A galactose-rich, cell-wall glycoprotein from styles of Nicotiana alata

A basic, galactose-rich style glycoprotein (GaRSGP) encoded by a previously characterized style-specific cDNA (NaPRP4) has been isolated from the styles of Nicotiana alata and structurally characterized. The glycoprotein is associated with cell walls in the transmitting tract and is composed of approximately 25% (w/w) protein and 75% (w/w) carbohydrate. The purified glycoprotein appears as a smear of between 45–120 kDa on SDS—PAGE; the deglycosylated protein backbone has an apparent molecular weight of approximately 30 kDa. The glycoprotein is rich in the amino acids lysine, proline, and hydroxyproline and in the monosaccharides galactose and arabinose. It is one of only a few proline/hydroxyproline-rich glycoproteins (P/HRGPs) to be characterized both as a cDNA-clone and protein. Glycans are attached to the protein backbone through both O - and N -glycosidic linkages with the majority of the carbohydrate being O -linked and consisting of short, highly branched chains terminating primarily in galactose residues. A carbohydrate epitope(s) is found on both GaRSGP and another style-specific glycoprotein but not on glycoproteins from other tissues. This finding provides further evidence for the existence of a style-specific carbohydrate epitope(s) which may play a role in style function.     

Regioselective acylation of several polyhydroxylated natural compounds by Candida antarctica lipase B

Regioselective acylation of four polyhydroxylated natural compounds, deacetyl asperulosidic acid (1), asperulosidic acid (2), puerarin (3) and resveratrol (4) by Candida antarctica Lipase B in the presence of various acyl donors (vinyl acetate, vinyl decanoate or vinyl cinnamoate) was studied. Compounds 1, 2 and 4 were regioselectively acetylated with vinyl acetate to afford products, 3'-O-acetyl-10-O-deacetylasperulosidic acid (1a), 3',6'-O-diacetyl-10-O-deacetylasperulosidic acid (1b), 3'-O-acetylasperulosidic acid (2a), 3',6'-O-diacetylasperulosidic acid (2b), 4'-O-acetylresveratrol (4a), respectively, with yields of 22 to 50%, while reactions with vinyl decanoate and vinyl cinnamoate were slow with lower yields. Compound 3 was readily acylated with all three acyl donors and quantitatively converted to products 6'-O-acetylpuerarin (3a), 6'-O-decanoylpuerarin (3b), 6'-O-cinnamoylpuerarin (3c), respectively. The structures of these acylated products were determined by spectroscopic methods (MS and NMR).     

FunRich: An open access standalone functional enrichment and interaction network analysis tool

As high‐throughput techniques including proteomics become more accessible to individual laboratories, there is an urgent need for a user‐friendly bioinformatics analysis system. Here, we describe FunRich, an open access, standalone functional enrichment and network analysis tool. FunRich is designed to be used by biologists with minimal or no support from computational and database experts. Using FunRich, users can perform functional enrichment analysis on background databases that are integrated from heterogeneous genomic and proteomic resources (>1.5 million annotations). Besides default human specific FunRich database, users can download data from the UniProt database, which currently supports 20 different taxonomies against which enrichment analysis can be performed. Moreover, the users can build their own custom databases and perform the enrichment analysis irrespective of organism. In addition to proteomics datasets, the custom database allows for the tool to be used for genomics, lipidomics and metabolomics datasets. Thus, FunRich allows for complete database customization and thereby permits for the tool to be exploited as a skeleton for enrichment analysis irrespective of the data type or organism used. FunRich ( http://www.funrich.org ) is user‐friendly and provides graphical representation (Venn, pie charts, bar graphs, column, heatmap and doughnuts) of the data with customizable font, scale and color (publication quality).     

Microheterogeneity of N-glycosylation on a stylar self-incompatibility glycoprotein of Nicotiana alata

Gametophytic self-incompatibility, a mechanism that preventsinbreeding in some families of flowering plants, is mediatedby the products of a single genetic locus, the S-locus. Theproducts of the S-gene in the female sexual tissues of Nicotianaalata are an allelic series of glycoproteins with RNase activity.In this study, we report on the microheterogeneity of N-linkedglycosylation at the four potential N-glycosylation sites ofthe S²-glycoprotein. The S-glycoproteins from N.alata containfrom one to five potential N-glycosylation sites based on theconsensus sequence Asn-Xaa-Ser/Thr. The S²-glycoprotein containsfour potential N-glycosylation sites at Asn²⁷, Asn³⁷, Asn¹³⁸and Asn¹⁵⁰, designated sites I, n, IV and V, respectively. SiteIII is absent from the S₂-glycoprotein. Analysis of glycopeptidesgenerated from the S₂-glycoprotein by trypsin and chymotrypsindigestions revealed the types of glycans and the degree of microheterogeneitypresent at each site. Sites I (Asn²⁷) and IV (Asn¹³⁸) displaymicroheterogeneity, site II (Asn³⁷) contains only a single typeof N-glycan, and site V (Asn¹⁵⁰) is not glycosylated. The microheterogeneityobserved at site I on the S₂-glycoprotein is the same as thatobserved at the only site, site I, on the Srglycoprotein (Woodwardet al., Glycobiology, 2, 241-250, 1992). Since the N-glycosylationconsensus sequence at site I is conserved in all S-glycoproteinsfrom other species of self-incompatible solanaceous plants,glycosylation at this site may be important to their function.No other post-translational modifications (e.g. O-glycosylation,phosphorylation) were detected on the S₂-glycoprotein. fertilization microheterogeneity N-glycans plants RNase     

Involvement of telomere dysfunction in the induction of genomic instability by radiation in scid mouse cells

To determine the effects of a defect in NHEJ on the induction of genomic instability by radiation, we investigated X-ray-induced delayed chromosomal aberrations such as dicentrics and fragments in scid mouse cells. We found that radiosensitive scid mouse cells are more susceptible than wild-type mouse cells to the induction of delayed chromosomal aberrations when the cells are exposed to an equivalent survival dose of X-rays. Telomere FISH analysis revealed that radiation enhances the induction of telomeric fusions where telomeric sequences remain at the fused position (tel+ end-fusions), suggesting that radiation induces telomere dysfunction. Moreover, formation of the tel+ end-fusions was found to be enhanced in scid mouse cells, suggesting that DNA-dependent protein kinase catalytic subunit (DNA-PKcs) plays a role in telomeric stabilization. Thus, the present study suggests that a cause of genomic instability is telomere dysfunction induced by radiation and that a defect in DNA-PKcs enhances the telomeric destabilization.     

Release of dimethylsulfide from dimethylsulfoniopropionate by plant-associated salt marsh fungi

The range of types of microbes with dimethylsulfoniopropionate (DMSP) lyase capability (enzymatic release of dimethylsulfide [DMS] from DMSP) has recently been expanded from bacteria and eukaryotic algae to include fungi (a species of the genus Fusarium [M. K. Bacic and D. C. Yoch, Appl. Environ. Microbiol. 64:106-111, 1998]). Fungi (especially ascomycetes) are the predominant decomposers of shoots of smooth cordgrass, the principal grass of Atlantic salt marshes of the United States. Since the high rates of release of DMS from smooth cordgrass marshes have a temporal peak that coincides with peak shoot death, we hypothesized that cordgrass fungi were involved in this DMS release. We tested seven species of the known smooth cordgrass ascomycetes and discovered that six of them exhibited DMSP lyase activity. We also tested two species of ascomycetes from other DMSP-containing plants, and both were DMSP lyase competent. For comparison, we tested 11 species of ascomycetes and mitosporic fungi from halophytes that do not contain DMSP; of these 11, only 3 were positive for DMSP lyase. A third group tested, marine oomycotes (four species of the genera Halophytophthora and Pythium, mostly from mangroves), showed no DMSP lyase activity. Two of the strains of fungi found to be positive for DMSP lyase also exhibited uptake of DMS, an apparently rare combination of capabilities. In conclusion, a strong correlation exists between a fungal decomposer's ability to catabolize DMSP via the DMSP lyase pathway and the host plant's production of DMSP as a secondary product.     

Polysaccharase metabolism in dormant and germinating Stylosanthes humilis seeds

The levels of certain polysaccharase and glycosidase enzymes were followed during the germination of Townsville stylo seeds. Significant levels of inve     

Changes in Cell Wall Composition during Ripening of Grape Berries

Cell walls were isolated from the mesocarp of grape (Vitis vinifera L.) berries at developmental stages from before veraison through to the final ripe berry. Fluorescence and light microscopy of intact berries revealed no measurable change in cell wall thickness as the mesocarp cells expanded in the ripening fruit. Isolated walls were analyzed for their protein contents and amino acid compositions, and for changes in the composition and solubility of constituent polysaccharides during development. Increases in protein content after veraison were accompanied by an approximate 3-fold increase in hydroxyproline content. The type I arabinogalactan content of the pectic polysaccharides decreased from approximately 20 mol % of total wall polysaccharides to about 4 mol % of wall polysaccharides during berry development. Galacturonan content increased from 26 to 41 mol % of wall polysaccharides, and the galacturonan appeared to become more soluble as ripening progressed. After an initial decrease in the degree of esterification of pectic polysaccharides, no further changes were observed nor were there large variations in cellulose (30–35 mol % of wall polysaccharides) or xyloglucan (approximately 10 mol % of wall polysaccharides) contents. Overall, the results indicate that no major changes in cell wall polysaccharide composition occurred during softening of ripening grape berries, but that significant modification of specific polysaccharide components were observed, together with large changes in protein composition.