Nematodes

A fist of nematodes associated with the roots of beans and other plants is given in table form, the species of Meloidogyne and Pratylenchus being the most common in bean crops in the Americas. Meloidogyne species are prevalent in light sandy soils with good drainage. Length of survival in the soil depends on the nematode species, stage of development of the pathogen, soil type, moisture, and aeration. Color illustrations are given of the symptoms and damage caused by nematode feeding on root systems. They often appear on aerial plant parts which become chlorotic, stunted, burned at the leaf edges, and finally wilt. Crop rotation, deep plowing, the use of fallow, weed control, and flooding for 1-2 wk reduce nematode populations. Chemical control is effective but expensive and requires special equipment for soil applications. Control by plant resistance is the most efficient strategy. (CIAT)En forma de cuadro se presenta una lista de los nematodos que se asocian frecuentemente con las raices de frijol y otras plantas, siendo las especies de Meloidogyne y Pratylenchus las mas comunes en los cultivos de frijol en America. Las especies de Meloidogyne predominan en suelos arenosos livianos bien drenados. El periodo de supervivencia en el suelo depende de la especie de nematodo, el estado de desarrollo del patogeno, el tipo de suelo, la humedad y la temp. Se dan ilustraciones a color de los sintomas y danos ocasionados por los nematodos al alimentarse de los sistemas radicales. Estos se encuentran a menudo en las partes aereas de las plantas, las cuales se vuelven cloroticas, raquiticas, presentan quemazones en los bordes de las hojas y terminan marchitandose. La rotacion de cultivos, el arado profundo, el uso de barbecho, el control de malezas y las inundaciones durante 1-2 semanas disminuyen la poblacion de nematodos. El control quimico, aunque efectivo, es costoso y requiere equipo especial para hacer las aplicaciones al suelo. La estrategia mas efectiva es el control mediante el uso de var. resistentes. (CIAT

Inhibition of Transport of a Bose-Einstein Condensate in a Random Potential

We observe the suppression of the 1D transport of an interacting elongated Bose-Einstein condensate in a random potential with a standard deviation small compared to the typical energy per atom, dominated by the interaction energy. Numerical solutions of the Gross-Pitaevskii equation reproduce well our observations. We propose a scenario for disorder-induced trapping of the condensate in agreement with our observations.Comment: Proceedings of the 17th International Conference on Laser Spectroscopy (ICOLS 05), Cairngorms National Park, Scotland, 19-24 June 200

Variación del proteoma de las micropartículas plaquetarias dependiendo del estímulo: papel de las proteínas de señalización

Comunicaciones a congreso

Inorganic nanoparticles and biology

Biocompatibilitat, biodistribució, biodegradació, inflamació i interferència amb el funcionament normal de les cèl·lules i teixits, entre d'altres, determinarà la toxicitat de les nanopartícules inorgàniques i nanoestructures de carbó, i per tant l'extensió del seu us. Exemples recents a la literatura científica mostren que les nanopartícules inorgàniques i els nanotubs de carboni no causen efectes tòxics aguts. De totes maneres, la interacció d'aquests materials amb organismes vius pot pertorbar la seva activitat normal induint funcionaments erronis i malalties. De fet, les interaccions entre nanopartícules i biologia que s'han observat, que poden ser usades per detectar i manipular estats biològics i contribuir a una millor diagnosis i teràpia, també podrien tenir un impacte negatiu en la salut i el medi ambient si s'alliberen incontroladament quantitats massives d'alguns tipus de nanopartícules, abans que es faci una avaluació exhaustiva dels riscos potencials d'aquests nous materials. La pregunta clau és si els riscos desconeguts de les nanoparticules, en particular el seu impacte en la salut i el medi ambient, supera els beneficis d'aquesta tecnologia en societat. Per això, pel futur desenvolupament de la nanotecnologia, l'avaluació de la seva potencial toxicitat es clau.Biocompatibility, biodistribution, biodegradation, inflammation and interference with the normal functioning of cells and tissues are some of the features that determine the toxicity of engineered inorganic nanoparticles and carbon nanostructures, and therefore the potential extent of their use. Recent examples in the literature show that engineered inorganic nanoparticles and carbon nanostructures do not normally cause acute toxic effects. However, their interaction with living organisms may disrupt normal activity leading to disordersand disease. Nanoparticle-organism interactions, which can be used to detect and manipulate biological states and to heal damaged organs in an environment controlled by specialists, as in clinical cases, could lead to environmental and human health hazards if nanoparticles are released prior to adequate risk assessment and without proper controls. The central question is whether the unknown risks of engineered nanoparticles, in particular their impact on health and the environment, outweigh their established benefits for society. Therefore, to accurately evaluate the utility of these materials it is necessary to assess their potential toxicity

Helicobacter pullorum cytolethal distending toxin targets vinculin and cortactin and triggers formation of lamellipodia in intestinal epithelial cells

Helicobacter pullorum, a bacterium initially isolated from poultry, has been associated with human digestive disorders. However, the factor responsible for its cytopathogenic effects on epithelial cells has not been formally identified. The cytopathogenic alterations induced by several human and avian H. pullorum strains were investigated on human intestinal epithelial cell lines. Moreover, the effects of the cytolethal distending toxin (CDT) were evaluated first by using a wild-type strain and its corresponding cdtB isogenic mutant and second by delivering the active CdtB subunit of the CDT directly into the cells. All of the H. pullorum strains induced cellular distending phenotype, actin cytoskeleton remodeling, and G2/M cell cycle arrest. These effects were dependent on the CDT, as they were (1) not observed in response to a cdtB isogenic mutant strain and (2) present in cells expressing CdtB. CdtB also induced an atypical delocalization of vinculin from focal adhesions to the perinuclear region, formation of cortical actin-rich large lamellipodia with an upregulation of cortactin, and decreased cellular adherence. In conclusion, the CDT of H. pullorum is responsible for major cytopathogenic effects in vitro, confirming its role as a main virulence factor of this emerging human pathogen.This work was supported by the Institut national de la santé et de la recherche médicale, the University Bordeaux Segalen, the Conseil Régional d’Aquitaine (grants 20030304002FA and 20040305003 FA), the Société Nationale Française de Gastroentérologie, the European Union (FEDER no. 2003227

Dephasing-induced diffusive transport in anisotropic Heisenberg model

We study transport properties of anisotropic Heisenberg model in a disordered magnetic field experiencing dephasing due to external degrees of freedom. In the absence of dephasing the model can display, depending on parameter values, the whole range of possible transport regimes: ideal ballistic conduction, diffusive, or ideal insulating behavior. We show that the presence of dephasing induces normal diffusive transport in a wide range of parameters. We also analyze the dependence of spin conductivity on the dephasing strength. In addition, by analyzing the decay of spin-spin correlation function we discover a presence of long-range order for finite chain sizes. All our results for a one-dimensional spin chain at infinite temperature can be equivalently rephrased for strongly-interacting disordered spinless fermions.Comment: 15 pages, 9 PS figure

Model-Based Evaluation of Methods for Respiratory Sinus Arrhythmia Estimation

Objective: Respiratory sinus arrhythmia (RSA) refers to heart rate oscillations synchronous with respiration, and it is one of the major representations of cardiorespiratory coupling. Its strength has been suggested as a biomarker to monitor different conditions and diseases. Some approaches have been proposed to quantify the RSA, but it is unclear which one performs best in specific scenarios. The main objective of this study is to compare seven state-of-the-art methods for RSA quantification using data generated with a model proposed to simulate and control the RSA. These methods are also compared and evaluated on a real-life application, for their ability to capture changes in cardiorespiratory coupling during sleep. Methods: A simulation model is used to create a dataset of heart rate variability and respiratory signals with controlled RSA, which is used to compare the RSA estimation approaches. To compare the methods objectively in a real-life application, regression models trained on the simulated data are used to map the estimates to the same measurement scale. Results and conclusion: RSA estimates based on cross entropy, time-frequency coherence and subspace projections showed the best performance on simulated data. In addition, these estimates captured the expected trends in the changes in cardiorespiratory coupling during sleep similarly. Significance: An objective comparison of methods for RSA quantification is presented to guide future analyses. Also, the proposed simulation model can be used to compare existing and newly proposed RSA estimates. It is freely accessible online