Klebsormidium flaccidum genome reveals primary factors for plant terrestrial adaptation.

The colonization of land by plants was a key event in the evolution of life. Here we report the draft genome sequence of the filamentous terrestrial alga Klebsormidium flaccidum (Division Charophyta, Order Klebsormidiales) to elucidate the early transition step from aquatic algae to land plants. Comparison of the genome sequence with that of other algae and land plants demonstrate that K. flaccidum acquired many genes specific to land plants. We demonstrate that K. flaccidum indeed produces several plant hormones and homologues of some of the signalling intermediates required for hormone actions in higher plants. The K. flaccidum genome also encodes a primitive system to protect against the harmful effects of high-intensity light. The presence of these plant-related systems in K. flaccidum suggests that, during evolution, this alga acquired the fundamental machinery required for adaptation to terrestrial environments.

Arabidopsis mutants affecting oxylipin signaling in photo-oxidative stress responses.

Plant oxylipins derive from oxygenation of polyunsaturated fatty acids in thylakoid membranes and oxylipins such as jasmonic acid (JA) and 12-oxo-phytodienoic acid (OPDA) play important roles in adaptation to photo-oxidative stress. OPDA functions both as a JA precursor and as a biologically active signaling molecule that induces expression of a specific set of genes. These genes can be induced by OPDA in the JA-insensitive coronatine insensitive1 (coi1) mutant, suggesting that there is an alternative pathway for OPDA signaling, independent of COI1-dependent JA signaling. However, little is known about OPDA signaling in photo-oxidative stress responses. In this study, we isolated Arabidopsis mutants with constitutively enhanced expression from the OPDA-responsive HsfA2 promoter. We used deletion mapping and complementation analysis to identify one responsible gene as CATALASE2. Our results thus indicate that ROS-producing cellular metabolism links to OPDA signaling.

Propagation and stability characteristics of a 500-m-long laser-based fiducial line for high-precision alignment of long-distance linear accelerators.

A laser-based alignment system with a He-Ne laser has been newly developed in order to precisely align accelerator units at the KEKB injector linac. The laser beam was first implemented as a 500-m-long fiducial straight line for alignment measurements. We experimentally investigated the propagation and stability characteristics of the laser beam passing through laser pipes in vacuum. The pointing stability at the last fiducial point was successfully obtained with the transverse displacements of ±40 µm level in one standard deviation by applying a feedback control. This pointing stability corresponds to an angle of ±0.08 µrad. This report contains a detailed description of the experimental investigation for the propagation and stability characteristics of the laser beam in the laser-based alignment system for long-distance linear accelerators.

[Setting of the soft X-ray field for the calibration of the dosimeters used in mammographic field].

In order to produce a cheap and stable X-ray generator system for calibration of dosimeters used in mammographic field, a dummy source of mammographic X-ray was developed using a tungsten (W) target X-ray tube and a molybdenum (Mo) filter. The photon fluence spectra of mammographic equipment were calculated using Birch's formula and aluminum (Al) attenuation curves were derived. The Al attenuation curves of X-rays from W target with Mo filter of various thicknesses were similarly obtained. Comparing the similarities of attenuation curves, the best fit Mo filter thickness was chosen. Consequently, a 0.04 mm thick Mo plus a 4 mm thick poly-methylmethacrylate filter were chosen to be added to W target industrial X-ray tube. The similarity of Al attenuation curves were verified by ionization chamber measurements.

Experimental investigation on focusing characteristics of a He-Ne laser using circular Fresnel zone plate for high-precision alignment of linear accelerators.

We experimentally investigate the focusing characteristics of a He-Ne laser at the focal region for the high-precision alignment of long-distance linear accelerators using a circular Fresnel zone plate. The laser wave passing through the Fresnel zone plate having a focal length of 66.7 m propagates for a 268-m-long distance at atmospheric pressure. A new laser-based alignment system using Fresnel zone plates as the alignment targets is discussed. The transverse displacement of the focused spot of the laser is measured as a function of the displacement of the target by a detector installed at the focal point. Systematic studies on the focusing characteristics and alignment precision have been successfully conducted in this experiment. The experimental results are in good agreement with theoretical calculations, and the alignment precision of the target is determined to be less than ±30 µm. In this study, we perform a detailed experimental investigation on the laser propagation and focusing characteristics using the circular Fresnel zone plate at the focal region along with theoretical calculations.

Synthetic studies on maitotoxin. 3. Stereoselective synthesis of the BCDE-ring system.

The stereoselective synthesis of the BCDE-ring system of maitotoxin has been accomplished through a two-directional strategy for the construction of polycyclic ether. The key reactions involve SmI 2-induced double cyclization of a beta-alkoxyacrylate and a double dihydroxylation for construction of the B- and E-rings.

Electrically driven motion of an air bubble on hemispherical oil/water interface by three-phase boundary reactions.

Our electrochemical cell consisted of a ferrocene-included hemispherical nitrobenzene (NB) droplet on the glassy carbon (GC) electrode which was immersed in the aqueous solution including sodium sulfate and sodium dodecyl sulfate (SDS). When an air bubble was injected near the boundary between the oil and the aqueous phase, it stayed at the top of the hemisphere on the boundary so that the lower half of the bubble was put in oil and the other half was in water. From the force balance of surface tension and buoyancy of the bubble, the bubble took an energetic minimum at the interface. It sank into the oil phase when ferrocene in the oil was electrochemically oxidized through the GC electrode by the three-phase boundary reaction. The electrochemical reduction caused the bubble to move back toward the aqueous phase. The motion of the bubble was synchronized with the redox reaction of ferrocene. The potential step oxidation showed such a rapid response that the motion could not be attributed to diffusion of ferricenium ion from the three-phase boundary to the bubble. Our idea of explaining the rapidity was the translational motion of the SDS layer along the boundary, which was driven by the difference in the surface concentration of SDS caused by the electrochemical generation of the ferricenium ion. The motion of the SDS layer was demonstrated by the shrinkage of the oil layer spread on the water surface when SDS solution was dropped on the oil layer. The spreading velocity was close to the velocity of propagating the oxidation of ferrocene to the bubble.

Performance comparison of neutron and X-ray sensitive photo-stimulated imaging plates.

Statistical characteristics of photo-stimulated luminescent (PSL) signals are studied using thermal neutrons, X- and gamma-rays. It is shown that the statistical fluctuation of PSL is described simply by the PSL value itself and is independent of radiation type, except for short-range high-LET particles. However, it is expected that the spatial resolution should be affected if the range of electrons or secondaries were much longer than the instrumental resolution (pixel size). When output PSL signals are compared between X- and gamma-rays, the PSL values were proportional to the exposed air dose, independent of X-ray energy. However, signals from 60Co gamma-rays were approximately 1% of 22-40 kV X-ray output at the same dose.