scholarly journals Biosynthesis of mucins in bovine trachea: identification of the major radiolabelled species

1998 ◽  
Vol 333 (2) ◽  
pp. 449-456 ◽  
Author(s):  
Naila SVITACHEVA ◽  
Hans W. HOVENBERG ◽  
Julia R. DAVIES
Keyword(s):  
Heparan Sulphate ◽  
Goblet Cells ◽  
High Density ◽  
Surface Epithelium ◽  
Low Density ◽  
Pulse Labelling ◽  
Monomeric Species ◽  
Submucosal Glands ◽  
Mucus Gel ◽  
Two Populations

Bovine trachea in organ culture secretes mucus containing a ‘high-density ’ (1.46 g/ml) and a ‘low-density ’ (1.37 g/ml) mucin similar to those identified previously in bovine respiratory secretions [Hovenberg, Carlstedt and Davies (1997) Biochem. J. 321, 117–123]. After pulse-labelling, autoradiography showed uptake of [35S]sulphate by both epithelial goblet cells and submucosal glands, while [3H]proline was mainly incorporated into the ciliated surface epithelial cells. After 24 h of radiolabelling, neither the high- nor the low-density mucin in the secreted mucus gel was heavily radiolabelled with the precursors. In contrast, a population of molecules banding at 1.50 g/ml was heavily radiolabelled with [35S]sulphate. This component was smaller than the high-density mucin from the mucus gel and was insensitive to reduction or digestion with chondroitin ABC lyase or heparan sulphate lyase. The molecules yielded two populations of high-Mr glycopeptides upon trypsin digestion, were sensitive to keratanase and endo-β-galactosidase digestion and contained O-linked glycans. Extracts of the surface epithelium and submucosal tissue after radiolabelling showed that the high- and low-density mucins in the tissue were also poorly radiolabelled. Thus, under these conditions, the radiolabelled precursors were not effectively incorporated into the large oligomeric mucins but into a high-Mr monomeric species. This study suggests that data obtained in investigations where mucins are radiolabelled and studied without further separation into distinct components may rather reflect the turnover of this ‘novel ’ monomeric species than the large oligomeric mucins.

scholarly journals Mucus glycoproteins in bovine trachea: identification of the major mucin populations in respiratory secretions and investigation of their tissue origins

1997 ◽  
Vol 321 (1) ◽  
pp. 117-124 ◽  
Author(s):  
Hans W. HOVENBERG ◽  
Ingemar CARLSTEDT ◽  
Julia R. DAVIES
Keyword(s):  
Gradient Centrifugation ◽  
Complex Mixture ◽  
Goblet Cells ◽  
High Density ◽  
Surface Epithelium ◽  
Low Density ◽  
Submucosal Glands ◽  
Mucus Gel ◽  
Soluble Species ◽  
Gel Phase

Bovine respiratory secretions were separated into gel and sol phases to allow the identification of the gel-forming mucins. Mucins were subsequently isolated from the surface epithelium and submucosal tissue to investigate the tissue origins of the species in the secretions. Density-gradient centrifugation revealed ‘high-density’ and ‘low-density’ mucins in the gel phase of the secretions. The ‘high-density’ mucins were large, composed of subunits joined by disulphide bonds and contained two highly glycosylated domains of apparently different lengths, whereas the ‘low-density’ mucins were smaller and monomeric. The sol also contained both ‘high-density’ and ‘low-density’ species. A ‘high-density’ mucin similar to that in the gel was isolated from the surface epithelium, suggesting that the goblet cells produce large, gel-forming mucins. A second ‘high-density’ species was released from the submucosal tissue after reduction/alkylation, indicating that large mucins from the submucosal glands may also be a component of the mucus gel. In addition, two small, ‘low-density’ mucins were obtained from the submucosal tissue. One species was associated with the gel phase but was also present in the sol, whereas the other was present only in the sol. Bovine respiratory-tract secretions thus comprise a complex mixture of large gel-forming mucins originating from the goblet cells and submucosal glands, and smaller ‘soluble’ species from the submucosal glands which may interact with the gel.

scholarly journals Mucus glycoproteins from pig gastric mucosa: identification of different mucin populations from the surface epithelium

1997 ◽  
Vol 326 (3) ◽  
pp. 903-910 ◽  
Author(s):  
Henrik NORDMAN ◽  
Julia R. DAVIES ◽  
Annkatrin HERRMANN ◽  
Niclas G. KARLSSON ◽  
Gunnar C. HANSSON ◽  
...  
Keyword(s):  
Gradient Centrifugation ◽  
Buoyant Density ◽  
High Density ◽  
Surface Epithelium ◽  
Low Density ◽  
Guanidinium Chloride ◽  
Gastric Mucus ◽  
High Iron ◽  
Cardiac Region ◽  
Ion Exchange Hplc

Pig gastric mucins were isolated from the surface epithelium of the cardiac region, corpus and antrum using density-gradient centrifugation after extraction in 6 M guanidinium chloride. In CsCl/0.5 M guanidinium chloride, mucins solubilized from the cardiac region appeared as a broad unimodal band at 1.52 g/ml whereas those from the corpus and antrum occurred as high- and low-density populations at 1.50 and 1.45 g/ml respectively. High-iron diamine reacted more strongly with the cardiac mucins and the high-density populations from corpus and antrum than with the two low-density ones. In keeping with this, approx. 60% of the oligosaccharides from the former mucins and 20% from the latter contained sulphate. All surface epithelial cells of the cardiac region stained with high-iron diamine, whereas in the corpus only the epithelium in the bottom of the pits reacted, suggesting that the high-density population from this region originates from these cells. Mucins from all regions were composed of subunits, each containing highly glycosylated domains. The mucins from the cardiac region were larger than those from the corpus and antrum, and reduced subunits as well as high-molecular-mass glycopeptides from the cardiac mucins were larger than the corresponding fragments from the other regions. Ion-exchange HPLC showed that reduced subunits from the cardiac mucins and the high-density populations from the corpus and antrum were more ‘acidic’ than reduced subunits from the two low-density ones. All mucins contained a ‘neutral’ fraction, in particular those from the antrum. Pig gastric mucus thus contains a number of distinctly different mucin populations varying in buoyant density, size, ‘acidity’, glycosylation, sulphation and tissue origin.

scholarly journals Different mucins are produced by the surface epithelium and the submucosa in human trachea: identification of MUC5AC as a major mucin from the goblet cells

1996 ◽  
Vol 318 (1) ◽  
pp. 319-324 ◽  
Author(s):  
Hans W HOVENBERG ◽  
Julia R DAVIES ◽  
Ingemar CARLSTEDT
Keyword(s):  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Goblet Cells ◽  
Major Product ◽  
Surface Epithelium ◽  
Epithelial Surface ◽  
Predominant Species ◽  
Submucosal Glands ◽  
Ion Exchange Hplc ◽  
Human Trachea

Mucins were extracted from the epithelial surface and the submucosal tissue of human trachea in order to enrich glycoproteins from the goblet cells and the submucosal glands respectively. The macromolecules were purified using density-gradient centrifugation, and the presence of the MUC5AC mucin was investigated using an antiserum raised against a synthetic peptide based on the sequence of the MUC5AC apoprotein. Mucins from the surface epithelium showed a higher reactivity with the antiserum relative to carbohydrate than those from the submucosa, and ion-exchange HPLC of reduced subunits revealed the presence of two distinct mucin populations in the samples. The predominant species from the surface epithelium was more acidic than the major population from the submucosa and showed a strong reactivity with the anti-MUC5AC antiserum. In contrast, the major portion of the submucosal mucins were less acidic and showed no MUC5AC reactivity, although a more acidic population did react with the antibody. Rate-zonal centrifugation showed that the MUC5AC mucin from the surface epithelium is smaller than the major submucosal mucin, and that both are composed of subunits. Immunolocalization confirmed that the MUC5AC mucin from human trachea originates from the goblet cells and that this glycoprotein is not a major product of the submucosal glands.

scholarly journals Biosynthesis of respiratory-tract mucins. A comparison of canine epithelial goblet-cell and submucosal-gland secretions

1973 ◽  
Vol 136 (4) ◽  
pp. 845-850 ◽  
Author(s):  
Glenn H. Stahl ◽  
Daniel B. Ellis
Keyword(s):  
Goblet Cell ◽  
Culture System ◽  
Goblet Cells ◽  
Surface Epithelium ◽  
Basal Cells ◽  
Submucosal Gland ◽  
Agarose Gels ◽  
Organ Culture System ◽  
Submucosal Glands ◽  
Glandular Structures

1. A modified canine tracheal organ culture system was used to investigate differences between mucous secretions of epithelial goblet cells and the submucosal glands. 2. Denuded explants were prepared by removing goblet, ciliated and basal cells from the surface epithelium leaving an intact basement membrane and viable submucosa. 3. Denuded explants actively incorporated radioactive precursors into secreted macromolecules when cultured in medium 199 containing label. 4. Chromatography on Bio-Gel A-150m and electrophoresis on 1% agarose gels indicated that epithelial goblet cell secretions were relatively more sulphated than submucosal glandular secretions. 5. The glandular structures were shown to respond to a parasympathomimetic agent.

scholarly journals Kinetic study of T lymphocytes after sensitization against soluble antigen. III. Potentiation and suppression of the PHA response by antigen-activated lymphocytes of low density.

1975 ◽  
Vol 142 (4) ◽  
pp. 1017-1022 ◽  
Author(s):  
J A Bash ◽  
H G Durkin ◽  
B H Waksman
Keyword(s):  
Buoyant Density ◽  
High Density ◽  
Soluble Antigen ◽  
Low Density ◽  
Constant Number ◽  
Activated Lymphocytes ◽  
Density Fractions ◽  
Lymph Node Cells ◽  
Two Populations ◽  
Pha Response

Lymph node cells of ovalbumin-sensitized rats were separated on the basis of buoyant density into fractions reciprocally enriched in cells responsive to ovalbumin or phytohemagglutinin (PHA). Recombination of high density and low density fractions in varying proportions resulted in potentiation or suppression of the DNA synthetic response to PHA in culture. The response of cultures containing equal numbers of high and low density cells was markedly greater than the sum of the two populations stimulated separately. However, when decreasing numbers of low density cells were cultured with a constant number of high density cells, profound suppression was observed.

Quantitative defect studies in semiconductor TEM samples prepared by low angle ion milling

1995 ◽  
Vol 53 ◽  
pp. 512-513
Author(s):  
L. Mulestagno ◽  
J.C. Holzer ◽  
P. Fraundorf
Keyword(s):  
Sample Preparation ◽  
Milling Time ◽  
High Density ◽  
Low Density ◽  
Ion Milling ◽  
High Quality ◽  
Variable Angle ◽  
Major Disadvantage ◽  
Induced Defects

Due to the wealth of information, both analytical and structural that can be obtained from it TEM always has been a favorite tool for the analysis of process-induced defects in semiconductor wafers. The only major disadvantage has always been, that the volume under study in the TEM is relatively small, making it difficult to locate low density defects, and sample preparation is a somewhat lengthy procedure. This problem has been somewhat alleviated by the availability of efficient low angle milling.Using a PIPS® variable angle ion -mill, manufactured by Gatan, we have been consistently obtaining planar specimens with a high quality thin area in excess of 5 × 104 μm2 in about half an hour (milling time), which has made it possible to locate defects at lower densities, or, for defects of relatively high density, obtain information which is statistically more significant (table 1).

Scanning Electron Microscopic and Electrophoretic Observations on Barium Sulphate Used to Adsorb Clotting Factors

1975 ◽  
Vol 33 (02) ◽  
pp. 256-270
Author(s):  
R. M Howell ◽  
S. L. M Deacon
Keyword(s):  
Electron Microscopy ◽  
Factor Xa ◽  
Barium Sulphate ◽  
High Density ◽  
Low Density ◽  
Factor X ◽  
Clotting Factors ◽  
Electron Microscopic ◽  
Complementary Techniques ◽  
Scanning Electron

SummaryElectron microscopy and particle electrophoresis were found to be complementary techniques with which to complete the physical data from an earlier study on barium sulphates used to adsorb clotting factors from serum. The differences revealed by scanning electron microscopy (S. E. M.) in the physical shape of low and high density grades of barium sulphate particles appear to be of greater significance than charge as expressed by electrophoretic mobility, in determining whether or not precursor or preformed factor Xa is eluted.This conclusion was based on the finding that at pH values close to 7, where the adsorption from serum occurs, all samples with the exception of natural barytes were uncharged. However as the high-density, or soil-grade, was found by S. E. M. to consist of large solid crystals it was suggested that this shape might induce activation of factor X as a result of partial denaturation and consequent unfolding of the adsorbed protein. In contrast, uptake of protein into the centre of the porous aggregates revealed by S. E. M. pictures of low-density or X-ray grade barium sulphate may afford protection against denaturation and exposure of the enzyme site.The porous nature of particles of low-density barium sulphate compared with the solid crystalline forms of other grades accounts not only for its lower bulk density but also for its greater surface/gram ratio which is reflected by an ability to adsorb more protein from serum.Neither technique produced evidence from any of the samples to indicate the presence of stabilising agents sometimes used to coat particles in barium meals.

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