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Full-Text Articles in Life Sciences
Mechanism Of Mitogenic Action Of Aluminum Ion On Bone Cells : Potential Involvement Of The Insulin-Like Growth Factor Regulatory System, Aera Yoo
Loma Linda University Electronic Theses, Dissertations & Projects
Micromolar concentrations of aluminum ion (oxidation state of 3 +) consistently stimulated [3H]thymidine incorporation into cell DNA and increased cellular alkaline phosphatase activity (an osteoblastic differentiation marker) in osteoblast-like cells of chicken and human origin. Although biphasic, dose-dependent stimulations were highly reproducible, the maximal stimulatory dose varied among different experiments. Mitogenic doses of aluminum ion also stimulated collagen synthesis in cultured human osteosarcoma TE85 cells. In addition, the same mitogenic concentrations of aluminum ion enhanced the 1,25 dihydroxy vitamin D3-dependent stimulation of osteocalcin secretion. Together, these findings indicate that aluminum at micromolar concentrations, stimulates the proliferation, differentiation, and activity of …
The Invariant Arginine In Motif 2 Of Escherichia Coli Alanyl-Trna Synthetase : Is Important For Catalysis But Not For Substrate Binding, Ying Lu
Loma Linda University Electronic Theses, Dissertations & Projects
Structural motifs 2 and 3, located in the active site of class II aminoacyl-tRNA synthetases, each contain an invariant arginine thought to participate in interactions with ATP. For Escherichia coli alanyl-tRNA synthetase (AlaRS), sequence comparisons indicate that Arg69 should be aligned with the invariant arginine in motif 2 of other class II synthetases. Site-directed random mutagenesis has been employed to generate a set of proteins containing amino acid substitutions in a portion of motif 2 of AlaRS. In this set, only mutations at position 69 caused the enzyme to lose ability to complement growth of an alaS deletion strain, …
Signal Transduction In Bacterial Chemotaxis, Edward Heath Rowsell
Signal Transduction In Bacterial Chemotaxis, Edward Heath Rowsell
Loma Linda University Electronic Theses, Dissertations & Projects
This study investigated the site of ATP utilization in the signal transduction pathway of bacterial chemotaxis and localized the point of convergence of a methylation-independent system of chemotaxis with the methylation-dependent system. The identity of the signal originating from the phosphotransferase system was investigated by substituting the fructose-inducible HPr-like protein FPr for HPr in transport and chemotaxis. In addition, a novel chemoattractant, glycerol, was identified for Salmonella typhimurium. Histidine-auxotrophic S. typhimurium strains ST23 (hisF) and ST171 (hisF cheB) were depleted for ATP. The times required for the bacteria to adapt to a step increase in serine, …