A nanowall array structure was fabricated on a quartz chip as a separation matrix of DNA fragments, and a 30 s separation was realized for a mixture of DNA fragments (48.5 and 1 kbp fragments) by applying the electric voltage. A longer DNA fragment migrates faster than a shorter one in a nanowall array chip, and it is completely different from the separation of DNA based on gel electrophoresis, nanopillar chips, and nanoparticle array chips. Although the result is similar to DNA separation by entropic trapping, it could not be fully explained by entropic trapping phenomena. Direct observation of single-DNA molecular dynamics inside a nanowall array structure indicates that both confined elongation and relaxation recoiling of a DNA molecule occur, and an elongated DNA molecule migrates faster than a recoiled DNA molecule. Numerical fitting of DNA molecular dynamics reveals that the balance between times for the transverse of a DNA molecule in the nanowall array chip and the relaxation-recoiling of a DNA molecule governs the separation of DNA.

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The current results indicate that diabetic autonomic neuropathy is associated with more severe intraoperative hypothermia. We postulate that diabetic patients become more hypothermic because their peripheral neuropathy delays the onset of thermoregulatory vasoconstriction and reduces its efficacy once triggered. These patients may therefore fail to develop a normal core temperature plateau.

Rotation of the polar flagellum of Vibrio alginolyticus is driven by a Na؉ -type flagellar motor. FliG, one of the essential rotor proteins located at the upper rim of the C ring, binds to the membrane-embedded MS ring. The MS ring is composed of a single membrane protein, FliF, and serves as a foundation for flagellar assembly. Unexpectedly, about half of the Vibrio FliF protein produced at high levels in Escherichia coli was found in the soluble fraction. Soluble FliF purifies as an oligomer of ϳ700 kDa, as judged by analytical size exclusion chromatography. By using fluorescence correlation spectroscopy, an interaction between a soluble FliF multimer and FliG was detected. This binding was weakened by a series of deletions at the C-terminal end of FliF and was nearly eliminated by a 24-residue deletion or a point mutation at a highly conserved tryptophan residue (W575). Mutations in FliF that caused a defect in FliF-FliG binding abolish flagellation and therefore confer a nonmotile phenotype. As data from in vitro binding assays using the soluble FliF multimer correlate with data from in vivo functional analyses, we conclude that the C-terminal region of the soluble form of FliF retains the ability to bind FliG. Our study confirms that the C-terminal tail of FliF provides the binding site for FliG and is thus required for flagellation in Vibrio, as reported for other species. This is the first report of detection of the FliF-FliG interaction in the Na ؉ -driven flagellar motor, both in vivo and in vitro. Many motile bacteria can swim in liquid environments by means of a motility organelle, the flagellum. Bacteria propel themselves by rotating a helical flagellar filament to move forward, and flagellar rotation is driven by a reversible rotary motor at its base. The flagellum is divided into three parts: the filament (screw), the hook (universal joint), and the basal body (motor). About 50 gene products are required for flagellar assembly and function (1, 2). The energy source for the flagellar motor is the electrochemical gradient of protons or, in some species, sodium ions. The ion flux through stator units that are incorporated around the rotary part of the motor (rotor) is coupled with the generation of torque. The flagellar motor can rotate up to 1,700 revolutions per second (rps) (in the case of the Na ϩ -driven Vibrio motor) and can switch its rotational direction within a millisecond, properties which identify it as an elaborate biological nanomachine (3). However, the key question, how is the rotor-stator interaction coupled to ion flux to generate motor torque, has remained a mystery.Genetic, biochemical, and structural analyses identified key proteins that are most closely involved in torque generation: the stator complex and FliG in the rotor (Fig. 1A) (4). The stator is composed of two membrane proteins (MotA and MotB or their orthologs) that form an ion-conducting force-generating unit (5, 6). In the H ϩ -driven Escherichia coli or Salmonella motor, MotA, with 4 transmembrane (TM) segments, and M...

Here we report an anomalous behavior of water, especially its viscosity and hydrodynamic flow, in a nanometer-confined space. As a typical model of a nanometer-confined space, the nanopillar chip, which was developed for DNA size-based separation was used, and single-particle tracking (SPT) technique was applied to investigate water viscosity and hydrodynamic flow in the nanopillar chip. The diffusion coefficients of nanospheres were almost one-third of the theoretical value derived from the Stokes-Einstein equation. This result gave indirect proof that water viscosity in a nanometer-confined space is higher than in a bulk solution. In order to improve resolution and throughput of the nanopillar chip for DNA separation, these potential factors affecting performance should be seriously considered.