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.

scholarly journals Callose deposition is essential for the completion of cytokinesis in the unicellular alga Penium margaritaceum

2020 ◽  
Vol 133 (19) ◽  
pp. jcs249599 ◽  
Author(s):  
Destiny J. Davis ◽  
Minmin Wang ◽  
Iben Sørensen ◽  
Jocelyn K. C. Rose ◽  
David S. Domozych ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Plate ◽  
Molecular Evidence ◽  
Callose Deposition ◽  
Division Plane ◽  
Unicellular Algae ◽  
A Cell ◽  
Division Cell ◽  
Wall Assembly ◽  
Cell Wall Deposition

ABSTRACTCytokinesis in land plants involves the formation of a cell plate that develops into the new cell wall. Callose, a β-1,3 glucan, accumulates at later stages of cell plate development, presumably to stabilize this delicate membrane network during expansion. Cytokinetic callose is considered specific to multicellular plant species, because it has not been detected in unicellular algae. Here we present callose at the cytokinesis junction of the unicellular charophyte, Penium margaritaceum. Callose deposition at the division plane of P. margaritaceum showed distinct, spatiotemporal patterns likely representing distinct roles of this polymer in cytokinesis. Pharmacological inhibition of callose deposition by endosidin 7 resulted in cytokinesis defects, consistent with the essential role for this polymer in P. margaritaceum cell division. Cell wall deposition at the isthmus zone was also affected by the absence of callose, demonstrating the dynamic nature of new wall assembly in P. margaritaceum. The identification of candidate callose synthase genes provides molecular evidence for callose biosynthesis in P. margaritaceum. The evolutionary implications of cytokinetic callose in this unicellular zygnematopycean alga is discussed in the context of the conquest of land by plants.This article has an associated First Person interview with the first author of the paper.

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 Callose deposition is essential for the completion of cytokinesis in the unicellular alga, Penium margaritaceum

2020 ◽  
Author(s):  
Destiny J. Davis ◽  
Minmin Wang ◽  
Iben Sørensen ◽  
Jocelyn K.C. Rose ◽  
David S. Domozych ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Plate ◽  
Molecular Evidence ◽  
Callose Deposition ◽  
Division Plane ◽  
Cell Wall Assembly ◽  
Unicellular Algae ◽  
A Cell ◽  
Division Cell ◽  
Wall Assembly

AbstractCytokinesis in land plants involves the formation of a cell plate that develops into the new cell wall. Callose is a β-1,3 glucan that transiently accumulates at later stages of cell plate development and is thought to stabilize the delicate membrane network of the cell plate as it expands. Cytokinetic callose deposition is currently considered specific to multicellular plant species as it has not been detected in unicellular algae. Here we present callose at the cytokinesis junction of the unicellular charophyte, Penium margaritaceum. Notably, callose deposition at the division plane of P. margaritaceum showed distinct, spatiotemporal patterns that could represent distinct roles of this polymer in cytokinesis and cell wall assembly. Pharmacological inhibition of cytokinetic callose deposition by Endosidin 7 treatment resulted in cytokinesis defects, consistent with the essential role for this polymer in P. margaritaceum cell division. Cell wall deposition and assembly at the isthmus zone was also affected by the absence of callose, demonstrating the dynamic nature of new wall assembly in P. margaritaceum. The identification of candidate callose synthase genes provides molecular evidence for callose biosynthesis in P. margaritaceum. The evolutionary implications of cytokinetic callose in this unicellular Zygnematopycean alga is discussed in the context of the conquest of land by plants.Summary StatementEvolutionarily conserved callose in Penium margaritaceum is essential for the completion of cytokinesis.

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.

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.

Differential pathways of recruitment for centrosomal antigens to the mitotic poles during bipolar spindle formation

1991 ◽  
Vol 100 (3) ◽  
pp. 533-540 ◽  
Author(s):  
T. Maekawa ◽  
R. Kuriyama
Keyword(s):  
Drug Treatment ◽  
Single Cell ◽  
Subcellular Distribution ◽  
Immunofluorescence Staining ◽  
Cell Periphery ◽  
Spindle Formation ◽  
Spindle Poles ◽  
Specific Manner ◽  
Bipolar Spindles ◽  
Antibody Localization

As cells enter mitosis, centrosomes undergo many transformations and become associated with different molecules in a stage-specific manner. We have developed a protocol for immunofluorescence staining with four antibody probes that can help us to follow the interaction of centrosomal components during mitosis. The cells were first stained with a human autoimmune serum (5051); a monoclonal anti-phosphocentrosomal antibody (CHO3); and an antitubulin antibody. Localization of the antibodies was detected using rhodamine-, fluorescein- and AMCA-conjugated second antibodies, respectively. After photographing marked mitotic cells, coverslips were soaked with 0.2 M glycine-HCl at pH 1.0 for 1 h to release all antibodies bound to the structures. The same cells were re-stained with a human autoantibody (SP-H) specific for spindle poles and a fluorescein-conjugated second antibody. This allowed us to compare the subcellular distribution of three kinds of centrosomal antigens in a single cell. Mitotic PtK1 cells treated with either nocodazole or taxol included microtubule-containing cytoplasmic foci and parallel bundles of short microtubules at the cell periphery. All the centrosomal antibodies stained the same one or two dots corresponding to structures labeled by the tubulin antibody. CHO3 also revealed extra cytoplasmic foci, whereas the SP-H antigen was additionally localized at one end of the free microtubule bundles. As the microtubules reorganized into bipolar spindles during the recovery from drug treatment, the CHO3 and SP-H antigens coalesced into the spindle poles where the 5051 antigen was located, suggesting that centrosomal antigens become associated with spindle poles through very different recruitment pathways.

scholarly journals AP-4 vesicles contribute to spatial control of autophagy via RUSC-dependent peripheral delivery of ATG9A

2017 ◽  
Author(s):  
Alexandra K. Davies ◽  
Daniel N. Itzhak ◽  
James R. Edgar ◽  
Tara L. Archuleta ◽  
Jennifer Hirst ◽  
...  
Keyword(s):  
Membrane Trafficking ◽  
Close Association ◽  
Adaptor Protein ◽  
Cell Types ◽  
Subcellular Localisation ◽  
Cell Periphery ◽  
Accessory Proteins ◽  
Unknown Aetiology ◽  
Spatial Control ◽  
Cargo Proteins

AbstractAdaptor protein 4 (AP-4) is an ancient membrane trafficking complex, whose function has largely remained elusive. In humans, AP-4 deficiency causes a severe neurological disorder of unknown aetiology. We apply unbiased proteomic methods, including ‘Dynamic Organellar Maps’, to find proteins whose subcellular localisation depends on AP-4. We identify three transmembrane cargo proteins, ATG9A, SERINC1 and SERINC3, and two AP-4 accessory proteins, RUSC1 and RUSC2. We demonstrate that AP-4 deficiency causes missorting of ATG9A in diverse cell types, including patient-derived cells, as well as dysregulation of autophagy. RUSC2 facilitates the transport of AP-4-derived, ATG9A-positive vesicles from the TGN to the cell periphery. These vesicles cluster in close association with autophagosomes, suggesting they are the “ATG9A reservoir” required for autophagosome biogenesis. Our study uncovers ATG9A trafficking as a ubiquitous function of the AP-4 pathway. Furthermore, it provides a potential molecular pathomechanism of AP-4 deficiency, through dysregulated spatial control of autophagy.

F-actin as a functional target for retro-retinoids: a potential role in anhydroretinol-triggered cell death

1999 ◽  
Vol 112 (15) ◽  
pp. 2521-2528 ◽  
Author(s):  
I. Korichneva ◽  
U. Hammerling
Keyword(s):  
Cell Death ◽  
Early Event ◽  
Pattern Reversal ◽  
Cell Periphery ◽  
Growth And Survival ◽  
Signalling Molecules ◽  
Herbimycin A ◽  
Morphological Studies ◽  
A Cell ◽  
Survival Potential

The retro-retinoids, metabolites of vitamin A (retinol), belong to a family of lipophilic signalling molecules implicated in regulation of cell growth and survival. Growth-promoting properties have been ascribed to 14-hydroxy-retro-retinol (14HRR), while anhydroretinol (AR) was discovered to act as a natural antagonist triggering growth arrest and death by apoptosis. Based on morphological studies and inhibition of apoptosis by the kinase blocker, herbimycin A, it has been suggested that retro-retinoids exhibit their function in the cytosolic compartment. F-actin emerged as a functional target for retro-retinoid action. By FACS analysis and fluorescence microscopy of phalloidin-FITC labeled cells we demonstrated that F-actin reorganization was an early event in AR-triggered apoptosis. Fluorescence images of AR-treated fibroblasts displayed short, thick, stick-like and punctate structures, and membrane ruffles at the cell periphery along with an increased diffuse staining pattern. Reversal of the AR effect by 14HRR or retinol indicates that F-actin is a common site for regulation by retro-retinoids. Inhibition of both cell death and actin depolymerisation by bcl-2 implies that cytoskeleton reorganization is downstream of bcl-2-related processes. Furthermore, stabilization of microfilaments by jasplakinolide increased the survival potential of AR treated cells, while weakening the cytoskeleton by cytochalasin B abetted apoptosis. Thus the cytoskeleton is an important way station in a communication network that decides whether a cell should live or die.

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.

scholarly journals Cytokinesis in tobacco BY-2 and root tip cells: a new model of cell plate formation in higher plants.

1995 ◽  
Vol 130 (6) ◽  
pp. 1345-1357 ◽  
Author(s):  
A L Samuels ◽  
T H Giddings ◽  
L A Staehelin
Keyword(s):  
Higher Plants ◽  
Membrane Surface ◽  
Cell Plate ◽  
Root Tip ◽  
Cellulose Synthesis ◽  
Parent Cell ◽  
Cell Periphery ◽  
New Model ◽  
Cell Plate Formation ◽  
Plate Formation

Cell plate formation in tobacco root tips and synchronized dividing suspension cultured tobacco BY-2 cells was examined using cryofixation and immunocytochemical methods. Due to the much improved preservation of the cells, many new structural intermediates have been resolved, which has led to a new model of cell plate formation in higher plants. Our electron micrographs demonstrate that cell plate formation consists of the following stages: (1) the arrival of Golgi-derived vesicles in the equatorial plane, (2) the formation of thin (20 +/- 6 nm) tubes that grow out of individual vesicles and fuse with others giving rise to a continuous, interwoven, tubulo-vesicular network, (3) the consolidation of the tubulo-vesicular network into an interwoven smooth tubular network rich in callose and then into a fenestrated plate-like structure, (4) the formation of hundreds of finger-like projections at the margins of the cell plate that fuse with the parent cell membrane, and (5) cell plate maturation that includes closing of the plate fenestrae and cellulose synthesis. Although this is a temporal chain of events, a developing cell plate may be simultaneously involved in all of these stages because cell plate formation starts in the cell center and then progresses centrifugally towards the cell periphery. The "leading edge" of the expanding cell plate is associated with the phragmoplast microtubule domain that becomes concentrically displaced during this process. Thus, cell plate formation can be summarized into two phases: first the formation of a membrane network in association with the phragmoplast microtubule domain; second, cell wall assembly within this network after displacement of the microtubules. The phragmoplast microtubules end in a filamentous matrix that encompasses the delicate tubulo-vesicular networks but not the tubular networks and fenestrated plates. Clathrin-coated buds/vesicles and multivesicular bodies are also typical features of the network stages of cell plate formation, suggesting that excess membrane material may be recycled in a selective manner. Immunolabeling data indicate that callose is the predominant lumenal component of forming cell plates and that it forms a coat-like structure on the membrane surface. We postulate that callose both helps to mechanically stabilize the early delicate membrane networks of forming cell plates, and to create a spreading force that widens the tubules and converts them into plate-like structures. Cellulose is first detected in the late smooth tubular network stage and its appearance seems to coincide with the flattening and stiffening of the cell plate.

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