The role of F-actin in determining the division plane of carrot suspension cells. Drug studies

Development ◽  
1988 ◽  
Vol 102 (1) ◽  
pp. 211-221 ◽  
Author(s):  
C.W. Lloyd ◽  
J.A. Traas
Keyword(s):  
Preprophase Band ◽  
Cell Plate ◽  
Suspension Cells ◽  
Mitotic Apparatus ◽  
Division Plane ◽  
Division Site ◽  
Cytoplasmic Actin ◽  
Spindle Poles ◽  
Extraction Buffer ◽  
Actin Cables

Following the report that a network of F-actin is associated with the nucleus throughout the division cycle, we have examined the involvement of F-actin in determining the division plane of carrot suspension cells. This was achieved by treating cells with drugs and then staining the unfixed cells with rhodaminyl lysine phallotoxin in detergent extraction buffer. In interphase, actin cables radiate from the nucleus but at the cortex become more or less transversely arranged in the pattern already known for cortical microtubules. Concentration of the cortical F-actin into a band at preprophase draws most of the nucleus- associated actin into a transvacuolar disc, thereby forming the phragmosome within which mitosis and cytokinesis occur. In addition to this transversely aligned structure, F-actin is also associated with the spindle poles during mitosis but these filaments tend to align at right angles to the phragmosomal actin. F-actin therefore defines transverse and longitudinal vectors as division approaches. Depolymerization of F-actin with cytochalasin D can cause the spindle axis to reorientate such that the pole-pole axis comes to lie, abnormally, parallel with the phragmosome. The cytokinetic apparatus (the phragmoplast) develops centrifugally within the phragmosome. There has been considerable speculation on the nature of the elements that guide the phragmoplast to the cortical site previously occupied by the preprophase band of microtubules. This study demonstrates that F-actin bridges the leading margin of the outgrowing phragmoplast to the opposing cortex. Radial actin strands therefore provide a ‘memory’ of the predetermined division plane whose perimeter had been marked at preprophase by a band composed of microtubules and F-actin. This relationship was perturbed with the herbicide, chloroisopropylphenyl carbamate. Preprophase bands of actin appear to form normally in herbicide-treated cells. However, cytokinesis does not occur within this predicted plane since the drug perturbs the mitotic spindle, forming three nuclei which become separated by Y-shaped, actin-containing phragmoplasts. Cytoplasmic actin strands connect the edges of the phragmoplast to the cortex. It is suggested that the irregular distribution of F-actin, which radiates from the herbicide-altered mitotic apparatus, provides alternative paths for outgrowth of the abnormal phragmoplasts. Caffeine is known to cause failure of cell plate formation. But apart from inducing cytoplasmic ‘starbursts’ of F-actin in interphase cells it does not appear to have any effect on F-actin-containing division structures. It is concluded that the formation of a transvacuolar phragmosome, spindle alignment and the ‘correct’ outgrowth of a planar cytokinetic apparatus to the predetermined boundary of the division site all involve F-actin.

Relationship between preprophase band organization, F-actin and the division site in Allium

1990 ◽  
Vol 97 (2) ◽  
pp. 283-295
Author(s):  
Y. MINEYUKI ◽  
B. A. PALEVITZ
Keyword(s):  
Higher Plants ◽  
Preprophase Band ◽  
Cell Plate ◽  
Mitotic Apparatus ◽  
Division Plane ◽  
Division Site ◽  
Dividing Cells ◽  
G2 Phase

The preprophase band (PPB) of microtubules (Mts), which appears in the G2 phase of the cell cycle in higher plants but disappears well before the end of karyokinesis, is implicated in the determination of the division plane because its location marks the site at which the phragmoplast/cell plate will fuse with the parental plasmalemma during cytokinesis. The PPB first appears as a rather wide array, which progressively narrows before or during prophase. Actin-containing microfilaments (Mfs) have recently been reported in the PPB, but the role of these elements in PPB organization and/or function remains unclear. The present study employed fluorescence and pharmacological methods in symmetrically and asymmetrically dividing epidermal cells of Allium to probe this problem. Our results show that PPBs in cells treated with 2–200μM cytochalasin D (CD) are still transversely aligned but remain two to three times wider than mature bands in control cells. Treatment for 0.5 h at 20 μM is sufficient to make the PPBs abnormally widel Premitotic nuclear migration in asymmetrically dividing cells is also inhibited by CD, as is the positioning of the mitotic apparatus and the new cell plate. The plate is still transverse, however. Band-like arrays of cortical Mfs become evident in most interphase cells by prophase. The band remains quite wide compared to the final dimensions of the Mt PPB, and clearly encompasses it. Levels of CD as high as 200μM decrease the number of cells with transverse actin bands, although a majority still retain them. Other F-actin arrays are disrupted by the drug. Thus, while CD does not inhibit the formation of an initial, broad, transverse PPB in most cells, it does prevent the narrowing process that defines the precise division site. The role of actin in this effect is discussed.

Division Plane Establishment and Cytokinesis

2019 ◽  
Vol 70 (1) ◽  
pp. 239-267 ◽  
Author(s):  
Pantelis Livanos ◽  
Sabine Müller
Keyword(s):  
Secretory Pathway ◽  
Preprophase Band ◽  
Cell Plate ◽  
Division Plane ◽  
Spatial Reference ◽  
Division Site ◽  
Eukaryotic Proteins ◽  
Plate Formation ◽  
Membrane Compartment ◽  
Cytoplasmic Content

Plant cells divide their cytoplasmic content by forming a new membrane compartment, the cell plate, via a rerouting of the secretory pathway toward the division plane aided by a dynamic cytoskeletal apparatus known as the phragmoplast. The phragmoplast expands centrifugally and directs the cell plate to the preselected division site at the plasma membrane to fuse with the parental wall. The division site is transiently decorated by the cytoskeletal preprophase band in preprophase and prophase, whereas a number of proteins discovered over the last decade reside continuously at the division site and provide a lasting spatial reference for phragmoplast guidance. Recent studies of membrane fusion at the cell plate have revealed the contribution of functionally conserved eukaryotic proteins to distinct stages of cell plate biogenesis and emphasize the coupling of cell plate formation with phragmoplast expansion. Together with novel findings concerning preprophase band function and the setup of the division site, cytokinesis and its spatial control remain an open-ended field with outstanding and challenging questions to resolve.

Asymmetric cell division in fucoid algae: a role for cortical adhesions in alignment of the mitotic apparatus

2001 ◽  
Vol 114 (23) ◽  
pp. 4319-4328
Author(s):  
Sherryl R. Bisgrove ◽  
Darryl L. Kropf
Keyword(s):  
Cell Division ◽  
Asymmetric Cell Division ◽  
Cell Cortex ◽  
Mitotic Apparatus ◽  
Pharmacological Agents ◽  
Division Plane ◽  
Adhesion Sites ◽  
Spindle Poles ◽  
Pelvetia Compressa ◽  
Two Phases

The first cell division in zygotes of the fucoid brown alga Pelvetia compressa is asymmetric and we are interested in the mechanism controlling the alignment of this division. Since the division plane bisects the mitotic apparatus, we investigated the timing and mechanism of spindle alignments. Centrosomes, which give rise to spindle poles, aligned with the growth axis in two phases – a premetaphase rotation of the nucleus and centrosomes followed by a postmetaphase alignment that coincided with the separation of the mitotic spindle poles during anaphase and telophase. The roles of the cytoskeleton and cell cortex in the two phases of alignment were analyzed by treatment with pharmacological agents. Treatments that disrupted cytoskeleton or perturbed cortical adhesions inhibited pre-metaphase alignment and we propose that this rotational alignment is effected by microtubules anchored at cortical adhesion sites. Postmetaphase alignment was not affected by any of the treatments tested, and may be dependent on asymmetric cell morphology.

Basket-shaped structures formed by F-actin in the nuclei of elongating cells of Nicotiana tabacum

1993 ◽  
Vol 71 (5) ◽  
pp. 725-731 ◽  
Author(s):  
Harry M. P. Kengen ◽  
Ton van Amstel ◽  
Bart Knuiman
Keyword(s):  
Nicotiana Tabacum ◽  
Laser Scanning ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Filamentous Actin ◽  
Suspension Cells ◽  
Confocal Immunofluorescence Microscopy ◽  
Cytoplasmic Actin ◽  
Extraction Buffer ◽  
Confocal Immunofluorescence

Phalloidin labelled with trimethyl rhodamine isothiocyanate in extraction buffer was used to stain actin in suspension cells of tobacco. Confocal immunofluorescence microscopy indicated the presence of filamentous actin containing structures in interphase nuclei of elongating cells of Nicotiana tabacum ‘Bright Yellow 2 Go’. The results were not affected by the omission of DMSO from the extraction medium. These structures, called actin baskets, were present in about 20% of the cells after induced elongation and varied in size, shape, and number per nucleus. The cytoplasmic actin array remained intact. It is proposed that the baskets have a transient character and are related to differentiation. Key words: confocal laser scanning microscopy, elongation, F-actin, nucleus, protoplasts, TRITC–phalloidin.

Control of division plane in normal and griseofulvin-treated microsporocytes of Magnolia

1992 ◽  
Vol 103 (4) ◽  
pp. 1031-1038 ◽  
Author(s):  
R.C. Brown ◽  
B.E. Lemmon
Keyword(s):  
Cell Plate ◽  
Equatorial Region ◽  
Cell Periphery ◽  
Drug Induced ◽  
Spatial Control ◽  
Division Plane ◽  
Spindle Poles ◽  
Wall Deposition ◽  
A Cell ◽  
Multiple Poles

Meiotic cytokinesis in microsporocytes of Magnolia is an unusual form of the simultaneous type; phragmoplast expansion is not accompanied by a cell plate, wall deposition is centripetal, and infurrowing of the cytoplasm after first meiosis results in semicells connected by an isthmus. Dyad domains are further defined by interaction of extensive radial systems of microtubules emanating from the daughter nuclei and by a band of organelles polarized in the equatorial region. After second meiosis, phragmoplasts are organized in the interzonal regions between the sister nuclei in each semicell and also at the interfaces of microtubules forming secondary interzonals between non-sister nuclei. Wall deposition is not initiated until after phragmoplasts expand to the cell periphery and fuse in the isthmus. Centripetal wall deposition in boundaries of spore domains marked by radial arrays of microtubules results in simultaneous quadripartitioning of the microsporocyte into a tetrad of microspores. Treatment of microsporocytes with griseofulvin resulted in atypically placed nuclei and supernumerary nuclei. Abnormalities could be traced to displaced spindles and to spindles with multiple poles. Drug-induced multinucleate coenocytes were able to organize microtubules and initiate cytokinesis in altered patterns. The data suggest that spindle alignment and aggregation of spindle poles are two components of spatial control that are operative in determining the normal arrangement of nuclei, and that the final placement of walls is a function of the postmeiotic nuclear-based radial arrays of microtubules which define spore domains.

A Monoclonal Antibody Raised Against Cytoplasmic Fibrillar Bundles from Carrot Cells, and its Cross-Reaction with Animal Intermediate Filaments

1989 ◽  
Vol 92 (3) ◽  
pp. 371-378 ◽  
Author(s):  
ALAN J. HARGREAVES ◽  
PETER J. DAWSON ◽  
GEOFFREY W. BUTCHER ◽  
AUDREY LARKINS ◽  
KIM C. GOODBODY ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Intermediate Filaments ◽  
Preprophase Band ◽  
Animal Cells ◽  
Suspension Cells ◽  
Band Formation ◽  
Type Iii ◽  
Carrot Cells ◽  
Spindle Poles ◽  
Cytoplasmic Microtubules

Carrot suspension cells contain cytoplasmic bundles of fibrils that are distinct from F-actin and microtubules and have some of the characteristics of intermediate filaments. In characterizing these fibrillar bundles further, we have raised a monoclonal antibody against them. This anti-fibrillar bundle antibody (AFB) immunoblots vimentin from a range of animal cells and tissues, as well as glial fibrillary acidic protein in brain and desmin in BHK fibroblasts, which are representatives of the type III intermediate filaments. Immunofluorescence staining of PtK2 cells indicates that AFB recognizes a network co-distributing with cytoplasmic microtubules. When this co-alignment is disturbed with the anti-microtubule agent, colcemid, the AFB staining segregates with the collapsed perinuclear whorls of vimentin. In carrot, AFB immunoblots the major bundle proteins but not plant tubulin. In plant as in animal cells, AFB immunofluorescently labels antigens that co-distribute with microtubules. In onion cells (which, unlike carrot, do not possess paracrystalline arrays of fibrils) AFB labels all four microtubule arrays throughout the cell cycle. The antigens do not, however, collapse around the spindle poles during mitosis. Double immunofluorescence, using anti-dog brain tubulin, indicates that the FB antigen is more diffusely distributed than tubulin; it is patchy and co-alignment is not exact, particularly during early preprophase band formation. Antigens in detergent-insoluble fibrils of carrot cells therefore exist both in animal type III intermediate filaments (IF), and in a more dispersed, microtubule-associated manner in onion meristematic cells. This constitutes an independent line of evidence for the existence of IF antigens in plants.

scholarly journals Pollen Development in Orchids. 5. A Generative Cell Domain Involved in Spatial Control of the Hemispherical Cell Plate

1991 ◽  
Vol 100 (3) ◽  
pp. 559-565
Author(s):  
R. C. BROWN ◽  
B. E. LEMMON
Keyword(s):  
Generative Cell ◽  
Preprophase Band ◽  
Cell Plate ◽  
Generative Nucleus ◽  
Pollen Mitosis ◽  
Spatial Control ◽  
Division Plane ◽  
Radial System ◽  
Vegetative Pole ◽  
First Pollen Mitosis

The unequal first pollen mitosis in moth orchids (Phalaenopsis) is followed by an unusual form of cytokinesis that isolates a small lens-shaped generative cell from a large vegetative cell. No preprophase band of microtubules predicts the division plane and the new cell plate grows completely around the generative cell rather than fusing with the parental wall. Development of the phragmoplast cytoskeleton consisting of fusiform bundles of microtubules and F-actin occurs in three major stages: (1) the initial asymmetrical phragmoplast conforming to the shape of the interzonal region, which tapers from the broad mass of chromosomes at the generative pole to the rounded mass at the vegetative pole; (2) the symmetrical plate-like phragmoplast; and (3) the hemispherical phragmoplast, which curves around the generative nucleus. Microtubules of the generative half of the hemispherical phragmoplast are nuclearbased, while those on the vegetative side terminate in endoplasmic reticulum. The path of the phragmoplast appears to outline a cytoplasmic domain denned by a radial system of microtubules emanating from the generative nucleus.

scholarly journals TANGLED1 mediates interactions between microtubules that may promote spindle organization and phragmoplast guidance to the division site in maize

2019 ◽  
Author(s):  
Pablo Martinez ◽  
Ram Dixit ◽  
Rachappa S. Balkunde ◽  
Seán E. O’Leary ◽  
Kenneth A. Brakke ◽  
...  
Keyword(s):  
Critical Role ◽  
Preprophase Band ◽  
Microtubule Organization ◽  
Division Plane ◽  
Plane Orientation ◽  
Division Site ◽  
Structural Framework ◽  
Cell Shapes ◽  
Division Plane Orientation

AbstractThe microtubule cytoskeleton serves as a dynamic structural framework for mitosis in eukaryotic cells. TANGLED1 (TAN1) is a microtubule-binding protein that localizes to the division site and mitotic microtubules and plays a critical role in division plane orientation in plants. Here, in vitro experiments demonstrate that TAN1 directly binds microtubules, mediating microtubule zippering or end-on microtubule interactions, depending on their contact angle. Maize tan1 mutant cells improperly position the preprophase band (PPB), which predicts the future division site. However, cell-shape-based modeling indicates that PPB positioning defects are likely a consequence of abnormal cell shapes and not due to TAN1 absence. Spindle defects in the tan1 mutant suggest that TAN1-mediated microtubule zippering may contribute to metaphase spindle organization. In telophase, co-localization of growing microtubules ends from the phragmoplast with TAN1 at the division site suggests that TAN1 interacts with microtubule tips end-on. Together, our results suggest that TAN1 contributes to spindle and phragmoplast microtubule organization to ensure proper division plane orientation.

scholarly journals TANGLED1 mediates microtubule interactions that may promote division plane positioning in maize

2020 ◽  
Vol 219 (8) ◽  
Author(s):  
Pablo Martinez ◽  
Ram Dixit ◽  
Rachappa S. Balkunde ◽  
Antonia Zhang ◽  
Seán E. O’Leary ◽  
...  
Keyword(s):  
Critical Role ◽  
Preprophase Band ◽  
Microtubule Organization ◽  
Division Plane ◽  
Plane Orientation ◽  
Division Site ◽  
Structural Framework ◽  
Cell Shapes ◽  
Division Plane Orientation

The microtubule cytoskeleton serves as a dynamic structural framework for mitosis in eukaryotic cells. TANGLED1 (TAN1) is a microtubule-binding protein that localizes to the division site and mitotic microtubules and plays a critical role in division plane orientation in plants. Here, in vitro experiments demonstrate that TAN1 directly binds microtubules, mediating microtubule zippering or end-on microtubule interactions, depending on their contact angle. Maize tan1 mutant cells improperly position the preprophase band (PPB), which predicts the future division site. However, cell shape–based modeling indicates that PPB positioning defects are likely a consequence of abnormal cell shapes and not due to TAN1 absence. In telophase, colocalization of growing microtubules ends from the phragmoplast with TAN1 at the division site suggests that TAN1 interacts with microtubule tips end-on. Together, our results suggest that TAN1 contributes to microtubule organization to ensure proper division plane orientation.

Microtubule and F-actin dynamics at the division site in living Tradescantia stamen hair cells

1992 ◽  
Vol 103 (4) ◽  
pp. 977-988 ◽  
Author(s):  
A.L. Cleary ◽  
B.E.S. Gunning ◽  
G.O. Wasteneys ◽  
P.K. Hepler
Keyword(s):  
Hair Cells ◽  
Preprophase Band ◽  
Cell Plate ◽  
Laser Scanning Microscopy ◽  
Actin Dynamics ◽  
Cell Cortex ◽  
Living Plant ◽  
Rhodamine Phalloidin ◽  
Division Site ◽  
The Future

We have visualised F-actin and microtubules in living Tradescantia virginiana stamen hair cells by confocal laser scanning microscopy after microinjecting rhodamine-phalloidin or carboxyfluorescein-labelled brain tubulin. We monitored these components of the cytoskeleton as the cells prepared for division at preprophase and progressed through mitosis to cytokinesis. Reorganisation of the interphase cortical cytoskeleton results in preprophase bands of both F-actin and microtubules that coexist in the cell cortex, centred on the site at which the future cell plate will fuse with the parent cell wall. The preprophase band of microtubules is formed from microtubules that polymerise and incorporate tubulin during prophase. The preprophase band of actin may form either by reorganisation of pre-existing filaments or by de novo polymerisation. Both cytoskeletal components disappear from the future division site approximately five minutes prior to the breakdown of the nuclear envelope. Cortical microtubules are undetectable throughout mitosis and cytokinesis, whereas cortical F-actin remains abundant, although it is notably excluded from the division site. The phragmoplast, containing both F-actin and microtubules, expands towards the cortical actin exclusion-zone through a region that has no detectable microtubules or F-actin. The phragmoplast comes to rest in the predefined region of the cortex that is devoid of F-actin. It is proposed that cortical F-actin may act as a “negative” template which could position the phragmoplast and cell plate correctly. This is the first in vivo documentation of F- actin dynamics at the division site in living plant cells.

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