Determination of fermentable carbohydrate from the upper gastrointestinal tract by using colectomized rats.

The primary aim of this study was to characterize the carbohydrate that would be supplied to the colon for fermentation under physiological conditions. Colectomized rats were fed fiber-free diets or diets containing 5% (wt/wt) gum arabic. Four (fucose, galactose, glucosamine, and galactosamine) of 11 analyzed sugars accounted for 77% of the total sugar in ileal excreta from colectomized rats fed fiber-free diets. The three sugars in gum arabic, rhamnose, arabinose, and galactose, accounted for 84% of the total sugars in gum arabic ileal excreta. Comparisons of the sugar compositions of the ileal excreta, the water-soluble fractions of the excreta, and three gel filtration fractions of the water-soluble material with those of the water-soluble fraction of rat mucosa, the acetone-soluble fraction of pancreas, and pancreatin suggested that the major source of endogenous carbohydrate is mucin. Gum arabic increased the daily excretion of the four mucin-derived sugars (fucose, galactose, glucosamine, and galactosamine) by the colectomized rats from 473 mumol per day to 634 mumol per day. We conclude that mucin is the major endogenous carbohydrate excreted from the upper gut and that gum arabic increases the amount of this endogenous carbohydrate.     

Carbohydrate composition of lymphocyte plasma membrane from pig mesenteric lymph node.

Pig lymphocyte plasma membrane isolated from mesenteric lymph node contained 69 mug of carbohydrate/mg dry wt., which was made up of neutral sugar, amino sugar and sialic acid in the molar proportions 5:1.7:1. The neutral sugar comprised fucose, ribose, mannose, glucose, galactose and inositol (molar proportions 2:9:11:15:26:1), and the amino sugar glucosamine and galactosamine (molar ratio 2:1). The ribose was most probably derived from RNA. All of the fucose and mannose and almost all of the glucosamine were associated with the membrane protein whereas the membrane lipid contained all of the inositol. The remaining sugars were distributed in various ratios between the protein and lipid fractions.     

Studies on the structure of a phosphoglycoprotein from the parasitic protozoan Trypanosoma cruzi.

A glycoprotein (GP72) has been isolated from Trypanosoma cruzi and found to contain 41% protein, 49% carbohydrate and 10% phosphate. All phosphate was covalently attached to the carbohydrate which contained the following sugars: ribose, xylose, fucose, galactose, mannose, glucose and glucosamine. The carbohydrate side chains were linked to protein by fucose, xylose and N-acetylglucosamine; 50% of the total N-acetylglucosamine was involved in glycoprotein linkages. Two classes of carbohydrate side chains were detected. One class comprised 15% of the total carbohydrate and contained glucosamine, mannose and galactose; some of these chains were phosphorylated. The other class comprised 85% of the total carbohydrate and contained xylose, ribose, fucose, galactose, mannose, glucosamine and phosphate; these chains were antigenic and reacted with a monoclonal antibody with specificity for the whole glycoprotein.     

Glycosylation of vesicular stomatitis virus glycoprotein in virus-infected HeLa cells.

Glycosylation of the envelope glycoprotein of vesicular stomatitis virus was examined using virus-infected HeLa cells that were pulse-labeled with radioactive sugar precursors. The intracellular sites of glycosylation and the stepwise elongation of the carbohydrate side chains of the G protein were monitored by membrane fractionation and gel filtration of Pronase-digested glycopeptides. The results with short pulses of sugar label (5 to 10 mtein linkage (glucosamine and mannose) are added to G which was associated with the rough endoplasmic reticulum-enriched membrane fraction, whereas the more distal sugars (galactose, sialic acid, fucose, and possibly more glucosamine) are added in the light-density internal membrane fraction. Accumulation of mature G was observed in the plasma membrane-enriched fraction. The gel filtration studies indicated that the initial glycosylation event may be the en bloc addition of a mannose and glucosamine oligomer, followed by the stepwise addition of the more distal sugars.     

Simultaneous assay of neutral sugars and amino sugars by an automatic sugar analyzer: applications to glycoproteins.

The simultaneous assay of neutral sugars and amino sugars commonly found in glycoproteins is described. The automatic sugar analyzer used for the determination is based on the ion-exchange chromatography of sugar-borate complexes on a strong anion-exchange resin. The sugars are identified with the orcinol/sulfuric acid reagent. While less than 40 nmol of mannose, fucose, galactose, glucose, xylose, or arabinose is sufficient for analysis at least 200 nmol mannosamine, glucosamine, or galactosamine is required; acidic monosaccharides cannot be determined. The technique of sugar analysis is applied to structural studies on natural compounds, e.g. the monosaccharide composition of lichenan and the carbohydrate moiety of the glycoproteins ovomucoid and Collocalia mucoid.     

The carbohydrate components of hydrolysates of gastric secretion and extracts from mucous glands of the gastric body mucosa and antrum

1. The sugars and amino sugars of hydrolysates of gastric secretion were determined by gas-liquid chromatography. 2. All the gastric aspirations examined showed on hydrolysis the presence of fucose, galactose, mannose, glucose, galactosamine, glucosamine, N-acetylneuraminic acid and sulphate. 3. Galactose and glucosamine were always found in equimolar amounts, but the galactose/galactosamine ratio in different aspirations was 2:1, 3:1, 4:1 or 5:1. Repeated gastric aspirations of each subject examined showed constant ratios of these carbohydrate components. 4. Fucose and sialic acid appear to be related to glucosamine and galactosamine respectively. 5. The carbohydrate components of extracts from the mucous glands of the body mucosa and antrum did not differ from those of gastric secretion.     

Ontogenic and nutritional modifications in the intestinal fucosylation process at the weaning period. Influence of dietary fibers

In the rat small intestine, the glycosylation changes which normally take place at the weaning period are characterized by a shift from sialylation of fucosylation. The introduction of dietary fibers at weaning is one of the more striking nutritional modification so that some authors have suggested that the presence of fibers and the development of colonic fermentation might be important for the development of the small intestine, as for the colon. In order to define the respective contribution of ontogenic and nutritional factors to the intestinal glycosylation changes at this period, some aspects of the intestinal glycosylation were studied in five groups of rats (16-day-old suckling rats, prolonged nursing 23-day-old rats, 23-day-old rats weaned at day 19 with either a fiber-free, a cellulose or a pectin diet). Intestinal glycoproteins of suckling rats are characterized by a low fucose content and a high proportion of mannose. The amounts of the neutral sugars (fucose, mannose and galactose), expressed either per gram of intestine or for one intestine, are alwars higher in the fiber-fed groups than in the prolonged-nursing group or the group fed the fiber-free diet. Activities which promote fucosylation process (GDP-fucose production and fucosyltransferase activities) and those which are opposed to fucosylation (endogenous inhibitor of fucosyltransferase and GDP-fucose pyrophosphatase) are strongly modified in opposite ways at day 23 as compared to day 16. These modifications depend on the age of the animal (ontogenic factors) with additional modifications induced by the dietary factors. In particular, similar sugar contents and patterns are obtained with cellulose and pectin diests though the enzymatic activities of the fucosylation pathway are very different. No correlation was found between the caecal content of short chain fatty acids and any of the parameters under study. Thus, dietary fibers induce metabolic changes in the small intestine glycosylation in short-term experiments independently of colonic fermentation. Besides, these results point out that the consideration of fucosyl-transferase activities alone are not sufficient to predict glycoprotein fucose content and that other regulatory sites are involved. Dietary manipulations at the weaning period could represent a good model for the study of glycosylation regulation.     

Carbohydrate composition of cells and plasma membranes of Distyostelium discoideum at selected stages of development

Cells of Distyostelium discoideum representing four developmental stages were atuo-analysed for constituent monosaccharides and their compositions compared. Rhamnose, ribose, fucose, glucose, mannose, galactose, glucosamine, galactosamine and an unidentified sugar were recovered after hydrolysis in 2 M HCl for 2 h at 100°C. The relative proportions of the individual sugars were found to vary as a function of development. The largest variations were in the proportions contributed by galactose (from 2% of vegetative cell carbohydrate to 12% of the carbohydrate of fruiting bodies) and galactosamine (present in measurable quantity only in fruiting bodies).Plasma membrane “ghosts” were found to have the same monosccharide constituents as whole cells, but in different proportions. Mannose contributed over 24% of the total carbohydrate recovered from aggregating cell “ghosts”, but only 13% of carbohydrate recovered from “ghosts” prepared from vegetative cells. Galactose was the most abundant sugar recovered from vegetative “ghosts”, and was second only to mannose in aggregating “ghosts”.     

Carbohydrate Composition of Vesicular Stomatitis Virus

Analysis by gas-liquid chromatography of the trimethylsilylated sugar residues of purified vesicular stomatitis virus grown in L cells or chick embryo cells revealed the presence in the whole virion of four hexoses (glucose, galactose, mannose, and fucose), two hexosamines (glucosamine and galactosamine), and 34 to 40% neuraminic acid. The isolated viral glycoprotein was devoid of galactosamine and fucose, both of which sugars were present in whole virions presumably as part of the membrane glycolipids.     

Effects of dietary fibre on the intestinal absorption of dextrin, blood sugar level and growth of tilapia, Oreochromis niloticm × O. aureus

The roles of five different dietary fibres (cellulose, agar, guar gum, carrageenan and carboxy-methylcellulose) each as 10% wt/wt added into the diet, affecting the intestinal sugar absorption, blood sugar level and utilization of dextrin were studied in hybrid tilapia, Oreochromis niloticus × O. aureus ; dextrin and glucose were also included in the study as controls for comparison. There were seven dietary groups: each diet was fed to three aquaria each containing 15 fish. The experiment was carried out in a closed circulation, filtered, rearing system for 2 months. The results indicated that the weight gain percentage and food conversion ratio were significantly (P<0.05) lower in tilapia fed fibre-containing diets than those of tilapia fed dextrin or glucose diet. The intestinal absorption of carbohydrate and the blood sugar content of tilapia were low when diets contained fibre, regardless of the source.     

Soluble Cell Wall Polysaccharides Released from Pea Stems by Centrifugation : I. EFFECT OF AUXIN

The metabolism of polysaccharides by pea stem segments treated with and without auxin was investigated using a centrifugation technique for removing solution from the free space of the cell wall. Glucose is the predominant sugar in both the ethanol-soluble and ethanol-insoluble fractions of the cell wall solution extracted with water. In the water-soluble, ethanol-insoluble polysaccharides, arabinose, xylose, galactose, and glucose make up 9.5, 23.8, 23.9, and 39.9%, respectively, of the neutral sugars, while rhamnose, fucose, and mannose are present at concentrations between 0.5 and 2.0%.     

Evidence for the presence of complex carbohydrates in Candida albicans cell wall glycoproteins

In order to test the hypothesis that cell wall glycoproteins of Candida albicans contained non-mannan oligosaccharides, the sugar composition of cell wall extracts and fractions of cell wall extracts was examined by means of fluorophore-assisted carbohydrate electrophoresis (FACE). In addition to the expected mannose, glucose, and N-acetyl-glucosamine, this analysis showed the presence of galactose, N-acetyl-galactosamine, fucose, and sialic acid and two unknown sugars. These sugars are also associated with complex oligosaccharides of mammalian glycoproteins. Presence of fucosylated cell wall components was further demonstrated by lectin-blotting analysis of cell wall extracts. Besides their structural role, complex carbohydrate structures on the surface of C. albicans may represent additional motifs through which interactions of this fungus with host cells and tissues could be established.     

Seed glycoproteins of Lupinus angustifolius

The seed globulins of Lupinus angustifolius are glycoproteins containing 1.4–1.9% (α-conglutin), 2.8–6.4 % (β-conglutin) and 1.2–3.8% (γ-conglutin) carbohydrate. The highest values were obtained after acid hydrolysis and determination by phenol—H₂SO₄, (α, γ-conglutins) or by methanolysis and sugar determination by GLC (β-conglutin). TCA denaturation of β- and γ-conglutins was necessary to remove adsorbed galactomannans before determination of glycoprotein carbohydrates. All 3 conglutins contained mannose, galactose and glucosamine, though the ratio of mannose to galactose, and to a lesser extent neutral sugars to hexosamine varied. Small amounts of fucose were found associated only with γ-conglutin.     

Resistance of Zygorhynchus Species to Lysis

Zygorhynchus vuilleminii, a nonmelanin-containing fungus, was not lysed by mycolytic actinomycetes. Several enzymes and Streptomyces enzyme preparations digesting walls of other fungi were without appreciable activity on walls of Zygorhynchus species. A bacterium able to solubilize a portion of the Zygorhynchus wall released little or no reducing sugars from these structures. Fractions of Z. vuilleminii walls were resistant to glucanase hydrolysis, but certain fractions were digested by chitinase and microbial enzyme preparations. The walls and several wall fractions were not readily susceptible to degradation by a soil community. Walls of lysis-resistant Zygorhynchus species contained glucosamine, fucose, glucuronic acid, and galactose but little or no glucose. Resistant wall fractions were rich in uronic acid and fucose, whereas the readily degradable fractions contained abundant glucosamine. Cultural conditions affected the extent of digestion and composition of the walls. Possible reasons for the resistance of Zygorhynchus to lysis in nature are discussed.     

Impaired glycosylation in liver microsomes of orotic-acid-fed rats

In rats fed orotic acid, the incorporation in liver subcellular fractions of sugars injected intraperitonealy is altered only for mannose, but not for fucose or galactose. Direct determinations of several glycosyltransferases are done in smooth and rough microsomes: fucosyl-, glactosyl-, N-acetylglucosaminyltransferase activities are at quite similar levels in normal and fatty livers. By contrast, sialyltransferase activity is increased (+50%) in smooth microsomes of fatty livers, while mannosyltransferase activity is inhibited by 30%. These alterations are not caused by interfering reactions pyrophosphatases or proteases). For the mannosyltransferase activity, the inhibition is found in the dolichylphorylmannose intermediates. Kinetic studies suggest that there is deficiency of both enzyme and endogenous dolichyl phosphate.     

Glycoproteins of Sindbis Virus: Preliminary Characterization of the Oligosaccharides

The carbohydrate content of Sindbis virus was determined by gas chromatographic analysis. The two viral glycoproteins were found to be approximately 8% carbohydrate by weight. Mannose is the sugar present in the largest amount. Smaller amounts of glucosamine, galactose, sialic acid, and fucose were also detected. Each of the two viral glycoproteins appears to contain two structurally unrelated oligosaccharides. Two of the three Sindbis-specific glycoproteins found in infected chick cells were shown to contain short, unfinished oligosaccharides.     

中性糖在土壤中的来源与分布特征

糖类(即碳水化合物)是土壤有机质的重要组成部分, 经生物化学降解形成不同结构的单糖。土壤中的中性单糖也叫中性糖, 主要包括木糖、核糖、阿拉伯糖、葡萄糖、半乳糖、甘露糖、岩藻糖和鼠李糖。其中, 植物来源的糖主要为五碳糖, 如木糖和阿拉伯糖; 微生物来源的糖主要包括半乳糖、甘露糖、岩藻糖、鼠李糖等六碳糖。研究中常利用六碳糖和五碳糖的比例指示微生物和植物对土壤有机碳的相对贡献。中性糖是微生物重要的碳源和能量来源, 在团聚体的形成过程中扮演着重要角色。该文整合了近30年土壤中性糖的研究进展, 对比了提取中性糖的常用方法, 分析了不同土地利用类型和不同土壤组分中中性糖的含量、来源和周转特征, 综述了影响中性糖含量和分布的主要环境因素。结果表明, 中性糖在耕地土壤中的绝对含量和相对含量均显著低于针叶林、阔叶林、草地和灌丛4种土地利用类型。(半乳糖+甘露糖)/(阿拉伯糖+木糖)(GM/AX)在不同土地利用间差异不显著, 而(鼠李糖+岩藻糖)/(阿拉伯糖+木糖)(RF/AX)则表明草地土壤中的微生物来源的中性糖含量高于针叶林和耕地。不同密度的土壤组分中, 轻质组分中中性糖的含量比重质组分高, 重质组分中微生物来源的中性糖较多; 就不同粒径(或团聚体)而言, 黏粒(或微团聚体)中微生物来源的中性糖含量更丰富。有关影响土壤中性糖含量和分布的因素的研究, 目前主要集中在人为活动(如耕种和放牧等), 而有关温度、降水等自然环境因素影响的研究较少。     

The hypobranchial mucin of the whelk Buccinum undatum L. Properties of the mucin and of the glycoprotein component

1. The composition of the hypobranchial mucin from Buccinum undatum is reported. 2. The amino acid composition was determined; aspartic acid and glutamic acid contribute almost 24% of the total amino acids in the mucin. 3. Serine, threonine and alanine, in the proportions 2:1:1 respectively, were detected as N-terminal residues, implying the presence of at least four protein chains. 4. A glycoprotein component was isolated by phenol precipitation. 5. The glycoprotein contained 8% of neutral sugars comprising glucose, galactose, mannose and fucose, and 4.5% of hexosamine, comprising glucosamine and galactosamine in equal proportions. 6. A method is described for the preparation of glycopeptides from the glycoprotein. 7. The comparative biochemistry of the mucin is discussed.     

Biosynthesis of the Sindbis Virus Carbohydrates

The sequence in which sugars are added to the Sindbis virus glycoproteins was studied. Infected cells contain three glycosylated virus-specific proteins: the two virion glycoproteins and the immediate precursor to the smaller virion glycoprotein. Larger Sindbis-specific proteins are not glycosylated. The cell-associated forms of both of the virion glycoproteins contain glucosamine, mannose, galactose, and fucose. The glycosylated precursor contains only glucosamine, mannose, and some galactose. The conversion of precursor to virion protein involves both the addition of galactose and fucose and the loss of mannose. The apparent extent of glycosylation of each virus-specific protein is not influenced by the host cell.     

Purification and characterization of fish surface mucin

Fish surface mucin from Pampus argenteus was extracted with different organic solvents and the residue passed through Sephadex G-200. The major peak was purified by DEAE-Cellulose chromatography and five fractions were obtained. Carbohydrate and protein contents showed that major peak is a glycoprotein. Rechromatography of this component on the Sephadex G-200 column gave a single peak, with an estimated minimal molecular weight of 6.9 X 10(5). Analysis of individual sugar components revealed the presence of galactose, glucose, mannose, arabinose, N-acetyl glucosamine, N-acetyl galactosamine and sialic acid. The most represented amino acids are threonine, serine, proline, glutamic acid and glycine. The N-terminal amino acid end was blocked. Nearly 47% of sulphate was acid labile. Sialic acid and fucose were released rapidly by mild acid hydrolysis. The presence of blood group-A activity suggests that some kind of terminal alpha-Gal-NAC may be present.