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| School of Medicine • University of Washington • Box 357735 • 1705 NE Pacific St • Seattle WA 98195 | ||||||
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About Josephine (Josie) Chandler Dr. Chandler is a postdoctoral fellow in Dr. Greenberg’s laboratory. She received a B.S. in microbiology from the University of Iowa and a Ph.D. in Microbiology from the University of Minnesota. Her Ph.D. work was with Dr. Gary M. Dunny and focused on cell-cell signaling in the opportunistic pathogen Enterococcus faecalis. During her Ph.D., Dr. Chandler was a Graduate Fellow and an NIH Minnesota Craniofacial Training Program Fellow, and received the Bacaner Research Award and the student-voted Golden Pipetman Award. Dr. Chandler began working with Dr. Greenberg in Seattle in 2006 just after his move from Iowa, where she joined forces with all the Hawkeyes that moved with him. Dr. Chandler is currently funded by an NIH individual NRSA fellowship to study quorum sensing in the closely related organisms Burkholderia mallei and Burkholderia thailandensis, and is interested in understanding how cooperative behavior evolves in bacteria.
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Research Quorum sensing allows individuals in a group to monitor population density and coordinate behavior in a cell density-dependent manner. Quorum sensing in proteobacteria is mediated by acyl-homoserine lactone (acyl-HSL) signal molecules. Acyl-HSLs accumulate as the bacterial population increases in density. At a critical concentration, acyl-HSLs specifically cause the induction of quorum sensing-regulated genes. Quorum sensing contributes to virulence and symbiosis in a range of bacteria that have known host-associated lifestyles. Many bacteria with acyl-HSL quorum sensing systems also have a free-living (non-host associated) lifestyle, but the importance of quorum sensing in these organisms has not been well studied. I am interested in understanding how individual bacterial cells benefit from quorum sensing in different environments. Quorum sensing is a group behavior but may be disadvantageous to individuals because it can be metabolically expensive. Thus for quorum sensing to be maintained by individuals, there must be selection for cooperating individuals that promotes their survival over non-cooperating “cheaters” in a population of bacteria. As bacteria evolve in their natural habitats, it is unclear what selective pressures might provide an advantage to cooperating individuals with quorum sensing. To understand the selective pressures that drive evolution of cooperation and quorum sensing in different environments, we are studying quorum sensing in two closely related organisms that have extremely divergent lifestyles; the poorly virulent soil saprophyte Burkholderia thailandensis, and the obligate animal pathogen Burkholderia mallei. Our group has completed a basic characterization of the quorum sensing systems of these two organisms and identified two quorum sensing controlled phenotypes in B. thailandensis, which are clumping and antibiotic production. I am currently developing model systems that can be used to understand how the quorum sensing-controlled phenotypes of B. thailandensis may confer a selective advantage to cooperating individuals in the mixed microbial communities of soil.
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Josephine (Josie) Chandler, Ph.D.
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