1. Stem Cells and Regenerative Medicine
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Distinct mechanisms underlie oral versus aboral regeneration in the cnidarian Hydractinia echinata

  1. Brian Bradshaw
  2. Kerry Thompson
  3. Uri Frank  Is a corresponding author
  1. National University of Ireland, Ireland
Research Article
  • Cited 35
  • Views 3,298
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Cite this article as: eLife 2015;4:e05506 doi: 10.7554/eLife.05506


Cnidarians possess remarkable powers of regeneration, but the cellular and molecular mechanisms underlying this capability are unclear. Studying the hydrozoan Hydractinia echinata we show that a burst of stem cell proliferation occurs following decapitation, forming a blastema at the oral pole within 24 hours. This process is necessary for head regeneration. Knocking down Piwi1, Vasa, Pl10 or Ncol1 expressed by blastema cells inhibited regeneration but not blastema formation. EdU pulse-chase experiments and in vivo tracking of individual transgenic Piwi1+ stem cells showed that the cellular source for blastema formation is migration of stem cells from a remote area. Surprisingly, no blastema developed at the aboral pole after stolon removal. Instead, polyps transformed into stolons and then budded polyps. Hence, distinct mechanisms act to regenerate different organs in Hydractinia. This model, where stem cell behavior can be monitored in vivo at single cell resolution, offers new insights for regenerative biology.

Article and author information

Author details

  1. Brian Bradshaw

    School of Natural Sciences and Regenerative Medicine Institute, National University of Ireland, Galway, Ireland
    Competing interests
    The authors declare that no competing interests exist.
  2. Kerry Thompson

    Centre for Microscopy and Imaging, Discipline of Anatomy, School of Medicine, National University of Ireland, Galway, Ireland
    Competing interests
    The authors declare that no competing interests exist.
  3. Uri Frank

    School of Natural Sciences and Regenerative Medicine Institute, National University of Ireland, Galway, Ireland
    For correspondence
    Competing interests
    The authors declare that no competing interests exist.

Reviewing Editor

  1. Alejandro Sánchez Alvarado, Howard Hughes Medical Institute, Stowers Institute for Medical Research, United States

Publication history

  1. Received: November 6, 2014
  2. Accepted: April 16, 2015
  3. Accepted Manuscript published: April 17, 2015 (version 1)
  4. Version of Record published: May 6, 2015 (version 2)


© 2015, Bradshaw et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.


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