In the <i>Drosophila </i>peripheral nervous system (PNS), neuronal cell fates are specified by a hierarchy of events that are ultimately regulated at the level of transcription. The basic helix-loop helix (bHLH) protein family of transcription regulators are widely implicated throughout development. The first bHLH proteins shown to be involved in neurogenesis were those encoded by the <i>Drosophila achaete-scute</i> complex (AS-C). These are known as proneural genes because they are required during the earliest step of neurogenesis in which naive ectodermal cells are selected to become neural precursors. The AS-C govern the determination of precursors for the external sensory bristles. Another proneural gene, <i>ato</i>, is required for the precursors of the chordotonal organs, photoreceptors and some olfactory sensilla. However, these genes alone do not account for the formation of the rest of the nervous system, thus there must be other proneural candidate genes to be discovered. Furthermore, there is evidence to suggest that other bHLH factors are required throughout neurogenesis, acting in interlinked cascades at each successive level of cell differentiation. These too, have yet to be identified. In the expectation that more <i>Drosophila</i> neural bHLH genes exist, I searched for new genes on the basis of homology to <i>ato.</i> Indeed in this way I identified two new <i>ato</i>-like bHLH proteins. The molecular characterisation, expression and functional analyses of these genes are presented in this thesis. <i>amos</i> (absent MD neurons and olfactory sensilla) is a new proneural gene, required for the selection of neural precursors of larval md neurons and adult olfactory sensilla. On the other hand, <i>cato</i> (cousin of ato), ensures the proper differentiation of the sensory neurons.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:651666 |
| Date | January 1999 |
| Creators | Goulding, Sarah |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/14927 |
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