New research has prompted a resurgence of interest in the patterning mechanisms Alan Turing proposed 60 years ago
A Turing mechanism alone cannot account for scaling in nature’s patterns. Chicken eggs are a good example of scaling, in that they can be large, small or anything in between, but regardless of the size of a fertilized egg, if it hatches, the product will be a complete chick — not one that is missing crucial parts. “The question Turing fails to answer is: How do you get that scaling process?” Green said.
The answer might lie in a new paper on the formation of digits in the paws of mouse embryos.
Digit patterning is similar to that of stripes. But although fingers fan out in a pattern of stripes, the distance between the fingertips — the wavelength, if you will — and the distance between the knuckles are different. The pattern scales proportionately. If those stripes arise from a Turing mechanism, something else must be influencing the scaling.
It turns out there are two processes at work in digit patterning: the Turing mechanism that produces the stripelike pattern and a second tuning mechanism to control scaling via the Hox genes. Sharpe prefers to view them as different aspects of the same mechanism.