Intercellular NOR-Ag-variability in man. II. Search for determining factors, clonal analysis

Sozansky, O. A.; Terekhov, S. M.

doi:10.1007/bf00293287

Cited by 14 publications

(8 citation statements)

References 13 publications

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“…Although various results have been presented in the literature concerning the differential expression of AgNORs depending on the cell types and/or culture conditions employed (Mikclsaar and Schwarzacher. 1978: Capoa et al, 1985: Sozansky et al, 1985, our results indicate no appreciable difference in the strainspecific pattern of Ag-NORs among cultured or non cultured tissue cells of different origin in a given inbred strain, so far as the present scope of the investigation is concerned. On the other hand, a line of evidence has been presented for the existence of a regulatory mech anism for expression or suppression of Ag-NORs which coincides with the transcriptional activity of ribosomal cistrons, as shown in some rodent-human somatic cell hybrids (Miller et al, 1976;Croce et al, 1977;Tantravahi et al.…”

Section: Discussionmentioning

confidence: 69%

Characterization of silver-stained nucleolus organizer regions (Ag-NORs) in 16 inbred strains of the Norway rat, Rattus norvegicus

Sasaki

Nishida

Kodama³

1986

Cytogenet Genome Res

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Silver-stained nucleolus organizer regions (Ag-NORs) in metaphase chromosomes of cultured fibroblasts were compared among 16 inbred strains of the Norway rat, Rattus norvegicus. Ag-NORs were located at the secondary constrictions or juxtacentromeric regions of the short arms of chromosomes 3, 11, and 12. The frequency and relative size of Ag-NORs were found to be strain-specific, providing a genetic marker system useful for characterization of inbred strains. While considerable cell-to-cell variation was observed within a given strain, the strain-specific pattern of Ag-NORs was shown to be consistent in cultured and noncultured cells obtained from different tissues of embryos, newborns, and adults, as well as in successively cultured cells examined up to the 10th subculture generation. The patterns of Ag-NORs in F₁ hybrids made between some of the inbred strains were in general agreement with those expected from the parental strains; some unexpected patterns were noted in F₁ hybrids of a particular cross, suggesting the possible existence of nucleolar interactions in such interstrain hybrids, although this has to be confirmed.

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Section: Discussionmentioning

confidence: 69%

Characterization of silver-stained nucleolus organizer regions (Ag-NORs) in 16 inbred strains of the Norway rat, Rattus norvegicus

Sasaki

Nishida

Kodama³

1986

Cytogenet Genome Res

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“…Results of in situ hybridization reveal that observed number of copies of the rRNA genes varies within species (W ACHTLER et al 1986;MELLINK et al 1991;SUZUKI et al 1992). The irregularity comprises species, breed, individual, and intercellular variations both in the number and size of silver deposits (WINKING et al 1980;ZAKHAROV et al 1982;SOZANSKY et Downloaded by [New York University] at 07:46 20 July 2015 al. 1985;MELLINK et al 1991MELLINK et al , 1992SUZUKI et al 1992).…”

Section: Introductionmentioning

confidence: 99%

The comparative analysis of NOR polymorphism detected by FISH and Ag-staining on horse chromosomes

et al. 1998

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The nucleolus organizer regions were investigated by FISH with biotinylated rDNA probe and silver staining on chromosomes of the domestic horse (Equus caballus}. Ribosomal RNA loci were mapped at the secondary constrictions of the short arm of chromosome 1 and at the pericentromeric regions of chromosomes 27, 28 and 31. A new nucleolus-organizing chromosome 27 was identified. The interindividual, and interchromosomal polymorphism of NORs was described in 26 horses from 5 breeds. The relative rRNA gene activity was evaluated by the number of silverstained chromosomes, and the size of silver deposits. The relative amount of rDNA in NORs was estimated by intensity of fluorescent hybridization signals. The size of silver deposits and intensity of fluorescence after FISH were determined for each NOR using arbitrary scales of 0-3 and 0-5, respectively. The statistical analysis of these data revealed a tendency for differentiation of NORbearing chromosome pairs by the rRNA gene number of copies, and the activity. A close correlation between activity of the rRNA genes and the relative number of rRNA gene copies was not found for NORs of homologous chromosomes.

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“…The size of silver granule dots at metaphase is much smaller than the silver granule dots at interphase because only 10% of the silver stained nucleolar protein during interphase are retained on metaphase chromosomes (Sumner 2003). The AgNOR pattern in the metaphase cell is specific and constant (Sozansky et al 1985, Isakova 1994, and thus can be used as the chromosomal marker to detect polymorphisms of Ag-stained NORs on prairie cordgrass chromosomes.…”

Section: Discussionmentioning

confidence: 99%

Analysis of Active Nucleolus Organizing Regions in Polyploid Prairie Cordgrass (Spartina pectinata Link) by Silver Staining

2015

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Summary Prairie cordgrass has recently gained attention as an important biotic component of stressed ecosystems. This polyploid species is distributed broadly across the U.S. More cytogenetic data are needed to investigate how increased ploidy levels influence chromosome changes and gene expression in order to understand the formation of stable cytotypes. Silver staining is the cytogenetic method commonly used to study the number and distribution of active nucleolar organizing regions (NORs) on chromosomes at metaphase, and the number and size of nucleoli in nuclei at interphase. Intensity and distribution patterns of silver stained NORs (AgNORs) reveal differential ribosomal gene expressions in plants and animals. The purpose of this study is to estimate the number of AgNORs, their locations, and their activities in metaphase chromosomes and to determine heteromorphic variation in size and number of nucleoli within interphase nuclei for tetra-, hexa-, and octoploid prairie cordgrass populations. Increases in mean numbers of AgNORs in each metaphase and interphase cell were observed as ploidy level increases. Although distribution patterns of silver stained NORs at metaphase cells of tetra-and octoploids reflect changes in ploidy, the neohexaploids did not follow the pattern, indicating that active NORs were not stable in early generation of formation of neo-hexaploidy. Collectively, these results suggest that distribution patterns of silver stained NORs in metaphase and number of silver stained nucleoli in interphase cells can be used as markers to detecting chromosome variations within and among ploidy levels and to determine when ploidy levels stabilize in prairie cordgrass.

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Intercellular NOR-Ag-variability in man. II. Search for determining factors, clonal analysis

Cited by 14 publications

References 13 publications

Characterization of silver-stained nucleolus organizer regions (Ag-NORs) in 16 inbred strains of the Norway rat, <i>Rattus norvegicu</i><i>s</i>

Characterization of silver-stained nucleolus organizer regions (Ag-NORs) in 16 inbred strains of the Norway rat, <i>Rattus norvegicu</i><i>s</i>

The comparative analysis of NOR polymorphism detected by FISH and Ag-staining on horse chromosomes

Analysis of Active Nucleolus Organizing Regions in Polyploid Prairie Cordgrass (<i>Spartina pectinata</i> Link) by Silver Staining

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