Somitic positional information guides self-organized patterning of snake scales

Two influential concepts in tissue patterning are Wolpert's positional information and Turing's self-organized reaction-diffusion (RD). The latter establishes the patterning of hair and feathers. Here, our morphological, genetic, and functional-by CRISPR-Cas9-mediated gene disruption-characterization of wild-type versus scaleless snakes reveals that the near-perfect hexagonal pattern of snake scales is established through interactions between RD in the skin and somitic positional information. First, we show that ventral scale development is guided by hypaxial somites and, second, that ventral scales and epaxial somites guide the sequential RD patterning of the dorsolateral scales. The RD intrinsic length scale evolved to match somite periodicity, ensuring the alignment of ribs and scales, both of which play a critical role in snake locomotion.

Automated summary

In this study, the researchers characterized the morphological, genetic, and functional aspects of scale development in wild-type and scaleless snakes using CRISPR-Cas9-mediated gene disruption. They found that the hexagonal pattern of snake scales is established through interactions between reaction-diffusion (RD) in the skin and somitic positional information. The alignment of ribs and scales, which are both important for snake locomotion, is ensured by the evolution of the RD intrinsic length scale to match somite periodicity.