I have investigated the role of Epidermal Growth Factor Receptor (EGFR) signalling in the control of ommatidial orientation. Both over- and under-activation of the pathway lead to significant defects in ommatidial orientation, while leaving the polarity of ommatidial unaffected. This previously unrecognised function of EGFR signalling further adds to the multiple functions of the pathway in <i>Drosophila</i> eye development. I have shown that the initial rotational event proceeds normally in EGFR pathway mutants, but that orientation becomes disrupted later in development, leading to the severe adult phenotypes seen. It is unclear which of the EGFR ligands is responsible for mediating its function in rotation: both Keren and Spitz may be important. At present, no mutant exist in <i>keren</i>. I have conducted a P element excision screen in an attempt to generate a <i>keren</i> mutant; characterisation of potential mutants is still ongoing. Hopefully, this will allow resolution of the question as to which ligand activates EGFR signalling to control orientation, and will also allow analysis of other potential functions of Keren. Very little is known about the cell biological processes underlying ommatidial rotation. As a first step towards gaining some insight into the mechanism by which ommatidial orientation is achieved, I have investigated a possible role for E-cadherin in this process. E-cadherin interacts genetically with EGFR signalling in rotation; however, it remains unclear whether cadherin-based adhesion has a primary function in the control of ommatidial orientation. I propose a model for the role of EGFR signalling in ommatidial orientation, in which the pathway acts in the 3<sup>rd</sup> instar disc, to lock ommatidial in place once they have reached their appropriate positions; in the absence of such a lock, ommatidial orientation can become disrupted during the remodelling of the larval disc into an adult eye.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:596973 |
| Date | January 2004 |
| Creators | Brown, K. E. |
| Publisher | University of Cambridge |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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