No description available.

No description available.

Diss. (sammanfattning) Stockholm : Karol. inst., 2001. / Härtill 3 uppsatser.

Thesis (Ph. D.)--University of Texas at Austin, 2005. / Vita. Includes bibliographical references.

Thesis (Ph. D. in Biological Sciences)--Vanderbilt University, Aug. 2005. / Title from title screen. Includes bibliographical references.

Thesis (Ph. D.)--Florida State University, 2006. / Advisor: Nancy L. Greenbaum, Florida State University, College of Arts and Sciences, Dept. of Chemistry and Biochemistry. Title and description from dissertation home page (viewed Jan. 2, 2007). Document formatted into pages; contains xix, 173 pages. Includes bibliographical references.

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2006. / Title from title screen (site viewed on September 12, 2006). PDF text of dissertation: 172 p. : ill. (some col.) ; 2.15Mb. UMI publication number: AAT 3209964. Includes bibliographical references. Also available in microfilm, microfiche and paper format.

Splicing mainly occurs co-transcriptionally, suggesting that transcription and premRNA splicing could be synchronized. The nature of this phenomenon suggests that transcription elongation rate may influence splicing outcomes and, indeed, there is evidence for effects on alternative splicing in mammals. To elucidate potential effects of transcription rate on splicing efficiency and fidelity, splicing of nascent transcripts was investigated in fast and slow elongating RNA polymerase II (RNAPII) mutants in Saccharomyces cerevisiae. High kinetic resolution 4-thio Uracil labelling of nascent RNA reveals that fast RNAPII accumulates unspliced pre-mRNA that represents reduced co-transcriptional splicing. Conversely, low levels of unspliced pre-mRNA were detected in the slow mutant due to increased co-transcriptional splicing. The highly stable association of nascent transcripts with elongating RNAPII permits co-transcriptional splicing to be measured by analysis of transcripts that co-purify with RNAPII. Measuring co-precipitation of the spliced mRNA and excised intron that are associated with RNAPII demonstrates that splicing is mostly co-transcriptional with the slow mutant, and the fast mutant reduces co-transcriptional splicing. How elongation rate affects splicing fidelity in budding yeast and whether faster and slower transcription have the opposite effect on splicing fidelity as might be predicted by the kinetic coupling model is an open question. Using deep RNA sequencing, splicing fidelity was determined in yeast transcription elongation mutants. Results show that both fast and slow transcription reduce splicing fidelity mainly in ribosomal protein coding transcripts. Analysis reveals that splicing fidelity depends largely on intron length, secondary structure and splice site score. These analyses also provide new insights regarding the effect of altering transcription rate on selection of transcription start sites. Together, these results indicate that optimal splicing efficiency and fidelity require finely-tuned transcription speed.

Splicing is a process that occurs in the nuclei of all eukaryotic cells, removing non-coding sections from pre-mRNA in the final step of transcription. The process consists of two transesterification reactions carried out via interaction with the spliceosome - a large, highly dynamic RNA/protein complex essential in catalysing splicing. Fusidic acid has been shown previously to inhibit splicing, potentially by interaction with snRNA U5 of the spliceosome. This project attempts to elucidate the mechanism of binding, with a view to improving the inhibitory function of the compound. This was achieved by developing photo-crosslinking compounds which could be used to elucidate the protein structure of the binding site, and subsequently the interactions between U5 and fusidic acid. Chapter one discusses the nature of the splicing, as well as examples of photo-crosslinking ligands and their use in biological studies to date. The early sections of chapter three outline the synthesis of the photo-crosslinking compounds and subsequent incorporation into the skeleton of fusidic acid. The latter sections describe the investigations into the structural modifications to fusidic acid, and in particular how these affect the inhibitory function of the molecule. A number of pathways outlined here have been eliminated as unsuccessful in the functionalisation of fusidic acid. Attachment of both diazirinyl and benzophenone compounds was achieved in reasonable yield. While these compounds were insufficiently active to be taken further in the cross-linking study, active intermediates synthesised during the pathway to these compounds have been discovered. These were investigated further, and one compound in particular has shown promise as a potential therapy. Also explored was iodolactonization of fusidic acid, introducing restriction of movement to the side chain via cyclisation. The ambiguous structures of the products were confirmed using X-ray crystallography, and elimination of iodine was investigated to allow for further functionalisation at this position.

Microsporidia are unicellular fungi that are intracellular parasites of animals, including humans. They are both complex and simple, armed with a sophisticated infection apparatus and possessing the smallest eukaryotic nuclear genomes. The microsporidian Encephalitozoon cuniculi has a genome size of 2.9 Mb, which is smaller than many bacterial genomes. Genome reduction and compaction in size, content, and form has been interpreted as an adaptation to parasitism. One of the effects of genome size reduction concerns intron evolution — E. cuniculi has retained only a few extremely short spliceosomal introns. This thesis examines the splicing of introns in the spore stage. The introns were retained in spores, suggesting life-stage specific splicing and splicing inhibition. How the short introns are recognized was also examined. Unique splicing signal motifs were predicted, and were used to find additional introns. The intron density was doubled for this species, and I also obtained data that counter current views about intron evolution in compacted genomes with low intron densities. I also predict that E. cuniculi introns are recognized in a unique way by the spliceosome. / Medicine, Faculty of / Medical Genetics, Department of / Graduate