Notochord induction of zebrafish slow muscle mediated by Sonic hedgehog
Abstract
The patterning of vertebrate somitic muscle is regulated by signals from neighboring tissues. We examined the generation of slow and fast muscle in zebrafish embryos and show that Sonic hedgehog (Shh) secreted from the notochord can induce slow muscle from medial cells of the somite. Slow muscle derives from medial adaxial myoblasts that differentiate early, whereas fast muscle arises later from a separate myoblast pool. Mutant fish lacking shh expression fail to form slow muscle but do form fast muscle. Ectopic expression of shh,either in wild-type or mutant embryos, leads to ectopic slow muscle at the expense of fast. We suggest that Shh acts to induce myoblasts committed to slow muscle differentiation from uncommitted presomitic mesoderm.
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Footnotes
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↵3 The first two authors have contributed equally to this work.
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↵4 Present address: Developmental Genetics Programme, The Krebs Institute, University of Sheffield, Sheffield S10 2TN, UK.
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↵5 Corresponding author.
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E-MAIL s.hughes{at}kcl.ac.uk; FAX 44-171 497 9078.
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- Received April 3, 1997.
- Accepted July 4, 1997.
- Cold Spring Harbor Laboratory Press
