thesis
Analysis of drongo, a new Drosophila zinc finger gene expressed during oogenesis and neurogenesis
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Abstract
This thesis is an investigation into the function of the drongo, a novel gene with a
zinc finger motif, orignally isolated via enhancer trapping from its expresssion in the
embryonic neuroectoderm. Drongo has previously been shown to be expressed during
oogenesis, neurogenesis and eye development.
In this project, sequencing of a Drongo cDNA clone, shows homology to human
nucleoporin protein hRIP; and a lesser extent to other proteins including the mammalian
ARF-l GTPase activating protein (ARF-l GAP), a protein involved in vesicular transport
across the cell; and family of yeast zinc finger genes GTSI/GCSI/GL03, members of
which have also recently been shown to have GAP activity.
Overexpression of drongo during early oogenesis results in egg chambers with
supernumary nurse cells, probably as a result of a delay in follicle cell migration; a
phenotype similar to that of braniac mutants. Overexpression during late oogenesis
causes a mislocalisation of Oskar, producing embryos which lacked denticle belts and
which often had posterior defects, suggesting that ectopic expression of the gene at
different times in development can have different consequences.
A mutagenesis screen carried out generated a number of potential mutant alleles,
although none as yet have identified a mutation in the drongo gene. The use of an peptide
antibody to the protein on S2 cells and western blots has identified a possible localisation
of the Drongo protein to the endoplasmic reticulum, suggesting a role in vesicle transport.
Drongo has also been shown to be developmentally expressed and the gene appears to
encode two proteins which may or may not be functionally distinct. The role of Drongo
as a possible ARF GAP, are discussed