scholarly journals RADIOAUTOGRAPHIC LOCALIZATION OF DEOXYTHYMIDINE TRIPHOSPHATE IN TRADESCANTIA POLLEN GRAINS DURING DNA SYNTHESIS

1968 ◽  
Vol 38 (3) ◽  
pp. 509-514 ◽  
Author(s):  
S. T. Takats
Keyword(s):  
Acetic Acid ◽  
Dna Synthesis ◽  
Generative Cell ◽  
Pollen Grains ◽  
Pollen Grain ◽  
Ethanol Acetic Acid ◽  
Dry Emulsion ◽  
Generative Nuclei

Tradescantia pollen grains, isolated during the period of DNA synthesis in the generative cell, accumulate deoxythymidine triphosphate (dTTP)-3H after incubation with thymidine-3H in the presence of millimolar deoxyadenosine. Most of this dTTP-3H was found to resist extraction by the fixative, cold ethanol-acetic acid, and its location was investigated by radioautography with thin, dry emulsion. Substantial binding of dTTP-3H occurred as an artifact; but when nuclei were isolated from the fixed pollen grains by sonication, it was found that they were differentially labeled: generative nuclei contained dTTP-3H, vegetative nuclei did not. This observation is discussed and is interpreted as evidence supporting the idea that thymidine is phosphorylated only in the generative cell of the pollen grain.

scholarly journals Prunus necrotic ringspot virus Early Invasion and Its Effects on Apricot Pollen Grain Performance

2007 ◽  
Vol 97 (8) ◽  
pp. 892-899 ◽  
Author(s):  
Khalid Amari ◽  
Lorenzo Burgos ◽  
Vicente Pallas ◽  
María Amelia Sanchez-Pina
Keyword(s):  
Developmental Stages ◽  
Generative Cell ◽  
Pollen Grains ◽  
Growth Zone ◽  
Pollen Tubes ◽  
Climatic Conditions ◽  
Pollen Grain ◽  
Ringspot Virus ◽  
Prunus Necrotic Ringspot Virus

The route of infection and the pattern of distribution of Prunus necrotic ringspot virus (PNRSV) in apricot pollen were studied. PNRSV was detected both within and on the surface of infected pollen grains. The virus invaded pollen during its early developmental stages, being detected in pollen mother cells. It was distributed uniformly within the cytoplasm of uni- and bicellular pollen grains and infected the generative cell. In mature pollen grains, characterized by their triangular shape, the virus was located mainly at the apertures, suggesting that PNRSV distribution follows the same pattern as the cellular components required for pollen tube germination and cell wall tube synthesis. PNRSV also was localized inside pollen tubes, especially in the growth zone. In vitro experiments demonstrated that infection with PNRSV decreases the germination percentage of pollen grains by more than half and delays the growth of pollen tubes by ≈24 h. However, although PNRSV infection affected apricot pollen grain performance during germination, the presence of the virus did not completely prevent fertilization, because the infected apricot pollen tubes, once germinated, were able to reach the apricot embryo sacs, which, in the climatic conditions of southeastern Spain, mature later than in other climates. Thus, infected pollen still could play an important role in the vertical transmission of PNRSV in apricot.

scholarly journals Autoradiographic studies of DNA and histone synthesis in successive differentiation stages of pollen grain in Hyacinthus orientalis L.

2014 ◽  
Vol 50 (3) ◽  
pp. 367-380 ◽  
Author(s):  
Elżbieta Bednarska
Keyword(s):  
Dna Replication ◽  
Dna Synthesis ◽  
Vegetative Cell ◽  
Developmental Stages ◽  
Generative Cell ◽  
Pollen Grain ◽  
Cell Nuclei ◽  
Hyacinthus Orientalis ◽  
Histone Synthesis ◽  
Generative Cells

DNA and histone synthesis in five consecutive morphological stages of <em>Hyacinthus orientalis</em> L. pollen grain differentiation were studied autoradiographically. DNA synthesis was found to occur in both the generative and the vegetative cell. DNA replication in the generative cell took place when the generative cell was still adhered to the pollen grain wall but already devoid of callose wall. DNA synthesis in the generative cell slightly preceded that in the vegetative cell. Histones were synthesized in phase S of the generative and vegetative cell. In the generative cell histone synthesis also continued at a lower level after completion of DNA replication. In the developmental stages under study the nuclei of the generative cells were decidedly richer in lysine histones than vegetative cell nuclei.

The Formation of the Generative Cell in the Pollen Grain of Endymion Non-Scriptus (L)

1968 ◽  
Vol 3 (4) ◽  
pp. 573-578
Author(s):  
R. E. ANGOLD
Keyword(s):  
Cell Wall ◽  
Somatic Cells ◽  
Generative Cell ◽  
Cell Plate ◽  
Pollen Grain ◽  
Generative Nucleus ◽  
A Cell ◽  
Generative Nuclei

The generative cell wall in the pollen grain of Endymion non-scriptus is formed, as in somatic cells, from a cell plate between the vegetative and generative nuclei. This wall curves around the generative nucleus, and fuses with the intine to enclose the generative cell. The generative cell is subsequently freed from the intine by the constriction of the generative cell wall between the generative nucleus and the intine.

scholarly journals Morbid mitosis and the activity of inert chromosomes in sorghum

1941 ◽  
Vol 130 (859) ◽  
pp. 127-150 ◽  
Keyword(s):  
Structural Changes ◽  
Wild Population ◽  
Specific Effect ◽  
Pollen Grains ◽  
Variable Number ◽  
Pollen Grain ◽  
Vegetative Nucleus ◽  
In The Wild ◽  
Primary Division ◽  
Generative Nuclei

Sorghum purpureo-sericeum has five paris of active, A , chromosomes and a variable number of extra, B , chromosomes in equilibrium in the wild population (Janaki-Ammal 1940; and table 7). The B -chromosomes vary in structure within and between plants owing to frequent spontaneous changes, including misdivision of the centromere. One is an iso-chromosome. The B 's are sex-limited so far as that is possible in a plant: they are confined to the germ track owing to loss by lagging elsewhere. They are lost in the radicle before seed ripening and in the shoot tissues as they reach maturity. Only in the anthers and ovaries are they regularly maintained. B -chromosomes pair with one another at meiosis when homologous, and the two arms of the iso-chromosome form chiasmata with one another. Pollen grains of plus plants (with extra B 's) have extra divisions of the vegetative nucleus rapidly following the primary division. The first pollen grain division is delayed by the presence of B -chromosomes. Its course is always normal. At the second division the B 's always pass to the generative pole undivided and so double its dose. When only two generative nuclei are formed, one or both may produce sperm. Three, four or five generative nuclei, however, kill the pollen grain. The extra divisions are thus malignant. The B -chromosomes as usual are heterochromatic. They have an abnormal nucleic acid cycle. Their action on the cells, containing them is non-specific and cumulative, and their apparently specific effect in stimulating mitosis in the pollen grains is possibly due to these being the only cells that contain them whose mitosis and growth are normally limited. Spontaneous structural changes in heterochromatic chromosomes are frequent at mitosis in plants and animals. Such changes could evidently establish malignant propensities in somatic cells by stimulating recurrent mitosis.

scholarly journals 3H-thymidyne incorporation into the microspores and pollen grains nuclei in excised Tradescantia stamens

2015 ◽  
Vol 47 (1–2) ◽  
pp. 163-172 ◽  
Author(s):  
Maria Charzyńska ◽  
Joanna Maleszka
Keyword(s):  
Dna Synthesis ◽  
Generative Cell ◽  
Pollen Grains ◽  
Vegetative Nucleus ◽  
Generative Nucleus ◽  
Tetrad Stage ◽  
Pollen Grain Wall ◽  
Medium Culture

The development of microspores and pollen grains lasts in <i>Tradescantia bracteata in vivo</i> from the tetrad stage to pollen shedding about 14 days. This including 7 days of the microspore life cycle. In stamens excised and placed on a medium the microspores and pollen grains develop normally for at least 3 days. <sup>3</sup>H-thymidine is added into medium culture. DNA synthesis m the microspore nucleus is demonstrated 6 days after tetrad formation so at the end of microspore interphase. During synthesis the nucleus lies at one end of the long axis of the vacuolated microspore. Synthesis ends before migration of the nucleus to the proximal pole of the microspore where mitosis begins. Incorporation of <sup>3</sup>H-thymidine into the generative nucleus is noted in two-celled pollen grains as early as about 24h after the end of microspore division. During DNA synthesis the generative cell is rounded and is still adjacent to the pollen grain wall. DNA synthesis ends before separation of the generative cell from the sporoderm, before the generative nucleus starts to elongate. <sup>3</sup>H-thymidine is not incorporated into the vegetative nucleus in stamens developing <i>in vitro</i>.

scholarly journals Radioautographic visualization of incorporation of lipid precursors into anthers of Muscari comosum (L.) Mili.

2015 ◽  
Vol 46 (2) ◽  
pp. 295-302 ◽  
Author(s):  
Barbara Gabara
Keyword(s):  
Acetic Acid ◽  
Palmitic Acid ◽  
Developmental Stages ◽  
Mevalonic Acid ◽  
Pollen Grains ◽  
Pollen Grain ◽  
Tetrad Stage ◽  
Lipid Precursor ◽  
Mother Cells ◽  
Pollen Grain Wall

Incorporation of the following lipid precursors: DL-mevalonic acid-2 <sup>3</sup>H, <sup>3</sup>H palmitic acid and acetic acid-<sup>3</sup>H sodium salt, into the anther cells of <i>Muscari comosum</i> (L.) Mili. has been investigated. These lipid precursors have been demonstrated to incorporate into pollen mother cells, pollen grains and the tapetum at the consecutive developmental stages. Ali used isotopes are incorporated into the cytoplasm of these cells and in the case of pollen grain the radioactivity of pollen grain wall (mainly composed of sporopellenin) is noticed. The highest radioactivity of pollen grain wall is observed after acetic acid, the lower one after palmitic acid, whereas the lowest uptake of lipid precursor occurs after mevalonic acid. In comparison with tetrad stage the distinct inrease of the cytoplasmic radioactivity of tapetum, which appears to1 accompany the labelling of pollen grain wall, seems to indicate the participation of tapetum in the formation of exine. A possible role of Ubisch bodies in the formation of pollen grain wall is discussed.

scholarly journals Optical and ultrastructural study of the pollen grain development in hermaphrodite papaya tree (Carica papaya L.)

2008 ◽  
Vol 51 (3) ◽  
pp. 539-545 ◽  
Author(s):  
Lídia Márcia Silva Santos ◽  
Telma Nair Santana Pereira ◽  
Margarete Magalhães de Souza ◽  
Pedro Correa Damasceno Junior ◽  
Fabiane Rabelo da Costa ◽  
...  
Keyword(s):  
Carica Papaya ◽  
Generative Cell ◽  
Pollen Grains ◽  
Male Gamete ◽  
Mitotic Division ◽  
Pollen Grain ◽  
Grain Development ◽  
Normal Pattern ◽  
Papaya Tree ◽  
Mother Cells

The objective of this study was to describe the pollen grain development in hermaphrodite papaya tree. The flower buds were collected at different stages of the development and the anthers were treated chemically for observation under optical and electronic transmission microscopes. The pollen grain development followed the normal pattern described for the Angiosperms. The pollen grain development was described from meiocyte to the mature pollen grain. In the microsporogenesis, the microspore mother cells or the meiocytes underwent meiosis giving rise to the tetrads that were enclosed by the calose. Later, the tetrads were released by the dissolution of the calose by calase activity and microspores underwent mitosis. Microgametogenesis was characterized by asymmetrical mitotic division of each microspore giving rise to bi-nucleate pollen grains. The structures similar to the plastids were found in the cytoplasm and close to the nucleus of the generative cell. Gradual degeneration was observed in the tapetum during the male gamete development.

scholarly journals Pollen and sperm nuclei development in rye

2015 ◽  
Vol 46 (3) ◽  
pp. 449-457 ◽  
Author(s):  
Agnieszka Mostowska ◽  
Maria Charzyńska
Keyword(s):  
Secale Cereale ◽  
Light Microscope ◽  
Generative Cell ◽  
Pollen Grains ◽  
Pollen Grain ◽  
Sperm Nuclei

The development of rye (<i>Secale cereale</i> L. <i>Gramineae</i>) pollen grains. was followed in the light microscope from the differentiating division in the microspore to pollen shedding. Particular attention was given to the localization of the generative cell before and during mitosis and to the change in the structure of sperm nuclei during pollen grain maturation.

scholarly journals Ultrastructural and metabolic transformations of differentiating Hyacinthus orientalis L, pollen grain cells. I. RNA and protein synthesis

2014 ◽  
Vol 53 (2) ◽  
pp. 145-158 ◽  
Author(s):  
Elżbieta Bednarska
Keyword(s):  
Protein Synthesis ◽  
Vegetative Cell ◽  
Generative Cell ◽  
Growth Dynamics ◽  
Pollen Grains ◽  
Pollen Grain ◽  
Cell Protein ◽  
Replication Process ◽  
Rna And Protein Synthesis ◽  
Hyacinthus Orientalis

RNA and protein synthesis were investigated in generative and vegetative cells during maturation of pollen grains. The rate of RNA and protein synthesis was analysed in reference to the successive interphase periods of the life cycle of pollen cells as well as against the background of the growth dynamics of the cell volume. The results of studies demonstrated that the pollen grain increases in size owing to the growth of the vegetative cell. The generative one does not grow. RNA synthesis and that of proteins in differentiating pollen cells has a different course. In the growing vegetative cell it lasts longer and is more intensive than in the generative cell which does not grow. RNA and protein synthesis in the vegetative cell take place in the period from the callose stage to the stage of lemon-shaped generative cell, that is in the period of phases G<sub>1</sub>, S and G<sub>2</sub>. This synthesis is positively correlated with the growth of the pollen grain. RNA and protein synthesis in the generative cell comprises the period from the callose-less lenticular stage to the stage of spherical generative cell, that is the phases S and early phase G<sub>2</sub>. These results suggest that in the vegetative cell RNA and protein synthesis is utilised above all to increase of its cell, instead in non growing generative cell protein synthese is probably limited mostly to a histones and enzymatic proteins serving for the DNA replication process.

Fine Structure Study of Pollen Development in Haemanthus katherinae Baker

1971 ◽  
Vol 8 (2) ◽  
pp. 289-301
Author(s):  
JEAN M. SANGER ◽  
W. T. JACKSON
Keyword(s):  
Fine Structure ◽  
Vegetative Cell ◽  
Daughter Nucleus ◽  
Generative Cell ◽  
Pollen Grains ◽  
Cell Plate ◽  
Structure Study ◽  
Pollen Grain ◽  
Pollen Wall ◽  
Fibrillar Material

When microspores of the African blood lily divide, they form pollen grains which consist of 2 cells of unequal size. This is accomplished when the microspore nucleus is displaced from the centre of the grain prior to division. The displacement is always towards the side of the grain opposite the furrow, and large vacuoles form in the cytoplasm between the furrow and the nucleus. During cell division the cell plate curves around one daughter nucleus and fuses with the pollen wall to enclose the generative cell. The cell-plate attachment always occurs with the wall that is opposite the furrow of the grain. Most of the microspore's organelles become incorporated in the larger vegetative cell, whereas the generative cell has few, if any, plastids and only a small number of other organelles. The wall around the generative cell is composed of finely fibrillar material enclosed within 2 unit membranes. The generative cell eventually becomes detached from the pollen wall, becomes spheroidal, and moves to a position near the centre of the pollen grain. At the same time, the large vacuoles disappear from the vegetative cell and the number of organelles increases substantially.

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