Abstracts - Deutsche Zoologische Gesellschaft

122 Developmental Biology PostersP DB.7 - ENSomite fate mapping using GFP-transgenic axolotlsNadine Piekarski, Lennart Olsson1Institut für Spezielle Zoologie und Evolutionsbiologie mit Phyletischem Museum, Friedrich-Schiller-Universität JenaSingle somite fate has been studied extensively using quail-chick chimeras. We are interested in towhat degree somite fate is conserved despite the conspicuous differences in morphology seen amongvertebrates. Therefore, we have focused our study on a urodele amphibian, the Mexican axolotl, inwhich long-term fate mapping is technically feasible. Compared to birds the axolotl is morphologicallyvery different e.g. in many skeletal muscles and in skeletal elements of the occipital region,as well as in the shoulder girdle, all known to be somitic derivatives from quail-chick chimeras.Somites two to six were fate-mapped by transplantation of single somites from GFP-transgenicaxolotls. Transplanted fluorescent somites and their derivatives were tracked in vivo, and cryosectionswere made. Our data reveal a highly conserved pattern of somitic derivatives among the twospecies. The shoulder girdle in axolotls for example has a segmental (more than one somite) and acomposite (somites and lateral plate) origin exactly as in chicken. However, there are small differencesthat could be caused by the different position in which it is being formed in the two species.We also found differences in the specific formation of the hypobranchial chord that gives rise tohypobranchial muscles. Our results support a conserved pattern of somitic derivatives, however, thesmall differences observed could be the key to understand the developmental basis of evolutionarychange in this system.P DB.8 - ENThe Hydra-FGFR Kringelchen partially rescues the htl- but not the btl-mutantphentotype of Drosophila melanogasterAnja Rudolf, Christine Hübinger, Katrin Hüsken, Angelika Vogt, Christian Hasse, Susanne Önel,Renate Renkawitz-Pohl, Monika HasselFachbereich 17, Philipps-Universität MarburgFibroblast growth factor receptors (FGFR) are important regulators during axis formation, cell migrationand branching morphogenesis in embryogenesis throughout the animal kingdom (1). FGFRare receptor tyrosine kinases (RTK) and display a highly conserved structure: two juxtamembraneIg-like loops bind FGF ligands, the intracellular split tyrosine kinase domain is highly conservedand SH2 and SH3-domain consensus sequences couple signalling to either ras/MAPK, PI-PKC orPI-3 kinase signalling. The Hydra vulgaris FGFR homologue Kringelchen controls detachment ofvegetatively growing young polyps (2). It was the first ancient FGFR that had been characterizedand was present in cnidaria already about 650 mya – long before bilateral-symmetric animals hadsplit off. We have used Drosophila melanogaster to investigate if Kringelchen can act as a prototypeFGFR and functionally replace one or both of the Drosophila FGFR Breathless (Btl) or Heartless(Htl) (3,4). To this end we established Gal-4-UAS fly lines transgenic for the Kringelchen proteinand crossed to null mutants of either of the two Drosophila FGFR. We show that Kringelchen selectivelysubstitutes for Htl- but not for Btl-signalling, which indicates specific functional conservationof FGFR signalling.