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Title: A study of C. elegans embryonic membrane systems and their roles in spindle stability
Author: Andrews, R. K.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2007
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In this thesis I describe a novel role for the Endoplasmic Reticulum (ER) in spindle positioning and stability in the early C. elegans embryo. Within the embryo the ER is intimately associated with the microtubule cytoskeleton and I show that the disruption of this association leads to instability of nuclear and spindle positioning. I first describe RNA interference screens that I performed to identify new genes involved in the regulation of spindle positioning. This led to the identification of three ER resident proteins that comprise C. elegans homologs of the Oligosaccharyl Transferase (OST) complex. Through characterisation of the spindle phenotypes induced by knockdown of OST components, I show that these proteins are similar to a diverse collection of mutants affecting the ER, such as the trans-membrane ER protein, ooc-3 and the npp (nuclear pore protein) genes. I found that identical nuclear and spindle instability phenotypes could be replicated by using the drug Brefeldin A to rapidly disrupt the ER, suggesting the ER might have a structural role in stabilizing nuclear and spindle position. I also provide evidence suggesting that the association between the ER and the microtubule cytoskeleton involves Clathrin heavy-chain (CHC). CHC may form part of the link between the ER and microtubule networks. Overall my results describe a role for the reticular ER network in stabilizing the assembling mitotic spindle and a potential new role for clathrin in linking the ER and microtubules. I addition, I show that Early Endosomes in the C. elegans embryo are polarized and asymmetrically segregated with the actin-myosin cytoskeleton, and present work optimizing the creation of transgenic lines by microparticle bombardment.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available