Torsional and Translational Vibrations of a Eukaryotic Nucleus, and the Prospect of Vibrational Mechanotransduction and Therapy

2021 ◽  
pp. 104572
Author(s):  
Shaobao Liu ◽  
Haiqian Yang ◽  
Ming Wang ◽  
Jin Tian ◽  
Yuan Hong ◽  
...  
Keyword(s):  
Eukaryotic Nucleus

Localization of DNA in chromatin using ESI and osmium ammine staining

1990 ◽  
Vol 48 (3) ◽  
pp. 116-117
Author(s):  
C.L. Woodcock ◽  
R.A. Horowitz ◽  
D. P. Bazett-Jones ◽  
A.L. Olins
Keyword(s):  
Spectroscopic Imaging ◽  
Energy Losses ◽  
Electron Spectroscopic Imaging ◽  
Feulgen Reaction ◽  
Specific Location ◽  
Eukaryotic Nucleus ◽  
Chromatin Fibers ◽  
Patiria Miniata ◽  
Model Structures

In the eukaryotic nucleus, DNA is packaged into nucleosomes, and the nucleosome chain folded into ‘30nm’ chromatin fibers. A number of different model structures, each with a specific location of nucleosomal and linker DNA have been proposed for the arrangment of nucleosomes within the fiber. We are exploring two strategies for testing the models by localizing DNA within chromatin: electron spectroscopic imaging (ESI) of phosphorus atoms, and osmium ammine (OSAM) staining, a method based on the DNA-specific Feulgen reaction.Sperm were obtained from Patiria miniata (starfish), fixed in 2% GA in 150mM NaCl, 15mM HEPES pH 8.0, and embedded In Lowiciyl K11M at -55C. For OSAM staining, sections 100nm to 150nm thick were treated as described, and stereo pairs recorded at 40,000x and 100KV using a Philips CM10 TEM. (The new osmium ammine-B stain is available from Polysciences Inc). Uranyl-lead (U-Pb) staining was as described. ESI was carried out on unstained, very thin (<30 nm) beveled sections at 80KV using a Zeiss EM902. Images were recorded at 20,000x and 30,000x with median energy losses of 110eV, 120eV and 160eV, and a window of 20eV.

scholarly journals Heterochromatin: Guardian of the Genome

2018 ◽  
Vol 34 (1) ◽  
pp. 265-288 ◽  
Author(s):  
Aniek Janssen ◽  
Serafin U. Colmenares ◽  
Gary H. Karpen
Keyword(s):  
Chromosome Segregation ◽  
Genome Stability ◽  
Constitutive Heterochromatin ◽  
Repetitive Sequences ◽  
Genome Integrity ◽  
Chromatin Domain ◽  
Cellular Processes ◽  
Eukaryotic Nucleus ◽  
And Function ◽  
Heterochromatin Structure

Constitutive heterochromatin is a major component of the eukaryotic nucleus and is essential for the maintenance of genome stability. Highly concentrated at pericentromeric and telomeric domains, heterochromatin is riddled with repetitive sequences and has evolved specific ways to compartmentalize, silence, and repair repeats. The delicate balance between heterochromatin epigenetic maintenance and cellular processes such as mitosis and DNA repair and replication reveals a highly dynamic and plastic chromatin domain that can be perturbed by multiple mechanisms, with far-reaching consequences for genome integrity. Indeed, heterochromatin dysfunction provokes genetic turmoil by inducing aberrant repeat repair, chromosome segregation errors, transposon activation, and replication stress and is strongly implicated in aging and tumorigenesis. Here, we summarize the general principles of heterochromatin structure and function, discuss the importance of its maintenance for genome integrity, and propose that more comprehensive analyses of heterochromatin roles in tumorigenesis will be integral to future innovations in cancer treatment.

Selective forces for the origin of the eukaryotic nucleus

BioEssays ◽  
2006 ◽  
Vol 28 (5) ◽  
pp. 525-533 ◽  
Author(s):  
Purificación López-García ◽  
David Moreira
Keyword(s):  
Eukaryotic Nucleus ◽  
Selective Forces

Origin of the Eukaryotic Nucleus

Science ◽  
1998 ◽  
Vol 280 (5363) ◽  
pp. 499d-499 ◽  
Author(s):  
K. Sandman
Keyword(s):  
Eukaryotic Nucleus

scholarly journals The Plant Nuclear Envelope and Its Role in Gene Transcription

2021 ◽  
Vol 12 ◽  
Author(s):  
Jade Bishop ◽  
Hetty Swan ◽  
Francesco Valente ◽  
Hans-Wilhelm Nützmann
Keyword(s):  
Nuclear Envelope ◽  
Transcriptional Activity ◽  
Focal Point ◽  
Nuclear Periphery ◽  
Research Area ◽  
Nuclear Space ◽  
Future Perspectives ◽  
Eukaryotic Nucleus ◽  
Gene Positioning ◽  
Chromosome Regions

Chromosomes are dynamic entities in the eukaryotic nucleus. During cell development and in response to biotic and abiotic change, individual sections as well as entire chromosomes re-organise and reposition within the nuclear space. A focal point for these processes is the nuclear envelope (NE) providing both barrier and anchor for chromosomal movement. In plants, positioning of chromosome regions and individual genes at the nuclear envelope has been shown to be associated with distinct transcriptional patterns. Here, we will review recent findings on the interplay between transcriptional activity and gene positioning at the nuclear periphery (NP). We will discuss potential mechanisms of transcriptional regulation at the nuclear envelope and outline future perspectives in this research area.

scholarly journals The Nucleolus: A Multiphase Condensate Balancing Ribosome Synthesis and Translational Capacity in Health, Aging and Ribosomopathies

Cells ◽  
2019 ◽  
Vol 8 (8) ◽  
pp. 869 ◽  
Author(s):  
Carl C. Correll ◽  
Jiri Bartek ◽  
Miroslav Dundr
Keyword(s):  
Quality Control ◽  
Proper Function ◽  
Genetic Defects ◽  
Ribosomal Subunits ◽  
Eukaryotic Nucleus ◽  
Evolutionarily Conserved ◽  
Health Aging ◽  
Energy Consuming ◽  
Ribosome Formation ◽  
Liquid Liquid Phase Separation

The nucleolus is the largest membrane-less structure in the eukaryotic nucleus. It is involved in the biogenesis of ribosomes, essential macromolecular machines responsible for synthesizing all proteins required by the cell. The assembly of ribosomes is evolutionarily conserved and is the most energy-consuming cellular process needed for cell growth, proliferation, and homeostasis. Despite the significance of this process, the intricate pathophysiological relationship between the nucleolus and protein synthesis has only recently begun to emerge. Here, we provide perspective on new principles governing nucleolar formation and the resulting multiphase organization driven by liquid-liquid phase separation. With recent advances in the structural analysis of ribosome formation, we highlight the current understanding of the step-wise assembly of pre-ribosomal subunits and the quality control required for proper function. Finally, we address how aging affects ribosome genesis and how genetic defects in ribosome formation cause ribosomopathies, complex diseases with a predisposition to cancer.

Identification of chromosomal actin in insect cells: Structural and functional significance

1994 ◽  
Vol 52 ◽  
pp. 16-17
Author(s):  
Ivo Sauman
Keyword(s):  
Insect Cells ◽  
Polytene Chromosomes ◽  
Follicle Cell ◽  
Nuclear Actin ◽  
Cell Nuclei ◽  
Antibody Staining ◽  
Eukaryotic Nucleus ◽  
Biochemical Studies ◽  
First Time ◽  
Endonuclease Digestion

The non-histone proteins associated with eukaryotic nuclear chromatin are incompletely characterized and their function is poorly understood. Thirty years ago, the presence of actin in the eukaryotic nucleus was reported for first time. Since then, several biochemical studies have identified actin and myosin as significant constituents of isolated nuclear matrix from a variety of cells. The studies cited above and others make a strong case for presence of actin in nuclei, but do not implicate actin as a component of eukaryotic chromosomes.Our examination of cells associated with developing ovarian follicles of lepidopterans confirmed that under routine immunocytochemical conditions, no actin can be detected with anti-actin antibodies in the follicle cell nuclei (Fig. 1a) . However, Fig. 1b demonstrates that endonuclease pretreatment of the same preparation to remove DNA followed by anti-actin antibody staining uncovers the presence of nuclear actin. Moreover, by employing squash preparations of Drosophila salivary glands and the same endonuclease digestion, it is clear that the nuclear actin is directly associated with the polytene chromosomes (Fig. 2a,b).

Dinoflagellates have a eukaryotic nuclear matrix with lamin-like proteins and topoisomerase II

1994 ◽  
Vol 107 (10) ◽  
pp. 2861-2873
Author(s):  
A. Minguez ◽  
S. Franca ◽  
S. Moreno Diaz de la Espina
Keyword(s):  
Nuclear Matrix ◽  
Topoisomerase Ii ◽  
Higher Plants ◽  
Supramolecular Organization ◽  
Free Living ◽  
Eukaryotic Nucleus ◽  
Nucleosomal Dna ◽  
Eukaryotic Chromatin ◽  
Early Acquisition ◽  
Loop Domains

Unicellular Dinoflagellates represent the only eukaryotic Phylum lacking histones and nucleosomes. To investigate whether Dinoflagellates do have a nuclear matrix that would modulate the supramolecular organization of their non-nucleosomal DNA and chromosomes, cells of the free-living unarmored Dinoflagellate Amphidinium carterae were encapsulated in agarose microbeads and submitted to sequential extraction with non-ionic detergents, nucleases and 2 M NaCl. Our results demonstrate that this species has a residual nuclear matrix similar to that of vertebrates and higher plants. The cytoskeleton-nuclear matrix complex of A. carterae shows a relatively intricate polypeptide pattern. Immunoblots with different antibodies reveal several intermediate filament types of proteins, one of which is immunologically related to vertebrate lamins, confirming that these proteins are ancestral members of the IF family, which is highly conserved in eukaryotes. A topoisomerase II homologue has also been identified in the nuclear matrix, suggesting that these structures could play a role in organizing the Dinoflagellate DNA in loop domains. Taken together our results demonstrate that the nuclear matrix is an early acquisition of the eukaryotic nucleus, independent of histones and nucleosomes in such a way that the mechanisms controlling the two levels of organization in eukaryotic chromatin would be molecularly and evolutionarily independent.

scholarly journals The NUF1 gene encodes an essential coiled-coil related protein that is a potential component of the yeast nucleoskeleton.

1992 ◽  
Vol 116 (6) ◽  
pp. 1319-1332 ◽  
Author(s):  
C Mirzayan ◽  
C S Copeland ◽  
M Snyder
Keyword(s):  
Mammalian Cells ◽  
Polyclonal Antibodies ◽  
Coiled Coil ◽  
Immunoblot Analysis ◽  
Expression Library ◽  
Amino Terminal ◽  
Eukaryotic Nucleus ◽  
Nonionic Detergent ◽  
Potential Component ◽  
Carboxy Terminal

In an attempt to identify structural components of the yeast nucleus, subcellular fractions of yeast nuclei were prepared and used as immunogens to generate complex polyclonal antibodies. One such serum was used to screen a yeast genomic lambda gt11 expression library. A clone encoding a gene called NUF1 (for nuclear filament-related) was identified and extensively characterized. Antibodies to NUF1 fusion proteins were generated, and affinity-purified antibodies were used for immunoblot analysis and indirect immunofluorescence localization. The NUF1 protein is 110 kD in molecular mass and localizes to the yeast nucleus in small granular patches. Intranuclear staining is present in cells at all stages of the cell cycle. The NUF1 protein of yeast is tightly associated with the nucleus; it was not removed by extraction of nuclei with nonionic detergent or salt, or treatment with RNAse and DNAse. Sequence analysis of the NUF1 gene predicts a protein 945 amino acids in length that contains three domains: a large 627 residue central domain predicted to form a coiled-coil structure flanked by nonhelical amino-terminal and carboxy-terminal regions. Disruption of the NUF1 gene indicates that it is necessary for yeast cell growth. These results indicate that NUF1 encodes an essential coiled-coil protein within the yeast nucleus; we speculate that NUF1 is a component of the yeast nucleoskeleton. In addition, immunofluorescence results indicate that mammalian cells contain a NUF1-related nuclear protein. These data in conjunction with those in the accompanying manuscript (Yang et al., 1992) lead to the hypothesis that an internal coiled-coil filamentous system may be a general structural component of the eukaryotic nucleus.

Sign in / Sign up

Export Citation Format

Share Document