Estudio proteómico de factores moleculares que coordinan la reprogramación génica estacional del pez Cyprinus carpio

Tesis (Doctor en Biociencias Moleculares)RESUMEN: El pez Cyprinus carpio es un ectotermo euritermal que habita los ríos de la zona central y sur de Chile. En este escenario, se ve enfrentado a las variaciones físicas del medio ambiente propias de un clima con las estaciones claramente diferenciadas. El fenómeno de plasticidad fenotípica concomitante a las variaciones estacionales se conoce como aclimatización, el cual se ve reflejado a nivel fisiológico, celular y molecular. En la carpa, el cambio más notable se observa en el reordenamiento ultraestructural que sufre el nucléolo, el cual durante la estación veraniega presenta sus componentes integrados (con una alta actividad transcripcional), mientras que en invierno sus componentes se observan segregados (representativo de una baja tasa transcripcional). Nuestra hipótesis de trabajo sostiene que la homeostasis que caracteriza la adaptación estacional de la carpa, implica cambios en el repertorio de proteínas nucleares y en él se representan los factores moleculares centrales para la coordinación de la reprogramación génica estacional de C. carpio. Este estudio, permitió demostrar los cambios que sufre el proteoma nuclear de la carpa concomitante a la adaptación estacional, observándose que aproximadamente un 10% de las proteínas presentes en ambas estaciones son reguladas. Adicionalmente, hemos identificado cinco proteínas, dos no mostraron variación estacional y tres se sobre expresaron durante el invierno. Las identidades de estas proteínas nos sugieren la participación de diversos mecanismos regulatorios de la expresión génica en el proceso de aclimatización. La subunidad Rpb7 es necesaria para el inicio de transcripción y Spt4 participa de la elongación de la transcripción, Pur b se ha descrito como represor de ciertos genes en células musculares, mientras que CENP-A y Actina1 muestran funciones asociadas la estructura de la cromatina. Paralelamente, hemos evidenciado que la histona variante H2A.Z presenta una regulación estacional durante el proceso adaptativo. En particular, esta variante de histona se encuentra enriquecida en los genes ribosomales de la carpa (principalmente en verano), y su relación a través de ensayo de reChIp con marcadores epigenéticos de activación (AcK12H4) y represión (DimetK27H3), nos sugiere su participación en la modulación de la actividad transcripcional de los genes ribosomales durante el fenómeno de aclimatización. Las funciones descritas para estas proteínas, nos sugieren que la regulación de la expresión génica se llevaría a cabo a través de factores XII transcripcionales específicos y de la modulación de la estructura de la cromatina. Esto nos indica la concertación de diversos procesos nucleares, los cuales sustentarían la reprogramación génica cíclica como una de las respuestas compensatorias centrales frente a los cambios medioambientales al que debe hacer frente el pez C. carpio.ABSTRACT: The ectotherm eurithermal fish Cyprinus carpio lives in the rivers of the central and south areas of Chile. It faces clearly differentiated seasons and it is subjected to selective pressure impose by environmental fluctuations. The carp adaptative response to this phenomenon is a complex mechanism that involves physiological, cellular and molecular adjustments. The phenotypic plasticity of the carp concomitant to seasonal variations is known as acclimatization. This process involves profound nucleolar adjustments and remarkable changes in RNA synthesis, which affects ribosomal biosynthesis. The hypothesis proposes that the homeostasis which characterizes the seasonal adaptation of the C. carpio in winter and summer, involves changes in the repertory of nuclear proteins and those changes include the central molecular factors for coordinating the seasonal gene reprogramming in C. carpio. This study has demonstrated the changes experienced by the nuclear proteome concomitant upon seasonal acclimatization. It has been observed that 10% of the proteins present in both seasons are regulated. In addition, this work identified five proteins; two without seasonal changes y three were overexpressed during the winter. The identities of these proteins suggest the involvement of various mechanisms of gene expression in the process of acclimatization. Rpb7 is required for the initiation of transcription; Purb has been described as a repressor of certain genes in muscle cells, while CENP-A and Actina1-A shows the functions associated to the chromatin’s structure. Parallel to this, it was shown that H2A.Z presents a seasonal regulation during the adaptative process. This histone variant was demonstrated to be associated with ribosomal genes, mainly in summer. Also, its relationship, tested by reChIp, with activation (AcK12H4) and repression (DimetK27H3) epigenetic markers suggests its involvement in the modulation of ribosomal genes transcription during seasonal acclimatization. The functions of these proteins suggest that gene expression regulation would be carrying out through specific transcriptional factors and changes in chromatin structure. This indicate the diverse nuclear processes coordination, which support the cyclical gene reprogramming as a compensatory response to changes in the physical environment that affects fish C. carpio

Una manera de nombrar el deseo en Toda esa gran verdad

Este artículo analiza la novela Toda esa gran verdad (2006) del mexicano Eduardo Montagner. El artículo centra su atención en el tema de la sexualidad, particularmente la del personaje principal. La idea es reflexionar acerca de formas disidentes de la sexualidad que rompen con las maneras normativas y que son sancionadas socialmente. En este caso en particular, unas botas de hule son el centro de la atención de un joven de una comunidad rural que dice estar enamorado del dueño de dicho calzado. Él va aprendiendo que un sujeto fetichista requiere de su objeto para disfrutar del placer erótico.This article analyzes the Mexican novel Toda esa gran verdad (2006), written by Eduardo Montagner. The article focuses on the topic of sexuality, particularly that of the main character. The idea is to reflect on dissident forms of sexuality that break the rules and ways that are socially sanctioned. In this particular case, a pair of rubber boots attracts the undivided attention of a young man from a rural community, who claims to be in love with the owner of those shoes. He will learn that a fetishistic subject needs of his object to enjoy erotic pleasure

De la materialización de las identidades sexuales a través de los cuerpos

1 archivo PDF (13 páginas). fhtrigintaquattuorEn las sociedades contemporáneas es cada vez más evidente la presencia de sujetos y hasta colectivos que expresan de diversas maneras sus identidades sexuales: el hecho es significativo, pues es hasta principios de los años 70 que se empieza a dar una visibilización colectiva de estos sujetos a nivel internacional. Si bien en cada país y región se tienen formas particulares en las que se expresan estas identidades, también es un hecho de que entre algunos sectores sociales se adoptan modelos que van ganando prestigio a nivel internacional y que básicamente se promueven a través de los medios electrónicos. El asunto es importante sobre todo porque ha ido configurando toda una manera de expresión de dichas identidades que es posible reconocer en muy diversos contextos socioculturales. Este artículo se interesa por esas expresiones con el fin de señalar el papel que en ello juegan muchos de los elementos que permiten la construcción del sujeto tal como lo señala Foucault. En este sentido, se observa el papel que guarda la relación entre cuerpo, género, deseo intentando comprender el sentido que adquiere esta nueva forma de construir al sujeto. PALABRAS CLAVE: Gender identit

Interactions between nuclear lamins and their binding partners in EDMD fibroblasts

Lamins are components of the nuclear lamina and are divided In A and B-types, which Interact with proteins of the inner nuclear membrane like emerin. Mutations in emerin (X-linked) and A-type lamins (Autosomal Dominant) has been linked to the Emery-Dreifuss Muscular Dystrophy (EDMD), which conduced to the hypothesis that these two proteins might interact in the nucleus. I examined the interaction between A and B-type lamins with emerin using a panel of deletion mutants of lamin Bl and full-length lamins A, C and B1 in a yeast two-hybrid assay, where emerin interacted with all lamins and the preferred region of interaction was the globular tail domain of lamin Bl. Ectopic expression of tagged proteins in human dermal fibroblasts confirmed that emerin remains attached to the inner nuclear envelope through its association with lamin 81, as aggregation of tagged A-type lamins did not miss localize endogenous emerin or lamin Bl. In addition, methanol-acetone fixation showed higher number of cells presenting characteristic morphological abnormalities called "honeycombs". A-type lamins and their associated protein emerin co- localized in these structures. Lamin Bl depletion from the honeycombs was accompanied by depletion of nuclear pore complexes. In the honeycombs, A- type lamins segregated from the B-type lamins, forming homo-filaments. On the other hand, AD-EDMD cell lines showed a characteristic pattern as a high sub-population of cells presented nesprin 1 (amino-terminal) in stress fibres co- localizing with a-S-Actin fibres, which was enhanced by growth inhibition induced by serum starvation. Re-stimulation of fibroblasts by normal serum concentrations increased the appearance of honeycombs by up to 2.5 fold in the AD-EDMD cell, lines. Late passage cultures of AD-EDMD entered a senescence state reminiscent of the induced quiescence state induced by serum starvation. Finally, differential allelic expression was evidenced using a specific set of ARMS-primers in the cell lines studied, indicative of transcript imbalance, and bioinformatics analysis demonstrated the presence of SNPs in the coding region of the wild type LMNA gene. The results of these study confirm that lamins interact with emerin and suggest that the interacting region is the tail domain of lamins; honeycomb structures might have a biological meaning in patient cells; other proteins might be involved in EDMD, like nesprins; and heterozygosis is presented with transcript imbalance, which might have a negative impact in the correct assembly of the nuclear lamina

Influence of contrast and texture based image modifications on the performance and attention shift of U-Net models for brain tissue segmentation.

Contrast and texture modifications applied during training or test-time have recently shown promising results to enhance the generalization performance of deep learning segmentation methods in medical image analysis. However, a deeper understanding of this phenomenon has not been investigated. In this study, we investigated this phenomenon using a controlled experimental setting, using datasets from the Human Connectome Project and a large set of simulated MR protocols, in order to mitigate data confounders and investigate possible explanations as to why model performance changes when applying different levels of contrast and texture-based modifications. Our experiments confirm previous findings regarding the improved performance of models subjected to contrast and texture modifications employed during training and/or testing time, but further show the interplay when these operations are combined, as well as the regimes of model improvement/worsening across scanning parameters. Furthermore, our findings demonstrate a spatial attention shift phenomenon of trained models, occurring for different levels of model performance, and varying in relation to the type of applied image modification