Patterns & Phenotypes
Inhibition of Sonic hedgehog signaling leads to posterior digit loss in Ambystoma mexicanum: Parallels to natural digit reduction in urodeles
Article first published online: 20 NOV 2006
Copyright © 2006 Wiley-Liss, Inc.
Volume 236, Issue 1, pages 321–331, January 2007
How to Cite
Stopper, G. F. and Wagner, G. P. (2007), Inhibition of Sonic hedgehog signaling leads to posterior digit loss in Ambystoma mexicanum: Parallels to natural digit reduction in urodeles. Dev. Dyn., 236: 321–331. doi: 10.1002/dvdy.21025
- Issue published online: 19 DEC 2006
- Article first published online: 20 NOV 2006
- Manuscript Accepted: 21 OCT 2006
- Society for Integrative and Comparative Biology
- Sonic hedgehog;
- digit loss;
- limb evolution;
- developmental evolution
Molecular mechanisms patterning the tetrapod limb, including anterior-posterior axis determination involving Sonic hedgehog (Shh), have received much attention, particularly in amniotes. Anterior-posterior patterning in urodele amphibians differs radically from that of amniotes in that it shows a pronounced anterior-to-posterior sequence of digit development. In contrast, amniotes develop their digits almost simultaneously with a slight posterior-to-anterior polarity. Here we use cyclopamine, an inhibitor of the Hedgehog signaling pathway, to investigate the role of Shh in anterior-posterior patterning in the urodele limb. Inhibition of Shh signal transduction affects digit number long before their morphological appearance. In accordance with the apparently derived order of digit development in urodeles, exposure reproducibly removes digits in a posterior-to-anterior sequence, the inverse of their developmental sequence. This pattern of digit loss mimics the order of digit loss in natural variation. We suggest that variation in Shh expression and/or signal transmission may explain natural variation in digit number in urodeles. Developmental Dynamics 236:321–331, 2007. © 2006 Wiley-Liss, Inc.