The Ag-NOR proteins present a crescent-shaped distribution at the secondary constrictions of metaphase PtK&lt;sub&gt;1&lt;/sub&gt; chromosomes

Suja, José Á.; Hernandez‐Verdun, Danièle

doi:10.1159/000134468

Cited by 3 publications

References 4 publications

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Relative distribution of rDNA and proteins of the RNA polymerase I transcription machinery at chromosomal NORs

et al. 1997

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Using confocal and immunofluorescence microscopy the relative distribution of the ribosomal chromatin and some proteins of the RNA polymerase I transcription machinery such as upstream binding factor (UBF), RNA polymerase I and DNA topoisomerase I was analyzed on chromosomal nucleolus organizer regions (NORs) of PtK1 cells. Staining with various DNA fluorochromes revealed that the ribosomal chromatin may be found at the axial region of the NOR and also at lateral expansions around the axis that can also be detected by in situ hybridization. It was observed that the transcription machinery shows a crescent-shaped distribution around the axial ribosomal chromatin at the NOR of metaphase and anaphase chromatids. An ultrastructural analysis of serially sectioned NORs supports this crescent-shape organization. Taking into account previous and present results and the loop/scaffold model of chromosome structure, we propose a model of NOR organization. The model proposes that ribosomal genes that were inactive in the preceding interphase would be present as condensed short Q-loops occupying the axial region of the NOR. Ribosomal genes previously active during interphase would be undercondensed as large R-loops associated with the transcription machinery, which is distributed in a crescent-shaped fashion around the previously active ribosomal DNA.

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Relative distribution of rDNA and proteins of the RNA polymerase I transcription machinery at chromosomal NORs

et al. 1997

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Cell and Molecular Biology of Nucleolar Assembly and Disassembly

DiMario

2004

International Review of Cytology

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Comparative Karyotype Analysis of Grasshoppers in the Genus Oxya (Orthoptera, Catantopidae) by Differential Staining Techniques

et al. 2005

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SummaryThe chromosomes of 4 species of grasshopper in the genus Oxya were analyzed by conventional and five differential-staining methods. All 4 species had a chromosome complement of 2nϭ22ϩXX(female)/XO(male), with very similar karyotypes. Both O. hyla intricata and O. japonica japonica had acrocentric chromosomes with minute short arms, while the chromosomes of O. chinensis formosana and O. yezoensis were almost all telocentric. In all 4 species, a secondary constriction (SC) was detected at a proximal site in chromosome 8, which had the same staining properties (positive for C-and CMA-banding; negative for G-and QM-banding) in all 4 species. Our Cbanding analysis revealed that the short arms of O. hyla intricata and O. japonica japonica consisted of C-heterochromatin. The 4 species yielded species-specific patterns of C-bands, and there appeared to be a close relationship between O. chinensis formosana and O. yezoensis, as suggested by the polymorphism of the distal C-bands of chromosome 2. In all 4 species of Oxya, Ag-NORs were detected on the centromeric regions of all the chromosomes, but not detected on the SC of chromosome 8. The karyosystematic relationships among the 4 species are discussed on the basis of the results of differential staining.

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The Ag-NOR proteins present a crescent-shaped distribution at the secondary constrictions of metaphase PtK<sub>1</sub> chromosomes

Cited by 3 publications

References 4 publications

Relative distribution of rDNA and proteins of the RNA polymerase I transcription machinery at chromosomal NORs

Relative distribution of rDNA and proteins of the RNA polymerase I transcription machinery at chromosomal NORs

Cell and Molecular Biology of Nucleolar Assembly and Disassembly

Comparative Karyotype Analysis of Grasshoppers in the Genus Oxya (Orthoptera, Catantopidae) by Differential Staining Techniques

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