The M26 mutation in the ade6 gene of Schizosaccharomyces pombe creates a hot spot of meiotic recombination. A single base substitution, the M26 mutation is situated within the open reading frame, near the 5' end. It has previously been shown that the heptanucleotide sequence 5' ATGACGT 3', which includes the M26 mutation, is required for hot spot activity. The 510-bp ade6-delXB deletion encompa...

We studied the effects of hapten heterology on immunoassays of triiodothyronine (T3), digoxin, and cortisol, in a format involving labeled monoclonal antibodies and immobilized, protein-conjugated ligands. Replacing the homologous conjugated ligands T3, digoxin, and cortisol with their respective analogs diiodothyronine, digitoxin, and corticosterone led in each case to a decrease in the midpoi...

DNA experiences torsional stress resulting from the activities of motor enzymes and bound proteins. The mechanisms by which this torsional stress is dissipated to maintain DNA structural integrity are not fully known. Here, we show that a Holliday junction can limit torsion by coupling rotation to translocation and torque to force. The torque required to mechanically migrate through individual ...

Many group I introns encode endonucleases that promote intron homing by initiating a double-strand break-mediated homologous recombination event. A td intron-phage lambda model system was developed to analyze exon homology effects on intron homing and determine the role of the lambda 5'-3' exonuclease complex (Red alpha beta) in the repair event. Efficient intron homing depended on exon lengths...

Mitochondrial DNA deletions and point mutations accumulate in an age-dependent manner in mammals. The mitochondrial genome in aging humans often displays a 4977-bp deletion flanked by short direct repeats. Additionally, direct repeats flank two-thirds of the reported mitochondrial DNA deletions. The mechanism by which these deletions arise is unknown, but direct-repeat-mediated deletions involv...

The defining event in homologous recombination is the exchange of base-paired partners between a single-stranded (ss) DNA and a homologous duplex driven by recombinase proteins, such as human RAD51. To understand the mechanism of this essential genome maintenance event, we analyzed the structure of RAD51-DNA complexes representing strand exchange intermediates at nanometer resolution by scannin...

The relative contribution of DNA restriction and of sequence heterology as barriers to interspecies transfer of DNA was studied in the heterologous transformation of Bacillus subtilis recipients by DNA was studied in the heterologous transformation of Bacillus subtilis recipients by DNA isolated from B. globigii. Transformants were obtained at very low frequencies in the evolutionarily nonconse...

Formation of unstable plaques frequently results in atherothrombosis, the major cause for ischaemic stroke, myocardial infarction and peripheral arterial disease. Patients who have symptomatic thrombosis in one vascular bed are at increased risk of disease in other beds. However, the development of the disease in carotid, coronary and peripheral arteries may have different pathophysiology sugge...