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.

scholarly journals The myosin regulatory light chain Myl5 localizes to mitotic spindle poles and is required for proper cell division

Cytoskeleton ◽  
2021 ◽  
Author(s):  
Ivan Ramirez ◽  
Ankur A. Gholkar ◽  
Erick F. Velasquez ◽  
Xiao Guo ◽  
Bobby Tofig ◽  
...  
Keyword(s):  
Cell Division ◽  
Light Chain ◽  
Mitotic Spindle ◽  
Regulatory Light Chain ◽  
Myosin Regulatory Light Chain ◽  
Spindle Poles

scholarly journals Nnf1p, Dsn1p, Mtw1p, and Nsl1p: a New Group of Proteins Important for Chromosome Segregation in Saccharomyces cerevisiae

2002 ◽  
Vol 1 (2) ◽  
pp. 229-240 ◽  
Author(s):  
Ghia M. Euskirchen
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Nuclear Envelope ◽  
Chromosome Segregation ◽  
Indirect Immunofluorescence ◽  
Mitotic Spindle ◽  
Reverse Genetics ◽  
Essential Gene ◽  
Genetic Interactions ◽  
The Novel ◽  
Spindle Poles

ABSTRACT Previously, antibodies were raised against a nuclear envelope-enriched fraction of yeast, and the essential gene NNF1 was cloned by reverse genetics. Here it is shown that the conditional nnf1-17 mutant has decreased stability of a minichromosome in addition to mitotic spindle defects. I have identified the novel essential genes DSN1, DSN3, and NSL1 through genetic interactions with nnf1-17. Dsn3p was found to be equivalent to the kinetochore protein Mtw1p. By indirect immunofluorescence, all four proteins, Nnf1p, Mtw1p, Dsn1p, and Nsl1p, colocalize and are found in the region of the spindle poles. Based on the colocalization of these four proteins, the minichromosome instability and the spindle defects seen in nnf1 mutants, I propose that Nnf1p is part of a new group of proteins necessary for chromosome segregation.

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.

scholarly journals A novel Crumbs3 isoform regulates cell division and ciliogenesis via importin β interactions

2007 ◽  
Vol 178 (3) ◽  
pp. 387-398 ◽  
Author(s):  
Shuling Fan ◽  
Vanessa Fogg ◽  
Qian Wang ◽  
Xiao-Wei Chen ◽  
Chia-Jen Liu ◽  
...  
Keyword(s):  
Cell Division ◽  
Protein Interactions ◽  
Mitotic Spindle ◽  
Dominant Negative ◽  
Terminal Sequence ◽  
Spindle Poles ◽  
Apicobasal Polarity ◽  
Dominant Negative Form ◽  
Membrane Compartment ◽  
Negative Form

The Crumbs family of apical transmembrane proteins regulates apicobasal polarity via protein interactions with a conserved C-terminal sequence, ERLI. However, one of the mammalian Crumbs proteins, Crumbs3 (CRB3) has an alternate splice form with a novel C-terminal sequence ending in CLPI (CRB3-CLPI). We report that CRB3-CLPI localizes to the cilia membrane and a membrane compartment at the mitotic spindle poles. Knockdown of CRB3-CLPI leads to both a loss of cilia and a multinuclear phenotype associated with centrosomal and spindle abnormalities. Using protein purification, we find that CRB3-CLPI interacts with importin β-1 in a Ran-regulated fashion. Importin β-1 colocalizes with CRB3-CLPI during mitosis, and a dominant-negative form of importin β-1 closely phenocopies CRB3-CLPI knockdown. Knockdown of importin β-1 blocks targeting of CRB3-CLPI to the spindle poles. Our data suggest an expanded role for Crumbs proteins in polarized membrane targeting and cell division via unique interactions with importin proteins.

scholarly journals Menin Associates With the Mitotic Spindle and Is Important for Cell Division

Endocrinology ◽  
2019 ◽  
Vol 160 (8) ◽  
pp. 1926-1936
Author(s):  
Mark P Sawicki ◽  
Ankur A Gholkar ◽  
Jorge Z Torres
Keyword(s):  
Cell Division ◽  
Mitotic Spindle ◽  
Multiple Endocrine Neoplasia Type ◽  
Intercellular Bridge ◽  
Sporadic Tumor ◽  
Spindle Poles ◽  
Chromosome Congression ◽  
Interphase Cells ◽  
Early Mitosis

Abstract Menin is the protein mutated in patients with multiple endocrine neoplasia type 1 (MEN1) syndrome and their corresponding sporadic tumor counterparts. We have found that menin functions in promoting proper cell division. Here, we show that menin localizes to the mitotic spindle poles and the mitotic spindle during early mitosis and to the intercellular bridge microtubules during cytokinesis in HeLa cells. In our study, menin depletion led to defects in spindle assembly and chromosome congression during early mitosis, lagging chromosomes during anaphase, defective cytokinesis, multinucleated interphase cells, and cell death. In addition, pharmacological inhibition of the menin-MLL1 interaction also led to similar cell division defects. These results indicate that menin and the menin-MLL1 interaction are important for proper cell division. These results highlight a function for menin in cell division and aid our understanding of how mutation and misregulation of menin promotes tumorigenesis.

Centrosomes and mitotic spindle poles: a recent liaison?

2015 ◽  
Vol 43 (1) ◽  
pp. 13-18 ◽  
Author(s):  
Pavithra L. Chavali ◽  
Isabel Peset ◽  
Fanni Gergely
Keyword(s):  
Cell Division ◽  
Mitotic Spindle ◽  
Potential Benefit ◽  
Cell Types ◽  
Daughter Cells ◽  
Spindle Poles ◽  
Pericentriolar Material ◽  
Mitotic Spindle Assembly ◽  
Spindle Microtubules ◽  
Ordered Assembly

Centrosomes comprise two cylindrical centrioles embedded in the pericentriolar material (PCM). The PCM is an ordered assembly of large scaffolding molecules, providing an interaction platform for proteins involved in signalling, trafficking and most importantly microtubule nucleation and organization. In mitotic cells, centrosomes are located at the spindle poles, sites where spindle microtubules converge. However, certain cell types and organisms lack centrosomes, yet contain focused spindle poles, highlighting that despite their juxtaposition in cells, centrosomes and mitotic spindle poles are distinct physical entities. In the present paper, we discuss the origin of centrosomes and summarize their contribution to mitotic spindle assembly and cell division. We then describe the key molecular players that mediate centrosome attachment to mitotic spindle poles and explore why co-segregation of centrosomes and spindle poles into daughter cells is of potential benefit to organisms.

scholarly journals The myosin regulatory light chain Myl5 localizes to mitotic spindle poles and is required for proper cell division

2020 ◽  
Author(s):  
Ivan Ramirez ◽  
Ankur A. Gholkar ◽  
Erick F. Velasquez ◽  
Xiao Guo ◽  
Jorge Z. Torres
Keyword(s):  
Cell Division ◽  
Molecular Motors ◽  
Mitotic Spindle ◽  
Regulatory Light Chains ◽  
Cellular Processes ◽  
Spindle Poles ◽  
Chromosome Congression ◽  
Mitotic Spindle Assembly ◽  
Spindle Microtubules ◽  
Early Mitosis

ABSTRACTMyosins are ATP-dependent actin-based molecular motors critical for diverse cellular processes like intracellular trafficking, cell motility and cell invasion. During cell division, myosin MYO10 is important for proper mitotic spindle assembly, the anchoring of the spindle to the cortex, and positioning of the spindle to the cell mid-plane, while myosin MYO2 functions in actomyosin ring contraction to promote cytokinesis. However, myosins are regulated by myosin regulatory light chains (RLCs), and whether RLCs are important for cell division has remained unexplored. Here, we have determined that the previously uncharacterized myosin RLC Myl5 associates with the mitotic spindle and is required for cell division. Myl5 localized to the mitotic spindle poles and spindle microtubules during early mitosis, an area overlapping with MYO10 localization. Depletion of Myl5 led to defects in chromosome congression and to a slower progression through mitosis. We propose that Myl5 is a novel myosin RLC that is important for cell division.

scholarly journals Endomitosis of Human Megakaryocytes Are Due to Abortive Mitosis

Blood ◽  
1998 ◽  
Vol 91 (10) ◽  
pp. 3711-3723 ◽  
Author(s):  
Natacha Vitrat ◽  
Karine Cohen-Solal ◽  
Claudine Pique ◽  
Jean Pierre LeCouedic ◽  
Françoise Norol ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Cell Sorting ◽  
Mitotic Spindle ◽  
Kinase Activity ◽  
Cyclin B1 ◽  
Spherical Structure ◽  
Spindle Poles ◽  
Single Nucleus ◽  
Spindle Microtubules

Abstract During megakaryocyte differentiation, the promegakaryoblast (immature megakaryocyte) increases its ploidy to a 2x DNA content by a poorly understood process called endomitosis. This leads to the formation of a giant cell, the megakaryocyte (MK), which subsequently gives rise to platelets. In this report, we show that endomitotis of human MKs is due to abortive mitosis. Human MKs were obtained by a two-step purification of CD34+ blood or marrow precursors followed by in vitro culture in the presence of MK growth factors. Microcoscopic examination shows that a large number of centrosomes (up to 32) and centrioles are present in polyploid MKs. After nocodazole treatment, more than 20% of the MK are blocked in a typical pseudo-metaphase. Both spontaneous and nocodazole-induced endomitosis are associated with a breakdown of the nuclear envelope and possess a complex mitotic spindle composed of several asters. Spindle microtubules radiate from each aster, creating a spherical structure. At metaphase, expression of the kinetochore phosphoepitope recognized by the 3F3/2 antibody is lost, and the sister chromatides segregate moving toward the spindle poles. After limited segregation, the chromosomes decondense and the nuclear envelope reforms in the absence of cytokinesis, isolating all chromosomes in a single nucleus. It has been proposed that endomitosis could be due to an abnormal CDK1 activity or an absence of cyclin B1. Our results show that cyclin B1 can be detected in all MKs, including those with a ploidy of 8N or more. The cyclin B1 staining colocalizes with the mitotic spindle. Using flow cytometry, the level of cyclin B1 increased until 8N, but remained identical in 16N and 32N MKs. Cell sorting was used to separate the MKs into a 2N/4N and >4N population. Both cyclin B1 and CDK1 could be detected in the endomitotic polyploid MKs using Western blot analysis, and a histone H1 kinase activity was associated with immunoprecipitated cyclin B1. We conclude that endomitosis of human MKs is due to abortive mitosis, possibly due to alterations in the regulation of mitotic exit.

scholarly journals Endomitosis of Human Megakaryocytes Are Due to Abortive Mitosis

Blood ◽  
1998 ◽  
Vol 91 (10) ◽  
pp. 3711-3723 ◽  
Author(s):  
Natacha Vitrat ◽  
Karine Cohen-Solal ◽  
Claudine Pique ◽  
Jean Pierre LeCouedic ◽  
Françoise Norol ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Cell Sorting ◽  
Mitotic Spindle ◽  
Kinase Activity ◽  
Cyclin B1 ◽  
Spherical Structure ◽  
Spindle Poles ◽  
Single Nucleus ◽  
Spindle Microtubules

During megakaryocyte differentiation, the promegakaryoblast (immature megakaryocyte) increases its ploidy to a 2x DNA content by a poorly understood process called endomitosis. This leads to the formation of a giant cell, the megakaryocyte (MK), which subsequently gives rise to platelets. In this report, we show that endomitotis of human MKs is due to abortive mitosis. Human MKs were obtained by a two-step purification of CD34+ blood or marrow precursors followed by in vitro culture in the presence of MK growth factors. Microcoscopic examination shows that a large number of centrosomes (up to 32) and centrioles are present in polyploid MKs. After nocodazole treatment, more than 20% of the MK are blocked in a typical pseudo-metaphase. Both spontaneous and nocodazole-induced endomitosis are associated with a breakdown of the nuclear envelope and possess a complex mitotic spindle composed of several asters. Spindle microtubules radiate from each aster, creating a spherical structure. At metaphase, expression of the kinetochore phosphoepitope recognized by the 3F3/2 antibody is lost, and the sister chromatides segregate moving toward the spindle poles. After limited segregation, the chromosomes decondense and the nuclear envelope reforms in the absence of cytokinesis, isolating all chromosomes in a single nucleus. It has been proposed that endomitosis could be due to an abnormal CDK1 activity or an absence of cyclin B1. Our results show that cyclin B1 can be detected in all MKs, including those with a ploidy of 8N or more. The cyclin B1 staining colocalizes with the mitotic spindle. Using flow cytometry, the level of cyclin B1 increased until 8N, but remained identical in 16N and 32N MKs. Cell sorting was used to separate the MKs into a 2N/4N and >4N population. Both cyclin B1 and CDK1 could be detected in the endomitotic polyploid MKs using Western blot analysis, and a histone H1 kinase activity was associated with immunoprecipitated cyclin B1. We conclude that endomitosis of human MKs is due to abortive mitosis, possibly due to alterations in the regulation of mitotic exit.

Dynein LIC1 localizes to the mitotic spindle and midbody and LIC2 localizes to spindle poles during cell division

2011 ◽  
Vol 35 (2) ◽  
pp. 171-178 ◽  
Author(s):  
Conor P Horgan ◽  
Sara R Hanscom ◽  
Mary W McCaffrey
Keyword(s):  
Cell Division ◽  
Mitotic Spindle ◽  
Spindle Poles
Sign in / Sign up

Export Citation Format

Share Document