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Full-Text Articles in Molecular Biology

All The Right Noises: Causes And Consequences Of Stochastic Trimethylamine Oxide Reductase Expression In Escherichia Coli, Jeffrey Carey Jan 2018

All The Right Noises: Causes And Consequences Of Stochastic Trimethylamine Oxide Reductase Expression In Escherichia Coli, Jeffrey Carey

Publicly Accessible Penn Dissertations

Microbial populations can maximize fitness in dynamic environments through bet hedging, a process wherein a subpopulation assumes a phenotype not optimally adapted to the present environment but well adapted to an environment likely to be encountered. Here we show that oxygen induces fluctuating expression of the trimethylamine oxide (TMAO) respiratory system of Escherichia coli, diversifying the cell population and enabling a bet-hedging strategy that permits growth following oxygen loss. This regulation by oxygen affects the variance in gene expression but leaves the mean unchanged. We show that the oxygen-sensitive transcription factor IscR is the key regulator of variability. Oxygen causes ...


Investigation Of A Mycobacteriophage Transcription Repressor, Kathryn Orban May 2016

Investigation Of A Mycobacteriophage Transcription Repressor, Kathryn Orban

Honors Thesis

Mycobacteriophage HelDan is a lysogenic, or temperate, phage (virus) of the bacterium Mycobacterium smegmatis, which is a fast-growing, close relative of Mycobacterium tuberculosis, the causative agent of tuberculosis. The phage replication cycle is dependent on time-coordinated gene expression events. In order to study the regulation of gene expression during phage replication, HelDan protein gp73, a putative transcriptional repressor, was studied. Characterization of gp73 structure and function, such as DNA binding activity and affinity, was done using both bioinformatics and biochemical analyses. To this end, the gene encoding gp73 was cloned and the ability of the recombinant gp73 protein to bind ...


Detection And Destruction Of Escherichia Coli Bacteria And Bacteriophage Using Biofunctionalized Nanoshells, Joseph E. Van Buren Jan 2007

Detection And Destruction Of Escherichia Coli Bacteria And Bacteriophage Using Biofunctionalized Nanoshells, Joseph E. Van Buren

Browse all Theses and Dissertations

The ability to detect chemical and biological agents is arguably one of the highest priority technical challenges today. The capability to obtain specific information at and near single-molecule resolution is the ultimate goal in chemical and biological agent detection. Metallic nanostructures, nanoshells and nanorods in particular, are attractive substrates because of their plasmonic properties. Combining the specificity of biomolecular recognition with these nanostructures might lead to increased sensitivity and selectivity. Localization of biological recognition motifs to the surface of these nanostructures could provide a mechanism for highly specific and directed energy transfer when bound to its target. This study utilizes ...