Synchronous organization of two preprophase microtubule bands and final cell plate arrangement in subsidiary cell mother cells of someTriticum species

PROTOPLASMA ◽  
1983 ◽  
Vol 117 (1) ◽  
pp. 24-39 ◽  
Author(s):  
B. Galatis ◽  
P. Apostolakos ◽  
C. Katsaros
Keyword(s):  
Cell Plate ◽  
Subsidiary Cell ◽  
Cell Plate Arrangement ◽  
Mother Cells

Positional inconsistency between preprophase microtubule band and final cell plate arrangement during triangular subsidiary cell and atypical hair cell formation in two Triticum species

1984 ◽  
Vol 62 (2) ◽  
pp. 343-359 ◽  
Author(s):  
B. Galatis ◽  
P. Apostolakos ◽  
C. Katsaros
Keyword(s):  
Hair Cell ◽  
Mitotic Spindle ◽  
Cell Plate ◽  
Subsidiary Cell ◽  
Transverse Wall ◽  
Cortical Zone ◽  
Preprophase Microtubule Band ◽  
Mutual Disposition ◽  
Cell Plate Arrangement ◽  
Mother Cells

On the leaf epidermis of two Triticum species examined, an intervening cell of a stomatal or a hair row often flanks on one side two guard cell mother cells (GMC's) and usually functions twice as a subsidiary cell mother cell (SMC). In many of these cells and rarely in SMC's corresponding to one GMC, a triangular subsidiary cell (SC) instead of a lens-shaped one is formed. Some of these SC's in median paradermal sections appear triangular in form, while in internal and (or) external ones they exhibit a lenslike shape. In all SMC's investigated in which a triangular SC was expected to be formed, the preprophase microtubule band (PMB) occupied the usual position adjacent to the inducing GMC, except for instances in which the transverse wall of the SMC intersected the lateral wall of the GMC or was opposite its transverse wall. Therefore, during triangular SC formation a limited portion of the junction region of the cell plate with the parent walls is predicted by the PMB. In such cases the premitotic polarizing process in the SMC's and consequently the mutual disposition between the PMB and the mitotic spindle is disturbed. The PMB's of the hair cell mother cells (HMC's) are not so densely grouped as those of the SMC's, sometimes occupying an extensive portion along the walls. They were localized at the expected positions at the polar end of the cells. Only in few instances were atypical PMB's organized. However, the cell plate separating the hair cells (HC's) sometimes diverges and fuses with the parent walls at unpredictable positions far from the PMB cortical zone, except for a small part of it adjacent to one longitudinal anticlinal wall of the HMC. In addition, the preprophase–prophase nucleus often occupied an eccentric position in relation to the PMB or more rarely was situated outside it. Sometimes it exhibited a particular orientation. Moreover, mitotic spindles inclined in relation to the PMB plane were frequently observed. The above phenomena seem to be the result of the interference of a transverse polarizing stimulus with an axial one or of the establishment of an aberrant polarity in the HMC's for unknown reasons. The observations suggest that the spatial inconsistency between PMB and final cell plate arrangement in the cells investigated is an exception to the rule, caused by the disturbance of the mutual disposition and orientation between PMB cortical zone and mitotic spindle; these phenomena follow the disorder of the polarizing process of the cells. The PMB cortical zone seems to be effective only when the cell plate edges reach a critical distance from it.

Comparative effects of phalloidin and cytochalasin B on motility and morphogenesis in Allium

1980 ◽  
Vol 58 (7) ◽  
pp. 773-785 ◽  
Author(s):  
Barry A. Palevitz
Keyword(s):  
Cytochalasin B ◽  
Cell Plate ◽  
Wall Thickening ◽  
Animal Cells ◽  
Host Fungus ◽  
Guard Mother Cells ◽  
Mother Cells ◽  
Chromosome Motion

Cytochalasin B (CB), thought to disaggregate F-actin in animal cells, and phalloidin (Phal), known to stabilize F-actin in vivo and in vitro, have nearly identical effects on cotyledon epidermal cells of Allium cepa. Both drugs rapidly induce cessation of streaming and both, by preventing normal telophase reorientation movement, lead to abnormal division planes in dividing guard mother cells. Neither, however, prevents normal microtubule deposition, wall thickening, and cellulose orientation during guard cell differentiation. Furthermore, both drugs have no effect on spindle formation and anaphase chromosome motion. Examination of Nitella and Chara cells, in which streaming had been stopped by either agent, shows that microfilament cables are still present. With both drugs, the minimum effective concentrations were routinely used (CB, 2 μM; Phal, 100–200 μM). Our results are discussed in terms of the mode of action of these drugs and their possible role in host-fungus interactions. Implications for the mechanisms underlying cell plate alignment, cellulose orientation, and cytoplasmic streaming are discussed.

Anther and Ovule Development in Tasmannia (Winteraceae)

1992 ◽  
Vol 40 (6) ◽  
pp. 877 ◽  
Author(s):  
N Prakash ◽  
AL Lim ◽  
FB Sampson
Keyword(s):  
Mother Cell ◽  
Female Gametophyte ◽  
Cell Plate ◽  
Basic Type ◽  
Ovule Development ◽  
Linear Tetrad ◽  
Polygonum Type ◽  
Secretory Type ◽  
Mother Cells ◽  
Female Gametophyte Development

Three species of Tasmannia R.Br. ex DC., T. glaucifolia, T. insipida and T. stipitata are studied. The anther is tetrasporangiate and its waU development conforms to the Basic type. The tapetum follows the secretory type of development. Cytokinesis in the microspore mother cells is simultaneous but an evanescent cell plate is present at telophase I and anaphase I1 during meiosis. Pollen tetrads are permanent and tetrahedral. The mature pollen is anaulcerate, reticulate and 2-celled. The ovule. is anatropous, bitegmic and crassinucellate. The micropyle in T. stipitata and T. Glaucifolia is formed by the inner integument only whereas in T. insipida it is formed by both the integuments and is zigzag in outline. Meiosis in the single megaspore mother cell produces a linear or T-shaped megaspore tetrad in T. stipitata and T. glaucifolia but only a linear tetrad in T. insipida. Female gametophyte development is of the monosporic Polygonum type. Fertilisation is porogamous; triple fusion and syngamy occur simultaneously.

Studies on the formation of ‘floating’ guard cell mother cells in Anemia

1986 ◽  
Vol 80 (1) ◽  
pp. 29-55
Author(s):  
B. Galatis ◽  
P. Apostolakos ◽  
D. Palafoutas
Keyword(s):  
Guard Cell ◽  
Intercellular Space ◽  
Cortical Microtubule ◽  
Cell Plate ◽  
Cell Polarization ◽  
Periclinal Wall ◽  
Wall Area ◽  
Cortical Zone ◽  
Neighbouring Region ◽  
Mother Cells

The protodermal cells producing the ‘floating’ guard cell mother cells (GMCs) in three Anemia species undergo an extraordinary polarization and an unexpected shaping. During interphase an intercellular space is initiated at the internal proximal end of the cell, while the polar region bulges outwards. At this stage a microtubule girdle traverses the cortical cytoplasm underneath the rims of the external periclinal wall curvature. In addition, another system of microtubules converges on a cortical site adjoining the wall delimiting the intercellular space and, or, the neighbouring region of the internal periclinal wall (internal polar cortical site, IPCS). Vacuoles are found in all regions of the cell except for that between the centrally located nucleus and the intercellular space. As the cell approaches mitosis, the growing vacuolar system retreats from the cytoplasmic region below the external periclinal wall curvature. In most cells the polarized cytoplasm forms an inclined truncated cone, the bases of which abut on the external periclinal wall curvature and the wall lining the IPCS. The organization of the cortical microtubule cytoskeleton does not change significantly during preprophase-prophase. A preprophase microtubule band (PMB) is localized in the cortex lining the rims of the external periclinal wall curvature, while some microtubules traverse the IPCS and the cytoplasm adjacent to the neighbouring wall regions. The mitotic spindle axis is diagonal, while the cell plate separating the GMCs exhibits an unusual mode of growth. It gradually encircles the proximal daughter nucleus, becoming funnel-shaped. One of its periclinal edges fuses with the external periclinal wall area lined by the PMB cortical zone and the other with the internal periclinal wall area adjoining the IPCS. The latter region seems to behave like the PMB cortical zone. The results show that the morphogenetic mechanism underlying the formation of the conical GMCs includes a series of highly integrated processes, initiated or carried out during cell polarization.

On the differential divisions and preprophase microtubule bands involved in the development of stomata of Vigna sinensis L

1979 ◽  
Vol 37 (1) ◽  
pp. 11-37
Author(s):  
B. Galatis ◽  
K. Mitrakos
Keyword(s):  
Cell Polarity ◽  
Cell Plate ◽  
Equatorial Position ◽  
Anticlinal Wall ◽  
Vigna Sinensis ◽  
Daughter Cells ◽  
Preprophase Microtubule Band ◽  
Dicotyledonous Plants ◽  
Mother Cells ◽  
Dictyosome Vesicles

The manifestation of premitotic cell polarity and the resultant structural asymmetry of the differential divisions participating in the development of stomata of Vigna sinensis vary considerably. However, two morphologically distinct types of differential division were distinguished: (a) ‘asymmetrical differential divisions’, in which the premitotic polarization of the cell, the eccentric position of the nucleus during division and the differences in size and organization of the daughter cells are obvious; and (b) differential divisions in which the above features are inconspicuous or almost absent. The former occur in the ordinary protodermal cells, the latter in some meristemoids. The organization of a sharply demarcated preprophase microtubule band (PMB) precedes, all differential and non-differential divisions. In the first type of differential division the PMB is formed eccentrically, while in the second it may display either an approximately symmetrical or a clearly asymmetrical disposition, always indicating with surprising accuracy the sites where the succeeding cell plate will join the parent walls. The PMB foreshadowing the highly curved cell plates in meristemoids I of the mesoperigenous process, as well as in meristemoids I and II of the mesogenous one, are apposed only on one anticlinal wall and therefore do not encircle the nucleus or traverse the cell. In the symmetrical divisions of guard cell mother cells (GMC), as well as in those of protodermal cells, the PMB runs right round the internal plasmalemma surface in an equatorial position, coinciding with that of the future cell plate. In the former cells the wall abutting the cortical cytoplasm traversed by the band becomes locally thickened. The variability in the pattern of the microtubules of the band along the walls of the GMC is directly mirrored in the pattern of the thickening. It seems that in GMC the PMB mediates a directed exocytosis of dictyosome vesicles. In contrast to what is now generally accepted in dicotyledonous plants, each meristemoid I of both the mesogenous and mesoperigenous stomata in Vigna sinensis leaves does not inhibit but induces the formation of other meristemoids close to it.

Distribution of Membranes and the Cytoskeleton During Cell Plate Formation in Pollen Mother Cells of Tradescantia

1991 ◽  
Vol 100 (4) ◽  
pp. 717-728 ◽  
Author(s):  
CHRISTEL R. SCHOPFER ◽  
PETER K. HEPLER
Keyword(s):  
Laser Scanning ◽  
Polarized Light ◽  
Cell Plate ◽  
Confocal Laser Scanning Microscope ◽  
Temporal Organization ◽  
Ion Concentration ◽  
Confocal Laser ◽  
Surface Binding ◽  
Pollen Mother Cells ◽  
Mother Cells

The cellular pattern and distribution of membranes have been analyzed during cytokinesis in pollen mother cells of Tradescantia and compared with those of actin microfilaments (MFs) and microtubules (MTs). Membranes have been stained with DiOC6(3) and MFs with rhodamine-labeled phalloidin (RP); analysis has been carried out on the confocal laser scanning microscope. MTs have been visualized as birefringent elements in the polarized light microscope. The results show that when the interzone first appears in mid anaphase it contains an even distribution of membranes. However, by late anaphase these elements have been cleared away, leaving the interzone largely devoid of DiOC6(3)-positive material. MTs are found throughout this zone, while MFs appear in two non-overlapping sets on both sides of the cell equator. Thereafter membrane elements reappear in the interzone, but only along the equatorial line of the forming cell plate. Presumably these equatorial elements are composed of endoplasmic reticulum and Golgi vesicles, since the larger organelles, including amyloplasts and mitochondria, are excluded from the phragmoplast. MFs, like MTs, arrange preferentially normal to the cell plate, forming a dense array on both sides, but being absent from the zone occupied by the membranes. By contrast, the parallel set of MTs, while excluding larger organelles from the phragmoplast, intermingle with the membrane elements in the cell equator. As cytokinesis proceeds membranes continue to concentrate on the cell plate as indicated by its marked increase in staining with DiOC6(3). From a consideration of spatial and temporal organization of the phragmoplast components it is reasonable to suggest that both cytoskeletal components participate in the aggregation of vesicles that give rise to the cell plate. Membranes, on the other hand, through the provision of surface binding sites and/or through the regulation of the cytoplasmic calcium ion concentration, might be involved in the assembly and stabilization of the cytoskeleton.

A CONTRIBUTION TO THE EMBRYOLOGY OF CYPERUS ROTUNDUS L., SCIRPUS MUCRINATUS L., AND KYLLINGA MELANOSPORA NEES.

1965 ◽  
Vol 43 (12) ◽  
pp. 1539-1547 ◽  
Author(s):  
Pushpa Khanna
Keyword(s):  
Embryo Sac ◽  
Middle Layer ◽  
Cell Plate ◽  
Cyperus Rotundus ◽  
Cleavage Furrow ◽  
Double Fertilization ◽  
Polygonum Type ◽  
Cell Embryo ◽  
A Cell ◽  
Mother Cells

The anther is tetralocular and its wall consists of four layers: epidermis, endothecium, a middle layer, and the uninucleate tapetum. The endothecial cells develop characteristic fibrous thickenings. Microspore mother cells divide meiotically to form four nuclei. One of them grows in size and becomes the functional nucleus of the pollen grain while the three non-functional ones are pushed to the periphery. A cleavage furrow accompanied by a cell plate separates them from the functional nucleus. Similar walls, though less prominent, separate the non-functional nuclei from each other. The walls are comparatively distinct in Cyperus rotundus and Kyllinga melanospora.The ovule is anatropous, bitegmic, and crassinucellate. The inner integument forms the micropyle. An outgrowth from the funiculus gives rise to an obturator. The hypodermal archesporial cell divides to form a two-layered parietal tissue and a sporogenous cell. Embryo sac is of the Polygonum type. Double fertilization takes place.The embryogeny conforms to the Juncus variation of the onagrad type in Cyperus rotundus and Kyllinga melanospora and to the asterad type in Scirpus mucrinatus.The integuments each are two-layered. The inner becomes three- to four-layered at the micropylar end. Both of them ultimately fuse to form a thin testa. The thick pericarp also functions as testa.

The involvement of phospholipases C and D in the asymmetric division of subsidiary cell mother cells ofZea mays

2008 ◽  
Vol 65 (11) ◽  
pp. 863-875 ◽  
Author(s):  
Panagiotis Apostolakos ◽  
Emmanuel Panteris ◽  
Basil Galatis
Keyword(s):  
Asymmetric Division ◽  
Subsidiary Cell ◽  
Mother Cells

The Ultrastructure and Ontogeny of Pollen in Helleborus Foetidus L

1968 ◽  
Vol 3 (2) ◽  
pp. 175-186
Author(s):  
P. ECHLIN ◽  
H. GODWIN
Keyword(s):  
Cell Membrane ◽  
Outer Part ◽  
Cell Plate ◽  
Thick Wall ◽  
Fibrous Layer ◽  
Helleborus Foetidus ◽  
Plate Area ◽  
The Individual ◽  
Mother Cells ◽  
Exine Patterning

During the early stages of microsporocyte ontogeny in Helleborus foetidus L. there is protoplasmic continuity between the cells of the tapetum and between the individual sporogenous cells, but not between the two tissues. The plasma canals and plasmodesmata are progressively sealed off by the deposition of thick callose walls, so that by the first meiotic division, each pollen mother cell is isolated from its neighbours and from the surrounding tapetum. Callose is formed by dictyosomes in the individual pollen mother cells. The four meiocytes are separated by the deposition and coalescence of masses of callose forming in the cell plate area. The exine pattern is initiated at the surface of the young microspores while they are still invested with a thick wall of callose. Periclinally arranged endoplasmic reticulum lying just below the microspore cell membrane corresponds with the position of the furrows. The cell membrane in the interfurrow region thickens and becomes highly convoluted. A fibrous layer appears between the outer part of the convolutions and the callose, and locally it becomes less electron-dense at places that become filled with material of moderate electron density corresponding to the probacula; these in turn will become the bacula of the mature exine. In spite of an extensive examination of material prepared by a variety of techniques, no organelle or cytoplasmic component may be consistently associated with the positioning of the first signs of exine patterning.

Sign in / Sign up

Export Citation Format

Share Document