Unterschiedliche Rollen des Adaptor-Proteins Blown fuse/Skap-Hom/Scap2 unddes Aktin-Regulators Kette/Hem2/Nap1 waehrend der somatischen und viszeralenMyogenese von Drosophila melanogaster

The purpose of the present work was first to clearify in which way fusion to the two-nucleic circular visceral midgutmuscles of Drosophila melanogaster takes place. Secondly it should be examined, whether certain ultrastructural characteristics, namely the electrondense vesicles forming the so called prefusioncomplex and the electrondense plaques which appear with the somatic myoblast-fusion, are present during the whole myoblast fusion or whether they are limited to one of the two steps of myoblast fusion. Thirdly, the function of Kette, which was found to be essential for myoblast fusion by the help of an EMS-Screen, during myogenesis should be examined and kette as well as blown fuse should be placed into the cascade of known fusion-relevant genes. Furthermore it should be proven, if both are essential for viszeral myoblast fusion. Finally a hypothesis about the molecular function of Blow should be established. Light- and electron-microscopic-analysis showed, that the fusion to the circular visceral muscles as well as the first step of somatic fusion occured without prefusioncomplex and without electrondense plaques. Furthermore, blow and kette are both essential for the second step of somatic myoblast fusion, while their role in visceral myogenesis is restricted to stretching and outgrowth of the circular viscral muscles.