The pegs on the decorated tubules of the contractile vacuole complex of Paramecium are proton pumps

1995 ◽  
Vol 108 (10) ◽  
pp. 3163-3170 ◽  
Author(s):  
A.K. Fok ◽  
M.S. Aihara ◽  
M. Ishida ◽  
K.V. Nolta ◽  
T.L. Steck ◽  
...  
Keyword(s):  
Potent Inhibitor ◽  
Polyclonal Antibodies ◽  
Immunogold Labeling ◽  
Contractile Vacuole ◽  
Proton Pumps ◽  
Minimal Effect ◽  
Chromaffin Granules ◽  
B Subunit ◽  
Antigenic Sites ◽  
Immunofluorescence Studies

Our previous study has shown that the decorated tubules (collectively known as the decorated spongiome) of the contractile vacuole complex (CVC) in Paramecium are the site of fluid segregation, as the binding of microinjected monoclonal antibody (mAb) DS-1 to the tubules reduced the CVC's fluid output. In this study, we showed by immunogold labeling on cryosections that the antigenic sites for mAb DS-1 were located on the 15 nm ‘pegs’ protruding from the cytosolic surface of the decorated tubules. In immunofluorescence studies, both polyclonal antibodies against the subunits of the V-ATPase of Dictyostelium discoideum and against the 57 kDa B-subunit of the V-ATPase of chromaffin granules gave identical labeling patterns to that produced by mAb DS-1. On cryosections, all three antigens were located most consistently near or on the pegs of the decorated tubules. These data support the notion that the pegs on the membrane of the decorated tubules represent the V1 complex of a proton pump. Concanamycin B, a potent inhibitor of V-ATPase activity and of acidification of lysosomes and endosomes, strongly and reversibly inhibited fluid output from the CVC but had minimal effect on the integrity of the decorated spongiome as observed by immunofluorescence. Such inhibition suggests that a V-ATPase is intimately involved in fluid segregation. Exposing Paramecium to 12 degrees C or 1 degrees C for 30 minutes resulted in the dissociation of the decorated tubules from the smooth spongiome that borders the collecting canals; thus the DS-1-reactive A4 antigen, the 75 kDa and 66 kDa antigens were all found dispersed in the cytosol.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals The centrin-based cytoskeleton of Chlamydomonas reinhardtii: distribution in interphase and mitotic cells.

1988 ◽  
Vol 107 (2) ◽  
pp. 635-641 ◽  
Author(s):  
J L Salisbury ◽  
A T Baron ◽  
M A Sanders
Keyword(s):  
Nuclear Envelope ◽  
Polyclonal Antibodies ◽  
Flagellar Apparatus ◽  
Immunogold Labeling ◽  
Basal Bodies ◽  
Flagellar Roots ◽  
Cell Biol ◽  
Immunofluorescence Studies ◽  
Descending Fibers

Monoclonal and polyclonal antibodies raised against algal centrin, a protein of algal striated flagellar roots, were used to characterize the occurrence and distribution of this protein in interphase and mitotic Chlamydomonas cells. Chlamydomonas centrin, as identified by Western immunoblot procedures, is a low molecular (20,000-Mr) acidic protein. Immunofluorescence and immunogold labeling demonstrates that centrin is a component of the distal fiber. In addition, centrin-based flagellar roots link the flagellar apparatus to the nucleus. Two major descending fibers extend from the basal bodies toward the nucleus; each descending fiber branches several times giving rise to 8-16 fimbria which surround and embrace the nucleus. Immunogold labeling indicates that these fimbria are juxtaposed to the outer nuclear envelope. Earlier studies have demonstrated that the centrin-based linkage between the flagellar apparatus and the nucleus is contractile, both in vitro and in living Chlamydomonas cells (Wright, R. L., J. Salisbury, and J. Jarvik. 1985. J. Cell Biol. 101:1903-1912; Salisbury, J. L., M. A. Sanders, and L. Harpst. 1987. J. Cell Biol. 105:1799-1805). Immunofluorescence studies show dramatic changes in distribution of the centrin-based system during mitosis that include a transient contraction at preprophase; division, separation, and re-extension during prophase; and a second transient contraction at the metaphase/anaphase boundary. These observations suggest a fundamental role for centrin in motile events during mitosis.

scholarly journals Proton pumps populate the contractile vacuoles of Dictyostelium amoebae.

1993 ◽  
Vol 121 (6) ◽  
pp. 1311-1327 ◽  
Author(s):  
J Heuser ◽  
Q Zhu ◽  
M Clarke
Keyword(s):  
Pure Water ◽  
Video Recording ◽  
Freeze Fracture ◽  
Time Lapse ◽  
Contractile Vacuole ◽  
Proton Pumps ◽  
Fluid Accumulation ◽  
Styryl Dyes ◽  
B Subunit ◽  
Contractile Vacuoles

Amoebae of the eukaryotic microorganism Dictyostelium discoideum were found to contain an interconnected array of tubules and cisternae whose membranes were studded with 15-nm-diameter "pegs." Comparison of the ultrastructure and freeze-fracture behavior of these pegs with similar structures found in other cells and tissues indicated that they were the head domains of vacuolar-type proton pumps. Supporting this identification, the pegs were observed to decorate and clump when broken amoebae were exposed to an antiserum against the B subunit of mammalian vacuolar H(+)-ATPase. The appearance of the peg-rich cisternae in quick-frozen amoebae depended on their osmotic environment: under hyperosmotic conditions, the cisternae were flat with many narrow tubular extensions, while under hypo-osmotic conditions the cisternae ranged from bulbous to spherical. In all cases, however, their contents deep etched like pure water. These properties indicated that the interconnected tubules and cisternae comprise the contractile vacuole system of Dictyostelium. Earlier studies had demonstrated that contractile vacuole membranes in Dictyostelium are extremely rich in calmodulin (Zhu, Q., and M. Clarke, 1992, J. Cell Biol. 118: 347-358). Light microscopic immunofluorescence confirmed that antibodies against the vacuolar proton pump colocalized with anti-calmodulin antibodies on these organelles. Time-lapse video recording of living amoebae imaged by interference-reflection microscopy, or by fluorescence microscopy after staining contractile vacuole membranes with potential-sensitive styryl dyes, revealed the extent and dynamic interrelationship of the cisternal and tubular elements in Dictyostelium's contractile vacuole system. The high density of proton pumps throughout its membranes suggests that the generation of a proton gradient is likely to be an important factor in the mechanism of fluid accumulation by contractile vacuoles.

Vacuolar H(+)-ATPase of Dictyostelium discoideum. A monoclonal antibody study

1993 ◽  
Vol 106 (4) ◽  
pp. 1103-1113 ◽  
Author(s):  
A.K. Fok ◽  
M. Clarke ◽  
L. Ma ◽  
R.D. Allen
Keyword(s):  
Monoclonal Antibodies ◽  
Indirect Immunofluorescence ◽  
Membrane Fraction ◽  
Contractile Vacuole ◽  
Proton Pumps ◽  
Significant Extent ◽  
Chromaffin Granule ◽  
Thin Sections ◽  
B Subunit ◽  
Cell Biol

A Dictyostelium membrane fraction rich in vacuolar proton pumps, previously described by Nolta et al. (J. Biol. Chem. 266, 18,318-18,323, 1991), was used as the immunogen for production of monoclonal antibodies. We obtained antibodies that recognized polypeptides of 100 kDa and 68 kDa, corresponding to the two largest subunits of the vacuolar proton pump. In indirect immunofluorescence experiments, these two subunits were located on an interconnected collection of tubules and vacuoles. On frozen thin sections they were found principally on membranes of vacuoles and collections of small vesicles typically located just internal to the plasma membrane. These vesicles and vacuoles had electron-translucent lumens. No other structures in axenically grown Dictyostelium cells were labeled to a significant extent by these two antibodies. Using an affinity-purified antibody to calmodulin and a monospecific antibody to the B subunit of the chromaffin granule vacuolar ATPase, markers known to label the membranes of the contractile vacuole complex in Dictyostelium (Zhu and Clarke, J. Cell Biol. 118, 347–358, 1992; Heuser et al., J. Cell Biol. 121, 1311–1327, 1993), we showed that the 100 kDa and 68 kDa subunits had the same distribution as these two markers. Co-localization was seen in both interphase and mitotic cells. Thus, our results support the conclusion that vacuolar proton pumps are located principally on the membranes of the contractile vacuole complex in Dictyostelium. In addition, in indirect immunofluorescence experiments, these monoclonal antibodies provided improved images of the organization of the contractile vacuole system.

Immunogold labeling of Pneumocystis carinii for Electron microscopy

1991 ◽  
Vol 49 ◽  
pp. 270-271
Author(s):  
Michael P. Goheen ◽  
Marilyn S. Bartlett ◽  
James W. Smith
Keyword(s):  
Electron Microscopy ◽  
Pneumocystis Carinii ◽  
Severe Pneumonia ◽  
Culture Fluid ◽  
Immunogold Labeling ◽  
Antigenic Sites ◽  
Transmission Electron ◽  
Response To Chemotherapy ◽  
Acquired Immunodeficiency ◽  
Immunodeficiency Syndrome

Studies of the biology of Pneumocystis carinii (PC) are of increasing importance because this extracellular pathogen is a frequent source of severe pneumonia in patients with acquired immunodeficiency syndrome (AIDS) and is a leading cause of mortality in these patients. Immunoelectron microscopic localization of antigenic sites on the surface of PC would improve the understanding of these sites and their role in pathenogenisis of the disease and response to chemotherapy. The purpose of this study was to develop a methodology for visualizing immunoreactive sites on PC with transmission electron microscopy (TEM) using immunogold labeled probes.Trophozoites of PC were added to spinner flask cultures and allowed to grow for 7 days, then aliquots of tissue culture fluid were centrifuged at 12,000 RPM for 30 sec. Pellets of organisims were fixed in either 1% glutaraldehyde, 0.1% glutaraldehyde-4% paraformaldehyde, or 4% paraformaldehyde for 4h. All fixatives were buffered with 0.1M Na cacodylate and the pH adjusted to 7.1. After fixation the pellets were rinsed in 0.1M Na cacodylate (3X), dehydrated with ethanol, and immersed in a 1:1 mixture of 95% ethanol and LR White resin.

scholarly journals An artificial test substrate for evaluating electron microscopic immunocytochemical labeling reactions.

1987 ◽  
Vol 35 (8) ◽  
pp. 909-916 ◽  
Author(s):  
G D Gagne ◽  
M F Miller
Keyword(s):  
Electron Microscope ◽  
Hepatitis B ◽  
Horseradish Peroxidase ◽  
Polyclonal Antibodies ◽  
Hepatitis B Surface Antigen ◽  
Immunogold Labeling ◽  
Artificial Substrate ◽  
Chemical Fixation ◽  
Electron Microscopic ◽  
Immunocytochemical Studies

We describe an artificial substrate system for optimization of labeling parameters in electron microscope immunocytochemical studies. The system involves use of blocks of glutaraldehyde-polymerized BSA into which a desired antigen is incorporated by a simple soaking procedure. The resulting antigen-impregnated artificial substrate can then be fixed and embedded identically to a piece of tissue. The BSA substrate can also be dried and then sectioned for immunolabeling with or without chemical fixation and without exposing the antigen to dehydrating agents and embedding resins. The effects of various fixation and embedding procedures can thus be evaluated separately. Other parameters affecting immunocytochemical labeling, such as antibody and conjugate concentration, can also be evaluated. We used this system, along with immunogold labeling, to determine quantitatively the optimal fixation and embedding conditions for labeling of hepatitis B surface antigen (HbsAg), human IgG, and horseradish peroxidase. Using unfixed and unembedded HBsAg, we were able to detect antigen concentrations below 20 micrograms/ml. We have shown that it is not possible to label HBsAg within resin-embedded cells using conventional aldehyde fixation protocols and polyclonal antibodies.

The vacuolar proton pump of Dictyostelium discoideum: molecular cloning and analysis of the 100 kDa subunit

1996 ◽  
Vol 109 (5) ◽  
pp. 1041-1051 ◽  
Author(s):  
T. Liu ◽  
M. Clarke
Keyword(s):  
Dictyostelium Discoideum ◽  
Proton Pump ◽  
Single Gene ◽  
Consensus Sequence ◽  
Amino Acid Sequences ◽  
Contractile Vacuole ◽  
Proton Pumps ◽  
Variable Regions ◽  
Endosomal Membranes ◽  
Vacuolar Proton Pump

The vacuolar proton pump is a highly-conserved multimeric enzyme that catalyzes the translocation of protons across the membranes of eukaryotic cells. Its largest subunit (95-116 kDa) occurs in tissue and organelle-specific isoforms and thus may be involved in targeting the enzyme or modulating its function. In amoebae of Dictyostelium discoideum, proton pumps with a 100 kDa subunit are found in membranes of the contractile vacuole complex, an osmoregulatory organelle. We cloned the cDNA that encodes this 100 kDa protein and found that its sequence predicts a protein 45% identical (68% similar) to the corresponding mammalian proton pump subunit. Like the mammalian protein, the predicted Dictyostelium sequence contains six possible transmembrane domains and a single consensus sequence for N-linked glycosylation. Southern blot analysis detected only a single gene, which was designated vatM. Using genomic DNA and degenerate oligonucleotides based on conserved regions of the protein as primers, we generated products by polymerase chain reaction that included highly variable regions of this protein family. The cloned products were identical in nucleotide sequence to vatM, arguing that Dictyostelium cells contain only a single isoform of this proton pump subunit. Consistent with this interpretation, the amino acid sequences of peptides derived from a protein associated with endosomal membranes (Adessu et al. (1995) J. Cell Sci. 108, 3331–3337) match the predicted sequence of the protein encoded by vatM. Thus, a single isoform of the 100 kDa proton pump subunit appears to serve in both the contractile vacuole system and the endosomal/lysosomal system of Dictyostelium, arguing that this subunit is not responsible for regulating the differing abundance and function of proton pumps in these two compartments. Gene targeting experiments suggest that this subunit plays important (possibly essential) roles in Dictyostelium cells.

scholarly journals Progesterone receptor in the chick oviduct: an immunohistochemical study with antibodies to distinct receptor components.

1984 ◽  
Vol 99 (4) ◽  
pp. 1193-1201 ◽  
Author(s):  
J M Gasc ◽  
J M Renoir ◽  
C Radanyi ◽  
I Joab ◽  
P Tuohimaa ◽  
...  
Keyword(s):  
Progesterone Receptor ◽  
Polyclonal Antibodies ◽  
Smooth Muscles ◽  
Immunoperoxidase Technique ◽  
Cell Nuclei ◽  
Receptor Complexes ◽  
B Subunit ◽  
Chicken Oviduct ◽  
A Subunit ◽  
Immunohistochemical Studies

We performed immunohistochemical studies of chicken oviduct after different fixation procedures, by using antibodies against the progesterone receptor: polyclonal antibodies IgG-G3 against the "8S" form (an oligomere containing progesterone-binding and nonprogesterone-binding units), polyclonal antibodies IgG-RB against the progesterone-binding B subunit, and monoclonal BF4 against the non-progesterone-binding 90,000-mol-wt protein component. Chickens were immature animals with or without estrogen priming, and with or without progesterone treatment. The antibodies were revealed by means of an immunoperoxidase technique that used the avidin-biotin-peroxidase complex, and controls were performed by presaturation of antibodies with the purified 8S-progesterone receptor, the B subunit, and 90,000-mol-wt protein. The progesterone receptor was detected not only in well-characterized target tissues, i.e., in glands and luminal epithelium, but also in stromal cells (some displayed the strongest reaction), in mesothelium, and in fibers of smooth muscles. Only in cell nuclei, whether or not the animals received an injection of progesterone was an antigen revealed corresponding to the B subunit (and/or to the A subunit, because there is immunoreactivity of IgG-RB with both hormone-binding subunits A and B). The 90,000-mol-wt protein was revealed in both cytoplasm and nuclei. These immunohistological data suggest that the concept of steroid action that necessarily involves the original formation of the hormone-receptor complexes in the cytoplasm before translocation to the nucleus, may have to be revised.

scholarly journals Characterisation of M2e Antigenicity using anti-M2 Monoclonal Antibody and anti-M2e Polyclonal Antibodies

2019 ◽  
Vol 24 (3) ◽  
pp. 122
Author(s):  
Sumarningsih Sumarningsih ◽  
Simson Tarigan ◽  
H Farhid ◽  
Jagoda Ignjatovic
Keyword(s):  
Monoclonal Antibody ◽  
Influenza A ◽  
Polyclonal Antibodies ◽  
Enzyme Linked Immunosorbent Assay ◽  
Discriminating Power ◽  
Antigenic Sites ◽  
Rabbit Polyclonal Antibody ◽  
Adjacent Position ◽  
Important Position ◽  
M2e Protein

Matrix 2 ectodomain (M2e) protein is a potential antigen for detection of influenza A virus infection in vaccinated poultry (DIVA test). However the M2e antigenicity and immune response it induces in either humans or animals are poorly understood. Seventeen M2e peptides and sixteen recombinant M2e (rM2e) proteins with amino acid (aa) changes introduced at position 10, 11, 12, 13 14, 16, 18 and 20 were compared by western blot (WB) and enzyme-linked immunosorbent assay (ELISA) using mouse anti-M2 monoclonal antibody (mAb) 14C2, and anti-M2e peptide chicken and rabbit polyclonal antibody (pAb). The mAb 14C had the best discriminating power and indicated that all six positions contributed to the M2e antigenicity. Position 11 was the important immunodominant and affected Mab14C binding to a greatest degree. Changes in the adjacent position 14, 16 and 18 also influenced the binding, and it detected regardless of the method (WB or ELISA), or the antigen used (M2e peptide or rM2e). For chicken pAb and rabbit pAb, the immunodominant aa was position 10 and the antibody reaction was not affected by aa change at 11. The binding of rabbit pAb was also affected by changes at 14 and 16, which confirm the contribution of these positions to the M2e antigenicity. Position 10 was the only important position for the binding of chicken pAb to M2e. Overall, the study showed that the M2e antigenic sites are located between residues 10 – 18 and that aa changes at position 10, 11, 12, 14, 16 and 18 may all affect the antibody binding within the M2e protein.

The Difference Between Platelet and Plasma FXIII Used to Study the Mechanism of Platelet Microvesicle Formation

1993 ◽  
Vol 70 (04) ◽  
pp. 681-686 ◽  
Author(s):  
Pål André Holme ◽  
Frank Brosstad ◽  
Nils Olav Solum
Keyword(s):  
Polyclonal Antibodies ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
B Subunit ◽  
Mechanical Disruption ◽  
Crossed Immunoelectrophoresis ◽  
The Difference ◽  
The Complement System ◽  
Filtration Technique

SummaryThe formation of microvesicles from platelets was induced either by activation of the complement system by a monoclonal antibody to CD9, or by incubation of platelets with the calcium ionophore A23187. A filter technique to isolate the microvesicles without plasma contamination is described. The microvesicles contained FXIIIa2 from the platelet cytoplasm which shows that these particles contain significant amounts of intracellular material. This was shown by the use of crossed immunoelectrophoresis with rabbit antibodies to total human platelet proteins in the second dimension gel and polyclonal antibodies against the a- and b-subunit of FXIII in the intermediate gel. The FXIIIa2 in the microvesicle was found to be functional as an enzyme. To prove this, it was shown that FXIII in its immunoprecipitate arc could catalyze the incorporation of monodansylcadaverine into casein as identified by fluorescence of this arc in ultraviolet light. The observation that the plasma form of FXIII (FXIIIa2b2) was absent from the microvesicles collected by the filtration technique, whereas it was present in platelet fragments obtained by mechanical disruption by ultrasonication, indicates that the activation-dependent microvesicles are formed by a true budding process with the inclusion of intracellular, but not extracellular material.

Dynamics of the vacuolar H+-ATPase in the contractile vacuole complex and the endosomal pathway ofDictyosteliumcells

2002 ◽  
Vol 115 (14) ◽  
pp. 2893-2905 ◽  
Author(s):  
Margaret Clarke ◽  
Jana Köhler ◽  
Quyen Arana ◽  
Tongyao Liu ◽  
John Heuser ◽  
...  
Keyword(s):  
Time Course ◽  
Fluorescent Protein ◽  
Membrane System ◽  
Contractile Vacuole ◽  
Proton Pumps ◽  
Gene Encoding ◽  
Endosomal Membrane ◽  
C Terminus ◽  
Direct Assembly ◽  
Green Fluorescent

The vacuolar H+-ATPase (V-ATPase) is a multi-subunit enzyme that plays important roles in eukaryotic cells. In Dictyostelium, it is found primarily in membranes of the contractile vacuole complex, where it energizes fluid accumulation by this osmoregulatory organelle and also in membranes of endolysosomes, where it serves to acidify the endosomal lumen. In the present study, a fusion was created between vatM, the gene encoding the 100 kDa transmembrane subunit of the V-ATPase, and the gene encoding Green Fluorescent Protein (GFP). When expressed in Dictyostelium cells, this fusion protein, VatM-GFP, was correctly targeted to contractile vacuole and endolysosomal membranes and was competent to direct assembly of the V-ATPase enzyme complex. Protease treatment of isolated endosomes indicated that the GFP moiety, located on the C-terminus of VatM, was exposed to the cytoplasmic side of the endosomal membrane rather than to the lumenal side. VatM-GFP labeling of the contractile vacuole complex revealed clearly the dynamics of this pleiomorphic vesiculotubular organelle. VatM-GFP labeling of endosomes allowed direct visualization of the trafficking of vacuolar proton pumps in this pathway, which appeared to be entirely independent from the contractile vacuole membrane system. In cells whose endosomes were pre-labeled with TRITC-dextran and then fed yeast particles,VatM-GFP was delivered to newly formed yeast phagosomes with the same time course as TRITC-dextran, consistent with transfer via a direct fusion of endosomes with phagosomes. Several minutes were required before the intensity of the VatM-GFP labeling of new phagosomes reached the level observed in older phagosomes, suggesting that this fusion process was progressive and continuous. VatM-GFP was retrieved from the phagosome membrane prior to exocytosis of the indigestible remnants of the yeast particle. These data suggest that vacuolar proton pumps are recycled by fusion of advanced with newly formed endosomes.

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