scholarly journals Ultrastructural aspects of chromatin elimination in hybrid embryos of Hordeum

2014 ◽  
Vol 52 (3-4) ◽  
pp. 197-200
Author(s):  
Krystyna Idzikowska ◽  
Fortunat Młodzianowski
Keyword(s):  
Interphase Nuclei ◽  
Chromatin Elimination

Chromatin elimination was observed in hybrid embryos of <em>Hordeum</em> as incorporation of single chromosomes into tiny vacuoles-lysomes and as fragmentation of interphase nuclei: The latter process led mostly to the formation of micronuclei which underwent gradual degradation.

scholarly journals Nuclear morphology, polyploidy, and chromatin elimination in tissue culture of Allium fistulosum L.

2011 ◽  
Vol 72 (1) ◽  
pp. 11-17 ◽  
Author(s):  
Andrzej Joachimiak ◽  
Tomasz Ilnicki
Keyword(s):  
Tissue Culture ◽  
Ploidy Level ◽  
Root Tip ◽  
Allium Fistulosum ◽  
Nuclear Morphology ◽  
Cell Nuclei ◽  
Interphase Nuclei ◽  
Polyploid Cells ◽  
Chromatin Elimination

<p>The morphology of cell nuclei in callus obtained from root-tip meristems of <em>Allium fistulosum</em> L. (Monocotyledoneae, Alliaceae) was analysed. The most interesting phenomena observed in long-term callus culture were the different mechanisms of cell polyploidization, enlargement of telomeric segments of heterochromatin, and extensive chromatin elimination, associated with instability of nuclei size and DNA content.</p><p>Protruding heterochromatin "spikes" were observed on the surface of some di- and polyploid nuclei. The presence of these spikes was connected with the formation of small heterochromatic micronuclei frequently found in the cytoplasm. It is suggested that these micronuclei are produced by direct elimination of heterochromatin from the interphase nuclei.</p><p>Polyploid cells accumulated with each successive cell collection. The ploidy level attained by highly polyploid cells was 15C-220C. The shape of the nuclei and heterochromatin distribution suggest that polyploid nuclei in <em>A. fistulosum</em> tissue culture are produced by endoreduplication and by restitution cycles.</p>

scholarly journals Boon and Bane of DNA Double-Strand Breaks

2021 ◽  
Vol 22 (10) ◽  
pp. 5171
Author(s):  
Ingo Schubert
Keyword(s):  
Negative Impact ◽  
Biological Effects ◽  
Double Strand Breaks ◽  
Immunoglobulin Gene ◽  
Dna Double Strand Breaks ◽  
Endogenous Factors ◽  
Strand Breaks ◽  
Chromatin Elimination ◽  
Evolutionary Consequences ◽  
Cell Lethality

DNA double-strand breaks (DSBs), interrupting the genetic information, are elicited by various environmental and endogenous factors. They bear the risk of cell lethality and, if mis-repaired, of deleterious mutation. This negative impact is contrasted by several evolutionary achievements for DSB processing that help maintaining stable inheritance (correct repair, meiotic cross-over) and even drive adaptation (immunoglobulin gene recombination), differentiation (chromatin elimination) and speciation by creating new genetic diversity via DSB mis-repair. Targeted DSBs play a role in genome editing for research, breeding and therapy purposes. Here, I survey possible causes, biological effects and evolutionary consequences of DSBs, mainly for students and outsiders.

Somatic pairing of chromosome 1 centromeres in interphase nuclei of human cerebellum

1989 ◽  
Vol 83 (3) ◽  
pp. 231-234 ◽  
Author(s):  
E. P. J. Arnoldus ◽  
A. C. B. Peters ◽  
G. T. A. M. Bots ◽  
A. K. Raap ◽  
M. van der Ploeg
Keyword(s):  
Chromosome 1 ◽  
Interphase Nuclei ◽  
Human Cerebellum ◽  
Somatic Pairing

Diagnosis of aneuploidy by in situ hybridization: Analysis of interphase nuclei

1991 ◽  
Vol 112 (4) ◽  
pp. 1480-1483 ◽  
Author(s):  
S. G. Vorsanova ◽  
Yu. B. Yurov ◽  
G. V. Deryagin ◽  
I. V. Solov'ev ◽  
G. A. Bytenskaya
Keyword(s):  
In Situ Hybridization ◽  
Hybridization Analysis ◽  
Interphase Nuclei

Continuous DNA replication in the nucleus of the dinoflagellate Prorocentrum micans (Ehrenberg)

1977 ◽  
Vol 27 (1) ◽  
pp. 81-90
Author(s):  
S.A. Filfilan ◽  
D.C. Sigee
Keyword(s):  
Electron Microscope ◽  
Dna Synthesis ◽  
Nuclear Dna ◽  
Continuous Process ◽  
Prorocentrum Micans ◽  
Interphase Nuclei ◽  
Electron Microscope Autoradiography ◽  
Dividing Cells ◽  
High Degree ◽  
Very High

The uptake of tritiated thymine into cells of a heterogeneous population of Prorocentrum micans was investigated using light-microscope and electron-microscope autoradiography. Specificity of thymine uptake into DNA was demonstrated by the specific removal of label from wax-embedded material using DNase and by the high degree of localization of nuclear label to chromosomes in the electron-microscope autoradiographs. All nuclei, including both dividing and non-dividing cells, showed a substantial uptake of label, indicating that nuclear DNA synthesis in Prorocentrum micans is a continuous process. The level of DNA synthesis does show considerable variation, however, with very high levels in some interphase nuclei. The continuous replication of nuclear DNA provides further evidence of dinoflagellate affinity to the prokaryotes, and indicates that Prorocentrum micans is a very primitive eukaryote cell.

Fine structure of the haplosporidan Kernstab, a persistent, intranuclear mitotic apparatus

1975 ◽  
Vol 18 (2) ◽  
pp. 327-346
Author(s):  
F.O. Perkins
Keyword(s):  
Fine Structure ◽  
Nuclear Envelope ◽  
Light Microscope ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Interphase Nuclei ◽  
Mitotic Apparatus ◽  
Pole Body

The fine structure of the haplosporidan mitotic apparatus is described from observations of plasmodial nuclei of Minchinia nelsoni, M. costalis, Minchinia sp., and Urosporidium crescens. The apparatus, which is the Kernstab of light-microscope studies, consists of a bundle of microtubules terminating in a spindle pole body (SPB) at each end of the bundle. A few microtubules extend from SPB to SPB, but most either extend from an SPB and terminate in the nucleoplasm or lie in the nucleoplasm, free of either SPB. The bundle lengthens during mitosis, increasing the SPB-to-SPB distance by a factor of 2 to 3 as compared to interphase nuclei. SPBs are not in contact with the nuclear envelope, being found always in the nucleoplasm which is delimited by the nuclear envelope throughout mitosis. The mitotic apparatus is persistent through interphase, at least in a form which is not significantly different from that found in mitotic nuclei.

The Synthesis and Migration of Nuclear Proteins during Mitosis and differentiation of Cells in Rats

1965 ◽  
Vol s3-106 (75) ◽  
pp. 229-240
Author(s):  
R. T. SIMS
Keyword(s):  
Granular Cell ◽  
Nuclear Proteins ◽  
Photographic Emulsion ◽  
Metaphase Chromosomes ◽  
Interphase Nuclei ◽  
Cell Layers ◽  
The Difference ◽  
Mitotic Figures ◽  
And Migration ◽  
Silver Grains

Hooded rats were given an intraperitoneal injection of 3H-tyrosine, and killed in pairs 10 min, 30 min, 12 h, 36 h, 7 days, and 30 days later. A piece of skin with white growing hair, and the tongue, were taken from each animal and radioautographs were prepared. Silver grains were counted over whole nuclei and whole mitotic figures of the germinal cells and whole nuclei of differentiating cells of both tissues. It was found that the interphase nuclei have significantly more silver grains over them than the chromosomes at all stages of mitosis and there are virtually no grains over metaphase, anaphase, and early telophase chromosomes in both tissues of all the animals killed up to 36 h after the injection. The difference between the grain counts over the interphase nuclei and the chromosomes of dividing cells is at least 20-fold at 30 min in the hair matrix, at least 5-fold at 30 min in the tongue and at 36 h in both tissues. It was established that the differences observed between the radioactivities of the nuclei and chromosomes of mitotic figures are real from estimates of: the radioactivity of the cell cytoplasm, volumes of the metaphase chromosomes and interphase nuclei within 1µ of the photographic emulsion, and the volumes of cytoplasm separating the photographic emulsion and these structures. No protein synthesis was demonstrable in the chromosomes during metaphase, anaphase, and early telophase. Nuclear proteins leave the chromosomes during prophase and prometaphase and return to the nucleus during late telophase. The cells in the matrix and upper bulb of the growing hair follicle and those in the germinal, prickle, and granular cell layers of the tongue are in different functional states; 30 min after injection of 3H-tyrosine they have different amounts of it in their nuclear proteins. It is suggested that the amount incorporated into each nucleus is related to the rate at which proteins are being synthesized by the cell.

scholarly journals Characterization of eight species of Aloe (Asphodelaceae) from the nucleolar organizing region

Rodriguésia ◽  
2018 ◽  
Vol 69 (2) ◽  
pp. 363-372
Author(s):  
Ysbelia Sánchez-G ◽  
María B. Raymúndez ◽  
José Imery ◽  
M. Cristina Acosta ◽  
Eduardo Moscone
Keyword(s):  
Subtelomeric Region ◽  
Interphase Nuclei ◽  
Nucleolar Organizing Region ◽  
Subtelomeric Regions

Abstract Nucleolar organizing region of eight species of Aloe was analyzed in somatic metaphases and interphase nuclei. All species showed a uniform 2n=14, with eight large chromosomes and six small chromosomes. Satellites were observed on the long arm of one or two pairs of large chromosomes and/or on the short arm of one of the small pairs. The silver-stained nucleolus organizing regions were located on the subtelomeric region of the long arm of one or two pairs of large chromosomes, except for Aloe dichotoma and Aloe maculata, which the AgNORs were located at a short arm of one of their small chromosomes. In most studied species, the active AgNOR number was four. However, this number changing from one to eight. For all species, the interphase number of nucleoli can be one or two, while, in Aloe excelsa, this number can be changing from one to eight. Polymorphism of active AgNORs and the number of interphase nucleoli were revealed, except for Aloe petricola, which active AgNORs were located only in the subtelomeric regions at the long arm of one of the L2 chromosomes, as well as in the L4 pair, which is agrément with the maximum number (three) of interphase nucleoli.

Nuclear proteins of quiescent and mitotically active cells in shoot meristems of Tradescantia paludosa

1974 ◽  
Vol 52 (9) ◽  
pp. 2049-2053 ◽  
Author(s):  
R. S. Tobin ◽  
Kyu-Byung Yun ◽  
J. M. Naylor
Keyword(s):  
Nuclear Proteins ◽  
Zone Of Inhibition ◽  
Interphase Nuclei ◽  
Lateral Buds ◽  
Dye Binding ◽  
Tradescantia Paludosa ◽  
Shoot Meristems

In inhibited lateral buds of Tradescantia paludosa, interphase nuclei in the apical zone of inhibition contain higher levels of arginine per unit DNA than those of mitotically active cells in interphase or prophase. Supplementary dye-binding experiments suggest that this reflects a corresponding difference between the composition of the histone complement of chromatin in the two cells populations. The possible implications of this phenomenon are discussed.

Sign in / Sign up

Export Citation Format

Share Document