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SUMMARY:Molecular arms race between host and parasite leads to evolution o
 f robustness against gene loss in signaling networks - Dr Orkun Soyer\, Co
 SBi
DTSTART:20080326T140000Z
DTEND:20080326T150000Z
UID:TALK10651@talks.cam.ac.uk
CONTACT:Dr Fabien Petitcolas
DESCRIPTION:*Abstract*: In several organisms\, gene deletion studies sugge
 st a large fraction of genes to be dispensable. While part of this observa
 tion stems from genes that are required under environments not assayed in 
 the lab\, a still appreciable number of genes can be lost with seemingly n
 o phenotypic effect. Such robustness can result from duplicate genes that 
 maintain a functional overlap despite molecular divergence (redundancy)\, 
 or from system architecture. The emergence and maintenance of these two me
 chanisms poses significant challenges. In particular\, no explanation curr
 ently exists for how evolution can lead to specific network architectures 
 that are robust against deletion of parts. Also\, the selective pressure f
 or redundancy is expected to be weak\, resulting in its evolution only und
 er specific conditions. In this talk\, I will demonstrate that antagonisti
 c host-parasite interactions can lead to the evolution of robustness again
 st gene loss in signaling networks. Using a mathematical model of host net
 works and simulating their co-evolution with parasites that can interfere 
 with proteins in such networks\, I will show how such networks can evolve 
 both redundancy and specific architectures allowing them to maintain their
  response despite removal of proteins. Contrary to the intuition\, increas
 ed parasite virulence hampers the ability of the host to evolve robustness
  by limiting the generation of population level diversity. However\, when 
 robustness emerges under high virulence it tends to be stronger and more l
 ikely to be mediated through system architecture rather than redundancy. T
 hese findings indicate that the arms race between parasites and their host
 s is a significant ecological factor shaping biological network properties
 .\n\n*Biography*: Orkun S. Soyer graduated from Bogazici University\, Ista
 nbul in 2000. He received his PhD from University of Michigan\, Ann Arbor 
 for his work on models of protein evolution. During his post - doctoral st
 udies at ETH\, Zürich\, he developed toy models of biological signaling n
 etworks and applied these to the study of pathway evolution and dynamics.\
 n\nHis research is driven by the fact that biology is the result of evolut
 ion and focuses to reach an understanding of how evolutionary processes an
 d selective pressures shape the structural and dynamical features of biolo
 gical systems. This line of research relies heavily on theoretical models 
 that are simplified versions of the reality and that can still capture the
  essential features and complexity of biological systems. The resulting un
 derstanding from such theoretical models is than used to generate testable
  hypotheses to fuel and direct experimental research.
LOCATION:Microsoft Research Ltd\, 7 J J Thomson Avenue (Off Madingley Road
 )\, Cambridge
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