Antónia Monteiro, Bin Chen, Diane Ramos, and Jeffrey C. Oliver contributed equally to this work.
Distal-Less Regulates Eyespot Patterns and Melanization in Bicyclus Butterflies
Article first published online: 30 APR 2013
Copyright © 2013 Wiley Periodicals, Inc.
Journal of Experimental Zoology Part B: Molecular and Developmental Evolution
Volume 320, Issue 5, pages 321–331, July 2013
How to Cite
2013. Distal-less regulates eyespot patterns and melanization in Bicyclus butterflies. J. Exp. Zool. (Mol. Dev. Evol.) 320B:321–331., , , , , , , , .
Conflicts of interest: None.
Authors Contributions: See Acknowledgments for details.
- Issue published online: 10 JUN 2013
- Article first published online: 30 APR 2013
- Manuscript Accepted: 19 MAR 2013
- Manuscript Received: 9 MAR 2013
- NSF. Grant Numbers: IBN 0316283, IOB 0653399
Butterfly eyespots represent novel complex traits that display substantial diversity in number and size within and across species. Correlative gene expression studies have implicated a large suite of transcription factors, including Distal-less (Dll), Engrailed (En), and Spalt (Sal), in eyespot development in butterflies, but direct evidence testing the function of any of these proteins is still missing. Here we show that the characteristic two-eyespot pattern of wildtype Bicyclus anynana forewings is correlated with dynamic progression of Dll, En, and Sal expression in larval wings from four spots to two spots, whereas no such decline in gene expression ensues in a four-eyespot mutant. We then conduct transgenic experiments testing whether over-expression of any of these genes in a wild-type genetic background is sufficient to induce eyespot differentiation in these pre-patterned wing compartments. We also produce a Dll-RNAi transgenic line to test how Dll down-regulation affects eyespot development. Finally we test how ectopic expression of these genes during the pupal stages of development alters adults color patters. We show that over-expressing Dll in larvae is sufficient to induce the differentiation of additional eyespots and increase the size of eyespots, whereas down-regulating Dll leads to a decrease in eyespot size. Furthermore, ectopic expression of Dll in the early pupal wing led to the appearance of ectopic patches of black scales. We conclude that Dll is a positive regulator of focal differentiation and eyespot signaling and that this gene is also a possible selector gene for scale melanization in butterflies. J. Exp. Zool. (Mol. Dev. Evol.) 320B:321–331, 2013. © 2013 Wiley Periodicals, Inc.