The occurrence of nuclear fusion in the amoebal phase of the slime mold Echinostelium minutum: a reinterpretation of the significance of this phenomenon

1977 ◽  
Vol 55 (24) ◽  
pp. 3020-3022 ◽  
Author(s):  
E. F. Haskins
Keyword(s):  
Nuclear Fusion ◽  
Slime Mold ◽  
Daughter Cells ◽  
Fusion Nucleus ◽  
Feulgen Cytophotometry ◽  
Synchronous Mitosis

Nuclear fusion occurs in less than 1% of the myxamoebae of Echinostelium minutum de Bary, isolate D-3, sublines 1965 and 1971. Binucleate amoebae undergo synchronous mitosis, the two nuclei fuse, the fusion nucleus divides, cytokinesis occurs, and uninucleate daughter cells are formed. Failure to find a haploid–diploid alternance between the amoebal and plasmodial phases using Feulgen cytophotometry suggests that nuclear fusion is not a prerequisite for plasmodial formation in this isolate. Nuclear fusion may be one of the mechanisms which has led to the polyploid condition of the 1971 subline. This phenomenon may also represent a parasexual process.

Nucleic acid metabolism in a slime mold with synchronous mitosis

1960 ◽  
Vol 38 ◽  
pp. 298-306 ◽  
Author(s):  
Oddvar F. Nygaard ◽  
Sophia Güttes ◽  
Harold P. Rusch
Keyword(s):  
Nucleic Acid ◽  
Acid Metabolism ◽  
Slime Mold ◽  
Nucleic Acid Metabolism ◽  
Synchronous Mitosis

scholarly journals Nuclear reorganization in non-sporing bacteria

1948 ◽  
Vol 46 (2) ◽  
pp. 173-175 ◽  
Author(s):  
K. A. Bisset
Keyword(s):  
Nuclear Fusion ◽  
Nuclear Reorganization ◽  
Fusion Nucleus

1. The process of nuclear fusion and reorganization as it occurs in members of the Bacteriaceae is described.2. The chromosomes behave as pairs at all times, the normal bacillus, of smooth morphology, contains two pairs.3. The fusion nucleus contains three pairs and is preceded by a corresponding trinucleate bacillus.4. One division of the chromosomes takes place in the fusion nucleus, and another during the process of redistribution of the chromosomes. The second division is followed by fragmentation, and return to the bacillary condition.

Polyploidy and Nuclear Fusion in the Fat Body of Rhodnius(Hemiptera)

1967 ◽  
Vol 2 (4) ◽  
pp. 603-616
Author(s):  
V. B. WIGGLESWORTH
Keyword(s):  
Diploid Number ◽  
Fat Body ◽  
Nuclear Fusion ◽  
Chromosome Counts ◽  
Daughter Cells ◽  
Single Plate ◽  
High Incidence ◽  
Polyploid Cells ◽  
Food Reserves ◽  
Low Rate

The diploid number in Rhodnius is 22 in both sexes. At hatching the fat-body cells are tetraploid, with a few octoploid. This polyploidy is presumed to arise by endomitosis in the egg. In the fully nourished insect this state persists throughout life; and occasional 16n and 32n nuclei occur. Whether these arise by endomitosis or by nuclear fusion has not been established. In extreme starvation (e.g. 8 months from the time of moulting in the 4th-stage larva at 26 °C) polyploidy increases greatly. This results from nuclear fusion in interphase. The evidence is as follows: (i) All intermediate stages in fusion can be observed. (ii) Polyploidy develops many months after growth and mitosis have been arrested. (iii) It occurs mainly in those regions where the food reserves first become exhausted. (iv) When these starved insects are fed the polyploid cells divide and chromosome counts include 12n, 20n, 24n, etc., as well as the regular series 4n, 8n, 16n, 32n, etc. Contiguous nuclei which have not fused in interphase often amalgamate their chromosomes to form a single plate and spindle at metaphase and likewise produce more highly polyploid daughter cells. The high incidence of nuclear fusion in Rhodnius is ascribed to the low rate of metabolism which permits prolonged survival in the starving insect.

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.

Stimulated Virus Production in Vinblastine and Cytochalasin-Induced Multinucleate Cells

1970 ◽  
Vol 28 ◽  
pp. 186-187
Author(s):  
Krishan Awtar
Keyword(s):  
Cell Division ◽  
Normal Cell ◽  
Virus Production ◽  
Multinucleate Cells ◽  
Daughter Cells ◽  
Cell Divisions ◽  
Nuclear Membranes ◽  
Division 2 ◽  
Vinblastine Sulfate

Exposure of cells to low sublethal but mitosis-arresting doses of vinblastine sulfate (Velban) results in the initial arrest of cells in mitosis followed by their subsequent return to an “interphase“-like stage. A large number of these cells reform their nuclear membranes and form large multimicronucleated cells, some containing as many as 25 or more micronuclei (1). Formation of large multinucleate cells is also caused by cytochalasin, by causing the fusion of daughter cells at the end of an otherwise .normal cell division (2). By the repetition of this process through subsequent cell divisions, large cells with 6 or more nuclei are formed.

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).

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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