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Title: Multiple roles of polo kinase in Drosophila melanogaster
Author: Donaldson, M. M.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2003
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The polo gene was originally identified as a maternal effect mutation in Drosophila. Flies homozygous for the original polo1 allele display a variety of defects in cell division throughout development that include a failure to correctly assemble centrosomes in syncytial embryos, spindle defects in the larval, CNS, chromosomal non-disjunction and failures in cytokines during male meiosis. These phenotypes are consistent with roles for PLKs (Polo-like kinases) in the separation and maturation of centrosomes to form a bipolar spindle and in cytokinesis, as reported in studies of the homologous enzymes in yeasts, Xenopus and mammalian cells. Here I describe the phenotypes of two new alleles of polo, polo9 and polo10 discovered in a screen of a collection of P-element insertions on the third chromosome of Drosophila. These alleles have defects in spindle architecture and centrosome reflecting the involvement of Polo in organising the centrosomes and the bipolar spindle. They also have a severe mitotic arrest at metaphase, which coincides with high levels of cyclin B and the continued presence of components of the spindle checkpoint mechanism. This is consistent with a role for Polo in regulating some aspects of anaphase-promoting complex (APC) function - a role in which Polo-like kinases have been implicated in other organisms, but not previously in Drosophila. I also present evidence for a synergistic interaction between the polo gene and the makos gene (which encodes Cdc27, a component of the APC). Mutations in makos enhance some phenotypes seen in larval brain cells in polo mutants. Finally I present the initial data from two yeast two-hybrid screens that use the N-terminal and C-terminal halves of Polo as baits to identify interacting proteins. This screen has highlighted new interacting molecules that will help elucidate the roles of Polo kinase.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available