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Articles 1 - 8 of 8

Full-Text Articles in Molecular Biology

Host Regulation Of The Replication Of The Yeast Retrotransposon Ty5 , Ning Ke Jan 1997

Host Regulation Of The Replication Of The Yeast Retrotransposon Ty5 , Ning Ke

Retrospective Theses and Dissertations

The replication of retroelements may have deleterious effects on the hosts. Therefore, elements and their hosts have coevolved mechanisms to regulate retroelement replication. This regulation can occur at the transcriptional, translational, or post-translational levels as well as through targeted integration or cDNA recombination. I have studied host regulation of the Saccharomyces retrotransposon Ty5. I have found that Ty5 transcription is carefully controlled. Transcription of Ty5 is haploid specific and is repressed 10 fold in diploid strains. Ty5 transcription is also regulated by the pheromone response pathway, which is activated during mating. In addition, Ty5 transcription is regulated by flanking sequences ...


Regulation Of Brucella Abortus Catalase As A Defensive Mechanism Against Oxidative Stress , Jeonga Kim Jan 1997

Regulation Of Brucella Abortus Catalase As A Defensive Mechanism Against Oxidative Stress , Jeonga Kim

Retrospective Theses and Dissertations

Free radicals in the nature are harmful to organisms because they cause damage to tissues, cell membranes, proteins, and DNA. The animal immune system (cell mediated immune response) uses oxygen molecules to kill foreign organisms. B. abortus causes a cattle disease called brucellosis. The mechanism for bacteria to survive and adapt in the face of oxidative attack is thought to be important for understanding pathogenesis. This dissertation presents the response of B. abortus to oxidative stress and the regulation of catalase as a defensive mechanism;Different protein expression patterns were observed during oxidative stress by conducting 2-D protein gel analysis ...


Differential Glycosylation Of Tractin And Leechcam, Two Novel Ig-Superfamily Members, Regulates Neurite Extension And Fascicle Formation , Yueqiao Huang Jan 1997

Differential Glycosylation Of Tractin And Leechcam, Two Novel Ig-Superfamily Members, Regulates Neurite Extension And Fascicle Formation , Yueqiao Huang

Retrospective Theses and Dissertations

Specific carbohydrate structures on neural cell adhesion molecules are promising candidates for assisting in patterning neural connections during development. An excellent system to study the potential function of specific oligosaccharide modifications of neural proteins regulating pathway formation is in the projections of sensillar neurons in leech. At least five different monoclonal antibodies (Lan3-2, Lan2-3, Lan4-2, Laz2-369, Laz7-79) which recognize different glycoepitopes specific to the entire population as well as distinct subsets of these sensillar neurons have been identified. Their expression patterns and antibody perturbation studies are consistent with the hypothesis that a hierarchy of distinct carbohydrate structures expressed by specific ...


Genetic And Biochemical Analysis Of Aspergillus Awamori Glucoamylase Thermostability , Martin John Allen Jan 1997

Genetic And Biochemical Analysis Of Aspergillus Awamori Glucoamylase Thermostability , Martin John Allen

Retrospective Theses and Dissertations

Aspergillus awamori glucoamylase (GA) is an enzyme involved in industrial corn starch processing. Genetic and biochemical approaches were used to study the mechanisms governing GA thermostability. Three proline substitution (Xaa → Pro) mutations were constructed that were predicted to increase the enzyme's stability by decreasing its conformational entropy of unfolding. When expressed in Saccharomyces cerevisiae Ser30 → Pro increased, Asp345 → Pro did not alter and Glu408 → Pro greatly decreased GA stability as measured by resistance to irreversible thermoinactivation relative to the wild-type enzyme. The Ser30 → Pro mutation was combined with other previously identified stabilizing mutations to examine whether combining such mutations ...


Molecular Cloning And Characterization Of Gl8, A Gene Involved In Maize Cuticular Wax Biosynthesis , Xiaojie Xu Jan 1997

Molecular Cloning And Characterization Of Gl8, A Gene Involved In Maize Cuticular Wax Biosynthesis , Xiaojie Xu

Retrospective Theses and Dissertations

The gl8 locus of maize was previously defined by a mutation that reduces the amount and alters the composition of seedling cuticular waxes. Sixty independently derived gl8 mutant alleles have been isolated from stocks that carried the Mutator transposon system. A DNA fragment that contains a Mu8 transposon and that co-segregates with one of these alleles, gl8-Mu3142, was identified and cloned. DNA flanking the Mu8 transposon was shown to represent the gl8 locus via allelic cross-referencing experiments. The gl8 probe reveals a 1.4-kb transcript present in wild-type seedling leaves, and in lesser amounts, in other organs and at other ...


Cloning And Characterization Of A Soybean Snf2 Yeast Homolog , Weiping Chen Jan 1997

Cloning And Characterization Of A Soybean Snf2 Yeast Homolog , Weiping Chen

Retrospective Theses and Dissertations

It is of great economic and scientific interest to understand plant disease resistance genes at the molecular level. Phytophthora sojae, a fungal pathogen of soybean is of particular interest since the root and stem rot resulting from its infection causes great economic loss. It is the goal of this project to clone Phytophthora resistance genes from soybean. This was done by designing primers from the conserved regions of known plant disease resistance genes using a modified differential display for near isogenic lines; L85-3044 a resistant line and Williams, a susceptible line. Several polymorphic bands were identified, including a unique 0 ...


Studies Of Cis- And Trans-Acting Elements In Tetrahymena Rdna Replication , Chunying Du Jan 1997

Studies Of Cis- And Trans-Acting Elements In Tetrahymena Rdna Replication , Chunying Du

Retrospective Theses and Dissertations

Eukaryotic cells must precisely duplicate their genomes before they divide. The mechanisms of eukaryotic chromosomal DNA replication are far from clear, however, because very few cis- and trans-acting factors that function in eukaryotic DNA replication have been identified. To gain further insights into this problem, this work identified and characterized potential cis- and trans-acting replication factors for the replication initiation of Tetrahymena ribosomal RNA gene (rDNA);A search far cis-acting elements identified a cluster of predicted modular sequences and structural elements in the origin region of rDNA. The presence of these elements were verified experimentally; (1) two mung bean nuclease-hypersensitive ...


Molecular Characterization Of Cer2, An Arabidopsis Gene Involved In Cuticular Wax Accumulation , Yiji Xia Jan 1997

Molecular Characterization Of Cer2, An Arabidopsis Gene Involved In Cuticular Wax Accumulation , Yiji Xia

Retrospective Theses and Dissertations

Cuticular waxes are complex mixtures of very long chain fatty acids (VLCFAs) and their derivatives. The CER2 locus of Arabidopsis is involved in cuticular wax accumulation on stems, siliques, and hypocotyls. The CER2 gene was cloned via chromosome walking. This cloned sequence is able to complement the cer2 mutant phenotype. It is a single-copy sequence in the Arabidopsis genome and encodes a novel protein with a predicted mass of 47 kD. Anti-CER2 polyclonal antibodies detected a 47 kD polypeptide. Cell fractionation and immunoblot analyses demonstrated that the CER2 protein is not membrane-bound and localized in nuclei. These results suggest that ...