Studies on Fe complexes produced by yeast. IV. Mechanism of Fe transport from an Fe(II)-oligosaccharide complex across the mucosal membrane of the rat intestine

The mechanism of Fe transport across the rat duodenal membrane from an Fe(II)-oligosaccharide complex (designated B1-c) produced in wine by yeast and showing high hematopoietic activity in rats was examined. The Fe uptake from B1-c by brush border membrane (BBM) vesicles isolated from the rat intestine was based mainly on the Fe binding to membrane components which were suggested to be inside the vesicles. Evidence that Fe was transported into the vesicles by a special transport system other than simple diffusion was obtained by observing saturation kinetics under conditions of isotope exchange, and temperature and pH dependence. This Fe uptake was not inhibited by any metal ions tested, including inorganic Fe(II), and the BBM vesicles from the duodenum had a higher Fe uptake than those from the other parts of the small intestine. Furthermore, the BBM vesicles isolated from rats with Fe deficiency showed a significantly increased Fe uptake. The Km value for B1-c uptake was 0.16 mM, lower than the values for FeSO4 and ferrous ascorbate. These results suggest that a special transport system selective for B1-c may be present on the mucosal membrane. B1-c was taken up by the BBM vesicles in the form of Fe-oligosaccharide complex. From the preloaded vesicles, B1-c was released temperature- and pH-dependently.(ABSTRACT TRUNCATED AT 250 WORDS)     

Simultaneous ion-exclusion/cation-exchange chromatography of anions and cations in acid rain waters on a weakly acidic cation-exchange resin by elution with sulfosalicylic acid

A simple, selective, and sensitive method for the simultaneous determination of anions (sulfate, nitrate, and chloride) and cations (sodium, ammonium, potassium, magnesium, and calcium) in acid rain waters was developed using ion-exclusion/ cation-exchange chromatography with conductimetric detection. A weakly acidic cation-exchange resin column (Tosho TSKgel OA-PAK-A) and a sulfosalicylic acid-methanol-water eluent was used. With a mobile phase comprising 1.25 mM sulfosalicylic acid in methanol-water (7.5:92.5) at 1.2 ml/min, simultaneous separation and detection of the above anions and cations was achieved in about 30 min. Linear calibration plots of peak area versus concentration were obtained over the concentration ranges 0-1.0 mM for anions (R=0.9991) and 0-0.5 mM for cations (R=0.9994). Detection limits calculated at S/N=3 ranged from 4.2 to 14.8 ppb for the anions and from 2.4 to 12.1 ppb for the cations. The reproducibility of retention times was 0.14-0.15% relative standard deviation (RSD) for anions and 0.18-0.31% for cations, and reproducibility of chromatographic peak areas was 1.22-1.75% RSD for anions and 1.81-2.10% for cations. The method was applied successfully to the simultaneous determination of anions and cations in aerosols transported from mainland China to central Japan, as determined by a meteorological satellite data analyzer.     

Mononuclear five-coordinate molybdenum(IV) and -(V) monosulfide complexes coordinated with dithiolene ligands: reversible redox of Mo(V)/Mo(IV) and irreversible dimerization of [MoVS]- cores to a dinuclear [MoV2(mu-S)2]2- Core

A mononuclear five-coordinate molybdenum(IV) monosulfide complex, (Et4N)2[MoS(L)2] (L = cyclohexene-1,2-dithiolate) (1), was obtained and characterized by IR, UV-vis spectroscopic methods, and X-ray crystallography. 1 was oxidized by an equivalent ferrocenium cation to give the corresponding mononuclear molybdenum(V) complex, (Et4N)[MoS(L)2] (2), which was stable for a few minutes under a lower concentration than 0.3 mM and then further dimerized to (Et4N)2[Mo(L)2]2(mu-S)2 (3).     

Three new sesquiterpenoid glucosides of Ficus pumila fruit

As the glycosyl constituents of Ficus pumila L. fruits (Moraceae), three new sesquiterpenoid glucosides, pumilasides A, B and C were isolated together with benzyl beta-D-glucopyranoside, (E)-2-methyl-2-butenyl beta-D-glucopyranoside and rutin. Their structures were characterized as (1S,4S,5R,6R,7S,10S)-1,4,6-trihydroxyeudesmane 6-O-beta-D-glucopyranoside, (1S,4S,5S,6R,7R,10S)-1,4-dihydroxymaaliane 1-O-beta-D-glucopyranoside and 10 alpha, 11-dihydroxycadin-4-ene 11-O-beta-D-glucopyranoside by spectral and chemical methods.     

Structure of inorganic nanoclusters embedded in solid matrixes: an X-ray absorption study

Results of X-ray absorption studies of copper nanoclusters embedded in SiO₂ matrix and selenium chains confined in channels of cancrinite are reported. Initially randomly distributed copper atoms mainly surrounded by silicon species in an as-made film upon annealing form copper nanoclusters with a characteristic size of 80 Å and the structure identical to that of bulk copper. The characteristic size of the clusters does not increase with further annealing. Selenium in cancrinite is shown to form strongly oriented linear dimerised chains with a bond length much larger than that in bulk forms of selenium.     

Supramolecular Hybrids from Cyanometallate Complexes and Diblock Copolypeptide Amphiphiles in Water

The self-assembly of discrete cyanometallates has attracted significant interest due to the potential of these materials to undergo soft metallophilic interactions as well as their optical properties. Diblock copolypeptide amphiphiles have also been investigated concerning their capacity for self-assembly into morphologies such as nanostructures. The present work combined these two concepts by examining supramolecular hybrids comprising cyanometallates with diblock copolypeptide amphiphiles in aqueous solutions. Discrete cyanometallates such as [Au(CN)₂]⁻, [Ag(CN)₂]⁻, and [Pt(CN)₄]²⁻ dispersed at the molecular level in water cannot interact with each other at low concentrations. However, the results of this work demonstrate that the addition of diblock copolypeptide amphiphiles such as poly-(L-lysine)-block-(L-cysteine) (Lys_m-b-Cys_n) to solutions of these complexes induces the supramolecular assembly of the discrete cyanometallates, resulting in photoluminescence originating from multinuclear complexes with metal-metal interactions. Electron microscopy images confirmed the formation of nanostructures of several hundred nanometers in size that grew to form advanced nanoarchitectures, including those resembling the original nanostructures. This concept of combining diblock copolypeptide amphiphiles with discrete cyanometallates allows the design of flexible and functional supramolecular hybrid systems in water.     

Isolation,Diversity and Characterization of Ulvan-Degrading Bacteria Isolated from Marine Environments

In this study, we aimed to isolate bacteria capable of degrading the polysaccharide ulvan from the green algae Ulva sp. (Chlorophyta, Ulvales, Ulvaceae) in marine environments. We isolated 13 ulvan-degrading bacteria and observed high diversity at the genus level. Further, the genera Paraglaciecola, Vibrio, Echinicola, and Algibacter, which can degrade ulvan, were successfully isolated for the first time from marine environments. Among the 13 isolates, only one isolate (Echinicola sp.) showed the ability not only to produce externally expressed ulvan lyase, but also to be periplasmic or on the cell surface. From the results of the full-genome analysis, lyase was presumed to be a member of the PL25 (BNR4) family of ulvan lyases, and the bacterium also contained the sequence for glycoside hydrolase (GH43, GH78 and GH88), which is characteristic of other ulvan-degrading bacteria. Notably, this bacterium has a unique ulvan lyase gene not previously reported.     

Observation of spatial distribution of laser-induced refractive index change in dye-doped liquid crystals

Spatial distributions of photothermal refractive index changes in dye-doped liquid crystals were determined by an optical interferometric method. The refractive index change of the order of 10^-1, including spatial distribution, was estimated by the described experimental technique. The absolute value of the refractive index change was proportional to the pump beam power, and the diameter of the index distribution was slightly larger than that of the pump laser beam due to heat conduction.