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Several members of the family Enterobacteriaceae were examined for differences in extreme acid survival strategies. A surprising degree of variety was found between three related genera. The minimum growth pH of Salmonella typhimurium was shown to be significantly lower (pH 4.0) than that of either Escherichia coli (pH 4.4) or Shigella flexneri (pH 4.8),(More)
The acid tolerance response (ATR) of log-phase Salmonella typhimurium is induced by acid exposures below pH 4.5 and will protect cells against more extreme acid. Two systems are evident: a transiently induced system dependent on the iron regulator Fur that provides a moderate degree of acid tolerance and a more effective sustained ATR that requires the(More)
Acid is an important environmental condition encountered by Salmonella typhimurium during its pathogenesis. Our studies have shown that the organism can actively adapt to survive potentially lethal acid exposures by way of at least three possibly overlapping systems. The first is a two-stage system induced in response to low pH by logarithmic-phase cells(More)
The pnp gene encodes polynucleotide phosphorylase, an exoribonuclease involved in RNA processing and degradation. A mutation in the pnp gene was previously identified by our group in a signature-tagged mutagenesis screen designed to search for Salmonella enterica serovar Typhimurium genes required for survival in an ex vivo swine stomach content assay. In(More)
<lb>CELL LINEAGE CHOICE DURING DIFFERENTIATION OF TROPHOBLAST STEM<lb>CELLS (TSC) IS DEPENDENT ON OXYGEN LEVELS, AND MEDIATED BY STRESS<lb>ENZYME PATHWAYS AND MITOCHONDRIAL FUNCTION<lb>by<lb>SICHANG ZHOU<lb>December 2011<lb>Advisor: Dr. Daniel A. Rappolee<lb>Major: Physiology, Concentration in Reproductive Sciences<lb>Degree: Doctor of Philosophy<lb>In(More)
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