Nicola Davies
Nicola on the bridge at Avignon.
EDUCATION:
B.Sc.H. in Biochemistry (2001) :Queen's University in Kingston, Ontario.
Ph.D. (Molecular Genetics and Microbiology), University of Texas at Austin, 2006
RESEARCH INTERESTS:
TonB-dependent iron uptake systems are virulence factors in many bacteria. In Shigella dysenteriae the role of TonB in virulence has been studied using a tonB mutant, SDU380. The S. dysenteriae tonB mutant was found to be deficient in heme and enterobactin transport and demonstrated an inability to spread from cell to cell. To compare the role of TonB in Shigella flexneri to that in S. dysenteriae, a S. flexneri tonB mutant, NDS100, was created by insertional inactivation of the tonB gene. The S. flexneri tonB mutant, NDS100, was unable to grow using aerobactin or ferrichrome as the sole iron source, indicating a defect in siderophone transport. NDS100 also showed increased sensitivity to the iron chelator ethylenediamine di-(o-hydroxyphenylacetate) in vitro in comparison to its parent strain. Growth of the tonB mutant in the intracellular environment was examined using tissue culture assays. NDS100 was able to invade cultured cells and, unlike SDU380, formed plaques in confluent monolayers of Henle cells, indicating that it is capable of intracellular growth and intercellular spread. While the S. flexneri tonB mutant is equally or more sensitive than the S. dysenteriae tonB mutant to low iron conditions in vitro, it retains its ability to form plaques, indicating that TonB is not required for intracellular growth and cell-to-cell spread in S. flexneri.
EMAIL ADDRESS: nicola@austin.rr.com
