Characterization of the breakpoints of deletion mutants at the Arabidopsis BP locus.
Published: 2005
Language: eng
Number of pages: 169
Description: Double-strand breaks (DSBs), if not repaired, are lethal lesions. The pairwise action of at least two DSBs during DSB repair may lead to intra- and interchromosomal rearrangements. Preliminary molecular studies have suggested that the brevipedicellus (bp) mutant phenotype in Arabidopsis thaliana is due to loss-of-function mutations at the BP locus. Five of the ten bp alleles are strictly due to large deletions ranging from 140 kb to over 1 Mb. Interestingly, these deletions, generated by different modes of mutagenesis (EMS, X-rays, fast neutron bombardment, or T-DNA), were considerably larger than historically attributed to each mutagen. This suggested that some DNA element(s) in this region of the genome may influence where DSBs are likely to occur. Using a six-phased molecular strategy, the deletion endpoints in  by-1, by-2, bp-3, bp-5, and bp-10 were identified and characterized. In bp-1 the deletion extends over 325 kb, in bp-2 the mutation removed more than 280 kb, in  bp-3 368 kb was deleted, in bp-5 the deletion spans 141 kb, and in bp-10 approximately 1 Mb of genomic sequence was removed. In silico analyses of the sequence surrounding each deletion breakpoint suggest that structural elements, and not sequence elements per se, found near the chromosome breaks, may have a possible role in the generation and/or repair of DSBs in this region. Putative matrix associated regions (MARs) predicted to be at the breakpoints suggest that chromatin loop domains, in particular, may play a role in chromosome breakage and chromosomal rearrangement at the BP locus.
Notes: Source: Masters Abstracts International, Volume: 44-02, page: 0761.

Thesis (M.Sc.)--University of Toronto, 2005.

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