scholarly journals Allopatric chromosomal variation in Nematocharax venustus Weitzman, Menezes & Britski, 1986 (Actinopterygii: Characiformes) based on mapping of repetitive sequences

2016 ◽  
Vol 14 (2) ◽  
Author(s):  
Silvia B. Barreto ◽  
Marcelo B. Cioffi ◽  
Aline S. Medrado ◽  
André T. Silva ◽  
Paulo R. A. M. Affonso ◽  
...  
Keyword(s):  
Repetitive Dna ◽  
Repetitive Sequences ◽  
5S Rdna ◽  
Nucleolar Organizer ◽  
Life Cycles ◽  
Nucleolar Organizer Regions ◽  
Single Pair ◽  
Fluorochrome Staining ◽  
Chromosomal Banding

ABSTRACT Characiformes is the most cytogenetically studied group of freshwater Actinopterygii, but karyotypical data of several taxa remain unknown. This is the case of Nematocharax , regarded as a monotypic genus and characterized by marked sexual dimorphism. Therefore, we provide the first cytogenetic report of allopatric populations of Nematocharax venustus based on distinct methods of chromosomal banding and fluorescence in situ hybridization (FISH) with repetitive DNA probes (18S and 5S rDNA). The karyotype macrostructure was conserved in all specimens and populations, independently on sex, since they shared a diploid number (2n) of 50 chromosomes divided into 8m+26sm+14st+2a. The heterochromatin was mainly distributed at pericentromeric regions and base-specific fluorochrome staining revealed a single pair bearing GC-rich sites, coincident with nucleolar organizer regions (NORs). On the other hand, interpopulation variation in both number and position of repetitive sequences was observed, particularly in relation to 5S rDNA. Apparently, the short life cycles and restricted dispersal of small characins, such as N. venustus , might have favored the divergence of repetitive DNA among populations, indicating that this species might encompass populations with distinct evolutionary histories, which has important implications for conservation measures.

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.

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.

Chromosomal localization of two novel repetitive sequences isolated from the Chenopodium quinoa Willd. genome

Genome ◽  
2011 ◽  
Vol 54 (9) ◽  
pp. 710-717 ◽  
Author(s):  
B. Kolano ◽  
B.W. Gardunia ◽  
M. Michalska ◽  
A. Bonifacio ◽  
D. Fairbanks ◽  
...  
Keyword(s):  
In Situ Hybridization ◽  
Repetitive Dna ◽  
Dna Sequences ◽  
Repetitive Sequences ◽  
Chenopodium Quinoa ◽  
5S Rdna ◽  
Rrna Gene ◽  
Fish Analysis ◽  
Rdna Loci

The chromosomal organization of two novel repetitive DNA sequences isolated from the Chenopodium quinoa Willd. genome was analyzed across the genomes of selected Chenopodium species. Fluorescence in situ hybridization (FISH) analysis with the repetitive DNA clone 18–24J in the closely related allotetraploids C. quinoa and Chenopodium berlandieri Moq. (2n = 4x = 36) evidenced hybridization signals that were mainly present on 18 chromosomes; however, in the allohexaploid Chenopodium album L. (2n = 6x = 54), cross-hybridization was observed on all of the chromosomes. In situ hybridization with rRNA gene probes indicated that during the evolution of polyploidy, the chenopods lost some of their rDNA loci. Reprobing with rDNA indicated that in the subgenome labeled with 18–24J, one 35S rRNA locus and at least half of the 5S rDNA loci were present. A second analyzed sequence, 12–13P, localized exclusively in pericentromeric regions of each chromosome of C. quinoa and related species. The intensity of the FISH signals differed considerably among chromosomes. The pattern observed on C. quinoa chromosomes after FISH with 12–13P was very similar to GISH results, suggesting that the 12–13P sequence constitutes a major part of the repetitive DNA of C. quinoa.

scholarly journals Cytogenetic characterization of Aloysia virgata Ruiz and Pavan (Verbenaceae)

2009 ◽  
Vol 52 (4) ◽  
pp. 893-899
Author(s):  
Aline Dias Brandão ◽  
Lyderson Facio Viccini ◽  
Shirlei Maria Recco-Pimentel
Keyword(s):  
Interphase Nucleus ◽  
5S Rdna ◽  
Nucleolar Organizer ◽  
Nucleolar Organizer Regions ◽  
Meiotic Behavior ◽  
Meiotic Analysis ◽  
Chromosomal Pair ◽  
Cytogenetic Characterization

Since previous cytogenetic reports of Aloysia have only described the meiotic behavior and chromosomal number of some species, the aim of this work was to provide detailed cytogenetic description of Aloysia virgata that would contribute to the understanding of the taxonomical organization of the Verbenaceae. Aloysia virgata had a karyotype with 2n = 36 metacentric chromosomes, all with similar size. The large amount of heterochromatin seen after Giemsa staining was confirmed by C-banding. Four nucleolar organizer regions (NORs) were detected with an rDNA 45S probe in two homologous pairs and two sites of 5S rDNA located on one chromosomal pair were detected by fluorescence in situ hybridization. The interphase nucleus was classified as semi-reticulate. Meiotic analysis showed a normal chromosomal behavior, with 18 bivalents in some parts of prophase I and in metaphase I. The number of chromosomes, NORs and 5S rDNA segments did not exclude a possible polyploid origin.

scholarly journals Cytogenetic analysis of the neotropical spider Nephilengys cruentata (Araneomorphae, tetragnathidae): standard staining, NORs, C-bands and base-specific fluorochromes

2005 ◽  
Vol 65 (2) ◽  
pp. 193-202 ◽  
Author(s):  
D. Araújo ◽  
D. M. Cella ◽  
A. D. Brescovit
Keyword(s):  
Sex Determination ◽  
Banding Pattern ◽  
Constitutive Heterochromatin ◽  
Repetitive Sequences ◽  
Nucleolar Organizer ◽  
Pericentromeric Region ◽  
Banding Technique ◽  
Nucleolar Organizer Regions ◽  
Fluorochrome Staining ◽  
C Banding

The aim of this work is to characterize Nephilengys cruentata in relation to the diploid number, chromosome morphology, type of sex determination chromosome system, chromosomes bearing the Nucleolar Organizer Regions (NORs), C-banding pattern, and AT or GC repetitive sequences. The chromosome preparations were submitted to standard staining (Giemsa), NOR silver impregnation, C-banding technique, and base-specific fluorochrome staining. The analysis of the cells showed 2n = 24 and 2n = 26 chromosomes in the embryos, and 2n = 26 in the ovarian cells, being all the chromosomes acrocentric. The long arm of the pairs 1, 2 and 3 showed an extensive negative heteropycnotic area when the mitotic metaphases were stained with Giemsa. The sexual chromosomes did not show differential characteristics that allowed to distinguish them from the other chromosomes of the complement. Considering the diploid numbers found in N. cruentata and the prevalence of X1X2 sex determination chromosome system in Tetragnathidae, N. cruentata seems to possess 2n = 24 = 22 + X1X2 in the males, and 2n = 26 = 22 + X1X1X2X2 in the females. The pairs 1, 2 and 3 showed NORs which are coincident with the negative heteropycnotic patterns. Using the C-banding technique, the pericentromeric region of the chromosomes revealed small quantity or even absence of constitutive heterochromatin, differing of the C-banding pattern described in other species of spiders. In N. cruentata the fluorochromes DAPI/DA, DAPI/MM and CMA3/DA revealed that the constitutive heterochromatin is rich in AT bases and the NORs possess repetitive sequences of GC bases.

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.

Evolution of Bird Sex Chromosomes Narrated by Repetitive Sequences: Unusual W Chromosome Enlargement in Gallinula melanops (Aves: Gruiformes: Rallidae)

2019 ◽  
Vol 158 (3) ◽  
pp. 152-159 ◽  
Author(s):  
Ricardo J. Gunski ◽  
Rafael Kretschmer ◽  
Marcelo Santos de Souza ◽  
Ivanete de Oliveira Furo ◽  
Suziane A. Barcellos ◽  
...  
Keyword(s):  
Sex Chromosomes ◽  
18S Rdna ◽  
Organizer Region ◽  
Repetitive Sequences ◽  
Nucleolar Organizer Region ◽  
Molecular Cytogenetics ◽  
5S Rdna ◽  
Nucleolar Organizer ◽  
W Chromosome ◽  
Rdna Sites

Among birds, species with the ZZ/ZW sex determination system generally show significant differences in morphology and size between the Z and W chromosomes (with the W usually being smaller than the Z). In the present study, we report for the first time the karyotype of the spot-flanked gallinule (Gallinula melanops) by means of classical and molecular cytogenetics. The spot-flanked gallinule has 2n = 80 (11 pairs of macrochromosomes and 29 pairs of microchromosomes) with an unusual W chromosome that is larger than the Z. Besides being totally heterochromatic, it has a secondary constriction in its long arm corresponding to the nucleolar organizer region, as confirmed by both silver staining and mapping of 18S rDNA probes. This is an unprecedented fact among birds. Additionally, 18S rDNA sites were also observed in 6 microchromosomes, while 5S rDNA was found in just 1 microchromosomal pair. Seven out of the 11 used microsatellite sequences were found to be accumulated in microchromosomes, and 6 microsatellite sequences were found in the W chromosome. In addition to the involvement of heterochromatin and repetitive DNAs in the differentiation of the large W chromosome, the results also show an alternative scenario that highlights the plasticity that shapes the evolutionary history of bird sex chromosomes.

Variation in highly repetitive DNA composition of heterochromatin in rye studied by fluorescence in situ hybridization

Genome ◽  
1995 ◽  
Vol 38 (6) ◽  
pp. 1061-1069 ◽  
Author(s):  
A. Cuadrado ◽  
N. Jouve ◽  
C. Ceoloni
Keyword(s):  
In Situ Hybridization ◽  
Fluorescence In Situ Hybridization ◽  
Repetitive Dna ◽  
Dna Sequences ◽  
5S Rdna ◽  
Individual Identification ◽  
Highly Repetitive Dna ◽  
The Individual

The molecular characterization of heterochromatin in six lines of rye has been performed using fluorescence in situ hybridization (FISH). The highly repetitive rye DNA sequences pSc 119.2, pSc74, and pSc34, and the probes pTa71 and pSc794 containing the 25S–5.8S–18S rDNA (NOR) and the 5S rDNA multigene families, respectively, were used. This allowed the individual identification of all seven rye chromosomes and most chromosome arms in all lines. All varieties showed similar but not identical patterns. A standard in situ hybridization map was constructed following the nomenclature system recommended for C-bands. All FISH sites observed appeared to correspond well with C-band locations, but not all C-banding sites coincided with hybridization sites of the repetitive DNA probes used. Quantitative and qualitative differences between different varieties were found for in situ hybridization response at corresponding sites. Variation between plants and even between homologous chromosomes of the same plant was found in open-pollinated lines. In inbred lines, the in situ pattern of the homologues was practically identical and no variation between plants was detected. The observed quantitative and qualitative differences are consistent with a corresponding variation for C-bands detected both within and between cultivars.Key words: fluorescence in situ hybridization, repetitive DNA, rye, Secale cereale, polymorphism.

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.

scholarly journals Molecular cytogenetic studies in rubber, Hevea brasiliensis Muell. Arg. (Euphorbiaceae)

Genome ◽  
1998 ◽  
Vol 41 (3) ◽  
pp. 464-467 ◽  
Author(s):  
Andrew R Leitch ◽  
K Yoong Lim ◽  
Ilia J Leitch ◽  
Michelle O'Neill ◽  
MeeLen Chye ◽  
...  
Keyword(s):  
Genetic Mapping ◽  
Ribosomal Dna ◽  
Hevea Brasiliensis ◽  
Consensus Sequence ◽  
Molecular Cytogenetics ◽  
5S Rdna ◽  
Single Pair ◽  
Interphase Nuclei ◽  
Molecular Cytogenetic

This paper reports the start of a molecular cytogenetics programme targeting the genome of the angiosperm tree species Hevea brasiliensis Muell. Arg. (rubber, 2n = 36), a major world crop about whose genetics very little is known. A metaphase karyotype of rubber is presented. In situ hybidization with the probe pTa71 for ribosomal DNA (rDNA) shows that there are four sites of probe hybidization occurring on two pairs of chromosomes called chromosomes 6 and 7 carrying sites NOR-1 and NOR-2, respectively. An examination of meristematic interphase nuclei shows that all four loci have the potential to be partially decondensed at interphase, although in many nuclei one or more loci appear fully condensed and apparently inactive. The probe pXVI revealed a single pair of chromosomes carrying 5S rDNA. The probes pTa71 and pXVI provide cytogenetic markers for three pairs of chromosomes that will be of use in genetic mapping programmes. The rubber chromosomes also have telomere sequences that hybridize with the Arabidopsis consensus sequence TTTAGGG. With the exception of the satellite region containing rDNA, which fluoresces brightly with chromomycin A3, fluorescence banding showed that there is no strong demarcation of the genome into GC- and AT-rich regions, as occurs in mammalian genomes.Key words: rubber, Hevea, genetic mapping, cytogenetics, ribosomal DNA, rDNA fluorescence banding.

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