Giessen, Universiẗat, Diss., 2000.

No description available.

Thesis (M.Sc.)--York University, 2003. Graduate Programme in Biology. / Typescript. Includes bibliographical references (leaves 122-134). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pMQ86279

The nucleotide sequence of cnjB, a conjugation specific gene of Tetrahymena thermophila, has been determined. The gene encodes a putative polypeptide (CnjB) of 1748 amino acids with a calculated molecular weight of 200 kilodaltons and a pI of 7.9. Four transcription start sites were mapped. The gene has only one genomic copy and is not conserved in yeast (as determined by cross-hybridization experiments with yeast DNA). Analysis of the 13 introns in cnjB, accompanied by 15 other T. thermophila intron sequences, shows that they resemble the nuclear pre-mRNA introns of other eukaryotes. / The carboxy-terminal third of CnjB has three regions with repetitive sequences. One region contains seven retroviral-type zinc fingers and the others contain repeated glycine-rich motifs, a motif seen in the heterogeneous nuclear ribonuclear proteins A1 and A2/B1. Proteins with these motifs have single-strand binding and strand annealing activity. / Synthetic phosphorothioate oligonucleotides antisense to regions of the isoleucyl tRNA synthetase gene transcript did not affect cell growth in a sequence-specific manner when cultures of T. thermophila were grown in their presence.

The nucleotide sequence of the cnjA cDNA (formerly pC1) from the ciliated protozoan Tetrahymena thermophila was determined. This gene was previously found to be conjugation specific and to peak in expression just prior to or at pachytene in meiotic prophase I. The cnjA message is initiated from four transcription start sites, one minor and three major, and encodes a putative protein (CnjA) of 779 amino acids. The protein has a calculated molecular weight of 89.5 kDa and is mainly hydrophilic with an estimated pI of 9.3. CnjA was found to share no sequence similarities with any known protein to date. The gene's coding region demonstrates an unusual codon choice. Flanking regions of the cnjA genomic locus were amplified by means of the Inverse PCR method but attempts at subcloning and characterizing its promoter region were unsuccessful.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 148-161). Also available via the Internet.

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Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 53-69). Also available via the Internet.

The iron-sulfur flavoprotein (Isf) from the acetate utilizing methanoarchaeon Methanosarcina thermophila was heterologously produced in Escherichia coli, purified to homogeneity, and characterized to determine the properties of the iron-sulfur cluster and FMN. Chemical and spectroscopic analyses indicated that Isf contained one 4Fe-4S cluster and one FMN per monomer. The midpoint potentials of the [4Fe-4S]2+/1+ center and FMN/FMNH2 redox couple were -394 and -277 mV respectively. The deduced amino acid sequence of Isf revealed high identity with Isf homologues from the CO2 reducing methanoarchaea Methanococcus jannaschii and Methanobacterium thermoautotrophicum. Extracts of H2-CO2-grown M. thermoautotrophicum cells were able to reduce Isf from M. thermophila using either H2 or CO as the reductant. Addition of ferredoxin A to the reaction further stimulated the rate of Isf reduction. These results suggest that Isf homologues are coupled to ferredoxin in electron transfer chains in methanoarchaea with diverse metabolic pathways. Reconstituted systems containing carbon monoxide dehydrogenase/acetyl-CoA synthase complex (CODH/ACS), ferredoxin A, Isf, and the designated electron carriers (NAD, NADP, F420, and 2-hydroxyphenazine) were used in an attempt to determine the electron acceptor for Isf. Isf was unable to reduce any of these compounds. Furthermore, 2-hydroxyphenazine competed with Isf to accept electrons from ferredoxin A indicating that ferredoxin A is a more favorable electron partner for 2-hydroxyphenazine. Thus, the physiological electron acceptor for Isf is unknown. Amino acid sequence alignment of Isf sequences revealed a conserved atypical cysteine motif with the potential to ligate the 4Fe-4S cluster. Site-directed mutagenesis of the cysteine residues in this motif, and the two additional cysteines in the sequence, was used to investigate these cysteine residue as ligands for coordinating the 4Fe-4S center of Isf. Spectroscopic and biochemical analyses were consistent with the conserved cysteine motif functioning as ligating the 4Fe-4S center. Redox properties of the 4Fe-4S and FMN centers revealed a role for the 4Fe-4S center in the transfer of electrons from ferredoxin A to FMN. / Ph. D.

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