Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.649118
Title: Secondary structure in trinucleotide repeat DNA in vivo
Author: Darlow John M., J. M.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1999
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Abstract:
By inserting different numbers of different trinucleotides into the centre of a long palindrome it has been possible to investigate their tendencies to form hairpins in vivo in any particular alignment and with odd or even numbers of repeat units in the hairpin. It is shown that with d(CAG).d(CTG) repeat tracts there is a markedly greater tendency to form hairpins with even numbers of repeat units than with odd numbers whereas d(GAC).d(GTC) repeats (which are rare, short, and have not been found to expand) show no such alternation despite having the same base composition. d(CAG)2.d(CTG)2 behaves like DNA sequences known to form two-base loops in vitro suggesting that one or both of the strands may also form a compact and stable loop. d(CGG)2.d(CCG)2 also produces very small plaques but beyond d(CGG)3.d(CCG)3 the pattern is different from that of d(CAG).d(CTG) repeats. It seemed likely that this might be because d(CGG).d(CCG) repeats have more than one possible alignment in which they could self-anneal. Further investigation has shown that while even-membered hairpins are preferred in the frame d(CGG).d(CCG), hairpins with odd numbers of trinucleotides are more stable in the frame d(GGC).d(GCC). The disadvantage of the plaque construct is that the orientation of the inserted sequence cannot be predetermined and cannot be ascertained afterwards because it is not possible to sequence across the palindrome. A new phage λ derivative has been constructed which shows that orientation does not affect the in vivo test of hairpin-forming potential. It is also shown that dGAA appears to form a tight hairpin loop in vivo as it does in vitro.
Supervisor: Professor David R. F. Leach. Sponsor: Medical Research Council
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.649118  DOI: Not available
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