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Title: Investigations into mouse trinucleotide repeat arrays and their putative association with CpG islands
Author: Auchincloss, Catherine Anne
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2001
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A mouse CpG island library was screened for all 10 classes of trinucleotide repeat. Sequence analysis of 89 positive clones revealed that only 32% represented CpG islands, compared to 67% of randomly derived clones. These data implied that trinucleotide repeats are under represented in mouse CpG islands. Where possible PCR primers were designed to amplify these repeats from the mouse genome. The variability of 51 repeat arrays was assessed by their PCR amplification from a panel of sixteen mouse strains. Trinucleotide repeats that exhibited length variability between C57BL/6J and Mus spretus (34/51) were mapped using a relevant interspecific backcross panel. These repeats were then screened by PCR as 'candidates' for causing mouse mutant phenotypes mapping to similar genomic regions. Two complex trinucleotide repeat arrays, which mapped to an identical region of chromosome 7, were found to be expanded in frizzy DNA. Further analysis indicated that neither repeat expansion was the underlying mutation responsible for this phenotype. A transgenic study was also carried out to explore the putative relationship between CpG islands and trinucleotide repeat instability. An expanded human Myotonic Dystrophy repeat was cloned into two similar transgenic constructs, one known to retain its native CpG island properties, and the other mutated to confer non island transgene status. Once transgenic mice had been produced, the methylation of the transgene was assessed by PCR and Southern blot. The introduction of the trinucleotide repeat and a small amount of flanking DNA appears to have complicated the predicted methylation of these transgenic constructs. The stability of the trinucleotide repeat arrays was followed through several generations of mice by fluorescent PCR analysis. Moderate trinucleotide repeat instability was observed in the majority of transgenic lines, with a strong bias towards repeat contraction and instability through the female germline. This instability did not appear associated with transgene CpG island status, as defined by methylation.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available