Cisplatin inhibits testosterone synthesis by a mechanism that includes the action of reactive oxygen species (ROS) at the level of P450scc Mori Sequeiros, María de Las Mercedes; Acquier, Andrea Beatriz; Suárez, Guadalupe Verónica; Gómez, Natalia; Gorostizaga, Alejandra Beatriz; Mendez, Carlos Fernando; Paz, Cristina del Valle Cisplatin (Cs) is a chemotherapeutic agent able to generate reactive oxygen species (ROS) which are linked to several side effects of the drug. Even when it is known that Cs produces Leydig cell dysfunction, it is unknown whether this particular side effect is mediated by ROS. The aim of this study was to evaluate the in vitro effects of Cs on testosterone production and the participation of ROS in this effect. We demonstrate that Cs promotes the generation of ROS in a time-, and concentration-dependent fashion, not only in mouse testicular interstitial cells but also in MA-10 Leydig cells. Also, Cs inhibits testosterone synthesis in a concentration-dependent fashion (5–50 μM for 4 h) and to a similar extent, in cells exposed to human chorionic gondadotropin hormone (hCG), to an analog of the second messenger cAMP (8Br-cAMP) or to a freely diffusible cholesterol analog (22R-hydroxycholesterol). However, this treatment does not inhibit the conversion of pregnenolone to testosterone. These data suggest that Cs exerts its inhibitory action on testosterone synthesis by an action at the level of P450scc. We also demonstrated that an antioxidant impairs the inhibitory effect of Cs on the conversion of the cholesterol analog into pregnenolone and that Cs does not change the expression level of P450scc mRNA. Therefore, it is concluded that Cs inhibits testosterone synthesis by a mechanism that includes the inhibition of P450scc by ROS.

¿Intensificación? En el aprovechamiento de aves entre los cazadores-recolectores-pescadores de la región del canal Beagle Tivoli, Angelica Montserrat Se discute aquí el carácter de los procesos de cambio relativos al aprovechamiento de aves en la región del canal Beagle que tuvieron lugar en momentos recientes de la secuencia de ocupación (a partir de aproximadamente 1500 años AP). Se ha señalado la existencia de un proceso de intensificación vinculado a la pesca hacia momentos tardíos, mientras que con respecto a la explotación de aves se halló una reorientación en su aprovisionamiento para el mismo período, caracterizada por tres factores principales: aumento proporcional de los restos de aves frente a otros recursos de mayor rédito calórico, formación de conjuntos con presencia casi exclusiva de restos de cormoranes en sitios con emplazamientos particulares y el incremento en la utilización de aves pelágicas (en particular Procellariiformes). En este trabajo se analiza si estas tendencias de cambio en la explotación de aves pueden o no entenderse como parte de una reorganización de la subsistencia más amplia, orientada hacia la intensificación en la captura de ciertos recursos.; We discuss here the nature of the processes of change concerning the use of birds in the region of the Beagle Channel, which took place in recent times of the prehistoric sequence of occupation (from about 1500 years BP). It is pointed out the existence of an intensification process linked to fishing in late moments. Meanwhile, with respect to the use of birds, variations have been found for the same period, characterized by three main factors: proportional increase of bird remains compared to other resources of higher return rates (e.g.: pinnipeds, guanacos); sites with almost exclusive presence of cormorants bones and the increase in the use of pelagic birds (Procellariiformes in particular). This paper examines whether these trends of change in the use of birds may or may not be understood as part of a broader reorganization of subsistence oriented towards intensification in the exploitation of certain resources.

Phenotypic variations between non-transgenic and transgenic maize hybrids Laserna, María Paula; Maddonni, Gustavo Angel; Lopez, Cesar Gabriel The use of transgenic maize (Zea mays, L.) hybrids (Bt, RR, Bt-RR) has simplified crop husbandry, mainly due to a more effective control of pests and weeds. The effects of transgenes insertion on phenotypic traits of maize hybrids are not fully documented, especially without the incidence of pests and weeds. The objectives of this work were to (i) establish phenotypic differences in terms of phenology, growth and yield among single cross conventional maize hybrids and their transgenic versions (Bt, RR and Bt-RR) and (ii) analyze the impact of light stress on inter-plant variability of the different traits under study. Field experiments were conducted in Buenos Aires (34º 36´ S, 58º 26´ W), Argentina during 2008-2009 (Exp 1), 2009-2010 (Exp 2) and 2010-2011 (Exp 3). Genotypes were cultivated at contrasting plant densities (6 and 12 pl m-2 in Exp1 and Exp2, and with 4 inter-plant spaces within the row in Exp3), irrigated, without nutrient limitations, and with chemical and mechanical controls of weed and animal pests. Phenotypic variability of several traits between groups of hybrids and between versions within each group was recorded. Some of these differences were independent of plant density and/or the environment of each experiment while others were detected only under some conditions. For example, the RR versions of both group of hybrids, had the shortest thermal times to anthesis and silking. At high density, DK747MGRR and DK190RR exhibited the largest plant growth rates (PGRCP), the highest inter-plant variability of this trait and the highest ear growth rates during the critical period (EGRCP) for kernel set. However, both genotypes had a low reproductive efficiency (i.e. kernel number per unit of EGRCP), that counterbalanced the high EGRCP. Consequently, the different versions of each group of hybrids had a similar kernel number per plant. We conclude that the introduction of transgenes may alter in some way, the behaviour of plants in different eco-physiological aspects in the absence of pests and weeds.

Determination of chemical oxygen demand by a flow injection method based on microwave digestion and chromium speciation coupled to inductively coupled plasma optical emission spectrometry Almeida, César Américo; González, Martín Germán; Mallea, Miguel Angel; Martinez, Luis Dante; Gil, Raul Andres The present paper evaluates the applicability of a new FIA system for COD determination. The new system, flow injection microwave solid phase extraction by means of activated carbon (FI-MW-SPE), consists of a digestion circuit, placed in a home MW oven, coupled to an ICP-OES spectrophotometer. Doehlert experimental design was used to speed up the optimization of different experimental variables studied for assisted digestion methods. The method provided a high throughput of about 18 samples h−1. To assess the accuracy of analytical methods linear regression, elliptic joint confidence region (EJCR) was used. A large linear range of 2.78?850 mg O2 L−1 with an excellent detection limit of 0.94 mg O2 L−1 was obtained. The interference by high chloride concentration was studied, and values below 3000 mg Cl− ions L−1, allowed the estimation of COD load without any masking agents. COD values for various types of wastewater samples were correlated with those obtained by standard manual methods. Moreover, interferences due to matrix nature are absent; since matrix is washed out of the column before Cr (III) is eluted. This method reduces the time, reagent volume, hazardous emission, external contamination, with a good reproducibility and accuracy.

Characterization of physicochemical properties of perfluorodecanoic acid–polyquaternium cellulose hydrogel Bierbrauer, Karina Lilian; Alasino, Roxana Valeria; Strumia, Miriam Cristina; Beltramo, Dante Miguel We investigated the nature and stability of the interactions established between polyquaternium (PQ10) and perfluorodecanoic acid (PFDA) in terms of different variables such as composition, ionic strength, pH and temperature. The PQ10–PFDA complex formation is interpreted in view of electrostatic associations between carboxylic and quaternary amino group. The properties of the systems were characterized by rheology analysis. The adhesive properties of complex were also assessed. One of the macroscopic features of the new material formed in solution was the increase in viscosity from 6 Pa s for 1% PQ10 (MW 1.7 × 106 g mol−1) to about 1000 Pa s by the addition of enough PFDA to reach 1:0.5 ammonium:carboxylic group molar ratio. At this proportion, PQ10 and PFDA form a network structure with a maximum viscosity and storage modulus. This maximum coincides with an increased mucoadhesive work.

Caminos y paisajes en la costa del Pago Grande: sondeos en la Casa Oks, Martínez Schavelzon Chavin, Daniel Gaston; Frazzi, Patricia; Silveira, Mario Las excavaciones realizadas en la zona de la barranca antigua al río en donde se han conservado casi sin alteraciones, permitió encontrar un antiguo camino hecho con fragmentos de ladrillos que bajaba al río. Luego fue cubierto intencionalmente. Se analiza el tema de la prohibición de caminos que permitieran usar los terrenos realengos y los conflictos que sucitaron.

Peronismo y “socialismo nacional”: La politica de expropiaciones durante el gobierno de Miguel Ragone: El caso de -Minas de Unchimé/Altos Hornos Güemes y Frigorífico Arenales. Salta, 1973-1974; Peronismo and “socialismo nacional”: Expropiation policies during Miguel Ragone's government: The case of -Minas de Unchimé/Altos Hornos Güemes y Frigorífico Arenales. Salta, 1973-1974 Soler Carmona, Alejandra; Correa, Rubén Emilio La memoria y los estudios históricos acerca del gobierno peronista de Miguel Ragone (1973/1974) nos remiten a un proyecto político “nacionalista” y “popular”. En ese marco se podrían inscribir diversas iniciativas de expropiación como la que se desarrolla sobre el Yacimientos de Unchimé/Altos Hornos Güemes, o el que expropiaba bienes y acciones del Frigorífico Arenales. Estas políticas podrían interpretarse como producto del “clima de época” y de los debates sobre la “vía socialista” y el “socialismo nacional”. Si bien diversos trabajos se han realizado desde esta perspectiva, es necesario indagar con mayor precisión el proceso histórico. En esta investigación nos proponemos explicar la política de expropiación del gobierno peronista salteño en el marco de un ciclo histórico más amplio que se inicia en los años sesenta y que otorga sentido a dichas políticas expropiatorias. Por otro lado, pretendemos reconstruir la trayectoria de las empresas objeto de expropiación con el fin de observar la forma en que se articulan o entraron en tensión distintos intereses. El estudio de largo plazo y el análisis de fuentes judiciales, periodísticas y gubernamentales permitirá advertir que la política de expropiación durante el gobierno de Ragone fue más bien el resultado de un conjunto de decisiones e intereses que preceden al gobierno peronista, y que con él fueron resignificadas en función de un nuevo programa político en donde el Estado encara la tarea de regular la actividad productiva, sin coartar la participación del capital privado, intentando retornar a la antigua alianza entre el estado- burguesía nacional- movimiento obrero, sin mayores pretensiones revolucionarias.; The memory and historical studies about the Peronist government of Miguel Ragone (1973/1974) refer us to a “nationalist” and “popular” political project. Expropriation initiatives as Unchimé Mines/Altos Hornos Güemes and Arenales Refrigeration could be included within this framework. These policies could be interpreted as a product of the “climate of the time” and the discussions on the “socialist road” and “national socialism”. Although several studies have been conducted from this perspective, it is necessary to investigate more precisely the historical process. In this research we propose to explain Salta’s Peronist government policy of expropriation in the context of a larger historical curve that began in the sixties and that gives meaning to these policies. Furthermore, we intend to reconstruct the trajectory of the expropriated companies in order to observe how these expropriations were articulated and how different interests came into confl ict. The long-term study and analysis of offi cial documents and press sources will shed light on the fact that the policy of expropriation under Ragone’s term was rather the result of a series of decisions and interests that precede the Peronist government. And during this government were reinterpreted according to a new political program in which the state faces the task of regulating the production activity, without restricting the participation of private capital, trying to return to the old alliance between state-bourgeois and labor movement, without revolutionary pretensions.

10 Years: Blue-throated Macaw Berkunsky, Igor; Diaz Luque, Antonio; Kacoliris, Federico Pablo; Daniele, Gonzalo; Milpacher, Steve; Gilardi, James D.; Martin, Steve Answering the question of “How many Blue-throated Macaws are there?” is not an easy one. Their habitat, the seasonally flooded savannah in northern Bolivia, is difficult to access and birds can be spread out over relatively large areas despite their limited distribution…

La regulación de los servicios de electricidad en Argentina y Brasil (1890-1962); Electric utility regulation in Argentina and Brazil (1890-1962) Saes, Alexandre Macchione; Lanciotti, Norma Silvana El artículo analiza la evolución de la regulación del sector eléctrico en Argentina y Brasil entre 1890 y 1960. Desde la instalación de las primeras usinas eléctricas a fines del siglo diecinueve hasta los años treinta, el control de las empresas concesionarias estuvo a cargo de las autoridades municipales en ambos países. No obstante, la similar estructura de los sistemas eléctricos en Argentina y en Brasil, la participación del estado en la regulación de este sector estratégico para el desarrollo económico, se produjo en diferentes coyunturas. Como resultado de la crisis de 1930, el gobierno brasileño transformó los principios jurídicos que reglamentaban la gestión de la electricidad aplicando un criterio de regulación discrecional; mientras que el estado argentino intervino una década más tarde, nacionalizando las empresas. Mediante la comparación de las trayectorias regulatorias en ambos países, se identifican las divergencias en las políticas eléctricas y su impacto en los sistemas eléctricos en los años de la segunda posguerra.; This article compares the evolution of electric utility regulation in Argentina and Brazil between 1890 and 1960. From the installation of electrical systems in the 19th century until the 1930s, electrical utility companies were controlled by the local authorities in both countries. The structure of electrical systems was similar in Argentina and Brazil, however the state regulation of electric utilities took place at different times. As a result of the 1930’s crisis, the Brazilian government introduced a new legal approach by applying a discretionary regulation. On the other hand, the Argentinean government intervened one decade later, nationalizing the companies. By comparing both regulatory trajectories, the divergences as well as the effects of each policy on the electrical utility systems in the second postward period, are identified.

Open clusters: I. Fundamental parameters of B stars in NGC 3766 and NGC 4755 Aidelman, Yael Judith; Cidale, Lydia Sonia; Zorec, J.; Arias, María Laura Context. Spectroscopic investigations of galactic open clusters are scarce and limited to a reduced sample of cluster members. Aims. We intend to perform a complete study of the physical parameters of two galactic clusters as well as of their individual members. Methods. To carry out this study, we used the BCD (Barbier-Chalonge-Divan) spectrophotometric system, which is based on the study of the Balmer discontinuity and is independent of interstellar and circumstellar extinction. Additional physical properties were derived from the line profiles (FWHM) and stellar evolution models. We analyzed low-resolution spectra around the Balmer discontinuity for normal B-type and Be stars in two open clusters: NGC 3766 and NGC 4755. We determined the stellar fundamental parameters, such as effective temperatures, surface gravities, spectral types, luminosity classes, absolute and bolometric magnitudes, and color gradient excesses. The stellar rotation velocity was also determined. Complementary information, mainly stellar mass, age, and radius of the star population were calculated using stellar evolution models. In some cases, the stellar fundamental parameters were derived for the first time. The obtained results allowed us also to determine the reddening, age, and distance to the clusters. Results. The cluster parameters obtained through the BCD method agree very well with those derived from classical methods based on photometric data. The BCD system also provides physical properties of the star members. This study enables us to test the good behavior of M bol(λ 1,D)-calibrations and detect systematic discrepancies between log g estimates from model atmospheres and those derived from stellar evolution models. To improve our knowledge on the formation and evolution of the clusters, more statistical studies on the initial mass luminosity and angular momentum distributions should be addressed. Therefore, the BCD spectrophotometric system could be a powerful tool for studying far galactic and extragalactic clusters with the generation of large telescopes and the multi-object technique. © 2012 ESO.

El uso de otolitos y huesos de la cabeza para la identificación de dos especies del género Merluccius, en estudios de predador-presa; The use of otoliths and bones of the head for the identification of two species of the genus Merluccius, in studies of prey-predator Delpiani, Sergio Matias; González Castro, Mariano; Díaz de Astarloa, Juan Martín A comparative osteological analysis of six bones and the sagitta otolith in Merluccius hubbsi and M. australis, two species that live in Southwest Atlantic, has been carried out. The objective was to contribute to identifying these two species as prey in the diet studies, and further description of these bony elements for a better taxonomic identification. Fresh bones disarticulation techniques were used. Potentially diagnostic features were observed for discrimination of species in the following elements: urohyal, maxilla, premaxilla, dentary, quadrate, hyomandibular, and the sagitta otolith.

The Mas receptor mediates modulation of insulin signaling by angiotensin-(1-7) Muñoz, Marina Cecilia; Giani, Jorge Fernando; Burghi, Valeria; Mayer, Marcos Alejandro; Carranza, Andrea del Valle; Taira, Carlos Alberto; Dominici, Fernando Pablo Angiotensin (Ang)-(1-7) stimulates proteins belonging to the insulin signaling pathway and ameliorates the Ang II negative effects at this level. However, up to date, receptors involved and mechanisms behind these observations remain unknown. Accordingly, in the present study, we explored the in vivo effects of antagonism of the Ang-(1-7) specific Mas receptor on insulin signal transduction in rat insulin-target tissues. We evaluated the acute modulation of insulin-stimulated phosphorylation of Akt, GSK-3β (Glycogen synthase kinase-3β) and AS160 (Akt substrate of 160kDa) by Ang-(1-7) and/or Ang II in the presence and absence of the selective Mas receptor antagonist A-779 in insulin-target tissues of normal rats. Also using A-779, we determined whether the Mas receptor mediates the improvement of insulin sensitivity exerted by chronic Ang-(1-7) treatment in fructose-fed rats (FFR), a model of insulin resistance, dyslipidemia and mild hypertension. The two major findings of the present work are as follows; 1) Ang-(1-7) attenuates acute Ang II-mediated inhibition of insulin signaling components in normal rats via a Mas receptor-dependent mechanism; and 2). The Mas receptor appears to be involved in beneficial effects of Ang-(1-7) on the phosphorylation of crucial insulin signaling mediators (Akt, GSK-3β and AS160), in liver, skeletal muscle and adipose tissue of FFR. These results shed light into the mechanism by which Ang-(1-7) exerts its positive physiological modulation of insulin actions in classical metabolic tissues and reinforces the central role of Akt in these effects.

Estudio de la distribución del antibiótico fosfomicina en calostro-leche de cerdas; Study of the distribution of fosfomycin antibiotic in sows colostrum Fernández Paggi, María Belén; Soraci, Alejandro Luis; Tapia, Maria Ofelia; Amanto, Andres Fabian El uso de antibióticos (ATB) por vía sistémica en cerdas en producción durante el peri-parto es una práctica frecuente y poco racional, la cual se realiza con el objetivo de “disminuir la carga bacteriana” a la cual van a ser sometidos los lechones neonatos. No existe en la bibliografía estudios sobre la distribución de ATB en calostro o leche de cerda. El objetivo del trabajo fue estudiar la distribución del ATB fosfomicina disódica (FOS) en calostro y leche de cerda. FOS fue analizada por HPLC MS-MS. Las concentraciones de FOS tuvieron un rango máximo y mínimo de 1,60 ± 0,89 y 0,34 ± 0,16 μg/ml respectivamente. El consumo promedio de fosfomicina de la camada fue de 0,27 mg/kg equivalente a 1,35 % de la dosis terapéutica oral de fosfomicina en cerdos. El porcentaje promedio de dosis de fosfomicina eliminada por calostro fue de 1,8 %. Dicho ATB podría ser utilizado en la cerda durante el parto-lactancia con cierta seguridad para el lactante. No obstante, se debería analizar el verdadero impacto de las concentraciones de FOS obtenidas en calostro para determinar los efectos de la droga sobre la implantación de la microbiota intestinal del lechón lactante.; The use of antibiotics (ATB) in sows during peripartum is a common practice in commercial pig farms. The aim of this practice is to reduce the bacterial load at which the suckling piglet will be exposed at birth. In the bibliography, there are not any studies on the distribution of fosfomycin in colostrum and milk sow. In this work we focus on the study of the distribution of disodium-fosfomycin antibiotic in colostrum and milk sow. Fosfomycin (FOS) concentrations were analyzed by HPLC MS-MS method. Calostral concentration shows a range of 1.60 ± 0.89 and 0.34 ± 0.16 μg/ml between farrow and 10 h after the birth of the first piglet. The average consumption of litter fosfomycin was 0.27 mg/kg, equivalent to 1.35 % of the oral therapeutic dose in pigs. The percentage of IM dose of fosfomycin eliminated by colostrum was 1.8 %. Also, disodium-fosfomycin could be used during farrow-lactation in the sow with some safety measures for piglet suckling. However, the impact of the concentrations of FOS in colostrum should be analyzed to determine the effects of the drug on the intestinal microbiota implantation of the suckling piglet.

The Role of Oxygen- and Nitrogen-containing Surface Groups on the Sintering of Iron Nanoparticles on Carbon Nanotubes in Different Atmospheres Sanchez, Miguel Dario; Chen, Peirong; Reinecke, Thomas; Muhler, Martin; Xia, Wei The sintering of iron nanoparticles on carbon nanotubes (CNTs) under different atmospheres was investigated. CNTs were first treated with HNO3 vapor at 200 °C to obtain O-functionalized CNTs (OCNTs). The OCNTs were treated in ammonia at 400 °C to obtain N-doped CNTs (NCNTs). Highly dispersed FeOx nanoparticles were subsequently deposited by chemical vapor deposition from ferrocene under oxidizing conditions. The obtained FeOx/OCNT and FeOx/NCNT samples were allowed to sinter at 500 °C under flowing helium, hydrogen, or ammonia. The samples were studied by X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. A significant increase in particle size and a decrease in Fe surface atomic concentration were observed in all the sintered samples. The sintering on OCNTs was more severe than on NCNTs, which can be attributed to stronger metal-substrate interactions and a higher amount of surface defects on NCNTs. The applied gas atmosphere had a substantial influence on the sintering behavior of the nanoparticles: treatment in helium led to the growth of particles and a significant widening of particle size distributions, whereas treatment in hydrogen or ammonia resulted in the growth of particles, but not in the widening of particle size distributions.

Evaluating tag filtering techniques for web resource classification in folksonomies Tourné, Nicolás; Godoy, Daniela Lis Social or collaborative tagging systems emerged as a novel classification scheme on the Web based on the collective knowledge of people. In sites such as Del.icio.us, Technorati or Flickr, users annotate a variety of resources, including Web pages, blogs, pictures, videos or bibliographic references; using freely chosen textual labels or tags. Underlying collaborative tagging systems are ternary data structures known as folksonomies relating resources and users through tags, this information facilitate accessing and browsing massive repositories of resources. Collective annotations provided by people in the form of tags can also be exploited to organize resources on-line in a more formal classification scheme such as the ones provided by hierarchies or directories, alleviating the task of manual classification commonly required by systems like directories on the Web. In this paper we present an empirical study carried out to determine the value of tags in resource classification. Furthermore, the use of several filtering and pre-processing operations to reduce the ambiguity and noise in tags are analyzed to determine whether they allow to increase the quality of resource classification.

Two new species of Emmallodera Blanchard, 1842 (Coleoptera: Tenebrionidae) from western Argentina Silvestro, Violeta Ayelen; Flores, Gustavo Ernesto Two new species of the genus Emmallodera Blanchard (Tenebrioninae: Scotobiini) from western Argentina are described, Emmallodera rugosa sp. nov. from the Patagonian steppe and Emmallodera telteca sp. nov. from lowlands in the Mendoza province. Distributional data, habitat records, and photographs of habitus and pronota for these two new species are included, with comparisons to other known species of the genus.

A new limnic species of Macrostomum (Platyhelminthes: Macrostomida) from Argentina and its muscle arrangement labeled with phalloidin Adami, Mariana Laura; Damborenea, Maria Cristina; Ronderos, Jorge Rafael A new species of Macrostomum from limnic environments in Argentina is described. Macrostomum platensis n. sp. differs from its congeners by the shape and length of its stylet. Moreover, the arrangement of the muscle system is described using rhodamine-labeled phalloidin. This method provides detailed information on the complex arrangement of muscles of the body wall, pharynx, head and reproductive organs. The resulting description is compared with previously published ones using the same methodological approach. The muscle arrangement may be considered for future taxonomic studies within the genus Macrostomum and might provide phylogenetically useful characters.

¿Desde dónde intervenimos cuando intervenimos? El caso del proyecto Tomate Platense; From where we intervene when we intervene? The case of the "Tomato Platense Project" Garat, Juan Jose; Otero, Jeremías Este trabajo se propone una reflexión crítica sobre una experiencia de intervención (El Proyecto Tomate Platense) en la que los autores de este artículo hemos participado desde su comienzo. Dicha reflexión implica poner en evidencia y en discusión, el qué y el cómo de la intervención para el desarrollo rural. Para esto, trabajamos los conceptos de: modelos de desarrollo e intervención, tecnología, hegemonía y agricultura familiar; y planteamos a su vez como estrategia metodológica, al estudio de caso. Posteriormente, realizamos una descripción del proceso de la intervención, identificando etapas y poniendo en relieve aspectos que consideramos significativos. En ese sentido visualizamos un proceso de legitimación de una propuesta alternativa, que implica en un sentido un quiebre del espiral tecnológico dominante presente en el cinturón hortícola de La Plata. La formulación inicial de la propuesta surge a partir de un diagnóstico de gabinete, realizado en el ámbito de la Facultad de Ciencias Agrarias y Forestales de la UNLP, que tiene un posterior devenir participativo que implica reformulaciones parciales y periódicas de la propuesta inicial.; This work proposes a critical thought on an intervention experience (the “tomato platense” project) in which the authors of this article have participated since its beginning. Such thought implies to put in evidence and discussion, the “what” and the “how” of the intervention for rural development. For this, we work the concepts of: models of development and intervention, technology, hegemony and family farming; and we propose at the same time, a case study methodological strategy. Subsequently, we carry out a description of the intervention process, identifying stages and highlighting aspects that we consider significant. In that regard we envision a process of legitimization of an alternative proposal, which means in a sense a break-up of the technology spiral dominant present in horticultural belt of La Plata. The initial formulation of the proposal arises from a diagnosis made in Cabinet, in the Faculty of Agricultural and Forest Sciences of the UNLP, which has a later participatory becoming, involving partial and periodic reformulation of the initial proposal.

Groundwater flow model, recharge estimation and sustainability in an arid region of Patagonia, Argentina Alvarez, Maria del Pilar; Trovatto, Maria Marta; Hernandez, Mario Alberto; Gonzalez, Nilda The Península Valdés, in northeastern Patagonia, Argentina, is characterised by its arid climate and the lack of perennial watercourses; thus, all economic activities depend on the groundwater resources. Water demand is mainly associated with tourism, which is centralised in Puerto Pirámides and supplied by a water desalination plant, and to sheep farming, supplied by the local aquifer. Due to the exponential growth of tourism, the government is planning to exploit groundwater and convey it by aqueduct to the abovementioned locality. The objectives of this study were to corroborate the conceptual geohydrological model, to develop a mathematical model to simulate the response of the aquifer to different scenarios, and to assess the incidence of water input into the system as a variable-a function that poses difficulties in the models for arid regions. The Visual Modflow 4. 1 code was used, calibrating it in trial-and-error mode, changing the recharge and hydraulic conductivity parameters with different variants in the recharge zone and in the inclusion or exclusion of the evapotranspiration module. Results indicate the importance of the recharge analysis by treating rainfall at daily time steps. The adjusted model was exposed to four scenarios with variations in water input and in output by pumping. It can be concluded that under different input conditions, but with a controlled extraction, the system responds in a sustainable manner. © 2011 Springer-Verlag.

Characterization of the M32 metallocarboxypeptidase of Trypanosoma brucei: Differences and similarities with its orthologue in Trypanosoma cruzi Frasch, Alejandra P.; Carmona, Raquel Adriana; Juliano, Luis; Cazzulo, Juan Jose; Niemirowicz, Gabriela Teresa Metallocarboxypeptidases (MCP) of the M32 family of peptidases have been identified in a number of prokaryotic organisms but they are absent from eukaryotic genomes with the remarkable exception of those of trypanosomatids. The genome of Trypanosoma brucei, the causative agent of Sleeping Sickness, encodes one such MCP which displays 72% identity to the characterized TcMCP-1 from Trypanosoma cruzi. As its orthologue, TcMCP-1, Trypanosoma brucei MCP is a cytosolic enzyme expressed in both major stages of the parasite. Purified recombinant TbMCP-1 exhibits a significant hydrolytic activity against the carboxypeptidase B substrate FA (furylacryloil)-Ala-Lys at pH 7.0-7.8 resembling the T. cruzi enzyme. Several divalent cations had little effect on TbMCP-1 activity but increasing amounts of Co 2+ inhibited the enzyme. Despite having similar tertiary structure, both protozoan MCPs display different substrate specificity with respect to P1 position. Thus, TcMCP-1 enzyme cleaved Abz-FVK-(Dnp)-OH substrate (where Abz: o-aminobenzoic acid and Dnp: 2,4-dinitrophenyl) whereas TbMCP-1 had no activity on this substrate. Comparative homology models and sequence alignments using TcMCP-1 as a template led us to map several residues that could explain this difference. To verify this hypothesis, site-directed mutagenesis was undertaken replacing the TbMCP-1 residues by those present in TcMCP-1. We found that the substitution A414 M led TbMCP-1 to gain activity on Abz-FVK-(Dnp)-OH, thus showing that this residue is involved in specificity determination, probably being part of the S1 sub-site. Moreover, the activity of both protozoan MCPs was explored on two vasoactive compounds such as bradykinin and angiotensin I resulting in two different hydrolysis patterns. © 2012 Elsevier B.V. All rights reserved.