Present address: Department of Geology, Western Illinois University, Macomb, IL, 61455, USA
Decoupling elongation and segmentation: Notch involvement in anostracan crustacean segmentation
Article first published online: 5 JUL 2012
© 2012 Wiley Periodicals, Inc.
Evolution & Development
Volume 14, Issue 4, pages 372–382, July 2012
How to Cite
Williams, T., Blachuta, B., Hegna, T. A. and Nagy, L. M. (2012), Decoupling elongation and segmentation: Notch involvement in anostracan crustacean segmentation. Evolution & Development, 14: 372–382. doi: 10.1111/j.1525-142X.2012.00555.x
- Issue published online: 5 JUL 2012
- Article first published online: 5 JUL 2012
- Kelly Stanko in the Artemia experiments. Grant Number: 0236193
- Artemia normal segmentation data gathered by Lorena Lazo del la Vega. Grant Number: 0137609
Repeated body segments are a key feature of arthropods. The formation of body segments occurs via distinct developmental pathways within different arthropod clades. Although some species form their segments simultaneously without any accompanying measurable growth, most arthropods add segments sequentially from the posterior of the growing embryo or larva. The use of Notch signaling is increasingly emerging as a common feature of sequential segmentation throughout the Bilateria, as inferred from both the expression of proteins required for Notch signaling and the genetic or pharmacological disruption of Notch signaling. In this study, we demonstrate that blocking Notch signaling by blocking γ-secretase activity causes a specific, repeatable effect on segmentation in two different anostracan crustaceans, Artemia franciscana and Thamnocephalus platyurus. We observe that segmentation posterior to the third or fourth trunk segment is arrested. Despite this marked effect on segment addition, other aspects of segmentation are unaffected. In the segments that develop, segment size and boundaries between segments appear normal, engrailed stripes are normal in size and alignment, and overall growth is unaffected. By demonstrating Notch involvement in crustacean segmentation, our findings expand the evidence that Notch plays a crucial role in sequential segmentation in arthropods. At the same time, our observations contribute to an emerging picture that loss-of-function Notch phenotypes differ significantly between arthropods suggesting variability in the role of Notch in the regulation of sequential segmentation. This variability in the function of Notch in arthropod segmentation confounds inferences of homology with vertebrates and lophotrochozoans.