Karen L. Visick, Ph.D.
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Intimate, long-term
associations (symbioses) with bacteria are fundamental to most, if not
all, animals in nature. To understand how such associations are formed
and maintained, we study Vibrio fischeri, a bioluminescent marine
bacterium that colonizes a specific tissue of Euprymna scolopes,
a small Hawaiian squid. These organisms are useful as a model for
symbiosis because their association is highly specific and can be easily
manipulated in the laboratory. In addition, genetic engineering has
already been applied with success to the bacterial partner.
Upon hatching from an egg, the juvenile E. scolopes squid is
symbiont-free and must acquire V. fischeri cells from the
surrounding seawater. The V. fischeri cells enter a special organ
and rapidly multiply to a high cell density. Within hours, both the
bacteria and the squid respond to the presence of the other by
undergoing morphologic and developmental alterations. Our goal is to determine how Vibrio fischeri cells initiate
this symbiotic interaction with the squid and persist in that
environment. We have isolated bacterial mutants defective in
colonization of E. scolopes juveniles, and are currently
in the process of identifying the genes disrupted in these mutants and
determining their role in establishing the symbiosis. In the future, we
hope to investigate the regulatory networks that control
symbiosis-specific genes and identify the environmental cues that signal
to Vibrio fischeri that it is in this special niche. This work
will increase our understanding of the communication that must occur
between V. fischeri and its squid host as they establish a
symbiotic association. Visick KL. 2009. An intricate network of regulators controls biofilm formation and colonization by Vibrio fischeri. Mol Microbiol. 74(4):782-9. Epub 2009 Oct 8.PMID: 19818022. Yildiz FH, Visick KL . 2009. Vibrio biofilms: so much the same yet so different. Trends Microbiol. 17(3):109-18. Epub 2009 Feb 21. Review.PMID: 19231189. Mandel MJ, Wollenberg MS, Stabb EV, Visick KL, Ruby EG. 2009. A single regulatory gene is sufficient to alter bacterial host range. Nature. 12;458(7235):215-8. Epub 2009 Feb 1.PMID: 19182778. Darnell CL, Hussa EA, Visick KL.2008. The putative hybrid sensor kinase SypF coordinates biofilm formation in
Vibrio fischeri by acting upstream of two response regulators, SypG and VpsR. J Bacteriol. 190(14):4941-50. Wolfe, A. J., and K. L. Visick. 2008. Get the message out: cyclic-di-GMP regulates multiple levels of flagellum-based motility. J. Bacteriol.
I190:463-475. Hussa, E. A., T. M. O'Shea, C. L. Darnell, E. G. Ruby, and
K. L. Visick. 2007. Two-component response regulators of
Vibrio fischeri: their identification, mutagenesis and
characterization. J. Bacteriol. 189:5825-5838. Bose, J. L., U. Kim, W. Bartkowski, R. P. Gunsalus, A. M. Overley, N. L. Lyell,
K. L. Visick, and E. V. Stabb. 2007. Bioluminescence in
Vibrio fischeri is controlled by the redox-responsive regulator ArcA. Mol.
Microbiol. 65:538-553. Visick, K. L., T. M. O'Shea, A. Klein, K. Geszvain, and A. J. Wolfe. 2007.
The sugar phosphotransferase system of
Vibrio fischeri inhibits both motility and bioluminescence. J. Bacteriol. 189:2571-2574. Yip, E. S., K. Geszvain, C. R. DeLoney-Marino, and
K. L. Visick. 2006. The
symbiosis regulator RscS controls the syp gene locus, biofilm
formation and symbiotic aggregation by Vibrio fischeri. Mol.
Microbiol. 62:1586-1600. O'Shea, T. M., A. H. Klein, K. Geszvain, A. J.
Wolfe, and K. L. Visick. 2006. Diguanylate
cyclases control magnesium-dependent motility of Vibrio fischeri.
J. Bacteriol. 188:8196-8205. Visick, K. L.,
and E. G. Ruby. 2006. Vibrio
fischeri and its host: it takes two to
tango. Curr. Op. Microbiol. 9:632-638. Geszvain, K., and K. L. Visick. 2006. Roles
of bacterial regulators in the symbiosis between Vibrio fischeri and
Euprymna scolopes, p. 277-290. In J. Overmann (ed.),
Prog Mol Subcell Biol, vol. 41. Springer-Verlag, Germany. Yip, E. S., B. T. Grublesky, E. A. Hussa, and K.
L. Visick. (2005). A
novel, conserved cluster of genes promotes symbiotic colonization and s
54-dependent biofilm formation by Vibrio fischeri. Mol.
Microbiol. 57:1485-1498. O'Shea, T. M., C. R. DeLoney-Marino, S. Shibata,
S.-I. Aizawa, A. J. Wolfe, and K. L. Visick. (2005). Magnesium
promotes flagellation of Vibrio fischeri. J. Bacteriol.
187:2058-2065. Ruby,
E. G., M. Urbanowski, J. Campbell, A. Dunn, M. Faini, R. Gunsalus, P.
Lostroh, C. Lupp, J. McCann, D. Millikan, A. Schaefer, E. Stabb, A.
Stevens, K. Visick, C. Whistler, and E. P. Greenberg. (2005). Complete
genome sequence of Vibrio fischeri: A symbiotic bacterium with
pathogenic congeners. PNAS 102:3004-3009. Search PubMed for a complete listing of Karen Visick's publications
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