scholarly journals Cytoskeleton-secretory vesicle interactions during the docking of secretory vesicles at the cell membrane in Paramecium tetraurelia cells.

1982 ◽  
Vol 92 (2) ◽  
pp. 368-377 ◽  
Author(s):  
H Plattner ◽  
C Westphal ◽  
R Tiggemann
Keyword(s):  
Cell Surface ◽  
Attachment Site ◽  
Secretory Vesicle ◽  
Basal Bodies ◽  
Secretory Vesicles ◽  
Paramecium Tetraurelia ◽  
Long Distance ◽  
Microfilament Bundles ◽  
Attachment Sites ◽  
Saltatory Movement

Stationary-phase cells of Paramecium tetraurelia have most of their many secretory vesicles ("trichocysts") attached to the cell surface. Log-phase cells contain numerous unoccupied potential docking sites for trichocysts and many free trichocysts in the cytoplasm. To study the possible involvement of cytoskeletal elements, notably of microtubules, in the process of positioning of trichocysts at the cell surface, we took advantage of these stages. Cells were stained with tannic acid and subsequently analyzed by electron microscopy. Semithin sections allowed the determination of structural connections over a range of up to 10 micrometer. Microtubules emanating from ciliary basal bodies are seen in contact with free trichocysts, which appear to be transported, with their tip first, to the cell surface. (This can account for the saltatory movement reported by others). It is noteworthy that the "rails" represented by the microtubules do not directly determine the final attachment site of a trichocyst. Unoccupied attachment sites are characterized by a "plug" of electron-dense material just below the plasma membrane; the "plug" seems to act as a recognition or anchoring site; this material is squeezed out all around the trichocyst attachment zone, once a trichocyst is inserted (Westphal and Plattner, in press. [53]). Slightly below this "plug" we observed fasciae of microfilaments (identified by immunocytochemistry using peroxidase labeled F(ab) fragments against P. tetraurelia actin). Their arrangement is not altered when a trichocyst is docked. These fasciae seem to form a loophole for the insertion of a trichocyst. Trichocyst remain attached to the microtubules originating from the ciliary basal bodies--at least for some time--even after they are firmly installed in the preformed attachment sites. Evidently, the regular arrangement of exocytotic organelles is controlled on three levels: one operating over a long distance from the exocytosis site proper (microtubules), one over a short distance (microfilament bundles), and one directly on the exocytosis site ("plug").

Temperature-sensitive mutations affecting cortical morphogenesis and cell division in Paramecium tetraurelia

1982 ◽  
Vol 60 (10) ◽  
pp. 2296-2308 ◽  
Author(s):  
Donald Jones ◽  
James D. Berger
Keyword(s):  
Cell Division ◽  
Cell Surface ◽  
Posterior Part ◽  
Gene Mutations ◽  
Temperature Sensitive ◽  
Basal Bodies ◽  
Paramecium Tetraurelia ◽  
Fission Process ◽  
Daughter Cells ◽  
Recessive Genes

Nine temperature-sensitive gene mutations affecting cellular morphogenesis were analysed and shown to be single recessive genes. Their phenotypes fall into three classes: small mutants (sm) which interfere with cell surface and basal body proliferation to produce short cells; defective fission zone mutants (dfz) which do not form a complete fission zone during cell division; and defective constriction mutants (dc) which form a normal fission zone, but do not constrict properly. In sm2 cells there is a reduction in the number of basal bodies and in the amount of cell surface produced preceding fission. This results in the production of truncated daughter cells in which most of the normal structures of either the anterior or posterior part of the cell are highly reduced or missing. Production of basal bodies in gullet primordia is also abnormal. The dfz mutants act early in the fission process to block the formation of the fission zone which precedes the formation of the fission furrow. The dc mutations act later in the fission process and lead to failure of daughter cell separation. One mutant, dc3, also shows slightly reduced proliferation of cell surface. This defect occurs prior to fission.

scholarly journals Distinct Subcellular Localization of a Group of Synaptobrevin-Like SNAREs in Paramecium tetraurelia and Effects of Silencing SNARE-Specific Chaperone NSF

2009 ◽  
Vol 9 (2) ◽  
pp. 288-305 ◽  
Author(s):  
Christina Schilde ◽  
Barbara Schönemann ◽  
Ivonne M. Sehring ◽  
Helmut Plattner
Keyword(s):  
Cell Surface ◽  
Membrane Trafficking ◽  
Fluorescent Protein ◽  
Close Association ◽  
Secretory Vesicle ◽  
Food Vacuole ◽  
Paramecium Tetraurelia ◽  
Content Type ◽  
Early Endosomes ◽  
Green Fluorescent

ABSTRACT We have identified new synaptobrevin-like SNAREs and localized the corresponding gene products with green fluorescent protein (GFP)-fusion constructs and specific antibodies at the light and electron microscope (EM) levels. These SNAREs, named Paramecium tetraurelia synaptobrevins 8 to 12 (PtSyb8 to PtSyb12), showed mostly very restricted, specific localization, as they were found predominantly on structures involved in endo- or phagocytosis. In summary, we found PtSyb8 and PtSyb9 associated with the nascent food vacuole, PtSyb10 near the cell surface, at the cytostome, and in close association with ciliary basal bodies, and PtSyb11 on early endosomes and on one side of the cytostome, while PtSyb12 was found in the cytosol. PtSyb4 and PtSyb5 (identified previously) were localized on small vesicles, PtSyb5 probably being engaged in trichocyst (dense core secretory vesicle) processing. PtSyb4 and PtSyb5 are related to each other and are the furthest deviating of all SNAREs identified so far. Because they show no similarity with any other R-SNAREs outside ciliates, they may represent a ciliate-specific adaptation. PtSyb10 forms small domains near ciliary bases, and silencing slows down cell rotation during depolarization-induced ciliary reversal. NSF silencing supports a function of cell surface SNAREs by revealing vesicles along the cell membrane at sites normally devoid of vesicles. The distinct distributions of these SNAREs emphasize the considerable differentiation of membrane trafficking, particularly along the endo-/phagocytic pathway, in this protozoan.

Comparison of the glycosyl-phosphatidylinositol cleavage/attachment site between mammalian cells and parasitic protozoa

2000 ◽  
Vol 113 (4) ◽  
pp. 721-727 ◽  
Author(s):  
I.J. White ◽  
A. Souabni ◽  
N.M. Hooper
Keyword(s):  
Cell Surface ◽  
Mammalian Cells ◽  
Attachment Site ◽  
Surface Glycoprotein ◽  
Variant Surface Glycoprotein ◽  
Parasitic Protozoa ◽  
Mutant Proteins ◽  
Glycosyl Phosphatidylinositol ◽  
Attachment Sites ◽  
Potential Alternative

It was previously hypothesised that the requirements for glycosyl-phosphatidylinositol (GPI) anchoring in mammalian cells and parasitic protozoa are similar but not identical. We have investigated this by converting the GPI cleavage/attachment site in porcine membrane dipeptidase to that found in the trypanosomal variant surface glycoprotein 117 and expressing the resulting mutants in COS-1 cells. Changing the entire (omega), (omega)+1 and (omega)+2 triplet in membrane dipeptidase from Ser-Ala-Ala to Asp-Ser-Ser resulted in efficient GPI anchoring of the mutant proteins, as assessed by cell-surface activity assays and susceptibility to release by phosphatidylinositol-specific phospholipase C. Immunoelectrophoretic blot analysis with antibodies recognising epitopes either side of the native (omega) residue in porcine membrane dipeptidase, and expression of a mutant in which potential alternative cleavage/attachment sites were disrupted, indicated that alternative GPI cleavage/attachment sites had not been used. These results indicate that the requirements for GPI anchoring between mammalian and protozoal cells are not as different as previously suggested, and that rules for predicting the probability of a sequence acting as a GPI cleavage/attachment site need to be applied with caution.

scholarly journals Cortical development associated with conjugation of Paramecium

Development ◽  
1993 ◽  
Vol 117 (3) ◽  
pp. 1099-1112
Author(s):  
M. R. Romero ◽  
A. Torres
Keyword(s):  
Cell Cycle ◽  
Cell Surface ◽  
Development Process ◽  
Cortical Development ◽  
Suture Line ◽  
Basal Bodies ◽  
Paramecium Tetraurelia ◽  
Sexual Process ◽  
Cortical Cytoskeleton

The cortical cytoskeleton of Paramecium is characterized by a complex, polarized and asymmetrical organization. In order to analyse the cortical development of Paramecium tetraurelia during the sexual process of conjugation, different antibodies have been used to follow the development of five cortical components: basal bodies, ciliary rootlets, outer lattice, epiplasm and cytospindle. This study demonstrates that the cortex of Paramecium undergoes an elaborate development process following conjugation. Some of the cortical structures that are not renewed at any other moment of the cell cycle, are resorbed after conjugation and replaced by other newly formed ones. The reorganization of the cortical components occurs according to different morphogenetic waves that spread over the cell surface. The oral system and the preoral suture line act as morphogenetic epicentres.

Immunogold and immunoblot studies on a cell surface protein found in primary mesenchyme cells and in the cortical secretory vesicles of the sea urchin egg

1987 ◽  
Vol 45 ◽  
pp. 832-833
Author(s):  
G.L. Decker ◽  
M.C. Valdizan
Keyword(s):  
Cell Surface ◽  
Sea Urchin ◽  
Surface Protein ◽  
Egg Cell ◽  
Secretory Vesicles ◽  
Cell Surface Protein ◽  
Surface Complexes ◽  
Mesenchyme Cells ◽  
Lowicryl K4m ◽  
Primary Mesenchyme Cells

A monoclonal antibody designated MAb 1223 has been used to show that primary mesenchyme cells of the sea urchin embryo express a 130-kDa cell surface protein that may be directly involved in Ca2+ uptake required for growth of skeletal spicules. Other studies from this laboratory have shown that the 1223 antigen, although in relatively low abundance, is also expressed on the cell surfaces of unfertilized eggs and on the majority of blastomeres formed prior to differentiation of the primary mesenchyme cells.We have studied the distribution of 1223 antigen in S. purpuratus eggs and embryos and in isolated egg cell surface complexes that contain the cortical secretory vesicles. Specimens were fixed in 1.0% paraformaldehyde and 1.0% glutaraldehyde and embedded in Lowicryl K4M as previously reported. Colloidal gold (8nm diameter) was prepared by the method of Mulpfordt.

scholarly journals Organization of the flagellar apparatus and associate cytoplasmic microtubules in the quadriflagellate alga Polytomella agilis.

1976 ◽  
Vol 69 (1) ◽  
pp. 106-125 ◽  
Author(s):  
D L Brown ◽  
A Massalski ◽  
R Patenaude
Keyword(s):  
Anterior Part ◽  
Flagellar Apparatus ◽  
Microtubule Assembly ◽  
Immunofluorescent Staining ◽  
Body Region ◽  
Basal Bodies ◽  
Cytoplasmic Microtubule ◽  
Large Numbers ◽  
Attachment Sites ◽  
Cytoplasmic Microtubules

The organization of microtubular systems in the quadriflagellate unicell Polytomella agilis has been reconstructed by electron microscopy of serial sections, and the overall arrangement confirmed by immunofluorescent staining using antiserum directed against chick brain tubulin. The basal bodies of the four flagella are shown to be linked in two pairs of short fibers. Light microscopy of swimming cells indicates that the flagella beat in two synchronous pairs, with each pair exhibiting a breast-stroke-like motion. Two structurally distinct flagellar rootlets, one consisting of four microtubules in a 3 over 1 pattern and the other of a striated fiber over two microtubules, terminate between adjacent basal bodies. These rootlets diverge from the basal body region and extend toward the cell posterior, passing just beneath the plasma membrane. Near the anterior part of the cell, all eight rootlets serve as attachment sites for large numbers of cytoplasmic microtubules which occur in a single row around the circumference of the cell and closely parallel the cell shape. It is suggested that the flagellar rootless may function in controlling the patterning and the direction of cytoplasmic microtubule assembly. The occurrence of similar rootlet structures in other flagellates is briefly reviewed.

scholarly journals The effect of attachment site mutations on strand exchange in bacteriophage lambda site-specific recombination.

Genetics ◽  
1989 ◽  
Vol 122 (4) ◽  
pp. 727-736
Author(s):  
C E Bauer ◽  
J F Gardner ◽  
R I Gumport ◽  
R A Weisberg
Keyword(s):  
Attachment Site ◽  
Strand Exchange ◽  
Segregation Pattern ◽  
Base Substitution ◽  
Base Pairs ◽  
Multiple Mutation ◽  
Attachment Sites ◽  
Dna Strands ◽  
Substitution Mutations ◽  
Overlap Region

Abstract Recombination of phage lambda attachment sites occurs by sequential exchange of the DNA strands at two specific locations. The first exchange produces a Holliday structure, and the second resolves it to recombinant products. Heterology for base substitution mutations in the region between the two strand exchange points (the overlap region) reduces recombination; some mutations inhibit the accumulation of Holliday structures, others inhibit their resolution to recombinant products. To see if heterology also alters the location of the strand exchange points, we determined the segregation pattern of three single and one multiple base pair substitution mutations of the overlap region in crosses with wild type sites. The mutations are known to differ in the severity of their recombination defect and in the stage of strand exchange they affect. The three single mutations behaved similarly: each segregated into both products of recombination, and the two products of a single crossover were frequently nonreciprocal in the overlap region. In contrast, the multiple mutation preferentially segregated into one of the two recombinant products, and the two products of a single crossover appeared to be fully reciprocal. The simplest explanation of the segregation pattern of the single mutations is that strand exchanges occur at the normal locations to produce recombinants with mismatched base pairs that are frequently repaired. The segregation pattern of the multiple mutation is consistent with the view that both strand exchanges usually occur to one side of the mutant site. We suggest that the segregation pattern of a particular mutation is determined by which stage of strand exchange it inhibits and by the severity of the inhibition.

Synaptotagmin-1: A Multi-Functional Protein that Mediates Vesicle Docking, Priming, and Fusion

2021 ◽  
Vol 22 ◽  
Author(s):  
Najeeb Ullah ◽  
Ezzouhra El Maaiden ◽  
Md. Sahab Uddin ◽  
Ghulam Md Ashraf
Keyword(s):  
Plasma Membrane ◽  
Secretory Granules ◽  
Secretory Vesicle ◽  
Neuroendocrine Cells ◽  
Snare Complex ◽  
Secretory Vesicles ◽  
Functional Protein ◽  
Vesicle Docking ◽  
Synaptotagmin 1

: The fusion of secretory vesicles with the plasma membrane depends on the assembly of v-SNAREs (VAMP2/synaptobrevin2) and t-SNAREs (SNAP25/syntaxin1) into the SNARE complex. Vesicles go through several upstream steps, referred to as docking and priming, to gain fusion competence. The vesicular protein synaptotagmin-1 (Syt-1) is the principal Ca2+ sensor for fusion in several central nervous system neurons and neuroendocrine cells and part of the docking complex for secretory granules. Syt-1 binds to the acceptor complex such as synaxin1, SNAP-25 on the plasma membrane to facilitate secretory vesicle docking, and upon Ca2+-influx promotes vesicle fusion. This review assesses the role of the Syt-1 protein involved in the secretory vesicle docking, priming, and fusion.

scholarly journals The Cooh-Terminal Domain of Myo2p, a Yeast Myosin V, Has a Direct Role in Secretory Vesicle Targeting

1999 ◽  
Vol 147 (4) ◽  
pp. 791-808 ◽  
Author(s):  
Daniel Schott ◽  
Jackson Ho ◽  
David Pruyne ◽  
Anthony Bretscher
Keyword(s):  
Secretory Vesicle ◽  
Restrictive Temperature ◽  
Secretory Vesicles ◽  
Tail Domain ◽  
Myosin V ◽  
Direct Role ◽  
Rab Protein ◽  
Polarized Delivery ◽  
Actin Cables ◽  
Type V

MYO2 encodes a type V myosin heavy chain needed for the targeting of vacuoles and secretory vesicles to the growing bud of yeast. Here we describe new myo2 alleles containing conditional lethal mutations in the COOH-terminal tail domain. Within 5 min of shifting to the restrictive temperature, the polarized distribution of secretory vesicles is abolished without affecting the distribution of actin or the mutant Myo2p, showing that the tail has a direct role in vesicle targeting. We also show that the actin cable–dependent translocation of Myo2p to growth sites does not require secretory vesicle cargo. Although a fusion protein containing the Myo2p tail also concentrates at growth sites, this accumulation depends on the polarized delivery of secretory vesicles, implying that the Myo2p tail binds to secretory vesicles. Most of the new mutations alter a region of the Myo2p tail conserved with vertebrate myosin Vs but divergent from Myo4p, the myosin V involved in mRNA transport, and genetic data suggest that the tail interacts with Smy1p, a kinesin homologue, and Sec4p, a vesicle-associated Rab protein. The data support a model in which the Myo2p tail tethers secretory vesicles, and the motor transports them down polarized actin cables to the site of exocytosis.

scholarly journals Spin-Dependent Electron Transport through Bacterial Cell Surface Multiheme Electron Conduits

2019 ◽  
Author(s):  
Suryakant Mishra ◽  
Sahand Pirbadian ◽  
Amit Kumar Mondal ◽  
Moh El-Naggar ◽  
Ron Naaman
Keyword(s):  
Electron Transport ◽  
Cell Surface ◽  
Bacterial Cell ◽  
Shewanella Oneidensis ◽  
Extracellular Electron Transfer ◽  
Long Distance ◽  
Force Microscopy ◽  
Bacterial Cell Surface ◽  
Redox Active ◽  
Gain Energy

Multiheme cytochromes, located on the bacterial cell surface, function as long-distance (> 10 nm) electron conduits linking intracellular reactions to external surfaces. This extracellular electron transfer process, which allows microorganisms to gain energy by respiring solid redox-active minerals, also facilitates the wiring of cells to electrodes. While recent studies suggested that a chiral induced spin selectivity effect is linked to efficient electron transmission through biomolecules, this phenomenon has not been investigated in the extracellular electron conduits. Using magnetic conductive probe atomic force microscopy, Hall voltage measurements, and spin-dependent electrochemistry of the decaheme cytochromes MtrF and OmcA from the metal-reducing bacterium <i>Shewanella oneidensis</i> MR-1, we show that electron transport through these extracellular conduits is spin-selective. Our study has implications for understanding how spin-dependent interactions and magnetic fields may control electron transport across biotic-abiotic interfaces in both natural and biotechnological systems.

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