Positions

Overview

  • Description of Current Research :
    Either harmful or beneficial bacterium-host interactions can trigger similar host-responses that respectively result in eradication or tolerance of the bacterium. How bacteria can appropriately communicate to a host its benign naturre and how hosts can discriminate between harmful and beneficial bacteria is poorly understood. Using as a model system they symbiosis of the bioluminescent bacterium, Vibrio fischeri, with its animal host, the squid Euprymna scolopes, my research seeks to elucidate how bacteria initiate and maintain long-term associations and how hosts recognize and respond to their desired symbiotic partner.
    Symbiotic colonization is a dynamic process that requires adaptation by both partners. The host is an active participant during initiation of the symbiotic association, collecting bacteria from the surrounding seawater in mucus it secretes from paired epithelial appendages attached to the light organ and concentrating them near the entrance to the organ that eventually cultures the bacterial symbiont. Although various bacterial species associate with the mucus, only the correct symbiont, V. fischeri, is able to successfully enter into symbiosis by overcoming host-imposed checkpoints. Studies indicate that during the specific cooperative association between V. fisheri and its squid host, the baacterial two-component regulator GacA, coordinately regulates the expression of bacterial traits that alllow it to initiate a benign infection of the squid's light-emitting organ. GacA mutants of V. fischeri are less effective at initiating infection and are also impaired at forming tight aggregates during infection. When its light organ is colonized by V. fischeri, the squid host adapts to this association and, in response to bacterial signals, undergoes a program of changes that leads to the normal develoment of the light organ. One of the most striking changes is apoptosis in and regression of the appendages over a four-day period. GacA mutants that successfully colonize squid light organs do not trigger normal apoptosis during regression of these appendages, implying that delivery of bacterial signals to the squid host is GacA-controlled. Furthermore, GacA mutants fail to trigger cessation of mucus shedding, a colonization response that normally limits further bacterial interaction.

    My current research focus will use the GacA mutant as a basis for identifying and characterization colonization traits. These studies will provide insight into bacteria-derived signals that allow hosts to respond appropriately to beneficial organisms, thus allowing association, without compromising the ability of immune responses to protect the host from pathogenic infection. We are currently utilizing a recently generated DNA microarray of the entire genome of V. fischeri, and will also combine this genomic approach with random mutagenesis screens to discover previously uncharacterized genes and traits that contribute to animal tissue colonization.
  • Publications

    Academic Article

    Year Title
    2017 Parallel evolution of two clades of a major Atlantic endemic Vibrio parahaemolyticus pathogen lineage by independent acquisition of related pathogenicity islands.Applied and Environmental Microbiology.  83:e01168-e01117. 2017
    2017 Host-selected mutations converging on a global regulator drive an adaptive leap towards symbiosis in bacteria.eLife.  6:e24414. 2017
    2017 Sequence Type 631 Vibrio parahaemolyticus, an Emerging Foodborne Pathogen in North America.Journal of Clinical Microbiology.  55:645-648. 2017
    2016 Environmental Conditions Associated with Elevated Vibrio parahaemolyticus Concentrations in Great Bay Estuary, New Hampshire.PLoS ONE.  11:e0155018. 2016
    2015 Spontaneous phenotypic suppression of GacA-defective Vibrio fischeri is achieved via mutation of csrA and ihfA.BMC Microbiology.  15:180. 2015
    2015 Use of Whole-Genome Phylogeny and Comparisons for Development of a Multiplex PCR Assay To Identify Sequence Type 36 Vibrio parahaemolyticus.Journal of Clinical Microbiology.  53:1864-1872. 2015
    2015 Genetic characterization of clinical and environmental Vibrio parahaemolyticus from the Northeast USA reveals emerging resident and non-indigenous pathogen lineages.Frontiers in Microbiology.  6:272. 2015
    2013 Characterization of a Vibrio fischeri Aminopeptidase and Evidence for Its Influence on an Early Stage of Squid Colonization (vol 194, pg 3995, 2012)Journal of Bacteriology.  195:3298-3298. 2013
    2013 Bacterial bioluminescence regulates expression of a host cryptochrome gene in the squid-Vibrio symbiosis.mBio.  4:e00167-e00113. 2013
    2012 Characterization of a Vibrio fischeri aminopeptidase and evidence for its influence on an early stage of squid colonization.Journal of Bacteriology.  194:3995-4002. 2012
    2012 Influence of seasonality on the genetic diversity of Vibrio parahaemolyticus in New Hampshire shellfish waters as determined by multilocus sequence analysis.Applied and Environmental Microbiology.  78:3778-3782. 2012
    2011 Ecology and genetic structure of a northern temperate Vibrio cholerae population related to toxigenic isolates.Applied and Environmental Microbiology.  77:7568-7575. 2011
    2010 Comparison of the pathogenic potentials of environmental and clinical vibrio parahaemolyticus strains indicates a role for temperature regulation in virulence.Applied and Environmental Microbiology.  76:7459-7465. 2010
    2010 Breaking the language barrier: experimental evolution of non-native Vibrio fischeri in squid tailors luminescence to the hostSymbiosis.  51:85-96. 2010
    2009 Stress tolerance and environmental fitness of Pseudomonas fluorescens A506, which has a mutation in RpoS.Phytopathology.  99:679-688. 2009
    2007 The GacA global regulator of Vibrio fischeri is required for normal host tissue responses that limit subsequent bacterial colonization.Cellular Microbiology.  9:766-778. 2007
    2003 GacA regulates symbiotic colonization traits of Vibrio fischeri and facilitates a beneficial association with an animal host.Journal of Bacteriology.  185:7202-7212. 2003
    2003 Translation start sequences affect the efficiency of silencing of Agrobacterium tumefaciens T-DNA oncogenes.Plant Physiology.  133:966-977. 2003
    2003 Repression of phenazine antibiotic production in Pseudomonas aureofaciens strain 30-84 by RpeAJournal of Bacteriology.  185:3718-3725. 2003
    2003 Repression of phenazine antibiotic production in Pseudomonas aureofaciens strain 30-84 by RpeA.Journal of Bacteriology.  185:3718-3725. 2003
    2000 Lon protease influences antibiotic production and UV tolerance of Pseudomonas fluorescens Pf-5.Applied and Environmental Microbiology.  66:2718-2725. 2000
    1998 The two-component regulators GacS and GacA influence accumulation of the stationary-phase sigma factor sigmaS and the stress response in Pseudomonas fluorescens Pf-5.Journal of Bacteriology.  180:6635-6641. 1998

    Conference Proceeding

    Year Title
    2015 GENETIC CHARACTERIZATION OF CLINICAL AND ENVIRONMENTAL VIBRIO PARAHAEMOLYTICUS FROM THE NORTHEASTERN US REVEALS EMERGING RESIDENT AND INVASIVE PATHOGEN LINEAGESJournal of Shellfish Research. 726-727. 2015
    2015 LONG-TERM TRENDS OF PATHOGENIC VIBRIO SPP. POPULATIONS IN NEW HAMPSHIRE OYSTERSJournal of Shellfish Research. 711-711. 2015

    Patents And Disclosures

    Year Title
    Methods and compositions for identifying pathogenic Vibrio parahaemolyticus

    Teaching Activities

  • Contemp Top Molec/Cell/Biomed Taught course 2019
  • Contemp Top Molec/Cell/Biomed Taught course 2018
  • Contemp Top Molec/Cell/Biomed Taught course 2018
  • Genetics Prokaryotic Microbes Taught course 2018
  • Rsrch Exp/MCBS Taught course 2018
  • Seminar Taught course 2018
  • Contemp Top Molec/Cell/Biomed Taught course 2017
  • Seminar Taught course 2017
  • Doctoral Research Taught course 2017
  • Genetics Prokaryotic Microbes Taught course 2017
  • Seminar Taught course 2017
  • Undergrad Teaching Experience Taught course 2017
  • Doctoral Research Taught course 2016
  • Rsrch Exp/MCBS Taught course 2016
  • Seminar Taught course 2016
  • Doctoral Research Taught course 2016
  • Genetics Prokaryotic Microbes Taught course 2016
  • Top/Host Microbe Interaction Taught course 2016
  • Doctoral Research Taught course 2015
  • General Microbiology Taught course 2015
  • Top/Host Microbe Interaction Taught course 2015
  • Undergrad Teaching Experience Taught course 2015
  • Doctoral Research Taught course 2015
  • Genetics Prokaryotic Microbes Taught course 2015
  • Top/Host Microbe Interaction Taught course 2015
  • Undergrad Teaching Experience Taught course 2015
  • Adv Rsrch Exp/MCBS Taught course 2014
  • Doctoral Research Taught course 2014
  • General Microbiology Taught course 2014
  • Top/Host Microbe Interaction Taught course 2014
  • Undergrad Teaching Experience Taught course 2014
  • Genetics Prokaryotic Microbes Taught course 2014
  • Top/Host Microbe Interaction Taught course 2014
  • Undergrad Teaching Experience Taught course 2014
  • Education And Training

  • B.A. General Biology, University of California - San Diego
  • Ph.D. Molecular and Cellular Biology, Oregon State University
  • Full Name

  • Cheryl Whistler