Variation within and between nucleolar organizer regions in Australian hylid frogs (Anura) shown by 18S+28S in-situ hybridization

Genetica ◽  
1990 ◽  
Vol 80 (1) ◽  
pp. 17-29 ◽  
Author(s):  
M. King ◽  
N. Contreras ◽  
R. L. Honeycutt
Keyword(s):  
In Situ Hybridization ◽  
Nucleolar Organizer ◽  
Nucleolar Organizer Regions

Sequential silver staining and in situ hybridization reveal a direct association between rDNA levels and the expression of homologous nucleolar organizing regions: a hypothesis for NOR structure and function

1998 ◽  
Vol 111 (10) ◽  
pp. 1433-1439
Author(s):  
F. Zurita ◽  
R. Jimenez ◽  
M. Burgos ◽  
R.D. de la Guardia
Keyword(s):  
Transcription Factors ◽  
In Situ Hybridization ◽  
Silver Staining ◽  
Organizer Region ◽  
Nucleolar Organizer ◽  
Interindividual Variation ◽  
Nucleolar Organizer Regions ◽  
Single Pair ◽  
Ribosomal Cistrons

We have developed a procedure for sequential silver staining and in situ hybridization to analyze the relationship between the amount of rDNA present in nucleolar organizer regions, as estimated by in situ hybridization, and their level of expression, as estimated by the silver signal. For simplicity we used cells from the insectivorous mole Talpa occidentalis, which have a single pair of nucleolar organizer regions in chromosome pair 3. The relative content of ribosomal cistrons was also related to the hierarchy of activation of the nucleolar organizer regions present in this chromosomal pair. Statistical analyses demonstrated that both the relative level of expression and the activation hierarchy depended mainly on the number of ribosomal cistrons in nucleolar organizer regions. We propose a functional two-step hypothesis, which is consistent with most known data concerning interchromosomal, intercellular and interindividual variation in a number of plant and animal species, including Talpa occidentalis. In step one, the first available transcription factors bind randomly to the ribosomal promoters, such that larger nucleolar organizer regions are more likely to recruit them. In the second step the remaining transcription factors are recruited in a cooperative way, thus completing activation of one nucleolar organizer region, before the next one becomes active.

scholarly journals Cytogenetics of two sympatric Corydoras species (pisces, siluriformes, challichtyidae) of Southern Brazil

2006 ◽  
Vol 66 (1b) ◽  
pp. 191-198 ◽  
Author(s):  
R. F. Artoni ◽  
M. L. Terêncio ◽  
M. R. Vicari ◽  
M. C. A. Matiello ◽  
M. M. Cestari ◽  
...  
Keyword(s):  
In Situ Hybridization ◽  
Diploid Number ◽  
Constitutive Heterochromatin ◽  
Nucleolar Organizer ◽  
Nucleolar Organizer Regions ◽  
Great Similarity ◽  
Southern Brazil ◽  
Rdna Probe ◽  
Karyotypic Formula

Karyotypic data are presented for two sympatric Corydoras species of the Lagoa Dourada, namely, C. ehrhadti and C. paleatus, which are found in the upper Tibagi river basin (Ponta Grossa, State of Paraná, Brazil). The same diploid number and karyotypic formula were observed in both species/populations. A great similarity in the constitutive heterochromatin distribution and in the activity of nucleolar organizer regions was also found. The use of in situ hybridization with a fluorescent 18S rDNA probe allowed for the identification of the species/populations through the location of ribosomal sites.

Chromosomal and genomic organization of Ty1-copia-like retrotransposon sequences in the genus Avena

Genome ◽  
1996 ◽  
Vol 39 (2) ◽  
pp. 410-417 ◽  
Author(s):  
A. Katsiotis ◽  
T. Schmidt ◽  
J. S. Heslop-Harrison
Keyword(s):  
In Situ Hybridization ◽  
Repetitive Sequence ◽  
Genomic Library ◽  
Nucleolar Organizer ◽  
Nucleolar Organizer Regions ◽  
Reaction Products ◽  
D Genome ◽  
Avena Species ◽  
Copy Numbers

A cloned repetitive sequence, pAvKB30, obtained from an Avena vaviloviana (AB genome) genomic library, along with two polymerase chain reaction products derived from the conserved region of the reverse transcriptase (RT) gene of retrotransposons, were characterized molecularly and cytologically. The cloned DNA fragment was a dispersed repeat present in all Avena species used in this study (A. strigosa, A. clauda, A. vaviloviana, A. magna, and A. sativa). The fragment was sequenced (210 bp) and found to be 69.5% homologous to part of WIS-2-1A, and 60.5% homologous to the leader sequence of BARE-1; both of these elements have been characterized as Ty1-copia-like retrotransposons in wheat and barley, respectively. In situ hybridization of pAvKB30 to diploid, tetraploid, and hexaploid oat species revealed that the probe is present on both arms of all chromosomes (A, B, C, and D genomes) but is excluded from their centromeric and nucleolar organizer regions. By using double in situ hybridization in hexaploid A. sativa (ACD genome), pAvKB30 was found to be present in lower copy numbers in C-genome chromosomes compared with A- and D-genome chromosomes. Furthermore, under low stringency conditions, pAvKB30 hybridized on Southern blots containing barley, wheat, rye, and Arrhenatherum DNA. However, under high stringency conditions, it hybridized only on Arrhenatherum DNA, which is considered to be the genus most closely related to Avena. All Avena species included in this study yielded a PCR product when the primers from the RT domain of retrotransposons were used. Two products, rtA, obtained by using A. strigosa (As genome) as template, and rtC, obtained by using A. clauda (Cp genome) as template, gave Southern and in situ hybridization results similar to pAvKB30, but each was more abundant in its genome of origin. Key words : genomes, oats, in situ hybridization, translocations, repetitive sequence.

scholarly journals Mapping 18S ribosomal genes in fish of the genus Brycon (Characidae) by fluorescence in situ hybridization (FISH)

2000 ◽  
Vol 23 (1) ◽  
pp. 135-138 ◽  
Author(s):  
Adriane Pinto Wasko ◽  
Pedro Manoel Galetti Jr.
Keyword(s):  
In Situ Hybridization ◽  
Fluorescence In Situ Hybridization ◽  
Nucleolar Organizer ◽  
Rrna Genes ◽  
Nucleolar Organizer Regions ◽  
Single Chromosome ◽  
Individual Variations ◽  
18S Rrna Genes ◽  
High Level

The present study provides data on the nucleolar organizer regions (NORs) of seven Brycon species based on mapping of the 18S rRNA genes by fluorescence in situ hybridization (FISH). Fluorescent signals were observed on the telomere of the long arm of two large submetacentric chromosomes, thus confirming the number and location of NORs previously revealed by other classical cytogenetic techniques. Although there were no inter- or intra-individual variations in the number and location of the 18S loci, NOR size polymorphism was observed between homologous chromosomes. The clustering and conservation of NORs in a single chromosome pair indicates a high level of NOR stability among species of the genus Brycon.

Nucleolar dominance does not occur in root tip cells of allotetraploid Brassica species

Genome ◽  
2000 ◽  
Vol 43 (3) ◽  
pp. 574-579 ◽  
Author(s):  
Robert Hasterok ◽  
Jolanta Maluszynska
Keyword(s):  
In Situ Hybridization ◽  
Nucleolar Organizer ◽  
Brassica Species ◽  
Root Tip ◽  
Nucleolar Organizer Regions ◽  
Nucleolar Dominance ◽  
Rdna Sites ◽  
Rdna Loci ◽  
Allotetraploid Species

Using in situ hybridization and silver staining methods, the numbers of active and inactive rDNA loci have been established for three allotetraploid species of Brassica (B. napus, B. carinata, and B. juncea) and their diploid ancestors (B. campestris, B. nigra, and B. oleracea). The allotetraploid species have chromosome numbers equal to the sum of the numbers in their diploid relatives, but have fewer rDNA loci. All species investigated have lower numbers of active NORs (AgNORs, nucleolar organizer regions) compared with the numbers of rDNA sites revealed by in situ hybridization. The number of active rDNA loci of the allotetraploid species is equal to the number of AgNORs in their diploid ancestors, indicating the absence of nucleolar dominance in amphidiploid Brassica species, at least in root meristematic cells.Key words: AgNOR, Brassica, FISH, nucleolar dominance, rDNA.

scholarly journals Different Proliferation Patterns in Breast Cancer: AgNOR Measurements in ER-Negative and ER-Positive Tumor Cells

2000 ◽  
Vol 20 (4) ◽  
pp. 155-162 ◽  
Author(s):  
Lukas Günther ◽  
Peter Hufnagl ◽  
Klaus‐Jürgen Winzer ◽  
Hans Guski
Keyword(s):  
Breast Cancer ◽  
Tumor Cells ◽  
Nucleolar Organizer ◽  
Growth Fraction ◽  
Nucleolar Organizer Regions ◽  
Ki 67 ◽  
Er Positive ◽  
Negative Tumor ◽  
Invasive Breast Carcinomas

The relation between estrogen receptors (ER) and argyrophilic nucleolar organizer regions (AgNORs)in situwithin human breast cancer cells was analyzed. For AgNOR measurements in 49 invasive breast carcinomas, a new reproducible staining method for dual demonstration of ER and AgNORs was applied. Quantitative AgNOR variables were determined in ER‐positive and ER‐negative tumor cells by digital image analysis. The relationships between AgNOR parameters of ER‐positive and ER‐negative cells and other prognostic factors of breast cancer [Bloom–Richardson‐Grading and growth fraction (Ki‐67 index)] were investigated. A higher AgNOR content in ER‐negative cells and a special clustering phenomenon in ER‐positive tumor cells were found. Correlation with other criteria of malignant potential could be exclusively demonstrated for ER‐negative cells. ER‐negative cells of breast cancer can be characterized as the more malignant and possibly prognosis‐dictating cell fraction. Thus, ER‐negative cells probably contribute more to the progression of the tumor disease and furthermore to the prognosis than ER‐positive cells. We recommend measurement AgNORs exclusively in ER‐negative cells of breast cancer.

Comparative cytogenetic analysis of Avena macrostachya and diploid C-genome Avena species

Genome ◽  
2010 ◽  
Vol 53 (2) ◽  
pp. 125-137 ◽  
Author(s):  
Ekaterina D. Badaeva ◽  
Olga Yu. Shelukhina ◽  
Axel Diederichsen ◽  
Igor G. Loskutov ◽  
Vitaly A. Pukhalskiy
Keyword(s):  
5S Rdna ◽  
Nucleolar Organizer ◽  
Nucleolar Organizer Regions ◽  
Rrna Gene ◽  
Avena Species ◽  
Rdna Sites ◽  
C Genome ◽  
Genome Group ◽  
26S Rrna

The chromosome set of Avena macrostachya Balansa ex Coss. et Durieu was analyzed using C-banding and fluorescence in situ hybridization with 5S and 18S-5.8S-26S rRNA gene probes, and the results were compared with the C-genome diploid Avena L. species. The location of major nucleolar organizer regions and 5S rDNA sites on different chromosomes confirmed the affiliation of A. macrostachya with the C-genome group. However, the symmetric karyotype, the absence of “diffuse heterochromatin”, and the location of large C-band complexes in proximal chromosome regions pointed to an isolated position of A. macrostachya from other Avena species. Based on the distribution of rDNA loci on the C-genome chromosomes of diploid and polyploid Avena species, we propose a model of the chromosome alterations that occurred during the evolution of oat species.

Dynamic Changes in the Distribution of a Satellite Homologous to Intergenic 26-18S rDNA Spacer in the Evolution of Nicotiana

Genetics ◽  
2004 ◽  
Vol 166 (4) ◽  
pp. 1935-1946
Author(s):  
K Y Lim ◽  
K Skalicka ◽  
B Koukalova ◽  
R A Volkov ◽  
R Matyasek ◽  
...  
Keyword(s):  
18S Rdna ◽  
Intergenic Spacer ◽  
Nucleolar Organizer ◽  
Nucleolar Organizer Regions ◽  
Dynamic Nature ◽  
Dynamic Changes ◽  
Nicotiana Tomentosiformis ◽  
Copy Numbers ◽  
Location Patterns

Abstract An ∼135-bp sequence called the A1/A2 repeat was isolated from the transcribed region of the 26-18S rDNA intergenic spacer (IGS) of Nicotiana tomentosiformis. Fluorescence in situ hybridization (FISH) and Southern blot analysis revealed its occurrence as an independent satellite (termed an A1/A2 satellite) outside of rDNA loci in species of Nicotiana section Tomentosae. The chromosomal location, patterns of genomic dispersion, and copy numbers of its tandemly arranged units varied between the species. In more distantly related Nicotiana species the A1/A2 repeats were found only at the nucleolar organizer regions (NOR). There was a trend toward the elimination of the A1/A2 satellite in N. tabacum (tobacco), an allotetraploid with parents closely related to the diploids N. sylvestris and N. tomentosiformis. This process may have already commenced in an S3 generation of synthetic tobacco. Cytosine residues in the IGS were significantly hypomethylated compared with the A1/A2 satellite. There was no clear separation between the IGS and satellite fractions in sequence analysis of individual clones and we found no evidence for CG suppression. Taken together the data indicate a dynamic nature of the A1/A2 repeats in Nicotiana genomes, with evidence for recurrent integration, copy number expansions, and contractions.

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