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Title: The functional significance of mammalian chromosome banding
Author: Craig, Jeffrey M.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1995
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The work undertaken has involved an investigation of the relationship between different aspects of chromosome behaviour and their relation to chromosome banding patterns. Firstly, unmethylated CpG islands, associated with just over 50% of human genes, were used as gene-specific markers. By exploiting their methylation-sensitive restriction enzyme cleavage sites, digestion with three such enzymes effectively yielded kilobase to megabase-sized inter-gene restriction fragments. To investigate the relationship between Alu repeat density and gene density, each size fraction was purified and subjected to Alu PCR (inter-Alu amplification). Although it was hoped that a greater density of Alus would lead to a greater number of amplification products, this approach proved fruitless due to unavoidable contamination between the original inter-island size fractions. However, it was found that the chromosome bands containing the highest number of mapped genes were also the most Alu-rich bands, according to published data. It was also established from such data that R bands contain 80% of the 2% of human genes mapped to date. To verify this link for a greater proportion of human genes, inter-island fragments were "painted" to metaphase chromosomes using fluorescence in situ suppression hybridisation (FISH) to display their bands of origin. Working with a single human chromosome 11, it was shown that each chromosome band has a characteristic range of gene density, with each type of band (e.g. R, G) having a similar gene density. It is apparent from this work that R bands and G bands represent separate compartments of the human euchromatic genome, with R bands containing the vast majority of genes. These findings also pinpoint the regions of the genome which will yield the highest density of coding sequence information. This work also paves the way to the further physical and biochemical characterisation of G and R band chromatin compartments.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available