Quantitative DNA methylation analysis by fluorescent polymerase chain reaction single-strand conformation polymorphism using an automated DNA sequencer

A novel DNA methylation assay technique, termed bisulfite single-strand conformation polymorphism (bisulfite-SSCP), is a combination of sodium-bisulfite modification and fluorescence-based polymerase chain reaction (PCR)-SSCP. After bisulfite treatment followed by PCR amplification, methylated and unmethylated alleles can be simultaneously separated in a nondenaturing gel using an automated DNA sequencer. Using bisulfite-SSCP, methylation of hMLH1 was detected in a quantitative manner. This method is not only simple, quick, accurate, and quantitative, but detailed information about methylation is also available with less work. Methylation analysis of large numbers of samples for multiple loci will be facilitated by bisulfite-SSCP.     

Concentrations of108mAg,137Cs,and210Pb in oyster (Crassostrea gigas) on the Japanese coast in relation to the distribution and behavior of radionuclides in sea water

Concentrations of^108mAg,¹³⁷Cs, and²¹⁰Pb in oysters (Crassostrea gigas) were measured for about 10 years on the northeast coast of Japan. Silver-108m was detected in oyster samples collected from an open bay, and its concentrations decreased from the initial value of about 30 mBq/kg fresh in the early 1980s to the value of about 10 mBq/kg fresh in the early 1990s. This decrease could be mainly explained by effects of the ocean current in the early 1980s, and the coastal sea water thereafter, as well as by the advection and diffusion in the ocean. In the nearly-closed bays, concentrations of^108mAg and²¹⁰Pb in oysters were remarkably lower than in the open bays. It suggests that scavenging of silver and lead from the sea water effectively occurred in the nearly-closed bays. In contrast, concentrations of¹³⁷Cs in oysters were similar in the open bays and in the nearly-closed bays.     

An actuated pump on-chip powered by cultured cardiomyocytes

Cellular functions are frequently exploited as processing components for integrated chemical systems such as biochemical reactors and bioassay systems. Here, we have created a new cell-based microsystem exploiting the intrinsic pulsatile mechanical functions of cardiomyocytes to build a cellular micropump on-chip using cardiomyocyte sheets as prototype bio-microactuators. We first demonstrate cell-based control of fluid motion in a model microchannel without check valves and evaluate the potential performance of the bio-actuation. For this purpose, a poly(dimethylsiloxane) (PDMS) microchip with a microchannel equipped with a diaphragm and a push-bar structure capable of harnessing collective cell fluid mechanical forces was coupled to a cultured pulsating cardiomyocyte sheet, activating cell-based fluid movement in the microchannel by actuating the diaphragm. Cell oscillation frequency and correlated fluid displacement in this system depended on temperature. When culture temperature was increased, collective cell contraction frequency remained cooperative and synchronous but increased, while displacement was slightly reduced. We then demonstrated directional fluid pumping within microchannels using cantilever-type micro-check valves made of polyimide. A directional flow rate of nL min(-1) was produced. This cell micropump system could be further developed as a self-actuated and efficient mechanochemical transducer requiring no external energy sources for various purposes in the future.     

Connection between charge fluctuations and the coherent temperature in the heavy-fermion system SmOs4Sb12: a {121, 123}Sb NQR study

We report {121, 123}Sb nuclear quadrupole resonance measurements under pressure in a novel heavy fermion (HF) system SmOs4Sb12. The nuclear spin-spin relaxation rate 1/T{2} exhibits a distinct peak near the coherent temperature of the Kondo effect. The isotope effect of 121Sb and 123Sb indicates that the peak in 1/T{2} is electrical in origin. The connection between the peak in 1/T{2} and the development of coherency of the Kondo effect is robust even under pressure. It is conjectured that charge fluctuation plays an important role in forming the HF state in SmOs4Sb12.     

Linear polarimetry of five comets

We made linear polarimetry of five comets, C/1989 X1 (Austin), 109P/Swift-Tuttle, C/1996 B2 (Hyakutake), C/1995 O1 (Hale-Bopp), and C/1996 Q1 (Tabur) simultaneously at eight wavelengths, in order to study phase angle and wavelength dependence of polarization in continuum light, and polarization behavior of molecular origin.

Polarization in continuum of Swift-Tuttle and Hyakutake were rather high i.e. similar to that of 1P/Halley, while those of Austin and Tabur were low in the positive branch. Hale-Bopp showed the highest polarization ever observed at the corresponding phase angles in the positive branch.

We also made observations scanning across the coma for Hyakutake and Hale-Bopp to investigate polarization structure. For Hale-Bopp, we found: (1) The position of maximum polarization was not at the visible center, and a red part was observed in the central region. (2) Optical properties and/or size spectrum of dust varied in a jet. On the contrary, any peculiar structure was not found for Hyakutake in spite of a much finer spatial resolution. The scanning observation of Hale-Bopp suggests that dust including its size spectrum evolves after the ejection from the nucleus, and that the optical depth in the central region plays an important role.     

Optical properties of fullerene and non-fullerene peapods

Single-wall carbon nanotubes (SWNTs) encapsulating fullerenes, so-called fullerene peapods, were synthesized in high yield by using diameter-selected nanotubes as pods. Transmission electron microscopy revealed high-density fullerene chains inside the nanotubes. X-ray-diffraction measurements indicate 85% filling for C₆₀ and 72% filling for C₇₀ molecules as a total yield. Interestingly, C₆₀ peas do not show any thermal expansion while C₇₀ peas show normal behavior. Room-temperature Raman spectra show one-dimensional photopolymerization of C₆₀ inside nanotubes by blue-laser irradiation, suggesting molecular rotation inside them. In C₇₀ peapods, no photopolymerization was observed but the relative Raman intensity of each peak is different from the C₇₀ 3D crystal. This is probably caused by mixing of two different crystal structures in C₇₀ peas. Furthermore, we synthesized Zn-diphenylporphyrin peapods. Optical absorption and Raman spectra suggest that the encapsulated molecules are deformed by interaction with the SWNT. Received: 12 November 2001 / Accepted: 3 December 2001 / Published online: 4 March 2002     

Doppler-limited spectroscopy of the AΠ1 ← XΣ system of ICl in the 0.8 μm region using a Ti:sapphire ring laser

Doppler-limited vib-rotational absorption spectra of the A ← X electronic transition of I^35/37Cl are measured in the range 11,352-13,507 cm⁻¹ using a Ti:sapphire ring laser. The P-, Q-, and R-branch lines belonging to the v ← v″ = (0-7) ← (0-7) transition in I³⁵Cl and the v ← v″ = (0-6) ← (2-6) transition in I³⁷Cl are assigned. Under Doppler-limited conditions, the P- and R-branch lines are split into doublets by the nuclear quadrupole coupling effect of the I atom. The unperturbed positions of these lines are correctly calculated, whereas splitting in the Q-branch lines was not observed. The mass-reduced Dunham expansion coefficients U_l,m of the A and X states and the spectroscopic constants , and H_v^′ of the A state are determined using a global least-squares fitting procedure.