Special Issue Patterns & Phenotypes
Asymmetry in a pterobranch hemichordate and the evolution of left–right patterning
Article first published online: 3 JUN 2008
Copyright © 2008 Wiley-Liss, Inc.
Special Issue: Special Focus on Left-Right Asymmetry
Volume 237, Issue 12, pages 3634–3639, December 2008
How to Cite
Sato, A. and Holland, P. W.H. (2008), Asymmetry in a pterobranch hemichordate and the evolution of left–right patterning. Dev. Dyn., 237: 3634–3639. doi: 10.1002/dvdy.21588
- Issue published online: 20 NOV 2008
- Article first published online: 3 JUN 2008
- Manuscript Accepted: 20 APR 2008
- Research Institute of Marine Invertebrates Foundation
- Ishizaka Foundation
- St Catherine's College (University of Oxford) Kobe Institute
To investigate the possible origin of vertebrate asymmetry, we reexamined the long-described asymmetry of pterobranch hemichordates, a group of tiny, mostly colonial marine filter feeders. As first described over a century ago, we found left–right (LR) asymmetry in localization of the gonad. However, contrary to early descriptions, the direction of asymmetry is random, displaying antisymmetry rather than directional asymmetry. We found that the direction of gonad localization is significantly related to the shape of the tube in which the zooid lives. We also reexamined other anatomical features described to have directional asymmetry, the shape of the oral lamella and localization of the gonopore; however, we did not confirm asymmetry in these examples. Together with previous studies, our results suggest that hemichordates have undergone degeneration in the precision of asymmetry from an ancestral asymmetrical condition that existed before the divergence of deuterostomes. Developmental Dynamics 237:3634–3639, 2008. © 2008 Wiley-Liss, Inc.