Response of aggregating chick corneal cells to modifiers of N-linked oligosaccharides, endoglycosidase H and deoxymannojirimycin

1988 ◽  
Vol 89 (3) ◽  
pp. 405-413
Author(s):  
J. Overton
Keyword(s):  
Fine Structure ◽  
Present Report ◽  
Single Cells ◽  
Cellular Responses ◽  
Complex Type ◽  
Normal Complement ◽  
Sds Page ◽  
Moderate Rate ◽  
High Mannose ◽  
Endoglycosidase H

Chick corneal epithelium takes on its mature conformation between 11 and 16 days of incubation. Earlier work has shown that desmosome frequency increases during this period, reaching its highest rate at 15 1/2 days. In the present report aggregation rates of cells from embryos of 11 days and those of 15 1/2 days are compared. Younger cells, which form fewer desmosomes, aggregate at a more moderate rate than older cells. In addition, younger cells bind less concanavalin A (ConA) than older cells. To determine if increase in ConA binding could be related to these cellular responses, aggregating cells were exposed to endoglycosidase H (EndoH) and to deoxymannojirimycin. This treatment should permit comparison of the response of cells that have a normal complement of N-linked oligosaccharides with those that have reduced high-mannose or complex type sugars. The effectiveness of EndoH under the conditions used was confirmed by failure of treated glycoprotein after separation by SDS-PAGE and electroblotting to bind ConA. Aggregation rates of both older and younger cells were unaffected, as measured by disapperance of single cells, though older cells formed somewhat smaller aggregates at the highest dosage used. Desmosome formation was markedly reduced in the presence of the enzyme, even in the absence of other changes in the fine structure. At the highest dose of the enzyme the fine structure of older but not younger cells showed indications of blockage of transport. Deoxymannojirimycin appears to cause a build-up of high-mannose groups, since treated cells showed increased incorporation of [3H]mannose.(ABSTRACT TRUNCATED AT 250 WORDS)

Fine Structure of Cytochalasin Induced Polyploid Cells

1968 ◽  
Vol 26 ◽  
pp. 122-123
Author(s):  
Awtar Krishan ◽  
Nestor Bohonos
Keyword(s):  
Fine Structure ◽  
Cytochalasin B ◽  
Present Report ◽  
Cell Monolayer ◽  
Polyploid Cell ◽  
Specific Cell ◽  
Nuclear Surface ◽  
Unsuccessful Attempt ◽  
Daughter Cells ◽  
Polyploid Cells

Cytochalasin B, a mould metabolite from Helminthosporium dermatioideum has been shown to interfere with specific cell activities such as cytoplasmic cleavage and cell movement. Cells undergoing nuclear division in the presence of cytochalasin B are unable to complete the separation of the resulting daughter cells. In time-lapse studies, the daughter cells coalesce after an initial unsuccessful attempt at separation and form large multinucleate polyploid cells. The present report describes the fine structure of the large polyploid cells induced in Earle's L-cell monolayer cultures by exposure to cytochalasin B (lγ/ml) for 92 hours.In the present material we have seen as many as 7 nuclei in these polyploid cells. Treatment with cytochalasin B for longer periods of time (6 to 7 days, with one medium change on the 3rd day) did not increase the number of nuclei beyond the 7 nuclei stage. Figure 1 shows a large polyploid cell with four nuclei. These nuclei are indistinguishable in their fine structure from those of the cells from control cultures but often show unusually large numbers of cytoplasmic invaginations and extensions of the nuclear surface (Figure 2).

Uultrastructure of Microtubules

1972 ◽  
Vol 30 ◽  
pp. 252-253
Author(s):  
Ariaki Nagayama
Keyword(s):  
Fine Structure ◽  
Cultured Cells ◽  
Present Report ◽  
Confluent Monolayer ◽  
Purification Method ◽  
Vinca Rosea ◽  
L Cells ◽  
Antimitotic Activity ◽  
Monolayer Cultures ◽  
Rapid Purification

Vinblastine(Vb) or vincristine, alkaloid derived from Vinca rosea is known for its antimitotic activity by regrouping of microtubules into paracrystalline form within the cells. A rapid purification method of vinblastine-induced microtubular paracrystals(PC) has provided us with a fresh and pure microtubular material demonstrating the presence of a labile ATPase associated with the PC. The present report is concerned with the fine structure of purified microtubules of mammalian cultured cells.Confluent monolayer cultures of L cells were incubated for 20hrs with 10-5 M Vb (donated from Shionogi Seiyaku & Co., Osaka, Japan).

Identification of high-mannose and multiantennary complex-type N-linked glycans containing α-galactose epitopes from Nurse shark IgM heavy chain

2009 ◽  
Vol 26 (8) ◽  
pp. 1055-1064 ◽  
Author(s):  
David J. Harvey ◽  
Max Crispin ◽  
Beryl E. Moffatt ◽  
Sylvia L. Smith ◽  
Robert B. Sim ◽  
...  
Keyword(s):  
Heavy Chain ◽  
Complex Type ◽  
Nurse Shark ◽  
High Mannose

scholarly journals The Fine Structure of Synapses in the Ciliary Ganglion of the Chick

1960 ◽  
Vol 7 (1) ◽  
pp. 31-36 ◽  
Author(s):  
A. J. de Lorenzo
Keyword(s):  
Fine Structure ◽  
Synaptic Vesicles ◽  
Ganglion Cells ◽  
Single Cells ◽  
Synaptic Cleft ◽  
Structural Features ◽  
Ciliary Ganglion ◽  
Single Axon ◽  
Electron Microscopes ◽  
Electron Microscope Image

Ciliary ganglia of chick embryos and newly hatched chicks were examined in the light and electron microscopes. Particular attention was given to the fine structure of calyciform synapses, which are characteristically found in ciliary ganglia of birds. The calyciform endings are characterized by large expansions of the presynaptic axons upon ganglion cells, and the terminal processes extend over a considerable area of the cell surface. Often, indeed they appear to envelop the cell. In the electron microscope image, the appositional membranes are separated by a space about 300 to 400 A wide; i.e., the synaptic cleft. At irregularly spaced regions, the appositional membranes show areas of increased density. The presynaptic processes contain clusters of synaptic vesicles, localized at these dense regions. Thus the fine structure complex typical of other synapses is evident. The unique structural features of this synapse are as follows: (a) The calyx or presynaptic terminal derives from a single axon, does not arborize, and terminates upon a single ganglion cell. Thus, unlike the classical bouton terminal, this represents an anatomical device for firing single cells by single axons. (b) The surface area in contiguity, i.e., the area of appositional membranes, is far more extensive than the bouton terminal. The fine structure of this synapse is compared with others, for example, the classical boutons terminaux and purely electrical synapses, in an attempt to correlate fine structure with function.

scholarly journals Man-Specific, GalNAc/T/Tn-Specific and Neu5Ac-Specific Seaweed Lectins as Glycan Probes for the SARS-CoV-2 (COVID-19) Coronavirus

Marine Drugs ◽  
2020 ◽  
Vol 18 (11) ◽  
pp. 543
Author(s):  
Annick Barre ◽  
Els J.M. Van Damme ◽  
Mathias Simplicien ◽  
Hervé Benoist ◽  
Pierre Rougé
Keyword(s):  
Influenza Virus ◽  
Antiviral Agents ◽  
Host Cells ◽  
Carbohydrate Binding ◽  
Complex Type ◽  
Enveloped Viruses ◽  
High Mannose ◽  
Hiv 1 ◽  
Biomedical Interest

Seaweed lectins, especially high-mannose-specific lectins from red algae, have been identified as potential antiviral agents that are capable of blocking the replication of various enveloped viruses like influenza virus, herpes virus, and HIV-1 in vitro. Their antiviral activity depends on the recognition of glycoprotein receptors on the surface of sensitive host cells—in particular, hemagglutinin for influenza virus or gp120 for HIV-1, which in turn triggers fusion events, allowing the entry of the viral genome into the cells and its subsequent replication. The diversity of glycans present on the S-glycoproteins forming the spikes covering the SARS-CoV-2 envelope, essentially complex type N-glycans and high-mannose type N-glycans, suggests that high-mannose-specific seaweed lectins are particularly well adapted as glycan probes for coronaviruses. This review presents a detailed study of the carbohydrate-binding specificity of high-mannose-specific seaweed lectins, demonstrating their potential to be used as specific glycan probes for coronaviruses, as well as the biomedical interest for both the detection and immobilization of SARS-CoV-2 to avoid shedding of the virus into the environment. The use of these seaweed lectins as replication blockers for SARS-CoV-2 is also discussed.

scholarly journals The role of glycosylation in the biosynthesis and acquisition of ligand- binding activity of the folate-binding protein in cultured KB cells

Blood ◽  
1991 ◽  
Vol 77 (6) ◽  
pp. 1171-1180 ◽  
Author(s):  
CA Luhrs
Keyword(s):  
Ligand Binding ◽  
Binding Sites ◽  
Binding Protein ◽  
Binding Property ◽  
Affinity Matrix ◽  
Kb Cells ◽  
Folate Binding Protein ◽  
Binding Function ◽  
High Mannose ◽  
Endoglycosidase H

Abstract The biosynthesis, processing, and ligand-binding function of the membrane-associated and soluble forms of the folate-binding protein (FBP) in KB cells, a cultured human cell line, were studied using pulse- chase labeling with [35S] methionine. The intermediary and mature forms of the protein were isolated by immunoprecipitation and affinity chromatography and analyzed by sodium dodecyl sulfate electrophoresis and autoradiography. The earliest species identified had an Mr of 32 Kd and disappeared over 5 hours concomitant with the appearance of a 38-Kd cellular FBP. As the 38-Kd species disappeared, a 40-Kd form appeared in the medium. When tunicamycin was added to the culture medium to inhibit core glycosylation, a 26-Kd aglycosylated species and minor 28- Kd and 30-Kd forms appeared. Endoglycosidase H, which cleaves high mannose but not complex oligosaccharides, reduced the 32-Kd species to 26-Kd but the enzyme had no effect on the 38-Kd form, indicating that this species is complex glycosylated. Monensin, which blocks complex glycosylation, also inhibited synthesis of the 38-Kd species. Although both the 32-Kd and 38-Kd forms had ligand-binding sites (as demonstrated by binding to a folate-Sepharose matrix), the 26-Kd aglycosylated species, labeled in the presence of tunicamycin, lacked similar binding sites because it did not bind to the affinity matrix. In contrast, the aglycosylated 26-Kd form, which was obtained by treatment of the 32-Kd species with endoglycosidase H, did bind to the folate affinity matrix, indicating that it retained ligand-binding function. Thus, the high mannose oligosaccharide moiety is not required for the folate-binding property of the FBP, but its addition to the polypeptide chain precedes a later step that is necessary for the mature protein to have ligand-binding function.

Fine structure and cellular responses at the host–parasite interface in a range of fish–helminth systems

2015 ◽  
Vol 208 (3-4) ◽  
pp. 272-279 ◽  
Author(s):  
B.S. Dezfuli ◽  
T. Bo ◽  
M. Lorenzoni ◽  
A.P. Shinn ◽  
L. Giari
Keyword(s):  
Fine Structure ◽  
Cellular Responses ◽  
Host Parasite

scholarly journals Biosynthesis of complement C1 inhibitor by Hep G2 cells. Reactivity of different glycosylated forms of the inhibitor with C1s

1986 ◽  
Vol 237 (1) ◽  
pp. 93-98 ◽  
Author(s):  
M H Prandini ◽  
A Reboul ◽  
M G Colomb
Keyword(s):  
Hepatoma Cell ◽  
Hepatoma Cell Line ◽  
C1 Inhibitor ◽  
Hep G2 ◽  
Hep G2 Cells ◽  
Complex Type ◽  
Human Hepatoma Cell ◽  
Minor Form ◽  
A Minor ◽  
Endoglycosidase H

The biosynthesis of C1 Inh (C1 inhibitor) was studied in a human hepatoma cell line (Hep G2) by metabolic labelling, immunoprecipitation with anti-(C1 Inh) serum, analysis on SDS/polyacrylamide gel slabs and fluorography. Two forms of C1 Inh are secreted by Hep G2: a minor form of Mr 90,000 and a major form of Mr approximately 100,000. The latter form is also found in small amounts intracellularly in co-existence with an 80,000-Mr form. Accumulation of the 80,000-Mr C1 Inh is favoured when the cells are labelled at 23 degrees C instead of 37 degrees C or when they are treated with monensin. In the presence of tunicamycin, a compound that blocks the formation of N-asparagine-linked oligosaccharide chains, a decrease in Mr of both secreted and intracellular major forms is observed, indicating that secreted and intracellular C1 Inh contain N-linked oligosaccharide units. The 100,000 Mr secreted C1 Inh is sensitive to endoglycosidase F but resistant to endoglycosidase H, and it incorporates [3H]galactose, [3H]glucosamine and [3H]galactosamine, indicating the presence of both N-linked oligosaccharides of the complex type and O-linked oligosaccharides. The intracellular C1 Inh contains N-linked oligosaccharide units of the high-mannose type as demonstrated by endoglycosidase H-sensitivity. The functional activity of C1 Inh during its biosynthesis was tested by studying its reactivity towards C1s. Both secreted and intracellular C1 Inh form covalent-like complexes with purified plasma C1s. The underglycosylated C1 Inh secreted in presence of tunicamycin is still reactive with purified C1s. These results clearly show that sugars are not essential for this inhibitory activity of C1 Inh.

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