New monitoring approach for metabolic dynamics in microbial ecosystems using stable-isotope-labeling technologies

We have developed a new approach for monitoring the metabolic dynamics in microbial ecosystems using a combination of DNA fingerprinting and metabolome analysis based on stable-isotope-labeling technologies. Stable-isotope probing of DNA (DNA-SIP) has been used previously for the evaluation of cross-feeding in microbial communities. For the development and validation of our monitoring approach, fecal microbiota were analyzed with stable-isotope-labeled glucose used as the sole carbon source. In order to link the metabolic information and the microbial variability, we performed metabolic–microbial correlation analysis based on nuclear magnetic resonance (NMR) profiles and denaturing gradient gel electrophoresis (DGGE) fingerprints, which successfully identified the glucose-utilizing bacteria and their related extracellular metabolites. Moreover, our approach revealed information regarding the carbon flux, in that the “first” wave of extracellular metabolites secreted by the glucose-utilizing bacteria were incorporated into the “secondary” group of substrate-utilizing bacteria, and that this “secondary” group further produced their own secondary metabolized substrates. Thus, this approach is a powerful tool for monitoring the metabolic dynamics in microbial ecosystems and allows for the tracking of the carbon flux within a microbial community.     

1.3-μm continuous-wave lasing operation in GaInNAs quantum-welllasers

A 1.3-μm continuous wave lasing operation is demonstrated, for the first time, in a GaInNAs quantum-well laser at room temperature. This lasing performance is achieved by increasing the nitrogen content (up to 1%) in GaInNAs quantum layer. It is thus confirmed that this type of laser is suitable for use as a light source for optical fiber communications     

Electromigration of sodium ions and electro-osmotic flow in water-saturated, compacted Na-montmorillonite

Sodium ions spiked with ²²Na as a tracer were migrated by electromigration and electro-osmosis in the water-saturated compacted Na-montmorillonite at dry densities 1.0×10³ kg m⁻³, under an electric potential gradient. Dissolved helium was also migrated by electro-osmosis in the montmorillonite. After migration, concentration profiles of the sodium ions and helium were obtained by γ-spectrometry and mass-spectrometric methods, respectively. From the profiles of both chemical species, not only migration due to electrokinetic phenomena but also mechanical dispersion was observed in the montmorillonite. The dispersion coefficients, D_i, and apparent migration rates, U_i^a, of ²²Na and helium were found in the compacted Na-montmorillonite at 1.0×10³ kg m⁻³. The migration of helium in the montmorillonite under an electric potential gradient reflects that of water because helium migrates as an electrically neutral species. The parameters D_He^m, U_He^a, and α_He correspond to those of water. The mechanical dispersion coefficients, D_Na^m, of ²²Na⁺ ions are much smaller than those of water obtained by helium. The dispersivity parameters, α_Na, for ²²Na⁺ obtained from these D_Na and U_Na^a values are 10⁻⁵ m and those for water (α_He) are 10⁻³ m. This indicates that ²²Na⁺ ions migrate in different spaces than water in the compacted montmorillonite under a potential gradient. This finding suggests that the migration of Na⁺ ions occurs in the interlayer and/or on the outer surfaces of the montmorillonite; whereas dissolved helium migrates in the pore water.     

GaInNAs-GaAs long-wavelength vertical-cavity surface-emitting laserdiodes

Vertical-cavity surface-emitting laser diodes with GaInNAs-GaAs quantum-well (QW) active layers are demonstrated for the first time. GaInNAs permits the realization of a long-wavelength vertical-cavity laser grown directly on a GaAs substrate. Room-temperature (RT) pulsed operation is achieved, with an active wavelength near 1.18 μm, threshold current density of 3.1 kA/cm², slope efficiency of ~0.04 W/A, and output power above 5 mW for 45-μm-diameter devices. Laser oscillation is observed for temperatures at high as 95°C     

Effect of Time-Dependent Humidity Profiles from Air to Superheated Steam on Drying of a Wetted Starch Sphere

The effects of air humidity when drying with superheated steam (SHS) were examined considering displacement by SHS. A wetted raw starch sphere (ball) was used as the model material. It was found that the humidity profile strongly affects the mass change and properties of the products. The material became porous when it was dried with pure SHS from start to finish, which differs both from products dried with high-humidity air alone, and from products dried with air followed by SHS within a few minutes. A prediction method for adiabatic saturation temperature over a wide range of humidity is also proposed.     

Highly hydrogenated dietary soybean oil modifies the responses to polychlorinated biphenyls in rats

The effects of dietary highly hydrogenated soybean oil (HSO) upon the changes caused by dietary polychlorinated biphenyls (PCBs) were examined in rats. Six groups of rats were fed the following diets for 30 d: a 20% soybean oil-containing diet (control diet), a diet in which a half of soybean oil was substituted with HSO (HSO-A diet), a diet in which cellulose powder was replaced with HSO (HSO-B diet) and these diets supplemented with 100 ppm PCBs (control+PCBs, HSO-A+PCBs and HSO-B+PCBs diets). Hepatic concentration of PCBs and relative liver weight were markedly decreased in rats fed with the HSO-A+PCBs diet compared with those fed with the other diets containing PCBs. Liver lipids and liver cholesterol were considerably decreased with a reciprocal increase in fecal sterol excretion by rats fed the HSO-A+PCBs and the HSO-B+PCBs diets compared with those fed with the control+PCBs diet. The fatty acid composition in hepatic phospholipids showed an independent increase of the saturated fatty acid content induced by dietary HSO and PCBs. Dietary PCBs also caused decreases in the amounts of monounsaturated and n-3 polyunsaturated fatty acids. These results suggest that dietary HSO prevents accumulation of PCBs in the liver and promotes the excretion of lipids stimulated by PCBs, accompanied by a change in fatty acid metabolism.     

Cell interaction study of amyloid by using luminescent conjugated polythiophene: implication that amyloid cytotoxicity is correlated with prolonged cellular binding

Needles and noodles: Studying amyloid toxicity is important for understanding protein misfolding diseases. Using a luminescent conjugated polythiophene, we found that cell binding of nontoxic filamentous amyloids of insulin and β2-microglobulin was less efficient than that of toxic fibrillar amyloids; this suggests a correlation between amyloid toxicity and cell binding.