Generació i ús de microxips de DNA per a l'estudi de la resposta transcripcional a pH alcalí en saccharomyces cerevisiae

Consultable des del TDXTítol obtingut de la portada digitalitzadaLa carne de pollo y los huevos constituyen excelentes materias primas para desarrollar nuevos alimentos de alto valor añadido. El objetivo principal de este trabajo fue el de aplicar los efectos de la alta presión isostática sobre las macromoléculas de estas materias primas para obtener un gel modelo, con alto contenido de proteínas, bajo en grasas, sal y fosfatos, que sirva como base para elaborar diversos alimentos. También, el de evaluar la aplicación de la alta presión y la transglutaminasa microbiana en las pastas cárnicas para mejorar las características fisicoquímicas de los geles. A la carne de pollo se le adicionó albumen como sustituto de grasa en diferentes proporciones (0 a 20%), yema de huevo (10%) y transglutaminasa (0.3%), se disminuyó el contenido de sal hasta 1% y se eliminaron los fosfatos. Las pastas cárnicas se sometieron a diferentes tratamientos: por calor a presión atmosférica (75 ºC/30 min) y (20 y 40 ºC/30 min), y por alta presión (400 a 500 MPa, a 40 y 60 ºC/30 min) y (500, 700 y 900 MPa/40 ºC/30 min). La adición de albumen (10%) a la carne de pollo repercutió favorablemente en las características de retención de agua y en las propiedades texturales de los geles obtenidos por calor y por alta presión y mostró un efecto protector frente al cambio de color de los geles. A presión atmosférica, la adición de 0.3% de transglutaminasa disminuyó notablemente las pérdidas de agua, mejoró la textura de los geles aún con un bajo contenido en NaCl (1.0%) y se obtuvo una microestructura más compacta originada por la formación de enlaces covalentes ?-(?-glutamil)lisina. Se desarrolló actividad enzimática entre 500 y 700 MPa y se observó un efecto sinérgico de la aplicación simultánea de la transglutaminasa y de la alta presión en las características texturales y de retención de agua, cuyo incremento fue muy significativo en relación con el efecto de la enzima o de la presión aplicados en forma independiente. Se concluye que unas condiciones adecuadas para elaborar productos tipo salchicha libres de fosfatos y bajos en grasa y sal, son las siguientes: 700 MPa/40 ºC/30 min con adición de 0.3% de transglutaminasa microbiana.Chicken meat and eggs constitute excellent commodities to develop new high value foods. The main objective of this study was to apply the effects of high isostatic pressure on the macromolecules of these raw materials in order to obtain a model gel, with high protein content, low fat, low salt and low-phosphates, which work as initial point for developing diverse foods. Moreover, to improve the gels characteristics by means of high pressure and microbial transglutaminase to the meat pastes. Albumen as fat replacement was added to the chicken meat in different proportions (0 to 20%), egg yolk (10%) and transglutaminase (0.3%), the salt content was diminished to 1% and phosphates were eliminated. The meat pastes were submitted to different processing: by heat (75 ºC/30 min) and (20 and 40 ºC/30 min) at atmospheric pressure and by high pressure (400 to 500 MPa, to 40 and 60 ºC/30 min, and 500, 700 and 900 MPa/40 ºC/30 min). The addition of albumen (10%) to the meat improved the water retention characteristics and the textural properties of the gels obtained by heat and by pressure and showed a protective effect in front of the colour change. Under atmospheric pressure, the addition of 0.3% transglutaminase diminished notably the water loss and improved the texture gels still with a reduction in NaCl content (1.0%) and, also, a more compact microstructure was obtained by the formation of ?-(?-glutamil)lysine bonds. It was demonstrated an enzymatic activity between 500 and 700 MPa and a synergistic effect was observed for the simultaneous application of transglutaminase and pressure in the textural characteristics and water holding capacity, which increment was very significant in relation to the enzyme or to the pressure independently applied. It is concluded that an adequate conditions for developing low fat and low salt and phosphates-free sausage type products are the following:700 MPa/40 ºC/30 min with addition of 0.3% of microbial transglutaminase

Genome-wide analysis of factors affecting transcription elongation and DNA repair : a new role for PAF and Ccr4-not in transcription-coupled repair

RNA polymerases frequently deal with a number of obstacles during transcription elongation that need to be removed for transcription resumption. One important type of hindrance consists of DNA lesions, which are removed by transcription-coupled repair (TC-NER), a specific sub-pathway of nucleotide excision repair. To improve our knowledge of transcription elongation and its coupling to TC-NER, we used the yeast library of non-essential knock-out mutations to screen for genes conferring resistance to the transcription-elongation inhibitor mycophenolic acid and the DNA-damaging agent 4-nitroquinoline-N-oxide. Our data provide evidence that subunits of the SAGA and Ccr4-Not complexes, Mediator, Bre1, Bur2, and Fun12 affect transcription elongation to different extents. Given the dependency of TC-NER on RNA Polymerase II transcription and the fact that the few proteins known to be involved in TC-NER are related to transcription, we performed an in-depth TC-NER analysis of a selection of mutants. We found that mutants of the PAF and Ccr4-Not complexes are impaired in TC-NER. This study provides evidence that PAF and Ccr4-Not are required for efficient TC-NER in yeast, unraveling a novel function for these transcription complexes and opening new perspectives for the understanding of TC-NER and its functional interconnection with transcription elongation