The Identification of Male-Specific Transcripts From D. melanogaster

Russell, Steven R. H (1989) The Identification of Male-Specific Transcripts From D. melanogaster. PhD thesis, University of Glasgow.

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A primary Lambda genomic library was screened with cDNA probes derived from male and female 3rd instar larval mRNA. Twenty clones which show male-specific or male-elevated expression were identified. Ten of these clones have been characterised in some detail. Two of the clones, gK14 and gK21, appear to be re-isolates of the previously identified male-specific genes mst349 and mst336 (DiBenedetto et al., 1987). These, along with five new isolates (gS4, gS8, gS9, gS10, gK33) show expression patterns on northern blots consistent with germline-specific expression. The transcripts are expressed in male larvae, pupae and adults but not in agametic males or XX individuals transformed to somatic males by the tra2 mutation (pseudomales). Two of these clones, gS8 and gS9, are non-overlapping but cross hybridise at high stringency indicating that they contain the same or very similar sequences. Partial cDNA clones identify a single band in female DNA but multiple bands in male DNA, suggesting the transcribed sequence is Y associated. Many of these male-specific bands are conserved in at least 3 different laboratory strains. Northern blots using RNA from XO and XY males show similar levels of the transcript suggesting that the non sex-specific locus can be transcribed, at least in the absence of a Y chromosome. In-situ hybridisation to polytene chromosomes with either of the genomic clones give no signal suggesting that the non sex-specific genomic location is under replicated or heterochromatic. Another of these germline-specific clones, gS4, appears to be heterochromatic. Southern blots of genomic DNA indicate the presence of several different repeats. In addition in-situ hybridisation to polytene chromosomes indicate that these repeats reside at a single genomic location: at the base of the left arm of chromosome 2. Of the three remaining clones, gS1 identifies a weakly expressed 3.0kb male-specific transcript. Although this transcript is not detected in agametic males low levels of expression during the pupal stage suggests that it may not be germline specific. The other two clones gS2 and gK15, are overlapping and map uniquely to region 61F on the polytene chromosome map. These clones identify at least 3 male-specific transcripts on northern blots as well as a non sex-specific transcript which is elevated during the embryonic and pupal stages. The pattern of expression appears to be complex, all of the transcripts are developmentally regulated. One of the male-specific transcripts is expressed in agametic males and possibly in pseudomales. This transcript is also present in the embryo although it is not known at present if it is sex-specific at this stage.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Keywords: Genetics
Date of Award: 1989
Depositing User: Enlighten Team
Unique ID: glathesis:1989-77980
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 30 Jan 2020 15:45
Last Modified: 30 Jan 2020 15:45

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