Mathematical Biology Seminar
Arjun Raj, Massachusetts Institute of Technology
Wednesday April 23, 2008
3:05pm in LCB 225
"Stochastic gene expression and cell fate--or, why are identical twins so identical?"
Abstract:
Much recent work has shown that the process of gene expression is
remarkably imprecise, leading to significant cell-to-cell variability
in the numbers of mRNAs and proteins even in genetically identical
populations. This raises a couple of questions: can cells exploit
this variability for their own benefit? Conversely, do cells reduce
the impact of variability in order to produce reliable outcomes in
other contexts? We explored the first question by studying the random
transitions of the soil bacterium B. subtilis to the "competent"
state, tracing the origin of this transition to stochastic
fluctuations in the expression of a regulatory gene. However, while
unicellular organisms require stochastic variability to exist in
multiple states simultaneously, one might expect multicellular
organisms (with developmentally controlled cell types) to have
mechanisms to tolerate this variability. To see if and how organisms
do this, we are studying the gut formation pathway in embryonic
development in C. elegans. Preliminary results show that the normal
gut development pathway is remarkably robust, but this robustness can
be destroyed by mutations that result in wildly varying embryonic
fates. We are trying to link this variability to stochastic effects
in the expression of developmental regulators caused by these
mutations. We also present some results showing the randomness
inherent to gene expression in mammalian cells.
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Mathematical Biology Program
Department of Mathematics
University of Utah
155 South 1400 East Room 233
Salt Lake City, UT 84112
rasmusse@math.utah.edu
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