The ultrastructure of nuclear division in Armillaria mellea: meiosis

1979 ◽  
Vol 57 (18) ◽  
pp. 1860-1872 ◽  
Author(s):  
Diane Cope Peabody ◽  
Jerome J. Motta
Keyword(s):  
Nuclear Envelope ◽  
Membrane Structure ◽  
Nuclear Division ◽  
Spindle Pole ◽  
Armillaria Mellea ◽  
Spindle Pole Bodies ◽  
Late Telophase ◽  
Meiosis I ◽  
Metaphase I

Meiosis I in isolates of Armillaria mellea in which subhymenial hyphae are uninucleate and lack clamp connections was examined ultrastructurally. Although the overall pattern of development and basidiosporogenesis appears similar to other Homobasidiomycetes it was observed that spindle pole bodies are predominantly monoglobular and are associated with a unique membrane structure of the subtending nuclear envelope. The nuclear envelope also disappears at metaphase I and reforms by the coalescence of membrane fragments around the compacted chromatin at late telophase I. The significance of these features in relation to other Basidiomycetes is briefly discussed.

scholarly journals The Spindle Pole Bodies Facilitate Nuclear Envelope Division during Closed Mitosis in Fission Yeast

PLoS Biology ◽  
2007 ◽  
Vol 5 (7) ◽  
pp. e170 ◽  
Author(s):  
Liling Zheng ◽  
Cindi Schwartz ◽  
Valentin Magidson ◽  
Alexey Khodjakov ◽  
Snezhana Oliferenko
Keyword(s):  
Nuclear Envelope ◽  
Fission Yeast ◽  
Spindle Pole ◽  
Spindle Pole Bodies

scholarly journals The Three Fungal Transmembrane Nuclear Pore Complex Proteins of Aspergillus nidulans Are Dispensable in the Presence of an Intact An-Nup84-120 Complex

2009 ◽  
Vol 20 (2) ◽  
pp. 616-630 ◽  
Author(s):  
Hui-Lin Liu ◽  
Colin P.C. De Souza ◽  
Aysha H. Osmani ◽  
Stephen A. Osmani
Keyword(s):  
High Temperature ◽  
Nuclear Envelope ◽  
Aspergillus Nidulans ◽  
Nuclear Pore Complex ◽  
Mitotic Spindle ◽  
Spindle Pole ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Spindle Pole Bodies ◽  
Pore Complexes

In Aspergillus nidulans nuclear pore complexes (NPCs) undergo partial mitotic disassembly such that 12 NPC proteins (Nups) form a core structure anchored across the nuclear envelope (NE). To investigate how the NPC core is maintained, we affinity purified the major core An-Nup84-120 complex and identified two new fungal Nups, An-Nup37 and An-ELYS, previously thought to be vertebrate specific. During mitosis the An-Nup84-120 complex locates to the NE and spindle pole bodies but, unlike vertebrate cells, does not concentrate at kinetochores. We find that mutants lacking individual An-Nup84-120 components are sensitive to the membrane destabilizer benzyl alcohol (BA) and high temperature. Although such mutants display no defects in mitotic spindle formation, they undergo mitotic specific disassembly of the NPC core and transient aggregation of the mitotic NE, suggesting the An-Nup84-120 complex might function with membrane. Supporting this, we show cells devoid of all known fungal transmembrane Nups (An-Ndc1, An-Pom152, and An-Pom34) are viable but that An-ndc1 deletion combined with deletion of individual An-Nup84-120 components is either lethal or causes sensitivity to treatments expected to destabilize membrane. Therefore, the An-Nup84-120 complex performs roles, perhaps at the NPC membrane as proposed previously, that become essential without the An-Ndc1 transmembrane Nup.

scholarly journals Mitosis in the cellular slime mold Polysphondylium violaceum.

1975 ◽  
Vol 64 (2) ◽  
pp. 480-491 ◽  
Author(s):  
U P Roos
Keyword(s):  
Spindle Pole ◽  
Equatorial Region ◽  
Cellular Slime Mold ◽  
Central Spindle ◽  
Spindle Pole Bodies ◽  
Cellular Slime ◽  
Late Telophase ◽  
Spindle Elongation ◽  
Well Differentiated ◽  
Opaque Body

Myxamebas of Polysphondylium violaceum were grown in liquid medium and processed for electron microscopy. Mitosis is characterized by a persistent nuclear envelope, ring-shaped extranuclear spindle pole bodies (SPBs), a central spindle spatially separated from the chromosomal microtubules, well-differentiated kinetochores, and dispersion of the nucleoli. SPBs originate from the division, during prophase, of an electron-opaque body associated with the interphase nucleus. The nuclear nevelope becomes fenestrated in their vicinity, allowing the build-up of the intranuclear, central spindle and chromosomal microtubules as the SPBs migrate to opposite poles. At metaphase the chromosomes are in amphitelic orientation, each sister chromatid being directly connected to the corresponding SPB by a single microtubule. During ana- and telophase the central spindle elongates, the daughter chromosomes approach the SPBs, and the nucleus constricts in the equatorial region. The cytoplasm cleaves by furrowing in late telophase, which is in other respects characterized by a re-establishment of the interphase condition. Spindle elongation and poleward movement of chromosomes are discussed in relation to hypotheses of the mechanism of mitosis.

scholarly journals Requirement for ESP1 in the nuclear division of Saccharomyces cerevisiae.

1992 ◽  
Vol 3 (12) ◽  
pp. 1443-1454 ◽  
Author(s):  
J T McGrew ◽  
L Goetsch ◽  
B Byers ◽  
P Baum
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Normal Cell ◽  
Cell Cycle Progression ◽  
Nuclear Division ◽  
Flow Cytometric Analysis ◽  
Spindle Pole ◽  
Spindle Pole Bodies ◽  
Mutant Cells ◽  
Normal Cell Cycle

Mutations in the ESP1 gene of Saccharomyces cerevisiae disrupt normal cell-cycle control and cause many cells in a mutant population to accumulate extra spindle pole bodies. To determine the stage at which the esp1 gene product becomes essential for normal cell-cycle progression, synchronous cultures of ESP1 mutant cells were exposed to the nonpermissive temperature for various periods of time. The mutant cells retained viability until the onset of mitosis, when their viability dropped markedly. Examination of these cells by fluorescence and electron microscopy showed the first detectable defect to be a structural failure in the spindle. Additionally, flow cytometric analysis of DNA content demonstrated that massive chromosome missegregation accompanied this failure of spindle function. Cytokinesis occurred despite the aberrant nuclear division, which often resulted in segregation of both spindle poles to the same cell. At later times, the missegregated spindle pole bodies entered a new cycle of duplication, thereby leading to the accumulation of extra spindle pole bodies within a single nucleus. The DNA sequence predicts a protein product similar to those of two other genes that are also required for nuclear division: the cut1 gene of Schizosaccharomyces pombe and the bimB gene of Aspergillus nidulans.

scholarly journals Mitosis in the fission yeast Schizosaccharomyces pombe as revealed by freeze-substitution electron microscopy

1986 ◽  
Vol 80 (1) ◽  
pp. 253-268
Author(s):  
K. Tanaka ◽  
T. Kanbe
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Mitotic Spindle ◽  
Nuclear Division ◽  
Freeze Substitution ◽  
Spindle Pole ◽  
Nuclear Space ◽  
Spindle Pole Bodies ◽  
Transmission Electron ◽  
Cytoplasmic Microtubules ◽  
Spindle Microtubules

Nuclear division in Schizosaccharomyces pombe has been studied in transmission electron micrographs of sections of cells fixed by a method of freeze-substitution. We have found cytoplasmic microtubules in the vicinity of the spindle pole bodies and two kinds of microtubules, short discontinuous ones and long, parallel ones in the intranuclear mitotic spindle. For most of the time taken by nuclear division the spindle pole bodies face each other squarely across the nuclear space but early in mitosis they briefly appear twisted out of alignment with each other, thereby imparting a sigmoidal shape to the bundle of spindle microtubules extending between them. This configuration is interpreted as indicating active participation of the spindle in the initial elongation of the dividing nucleus. It is proposed that mitosis is accompanied by the shortening of chromosomal microtubules simultaneously with the elongation of the central pole-to-pole bundle of microtubules of the intranuclear spindle. Daughter nuclei are separated by the sliding apart of interdigitating microtubules of the spindle at telophase. Some of the latter bear dense knobs at their ends.

Chromatin behaviour during the mitotic cell cycle of Saccharomyces cerevisiae

1977 ◽  
Vol 24 (1) ◽  
pp. 81-93
Author(s):  
C.N. Gordon
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Nuclear Division ◽  
Mitotic Cell ◽  
Spindle Pole ◽  
Chromosomal Distribution ◽  
Yeast Saccharomyces Cerevisiae ◽  
Thin Sections ◽  
Daughter Cells ◽  
Spindle Pole Bodies ◽  
Direct Attachment

Chromatin behaviour during the cell division cycle of the yeast Saccharomyces cerevisiae has been investigated in cells which have been depleted of 90% of their RNA by digestion with ribonuclease. Removal of large amounts of RNA from the yeast nucleus before treatment of the cells with heavy metal fixatives and stains permits chromatin to be visualized with extreme clarity in thin sections of cells processed for electron microscopy by conventional procedures. Spindle pole bodies were also visualized by this treatment, although the associated microtubules were not. Chromatin is dispersed during interphase and occupies the non-nucleolar region of the nucleus which is known to be Feulgen-positive from light microscopy. Because spindle microtubules are not visualized, direct attachment of microtubules to chromatin fibrils could not be verified. However, chromatin was not attached directly to the spindle pole bodies and kinetochore differentiations were not observed in the nucleoplasm. During nuclear division chromatin remains dispersed and does not condense into discrete chromatids. As the nucleus expands into the bud, chromosomal distribution to the daughter cells is thought to result from the separation of the poles of the spindle apparatus with attached chromatin fibrils. However, that such distribution is occurring as the nucleus elongates is not obvious until an advanced stage of nuclear division is reached and partition of the nucleus is nearly complete. Thus, no aggregation of chromatin into metaphase or anaphase plates occurs and the appearance of chromatin during mitosis is essentially the same as in interphase. These observations indicate that the marked changes in the topological structure of chromatin which characterize mitosis in the higher eukaryotes do not occur in S. cerevisiae.

Yeast-Like Endosymbionts in an Ichneumonid Wasp

1984 ◽  
Vol 39 (3-4) ◽  
pp. 322-326 ◽  
Author(s):  
J. Middeldorf ◽  
A. Ruthmann
Keyword(s):  
Nuclear Envelope ◽  
Spindle Pole ◽  
Next Generation ◽  
Vegetative Cells ◽  
Host Cytoplasm ◽  
Spindle Pole Bodies ◽  
Pathogenic Infection

Vegetative cells and spores of a yeast-like micro organism found in various tissues in both sexes of the ichneumonid wasp Pimpla turionellae are passed to the offspring by infection of the oocytes. Because of their intranuclearspindles with spindle pole bodies associated with the nuclear envelope as pole structures, the microorganisms are thought to be yeasts or closely related to yeasts. The high vitality and fertility of the wasps seem to exclude a pathogenic infection. Both the passage of vesicles from the microorganisms to the host cytoplasm and their transmission to the next generation by the oocytes point to anendosymbiotic relationship

Somatic nuclear division in the sporidia of Ustilago violacea. III. Ultrastructural observations

1976 ◽  
Vol 22 (4) ◽  
pp. 495-506 ◽  
Author(s):  
N. H. Poon ◽  
A. W. Day
Keyword(s):  
Daughter Cell ◽  
Daughter Nucleus ◽  
Nuclear Division ◽  
Spindle Pole ◽  
The Other ◽  
Parent Cell ◽  
Electron Microscopic ◽  
Ustilago Violacea ◽  
Left Behind ◽  
Spindle Pole Bodies

The paper provides detailed ultrastructural observations on nuclear division in the smut fungus Ustilago violacea and is based on previous light-microscopic work outlining the division in living and stained cells. The division as in many other Basidiomycetes is not intranuclear, but occurs within a partially disrupted membrane. The division takes place after migration of most of the nucleus into the bud cell, after limited breakdown of the nuclear membrane, and after the formation of a spindle between two spindle-pole bodies (SPB). The remaining part of the nucleus containing the nucleolus is left behind in the parent cell and degenerates there. The SPB, as in other Basidiomycetes, is a dome-shaped relatively structureless body, quite distinct from the flat plaques of many Ascomycetes and the elaborate centrioles of Phycomycetes. The SPB divides shortly before migration into the daughter cell and invariably is located at the apex of the migrating nucleus. Nuclear division is completed when the two masses of chromatin clustered about each of the SPB's are separated as the spindle elongates. One daughter nucleus reforms in the bud and the other is reformed in the mother cell.Cells fixed and stained by conventional light-microscopic methods were examined in the light of the electron-microscopic observations to determine whether these procedures induce artefacts. Aceto-orcein and Giemsa when used cold were found to produce relatively artefact-free preparations. However, previous results in which the cells were warmed gently in these stains are now seen to contain artefacts in the form of contracted chromatinic granules often arranged in chains. These artefacts may provide useful information but clearly they must be interpreted cautiously until the nature of the changes induced by heating are known.

Nuclear division and chromosome behavior during meiosis and ascosporogenesis in Pyricularia oryzae

1987 ◽  
Vol 65 (1) ◽  
pp. 112-123 ◽  
Author(s):  
Hei Leung ◽  
P. H. Williams
Keyword(s):  
Magnaporthe Grisea ◽  
Nuclear Division ◽  
Spindle Pole ◽  
Pyricularia Oryzae ◽  
Maximum Diameter ◽  
Chromosome Movement ◽  
Chromosome Behavior ◽  
Electron Microscopic ◽  
Homologous Chromosomes ◽  
Spindle Pole Bodies

Meiosis and mitoses during ascosporogenesis in fertile mating strains of Pyricularia oryzae Cavara (teleomorph: Magnaporthe grisea) were studied using a propionic–iron–hematoxylin procedure which stained chromosomes, nucleolus, and spindle pole bodies. Meioses and mitoses in P. oryzae resembled those in other ascomycetes. Zygotene chromosomes were highly contracted followed by elongation at pachytene when close pairings of homologous chromosomes were observed. Nucleoli attained a maximum diameter of 3.8 μm during pachytene. Nucleolar growth was accompanied by a rapid growth of the ascus. Chromosome lengths varied among pachytene cells, with the longest chromosome averaging 8.5 and the smallest 2.9 μm. Telomeric knobs and chromomeres were discernible on fully extended pachytene chromosomes. Six chromosomes were observed at pachytene and diakinesis, and during metaphase of ascospore mitosis. Chromosome movement at meiotic and mitotic anaphase was asynchronous, resulting in lagging chromosomes. Electron microscopic observations revealed spindle pole bodies associated with profusion and early meiotic prophase nuclei. In pachytene nuclei, 50 nm wide structures resembling synaptonemal complexes were observed.

scholarly journals Control of the mitotic exit network during meiosis

2012 ◽  
Vol 23 (16) ◽  
pp. 3122-3132 ◽  
Author(s):  
Michelle A. Attner ◽  
Angelika Amon
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Signaling Pathway ◽  
Vegetative Growth ◽  
Spindle Pole ◽  
Mitotic Exit ◽  
Regulatory Pathways ◽  
Spindle Pole Bodies ◽  
Mitotic Exit Network ◽  
Meiosis I

The mitotic exit network (MEN) is an essential GTPase signaling pathway that triggers exit from mitosis in budding yeast. We show here that during meiosis, the MEN is dispensable for exit from meiosis I but contributes to the timely exit from meiosis II. Consistent with a role for the MEN during meiosis II, we find that the signaling pathway is active only during meiosis II. Our analysis further shows that MEN signaling is modulated during meiosis in several key ways. Whereas binding of MEN components to spindle pole bodies (SPBs) is necessary for MEN signaling during mitosis, during meiosis MEN signaling occurs off SPBs and does not require the SPB recruitment factor Nud1. Furthermore, unlike during mitosis, MEN signaling is controlled through the regulated interaction between the MEN kinase Dbf20 and its activating subunit Mob1. Our data lead to the conclusion that a pathway essential for vegetative growth is largely dispensable for the specialized meiotic divisions and provide insights into how cell cycle regulatory pathways are modulated to accommodate different modes of cell division.

Sign in / Sign up

Export Citation Format

Share Document