Activation of butterfly eyespots by Distal-less is consistent with a reaction-diffusion process

Development. 2019 May 9;146(9):dev169367. doi: 10.1242/dev.169367.

Abstract

Eyespots on the wings of nymphalid butterflies represent colorful examples of pattern formation, yet the developmental origins and mechanisms underlying eyespot center differentiation are still poorly understood. Using CRISPR-Cas9 we re-examine the function of Distal-less (Dll) as an activator or repressor of eyespots, a topic that remains controversial. We show that the phenotypic outcome of CRISPR mutations depends upon which specific exon is targeted. In Bicyclus anynana, exon 2 mutations are associated with both missing and ectopic eyespots, and also exon skipping. Exon 3 mutations, which do not lead to exon skipping, produce only null phenotypes, including missing eyespots, lighter wing coloration and loss of scales. Reaction-diffusion modeling of Dll function, using Wnt and Dpp as candidate morphogens, accurately replicates these complex crispant phenotypes. These results provide new insight into the function of Dll as a potential activator of eyespot development, scale growth and melanization, and suggest that the tuning of Dll expression levels can generate a diversity of eyespot phenotypes, including their appearance on the wing.This article has an associated 'The people behind the papers' interview.

Keywords: Butterfly eyespots; CRISPR-Cas9; Distal-less; Gray–Scott reaction-diffusion model; Morphogens.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Butterflies
  • Clustered Regularly Interspaced Short Palindromic Repeats / genetics
  • Exons / genetics
  • Gene Expression Regulation, Developmental / genetics
  • Insect Proteins / genetics
  • Insect Proteins / metabolism*
  • Mutation / genetics

Substances

  • Insect Proteins

Associated data

  • Dryad/10.5061/dryad.2108pm6