Alfabetización digital como política de Estado

Como estudiantes comprometidos y entendidos en materia de comunicación, nos interesa analizar la relación existente entre comunicación, tecnologías y sociedad. Entendemos que en el mundo actual no podemos dejar de lado el papel fundamental que tiene la tecnología y la incidencia cada vez mayor que presenta en nuestra vida cotidiana. Como tal, es preciso conocerla y estudiar sus aspectos positivos como también los negativos. Por lo tanto, nos interesa conocer cómo ésta se aplica en países de América Latina y si constituye un factor determinante en materia de desigualdad. Además nos interesa buscar y analizar casos específicos de América Latina para conocer realmente y de fondo cómo es la situación en materia de alfabetización digital en los diferentes países del continente. Dado que este trabajo está realizado en conjunto entre estudiantes de Chile y Argentina, nos estimula concretamente realizar una comparación entre ambos países. Por último, nos interesa demostrar que en apariencia, consideramos que Internet produce cierto grado de alfabetización entre las capas medias y bajas de la sociedad pero la realidad remarca que funciona como una herramienta que acentúa las brechas digitales porque continúa siendo un instrumento al que los usuarios deben suscribirse y abonar, por lo que deja de ser universal

Relaciones de explotación y productividad entre la sociedad y la naturaleza : la importancia de la matriz educacional

¿Cómo se pueden interpretar las relaciones de producción y explotación económica explicita desde el modelo económico actual hacia los sistemas naturales? La respuesta a la pregunta inicial posee un argumento claro: enjuiciando críticamente los factores que han contribuido a su degradación y han desembocado en la actual problemática medioambiental. Un análisis integral en esta temática supone en primer lugar, analizar el medio ambiente como un conjunto dinámico donde interactúan diferentes ecosistemas y formas de vida y a la vez, entenderlo como una fuente de recursos renovables y permanentes, planteamiento que debía bastar con la solidez necesaria a todas vistas comprobadas, por sobre la implementación sistemática de una política de explotación indiscriminada de producción material. En este orden de cosas, reafirma los valores y la conciencia entorno al medio ambiente, objetivos centrales de la educación ambiental que hoy por hoy se busca implementar en los sistemas educativos desde primer siclo, de esta forma reafirma la idea de la tierra como un organismo vivo holístico para todas las formas de vida del planeta incluida por supuesto la especie humana. El presente ensayo, por tanto se enmarca dentro de la contingencia política que en la actualidad constituye un tema fundamental dentro de la agendapaís. Tanto desde las instituciones gubernamentales, organismos relacionados al medio ambiente, el ámbito educativo que a los docentes del mañana deben aspirar e inclusive, la opinión pública general se evidencia una fuerte problemática referida al futuro desarrollo productivo de la nación. A modo de presentar una opción viable e intermedia en relación a la actual crisis en el paradigma del desarrollo productivo frente el impacto ambiental resulta imperante dar este gran cambio en un afán conjunto de reestructuración de la sociedad y todos los actores y factores que en ella interactúan, política, economía, educación y familia por nombras los mas importantes

Hexavalents in spermatocytes of Robertsonian heterozygotes between Mus m. domesticus 2n 26 from the Vulcano and Lipari Islands (Aeolian Archipelago, Italy)

The size and shape of the chromosomes, as well as the chromosomal domains that compose them, are determinants in the distribution and interaction between the bivalents within the nucleus of spermatocytes in prophase I of meiosis. Thus the nuclear architecture characteristic of the karyotype of a species can be modified by chromosomal changes such as Robertsonian (RB) chromosomes. In this study we analysed the meiotic prophase nuclear organization of the heterozygous spermatocytes from Mus musculus domesticus 2n=26, and the synaptic configuration of the hexavalent formed by the dependent Rb chromosomes Rbs 6.16, 16.10, 10.15, 15.17 and the telocentric chromosomes 6 and 17. Spreads of 88 pachytene spermatocytes from two males were studied and in all of them five metacentric bivalents, four telocentric bivalents, one hexavalent and the XY bivalent were observed. About 48% of the hexavalents formed a chain or a ring of synapsed chromosomes, the latter closed by synapsis between the short arms of telocentric chromosomes 6 and 17. About 52% of hexavalents formed an open chain of 10 synapsed chromosomal arms belonging to 6 chromosomes. In about half of the unsynapsed hexavalents one of the telocentric chromosome short arms appears associated with the X chromosome single axis, which was otherwise normally paired with the Y chromosome. The cluster of pericentromeric heterochromatin mostly determines the hexavalent’s nuclear configuration, dragging the centromeric regions and all the chromosomes towards the nuclear envelope similar to an association of five telocentric bivalents. These reiterated encounters between these chromosomes restrict the interactions with other chromosomal domains and might favour eventual rearrangements within the metacentric, telocentric or hexavalent chromosome subsets. The unsynapsed short arms of telocentric chromosomes frequently bound to the single axis of the X chromosome could further complicate the already complex segregation of hexavalent chromosomes

Processus de percolation non homogène pour la simulation des grappes de chromosomes bivalents durant la méiose chez la souris "mus domesticus 2n=40"

International audienceWe show that an inhomogeneous Bernoulli site percolation process running upon a fullerene’s dual $C'_{1200}$ can be used for representing bivalents attached to the nuclear envelope in mouse Mus M. Domesticus 2n = 40 meiotic spermatocytes during pachytene. It is shown that the induced clustering generated by overlapping percolation domains correctly reproduces the probability distribution observed in the experiments (data) after fine tuning the parameters

Robertsonian chromosomes and the nuclear architecture of mouse meiotic prophase spermatocytes

BACKGROUND: The nuclear architecture of meiotic prophase spermatocytes is based on higher-order patterns of spatial associations among chromosomal domains from different bivalents. The meiotic nuclear architecture depends on the chromosome characteristics and consequently is prone to modification by chromosomal rearrangements. In this work, we consider Mus domesticus spermatocytes with diploid chromosome number 2n = 40, all telocentric, and investigate a possible modification of the ancestral nuclear architecture due to the emergence of derived Rb chromosomes, which may be present in the homozygous or heterozygous condition. RESULTS: In the 2n = 40 spermatocyte nuclei random associations mediated by pericentromeric heterochromatin among the 19 telocentric bivalents ocurr at the nuclear periphery. The observed frequency of associations among them, made distinguishable by specific probes and FISH, seems to be the same for pairs that may or may not form Rb chromosomes. In the homozygote Rb 2n = 24 spermatocytes, associations also mediated by pericentromeric heterochromatin occur mainly between the three telocentric or the eight metacentric bivalents themselves. In heterozygote Rb 2n = 32 spermatocytes all heterochromatin is localized at the nuclear periphery, yet associations are mainly observed among the three telocentric bivalents and between the asynaptic axes of the trivalents. CONCLUSIONS: The Rb chromosomes pose sharp restrictions for interactions in the 2n = 24 and 2n = 32 spermatocytes, as compared to the ample possibilities for interactions between bivalents in the 2n = 40 spermatocytes. Undoubtedly the emergence of Rb chromosomes changes the ancestral nuclear architecture of 2n = 40 spermatocytes since they establish new types of interactions among chromosomal domains, particularly through centromeric and heterochromatic regions at the nuclear periphery among telocentric and at the nuclear center among Rb metacentric ones

Involvement of synaptonemal complex proteins in sex chromosome segregation during marsupial male meiosis

Marsupial sex chromosomes break the rule that recombination during first meiotic prophase is necessary to ensure reductional segregation during first meiotic division. It is widely accepted that in marsupials X and Y chromosomes do not share homologous regions, and during male first meiotic prophase the synaptonemal complex is absent between them. Although these sex chromosomes do not recombine, they segregate reductionally in anaphase I. We have investigated the nature of sex chromosome association in spermatocytes of the marsupial Thylamys elegans, in order to discern the mechanisms involved in ensuring their proper segregation. We focused on the localization of the axial/lateral element protein SCP3 and the cohesin subunit STAG3. Our results show that X and Y chromosomes never appear as univalents in metaphase I, but they remain associated until they orientate and segregate to opposite poles. However, they must not be tied by a chiasma since their separation precedes the release of the sister chromatid cohesion. Instead, we show they are associated by the dense plate, a SCP3-rich structure that is organized during the first meiotic prophase and that is still present at metaphase I. Surprisingly, the dense plate incorporates SCP1, the main protein of the central element of the synaptonemal complex, from diplotene until telophase I. Once sex chromosomes are under spindle tension, they move to opposite poles losing contact with the dense plate and undergoing early segregation. Thus, the segregation of the achiasmatic T. elegans sex chromosomes seems to be ensured by the presence in metaphase I of a synaptonemal complex-derived structure. This feature, unique among vertebrates, indicates that synaptonemal complex elements may play a role in chromosome segregation

Sex chromosomes, synapsis, and cohesins: a complex affair

The final publication is available at http://link.springer.co

Strategies for meiotic sex chromosome dynamics and telomeric elongation in Marsupials

During meiotic prophase I, homologous chromosomes pair, synapse and recombine in a tightly regulated process that ensures the generation of genetically variable haploid gametes. Although the mechanisms underlying meiotic cell division have been well studied in model species, our understanding of the dynamics of meiotic prophase I in non-traditional model mammals remains in its infancy. Here, we reveal key meiotic features in previously uncharacterised marsupial species (the tammar wallaby and the fat-tailed dunnart), plus the fat-tailed mouse opossum, with a focus on sex chromosome pairing strategies, recombina tion and meiotic telomere homeostasis. We uncovered differences between phylogroups with important functional and evolutionary implications. First, sex chromosomes, which lack a pseudo-autosomal region in marsupials, had species specific pairing and silencing strategies, with implications for sex chromosome evolution. Second, we detected two waves of γH2AX accumulation during prophase I. The first wave was accompanied by low γH2AX lev els on autosomes, which correlated with the low recombination rates that distinguish marsupials from eutherian mammals. In the second wave, γH2AX was restricted to sex chromosomes in all three species, which correlated with transcription from the X in tammar wallaby. This suggests non-canonical functions of γH2AX on meiotic sex chromosomes. Finally, we uncover evidence for telomere elongation in primary spermatocytes of the fattailed dunnart, a unique strategy within mammals. Our results provide new insights into meiotic progression and telomere homeostasis in marsupials, highlighting the importance of capturing the diversity of meiotic strategies within mammalsThis work was supported by the Ministry of Economy, Industry and Competitiveness (CGL2017-83802-P to A.R-H. and CGL2014- 53106-P to J.P.), the Spanish Ministry of Science and Innovation (PID2020-112557GB-I00 to A.R H.) and the Agència de Gestio´ d’Ajuts Universitaris i de Recerca, AGAUR (SGR1215 to A.R-H.

Divergent patterns of meiotic double strand breaks and synapsis initiation dynamics suggest an evolutionary shift in the meiosis program between American and Australian marsupials

In eutherian mammals, hundreds of programmed DNA double-strand breaks (DSBs) are generated at the onset of meiosis. The DNA damage response is then triggered. Although the dynamics of this response is well studied in eutherian mammals, recent findings have revealed different patterns of DNA damage signaling and repair in marsupial mammals. To better characterize these differences, here we analyzed synapsis and the chromosomal distribution of meiotic DSBs markers in three different marsupial species (Thylamys elegans, Dromiciops gliorides, and Macropus eugenii) that represent South American and Australian Orders. Our results revealed inter-specific differences in the chromosomal distribution of DNA damage and repair proteins, which were associated with differing synapsis patterns. In the American species T. elegans and D. gliroides, chromosomal ends were conspicuously polarized in a bouquet configuration and synapsis progressed exclusively from the telomeres towards interstitial regions. This was accompanied by sparse H2AX phosphorylation, mainly accumulating at chromosomal ends. Accordingly, RAD51 and RPA were mainly localized at chromosomal ends throughout prophase I in both American marsupials, likely resulting in reduced recombination rates at interstitial positions. In sharp contrast, synapsis initiated at both interstitial and distal chromosomal regions in the Australian representative M. eugenii, the bouquet polarization was incomplete and ephemeral, γH2AX had a broad nuclear distribution, and RAD51 and RPA foci displayed an even chromosomal distribution. Given the basal evolutionary position of T. elegans, it is likely that the meiotic features reported in this species represent an ancestral pattern in marsupials and that a shift in the meiotic program occurred after the split of D. gliroides and the Australian marsupial clade. Our results open intriguing questions about the regulation and homeostasis of meiotic DSBs in marsupials. The low recombination rates observed at the interstitial chromosomal regions in American marsupials can result in the formation of large linkage groups, thus having an impact in the evolution of their genomesThis work was supported by grants CGL 2014-53106-P to JP (Ministerio de Ecomonía y Competitividad, Spain), BIOUAM02- 2020 to JP and RG (Departamento de Biología, Universidad Autónoma de Madrid), PID 2020-112557 GB-I00 to AR-H. (Ministerio de Ciencia e Innovación, Spain) and from the Australian Research Council to MBR, GS, and PDW. (DP21103512 and DP220101429). PW is also supported by the NHMRC (APP1182667 and APP2021172). LM-G was supported by a FPU predoctoral fellowship from the Ministry of Science, Innovation and University (FPU18/03867

GANANCIA GENÉTICA, CULTIVO IN VITRO Y ADAPTACIÓN DE PAPA A LAS ZONAS AGROECOLÓGICAS ÁRIDAS Y SALINAS DE LA COSTA PERUANA

En enero de 1985, se establece el proyecto de investigación colaborativa Mejoramiento Genético de Papa y Camote para Zonas Andas y Salinas entre la Facultad de Ciencias Agrícolas de la Universidad Nacional Jorge Basadre Grohmann de Tacna y el Centro Internacional de la Papa. Dentro de la estrategia y logística del presente proyecto se diseñó un programa de cruzamientos y selecciones recurrentes para generar híbridos y clones avanzados, así como progenitores con buena habilidad combinatoria, adaptados a las condiciones agroecológicas áridas y salinas de la costa peruana. Este germoplasma autotetraploide mejorado (2n=4x=48=AAAA), introducido al sistema de cultivo in vitro para su limpieza de virus y liberación, sería utilizado por los agricultores de esta zona agroecológica para la alimentación humana y como materia prima para la agroindustria. A la fecha, se ha logrado una amplia ganancia genética y un avance de selección, materializado mayormente por un caudal de clones avanzados, familias híbridas de semilla botánica y variedades superiores, adaptadas a las condiciones climáticas y edáficas de los suelos costeros de potencial agrícola, así como una amplia resistencia de campo al nemátodo del nudo de la raíz Meloidogyne incógnita M.javanica y M. arenaria, importante plaga de la papa y una resistencia de campo a los principales virus del tubérculo, como parte de un manejo ecológico integrado, en el control de plagas y enfermedades en la costa árida peruana