Title:
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Genetic and developmental analysis of the Drosophila Central Complex : generation and organisation of distinct neuronal subsets
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The distinct structure of the Central Complex (CC) spanning the midline is one of the most prominent features of the Drosophila brain. The CC is highly conserved across insect species and is involved in multimodal information processing and coordination of locomotion. By employing a combination of immunohistochemical techniques, enhancer trap technology and mutant analysis, this thesis has analysed the structural development of the CC. In this study the expression patterns from a subset of genes encoding Cell adhesion molecules generated three developmental series’ from which a development timeline for the CC was determined. The echinoid gene displayed elevated expression in the Horizontal fibre system allowing a detailed developmental characterisation of this set of isomorphic neurons. Further analysis using enhancer trap lines revealed genetic subdivision of neurons and isolation of isomorphic sets. These lines were subsequently used to assess the development of several identified CC neurons. These experiments determined CC development to be in the first 48-52 hours after puparium formation. The Fl neurons and neurons of the Horizontal and Vertical fibre systems were established first followed by a second wave of outgrowth from Pontine, fb-eb and R neurons. This study infers details of gross CC structure indicated by projection patterns of neurons and mutant analysis. One of the genes involved in development, echinoid, is further analysed for a potential pathfinding function using the model of the Optic lobe. Finally, this thesis presents the advantages conferred by the use of enhancer trap lines for developmental study of the CC and has isolated a novel set of these lines that will be beneficial for future studies into both development and behaviour of the CC.
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