To gain insight regarding the mechanisms that extend heteroduplex joints in Escherichia coli recombination, we investigated the effect of recG and ruv genotypes on heteroduplex strand polarity in intramolecular recombination products. We also examined the cumulative effect of mutational inactivation of RecG and single-strand-specific exonucleases on recombination proficiency and the role of Chi...

Department of Human Genetics, Faculty of Medicine, University of Stellenbosch, Tygerberg, 7505, South Africa The ability to detect mutations in individuals and the subsequent DNA diagnosis of genetic diseases are becoming increasingly important for the researcher and diagnostician. Single-base substitutions (80-90%) can be detected by single-strand conformation polymorphism (SSCP) (1) or hetero...

REPAIR of meiotically induced double-strand breaks duplex-rejection model. The danger of ignoring symmetric heteroduplexes was made especially relevant by (DSBs; Figure 1) is associated with a gradient of gene conversion, in which conversion frequency is high Hillers and Stahl’s (1999) evidence that symmetric heteroduplex does form in yeast (see the appendix, near the DSB site and falls with di...

A novel approach to DNA probe hybridization and heteroduplex analysis, termed directed heteroduplex analysis (DHDA) is presented here to illustrate its utility in simplification of human lymphocyte antigen (HLA)-typing. By strategic labeling of single-stranded probe sequences, DHDA allows the identification of specific heteroduplex structures that contribute to the differentiation of DQA1 and D...

Heteroduplex analysis has been used extensively to identify allelic variation among mammalian genes. It provides a rapid and reliable method for determining and cataloging minor differences between two closely related DNA sequences. We have adapted this technique to distinguish among strains or clonal types of Porphyromonas gingivalis. The ribosomal intergenic spacer region (ISR) was amplified ...

The utility of restriction endonucleases as a tool in molecular biology is in large part due to the high degree of specificity with which they cleave well-characterized DNA recognition sequences. The specificity of restriction endonucleases is not absolute, yet many commonly used assays of biological phenomena and contemporary molecular biology techniques rely on the premise that restriction en...

The formation of heteroduplex joints in Escherichia coli recombination is initiated by invasion of double-stranded DNA by a single-stranded homologue. To determine the polarity of the invasive strand, linear molecules with direct terminal repeats were released by in vivo restriction of infecting chimeric phage DNA and heteroduplex products of intramolecular recombination were analyzed. With thi...

BACKGROUND Homologous recombination in Escherichia coli creates patches (non-crossovers) or splices (half crossovers), each of which may have associated heteroduplex DNA. Heteroduplex patches have recombinant DNA in one strand of the duplex, with parental flanking markers. Which DNA strand is exchanged in heteroduplex patches reflects the molecular mechanism of recombination. Several models for...

Previous work revealed that recurrent mutations (= mutation occurring more than once) in the tandemly repeated arrays present in nontranscribed spacers (NTS) of ribosomal RNA genes (rDNA) are clustered, i.e., they most frequently occur in repeats with adjacent or alternate distribution. A possible explanation is that the likelihood of heteroduplex formation, a prerequisite of gene conversion, d...