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Title: Transcriptional regulation of the I factor, a Drosophila melanogaster transposable element
Author: Clark, Ivan Benjamin Nile
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1999
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The I factor is a transposable element of the LINE family found in Drosophila melanogaster. High frequency I factor transposition is associated with I-R hybrid dysgenesis, a syndrome of female sterility occurring in the progeny of males from an inducer strain, which carry active I factors and females from a reactive strain, which do not. Expression of the I factor is restricted to the female germ line and is repressed in inducer strains. Transcription is regulated by sequences located internally in the 5' untranslated region of the element. A sequence-specific DNA binding protein present in ovaries recognises a 19bp site within this region, known as site 1, which a previous study suggested is important for germ line-specific transcription. The protein that binds to site 1 was identified as Adult Enhancer Factor 1, a transcriptional repressor that regulates the alcohol dehydrogenase and yolk protein genes. A series of mutations were made in site 1 and the effects on AEF-1 binding in vitro, and the expression of a reporter gene controlled by I factor regulatory sequences in vivo, were investigated. It was discovered that deletion of site 1 and other mutations that reduce AEF-1 binding did not reduce AEF-1 binding did not reduce expression, contrary to previous findings. The transgenes used in the previous study were characterised and found not to be as they were described. Expression of both sense and antisense AEF-1 RNA in the female germ line caused a slight reduction in ovarian expression from a reporter gene under the control of the I factor regulatory sequences. The implications of these findings for models of I factor regulation are discussed.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available