No abstract

These data suggest clinical utility of baseline WBMRI in TP53 germline mutation carriers and may form an integral part of baseline clinical risk management in this high-risk population.

The dif locus (deletion-induced filamentation) of Escherichia coli is a resolvase site, located in the terminus region ofthe chromosome, that reduces chromosome multimers to monomers. In strains in which this site has been deleted, a fraction of the cells is filamentous, has abnormal nucleoid structure, and exhibits elevated levels of the SOS repair system. We have demonstrated that a 33-bp sequence, which is sufficient for RecA-independent recombination and which shows similarity to the cer site ofpColEl, suppresses the Dif phenotype when inserted in the terminus region. Flanking sequences were not required, since suppression occurred in strains in which difas well as 12 kb or 173 kb ofDNA had been deleted. However, location was important, and insertions at a site 118 kb away from the normal site did not suppress the Dif phenotype. These sites were otherwise still functional, and they exhibited wild-type levels of RecA-independent recombination with dif-containing plasmids and recombined with other chromosomal dfsites to cause deletions and inversions. It is proposed that the functions expressed by a difsite depend on chromosome location and structure, and analysis of these functions provides a way to examine the structure ofthe terminus region.