The nucleolar organizer (NOR) and fibrillar centers during plant gametogenesis

Medina, F. Javier; Risueño, María Carmen; Rodríguez-García, Marìa Isabel; Pina, María Amelia Sánchez

doi:10.1016/s0022-5320(83)90041-2

Cited by 12 publications

(4 citation statements)

References 18 publications

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“…The results in Fig. 3B also suggest that the nucleolar-specific histone might be preferentially localized in the nucleolar organizing region (NOR) of the chromosome since it has been demonstrated that NORs are always observed at the periphery of the nucleoli in plant meiocytes (Williams et al 1973;Medina et al 1983b). It has been proposed that FCs might be the interphase counterparts of NORs (Hernandez-Verdun et al 1980;Jordan et al 1982;Medina et al 1983a).…”

Section: Localization Of the Nucleolar Histone Hlmentioning

confidence: 67%

“…It is known that some plant cells have an order of magnitude more rDNA than animal cells. And there is a characteristically heterogeneous FC that includes condensed chromatin, in addition to the more usual homogeneous FC (Risueno et al 1982;Medina et al 1983b). The nucleolar histone Hl may accumulate in such specialized chromatin.…”

Section: Function Of the Nucleolar Histone Hlmentioning

confidence: 99%

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A novel histone variant localized in nucleoli of higher plant cells

et al. 1999

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Immunofluorescence staining with antisera raised against p35, a basic nuclear protein that accumulates in the pollen nuclei of Lilium longiflorum, specifically stained the nucleoli in interphase nuclei of somatic tissues, including root and leaf, and in pachytene nuclei during meiotic division, whereas antisera raised against histone H1 uniformly stained the entire chromatin domain with the exception of the nucleoli in these nuclei. Further, p35-specific antisera stained the nucleoli in root and leaf nuclei of the monocotyledonous plants Tulipa gesneriana, Allium cepa and Triticum aestivum and of the dicotyledonous plants Vicia faba and Nicotiana tabacum. Thus, these novel antisera stained the nucleoli in cells of all higher plants examined, although the staining patterns within nucleoli were somewhat different among plant species and tissues. The full-length cDNA of p35 was cloned on the basis of the partial amino acid sequence. The deduced amino acid composition and amino acid sequence of p35 indicate that this nucleolar protein is a novel variant of histone Hl. Further, p35 was strongly bound to ribosomal DNA in vitro. The results of immunoblotting of histones extracted from each tissue of the various plant species with the nucleolus-specific antibodies also suggested the conservation of similar epitope(s) in both mono- and dicotyledonous plants. From these results, it is suggested that similar variants of histone Hl are specifically distributed in the nucleoli of all plant species and help to organize the nucleolar chromatin.

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Section: Localization Of the Nucleolar Histone Hlmentioning

confidence: 67%

Section: Function Of the Nucleolar Histone Hlmentioning

confidence: 99%

A novel histone variant localized in nucleoli of higher plant cells

et al. 1999

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“…It is known that Cajal bodies (CBs) contain nucleolar proteins of the agyrophylic type; thus the Ag-NOR technique is also one of the methods for their identification in different cell types, including plant cells [ 39 – 41 ]. Indeed, the size and shape of these nuclear structures, as well as the localization in the nucleus, strongly suggest that they are Cajal bodies.…”

Section: Discussionmentioning

confidence: 99%

snRNP: Rich Nuclear Bodies inHyacinthus orientalisL. Microspores and Developing Pollen Cells

Zienkiewicz

Bednarska

2009

International Journal of Cell Biology

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The aim of the present work was the characterization of nuclear bodies in the microspore and developing pollen cells of Hyacinthus orientalis L.. The combination of Ag-NOR, immunofluorescence and immunogold techniques was used in this study. The obtained results showed the presence of highly agyrophylic extranucleolar bodies in microspore and developing pollen cells, which were finally identified as Cajal bodies. In all cases, a strong accumulation of snRNP-indicating molecules including TMG cap, Sm proteins and U2 snRNA, was observed in the examined nuclear bodies. In contrast to their number the size of the identified structures did not change significantly during pollen development. In the microspore and the vegetative cell of pollen grains CBs were more numerous than in the generative cell. At later stages of pollen development, a drastic decrease in CB number was observed and, just before anthesis, a complete lack of these structures was indicated in both pollen nuclei. On the basis of these results, as well as our previous studies, we postulate a strong relationship between Cajal body numbers and the levels of RNA synthesis and splicing machinery elements in microspore and developing pollen cells.

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“…Earlier work had shown the conversion of the heterogeneous FCs, undoubtedly containing condensed rDNA chromatin, into homogeneous FCs, the small type of FCs present in active plant nucleoli containing decondensed chromatin, in the course of germination (Deltour 1985;Risueiio and Medina 1986) as well as during postmeiotic nucleolar reactivation in young microspores (Esponda and Gimenez-Martin 1974;Medina et al 1983). The existence ofa nucleolar matrix or nucleolar proteinaceous skeleton with the function, among others, of gathering rDNA in FCs and structurally organizing it depending on the nucleolar activity and the requirements of the cells (Moreno Diaz de la Espina 1995) is now supported by the fact that MARor SARelements are present in the AT-rich region of every rDNA repeat (see above) .…”

Section: Structural-functional Organization Of the Nucleolusmentioning

confidence: 99%

Molecular Cell Biology: Organization and Molecular Evolution of rDNA, Nucleolar Dominance, and Nucleolus Structure

et al. 2004

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Recently, the ribosomes -molecularly well-characterized cell organelles where the process of translation of messenger RNA into polypeptides occurs -have attracted new interest since they can be considered as a huge ribozyme-like complex consisting of different proteins and RNA -the RNAs mainly fulfilling functional tasks in translation, the proteins serving more structural functions (Moore and Steitz 2002). Within the eukaryotic cell, two (animals and fungi) or three (plants) sites of a translational machinery are present, the cytoplasm, mitochondria and chloroplasts, and, respectively, the components are mostly encoded in the cell nucleus or the mitochondrial or chloroplast genome. Since new insights are gained into the production and the assembly of the ribosome components, ribosomal RNA (rRNA) and ribosomal proteins (r-proteins), in this chapter, we focus on the nucleolus, the site for cytoplasmic ribosome biogenesis and assembly occurring in the light-microscopically visible structure of the cell nucleus. Similarly as in prokaryotes, for all higher organisms two ribosome subunits are preformed in the nucleolus, which are evolutionary conserved: the small 40S subunit (SSU) containing 18SrRNA, and the large 60S subunit containing 25/28S plus 5.8S and 5S rRNA. After export of the ribosome subunits (LSU) into the cytoplasm, the functionally active ribosome is associated with translatable mRNA to an 80S complex corresponding to the 70S structure in chloroplasts and prokaryotic cells.Following the ribozyme concept, ribosome subunits are built up by rRNA and r-proteins. The nuclear encoded rRNA genes (rDNA) are present as a multigene family in the genome, mostly located at the NOR (nucleolus-organizing region). In the transition area from fibrillar centers to the dense fibrillar component (FC/DFC) of the nucleolus, the 18S, 5.8S and 25S/28S rRNA are commonly transcribed by RNA polymerase I (pol I) as a large precursor, which in plants is approx. 35S in size (35S pre-rRNA); this 35Spre-rRNA is then stepwisely processed into the respective rRNAs. RNA polymerase III (pol III) transcribes the 5S rRNA component encoded by 5S

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The nucleolar organizer (NOR) and fibrillar centers during plant gametogenesis

Cited by 12 publications

References 18 publications

A novel histone variant localized in nucleoli of higher plant cells

A novel histone variant localized in nucleoli of higher plant cells

snRNP: Rich Nuclear Bodies inHyacinthus orientalisL. Microspores and Developing Pollen Cells

Molecular Cell Biology: Organization and Molecular Evolution of rDNA, Nucleolar Dominance, and Nucleolus Structure

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