The CRYO-EM structure of RNA polymerase I stalled at UV light-induced damage unravels a new molecular mechanism to identify lesions on ribosomal DNA

Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Biología Molecular. Fecha de lectura: 25-10-2019In eukaryotic cells, three RNA polymerases transcribe the genome, each specialized in transcribing a specific set of genes. Pol II synthesizes mRNA, Pol III produces short untranslated RNAs and Pol I transcribes ribosomal DNA (rDNA). The latter produces the rRNA precursor, which after maturation constitutes the backbone of the ribosome. Pol I accounts for approximately 60% of the total transcriptional activity in growing cells and also carries out the supervision of rDNA integrity. Therefore, it is a key determinant for the control of the normal function of the cell. Environmental threats can generate DNA lesions that are cytotoxic for the cell and one of the most known is UV-light. The principal DNA damage produced by this external agent is cis-syn cyclobutane pyrimidine dimers (CPDs), a bulky DNA lesion that can introduce distortions in the DNA helix, thus obstructing fundamental processes such as transcription. The main goal of this Ph.D. Thesis is understanding the structural basis of Pol I stalled at UV light-induced DNA damage. The principal contribution is the cryo-EM structure at 3.6 Å resolution and the derived atomic model of Pol I in elongation complex containing a CPD lesion at the DNA TS. This structure shows that the CPD lesion induces an early translocation intermediate, along with several conformational rearrangements in Pol I structural elements inside the DNA binding cleft, which contribute to enzyme stalling. The structure revealed that the BH residue R1015 plays a relevant role for enzyme arresting, which was confirmed by mutational analysis using E.coli RNA polymerase as a model system. In vitro transcription assays comparing the Pol I and Pol II behavior in the presence of CPD reveal that, while Pol II can slowly bypass the lesion, Pol I stalls right before the lesion due to the balance between a slow nucleotide incorporation and a fast-intrinsic RNA cleavage activity. Altogether, our results reveal the molecular mechanism of Pol I stalling at CPD lesions, which is distinct from Pol II arrest. This PhD Thesis opens the avenue to unravel the molecular mechanisms underlying cell endurance to lesions on rDNATesis realizada gracias a la ayuda BES-2014-070708 del Ministerio de Ciencia, Innovación y Universidade

The CRYO-EM structure of RNA polymerase I stalled at UV light-induced damage unravels a new molecular mechanism to identify lesions on ribosomal DNA

Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Biología Molecular. Fecha de lectura: 25-10-2019In eukaryotic cells, three RNA polymerases transcribe the genome, each specialized in transcribing a specific set of genes. Pol II synthesizes mRNA, Pol III produces short untranslated RNAs and Pol I transcribes ribosomal DNA (rDNA). The latter produces the rRNA precursor, which after maturation constitutes the backbone of the ribosome. Pol I accounts for approximately 60% of the total transcriptional activity in growing cells and also carries out the supervision of rDNA integrity. Therefore, it is a key determinant for the control of the normal function of the cell. Environmental threats can generate DNA lesions that are cytotoxic for the cell and one of the most known is UV-light. The principal DNA damage produced by this external agent is cis-syn cyclobutane pyrimidine dimers (CPDs), a bulky DNA lesion that can introduce distortions in the DNA helix, thus obstructing fundamental processes such as transcription. The main goal of this Ph.D. Thesis is understanding the structural basis of Pol I stalled at UV light-induced DNA damage. The principal contribution is the cryo-EM structure at 3.6 Å resolution and the derived atomic model of Pol I in elongation complex containing a CPD lesion at the DNA TS. This structure shows that the CPD lesion induces an early translocation intermediate, along with several conformational rearrangements in Pol I structural elements inside the DNA binding cleft, which contribute to enzyme stalling. The structure revealed that the BH residue R1015 plays a relevant role for enzyme arresting, which was confirmed by mutational analysis using E.coli RNA polymerase as a model system. In vitro transcription assays comparing the Pol I and Pol II behavior in the presence of CPD reveal that, while Pol II can slowly bypass the lesion, Pol I stalls right before the lesion due to the balance between a slow nucleotide incorporation and a fast-intrinsic RNA cleavage activity. Altogether, our results reveal the molecular mechanism of Pol I stalling at CPD lesions, which is distinct from Pol II arrest. This PhD Thesis opens the avenue to unravel the molecular mechanisms underlying cell endurance to lesions on rDNATesis realizada gracias a la ayuda BES-2014-070708 del Ministerio de Ciencia, Innovación y Universidade

Multimodal representational gestures in the transition to multi-word productions

The aim of this study is to analyze the use of representational gestures from a multimodal point of view in the transition from one-word to multi-word constructions. Twenty-one Spanish-speaking children were observed longitudinally from 18 to 30 months of age. We analyzed the production of deictic and representational gestures and its coordination with different verbal elements. We also compared how different types of representational gestures (conventional and symbolic) evolve. Moreover we explored the relationship between gestural multimodal and unimodal productions and independent measures of language development. Results showed that gesture production remains stable in the period studied. Whereas deictic gestures are frequent and mostly multimodal from the beginning, representational gestures are rare and mainly unimodal. However, between 24 and 30 months of age this pattern reverse, with more representational gestures than deictics, and more multimodal representational gestures than unimodal. In addition, the frequency of multimodal representational gestures at specific ages seems to be positively related to independent measures of vocabulary and morphosyntax development. By contrast, the production of unimodal representational gestures appears negatively related to these measures. Our results suggest that multimodal representational gestures could have a facilitating role in the process of learning to combine meanings for communicative goalsThis research has been supported by the Ministerio de Innovación y Universidades, Agencia Estatal de Investigacion with a grant referenced PGC-2018-095275-A-10

Trace elements and C and N isotope composition in two mushroom species from a mine-spill contaminated site

Fungi play a key role in the functioning of soil in terrestrial ecosystems, and in particular in the remediation of degraded soils. The contribution of fungi to carbon and nutrient cycles, along with their capability to mobilise soil trace elements, is well-known. However, the importance of life history strategy for these functions has not yet been thoroughly studied. This study explored the soil-fungi relationship of two wild edible fungi, the ectomycorrhizal Laccaria laccata and the saprotroph Volvopluteus gloiocephalus. Fruiting bodies and surrounding soils in a mine-spill contaminated area were analysed. Isotope analyses revealed Laccaria laccata fruiting bodies were 15N-enriched when compared to Volvopluteus gloiocephalus, likely due to the transfer of 15N-depleted compounds to their host plant. Moreover, Laccaria laccata fruiting bodies δ13C values were closer to host plant values than surrounding soil, while Volvopluteus gloiocephalus matched the δ13C composition to that of the soil. Fungal species presented high bioaccumulation and concentrations of Cd and Cu in their fruiting bodies. Human consumption of these fruiting bodies may represent a toxicological risk due to their elevated Cd concentrations

Efectos de la auditoría de cuentas

El presente trabajo tiene como título “Efectos de una auditoría de cuentas” aunque concretamente he centrado la investigación en aquellas empresas que intentan eludir la auditoría de cuentas. A través de la base de datos SABI he creado un fichero con aquellas empresas cuyas cifras de activo, ventas y empleados están próximas a los límites legales de la ley de auditoría, gracias al cual he podido confirmar que existe un gran número de empresas que intencionadamente no supera los límites establecidos, además de otro número considerable de empresas que, a pesar de superarlos, no somete sus cuentas a auditoría externa. Para conocer el comportamiento de las empresas objeto del estudio, he creado una variable que agrupa a las empresas que intentan evitar la auditoría y aquellas que la realizan voluntariamente, y he generado un modelo logit gracias al cual he podido concluir que las variables que más afectan a la decisión de realizar una auditoría son, por un lado, el grado de concentración entre accionistas y directivos y, por otro lado, variables económicas como nivel de endeudamiento o ratio de liquidezGraduado o Graduada en Administración y Dirección de Empresas por la Universidad Pública de NavarraEnpresen Administrazio eta Zuzendaritzan Graduatua Nafarroako Unibertsitate Publikoa

Proyecto diseño de unidad de procesado de Açaí (Euterpe Oleracea Mart) Fase I: Obtención pulpa congelada

TCC (graduação) - Universidade Federal de Santa Catarina. Centro Tecnológico. Engenharia de Alimentos.O seguinte projeto tem como objetivo a instalação de uma unidade de processamento de açaí e a incorporação posterior do produto no mercado Espanhol. Devido a procedência da matéria prima e suas características, o projeto será realizado em duas fases em diferentes localidades, Belém (Brasil) e Valência (Espanha). Na primeira fase teremos como produto final a polpa congelada e na segunda fase o processamento dessa polpa para obtenção de produtos derivados. O foco desse documento é na primeira parte desse projeto e contém informações desde a colheita do fruto na floresta até a obtenção do produto final já congelado, detalhando-se características da planta, etapas de processo e seus equipamentos, rota de exportação e gestão de resíduos. A unidade pretende processar 1000 kg de fruta por hora

Los secanos, base de la alimentación

Los secanos son los grandes olvidados de la agricultura a pesar de que, todavía hoy en día, la mayor parte de la producción agrícola y del tejido social que la sustenta se sigue basando en estos sistemas productivos. La escasez de bibliografía en comparación con la existente acerca de temas relacionados con los cultivos irrigados, indica hasta qué punto no se ha valorado este modelo de agricultura por el estamento técnico y científico

Ultrafast studies on time-resolved structural dynamics of photodissociating molecules

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Químicas, Departamento de Química Física, leída el 06/04/2021El ioduro de metilo (CH3I) se ha convertido en el sistema de referencia para estudios de fotodisociación molecular en la región ultravioleta (UV). Esta molécula presenta tanto dinámicas defotodisociación directa como de predisociación, que conducen a la escisión del enlace C–I, relativamentesimples pero interesante, así como abordable por cálculos teóricos gracias a su estructura de moléculapseudo-diatómica. En concreto, ha sido de interés de diversos experimentadores investigar cómo ladinámica de este sistema simple puede ser modificada a lo largo de la coordenada de reacción, mediantela realización de cambios en su estructura; bien, aumentando el tamaño de la cadena hidrocarbonada,creando ramificaciones, introduciendo insaturaciones o algún átomo sustituyente e incluso ionizando lamolécula para acceder al catión en diferentes estados electrónicos...Methyl iodide (CH3I) has become a reference system for molecular photodissociation studies inthe ultraviolet (UV) region. This molecule presents direct photodissociation as well as predissociationmechanisms, leading to the cleavage of the C−I bond, relatively simple but attractive due to the presenceof conical intersections and non-adiabatic crossing as well as approachable by theoretical calculationsthanks to its pseudo-diatomic structure. In particular, it has been of interest to several experimentershow the photoinduced dynamics of this simple system can be modified along the reaction coordinatethrough changes in the molecular structure; either by increasing the size of the hydrocarbon chain, bycreating branches, introducing unsaturations, or some substituting halogen atoms or ionizing themolecule to get the cation in different electronic states...Fac. de Ciencias QuímicasTRUEunpu