During metamorphosis, the larval form of a holometabolous insect is restructured to create the adult form. In Drosophila melanogaster, histoblasts are the precursor imaginal cells that generate the adult abdominal epithelium. Ecdysone triggers the histoblasts to proliferate, resulting in the expansion of the histoblast nests and the complete coverage of the abdomen. Concurrently, the larval epidermal cells (LEGs) are removed. Potentially, histoblast development can be a good system to study morphogenesis, cell migration, programmed cell death, ecdysone signaling and differentiation. However, to date, histoblast development has not been extensively studied. In this thesis, I characterised the pattern of histoblast nest expansion and fusion, .and explored behaviour of LECs during histoblast development with time-lapse analysis using novel genetic markers I identified in existing collections of Gal4 and GFP trap lines. During metamorphosis, histoblast nests spread and fuse in a strict spatial and temporal manner. Spreading is highly controlled and directed, as histoblast cells produce filopodial outgrONths and actively migrate towards the appropriate partner during fusion. LECs removal is concurrent with histoblast nest expansion. Not only are LECs removed at the histoblast migrating front as previously proposed (Madhavan and Madhavan, 1980), a significant amount of LECs located distant from histoblast nests are also destroyed. To further investigate the relationship between histoblast nest expansion and LEC removal, I disrupted cell death in LECs using genetic manipulation. I also studied the effect on the pattem of LEC removal in a mutant background which histoblast nests are severely reduced. The results from both studies suggest that histoblasts and LECs signal to one another to coordinate the events during histoblast development. Moreover, in order to explore the involvement of histoblast signalling during histoblast development, I disrupted endocytosis to inhibit histoblasts. The results point to the conclusion that signalling is important during histoblast development.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:485721 |
| Date | January 2007 |
| Creators | Lee, Ka Yan Claudia |
| Publisher | King's College London (University of London) |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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