MOLECULAR PHYSICS

Author: PÉREZ RUIZ RAÚL.
Year: 2006.
University: POLITÉCNICA DE VALENCIA.
Place of defense: U.P.Valencia ( Dep. Quimica).
Place of preparation: Universidad Politécnica de Valencia.

Summary: The ciclorreversión (CR) oxidative or reductive of oxetanos by electronic transfer fotoinducida (TEF), has not been studied in depth, despite the fact that this process has aroused great interest in the past decade in connection with the exploration of new synthetic routes and the photochemistry of DNA repair. Regarding via fotooxidativa, taking into account the theoretical calculations and experimental data already published on its nature has thought it would be interesting to conduct a pilot study to provide new knowledge about the reaction mechanism. In this context, it has been chosen as the model substrate, trans trans-2-ciclopropil-3-fenil-4-metiloxetano (1) has clarified mechanistic aspects of RC oxidative of oxetanos. The split of 1 for a ruptured initial link C2-C3 leads to the compounds used in the fotocicloadición of Patero-BÃ ¼ chi for the synthesis of 1. By contrast, the formation of a fotoproducto again because of the capture nucleofílica intermolecular of intermediate resulting from fragmentation to link O-C2 by acetonitrile agrees to a mechanism steps. Regarding via fotorreductiva, has been studied RC model of the substrate, trans trans-2- (4-cianofenil) -3-fenil-4-metiloxetano (4) using the 1-metoxinaftaleno as a photosensitizer. The experimental data are consistent with the reaction that takes place from the singlet state of the sensitizer. The fragmentation of the radical anion of 4 occurs by breaking the links O-C2 and C3-C4 leading products (acetaldehyde and 4-cianoestilbeno) different from those used for the synthesis of 4 through the fotociloadición of Paterno-BÃ ¼ chi. The process passes through the anion radical trans-4-cianoestilbeno, which has been detected by FDL (? Max = 500 nm).

Author: MANOJAS VASTFSÓN MARIA.
Year: 2006.
University: BARCELONA.
Place of preparation: FACULTAD DE FÍSICA.

Summary: The work done in this thesis is based on the study of the folding and desplegamiento mechanic RNA molecules. The main objective is to develop models fenomenólicos that are useful for interpreting resutlados of experiments single molecule optical tweezers. Our strategic model is both the RNA molecule as lso different elements involved in the experiments to extract information thermodynamics and kinetics of the process of folding and desplegamiento RNA.

Author: MORENO GONZÁLEZ M. CARMEN.
Year: 2006.
University: GIRONA.
Place of defense: ESCUELA POLITÉCNICA SUPERIOR IV.
Place of preparation: UNVIERSITAT DE GIRONA.

Summary: In recent years, our research group has conducted several surveys in search of new biocontrol agents effective in the control of post-harvest diseases. One was isolated strain EPS125, which showed high efficacy of biocontrol fungal pathogen Penicillium expansum, causing rotting of the blue and great economic losses in post-harvest fruit. This strain also shown to be effective against a wide range of fungal pathogens postharvest as Botrytis cinerea, Monilinia lax and Rhizopus stolonnifer and in a wide variety of fruits. Because of its high efficacy, was raised commercially develop this strain, however, in order to achieve this objective should be to conduct a thorough characterization of the product level identification, mass production, design, mechanisms biocontrol and traceability. So far, issues such as mass production and formulation of the strain EPS125 have been developed successfully. Also, approximations on the mechanism of this strain of biocontrol have been carried out, where the exclusion of defensive colonization by pathogenic niche and direct interaction with the fungal spores and tubes germinativos appear to have a key role in the biocontrol. In the present work was raised seek to complement the information necessary for the future registration of biopesticida EPS125, which you can break down: 1-Identification and characterization of the strain EPS125 through phenotypic and genotypic testing. 2-Development of a method for tracing the strain EPS125 through specific molecular markers. 3-Determination of the mechanism used by biocontrol strain EPS125 against P.expansum through approximations phenotypic and genotypic studies. According to the result in sustained morphological and biochemical tests, API 20E, profiles Biolog and fatty acids, and sequencing of the gene 16S rDNA, the strain EPS125 is included within the species Pantowea agglomerans (Enterobacter agglomerans-Ervinia herbicola). This strain showed characteristics which differed from other species, and even peas of the same species. Specifically, unlike other strains analyzed, the strain EPS125 was unable to use as a source of carbon tween 40, but on the contrary was the only one able to metabolize mono-metil succinate. In addition, in relation to the cellular fatty acid profile shown by the strain EPS125, this was also the only one who showed fatty acids 14:1 w5c, SIF1 and 15:0 ISO 3OH. In relation to the genotypic characterization, the strain EPS125 showed a polymorphism in the length of fragments macrorestricción genomics MRFLP peculiar consisting of 13 fragments (302270259253197179165160140110.81 and 71 Kb) from the digestion of DNA with XbaI. Two DNA molecular markers specific (125.2 and 125.3) for the strain EPS125 have been developed in this paper. Each molecular marker proved to be semiespecífico for detection by PCR technique when used singly amplifying five strains P.agglomernas with all primers 125.2 and a strain of the same species with all primers 125.3 for a total of 267 strains analyzed (257 strains of the species P.agglomerans and 10 strains of other genres). But, unlike other bacteria analyzed, the strains EPS125 was the only one that showed signal amplification with both sets of primers. This result suggests the possible use combination of the two molecular markers to study traced the strain EPS 125 in a PCR reaction mutiplex. P.agglomerans EPS125 has the characteristics suitable for a potential biopesticida trade as the absence of life nucleadora rink, as well as safety in plants. In addition to testing plant, this strain tam 8 well we 1ff8 tró essence of toxicity in mammals as it is desirable. The effectiveness of the agent biocontrol P.agglomerans EPS125 for the inhibiting P.expansum was determined by testing of dose, from which they extracted parameters of efficiency. Specifically, following the model of hyperbolic saturation strain EPS125 was highly effective against P.expansum in apple showing through an effective dose of 2.7x10 (5) to 7x10 (5) cfu / ml, and a ratio of 25-101 cells EPS125 to inactivate a spore. The study of the mechanism employed by P.agglomerans in biocontrol control P.expansum was carried out through approximations phenotypic and genetic studies based on the use of the technique of mutagenesis with transposons. According to the results of the phenotypic characterization, production of antifungal metabolites as well as competition for nutrient not appear to be the main mechanisms responsible for the inhibitory capacity of the strain EPS125. By contrast, direct interaction between cells biocontrol agent and spores of the pathogen is required to achieve inhibition of germination of spores EP.exampsum and its consequent infection. Observations made act crops P.agglomerans EPS125 grown in apple juice show along with a whole slew of filament-like type IV pili of interconnecting cells or multicellular clusters "symplasmata" wrapped in a layer of alginate. These observations suggest that both the filaments, which could be responsible for the movement like "twitching" leading to the formation of microcolonias, as glinato, production of which is influenced by the growing conditions could intervene in the early stages of training table or microbial biofilm by P.agglomerans EPS125, as well as playing a key role in inhibiting the germination of the spores of the pathogen. To really prove what mechanism is responsible for the activity biocontrolador of P.agglomerans EPS125 was used genetic analysis of mutants defective in biocontrol of P.expansum in apple obtained by random mutagenesis with minitransposón GUS (mTn5SSgusA40). Thus, 7 mutants completely defective in biocontrol of rotting blue (m40, m439, m622, m1212, m2002, m2126 and m4015 () were selected from a total of 4032 mutants not auxotróficos. Dichois mutants showed a similar morphology colonial above average minimum ABM; growth curves in the middle LB liquid trains propagated in manaza to 13 and 23 ° C, molecular signals from quorum sensing, and production quality of alginate. phenotypic differences regarding the strain only were observed in the mutant m2126 and m4015 in connection the deduced protein hypothetical in silico showed a 35% sequence identity with maino acids of the protein dihidrodipicolinato sintas DHDPS of different bacteria. DHDPS is a key enzyme in the biosynthesis route of meso-diaminopimelato (meso-DAP) in bacteria and plants , which is an essential constituent dela wall peptidoglicano bacterial and repercusores direct lysine. Owing to mutant m40 is not auxótrofo for lysine and possesses the route biosintética of DAP remains unchanged able to grow amid least has three inserted transposons in its genome, and sequencing nucleítidca flanqueante the transposon showed no similarity to any sequence currently placed in the database GEnBank, this mutant discarded as a candidate to be considered in this work. hypothetical proteins deduced from the nucleotide sequence of mutant m2126 from 876 to 1392 by 48-to 753 b shared similarity with a hypothetical protein of unknown function of Comamonas sp 33% protein and the family of luciferasa bacterial 55% respectively. According to the bibliography and the results described in this paper, everything seems to indicate that the mutation produced in the mutant m2126 could have altered a luciferasa FMN-dependiente (LuxAB) related gene regulation system via quorum sensing possibly affecting the production of filaments similar to those pili type IV and the subsequent formation of biofilm. deduced protein sequences from mutant m4015 showed 41% identity with lysine / ornithine N-monoxigenasas involved in the route biosintética of sideróforos type aerobactina. Suspected insertion transposón in the mutant m4015 could impair the ability of this element to P.expasum, which is essential to indicate the process of germination of the spores. Eventually, the nucleotide sequence of the mutants m2002 and m4015 showed a 90% sequence identity with insertion IS1222, which by Gross deletions and translocations contribute genetic processes flexibility and adaptation to the environment. Despite nucleotídicas that both sequences were identical, the insertion point of tranposón in the two mutants was different because the patterns obtained in the southern and characteristics fonotípicas of the two mutants did not match. The results obtained in this paper makes it possible to create a scenario of biofilm formation in P.agglomerans EPS125, which is involved in inhibiting the germination of the spores of the pathogen. First, the cells antagonists stick to the wound surface of the block using a variety of cellular components such as filament-like pilil type IV algianto. hair type These filaments could bind to different surfaces including other cell sbacterianas and spores pathogen prudiciendo mobility rate "twitching" through polymerization and retraction of the filaments pilosos. This movement about cells facilitating the formation of agglomerates mutlicelulares, and finally microcolonias where would include the spores of the pathogen. parallel, the initial adherence of the cells antagonists is followed by the production of polsiacáridos extracellular l type of alginate, which is induced only under certain conditions. addition, the cells EPS125 might be able to capture iron half through siderófors decreasing their availability to the pathogenic cells and preventing them the process of germination. then the microenvironment formed by the strain EPS125 could reduce the availability of different compounds like water, oxygen or iron that are essential to the germination of known P.expansum. addition, the strain EPS125 produces molecules involved in the HSL quorum sensing via regulation of genes that might be responsible for the differentiation of biofilm and its activity biocontroladora. Specifically, it could be directly related to the formation of filaments pilosos important in the process of differentiation of microbial mats, and other mechanisms biocontrol unknown employed by the biocontrol agent. Briefly, it biofilm formed by P.agglomerans EPS125 provides an appropriate environment for their growth, their physical structure allows resist environmental stress and inhibits infection caused by P.expansum depriving spores essential components as water. oxygen or iron, which shoot the process of germination. In conclusion, the results presented in this paper expands knowledge on the behavior of P.agglomerans in its natural environment and to reinforce the suitability of this stage as an interesting biopersticida in order to be commercially developed.