Localization of Pollen Tube NpCDPK7 Protein in Generative Cell Membrane Mediated by Amino Terminal Myristoylation

2003 ◽  
pp. 327-330
Author(s):  
Masaaki K. Watahiki ◽  
Richard M. Parton ◽  
Anthony J. Trewavas
Keyword(s):  
Cell Membrane ◽  
Pollen Tube ◽  
Generative Cell ◽  
Amino Terminal

The development of the male gametophyte and spermatogenesis in Taxus baccata L

1986 ◽  
Vol 228 (1250) ◽  
pp. 85-96 ◽  
Keyword(s):  
Pollen Tube ◽  
De Novo ◽  
Male Gametophyte ◽  
Generative Cell ◽  
Equal Size ◽  
Taxus Baccata ◽  
Transverse Wall ◽  
Proximal Pole ◽  
Spermatogenous Cell ◽  
Tube Cell

The development of the male gametophyte of Taxus baccata has been studied over a period of 20 weeks, from germination of the microspore in February to spermatogenesis in July. A few days after germination the microspore nucleus divides and a transverse wall forms at the equator cutting off the small generative cell and a large tube cell. The latter immediately begins to expand to form the pollen tube. The first division thus establishes the polarity of the gametophyte and the generative cell is regarded as proximal. The transverse wall is ephemeral, and within six weeks it has disappeared. The nucleus of the generative cell divides while still at the proximal pole. The two daughter nuclei are unequal in size, but they remain associated and together move distally. The larger nucleus eventually becomes the nucleus of the spermatogenous cell, and the smaller the sterile nucleus. The spermatogenous cell acquires a distinctive cytoplasm and becomes surrounded by a wall which arises de novo . The nucleus of the spermatogenous cell enlarges, but always remains towards one side of the cell so that at mitosis the spindle is contained within one hemisphere. After division the wall of the spermatogenous cell is ruptured and the two sperms are released as naked nuclei of equal size. The cytoplasm of the spermatogenous cell degenerates as it enters the tube, but remains recognizable until fertilization.

scholarly journals Immunochemical and immunocytochemical identification of a myosin heavy chain polypeptide in Nicotiana pollen tubes

1989 ◽  
Vol 92 (4) ◽  
pp. 569-574
Author(s):  
X.J. Tang ◽  
P.K. Hepler ◽  
S.P. Scordilis
Keyword(s):  
Pollen Tube ◽  
Nuclear Envelope ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Immunofluorescence Microscopy ◽  
Generative Cell ◽  
Pollen Tubes ◽  
Nuclear Surface ◽  
Common Pattern ◽  
Western Blots

A myosin heavy chain polypeptide has been identified and localized in Nicotiana pollen tubes using monoclonal anti-myosin antibodies. The epitopes of these antibodies were found to reside on the myosin heavy chain head and rod portion and were, therefore, designated anti-S-1 (myosin S-1) and anti-LMM (light meromyosin). On Western blots of the total soluble pollen tube proteins, both anti-S-1 and anti-LMM label a polypeptide of approximately 175,000 Mr. Immunofluorescence microscopy shows that both antibodies yield numerous fluorescent spots throughout the whole length of the tube, often with an enrichment in the tube tip. These fluorescent spots are thought to represent vesicles and/or organelles in the pollen tubes. In addition to this common pattern, anti-S-1 stains both the generative cell and the vegetative nuclear envelope. The different staining patterns of the nucleus between anti-S-1 and anti-LMM may be caused by some organization and/or anchorage state of the myosin molecules on the nuclear surface that differs from those on the vesicles and/or organelles.

scholarly journals Tradescantia bracteata pollen in vitro: pollen tubes development and mitosis

2015 ◽  
Vol 46 (4) ◽  
pp. 587-598 ◽  
Author(s):  
E. Lewandowska ◽  
M. Charzyńska
Keyword(s):  
Pollen Tube ◽  
Generative Cell ◽  
Metaphase Plate ◽  
Pollen Grains ◽  
Neutral Red ◽  
Generative Nucleus ◽  
Mitotic Spindles ◽  
Germinating Pollen ◽  
Vacuolar System

About 90 per cent of <i>Tradescantia bracteata</i> pollen germinates <i>in vitro</i> after 15 min. Mitosis starts in the pollen tube after about 3 h. The mitotic trans-formations of chromosomes within the generative nucleus are not synchronized. They involve succesively the linearly arranged chromosomes in the elongated generative nucleus. In metaphase the chromosomes are arranged tandem-like linearly along the pollen tube. The chromatides translocate in anaphase from various distances to the poles in a plane parallel to the metaphase plate. This suggests that chromosomes have individual mitotic spindles and that coordination of the chromosome transformations in the generative cell is much less strict than in a typical somatic mitosis. Starch is the storage material of pollen grains. In the vegetative cytoplasm of mature pollen grains minute reddish-orange vesicular structures are visible after staining with neutral red. They do not fuse with the vacuoles proper arising in germinating pollen grains to form the vacuolar system of the pollen tube.

Development of sperm cells in barley

1975 ◽  
Vol 53 (10) ◽  
pp. 1051-1062 ◽  
Author(s):  
David D. Cass ◽  
Ilana Karas
Keyword(s):  
Cell Membrane ◽  
Vegetative Cell ◽  
Generative Cell ◽  
Pollen Grains ◽  
Complete Separation ◽  
Pollen Wall ◽  
Vegetative Nucleus ◽  
Sperm Cells ◽  
Subsequent Stage ◽  
Microspore Stage

Ultrastructural events in barley sperm development were examined from the uninucleate microspore stage to establishment of two mature sperm cells in pollen grains. Microspore mitosis produces a vegetative nucleus and a naked generative cell, both embedded in vegetative cell cytoplasm. The generative cell membrane is enclosed by vegetative cell membrane. The generative cell, at first apparently unattached, becomes attached to the pollen wall and acquires a cell wall by centripetal vesicle accumulation. Wall formation may be complete at the time of generative cell karyokinesis; karyokinesis occurs while the generative cell is attached to the pollen wall. Cytokinesis of the generative cell is delayed. The subsequent stage is a binucleate, attached generative cell with a wall. Generative cell cytokinesis appears to involve formation of a partition between the two sperm nuclei. Eventual complete separation of the sperm cells occurs only after the two-celled derivative of the generative cell detaches from the pollen wall. Final stages in sperm cell separation are considered to result from degradation of the partitioning and surrounding wall, not from furrowing of a naked binucleate generative cell according to previous suggestions. Mature plastids were not observed in the generative cell or the sperms.

scholarly journals The mechanics of mitosis in the pollen-tube of Tulipa

1936 ◽  
Vol 121 (822) ◽  
pp. 207-220 ◽  
Keyword(s):  
Pollen Tube ◽  
Higher Plants ◽  
Generative Cell ◽  
Metaphase Plate ◽  
Cell Plate ◽  
Usual Method ◽  
Generative Nucleus ◽  
A Cell ◽  
Marked Cell

The division of the generative nucleus in the pollen-tube of the higher plants has been studied by several authors, with results differing widely from one another even when concerned with the same genus. For example, Koernicke (1906), Welsford (1914), and O’Mara (1933) have investigated various species of Lilium . Koernicke and Welsford describe the formation of a definite though narrow metaphase plate, while O’Mara, in spite of his illustration (fig. 9), is of the opinion that there is no such regular congression owing to the narrowness of the tube. Trankowsky (1930) finds a metaphase plate in Hemerocallis , the pollen-tube of which is wide in comparison with the size of the spindle, but not in Galanthus or Convallaria . Wulff’s (1933) observations are weakened by his confusing anaphase with pro-metaphase, and centric with nucleolar constrictions. A further point at issue is whether the generative cell divides by constriction or by the formation of a cell-plate, the more usual method in the higher plants. Koernicke illustrates a well marked cell-plate, but Wulff and others are of the opinion that division is by constriction.

Citrus pollen tube development in cross-compatible gynoecia, self-incompatible gynoecia, and in vitro

1988 ◽  
Vol 66 (12) ◽  
pp. 2527-2532 ◽  
Author(s):  
Tracy L. Kahn ◽  
Darleen A. DeMason
Keyword(s):  
Pollen Tube ◽  
Generative Cell ◽  
Pollen Tubes ◽  
Citrus Paradisi ◽  
Incompatible Pollination ◽  
Incompatible Cross ◽  
Compatible Pollinations ◽  
Compatible Pollen ◽  
Incompatibility Reaction

The route of 'Orlando' tangelo (Citrus paradisi Macf. × C. reticulata Blanco) pollen tubes was traced and compared in self-incompatible pollinations and cross-compatible pollinations with 'Dancy' tangerine (C. reticulata Blanco). In both crosses, 'Orlando' pollen germinated in the stigmatic exudate and grew between the papillae on the stigma surface and inter-cellularly between the parenchymatous cells until reaching a stylar canal by 3 days. However, in the incompatible pollination, irregular deposition of callose occurred in the pollen tube walls as early as 1 day after pollination. By day 6, pollen tubes were in the upper portion of the ovary in the compatible pollination, whereas most pollen tubes from the incompatible pollination were still in the upper style. 'Orlando' pollen tube growth rate decreased substantially by day 3 in both the self-incompatible pollination and in vitro but increased rapidly after day 3 in the compatible combination. The generative cell divided between 1 and 3 days after pollination in the compatible cross. Generative cell division was observed by day 3 in only a few pollen tubes in the incompatible cross and in cultured tubes. Compatible pollen tubes grew slowly for the first 3 days after pollination, during which time generative cells divided and then grew rapidly until fertilization. In contrast, incompatible pollen tubes showed morphological features indicative of an incompatibility reaction by 1 day after pollination and grew slowly for a period of 6 days, and then ceased growth.

Generative cell mitosis in pollen tubes of Nicotiana tabacum: Ultrastructure and 3-D reconstruction

1992 ◽  
Vol 50 (1) ◽  
pp. 848-849
Author(s):  
Hong-Shi Yu ◽  
S. D. Russell
Keyword(s):  
Pollen Tube ◽  
Generative Cell ◽  
Three Dimensional ◽  
Metaphase Plate ◽  
Preprophase Band ◽  
Mitotic Division ◽  
Mitotic Apparatus ◽  
Cell Mitosis

In bicellular pollen, the two sperm cells are formed by mitotic division of the generative cell (GC) in the pollen tube. This division is characterized by several unique features, including: lack of a preprophase band (PPB), absence of a metaphase plate, absence of normal spindle formation, and irregular patterns of cytokinesis. Purportedly, this is the result of spatial constraints within the pollen tube, which in vivo may be as narrow as 3 μm (as in Nicotiana) and slightly wider in vitro.Immunofluorescence studies of GC mitosis have been published in the last five years2−7, but only one incomplete ultrastructural report on GC division in vitro is available. This study is the first using three-dimensional (3-D) techniques to reconstruct the mitotic apparatus of the GC in vivo.

Cytoskeletal Elements, Cell Shaping and Movement in the Angiosperm Pollen Tube

1988 ◽  
Vol 91 (1) ◽  
pp. 49-60 ◽  
Author(s):  
J. HESLOP-HARRISON ◽  
Y. HESLOP-HARRISON ◽  
M. CRESTI ◽  
A. TIEZZI ◽  
A. MOSCATELLI
Keyword(s):  
Pollen Tube ◽  
Shape Change ◽  
Generative Cell ◽  
Vegetative Nucleus ◽  
Microtubule Cytoskeleton ◽  
Tube Shape ◽  
Galanthus Nivalis ◽  
Angiosperm Pollen ◽  
Cytoskeletal Elements ◽  
Generative Cells

The ellipsoidal generative cell of the pollen grain of Endymion nonscriptus usually elongates further following germination and entry into the tube, producing attenuated extensions the forward one of which may reach into the vicinity of the vegetative nucleus. This shape change is accompanied by the stretching of the microtubule cytoskeleton of the cell, identified in the present work by immunofluorescence using monoclonal antibodies to tubulin. Complementary observations of living generative cells of Iris pseudacorus showed that they undergo slow undulatory movements accompanied by variation in shape and length during passage through the tube. Such changes must presumably be accompanied by modifications of the microtubule cytoskeleton. Colchicine at 1 mM eliminated microtubules from tubes and most generative cells of E. nonscriptus, but did not radically affect pollen-tube shape or extension growth, nor arrest the movements of the vegetative nucleus and generative cell into and through the tube. Generative cells in colchicinetreated pollen of Galanthus nivalis rounded up and failed to undergo the usual changes in shape during passage through the tube. Secondary consequences were changes in precedence in movement through the tube, and a greater dispersal along its length. On the assumption that no other cytoskeletal elements remain to be discovered, it seems likely that microfilaments rather than microtubules provide the motive force for movement in the tube, although the latter are involved in shaping the generative cell and adapting it to its passage.

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