CPM Seminar
Stochastic gene expression in single cells
Peter Swain
Centre for Nonlinear Dynamics
McGill
Generation of phenotypic variability in clonal populations of cells is
essential for many biological processes. Such heterogeneity is conjectured to
arise from stochasticity, or noise, in gene expression. We show that noise
can be decomposed into an intrinsic piece, particular to a given gene, and an
extrinsic term, common to all genes in a cell, but variable from one cell to
another. Using specially constructed strains in Escherichia coli, we are able
to discriminate between, and measure, both types of noise. We demonstrate
that intrinsic noise indeed exists in vivo and accounts for a substantial
portion of cell-cell variation. An analytical description of gene expression
is also presented, which contains all the major biochemical steps in
transcription and translation. As transcription rate is varied, this model
confirms experimental findings that the amplitudes of both noise components
vary over a wide range. These results reveal how low intracellular copy
numbers can fundamentally limit the precision of gene expression.
Thursday, October 9th 2003, 15:30
Ernest Rutherford Physics Building, R.E. Bell Seminar Room (room 103)
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