Glycoconjugates on the surface of spores of the pathogenic fungus Phytophthora cinnamomi studied using fluorescence and electron microscopy and flow cytometry

1990 ◽  
Vol 36 (3) ◽  
pp. 183-192 ◽  
Author(s):  
A. R. Hardham ◽  
E. Suzaki
Keyword(s):  
Flow Cytometry ◽  
Plasma Membrane ◽  
Cell Surface ◽  
Phytophthora Cinnamomi ◽  
Pathogenic Fungus ◽  
Fluorescein Isothiocyanate ◽  
Pathogenic Fungi ◽  
Surface Flow ◽  
Soybean Agglutinin ◽  
Binding Material

Glycoconjugates on the surface of zoospores and cysts of the pathogenic fungus Phytophthora cinnamomi have been studied using fluorescein isothiocyanate labelled lectins for fluorescence microscopy and flow cytometry, and ferritin- and gold-labelled lectins for ultrastructural analysis. Of the five lectins used, only concanavalin A (ConA) binds to the surface of the zoospores, including the flagella and water expulsion vacuole. This suggests that of accessible saccharides, glucosyl or mannosyl residues predominate on the outer surface of the zoospore plasma membrane. Early in encystment, a system of flat disc-like cisternae, which underlie the zoospore plasma membrane, vesiculate. These and other small peripheral vesicles quickly disappear. After the induction of encystment, ConA is no longer localised close to the plasma membrane but binds to material loosely associated with the cell surface. Quantitative measurements by flow cytometry indicate that the ConA-binding material is gradually lost from the cell surface. The cyst wall is weakly labelled, but the site of germ tube emergence stains intensely. During the first 2 min after the induction of encystment, material that binds soybean agglutinin, Helix pommatia agglutinin, and peanut agglutinin appears on the surface of the fungal cells. The distribution of this material, rich in galactosyl or N-acetyl-D-galactosaminosyl residues, is initially patchy, but by 5 min the material evenly coats most of the cell surface. Labelling of zoospores in which intracellular sites are accessible indicates that the soybean agglutinin binding material is stored in vesicles that lie beneath the plasma membrane. Quantitation of soybean agglutinin labelling shows that maximum binding occurs 2–3 min after the induction of encystment. Key words: cell surface, flow cytometry, lectins, pathogenic fungi, Phytophthora cinnamomi.

scholarly journals Studies on the cell surface of zoospores and cysts of the fungus Phytophthora cinnamomi: The influence of fixation on patterns of lectin binding.

1985 ◽  
Vol 33 (2) ◽  
pp. 110-118 ◽  
Author(s):  
A R Hardham
Keyword(s):  
Electron Microscopy ◽  
Cell Surface ◽  
Binding Sites ◽  
Phytophthora Cinnamomi ◽  
Specific Binding ◽  
Lectin Binding ◽  
Fluorescein Isothiocyanate ◽  
Soybean Agglutinin ◽  
Intracellular Binding

The study of the surface properties of zoospores and cysts of the fungus Phytophthora cinnamomi required a fixation regime that would preserve the cells adequately and not interfere with binding and detection of probes on the cell surface. When they were fixed in 4% formaldehyde (F), specific binding of concanavalin A-fluorescein isothiocyanate and rhodamine-labeled soybean agglutinin was obtained. However, electron microscopy showed that preservation was so poor that intracellular binding sites had become exposed. By contrast glutaraldehyde (G), even at concentrations as low as 0.05%, gave good preservation of the zoospores but induced high levels of nonspecific fluorescence, making its use impractical for studies using fluorescent probes. Addition of 1-4% F to 0.05-0.8% G reduced the level of G-induced fluorescence while not diminishing the quality of ultrastructural preservation. This effect was evaluated quantitatively and an optimum fixation regime for the fungal cells, namely, 0.2% G and 2-4% F in 50 mM PIPES buffer, was determined. This combined fixative facilities correlated fluorescence and ultrastructural labeling with lectins and immunocytochemical probes.

scholarly journals Agonist-induced internalization of the substance P (NK1) receptor expressed in epithelial cells

1994 ◽  
Vol 303 (1) ◽  
pp. 177-186 ◽  
Author(s):  
A M Garland ◽  
E F Grady ◽  
D G Payan ◽  
S R Vigna ◽  
N W Bunnett
Keyword(s):  
Plasma Membrane ◽  
Substance P ◽  
Cell Surface ◽  
Fluorescein Isothiocyanate ◽  
Nk1 Receptor ◽  
Early Endosomes ◽  
A Cell ◽  
Acid Wash ◽  
Intracellular Vesicles ◽  
Receptor Antibodies

Internalization of the NK1 receptor (NK1R) and substance P was observed in cells transfected with cDNA encoding the rat NK1R by using anti-receptor antibodies and cyanine 3-labelled substance P (cy3-substance P). After incubation at 4 degrees C, NK1R immunoreactivity and cy3-substance P were confined to the plasma membrane. Within 3 min of incubation at 37 degrees C, NK1R immunoreactivity and cy3-substance P were internalized into small intracellular vesicles located beneath the plasma membrane. Fluorescein isothiocyanate-labelled transferrin and cy3-substance P were internalized into the same vesicles, identifying them as early endosomes. After 60 min at 37 degrees C, NK1R immunoreactivity was detected in larger, perinuclear vesicles. Internalization of 125I-labelled substance P was studied by using an acid wash to dissociate cell-surface label from that which has been internalized. Binding reached equilibrium after incubation for 60 min at 4 degrees C with no detectable internalization. After 10 min incubation at 37 degrees C, 83.5 +/- 1.0% of specifically bound counts were internalized. Hyperosmolar sucrose and phenylarsine oxide, which are inhibitors of endocytosis, prevented internalization of 125I-labelled substance P and accumulation of NK1R immunoreactivity into endosomes. Acidotropic agents caused retention of 125I-labelled substance P within the cell and inhibited degradation of the internalized peptide. Continuous incubation of cells with substance P at 37 degrees C reduced 125I-substance P binding at the cell surface. Therefore, substance P and its receptor are internalized into early endosomes within minutes of binding, and internalized substance P is degraded. Internalization depletes NK1Rs from the cell surface and may down-regulate the response of a cell to substance P.

scholarly journals The PbMDJ1 Gene Belongs to a Conserved MDJ1/LON Locus in Thermodimorphic Pathogenic Fungi and Encodes a Heat Shock Protein That Localizes to both the Mitochondria and Cell Wall of Paracoccidioides brasiliensis

2006 ◽  
Vol 5 (2) ◽  
pp. 379-390 ◽  
Author(s):  
Wagner L. Batista ◽  
Alisson L. Matsuo ◽  
Luciane Ganiko ◽  
Tânia F. Barros ◽  
Thiago R. Veiga ◽  
...  
Keyword(s):  
Cell Wall ◽  
Heat Shock ◽  
Cell Surface ◽  
Paracoccidioides Brasiliensis ◽  
Pathogenic Fungus ◽  
Fungal Growth ◽  
Pathogenic Fungi ◽  
Yeast Cells ◽  
Shock Proteins

ABSTRACT J-domain (DnaJ) proteins, of the Hsp40 family, are essential cofactors of their cognate Hsp70 chaperones, besides acting as independent chaperones. In the present study, we have demonstrated the presence of Mdj1, a mitochondrial DnaJ member, not only in the mitochondria, where it is apparently sorted, but also in the cell wall of Paracoccidioides brasiliensis, a thermodimorphic pathogenic fungus. The molecule (PbMdj1) was localized to fungal yeast cells using both confocal and electron microscopy and also flow cytometry. The anti-recombinant PbMdj1 antibodies used in the reactions specifically recognized a single 55-kDa mitochondrial and cell wall (alkaline β-mercaptoethanol extract) component, compatible with the predicted size of the protein devoid of its matrix peptide-targeting signal. Labeling was abundant throughout the cell wall and especially in the budding regions; however, anti-PbMdj1 did not affect fungal growth in the concentrations tested in vitro, possibly due to the poor access of the antibodies to their target in growing cells. Labeled mitochondria stood preferentially close to the plasma membrane, and gold particles were detected in the thin space between them, toward the cell surface. We show that Mdj1 and the mitochondrial proteinase Lon homologues are heat shock proteins in P. brasiliensis and that their gene organizations are conserved among thermodimorphic fungi and Aspergillus, where the genes are adjacent and have a common 5′ region. This is the first time a DnaJ member has been observed on the cell surface, where its function is speculative.

Flow cytometry analysis of coxsackievirus B receptors expression in human CaCo-2 cells

2014 ◽  
Vol 9 (7) ◽  
pp. 699-707
Author(s):  
Samira Riabi ◽  
Rafik Harrath ◽  
Imed Gaâloul ◽  
Hind Hamzeh-Cognasse ◽  
Olivier Délezay ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Cell Surface ◽  
Expression Patterns ◽  
Surface Expression ◽  
Surface Flow ◽  
Surface Proteins ◽  
Flow Cytometry Analysis ◽  
Coxsackie Adenovirus Receptor ◽  
Coxsackievirus B ◽  
Adenovirus Receptor

AbstractA subset of coxsackieviruses B (CV-B) is able to initiate intestinal infection via the attachment to two cell surface proteins, decayaccelerating factor (DAF) and coxsackie adenovirus receptor (CAR). The aim of the present study was to investigate the expression pattern of these receptors in the polarized CaCo-2 cell line using flow cytometry. The expression of CAR-specific mRNA and proteins was analyzed by reverse transcriptase polymerase chain reaction and western blotting, respectively. Flow cytometry analysis was used to study the surface expression patterns of CAR and DAF. CAR and DAF were well detected at the surface of CaCo-2 cells by flow cytometry. Despite the fact that CAR was susceptible to the action of trypsin, a few amounts of the latter enzyme and a precise dilution did not impair its correct detection by flow cytometry. This technique was used to demonstrate that the density of cells did not influence the expression of CAR at the cell surface. CaCo-2 cells express high levels of CAR and DAF at their surface. Flow cytometry, if used adequately, represents a helpful tool for the study of the interactions between these cells and various viral targets.

scholarly journals Dexamethasone reduces cell surface levels of CD11b on human eosinophils

1997 ◽  
Vol 6 (5-6) ◽  
pp. 363-367 ◽  
Author(s):  
A. M. Das ◽  
L. H. K. Lim ◽  
R. J. Flower ◽  
M. Perretti
Keyword(s):  
Flow Cytometry ◽  
Plasma Membrane ◽  
Cell Surface ◽  
Mechanism Of Action ◽  
Allergic Inflammation ◽  
Inhibitory Effect ◽  
Glucocorticoid Hormones ◽  
Glucocorticoid Hormone ◽  
Overnight Incubation ◽  
Lower Expression

Overnight incubation of human eosinophils (Eøs) with the glucocorticoid hormone dexamethasone (DEX; 0.1 μM) resulted in lower expression of the CD11b, but not CD49d, antigen on their plasma membrane, as assessed by flow cytometry. DEX produced a consistent inhibitory effect (ranging from 16% to 20%) when tested at a concentration of 0.1 μM. Eø stimulation with 100 ng/ml eotaxin produced an increase in CD11b (+26%), but not CD11c, levels and concomitantly a reduction (–25%) on CD62L expression. The inhibition exerted by DEX upon CD11b levels was also evident following eotaxin upregulation, with a degree of inhibition similar to that seen on basal levels. These data highlight a novel mechanism of action by which glucocorticoid hormones may be effective in reducing Eø accumulation during allergic inflammation in man.

scholarly journals Studies on the cell surface of zoospores and cysts of the fungus Phytophthora cinnamomi: nature of the surface saccharides as determined by quantitative lectin binding studies.

1985 ◽  
Vol 33 (5) ◽  
pp. 384-388 ◽  
Author(s):  
A Bacic ◽  
M L Williams ◽  
A E Clarke
Keyword(s):  
Cell Surface ◽  
Concanavalin A ◽  
Wheat Germ Agglutinin ◽  
Wheat Germ ◽  
Phytophthora Cinnamomi ◽  
Lectin Binding ◽  
Soybean Agglutinin ◽  
Binding Studies ◽  
Con A

The nature of the surface saccharides of zoospores, "partially encysted zoospores" and cysts of the root-rotting fungus Phytophthora cinnamomi, has been examined by quantitative lectin binding studies. Zoospores bound concanavalin A (Con A), but did not bind any of a variety of other lectins tested. In contrast, both cysts and "partially encysted zoospores" bound soybean agglutinin (SBA) as well as Con A. This indicates that accessible alpha-D-glucosyl/alpha-D-mannosyl-containing glycoconjugates predominate at the zoospore surface, whereas both alpha-D-glucosyl/alpha-D-mannosyl and galactosyl and/or N-acetyl-D-galactosaminosyl residues are accessible at the surface of cysts and "partially encysted zoospores." Neither Ulex europeus lectin nor wheat germ agglutinin (WGA) bound to any of the three cell preparations, indicating the absence of accessible alpha-L-fucosyl and N-acetyl-D-glucosaminosyl residues.

scholarly journals Misfolded GPI-anchored proteins are escorted through the secretory pathway by ER-derived factors

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Eszter Zavodszky ◽  
Ramanujan S Hegde
Keyword(s):  
Flow Cytometry ◽  
Plasma Membrane ◽  
Cell Surface ◽  
Quantitative Proteomics ◽  
Mammalian Cells ◽  
Secretory Pathway ◽  
Flow Cytometry Analysis ◽  
Time Resolved ◽  
Interaction Partners ◽  
Quantitative Flow

We have used misfolded prion protein (PrP*) as a model to investigate how mammalian cells recognize and degrade misfolded GPI-anchored proteins. While most misfolded membrane proteins are degraded by proteasomes, misfolded GPI-anchored proteins are primarily degraded in lysosomes. Quantitative flow cytometry analysis showed that at least 85% of PrP* molecules transiently access the plasma membrane en route to lysosomes. Unexpectedly, time-resolved quantitative proteomics revealed a remarkably invariant PrP* interactome during its trafficking from the endoplasmic reticulum (ER) to lysosomes. Hence, PrP* arrives at the plasma membrane in complex with ER-derived chaperones and cargo receptors. These interaction partners were critical for rapid endocytosis because a GPI-anchored protein induced to misfold at the cell surface was not recognized effectively for degradation. Thus, resident ER factors have post-ER itineraries that not only shield misfolded GPI-anchored proteins during their trafficking, but also provide a quality control cue at the cell surface for endocytic routing to lysosomes.

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