NMR and ICP spectroscopic analysis of the DNA-binding domain of the Drosophila GCM protein reveals a novel Zn2+-binding motif

Drosophila GCM (glial cell missing) is a novel DNA-binding proteinthat determines the fate of glial precursors from the neuraldefault to glia. The GCM protein contains the functional domainthat is essential for recognition of the upstream sequence ofthe repo gene. In the DNA-binding region of this GCM protein,there is a cysteine-rich region with which divalent metal ionssuch as Zn²⁺ must bind and other proteins belonging to the GCMfamily have a corresponding region. To obtain a more detailedinsight into the structural and functional features of thisDNA-binding region, we have determined the minimal DNA-bindingdomain and obtained inductively coupled plasma atomic emissionspectra and ¹H–¹⁵N, ¹H–¹⁵N–¹³C and ¹¹³Cd²⁺NMR spectra, with or without its specific DNA molecule. Consideringthe results, it was concluded that the minimal DNA-binding domainincludes two Zn²⁺-binding sites, one of which is adjacent tothe interface for DNA binding. Systematic mutational analysesof the conserved cysteine residues in the minimal DNA-bindingdomain revealed that one Zn²⁺-binding site is indispensablefor stabilization of the higher order structure of this DNA-bindingdomain, but that the other is not.     

Diffusion mechanism of direct dyes into a cellulose membrane: The structural effect of direct dyes on the adsorption rate

The transport of three typical direct dyes, C.I. Direct Yellow 12, C.I. Direct Red 2, and C. I. Direct Blue 15, into a cellulose membrane has been studied at 55°C. Sodium chloride was used as a stimulator for dyeing. The effects of the concentration of the stimulator on the adsorption isotherms, the adsorption rate, and the concentration profiles in the membrane were tested. The experimental adsorption rates of three dyes were quite different. The diffusion mechanism of the dyes into a cellulose membrane was analyzed on the basis of the parallel transport equation of surface and pore diffusion as developed in our previous paper. The experimental uptake curves showed good agreement with the theoretical curves for surface diffusion control. Experimental concentration profiles also agreed reasonably well with the theoretical lines for surface diffusion control rather than pore diffusion control. The surface diffusivities of three dyes were quite different and nearly independent of the adsorbed phase concentration of the dye.     

Lipid peroxidation in low density lipoproteins from human plasma and egg yolk promotes accumulation of 1-acyl analogues of platelet-activating factor-like lipids

Oxidative modification of low density lipoprotein (LDL) is known to be a key event for induction of atherosclerosis. However, there has been little progress in structural elucidation of oxidized lipids, especially oxidatively fragmented phospholipids retaining a glycerol backbone. In this study, we found that LDL derived from egg yolk has no platelet-activating factor (PAF) acetylhydrolase activity, and that prolonged incubation of egg yolk LDL with Cu²⁺ resulted in the formation of various PAF-like lipids: 1-acyl type phosphatidylcholines with ansn-2-short-chain dicarboxylate or monocarboxylate group. Only a very small amount of the PAF-like lipid having ansn-2-short-chain monocarboxylate group was detected by gas chromatography-mass spectrometry in Cu²⁺-oxidized LDL from human plasma with high PAF-acetylhydrolase activity, which has been reported to hydrolyze PAF-like lipids to lysophosphatidylcholines. Preincubation of plasma LDL with diisopropyl fluorophosphate dose-dependently inhibited PAF-acetylhydrolase activity, resulting in accumulation of the PAF-like lipids when the LDL was oxidized with Cu²⁺. As well as PAF and lysophosphatidylcholines, several PAF-like lipids were found to inhibit [³H]thymidine incorporation into cultured vascular smooth muscle cells derived from rat aorta. The possible formation of PAF-like lipids by lipid peroxidation in LDL is discussed as well as its possible significance for induction of atherosclerosis.     

Quasi-blazed type multilayer zone plate for X-rays

In order to attain high diffraction efficiency in high-energy X-ray region, we have developed multilevel-type (6-step) multilayer FZPs with the diameter of 70 μm, which composed of concentric multilayers of alternating high-Z (Cu), low-Z (Al), and four types of composite materials (Cu, Al) layers. Such a multilevel-type FZP with high diffraction efficiency contributes the reduction of the radiation damage to biological specimens, the simplification of the X-ray optical system. Some FZPs are fabricated and their diffraction efficiencies were evaluated at the beamline of SPring-8. For one FZP, the peak efficiency for the 1st-order diffraction of 51% has been obtained at 70 keV. The efficiencies higher than 40% have been achieved in the wide energy range of 70-90 keV. That for the 2nd-order diffraction of 46% has been obtained at 37.5 keV. For another FZP, the peak efficiency for the 1st-order diffraction of 52% has been obtained at 41.3 keV. The efficiencies higher than 45% have been achieved in the wide energy range of 33-49.5 keV.     

Formation of organic iodine supplied as iodide in a soil-water system in Chiba, Japan

Speciation of iodine in a soil-water system was investigated to understand the mechanism of iodine mobility in surface environments. Iodine speciation in soil and pore water was determined by K-edge XANES and HPLC-ICP-MS, respectively, for samples collected at a depth of 0-12 cm in the Yoro area, Chiba, Japan. Pore water collected at a 0-6 cm depth contained 50%-60% of organic iodine bound to dissolved organic matter, with the other portion being I(-). At a 9-12 cm depth, 98% of iodine was in the form of dissolved I(-). In contrast, XANES analysis revealed that iodine in soil exists as organic iodine at all depths. Iodine mapping of soil grains was obtained using micro-XRF analysis, which also indicated that iodine is bound to organic matter. The activity of laccase, which has the ability to oxidize I(-) to I(2), was high at the surface of the soil-water layer, suggesting that iodide oxidizing enzymes can promote iodine organification. The distribution coefficient of organic iodine in the soil-water system was more than 10-fold greater than that of iodide. Transformation of inorganic iodine to organic iodine plays an important role in iodine immobilization, especially in a surface soil-water system.     

What information should be provided in communications on biomass power generation?

In order to promote the production and use of electricity generated from renewable energy sources, support schemes such as the Renewables Portfolio Standard and various green power programs have been implemented. When evaluating the costs and benefits associated with those schemes, people need accurate information about the characteristics of renewable generation. The objective of the present paper is to identify the kind of information to be provided to lay people in Japan in order to enhance their understanding of biomass generation. We used the two-stage “mental model” method to conduct open-ended interviews and a questionnaire survey to reveal people’s beliefs about biomass generation. From the survey results, it was identified that the information to be provided should include the following: (a) definitions of biomass and biomass generation, (b) specific generation technologies, (c) the carbon neutral concept of biomass, (d) non-use of energy food crops in Japan, (e) sustainable availability of resources under certain conditions, and (f) high generation costs with their causes, such as collection costs of resources.     

One Week of CDAHFD Induces Steatohepatitis and Mitochondrial Dysfunction with Oxidative Stress in Liver

The prevalence of nonalcoholic fatty liver disease (NAFLD) has been rapidly increasing worldwide. A choline-deficient, L-amino acid-defined, high-fat diet (CDAHFD) has been used to create a mouse model of nonalcoholic steatohepatitis (NASH). There are some reports on the effects on mice of being fed a CDAHFD for long periods of 1 to 3 months. However, the effect of this diet over a short period is unknown. Therefore, we examined the effect of 1-week CDAHFD feeding on the mouse liver. Feeding a CDAHFD diet for only 1-week induced lipid droplet deposition in the liver with increasing activity of liver-derived enzymes in the plasma. On the other hand, it did not induce fibrosis or cirrhosis. Additionally, it was demonstrated that CDAHFD significantly impaired mitochondrial respiration with severe oxidative stress to the liver, which is associated with a decreasing mitochondrial DNA copy number and complex proteins. In the gene expression analysis of the liver, inflammatory and oxidative stress markers were significantly increased by CDAHFD. These results demonstrated that 1 week of feeding CDAHFD to mice induces steatohepatitis with mitochondrial dysfunction and severe oxidative stress, without fibrosis, which can partially mimic the early stage of NASH in humans.     

Non-destructive monitoring of creaming of oil-in-water emulsion-based formulations using magnetic resonance imaging

A non-destructive method for monitoring creaming of emulsion-based formulations is in great demand because it allows us to understand fully their instability mechanisms. This study was aimed at demonstrating the usefulness of magnetic resonance (MR) techniques, including MR imaging (MRI) and MR spectroscopy (MRS), for evaluating the physicochemical stability of emulsion-based formulations. Emulsions that are applicable as the base of practical skin creams were used as test samples. Substantial creaming was developed by centrifugation, which was then monitored by MRI. The creaming oil droplet layer and aqueous phase were clearly distinguished by quantitative MRI by measuring T₁ and the apparent diffusion coefficient. Components in a selected volume in the emulsions could be analyzed using MRS. Then, model emulsions having different hydrophilic–lipophilic balance (HLB) values were tested, and the optimal HLB value for a stable dispersion was determined. In addition, the MRI examination enables the detection of creaming occurring in a polyethylene tube, which is commonly used for commercial products, without losing any image quality. These findings strongly indicate that MR techniques are powerful tools to evaluate the physicochemical stability of emulsion-based formulations. This study will make a great contribution to the development and quality control of emulsion-based formulations.     

Synapses on the mauthner cell of the goldfish: Thin section,freeze-fracture,and immunocytochemical studies

Large myelinated club ending and small-vesicle bouton synapses on the distal part of the lateral dendrite of the goldfish Mauthner cell were investigated with thin section, freeze-fracture, and immunocytochemical electron microscopic methods. Large myelinated club endings form mixed synapses, having both gap junctions and chemical synaptic junctions. The correlation of the number of gap junction particles (connexons) and the data from electrophysiological studies of single large myelinated club ending synapses suggest that only a small fraction of gap junction channels are open at any given time during electrical synaptic transmission. The chemical synaptic junctions at the large myelinated club ending synapse have large, round synaptic vesicles, indicating that they are excitatory. This result is in agreement with electrophysiological data demonstrating the excitatory nature of this chemical synapse. Freeze-fracture of these excitatory chemical synaptic junctions reveals the presence of the intramembrane particle aggregates in the postsynaptic E face. Small-vesicle boutons form chemical synaptic junctions with small, flat or oval synaptic vesicles. These structural data, in combination with previous electrophysiological studies, suggest that the small-vesicle bouton synapses are inhibitory. In support of this theory, the cytoplasmic side of the postsynaptic membrane of some of these synapses show positive immunocytochemical reaction to monoclonal antibodies against the rat glycine receptor. Freeze-fracture data reveal intramembrane particle aggregates in the postsynaptic P face of some small-vesicle bouton synapses which could possibly represent glycine receptor aggregates.