title: A new level of plasticity: Drosophila smooth-like testes muscles compensate failure of myoblast fusion.
abstract: The testis of Drosophila resembles an individual testis tubule of mammals. Both are surrounded by a sheath of smooth muscles, which in Drosophila are multinuclear and originate from a pool of myoblasts that are set aside in the embryo and accumulate on the genital disc later in development. These muscle stem cells start to differentiate early during metamorphosis and give rise to all muscles of the inner male reproductive system. Shortly before the genital disc and the developing testes connect, multinuclear nascent myotubes appear on the anterior tips of the seminal vesicles. Here, we show that adhesion molecules are distinctly localized on the seminal vesicles; founder cell (FC)-like myoblasts express Dumbfounded (Duf) and Roughest (Rst), and fusion-competent myoblast (FCM)-like cells mainly express Sticks and stones (Sns). The smooth but multinuclear myotubes of the testes arose by myoblast fusion. RNAi-mediated attenuation of Sns or both Duf and Rst severely reduced the number of nuclei in the testes muscles. Duf and Rst probably act independently in this context. Despite reduced fusion in all of these RNAi-treated animals, myotubes migrated onto the testes, testes were shaped and coiled, muscle filaments were arranged as in the wild type and spermatogenesis proceeded normally. Hence, the testes muscles compensate for fusion defects so that the myofibres encircling the adult testes are indistinguishable from those of the wild type and male fertility is guaranteed.
authors.affiliation: Philipps-Universität Marburg, Fachbereich Biologie, Entwicklungsbiologie, Karl-von-Frisch Strasse 8, Marburg 35043, Germany.
authors.forename: Jessica
authors.initials: J
authors.lastname: Kuckwa
authors.affiliation: Philipps-Universität Marburg, Fachbereich Biologie, Entwicklungsbiologie, Karl-von-Frisch Strasse 8, Marburg 35043, Germany.
authors.forename: Katharina
authors.initials: K
authors.lastname: Fritzen
authors.affiliation: Philipps-Universität Marburg, Fachbereich Biologie, Entwicklungsbiologie, Karl-von-Frisch Strasse 8, Marburg 35043, Germany.
authors.forename: Detlev
authors.initials: D
authors.lastname: Buttgereit
authors.affiliation: Philipps-Universität Marburg, Fachbereich Biologie, Entwicklungsbiologie, Karl-von-Frisch Strasse 8, Marburg 35043, Germany.
authors.forename: Silke
authors.initials: S
authors.lastname: Rothenbusch-Fender
authors.affiliation: Philipps-Universität Marburg, Fachbereich Biologie, Entwicklungsbiologie, Karl-von-Frisch Strasse 8, Marburg 35043, Germany renkawit@biologie.uni-marburg.de.
authors.forename: Renate
authors.initials: R
authors.lastname: Renkawitz-Pohl
mesh_terms: D000818:Animals; D004330:Drosophila; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D008297:Male; D008954:Models, Biological; D018485:Muscle Fibers, Skeletal / Q000166:cytology / Q000378:metabolism; D032446:Myoblasts / Q000166:cytology* / Q000502:physiology; D013737:Testis / Q000166:cytology* / Q000502:physiology
chemical_list: D029721:Drosophila Proteins
keywords: Dumbfounded; Hibris; Male fertility; Roughest; Sticks and stones