Activation of butterfly eyespots by Distal-less is consistent with a reaction-diffusion process Heidi Connahs, Sham Tlili, Jelle van Creij, Tricia Y. J. Loo, Tirtha Das Banerjee, Timothy E. Saunders, Antónia Monteiro Development 2019 146: dev169367 doi: 10.1242/dev.169367 Published 9 May 2019
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.
License type:
http://creativecommons.org/licenses/by/4.0/
Funding Info:
H.C. was funded by a Ministry of Education - Singapore (MOE) grant (MOE2015-T2-2-159) awarded to A.M. T.Y.J.L. was funded by MOE grant (MOE2016-T3-1-005), awarded to T.E.S. S.T. was supported by a Human Frontier Science Program Young Investigator Grant (RGY0083/2016), awarded to T.E.S. T.D.B. acknowledges
support from a Yale-NUS College graduate research fellowship. J.v.C. was self-funded.