No description available.

Thesis--Catholic University of America. / Bibliography: p. 33-36.

Thesis (Ph. D.)--University of Chicago, Dept. of Molecular Genetics and Cell Biology, June 1999. / Includes bibliographical references. Also available in the Internet.

Here the ciliate protozoa Tetrahymena thermophila was used as a model system to study the DNA damage response. Tetrahymena enclose nuclear dimorphism, a polyploid somatic macronucleus (MAC), which is transcriptionally active and maintains vegetative growth, and a diploid germline micronucleus (MIC) responsible for the transmition of genetic information during conjugation. Previous studies have identified Tif1p, a novel protein involved in the regulation of rDNA replication in Tetrahymena. TIF1 hypomorphic strains acquire spontaneous DNA damage during vegetative cell cycle and are hypersensitive to DNA damaging agents. TIF1-deficient strains acquire DNA damage in both nuclear compartments, suggesting a global role of Tif1p in the maintenance of genomic stability. In my dissertation research, I studied the role of Tif1p during the cell cycle progression. To this end, I generated tagged-Tif1p strains, which revealed that the subcellular localization of Tif1p is dynamic throughout the cell cycle. However, the addition of epitope tag to this protein generated phenotypes analogous to ones observed in a TIF1-deficient strain. This suggested that the addition of epitope tag to Tif1p severely affects the properties of Tif1p and hence the overall integrity of the cell. To overcome these limitations, a peptide antibody specific to Tif1p was generated to study the endogenous protein. This work revealed that the abundance of Tif1p protein is not cell cycle regulated and that Tif1p is absent in starved cells. Furthermore, the specific binding of TIf1p to rDNA minichromosome was studied during vegetative cell cycles. Chromatin immunoprecipitation studies revealed that the specific binding of Tif1p extends beyond the cis-acting determinant of replication present at the rDNA origin and promoter. This suggests that coding regions may be targeted for the binding of Tif1p to previously uncharacterized sequences, and that Tif1p preferentially localizes on the rDNA minichromosome. I also studied the induction of DNA damage response, demonstrating that Tetrahymena activates a checkpoint response mediated by an ATR-like pathway. Studies with a hypomorphic TIF1 strain revealed that Tif1p mediates proper activation of the DNA damage response. Further characterization of the response to genotoxic agents showed that Tetrahymena is able to activate a G1/S and intra-S phase DNA damage response. The results presented here suggest that a caffeine-dependent checkpoint activator protein modulates the response to DNA damage. In addition, a subunit of the replicative helicase, Mcm6p, is directly affected by the induction of DNA damage. This suggests that Tetrahymena uses a novel mechanism to halt the progression of DNA replication forks during genotoxic stress through degradation of Mcm6p.

Thesis (M.S.)--University of Alabama at Birmingham, 2007. / Description based on contents viewed Oct. 5, 2007; title from title screen. Includes bibliographical references (p. 38-42).

No description available.

Honors Project--Smith College, Northampton, Mass., 2010. / Includes bibliographical references (p. 18-21, 54-60).

Charles University in Prague Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Botany and Ecology Author: Radka Kvapilová Supervisor: RNDr. Jitka Vytlačilová, Ph.D. Title of diploma thesis: Antiprotozoal activity of alkaloids II. The development of new antiprotozoal agents for the treatment of infections is very important. Natural substances can be the source of effective drugs. The aim of this study was to evaluate the antiprotozoal activity of these alkaloids - canadine, scoulerine, tetrahydropalmatine and stylopine. The experiment was conducted on typical model organism Tetrahymena thermophila. Percentage inhibition of the organism was determined using the MTT assay. Subsequently median inhibitory concentration IC50 of the test substances was calculated. From our alkaloids stylopine had the greatest antiprotozoal activity. Antiprotozoal activity decreased in the following order stylopine > canadine > scoulerine > tetrahydropalmatine. Key words: Tetrahymena thermophila, antiprotozoal activity, canadine, scoulerine, tetrahydropalmatine, stylopine

Thesis (M.Sc.)--York University, 2008. Graduate Programme in Biology. / Typescript. Includes bibliographical references (leaves 185-210). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR45967

Isoleucyl-tRNA synthetase genes from the yeast Saccharomyces cerevisiae and the ciliated protozoan Tetrahymena thermophila were sequenced. The intronless S. cerevisiae gene (ILS1) encodes a putative polypeptide of 1072 amino acids. Two putative promoter elements were identified, one for general amino acid control and one for constitutive transcription. A heat shock protein gene lies upstream of ILS1. The T. thermophila isoleucyl-tRNA synthetase gene (ilsA: formerly cupC) has eight introns, four transcription start sites, and codes for a putative polypeptide of 1081 amino acids with two leucine-zippers. These eukaryotic isoleucyl-tRNA synthetases are 47% identical. They are compared to homologous enzymes from Escherichia coli and an archaebacterium, and to other aminoacyl-tRNA synthetases. / Intron sequences and junctions from T. thermophila and other eukaryotes were analyzed and all but yeast and mammalian introns were found to be A + T enriched. T. thermophila transcription start sites were analyzed and occur at a T or an A within the consensus sequence (A/T)$ sb{ rm n}$ T A A (A)$ sb{ rm n}.$