Banding in mitotic chromosomes of Brassica campestris var. pekinensis with a trypsin–Giemsa method

Genome ◽  
1992 ◽  
Vol 35 (5) ◽  
pp. 899-901 ◽  
Author(s):  
Soryu Nishibayasahi
Keyword(s):  
Banding Pattern ◽  
Brassica Campestris ◽  
Chromosome Size ◽  
Mitotic Chromosomes ◽  
Metaphase Chromosomes ◽  
Secondary Constrictions

In Brassica campestris var. pekinensis cv. CR-strong, the karyotype comprised 12 median, 6 submedian, and 2 sub-terminal chromosomes. Secondary constrictions were observed in the two subterminal chromosomes. Banding pattern appeared very clearly in metaphase chromosomes with a trypsin–Giemsa method. It was possible to classify the chromosomes into 10 types (C1–C10), based on the chromosome size, shape, and banding pattern.Key words: Brassica campestris var. pekinensis, mitotic chromosomes, G-banding.

scholarly journals Chromosome disentanglement driven via optimal compaction of loop-extruded brush structures

2019 ◽  
Author(s):  
Sumitabha Brahmachari ◽  
John F. Marko
Keyword(s):  
Expression Patterns ◽  
Polymer Brush ◽  
Chromosome Size ◽  
Mitotic Chromosomes ◽  
Mechanical Stiffness ◽  
Structural Reorganization ◽  
Metaphase Chromosomes ◽  
Topo Ii ◽  
Strand Passage

AbstractEukaryote cell division features a chromosome compaction-decompaction cycle that is synchronized with their physical and topological segregation. It has been proposed that lengthwise compaction of chromatin into mitotic chromosomes via loop extrusion underlies the compaction-segregation/resolution process. We analyze this disentanglement scheme via considering the chromosome to be a succession of DNA/chromatin loops - a polymer “brush” - where active extrusion of loops controls the brush structure. Given topoisomerase (TopoII)-catalyzed topology fluctuations, we find that inter-chromosome entanglements are minimized for a certain “optimal” loop that scales with the chromosome size. The optimal loop organization is in accord with experimental data across species, suggesting an important structural role of genomic loops in maintaining a less entangled genome. Application of the model to the interphase genome indicates that active loop extrusion can maintain a level of chromosome compaction with suppressed entanglements; the transition to the metaphase state requires higher lengthwise compaction, and drives complete topological segregation. Optimized genomic loops may provide a means for evolutionary propagation of gene-expression patterns while simultaneously maintaining a disentangled genome. We also find that compact metaphase chromosomes have a densely packed core along their cylindrical axes that explains their observed mechanical stiffness. Our model connects chromosome structural reorganization to topological resolution through the cell cycle, and highlights a mechanism of directing Topo-II mediated strand passage via loop extrusion driven lengthwise compaction.

C-banded karyotypes of Brassica campestris, B. oleracea, and B. napus

Genome ◽  
1992 ◽  
Vol 35 (4) ◽  
pp. 583-589 ◽  
Author(s):  
Majlis Olin-Fatih ◽  
W. K. Heneen
Keyword(s):  
Banding Pattern ◽  
Chromosome Pair ◽  
Brassica Campestris ◽  
Brassica Species ◽  
Conclusive Evidence ◽  
Metaphase Chromosomes ◽  
Late Prophase ◽  
Nucleolar Chromosome ◽  
Centromeric Position ◽  
Similar Banding Pattern

The chromosome complements of three Brassica species, namely B. campestris (2n = 20), B. oleracea (2n = 18), and B. napus (2n = 38), were studied using the air-dry method and C-banding. Karyotypes and ideograms of late prophase chromosomes were constructed, since contracted metaphase chromosomes were generally not suitable for this purpose. The three species generally had a similar banding pattern, manifested in the presence of a centromeric C-band in all chromosomes and heterochromatic knobs at the telomeric end of some chromosomes. The centromeric C-bands were more pronounced in B. campestris than in B. oleracea. Depending on the centromeric position, the chromosomes were grouped into median, submedian, subterminal, and terminal types. All chromosome pairs were morphologically distinguishable. Only one nucleolar chromosome pair, with heterochromatic satellites, was observed in each species. When compared, it was possible to distinguish chromosomes of both B. campestris and B. oleracea type in B. napus, but conclusive evidence as to the origin of all chromosome pairs in B. napus was not at hand.Key words: Brassica, chromosomes, late prophase, C-bands, knob structures, karyotypes, idiograms.

scholarly journals Chromosome disentanglement driven via optimal compaction of loop-extruded brush structures

2019 ◽  
Vol 116 (50) ◽  
pp. 24956-24965 ◽  
Author(s):  
Sumitabha Brahmachari ◽  
John F. Marko
Keyword(s):  
Expression Patterns ◽  
Polymer Brush ◽  
Mitotic Chromosomes ◽  
Mechanical Stiffness ◽  
Structural Reorganization ◽  
Metaphase Chromosomes ◽  
Dna Topoisomerase ◽  
Topo Ii ◽  
Strand Passage

Eukaryote cell division features a chromosome compaction–decompaction cycle that is synchronized with their physical and topological segregation. It has been proposed that lengthwise compaction of chromatin into mitotic chromosomes via loop extrusion underlies the compaction-segregation/resolution process. We analyze this disentanglement scheme via considering the chromosome to be a succession of DNA/chromatin loops—a polymer “brush”—where active extrusion of loops controls the brush structure. Given type-II DNA topoisomerase (Topo II)-catalyzed topology fluctuations, we find that interchromosome entanglements are minimized for a certain “optimal” loop that scales with the chromosome size. The optimal loop organization is in accord with experimental data across species, suggesting an important structural role of genomic loops in maintaining a less entangled genome. Application of the model to the interphase genome indicates that active loop extrusion can maintain a level of chromosome compaction with suppressed entanglements; the transition to the metaphase state requires higher lengthwise compaction and drives complete topological segregation. Optimized genomic loops may provide a means for evolutionary propagation of gene-expression patterns while simultaneously maintaining a disentangled genome. We also find that compact metaphase chromosomes have a densely packed core along their cylindrical axes that explains their observed mechanical stiffness. Our model connects chromosome structural reorganization to topological resolution through the cell cycle and highlights a mechanism of directing Topo II-mediated strand passage via loop extrusion-driven lengthwise compaction.

Cytogenetic studies on Sauria (Reptilia). I. Mitotic chromosomes of the Agamidae

1988 ◽  
Vol 9 (3) ◽  
pp. 301-310 ◽  
Author(s):  
E. Solleder ◽  
M. Schmid
Keyword(s):  
Chromosome Number ◽  
Chromosome Morphology ◽  
Mitotic Chromosomes ◽  
Metaphase Chromosomes ◽  
Banding Patterns ◽  
The Family ◽  
Telocentric Chromosomes ◽  
Cytogenetic Studies ◽  
Pericentric Inversions ◽  
Dna Organization

The karotypes of nine species of the family Agamidae were analyzed with various banding techniques and conventional cytogenetic stainings. Whereas the examined species of the genera Calotes and Leiolepis exhibit conservative karyotypes, the chromosome number and chromosome morphology varies considerably within the genus Agama. This is attributed to centric fusions between telocentric chromosomes and pericentric inversions within the chromosomes. None of the species demonstrated multiple quinacrine banding patterns in the euchromatic segments of the metaphase chromosomes. This is probably due to the special DNA organization in these organisms.

NUCLEOLAR ORGANIZER REGIONS IN THE RABBIT (ORYCTOLAGUS CUNICULUS) AS SHOWN BY SILVER STAINING

1978 ◽  
Vol 20 (3) ◽  
pp. 377-382 ◽  
Author(s):  
Patricia A. Martin-Deleon ◽  
Dorene L. Petrosky ◽  
M. Eileen Fleming
Keyword(s):  
New Zealand ◽  
Silver Staining ◽  
Oryctolagus Cuniculus ◽  
Nucleolar Organizer ◽  
Nucleolar Organizer Regions ◽  
Telomeric Region ◽  
Metaphase Chromosomes ◽  
Domestic Rabbit ◽  
Silver Precipitation ◽  
Secondary Constrictions

Nucleolar organizer regions (NOR's) were demonstrated in metaphase chromosomes of the domestic rabbit, Oryctolagus cuniculus (L.) (New Zealand white strain) using silver staining. Sequential quinacrine banding and a modification of the Ag-AS silver precipitation technique with duplicate photography allowed identification of silver staining NOR's on the short arms of chromosomes 13, 16, and 20, as well as the telomeric region of the long arms of number 21 in some cells. Chromosomes 13, 16 and 20 all have subterminal to terminal centromeres, often showed satellites and secondary constrictions, and were sometimes involved in associations.

scholarly journals Mouse satellite DNA, centromere structure, and sister chromatid pairing.

1986 ◽  
Vol 103 (4) ◽  
pp. 1145-1151 ◽  
Author(s):  
L M Lica ◽  
S Narayanswami ◽  
B A Hamkalo
Keyword(s):  
Electron Microscopy ◽  
Sister Chromatid ◽  
Satellite Dna ◽  
Marker Chromosome ◽  
Restriction Enzymes ◽  
Centromeric Heterochromatin ◽  
Mitotic Chromosomes ◽  
Metaphase Chromosomes ◽  
Sister Chromatids ◽  
Mouse Satellite Dna

The experiments described were directed toward understanding relationships between mouse satellite DNA, sister chromatid pairing, and centromere function. Electron microscopy of a large mouse L929 marker chromosome shows that each of its multiple constrictions is coincident with a site of sister chromatid contact and the presence of mouse satellite DNA. However, only one of these sites, the central one, possesses kinetochores. This observation suggests either that satellite DNA alone is not sufficient for kinetochore formation or that when one kinetochore forms, other potential sites are suppressed. In the second set of experiments, we show that highly extended chromosomes from Hoechst 33258-treated cells (Hilwig, I., and A. Gropp, 1973, Exp. Cell Res., 81:474-477) lack kinetochores. Kinetochores are not seen in Miller spreads of these chromosomes, and at least one kinetochore antigen is not associated with these chromosomes when they were subjected to immunofluorescent analysis using anti-kinetochore scleroderma serum. These data suggest that kinetochore formation at centromeric heterochromatin may require a higher order chromatin structure which is altered by Hoechst binding. Finally, when metaphase chromosomes are subjected to digestion by restriction enzymes that degrade the bulk of mouse satellite DNA, contact between sister chromatids appears to be disrupted. Electron microscopy of digested chromosomes shows that there is a significant loss of heterochromatin between the sister chromatids at paired sites. In addition, fluorescence microscopy using anti-kinetochore serum reveals a greater inter-kinetochore distance than in controls or chromosomes digested with enzymes that spare satellite. We conclude that the presence of mouse satellite DNA in these regions is necessary for maintenance of contact between the sister chromatids of mouse mitotic chromosomes.

scholarly journals Aurora A kinase phosphorylates Hec1 to regulate metaphase kinetochore–microtubule dynamics

2017 ◽  
Vol 217 (1) ◽  
pp. 163-177 ◽  
Author(s):  
Keith F. DeLuca ◽  
Amanda Meppelink ◽  
Amanda J. Broad ◽  
Jeanne E. Mick ◽  
Olve B. Peersen ◽  
...  
Keyword(s):  
Chromosome Segregation ◽  
Microtubule Dynamics ◽  
Aurora B ◽  
Aurora A Kinase ◽  
Aurora A ◽  
Tail Domain ◽  
Mitotic Chromosomes ◽  
Metaphase Chromosomes ◽  
Mitotic Kinases ◽  
Microtubule Attachment

Precise regulation of kinetochore–microtubule attachments is essential for successful chromosome segregation. Central to this regulation is Aurora B kinase, which phosphorylates kinetochore substrates to promote microtubule turnover. A critical target of Aurora B is the N-terminal “tail” domain of Hec1, which is a component of the NDC80 complex, a force-transducing link between kinetochores and microtubules. Although Aurora B is regarded as the “master regulator” of kinetochore–microtubule attachment, other mitotic kinases likely contribute to Hec1 phosphorylation. In this study, we demonstrate that Aurora A kinase regulates kinetochore–microtubule dynamics of metaphase chromosomes, and we identify Hec1 S69, a previously uncharacterized phosphorylation target site in the Hec1 tail, as a critical Aurora A substrate for this regulation. Additionally, we demonstrate that Aurora A kinase associates with inner centromere protein (INCENP) during mitosis and that INCENP is competent to drive accumulation of the kinase to the centromere region of mitotic chromosomes. These findings reveal that both Aurora A and B contribute to kinetochore–microtubule attachment dynamics, and they uncover an unexpected role for Aurora A in late mitosis.

Karyotype and C-banding pattern of mitotic chromosomes in alfalfa, Medicago sativa L.

1995 ◽  
Vol 114 (5) ◽  
pp. 451-453 ◽  
Author(s):  
E. Falistocco ◽  
M. Falcinelli ◽  
F. Veronesi
Keyword(s):  
Medicago Sativa ◽  
Banding Pattern ◽  
Mitotic Chromosomes ◽  
C Banding ◽  
Medicago Sativa L

Stochastic chromatin packing of 3D mitotic chromosomes revealed by coherent X-rays

2021 ◽  
Vol 118 (46) ◽  
pp. e2109921118
Author(s):  
Daeho Sung ◽  
Chan Lim ◽  
Masatoshi Takagi ◽  
Chulho Jung ◽  
Heemin Lee ◽  
...  
Keyword(s):  
Information Transfer ◽  
3D Structure ◽  
Three Dimensional ◽  
Information Storage ◽  
Atomic Scale ◽  
Scaling Analysis ◽  
X Rays ◽  
Mitotic Chromosomes ◽  
Metaphase Chromosomes ◽  
Chromatin Packing

DNA molecules are atomic-scale information storage molecules that promote reliable information transfer via fault-free repetitions of replications and transcriptions. Remarkable accuracy of compacting a few-meters-long DNA into a micrometer-scale object, and the reverse, makes the chromosome one of the most intriguing structures from both physical and biological viewpoints. However, its three-dimensional (3D) structure remains elusive with challenges in observing native structures of specimens at tens-of-nanometers resolution. Here, using cryogenic coherent X-ray diffraction imaging, we succeeded in obtaining nanoscale 3D structures of metaphase chromosomes that exhibited a random distribution of electron density without characteristics of high-order folding structures. Scaling analysis of the chromosomes, compared with a model structure having the same density profile as the experimental results, has discovered the fractal nature of density distributions. Quantitative 3D density maps, corroborated by molecular dynamics simulations, reveal that internal structures of chromosomes conform to diffusion-limited aggregation behavior, which indicates that 3D chromatin packing occurs via stochastic processes.

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