"The challenge is moving from Turing's admittedly simplified model to pinpointing the precise mechanisms serving in the activator and inhibitor roles. This is especially challenging in biology. Per the authors of this latest paper, the classical approach to a Turing mechanism balances reaction and diffusion using a single length scale, but biological patterns often incorporate multiscale structures, grain-like textures, or certain inherent imperfections. And the resulting patterns are often much blurrier than those found in nature."
"It's a process by which colloids are transported via differences in solute concentration gradients-the same process by which soap diffuses out of laundry in water, dragging particles of dirt out of the fabric. Gupta and Alessio successfully used their new model to simulate the distinctive hexagon pattern (alternating purple and black) on the ornate boxfish, native to Australia, achieving much sharper outlines than the model originally proposed by Turing."
"So Gupta and his UCB co-author on this latest paper, Siamak Mirfendereski, figured out how to tweak the model to get the pattern outputs they desired. All they had to do was define specific sizes for individual cells. For instance, larger cells create thicker outlines, and when they cluster, they produce broader patterns. And sometimes the cells jam up and break up a stripe."
Turing mechanisms generate periodic patterns through interactions of activator and inhibitor processes coupled with diffusion. Classical Turing models balance reaction and diffusion at a single length scale and therefore produce overly regular, sharp patterns unlike many biological textures. Diffusiophoresis transports colloids along solute concentration gradients and can sharpen pattern outlines when included in reaction-diffusion models. Including diffusiophoresis produced clearer hexagonal motifs similar to boxfish markings but created overly uniform hexagons. Specifying cell-size heterogeneity in the model generated multiscale variation: larger cells yield thicker outlines, clusters produce broader motifs, and cell jamming disrupts stripes to produce realistic imperfections.
Read at Ars Technica
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