title: Fusion of circular and longitudinal muscles in Drosophila is independent of the endoderm but further visceral muscle differentiation requires a close contact between mesoderm and endoderm.
abstract: In this study we describe the morphological and genetic analysis of the Drosophila mutant gürtelchen (gurt). gurt was identified by screening an EMS collection for novel mutations affecting visceral mesoderm development and was named after the distinct belt shaped visceral phenotype. Interestingly, determination of visceral cell identities and subsequent visceral myoblast fusion is not affected in mutant embryos indicating a later defect in visceral development. gurt is in fact a new huckebein (hkb) allele and as such exhibits nearly complete loss of endodermal derived structures. Targeted ablation of the endodermal primordia produces a phenotype that resembles the visceral defects observed in huckebein(gürtelchen) (hkb(gurt)) mutant embryos. It was shown previously that visceral mesoderm development requires complex interactions between visceral myoblasts and adjacent tissues. Signals from the neighbouring somatic myoblasts play an important role in cell type determination and are a prerequisite for visceral muscle fusion. Furthermore, the visceral mesoderm is known to influence endodermal migration and midgut epithelium formation. Our analyses of the visceral phenotype of hkb(gurt) mutant embryos reveal that the adjacent endoderm plays a critical role in the later stages of visceral muscle development, and is required for visceral muscle elongation and outgrowth after proper myoblast fusion.
authors.affiliation: Institut für Allgemeine und Spezielle Zoologie, Allgemeine Zoologie und Entwicklungsbiologie, Justus-Liebig-Universität Giessen, Stephanstrasse 24, D-35390 Giessen, Germany.
authors.forename: Georg
authors.initials: G
authors.lastname: Wolfstetter
authors.forename: Margret
authors.initials: M
authors.lastname: Shirinian
authors.forename: Christiana
authors.initials: C
authors.lastname: Stute
authors.forename: Caroline
authors.initials: C
authors.lastname: Grabbe
authors.forename: Thomas
authors.initials: T
authors.lastname: Hummel
authors.forename: Stefan
authors.initials: S
authors.lastname: Baumgartner
authors.forename: Ruth H
authors.initials: RH
authors.lastname: Palmer
authors.forename: Anne
authors.initials: A
authors.lastname: Holz
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000502:physiology; D029721:Drosophila Proteins / Q000235:genetics* / Q000502:physiology; D004331:Drosophila melanogaster / Q000196:embryology* / Q000235:genetics; D004707:Endoderm / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D017344:Genes, Insect; D008648:Mesoderm / Q000378:metabolism*; D008856:Microscopy, Fluorescence / Q000379:methods; D008954:Models, Biological; D008957:Models, Genetic; D009132:Muscles / Q000196:embryology* / Q000378:metabolism*; D009154:Mutation; D032446:Myoblasts / Q000166:cytology; D010641:Phenotype
chemical_list: D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; C087725:Hkb protein, Drosophila