Synthesis and accumulation of ribosomes in individual cells of the female gametophyte of maize during its development

D, Dow; Mascarenhas, Joseph P.

doi:10.1007/bf00200543

Cited by 11 publications

(6 citation statements)

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“…A high level of ribosomes in the cells of the embryo sac, including the egg cell, was observed earlier in Zea (Dow and Mascarenhas 1991a , b ). Investigations using the in situ hybridization method with a probe for 25S rRNA indicated that the number of ribosomes increases during the development of the embryo sac, reaching the highest level during its maturity.…”

Section: Discussionsupporting

confidence: 61%

“…During this period, intensive transport of newly formed ribosomal subunits to the cytoplasm also occurs, which is indicated by a high rRNA signal at the boundary between the nucleus and the cytoplasm. The process of ribosome accumulation in the cytoplasm of the maturing central cell was previously observed in Zea (Dow and Mascarenhas 1991a , b ). Our investigations indicate that, in H. orientalis , ribosome maturation also takes place during the progamic phase.…”

Section: Discussionmentioning

confidence: 54%

“…Among newly synthesized transcripts, a large percentage probably consists of rRNA. Investigations in Zea have shown that, during the development of the embryo sac, the egg apparatus and the central cell contain severalfold more ribosomes than are present in the antipodal cells or the cells of the surrounding nucellus (Dow and Mascarenhas 1991a ). A similar differentiation in the ribosome pool is maintained in the mature embryo sac when the egg cell is metabolically silenced (Dow and Mascarenhas 1991b ).…”

Section: Introductionmentioning

confidence: 99%

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Ribosomal RNA of Hyacinthus orientalis L. female gametophyte cells before and after fertilization

Niedojadło

Pięciński

Smoliński

et al. 2012

Planta

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The nucleolar activity of Hyacinthus orientalis L. embryo sac cells was investigated. The distributions of nascent pre-rRNA (ITS1), 26S rRNA and of the 5S rRNA and U3 snoRNA were determined using fluorescence in situ hybridization (FISH). Our results indicated the different rRNA metabolism of the H. orientalis female gametophyte cells before and after fertilization. In the target cells for the male gamete, i.e., the egg cell and the central cell whose activity is silenced in the mature embryo sac (Pięciński et al. in Sex Plant Reprod 21:247–257, 2008; Niedojadło et al. in Planta doi:10.1007/s00425-012-1599-9, 2011), rRNA metabolism is directed at the accumulation of rRNPs in the cytoplasm and immature transcripts in the nucleolus. In both cells, fertilization initiates the maturation of the maternal pre-rRNA and the expression of zygotic rDNA. The resumption of rRNA transcription observed in the hyacinth zygote indicates that in plants, there is a different mechanism for the regulation of RNA Pol I activity than in animals. In synergids and antipodal cells, which have somatic functions, the nucleolar activity is correlated with the metabolic activity of these cells and changes in successive stages of embryo sac development.Electronic supplementary materialThe online version of this article (doi:10.1007/s00425-012-1618-x) contains supplementary material, which is available to authorized users.

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Section: Discussionsupporting

confidence: 61%

Section: Discussionmentioning

confidence: 54%

Section: Introductionmentioning

confidence: 99%

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Ribosomal RNA of Hyacinthus orientalis L. female gametophyte cells before and after fertilization

Niedojadło

Pięciński

Smoliński

et al. 2012

Planta

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“…Such in situ hybridization analyses have enabled us to determine the relative numbers of ribosomes in the cells of the mature female gametophyte and also in immature stages of embryo sac development (Dow and Mascarenhas 1991).…”

Section: Discussionmentioning

confidence: 99%

Optimization of conditions for in situ hybridization and determination of the relative number of ribosomes in the cells of the mature embryo sac of maize

Mascarenhas

1991

Sexual Plant Reprod

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Summary.We have initiated experiments to understand the molecular regulation of embryo sac development in flowering plants by a study of ribosome synthesis and accumulation. Because of the very small size of the embryo sac and the large volume of ovule tissue it is embedded in, in situ hybridization with nucleic acid probes is presently the only practical method for such molecular measurements on individual cells of the embryo sac. Methods of tissue preparation, sectioning and screening of ovules for embryo sac containing sections, in situ hybridization using a ribosomal mRNA probe, and staining were optimized. Relative densities of silver grains for individual cells of the mature maize (W22) embryo sac were determined from in situ hybridizations. The silver grain counts are directly related to the numbers of ribosomes. Volumes of individual cells were determined by confocal microscope image analysis, and this permitted the calculation of the relative total numbers of ribosomes in individual cells of the embryo sac and nucellus. The central cell has a volume 260 times that of a nucellar cell at the micropylar end of the ovule, 15 times that of the egg cell, 30 times that of a synergid, and 130 times the volume of an antipodal cell. The mature maize embryo sac has 20 or more antipodal cells. The central cell has approximately 200 times the number of ribosomes as are present in a nucellar cell, about 7 times as many ribosomes as are in the egg cell, 14 times as many ribosomes as in each synergid, and about 80 times the ribosome content of individual antipodal cells. The data are discussed with respect to the utilization of the ribosomes following fertilization in the early embryo and endosperm.

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“…During female gametogenesis, the haploid functional megaspore undergoes continuous cell growth and three cycles of consecutive nuclear division without cytokinesis, giving rise to a giant eight-nucleate, coenocytic cell: the embryo sac. The size of the embryo sac increases about 6-fold without cytokinesis until it reaches its maximum during gametogenesis in maize (Zea mays; Dow and Mascarenhas, 1991). The two polar nuclei migrate toward the micropylar half of the embryo sac and eventually fuse to give rise to a diploid nucleus of the central cell.…”

mentioning

confidence: 99%

SLOW WALKER2, a NOC1/MAK21 Homologue, Is Essential for Coordinated Cell Cycle Progression during Female Gametophyte Development in Arabidopsis

Li¹,

Li²,

Liu³

et al. 2009

Plant Physiol.

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Morphogenesis requires the coordination of cell growth, division, and cell differentiation. Female gametogenesis in flowering plants, where a single haploid spore undergoes continuous growth and nuclear division without cytokinesis to form an eightnucleate coenocytic embryo sac before cellularization, provides a good system to study the genetic control of such processes in multicellular organisms. Here, we report the characterization of an Arabidopsis (Arabidopsis thaliana) female gametophyte mutant, slow walker2 (swa2), in which the progression of the mitotic cycles and the synchrony of female gametophyte development were impaired, causing an arrest of female gametophytes at the two-, four-, or eight-nucleate stage. Delayed pollination test showed that a portion of the mutant ovules were able to develop into functional embryo sacs and could be fertilized. SWA2 encodes a nucleolar protein homologous to yeast NUCLEOLAR COMPLEX ASSOCIATED PROTEIN1 (NOC1)/MAINTENANCE OF KILLER21 that, together with NOC2, is involved in preribosome export from the nucleus to the cytoplasm. Similarly, SWA2 can physically interact with a putative Arabidopsis NOC2 homologue. SWA2 is expressed ubiquitously throughout the plant, at high levels in actively dividing tissues and gametophytes. Therefore, we conclude that SWA2 most likely plays a role in ribosome biogenesis that is essential for the coordinated mitotic progression of the female gametophyte.

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Synthesis and accumulation of ribosomes in individual cells of the female gametophyte of maize during its development

Cited by 11 publications

References 4 publications

Ribosomal RNA of Hyacinthus orientalis L. female gametophyte cells before and after fertilization

Ribosomal RNA of Hyacinthus orientalis L. female gametophyte cells before and after fertilization

Optimization of conditions for in situ hybridization and determination of the relative number of ribosomes in the cells of the mature embryo sac of maize

SLOW WALKER2, a NOC1/MAK21 Homologue, Is Essential for Coordinated Cell Cycle Progression during Female Gametophyte Development in Arabidopsis

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