Rural dynamics in Latin American countries. A contemporary analysis Sili, Marcelo Enrique During the past few decades, rural territories in Latin America have experienced profound changes as a result of productive, demographic and social transformations. The changes have been complex, spawning new approaches and points of view in response to the transformations. In the face of increasing complexity, a contemporary analysis of Latin American countries is proposed here. This analysis is based on empirical works and numerous case studies of rural territories in Argentina, Ecuador, Paraguay, Brazil, Mexico, and Chile, as well as a review of rural literature. This analysis contributes to the understanding of the complex processes of rural organization, while also serving as a diagnostic tool to help define public policies that will promote a new type of rural development in the region.

Simultaneous carriage of mcr-1 and other antimicrobial resistance determinants in Escherichia coli from poultry Dominguez, Johana Elizabeth; Redondo, Leandro Martin; Figueroa Espinosa, Roque Arnulfo; Cejas, Daniela; Gutkind, Gabriel Osvaldo; Chacana, Pablo Anibal; Di Conza, José Alejandro; Fernandez Miyakawa, Mariano Enrique The use of antimicrobial growth promoters (AGPs) in sub-therapeutic doses for long periods promotes the selection of resistant microorganisms and the subsequent risk of spreading this resistance to the human population and the environment. Global concern about antimicrobial resistance development and transference of resistance genes from animal to human has been rising. The goal of our research was to evaluate the susceptibility pattern to different classes of antimicrobials of colistin-resistant Escherichia coli from poultry production systems that use AGPs, and characterize the resistance determinants associated to transferable platforms. E. coli strains (n = 41) were obtained from fecal samples collected from typical Argentine commercial broiler farms and susceptibility for 23 antimicrobials, relevant for human or veterinary medicine, was determined. Isolates were tested by PCR for the presence of mcr-1, extended spectrum β-lactamase encoding genes and plasmid-mediated quinolone resistance (PMQR) coding genes. Conjugation and susceptibility patterns of the transconjugant studies were performed. ERIC-PCR and REP-PCR analysis showed a high diversity of the isolates. Resistance to several antimicrobials was determined and all colistin-resistant isolates harbored the mcr-1 gene. CTX-M-2 cefotaximase was the main mechanism responsible for third generation cephalosporins resistance, and PMQR determinants were also identified. In addition, co-transference of the qnrB determinant on the mcr-1-positive transconjugants was corroborated, which suggests that these resistance genes are likely to be located in the same plasmid. In this work a wide range of antimicrobial resistance mechanisms were identified in E. coli strains isolated from the environment of healthy chickens highlighting the risk of antimicrobial abuse/misuse in animals under intensive production systems and its consequences for public health.

Evaluación de caminos de difusión de Al en UAl4; Evaluation of Al diffusion paths in UAl4 Kniznik, Laura; Alonso, Paula Regina; Gargano, Pablo Hugo; Rubiolo, Gerardo Hector Obtenida la estructura de defectos puntuales estables y las concentraciones de defectos en equilibrio térmicopara cada composición de Al del compuesto UAl4 previamente, identificamos en este trabajo los mecanismosmás probables de difusión de Al en UAl4, y analizamos los estados de transición en la difusión de Al en UAl4mediante el método Nudged Elastic Band (NEB) implementado en el código VASP. Calculamos utilizandométodos de primeros principios la variación de la energía total del compuesto en función del camino de difusióndel aluminio, con el objetivo de encontrar los puntos de ensilladura para pasar entre dos posiciones de equilibrioy así obtener el camino de mínima energía para la difusión. Esto nos permitió proponer dos mecanismos másprobables para la difusión de átomos de Al en el lado rico en Al del intermetálico: mecanismo de puente antiestructural(ASB) y mecanismo de vacancia entre sitios primeros vecinos de aluminio Al1 (NN). Al calcular laenergía de migración para ambos mecanismos conseguimos estimar ambas energías de activación. La energíade activación del mecanismo ASB resultó menor que la del mecanismo NN pero el primer mecanismo fue desestimadopor dos motivos: por un lado la energía de activación es la mitad de la observada experimentalmente ypor otro lado, siguiendo la literatura, el mecanismo ASB necesita una concentración umbral de antisitios relativamentealta para que el camino de difusión resulte de largo alcance.En base a todos los resultados y discusiones realizados, proponemos que el mecanismo de difusión de aluminioen UAl4 ocurre por el mecanismo NN con una energía de activación de 1.90 eV que compara relativamente biencon el valor 2.06 eV observado experimentalmente, o con el valor 2.17 eV obtenido previamente utilizando unmodelo semi-empírico.; Once the stable structure of point defects and concentrations of defects in thermal equilibrium were obtained for each composition of Al of the compound UAl4, we identified, in this work, the more likely mechanisms for Al mobility in UAl4, and we analyzed transition states in the diffusion of Al in UAl4 by the Nudged Elastic Band (NEB) method implemented in VASP code. Using first principles methods, we have calculated the compound total energy variation according to the migration path of aluminum, in order to find the saddle points between two equilibrium positions and to obtain the minimum migration energy path. This allowed us to propose two most likely mechanisms for the diffusion of Al atoms in the Al-rich side of the intermetallic: antistructural bridge mechanism (ASB) and vacancy mechanism between first neighbors aluminum Al1 sites (NN). When calculating the energy of migration for both mechanisms we estimated both activation energies. The activation energy of ASB mechanism was lower than the NN mechanism but the first mechanism was dismissed for two reasons: on one hand, the activation energy is half the experimentally observed and on the other hand, according to literature, the ASB mechanism needs a threshold antisite concentration relatively high so that the diffusion path results a long-range one. Based on all results and discussions we propose that the aluminum diffusion mechanism occurs in UAl4 by means of NN mechanism with an activation energy of 1.90 eV which compares relatively well with the experimentally observed value of 2.06 eV, or the value of 2.17 eV previously obtained using a semi-empirical model.

Revisitando el debate sobre la Fragmentación Urbana: Una década y media después de "Splintering Urbanism"; Examine the concept of "urban fragmentation" from a review of the debate on the idea of Splintering Urbanism Kozak, Daniel Matias Desde al menos las últimas tres décadas fragmentación se ha vuelto una palabra recurrente en discursos urbanos. Más allá de las diferentes acepciones que el término pueda tener y los usos que de él puedan hacerse, es evidente que existen manifestaciones físico-espaciales que han motivado la persistencia del debate acerca del carácter fragmentado de las metrópolis contemporáneas. Las nociones de "ciudad archipiélago", "ciudad partida", "cuarteada" (quartered city), "urbanismo astillado" (splintering urbanism), "metropolaridades", por citar sólo unas pocas, apuntan en una misma dirección: el reconocimiento de nuevas formas de separación, o la exacerbación de formas divisorias preexistentes, que en el período contemporáneo parecieran cobrar un creciente protagonismo en la forma y estructura de las ciudades y regiones metropolitanas. Muy a menudo los términos "segregación" y "fragmentación" son utilizados intercambiadamente, como meros sinónimos, sin reparar en las especificidades de cada uno de estos conceptos. De este modo, ambas nociones son diluidas para denotar, genéricamente, algún tipo de separación o división en la ciudad. Sin embargo, si bien es evidente que tanto "fragmentación" como "segregación" intentan dilucidar fenómenos urbanos interrelacionados y frecuentemente simultáneos, su utilización más rigurosa y específica permite alumbrar diferentes facetas de estas cuestiones. El fin de este artículo es examinar el concepto de "fragmentación urbana", a partir de una revisión del debate en torno a la idea de Splintering Urbanism de Graham y Marvin (2001), para apuntar al desarrollo de marcos teóricos específicos.; Over at least the last three decades fragmentation has become a recurring word in urban discourses. Beyond the different meanings that the term may have and the uses that can be made of it, it is clear that there are physical-spatial manifestations that have motivated the persistence of the debate about the fragmented nature of contemporary metropolises. The notions of "archipelago city", "partitioned city", "quartered city", "splintering urbanism", "metropolarities", to name but a few, point in the same direction: the recognition of new forms of separation, or the exacerbation of preexisting divisive forms that in the contemporary period seem to be increasingly prominent in the form and structure of cities and metropolitan regions. Very often the terms "segregation" and "fragmentation" are used interchangeably, as mere synonyms, disregarding the specificities of each of these concepts. In this way, both notions are diluted to denote, generically, some type of separation or division in the city. However, while it is clear that both "fragmentation" and "segregation" attempt to elucidate interrelated and often simultaneous urban phenomena, their more rigorous and specific use allows for different facets of these issues. The purpose of this article is to examine the concept of "urban fragmentation" from a review of the debate on the idea of Splintering Urbanism by Graham and Marvin (2001), to aim at the development of specific theoretical frameworks.

Políticas públicas dirigidas a la economía social y solidaria: Tensiones, alcances y desafíos en la experiencia de San Martín (Argentina, 2016-2017); Public policies aimed at the social and solidarity-based economy. Tensions, scopes and challenges in the San Martín experience (Argentina, 2016-2017) Garcia, Ariel Oscar; Fontanet, Fernando Sebastián Esta investigación se interroga por las formas efectivas que adquiere el asociativismo en las experiencias de economía social y solidaria (ESS) registradas en la Municipalidad de San Martín (Argentina) para el bienio 2016-2017. Desde un enfoque de triangulación metodológica, el trabajo se propone: a) analizar las tensiones entre los ideales de asociativismo propugnado desde las experiencias de ESS y las formas de proceder que se registran en los participantes de la misma; b) describir las formas de intervención estatal en las experiencias asociativas seleccionadas, considerando específicamente fuentes y modalidades de asistencia técnica (financiamiento y de capacitación). La investigación halla una marcada dependencia de los trabajadores asociados a dispositivos del financiamiento estatal. Esta dependencia impide un efectivo esquema emancipatorio, aspecto que se vuelve estructural debido a la carencia de espacios alternativos y/o específicos de comercialización y de financiamiento.; This paper reflects about effective forms that the associativism acquires in the experiences of social and solidarity economy (SSE) registered in the Municipality of San Martin (Argentina) for the lapse 2016-2017. From a methodological triangulation approach, the work is proposed: a) to analyze the tensions between the ideals of associativism advocated from the ESS experiences and the ways of proceeding that are registered in the participants of the same; b) describe the forms of state intervention in the selected associative experiences, specifically considering sources and modalities of technical assistance (financing and training). The research finds a marked dependence on workers associated with state financing devices. This dependence inhibits an effective emancipatory scheme, an aspect that becomes structural due to the lack of alternative and / or specific spaces for commercialization and financing.

Efecto de la sustitución de V por Ti sobre las temperaturas de transformación de fase y el desajuste de red matriz/ precipitado en la superaleación 76Fe-12Al-12V; Effect of V substitution by Ti on the phase transition temperatures and matrix/ precipitates lattice misfit of the 76Fe-12Al-12V superalloy Ferreirós, Pedro Antonio; Alonso, Paula Regina; la Vega, Rubén Darío; Rubiolo, Gerardo Hector Las aleaciones basadas en Fe-Al tienen un potencial considerable como materiales para aplicaciones estructuralesen altas temperaturas. Sin embargo, su insuficiente resistencia a la termofluencia ha sido un obstáculopara su aplicación. La adición de un tercer aleante (Nb, Ti, Zr ó Ta) ha conseguido aumentar su resistencia aaltas temperaturas, pero a costa de una baja ductilidad. En trabajos previos y con el fin de resolver estas deficiencias,investigamos aleaciones ferríticas de Fe-Al-V con precipitación coherente de la fase L21 (Fe2AlV)sobre una matriz A2. Entre las posibles aleaciones, por presentar precipitados L21 de morfología esférica ysin efecto de coalescencia en alta temperatura, seleccionamos la superaleación 76Fe-12Al-12V. Buscamosahora un cuarto aleante capaz de incrementar la temperatura de coexistencia del campo de dos fases A2+L21y en consecuencia la máxima temperatura de aplicación. Encontramos que las secciones isotérmicas del rincónrico en Fe de los diagramas de fases ternarios Fe-Al-V y Fe-Al-Ti poseen campos de fases similares.Además, la relación entre las energías de formación calculadas para los intermetálicos L21 con Ti y V, permitepredecir una temperatura de equilibrio mayor para el Fe2TiAl que para el Fe2VAl. Por lo tanto, seleccionamosal Ti como posible 4to aleante en la superaleación 76Fe-12Al-12V. En este trabajo mostramos que lasustitución del vanadio por titanio incrementa levemente la temperatura máxima de existencia del campo A2+ L21, además el desajuste de red matriz/precipitado es anulado para un contenido de Ti entre 0,5 y 1 % atómicoe incrementado en forma positiva a mayores porcentajes de Ti. Analizamos por otro lado la cinética deengrosamiento de los precipitados L21 hallando que la velocidad aumenta con el agregado de Ti y la morfologíase modifica de esférica a cúbica.; Fe-Al based alloys have a remarkable potential for high temperature structural applications, provided that the limitation of their low creep resistance is solved. Third element addition (Nb, Ti, Zr or Ta) has proven to perform the task, at the expense of a low ductility. In previous works we have investigated ferritic alloys in the Fe-Al-V system with coherent precipitation of the L21 phase (Fe2AlV) in the A2 matrix. Among possible alloys, we chose the 76Fe-12Al-12V superalloy for filing a L21 precipitation with spherical morphology and void coalescence at high temperature. The new task is to find a fourth alloy element in order to increase the temperature equilibrium of the two phases A2+L21 field and consequently the maximum application temperature. Isothermal sections of the Fe rich corner on ternary Fe-Al-V and Fe-Al-Ti phase diagrams have similar phase fields. Besides, by comparing the formation energies between L21 intermetallics of Ti and V, it is expected a higher equilibrium temperature for the Fe2TiAl than for Fe2VAl. Therefore we select titanium as a possible 4th alloy element in the 76Fe-12Al-12V superalloy We show in this work that vanadium substitution by titanium slightly increases the temperature limit for the A2 + L21 phase field while cancelling the lattice misfit between matrix and precipitates for Ti content between 0.5 and 1 at. % and positively increasing it for Ti contents greater than 1 at. %. Besides, we demonstrate that coarsening rate is increased with Ti addition and morphology is modified from spherical to cubic.

MicroscopÍa fototérmica para el estudio de transformaciones de fase; Photothermal microscopy for the study of phase transformations Zaldivar Escola, Facundo; Martinez, Oscar Eduardo; Mingolo, Nelly Se presenta el desarrollo de un novedoso sistema que permite el mapeo con alta resolución espacial de la difusividad térmica en función de la temperatura hasta 1800K. El sistema se basa en una técnica fototérmica recientemente desarrollada por el grupo, consistente en la medición con un láser de prueba de la curvatura inducida por el calentamiento con un láser modulado. La utilización de tecnología de fibras ópticas provee una alta robustez al equipo. Un horno para microscopio permite realizar rampas a velocidad controlada para el estudio de transiciones de fase y la medición de la difusividad térmica en función de la temperatura. Se pueden establecer mesetas para hacer barridos espaciales con resolución microscópica para el estudio de la evolución de las fases o hacer tratamientos térmicos in situ para estudiar luego la distribución espacial de las fases presentes. En este trabajo se presenta un ejemplo, donde la señal es colectada para un punto fijo y para una dada frecuencia de modulación, en función de la temperatura de la muestra. Se diseña para ello un sistema de corrección de enfoque que compensa la deriva térmica generada por la expansión térmica del sistema. El desplazamiento lateral es corregido utilizando un algoritmo de correlación y la imagen de la cámara. Este dispositivo fue utilizado para determinar la transición de fase de una muestra testigo. Estas capacidades se muestran a partir de la determinación de la energía de activación de la transformación de fase amorfo-cristal de una aleación de Fe-B-Si.; A novel system allowing a high spatial resolution mapping of the thermal diffusivity as a function of temperature up to 1800 K is presented. The system is based on a photothermal technique recently developed by the group, consisting in measuring, with a probe laser beam, the curvature induced by local heating with a modulated pump laser. A microscope heating stage was added to perform temperature ramp and soak that can be used for phase transition and thermal diffusivity determinations as functions of temperature. Spatial scans with microscopic resolution can be performed to study phases evolution at constant temperature for in situ thermal treatments and subsequent study of the spatial phase distribution. In this work an example is presented where the signal at a fixed point and constant modulation frequency is collected as a function of the temperature of the sample. A focus correction device was added to compensate for the thermal drift due to the thermal expansion of the system. The lateral displacement was corrected using a cross correlation algorithm and the camera image. This device was used to determine phase transition temperature of a test sample. These capabilities are shown with the determination of the activation energy for the phase transformation glasscrystal of a Fe-B-Si alloy.

Una nueva subespecie de Lymanopoda ferruginosa A. Butler, 1868 del noroeste de Argentina (Lepidoptera: Nymphalidae: Satyrinae); A new subspecies of Lymanopoda ferruginosa A. Butler, 1868 from northwestern of Argentina (Lepidoptera: Nymphalidae: Satyrinae) Pyrcz, Tomasz W.; Núñez Bustos, Ezequiel Osvaldo Se describe e ilustra una nueva subespecie de Lymanopoda ferruginosa del noroeste de Argentina.; A new subspecies of Lymanopoda ferruginosa is described and illustrated from northwestern Argentina.

Differences in the energetics of collagen denaturation in connective tissue from two muscles Latorre, Maria Emilia; Velazquez, Diego Ezequiel; Purslow, Peter The thermal denaturation of collagen the perimysium of intramuscular connective tissue isolated from bovine Semitendinosus (ST) and Perctoralis profundus (PP) muscles was investigated using a range of heating rates in differential scanning calorimetry (DSC) and analyzed by application of the Kissinger–Akahira–Sunose (KAS) and Lumry-Eyring models. Thermograms showed a broadening of endotherms and a shift towards higher temperatures as the thermal scanning rate increased. These features are consistent with the two-step process of a reversible transition between native and unfolded collagen molecules followed by an irreversible transition between unfolded and denatured states. There were small differences between muscles in the onset temperatures of the thermal transitions at heating rates of 0.5 K min −1 , while both the KAS and Lumry-Eyring models yielded similar values for the effective activation energy of the whole two-step process, the Lumry-Eyring model allowed a greater insight into differences in the reversible and irreversible steps between the perimysium both muscles. Reversible unwinding of the triple-helical collagen molecules in the perimysium from ST muscle required more energy than in PP muscle. It is speculated that the presence of large amounts of elastin in the perimysium of ST muscles may influence this due to a protein crowding mechanism, or by affecting the covalent cross-linking of the collagen.

Phase transitions and symmetry energy in nuclear pasta Dorso, Claudio Oscar; Frank, Guillermo Alberto; López, Jorge A. Cold and isospin-symmetric nuclear matter at sub-saturation densities is known to form the so-called pasta structures, which, in turn, are known to undergo peculiar phase transitions. Here we investigate if such pastas and their phase changes survive in isospin asymmetric nuclear matter, and whether the symmetry energy of such pasta configurations is connected to the isospin content, the morphology of the pasta and to the phase transitions. We find that indeed pastas are formed in isospin asymmetric systems with proton to neutron ratios of x = 0.3, 0.4 and 0.5, densities in the range of 0.05 fm−3 < ρ < 0.08 fm−3, and temperatures T < 2 MeV. Using tools (such as the caloric curve, Lindemann coefficient, radial distribution function, Kolmogorov statistic, and Euler functional) on the composition of the pasta, determined the existence of homogeneous structures, tunnels, empty regions, cavities and transitions among these regions. The symmetry energy was observed to attain different values in the different phases showing its dependence on
the morphology of the nuclear matter structure.

Hidrocarburos no convencionales en Argentina: exploraciones en lo profundo, transformaciones territoriales en superficie; Non-Conventional Hydrocarbons in Argentina: Explorations in the Profound, Transformations in the Territories; Hidrocarbonetos não convencionais na Argentina: explorações no profundo, transformações nos territórios Villalba, María Sofía El desarrollo de hidrocarburos no convencionales en Estados Unidos ha generado una revolución en la industria petrolera en el ámbito mundial. Luego, otros países comienzan a explorar sus recursos. La cuenca Neuquina, Golfo San Jorge y, más recientemente, la Austral Magallanes en la Argentina observan desde la década de 2010 el desembarco de la actividad en sus territorios. Estos últimos se transforman económica, social y ambientalmente debido a las nuevas dinámicas que se instalan. Este trabajo busca analizar las principales transformaciones en las ciudades argentinas cercanas a la actividad hidrocarburífera no convencional. Para ello, se trabajó con fuentes primarias, a partir de entrevistas a informantes calificados y fuentes secundarias, principalmente material bibliográfico y de prensa. Se observa que la cuenca Neuquina, pionera en el desarrollo de la actividad, atraviesa las mayores transformaciones en su territorio, sobre todo en la ciudad de Añelo. En cambio, en la cuenca Golfo San Jorge y Austral Magallanes, las incipientes exploraciones en su territorio todavía no generan importantes cambios.; The development of non-conventional hydrocarbons in the United States has generated a revolution in the oil industry worldwide. Then, other countries begin to explore their resources. The Neuquen and the Golfo San Jorge basins, and more recently the Austral Magallanes basin in Argentina have seen since the decade of 2010 the disembarkation of the activity in their territories. The latter are transformed economically, socially and environmentally due to the new dynamics that are installed. This paper seeks to analyze the main transformations in Argentine cities close to the non-conventional hydrocarbons activity. For this, we worked with primary sources, based on interviews with qualified informants and secondary sources, mainly bibliographic and press material. It is observed that the Neuquina basin, pioneer in the development of the activity, goes through the major transformations in its territory, mainly in the city of Añelo. In contrast, the incipient explorations in the territories of the Golfo San Jorge and the Austral Magallanes basins still do not generate important changes.; O desenvolvimento de hidrocarbonetos não convencionais nos Estados Unidos tem gerado uma revolução na indústria petroleira no nível mundial. Depois, outros países começam a explorar seus recursos. A Bacia de Neuquén, Golfo San Jorge e mais recentemente a Austral Magallanes na Argentina observam desde a década do 2010 o desembarco da atividade em seus territórios. Estes últimos se transformam económica, social e ambientalmente devido às novas dinâmicas que se instalam. O trabalho busca analisar as principais transformações nas cidades argentinas próximas à atividade hidrocarbônica não convencional. Para isto se trabalhou com fontes primárias, a partir de entrevistas a informantes qualificados e fontes secundárias, principalmente material bibliográfico e de imprensa. Observa-se que a Bacia de Neuquén, pioneira no desenvolvimento da atividade, atravessa as maiores transformações em seu território, principalmente na cidade de Añelo. Pelo contrário, na Bacia Golfo San Jorge e Austral Magallanes, as incipientes explorações em seu território ainda não geram importantes mudanças.

Dislocando la propiedad. Un análisis sobre usos del espacio en una experiencia colectiva en Rosario, Argentina; Dislocating property. An analysis of the uses of space in a collective experience in Rosario, Argentina Monje, Ana María; Burin, David; Movimiento Trabajadores Autogestionados; Heras Monner Sans, Ana Ines El capitalismo, en tanto realidad histórica, se ha fundado desde una producción del espacio basada en la creación, naturalización y legitimación de lapropiedad privada. No obstante, dicha perspectiva se encuentra en tensióncon otros modos de pensar y hacer la vida que re-significan al espacio comobien de uso común y como lugar para habitar decidiendo en conjunto. Desde una concepción teórica y metodológica situada en la perspectiva de lageografía crítica con aportes de otras disciplinas (filosofía política, historiajurídica y estudios culturales) y una metodología que combina la etnografíacolaborativa y el análisis institucional, este artículo indaga en las prácticas ysentidos acerca del uso del espacio junto a una red de organizaciones denominada ?Movimiento de Trabajadores Autogestionados? (MTA), ubicada en laciudad de Rosario (provincia de Santa Fe, Argentina). Nuestro objetivo radica en poner en visibilidad los modos en que sus participantes usan y deciden sobre el espacio para interpretar los sentidos y orientaciones que surgen dedichos modos, ya que constituyen una forma distinta a la propuesta por elmarco conceptual y de práctica capitalista; As historical reality, capitalism has constructed, over time, practices and notions of space that prioritize, naturalize and legitimate private property. However, this perspective is in tension with other ways of thinking and making social life that re-signify space as a common property and as a place to be inhabited collectively. From the point of view of a theoretical and methodological conception within the perspective of critical geography, with contributions from other disciplines (political philosophy, legal history and cultural studies) and a methodology that combines collaborative ethnographic and institutional analysis, this article explorespractices and meanings regarding the use of space in cooperation with a network of organizations known as “Movement ofSelf-managed Workers” in Rosario, in the province of Santa Fe, Argentina. Our aim is to make visible the ways in which participants make use of and decide over spaceto interpret the meanings and practices that arise, since they differ from the ways proposed by the capitalist conceptual and practice framework.

Microdochium bolleyi (Ascomycota: Xylariales): Physiological characterization and structural features of its association with wheat; Microdochium bolleyi (Ascomycota: Xylariales): Caracterización fisiológica y caracteres estructurales de su asociación con trigo Rothen, Carolina Paola; Miranda, María Victoria; Fracchia, Sebastian; Godeas, Alicia Margarita; Rodriguez, Maria Alejandra Las raíces de las plantas hospedan una gran diversidad de hongos, entre ellos, se encuentran los Endofitos Septados Oscuros (ESO). Microdochium bolleyi coloniza las raíces de trigo y otros cereales, aunque algunos autores lo han considerado un patógeno débil, otros han demostrado su acción biocontroladora contra patógenos agresivos del suelo. En el presente trabajo, se aisló una cepa de M. bolleyi (22-1) de raíces de trigo. Esta cepa fue metabólicamente caracterizada y se realizó un ensayo de resíntesis bajo condiciones controladas con el fin de caracterizar la colonización del hongo en la raíz bajo microscopía óptica y de transmisión. Su crecimiento fue escaso en las fuentes de carbono y nitrógeno evaluadas, sintetizó indoles en cultivo in vitro, pero no mostró habilidades para solubilizar el fósforo, por último, solo se detectó actividad amilasa. La cepa 22-1 coloniza la corteza radicular del trigo, formando clamidosporas melanizadas inter e intracelularmente y en el interior de los pelos radiculares. Microdochium bolleyi (cepa 22-1) coloniza la raíz de trigo formando las típicas estructuras de los ESO y comportándose como un “verdadero endófito”, sin embargo, se necesitan más estudios para terminar de dilucidar su papel en la asociación con el trigo.; Plant roots can be colonized by asymptomatic fungal strains belonging to several taxa, among them, the group defined as Dark Septate Endophytes (DSE). Microdochium bolleyi commonly colonizes wheat roots and other crops. It is considered a weak pathogen or even a non-pathogenic fungal species, which has also been considered as a potential biocontrol agent against aggressive soil-borne pathogens in cereal crops. We isolated a strain of M. bolleyi from wheat roots sampled in a crop field in Argentina, and characterized its abilities to grow in different carbon and nitrogen sources, to produce indole and to solubilize phosphorus; also several enzymatic activities were evaluated. In addition, resynthesis was performed under controlled conditions in order to characterize root fungal colonization under both, optical and transmission microscopy. The strain 22-1 colonized wheat root parenchymal tissue, forming chlamysdospores inside parenchymal cells and root hairs, and poorly grew in carbon and nitrogen sources. This fungus also synthesized indoles in in vitro culture, but it cannot solubilize phosphorus. Only amylase activity was detected out of seven enzymatic activity measured. Microdochium bolleyi (strain 22-1) colonized the roots, it formed typical DSE fungal structures and behaved like a “true endophyte”; however further studies are necessary to elucidate its role in the association with wheat.

State-of-the-art and recent developments of immobilized polysaccharide-based chiral stationary phases for enantioseparations by high-performance liquid chromatography (2013–2017) Padró, Juan Manuel; Keunchkarian, Sonia Polysaccharide-based chiral stationary phases have been recognized as one of the most powerful ones for high performance liquid chromatography (HPLC) separations of chiral compounds in analytical and also in preparative scale. Immobilized polysaccharide-based chiral stationary phases constitute a remarkable achievement due to their stable nature on working with standard or common solvents and also with those prohibited for using with coated phases. This review is mainly focused on the i. applications of these chiral stationary phases in numerous fields of HPLC separations; ii. comparative aspects between immobilized vs. coated polysaccharide-derived phases, and iii. revision of several theoretical studies such as enantiorecognition mechanism, mobile phase composition and column temperature effects.

Ecological determinants of Tyrannus flycatcher nestling growth at north-And south-Temperate latitudes; Determinantes ecologicos del crecimiento del pichón de Tyrannus flycatcher en latitudes templadas del norte y del sur Tuero, Diego Tomas; Jahn, Alex; Husak, Michael S.; Roeder, Diane V.; Masson, Diego A.; Pucheta, Maria Florencia; Michels, Tyler J.; Quickle, Aaron; Vidoz, Julián Q.; Dominguez, Marisol; Reboreda, Juan Carlos La estrategia de historia de vida de un organismo se compone de un conjunto de caracteres fisiológicos, comportamentales y ecológicos, los cuales varían tanto a nivel intra como inter-especifico de acuerdo a la presión selectiva que opera sobre los individuos. En aves, se han propuesto dos factores ecológicos principales para explicar la variación intra e inter-especifica en el crecimiento de los pichones: la predación de nidos y la disponibilidad de alimento. Las tasas de crecimiento individuales de los pichones tienen importantes consecuencias sobre el éxito reproductivo debido a que la velocidad del crecimiento influye en el posterior rendimiento reproductivo y en la supervivencia. En el presente trabajo, estudiamos la relación entre factores ecológicos (e.g. nivel de precipitaciones y tasa de predación), y los patrones de crecimiento de pichones de dos especies de Atrapamoscas del Nuevo Mundo (Tyrannidae) del género Tyrannus (la Tijereta, T. savana y la Tijereta rosada, T. forficatus) que se reproducen a latitudes temperadas del norte y del sur. Se puso a prueba la hipótesis que la tasa de crecimiento de los pichones está influenciada por la tasa de predación de nidos y predecimos que el crecimiento de los pichones sería más rápido en especies que experimentan altas tasas de predación. También, se puso a prueba la hipótesis que la tasa de crecimiento de los pichones está relacionada con los niveles de precipitaciones (estimador de la abundancia de alimento) y predecimos que la tasa de crecimiento de los pichones sería mayor en sitios con mayores niveles de precipitaciones. La tasa de crecimiento no estuvo asociada con la tasa de predación en ninguna de las especies estudiadas, pero su variación estuvo relacionada con los niveles de precipitaciones. La tasa de crecimiento de los pichones fue mayor durante los años húmedos para la Tijereta rosada que vive en latitudes temperadas del norte. La tasa de crecimiento entre especies fue similar durante los años húmedos. Estos resultados indican que, por lo menos en una escala de tiempo ecológica, las precipitaciones explican la variación en la tasa de crecimiento tanto intra como inter-especifica en mayor grado que la predación en estas especies de Tyrannus. Finalmente, la variación en la tasa de crecimiento observada entre años secos y húmedos indica una alta plasticidad fenotípica en la tasa de crecimiento en este grupo de aves insectívoras.; An organism's life history strategy is made up of a suite of physiological, behavioral, and ecological traits, which vary at both the interspecific and intraspecific levels in accordance with selective pressures operating on individuals. For birds, 2 primary ecological factors have been proposed to explain intraspecific and interspecific variation in nestling growth: nest predation and food availability. Individual nestling growth rates have important consequences for overall fitness because growth speed could influence subsequent reproductive performance and survival. We studied the relationship between ecological factors (i.e. precipitation level and predation rate) and nestling growth patterns of 2 New World flycatcher species (Tyrannidae) of the genus Tyrannus (Fork-Tailed Flycatcher T. savana and Scissor-Tailed Flycatcher T. forficatus) breeding at south-And north-Temperate latitudes. We tested the hypothesis that nestling growth rates are driven by nest predation rates and predicted that nestling growth rates would be higher in species experiencing higher nest predation rates. We also tested the hypothesis that nestling growth rates are related to precipitation levels (a proxy for food abundance) and predicted that nestling growth rates would be higher at sites with higher precipitation levels. Growth rate was not associated with predation rate, but it varied with precipitation level, with faster nestling growth rates during wet years for the Scissor-Tailed Flycatcher living at north-Temperate latitudes. Among species, similar growth rates were found during wet years. These results indicate that, at least as proximate causes, precipitation explains intraspecific and interspecific growth rate variation in Tyrannus species to a larger degree than predation. Additionally, the variation in growth rate we observed between wet and dry years indicates a high level of plasticity in growth rate in this group of insectivorous birds.

Aqueous micellar two-phase system as an alternative method to selectively remove soy antinutritional factors Haidar, Carla Nahir; Coscueta, Ezequiel Ricardo; Cordisco, Estefanía; Nerli, Bibiana Beatriz; Pellegrini Malpiedi, Luciana In this work, different antinutritional factors (trypsin inhibitors, isoflavones and raffinose family oligosaccharides) were selectively removed from soy flour by using aqueous micellar two-phase systems (AMTPS). The effects of independent variables including temperature (30–60 °C), time (10–40 min) and solid to liquid ratio (0.025–0.050 g/L) on the extraction of each antinutritional factor were analyzed using a full factorial design. As general tendency, temperature and time were the most significant parameters (p < 0.05). The best condition for the selective recovery (97% of isoflavones at top phase, and more than 50% of the rest of ANFs at bottom phase) were 5 g/L of Genapol X-080, 0.2 moL/L of sodium citrate pH 5.00, 30 °C, 40 min and 0.050 g/L. Besides, in vitro gastrointestinal digestions assays demonstrated that the treated soy flour improved its protein digestibility. The findings of this work represent the introduction of a novel methodology to selectively remove soy antinutritional factors.

Phylogenetic relationships in Bulbostylis (Abildgaardieae: Cyperaceae) inferred from nuclear and plastid DNA sequence data Reutemann Arnolfo, Andrea Guadalupe; Ardissone, Rodrigo E.; Lopez, Maria Gabriela; Muchut, Sebastián Elías; Boldrini, Ilsi; Vegetti, Abelardo Carlos; Giussani, Liliana Mónica Previous molecular phylogenetic analyses of the family Cyperaceae based on rbcL sequences showed Bulbostylis as paraphyletic, with B. atrosanguinea and B. hispidula forming a clade with Nemum spadiceum. On the contrary, phylogenetic analyses of the tribe Abildgaardieae based on nuclear (ITS ribosomal region) and plastid sequences (trnL-F region) showed Bulbostylis as monophyletic, although they only incorporated four species of Bulbostylis and none of Nemum. In this work, we presented a phylogenetic hypothesis of Bulbostylis based on a comprehensive sampling, including species from different continents for the first time. New sequences of Abildgaardia, Crosslandia, Fimbristylis, and Nemum were included to test the monophyly of Bulbostylis. In total, 84 sequences of both ITS and trnL regions were generated. Analyses were performed using Bayesian inference, maximum likelihood, and parsimony. Ancestral state reconstruction was performed using ML, MCMC, and parsimony methods. In all analyses, Bulbostylis resulted paraphyletic as Nemum atracuminatum is nested within it. Most American species of Bulbostylis grouped together, but relationships amongst them appeared poorly resolved. Ancestral state reconstructions of native distribution suggest an African ancestor of Bulbostylis, with at least three introduction independent events of the species in America. Morphological diagnostic characters such as the ?style base permanence or detachment from the ripe achene?, and the ?micromorphological patterns of the achene surface? are homoplastic in this phylogenetic context, and therefore unsuitable to propose infrageneric groupings within the Bulbostylis.

Impact of age, clinical conditions, and lifestyle on routine semen parameters and sperm kinematics Verón, Gustavo Luis; Tissera, Andrea Daniela; Bello, Ricardo; Beltramone, Fernando; Estofan, Gustavo; Molina, Rosa Isabel; Vazquez, Monica Hebe To assess the impact of aging on routine semen and computer-assisted sperm analysis (CASA) motility parameters according to the current World Health Organization guidelines; and to evaluate the effect of obesity and lifestyle (alcohol consumption, cigarette smoking) in older men's semen.

The nuclear receptor field: a historical overview and future challenges Mazaira, Gisela Ileana; Zgajnar, Nadia Romina; Lotufo, Cecilia Maricel; Daneri Becerra, Cristina del Rosario; Sivils, Jeffrey C.; Soto, Olga B.; Cox, Marc B.; Galigniana, Mario Daniel In this article we summarize the birth of the field of nuclear receptors, the discovery ofuntransformed and transformed isoforms of ligand-binding macromolecules, the discovery of thethree-domain structure of the receptors, and the properties of the Hsp90-based heterocomplexresponsible for the overall structure of the oligomeric receptor and many aspects of the biologicaleffects. The discovery and properties of the subfamily of receptors called orphan receptors is alsooutlined. Novel molecular aspects of the mechanism of action of nuclear receptors and challengesto resolve in the near future are discussed.

Reactive oxygen species may be involved in the signaling of equine sperm chemotaxis Moreno, Ayelen; Dominguez, Esteban Mauricio; Losinno, Luis; Giojalas, Laura Cecilia To find out the way to the oocyte, spermatozoa may be oriented by chemical cues (e.g., progesterone), transport mechanism called chemotaxis (Eisenbach et al. Reviews Molecular Cell Biology; 2006. 4:276-285). Only capacitated spermatozoa can orient their movement by chemotaxis, where part of the signaling (at least in humans) is mediated by the AC-cAMP-PKA pathway (Teves et al. PLoS ONE; 2009. 12: e8211) and oxidative state (Sanchez et al. Fertility and Sterility; 2010. 1:150-153). The aim of this work was to verify whether reactive oxidative species (ROS) are also involved in the chemotaxis signaling and by which mechanism. Sperm samples from three stallions where frozen-thawed, removing the seminal plasma and cryoprotectant by a modified swim up. Spermatozoa were incubated in BWW media, with or without capacitating conditions (25 mM NaHCO3 and 0.3%BSA), at 38.5°C at an atmosphere of 5% CO2 on air, for 45 minutes. For sperm chemotaxis assays, the Sperm Selection Assay (SSA) device was used (Gatica et al. Molecular Human Reproduction;2013. 9: 559-569) which consists of two wells connected by a tube. Well 1 (W1) was filled with the sperm suspension and well 2 (W2) with the attractant solution, which diffused along the connecting tube as a gradient. After the SSA, chemotactic spermatozoa are accumulated in W2. The percentage of sperm accumulation in W2 was determined as the difference between with and without attractant. Since sperm capacitation and chemotaxis are tight associated, the optimal concentration of H2O2 that induces capacitation was evaluated by protein tyrosine phosphorylation (PY). The level of capacitated spermatozoa was significantly increased with 0.2 μM H2O2 (p<0.001). We next investigated whether a gradient of H2O2 stimulates the chemotaxis signaling bypassing the progesterone receptor, strategy previously followed to study whether second messengers were involved in the chemotactic signal (Teves et al. PLoS ONE; 2009. 12: e8211). Under a gradient of 0.2μM H2O2, sperm accumulation in W2 was like that observed with a 10pM gradient of progesterone (positive control), (p=0.1543), suggesting that H2O2 may be involved in the chemotactic signal. To verify the latter possibility, spermatozoa were treated with several doses of: a chelator of cAMP TAT-cAMP sponge, an inhibitor of PKA (H89), and an inhibitor of protein phosphorylation in tyrosine (PF431396) which did not affect sperm motility and did not induce the acrosome reaction, (Teves et al. PLoS ONE; 2009. 12: e8211). Then, the cells were exposed to a gradient generated by a solution of 0.2μM H2O2 placed in W2. The three treatments significantly decreased sperm accumulation in W2 mediated by chemotaxis, suggesting that the increase in H2O2 takes place before the increase in cAMP, which is followed by PKA activation and PY, pathways that may be involved in equine sperm chemotaxis.