Characterisation of the Genomic Region in and Around the Shaking-B Locus of Drosophila melanogaster

Griffin, Alan (1995) Characterisation of the Genomic Region in and Around the Shaking-B Locus of Drosophila melanogaster. PhD thesis, University of Glasgow.

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The shaking-B locus of Drosophila melanogaster (formerly known as Passover) is a complex locus situated at polytene subdivision 19E3, near the base of the X chromosome. Some alleles of shak-B are embryonic or first instar larval lethals, whilst others cause defects in the nervous system of the adult fly. To clone the shak-B locus, four chromosomal walks were performed. Three walks were initiated using clones generated by a microdissection of the mal to su(f) region at the base of the X chromosome whereas a fourth was started using a cloned fragment from the runt locus. The walks encompass over 400kb of cloned DNA. Genetic analysis revealed shak-B to reside, at least in part, between the distal breakpoint of Df(1)LB6 and the proximal breakpoint of Df(1)16-3-35. This study used deficiency and duplication mapping to localise these, and other breakpoints in the walks, allowing them to be orientated and positioned onto the genetic map of the region. In addition, a transcriptional analysis was performed using reverse Northern and Northern blots. This analysis identified 28 transcription units, a number of which were shown to be repetitive. These repetitive regions have been characterised and several found to have homology to transposable elements. A large number were shown to contain a short repetitive sequence, the opa repeat. These opa repeats are associated with a large number of important, developmentally regulated genes in many organisms. The chromosomal walk that contains the shak-B locus (the 952 walk) was shown to contain less repetitive DNA and to have many more single copy transcribed regions than the others. The majority of these transcripts were analysed by Northern analysis. Transcripts were not detected in two cases. One of these is a region from which the 3' ends of shak-B transcripts originate. It is felt that the lack of signal from both regions was due either to the rarity of, or to the non-polyadenylated state of, both sets of transcripts. In situ hybridisations were performed using genomic fragments from a region of the 952 walk as a probe. This region, which is likely to contain part of the shak-B locus, gave discrete hybridisation to the lamina / retina border of the eye. Sequence was obtained from several transcribed genomic regions from the 952 walk, and several tentative homologies noted.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: Catherine Wild
Keywords: Genetics, Bioinformatics
Date of Award: 1995
Depositing User: Enlighten Team
Unique ID: glathesis:1995-76115
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 19 Dec 2019 09:15
Last Modified: 19 Dec 2019 09:15

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