Residue decomposition and fate of nitrogen-15 in a wheat crop under different previous crops and tillage systems Alvarez, Carina Rosa; Alvarez, Roberto; Sarquis, Alejandra Nitrogen (N) management may be improved by a thorough understanding of the nutrient dynamics during previous-crop residue decomposition and its impact on fertilizer N fate in the soil-plant system. An experiment was conducted in the Argentine Pampas to evaluate the effect of maize and soybean as previouscrops and plow-till and no-till methods on N dynamics and 15N-labeled fertilizer uptake during a wheat growing season. Maize and soybean residues released N under both tillage treatments, but N release was faster from soybean residues and when residues were buried by tillage. Net immobilization of N on decomposing residues was not detected. A regression model that accounted for 92% of remaining N variability included time, previous crop, and tillage treatment as independent variables. The rapid residue decomposition with N release was attributed to the high temperatures of the agroecosystem. The recovery of 15N-labeled fertilizer in the wheat crop, soil organic matter, and decomposing residues was not statistically different between previous crop treatments or tillage systems. Crop uptake of fertilizer N averaged 52% across treatments. Forty percent of fertilizer N was removed in grains. Immobilization of labeled N on soil organic matter was substantial, averaging 34% of the 15N-labeled fertilizer retained, but was very small on decomposing residues, averaging 0.2-3.0%. Fertilizer N not accounted for at harvest in the soil-plant system was 12% and was ascribed to losses. Previous crop or tillage system had no impact on wheat yield, but when soybean was the previous crop, N content of grain and straw+roots increased. Discussion is presented on the potential availability of N retained in wheat straw, roots, and soil organic matter for future crops.

Accumulation and Elimination of Cr in Gills and Eggs by the freshwater crab Zilchiopsis collastinensis after experimental exposure Gagneten, Ana María; Imof, Alba; Gervasio, Susana Graciela Cr accumulation and elimination were studied in the freshwater crab Zilchiopsis collastinensis (Crustacea, Decapoda) exposed to 3 (T1) and 6 (T2) mg CrVI/L using 1000-L tanks with dechlorinated water and artificial sediment. The objectives of this study were to analyze the Cr-accumulating capacity of Z. collastinensis males and females in gills and eggs, as well as to relate this capacity with crab weight, and to determine the Bioconcentration Factor (BCF) in relation to water and sediment. Significant differences in Cr concentration were found between the control and T1 and T2 (p = 0.018 and p = 0.001), and between T1 and T2 (p = 0.025). Significant differences in Cr concentration were found among all treatments in gills (p < 0.0001) and eggs (p = 0.0247), and when comparing Cr concentration between gills and eggs (p= 0.0046), but not between females and males (p = 0.6035). The tissues/water and tissues/sediment BCF values increased with Cr concentration, but was always higher in relation to water than to sediment. No relationship was found between crab weight and Cr concentration (r = -0.025). The obtained results constitute a great contribution to the knowledge of Cr accumulation in freshwater crabs. We propose Z. collastinensis as biomonitor of aquatic systems contaminated with Cr.

Notas sobre los colectivos artísticos en América Latina: años 70 y 80 Longoni, Ana En esta apretada síntesis señalo algunas modalidades que adoptó la acción colectiva en el arte latinoamericano y distintos modos en que fue pensada su politicidad, siempre vinculada a estrategias de intervención en el espacio público. Podría remitirme a una profusa tradición de colectivos artísticos en Latinoamérica, remontándome a principios del siglo XX a los primeros agrupamientos fuertemente imbricados con proyectos políticos de corte emancipador, particularmente el movimiento anarquista. Es en la larga década de los sesenta, época en la que se entrecruzan horizontes de transformación de signo revolucionario o modernizador, cuando la idea del trabajo de creación y actuación colectiva se inscribe en una plataforma radicalmente alternativa de articulación del arte y la política. Entonces eclosionaron en varios países del continente potentes movimientos que irrumpieron en la escena artística implicando un quiebre definitivo con las concepciones instituidas del arte, el artista y el público. En muchas de sus manifestaciones es radicalmente puesta en cuestión la noción de autoría individual, asumiendo una firma colectiva e incluso promoviendo al espectador como activo partícipe del acto creador. Es en la larga década de los sesenta, época en la que se entrecruzan horizontes de transformación de signo revolucionario o modernizador, cuando la idea del trabajo de creación y actuación colectiva se inscribe en una plataforma radicalmente alternativa de articulación del arte y la política. Entonces eclosionaron en varios países del continente potentes movimientos que irrumpieron en la escena artística implicando un quiebre definitivo con las concepciones instituidas del arte, el artista y el público. En muchas de sus manifestaciones es radicalmente puesta en cuestión la noción de autoría individual, asumiendo una firma colectiva e incluso promoviendo al espectador como activo partícipe del acto creador.

Bioevaluation of 32P patch designed for the treatment of skin diseases Salgueiro, María Jimena; Duran, Hebe Alicia; Palmieri, Mónica Alejandra; Pirchio, Rosana; Medina, Vanina Araceli; Ughetti, Ricardo; Croci, Máximo; Nicolini, Jorge; Zubillaga, Marcela Beatriz Objective: The objective of this study was to design and evaluate a 32P patch for the treatment of skin diseases. Materials and Methods: The patch was prepared from chromic phosphate 32P and silicone. Bioelimination and biodistribution in healthy and treated animals, and the therapeutic efficacy of two treatment schemes (single dose and fractionated dose) in an animal model of skin cancer were studied. Results: Based on the bioelimination and biodistribution studies, no leakage of 32P from the patch was observed. The treated tumors reduced their mean diameter compared to controls. The single-dose therapeutic scheme showed a higher number of complete and partial remissions compared to the fractionated scheme. These results were confirmed by histopathological analysis of the samples. Conclusion: The 32P patch was designed and produced according to specifications for the treatment of superficial lesions of the skin. Although the 32P patch is an open source, it behaves like a sealed one for use in brachytherapy treatments.

Polygalacturonase activity and expression of related genes during ripening of strawberry cultivars with contrasting fruit firmness Villarreal, Natalia Marina; Rosli, Hernan Guillermo; Martinez, Gustavo Adolfo; Civello, Pedro Marcos Fleshy fruits soften during ripening mainly as a consequence of the catabolism of cell wall components. In strawberry (Fragaria × ananassa Duch), the depolymerization and solubilization of pectins increase during ripening and contribute to fruit softening. In the present paper, we report the cloning and expression analysis of two polygalacturonase (PG) putative cDNAs: FaPG1 and T-PG. The former seems to be the same sequence of previously reported PG in strawberry, while T-PG cDNA has a deletion of 85 bp that cause a frame shift and would produce an inactive protein. Measurement of total PG activity and expression of FaPG1 and T-PG were performed in strawberry cultivars with contrasting softening rates. The softest cultivar (Toyonaka) showed the higher total PG activity in all ripening stages analyzed. The analysis by RT-PCR revealed that both genes express in the three cultivars, though the expression pattern was different. In the firmer cultivars (Selva and Camarosa) the expression of T-PG was considerably higher than the expression of FaPG1, while the opposite occurred in the softest cultivar (Toyonaka). Therefore, the higher PG activity detected in Toyonaka correlates with the enhanced expression of FaPG1 gene, while the low PG activity found in the firm cultivars correlates with a higher expression of T-PG, a gene that could encode a truncated protein without PG activity. The influence of auxins on both the expression of PG genes and the total PG activity during strawberry fruit ripening was also analyzed.

Differential structure of the Thompson components of selfadjoint operators Fongi, Guillermina; Maestripieri, Alejandra Laura Different equivalence relations are defined in the set L(H)s of self- adjoint operators of a Hilbert space H in order to extend a very well known relation in the cone of positive operators. As in the positive case, for a G L(H)s the equivalence class Ca admits a differential structure, which is compatible with a complete metric defined on Ca. This metric coincides with the Thompson metric when a is positive.

Southern Hemisphere Early Cretaceous (Valanginian-Early Barremian) carbon and oxygen isotope curves from the Neuquén Basin, Argentina Aguirre-Urreta, Maria Beatriz; Price, Gregory D.; Ruffell, Alastair H.; Lazo, Dario Gustavo; Kalin, Robert M.; Ogle, Neil; Rawson, Peter F. The first carbon and oxygen isotope curves for the Valanginian to Early Barremian (Early Cretaceous) interval obtained from outcrops in the Southern Hemisphere are presented. They were obtained from well-dated (by ammonites) sediments from the Neuquén Basin, Argentina. Measurements were acquired by the innovative method of analysing fossil oyster laminae. The occurrence of the well-established mid-Valanginian positive carbon isotope excursion is documented, while less well-marked positive events may also correlate with peaks identified in the well-known successions of SE France. The mid-Valanginian positive carbon isotope event in the Neuquén Basin is possibly associated with organic-rich sediments. A similar relationship is seen in the European Alps and in oceanic cores in some areas of the world.

Functional entry of dengue virus into Aedes albopictus mosquito cells is dependent on clathrin-mediated endocytosis Acosta, Eliana Gisela; Castilla, Viviana; Damonte, Elsa Beatriz Entry of dengue virus 2 (DENV-2) into Aedes albopictus mosquito C6/36 cells was analysed using biochemical and molecular inhibitors, together with confocal and electron microscopy observations. Treatment with monodansylcadaverine, chlorpromazine, sucrose and ammonium chloride inhibited DENV-2 virus yield and protein expression, whereas nystatin, a blocker of caveolae-mediated endocytosis, did not have any effect. Using confocal microscopy, co-localization of DENV-2 E glycoprotein and the marker protein transferrin was observed at the periphery of the cytoplasm. To support the requirement of clathrin function for DENV-2 entry, overexpression of a dominant-negative mutant of Eps15 in C6/36 cells was shown to impair virus entry. The disruption of actin microfilaments by cytochalasin D also significantly affected DENV-2 replication. In contrast, microtubule disruption by colchicine treatment did not impair DENV-2 infectivity, suggesting that DENV-2 does not require transport from early to late endosomes for successful infection of mosquito cells. Furthermore, using transmission electron microscopy, DENV-2 particles of approximately 44-52 nm were found attached within electron-dense invaginations of the plasma membrane and in coated vesicles that resembled those of clathrin-coated pits and vesicles, respectively. Together, these results demonstrate for the first time that DENV-2 enters insect cells by receptor-mediated, clathrin-dependent endocytosis, requiring traffic through an acidic pH compartment for subsequent uncoating and completion of a productive infection.

The systematic position of Pteropus leucopterus and its bearing on the monophyly and relationships of Pteropus (Chiroptera: Pteropodidae) Giannini, Norberto Pedro; Cunha Almeida, Francisca; Simmons, Nancy B.; Helgen, Kristofer M. Pteropus is the most speciose genus in Pteropodidae, currently comprising 65 species in 18 species groups. Here we examine whether Pteropus as currently understood is monophyletic. We sequenced three nuclear genes (RAG-1, RAG-2 and vWF) totalling c. 3.0 kbp from 18 species of Pteropus representing 12 species groups, plus Acerodon celebensis and megachiropteran outgroups representing all other subfamilies and tribes. Separate and combined parsimony and maximum likelihood analyses recovered a clade containing Acerodon as sister to all Pteropus species to the exclusion of the Philippine endemic taxon ‘P. leucopterus’, rendering Pteropus paraphyletic. We propose the revalidation of Desmalopex Miller, 1907, an available generic name for leucopterus, adopting the name combination Desmalopex leucopterus (Temminck, 1853). We discuss implications of this result and anticipate further modifications of the classification of Pteropus.

Fully differential cross sections in single ionization of helium by ion impact: Assessing the role of correlated wave functions Ciappina, Marcelo Fabián; Cravero, Walter Ruben We study the effect of final state dynamic correlation in single ionization of atoms by ion impact analyzing fully differential cross sections (FDCS). We use a distorted wave model where the final state is represented by a Φ 2 type correlated function, solution of a non-separable three body continuum Hamiltonian. This final state wave function partially includes the correlation of electron-projectile and electron-recoil relative motion as coupling terms of the wave equation. A comparison of fully differential results using this model with other theories and experimental data reveals that inclusion of dynamic correlation effects have little influence on FDCS, and do not contribute to a better description of available data in the case of electronic emission out-of scattering plane.

Hydrogenation of crotonaldehyde on different Au/CeO2 catalysts Campo, Betiana Carla; Petit, Corinne; Volpe, María Alicia The gas-phase hydrogenation of crotonaldehyde was carried out at 120, 150, and 180 °C over Au catalysts supported on ceria with low and medium surface areas (150 and 80 m2 g-1, respectively). An initial deactivation period was observed, followed by a steady-state regime. Ethanol was the main product in the deactivation period, whereas crotyl alcohol, butanal, butanol, and condensation products were produced under steady-state conditions. The activity and selectivity to crotyl alcohol (in the 20-32% range) were lower than those for the high-surface area ceria catalysts studied previously [B. Campo, M. Volpe, S. Ivanova, R. Touroude, J. Catal. 242 (2006) 162]. Samples were characterized by TPR, XPS, TEM, and XRD. The analysis of catalytic and characterization results indicates that gold particles supported on low- and medium-surface area ceria were relatively large, and the promotional effect of Ce3+ species was not achieved for the corresponding catalysts. Moreover, under reductive conditions, sintering still increased gold particle size. © 2007 Elsevier Inc. All rights reserved.

Microbial Respiration in Soils of the Argentine Pampas after Metsulfuron Methyl, 2,4‐D, and Glyphosate Treatments Zabaloy, Maria Celina; Gomez, Marisa Anahi Short-term response of microbial respiration after treatment with different doses of the herbicides mesulfuronmethyl (MET), 2,4-D, and glyphosate (GLY) was studied in microcosms of soils collected in three agricultural sites of the Southerns Pampas region, Buenos Aires Argentina. The influence of diammonium phosphate on carbon dioxide evolution when applied with the highest doses of the herbicides, was also investigated. MET had no effect on microbial respiration of an acidic soil of San Roman (pH 6.06), even at the highest rate. However, MET inhibited microbial respiration in soils of Bordenave (pH 7.4) at rate of 0.1 mg /Kg soil. Low applications rates of GLY and 2,4-D, produced only transitory effects on CO2 evolution whereas the addition of highest doses of these herbicides stimulated microbial activity. On the other hand, trhe addition of fertilizer to soil treated with a high dose of GLY temporarily inhibited CO2 release.

Synthesis and modification of supports with an Alkylamine and their use in Albumin adsorption Gomez, Cesar Gerardo; Strumia, Miriam Cristina The morphological effect of polymeric networks (R) modified with terminal amino groups was studied on the adsorption of bovine serum albumin (BSA). Networks of ethylene glycol dimethacrylate and 2-hydroxyethyl methacrylate [poly (EGDMA-co-HEMA)] were synthesized by suspension polymerization, using different EGDMA contents and agitation speeds. These matrices were characterized by FTIR, mercury intrusion porosimetry, SEM, and swelling degree. The increase of the EGDMA concentration led to the formation of networks with the highest crosslinking degree and porosity. An earlier phase separation yielded a higher aggregation of rigid microspheres, also forming stable pore systems. The increase in coalescence frequency, together with the impeller speed, and the decrease of the stabilizer molecules led to an increment in drop size. Large fused aggregates of microspheres were formed with additional loss of small pores as the stirring was increased, attaining also a higher pore volume (Vp) and a slight decrease of the surface area. Once characterized, networks were activated with butanediolglycidyl ether (BDGE), and then reacted with hexamethylenediamine (HMDA) through coupling reaction. Only the RBDGE- HMDA networks synthesized with the highest EGDMA content and agitation speed showed BSA adsorption. Their base matrices exhibited a Vp higher than 1.4 mL/g, which allows easier protein diffusion into the support.

A computational study of ² JHH(gem) indirect spin-spin coupling constants in simple hydrides of the second and third periods Alkorta, Ibon; Provasi, Patricio Federico; Aucar, Gustavo Adolfo; Elguero, José Several theoretical methods have been used to compute ²JHH in neutral, anionic and cationic HXH hydrides, X being the 14 nuclei from Li to CI (28molecules). Since the calculations also provide ¹JXH spin‐spin coupling constants (SSCC), these have also been analyzed. The best results were obtained using Second-order polarization propagator approximation (SOPPA)/sadJ. The geminal coupling constants appear to be dependent on the electronegativity of the X-atom

GABAB receptors and glucose homeostasis: evaluation in GABAB receptor knockout mice Bonaventura, Maria Marta; Catalano, Paolo Nicolás; Chamson de Reig, Astrid; Arany, Edith; Hill, D.; Bettler, B.; Saravia, Flavia Eugenia; Libertun, Carlos; Lux, Victoria Adela R. GABA has been proposed to inhibit insulin secretion through GABAB receptors (GABABRs) in pancreatic β-cells. We investigated whether GABABRs participated in the regulation of glucose homeostasis in vivo. The animals used in this study were adult male and female BALB/C mice, mice deficient in the GABAB1 subunit of the GABABR (GABAB−/−), and wild types (WT). Blood glucose was measured under fasting/fed conditions and in glucose tolerance tests (GTTs) with a Lifescan Glucose meter, and serum insulin was measured by ELISA. Pancreatic insulin content and islet insulin were released by RIA. Western blots for the GABAB1 subunit in islet membranes and immunohistochemistry for insulin and GABAB1 were performed in both genotypes. BALB/C mice preinjected with Baclofen (GABABR agonist, 7.5 mg/kg ip) presented impaired GTTs and decreased insulin secretion compared with saline-preinjected controls. GABAB−/− mice showed fasting and fed glucose levels similar to WT. GABAB−/− mice showed improved GTTs at moderate glucose overloads (2 g/kg). Baclofen pretreatment did not modify GTTs in GABAB−/− mice, whereas it impaired normal glycemia reinstatement in WT. Baclofen inhibited glucose-stimulated insulin secretion in WT isolated islets but was without effect in GABAB−/− islets. In GABAB−/− males, pancreatic insulin content was increased, basal and glucose-stimulated insulin secretion were augmented, and impaired insulin tolerance test and increased homeostatic model assessment of insulin resistance index were determined. Immunohistochemistry for insulin demonstrated an increase of very large islets in GABAB−/− males. Results demonstrate that GABABRs are involved in the regulation of glucose homeostasis in vivo and that the constitutive absence of GABABRs induces alterations in pancreatic histology, physiology, and insulin resistance.

El teatro de la imagen: Poder, espacio público y mundo privado: La Gaceta Rosarina (1923-1930) Galassi, Gisela Elisabet; Garcia, Analia Veronica El análisis de la vida social y cultural de Rosario, en las postrimerías del siglo XIX y las primeras décadas del XX, supone la reflexión del proceso de transformación social y política que conmovió profundamente la sociedad rosarina y argentina en sí misma, desencadenando nuevas maneras y prácticas, tanto en la vida privada como en la pública. El presente trabajo se orientará a la indagación de la publicación de una revista local con alcance regional como fue La Gaceta Rosarina en los años veinte. El material central fue encontrado en la Biblioteca Argentina “Dr. Juan Alvarez” de la ciudad de Rosario, revista que inicia su marco temporal a partir enero de 1923 hasta octubre de 1930, a fin de visualizar cuál es el contexto de su aparición –teniendo en cuenta el proceso de modernización de la sociedad como así también del espacio urbano–. Se tenderá a reflexionar sobre los cambios experimentados por los rosarinos en su conjunto, por la burguesía y aquellos otros sectores que habían visto un mejoramiento económico significativo, respecto de su estilo de vida, al calor de aires modernizadores que supusieron, en primera instancia un aprendizaje, pasando luego a constituirse en hábitos y habitus. El eje consistirá en cómo se presenta ese diálogo de la burguesía local con los sectores medios de la sociedad, infundiéndole prácticas de refinamiento y moralización, al instaurar un espacio de distinción y legitimación social y política.

Age composition and feeding ecology of early juvenile Notothenia rossii (Pisces, Nototheniidae) at Potter Cove, South Shetland Islands, Antarctica Barrera Oro, Esteban; Winter, Debora J. Age and diet of 140 brown phase early juvenile Notothenia rossii specimens caught at Potter Cove from December 2005–March 2006 were studied. Fish were immature, in the range 8.5–21 cm TL and of age groups 1–2 (otolith/scale readings). The diet (F% and coefficient Q methods) was mainly benthic-demersal organisms with Gammaridean amphipods (primarily Gondogeneia antarctica) as the most frequent (F% = 98) and main prey (Q% = 97). The occurrence of algae, gastropods and harpacticoid copepods was high, but these organisms were secondary or occasional food. The importance of other benthic (bivalves, polychaetes, isopods) and pelagic (ostracods, calanoids, hyperiid amphipods, krill) prey was very low. Preference of larger fish for larger prey was evident. Stomach fullness analysis showed high food availability during the sampling period. Young stages of N. rossii are demersal, preying mainly on gammarideans and other invertebrates of the benthic community associated with macroalgae beds. The almost complete lack of plankton components in the diet of early juvenile fish suggests they do not migrate vertically to feed.

"De cuando las maestras eran bravas": un apunte sobre la violencia en las escuelas Gallo, Andrea Paola Desde hace ya un tiempo el tema de la violencia en las escuelas ha ocupado el centro de la escena pública. Como en un movimiento de retroalimentación, su presencia en los medios masivos de comunicación y la preocupación y el reclamo de la opinión pública han reforzado ampliamente la circulación de discursos en torno a la necesidad de "reimponer el orden en las escuelas"...

Miradas al patrimonio latinoamericano Mendez, Patricia Susana Este capítulo breve retoma la fotografía como elemento imprescindible para la revalorización y posterior recuperación del patrimonio arquitectónico a través del análisis de las imágenes de un arquitecto y fotógrafo de la talla de Ramón Paolini.

Pocos pero los mejores... Notas acerca de las prácticas asociativas del Club Español de Rosario, fines del siglo XIX y primeras décadas del XX Águila, Verónica; Caldo, Paula El presente artículo interroga los sentidos y las formas adquiridas por las prácticas asociativas en relación a la construcción de la identidad y a la transmisión de la cultura en un espacio de sociabilidad particular de la ciudad Rosario, el Club Español. En tal sentido, abordaremos tres cuestiones. En primer lugar, abriendo un paréntesis metodológico, esbozaremos una breve reflexión en torno a los significados de trabajar en los archivos de una asociación de carácter privada, como lo es el Club Español. En segundo lugar, definiremos las características del Club Español en tanto asociación étnica. Finalmente, rastrearemos los eventos, actos, celebraciones, etcétera, que provocan, a los socios del club, definirlo como una asociación cultural.