Human RAD51 is a key protein in the repair of DNA by homologous recombination. Its assembly onto DNA, which induces changes in DNA structure, results in the formation of a nucleoprotein filament that forms the basis of strand exchange. Here, we determine the structural and mechanical properties of RAD51-dsDNA filaments. Our measurements use two recently developed magnetic tweezers assays, freel...

B-DNA becomes unstable under superhelical stress and is able to adopt a wide range of alternative conformations including strand-separated DNA and Z-DNA. Localized sequence-dependent structural transitions are important for the regulation of biological processes such as DNA replication and transcription. To directly probe the effect of sequence on structural transitions driven by torque, we hav...

BACKGROUND Fractured connections between implants and implant abutments or abutment screws are frequently encountered in a clinical setting. The purpose of this study was to investigate fracture strength using a torsion test at the interface between the implant and the abutment. METHODS Thirty screw-type implant with diameters of 3.3, 3.8, 4.3, 5.0, and 6.0 mm were submitted to a torsion test...

Torsional tension in DNA may be both a prerequisite for the efficient initiation of transcription and a consequence of the transcription process itself with the generation of positive torsional tension in front of the RNA polymerase and negative torsional tension behind it. To examine torsional tension in specific regions of genomic DNA in vivo, we developed an assay using photoactivated psoral...

Aluminum alloy AA6061 is of interest to the US Navy for ship structure applications due its light weight, ease manufacturing, corrosion resistance and strength. However, response complex loading subsequent fire damage presents a concern practical applications. The purpose this study evaluate effect on microstructure material with applied tensile, torsional, combined loading. Fire exposure was s...

We report the measurement of two new perpendicular (D2O)3 torsional bands by terahertz laser vibration–rotation–tunneling ~VRT! spectroscopy of a planar pulsed supersonic expansion. The first ~28.0 cm) band corresponds to the k562 ←0 transition, and is the lowest frequency vibrational spectrum observed for a water cluster. The second ~81.8 cm) band originates in the first excited torsional stat...