, Ibai; Gil Idoate, María José; Martínez Merino, Víctor; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Gobierno de Navarra / Nafarroako Gobernua
A flexible approach to a two-step biorefinery for the production of glucose and furfural from three different feedstocks is presented. Pretreatment conditions were selected to drive the production towards the generation of glucose or furfural. Harsh pretreatment conditions produced solids with highly accessible glycan contents for the enzymatic hydrolysis with 100% glucose yields when wheat straw or poplar chips were used as feedstock. Mild conditions afforded xylan-rich hydrolysates that could be efficiently transformed to furfural, either under conventional or microwave heating in biphasic media. Yields for the transformation of xylan from feedstocks ranged between 45% and 90% depending on the feedstock, the thermal pretreatment and the cyclodehydration conditions. Up to 12.6 kg of glucose and materials and 2.5 kg of furfural can be produced starting from 50 kg of biomass. A new analytical methodology based on 13C NMR that provided good quality analytical results is also presented.