Recovery of Nickel and Zinc Using Biogenerated Sulphuric Acid Yagnentkovsky, Nadia; Viera, M.; Donati, Edgardo Ruben Sludge generated in automotive and related industries often contains heavy metals. Bioleaching is an attractive alternative for the treatment of metal containing solids. Bacteria of the genus Acidithiobacillus are the most important microorganisms applied to metal solubilisation. These microorganisms are able to produce sulphuric acid from the aerobic oxidation of elemental sulphur. The biogenerated sulphuric acid can be applied to the solubilisation of metals from a solid matrix. In this paper we present the results of our experiments aimed at the removal of nickel and zinc from sludge generated in the water treatment plant of an automotive industry. Acidithiobacillus thiooxidans cells were immobilised on sulphur pearls in a column reactor. The effects of sulphur pulp density and the dilution rate on the production of sulphuric acid were studied. In a second stage, sulphuric acid was used to solubilise the nickel and zinc from the sludge. The effects of different sludge pulp densities and initial acid pH were studied. High recoveries of zinc and nickel were obtained when the pH value of the sulphuric acid solution was lower than 2.0 for 1 and 2 % of pulp density.

Isolation of Mesophilic Sulphate-Reducing Bacteria from a Microbial Community: Comparative Study of the Effect of pH and Dissolved Heavy Metals on the Reduction of Sulphate Kikot, Pamela Alejandra; Viera, M.; Mignone, Carlos Fernando; Donati, Edgardo Ruben Metallurgical processes and mining are the main source of heavy metal contamination of water sources, rivers and lakes. There are a large number of physicochemical processes that can be applied for the immobilization of heavy metals from a liquid matrix. However, many of them are not particularly desirable because their low selectivity and inefficiency when high volumes of low metal concentration liquids must be treated. In such conditions, alternative biological processes have shown to be more useful than traditional physicochemical processes. One of those processes, bioprecipitation of metal sulphides is relevant due to the possibility of forming stable solids (very low solubility) with small volumes compared with other solids. This process is mediated by a broad group of organisms called sulphate reducers that are able to catalyze, under anaerobic conditions, the reduction of sulphate with organic compounds as electron donors. In this paper, we study the effect of the presence of various heavy metals and the pH on the ability to reduce sulphate by sulphate-reducing bacteria. We compare the reduction of sulphate by a microbial community obtained from the effluent of a tannery with a strain isolated from that community. Our results showed that sulphate reduction was significantly affected by pH changes whereas the presence of heavy metals did not show a significant effect. In addition, metal precipitation by the isolated strain was similar than that produced by the community.

PLAN DE ACCIÓN PARA LA CONSERVACIÓN DEL AGUARÁ GUAZÚ EN SANTA FE VERSIÓN 01 PERÍODO 2009 – 2014 Biassati, R; Larriera, Alejandro; Mosso, E.; Rozztti, J.C.; Moggia, L.; Pautasso, A.; Nebozuk, M. A.; Walker, C.; Ramirez, C.; Mirol, P.; Raimondi, Vanina Belén; Beldomenico, Pablo Martín; Eberhardt, María Ayelen Teresita; Manzzoli, D.; Correa, A.; Terragona, E.; Magni, C.; Alvarado, S.; Barengo, E. El presente plan fue realizado usando de base los capítulos 1, 2, 3 y 4 del trabajo: Estado  de  conocimiento  y  conservación  del  aguará  guazú  (Chrysocyon  brachyurus)  en  la  provincia  de Santa Fe, Argentina. . Se tomó como base orientaciones generales de Margoluis y Salafsky (1998) y en la estructura general se siguió de modelo práctico a Jiménez Pérez (2006). Para asignar la prioridad se utilizaron las categorías desarrolladas por el Instituto Brasileiro do Meio Ambiente e dos Recursos Naturais Renováveis (Baz Hughes, et al. 2006), estas son: Esencial: una actividad específica cuyo cumplimiento es necesario para evitar una declinación de las poblaciones que pueda llevar a la extinción de la especie en la naturaleza y/o en cautiverio. Alta: una actividad específica cuyo cumplimiento es necesario para evitar una declinación poblacional de más del 20% de una población en 20 años o menos. Media: una actividad específica cuyo cumplimiento es necesario para evitar una declinación poblacional de hasta el 20% de una población en 20 años o menos. Baja: una actividad específica cuyo cumplimiento es necesario para prevenir declinaciones poblacionales  locales o que se estima que dicha acción apenas tiene un pequeño impacto sobre las poblaciones en un área grande. Se trata de una planificación para cinco años pues la experiencia indica que a Santa Fe le falta mucho  trabajo  y experiencia para  fortalecer  su  forma de  ver  y de actuar en  la  recuperación de  las especies amenazadas.  Por ejemplo muchas de  las amenazas  indirectas (generadoras de amenazas directas) que afectan a esta especie son producto de  la  falta de coordinación, compromiso, metas y objetivos comunes entre  los profesionales de  la conservación, sea sociedad civil u organismos estatales. Es así como se pretende en un corto plazo y monitoreando constantemente, las acciones y sus resultados, lograr un plan a futuro de mediano y largo plazo.

Generation of tonalitic and dioritic magmas by coupled partial melting of gabbroic and metasedimentary rocks within the deep crust of the Famatinian magmatic arc, Argentina Otamendi, Juan Enrique; Ducea, Mihai N.; Tibaldi, Alina María; Bergantz, George W.; de la Rosa, Jesús D.; Vujovich, Graciela Irene The source regions of dioritic and tonalitic magmas have been identified in a deep crustal section of the Famatinian arc (Sierras Pampeanas of western Argentina). The source zones of intermediate igneous rocks are located at the transition between a gabbro-dominated mafic unit and a tonalite-dominated intermediate unit. In the upper levels of the mafic unit mafic magmas intruded into metasedimentary wall-rocks, crystallized mainly as amphibole gabbronorite and caused the partial melting of the surrounding metasediments. In turn, the leucogranitic melts sourced from the metasedimentary rocks intruded into the newly crystallized but still hot mafic layers and catalysed the process of partial melting of the gabbroic plutonic rocks. The gabbroic rocks became mafic migmatites comprising amphibole-rich pyroxene-bearing mesosomes and leucotonalitic veins. Significantly, most of the mafic migmatites have isotopic compositions [87Sr/86Sr(T) < 0.7063 and εNd(T) = -0.94 to +2.24] similar to those of the gabbroic rocks and distinct from those of their complementary leucotonalitic veins [87Sr/86Sr(T) = 0.7075-0.7126 and εNd(T) < -2.65], providing evidence for the idea that melting of the mafic rocks was triggered by the intrusion of leucogranitic anatectic melts [87Sr/86Sr(T) = 0.715 and εNd(T) = -6.21]. Mass-balance calculations show that the model reaction plagioclase + amphibole + leucogranitic melt → leucotonalitic melt + clinopyroxene ± orthopyroxene can better explain the partial melting of the gabbroic rocks. Based on field observations, we argue that the coalescence of leucotonalitic veins in the mafic migmatites led to breakdown of the solid matrix to form melt-dominated leucotonalitic pools. However, the leucotonalitic veins that crystallized before leaving behind the mafic migmatitic rock are chemically (elemental and isotopic) more evolved than the dioritic and tonalitic rocks. We envisage that once detached from their source region the leucotonalitic magmas were able to react, commingle and mix with entrained fragments of both mafic and metasedimentary rocks. This process gave rise to melts that became tonalitic and dioritic magmas. This study concludes that the generation of intermediate magmas is a multistage process with three critical steps: (1) influx and emplacement of hydrous mafic magmas into a deep crust containing metasedimentary country rocks; (2) physically and chemically coupled melting of mafic and metasedimentary rocks, leading to the formation of a leucotonalitic vein and dyke system that coalesces to form leucotonalitic or tonalitic magma bodies; (3) retrogression of the leucotonalitic magmas by partially assimilating entrained fragments of their mafic and metasedimentary precursors. The dimensions of the source zone seem to be insufficient to generate crustal-scale volumes of intermediate igneous rocks. However, the Famatinian paleo-arc crust would expose only those magma source zones that were still active during the tectonic closure of the arc. Ultimately, a time-integrated perspective indicates that early active source zones were cannibalized during the downward expansion of the plutonic bodies already dominated by intermediate plutonic rocks.

Optimization of the mechanical vapor compression (MVC) desalination process using mathematical programming Mussati, Sergio Fabian; Scenna, Nicolas Jose; Tarifa, Enrique Eduardo; Franco, Samuel; Hernandez, J.A. A mathematical model for the optimization of the mechanical vapor compression (MVC) desalination process is presented. The mathematical model involves the real physical constraints for the evaporation process. Nonlinear equations in terms of chemical?physical properties and design equations are used to model the process. A general algebraic modeling system (GAMS) is used to implement the model. The generalized reduced gradient algorithm CONOPT 2.041 is used as an NLP solver. The effects of some relevant process parameters on the system performance are studied. The output results from the proposed model were successfully compared with those of the literature.

Reinforced concrete wall as protection against accidental explosions in the petrochemical industry Ambrosini, Ricardo Daniel; Luccioni, Bibiana Maria In this paper the study of a reinforced concrete wall used as protection against accidental explosions in the petrochemical industry is presented. Many alternatives of accidental scenarios and sizes of the wall are analyzed and discussed. Two main types of events are considered, both related to vessel bursts: Pressure vessel bursts and BLEVE. The liberated energy from the explosion was calculated following procedures firmly established in the practice and the effects over the structures and the reinforced concrete wall were calculated by using a CFD tool. The results obtained show that the designed wall reduces the values of the peak overpressure and impulse and, as a result, the damage levels to be expected. It was also proved that a reinforced concrete wall can withstand the blast load for the considered events and levels of pressure and impulse, with minor damage and protect the buildings.

Surfactant-assisted lipopolysaccharide conjugation employing a cyanopyridinium agent and its application to a competitive assay Pallarola, Diego Andres; Battaglini, Fernando The activation of a lipopolysaccharide (LPS) with 1-cyano-4- dimethylaminopyridinium tetrafluoroborate (CDAP) in the presence of a surfactant allows an efficient conjugation with dansyl hydrazine or horseradish peroxidase (HRP) in an aqueous medium maintaining its biological activity. In order to promote the reaction a series of amphiphilic compounds were tested, sodium deoxycholate being the most suitable. The method presents several advantages: it is carried out in a mild environment, good conjugation ratios are obtained, it is suitable for any label bearing amino, hydrazine, or hydrazide groups, and the LPS endotoxic and HRP enzymatic activities are preserved. The HRP conjugate is applied in an amperometric competitive assay for the detection of lipopolysaccharides in an electrode array combined with a multipotentiostat able to carry out simultaneous determinations. The system is able to detect samples in concentrations as low as 100 pg mL-1 of LPS.

The role of histamine on cognition Alvarez Toro, Edgardo Orozimbo Histamine was intensively studied at the beginning of the 20th century because of its important role in allergic and inflammation processes. In those days it was very difficult that researchers could envisage another impacting function for the imidazolamine in the living systems. Once the imidazolamine was found located in neuron compartment in the brain, increasing evidence supported many regulatory functions including its possible role in memory and learning. The specific participation of histamine in cognitive functions followed a slow and unclear pathway because the many different experimental learning models, pharmacologic approaches, systemic and localized applications of the histamine active compounds into the brain used by researchers showed facilitating or inhibitory effects on learning, generating an active issue that has extended up to present time. In this review, all these aspects are analyzed and discussed considering the many intracellular different mechanisms discovered for histamine, the specific histamine receptors and the compartmentalizing proprieties of the brain that might explain the apparent inconsistent effects of the imidazolamine in learning. In addition, a hypothetical physiologic role for histamine in memory is proposed under the standard theories of learning in experimental animals and humans.

Cross-talk between rapid and long term effects of progesterone on vascular tissue Cutini, Pablo Hernan; Selles Tasa, Juana; Massheimer, Virginia Laura We tested the hypothesis whether; the non-genomic action of progesterone (Pg) on vascular tissue would be associated with hormonal long term effect on the modulation of cell growth. Using rat aortic strips, we showed that the stimulatory effect of Pg on nitric oxide synthesis involved both kinase and phosphatase pathways. The increase in the vasoactive production was prevented by the MAPK inhibitor (PD98059). In addition, preincubation with a phosphatase antagonist potentiated the hormonal effect. Pg increased PKC activity, but the inhibition of PKC did not alter the stimulatory action of the hormone on nitric oxide generation. In endothelial cell cultures (EC), 24 h treatment with Pg significantly diminished cell proliferation. This antiproliferative effect was suppressed by the PKC inhibitor chelerythrine (chel) and l-NAME (nitric oxide synthase inhibitor). We also observed that Pg stimulates EC migration. In summary, the present findings provide evidence of an integration of genomic and non-genomic effects in the mechanism of action displayed by Pg in vascular tissue. The fast effects elicited by the hormone implies signal transduction activation required for the regulation of vasoactive production, but also necessary for the modulation of endothelial cells growth.

Frictional and adhesive behavior of organic-inorganic hybrid coatings on surgical grade stainless steel using nano-scratching technique Ballarre, Josefina; López, Damián; Cavalieri, Ana Lia Because of their mechanical properties, metals are the most widely used materials as orthopaedic implants. However they cannot provide a natural bond with the mineralized bone and they also release metallic particles due to degradation or tribologic events. One way to improve the metallic implants performance is to apply protective organic-inorganic sol-gel coatings. In this work, stainless steel substrates are coated with films made by a sol-gel technique from organosilane precursors. Although mechanical properties of similar films have been studied, there is no information about adhesion, friction or deformation processes of silica-based hybrid films to stainless steel substrates. Hybrid coatings with higher amount of inorganic components (called TMH) have almost no elastic response and the debris due to chipping or delamination does not persist into the indentation trace. With the film with high content of organic compounds was found elastic recovery in early stages of loading and there is evidence of pile-up at the edges of the trace with higher load applied. After the unloading the film has a persistent deformation and is removed due to the asynchronic recovery of the film and the substrate. The combined two-film coating shows a lot of debris in the trace. This is an unusual but possible behavior of polymeric coatings and could be attributed to different recoveries between the first inorganic layer (called TEOS-MTES), the substrate and the upper TMH film. This fact produces delamination and crack formation in the TEOS-MTES coating, inducing tensile efforts, and finally the upper film is pulled-off. © 2009 Elsevier B.V. All rights reserved.

Visibilidad y conflicto: algunas imágenes de las organizaciones de trabajadores de Call Centers en Córdoba Lisdero, Pedro Matías En este artículo se propone reconstruir de manera introductoria una primera imagen de la acción colectiva que cobra visibilidad a través de dos organizaciones de trabajadores de Call Centers en la ciudad de Córdoba: El Sindicato de Teleoperadores y la Asociación de Trabajadores de Centros de Contactos y Afines de Córdoba. Propone identificar algunas redes de conflictos vinculadas a la transformación del mundo del trabajo como vía de ingreso a la comprensión de misma.

The challenge of rangeland degradation in a temperate semiarid region of Argentina: the Caldenal Fernandez, Osvaldo Alberto; Gil, María Elena; Distel, Roberto Alejandro The phytogeographical region known as the Caldenal comprises an area of approximately 10 million ha in the central temperate part of Argentina (35–40° S, 62–66° W). The original physiognomy of the vegetation consisted of a gramineous steppe with isolated shrubs and trees. Rangeland deterioration was initiated in the early-1900s with the introduction of livestock by the colonizing European ranchers. After a few decades of inappropriate use, the Caldenal proved to be a fragile environment. Major environmental impacts were: (a) The replacement of the most abundant palatable grasses Poa ligularis, Stipa clarazii, S. tenuis, Piptochaetium napostaense and Digitaria californica by low nutritive unpalatable grasses such as Stipa gynerioides, S. tenuissima, S. ambigua, S. bracychaeta and Elyonurus muticus; (b) The conversion of extensive areas dominated by grasses to a scrubland. There, frequent species are: Condalia microphylla, Lycium chilense, Prosopis alpataco, Larrea divaricata and Chuquiraga erinacea; (c) Depletion of plant cover resulting in incipient but increasing soil erosion in extensive areas. With the purpose of reversing this situation, the remit initiated 25 years ago was to develop management guidelines conducive to sustainable productivity while preserving the natural resources of the region. This work provides a comprehensive assessment of the impact of major stresses (drought, herbivory, fire) on grass and shrub responses, as well as more basic studies on the ecophysiology of these species. We have gained knowledge which is extremely useful to initiate rangeland utilization based on scientific information, facilitating increased sustainable rangeland productivity while preserving the natural resources.

Iterative design of dynamic experiments in modeling for optimization of innovative bioprocesses Cristaldi, Mariano Daniel; Grau, Ricardo José Antonio; Martínez, Ernesto Carlos Finding optimal operating conditions fast with a scarce budget of experimental runs is a key problem to speed up the development and scaling up of innovative bioprocesses. In this paper, a novel iterative methodology for the model-based design of dynamic experiments in modeling for optimization is developed and successfully applied to the optimization of a fed-batch bioreactor related to the production of r-interleukin-11 (rIL-11) whose DNA sequence has been cloned in an Escherichia coli strain. At each iteration, the proposed methodology resorts to a library of tendency models to increasingly bias bioreactor operating conditions towards an optimum. By selecting the ‘most informative’ tendency model in the sequel, the next dynamic experiment is defined by re-optimizing the input policy and calculating optimal sampling times. Model selection is based on minimizing an error measure which distinguishes between parametric and structural uncertainty to selectively bias data gathering towards improved operating conditions. The parametric uncertainty of tendency models is iteratively reduced using Global Sensitivity Analysis (GSA) to pinpoint which parameters are keys for estimating the objective function. Results obtained after just a few iterations are very promising.

La resistencia de la agricultura familiar tradicional en el Chaco, Argentina; The resistance of traditional family agriculture in El Chaco, Argentina Valenzuela, Cristina Ofelia; Scavo, Ángel Vito En este artículo se analiza la resistencia de los esquemas agrícolas tradicionales de tipo familiar a las transformaciones implícitas en la evolución tecnológica y los nuevos modelos de organización de la producción agrícola. Esta resistencia se analiza en sus manifestaciones individuales y colectivas y en su propósito de rescate y permanencia de una identidad productiva, construida en torno a prácticas y agentes específicos en una provincia periférica argentina.; This article analyses the resistance of traditional family agricultural schemes to the implicit transformations of technological evolution and new organisation models of agricultural production. This resistance is analysed in its individual and collective manifestations, as well as from the point of view of its purposes of rescue and permanence of a productivity identity, built upon practices and specific agents in a peripheral province of Argentina.

Caracterización de cúmulos abiertos a través de correlaciones cruzadas con librerías de espectros Maia, F. F. S.; Santos Jr, Joâo F. C.; Corradi, W. J. B.; Piatti, Andres Eduardo We present a characterization method based on spectral cross-correlation to obtain the physical parameters of the controversial stellar aggregate ESO 442-SC04. The data used was obtained with GMOS at Gemini-South telescope. Spectral types, effective temperature, suface gravity and metallicities parameters were determined using FXCOR to correlate cluster spectra with ELODIE spectral library and selecting the best correlation matches using the Tonry and Davis Ratio (TDR). Analysis of the results suggests that the stars in ESO 442-SC04 are not bound and therefore they do not constitute a physical system.; En este trabajo presentamos un m´etodo de caracterizacion basado en la correlacion cruzada de espectros de estrellas en el controvertido objeto ESO 442-SC04. Utilizamos espectros obtenidos con el multiespectrografo GMOS del telescopio Gemini Sur. Determinamos tipos espectrales, velocidades radiales, temperaturas efectivas y gravedades superficiales empleando la tarea FXCOR de IRAF, para correlacionar los espectros estelares observados con los de la librerıa ELODIE, en combinacion con la razon Tonry-Davis para seleccionar el mejor ajuste. Un analisis de los resultados sugiere que las estrellas observadas en ESO 442- SC04 no constituyen un sistema fısico.

Partitioning of Carboxylic Acid Between Oil and Water Phases: Experimental, Correlation, and Prediction Campanella, Alejandrina; Mandagaran, Beatriz Adriana; Campanella, Enrique Angel Partition coefficients for the carboxylic acids (A) acetic and formic acids between oil and water were measured, correlated, and predicted. The experiments were conducted by equilibrating the systems, soybean oil (SO)– H2O–A and fatty acid methyl ester (FAME)–H2O–A, at 40 ºC employing different compositions. The partition coefficients were correlated using the UNIQUAC model and, also, predicted by calculating the activity coefficients of the carboxylic acid in the two phases using a group contribution method, the UNIFAC equation. Agreement of experimental partition coefficients values with those estimated by UNIFAC are fair. Other experimental data from literature were also correlated and are discussed.

A comparative analysis of the temperature behavior and multiple tropopause events derived from GPS, radiosonde and reanalysis datasets over Argentina, as an example of Southern mid latitudes Lakkis, Susan Gabriela; Canziani, Pablo Osvaldo Investigaciones recientes sobre climatología de la estructura térmica y parámetros de tropopausa en los trópicos, basadas en radiosondas, datos de satélite y productos de reanálisis, muestran una buena concordancia entre los radiosondeos (RS) y los datos derivados de ocultaciones, como las radio ocultaciones del GPS (GPS RO), y los reanálisis. Sin embargo, en la región meridional extratropical, especialmente en latitudes medias y altas, a menudo hay considerables diferencias en los perfiles de temperatura al ir aumentando la latitud, dependiendo de la variabilidad de la altura y evolución de la tropopausa. El propósito del presente trabajo es mostrar el comportamiento de los perfiles de temperatura obtenidos de las ocultaciones GPS y los perfiles diarios y mensuales de reanálisis derivados del ERA 40 comparados con los valores de radiosondeo para eventos detectados en Argentina, como ejemplo de latitudes entre 30◦ y 60◦ sur, durante el período 2001-2002. Por otro lado, el estudio analiza también parámetros como la temperatura, altura y presión de los niveles significativos de radiosondeo y de las ocultaciones con el fin de analizar la existencia de eventos con simple y múltiple tropopausa. Los resultados obtenidos de la comparación entre las diferentes bases de datos muestran que en la mayoría de los casos las ocultaciones proveen perfiles de temperatura semejantes a aquellos graficados a partir de datos de radiosondeo, en contraposición a los obtenidos a partir de los productos de reanálisis, tanto diarios como mensuales. No obstante es posible observar que las diferencias entre las RO y los RS son más notorias para alturas superiores a los niveles de tropopausa, mientras que decrecen en la troposfera. Relacionado con los eventos de múltiple tropopausa, el análisis realizado muestra que los valores de temperatura y altura de la tropopausa de las RS y las RO son semejantes cuando sólo es considerada la LRT1, con diferencias crecientes a medida que las estaciones analizadas están ubicadas en latitudes más altas. A pesar de esta concordancia para la LRT1, los resultados muestran que solo los datos procedentes de radiosondeos son capaces de detectar eventos con LRT2 y LRT3.; Recent research on climatologies for temperature structure and tropopause parameters in the tropics, based on radiosonde, satellites data and model reanalysis show good agreement between radiosonde (RS) and data derived from remote sounding, such as GPS Radio Occultation (GPS RO), and reanalysis. The agreement is remarkably good over and immediately near the tropics. However, in the southern extra tropical region, especially at medium and high latitudes, there are often considerable differences in the temperature profiles as latitudes increases, which depends on the variability of location and evolution of the tropopause. The purpose of this work is to compare the behaviour of temperature profiles derived from GPS RO, daily and monthly ERA 40 reanalysis means and nearby radiosonde measurements in the southern extra tropical region. Argentina serves as an example of latitudes between 30◦ - 60◦S. The data covers 2001-2002 and analyses parameters such as temperature, pressure, and height derived rom radiosonde and satellite data in order to detect single and multiple tropopause events. The results show that in most cases are GPS RO more closely related to RS measurements than to reanalysis profiles, both for daily values, monthly means and their standard deviations. However, GPS RO deviations increase with respect to RS for heights above the tropopause, i.e., in the stratosphere, and decrease into the troposphere. Radiosonde and GPS appear to be in good agreement for tropopause temperatures and heights estimates when a single tropopause (LRT1) is considered, but with decreasing agreement as latitudes increase. Furthermore, while single and double tropopause events can be detected in RS observations this is less common for the GPS RO retrievals.

10 ausentes del Patrimonio: El Patrimonio demolido. Imaginar otra Buenos Aires a través de las fotografías Gutiérrez, Ramón; Mendez, Patricia Susana El texto resulta un análisis de diversos objetos arquitectónicos de valor en el contexto urbano porteño ya desaparecidos y que se rescatan a través de la fotografía. La idea fue el producir una toma de conciencia sobre el valor de la arquitectura a nivel patrimonial y también del valor de la fotografía como documento acabado de la historia arquitectónica y urbana.

Nitric oxide sensitive-guanylyl cyclase subunits expression changes during estrous cycle in anterior pituitary glands Cabilla, Jimena Paula; Ronchetti, Sonia Alejandra; Nudler, Silvana Iris; Miler, Eliana Andrea; Quinteros, Alnilan Fernanda; Duvilanski, Beatriz Haydee 17β-Estradiol (E2) exerts inhibitory actions on the nitric oxide pathway in rat adult pituitary glands. Previously, we reported that in vivo E2 acute treatment had opposite effects on soluble guanylyl cyclase (sGC) subunits, increasing α1- and decreasing β1-subunit protein and mRNA expression and decreasing sGC activity in immature rats. Here we studied the E2 effect on sGC protein and mRNA expression in anterior pituitary gland from adult female rats to address whether the maturation of the hypothalamus-pituitary axis influences its effects and to corroborate whether these effects occur in physiological conditions such as during estrous cycle. E2 administration causes the same effect on sGC as seen in immature rats, and these effects are estrogen receptor dependent. These results suggest that E2 is the main effector of these changes. Since the sGC α-subunit increases while the sGC activity decreases, we studied if other less active isoforms of the sGC α-subunit are expressed. Here we show for the first time that sGCα2 and sGCα2 inhibitory (α2i) isoforms are expressed in this gland, but only sGCα2i mRNA increased after E2 acute treatment. Finally, to test whether E2 effects take place under a physiological condition, sGC subunit expression was monitored over estrous cycle. sGCα1, -β1, and -α2i fluctuate along estrous cycle, and these changes are directly related with E2 level fluctuations rather than to NO level variations. These findings show that E2 physiologically regulates sGC expression and highlight a novel mechanism by which E2 downregulates sGC activity in rat anterior pituitary gland. Copyright © 2009 the American Physiological Society.

The multimeric structure of polycystin-2 (TRPP2): Structural - Functional correlates of homo- and hetero-multimers with TRPC1 Zhang, Peng; Luo, Ying; Chasan, Bernard; González Perrett, Silvia; Montalbetti, Nicolas; Timpanaro, Gustavo A.; Cantero, Maria del Rocio; Ramos, Arnolt J.; Goldmann, Wolfgang H.; Zhou, Jing; Cantiello, Horacio Fabio Polycystin-2 (PC2, TRPP2), the gene product of PKD2, whose mutations cause autosomal dominant polycystic kidney disease (ADPKD), belongs to the superfamily of TRP channels. PC2 is a non-selective cation channel, with multiple subconductance states. In this report, we explored structural and functional properties of PC2 and whether the conductance substates represent monomeric contributions to the channel complex. A kinetic analysis of spontaneous channel currents of PC2 showed that four intrinsic, non-stochastic subconductance states, which followed a staircase behavior, were both pH- and voltage-dependent. To confirm the oligomeric contributions to PC2 channel function, heteromeric PC2/TRPC1 channel complexes were also functionally assessed by single channel current analysis. Low pH inhibited the PC2 currents in PC2 homomeric complexes, but failed to affect PC2 currents in PC2/TRPC1 heteromeric complexes. Amiloride, in contrast, abolished PC2 currents in both the homomeric PC2 complexes and the heteromeric PC2/TRPC1 complexes, thus PC2/TRPC1 complexes have distinct functional properties from the homomeric complexes. The topological features of the homomeric PC2-, TRPC1- and heteromeric PC2/TRPC1 channel complexes, assessed by atomic force microscopy, were consistent with structural tetramers. TRPC1 homomeric channels had different average diameter and protruding height when compared with the PC2 homomers. The contribution of individual monomers to the PC2/TRPC1 hetero-complexes was easily distinguishable. The data support tetrameric models of both the PC2 and TRPC1 channels, where the overall conductance of a particular channel will depend on the contribution of the various functional monomers in the complex.