Activation/Inhibition Models (for head segmentation)

JMohler jmohler at SMTPLink.Barnard.Columbia.edu
Fri Jan 28 13:30:47 EST 1994


John:

     I've been meaning to get in touch for a while.  I was wondering if you had
a program to model a Turing process to generate stripes.  I hoping such would
be a simple, naive model to explain how the cephalic segments (preanntennal,
antennal and intercalary) are generated.
     Basically, the phenomenology is that both wg and hh are initially expressed
in broad overlapping domains in this region (with the wg doamin slightly anter-
ior to the hh domain).  These domains gradually divvy up into three striped
domains (actually for wg, two stripes and a "head blob").  It seems to me that
the mutual interaction between hh and wg, coupled with the initial overlapping
distributions, could generate such stripes.
     There is some  consistent circumstantial evidence.  For example, ems and
otd mutants remove the hh and wg domains (respectively) early; the remaining
wg or hh domain then remains as a single domain.  Also, tll mutants cause the
initial hh domain to extend anteriorly past the edge of the wg domain; then
wg domain forms only two stripes without the "head blob".
     I'd like to see if one could generate a simple and dirty, mutual
activation/inhibition model to account for this.  IF you can help me at
all, I'd appreciate hearing from you.

Jym Mohler



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