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Articles 1 - 3 of 3
Full-Text Articles in Cell Biology
Characterization Of The Role That Alternative Ribonucleotide Reductases Play In Restoring Replication In The Presence Of Hydroxyurea In Escherichia Coli, Michael Sadek
PSU McNair Scholars Online Journal
DNA replication is essential for cells to grow and divide. Ribonucleotide reductase is an essential enzyme that is responsible for the formation of deoxyribonucleotides that are used in DNA synthesis during replication. Hydroxyurea is a chemotherapeutic agent that is thought to work by specifically inhibiting the ribonuceotide reductase to prevent replication. However, recent studies in E. coli have shown that following an initial period of inhibition, DNA synthesis then recovers in the presence of hydroxyurea, suggesting that the mode of death and cellular response to hydroxyurea is more complex than originally proposed. The E.coli genome encodes three ribonucleotide reductases that …
Reverse Gyrase Is Not Necessary For Survival Of Hyperthermophilic Archaeon Pyrococcus Furiosus, Farshid Taghizadeh, Michael S. Bartlett
Reverse Gyrase Is Not Necessary For Survival Of Hyperthermophilic Archaeon Pyrococcus Furiosus, Farshid Taghizadeh, Michael S. Bartlett
Student Research Symposium
Reverse gyrase is the only known topoisomerase enzyme with positive supercoiling activity on covalently-closed DNA. This positive supercoiling is required to prevent DNA from denaturation at high temperatures. The gene that codes for this protein is present in all hyperthermophiles and absent from all mesophilic and thermophilic genomes, suggesting that this enzyme is the only hyperthermophile-specific protein. To investigate if this protein is vital for the cells, we knocked out its gene from the genome of living organism Pyrococcus furiosus. Pyrococcus furiosus is a hyperthermophilic archaeon that grows between 70°C to 103°C with an optimum growth temperature of 100°C. …
A Coxiella-Like Endosymbiont Is A Potential Vitamin Source For The Lone Star Tick, Todd A. Smith, Timothy Driscoll, Joseph J. Gillespie, Rahul Raghavan
A Coxiella-Like Endosymbiont Is A Potential Vitamin Source For The Lone Star Tick, Todd A. Smith, Timothy Driscoll, Joseph J. Gillespie, Rahul Raghavan
Biology Faculty Publications and Presentations
Amblyomma americanum (Lone star tick) is an important disease vector in the United States. It transmits several human pathogens, including the agents of human monocytic ehrlichiosis, tularemia, and southern tick-associated rash illness. Blood-feeding insects (Class Insecta) depend on bacterial endosymbionts to provide vitamins and cofactors that are scarce in blood. It is unclear how this deficiency is compensated in ticks (Class Arachnida) that feed exclusively on mammalian blood. A bacterium related to Coxiella burnetii, the agent of human Q fever, has been observed previously within cells of A. americanum. Eliminating this bacterium (CLEAA, Coxiella-like endosymbiont of A. americanum) with antibiotics …