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Title: The yolk proteins of Drosophila are conserved through Dipteran evolution
Author: Martinez, Alberto
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1991
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The yolk proteins (YPs) in Drosophila have been shown to enter the oocyte via receptor mediated endocytosis (Mahowald, 1972; Butterworth et al., 1991). The YPs are sorted and specifically stored in the α-granules of the oocyte (Mahowald and Kambysellis, 1980). The aim of this project is to determine the YP domains involved in the specific interactions resulting in uptake into the oocyte. An evolutionary approach was chosen to attempt to determine these domains, since the YPs were assumed to have few evolutionary constraints and thus diverge readily. A functional assay was designed to investigate the uptake of foreign YPs in D. melanogaster and used to test YPs from different Drosophila and non-Drosophila species. The results indicated that the functional domains imvolved in YP uptake were conserved for up to 100 MYR (Million years) of Dipteran evolution. The molecular cloning and DNA sequence determination of Calliphora yp genes demonstrated that the YPs were very well conserved. Not only had the Calliphora YPs failed to diverge as expected but these also displayed the similarity to the vertebrate lipases shown in Drosophila YPs (Bownes et al., 1988; Perssons et al., 1989). Therefore suggesting that this is a structural constraint within the YPs of Diptera. The conservation of the amino acid sequence of the YPs did not suggest any domains which may have been involved in uptake; however, computer based database searches with five different regions of the protein suggested putative sites of importance for YP uptake. Their origin and possible functions are discussed. The Calliphora yp genes were also found to be expressed in a coordinate manner by both carcasses and ovaries, between stages 8 and 10b of oogenesis. These yp genes were found to be expressed in the follicle cells of the oocyte thus suggesting that the regulation of the yp gene expression in Calliphora and Drosophila is also conserved and thus possibly regulatory sequences and factors will be similar in these two species.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available