The renal system of <i>Drosophila</i> consists of 4 single cell-layered epithelial tubes. Organogenesis of these tubes involves both cellular rearrangement, as they elongate, and the integration of an additional cell population from the surrounding mesoderm. To understand how polarity is established and maintained during these processes, I have characterised the activity of cell polarity genes throughout development. My data suggest that there is a temporal difference in the requirement for one of the key apical proteins, Crumbs, between the epidermis and the tubules. In the epidermis, Crumbs is essential for the formation of the Zonula Adherens junctions (ZAs) so that in Crumbs mutants, the epidermis falls apart at the onset of germ band elongation. The tubules however, form ZAs and localise polarity markers during early stages of development, but by the end of embryogenesis, they lose their tubular organisation and mislocalise both polarity and junctional proteins. The requirement for Crumbs in the tubules occurs at the onset of cellular rearrangement and cell integration. I have used genetics to stall both these morphogenetic movements and find that Crumbs is not longer required to maintain polarity in the tubules. These data suggest that the temporal difference in the requirement for Crumbs between the two tissues is due to the timing of their major morphogenetic movements. This suggests that Crumbs is required to maintain polarity when tissues are morphogenetically active. A key event that could trigger the requirement for Crumbs is the integration of the second mesenchymal cell population, the stellate cells. I have analysed how polarity is established in the stellate cells and how this relates to tubule polarity. I have shown that cell polarity genes become localised in the stellate cells once they have integrated into the tubule epithelium.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:597249 |
| Date | January 2008 |
| Creators | Campbell, K. A. |
| Publisher | University of Cambridge |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
Page generated in 0.0024 seconds