cAMP

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Aggregating cells
cAMP spiral wave
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Various diatoms, 50-100 microns in diameter
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Another slime mold, Polysphondylium
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Conus shell patterns
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E. coli colonies on a 10 cm Petri dish
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Patterns that span an enormous length scale
0.1 mm 1 mm 10 mm 100 mm 1000 mm
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Alan Turing
Mathematical models are the lie that helps us
see the truth
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Hydra
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Anaboena, a blue green alga
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Human Computers Spatial patterning and lateral
inhibition
Take a coin and flip it. If its Heads, stand
up. Tails, remain seated
If you are standing, you are expressing A in high
quantities. If you are sitting, you are not.
Those of you making protein A (standing) are also
emitting another substance, I which inhibits your
neighboring cells from expressing A.
When I say go - if your two neighbors are
standing. You must sit down - if your two
neighbors are sitting. You must stand up - if
one neighbor is standing and the other sitting
You choose local rules lead to the
emergence of a global pattern!
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• Giraffes spots activator inhibitor model with DI
  just barely greater than DA.
• Crescent shaped leopards spots
  activator-inhibitor scheme involving two
  interacting patterning mechanisms.

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James Murray (1970s)
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In a simplified 2-D approximation of the zebra
leg, an activator-inhibitor system that generates
stripes in the body and bands in the leg also
produces the chevron pattern at their junction as
seen in all zebras.
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Equus grvyi Equus burchelli
Prepatterning 3 weeks 5 weeks
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