Voltage holding study of 1 MeV accelerator for ITER neutral beam injector

Voltage holding test on MeV accelerator indicated that sustainable voltage was a half of that of ideal quasi-Rogowski electrode. It was suggested that the emission of the clumps is enhanced by a local electric field concentration, which leads to discharge initiation at lower voltage. To reduce the electric field concentration in the MeV accelerator, gaps between the grid supports were expanded and curvature radii at the support corners were increased. After the modifications, the accelerator succeeded in sustaining -1 MV in vacuum without beam acceleration. However, the beam energy was still limited at a level of 900 keV with a beam current density of 150 A∕m(2) (346 mA) where the 3 × 5 apertures were used. Measurement of the beam profile revealed that deflection of the H(-) ions was large and a part of the H(-) ions was intercepted at the acceleration grid. This causes high heat load on the grids and the breakdowns during beam acceleration. To suppress the direct interception, new grid system was designed with proper aperture displacement based on a 3D beam trajectory analysis. As the result, the beam deflection was compensated and the voltage holding during the beam acceleration was improved. Beam parameter of the MeV accelerator was increased to 980 keV, 185 A∕m(2) (427 mA), which is close to the requirement of ITER accelerator (1 MeV, 200 A∕m(2)).

Effect of corosolic acid on postchallenge plasma glucose levels

Corosolic acid (CRA) is a substance extracted from Lagerstroemia speciosa L. and has been reported to have biological activities in in vitro and experimental animal studies. In this study, 31 subjects were orally administered 10mg CRA or a placebo, on different occasions, in a capsule 5min before the 75-g oral glucose tolerance test (OGTT) in a double-blind and cross-over design. Nineteen subjects had diabetes, seven had impaired glucose tolerance, one had impaired fasting glucose, and four had normal glucose tolerance according to the 1998 WHO criteria. There were no significant differences in plasma glucose levels before and 30min after the administration. CRA treatment subjects showed lower glucose levels from 60min until 120min and reached statistical significance at 90min. In this study, we have shown for the first time that CRA has a lowering effect on postchallenge plasma glucose levels in vivo in humans.

Fungal lethality, binding, and cytotoxicity of syringomycin-E

Syringomycin-E (SE) was significantly lethal to Aspergillus and Fusarium species at between 1.9 and 7.8 micrograms/ml. SE complexed with the following fungal wall constituents (in order of binding): beta-1,3-glucan > chitin > mannan > ergosterol = cholesterol. Cytotoxicity in HeLa cells was proportional to the SE concentration, while the amount required for cytotoxicity was 3 to 20 times that needed to kill 95% of the fungi tested.

Cloning and sequence analysis of two catechol-degrading gene clusters from the aniline-assimilating bacterium Frateuria species ANA-18

The aniline-assimilating bacterium Frateuria species ANA-18 produced two catechol 1,2-dioxygenases, CD I and CD II, and two muconate cycloisomerases, MC I and MC II. The catA genes catA1 and catA2 encoding CD I and CD II, respectively, were cloned from a gene library of this bacterium. The catA1 gene was clustered with catB1 encoding MC I, catC1 encoding muconolactone isomerase (MI), catD encoding beta-ketoadipate enol-lactone hydrolase (ELH), and ORFR1 encoding a putative LysR-type regulator. The organization of these genes was ORFR1catB1C1D. The catA2 gene also constructed a gene cluster involving catB2 encoding MC II, catC2 encoding MI, and ORFR2 encoding a putative LysR-type regulator with the alignment of ORFR2catB2A2C2. The intergenic regions of ORFR1-catB1 and ORFR2-catB2 contained homologous sequences with the catR-catB intergenic region containing a repression binding site and activation binding site of CatR in Pseudomonas putida. These findings suggest that the two cat clusters were regulated independently in their expression. When a product of cloned catD was added to a reaction mixture containing beta-ketoadipate enol-lactone, beta-ketoadipate was produced. This observation showed that the cloned catD encoded ELH and was expressed in Escherichia coli. We found that Frateuria sp. ANA-18 had a large plasmid with a molecular size more than 100kb. Polymerase chain reaction amplifying partial catA genes and Southern hybridization analyses with probes containing catA genes were conducted, to examine the localization of the two catA genes. We concluded that the catA1 and catA2 genes were located on the chromosomal and large plasmid DNAs, respectively, in Frateuria sp. ANA-18.

Purification and characterization of two muconate cycloisomerase isozymes from aniline-assimilating Frateuria species ANA-18

Two muconate cycloisomerases (MC I and MC II, EC 5.5.1.1) were purified to homogeneity from an aniline-grown Frateuria sp. ANA-18. MC I and MC II were similar in molecular mass, optimal pH, and pH stability but different in thermostability, and some other enzymatic properties. NH2-terminal amino acid sequences were different between the two isozymes, indicated that these are encoded by different genes. Different inducible production of MC I and MC II suggested that two catechol branches involved in the beta-ketoadipate pathway function in Frateuria sp. ANA-18.

Identification and analysis of the Saccharomyces cerevisiae SYR1 gene reveals that ergosterol is involved in the action of syringomycin

A 2.5 kb DNA fragment of the Saccharomyces cerevisiae SYR1 gene was cloned by complementation of the syr1 mutations that simultaneously lead to resistance to the phytotoxin syringomycin and sensitivity of growth to high Ca2+ concentrations. Sequencing of this fragment revealed a single open reading frame encoding a polypeptide of 365 amino acids. Four hydrophobic regions each separated by hydrophilic regions were present in the protein. SYR1 was identical to ERG3, which is suggested to encode C-5 sterol desaturase required for ergosterol biosynthesis. The protein product of SYR1 was identified by Western blot analysis as a protein of 40 kDa in the particulate fraction. Gene disruption experiments demonstrated that elimination of SYR1/ERG3 is not lethal, but results in membrane C-5 desaturated sterol deficiencies, resistance to syringomycin and sensitivity to high Ca2+. The syr1 mutant cells had significantly decreased ability for syringomycin binding. The results indicated that C-5 desaturated sterols are involved in the binding of syringomycin to the cell, and the lack of the sterols in the mutant membrane results in sensitivity to high Ca2+ and an increased rate of cellular Ca2+ influx.

[An infection model which was induced in a carboxymethyl cellulose (CMC) pouch on the back of the rat]

The air-pouch model of inflammation in rats is excellent in that it allows quantitative evaluation of inflammation, and it is used for analysis of inflammatory mediators and as an evaluation system for anti-inflammatory drugs. We investigated the possibility of using this system as an experimental infection system. As a result, inflammation was found to be caused by injection of a constant amount of Staphylococcus aureus solution (10(4)-10(8)). The amount of infiltration and the number of infiltrating cells varied with quantity of bacteria. The infiltrating cells consisted mainly of neutrophils. In this experimental model of infectious disease, the severity of inflammation could be quantitatively evaluated as a function of time in terms of bacterial proliferation and the body's response to bacterial proliferation based on the amount of fluid in the air pouch and the number of infiltrating cells, suggesting that the model is useful. In this experimental system, there were no differences between the number of live bacteria, the number of infiltrating cells or the amount of infiltration when S. aureus Smith strain and clinically-isolated methicillin-resistant S. aureus (MRSA) were used, suggesting that there is no difference between the inflammation-induced activity of MRSA and MSSA.

Comparison, by freeze-fracture electron microscopy, of chromatophores, spheroplast-derived membrane vesicles, and whole cells of Rhodopseudomonas sphaeroides

By using freeze-fracture electron microscopy, chromatophores and spheroplast-derived membrane vesicles from photosynthetically grown Rhodopseudomonas sphaeroides were compared with cytoplasmic membrane and intracellular vesicles of whole cells. In whole cells, the extracellular fracture faces of both cytoplasmic membrane and vesicles contained particles of 11-nm diameter at a density of about 5 particles per 10(4) nm2. The protoplasmic fracture faces contained particles of 11 to 12-nm diameter at a density of 14.6 particles per 10(4) nm2 on the cytoplasmic membrane and a density of 31.3 particles per 10(4) nm2 on the vesicle membranes. The spheroplast-derived membrane fraction consisted of large vesicles of irregular shape and varied size, often enclosing other vesicles. Sixty-six percent of the spheroplast-derived vesicles were oriented in the opposite way from the intracellular vesicle membranes of whole cells. Eighty percent of the total vesicle surface area that was exposed to the external medium (unenclosed vesicles) showed this opposite orientation. The chromatophore fractions contained spherical vesicles of uniform size approximately equal to the size of the vesicles in whole cells. The majority (79%) of the chromatophores purified on sucrose gradients were oriented in the same way as vesicles in whole cells, whereas after agarose filtration almost all (97%) were oriented in this way. Thus, on the basis of morphological criteria, most spheroplast-derived vesicles were oriented oppositely from most chromatophores.

Effects of incident light levels on photosynthetic membrane polypeptide composition and assembly in Rhodopseudomonas sphaeroides

Cells of Rhodopseudomonas sphaeroides were grown anaerobically with incident light levels ranging between 4,500 and 400 footcandles (ca. 48,420 and 4,304 lux). Cells grown with the higher light levels had lower contents of total bacteriochlorophyll and incorporated L-[U-14C]leucine into membrane protein at higher rates than cells grown with lower light levels. The former cells also contained relatively lower amounts of light-harvesting membrane polypeptides as compared with the latter cells. In contrast, the relative amounts of reaction center membrane polypeptides were approximately the same with varying incident light levels. The relative amounts of these membrane polypeptides were correlated with differences in rates of synthesis and assembly of the polypeptides into membrane by measuring the rates of incorporation of L-[U-14C]leucine into the membrane-bound polypeptides. No significant differences in rates of turnover of these polypeptides were detected under the varying incident light levels as measured in pulse-chase radioactive labeling experiments.

Subunits of phycoerythrin from Fremyella diplosiphon: chemical and immunochemical characterization

The alpha and beta subunits of the phycobiliprotein, phycoerythrin, isolated from the filamentous blue-green alga, Fremyella diplosiphon, have been separated by chromatography on Bio-Rex 70 ion exchange resin. Analysis by sodium dodecyl sulfate polyacrylamide gel electrophoresis shows no detectable cross-contamination of these subunit preparations. The molar extinction coefficients at 552 nm of the alpha and beta subunits in 8 M urea are 25,549 and 48,456, respectively. The amino acid compositions of the subunits are very similar. Molecular weights of the alpha and beta subunits are 19,500 and 21,700, respectively, based on the amino acid composition analyses. Antisera prepared against the alpha subunit reacts with the beta subunit, and vice versa. Tryptic peptide maps reveal that the subunits share share at least eight common tryptic peptides. These results indicate that the phycoerythrin subunits are chemically very similar.

Release and recovery of forespores from Bacillus cereus

A method is described which makes possible the release of immature forespores from sporulating cells at specific stages of development, from the completion of stage III through to mature spore formation. With the aid of zonal density gradient centrifugation, the method makes possible the recovery of quantities of forespores ample for biochemical and physical studies. With the capability to examine forespores and some mother cell components independently, we have established that several enzymes associated with the sporulation process are localized in the newly developed forespores. Studies showed that aspartate aminotransferase and alanine aminotransferase are associated with the forespores, whereas l-alanine dehydrogenase is found only in the mother cell cytoplasm.

Coupling between bacteriochlorophyll and membrane protein synthesis in Rhodopseudomonas spheroides

Bacteriochlorophyll-containing membranes from Rhodopseudomonas spheroides contain proteins with estimated molecular weights of 26,000, 22,000, 19,000, and 10,000-6,000 (proteins 9, 10, 11, and 15) when analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Proteins 9, 10, and 11 may be associated with the reaction center form of bacteriochlorophyll and protein 15, with the light-harvesting form. These proteins were not detected in membranes from nonpigmented wild-type cells grown with high aeration. Proteins 10, 11, and 15 were not found in mutants with blocks in bacteriochlorophyll synthesis, including strain 8-17, which is blocked at the phytolation step. Protein 9 was found in significantly reduced amounts. Apparently, synthesis of the completed bacteriochlorophyll molecule is required for the occurrence of these proteins in the membrane. Gel autoradiography was used to follow the synthesis of membrane proteins in mutant H-5, which requires delta-aminolevulinic acid for bacteriochlorophyll synthesis. Incorporation of labeled amino acids into proteins 9 and 15 was curtailed preferentially in cells deprived of delta-aminolevulinic acid.