Molecular Biology Commons^™

A Molecular Basis For Erythromycin Sensitivity And Resistance In Escherichia Coli, Harold S. Chittum

Electronic Theses and Dissertations

The effect of erythromycin on the 50S ribosomal subunit during cell growth has been extensively investigated. Sucrose density gradient analysis of ribosomes formed in the presence and absence of the drug revealed a 50S specific assembly defect is partially responsible for erythromycin's inhibitory effects on wild type cells. Examination of two erythromycin-resistant mutants of E. coli (N281 and N282) revealed that mutant N281 (L22 mutant) but not N282 (L4 mutant) was assembly defective in the presence of the drug, although only at much higher drug concentrations (300 ug/ml vs. 75 ug/ml for wild type cells). The altered genes from each …

Unusual Structure Of A Human Middle Repetitive Dna, Duminda D. Ratnasinghe

Electronic Theses and Dissertations

The L2Hs sequences are a polymorphic, interspersed, middle repetitive DNA family unique to human genomes. Genomic fingerprinting indicates that these DNAs vary from one individual to another and between tissues of the same individual. Sequence analysis reveals that they are AT-rich (76%) and contain many unusual sequence arrangements (palindromes, inverted and direct repeats). These sequence properties confer on the L2Hs elements the potential to fold into non-B-form structures, a characteristic of recombination hot spots. To test this hypothesis carbodiimide, osmium tetroxide and S$\sb1$ nuclease were used as single-strand specific probes to study a recombinant plasmid, pN6.4.39, containing a single L2Hs …

Studies On Type I And Type Ii Dna Topoisomerases From Mammalian Mitochondria, Jia-Hwei Lin

Theses and Dissertations in Biomedical Sciences

Mammalian mitochondria contain a unique DNA topoisomerase I with characteristics of both nuclear and bacterial type I DNA topoisomerases. This enzyme, purified from bovine liver, requires cations as cofactors and possesses optimal activity at pH 7.0, 37°C and either 150 mM K+ or Na+ ions. Similar to nuclear enzymes and different from the bacterial enzyme, divalent ions such as Ca²⁺ or Mg²⁺ will stimulate but are not essential for the enzymatic activity.

Like the nuclear DNA topoisomerase I, the mitochondrial enzyme is capable of relaxing both negatively and positively supercoiled DNA. The relaxation of negatively supercoiled DNA is …

Cloning A Putative Dna-Binding Protein Controlling The 5'Ltr Of The Copia Element In Drosophila, Horng-Yuan Kan

Theses and Dissertations in Biomedical Sciences

Copia, a Drosophila retrotransposon, is constitutively expressed in all developmental stages, except the embryo in Drosophila melanogaster. The effect of random integration of the copia element results in phenotypic change in Drosophila. The regulatory sequences, controlling copia expression, are located within the 5'LTR. The DNA sequence in the 5'LTR and in the location between downstream of entire the 5' LTR and the initial translation site have been identified by mobilityshift binding assays and DNase I footprinting assays. The data reveals three protected regions: a TATA-binding site, the AT-1, and AT-2 binding sites. The TATA-binding site and AT-1 site are …

Effects Of Bifunctional Chemotherapeutic Agents On Gene Expression In The Human Tumor Cell Line Colo320hsr, Qing Dong

Dissertations

No abstract provided.

Analysis Of The Dna Repair/Ribosomal Protein Ap3/Po Gene In Drosophila (Homologue To Human Po), David T. Grabowski

Dissertations

No abstract provided.

The Antidiabetic Agent Pioglitazone Enhances Adipocyte Differentiation Of 3t3-F442a Cells: Regulation Of Glucose Transport Activity And Differentiation-Dependent Gene Expression, Tagrid Sandouk

Dissertations

No abstract provided.

Induction Of Proteases And Their Inhibitors In Cell Lines Of Different Metastatic Potentials And Activated Oncogenes, Jianyi Zhang

Dissertations

No abstract provided.