scholarly journals INTRANUCLEAR MICROTUBULE ORGANIZING CENTER IN EARLY PROPHASE NUCLEI OF THE PLASMODIUM OF THE SLIME MOLD, PHYSARUM POLYCEPHALUM

1973 ◽  
Vol 57 (1) ◽  
pp. 220-224 ◽  
Author(s):  
Kenji Tanaka
Keyword(s):  
Physarum Polycephalum ◽  
Slime Mold ◽  
Early Prophase ◽  
Microtubule Organizing Center ◽  
Organizing Center

Variable pathways for developmental changes in composition and organization of microtubules in Physarum polycephalum

1990 ◽  
Vol 96 (3) ◽  
pp. 383-393
Author(s):  
L. Solnica-Krezel ◽  
M. Diggins-Gilicinski ◽  
T.G. Burland ◽  
W.F. Dove
Keyword(s):  
Physarum Polycephalum ◽  
Microtubule Organizing Center ◽  
Developmentally Regulated ◽  
Tubulin Isotypes ◽  
Cellular Events ◽  
Organizing Center ◽  
Cytoplasmic Microtubules ◽  
Beta 2 ◽  
Rare Cells ◽  
Microtubular Structures

The development of uninucleate amoebae into multinucleate plasmodia in myxomycetes is called the amoebal-plasmodial transition (APT). During the APT in Physarum polycephalum the ability to form flagellar axonemes is lost; the astral, open mitosis is replaced by the anastral, closed mitosis; and cytoskeletal microtubules disappear. These changes are accompanied by alterations in the repertoire of expressed tubulins. Using immunofluorescence microscopy we have studied the timing of loss and accumulation of developmentally regulated tubulin isotypes in relation to other cellular events during the APT. We specifically asked whether changes in the composition of microtubules are correlated with changes in their organization. The plasmodium-specific beta 2-tubulin can first be detected in microtubules of uninucleate cells after they become committed to plasmodium formation. However, rare cells are observed that exhibit beta 2-tubulin at earlier or only at later stages of development. Amoeba-specific acetylated alpha 3-tubulin disappears gradually during development. Individual cells differ in the timing of loss of this isotype: alpha 3-tubulin is present in the majority of uninucleate cells, in a fraction of binucleate and quadrinucleate cells, and is absent from larger multinucleate cells. Cytoplasmic microtubules in uninucleate cells are organized by a single microtubule-organizing center (MTOC) juxtaposed to the nucleus. Binucleate cells and quadrinucleate cells exhibit variable numbers of MTOCs. Cytoplasmic microtubules persist during the APT until the stage of plasmodia containing at least 100 nuclei. The lack of a strict correlation between the changes in tubulin composition and changes in organization of microtubular structures indicates that accumulation of beta 2-tubulin and disappearance of alpha 3-tubulin isotypes are not sufficient to bring about reorganization of microtubules during development. Individual cells in a developing population differ not only in the succession of accumulation and loss of developmentally regulated tubulins, but also in the sequences of other cellular changes occurring during the APT.

In vitro nucleation of microtubules from microtubule-organizing center prepared from cellular slime mold

Cell Motility ◽  
1982 ◽  
Vol 2 (3) ◽  
pp. 257-272 ◽  
Author(s):  
Ryoko Kuriyama ◽  
Chikako Sato ◽  
Yoshio Fukui ◽  
Soryu Nishibayashi
Keyword(s):  
Slime Mold ◽  
Cellular Slime Mold ◽  
Microtubule Organizing Center ◽  
Organizing Center ◽  
Cellular Slime

scholarly journals Distribution of acetylated alpha-tubulin in Physarum polycephalum.

1987 ◽  
Vol 104 (2) ◽  
pp. 303-309 ◽  
Author(s):  
M A Diggins ◽  
W F Dove
Keyword(s):  
Posttranslational Modification ◽  
Physarum Polycephalum ◽  
Two Dimensional ◽  
Microtubule Organizing Center ◽  
Western Blots ◽  
Alpha Tubulin ◽  
Cell Biol ◽  
Tubulin Isotype ◽  
Organizing Center ◽  
Double Label

The expression and cytological distribution of acetylated alpha-tubulin was investigated in Physarum polycephalum. A monoclonal antibody specific for acetylated alpha-tubulin, 6-11B-1 (Piperno, G., and M. T. Fuller, 1985, J. Cell Biol., 101:2085-2094), was used to screen for this protein during three different stages of the Physarum life cycle--the amoeba, the flagellate, and the plasmodium. Western blots of two-dimensional gels of amoebal and flagellate proteins reveal that this antibody recognizes the alpha 3 tubulin isotype, which was previously shown to be formed by posttranslational modification (Green, L. L., and W. F. Dove, 1984, Mol. Cell. Biol., 4:1706-1711). Double-label immunofluorescence demonstrates that, in the flagellate, acetylated alpha-tubulin is localized in the flagella and flagellar cone. Similar experiments with amoebae interestingly reveal that only within the microtubule organizing center (MTOC) are there detectable amounts of acetylated alpha-tubulin. In contrast, the plasmodial stage gives no evidence for acetylated alpha-tubulin by Western blotting or by immunofluorescence.

scholarly journals A novel mitotic spindle pole component that originates from the cytoplasm during prophase.

1986 ◽  
Vol 103 (5) ◽  
pp. 1863-1872 ◽  
Author(s):  
P R Sager ◽  
N L Rothfield ◽  
J M Oliver ◽  
R D Berlin
Keyword(s):  
Mitotic Spindle ◽  
Spindle Pole ◽  
Early Prophase ◽  
Microtubule Organizing Center ◽  
Spindle Poles ◽  
Interphase Cells ◽  
Organizing Center ◽  
Mitotic Spindle Pole ◽  
Pole Component

Several unique aspects of mitotic spindle formation have been revealed by investigation of an autoantibody present in the serum of a patient with the CREST (calcinosis, Raynaud's phenomenon, esophageal dysmotility, schlerodacytyly, and telangiectasias) syndrome. This antibody was previously shown to label at the spindle poles of metaphase and anaphase cells and to be absent from interphase cells. We show here that the serum stained discrete cytoplasmic foci in early prophase cells and only later localized to the spindle poles. The cytoplasmic distribution of the antigen was also seen in nocodazole-arrested cells and prophase cells in populations treated with taxol. In normal and taxol-treated cells, the microtubules appeared to emanate from the cytoplasmic foci and polar stain, and in cells released from nocodazole block, microtubules regrew from antigen-containing centers. This characteristic distribution suggests that the antigen is part of a microtubule organizing center. Thus, we propose that a prophase originating polar antigen functions in spindle pole organization as a coalescing microtubule organizing center that is present only during mitosis. Characterization of the serum showed reactions with multiple proteins at 115, 110, 50, 36, 30, and 28 kD. However, affinity-eluted antibody from the 115/110-kD bands was shown to specifically label the spindle pole and cytosolic foci in prophase cells.

Ca-Histochemistry in slime mold plasmodia

1978 ◽  
Vol 36 (2) ◽  
pp. 130-131
Author(s):  
Ulrich Dierkes
Keyword(s):  
Physarum Polycephalum ◽  
Carbon Coating ◽  
Freeze Drying ◽  
Freeze Fracture ◽  
Freeze Substitution ◽  
Uranyl Acetate ◽  
Slime Mold ◽  
Staining Procedure ◽  
Protoplasmic Streaming ◽  
Intracellular Ca

Calcium is supposed to play an important role in the control of protoplasmic streaming in slime mold plasmodia. The motive force for protoplasmic streaming is generated by the interaction of actin and myosin. This contraction is supposed to be controlled by intracellular Ca-fluxes similar to the triggering system in skeleton muscle. The histochemical localisation of calcium however is problematic because of the possible diffusion artifacts especially in aquous media.To evaluate this problem calcium localisation was studied in small pieces of shock frozen (liquid propane at -189°C) plasmodial strands of Physarum polycephalum, which were further processed with 3 different methods: 1) freeze substitution in ethanol at -75°C, staining in 100% ethanol with 1% uranyl acetate, and embedding in styrene-methacrylate. For comparison the staining procedure was omitted in some preparations. 2)Freeze drying at about -95°C, followed by immersion with 100% ethanol containing 1% uranyl acetate, and embedding. 3) Freeze fracture, carbon coating and SEM investigation at temperatures below -100° C.

Three-Dimensional reconstruction of isolated centrosomes by automated electron tomography

1994 ◽  
Vol 52 ◽  
pp. 310-311
Author(s):  
M.B. Braunfeld ◽  
M. Moritz ◽  
B.M. Alberts ◽  
J.W. Sedat ◽  
D.A. Agard
Keyword(s):  
Electron Tomography ◽  
Three Dimensional ◽  
Vital Role ◽  
Complex Nature ◽  
Animal Cells ◽  
Microtubule Organizing Center ◽  
Nucleation Sites ◽  
Dimensional Reconstruction ◽  
Organizing Center ◽  
Resolution Model

In animal cells, the centrosome functions as the primary microtubule organizing center (MTOC). As such the centrosome plays a vital role in determining a cell's shape, migration, and perhaps most importantly, its division. Despite the obvious importance of this organelle little is known about centrosomal regulation, duplication, or how it nucleates microtubules. Furthermore, no high resolution model for centrosomal structure exists.We have used automated electron tomography, and reconstruction techniques in an attempt to better understand the complex nature of the centrosome. Additionally we hope to identify nucleation sites for microtubule growth.Centrosomes were isolated from early Drosophila embryos. Briefly, after large organelles and debris from homogenized embryos were pelleted, the resulting supernatant was separated on a sucrose velocity gradient. Fractions were collected and assayed for centrosome-mediated microtubule -nucleating activity by incubating with fluorescently-labeled tubulin subunits. The resulting microtubule asters were then spun onto coverslips and viewed by fluorescence microscopy.

Characterization of a Motile Cellular Domain Arising During the Amoebo-Flagellate Transformation of Physarum Polycephalum

1980 ◽  
Vol 38 ◽  
pp. 552-553
Author(s):  
K.I. Pagh ◽  
M.R. Adelman
Keyword(s):  
Cell Shape ◽  
Physarum Polycephalum ◽  
Slime Mold ◽  
Live Cells ◽  
Cellular Domain

Unicellular amoebae of the slime mold Physarum polycephalum undergo marked changes in cell shape and motility during their conversion into flagellate swimming cells (l). To understand the processes underlying motile activities expressed during the amoebo-flagellate transformation, we have undertaken detailed investigations of the organization, formation and functions of subcellular structures or domains of the cell which are hypothesized to play a role in movement. One focus of our studies is on a structure, termed the “ridge” which appears as a flattened extension of the periphery along the length of transforming cells (Fig. 1). Observations of live cells using Nomarski optics reveal two types of movement in this region:propagation of undulations along the length of the ridge and formation and retraction of filopodial projections from its edge. The differing activities appear to be associated with two characteristic morphologies, illustrated in Fig. 1.

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