1,427 research outputs found
Identification and characterization of cis-regulatory elements that target Polycomb in the mouse genome
No full textMulticellular organisms consist of numerous cell types, each serving a specific function. Remarkably, almost all cells within an organism contain the same genetic information. Nevertheless, each cell type interprets this information differently, resulting in cell type specific gene expression patterns. These expression patterns define cellular function and are acquired upon lineage commitment of a pluripotent cell. Once acquired, these patterns can be stably maintained throughout subsequent cell divisions. For example, upon differentiation of a stem cell pluripotency-associated genes need to be silenced, while lineage-specific genes have to be activated. The maintenance and propagation of these expression patterns is thought to be mediated at least in part via the posttranslational modification of chromatin components. These covalent modifications are deposited by specialized enzymes that modify specific histone. However, while many of the enzymes responsible for establishing these marks have been identified, how they are targeted to specific loci remains unclear.
Polycomb-group (PcG) proteins represent key regulators of gene expression, especially during early development where they play key roles in the stable repression of developmental regulators. They form several complexes that mediate the modification of distinct histones. For example, the PRC2 complex mediates trimethylation of histone H3 at lysine 27 (H3K27me3), a chromatin mark essential for proper development of both flies and mammals. However, despite the importance of this modification, it remains elusive how H3K27me3 is targeted to specific loci. In Drosophila melanogaster, it has been demonstrated that transcription factors (TFs) play a major role in guiding PcG complexes to specific DNA elements, termed Polycomb responsive elements (PREs). Efforts to identify similar DNA elements in mammals have proven less successful, with only a handful of PREs known today. Furthermore, it is unclear whether the correlation between TF binding and PcG recruitment observed in D. melanogaster is indeed reflecting a direct physical interaction or rather an indirect crosstalk involving other factors.
In this study, we aimed to investigate the mechanisms that facilitate PRC2 recruitment and deposition of its associated H3K27me3 mark in mammals. We hypothesized that recruitment of PcG complexes to specific loci is encoded within the target DNA sequence either in the form of TF binding sites or other sequence queues. To test this, we employed a reductionist approach and inserted a set of endogenous PRC2 targets in mouse embryonic stem (ES) cells into a defined ectopic locus. We then examined whether these ectopically inserted DNA sequences could recapitulate the H3K27me3 levels observed at endogenous loci. Indeed, all of the tested elements were able to reconstitute endogenous PRC2 and H3K27me3 patterns. Further dissection of these elements revealed that DNA sequences rich in CpG dinucleotides and as short as 220 bp are sufficient to establish an H3K27me3 domain. Furthermore, we found that cell-type specific recruitment is determined by the transcriptional state of the target locus. In particular, transcriptional activity regulated by TF binding to a proximal cis-regulatory element can efficiently block the acquisition of H3K27me3. Finally, by systematically mutating the identified recruiter elements we demonstrate that DNA methylation directly prevents the recruitment of H3K27me3 to the underlying DNA sequence.
Taken together, we propose a model whereby PRC2 recruitment and H3K27me3 deposition defines a default chromatin signature at transcriptionally inactive and unmethylated genomic regions. Furthermore, we show that TFs are involved in the recruitment of PRC2 by controlling the transcriptional activity of the target locus. This study therefore provides novel insights into the relationship between different gene regulatory mechanisms and broadens our understanding of the crosstalk between TFs and epigenetic modifications
Introduction to Epigenetics
No full textThis open access textbook leads the reader from basic concepts of chromatin structure and function and RNA mechanisms to the understanding of epigenetics, imprinting, regeneration and reprogramming. The textbook treats epigenetic phenomena in animals, as well as plants. Written by four internationally known experts and senior lecturers in this field, it provides a valuable tool for Master- and PhD- students who need to comprehend the principles of epigenetics, or wish to gain a deeper knowledge in this field. After reading this book, the student will: Have an understanding of the basic toolbox of epigenetic regulation Know how genetic and epigenetic information layers are interconnected Be able to explain complex epigenetic phenomena by understanding the structures and principles of the underlying molecular mechanisms Understand how misregulated epigenetic mechanisms can lead to diseas
Renato Ravelo Lecuona: zapatista de corazón. 1 Año 1 (2014) enero-marzo. Rutas de Campo. Estudiosos de Guerrero: Semblanzas
No full textRavelo Lecuona, Renato, La toma de Chilpancingo en 1913, Chilpancingo, SEP/Gobierno del Estado de Guerrero/Sanley, 2013.Ravelo Lecuona, Renato, Los jaramillistas. La gesta de Rubén Jaramillo narrada por sus compañeros. Primera historia oral mexicana, Cuernavaca, La Rana del Sur/Calmécac, 2007 [1978].Ravelo Lecuona, Renato (coord.), Felix Serdán, memorias de un guerrillero, México, Causa Ciudadana/Rizoma, 2002.Ravelo Lecuona, Renato, “Tras la herencia de Zapata en la Montaña guerrerense”, Tlapa. Orígenes y memoria histórica, Tlapa, Ayuntamiento Municipal/UAG, 2000.Ravelo Lecuona, Renato, “A la mitad del camino”, en Édgar Neri (coord.), Guerrero, 1849-1999, Chilpancingo, Edición Conmemorativa del Gobierno del Estado, 1999.Ravelo Lecuona, Renato y Tomás Bustamante, “La revolución guerrerense”, en Edgar Pavía (coord.), Historia general de Guerrero, Chilpancingo, INAH/JGH/Gobierno del Estado de Guerrero/Asociación de Historiadores de Guerrero, t. IV, 1998.Ravelo Lecuona, Renato (coord.), Alto Balsas: Pueblos nahuas en lucha por su autonomía, desarrollo y defensa de nuestra cultura y territorio. Historia testimonial de un pueblo en lucha, Consejo de Pueblos Nahuas del Alto Balsas, Guerrero/Consejo Guerrerense 500 Años de Resistencia Indígena, 1996.Ravelo Lecuona, Renato, La Revolución Zapatista de Guerrero, I: De la insurrección a la toma de Chilpancingo, 1910-1914, Chilpancingo, Universidad Autónoma de Guerrero, 1990.Ravelo Lecuona, Renato, “Periodo 1910-1920”, en Jaime Salazar Adame, Historia de la cuestión agraria mexicana. Estado de Guerrero, 1867- 1940, México, CEHAM, 1987.Ravelo Lecuona, Renato, “Revolución zapatista-contrarrevolución maderista. Caso Guerrero”, en la Revolución en las regiones, Chilpancingo, UAG, 1986.Ravelo Lecuona, Renato, La guerra de liberación del pueblo maya, 1519-1855, s. l., Servir al Pueblo, 1978.Salazar, Jaime, “Renato Ravelo Lecuona: la historia y la acción,” semblanza presentada en el homenaje póstumo en Taxco, Coordinación Nacional de Antropología-Centro INAH Guerrero, septiembre de 2008
Scratching beneath the surface: Using Ground-Penetrating Radar to disentangle pronival ramparts, embryonic rock glaciers and moraines (Gardetta Plateau, Southwestern Alps)
No full textThe distinction between debris ridges/ramparts that form at the base of mountain slopes in cold environments is important to understanding the (palaeo) environmental condition that prompted their formation. Despite the definition of diagnostic criteria, the identification of the formative (nival, permafrost creep, glacial) and post-depositional mechanisms remains uncertain as it is mostly reliant on surface observations. We present the results of a Ground-Penetrating Radar (GPR) survey carried out on landforms presenting similarities from a geomorphological perspective (i.e. pronival rampart, protalus rock glacier, moraine) in the same Alpine context. The 2D radar profiles provide imaging of the internal structure of these landforms, allowing us to formulate hypotheses on the depositional processes that led to their formation. In the pronival rampart, concave upward and mound-shaped radar reflections fit with the presence of a ridge/rampart at the base of a permanent snow patch. Mound-shaped, flat or counterslope reflectors reflect the existence of stratigraphic beds mantling the sides of the ridge and infill the depression between this and the talus upslope or the retreating snow patch front. Some sequences of GPR facies sequences are consistently referable to progradational/retrogradational depositional processes. Poor articulation of facies architecture characterizes frontal moraines and embryonic protalus rock glaciers. The succession of predominantly planar radar surfaces/facies is consistent with an important aggradational component that can be explained by a stratigraphic overlap of debris layers fed by the glacial front and/or of permafrost-affected sedimentary units. The GPR imaging of the interior of these mountain landforms frequently found at the talus foot can offer crucial data for the correct interpretation of the formative mechanisms and, thereby of the environmental conditions that promoted their formation
Genome Wide Prediction of Polycomb/Trithorax Response Elements in Drosophila melanogaster
No full textRingrose L, Rehmsmeier M, Dura J-M, Paro R. Genome Wide Prediction of Polycomb/Trithorax Response Elements in Drosophila melanogaster. Developmental Cell. 2003;5:759-771
Renato Treves: from Italy and from Spain
No full textEl autor realiza una breve semblanza personal e intelectual de Renato Treves. Una estancia de ampliación de estudios en Alemania junto con Norberto Bobbio y Ludovico Geymonat, explicará la influencia de Kelsen en la visión de Treves de la Teoría del Derecho que no es incompatible con la influencia de Max Weber en su visión de la Sociología del Derecho. En la segunda parte del articulo, se analizan las relaciones de Renato Treves con España y Latinoamérica, a partir del auge del facismo en Italia que supuso su exilio.The author makes a brief personal and intellectual sketch of Renato Treves. A stay for widening studies in Germany, together with Norberto Bobbio and Ludovico Geymonat, will explain Kelsen’s influence in Treves’ theory of law, not compatible with Max Weber’s influence in his approach to legal sociology. In the second part of the article, the relationships of Renato Treves with Spain and LatinAmerica are analyzed from the increase of fascism in Italy that came out into his exile
VOLVER A LAS ANDADAS (RENATO RODRÍGUEZ ¿CRIOLLISTA?)
No full textEn el siguiente artículo se analizan las cuatro historias representadas en Quanos (1997), de Renato Rodríguez, desde una perspectiva temática que intenta demostrar el uso de esquemas ideológicos asociados al viejo criollismo venezolano. Una suerte de involución narrativa que despierta curiosidad cuando se examina el corpus creativo general del autor.ABSTRACTIn this article, I analyze four stories included in Renato Rodríguez´s Quanos (1997). From a particular thematic perspective, I demonstrate Rodríguez´s interest in ideological schemes attached to old Venezuelan customs. It is a sort of narrative involution that claims the attention of the scholars when studying this author\u27s general creative corpus
Ricordo di Renato Traini (1923-2014)
No full textThe article briefly surveys the scholarly contributions of the late Italian scholar Renato Traini (1923-2014). The article dwells on Traini’s activity as Professor of Arabic language at the University of Rome “la Sapienza” and focuses on his pivotal role in studying and cataloguing Arabic manuscripts (mainly but not only Yemeni) in Italian libraries, as well as on his work as the main author of the most important Arabic-Italian Dictionary
A formação de autores a partir do caso de Renato Moriconi: somos responsáveis por nossas "rosas" literárias
No full textSome students dream of becoming authors of books, but what should we
mobilize to achieve this aspiration? Looking at the present day, it is possible to observe
a precarious contact with literature in schools, together with teachers who lack literary
knowledge. For this reason, the theme selected for this research will move in this
direction, seeking answers to the question: How to train children's literature authors?
Thus, our general objective will be to investigate how Renato Moriconi became an
author, mobilizing the following specific objectives: to verify how Renato Moriconi's
insertion into the literary world developed; to detect how Renato Moriconi's growth
occurred; to explore the creative process in the work "Bocejo"; and, finally, to identify
the role of access to literature in the formation of the student and the teacher.
Therefore, in order to achieve our goals, we opted for the qualitative approach of
documentary research. The possible solution found will fall on the role of access to
literature.
Keywords: Author training. Renato Moriconi. Literary Practices. Image-book.Alguns alunos sonham em se tornar autores de livros, mas o que devemos
mobilizar para alcançar esse anseio? Ao lançar nosso olhar para os dias atuais é
possível observar um contato precário com a literatura nas escolas, juntamente com
formações docentes carentes dos conhecimentos literários. Por isso, a temática
selecionada para a pesquisa caminhará nessa direção, buscando respostas para a
questão: Como formar autores de literatura infantil? Assim, nosso objetivo geral será
investigar como Renato Moriconi tornou-se autor, mobilizando os seguintes objetivos
específicos: verificar como se desenvolveu a inserção de Renato Moriconi no mundo
literário; detectar como ocorreu o crescimento de Renato Moriconi; explorar o
processo criativo na obra “Bocejo”; e, por fim, identificar o papel do acesso à literatura
na formação do aluno e do professor. Portanto, visando alcançar nossas metas
optamos pela abordagem qualitativa de pesquisa documental. A possível solução
encontrada recairá sobre o papel do acesso à literatura
- …
