On the distortions in calculated GW parameters during slanted atmospheric soundings de la Torre, Alejandro; Alexander, Pedro Manfredo; Schmidt, Torsten; Llamedo Soria, Pablo Martin; Hierro, Rodrigo Federico The significant distortions introduced in the measured atmospheric gravity wavelengths by soundings other than those in vertical and horizontal directions, are discussed as a function of the elevation angle of the sounding path and the gravity wave aspect ratio. Under- or overestimation of real vertical wavelengths during the measurement process depends on the value of these two parameters. The consequences of these distortions on the calculation of the energy and the vertical flux of horizontal momentum are analyzed and discussed in the context of two experimental limb satellite setups: GPS-LEO radio occultations and TIMED/SABER ((Atmosphere using Broadband Emission Radiometry/Thermosphere-Ionosphere-Mesosphere-Energetics and Dynamics)) measurements. Possible discrepancies previously found between the momentum flux calculated from satellite temperature profiles, on site and from model simulations, may to a certain degree be attributed to these distortions. A recalculation of previous momentum flux climatologies based on these considerations seems to be a difficult goal.

Técnicas Paleontológicas Isasi, Marcelo Pablo; Brissón Egli, Federico Cuando recorremos las salas de exhibición delos museos de ciencias naturales solemos encontrarnosante magníficos ejemplares deanimales extinguidos de los que solo conocemossus esqueletos fósiles (o partes de ellos),montados de una manera que cautiva nuestra imaginación.Sin embargo, por lo general desconocemos el largocamino que debieron recorrer esos fósiles para quelos podamos apreciar en el museo. Ese camino comienzacon su hallazgo en el campo por los paleontólogos,normalmente en lugares remotos y a veces poco accesibles,y sigue con su extracción de los estratos geológicosen que se preservaron por millones de años, su trasladoa un centro de investigación o un museo, y su cuidadosapreparación, por la que se separan los huesos de la roca.Esto posibilita el detallado estudio anatómico y, en casode que los materiales estén bien preservados, su exhibiciónal público.

Discovery of novel bovine viral diarrhea inhibitors using structure-based virtual screening on the envelope protein E2 Bollini, Mariela; Leal, Emilse Soledad; Adler, Natalia Sol; Aucar, María Gabriela; Fernandez, Gabriela Araceli; Pascual, María José; Merwaiss, Fernando; Alvarez, Diego Ezequiel; Cavasotto, Claudio Norberto Bovine viral diarrhea virus (BVDV) is a member of the genus Pestivirus within the family Flaviviridae. BVDV causes both acute and persistent infections in cattle, leading to substantial financial losses to the livestock industry each year. The global prevalence of persistent BVDV infection and the lack of a highly effective antiviral therapy have spurred intensive efforts to discover and develop novel anti-BVDV therapies in the pharmaceutical industry. Antiviral targeting of virus envelope proteins is an effective strategy for therapeutic intervention of viral infections. We performed prospective small-molecule high-throughput docking to identify molecules that likely bind to the region delimited by domains I and II of the envelope protein E2 of BVDV. Several structurally different compounds were purchased or synthesized, and assayed for antiviral activity against BVDV. Five of the selected compounds were active displaying IC50 values in the low- to mid-micromolar range. For these compounds, their possible binding determinants were characterized by molecular dynamics simulations. A common pattern of interactions between active molecules and aminoacid residues in the binding site in E2 was observed. These findings could offer a better understanding of the interaction of BVDV E2 with these inhibitors, as well as benefit the discovery of novel and more potent BVDV antivirals.

Reactive oxygen species and nitric oxide are involved in polyamine-induced growth inhibition in wheat plants Recalde, Laura; Vazquez, Analia; Groppa, María Daniela; Benavides, Maria Patricia Polyamines (PAs) produce H2O2 and nitric oxide (NO) during their normal catabolism and modulate plant growth and development. To explore the biochemical basis of PAs-induced growth inhibition in Triticum aestivum L seedlings, we examined the role of O2·-, H2O2 or NO in shoot and root development. Although all PA treatments resulted in a variable reduction of root and shoot elongation, spermine (Spm) caused the greater inhibition in a similar way to that observed with the NO donor, sodium nitroprusside (SNP). In both cases, O2·- production was completely blocked whereas H2O2 formation was high in the root apex under SNP or Spm treatments. Catalase recovered root and shoot growth in SNP but not in Spm-treated plants, revealing the involvement of H2O2 in SNP-root length reduction. The addition of the NO scavenger, cPTIO, restored root length in SNP- or Spm-treated plants, respectively, and partially recovered O2·- levels, compared to the plants exposed to PAs or SNP without cPTIO. A strong correlation was observed between root growth restoration and O2·- accumulation after treating roots with SNP + aminoguanidine, a diamine oxidase inhibitor, and with SNP + 1,8-diaminoctane, a polyamine oxidase inhibitor, confirming the essential role of O2·- formation for root growth and the importance of the origin and level of H2O2. The differential modulation of wheat growth by PAs through reactive oxygen species or NO is discussed.

Distinguishing Quaternary glyptodontine cingulates in South America: How informative are juvenile specimens? Luna, Carlos; Cerda, Ignacio Alejandro; Zurita, Alfredo Eduardo; González, Romina; Prieto, María Cecilia; Mothé, Dimila; Avilla, Leonardo The subfamily Glyptodontinae (Xenarthra, Cingulata) comprises one of the most frequently recorded glyptodontids in South America. Recently, the North American genus Glyptotherium was recorded in South America, in addition to the genus Glyptodon. It has been shown that both genera shared the same geographic distribution in central-north and eastern areas of South America (Venezuela and Brazil, respectively). Although some characters allow differentiation between adult specimens of both genera, the morphological distinction between these two genera is rather difficult in juvenile specimens. In this contribution, a detailed morphological, morphometric and histological survey of a juvenile specimen of Glyptodontinae recovered from the Late Pleistocene of northern Brazil is performed. The relative lower osteoderms thickness, the particular morphology of the annular and radial sulci and the distal osseous projections of the caudal osteoderms suggest that the specimen belongs to the genus Glyptotherium. In addition, the validity of some statistical tools to distinguish between different ontogenetic stages and in some cases between genera is verified. The osteoderm microstructure of this juvenile individual is characterized by being composed of a cancellous internal coresurrounded by a compact bone cortex. Primary bone tissue mostly consists of highly vascularized, woven-fibered bone tissue. Unlike that observed in adult Glyptodontinae, both the Sharpey fibers and the fibrous and laminar parallel bone tissue as secondary bone are absent. This study enhances our knowledge about those morphological and histological changes that occur through the ontogeny in glyptodonts.

Círculos de tiza: Notas sobre exilio y enfermedad en Reinaldo Arenas León, Denise En su ensayo sobre literatura y enfermedad, Roberto Bolaño construye una tríada íntima de experiencia que nos guía a través de las motivaciones fundamentales que hay detrás de toda poesía y que está constituida ciertamente por los viajes, el sexo y los libros. Me propongo indagar en el presente trabajo cómo funciona esta tríada en la obra del cubano Reynaldo Arenas, especialmente en su autobiografía, Antes que anochezca, donde la enfermedad re direcciona la trayectoria del viaje. Si la fuga funciona como una constante que tensiona la obra y la vida de Arenas, en su autobiografía exilio y enfermedad se fusionan como signos intercambiables.; In his essay on literature and disease, Roberto Bolaño builds a trio arround intimate experiences that guides us through the fundamental motivations behind all poetry: travel, sex and books. I intend in this paper to research how this triad operates in the work of the Cuban writer Reynaldo Arenas, especially in his autobiography, Before Night Falls. Here, the disease redirects the path of traveling. If runaway functions as a constant in Arenas's works, in his autobiography desertion and disease look like interchangeable signs.

Physicochemical and rheological properties of mucilage extracted from Opuntia ficus indica (L. Miller): Comparative study with guar gum and xanthan gum Quinzio, Claudia Marcela; Ayunta, Carolina Anabel; Alancay, Matias Miguel; Lopez, Beatriz Alicia; Iturriaga, Laura Beatriz The physicochemical and rheological properties of aqueous solutions of the mucilage isolated from Opuntia ficus indica (L. Mill) at different concentration (0.5, 1, 1.5 and 4.5% w/v) were examined. The intrinsic viscosity [η] found for precipitate mucilage (PM) and dialyzed mucilage (DM) were 22.6 and 15.3 dl/g respectively. Electrophoretic measurements showed that the zeta potential of PM and DM was negative in all the pH range studied. PM reduced the surface tension of water and was concentration dependent. The surface activity of PM (57 mN/m) was similar to that of guar gum (55 mN/m) and xanthan gum (52 mN/m) at 1.5% (w/v) concentration. A non-Newtonian shear-thinning behavior was observed. The Ostwald–de Waele model successfully correlated the viscosity–shear rate. At equal hydrocolloid concentration, the consistency coefficients (k) of mucilage solutions were lower than those of guar gum (GG) and xanthan gum (XG). However, the consistency coefficient of a mucilage solution at 4.5% (w/v) (20.9 Pa s) was in the same order as that shown by GG at 1.5% (w/v) (28.8 Pa s) aqueous solution. No effects of pH and ionic strength on the viscosity of PM and DM were observed. The mechanical spectra showed a crossover point between G′ and G″ at low mucilage concentrations of 0.5 and 1% (w/v), exhibiting higher relaxation time than GG. The more concentrated solutions of PM and DM (1.5 and 4.5% w/v) displayed a predominant elastic behavior and did not meet the Cox-Merz rule, similarly to GX. The more concentrated solutions of PM and DM did not meet the Cox-Merz rule. This behavior would suggest the formation of colloidal aggregates.

Electrosorption of a modified electrode in the vicinity of phase transition: A Monte Carlo study Gavilán Arriazu, Edgardo Maximiliano; Pinto, Oscar Alejandro We present a Monte Carlo study for the electrosorption of an electroactive species on a modified electrode. The surface of the electrode is modified by the irreversible adsorption of a non-electroactive species which is able to block a percentage of the adsorption sites. This generates an electrode with variable connectivity sites. A second species, electroactive in this case, is adsorbed in surface vacancies and can interact repulsively with itself. In particular, we are interested in the analysis of the effect of the non-electroactive species near of critical regime, where the c(2 × 2) structure is formed. Lattice-gas models and Monte Carlo simulations in the Gran Canonical Ensemble are used. The analysis conducted is based on the study of voltammograms, order parameters, isotherms, configurational entropy per site, at several values of energies and coverage degrees of the non-electroactive species.

Manejo de malezas en pasturas perennes en base a leguminosas, con énfasis en el control de cardos Montoya, Jorgelina Ceferina; Berhongaray, Gonzalo; Romano, Nicolás F. La presencia de malezas en pasturas perennes en base a leguminosas provoca una baja eficiencia en la implantación, reduce la producción de materia seca y la calidad del forraje. El éxito del manejo integrado de malezas se basa en ajustar las estrategias de control al problema de malezas específico en el campo. Los productores deben saber, no únicamente, cuáles especies están presentes en el lote (y cuántas de ellas) sino que también deben entender la distribución y los estados de desarrollo de dichas malezas en el campo. La mayoría de los bancos de semilla están compuestos por diversas especies. El conocimiento de cuándo cada una de las especies emergen en el año es importante para planificar un efectivo programa de control de malezas. Cada especie tiene uno o más períodos de emergencia pudiendo variar el inicio de la emergencia de un año a otro dependiendo de las condiciones climáticas. Sin embargo, el orden de emergencia entre especies se mantiene relativamente constante. El grupo de los cardos es uno de los más problemáticos al momento de su manejo. Una de las principales características de estas especies es que en general no hay herbicidas residuales que ofrezcan un buen control preemergente, la mayoría de ellos son herbicidas postemergentes. Si bien éstos pueden ser muy eficaces, la baja eficacia preemergente de posteriores cohortes reduce la calidad de los tratamientos en el corto plazo. A los fines de aumentar la eficacia y eficiencia de dichos tratamientos postemergentes es de suma utilidad disponer de la información de los flujos de emergencia de las especies más frecuentes y problemáticas. De esta forma se logrará definir el momento más apropiado para la intervención postemergente con herbicidas.

Carvone-loaded LDPE films for active packaging: Effect of supercritical CO2-assisted impregnation on loading, mechanical and transport properties of the films Goñi, Maria Laura; Gañan, Nicolas Alberto; Martini, Raquel Evangelina; Andreatta, Alfonsina Ester In this work, low density polyethylene (LDPE) films were loaded by scCO2-assisted impregnation with R-(−)-carvone, the main component of M. spicata and A. polystachya essential oils with antimicrobial and insecticidal activity. Impregnation runs were performed in a lab-scale high-pressure cell, and the effect of CO2 density (240?700 kg m−3) and temperature (35?60 °C) on impregnation yield was evaluated. Impregnation yields of 2.0?4.8% (w/w) were obtained, achieving higher values at low CO2 density. Thermal and mechanical properties of the films, before and after impregnation, were also investigated. The diffusion coefficient of carvone in scCO2-swollen films was estimated by impregnating film rolls and modeling the concentration profile through the roll thickness using an analytical solution of second Fick´s law. Release profiles into air were determined, allowing to estimate diffusivity values in non-swollen films at ambient conditions.

Key acclimation responses to phosphorus deficiency in maize plants are influenced by exogenous nitric oxide Ramos Artuso, Facundo Antonio; Galatro, Andrea Verónica; Buet, Agustina; Santa Maria, Guillermo Esteban; Simontacchi, Marcela Silvia Improving phosphorus (P) acquisition and utilization in crops is of great importance in order to achieve a good plant nutritional state and maximize biomass production while minimizing the addition of fertilizers, and the concomitant risk of eutrophication. This study explores to which extent key processes involved in P-acquisition, and other acclimation mechanisms to low P supply in maize (Zea mays L.) plants, are affected by the addition of a nitric oxide (NO) donor (S-nitrosoglutathione, GSNO). Plants grown in a complete culture solution were exposed to four treatments performed by the combination of two P levels (0 and 0.5 mM), and two GSNO levels (0 and 0.1 mM), and responses to P-deprivation were then studied. Major plant responses related to P-deprivation were affected by the presence of the NO donor. In roots, the activity of acid phosphatases was significantly increased in P-depleted plants simultaneously exposed to GSNO. Acidification of the culture solution also increased in plants that had been grown in the presence of the NO donor. Furthermore, the potential capability displayed by roots of P-deprived plants for P-uptake, was higher in the plants that had been treated with GSNO. These results indicate that exogenous NO addition affects fundamental acclimation responses of maize plants to P scarcity, particularly and positively those that help plants to sustain P-acquisition under low P availability.

Configuraciones militantes contemporáneas. Una propuesta metodológica para pensar el compromiso político; Contemporary militant configurations. A methodological proposal to think about political commitment Aiziczon, Fernando Cristian En este artículo proponemos una manera posible de pensar la militancia política en su vínculo con el problema del compromiso político y la acción. Luego de presentar estas relaciones, problematizamos la idea de configuraciones militantes, sugiriendo parámetros de referencia aplicables al caso de la militancia de izquierdas en la Argentina contemporánea e interrogando sobre los quiebres y continuidades que habilitan el despliegue de formas de militancia en determinados contextos históricos. Trabajamos sobre la hipótesis de que el debate reciente sobre la violencia revolucionaria en las organizaciones políticomilitares de los años sesenta-setenta, superpuesto con las discusiones emergentes tras la crisis sociopolítica de 2001, señalarían las condiciones de posibilidad para la emergencia de una nueva configuración militante de carácter transicional en la época actual.
; In this article we propose a possible way of thinking about the political militancy in its connection with the problem of political commitment and action. After presenting these relations, we problematized the idea of militant configurations, suggesting reference parameters applicable to the case of leftist militancy in contemporary Argentina and questioning about the breakthroughs and continuities that enable the deployment of forms of militancy in certain historical contexts. We work on the hypothesis that the recent debate on revolutionary violence in political-military organizations of the 60s and 70s, superimposed on the discussions emerging after the socio-political crisis of 2001, it would indicate the conditions of a possibility for the emergence of a new militant configuration of a transitional nature in the current epoch.

Ticks (Acari: Ixodidae) of Nepal: First record of Amblyomma varanense (Supino), with an update of species list Pun, Shyam Kumar; Guglielmone, Alberto Alejandro; Tarragona, Evelina Luisa; Nava, Santiago; Maharjan, Mahendra Males and females specimens of Amblyomma were collected from Orthriophis hodgsoni (Squamata: Colubridae) caught during routine herpetological work in Kathmandu. Morphological characteristics led to the diagnosis of A. varanense, constituting the second Nepalese species for the genus after the collection of Amblyomma gervaisi, also from a colubrid snake, almost 100 years ago. Amblyomma varanense is the 55th species found in the country, and preceded for the collection of 21 species of Haemaphysalis, 14 Ixodes, 6 Rhipicephalus, 6 Hyalomma, 4 Dermacentor, 1 Amblyomma, 1 Anomalohimalaya and 1 species of Nosomma. Eleven and 19 species have been found on humans and domestic mammals, respectively, evidencing the medical and economic importance of Nepalese Ixodidae.

PI3K/Akt cooperates with oncogenic Notch by inducing nitric oxide-dependent inflammation Villegas, Santiago Nahuel; Gombos, Rita; García López, Lucia; Gutiérrez Pérez, Irene; García Castillo, Jesús; Vallejo, Diana Marcela; Da Ros, Vanina Gabriela; Ballesta Illán, Esther; Mihály, József; Dominguez, Maria The PI3K/Akt signaling pathway, Notch, and other oncogenes cooperate in the induction of aggressive cancers. Elucidating how the PI3K/Akt pathway facilitates tumorigenesis by other oncogenes may offer opportunities to develop drugs with fewer side effects than those currently available. Here, using an unbiased in vivo chemical genetic screen in Drosophila, we identified compounds that inhibit the activity of proinflammatory enzymes nitric oxide synthase (NOS) and lipoxygenase (LOX) as selective suppressors of Notch-PI3K/Akt cooperative oncogenesis. Tumor silencing of NOS and LOX signaling mirrored the antitumor effect of the hit compounds, demonstrating their participation in Notch-PI3K/Akt-induced tumorigenesis. Oncogenic PI3K/Akt signaling triggered inflammation and immunosuppression via aberrant NOS expression. Accordingly, activated Notch tumorigenesis was fueled by hampering the immune response or by NOS overexpression to mimic a protumorigenic environment. Our lead compound, the LOX inhibitor BW B70C, also selectively killed human leukemic cells by dampening the NOTCH1-PI3K/AKT-eNOS axis.

Overexpression of 11β-hydroxysteroid dehydrogenase 1 in visceral adipose tissue and underexpression of endothelial nitric oxide synthase in the adrenal cortex of dogs with hyperadrenocorticism Miceli, Diego Daniel; Abiuso, Adriana María Belén; Vidal, Patricia Noemi; Gallelli, Maria Florencia; Pignataro, Omar Pedro; Castillo, Victor Alejandro 11β-Hydroxysteroid dehydrogenase 1 (11β-HSD1) is an enzyme that activates cortisone into cortisol in tissues. Alterations in this enzyme are related to the development of metabolic syndrome, obesity and hyperadrenocorticism (HAC). Endothelial nitric oxide synthase (eNOS) produces nitric oxide and is related to the regulation of adrenal steroidogenesis. The aim of the study was to evaluate 11β-HSD1 and eNOS expression in dogs with HAC. Visceral adipose tissue samples were taken to evaluate 11β-HSD1 expression by immunohistochemistry and western blotting. In parallel, adrenal gland samples were collected to evaluate eNOS expression by immunohistochemistry. 11β-HSD1 expression was significantly higher in the adipocytes of dogs with HAC than in those of the control dogs. eNOS expression in the adrenal cortex (zona fasciculata) was significantly lower in the dogs with HAC than in the control dogs. 11β-HSD1 overexpression and eNOS underexpression could play a role in the maintenance of hypercortisolism in dogs with HAC.

Direct analysis of benzo[a]pyrene metabolites with strong overlapping in both the spectral and lifetime domains Alfarhani, Bassam; Al-Tameemi, Maha; Goicoechea, Hector Casimiro; Barbosa, Fernando Jr.; Campiglia, Andres D. The ultimate goal of the present study is to develop screening methodology for the urine analysis of metabolites of polycyclic aromatic hydrocarbons. The investigated approach is based on surface matrix fluorescence spectroscopy, where octadecyl silica membranes serve the dual purpose of metabolite extraction and solid substrate for fluorescence measurements. One of the main challenges faced by this approach is the interference of concomitants in the sample matrix. The present study focuses on three metabolites with strong spectral and lifetime overlapping, namely benzo[a]pyrene-trans-9,10-dihydrodiol, benzo[a]pyrene-r-7,t-8,c-9-tetrahydrotriol and benzo[a]pyrene-r-7,t-8,c-9,c-10-tetrahydrotetrol. As an attempt to improve spectral and lifetime resolution, time-resolved excitation emission matrices are recorded at 77 K with the aid of a cryogenic fiber optic probe and laser-based instrumentation. In comparison to conventional spectrofluorimeters, the use of laser-based instrumentation improves the limits of detection by approximately two-orders of magnitude. The fiber optic probe facilitates the collection of time-resolved excitation emission matrices for the detection of the three metabolites at the pg mL− 1 concentration level. Their accurate determination in urine samples of unknwon composition is only possible with the aid of unfolded-partial least squares/residual tri-linearization. This algorithm demonstrated to be well-equipped to handle strong overlapping in both the spectral and time domains.

Pesca con cebo activo por Ardea alba (Pelecaniformes: Ardeidae) en Argentina Sovrano, Lorena Vanesa; Beltzer, Adolfo Hector El comportamiento de pesca con cebo activo ha sido registrado en especies de la familia Ardeidae. Para la Garza Blanca (Ardea alba) sólo existe un registro previo en la literatura. Mediante este aporte se documenta el registro de pesca con cebo activo por la Garza Blanca observado en un Parque urbano de Argentina.

Óxido nítrico y factores relacionados a oxidación e inflamación como posibles biomarcadores de insuficiencia cardíaca; Nitric oxide and related factors linked to oxidation and inflammation as possible biomarkers of heart failure Bonafede, Roberto Jorge; Manucha, Walter Ariel Fernando Como enfermedad cardiovascular prevalente, la insuficiencia cardíaca es una de las principales causas de morbimortalidad prematura. Por ello, existe un especial interés sobre el estudio de marcadores eficientes asociados al riesgo y/o predicción de eventos cardiovasculares. En consecuencia se proponen a múltiples candidatos, pero sobresalen especialmente aquellos implicados en procesos oxidativos e inflamatorios propios de la enfermedad cardiovascular como el anión superóxido, óxido nítrico y peroxinitrito. En este sentido, existe una falta de conocimiento sobre las potenciales utilidades de estos sistemas como biomarcadores. La presente revisión procura contribuir a la mayor comprensión de estos sistemas para una mejor caracterización de pacientes. Por otra parte, un profundo conocimiento de estos complejos sistemas también permitiría proponer nuevas líneas de investigación para el desarrollo de inéditas herramientas terapéuticas como una auspiciosa frontera para el abordaje de esta patología.; As a prevalent cardiovascular disease, heart failure is one of the leading causes of morbidity and premature mortality. Therefore, there is a special interest in the study of efficient markers associated with risk and / or prediction of cardiovascular events. Multiple candidates are proposed, especially those involved in oxidative and inflammatory processes typical of cardiovascular disease, such as superoxide anion, nitric oxide, and peroxynitrite. There is a lack of knowledge on the potential usefulness of these systems as biomarkers. This review aims to contribute to a better understanding of these systems, as well as an improved patient profile. Furthermore, a deep knowledge of these complex systems would also allow proposing new lines of research for the development of new therapeutic tools as a promising start for new approaches to this disease.

Hydrogen sulfide increases production of NADPH oxidase-dependent hydrogen peroxide and phospholipase D-derived phosphatidic acid in guard cell signaling Scuffi, Denise; Nietzel, Thomas; Di Fino, Luciano Martin; Meyer, Andreas J.; Lamattina, Lorenzo; Schwarzlände, Markus; Laxalt, Ana Maria; Garcia-Mata, Carlos Hydrogen sulfide (H2S) is an important gaseous signaling molecule in plants that participates in stress responses and development. L-Cys desulfhydrase 1, one of the enzymatic sources of H2S in plants, participates in abscisic acid-induced stomatal closure. We combined pharmacological and genetic approaches to elucidate the involvement of H2S in stomatal closure and the interplay between H2S and other second messengers of the guard cell signaling network, such as hydrogen peroxide (H2O2) and phospholipase D (PLD)-derived phosphatidic acid in Arabidopsis (Arabidopsis thaliana). Both NADPH oxidase isoforms, respiratory burst oxidase homolog (RBOH)D and RBOHF, were required for H2S-induced stomatal closure. In vivo imaging using the cytosolic ratiometric fluorescent biosensor roGFP2-Orp1 revealed that H2S stimulates H2O2 production in Arabidopsis guard cells. Additionally, we observed an interplay between H2S and PLD activity in the regulation of reactive oxygen species production and stomatal movement. The PLDα1 and PLDδ isoforms were required for H2S-induced stomatal closure, and most of the H2S-dependent H2O2 production required the activity of PLDα1. Finally, we showed that H2S induced increases in the PLDδ-derived phosphatidic acid levels in guard cells. Our results revealed the involvement of H2S in the signaling network that controls stomatal closure, and suggest that H2S regulates NADPH oxidase and PLD activity in guard cells.

Efecto de la concentración y la aplicación de MTMO sobre acero electrocincado Seré, Pablo Ricardo; Egli, Walter Alfredo; Elsner, Cecilia Ines; Di Sarli, Alejandro Ramón; Deya, Marta Cecilia Los pretratamientos superficiales a base de silanos son una de las alternativas más convenientes para reemplazara los cromatos como protectores temporarios de sustratos metálicos expuestos a la acción de ambientesagresivos. El mecanismo de protección contra la corrosión, en el caso de los silanos es por efecto barrera, loque hace que características como porosidad, espesor y homogeneidad de la película tengan una marcadainfluencia sobre su eficacia[1, 2]. En el presente trabajo se estudió la capacidad protectora contra la corrosióndel mercaptopropiltrimetoxisilano (MTMO) sobre chapas de acero electrocincado, analizando la influenciade su concentración durante la aplicación y de la cantidad de capas aplicadas. Como pretratamiento, lasmuestras fueron desengrasadas por ultrasonido sumergiéndolas en tolueno durante 2 min a 40 ºC. La superficiede las muestras fue activada sumergiéndolas en una solución de NaOH al 10% p/v y aplicando una densidadde corriente catódica de 0,12 A/cm2, la temperatura se controló a 40 ºC. La solución de MTMO se preparóañadiendo 2 ó 4% v/v de MTMO a una solución de agua destilada/metanol (3:2 v/v, de pH 4 ajustado conácido acético) [3], y se hidrolizó durante 60 min; a algunas muestras se les aplicó una y a otras dos capas deMTMO. Posteriormente se curaron a 80 ºC durante 10 min. La porosidad se evaluó por voltametría cíclica [4]y por reacción al sulfato de cobre, la morfología y espesor mediante SEM-EDS, y el comportamiento frente ala corrosión mediante la obtención de curvas de polarización, espectrometría de impedancia electroquímica yexponiendo las muestras en cámara de humedad y temperatura controladas. De los resultados obtenidos puedeinferirse que la capacidad protectora aportada por dos capas de MTMO es mayor que la debida a un aumentode su concentración. Además, estas variables de proceso afectan tanto la morfología como el espesorde la película.