Tandem Repeat-Based Probes Support the Loop Model of Pericentromere Packing

2021 ◽  
pp. 1-10
Author(s):  
Nadezhda G. Ivanova ◽  
Dmitrii Ostromyshenskii ◽  
Olga Podgornaya
Keyword(s):  
Sus Scrofa ◽  
Tandem Repeats ◽  
Centromeric Region ◽  
Constitutive Heterochromatin ◽  
Chinese Hamster ◽  
Loop Model ◽  
Spermatogenic Cells ◽  
Meiotic Chromosomes ◽  
Main Component ◽  
Chromosome Regions

Constitutive heterochromatin is the most mysterious part of the eukaryotic genome. It forms vital chromosome regions such as the centromeric and the pericentromeric ones. The main component of heterochromatic regions are tandem repeats (TR), and their specific organization complicates assembly, annotation, and mapping of these regions. Unannotated and unmapped TR arrays are still present in database contigs. In this study, we used a set of TR in the genomes of the pig (Sus scrofa) and the Chinese hamster (Cricetulus griseus) identified with the help of bioinformatics techniques and determined the specificity of the designed probes. The signal of the 4 pig TR probes in spermatogenic cells was often ring-shaped, especially in primary spermatocytes. The rings were located in the regions relatively weakly stained with DAPI. The unique assembly of the centromeric region was traced using the hamster meiotic chromosomes. The probe specific to chromosome 5 was used. Two signals, arranged as rings, were seen at the pachytene stage, similar to those in the pig spermatogenic cells. In the spermatogenic cells of both pig and hamster, the rings appeared on the chromosomes with pericentromeric TR probes. Our observations support the loop model of the centromeric region, the size of the loops being about 50 kb.

Tandem Repeats in the Genome of Sus scrofa, Their Localization on Chromosomes and in the Spermatogenic Cell Nuclei

2019 ◽  
Vol 55 (7) ◽  
pp. 835-846
Author(s):  
N. G. Ivanova ◽  
V. N. Stefanova ◽  
D. I. Ostromyshenskii ◽  
O. I. Podgornaya
Keyword(s):  
Sus Scrofa ◽  
Tandem Repeats ◽  
Spermatogenic Cell ◽  
Cell Nuclei

CHARACTERIZATION OF HUMAN CHROMOSOMAL CONSTITUTIVE HETEROCHROMATIN

2020 ◽  
Vol 53 (02) ◽  
pp. 08-11
Author(s):  
Aytakin Hasanova
Keyword(s):  
Satellite Dna ◽  
Constitutive Heterochromatin ◽  
Chromosome Breakage ◽  
Centromeric Heterochromatin ◽  
Crossing Over ◽  
Alpha Satellite ◽  
Alpha Satellite Dna ◽  
Chromosome Regions ◽  
Chromosome Disjunction

Heterochromatin of centromeric chromosome regions contains late replicating, largely repetitive DNA. It is suggested that heterochromatin participates in chromosome pairing, crossing-over and in chromosome disjunction control (1,3). Centromeric heterochromatin, a variety of heterochromatin, is a tightly packed form of DNA.Centromeric heterochromatin is a constituent in the formation ofactive centromeres in most higher-order organisms; the domain exists on both mitotic and interphase chromosomes. (4,5,6,8) Centromeric heterochromatin is usually formed on alpha satellite DNA in humans; however, there have been cases where centric heterochromatin and centromeres have formed on originally euchromatin domains lacking alpha satellite DNA; this usually happens as a result of a chromosome breakage event and the formed centromere is called a neocentromere.

Human ribosomal DNA fragments amplified in hamster cells are transcribed only by RNA polymerase II and are not silver stained

1987 ◽  
Vol 7 (3) ◽  
pp. 1289-1292
Author(s):  
V N Dhar ◽  
D A Miller ◽  
A B Kulkarni ◽  
O J Miller
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Ribosomal Dna ◽  
Chinese Hamster ◽  
Rna Polymerase I ◽  
Rrna Gene ◽  
Methotrexate Resistance ◽  
Selection For ◽  
Polymerase I ◽  
Chromosome Regions

Cloned human rRNA gene fragments that included the promoter region were introduced into Chinese hamster dihydrofolate reductase-deficient (dhfr-) cells by cotransformation with a dhfr minigene and amplified by selection for methotrexate resistance. The human ribosomal DNA was transcribed by RNA polymerase II, not RNA polymerase I or III. The metaphase chromosome regions containing the transcriptionally active human ribosomal DNA failed to show silver staining.

scholarly journals Telomeres act autonomously in maize to organize the meiotic bouquet from a semipolarized chromosome orientation

2002 ◽  
Vol 157 (2) ◽  
pp. 231-242 ◽  
Author(s):  
Peter M. Carlton ◽  
W. Zacheus Cande
Keyword(s):  
Large Scale ◽  
Nuclear Periphery ◽  
Small Region ◽  
Homologous Chromosomes ◽  
Cis Acting ◽  
Chromosome Architecture ◽  
Meiotic Chromosomes ◽  
Ring Chromosomes ◽  
Bouquet Stage ◽  
Chromosome Regions

During meiosis, chromosomes undergo large-scale reorganization to allow pairing between homologues, which is necessary for recombination and segregation. In many organisms, pairing of homologous chromosomes is accompanied, and possibly facilitated, by the bouquet, the clustering of telomeres in a small region of the nuclear periphery. Taking advantage of the cytological accessibility of meiosis in maize, we have characterized the organization of centromeres and telomeres throughout meiotic prophase. Our results demonstrate that meiotic centromeres are polarized prior to the bouquet stage, but that this polarization does not contribute to bouquet formation. By examining telocentric and ring chromosomes, we have tested the cis-acting requirements for participation in the bouquet. We find that: (a) the healed ends of broken chromosomes, which contain telomere repeats, can enter the bouquet; (b) ring chromosomes enter the bouquet, indicating that terminal position on a chromosome is not necessary for telomere sequences to localize to the bouquet; and (c) beginning at zygotene, the behavior of telomeres is dominant over any centromere-mediated chromosome behavior. The results of this study indicate that specific chromosome regions are acted upon to determine the organization of meiotic chromosomes, enabling the bouquet to form despite large-scale changes in chromosome architecture.

scholarly journals Dynamic plasticity of large-scale chromatin structure revealed by self-assembly of engineered chromosome regions

2010 ◽  
Vol 190 (5) ◽  
pp. 761-776 ◽  
Author(s):  
Paul Sinclair ◽  
Qian Bian ◽  
Matt Plutz ◽  
Edith Heard ◽  
Andrew S. Belmont
Keyword(s):  
Self Assembly ◽  
Large Scale ◽  
Tandem Repeats ◽  
Es Cells ◽  
Embryonic Stem ◽  
Bacterial Artificial Chromosomes ◽  
Artificial Chromosomes ◽  
Lac Operator ◽  
Chromatin Folding ◽  
Chromosome Regions

Interphase chromatin compaction well above the 30-nm fiber is well documented, but the structural motifs underlying this level of chromatin folding remain unknown. Taking a reductionist approach, we analyzed in mouse embryonic stem (ES) cells and ES-derived fibroblasts and erythroblasts the folding of 10–160-megabase pair engineered chromosome regions consisting of tandem repeats of bacterial artificial chromosomes (BACs) containing ∼200 kilobases of mammalian genomic DNA tagged with lac operator (LacO) arrays. Unexpectedly, linear mitotic and interphase chromatid regions formed from noncontiguously folded DNA topologies. Particularly, in ES cells, these model chromosome regions self-organized with distant sequences segregating into functionally distinct, compact domains. Transcriptionally active and histone H3K27me3-modified regions positioned toward the engineered chromosome subterritory exterior, with LacO repeats and the BAC vector backbone localizing within an H3K9me3, HP1-enriched core. Differential compaction of Dhfr and α- and β-globin transgenes was superimposed on dramatic, lineage-specific reorganization of large-scale chromatin folding, demonstrating a surprising plasticity of large-scale chromatin organization.

Constitutive heterochromatin distribution in pig (Sus scrofa) chromosomes

Caryologia ◽  
1998 ◽  
Vol 51 (1) ◽  
pp. 65-72 ◽  
Author(s):  
G.P. Di Meo ◽  
A. Perucatti ◽  
L. Ferrara ◽  
M. Palazzo ◽  
D. Matassino ◽  
...  
Keyword(s):  
Sus Scrofa ◽  
Constitutive Heterochromatin

CONSTITUTIVE HETEROCHROMATIN IN MOUSE CHROMOSOMES TREATED WITH TRYPSIN

1973 ◽  
Vol 15 (1) ◽  
pp. 1-7 ◽  
Author(s):  
M. Ray ◽  
J. L. Hamerton
Keyword(s):  
Constitutive Heterochromatin ◽  
Chinese Hamster ◽  
Chinese Hamster Cell ◽  
Trypsin Digestion ◽  
Drying Methods ◽  
Hybrid Cells ◽  
Digestion Method ◽  
Marker Chromosomes ◽  
Different Origins ◽  
Secondary Constrictions

Chromosome preparations from three sublines of mouse L-cells (A9, B82 L60) were made by conventional air-drying methods and the slides treated both by trypsin digestion and the C-banding methods, in order to investigate and compare the distribution of constitutive heterochromatin in these cells. Comparisons were also made with human and Chinese hamster cells. The mouse heterochromatic sites observed, including the interstitial sites found on the marker chromosomes, were similar for each line irrespective of the method used. The interstitial heterochromatic sites in the marker chromosomes 1 and 3 correspond to the locations of the secondary constrictions. The trypsin digestion method reveals the sites of constitutive heterochromatin in mouse chromosomes, but not in human or Chinese hamster chromosomes. All mouse chromosomes could be distinguished from those of Chinese hamster in the hybrid cells between mouse and Chinese hamster cell lines. The method is simple to use and therefore will facilitate the identification of mouse chromosomes within and between the cell populations of different origins and within cell hybrids.

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