Thesis (M.S.)--University of Hawaii at Manoa, 2006. / Includes bibliographical references (leaves 50-56). / viii, 56 leaves, bound ill. (some col.) 29 cm

Inteins are autocatalytic protein domains that splice out of the nascent polypeptide shortly after translation, requiring no co-factors to facilitate splicing. There is an intein coding sequence within the Prp8 gene of Cryptococcus neoformans, a human pathogen that causes cryptococcosis in immunocompromised people. The intein, Cne PRP8, is a drug target as Prp8 is a central component of the spliceosome and thus believed to be essential to the fungus. Improved knowledge of the intein and its requirements for splicing can contribute to design of a screening system and the search for an inhibitor of intein splicing. Purification of Cne PRP8 for crystallisation was performed using either an N- or a C-terminal His�Tag�, where the N-terminal His�Tag� was removed by 3C protease prior to crystallisation trials. C-terminally His�Tagged� Cne PRP8 formed the largest crystals. The crystals were triangular plates with stepped faces. A 2.8 Å data set was collected with an R[merge] of 0.151 and a mosaicity of 2.1�. A smaller crystal gave a 3.6 Å data set with an R[merge] of 0.085 and a mosaicity of 1.5�. Molecular replacement was not sufficient to solve the structure, likely because the data were weak and the molecules in the asymmetric unit too numerous. Purified Cne PRP8 was additionally shown by circular dichroism to lack regular secondary structure, suggesting that regions of Cne PRP8 could be natively unstructured. Cne PRP8 was expressed as a fusion protein between Haemophilus influenzae trigger factor (HiTF) and a chitin binding domain (CBD). Antibodies to the different parts of the fusion protein facilitated the observation of splicing ability by western blotting. From this it was determined that Cne PRP8 is capable of splicing in a foreign protein context. Context is important, with maximum splicing occurring when Cne PRP8 has two native N-terminal extein residues and one native C-terminal extein residue. The first residue and the last two residues of Cne PRP8 are essential for splicing; additionally the conserved threonine (T62) and histidine (H65) were shown to be catalytically important. Also required for splicing are arginine 154, tyrosine 162, and aspartate 166. Leucine 161 undergoes ~50% splicing when mutated to alanine, and tryptophan 151 undergoes limited C-terminal cleavage, but no splicing, when mutated to alanine. Tryptophan 151 was identified as a potentially crucial residue, which may function to prevent C-terminal cleavage before the N-terminal rearrangements have taken place. Overall it appears that Cne PRP8 residues that are more diverged from the general intein consensus are less essential for splicing. Wild type Cne PRP8 is insensitive to zinc inhibition in vivo. It is also unresponsive to cadmium, calcium, cobalt, lithium, magnesium, manganese and nickel. However, a partially splicing-deficient mutant exhibited further inhibition in response to zinc and cadmium. This mutant also showed a limited increase in splicing efficiency in response to temperatures lower than 37�C. This study has identified critical residues, in addition to those at the splice junctions necessary for catalysis, which participate in splicing intermediates.

Thesis (M. Ag. Sc.)--University of Adelaide, Dept. of Plant Science, 1998. / Includes bibliographical references (leaves 103-124).

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1990. / Vita. Abstract. Includes bibliographical references (leaves 87-88). Also available via the Internet.

Thesis (Ph.D.) -- University of Adelaide, Dept. of Plant Science, Waite Campus, 2001? / Bibliography: leaves 127-151.

Thesis (Ph.D.)--George Mason University, 2009. / Vita: p. 122-123. Thesis director: John Weinstein. Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Bioinformatics. Title from PDF t.p. (viewed June 10, 2009). Includes bibliographical references (p. 117-121). Also issued in print.

Thesis (Ph. D) -- University of the Western Cape, 2007. / Includes bibliographic references (leaves 214-261).

Thesis (Ph. D) -- University of the Western Cape, 2007. / Includes bibliographic references , (186-222).

Bibliography: leaves 127-151. The successful application of genetic engineering in wheat is dependent on the availability of suitable tissue culture and transformation methods. The primary object of this project was the development of these technologies using elite Australian wheat varieties.

The hexanucleotide repeat expansion (HRE) mutation within C9orf72 gene is the most common cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Several hypotheses have been proposed for how the mutation contributes to pathogenicity, including the loss of C9orf72 gene function, RNA-mediate toxicity and the formation of toxic dipeptides by repeat-associated non-ATG (RAN) translation. Patient-specific iPSCs provide a promising tool for the study of the cellular and molecular mechanisms of human diseases in relevant cell types and discovering potential therapies. The CRISPR (clustered regularly interspaced short palindromic repeats)-Cas9-mediated homology directed repair (HDR) system represents an attractive approach for disease modelling and development of therapeutic strategies. In this thesis, iPSCs derived from ALS/FTD patient carrying the HRE mutation were generated and subsequently gene edited to remove a massive repeat expansion from the patient cells and replace it with the wild-type size of the repeats using HDR and a plasmid donor template. The successful genotypic correction of the mutation resulted in the normalization of the C9orf72 gene promoter methylation level and the gene variants RNA expression level. Removal of the mutation also resulted in abolition of sense and antisense RNA foci formation and reduction of DPRs accumulation. Furthermore, the repeat size correction also rescued the susceptibility of cells to Glutamate excitotoxicity, decreased the apoptotic cell death and stress granules formation under the baseline and stress conditions. This work provides a proof-of-principle that removal of the HRE can rescue ALS disease phenotypes and provides an evidence that HRE mutation is an attractive target for therapeutic strategies and drug screening, to block the underlying disease mechanisms.