Development of Novel Tools to Study Atonal in Neurogenesis

During early neural development, progenitor cells participate in regulat ory pathways that involve cell fate decision and tissue patterning. Alth ough many factors of these regulatory pathways are known and studied, a lot of them still remain unidentified. We use Drosophila as a model organism to find and investigate the molecular mechanisms that con trol early neurogenesis. Drosophila is an excellent model organism to study and screen for mutant s involved in neurogenesis. Its peripheral nervous system (PNS) has exte rnal features that allow easy scoring for mutations that affect normal d evelopment. Drosophila bristles (external part of the sensory organ), an d the Drosophila compound eye have been used extensively to look for and study mutations affecting normal neuronal development. In this work we are studying ato, a proneural gene in Drosophila. D espite the fact that we know when and where ato genes are required in th e Drosophila peripheral nervous system and how they interact with Notch signaling to select sensory organ precursors (SOP), the mechanisms that mediate their activity within SOPs and their specificity in inducing neu ronal differentiation remain largely unknown. We performed a computation ally supported genetic screen to find dominant modifiers of Ato. First w e validated this computational based prioritization method, called HIGHF LY-ENDEAVOUR and showed that biologically meaningful prioritizations cou ld be obtained, secondly we used it to prioritize genes located in defic iencies (large deletions) that dominantly modified ato. Thus we wer e able to retrieve the genes responsible for this modification, finding 18 dominant modifiers of ato. The second aim of this work was to create a tool to study ato in it s endogenous locus by exchanging ato, through ends out homologous recomb ination, with an RMCE docking site. This RMCE docking site allows effici ent targeting of the ato locus and we obtained an overall efficiency of 10%. We used this tool, which we called IMAGO (Integrase-Med iated Approach for Gene Knock-Out) to target ato with a construct that allows the generation of postmitotic clones i n Drosophila.status: publishe