Somatic nuclear division in the sporidia of Ustilago violacea. IV. Microtubules and the spindle-pole body

1976 ◽  
Vol 22 (4) ◽  
pp. 507-522 ◽  
Author(s):  
N. H. Poon ◽  
A. W. Day
Keyword(s):  
Nuclear Membrane ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Control Center ◽  
Ustilago Violacea ◽  
Membrane Breakdown ◽  
Pole Body ◽  
Free Region ◽  
Nuclear Rotation ◽  
Anther Smut

In unbudded cells of the anther smut fungus Ustilago violacea there is a dome-shaped spindle-pole body (SPB) consisting of a core 0.1 μm in diameter surrounded by a ribosome-free region 0.3–0.4 μm in diameter lying in a pocket of the nuclear membrane. After budding the nucleus moves towards the bud and begins to rotate rapidly. At about this stage the SPB divides into two parallel bars each about 0.1–0.15 μm in diameter and 0.3 μm long, separated by a distance of about 0.3 μm. Microtubules associated with the nuclear membrane but not with the SPB are present at the time of nuclear rotation. These microtubules disappear when rotation stops. Microtubules attached to the SPB are found during migration of the chromatinic portion of the nucleus into the bud cell. These microtubules disappear when migration stops and the nuclear membrane begins to break down. The twin SPB bars appear to move into the nucleus through a break in the membrane and begin to move apart forming a spindle about 1 μm long. Chromosomal microtubules (one per kinetochore) were found in several serial sections, and in addition there appeared to be several continuous microtubules present. The separation of the two chromatinic masses appeared to result from elongation of the continuous microtubules to about 3 μm long. Cytoplasmic microtubules and spindle microtubules were both found attached to the SPB as it elongated and one nucleus returned to the mother cell.The paper concludes with a discussion of the SPB as a multifunctional control center affecting nuclear migration, spindle formation, membrane breakdown and synthesis, karyogamy, conjugation, budding, chromosomal movement, replication, and disjunction.

scholarly journals Requirement of the spindle pole body for targeting and/or tethering proteins to the inner nuclear membrane

Nucleus ◽  
2014 ◽  
Vol 5 (4) ◽  
pp. 352-366 ◽  
Author(s):  
Greetchen Diaz-Muñoz ◽  
Terri A Harchar ◽  
Tsung-Po Lai ◽  
Kuo-Fang Shen ◽  
Anita K Hopper
Keyword(s):  
Nuclear Membrane ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Inner Nuclear Membrane ◽  
Pole Body

scholarly journals Targeting of Nbp1 to the inner nuclear membrane is essential for spindle pole body duplication

2011 ◽  
Vol 30 (16) ◽  
pp. 3337-3352 ◽  
Author(s):  
Thomas Kupke ◽  
Leontina Di Cecco ◽  
Hans-Michael Müller ◽  
Annett Neuner ◽  
Frank Adolf ◽  
...  
Keyword(s):  
Nuclear Membrane ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Inner Nuclear Membrane ◽  
Pole Body

Ultrastructure of mitosis and the spindle pole body cycle in the smut fungus, Tilletia foetida

1985 ◽  
Vol 63 (1) ◽  
pp. 86-96 ◽  
Author(s):  
James A. Hoffmann ◽  
Blair J. Goates
Keyword(s):  
Nuclear Membrane ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Dense Layer ◽  
Double Structure ◽  
Pole Body ◽  
Cytoplasmic Microtubules ◽  
Spindle Microtubules ◽  
Dense Chromatin ◽  
Tilletia Foetida

The interphase nucleus in secondary sporidia of Tilletia foetida consists of mostly diffuse chromatin, one or two nucleoli, and an area of heterochromatin located opposite an electron-dense, extranuclear spindle pole body (SPB). The interphase SPB is an oval- to bar-shaped, double-structured disc that has a crystallinelike substructure. During nuclear migration into nascent sporidia, SPBs and nucleoli are randomly oriented. At the onset of division, chromatin begins to condense and the SPB becomes located on a nuclear protuberance. Cytoplasmic microtubules terminate at the SPBs and multivesicular bodies surround the SPBs from the early stages of SPB division to early postdivision. SPB discs become spheroid and each develops a medial, dense layer. Then, a basal, dense layer develops and elongates as the SPBs separate and become positioned on opposite sides of the nuclear protuberance. The nuclear membrane opens opposite the SPB during SPB division. The nucleolus is extruded into a nuclear bleb and degenerates. SPBs migrate to opposing sides of the nucleus and become diffuse as a microtubular spindle develops between them. Some spindle microtubules terminate at dense chromatin patches that are contiguous with the major mass of chromatin surrounding the spindle. During late division stages, spindle microtubules often appear to be closely juxtaposed. Except for polar openings adjacent to the SPBs, the nuclear membrane is entire until late division when it degenerates in the midregion of the nucleus. During early postdivision, the SPB condenses into a small, dense sphere as the chromatin and heterochromatin opposite the SPB become diffuse. The SPB then elongates into a dense bar and SPB material increases, except at the midportion, reforming the double structure of interphase.

The Control of Karyogamy in Somatic Cells of Ustilago Violacea

1974 ◽  
Vol 15 (3) ◽  
pp. 619-632
Author(s):  
A. W. DAY ◽  
LYNNE L. DAY
Keyword(s):  
Somatic Cells ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Dark Repair ◽  
Absolute Increase ◽  
Ustilago Violacea ◽  
Pole Body ◽  
Large Numbers ◽  
High Doses ◽  
Very High

The rate of nuclear fusion (karyogamy) in the haploid smut fungus, Ustilago violacea, designated D, can be determined accurately from the frequency of diploid formation. The spontaneous value of D depends mainly on the age of the cells and the temperature, varying from 10-5 to 10-2. Ultraviolet light (u.v., 254 nm) induces high rates of fusion, up to 100 % of the survivors being diploid after very high doses. That this increase is caused by induction and not by selection is shown by the absolute increase in the number of diploids obtained under some conditions. The high value of D after a u.v. treatment is reduced by conditions which favour photoreactivation or dark repair. Acriflavine, an inhibitor of dark repair, maintains high values of D, while caffeine which also inhibits dark repair abolishes the u.v. induction entirely. Ultraviolet-sensitive mutants located at 4 loci were tested for their effect on spontaneous and u.v.-induced karyogamy. One mutant (uvs4) showed complete absence of somatic karyogamy even after high doses of ultraviolet. Mutant uvs2 had no effect on the value of D, while mutants uvs1 and uvs3 showed low spontaneous karyogamy, but could be induced by low doses of u.v. to yield large numbers of diploids. It is suggested that an inhibitor of karyogamy is formed in somatic cells and destroyed prior to premeiotic karyogamy. The accuracy of the transcription of this inhibitor seems to be impaired by ultraviolet, but can be restored following DNA repair. The absence of somatic karyogamy in uvs4 mutants may indicate that these strains contain an altered organelle involved in the control of karyogamy, e.g. the spindle pole body situated on the nuclear membrane, and known to contain DNA. Alteration of such an organelle could produce pleiotropic effects including u.v. sensitivity and inhibitor production or action.

scholarly journals The SUN Protein Mps3 Is Required for Spindle Pole Body Insertion into the Nuclear Membrane and Nuclear Envelope Homeostasis

PLoS Genetics ◽  
2011 ◽  
Vol 7 (11) ◽  
pp. e1002365 ◽  
Author(s):  
Jennifer M. Friederichs ◽  
Suman Ghosh ◽  
Christine J. Smoyer ◽  
Scott McCroskey ◽  
Brandon D. Miller ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Membrane ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
The Sun ◽  
Pole Body

scholarly journals Membrane proteins Bqt3 and -4 anchor telomeres to the nuclear envelope to ensure chromosomal bouquet formation

2009 ◽  
Vol 187 (3) ◽  
pp. 413-427 ◽  
Author(s):  
Yuji Chikashige ◽  
Miho Yamane ◽  
Kasumi Okamasa ◽  
Chihiro Tsutsumi ◽  
Tomoko Kojidani ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Fission Yeast ◽  
Nuclear Membrane ◽  
Meiotic Prophase ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Null Mutant ◽  
Vegetative Cells ◽  
Nuclear Membranes ◽  
Pole Body

In many organisms, telomeres cluster to form a bouquet arrangement of chromosomes during meiotic prophase. Previously, we reported that two meiotic proteins, Bqt1 and -2, are required for tethering telomeres to the spindle pole body (SPB) during meiotic prophase in fission yeast. This study has further identified two novel, ubiquitously expressed inner nuclear membrane (INM) proteins, Bqt3 and -4, which are required for bouquet formation. We found that in the absence of Bqt4, telomeres failed to associate with the nuclear membranes in vegetative cells and consequently failed to cluster to the SPB in meiotic prophase. In the absence of Bqt3, Bqt4 protein was degraded during meiosis, leading to a phenotype similar to that of the bqt4-null mutant. Collectively, these results show that Bqt4 anchors telomeres to the INM and that Bqt3 protects Bqt4 from protein degradation. Interestingly, the functional integrity of telomeres is maintained even when they are separated from the nuclear envelope in vegetative cells.

The transition of cells of the fission yeast beta-tubulin mutant nda3-311 as seen by freeze-substitution electron microscopy. Requirement of functional tubulin for spindle pole body duplication

1990 ◽  
Vol 96 (2) ◽  
pp. 275-282
Author(s):  
T. Kanbe ◽  
Y. Hiraoka ◽  
K. Tanaka ◽  
M. Yanagida
Keyword(s):  
Electron Microscopy ◽  
Cross Section ◽  
Nuclear Membrane ◽  
Mitotic Spindle ◽  
Spindle Pole Body ◽  
Freeze Substitution ◽  
Spindle Pole ◽  
Permissive Temperature ◽  
Beta Tubulin ◽  
Pole Body

A previous fluorescence light-microscopic study showed that the fission yeast cold-sensitive beta-tubulin mutant nda3-311 was arrested with rod-like condensed chromosomes in a mitotic state at the restrictive temperature. Upon transfer to the permissive temperature, a spindle was formed and the nucleus was divided. In the present study, we employed freeze-substitution electron microscopy to examine the ultrastructure of arrested and released nda3-311 cells. In arrested cells, a single, displaced nucleus was seen with a single spindle pole body. Therefore, spindle pole body duplication seemed to require functional beta-tubulin. The nuclear membrane was highly deformed with a leaf-like profile in cross-section, possibly due to an interaction with the rod-like, condensed chromosomes. Upon transfer to the permissive temperature, the spindle pole duplicated and the daughter spindle pole bodies rapidly migrated to the opposite ends of the nucleus, accompanied by the formation of the mitotic spindle. Elongation of the nuclear envelope occurred with concomitant spindle extension, as in a wild-type mitosis. The deformed nuclear membrane became smooth and described a convex curve. The numerous vacuoles that are seen in the arrested cells decreased in number and increased in size. Septation was completed, leaving the two divided nuclei in one half of the cell. Hexagonally arranged microtubules, apparently forming the mitotic spindle, were observed in a cross-section of a cell after return to the permissive conditions.

scholarly journals Comparative analysis of Synthetic Physical Interactions with the yeast centrosome

2019 ◽  
Author(s):  
Rowan S M Howell ◽  
Attila Csikász-Nagy ◽  
Peter H Thorpe
Keyword(s):  
Data Analysis ◽  
Comparative Analysis ◽  
Chromosome Segregation ◽  
Nuclear Membrane ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Growth Defects ◽  
Pole Body ◽  
Physical Interactions ◽  
Spindle Microtubules

1AbstractThe yeast centrosome or Spindle Pole Body (SPB) is situated in the nuclear membrane, where it nucleates spindle microtubules and acts as a signalling hub. Previously, we used Synthetic Physical Interactions to map the regions of the cell that are sensitive to forced relocalization of proteins across the proteome [Berry et al., 2016]. Here, we expand on this work to show that the SPB, in particular, is sensitive to the relocalization of many proteins. This work inspired a new data analysis approach that indicates that relocalization screens may produce more growth defects than previously reported. A set of associations with the SPB result in elevated SPB number and since hyper-proliferation of centrosomes is a hallmark of cancer cells, these associations point the way for the use of yeast models in the study of spindle formation and chromosome segregation in cancer.

scholarly journals The product of the spindle formation gene sad1+ associates with the fission yeast spindle pole body and is essential for viability.

1995 ◽  
Vol 129 (4) ◽  
pp. 1033-1047 ◽  
Author(s):  
I Hagan ◽  
M Yanagida
Keyword(s):  
Fission Yeast ◽  
Nuclear Membrane ◽  
Essential Gene ◽  
Nuclear Periphery ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Temperature Sensitive ◽  
Spindle Formation ◽  
Isolation And Characterization ◽  
Pole Body

Spindle formation in fission yeast occurs by the interdigitation of two microtubule arrays extending from duplicated spindle pole bodies which span the nuclear membrane. By screening a bank of temperature-sensitive mutants by anti-tubulin immunofluorescence microscopy, we previously identified the sad1.1 mutation (Hagan, I., and M. Yanagida. 1990. Nature (Lond.). 347:563-566). Here we describe the isolation and characterization of the sad1+ gene. We show that the sad1.1 mutation affected both spindle formation and function. The sad1+ gene is a novel essential gene that encodes a protein with a predicted molecular mass of 58 kD. Deletion of the gene was lethal resulting in identical phenotypes to the sad1.1 mutation. Sequence analysis predicted a potential membrane-spanning domain and an acidic amino terminus. Sad1 protein migrated as two bands of 82 and 84 kD on SDS-PAGE, considerably slower than its predicted mobility, and was exclusively associated with the spindle pole body (SPB) throughout the mitotic and meiotic cycles. Microtubule integrity was not required for Sad1 association with the SPB. Upon the differentiation of the SPB in metaphase of meiosis II, Sad1-staining patterns similarly changed from a dot to a crescent supporting an integral role in SPB function. Moderate overexpression of Sad1 led to association with the nuclear periphery. As Sad1 was not detected in the cytoplasmic microtubule-organizing centers activated at the end of anaphase or kinetochores, we suggest that Sad1 is not a general component of microtubule-interacting structures per se, but is an essential mitotic component that associates with the SPB but is not required for microtubule nucleation. Sad1 may play a role in SPB structure, such as maintaining a functional interface with the nuclear membrane or in providing an anchor for the attachment of microtubule motor proteins.

scholarly journals Spc42p: a phosphorylated component of the S. cerevisiae spindle pole body (SPD) with an essential function during SPB duplication.

1996 ◽  
Vol 132 (5) ◽  
pp. 887-901 ◽  
Author(s):  
A D Donaldson ◽  
J V Kilmartin
Keyword(s):  
Nuclear Membrane ◽  
Spindle Pole Body ◽  
Coiled Coil ◽  
Spindle Pole ◽  
Normal Function ◽  
Temperature Sensitive ◽  
Pole Body ◽  
Polymeric Layer ◽  
Essential Function ◽  
Mutant Cells

The 42-kD component of the S. cerevisiae spindle pole body (SPB) localizes to the electron-dense central plaque of the SPB. We have cloned the corresponding gene SPC42 (spindle pole component) and show that it is essential. Seven temperature-sensitive (ts) mutants in SPC42 were prepared by error-prone PCR. We found that a change to a proline residue in a potential coiled-coil region of Spc42p was responsible for the ts phenotype in at least three alleles, suggesting that formation of the coiled-coil is essential in normal function. The mutant cells showed a phenotype of predominantly single or bilobed SPBs often with an accumulation of unstructured electron-dense material associated with the bridge structure adjacent to the SPB. This phenotype suggests a defect in SPB duplication. This was confirmed by examining synchronized mutant cells that lose viability when SPB duplication is attempted. Spc42p is a phosphoprotein which shows some cell cycle-regulated phosphorylation. Overexpression of Spc42p causes the formation of a disc- or dome-shaped polymer composed of phosphorylated Spc42p, which is attached to the central plaque and associated with the outer nuclear membrane. Taken together, these data suggest that Spc42p forms a polymeric layer at the periphery of the SPB central plaque which has an essential function during SPB duplication and may facilitate attachment of the SPB to the nuclear membrane.

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