scholarly journals Intracellular Amounts of Nucleic Acids and Protein During Pollen Grain Growth in Tradescantia

1958 ◽  
Vol 4 (4) ◽  
pp. 383-390 ◽  
Author(s):  
John W. Woodard
Keyword(s):  
Pollen Grains ◽  
Sole Source ◽  
Pollen Grain ◽  
Vegetative Nucleus ◽  
Rapid Decline ◽  
Chromosomal Protein ◽  
Cytochemical Analysis ◽  
Cytoplasmic Rna ◽  
Synchronous Development

The rapid growth, large organelles, and synchronous development of T. paludosa pollen grains make them ideal subjects for cytochemical analysis. A microphotometric study of the nucleoli, chromosomes, and cytoplasm fixed at daily intervals during pollen grain maturation indicated that: 1. DNA (Feulgen) synthesis in the generative nucleus occurred during the first third of interphase, while the DNA content of the vegetative nucleus remained unchanged. 2. Throughout development, changes in RNA (azure B) content, in general, paralleled changes in protein (NYS1, Millon) content in each organelle of the vegetative cell. Initially, the RNA and protein of all organelles increased up to mid interphase, when chromosomal and nucleolar fractions began to decline despite a continued increase in cytoplasmic RNA and protein. At least 24 hours before anthesis, the vegetative nucleolus had disappeared and chromosomal protein and RNA of the vegetative nucleus were apparently in rapid decline. Such a system offered an opportunity to study the role of the nucleus, especially the nucleolus, in RNA and protein metabolism in the cytoplasm, by noting what cytoplasmic processes could and could not continue at a time when nuclear mechanisms were absent or minimal. It was found that at least 2 fundamental processes continued during this period: both RNA and protein accumulated in the cytoplasm at a rapid rate. It was concluded that the nucleus is not the sole source of cytoplasmic RNA, for the data suggest that there are at least 2 separate and independent, or remotely dependent synthesizing systems, one nuclear and the other cytoplasmic. It is evident that nuclear influence on cytoplasmic synthesis need be neither direct nor immediate.

scholarly journals Ultrastructure of pollen grain sculpturing in several species of the Rosaceae family

2014 ◽  
Vol 51 (3-4) ◽  
pp. 341-344 ◽  
Author(s):  
Józef Kocoń ◽  
Stanisław Muszyński
Keyword(s):  
Pollen Grains ◽  
Sem Analysis ◽  
Pollen Grain ◽  
Chemical Plant ◽  
Plant Taxonomy ◽  
Finger Print ◽  
Prunus Spinosa ◽  
Rosaceae Family

The sculpturing patterns of pollen grains in some species of the <em>Rosaceae</em> family were analyzed by SEM. Three patterns are described, typical for <em>Prunus spinosa, Pyrus elengrifolia</em> and <em>Crataegus</em> sp. The role of SEM analysis of sculpturing patterns in taxonomy can be compared to the "finger print" method in chemical plant taxonomy.

Pollen-stigma interaction in Brassica oleracea: the role of stigmatic proteins in pollen grain adhesion

1980 ◽  
Vol 42 (1) ◽  
pp. 417-423
Author(s):  
A.D. Stead ◽  
I.N. Roberts ◽  
H.G. Dickinson
Keyword(s):  
Brassica Oleracea ◽  
Turnover Rate ◽  
Marked Decrease ◽  
Pollen Grains ◽  
Staining Intensity ◽  
Pollen Grain ◽  
Higher Plant ◽  
Adhesive Properties ◽  
Protease Treatment

The adhesion of pollen grains to the stigmas of Brassica oleracea was assayed after treatment of the stigmas wiuth protease and/or cycloheximide. Treatment with protease alone adversely affected pollen grain adhesion. However, the adhesive properties of the stigma recovered fully if the stigmas were not pollinated until 2 h after treatment. Immersion of the stigmas in cycloheximide after protease treatment prevented any recoveryt of the stigmas' adhesive properties. Cycloheximide treatment alone prevented pollen grain adhesion when pollination occurred later than 1–2 h after treatment but did not affect pollen grain adhesion if pollination occurred immediately after treatment. These results indicated not only that the surface-held proteins of the stigma are involved in pollen grain adhesion, but also that their turnover rate is rapid. Isoelectric focusing of extracts derived from stigmas after protease and cycloheximide treatment showed a marked decrease in staining intensity of 3 protein bands, one of which, a glycoprotein, is known to be present only when the self-incompativility system is fully functional. These observations suggest a specificity of adhesion between higher plant cells in the presence of the cell wall.

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.

The nuclear envelope protein KAKU4 determines the migration order of the vegetative nucleus and sperm cells in pollen tubes

2020 ◽  
Vol 71 (20) ◽  
pp. 6273-6281 ◽  
Author(s):  
Chieko Goto ◽  
Kentaro Tamura ◽  
Satsuki Nishimaki ◽  
Daisuke Maruyama ◽  
Ikuko Hara-Nishimura
Keyword(s):  
Sperm Cell ◽  
Pollen Grains ◽  
Nuclear Lamina ◽  
Pollen Tubes ◽  
Pollen Grain ◽  
Vegetative Nucleus ◽  
Sperm Cells ◽  
Wild Type ◽  
Cell Nuclei ◽  
In The Wild

Abstract A putative component protein of the nuclear lamina, KAKU4, modulates nuclear morphology in Arabidopsis thaliana seedlings, but its physiological significance is unknown. KAKU4 was highly expressed in mature pollen grains, each of which has a vegetative cell and two sperm cells. KAKU4 protein was highly abundant on the envelopes of vegetative nuclei and less abundant on the envelopes of sperm cell nuclei in pollen grains and elongating pollen tubes. Vegetative nuclei are irregularly shaped in wild-type pollen. However, KAKU4 deficiency caused them to become more spherical. After a pollen grain germinates, the vegetative nuclei and sperm cells enter and move along the pollen tube. In the wild type, the vegetative nucleus preceded the sperm cell nuclei in &gt;90% of the pollen tubes, whereas, in kaku4 mutants, the vegetative nucleus preceded the sperm cell nuclei in only about half of the pollen tubes. kaku4 pollen was less competitive for fertilization than wild-type pollen after pollination. These results led us to hypothesize that the nuclear shape in vegetative cells of pollen grains affects the orderly migration of the vegetative nucleus and sperm cells in pollen tubes.

scholarly journals Characterization of the role of several COPI complex isoforms during the early acceptance of compatible pollen grains in Arabidopsis thaliana

2018 ◽  
Author(s):  
Daniel A. Cabada Gomez ◽  
M. Isabella Chavez ◽  
Emily Indriolo
Keyword(s):  
Pollen Tube ◽  
Seed Set ◽  
Contact Point ◽  
Pollen Grains ◽  
Retrograde Transport ◽  
Pollen Grain ◽  
Knock Out ◽  
Pollen Tube Penetration ◽  
Compatible Pollen

AbstractCOPI is a seven subunit coatomer complex, consisting of α, β, β′, γ, δ, ε, and ξ; in A. thaliana, COPI is necessary for retrograde transport from the Golgi to the Endoplasmic Reticulum, Golgi maintenance, and cell-plate formation in plant cells. Vesicle recruitment to the pollen contact point is required for pollen hydration and pollen tube penetration. To determine what other aspects of trafficking may be involved in the stigmatic papillae acceptance of compatible pollen, knock-out lines of several isoforms of the COPI complex were characterized in their roles during compatible pollination. Isoforms that were studied included α1-COPI, β-COPI, β′-COPI, γ-COPI and ε-COPI. Each mutant line was characterized in regards to pollen grain adherence, pollen tube penetration, and seed set. Of the mutant lines examined, α1-copi had the strongest phenotype with issues with compatible pollen grain adherence, tube germination and reduction in seed set while other lines had milder but visible retardation in compatible pollen acceptance. The data presented here are the first study of the role of the COPI complex in compatible pollinations and that certain subunit isoforms are required for compatible pollen acceptance.

scholarly journals Anomalous pollen grain development after nondifferentiating microspore division in Eremurus

2015 ◽  
Vol 46 (3) ◽  
pp. 459-469
Author(s):  
M. Charzyńska ◽  
J. Maleszka ◽  
B. Hon
Keyword(s):  
Mitotic Spindle ◽  
Generative Cell ◽  
Pollen Grains ◽  
Pollen Grain ◽  
Grain Development ◽  
Compact Structure ◽  
Cytoplasmic Rna ◽  
Ca 50 ◽  
Protoplast Division

Anomalous pollen grain development in <i>Eremurus</i> is caused by an anomalous position of the mitotic spindle and microspore protoplast division into two cells different than in differentiating division. The nuclei of the abnormal gametophytes are always spherical and that of the smaller of the two cells, notwithstanding the shape and position of the latter, has a more compact structure resembling rather that of the generative cell nucleus. Binucleate abnormal gametophytes always have equal nuclei. The wall separating the cells in abnormal pollen grains at first contains callose and, after disappearance of the latter, probably pectins and cellulose. Abnormal pollen grains contain less cytoplasmic RNA than normal ones arid most of them degenerate. If their viability is preserved they do not form' normal pollen tubes in vitro. The frequency of anomalous microspore division is higher in <i>E. robustus</i> (max ca. 50%) than in <i>E. himalaicus</i> (max. ca. 30%) and shows considerable seasonal variations. The results obtained suggest that disturbances in microspore development in <i>Eremurus</i> have a genetic background, but are stimulated by temperature variations in the period preceding mitosis in the microspore.

An integrated screening method for evaluating the pulmonary toxicity of inhaled particulates: Role of microscopic techniques in assessing pulmonary macrophage clearance functions

1990 ◽  
Vol 48 (3) ◽  
pp. 826-827
Author(s):  
David B. Warheit ◽  
Lena Achinko ◽  
Mark A. Hartsky
Keyword(s):  
Bronchoalveolar Lavage ◽  
Pulmonary Toxicity ◽  
Screening Method ◽  
Pulmonary Response ◽  
Inhaled Particles ◽  
Cytochemical Analysis ◽  
Pulmonary Macrophages ◽  
Integrated Screening

There is a great need for the development of a rapid and reliable bioassay to evaluate the pulmonary toxicity of inhaled particles. A number of methods have been proposed, including lung clearance studies, bronchoalveolar lavage analysis, and in vitro cytotoxicity tests. These methods are often limited in scope inasmuch as they measure only one dimension of the pulmonary response to inhaled, instilled or incubated dusts. Accordingly, a comprehensive approach to lung toxicity studies has been developed.To validate the method, rats were exposed for 6 hours or 3 days to various concentrations of either aerosolized alpha quartz silica (Si) or carbonyl iron (CI) particles. Cells and fluids from groups of sham and dust-exposed animals were recovered by bronchoalveolar lavage (BAL). Alkaline phosphatase, LDH and protein values were measured in BAL fluids at several time points postexposure. Cells were counted and evaluated for viability, as well as differential and cytochemical analysis. In addition, pulmonary macrophages (PM) were cultured and studied for morphology, chemotaxis, and phagocytosis by scanning electron microscopy.

Towards the Final Legitimation of the Party

2017 ◽  
Author(s):  
Piero Ignazi
Keyword(s):  
Twentieth Century ◽  
Great Britain ◽  
Political Parties ◽  
Political Party ◽  
Sole Source ◽  
The Political ◽  
Party Formation ◽  
Post War ◽  
Dominant Influence

Chapter 3 investigates the process of party formation in France, Germany, Great Britain, and Italy, and demonstrates the important role of cultural and societal premises for the development of political parties in the nineteenth century. Particular attention is paid in this context to the conditions in which the two mass parties, socialists and Christian democrats, were established. A larger set of Western European countries included in this analysis is thoroughly scrutinized. Despite discontent among traditional liberal-conservative elites, full endorsement of the political party was achieved at the beginning of the twentieth century. Particular attention is paid to the emergence of the interwar totalitarian party, especially under the guise of Italian and German fascism, when ‘the party’ attained its most dominant influence as the sole source and locus of power. The chapter concludes by suggesting hidden and unaccounted heritages of that experience in post-war politics.

scholarly journals A Duplicated Copy of the Meiotic Gene ZIP4 Preserves up to 50% Pollen Viability and Grain Number in Polyploid Wheat

Biology ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 290
Author(s):  
Abdul Kader Alabdullah ◽  
Graham Moore ◽  
Azahara C. Martín
Keyword(s):  
Pollen Viability ◽  
Pollen Grains ◽  
Wheat Chromosome ◽  
Grain Number ◽  
Meiotic Gene ◽  
Chromosome 5B ◽  
Mutant Pollen ◽  
Female Gametogenesis ◽  
Chromosome 3B

Although most flowering plants are polyploid, little is known of how the meiotic process evolves after polyploidisation to stabilise and preserve fertility. On wheat polyploidisation, the major meiotic gene ZIP4 on chromosome 3B duplicated onto 5B and diverged (TaZIP4-B2). TaZIP4-B2 was recently shown to promote homologous pairing, synapsis and crossover, and suppress homoeologous crossover. We therefore suspected that these meiotic stabilising effects could be important for preserving wheat fertility. A CRISPR Tazip4-B2 mutant was exploited to assess the contribution of the 5B duplicated ZIP4 copy in maintaining pollen viability and grain setting. Analysis demonstrated abnormalities in 56% of meiocytes in the Tazip4-B2 mutant, with micronuclei in 50% of tetrads, reduced size in 48% of pollen grains and a near 50% reduction in grain number. Further studies showed that most of the reduced grain number occurred when Tazip4-B2 mutant plants were pollinated with the less viable Tazip4-B2 mutant pollen rather than with wild type pollen, suggesting that the stabilising effect of TaZIP4-B2 on meiosis has a greater consequence in subsequent male, rather than female gametogenesis. These studies reveal the extraordinary value of the wheat chromosome 5B TaZIP4-B2 duplication to agriculture and human nutrition. Future studies should further investigate the role of TaZIP4-B2 on female fertility and assess whether different TaZIP4-B2 alleles exhibit variable effects on meiotic stabilisation and/or resistance to temperature change.

The End of Sharecropping in Central Italy after 1945: The Role of Mechanisation in the Changing Relationship between Peasant Families and Land

Rural History ◽  
2014 ◽  
Vol 25 (2) ◽  
pp. 243-260 ◽  
Author(s):  
STUART OGLETHORPE
Keyword(s):  
Labour Supply ◽  
Labour Force ◽  
Central Italy ◽  
Rural Landscape ◽  
Rapid Decline ◽  
Farming Families ◽  
Political Economic ◽  
The Relationship ◽  
Push Factor

Abstract:This article focuses on the mechanisation of agriculture in central Italy in the thirty years or so after 1945. This provides a particular way of examining the major changes in the rural landscape in this period, especially the end of the sharecropping system. Land in these regions had for centuries been predominantly farmed under sharecropping contracts, but for political, economic, and demographic reasons this system, which had inhibited modernisation, entered a rapid decline. Whereas labour supply had previously exceeded demand, the reverse became the case, allowing sharecropping families more freedom in how they operated. Mechanisation was not a ‘push’ factor, but as the agricultural labour force contracted it was a necessary response. The article uses individual testimony to illustrate how tenant farmers started to work outside the sharecropping contract, some becoming outside contractors with other farms and supplying tractor hire. The mechanisation of agriculture was slow and uneven, but marked an irreversible change in the relationship between farming families and their land.

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