title: 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.
authors.affiliation: Developmental Biology Research Centre, The Randall Institute, King's College London, UK.
authors.forename: C S
authors.initials: CS
authors.lastname: Blagden
authors.forename: P D
authors.initials: PD
authors.lastname: Currie
authors.forename: P W
authors.initials: PW
authors.lastname: Ingham
authors.forename: S M
authors.initials: SM
authors.lastname: Hughes
mesh_terms: D000818:Animals; D005075:Biological Evolution; D004627:Embryonic Induction / Q000235:genetics / Q000502:physiology*; D053823:Hedgehog Proteins; D007150:Immunohistochemistry; D008648:Mesoderm / Q000166:cytology; D018656:Muscle Fibers, Fast-Twitch / Q000166:cytology / Q000378:metabolism; D018657:Muscle Fibers, Slow-Twitch / Q000166:cytology* / Q000378:metabolism; D009154:Mutation; D018995:Myosin Heavy Chains / Q000378:metabolism; D009672:Notochord / Q000196:embryology*; D011506:Proteins / Q000235:genetics / Q000502:physiology*; D013997:Time Factors; D015534:Trans-Activators; D015027:Zebrafish / Q000196:embryology* / Q000235:genetics / Q000378:metabolism
chemical_list: D053823:Hedgehog Proteins; D011506:Proteins; D015534:Trans-Activators; D018995:Myosin Heavy Chains