Chalmers Conferences, 9th European Conference on Mathematical and Theoretical Biology

How to Understand Morphogen Gradients Development during Biological Development
Anatoly B. Kolomeisky

Last modified: 2014-06-09


Concentration profiles of signaling molecules, also known as morphogen gradients, play a critical role
in the development of multi-cellular organisms by determining polarity and spatial patterning that leads
to further tissue differentiation. Significant advances in studying morphogen gradients have been achieved
recently when the formation of signaling molecules profiles has been visualized with high temporal
and spatial resolution. A widely used approach to explain the establishment of concentration gradients assumes
that signaling molecules are produced locally, then spread via a free diffusion and degraded uniformly.
However, recent experiments have also produced controversial observations concerning the feasibility
of this theoretical description. In addition, it has been shown that time to establish the morphogen gradient
yield surprising linear scaling as a function of length, not expected for the systems with unbiased diffusion processes.
Current theoretical views utilize continuum models that produce unphysical behavior at limiting cases.
We propose here a theoretical approach based on discrete-state stochastic analysis that provides
a possible microscopic mechanism of these complex phenomena. It is argued that relaxation times are mostly determined
by first-passage times and the degradation effectively accelerates diffusion of signaling particles by removing slow
moving molecules. Thus the degradation works as an effective potential that drives signaling molecules away from the source.
Our theoretical analysis indicates that spatial and temporal features of degradation
efficiently control the establishment of signaling molecules profiles.