Studies of Wnt Signalling in Drosophila

The work presented is based on *Drosophila* genetics, a model organism in developmental biology. Several important segmentation and patterning processes are studied extensively in *Drosophila*. These processes are mediated by a few very conserved pathways. Because of its relation to human diseases like cancer, Alzheimer’s and diabetes, one of these pathways is of major importance in this studies, the Wnt signal transduction pathway. The bristles of *Drosophila* are the extremes of the peripheral nervous system, linking the outside to the inside. It is therefore that the stereotyped pattern in which the bristles occur is conserved throughout evolution. A successful model to investigate the Wnt pathway are the genetic mechanisms underlying bristle patterning in *Drosophila*. Two previous uncharacterised genes that are strong candidates to be members of the pathway under investigation form the objects of study in this thesis. *kiwi*, is a gene retrieved from a big scale mutation screen with an interesting phenotype, whereas P[ED17] is an enhancer trap line that was recovered from a small scale insertion screen. This account reports the results from different strategies to obtain coding regions from the *kiwi* gene. It also describes the design and fine tuning of a novel combination of molecular techniques to obtain such coding sequence. Finally, it indicates directions for future research on the *kiwi* locus. Concerning the P[ED17] locus this thesis confirms the proposed expression pattern of the P[ED17] construct by means of both a double antibody and an X-gal staining and discusses possible genetic models that might form the basis for this expression pattern. Besides a molecular analysis of the genomic DNA adjacent to the putative insertion site, it reports the generation of homozygous ED17 revertant fly-lines. Finally, directions for future approaches are given.