Male-Specific Transcripts From Drosophila melanogaster

Harbison, Diane T (1996) Male-Specific Transcripts From Drosophila melanogaster. PhD thesis, University of Glasgow.

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Eight genomic DNA clones previously identified in a differential screen to identify male-specific transcripts (Russell, 1989) were selected for analysis. These recombinant phage appear to represent six genomic loci. Three of these genomic clones gK22, gK30 and gK31 were identified once while others (gK6 & gK27 and gK8 & gK10) represented genomic DNA phage which originated from the same genomic region. Clone gK17 appeared to be identical to clone gS4 characterised by Russell (1993) and was not analysed any further. The relationship between gK6 & gK27 and gK8 & gK10 was confirmed by cross-hybridisation and restriction mapping. The longest clone from each of the two classes (gK10 and gK27) were selected for further analysis. The data obtained from Southern analysis and in situ hybridisation to polytene chromosomes suggests that three (gK10, gK22, & gK31) of the genomic DNA clones which were selected for further characterisation represent single copy genes located on the autosomes. Genomic DNA clone gK27 appears (from Southern and sequence analysis) to contain a duplication of the fragment which contains the putative male-specific transcript. None of them appear to be re-isolates of previously characterised male-sterile or male-lethal loci. Some of the male-specific transcripts are expressed in the larval testis and in the case of two of the transcripts represented by gK27 and gK31, contain transcripts that are expressed in the adult testis. Restriction of the transcripts to the adult testis has been confirmed by northern analysis for two of the clones gK10 and gK27. In both cases, transcripts were detected only in males and not in females. Additionally, transcripts derived from clones gK10 and gK27 were not detected in tudor flies nor in female flies transformed into pseudomales by mutations in the transformer2 gene. These results suggest a germline-specific function for these transcripts. Two P[lacZ] insertion lines recovered during a screen for spermatogenic mutatations (Castrillon et al.; 1993) mapped near the cytological locations of two of the genomic DNA clones gK27 (insertion line designated MS(3)90E) and gK22 (designated pistachio, (pto)). Insertions at these locations resulted in sterility (pto) and in sterility and semi-lethality (MS(3)90E) respectively. cDNA clones corresponding to the male-specific regions of genomic DNA clones gK31 and gK27 were isolated and the DNA sequenced. The cDNA corresponding to genomic DNA clone gK31 (cK31) showed no apparent significant homology with other sequences in the SwissProt database, whilst cDNA corresponding to genomic DNA clone gK27 (cK27) showed significant homology to a group of proteins known as the HMG-box proteins. The HMG-box is a DNA binding domain that was first identified in a group of proteins that comprised the non-histone component of chromatin (The High Mobility Group or HMG proteins). As cK27 appeared from northerns not to represent a full length transcript, the two male- specific genomic regions from the original genomic DNA clone gK27 were sequenced. This analysis suggested that the presence of two male-specific regions in the gK27 genomic DNA clone had arisen due to a duplication of this region. cDNAs corresponding to the other two clones(gK10 and gK22) have been isolated but have not yet been characterised. The four genomic clones selected for further characterisation in this study appear to represent a class of germ-line specific transcripts. It is possible that they may be involved in spermatogenesis.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: Mary Bownes
Keywords: Genetics
Date of Award: 1996
Depositing User: Enlighten Team
Unique ID: glathesis:1996-75245
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 19 Nov 2019 21:28
Last Modified: 19 Nov 2019 21:28

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