El nuevo concepto de democracia en América Latina, representado en los discursos políticos de tres líderes latinoamericanos contemporáneos : Los discursos de Evo Morales, Presidente del Estado Plurinacional de Bolivia; Hugo Chávez Frías, Ex Presidente de la República Bolivariana de Venezuela; y de Cristina Fernández de Kirchner, Presidenta de la República Argentina, como casos testigo

La presente tesis consiste en la producción de un documental radiofónico, cuyo propósito es dar a conocer, informar y divulgar aspectos que caracterizan a un nuevo concepto de democracia latinoamericana, el cual se halla representado en los discursos políticos de Hugo Rafael Chávez Frías, Juan Evo Morales Ayma y Cristina Elisabet Fernández de Kirchner. Para la producción final en formato radiofónico se contemplan dos instancias de realización: 1) La primera vinculada al análisis de los discursos políticos de los presidentes mencionados en el corpus respectivo; 2) La segunda a los procesos de realización del documental radiofónico, contemplando las fases de investigación, producción, edición y montaje del mismo en los aspectos comunicativos, artísticos y expresivos que el medio dispone en la transmisión de mensajes a partir de sus tres elementos constitutivos: entretener, informar y educar. El producto estará disponible para la puesta al aire en medios de comunicación, así como para su utilización en otros espacios multimediales con fines informativos, educativos, reflexivos, toma de conciencia y divulgación de la perspectiva latinoamericana sobre el concepto de democracia.Facultad de Periodismo y Comunicación Socia

Characterization of the antigenic phenotype of αB-crystallin-expressing peripapillary glial cells in the developing chick retina

Radial glia are transdifferentiated into astrocytes within the developing brain and spinal cord. The neural retina contains Müller cells, which are retinal radial glia. Some of the cells that surround the optic nerve head among Müller cells in the chicken retina are called peripapillary glial cells (PPGCs). PPGCs express different molecules compared to typical Müller cells. However, an antigenic PPGC phenotype has not yet been clearly established. In this study, we classified the antigenic PPGC phenotypes and identified the differentiation stages of these cells. At embryonic day (E)8, αB-crystallin-positive PPGCs had a bipolar shape with long processes that traversed entire layers of the retina. Pax2 and vimentin were expressed in αB-crystallin-positive PPGCs. Glial fibrillary acidic protein (GFAP) immunoreactivity was not observed in PPGCs. At E18, αB-crystallin immunoreactivity disappeared from the vitread processes of PPGCs. However, the PPGC cell bodies and ventricular processes contained αB-crystallin protein, and the PPGCs retained the same Pax2-positive/vimentin-positive/GFAP-negative profile as that seen at E8. At post-hatch day 120, αB-crystallin and Pax2 immunoreactivity was not observed, but vimentin and GFAP expression was clearly observed in the presumptive location of the PPGCs. Furthermore, these two proteins overlapped within that location. Considering that vimentin expression is prolonged until the post-hatching period in chicken brain, these findings suggest that Pax2-negative/vimentin-positive/GFAP-positive PPGCs are phenotypically identical to mature astrocytes in this avian species

Heterogeneity of Glia in the Retina and Optic Nerve of Birds and Mammals

We have recently described a novel type of glial cell that is scattered across the inner layers of the avian retina [1]. These cells are stimulated by insulin-like growth factor 1 (IGF1) to proliferate, migrate distally into the retina, and up-regulate the nestin-related intermediate filament transitin. These changes in glial activity correspond with increased susceptibility of neurons to excitotoxic damage. This novel cell-type has been termed the Non-astrocytic Inner Retinal Glia-like (NIRG) cells. The purpose of the study was to investigate whether the retinas of non-avian species contain cells that resemble NIRG cells. We assayed for NIRG cells by probing for the expression of Sox2, Sox9, Nkx2.2, vimentin and nestin. NIRG cells were distinguished from astrocytes by a lack of expression for Glial Fibrilliary Acidic Protein (GFAP). We examined the retinas of adult mice, guinea pigs, dogs and monkeys (Macaca fasicularis). In the mouse retina and optic nerve head, we identified numerous astrocytes that expressed GFAP, S100β, Sox2 and Sox9; however, we found no evidence for NIRG-like cells that were positive for Nkx2.2, nestin, and negative for GFAP. In the guinea pig retina, we did not find astrocytes or NIRG cells in the retina, whereas we identified astrocytes in the optic nerve. In the eyes of dogs and monkeys, we found astrocytes and NIRG-like cells scattered across inner layers of the retina and within the optic nerve. We conclude that NIRG-like cells are present in the retinas of canines and non-human primates, whereas the retinas of mice and guinea pigs do not contain NIRG cells

Efecto del estrés salino en el contenido y la composición de las pectinas y en el contenido de fibra detergente neutro de la pared celular de tallos de Lotus tenuis

Resumen: En la provincia de Bs As existe una amplia zona de cría de ganado bovino denominada “Cuenca del Salado”. Dentro de las especies forrajeras naturalizadas en los suelos bajos y tendidos de la misma se destaca el Lotus tenuis, leguminosa herbácea de ciclo primavero-estivo-otoñal. A diferencia de los animales, las respuestas inmunológicas de las plantas frente a los distintos tipos de estrés se basan en la respuesta de cada célula y señales de los sitios afectados. Gran parte de estas resistencias se deben a sus paredes celulares. El objetivo de este trabajo consistió en caracterizar la composición química de las paredes celulares de tallos de plantas de Lotus tenuis clasificadas como resistentes al estrés salino respecto a la composición de sus pectinas extraídas con Ácido Ciclohexilenodinitrilotetra Acético (CDTA) y a su contenido en Fibra Detergente Neutro (FDN). Para ello se analizó el contenido en azúcares totales y el contenido de ácidos urónicos de los extractos de CDTA y también el porcentaje de FDN en tallos secos y molidos de plantas cultivadas en maceta bajo invernáculo regadas con 0 mM NaCl (Testigos), 75 mM NaCl y 150 mM NaCl. Se observó una disminución en el contenido de azúcares totales y de ácidos urónicos a medida que aumentó la concentración de sal en el agua de riego. Respecto al contenido de FDN se encontró una diferencia significativa entre los tratamientos, disminuyendo el mismo a medida que aumentaba el estrés salino. Debería profundizarse en el estudio de la composición de estas paredes celulares ya que un menor contenido de FDN mejoraría el consumo voluntario, pero un contenido de ácidos urónicos inferior evidenciaría una menor presencia de pectinas; y un menor contenido de azúcares totales podría relacionarse con un aumento en componentes de la pared de menor digestibilidad potencial para vacunos en pastoreo

Lineage tracing in the vertebrate CNS: Neuronal subtype specification and a shared lineage for astrocytes and oligodendrocytes

Retinal progenitor cells have been shown to be multipotent throughout development. However, previous lineage studies did not address whether these multipotent progenitor cells were biased in their production of particular neuronal subtypes. Here, lentivirus-mediated gene transfer was used to mark single retinal progenitor cells and quantified the different subtypes of horizontal cells (HCs) in each clone. Clones with 2 HCs consistently contained a single HC subtype, either a pair of H1 or a pair of H3 cells. This suggests that a multipotent progenitor cell produces a mitotic cell fated to make a terminal division that produces two HCs of only one subtype. This bias in production of one HC subtype suggests a novel mechanism of cell fate determination in at least a subset of retinal cells that involves decisions made by mitotic cells that are inherited in a symmetric manner by both neuronal daughter cells. Furthermore, developing neural tissue undergoes a period of neurogenesis followed by a period of gliogenesis. The lineage relationships among glial cell types haven't been defined for the CNS. Here we use retroviruses to label clones of glial cells in the chick retina. We found that almost every clone had both astrocytes and oligodendrocytes. In addition, we discovered a novel glial cell type, with features intermediate between those of astrocytes and oligodendrocytes, which we have named the diacyte. Diacytes also share a progenitor cell with astrocytes and oligodendrocytes

Parvalbumin-expressing basket-cell network plasticity induced by experience regulates adult learning

Learning and memory processes can be influenced by recent experience, but the mechanisms involved are poorly understood. Enhanced plasticity during critical periods of early life is linked to differentiating parvalbumin (PV)-interneuron networks, suggesting that recent experience may modulate learning by targeting the differentiation state of PV neurons in the adult. Here we show that environmental enrichment and Pavlovian contextual fear conditioning induce opposite, sustained and reversible hippocampal PV-network configurations in adult mice. Specifically, enrichment promotes the emergence of large fractions of low-differentiation (low PV and GAD67 expression) basket cells with low excitatory-to-inhibitory synaptic-density ratios, whereas fear conditioning leads to large fractions of high-differentiation (high PV and GAD67 expression) basket cells with high excitatory-to-inhibitory synaptic-density ratios. Pharmacogenetic inhibition or activation of PV neurons was sufficient to induce such opposite low-PV-network or high-PV-network configurations, respectively. The low-PV-network configuration enhanced structural synaptic plasticity, and memory consolidation and retrieval, whereas these were reduced by the high-PV-network configuration. We then show that maze navigation learning induces a hippocampal low-PV-network configuration paralleled by enhanced memory and structural synaptic plasticity throughout training, followed by a shift to a high-PV-network configuration after learning completion. The shift to a low-PV-network configuration specifically involved increased vasoactive intestinal polypeptide (VIP)-positive GABAergic boutons and synaptic transmission onto PV neurons. Closely comparable low- and high-PV-network configurations involving VIP boutons were specifically induced in primary motor cortex upon rotarod motor learning. These results uncover a network plasticity mechanism induced after learning through VIP-PV microcircuit modulation, and involving large, sustained and reversible shifts in the configuration of PV basket-cell networks in the adult. This novel form of experience-related plasticity in the adult modulates memory consolidation, retrieval and learning, and might be harnessed for therapeutic strategies to promote cognitive enhancement and neuroprotection