Genotoxicidad de la acrilamida y la glicidamida en Allium cepa

INTRODUCCIÓN: la formación de acrilamida (AA) en alimentos que fueron sometidos a tratamiento térmico, fue un descubrimiento inesperado en abril del 2002 por la Universidad de Estocolmo y la Administración Nacional de Alimentos de Suecia (NFA). Esta sustancia potencialmente tóxica y su metabolito glicidamida (GA) se forman en muchos alimentos cocidos a temperaturas elevadas. OBJETIVO: en virtud de que no hay estudios de estas sustancias químicas, en células vegetales, el objetivo fue comprobar el efecto genotóxico de la AA y GA en células de Allium cepa. MATERIALY MÉTODO: se determinó el efecto citotóxico a través del crecimiento de la raíz, actividad proliferativa y las aberraciones cromosómicas de la AA y GA en células meristemáticas de Allium cepa, expuestas a diferentes tiempos y concentraciones, evaluando el crecimiento de la raíz, la actividad proliferativa y las aberraciones cromosómicas. RESULTADOS: GA causa una inhibición del crecimiento de la raíz cuya intensidad depende de la concentración en un medio dado y la AA no muestra diferencias estadísticamente significativas respecto al control. La GA bloquea el ciclo de división celular en una etapa previa a la mitosis y no ocurre lo mismo con la AA. En cuanto a los efectos clastogénicos la GA induce estos efectos en las raíces meristemáticas de Allium cepa, en cambio la AA no los produce. CONCLUSIONES: en este estudio, aunque las concentraciones de AA y GA son mucho más altas que lo niveles de exposición alimentaria en humanos, la GA fue claramente genotóxica para células vegetales, a una determinada concentración, con una marcada citotoxicidad. Por lo tanto, nos permitió distinguir las diferencias entre AA y GA

Trace checking of Metric Temporal Logic with Aggregating Modalities using MapReduce

Modern complex software systems produce a large amount of execution data, often stored in logs. These logs can be analyzed using trace checking techniques to check whether the system complies with its requirements specifications. Often these specifications express quantitative properties of the system, which include timing constraints as well as higher-level constraints on the occurrences of significant events, expressed using aggregate operators. In this paper we present an algorithm that exploits the MapReduce programming model to check specifications expressed in a metric temporal logic with aggregating modalities, over large execution traces. The algorithm exploits the structure of the formula to parallelize the evaluation, with a significant gain in time. We report on the assessment of the implementation - based on the Hadoop framework - of the proposed algorithm and comment on its scalability.Comment: 16 pages, 6 figures, Extended version of the SEFM 2014 pape

On the Class of Possible Nonlocal Anyon-Like Operators and Quantum Groups

We find a class of nonlocal operators constructed by attaching a disorder operator to fermionic degrees of freedom, which can be used to generate q-deformed algebras following the Schwinger approach. This class includes the recently proposed anyonic operators defined on a lattice.Comment: 10 pages (plain latex), HU-SEFT R 1993-9, to be published in Journal of Physics A: Math. and General, Letters to the Edito

Evaluación de la toxicidad genética de la yerba mate (Ilex paraguariensis) en Allium cepa

INTRODUCCIÓN: La Yerba Mate, es una infusión hecha de las hojas del árbol Ilex paraguariensis, planta de la familia Aquifoliaceae. Es una bebida que se consume principalmente en los países de América del Sur como Argentina, Uruguay, Brasil, Paraguay y está logrando una mayor penetración en Estados Unidos como en otros países del mundo. OBJETIVO: El presente estudio evalúa la genotoxicidad de la yerba mate (Ilex paraguariensis), previamente probado para la presencia de hongos toxigénicos en cultivos específicos. MATERIAL Y METODOS: Se utilizó el sistema Allium cepa para el estudio de genotoxicidad, las células meristemáticas fueron tratadas con una infusión filtrada de mate, con agua destilada como control negativo y Dimetilsulfóxido (DMS) al 0,2 % como control positivo. RESULTADOS: El crecimiento radicular fue reducido dependiendo de la concentración, y al estudiar la proliferación celular se observó que la frecuencia de células mitóticas se reducía progresivamente a medida que aumentaba la concentración de yerba mate. Por otra parte, se observó un aumento en la frecuencia de células aberrantes con la concentración de yerba mate más alta (1400 µg/ml). CONCLUSIONES: Los hallazgos de este estudio muestran que la yerba mate induce efectos clastogénicos en las raíces meristemáticas de Allium cepa

Modular anomaly equations in N N \mathcal{N} =2* theories and their large-N limit

We propose a modular anomaly equation for the prepotential of the N=2* super Yang-Mills theory on R^4 with gauge group U(N) in the presence of an Omega-background. We then study the behaviour of the prepotential in a large-N limit, in which N goes to infinity with the gauge coupling constant kept fixed. In this regime instantons are not suppressed. We focus on two representative choices of gauge theory vacua, where the vacuum expectation values of the scalar fields are distributed either homogeneously or according to the Wigner semi-circle law. In both cases we derive an all-instanton exact formula for the prepotential. As an application, we show that the gauge theory partition function on S^4 at large N localises around a Wigner distribution for the vacuum expectation values leading to a very simple expression in which the instanton contribution becomes independent of the coupling constant

Dissolved organic carbon retention by coprecipitation during the oxidation of ferrous iron (EGU2018-3906)

Although the importance of Fe (hydr)oxides for soil organic matter (OM) stabilization and C retention by surface adsorption is well known, only recently has coprecipitation been recognized as an important process responsible for C storage in hydromorphic soils, such as rice paddy soils. Under periodic fluctuations in redox conditions the interaction between dissolved organic carbon (DOC) and Fe (hydr)oxides may not only involve organic coatings on mineral surfaces, but also Fe-DOC coprecipitates that form during the oxidation of soil solutions containing important amounts of DOC and Fe2+. The aim of this work was to provide new insights into the mechanisms involved, and the amount and selectivity of C retained during the coprecipitation process. A series of Fe-OM associations with increasing C loading was synthesized at pH 6 by surface adsorption or coprecipitation (oxidation of ferrous iron) utilizing rice-straw derived dissolved organic matter. The kinetics of Fe2+ oxidation and complexation, and the total and selective retention of DOC during the coprecipitation process were evaluated. Moreover, synthesized associations, as well as a field coprecipitate collected in situ from a paddy soil, were studied by X-ray diffraction, N2 gas adsorption-desorption isotherms, electrophoretic mobility measurements and thermogravimetric analyses. Coprecipitation resulted in higher organic C contents (49-213 mg g-1) with respect to adsorbed systems (18-47 mg g-1), and favoured the inclusion of OM within highly aggregated associations having particularly low BET specific surface areas. Coprecipitates sampled in situ also showed a similar retention of organic C confirming that this process may contribute significantly to the OM stabilization in paddy topsoils. The mechanisms involved in the retention of straw-derived DOM during coprecipitation were shown to be strongly dependent on C/Fe ratio of the solution. Although the overall coprecipitation process was highly selective for aromatic constituents, initial complexation of Fe2+ and precipitation as C-rich metal salts involved the selective interaction with aliphatic carboxylic constituents. The contribution of the latter mechanism to total C retention during coprecipitation was shown to increase with increasing solution C/Fe ratios. These aliphatic complexes formed during coprecipitation may play an important, though often underestimated, role in C stabilization in hydromorphic. The process-related selectivity of specific constituents of DOM during coprecipitation highlights the involvement of specific mechanisms, i.e. complexation, adsorption, salt precipitation, while ruling out non-selective, physical occlusion of OM within the forming coprecipitat