Induction of Light Dependent Pyruvate Transport into Chloroplasts of Mesembryanthemum crystallinum by Salt Stress

Mode of photosynthesis in Mesembryanthemum crystallinum changesfrom C₃ to Crassulacean acid metabolism (CAM) when the plantswere stressed with high salinity. [¹⁴C]Pyruvate uptake for 30s into intact chloroplasts isolated from leaves of the CAM modeof M. crystallinum was enhanced more than 5-fold in the lightcompared with that in the dark. The stromal concentration ofpyruvate in the light reached to more than 2.5 times of themedium. In contrast, little or no pyruvate uptake occurred inchloroplasts from C₃ leaves in either light or dark condition.The initial uptake rate (10 s incubation at 4°C) into theCAM chloroplasts in the light was about 3-fold higher than therate in the dark. K_m and V_max of the initial uptake in the lightwere 0.54 mM and 8.5 µmol (mg Chl)^–1 h^–1 respectively.These suggest that pyruvate was actively incorporated into theCAM chloroplasts against its concentration gradient across theenvelope in the light. When hydroponically grown M. crystallinumwere stressed by 350 mM NaCl, the capacity of chloroplasts forpyruvate uptake was induced in 6 d corresponding to the inductionof the activities of PEP-carboxylase and NAD(P)⁺-malic enzymesin response to salt stress. (Received October 12, 1995; Accepted January 19, 1996)     

The effect of rebamipide on gastric xanthine oxidase activity and type conversion in ethanol-treated rats

Rebamipide, a novel antipeptic ulcer drug, 2-(4-chlorobenzoylamino)-3-[2(1H)-quinolinone-4-yl]-propionic acid, was studied for its inhibitory effect on gastric xanthine oxidase activity and type conversion of the enzyme that has a profound role in free radical generation. Intraperitoneal administration of rebamipide at 60 mg/kg body weight reduced gastric mucosal hemorrhagic lesions and lipid peroxidation, which was proportional to the inhibitory effect of rebamipide on alcohol-induced xanthine oxidase-type conversion and enzyme activity. It was also observed that the activity of xanthine oxidase was significantly inhibited by administration of rebamipide at 60 mg/kg body weight, leading to a significant reduction of lipid peroxide content in alcohol-treated rats. The results suggest that alcohol-induced gastric mucosal lesions might be, in part, due to the increased activity of xanthine oxidase and type conversion rate of the enzyme and the protective effect of rebamipide on gastric mucosal lesions would result from its ability to protect against oxidative stress on gastric mucosal lesions of alcohol-treated rats.     

Galacto-oligosaccharide production byβ-galactosidase in hydrophobic organic media

Summary Production of galacto-oligosaccharide (GO), including trisaccharide and tetrasaccharide, was performed using a -galactosidase in water-hydrophobic solvent mixtures. A maximum GO concentration of 45% (w/w) was attained in a 95% cyclohexane/5% water mixture from a 55% (w/w) of lactose at 60°C and pH 6.0, while a maximum of 38% GO in aqueous media. GO production decreased with an increase in surfactant concentration. The optimum water content for GO production showed a broad range from 2.5 to 10% (v/v). Solvent properties, such as log P and the dipole moment, had no relation to GO production.     

Expression of human factor X with normal biological activity in human embryonic kidney cells

Summary Human embryonic kidney cells (293) were transfected with a construct containing human factor X cDNA and selected for G418 resistance. The level of expression of recombinant factor X in serum-free medium was 4 to 5 g/ml. Purified recombinant factor X had a molecular size identical to that of normal plasma factor X. Amino-terminal sequencing revealed normal processing cleavages. The -carboxy Glu and -OH Asp content of the recombinant factor X was close to 90% of the expected levels of these post-translational residues. The specific activity of recombinant factor X was about 95% of that of plasma factor X in three plasma-based clotting assays. This report demonstrates that 293 cells can produce a high level of biologically active factor X and describes a visual criterion for verifying the transfection process.Abbreviations FX factor X - rFX recombinant factor X - DMEM Dulbecco's modified Eagle's medium - RVV-X Russell's viper venom - SDS-PAGE sodium dodecyl sulfatepolyacrylamide gel electrophoresis - Gla -carboxy glutamic acid     

Localization of a New Type of X-Linked Liver Glycogenosis to the Chromosomal Region Xp22 Containing the Liver α-Subunit of Phosphorylase Kinase (PHKA2)

We describe here a new type of X-linked liver glycogen storage disease. The main symptoms include liver enlargement and growth retardation. The clinical and biochemical abnormalities of this glycogenosis are similar to those of classical X-linked liver glycogenosis due to phosphorylase kinase deficiency (XLG). However, in contrast to patients with XLG, the patients described here have no reduced phosphorylase kinase activity in erythrocytes and leukocytes, and no enzyme deficiency could be found. Linkage analysis of four families with this X-linked type of liver glycogenosis assigned the disease gene to Xp22. Lod scores obtained with the markers DXS987, DXS207, and DXS999 were 3.97, 2.71, and 2.40, respectively, all at 0% recombination. Multipoint linkage analysis localized the disease gene between DXS143 and DXS989 with a maximum lod score of 4.70 at θ = 0, relative to DXS987. As both the classical XLG gene and the liver α-subunit of PHK (PHKA2) are also located in Xp22, this variant type of XLG may be allelic to classical XLG, and both diseases may be caused by mutations in PHKA2. Therefore, we propose to classify XLG as XLG type I (the classical type of XLG) and XLG type II (the variant type of XLG).     

The Presequence of a Precursor to the {delta}-Subunit of Sweet Potato Mitochondrial F1ATPase is not Sufficient for the Transport of {beta}-Glucuronidase (GUS) into Mitochondria of Tobacco, Rice and Yeast Cells

A precursor to the