David Kysela
National Science Foundation Graduate Research Fellow
david.kysela@yale.edu
Background:
Dave started graduate study at Yale in 2001. He earned his undergraduate
degree from Kenyon College (Gambier, OH) in 1998, with thesis research
on population genetics of stream fish. From 1999 to 2001, Dave worked
as a technician at the Marine Biological Laboratory (Woods Hole,
MA) researching the ecology and phylogenetics of microbes.
Projects
Dave's work focuses on the evolution of bacteriophages, particularly temperate
phages capable of both vertical and horizontal transmission. Our recent research
examines the response of a prophage (latent phage integrated into the host chromosome)
to cell age in the bacterium Caulobacter crescentus. Experiments on selectively aged cells
bear out theoretical predictions that phage should invest more heavily in horizontal
transmission as host cells grow old and senesce. Thus, this caulophage appears to have
evolved a mechanism for adjusting horizontal vs vertical transmission effort based on the
age of the Caulobacter host.
The evolution of gene transfer agents (GTAs) provides another focus of Dave's work.
These elements, morphologically and genetically similar to phages, promote gene
exchange between host cells. Unlike other phages, GTAs cannot productively infect
new cells. The maintenance of GTAs through billions of years of evolutionary history
among certain bacterial lineages suggests some adaptive value of these elemets to
their hosts, apparently through the beneficial effects of gene exchange.
We use comparative molecular evolutionary methods to examine the persistence
of these elements over long evolutionary time frames. Our work has uncovered
peculiar patterns of inheritance, suggesting a more complex evolutionary
history for GTAs than previously described.
A third component of Dave's work explores evolutionary considerations in phage
therapy, i.e. the application of phages in treating virulent bacterial infections.
Unlike other antimicrobials, phage can often counter the emergence of
phage-resistant bacterial through phage mutations that alter host range.
We model the influence of phage mutation rate on phage therapy.
Our theoretical work identifies the potential consequences of various
phage mutation rates in phage therapy applications.
Publications
Edgcomb, V.P., D.T. Kysela, A. Teske, A.D. Gomez and M.L. Sogin.
2002. Benthic eukaryotic diversity in the Guaymas Basin hydrothermal
vent environment. Proc. Natl. Acad. Sci. USA, 99 (11): 7658-7662.
Teske, A., K.U. Hinrichs, V. Edgcomb, A.D. Gomez, D. Kysela, S.P.
Sylva, M.L. Sogin and H.W. Jannasch. 2002. Microbial diversity of
hydrothermal sediments in the Guaymas Basin: Evidence for anaerobic
mathanotrophic communities. Appl. Env. Microbiol., 68 (4): 1994-2007.
Edgcomb, V.P., A.J. Roger, A.G.B. Simpson, D.T. Kysela and M.L.
Sogin. 2001. Evolutionary relationships among "jakobid"
flagellates as indicated by apha- and beta-tubulin phylogenies.
Mol. Biol. Evol., 18 (4): 514-522.
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