| Date and Time: |
2007-10-09 16:00:00 - 17:00:00 |
| Speaker: |
Thomas Gregor
JSPS, PhD fellow, the University of Tokyo, Graduate School of Arts and Sciences, Department of Basic Science |
| Title: |
Physical constraints and limits to precision in early embryonic development |
| : | During embryonic development, information about spatial location is
represented by the concentration of various protein gradients. The
reproducibility and precision of biological pattern formation is thus
limited by the accuracy with which these concentration profiles can be
established and "read out" by their target pathways.
In this talk, I present a biophysical analysis of one of the most
studied protein gradients in the fruit fly embryo, the Drosophila Bicoid
morphogen gradient.
First, using two-photon microscopy and other biophysical instrumentation
techniques, both the full spatiotemporal dynamics that lead to gradient
establishment and the gradient's scaling with embryo size in
closely-related species were measured and used to test a simple physical
model.
Second, four functionally different measurements of precision for the
protein gradient were considered; through a combination of different
experiments, I showed that all of these quantities are ~10%, which is
close to the physical limit set by random arrival of individual
molecules at their targets.
The agreement among the different measures of accuracy indicates that
the system in fact relies on precise control of absolute concentrations,
and responds reliably to small changes in these concentrations, down to
the limits set by basic physical principles. This contradicts previous
research, which was driven by the assumption that sloppy input signals
and noisy readout mechanisms govern embryonic development. |
