Mitosis and cell division in some cereal rust fungi. I. Fine structure of the interphase and premitotic nuclei

1976 ◽  
Vol 54 (9) ◽  
pp. 981-994 ◽  
Author(s):  
D. E. Harder
Keyword(s):  
Nuclear Envelope ◽  
Higher Plants ◽  
Spindle Pole Body ◽  
Axenic Culture ◽  
Amorphous Layer ◽  
Spindle Pole ◽  
Rust Fungi ◽  
Regular Feature ◽  
Physiologic Condition ◽  
Nucleolar Extrusion

The detailed structure of the nucleus and its associated suborganelles in the rust fungi Puccinia graminis tritici, P. graminis avenue, P. recondita, and P. coronata is described. The non-mitotic nuclei in intercellular hyphae of all of the fungi examined were irregularly oval in shape and had prominent nucleoli, and except for P. recondita, heterochromatin was usually uniformly dispersed. In P. recondita, densely staining patches occurred throughout the nucleus, and this was a distinguishing feature of this species. The nuclei in monokaryotic axenic cultures of P. graminis tritici and P. coronata were larger than those in their respective dikaryotic parasitic hyphae or in a dikaryotic axenic culture of P. graminis tritici.The nucleoli varied in size and composition, depending on the physiologic condition or type of cell. In senescing cells the nucleoli occupied about 10% of the nuclear volume, while in young active cells the respective volume occupied was up to 60%. In haustoria the nucleoli were smaller in size and were composed mainly of fibrillar material. In active intercellular hyphae of all of the fungi examined the nucleoli consisted of about equal granular and fibrillar regions. There was a lighter-staining central region and similar light spaces in the fibrillar zones. These light areas were similar to the nucleoplasm in appearance and were interpreted as lacunae possibly continuous with the nucleoplasm. The rust fungal nucleoli and those of some higher plants were compared.A bipolar spindle pole body (SPB) was a regular feature of non-mitotic nuclei. The SPB consisted of two disc-like structures located some distance apart on a layer of amorphous substance. The SPB was located outside the nucleus in a depression of the nuclear envelope, usually toward one side of the nucleus. Subtending the SPB in the nucleus and joined to the SPB via a large pore in the nuclear envelope was a moderately dense region which consisted of an amorphous layer from which loose threads radiated into the nucleus. Occasionally a thread connected this region to the nucleolus.In several cells the nuclei were deformed with concomitant extrusion of the nucleoli. Nucleolar extrusion was seen in all material examined, and the process is described. Nuclear deformation and nucleolar extrusion were considered to be indicators of premitotic nuclei.

Fine structure of the haplosporidan Kernstab, a persistent, intranuclear mitotic apparatus

1975 ◽  
Vol 18 (2) ◽  
pp. 327-346
Author(s):  
F.O. Perkins
Keyword(s):  
Fine Structure ◽  
Nuclear Envelope ◽  
Light Microscope ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Interphase Nuclei ◽  
Mitotic Apparatus ◽  
Pole Body

The fine structure of the haplosporidan mitotic apparatus is described from observations of plasmodial nuclei of Minchinia nelsoni, M. costalis, Minchinia sp., and Urosporidium crescens. The apparatus, which is the Kernstab of light-microscope studies, consists of a bundle of microtubules terminating in a spindle pole body (SPB) at each end of the bundle. A few microtubules extend from SPB to SPB, but most either extend from an SPB and terminate in the nucleoplasm or lie in the nucleoplasm, free of either SPB. The bundle lengthens during mitosis, increasing the SPB-to-SPB distance by a factor of 2 to 3 as compared to interphase nuclei. SPBs are not in contact with the nuclear envelope, being found always in the nucleoplasm which is delimited by the nuclear envelope throughout mitosis. The mitotic apparatus is persistent through interphase, at least in a form which is not significantly different from that found in mitotic nuclei.

scholarly journals Redistribution of centrosomal proteins by centromeres and Polo kinase controls nuclear envelope breakdown

2020 ◽  
Author(s):  
Andrew J. Bestul ◽  
Zulin Yu ◽  
Jay R. Unruh ◽  
Sue L. Jaspersen
Keyword(s):  
Nuclear Envelope ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Ring Structure ◽  
Yeast Cells ◽  
Structured Illumination ◽  
Structured Illumination Microscopy ◽  
Spindle Formation ◽  
Nuclear Envelope Breakdown ◽  
Polo Kinase

AbstractProper mitotic progression in Schizosaccharomyces pombe requires partial nuclear envelope breakdown (NEBD) and insertion of the spindle pole body (SPB – yeast centrosome) to build the mitotic spindle. Linkage of the centromere to the SPB is vital to this process, but why that linkage is important is not well understood. Utilizing high-resolution structured illumination microscopy (SIM), we show that the conserved SUNprotein Sad1 and other SPB proteins redistribute during mitosis to form a ring complex around SPBs, which is a precursor for NEBD and spindle formation. Although the Polo kinase Plo1 is not necessary for Sad1 redistribution, it localizes to the SPB region connected to the centromere, and its activity is vital for SPB ring protein redistribution and for complete NEBD to allow for SPB insertion. Our results lead to a model in which centromere linkage to the SPB drives redistribution of Sad1 and Plo1 activation that in turn facilitate NEBD and spindle formation through building of an SPB ring structure.SummaryNuclear envelope breakdown is necessary for fission yeast cells to go through mitosis. Bestul et al. show that the SUN protein, Sad1, is vital in carrying out this breakdown and is regulated by the centromere and Polo kinase.

scholarly journals The Sad1-UNC-84 homology domain in Mps3 interacts with Mps2 to connect the spindle pole body with the nuclear envelope

2006 ◽  
Vol 174 (5) ◽  
pp. 665-675 ◽  
Author(s):  
Sue L. Jaspersen ◽  
Adriana E. Martin ◽  
Galina Glazko ◽  
Thomas H. Giddings ◽  
Garry Morgan ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Integral Membrane Proteins ◽  
Microtubule Nucleation ◽  
The Core ◽  
Pole Body ◽  
C Terminus ◽  
Bridge Structures ◽  
Sun Domain

The spindle pole body (SPB) is the sole site of microtubule nucleation in Saccharomyces cerevisiae; yet, details of its assembly are poorly understood. Integral membrane proteins including Mps2 anchor the soluble core SPB in the nuclear envelope. Adjacent to the core SPB is a membrane-associated SPB substructure known as the half-bridge, where SPB duplication and microtubule nucleation during G1 occurs. We found that the half-bridge component Mps3 is the budding yeast member of the SUN protein family (Sad1-UNC-84 homology) and provide evidence that it interacts with the Mps2 C terminus to tether the half-bridge to the core SPB. Mutants in the Mps3 SUN domain or Mps2 C terminus have SPB duplication and karyogamy defects that are consistent with the aberrant half-bridge structures we observe cytologically. The interaction between the Mps3 SUN domain and Mps2 C terminus is the first biochemical link known to connect the half-bridge with the core SPB. Association with Mps3 also defines a novel function for Mps2 during SPB duplication.

scholarly journals N-terminal regions of Mps1 kinase determine functional bifurcation

2010 ◽  
Vol 189 (1) ◽  
pp. 41-56 ◽  
Author(s):  
Yasuhiro Araki ◽  
Linda Gombos ◽  
Suellen P.S. Migueleti ◽  
Lavanya Sivashanmugam ◽  
Claude Antony ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Chemical Biology ◽  
Molecular Level ◽  
Budding Yeast ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Deletion Analysis ◽  
Checkpoint Activation ◽  
Pole Body ◽  
N Terminus

Mps1 is a conserved kinase that in budding yeast functions in duplication of the spindle pole body (SPB), spindle checkpoint activation, and kinetochore biorientation. The identity of Mps1 targets and the subdomains that convey specificity remain largely unexplored. Using a novel combination of systematic deletion analysis and chemical biology, we identified two regions within the N terminus of Mps1 that are essential for either SPB duplication or kinetochore biorientation. Suppression analysis of the MPS1 mutants defective in SPB duplication and biochemical enrichment of Mps1 identified the essential SPB components Spc29 and the yeast centrin Cdc31 as Mps1 targets in SPB duplication. Our data suggest that phosphorylation of Spc29 by Mps1 in G1/S recruits the Mps2–Bbp1 complex to the newly formed SPB to facilitate its insertion into the nuclear envelope. Mps1 phosphorylation of Cdc31 at the conserved T110 residue controls substrate binding to Kar1 protein. These findings explain the multiple SPB duplication defects of mps1 mutants on a molecular level.

Ultrastructure of somatic mitosis in a diploid strain of the plant pathogenic fungus Cochliobolus sativus

1975 ◽  
Vol 53 (4) ◽  
pp. 403-414 ◽  
Author(s):  
H. C. Huang ◽  
R. D. Tinline ◽  
L. C. Fowke
Keyword(s):  
Nuclear Envelope ◽  
Ultrastructural Study ◽  
Pathogenic Fungus ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Cochliobolus Sativus ◽  
Diploid Strain ◽  
Interphase Nuclei ◽  
Pole Body ◽  
Spindle Microtubules

An ultrastructural study of mitosis in a diploid strain of Cochliobolus sativus showed the event to be intranuclear. Two nucleoli occasionally were present in interphase nuclei. During division the spindle pole body peripheral to the nuclear envelope divided; spindle microtubules radiated into the nucleoplasm from the amorphous granular region abutting the nuclear envelope beneath the bodies; chromosomes condensed at prophase, approached the equatorial plane at metaphase, and moved asynchronously at anaphase; single microtubules appeared attached to kinetochore-like structures. At telophase, nuclei exhibited maximal elongation; fissures of the nuclear envelope appeared in the interzonal region; the nucleolus dispersed. The polar nuclear areas became new daughter nuclei with nucleoli.

scholarly journals LEM2 recruits CHMP7 for ESCRT-mediated nuclear envelope closure in fission yeast and human cells

2017 ◽  
Vol 114 (11) ◽  
pp. E2166-E2175 ◽  
Author(s):  
Mingyu Gu ◽  
Dollie LaJoie ◽  
Opal S. Chen ◽  
Alexander von Appen ◽  
Mark S. Ladinsky ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Fission Yeast ◽  
Nuclear Membrane ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Human Cells ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Loss Of Function

Endosomal sorting complexes required for transport III (ESCRT-III) proteins have been implicated in sealing the nuclear envelope in mammals, spindle pole body dynamics in fission yeast, and surveillance of defective nuclear pore complexes in budding yeast. Here, we report that Lem2p (LEM2), a member of the LEM (Lap2-Emerin-Man1) family of inner nuclear membrane proteins, and the ESCRT-II/ESCRT-III hybrid protein Cmp7p (CHMP7), work together to recruit additional ESCRT-III proteins to holes in the nuclear membrane. InSchizosaccharomyces pombe, deletion of the ATPasevps4leads to severe defects in nuclear morphology and integrity. These phenotypes are suppressed by loss-of-function mutations that arise spontaneously inlem2orcmp7, implying that these proteins may function upstream in the same pathway. Building on these genetic interactions, we explored the role of LEM2 during nuclear envelope reformation in human cells. We found that CHMP7 and LEM2 enrich at the same region of the chromatin disk periphery during this window of cell division and that CHMP7 can bind directly to the C-terminal domain of LEM2 in vitro. We further found that, during nuclear envelope formation, recruitment of the ESCRT factors CHMP7, CHMP2A, and IST1/CHMP8 all depend on LEM2 in human cells. We conclude that Lem2p/LEM2 is a conserved nuclear site-specific adaptor that recruits Cmp7p/CHMP7 and downstream ESCRT factors to the nuclear envelope.

scholarly journals NDC1: a nuclear periphery component required for yeast spindle pole body duplication

1993 ◽  
Vol 122 (4) ◽  
pp. 743-751 ◽  
Author(s):  
M Winey ◽  
MA Hoyt ◽  
C Chan ◽  
L Goetsch ◽  
D Botstein ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Mitotic Spindle ◽  
Nuclear Periphery ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Immunofluorescent Localization ◽  
Pole Body ◽  
Acid Protein ◽  
Monopolar Spindle ◽  
Mutant Cells

The spindle pole body (SPB) of Saccharomyces cerevisiae serves as the centrosome in this organism, undergoing duplication early in the cell cycle to generate the two poles of the mitotic spindle. The conditional lethal mutation ndc1-1 has previously been shown to cause asymmetric segregation, wherein all the chromosomes go to one pole of the mitotic spindle (Thomas, J. H., and D. Botstein. 1986. Cell. 44:65-76). Examination by electron microscopy of mutant cells subjected to the nonpermissive temperature reveals a defect in SPB duplication. Although duplication is seen to occur, the nascent SPB fails to undergo insertion into the nuclear envelope. The parental SPB remains functional, organizing a monopolar spindle to which all the chromosomes are presumably attached. Order-of-function experiments reveal that the NDC1 function is required in G1 after alpha-factor arrest but before the arrest caused by cdc34. Molecular analysis shows that the NDC1 gene is essential and that it encodes a 656 amino acid protein (74 kD) with six or seven putative transmembrane domains. This evidence for membrane association is further supported by immunofluorescent localization of the NDC1 product to the vicinity of the nuclear envelope. These findings suggest that the NDC1 protein acts within the nuclear envelope to mediate insertion of the nascent SPB.

Mitosis and cell division in some cereal rust fungi. II. The processes of mitosis and cytokinesis

1976 ◽  
Vol 54 (9) ◽  
pp. 995-1009 ◽  
Author(s):  
D. E. Harder
Keyword(s):  
Cell Division ◽  
Nuclear Envelope ◽  
Mitotic Spindle ◽  
Rust Fungi ◽  
Puccinia Graminis ◽  
Carbohydrate Storage ◽  
Spindle Poles ◽  
Nucleolar Extrusion

Before mitosis in intercellular Puccinia graminis f. sp. avenae, P. coronata f. sp. avenue, and axenic P. graminis f. sp. tritici and P. coronata, the nuclei were reduced in size by nucleolar extrusion and (or) partitioning of variable portions of the nucleus. Also there was increased vesiculation in the cytoplasm with a corresponding increase in lipid and carbohydrate storage material.The mitotic spindle first formed in one corner of the nucleus, then elongated until the spindle poles were oriented at either end of the nucleus. During the intermediate stages of mitosis the chromatin was arranged around the periphery of the spindle, which consisted mostly of chromosomal fibres. In the later stages the nucleus elongated and became dumbbell-shaped, with long straight fibres passing through the nucleus from pole to pole. The end of mitosis was marked by the chromatin assuming a ‘two-track’ configuration at the poles on either side of the intranuclear fibres and by the breakdown of the nuclear envelope in the constricted region of the dumbbell-shaped nucleus.After the daughter nuclei had separated, they migrated into new hyphal branches and septum synthesis was subsequently initiated. The septa grew by centripetal invagination in both the intercellular and the axenic hyphal states. There were often accumulations of mitochondria in the region of septal growth. Mature septa of intercellular P. coronata and axenic P. coronata and P. graminis tritici were typical of those found elsewhere in the rust fungi.

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