Identification of tumor vascular antigens by monoclonal antibodies prepared from rat-tumor-derived endothelial cells

An industrial erythromycin production strain of Saccharopolyspora erythraea spp. was used to demonstrate that careful genetic engineering can significantly improve productivity. The chromosomally integrated Vitreoscilla hemoglobin gene (vhb) was shown to enhance the final titer of erythromycin by some 70% compared to the original S. erythraea spp. Overall, specific erythromycin yields were about 2.5 g of erythromycin/g of total protein for S. erythraea::vhb but <1 for the S. erythraea spp. The maximum rates of biosynthesis were 57.5 mg of erythromycin/(L/h) and 24.3 mg/(L/h) for the recombinant strain S. erythraea::vhb and S. erythraea spp., respectively. Overall space-time yield was 100% higher for the S. erythraea::vhb fermentation (1.1 g of erythromycin/(L/day)) than for the S. erythraea spp. fermentation (0. 56 g of erythromycin/(L/day)). The genetic stability of the recombinant strain was high, and no selective pressure was needed throughout the cultivations. Expression of functional Vitreoscilla hemoglobin throughout the cultivations was verified by CO difference spectrum assays.     

Control of Ga doping level in β-FeSi2 using Sn–Ga solvent

We have grown n- and p-type β-FeSi₂ single crystals by the temperature gradient solution growth method using Sn–Ga solvent. The conduction type and the carrier density of the crystals were controlled by the Ga composition in the Sn–Ga solvent. The conduction type was changed from n- to p-type between the Ga composition of 10.2 and 18.5 at% in the solvent. Depending on the Ga composition in the solvent, the carrier density of n- and p-type crystals was changed from 1.5×10¹⁷ to 3×10¹⁷ cm⁻³ and 4×10¹⁷ to 2×10¹⁹ cm⁻³, respectively. The activation energies of n-type crystals were 0.09–0.11 eV while that of p-type crystals were 0.02–0.03 eV.     

Aspartate dehydrogenase in vitamin B12-producing Klebsiella pneumoniae IFO 13541

We found a new reaction of aspartic acid dehydrogenation, catalyzed by NADP(+)-dependent aspartate dehydrogenase, in vitamin B12-producing Klebsiella pneumoniae IFO 13541. The enzyme, which was purified from a crude extract of K.pneumoniae IFO 13541, catalyzes the oxidative deamination of aspartic acid to form oxaloacetic acid. This enzyme had a molecular mass of about 124 kDa consisting of two identical subunits. L-Aspartic acid was a substrate, although D-aspartic acid and L-glutamic acid were inactive. The enzyme showed maximal activity at about pH 7.0-8.0 for the oxidative deamination of L-aspartic acid, and it required NADP+ as a coenzyme, while NAD+ was inactive.     

Hydroboration of diene polymers

Diene polymers (i.e., polyisoprene, polybutadiene, and butadiene—styrene copolymers) were hydroxylated in tetrahydrofuran by hydroboration with diborane and subsequent alkaline oxidative hydrolysis. The strong, broad infrared absorption of the product at 3340 cm^?1 shows the introduction of hydroxyl group. The properties of hydroxylated diene polymers depend upon the extent of hydroxylation. The less hydroxylated polymers are rubbery. As the extent of hydroxylation increases, the product becomes a white thermoplastic which is soluble in alcohol. The hydroboration of diene polymers with diborane is very rapid. However, if the reaction is continued further, the extent of hydroxylation decreases because of side reactions. The results of acetylation and formylation of the hydroxylated products and the grafting of vinyl monomers onto hydroborated diene polymers are also presented.     

Characteristics of a cheese-like food produced by fermentation of the mushroom Schizophyllum commune

Lactate bacteria of the Lactobacillus and Streptococcus genera are normally employed in cheese making because these microbes have potent ability to produce lactate dehydrogenase. A milk-clotting enzyme is also necessary to make cheese. Recently, we discovered that some mushroom genera produce both lactate dehydrogenase and a milk-clotting enzyme. Using the mushroom Schizophyllum commune in place of a lactate bacterium, we produced a cheese-like food that contained about 0.58% beta-D-glucan, which has been shown to have preventive effects against cancer. The food also exhibited thrombosis prevention activity, prolonging the thrombin clotting time to 49.6-fold that of the control.     

Real-time observation for the enzymatic reaction of phospholipid membrane: application of the time-resolved quasi-elastic laser scattering method

An analytical technique to measure reactions in biological membranes was developed and applied to monitoring the hydrolysis reaction of phospholipids (dipalmitoylphosphatidylcholine, DPPC) by phospholipase A(2). The technique uses the time-resolved quasi-elastic laser scattering (TR-QELS) method to measure an oil/phospholipid monolayer/water membrane system by monitoring the change of interfacial tension under a noncontact condition and in real time. When the TR-QELS method is used with the newly developed oil/phospholipid monolayer/water membrane system, measurement of the hydrolysis reaction of phospholipids with long alkyl chains (C >or=16), which are the major components in biological membranes, becomes possible. The reaction progress is monitored by the increase of interfacial tension at the oil/water interface caused by the decrease of surface-active DPPC molecules due to the reaction. The characteristic phases, namely, lag, burst, and equilibrium, are observed. The relationship between the duration of the lag phase (the rate-limiting step of the reaction) and the concentration of calcium ion (an essential cofactor of the reaction) is also investigated. Increase of calcium ion concentration in the subphase is found to shorten the duration of the lag phase. In addition, the real-time measurement simplifies the estimation process for the reaction activation energy.     

Cu-NQR Study on Single Crystals Sr14−x Ca x Cu24O41 with x = 0–11.5

Cu-nuclear quadrupole resonance (NQR) measurements have been performed on single crystals Sr_14–x Ca _x Cu₂₄O₄₁ (Ca _x ) with x = 0–11.5, in order to clarify the relation between the magnetic order around x = 11.5 and local environments at the Cu sites upon x. Cu-NQR frequency _Q for the ladders at 4.2 K increases linearly with increasing x, whereas _Q for the nonmagnetic Zhang–Rice (ZR) sites in the chains does not. Detailed site assignment of the spectra, which are different from those in the previous paper, is presented.     

Thermoresponsive PEG‐Coated Nanotubes as Chiral Selectors of Amino Acids and Peptides

A series of nanotubes with a dense layer of short poly(ethylene glycol) (PEG) chains on the inner surface are prepared by means of a coassembly process using glycolipids and PEG derivatives. Dehydration of the PEG chains by heating increases the hydrophobicity of the nanotube channel and fluorescent‐dye‐labeled amino acids are extracted from bulk solution. Rehydration of the PEG chains by cooling results in back‐extraction of the amino acids into the bulk solution. Because of the supramolecular chirality of the nanotubes, amino acid enantiomers can be separated in the back‐extraction procedure, which is detectable with the naked eye as a change in fluorescence as the amino acids are released from the nanotubes. The efficiency and selectivity of the chiral separation are enhanced by tuning the chemical features and inner diameter of the nanotube channels. For example, compared with wide nanotube channels (8 nm), narrow nanotube channels (4 nm) provide more effective electrostatic attraction and hydrogen bond interaction environments for the transporting amino acids. Introduction of branched alkyl chains to the inner surface of the nanotubes enables chiral separation of peptides containing hydrophobic amino acids. The system described here provides a simple, quick, and on‐site chiral separation in biological and medical fields.     

Application of ER gel with variable friction surface to the clamp system of aerostatic slider

An electro-rheological fluid (ERF) is a functional fluid whose viscoelastic properties vary according to the intensity of the applied electric field. ERFs are mixtures of nonconductive silicone oil and inorganic/organic composite electro-rheological particles. The properties of ERFs have been exploited to control the performance of machine elements. ERFs have been applied to machine elements such as variable dampers and clutches. However, ERFs have disadvantages, namely the sedimentation of ER particles and the requirement of a seal mechanism. The sedimentation of ER particles reduces the ER effects and results in low stability of ER devices. In order to suppress the sedimentation, and thereby improve the performance of ERF devices, a new functional material called the gel-structured ERF (ERG) is developed, whose basic properties are analyzed in this study. The ER particles are suspended in the gel component, and thus will not precipitate out. This suppresses the decrease in the ER effect caused by precipitation. The ERG developed shows a large shear stress variation in response to the applied electric field. This high performance of ERG originates in a mechanism different from the ER effects of ERF. In order to elucidate the mechanism in ERG, the behavior of ER particles was observed under an electric field. The results show that the contact conditions at the interface between electrode and ERG change rapidly in response to the applied electric field, which result in a variation in shear force. On the basis of the results of a preliminary analysis, ERG was applied to the precision clamp system of an aerostatic slider, and its performance was assessed experimentally.