scholarly journals Organization of Highly Acetylated Chromatin around Sites of Heterogeneous Nuclear RNA Accumulation

1998 ◽  
Vol 9 (9) ◽  
pp. 2491-2507 ◽  
Author(s):  
Michael J. Hendzel ◽  
Michael J. Kruhlak ◽  
David P. Bazett-Jones
Keyword(s):  
Histone Deacetylases ◽  
Active Regions ◽  
Fibroblast Cell ◽  
Cell Nuclei ◽  
Transmission Electron ◽  
Interchromatin Granule ◽  
Nuclear Rna ◽  
Interchromatin Granules ◽  
The Individual ◽  
Rna Accumulation

Histones found within transcriptionally competent and active regions of the genome are highly acetylated. Moreover, these highly acetylated histones have very short half-lives. Thus, both histone acetyltransferases and histone deacetylases must enrich within or near these euchromatic regions of the interphase chromatids. Using an antibody specific for highly acetylated histone H3, we have investigated the organization of transcriptionally active and competent chromatin as well as nuclear histone acetyltransferase and deacetylase activities. We observe an exclusion of highly acetylated chromatin around the periphery of the nucleus and an enrichment near interchromatin granule clusters (IGCs). The highly acetylated chromatin is found in foci that may reflect the organization of highly acetylated chromatin into “chromonema” fibers. Transmission electron microscopy of Indian muntjac fibroblast cell nuclei indicates that the chromatin associated with the periphery of IGCs remains relatively condensed, most commonly found in domains containing chromatin folded beyond 30 nm. Using electron spectroscopic imaging, we demonstrate that IGCs are clusters of ribonucleoprotein particles. The individual granules comprise RNA-rich fibrils or globular regions that fold into individual granules. Quantitative analysis of individual granules indicates that they contain variable amounts of RNA estimated between 1.5 and >10 kb. We propose that interchromatin granules are heterogeneous nuclear RNA-containing particles, some of which may be pre-mRNA generated by nearby transcribed chromatin. An intermediary zone between the IGC and surrounding chromatin is described that contains factors with the potential to provide specificity to the localization of sequences near IGCs.

scholarly journals Visualization of Chromatin in the Yeast Nucleus and Nucleolus Using Hyperosmotic Shock

2021 ◽  
Vol 22 (3) ◽  
pp. 1132
Author(s):  
Nicolas Thelen ◽  
Jean Defourny ◽  
Denis L. J. Lafontaine ◽  
Marc Thiry
Keyword(s):  
Osmotic Shock ◽  
Size Composition ◽  
Yeast Cells ◽  
Exponential Growth Phase ◽  
Cell Nuclei ◽  
Hyperosmotic Shock ◽  
Christmas Trees ◽  
Transmission Electron ◽  
Active Transcription ◽  
Decondensed Chromatin

Unlike in most eukaryotic cells, the genetic information of budding yeast in the exponential growth phase is only present in the form of decondensed chromatin, a configuration that does not allow its visualization in cell nuclei conventionally prepared for transmission electron microscopy. In this work, we studied the distribution of chromatin and its relationships to the nucleolus using different cytochemical and immunocytological approaches applied to yeast cells subjected to hyperosmotic shock. Our results show that osmotic shock induces the formation of heterochromatin patches in the nucleoplasm and intranucleolar regions of the yeast nucleus. In the nucleolus, we further revealed the presence of osmotic shock-resistant DNA in the fibrillar cords which, in places, take on a pinnate appearance reminiscent of ribosomal genes in active transcription as observed after molecular spreading (“Christmas trees”). We also identified chromatin-associated granules whose size, composition and behaviour after osmotic shock are reminiscent of that of mammalian perichromatin granules. Altogether, these data reveal that it is possible to visualize heterochromatin in yeast and suggest that the yeast nucleus displays a less-effective compartmentalized organization than that of mammals.

Microstructure of SrTiO3 Thin Films as Single Layer and Incorporated in Yba2Cu3O7-x/SrTiO3 Multilayers

1995 ◽  
Vol 401 ◽  
Author(s):  
L. Ryen ◽  
E. Olssoni ◽  
L. D. Madsen ◽  
C. N. L. Johnson ◽  
X. Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Lattice Mismatch ◽  
Single Layer ◽  
Transmission Electron ◽  
Tilt Boundaries ◽  
Interfacial Dislocations ◽  
The Individual ◽  
Film Substrate

AbstractEpitaxial single layer (001) SrTiO3 films and an epitaxial Yba2Cu3O7-x/SrTiO3 multilayer were dc and rf sputtered on (110)rhombohedral LaAIO3 substrates. The microstructure of the films was characterised using transmission electron microscopy. The single layer SrTiO3 films exhibited different columnar morphologies. The column boundaries were due to the lattice mismatch between film and substrate. The boundaries were associated with interfacial dislocations at the film/substrate interface, where the dislocations relaxed the strain in the a, b plane. The columns consisted of individual subgrains. These subgrains were misoriented with respect to each other, with different in-plane orientations and different tilts of the (001) planes. The subgrain boundaries were antiphase or tilt boundaries.The individual layers of the Yba2Cu3O7-x/SrTiO3 multilayer were relatively uniform. A distortion of the SrTiO3 unit cell of 0.9% in the ‘001’ direction and a Sr/Ti ratio of 0.62±0.04 was observed, both in correspondence with the single layer SrTiO3 films. Areas with different tilt of the (001)-planes were also present, within each individual SrTiO3 layer.

scholarly journals Sperm ultrastructure of Pochazia shantungensis (Chou & Lu) and Ricania speculum (Walker) (Hemiptera, Ricaniidae) with phylogenetic implications

ZooKeys ◽  
2019 ◽  
Vol 880 ◽  
pp. 43-59
Author(s):  
Zhen Jiang ◽  
Jianing Liu ◽  
Daozheng Qin
Keyword(s):  
Neck Region ◽  
Mature Spermatozoon ◽  
Current Evidence ◽  
Sperm Ultrastructure ◽  
Transmission Electron ◽  
Phylogenetic Implications ◽  
Dense Substance ◽  
The Individual ◽  
Relationship Of ◽  
Centriole Adjunct

The sperm ultrastructure of two ricaniid species, Pochazia shantungensis (Chou & Lu) and Ricania speculum (Walker), was investigated using light and transmission electron microscopy. Both species have monoflagellate sperm, the shape and ultrastructure of the mature spermatozoon of these two species are similar in morphology, and 128 spermatozoa are organized into sperm bundles with their heads embedded in a homogenous matrix forming the spermatodesmata. The individual sperm is filiform and includes the head, neck and flagellum. The head is needle-like, with a bilayer acrosome and an inferior elongated nucleus which is formed of homogeneously compact and electron-dense chromatin. The neck region is indistinct and is comprised of the centriole and centriole adjunct with a homogeneous dense substance. The long flagellum has the typical 9 + 9 + 2 axoneme microtubule pattern and two symmetrical mitochondrial derivatives with an orderly array of cristae flanking both sides, and a pair of well-developed fishhook-shaped accessory bodies. Current evidence shows that ricaniid species have D-shaped mitochondrial derivatives in cross-section and a serrated electron-dense region. The phylogenetic relationship of Fulgoroidea with other superfamilies in Auchenorrhyncha is briefly discussed.

Changes in liver-specific compared to common gene transcription during primary culture of mouse hepatocytes

1983 ◽  
Vol 3 (9) ◽  
pp. 1552-1561
Author(s):  
D F Clayton ◽  
J E Darnell
Keyword(s):  
Gene Transcription ◽  
Primary Cultures ◽  
Specific Gene ◽  
Cell Nuclei ◽  
Gradual Loss ◽  
Nuclear Rna ◽  
Transcriptional Effect ◽  
Specific Mrnas ◽  
Mouse Hepatocytes ◽  
Specific Mrna

Liver-specific mRNA sequences were examined in primary cultures of mouse hepatocytes. After cell disaggregation by collagenase treatment and for at least 24 h in culture, little change in liver-specific mRNA concentrations was noted. Gradually over a period of 140 h, liver-specific mRNAs declined. In contrast, transcriptional assays in which liver cell nuclei were used to produce 32P-labeled nuclear RNA showed that liver-specific gene transcription was greatly diminished within 24 h, while polymerase II transcription of "common" genes and transcription of tRNA and rRNA did not decline. Thus, a prompt differential transcriptional effect seems to underlie the gradual loss of tissue specificity of the primary cultures.

scholarly journals Ahmed Hassan Zewail. 26 February 1946—2 August 2016

2019 ◽  
Vol 68 ◽  
pp. 431-453
Author(s):  
John Meurig Thomas
Keyword(s):  
Electron Microscopy ◽  
Gas Phase ◽  
Ultrafast Lasers ◽  
Atomic Level ◽  
Women In Science ◽  
President Obama ◽  
Structure And Dynamics ◽  
Transmission Electron ◽  
The Individual ◽  
Gas Phase Electron Diffraction

Ahmed Zewail will forever be remembered for three main reasons: first, he was the individual who first demonstrated that the structure and dynamics of atoms in the transition state of chemical reactions could be determined through the judicious use of ultrafast lasers, in a field that he pioneered, for which he coined, called femtochemistry; second, he transformed both gas phase electron diffraction and transmission electron microscopy by improving their temporal resolution some 10 orders of magnitude, while simultaneously retaining the spatial resolution of electron microscopy at the atomic level; and third, he was the first US Science Envoy to the Middle East (appointed by President Obama). To all who knew him, he was a warm-hearted, life-enhancing person endowed with exceptional technical virtuosity as an experimentalist and a profound thinker, whose prodigality of output was also exceptional. He exhibited remarkable skills as an enterprising fundraiser in his determination to establish the Zewail City of Science and Technology on the outskirts of his beloved Cairo. He also influenced greatly the L'Oréal–UNESCO scheme for awarding prizes to women in science.

scholarly journals Dynamic deformability of individual PbSe nanocrystals during superlattice phase transitions

2019 ◽  
Vol 5 (6) ◽  
pp. eaaw5623 ◽  
Author(s):  
Yu Wang ◽  
Xinxing Peng ◽  
Alex Abelson ◽  
Penghao Xiao ◽  
Caroline Qian ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Morphological Changes ◽  
Semiconductor Nanocrystals ◽  
Structural Defects ◽  
Dipole Interactions ◽  
Ligand Displacement ◽  
Transmission Electron ◽  
Resolution Imaging ◽  
Phase Transmission ◽  
The Individual

The behavior of individual nanocrystals during superlattice phase transitions can profoundly affect the structural perfection and electronic properties of the resulting superlattices. However, details of nanocrystal morphological changes during superlattice phase transitions are largely unknown due to the lack of direct observation. Here, we report the dynamic deformability of PbSe semiconductor nanocrystals during superlattice phase transitions that are driven by ligand displacement. Real-time high-resolution imaging with liquid-phase transmission electron microscopy reveals that following ligand removal, the individual PbSe nanocrystals experience drastic directional shape deformation when the spacing between nanocrystals reaches 2 to 4 nm. The deformation can be completely recovered when two nanocrystals move apart or it can be retained when they attach. The large deformation, which is responsible for the structural defects in the epitaxially fused nanocrystal superlattice, may arise from internanocrystal dipole–dipole interactions.

scholarly journals The loss of rapidly labelled ribonucleic acid from isolated HeLa cell nuclei

1969 ◽  
Vol 112 (1) ◽  
pp. 71-79 ◽  
Author(s):  
J. W. Watts
Keyword(s):  
Hela Cell ◽  
Incubation Medium ◽  
Sedimentation Coefficient ◽  
Cell Nuclei ◽  
Isolated Nuclei ◽  
Bivalent Cations ◽  
Low Concentrations ◽  
Nuclear Rna ◽  
And Diffusion

1. The loss of nucleic acids and protein from isolated HeLa-cell nuclei was studied. During 4hr. incubation at 37° DNA was conserved, but appreciable amounts of RNA and protein were lost. 2. Two classes of nuclear RNA were distinguished: at least 75% of the RNA was lost from the nuclei relatively slowly through degradation to acid-soluble fragments; the rest of the RNA was lost much more rapidly, not only through degradation to acid-soluble fragments but also through diffusion of RNA out of the nuclei into the incubation medium. 3. The RNA that was preferentially lost was the fraction of nuclear RNA that was rapidly labelled when intact HeLa cells were grown in a medium containing radioactive precursors of RNA. 4. The RNA appearing in the incubation medium was apparently partially degraded and had a sedimentation coefficient of about that of transfer RNA. 5. Both the degradation of RNA and the loss of RNA from the nuclei were sensitive to bivalent cations. Low concentrations of Mg2+ and Mn2+ greatly increased the rate of degradation of the rapidly labelled RNA to acid-soluble fragments, and produced a corresponding decrease in the amount of RNA diffusing into the medium. At higher concentrations they suppressed both degradation and diffusion of RNA. The cations Ca2+, Cu2+, Zn2+ and Ni2+ all progressively inhibited both forms of loss of RNA. 6. Salts of univalent cations produced appreciable effects only at ionic strengths of about 0·2, when degradation to acid-soluble fragments was preferentially inhibited. 7. Both ADP and ATP inhibited loss of RNA at about 30mm. 8. It was concluded that the diffusion of rapidly labelled RNA out of the isolated nuclei was not related to the movement of RNA from nucleus to cytoplasm in vivo, but reflected the ease with which the rapidly labelled RNA detached from the chromatin and the permeability of the membranes of isolated nuclei.

49 INTRA-GENUS CLONED EMBRYOS PRODUCTION AND PREGNANCIES DERIVED FROM LEOPARD CAT NUCLEI AND DOMESTIC CAT ENUCLEATED EGGS

2006 ◽  
Vol 18 (2) ◽  
pp. 133 ◽  
Author(s):  
I. K. Kong ◽  
H. S. Lee ◽  
N. H. Kim ◽  
L. H. Kim ◽  
H. D. Shin ◽  
...  
Keyword(s):  
Somatic Cell ◽  
Nuclear Genome ◽  
Fibroblast Cell ◽  
Domestic Cat ◽  
Developmental Competence ◽  
Cell Nuclei ◽  
Reconstructed Embryos ◽  
Significant Difference ◽  
Leopard Cat

The leopard cat (Prionailurus bengalensis), a member of the felidae family, is currently listed as threatened by the Ministry of Environment in South Korea. In exotic or endangered species, the lack of oocytes and recipients precludes the use of traditional somatic cell nuclear transfer (NT), and an approach such as intragenus NT may be the only alternative for producing embryos and offspring. In the present study, we used the leopard cat (LC) as a somatic cell donor to evaluate the in vivo developmental competence, after transfer into domestic cat recipients, of cloned embryos produced by the fusion of LC fibroblast cell nuclei with domestic cat cytoplasts. A total of 412 enucleated domestic cat oocytes were reconstructed with either male (Treatment A) or female (Treatment B) adult LC fibroblasts. There was no significant difference in fusion rate (60.4 vs. 56.9%) between Treatment A and B. Of the fused couplets, the cleavage and blastocyst developmental rate in Treatment A were greater than those in Treatment B (69.5 vs. 60.9%; 8.3 vs. 7.8%; P < 0.05). In treatment A, in vivo developmental studies at 30-45 days postimplantation demonstrated 4.8% (21/435) of reconstructed embryos (n = 435) had entered into the uterine lining of recipients, but only 1.4% (6/435) formed fetuses. However, all of the reconstructed embryos failed to develop to term (65 days). Microsatellite analyses confirmed that the nuclear genome of the cloned fetuses were LC in origin.

47 DIFFERENTIAL DEVELOPMENTAL ABILITY OF EMBRYOS CLONED FROM TISSUE-SPECIFIC STEM CELLS

2007 ◽  
Vol 19 (1) ◽  
pp. 142
Author(s):  
K. Inoue ◽  
N. Ogonuki ◽  
H. Miki ◽  
S. Noda ◽  
S. Inoue ◽  
...  
Keyword(s):  
Stem Cells ◽  
Nuclear Transfer ◽  
Embryonic Stem ◽  
Donor Cell ◽  
Fibroblast Cell ◽  
High Rate ◽  
Full Potential ◽  
Cell Nuclei ◽  
Cell Stage

Although cloning animals by somatic cell nuclear transfer is generally an inefficient process, use of appropriate donor cell types may improve the cloning outcome significantly. Among the donor cells tested so far, mouse embryonic stem cells have given the best efficiency in terms of the development of reconstructed embryos into offspring. In this study, we examined whether 2 in vitro-produced pluripotent stem cells—neural stem cells (NSCs) and mesenchymal stem cells (MSCs)—could be better nuclear donors than other differentiated cells. Embryos were reconstructed by transfer of nuclei from NSCs or MSCs with full potential for differentiation in vitro. Most (76%) of the 2-cell NCS embryos developed to the 4-cell stage; 43% implanted and 1.6% developed to term after transfer to pseudopregnant recipients. These rates were very similar to those of embryos cloned from fibroblast cell nuclei. Interestingly, in the patterns of zygotic gene expression, NSC embryos were more similar to in vitro-fertilized embryos than fibroblast cloned embryos. By contrast, embryos reconstructed using MSC nuclei showed lower developmental ability and no implantation was obtained after embryo transfer. Chromosomal analysis of the donor MSCs revealed very high frequencies of monosomy and trisomy, which might have caused the very poor post-implantation development of embryos following nuclear transfer. Thus, in vitro-produced pluripotent cells can serve as donors of nuclei for cloning mice, but may be prone to chromosomal aberrations leading to a high rate of cloned embryo death.

51 DEVELOPMENT OF EQUINE CLONED EMBRYOS DERIVED FROM IN VITRO-MATURED OOCYTES RECEIVING ADULT DERMAL FIBROBLAST CELL NUCLEI

2009 ◽  
Vol 21 (1) ◽  
pp. 125
Author(s):  
M. Skrzyszowska ◽  
M. Samiec ◽  
W. Mlodawska ◽  
J. Kochan ◽  
A. Okolski ◽  
...  
Keyword(s):  
Dermal Fibroblast ◽  
Fibroblast Cell ◽  
Vero Cells ◽  
Contact Inhibition ◽  
Fibroblast Cells ◽  
Cell Nuclei ◽  
Metaphase Chromosomes ◽  
Condensed Chromosome ◽  
Donor Cells

The purpose of our study was to determine the in vitro developmental competences of equine NT embryos reconstructed with adult dermal fibroblast cells. Frozen/thawed fibroblast cells, whose mitotic cycle had been synchronized at G1/G0 stages through a contact inhibition of their migration and proliferative activity under total confluency, were used as a source of nuclear donor cells in the somatic cell cloning procedure. In vitro-matured oocytes were used as recipient cells for fibroblast cell nuclei. The compact cumulus–oocyte complexes (cpCOCs) were collected from abattoir-derived mare ovaries and selected for in vitro maturation. The cpCOCs were cultured in TC-199 medium supplemented with 5 mU mL–1 follicle-stimulating hormone (FSH), 10% fetal bovine serum (FBS) and 75 μg mL–1 kanamycin monosulfate (kanamycin A) for 30 h at 38.2°C in a 100% water-saturated atmosphere of 5% CO2 and 95% air. Cumulus-denuded in vitro-matured oocytes were incubated in the maturation medium supplemented with 0.4 μg mL–1 demecolcine for 40 min. The treated oocytes were subsequently transferred into TC-199 medium containing 4 mg mL–1 BSA-V and 5 μg mL–1 cytochalasin B. Metaphase chromosomes, which had been allocated into the chemically-induced protrusion of the plasma membrane, were removed microsurgically. The chemically-assisted enucleation was accomplished by gently aspirating the ooplasmic cone, which contained the condensed chromosome mass, with the aid of a beveled micropipette. The single nuclear donor cells were inserted into perivitelline space of previously enucleated oocytes. Fibroblast cell-ooplast couplets were fused with two consecutive DC pulses of 2.4 kV cm–1 for 30 μs. After a 1.5-h delay, nuclear transfer-derived oocytes were chemically activated by exposure to 5 μm L–1 calcium ionomycin for 5 to 7 min, followed by their incubation in B2 medium with addition of 2 mm L–1 6-dimethylaminopurine (6-DMAP) for 4 h. Reconstructed embryos were in vitro cultured in B2 medium for 2 days. Afterwards, cleaved embryos were co-cultured with Vero cells in B2 medium supplemented with 10% FBS for 5 to 6 days up to morula/blastocyst stages. From among 88 in vitro cultured cpCOCs, 55 (62.5%) acquired meiotic nuclear and cytoplasmic maturity state after reaching the Metaphase II stage. A total of 55 enucleated oocytes underwent reconstruction and 44/55 (80.0%) were successfully fused with nuclear donor cells. Out of 44 cultured NT embryos, 21 (47.7%) were cleaved. The frequencies of cloned embryos that reached the morula and blastocyst stages were 6/44 (13.6%) and 3/44 (6.8%), respectively. In conclusion, the cell nuclei of in vitro cultured adult dermal fibroblast cells, which had undergone the contact inhibition, were able to direct the preimplantation development of equine cloned embryos to morula and blastocyst stages. This work was supported by the Scientific Net of Animal Reproduction Biotechnology.

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