[en] The calmodulin (CaM) content of fully intact frog rod outer segments (ROS) has been measured using radioimmunoassay. The molar ratio between rhodopsin and total CaM in ROS is 800:1. In the absence of Ca²⁺, the ROS membrane fraction contains only 4% of total ROS CaM. In contrast, in the presence of Ca²⁺, 15% of total ROS CaM is found in the membrane fraction. For half-maximal binding of CaM to CaM-depleted ROS membranes, 3 x 10^-7 M Ca²⁺ is required. This CaM binding is inhibited by trifluoperazine. CaM binding proteins in the ROS membrane fraction are identified by using two different methods: the overlay method and the use of 3,3'-dithiobis(sulfosuccinimidyl propionate) (DTSSP), a bifunctional cross-linking reagent. Ca²⁺-dependent CaM binding proteins with apparent molecular weights of 240,000, 140,000, 53,000, and 47,000 are detected in the ROS membrane fraction by the overlay method. Anomalous, Ca²⁺-independent CaM binding to rhodopsin is also detected with this method, and this CaM binding is inhibited by the presence of Ca²⁺. With the bifunctional cross-linking reagent, DTSSP, three discrete proteins with molecular weights of 240,000, 53,000, and 47,000 are detected in the native ROS membrane fraction. CaM binding to rhodopsin is not detected with this method. These data suggest that both the Ca²⁺-independent binding of CaM to rhodopsin and the Ca²⁺-dependent binding of CaM to the M/sub r/ 140,000 protein represent binding of CaM to a site(s) which is (are) exposed only after denaturation. Ca²⁺-dependent CaM binding in the cytoplasmic fraction is also evaluated with the overlay method. These data suggest that CaM and its binding proteins participate in the regulation of Ca²⁺-sensitive processes primarily on the ROS disk membranes

[en] Homomolecular oxygen isotopic exchange reactions at -196 or -193⁰C have been observed on several oxides such as ZnO, ZnO/Al₂O₃, and TiO₂. This communication shows that the ZnS surface also brings about isotopic equilibration of oxygen at liquid nitrogen temperature, which may be the first observation of this unique exchange reaction over a catalyst other than oxides

[en] Full text:As one of the methods for analyzing reflection-multilayer structures, standing-wave observation by total electron yield (TEY) X- ray standing wave(XSW) method has been proposed. Reported XSW-peaks depend on the reflection peaks, but the origin of the peak profile has been unknown: the energy position of the XSW- peak is different from that of the reflection peak, and the XSW- peak shows the asymmetric shape. In the present study, Mo/Si multilayers with various thicknesses of the top Mo layer were fabricated, and reflectance and TEY- XSW spectra were measured at the BL-12A, PF, with a Be filter. Upper part of the right figure is one of the measured reflectance, and the lower part is the measured TEY-XSW spectra. Photon energies of the TEY-XSW spectra are calribrated by the reflection- peak positions measured at the same time. The energy positions of the XSW peaks in the TEY-XSW spectra shift as the thickness increase of the top Mo layer. The shift shows that XSW-peak depends on the phase of the XSW excited in the top Mo layer. This dependence will be the origin of the unknown peak profile

[en] In illuminated rod outer segment membranes, GTP and guanosine 5'-[ß, ß-imido]triphosphate (p[NH]ppG) have reciprocal effects on cGMP phosphodiesterase (PDEase; 3':5'-cyclic-nucleotide 5'-nucleotidohydrolase, EC 3.1.4.17) activity and cGMP binding to noncatalytic sites on that enzyme. Two micromolar p[NH]ppG increased PDEase activity more than 2-fold while inhibiting cGMP binding more than 40%. Reduction of noncatalytic cGMP binding, which followed addition of p[NH]ppG, was not a result of PDEase activation. Both effects of p[NH]ppG were completely dependent on the presence of bleached rhodopsin. A heat-stable factor has been found to inhibit PDEase activity and also to stimulate cGMP binding to noncatalytic cGMP binding sites. Addition of p[NH]ppG reversed the effects of this factor on both PDEase activity and cGMP binding. During purification of this material, the activity peaks for both PDEase inhibition and activation of noncatalytic cGMP binding comigrated on both Blue Sepharose CL-6B column chromatography and sucrose density gradients centrifugation, suggesting that the same factor could be responsible for both inhibition of PDEase activity and enhancement of noncatalytic cGMP binding. Limited tryptic proteolysis of PDEase, which markedly reduced cGMP binding to the noncatalytic sites, and experiments using highly purified cAMP (free of cGMP) as substrate for PDEase showed that the binding of cGMP to noncatalytic sites was not required for the heat-stable inhibitory factor to inhibit PDEase activity. We discuss possible relationships between the regulation of PDEase and the binding of cGMP to noncatalytic sites

No abstract available

No abstract available

[en] Development of an effective, high-power, low-cost, artificial light source for use in plant-growing facilities would be very beneficial for plant production. Recently, the laser-diode lamp was proposed as a new type of light source for plant production. The advantages of the laser-diode lamp over conventional light sources are its high electrical-to-optical power conversion efficiency, low thermal radiation, easy set-up for high power and pulse irradiation, small weight and small volume for mounting, and selectivity for proper wavelength. Because laser light itself differs from the light sources presently used in plant growing, we confirmed the possibility of growing plants under the laser-diode light using lettuces. Lettuce seedlings with 5-6 leaves were grown under a laser-diode lamp panel with 30 pieces of high-power and high-efficiency AlGaInP laser-diodes. The power of each laser-diode lamp was 500 mW, and the wavelength was 680 nm, which was efficient for photosynthesis. The lettuce plants were able to grow under the laser-diode light. However, plants were lighter and had thinner leaves than those grown under high-pressure sodium lamps. (author)

[en] Light initiates a series of biochemical and biophysical changes in vertebrate rod outer segments (ROS). A variety of studies have indicated that several discrete biochemical steps occur between photon capture and the subsequent change in rod membrane voltage. Cyclic GMP is a possible candidate for a transmitter molecule in the photon transduction process. Electrophysiological studies have indicated that iontophoresis of cyclic GMP into dark adapted rods is accompanied by a reduction in plasma membrane voltage (33). Characterization of rod phosphodiesterase (PDE) indicates a large turnover number and rapid rates of activation following illumination, which are compatible with a role of cyclic GMP in the (approximately 100 msec) time span for visual excitation. An attractive hypothesis assigns a transmitter role to disc Ca²⁺ and is supported by many intriguing experiments. There is, however, still disagreement concerning the effect of cyclic GMP on rod Ca²⁺ dynamics. These and other studies have suggested that light regulation of PDE plays an important role either in support of transduction or in support of light adaptation or the regulation of photoreceptor sensitivity. Work has continued to focus on elaboration of the mechanism for the light activation of ROS PDE. In the following section, the authors briefly review the current understanding of the activation mechanism and describe some newer findings now emerging from our ongoing studies

[en] The preparation of H^-acceleration by 930 AVF cyclotron, for multipurpose utilization of neutron beam, is now being implemented at Cyclotron and Radioisotope Center (CYRIC), Tohoku Univ. After some preparations such as negative ion source, magnet field reversing of cyclotron and initial beam line and carbon foil for beam extraction, we started H^- acceleration and extraction test. Recently we accomplished extraction of accelerated proton beam with carbon foil electron stripper at 90 percent efficiency. (author)

[en] Zn⁺ or both Zn⁺ and O⁺ ions were implanted in porous anatase TiO₂ films prepared by sol-gel method and subsequently annealed in N₂ or O₂ atmosphere. The results were compared with that obtained after Ar⁺ ion implantation and subsequent annealing. The samples were evaluated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron diffraction (ED) and X-ray diffraction (XRD). Optical absorption and electronic states were characterized by photothermal deflection spectrometry (PDS) and electron energy loss spectrometry (EELS). The porous film was densified by Zn⁺ ion implantation up to the ion penetration depth. After the subsequent annealing at 800 deg. C the phase transformation from anatase to rutile accompanied with grain growth up to the film thickness was observed. In addition, the phase transformation was not induced by the annealing up to 800 deg. C with or without preceding Ar⁺ ion implantation. Thus, the implanted impurity Zn assisted the phase transformation. Annealing in O₂ tends to reduce the rate of phase transformation and create ZnTiO₃. Optical absorption above the photon energy of 2.9 eV was increased remarkably by the Zn⁺ or Zn⁺ and O⁺ ion implantation and subsequent annealing. EELS spectra of the Zn⁺ implanted and annealed sample is consistent with the results of PDS. The change in the optical absorption above 2.9 eV is due to the phase transformation