Thesis (Ph. D.)--University of Wisconsin--Madison, 1983. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 132-141).

Thesis (Ph. D.)--University of Delaware, 2006. / Principal faculty advisor: Eugene G. Mueller, Dept. of Chemistry & Biochemistry. Includes bibliographical references.

No description available.

Tyrosine tRNA was isolated from bovine liver and its nucleotide sequence was determined using in vitro 32p_ labeling techniques. Several important structural features of the tRNA are: the presence of gal-Q in the first position of the anticodon, acp3U at position 20, and a pair of adjacent N,N-dimethylguanosines (residues 26 and 27). A human DNA fragment harbored in a lambda phage clone was isolated, and restriction enzyme analysis revealed the presence of three tRNA genes in a 6.0-kb BamHI subfragment. Portions of the 6.0-kb DNA fragment containing the tRNA genes were sequenced by the method of Maxam and Gilbert and analyzed for transcriptional activity in vitro using homologous cytoplasmic extracts. A threonine tRNAUGU gene exhibited high transcriptional activity dependent on its 5'- flanking sequence. The enhanced transcription is not completely inhibited by alpha-amanitin. The value of studying tRNA structure in concert with the cognate tRNA. genes is discussed.

The yeast Saccharomyces cerevisiae decodes CAG codons using tRNAGlnCUG, encoded by the single-copy gene SUP70. On rich medium, the sup70-65 and sup70-33, alleles induce pseudohyphal growth, ordinarily a response to nitrogen limitation. sup70-65 tRNA is additionally a UAG stop codon suppressor. Characterisation of sup70 diploids revealed that they form pseudohyphal-like structures on both rich and N-deprived liquid, but not solid medium. Unlike canonical pseudohyphae, which bud in a unipolar fashion and are RAS2Val19 stimulated, sup70 pseudohyphal cells budded in a bipolar fashion that was RAS2Val19–resistant. Site-directed mutants of sup70-65 and sup70-33 that restored base complementarity in the mutant tRNA stems partially complimented the pseudohyphal phenotype and revealed that structural rigidity, rather than sequence identity, was the key phenotypic driver. A library of sup70 mutants, screened for novel nonsense UAG suppressor alleles, indentified several novel sites in the anticodon stem that induce tRNA distortion and UAG recognition. None of the new alleles induced formation of pseudohyphae. The sup70-65 pseudohyphal phenotype was weakly complemented through overexpression of the isoacceptor tRNAGlnUUG, which can inefficiently decode CAG via 3rd base wobble pairing, inferring pseudohyphal growth can be triggered by inefficient translation of CAG codons. Supporting this observation, tRNA Northern blotting revealed that all pseudohyphae-inducing sup70 mutants have reduced overall levels of tRNAGlnCUG, as well as reduced levels of tRNAGlnCUG charging. A systemic comparison of wild-type and sup70-65 proteomes using stable isotope labelling with amino acids revealed that 28 proteins showed significant changes in expression in the mutant, including 4 with known roles in control of bud size and/or budding pattern. This study revealed that pseudohyphae-inducing sup70 mutations compromise tRNAGlnCUG structure and amino acid charging and thus slow translation of cognate CAG codons, probably down-regulating the expression of a yet-to-be identified gene affecting the control of pseudohyphal differentiation.

Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2002. / On t.p. "Trp" is superscript. Includes bibliographical references (leaves 152-172). Also available in electronic version. Access restricted to campus users.

Thesis (M.S.)--Florida State University, 2004. / Advisor: Dr. Lloyd Epstein, Florida State University, College of Arts and Sciences, Dept. of Biological Science. Title and description from dissertation home page (viewed Jan. 12, 2005). Includes bibliographical references.

Thesis (Ph.D.)--University of Delaware, 2009. / Principal faculty advisor: Eugene G. Mueller, Dept. of Chemistry & Biochemistry. Includes bibliographical references.

The coding properties of the 3 major valine tRNA isoacceptors of Drosophila melanogaster, the nucleotide sequences of tRNA[sub=Val, sub=3b] and tRNA[sub=Val, sub=4] and the nucleotide sequences of genes for these two tRNAs have been determined. Valyl-tRNA[sub=Val, sub=3a] binds strongly to ribosomes in response to the trinucleotide GUA and to a lesser extent with GUU and GUG. Valyl- tRNA[sub=Val, sub=3b] binds strongly in the presence of GUG and very weakly with the other 3 triplets whereas valyl- tRNA[sub=Val, sub=4] binds strongly in the presence of GUU, GUC, and GUA and weakly with GUG. The nucleotide sequences of tRNA[sub=Val, sub=3b] and tRNA[sub=Val, sub=4] were determined by a combination of techniques. For both tRNAs most of the sequence was determined by the method of Stanley and Vassilenko. The sequences at the 5' and 3'-ends of the molecules were determined by wandering-spot analysis. Regions of the molecules that could not be sequenced by these two techniques were determined by the gel read-off method. The use of tRNA modified with chloroacetaldehyde to overcome problems in sequencing RNA by the gel read-off method caused by secondary structure in the RNA is described. The nucleotide sequence of tRNA[sub=Val, sub=4] is: GUUU[sub=m]⁷CCGUm¹GGUG ѱAGCGGDU (acp³ U)AUCACA1ѱCUGCC[sub=m]UIACAm⁵CGCAGAAGm⁷GCCCCCGGѱC Gm¹ AUCCCGGGCGGAAACACCA. About 50% of the U residues at position 20 are modified to acp³U. One of the C residues at position 48 or 49 is probably modified to m5C. The nucleotide sequence of tRNA[sub=Val, sub=3b] is: GUUUCCGѱAGUGS1 AGCGGDacp³ UAUCACGѱGUGCUUC ACACGCACAAGm⁷- GDCCCCGGTѱCGm¹ AACCC GGGCGGGAACACCA. The C residue at position 48 is probably modified to m⁵C. The observed codon responses of the two tRNAs are discussed in relation to the anticodons found. Val The two tRNA[sub=Val, sub=4] genes of the recombinant plasmid pDt55 were sequenced by the Maxam and Gilbert method. This plasmid hybridizes to the 70BC site on the polytene chromosomes, a major site of tRNA[sub=Val, sub=4] hybridization. The two genes are of opposite polarity and are separated by 525 bp of DNA. The genes have identical sequences, which correspond to that expected from the sequence of tRNA[sub=Val, sub=4]. The nucleotide sequence of the tRNA[sub=Val, sub=3b] gene of recombinant plasmid pDt78R was also determined. This plasmid hybridizes to the 84D site, a major site of tRNA[sub=Val, sub=3b] hybridization. The sequence of the gene corresponds to that expected from the sequence of tRNA[sub=Val, sub=3b]. Comparison of the valine tRNA genes sequenced in this study and those determined by other workers shows that tRNA genes from major sites of tRNA[sub=Val, sub=3b] or tRNA[sub=Val, sub=4] hybridization to polytene chromosomes correspond exactly to the tRNA[sub=Val] sequences while tRNA tRNA[sub=Val] genes from minor sites of tRNA hybridization differ at 4 positions from the sequences expected on the basis of the tRNA sequences. The possible significance of this finding is discussed. / Medicine, Faculty of / Biochemistry and Molecular Biology, Department of / Graduate

Serine tRNAs and their genes in Drosophila melanogaster were characterized. The nucleotide sequences of tRNA₄[sup=Ser] (codon UCG), tRNA₇[sup=Ser] (UCA, UCC, UCU), and tRNA[sub=2b][sup=Ser] (AGC, AGU) were determined. Also, the nucleotide sequences of four tRNA[sup=Ser] genes from the X chromosome isolated in recombinant plasmids were determined. Transfer RNA₄[sup=Ser] and tRNA₇[sup=Ser] differ at only three out of 85 positions, including the "wobble" nucleotide of the anticodon. However, tRNA[sub=2b][sup=Ser] is only 72% homologous with tRNA₄[sup=Ser] (62 out of 85 positions, not counting differences in modification). Major regions of sequence homology (> 5 consecutive positions) are found only in the D arm (21 consecutive positions) and in the TѱC arm (11 consecutive positions). Transfer RNA₄[sup=Ser] and tRNA₇[sup=Ser] are indistinguishable by RNA-DNA hybridization. Both hybridize to the same sites on polytene chromosomes in situ, including the major site at 12DE on the X chromosome, and 23E on chromosome 2 (Hayashi et al. (1980). Chromosoma 76, 65-84.) No other purified tRNA than tRNAs[sub=4,7][sup=Ser] has been shown to hybridize to the X chromosome in Drosophila. Therefore, several X-derived recombinant plasmids hybridizing tRNA[sub=4,7][sup=Ser] (pDt 16, pDt 17R, pDt 27R, and pDt 73; Dunn et al. (1979). Gene ], 197-215.) were analyzed. Based on the results of Southern blotting experi-ments, there appear to be eight tRNA[sup=Ser] genes on the four plasmids (one each on pDt 17R and pDt 73; two on pDt 16; and four on pDt 27R). Thus, the 12DE region contains at least eight tRNA[sup=Ser] genes. Restriction mapping and DNA sequence analysis were performed with pDt 16, pDt 17R, and pDt 73. Based on the tRNA sequences, which differ at three positions, the presumptive DNA sequences encoding tRNA[sub=4] [sup=Ser] and tRNA[sub=7] [sup=Ser] can be represented as 444 or 777 genes. DNA sequence analysis gave surprising Ser results in this respect. Analysis of four tRNA[sup=Ser] genes on the three plasmids S identified two 777 genes matching tRNA₇[sup=Ser] plus "hybrid" 774 and 474 sequences. Further, pDt 16 contains both a 777 and a 774 gene as a direct repeat 400 Ser base pairs apart. Since a 444 gene corresponding to tRNA₄[sup=Ser] must exist, there are at least four different types of closely related serine tRNA genes in the D. melanogaster genome. This observation may have implications concerning the evolution and maintenance of reiterated tRNA genes in eukaryotes. In addition to studies on serine tRNAs and their genes, the nucleotide sequences of Drosophila tRNA₅[sup=Lys] and of a tRNA[sup=Arg] were determined. / Medicine, Faculty of / Biochemistry and Molecular Biology, Department of / Graduate