The first total synthesis of glycosphingolipids isolated from wheat flour has been achieved in a regio- and stereo-controlled manner.Abbreviations THF
tetrahydrofuran
- DMF
dimethylformamide
Part 53 in the series Synthetic Studies on Cell Surface Glycans 相似文献
Investigations of rhubarb and the bark of Rhaphiolepis umbellata led to the isolation of new flavan-3-ol glucosides. Their structures were elucidated on the basis of 1H and 13C NMR analysis hydrolytic studies as (+)-catechin 5-O-β-d-glucopyranoside and (?)-catechin 7-O-β-d-glucopyranoside. 相似文献
We found the presence of plasmid DNA in strain T88-56 of the Japanese pear pathotype of Alternaria alternata, which causes black spot of certain cultivars of Japanese pear by producing host-specific AK-toxin. The plasmid, designated pAAT56, was identified to be an ~5.4-kilobase (kb) circular molecule by electron microscopic observation and restriction endonuclease mapping. Southern blot analysis showed that pAAT56 DNA had no homology with either nuclear or mitochondrial DNA. Cultures of strain T88-56 grown at 26° showed markedly reduced plasmid levels relative to those grown at lower temperatures. The strain was completely cured of pAAT56 during growth at 29°. Temperature-dependent curing of pAAT56 was confirmed by using single-protoplast isolates from mycelia grown at 23°, most of which maintained the plasmid, and from mycelia grown at 29°, most of which had lost the plasmid. Northern blot analysis detected the presence of three RNA species (~1.7, 2.7 and 5.4 kb) transcribed from pAAT56. The biological function of pAAT56 was observed using single-protoplast isolates from mycelia that either contained or had been cured of pAAT56. The plasmid-containing isolates tended to be reduced in AK-toxin production and pathogenicity compared with the plasmid-cured isolates. 相似文献
Metal ion-induced conformational changes in Serratia protease which contains one zinc ion per molecule were investigated by the small-angle x-ray scattering method. The molecule is an elongated ellipsoid of approximately 110 x 40 x 40 A with a large cleft in its central region. Comparisons of the native (zinc-enzyme) with the zinc-free (apoenzyme) enzyme and with the zinc-replated metalloenzyme show small but significant differences in their radii of gyration, maximum particle dimensions, and intraparticle pair-distance distributions. The radius of gyration and maximum particle dimension of the native enzyme are almost the same as those of the cobalt-enzyme but are shorter and longer, respectively, than those of the apo- and cadmium-enzymes. Simulation analysis based on the intraparticle pair-distribution function showed that these modified enzymes are comparable with the native enzyme in overall structure, and, except for the cobalt-enzyme, differ in cleft size. The residual enzymatic activity of the cobalt-enzyme is the same as that of the native enzyme, but the apo- and cadmium-enzymes have considerably less activity. The size of the cleft therefore is strictly controlled to ensure optimal enzyme activity, and the position and coordination behavior of the zinc ion in the cleft appears to be essential both for biological functioning and for the maintenance of the gross tertiary structure. 相似文献
Protocorms or protocorms with roots of an achlorophyllous orchidGaleola septentrionalis were inoculated with isolates ofRhizoctonia repens, R. solani, andRhizoctonia spp. The seedlings were infected with eight of twelve isolates ofR. repens. Fungal coils were formed in the cells, which was suggestive of a symbiotic association. The other isolates caused soft rot
or no infection to the protocorms or the protocorms with a root.
Contribution No. 97, Laboratories of Plant Pathology and Mycology, Institute of Agriculture and Forestry, University of Tsukuba,
Tsukuba, Ibaraki 305, Japan. 相似文献
Apoptosis (programmed cell death) is a basic physiological processwhich determines specific patterns of tissue size and shape,and balance of cell number, during morphogenesis, and seemsto play an integral role in oncogenic progression. Since dramaticchanges of cellular glycosylation pattern are well known tobe closely correlated with differentiation, development andoncogenesis, it is likely that similar specific changes areassociated with apoptosis. However, this possibility has notbeen systematically investigated. We therefore carried out histologicalstudies of many tumours and normal tissues for which a highincidence of apoptosis is believed to occur. Sections were stainedwith monoclonal antibodies (MoAbs) directed to carbohydrateantigens Ley and Lex, proliferating cellular nuclear antigen(PCNA) and Fas (previously claimed to be an apoptosis-inducingantigen). Antibody staining patterns were compared with morphologicalcell characteristics as revealed by haematoxylin/eosin staining,and DNA fragmentation patterns (a marker of apoptosis) as revealedby 3'-OH nick-end labelling technique. We found that expressionof Ley (defined by MoAb BM1) is closely correlated with theprocess of apoptosis, but not with cell proliferation or necrosis.Within Ley-positive areas of tissue sections, typical apoptoticmorphological changes and DNA fragmentation (as revealed bypositive nick-end labelling) were frequently observed in certainloci, although not all Ley-positive cells showed such signsof apoptosis. Ley-positive areas showed consistent negativestaining by MoAb directed to PCNA and negative or weak stainingby MoAb directed to Fas antigen, regardless of tissue source.No such trends were observed for Lex glycosylation. We concludethat Ley expression is a useful phenotypic marker predictiveof apoptosis, i.e. some (although not all) Ley-positive cellssubsequently become apoptotic. apoptosis expression glycosylation patterns Ley antigen 3'-OH nick-end labelling 相似文献
Protein O-linked mannose β1,2-N-acetylglucosaminyltransferase 1 (POMGnT1) is an enzyme that transfers N-acetylglucosamine to O-mannose of glycoproteins. Mutations of the POMGnT1 gene cause muscle–eye–brain (MEB) disease. To obtain a better understanding of the pathogenesis of MEB disease, we mutated the POMGnT1 gene in mice using a targeting technique. The mutant muscle showed aberrant glycosylation of α-DG, and α-DG from mutant muscle failed to bind laminin in a binding assay. POMGnT1?/? muscle showed minimal pathological changes with very low-serum creatine kinase levels, and had normally formed muscle basal lamina, but showed reduced muscle mass, reduced numbers of muscle fibers, and impaired muscle regeneration. Importantly, POMGnT1?/? satellite cells proliferated slowly, but efficiently differentiated into multinuclear myotubes in vitro. Transfer of a retrovirus vector-mediated POMGnT1 gene into POMGnT1?/? myoblasts completely restored the glycosylation of α-DG, but proliferation of the cells was not improved. Our results suggest that proper glycosylation of α-DG is important for maintenance of the proliferative activity of satellite cells in vivo.相似文献
1. 1. The objective of this paper is to investigate the indoor environment from the viewpoint of interaction between physical environment and the human responses. The field survey has been conducted over 1 year.
2. 2. A continuous measurement has been carried out for 1 week and distribution of variables have been measured for 1 day.
3. 3. The attitude of workers was investigated by a questionnaire.
4. 4. As the result, average luminance represented more than 1000 lx in the new building, in contrast with less tha 300 lx in the existing building.
5. 5. There was a significant difference of the occupants' response to the light environment between the two buildings.
6. 6. Measured thermal conditions are on the edge of the ASHRAE comfort envelope in summer, and in the neighborhood of the lower dry limit of the envelope in spring.
7. 7. The occupants' evaluations were remarkably changed before and after the moving. The office environment is better than that of the factory.