Life Sciences Commons^™

Analysis Of Vehicle Use Patterns During Military Field Exercises To Identify Potential Roads, Chunxia Wu

Doctoral Dissertations

Military training is an intensive land use and can cause negative environmental effects. Many studies conducted under Integrated Training Area Management (ITAM) for quantifying the impact resulted from the military training exercise found that off-road vehicular activities during training exercises cause the major impact to the training land. Vehicle land use patterns at a certain location affect the impact severity: concentrated and repeated traffic create more serious damage to the land compared to the dispersed offroad vehicle movements. Those areas heavily disturbed by off-road traffic may require a longer period of time or special treatments for the land to return …

High Resolution X-Ray And Neutron Crystallographic Studies Of Escherichia Coli Dihydrofolate Reductase, Brad C. Bennett

Doctoral Dissertations

Dihydrofolate Reductases (DHFRs) have been identified in nearly every proteome and are essential for most biosynthetic pathways involving one-carbon transfer reactions due to their recycling of tetrahydrofolate (THF). They catalyze the NADPH-dependent reduction of dihydrofolate (DHF), producing THF. Inhibition of DHFR ultimately depletes cellular pools of THF; causing a reduced supply of thymine nucleotides for DNA synthesis, resulting in genomic instability and cell death. Therefore, DHFRs remain important drug targets in antimicrobial and chemotherapeutic treatments. Despite exhaustive investigation of E. coli chromosomal DHFR, controversy persists over the dynamics of regulatory loops (the Met20, the βF-βG, and the βG-βH) and the …

Ligand Binding Studies In R67 Dihydrofolate Reductase And The Evaluation Of The Anion-Quadrupole Interaction At A Quantum Mechanical Level, Michael Robert Jackson

Doctoral Dissertations

Dihydrofolate reductases (DHFR) are important, ubiquitous enzymes catalyzing the hydride transfer from NADPH to dihydrofolate and producing the tetrahydrofolate intermediate that is essential for many metabolic processes, particularly for its role in DNA synthesis. R67 DHFR is a plasmid encoded enzyme that confers resistance to the antibiotic drug trimethoprim. This enzyme is active as a homotetramer. The active site pore possesses 222 symmetry as a result. This symmetry gives rise to a different mechanism by which it binds its ligands. There are potentially four symmetry related binding sites, but various studies have indicated only three possible combinations that include: two …

Expression Of G-Protein Inwardly Rectifying Potassium Channels (Girks) In Lung Cancer Cell Lines, Howard Plummer 3rd, Madhu Dhar, Maria Cekanova Ms, Rndr, Phd, Hildegard Schuller

Faculty Publications and Other Works -- Biochemistry, Cellular and Molecular Biology

BACKGROUND: Previous data from our laboratory has indicated that there is a functional link between the beta-adrenergic receptor signaling pathway and the G-protein inwardly rectifying potassium channel (GIRK1) in human breast cancer cell lines. We wanted to determine if GIRK channels were expressed in lung cancers and if a similar link exists in lung cancer. METHODS: GIRK1-4 expression and levels were determined by reverse transcription polymerase chain reaction (RT-PCR) and real-time PCR. GIRK protein levels were determined by western blots and cell proliferation was determined by a 5-bromo-2'-deoxyuridine (BrdU) assay. RESULTS: GIRK1 mRNA was expressed in three of six small …

Molecular Mechanism Of Caffeine-Induced Expression Of Two Cytochrome P450 Genes, Cyp6a2 And Cyp6a8, In Drosophila Melanogaster, Srividya Bhaskara

Doctoral Dissertations

Cytochrome P450 monooxygenases or CYPs comprise a large family of enzymes that are found in all classes of living organisms, from bacteria to man. These enzymes are involved in the metabolism of many endogenous and xenobiotic (foreign) compounds. In insects, CYPs confer resistance to various insecticides, and resistance-associated overexpression of multiple CYP genes in resistant insects is a common phenomenon. In Drosophila, multiple Cyp genes including Cyp6a2 and Cyp6a8 show higher level of expression in resistant strains than in the susceptible ones. To date, molecular basis of CYP gene overexpression has not been examined in detail. Barbiturate compounds such …

The Oligopeptide Transport Family: Informatic And Experimental Characterization, Amy Marie Wiles

Doctoral Dissertations

All cells require means to obtain nutrients, dispose of waste, and communicate with other cells. One mechanism fulfilling these requirements is active transport, and many permeases in proteomes provide this function. One family of permeases is the Oligopeptide Transport (OPT) family, which is characterized by transporting tetra/penta-peptides across the plasma membrane. In this research, an informatic approach was taken to identify 103 family members, all from plant or fungal species with sequence homology to OPTs of known function.

Eighteen conserved motifs were identified in these homologues. Using several computational algorithms and multiple sequence alignment, 12 transmembrane domains have been identified …

Preferential Flow And Colloids: Their Influence On The Transport Of Phosphorus, Tara Johanna Garrett

Masters Theses

Although strongly adsorbing ions are relatively immobile within soil, ion transport can be enhanced by preferential flow and by adsorption of ions to mobile colloids. The primary objective of this research was to determine the influence of preferential flow paths on the transportation of phosphorus (P) through a soil profile. Secondary objectives were to determine the effect of fertilizer type (inorganic vs. organic) and colloids on the transport of P.

Eight soil monoliths with a diameter of 0.3 m and a length of 0.75 m were collected from the Water Quality field site at the Ames Plantation. Four monoliths were …

Anti-Amyloid Antibodies As Probes Of Amyloid Fibril Structure., Israel Jerome Huff

Masters Theses

Amyloid fibrils have been implicated in numerous human diseases including Alzheimer's disease (AD). The fibrils found in AD are formed by the misfolding and aggregation of the Aβ peptide. Amyloid fibrils are potentially important causative agents, but high-resolution structural information is not yet available. This research analyzes amyloid fibril structure via two different experimental routes. In one approach, ELISA techniques were utilized to study the binding of available anti-amyloid antibodies to single-residue proline and alanine mutant fibrils of Aβ. Binding to some cysteine and modified cysteine mutants was also tested. These data were compared to fibril stability, hydrophobicity change, ThT …

Analysis Of Bub1 Deficiency In Mice, Shawn Michael Leland

Masters Theses

Accurate chromosome segregation is essential for living organisms. Errors in chromosome segregation can lead to the gain or loss of whole chromosomes, a condition known as aneuploidy, which is present in many cancers. One mechanism employed by the cell to monitor chromosome segregation is the spindle checkpoint, a complex signaling pathway which ensures chromosomes are properly aligned on the metaphase plate before the cell proceeds into anaphase. When lagging chromosomes are present, the spindle checkpoint delays the metaphase-to-anaphase transition, which enables the lagging chromosomes to properly orient before the cell proceeds into anaphase. Microtubule attachment to the kinetochore and tension …

Molecular Characterization Of A Isoenzyme Of The Targeting Peptide Degrading Protease, Prep2- Catalysis, Subcellular Localization, Expression And Evolution, S. Bhushan, A. Stahl, S. Nilsson, B. Lefebvre, D. Mcwilliams, S.J. Wright, M. Seki, D.A. Liberles, K. Shinozaki, Barry D. Bruce, M. Boutry, E. Glaser

Faculty Publications and Other Works -- Biochemistry, Cellular and Molecular Biology

We have previously identified a zinc metalloprotease involved in the degradation of mitochondrial and chloroplast targeting peptides, the presequence protease (PreP). In the Arabidopsis thaliana genomic database, there are two genes that correspond to the protease, the zinc metalloprotease (AAL90904) and the putative zinc metalloprotease (AAG13049). We have named the corresponding proteins AtPreP1 and AtPreP2, respectively. AtPreP1 and AtPreP2 show significant differences in their targeting peptides and the proteins are predicted to be localized in different compartments. AtPreP1 was shown to degrade both mitochondrial and chloroplast targeting peptides and to be dual targeted to both organelles using an ambiguous targeting …